JP3507044B2 - Forward illumination device and reflection type liquid crystal display device having the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used by being arranged between an object to be illuminated and an observer, irradiating the object to be illuminated with light, and allowing an observer to visually recognize reflected light from the object to be illuminated. The present invention relates to a front lighting device configured to transmit the reflected light as described above, and a reflective liquid crystal display device including the front lighting device.

[0002]

2. Description of the Related Art A liquid crystal display device is a CRT (Cathode Ray T
ube), PDP (Plasma Display Panel), or EL (E
Unlike other displays such as lectro Luminescence), the liquid crystal itself does not emit light, but characters and images are displayed by adjusting the amount of light transmitted from a specific light source.

A conventional liquid crystal display device (hereinafter, LCD: Liqu
The “id Crystal Display” can be roughly classified into a transmissive LCD and a reflective LCD. Transmission type LC
In D, a surface emitting light source such as a fluorescent tube or EL is disposed as a light source (backlight) on the back surface of the liquid crystal cell.

On the other hand, the reflective LCD has the advantages that it does not require a backlight and consumes less power because it uses ambient light for display. Further, in a very bright place such as exposed to direct sunlight, the display of the emissive display and the transmissive LCD becomes almost invisible, while the display of the reflective LCD becomes clearer. Therefore, the reflection type L
The CD is applied to mobile information terminals and mobile computers, which have been in increasing demand in recent years.

However, the reflective LCD has the following problems. That is, since the reflective LCD uses ambient light, the display brightness is highly dependent on the surrounding environment, and the display may not be recognized at all in the darkness such as at night. In particular, in the reflective LCD using a color filter for colorization or the reflective LCD using a polarizing plate, the above-mentioned problem is large, and auxiliary lighting is necessary in case sufficient ambient light cannot be obtained. Become.

However, the reflective LCD has a reflector installed on the back surface of the liquid crystal cell, and cannot use a backlight like the transmissive LCD. A device called a semi-transmissive LCD using a half mirror as a reflector has also been proposed, but its display characteristics are halfway between a transmissive type and a reflective type and are considered to be difficult to put into practical use.

Therefore, a front light system for arranging it in front of a liquid crystal cell has been conventionally proposed as auxiliary illumination for a reflective LCD when the surroundings are dark. This front light system generally comprises a light guide and a light source arranged on a side surface of the light guide. The light source light incident from the side surface of the light guide body travels inside the light guide body, is reflected by the shape formed on the surface of the light guide body, and is emitted to the liquid crystal cell side. The emitted light is dimmed according to the display information while passing through the liquid crystal cell, and is reflected by the reflecting plate arranged on the back side of the liquid crystal cell, and again passes through the light guide body to the viewer side. Is emitted. This allows the observer to recognize the display even when the amount of ambient light is insufficient.

Such a front light is disclosed, for example, in Japanese Patent Laid-Open No. 5-158034, SID DIGEST P.375 (1).
995) and the like.

[0009]

[Problems to be Solved by the Invention] Here, SID DIGEST
The operation principle of the front light system disclosed in P.375 (1995) will be briefly described with reference to FIG. In the above front light system, the flat portion 10
One side surface of the light guide body 104 having the interface 101 formed of 1a and the inclined portion 101b is defined as an incident surface 105 on which light from the light source 106 is incident. That is, the light source 10
6 is arranged at a position facing the incident surface 105 of the light guide 104.

Of the light that has entered the light guide 104 from the light source 106 through the incident surface 105, some of the light goes straight, and some of the light enters the interface 101.1 between the light guide 104 and its surrounding medium.
It is incident on 08. At this time, assuming that the surrounding medium of the light guide body 104 is air and the refractive index of the light guide body 104 is about 1.5, the interface 1 is calculated from Snell's law (Equation 1).
It can be seen that the light whose incident angle with respect to 01 · 108 is about 41.8 ° or more is totally reflected at the interfaces 101 · 108.

N1.sin.theta.1 = n2.sin.theta.2.theta.c = arcsin (n2 / n1) (Equation 1) where n1 is the refractive index of the first medium (here, the light guide 104), and n2 is the second Refractive index of the medium (here air),
θ 1 is the incident angle from the light guide 104 to the interface 101, θ 2 is the exit angle from the interface 101 to the second medium, θ c is the critical angle,
Is.

In the light incident on the interfaces 101 and 108,
The light totally reflected by the inclined portion 101b, which is a reflection surface, and the interface 1
After being totally reflected at 08, the light reflected by the inclined portion 101 b of the interface 101 enters the liquid crystal cell 110. Liquid crystal cell 11
The light that has entered 0 is modulated by a liquid crystal layer (not shown), is then reflected by a reflection plate 111 provided on the back surface of the liquid crystal cell 110, and is incident on the light guide 104 again to enter the flat portion 10.
The light passes through 1a and is emitted to the observer 109 side.

The light that has passed from the light source 106 through the incident surface 105 and is incident on the flat portion 101a instead of the inclined portion 101b is between the interface 101 and the interface 108.
It propagates while repeating total reflection until it reaches b. The area of the inclined portion 101b viewed from the observer 109 side is
The area is sufficiently smaller than the area of the flat portion 101a.

The above conventional front light system has the following problems.

(1) As shown in FIG. 52, the light which cannot reach the inclined portion 101b even if the total reflection is repeated, and the incident surface 1
The light that is incident substantially perpendicularly to the beam 05 is emitted from the surface 107 facing the incident surface 105 to the outside of the light guide 104.
4 and cannot be used for display. That is, the utilization efficiency of light is poor.

(2) The shape of the interface 101 composed of the slanted portion 101b and the flat portion 101a is similar to the shape in which the apex of the prism sheet is flattened. As shown in FIG. It is likely to be reflected to the observer 109 side, which leads to deterioration of display quality.

These problems are common to most of the conventional front light systems, and it is desired to improve the utilization efficiency of the light from the light source.

The present invention has been made in view of the above problems, and an object thereof is to improve the utilization efficiency of light from a light source and to provide a uniform and brighter illumination to an illuminated object. An object is to provide an illuminating device and a reflective liquid crystal display device using the front illuminating device.

[0019]

In order to solve the above problems, a front lighting device according to the present invention is provided with a light source and a light guide, and is used by being arranged in front of an object to be illuminated. In the above, the light guide member faces the incident surface on which light is incident from the light source, the first emission surface on which light is emitted toward the object to be illuminated, and the first emission surface. The second emission surface is provided with a second emission surface that emits the reflected light, and the second emission surface is a flat portion that mainly transmits the reflected light from the object to be illuminated and is constant in the same direction with respect to the flat portion. And has a shape in which inclined portions that mainly reflect the light from the light source toward the first emission surface are alternately arranged, and further, the first emission surface and the second emission surface are arranged. It is characterized in that the distance from each of the inclined portions on the exit surface of is substantially uniform.

According to the above structure, in the light guide, the distance from the inclined portion to the first emission surface, that is, the distance to the object to be illuminated is constant. Therefore, the front illumination device of the present invention can uniformly illuminate an object to be illuminated, and can realize bright and even high-quality display even when sufficient ambient light cannot be obtained. In addition,
The above-mentioned light guide body refers to one in which a first light guide body and a second light guide body in [Second Embodiment] described later are integrally formed.

In order to solve the above-mentioned problems, another front illumination device according to the present invention has a light source and a light guide body arranged in front of an object to be illuminated. An incident surface on which light from the light source is incident, a first emission surface that emits light toward the illuminated object, and a reflected light from the illuminated object that faces the first emission surface. And a second emitting surface that is provided to the second emitting surface, and an inclined portion that mainly reflects the light from the light source toward the first emitting surface, and a second emitting surface that mainly emits light from the illuminated object. It is characterized in that flat portions which transmit reflected light are alternately formed, and a line connecting the sloped portions and the portions where the flat portions are in contact with each other in a ridge shape is parallel to the first emission surface.

According to the above construction, in the light guide, the line connecting the portions where the inclined portion and the flat portion contact in a ridge shape is parallel to the first emission surface. for that reason,
The front lighting device of the present invention is capable of uniformly illuminating an object to be illuminated, and even when sufficient ambient light cannot be obtained,
It is possible to realize a bright and even high-quality display.

In addition to the above structure, the front lighting device according to the present invention further suppresses the reflection of light from the second emission surface on the first emission surface by the first emission surface. It is characterized by having optical means.

According to the above arrangement, since the optical means is further provided, it is possible to suppress the generation of reflected light generated by the incident light from the inclined portion being reflected by the second surface.
Therefore, it is possible to prevent interference or diffraction between the image on the inclined portion acting as the minute light source portion and the reflected image due to the reflected light. Therefore, it is possible to prevent the unevenness of the luminance distribution on the display observed on the observer side (the second emission surface) and the occurrence of the rainbow color spectrum.

The front illumination device according to the present invention is characterized in that, in addition to the above configuration, the optical means is an antireflection film.

According to the above construction, since the commercially available antireflection film (antireflection film) can be used as it is as the optical means, an increase in the manufacturing cost of the front lighting device can be suppressed. Therefore, an inexpensive front lighting device can be provided.

In the front lighting device according to the present invention, in addition to the above structure, the antireflection film is adhered to the light guide body with an adhesive having a refractive index substantially equal to that of the light guide body. It is characterized by being.

According to the above construction, since the antireflection film is adhered with the adhesive having a refractive index almost equal to that of the light guide, the light input / output conditions in the light guide are substantially unchanged. The antireflection effect can be improved.

In order to solve the above-mentioned problems, the reflection type liquid crystal display device according to the present invention is characterized in that the front illumination device having the above-mentioned structure is arranged on the front surface.

According to the above construction, the front lighting device is arranged in front of the reflection type liquid crystal display device. Therefore, when there is a sufficient amount of ambient light such as outdoors in the daytime, the front lighting device is arranged. On the other hand, the front lighting device can be turned on when a sufficient amount of ambient light cannot be obtained while the light is turned off. As a result, it is possible to provide a reflective liquid crystal display device that can always realize bright and high-quality display regardless of the surrounding environment.

The reflection type liquid crystal display device according to the present invention is characterized in that, in addition to the above configuration, the front illumination device is detachable.

According to the above structure, when the reflection type liquid crystal display device is used with the front illumination device turned on, the reflection type liquid crystal display device is placed in the front, and when the front illumination device is not required,
The reflective liquid crystal display device can be removed so that only the reflective liquid crystal display device is formed. This makes it possible to provide a reflective liquid crystal display device that can always realize a bright display without obstructing the incidence of ambient light by the front illumination device when the front illumination device is not required.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] The following will describe one embodiment of the present invention with reference to FIGS. 1 to 7.

The reflective LCD according to this embodiment is shown in FIG.
As shown in, a reflective liquid crystal cell 10 (reflective liquid crystal element)
The front light 20 (front illumination device) is provided on the front surface of the.

The front light 20 mainly comprises a light source 26.
And a light guide 24. Light source 26
Is a linear light source such as a fluorescent tube, and is arranged along the side surface (incident surface 25) of the light guide 24. The light guide 24 is
The interface 28 (first emission surface) on the liquid crystal cell 10 side is formed flat. On the other hand, in the light guide 24, the interface 28
The interface 23 (second emission surface) that faces the flat portion 21 and the flat portion 21 that are formed parallel or substantially parallel to the interface 28.
The inclined portions 22 that are inclined at a constant angle in the same direction with respect to 1 are formed alternately. That is, as is apparent from FIG. 1, the light guide body 24 is formed in a stepwise shape that lowers as it goes away from the light source 26 in a cross section whose normal line is the longitudinal direction of the light source 26.

The inclined portion 22 mainly acts as a surface for reflecting the light from the light source 26 toward the interface 28. On the other hand, the flat portion 22 mainly acts as a surface for transmitting the reflected light to the observer side when the illumination light from the front light 20 returns from the liquid crystal cell 10 as the reflected light.

Here, the shape of the light guide 24 will be described in more detail with reference to FIGS. 2 (a) to 2 (c). 2A is a plan view of the light guide 24 as seen from above in the normal direction of the flat portion 21, and FIG. 2B is a side view of the light guide 24 as seen in the direction of normal to the incident surface 25. 2C is a cross-sectional view of the light guide 24 taken along a plane perpendicular to both the incident surface 25 and the interface 28.

The light guide 24 is made of, for example, PMMA (polymethy).
It can be formed by injection molding using lmetacrylate) or the like. The light guide 24 according to this embodiment has a width W = 1.
10.0 mm, length L = 80.0 mm, incident surface 25 portion thickness h1 = 2.0 mm, flat portion 21 width w1 = 1.9.
mm. Also, the step h2 of the inclined portion 22 = 50 .mu.m,
By setting the inclination angle α of the inclined portion 22 with respect to the flat portion 21 to be 30 °, the width w2 of the inclined portion 22 is about 87 μm.

The front light 20 has the following advantages because the light guide 24 is formed in a stepped shape. First, as shown in FIG. 2B, when viewed from the direction normal to the incident surface 25, if the flat portion 21 is formed completely parallel to the interface 28, the flat portion 21 is visually recognized. Instead, only the inclined portion 22 is visually recognized. That is, the sum of the projections of the inclined portion 22 on the incident surface 25 is equal to the incident surface 25.

In such a case, of the light source light incident from the incident surface 25, all the components perpendicular to the incident surface 25 are directly incident on the inclined portion 22 and reflected toward the interface 28. As a result, the problem that a large amount of light is emitted to the outside of the light guide from the surface facing the incident surface, unlike the above-described conventional front light system, does not occur. That is, since the front light 20 is provided with the step-shaped light guide 24, the light utilization efficiency is significantly improved as compared with the conventional configuration.

Next, the structure of the liquid crystal cell 10 and its manufacturing method will be described.

As shown in FIG. 1, the liquid crystal cell 10 basically has a structure in which a pair of electrode substrates 11a and 11b sandwich a liquid crystal layer 12 therebetween. In the electrode substrate 11a, a transparent electrode 15a (scanning line) is provided on a glass substrate 14a having a light transmitting property, and a liquid crystal alignment film 16a is formed so as to cover the transparent electrode 15a.

The glass substrate 14a is realized, for example, by a glass substrate (product name: 7059) manufactured by Corning. The transparent electrode 15a is made of, for example, ITO (Indium Tin Oxid).
Use e) as a material. The liquid crystal alignment film 16a is, for example, an alignment film material manufactured by Japan Synthetic Rubber Co., Ltd. (trade name: AL-4552).
Is applied by a spin coater on the glass substrate 14a on which the transparent electrode 15a is formed, and a rubbing process is performed as an alignment process.

Similarly to the electrode substrate 11a, the electrode substrate 11b is also made by sequentially laminating the glass substrate 14b, the transparent electrode 15b, and the liquid crystal alignment film 16b.
An insulating film or the like may be formed on the electrode substrates 11a and 11b, if necessary.

The electrode substrates 11a and 11b are the liquid crystal alignment film 1
6a and 16b are arranged so as to face each other, and the rubbing processing directions are parallel and opposite (so-called anti-parallel), and they are bonded using an adhesive. At this time,
Glass electrode spacers (not shown) having a particle diameter of 4.5 μm are previously dispersed between the electrode substrates 11a and 11b, so that voids are formed at uniform intervals.

The liquid crystal layer 12 is formed by introducing liquid crystal into the voids by vacuum deaeration. As the material of the liquid crystal layer 12, for example, a liquid crystal material manufactured by Merck Ltd. (trade name: ZLI-3926) can be used. The Δn of this liquid crystal material is 0.2030. However, the liquid crystal material is not limited to this, and various liquid crystals can be used.

Further, on the outer surface of the glass substrate 14b, a hairline-processed aluminum plate is used as the reflector 17.
For example, a polarizing plate 18 is attached to the outer surface of the glass substrate 14a while the polarizing axis is set so as to form 45 ° with the alignment direction of the liquid crystal of the liquid crystal layer 12 while being adhered by an epoxy adhesive.

Through the above steps, the reflection type liquid crystal cell 10
Is manufactured. By combining the liquid crystal cell 10 with the front light 20 as described below, a reflective LCD with a front illumination device is manufactured. First, the liquid crystal cell 1
The light guide 24 is laminated on the zero polarizing plate 18. It should be noted that spacers (not shown) having a particle size of 50 μm are previously dispersed between the polarizing plate 18 of the liquid crystal cell 10 and the light guide 24, so that a uniform thickness approximately equal to the particle size of the spacer is obtained. A void 29 is formed. That is, the interface 28 of the light guide 24 optically corresponds to the interface between the PMMA and the air layer. Since the gap 29 has a thickness of about 100 times the wavelength of light, the occurrence of interference or the like due to the gap 29 is suppressed.

Next, a fluorescent tube is installed as a light source 26 so as to face the entrance surface 25 of the light guide 24, and the light source 26 and the entrance surface 25 are surrounded by a reflecting mirror 27 (light collecting means). Reflector 2
7 focuses the light from the light source 26 only on the incident surface 25. As the reflecting mirror 27, for example, aluminum tape or the like can be used. Through the above steps, the reflective LCD including the front light 20 as auxiliary illumination is completed.

This reflection type LCD is used in a lighting mode in which the front light 20 is turned on when ambient light is insufficient, and when sufficient ambient light is obtained, the front light 2 is used.
It can be used in reflection mode with 0 turned off.

Here, the operation principle of the front light 20 will be described with reference to FIGS. 3 (a) to 3 (c).

As described above, the light guide 24 has the incident surface 2
The sum of the projections of the inclined portion 22 on 5 is equal to the incident surface 25. Therefore, of the incident light from the light source 26, the incident surface 2
As shown in FIG. 3 (a), the component perpendicular to 5 is the inclined portion 2
2 and is output from the interface 28 toward the liquid crystal cell 10 (not shown in FIG. 3A).

Further, as shown in FIG. 3B, the light source 26
Of the incident light from, the component that first enters the interface 23 is
There are two types according to the behavior in the light guide 24. One is the inclined portion 22 like the light 31a shown in FIG.
Is directly incident on and reflected by the output light 31 to the liquid crystal cell 10.
It is the light which becomes b. The second is the light 32 shown in FIG.
As indicated by a, the light propagates in the light guide 24 while being totally reflected between the flat portion 21 and the interface 28, and finally reaches the inclined portion 22 and is reflected to become the output light 32b.

As shown in FIG. 3C, the light source 26
Of the incident light from, the component that first enters the interface 28 is
The light propagates in the light guide 24 while being totally reflected between the interface 28 and the flat portion 21 of the interface 23, finally reaches the inclined portion 22 and is reflected, and is output from the interface 28 toward the liquid crystal cell 10. .

As can be seen from the above description, almost all the components of the incident light from the light source 26 to the light guide 24 are reflected by the inclined portion 22 and go out to the liquid crystal cell 10 through the interface 28. That is, the front light 20 of the present embodiment
Since the light guide 24 having the stepwise interface 23 is provided, the loss of light from the light source 26 is extremely small and the utilization efficiency of the light from the light source is improved.

Next, the conditions 1. of the inclined portion 22 or the flat portion 21 for further improving the utilization efficiency of the light source light. ~ 3.
Will be described.

1. About the inclined portion 22 In the light guide 24, the inclined portion 22 of the interface 23 mainly functions as a reflecting surface that reflects the incident light from the light source 26. On the other hand, the flat portion 21 of the interface 23 mainly functions as a transmission surface that transmits the light reflected by the reflection plate 17 provided on the back surface of the liquid crystal cell 10 and the ambient light.

In order for the incident light from the light source 26 to be totally reflected by the inclined portion 22, the following conditions must be satisfied. That is, the light incident on the surface (interface) where substances having different refractive indices come into contact is totally reflected at the interface when the incident angle is equal to or greater than the critical angle. Therefore, in order for the light incident on the inclined portion 22 to be totally reflected by the inclined portion 22, the inclined portion 22 has an incident angle θ1 represented by θ1 ≧ θc = arcsin (n2 / n1) (Equation 2). Incident on.

However, in the above formula 2, θ1: angle of incidence on the inclined portion 22, n1: refractive index of the light guide 24 n2: refractive index of material in contact with the light guide 24 at the inclined portion 22 θc: inclined portion 22 Is the critical angle of.

As described above, if the inclined portion 22 is formed so that the incident angle θ 1 of the light on the inclined portion 22 satisfies the equation 2, light leakage from the inclined portion 22 to the outside of the light guide 24 is suppressed. As a result, the light utilization efficiency can be further improved.

2. Regarding the flat portion 21, it has been described above that the flat portion 21 is a region that mainly transmits light. The light transmitted through the flat portion 21 includes (a) reflected light from the liquid crystal cell 10 and (b) a reflection mode. There is ambient light when used in.

The output light of the above (a) is dimmed by the liquid crystal layer 12 of the liquid crystal cell 10, reflected by the reflection plate 17 and again incident on the light guide 24, and then emitted from the interface 23 to the observer side. At this time, the output is mainly from the flat portion 21. The light reflected by the reflector 17 becomes diffused light. This diffused light is incident on the flat portion 21 at a critical angle or less so that it is transmitted with very little reflection on the flat portion 21 and is transmitted. The critical angle changes depending on the refractive index of the light guide 24, but is approximately 42 ° when PMMA is used as the material of the light guide 24. That is, the liquid crystal cell 1
The output light from 0 is approximately 40 ° on the flat portion 21 of the light guide 24.
It is preferable that the light is incident at the following.

The flat portion 21 does not necessarily have to be parallel to the interface 28. The angle of incidence on the flat portion 21 also depends on the light scattering range of the reflector 17. Therefore, if the characteristics of the reflection plate 17 are also taken into consideration, as shown in FIG. 4, for example, the main range in which light is scattered in the reflection plate 17 is about ± 30 ° with respect to the normal line of the reflection plate 17. If so, if the inclination angle δ of the flat portion 21 with respect to the reflection plate 17 is within approximately ± 10 °, the component 33 of the light reflected by the flat portion 21 can be extremely reduced. In addition, in FIG. 4, in order to make it easy to understand that the flat portion 21 is inclined with respect to the interface 28, the inclination angle δ is shown to be larger than the above preferable range.

Thus, if the flat portion 21 is formed parallel to the interface 28 or inclined within ± 10 °,
Since the incident light from the light source 26 is incident on the flat portion 21 at an incident angle larger than the incident angle on the inclined portion 22, the light incident on the flat portion 21 from the light source 26 is unlikely to leak to the outside and is reflected by the flat portion 21. The amount of light emitted increases. Thereby, the loss of light from the light source is suppressed.

Further, considering the ambient light when used in the reflection mode of (b) above, when the reflection type LCD is used in the reflection mode in which the front light 20 is turned off,
In order to take in sufficient ambient light into the liquid crystal cell 10, it is preferable that the area of the flat portion 21 is large.

3. Arrangement of the inclined portion 22 and the flat portion 21 at the interface 23 Regarding the arrangement of the inclined portion 22 and the flat portion 21 of the interface 23, (a) when the user looks at the reflective LCD from the interface 23 side, the inclined portion 22 22 is small, the area of the flat portion 21 is large, and (b) the sum of the projections of the inclined portion 22 on the incident surface 25 is large and the sum of the projections of the flat portion 21 is small. is there.

The condition (a) above is that the interface 28
It means that the total sum of the projections of the flat part 21 on the is larger than the total sum of the projections of the inclined part 22. Slope 2 to interface 28
The magnitude of the projection of 2 is determined by the inclination angle α of the inclined portion 22 with respect to the interface 28 shown in FIG. Therefore, by adjusting the size of the inclination angle α, the area of the inclined portion 22 seen from the user can be made extremely smaller than the area of the flat portion 21.

Further, by adjusting the pitch of the inclined portion 22 and the flat portion 21 to match the scanning lines of the liquid crystal cell 10 or the bus lines, the flat portion 21 is arranged over the entire area where the liquid crystal cell 10 is actually displayed. You can
The light utilization efficiency is further improved.

As described above, the condition (b) is that the incident surface 25 is used in order to effectively use the incident light from the light source 26.
It means that it is preferable that only the inclined portion 22 of the interface 23 is visually recognized when viewed from the normal direction.

Next, the measurement result of the illumination light intensity of the front light 20 will be described. A measurement system as shown in FIG. 5 was used to measure the illumination light intensity of the front light 20. That is, the normal direction of the interface 28 of the front light 20 was set to 0 °, and the light intensity in the range of 0 ° to ± 90 ° was measured by the detector 34.

The results are shown in FIG. As is apparent from FIG. 6, in the front light 20, the light that has entered the light guide 24 from the light source 26 through the incident surface 25 is the light guide 2.
It is understood that the light is emitted in the substantially normal direction of the interface 28 by the action of 4. That is, the front light 20 can allow light from the light source 26 arranged on the side surface of the light guide 24 to enter the liquid crystal cell 10 substantially vertically, and functions as bright auxiliary illumination.

Further, the reflective LCD of this embodiment has an advantage that brighter display is possible as compared with a transmissive LCD, a self-luminous display such as a CRT or PDP.

That is, as shown in FIG. 7A, the light 36 a from the self-luminous display 35 is the ambient light 37.
The traveling direction is opposite to. Therefore, the light 36a
The component 36b obtained by subtracting the ambient light 37 from is recognized by the observer.

On the other hand, the reflective LCD of this embodiment
Then, when used in the illumination mode, as shown in FIG. 7B, the auxiliary light 39a from the front light 20 and the ambient light 37 are reflected by the reflection plate (not shown) of the liquid crystal cell 10. The component 39b corresponding to the sum of the auxiliary light 39a and the ambient light 37 is recognized by the observer. As a result, brighter display is realized not only in a dark place but also in a bright place such as outdoors during the day.

As described above, in the structure according to the present embodiment, since the front light 20 is provided with the step-shaped light guide 24, the utilization efficiency of the light emitted from the light source 26 is improved. Thereby, when the ambient light is not sufficient, sufficient illumination light can be given to the liquid crystal cell 10.
Reflective LCD that can always display brightly regardless of the surrounding environment
Can be provided.

[Second Embodiment] The following will describe another embodiment of the present invention with reference to FIGS. 8 to 11. It should be noted that configurations having the same functions as the configurations described in the above-described first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

The reflective LCD according to this embodiment is shown in FIG.
As shown in FIG. 5, a front light system 51 including the front light 20 (first light guide body) and the wedge-shaped second light guide body 40 described in the first embodiment on the front surface of the liquid crystal cell 10. It is characterized by having.

The second light guide 40 is disposed between the light guide 24 of the front light 20 and the liquid crystal cell 10, and has a slope 41 parallel to the interface 28 of the light guide 24 and the liquid crystal cell. And a bottom surface 42 parallel to the surface of 10. As shown in FIG. 9A, the inclination angle of the inclined surface 41 with respect to the bottom surface 42 is defined by a line 49 connecting the portions where the inclined portion 22 and the flat portion 21 contact with each other in a ridge shape at the interface 23 of the light guide 24.
It is preferably designed to be parallel to the bottom surface 42.

The second light guide 40 is preferably formed of a material having at least the same refractive index as that of the light guide 24 which is the first light guide. Needless to say, the second light guide 40 may be made of the same material as the light guide 24. If the light guide 24 and the second light guide 40 are integrally formed by, for example, injection molding, the manufacturing process can be simplified.

In the gap between the light guide 24 and the second light guide 40, spacers (not shown) having a particle size of 50 μm are previously dispersed. As a result, in the gap between the light guide 24 and the second light guide 40, a void 43 having a particle diameter substantially equal to the particle diameter of the spacer is formed.

The space between the bottom surface 42 of the second light guide 40 and the polarizing plate 18 of the liquid crystal cell 10 is filled with a filler (not shown) that matches the refractive indexes of the two. As a result, light attenuation due to reflection at the interface between the second light guide 40 and the polarizing plate 18 is prevented, and the loss of light from the light source is further suppressed.
As the filler, for example, a UV curable resin or methyl salicylate can be used.

Here, the effect of providing the second light guide 40 between the light guide 24 and the liquid crystal cell 10 will be described.

As shown in FIG. 9B, the second light guide 4
In the configuration in which 0 is not provided (Embodiment 1), the interface 28 as the exit surface from the inclined portion 22 to the liquid crystal cell 10 is provided.
The distance ln (l1, l2 in the drawing) becomes smaller as the distance xn (x1, x2 in the drawing) from the light source 26 increases. On the other hand, in the front light system 51 of the present embodiment, as shown in FIG.
By providing 0, the liquid crystal cell 10 can be
The distance ln to the bottom surface 42 of the second light guide 40, which is the exit surface to the light source, is approximately equal regardless of the distance xn from the light source 26.

That is, the second light guide 40 plays a role of keeping the distance from the inclined portion 22 of the front light 20 to the liquid crystal cell 10 constant, so that the front light system 51 can detect the distance from the light source 26. It functions as a surface light source that emits light with a constant brightness.

Here, in order to confirm the effect of the second light guide 40, as shown in FIG.
Was moved in parallel to the bottom surface 42 of the second light guide 40, and the luminance distribution of the output light of the front light system 51 was measured. The vicinity of the incident surface 25 is the measurement start position PS, and the position on the bottom surface 42 farthest from the light source 26 is the measurement end position PE. The measurement result is shown in FIG.
It is as shown in (a).

Similarly, for comparison, the second light guide 40
In order to measure the luminance distribution of the output light of the configuration (Embodiment 1) in which no is provided, as shown in FIG.
The measurement was performed while moving the detector 44 parallel to the interface 28 of the front light 20. The incident surface 2
The vicinity of 6 is the measurement start position PS, and the position farthest from the light source 26 at the interface 28 is the measurement end position PE. The measurement result is as shown in FIG.

As is clear from comparison between FIGS. 11A and 11B, when the second light guide 40 is not provided, as shown in FIG. The pitch p is larger as it is closer to the light source 26 and smaller as it is farther from the light source 26, whereas the front light system 51 of the present embodiment is as shown in FIG.
The pitch p of the luminance peak is the bottom surface 42 of the second light guide 40.
Almost the same throughout, and the brightness peak is also uniform.

As described above, the reflective LCD of this embodiment
The front light system 51 on the front of the liquid crystal cell 10.
The front light system 51 includes a light guide 24 as a first light guide and the liquid crystal cell 10 so that the distance from the inclined portion 22 of the light guide 24 to the liquid crystal cell 10 is constant. By providing the second light guide 40 for
Even when the front light system 51 illuminates the liquid crystal cell 10 evenly and sufficient ambient light cannot be obtained, a bright and even high-quality display is achieved.

[Third Embodiment] The following description will explain still another embodiment of the present invention with reference to FIGS. 5 and 12 to 14.
It should be noted that configurations having the same functions as the configurations described in the above-described respective embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 12, the reflective LCD of this embodiment has a front light 20 on the front surface of the liquid crystal cell 10.
And a front light system 52 constituted by the second light guide body 45 and the second light guide body 45.

As shown in FIG. 13, the second light guide member 45 is a front scattering plate having a function of scattering the incident light from the light guide member 24 only in the traveling direction side thereof, and has a predetermined shape. An anisotropic scattering plate having a property of scattering only light incident from an angle range and transmitting incident light from a range other than the predetermined angle range. As the second light guide 45 satisfying such a condition, for example, a viewing angle control plate (trade name: Lumisty) manufactured by Sumitomo Chemical Co., Ltd. is commercially available.

The angle range in which the second light guide 45 scatters the incident light preferably completely includes the angle range in which the light emitted from the light guide 24 is incident. As a result, the light emitted from the light guide 24 can be scattered without difficulty,
It is possible to improve the utilization efficiency of the light from the light source. In addition, the second light guide 45 is anisotropic scattering having a property of scattering only light incident from a predetermined angle range and transmitting incident light from a range other than the predetermined angle range. The second light guide member 4 receives the incident light from outside the predetermined angle range.
Since 5 does not act, the display quality is prevented from being deteriorated by unnecessary scattered light.

Spacers (not shown) having a particle diameter of 50 μm are previously dispersed in the gap between the light guide 24 and the second light guide 45. As a result, as shown in FIG. 12, in the gap between the light guide 24 and the second light guide 45, a void 46 having a particle diameter substantially equal to the particle diameter of the spacer is formed.

The space between the second light guide body 45 and the polarizing plate (not shown) of the liquid crystal cell 10 is filled with a filler (not shown) that matches the refractive indexes of the two. As a result, light attenuation due to reflection at the interface between the second light guide 45 and the liquid crystal cell 10 is prevented, and the loss of light from the light source is further suppressed.

Here, the measurement result of the illumination light intensity of the front light system 52 will be described. In order to measure the illumination light intensity of the front light system 52, the same measurement system as that used in the first embodiment (see FIG. 5) described above was used. Here, the front light system 52
The normal direction of the second light guide body 45 is 0 °, and 0 ° is ±
In the range of 90 °, the liquid crystal cell 1 of the second light guide body 45
The light intensity from the surface located on the 0 side was measured by the detector 34. The result of the measurement is shown in FIG.

As is apparent from FIG. 14, in the front light system 52 of this embodiment, the light emitted from the light guide 24 as the first light guide is scattered by the second light guide 45. It can be seen that, as compared with the first embodiment, it has a flat angle characteristic.

As described above, the structure described in the present embodiment is provided with the second light guide 45 that scatters the light emitted from the light guide 24, so that the brightness of the light emitted to the liquid crystal cell 10 is increased. The distribution is averaged, and the liquid crystal cell 10 can be uniformly irradiated.

As the second light guide 45, it is possible to use a hologram or the like in addition to the anisotropic scattering plate.

[Fourth Embodiment] The following description will explain still another embodiment of the present invention with reference to FIGS. In addition,
The components having the same functions as those described in each of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

As described in the first embodiment, when the viewer-side interface 23 of the light guide 24 is formed by the inclined portion 22 and the flat portion 21, it is reflected by the liquid crystal cell 10. When the light incident on the light guide 24 again passes through the interface 23, image blurring or blurring may occur.

That is, as shown in FIG. 15, the liquid crystal cell 1
The output light 48a from 0 is transmitted not only from the flat portion 21 but also from the inclined portion 22 to the observer side. At this time, the emitted light 48b from the inclined portion 22 and the emitted light 48c from the flat portion 21 are emitted in different directions and intersect with each other, so that blurring or blurring may appear in the image to be displayed.

In order to solve such a problem, the reflective LCD of the present embodiment is provided with a light guide 2 as shown in FIG.
In the interface 23 of No. 4, a metal reflection film 47 (reflection member) that reflects light is added to the surface of the inclined portion 22. As shown in FIG. 16, the metal reflection film 47 reflects all the light incident on the inclined portion 22 regardless of the incident angle. As a result, the light emitted from the interface 23 to the observer side is only the light transmitted through the flat portion 21. As a result, a clear display image without bleeding or blurring can be obtained.

An example of the method of manufacturing the metal reflection film 47 will be described below by taking the case of using aluminum as a material. The material of the metal reflection film 47 is not limited to aluminum, and a metal such as silver may be used.

First, as shown in FIG. 17A, an aluminum film 61 is formed on the entire surface of the interface 23 of the light guide 24 by sputtering. Furthermore, FIG. 17 (b)
As shown in, the photoresist 62 is applied to the surface of the aluminum film 61. Next, through an exposure process, FIG.
As shown in (c), the photoresist 62 is patterned. Then, as shown in FIG. 17D, the aluminum film 61 is etched using the patterned photoresist 62 as a mask. After that, the photoresist 62 is peeled off to form a metal reflection film 47 made of aluminum on the surface of the inclined portion 22 of the interface 23, as shown in FIG.

As described above, since the metal reflection film 47 is provided on the surface of the inclined portion 22, it is possible to increase the inclination angle α of the inclined portion 22 with respect to the flat portion 21, as shown in FIG. is there. For example, as shown in FIG. 18, in the configuration in which the metal reflection film 47 is not provided on the inclined portion 22,
When the inclination angle α is as large as 60 °, the light 49a incident on the inclined portion 22 at an incident angle smaller than the critical angle θc is
The light 49b is transmitted through the inclined portion 22 to the viewer side. Such light 49b is not preferable because it deteriorates the display quality.

On the other hand, in the structure of the present embodiment, since the metal reflection film 47 is formed on the inclined portion 22, even if the inclination angle α is large, the inclined portion 22 like the above-mentioned light 49b. There is no light that passes through, and all the light is reflected by the inclined portion 22.

As described above, since the inclination angle α of the inclined portion 22 can be made large, the inclined portion 22 becomes less visible when viewed from the direction normal to the flat portion 21,
There is an advantage that the display quality can be improved.

Incidentally, as shown in FIG. 19, if a black matrix 47b (light shielding member) for preventing reflection of ambient light is laminated on the surface of the metal reflection film 47, ambient light is reflected to the observer side. Can be prevented. This prevents deterioration of display quality due to reflection of ambient light to the observer side, which is more preferable.

As described above, the front light 20 according to the present embodiment is characterized in that the metal reflection film 47 for eliminating the transmitted light from the inclined portion 22 to the observer side is formed on the inclined portion 22. I am trying. As a result, the light emitted from the interface 23 to the observer side is only the light emitted from the flat portion 21, and therefore, in the reflective LCD having the front light 20 on the front surface of the liquid crystal cell 10, there is no bleeding or blurring. It is possible to obtain a clear display image.

[Fifth Embodiment] The following will describe still another embodiment of the present invention in reference to FIG. 15 and FIGS. 20 to 22. It should be noted that configurations having the same functions as the configurations described in the above-described respective embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

The reflective LCD according to this embodiment is shown in FIG.
As shown in FIG.
The front light system 53 configured by the front light 20 described above and the optical compensation plate 64 (compensation means) provided on the interface 23 of the front light 20.
It is characterized by having.

In the optical compensating plate 64, a bottom surface 64a which is a surface facing the light guide 24 of the front light 20.
As shown in FIG. 20, has a stepped shape complementary to the interface 23 of the light guide 24. That is, on the bottom surface 64 a, the inclined portion 65 parallel to the inclined portion 22 is formed at a position facing the inclined portion 22 of the light guide 24, and at the position facing the flat portion 21 of the light guide 24, the flat portion 21 is formed. Is formed with a flat portion 66 parallel to. On the other hand, in the optical compensation plate 64, the surface 64 b, which is the surface located on the observer side, has the interface 28 of the light guide 24.
Is formed as a plane parallel to.

The optical compensation plate 64, like the light guide 24,
For example, it can be produced by injection molding using PMMA. As described above, the optical compensation plate 64 and the light guide 24 are arranged so that their inclined portions and flat portions face each other, and are bonded via a spacer (not shown) having a particle diameter of about 20 μm. As a result, the air layer 6 having a substantially uniform thickness is provided between the bottom surface 64 a of the optical compensation plate 64 and the interface 23 of the light guide 24.
7 will intervene.

As described above, by providing the optical compensation plate 64 on the front surface of the light guide 24 and by providing the air layer 67 between the light guide 24 and the optical compensation plate 64, the following effects can be obtained. To be

That is, in FIG. 1 in the fourth embodiment.
As described with reference to FIG. 5, the lights 48 a and 48 a that are incident on the light guide 24 again from the liquid crystal cell 10 are
Even if they proceed in the same direction inside 4, by passing through the inclined portion 22 or the flat portion 21 of the interface 23, respectively,
The light is emitted from the interface 23 of the light guide in different directions, causing blurring or blurring of the image.

On the other hand, in the front light system 53 of this embodiment, as shown in FIG.
Light 68a / 69 that is incident on the light guide 24 from 0 in the same direction
After being emitted from the light guide 24, a is refracted at the bottom surface 64a serving as the interface between the air layer 67 and the optical compensation plate 64, and becomes light that travels in the same direction again, as shown as light 68b and 69b. The light is emitted from the surface 64b of the optical compensation plate 64 in the same direction. As a result, a clear image without bleeding or blurring can be obtained when viewed from the observer side.

In addition to the above-mentioned optical compensation plate 64, FIG.
As shown in FIG. 2A, the optical compensation plate 71 formed in a flat plate shape may be arranged on the front surface of the light guide 24. in this case,
As shown in FIG. 22B, the optical compensation plate 71 has a region 7 into which the light emitted from the inclined portion 22 of the light guide 24 is incident.
1a and the region 71b on which the light emitted from the flat portion 21 of the light guide 24 is incident have refractive indexes different from each other. θa and θb are almost equal. Alternatively, the region 71a may be formed of a member having a diffractive function (for example, a diffractive element) in order to diffract the light transmitted through the region 71a in the same direction as the light transmitted through the region 71b.

Alternatively, as shown in FIG. 22C, in the optical compensating plate 71, the black mask 7 for blocking the light incident on the region where the light emitted from the inclined portion 22 of the light guide 24 enters.
The light emitted from the inclined portion 22 may be prevented from reaching the observer side by being formed of 1c.

As described above, according to the configuration of this embodiment, the inclined portion 22 and the flat portion 2 of the interface 23 of the light guide 24 are formed by the optical compensation plate 64 (or the optical compensation plate 71).
By aligning the emission direction of the light from each of 1, the reflective LC that enables clear display without blurring or blurring.
D is realized.

[Embodiment 6] FIGS. 20 and 23 show still another embodiment of the present invention.
The following is a description with reference to FIGS. It should be noted that configurations having the same functions as the configurations described in the above-described respective embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

The reflective LCD according to the present embodiment is obtained by adding a touch panel function to the front light system 53 (see FIG. 20) of the reflective LCD described in the fifth embodiment.

In order to realize the above-mentioned touch panel function, the reflective LCD of this embodiment is provided with a transparent electrode 72 made of, for example, ITO on the bottom surface 64a of the optical compensation plate 64, as shown in FIG. The inclined portion 22 of the light body 24 is provided with a reflective electrode 73 made of a material that reflects light and has conductivity, such as aluminum. The transparent electrode 72 and the reflective electrode 73 constitute a position detecting means.

The lower part of FIG. 24 is a plan view showing the shape of the reflective electrode 73 when viewed from the direction normal to the flat portion 21 of the light guide 24. As shown in FIG. 24, since the reflective electrode 73 is provided on the entire surface of the inclined portion 22 of the light guide 23, it has a stripe shape when viewed from the normal direction of the flat portion 21 of the light guide 24. Further, as shown in FIG. 25, the transparent electrodes 72 formed on the optical compensation plate 64 are also formed in a stripe shape, and the reflective electrodes 73 and the transparent electrodes 72 form a matrix orthogonal to each other.

A plastic bead spacer (not shown) having a particle size of about 10 μm is scattered between the reflective electrode 73 of the light guide 24 and the transparent electrode 72 of the optical compensation plate 64. Voids are formed that are approximately equal in diameter.

This optical compensator 64 has flexibility and is shown in FIG.
As shown in FIG. 6, by being pressed by the pen 74, the transparent electrode 72 and the reflective electrode 73 come into contact with each other. The recognition of the coordinates pressed by the pen 74 is performed as follows. Figure 25
As shown in FIG. 7, the transparent electrode 72 and the reflective electrode 73 are scanned with a signal line-sequentially so that the contact point 7
The X coordinate and the Y coordinate of 5 are detected, and the coordinates of the position pressed by the pen 74 can be specified in the plane of the touch panel.

Here, the configuration in which the transparent electrode 72 in the form of a stripe is formed on the optical compensation plate 64 has been described as an example, but the transparent electrode may be formed on the entire bottom surface 64a of the optical compensation plate 64. . However, as described above, forming the transparent electrode 72 in a stripe shape has an advantage of high light utilization efficiency.

As described above, according to the configuration of this embodiment, the optical compensator 64 functions as a touch panel, so that a reflective LCD capable of pen input with respect to the content displayed in the liquid crystal cell 10 is provided. It becomes possible.

[Seventh Embodiment] The following description will explain still another embodiment of the present invention with reference to FIGS. 27 to 30. In addition,
The components having the same functions as those described in each of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 27, the front light included in the reflective LCD according to the present embodiment has, in addition to the structure described in the first embodiment, an incident surface of the light source 26 and the light guide 24. 25 between the light source 26 and the incident surface 2
5, a prism sheet 81 and a diffusion plate 82 are provided as a light control means for controlling the spread angle of the light incident on the light source 5. In addition, here, the prism sheet 8
The apex angle of the prism 1 is 100 °. In addition, the light guide 2
4 and the polarizing plate 18 of the liquid crystal cell 10 are filled with a filler 84 for relaxing the difference in refractive index.

The light source 26 is realized by, for example, a fluorescent tube, but the output light from the fluorescent tube does not have a particular directivity and is randomly generated. For this reason, there is light that enters the inclined portion 22 of the light guide 24 at an angle larger than the critical angle, and there is a risk that leakage light from the inclined portion 22 will cause deterioration in display quality.

Considering that the refractive index of PMMA which is preferably used as the material of the light guide 24 is about 1.5,
Light having an incident angle to the inclined portion 22 that is equal to or less than the critical angle (about 42 °) becomes leakage light. In order to eliminate such leaked light, the spread angle of the output light from the light source 26 may be controlled in advance so that the incident light that becomes the leaked light component does not enter the light guide 24.

Here, as shown in FIG. 28, the inclination angle of the inclined portion 22 with respect to the interface 28 is α. Note that FIG.
For the sake of convenience of explanation, the positional relationship among the inclined portion 22, the interface 28, and the incident surface 25 of the light guide 24 is extracted and shown, and the light guide 24 actually has such a shape. Do not mean.

Further, the spread angle of the light incident from the incident surface 25 of the light guide 24 is ± β, and the critical angle of the inclined portion 22 is θc.
Then, the incident angle θ of the light on the inclined portion 22 is represented by θ = 90 ° −α−β.

Therefore, the condition for the light incident on the inclined portion 22 from the incident surface 25 not to pass through the inclined portion 22 is θc <θ = 90 ° −α−β, that is, β <90 ° − (θc + α) · .. (Expression 3)

In this embodiment, the inclination angle α of the inclined portion 22 is 10 °. From this and the critical angle θc of 42 °, β <38 ° is derived based on the above equation 3.

The output light from the light source 26 is once diffused by the diffusion plate 82 and enters the prism sheet 81. The prism sheet 81 has a function of condensing diffused light in a specific angle range. When the apex angle of the prism is 100 °, the diffused light is scattered within an angle range of about ± 40 ° as shown in FIG. Focus. The light collected in the angle range of about ± 40 ° is guided by the light guide 2.
4 is further condensed by refraction at the incident surface 25 to become a spread light in the range of about ± 25.4 °. That is, it can be seen that the divergence angle of the light incident from the incident surface 25 is sufficiently within the above range of β <38 °, and leak light from the inclined portion 22 does not occur.

As described above, the reflection type L according to this embodiment is
In the CD, the prism sheet 81 is installed between the light source 26 and the incident surface 25 of the light guide 24 in order to suppress the spread of the light from the light source. It is further improved.

Incidentally, in this embodiment, the prism sheet 8 is used.
Although the apex angle of 1 is 100 °, it is not necessarily limited to this angle. Further, the prism sheet 81 is used as the light control means for limiting the spread of the light from the light source, but the invention is not limited to this as long as the same effect can be obtained, and for example, a collimator or the like may be used. Further, as shown in FIG. 30A, the same effect can be obtained by a configuration in which the periphery of the light source 26 is covered with an ellipsoidal mirror 98 and the light source 26 is installed at the focal point of the ellipsoidal mirror 98. In addition, SID DI
As shown in GEST P.375 (1995), FIG.
The spread of the incident light from the light source 26 may be controlled using the light pipe 99 shown in (b).

[Embodiment 8] The following description will discuss still another embodiment of the present invention with reference to FIGS. 1, 3, and 31 to 33. It should be noted that configurations having the same functions as the configurations described in the above-described respective embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

The reflective LCD according to this embodiment is the same as the reflective LCD described in each of the above-described embodiments, because of the difference in refractive index between the front light (or front light system) and the liquid crystal cell 10. It is filled with a filler (matching agent) that prevents light from being attenuated.

Here, the reflection type L described in the first embodiment is used.
Description will be given by taking as an example a configuration in which the above-mentioned filler is applied to a CD. In the first embodiment, as described with reference to FIG. 1, the light guide 24 of the front light 20 has the liquid crystal cell 1
It is laminated on the polarizing plate 18 of No. 0 through a spacer having a particle size of about 50 μm. As a result, a void 29 is formed between the liquid crystal cell 10 and the light guide 24 with a uniform thickness that is approximately equal to the particle size of the spacer.

In the reflective LCD of this embodiment, the void 29 is filled with a filler 84 as shown in FIG. As the filler 84, for example, a UV curable resin or methyl salicylate can be used. As a result, the interface 28 of the light guide 24 comes into contact with not the air but the filler 84 having a refractive index higher than that of the air. The filler 84 preferably has a refractive index substantially equal to that of the light guide 24.

As described above, the case where the interface 28 of the light guide 24 is in contact with the filler 84 and the case where the interface 28 of the light guide 24 is in contact with air as in each of the above-described embodiments. , The behavior of light at the interface 28 is different.

Of the incident light from the light source 26, FIG.
As shown in (a), the component that is substantially vertically incident on the incident surface 25 is directly incident on the inclined surface 22 from the incident surface 25, reflected, and then passes through the interface 28 and the filler 84 to pass through the liquid crystal cell 10.
Incident on. The behavior of light at the interface 28 at this time is as follows.
This is the same as when the interface 28 is in contact with air (see FIG. 3A).

On the other hand, of the incident light from the light source 26, FIG.
As shown in FIG. 1 (b), among the components that are first incident on the interface 23 from the incident surface 25, the flat portion 21 such as the light 85 a is included.
There is also one that is incident on the interface 28 after being reflected at. Of such light 85a and incident light from the light source 26, FIG.
As shown in (c), the component that first enters the interface 28 from the incident surface 25 has no effect on the interface 28 because the interface 28 is in contact with the filler 84 having a refractive index substantially equal to that of the light guide 24. Transparent without receiving.

These lights are emitted by the liquid crystal layer 12 of the liquid crystal cell 10.
Will be incident at a very large angle of incidence,
Since the light is reflected by the reflection plate 17 and re-enters the interface 28 of the light guide 24 at the above-mentioned large incident angle, it does not reach the observer.

However, in order to improve the utilization efficiency of the light from the light source, it is preferable to eliminate the component directly incident on the interface 28 from the light source 26. Therefore, as shown in FIG. 32, by tilting the incident surface 25 so that the incident surface 25 and the interface 28 form an obtuse angle, it is possible to eliminate a component that is directly incident on the interface 28 from the incident surface 25.

The angle γ formed by the incident surface 25 and the interface 28
As shown in FIG. 33, considering the spread angle β after the light from the light source 26 is incident on the incident surface 25, it is more preferable that the magnitude of γ be ≧≧ 90 ° + β. As a result, almost all of the light source light that has entered from the incident surface 25 enters the interface 23, and the utilization efficiency of the light source light can be further improved.

[Ninth Embodiment] The following will describe still another embodiment of the present invention in reference to FIG. It should be noted that configurations having the same functions as the configurations described in the above-described respective embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

The reflective LCD according to the present embodiment is characterized in that the front light 20 is formed in a lid shape that can be opened and closed with respect to the liquid crystal cell 10.

In each of the above-described embodiments, various forms of the front light or the front light system as the front lighting device have been described. Particularly, as in the configuration described in the fourth embodiment, the inclination of the light guide 24 is inclined. When the portion 22 is provided with the metal reflection film 47, the metal reflection film 47 prevents the ambient light from entering the light guide 24. Therefore, the ambient environment is not so dark as to require the reflective LCD to be used in the illumination mode, but the display in the reflective mode is not preferable especially in the situation where the ambient light amount is not enough to be used in the reflective mode. May become dark.

Therefore, as shown in FIG. 34, in the reflective LCD 91 of the present embodiment, the front light 20 is fixed to the liquid crystal cell 10 by fixing one side of the front light 20 with, for example, a hinge (not shown). It is openable and closable. The front light 20 is formed as an inner lid that can be opened and closed independently of a lid 92 that covers the liquid crystal cell 10 and the front light 20.

Therefore, when the reflective LCD 91 is used in the illumination mode, the front light 2 is placed on the surface of the liquid crystal cell 10.
When the reflective LCD 91 is used in the reflective mode when the reflective LCD 91 is used in a state in which 0 is covered, that is, only the lid 92 is opened,
The front light 20 can be used with the liquid crystal cell 10 open.

As a result, when used in the reflection mode, the reflection type LCD which can always realize a bright display without light loss due to the front light 20 is realized.

In the above description, at least a part of the front light 20 is fixed to the liquid crystal display device. However, the front light 20 is completely unitized and can be attached to and detached from the liquid crystal cell 10. Also good. However, in this case, it is necessary to consider how to store the front light 20 when it is removed from the liquid crystal cell 10.

Although the reflective LCD provided with the front light 20 in the shape of an inner lid has been described here, the front light system described in each of the above-described embodiments may be provided in the shape of an inner lid. .

[Embodiment 10] Still another embodiment of the present invention is described below with reference to FIGS. 35 and 36. In addition,
The components having the same functions as those described in each of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

In each of the above-described embodiments, the reflection type LCD having the structure in which the front light or the front light system as the front illumination device and the reflection type liquid crystal cell as the object to be illuminated are combined has been described. However, the front light or the front light system as the front lighting device of the present invention is not used only in combination with the reflective liquid crystal cell. For example, as shown in FIG. 35, the illumination device 95 according to the present embodiment is a device in which the front light or the front light system described in each of the above-described embodiments is formed as an independent unit, and various objects are provided. It is possible to illuminate.

For example, the illumination device 95 can be used by being arranged on a book 96 as shown in FIG. As a result, as shown in FIG. 36, it is possible to illuminate only a region substantially directly under the illumination device 95, and thus it is possible to avoid annoying other people when reading in a bedroom, for example. is there.

The embodiments described above do not limit the present invention, and various modifications can be made within the scope of the invention. For example, as the material of the light guide, PMMA
However, a material such as glass, polycarbonate, polyvinyl chloride, or polyester may be used as long as it can uniformly guide light without attenuation and has an appropriate refractive index. Further, the dimensions and the like of the inclined portion and the flat portion of the light guide body described above are merely examples, and can be freely designed within a range in which equivalent effects can be obtained.

Further, as the liquid crystal cell, various LCDs such as a simple matrix type LCD and an active matrix type LCD can be used. Further, in the above, an ECB mode (single polarizing plate mode) liquid crystal cell using one polarizing plate that also serves as a polarizer and an analyzer is used, but in addition, PDLC or PC-GH without a polarizing plate is used. Etc. may be applied.

[Eleventh Embodiment] The following will describe still another embodiment of the present invention in reference to FIGS. 37 to 48. In addition,
The components having the same functions as those described in each of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 37, the reflective LCD of this embodiment has the same structure as that of the first embodiment, except that the front face of the reflective liquid crystal cell 10a is provided with the front light 20a. The antireflection film (antireflection film) 13, which is the second light guide (optical means), is arranged between the reflective liquid crystal cell 10a and the front light 20a, and is formed in the light guide 24a. Different from the first embodiment, the width (pitch) of the flat portion 21 and the inclined portion 22 is different, and the reflection electrode (reflection plate) 17a is formed inside the reflection type liquid crystal cell 10a. There is.

First, the front light 20a will be specifically described. The front light 20a is mainly the light source 26 and the light guide 24 as in the first embodiment.
a, and the incident surface 25 of the light guide 24a.
A light source 26 as a linear light source covered with a reflecting mirror 27 is provided so as to be in contact with.

The interface (first emission surface) 28 of the light guide 24a on the liquid crystal cell 10a side is formed flat, and the interface (second emission surface) 23 facing this interface is parallel to the interface 28. Alternatively, the flat portion 21 formed substantially parallel to the flat portion 21 and the inclined portion 22 inclined in the same direction with respect to the flat portion 21 at a constant angle
And are formed alternately.

As described above, the light guide body 24a is similar to the light guide body 24 in the first embodiment in that, as shown in FIG. It is shaped like a staircase that goes down as it goes away.

Here, the shape of the light guide 24a will be described in more detail with reference to FIGS. 38 (a) to 38 (c). FIG. 38 (a) is a plan view of the light guide seen from above in the normal direction of the flat portion, and FIG. 38 (b) is a side view of the light guide seen from the direction normal to the incident surface. , FIG. 38 (c)
[FIG. 4] is a cross-sectional view of the light guide body taken along a plane perpendicular to both the incident surface and the interface.

As the material of the light guide 24a, an acrylic plate is used in this embodiment, and the light guide 24a can be processed into a step shape by molding the acrylic plate. The light guide 24a has a width W in the present embodiment.
= 75 mm, length L = 170 mm, thickness h1 of incident surface 25 = 2.0 mm, width w1 of flat portion 21 = 0.2 mm
And Further, by setting the step height h2 of the inclined portion 22 to be 10 μm and the inclination α with respect to the flat portion 21 to be 45 °, the width w2 of the inclined portion is about 10 μm.

Furthermore, in the present embodiment, the light guide 24a.
Has a configuration in which the sum w3 = 0.21 mm of the width w1 of the flat portion 21 and the width w2 of the inclined portion 22 gradually decreases in the direction away from the incident surface 25, that is, the light source 26. The configurations of the flat portion 21 and the inclined portion 22 will be described more specifically based on FIG. 39 in addition to FIGS. 38 (a) to 38 (c). The light guide 24a
The light source 2 in the direction away from the light source 26 in
A direction in which the longitudinal direction of 6 is a normal line is hereinafter referred to as a first direction and is indicated by an arrow A in FIGS. 38 and 39.

As shown in FIG. 39, the flat part 21 and the inclined part 22 are combined one by one to form one set, and 100 sets of the flat part 21 and the inclined part 22 from the side closest to the light source 26 are made into the first block. Let B1. And this first block B1
The distance w4 in the direction along the first direction is set to 21 mm.

The second block B2, which is the next 100 sets of blocks, is formed so that the interval w4 is 20 mm. Furthermore, the interval w in the next third block B3
4 is formed to be 19 mm, the interval w4 in the fourth block B4 is formed to be 18 mm, and the interval w4 in the fifth block B5 is formed to be 17 mm.

Therefore, in this embodiment, the light guide 24a is formed.
In the above, in each block from the end surface on the light source 26 side to the end surface on the side where the light source 26 is not arranged along the first direction,
The distance w4 between the blocks is reduced by 1 mm. That is, as the distance from the light source 26 increases, the flat portion 21
And the pitch of the inclined portion 22 (the sum w3 of the width w1 of the flat portion 21 and the width w2 of the inclined portion 22) is 10 μm.
It is formed so as to decrease by (1/100 mm). Note that, in FIGS. 38A to 38C, the reduction of the pitch of the flat portion 21 and the inclined portion 22 is not shown for convenience of description.

In the light guide 24a, the inclined portion 22 mainly acts as a minute light source portion which is a surface for reflecting the light from the light source 26 toward the interface 28. on the other hand,
The flat portion 21 mainly functions as a surface for transmitting the reflected light to the observer side when the illumination light from the front light 20a returns from the liquid crystal cell 10a as the reflected light. The operation of each of these parts is the same as in the first embodiment.

Further, the light guide 24a in the front light 20a has, in addition to this stepwise structure, a pitch of, for example, 10 μm for each 100 pairs of the flat portion 21 and the inclined portion 22, that is, A configuration is provided in which the pitch of the stairs is reduced as the distance from the light source 26 increases. Therefore, as shown in FIG. 40A, the number of the inclined portions 22 per unit area increases as the distance from the light source 26 increases.

Incident light from the incident surface 25 from the light source 26 is reflected by the inclined portion 22 acting as a minute light source portion, but the number of inclined portions 22 per unit area increases as the distance from the light source 26 increases. , Front light 20a
The reflection type liquid crystal cell 10a which is an illuminated object illuminated by
The brightness increases as the position moves away from the light source 26. Normally, the brightness tends to lower as the position is farther from the light source 26. Therefore, with the configuration of the light guide 24a of the present embodiment, the interface 28 (first emission surface) is further away from the light source 26. It is possible to cancel the decrease in brightness due to this and efficiently guide the light from the light source 26 to the entire illuminated object at a high angle. As a result, it is possible to average the luminance distribution on the interface 28 side, which is the interface on the illuminated object side (first emission surface).

On the other hand, as shown in FIG. 40B, in the conventional front light 120 in which the light guide 124 is formed in a wedge-shaped flat plate shape, the light source 26 is incident on the incident surface 125.
The incident light incident on is reflected by the interface 123 as it is. Therefore, the brightness on the first emission surface (the interface 128 in the front light 120) is equal to that of the light source 2.
It decreases as it goes away from 6.

Further, as shown in FIG. 41, the luminance distribution state on the first exit surface is as shown in FIG.
Compared to the graph F showing the brightness distribution of No. 20, the graph E showing the brightness distribution of the front light 20a of the present embodiment is substantially constant even at a position where the distance from the light source 26 is large. Therefore, the front light 20 of the present embodiment
It can be seen that a is more excellent in the uniformity of the luminance distribution on the first emission surface (interface 28).

In the light guide 24a having the above structure, since the pitch of the steps is 0.21 mm, the black matrix formed around the pixels of the reflection type liquid crystal cell 10a corresponding to the light guide 24a. The pitch and the pitch of the groove of the inclined portion 22 are deviated. As a result, since it is possible to suppress the generation of moire fringes due to the interference between the black matrix and the inclined portion 22, it is possible to improve the display quality of the obtained reflective LCD. Note that this point will be described later.

The results of the emission angle characteristics of the light guide 24a are shown in FIG. 42. In the graph G on the reflective LCD side (interface 28 side) which is the object to be illuminated, the light receiving angle is -10. 2,000c with a peak between ° and -5 °
The brightness is increased to the extent that it reaches d / m ² . On the other hand, in the graph H on the observer side (interface 23 side), when the light-receiving angle is -60 °, the maximum luminance is 500 cd / m ² , and the angle at which the reflective LCD is observed is 0 °. The luminance is 100 cd / m ² or less in the vicinity.

As described above, the light from the light source 26 arranged on the end face of the light guide 24a can be emitted from the interface 28 at an angle substantially perpendicular to the object to be illuminated (reflection type LCD). At the same time, there is almost no light leakage on the observer side, which is the interface 23 side, and the light from the light source 26 can be efficiently guided to the illuminated object at a high angle.

In this embodiment, a fluorescent tube is used as the light source 26, but the light source 26 is not limited to this. For example, an LED (light emitting diode), an EL element, or a tungsten lamp is used. Can be used.

Next, the liquid crystal cell 10a will be described. As shown in FIG. 37, the liquid crystal cell 10a has the same basic structure as that of the liquid crystal cell 10 of the first embodiment, but the reflector 17a. Is different in that it is formed in the liquid crystal cell 10a.

As shown in FIG. 43, this liquid crystal cell 10a includes a pair of electrode substrates 11a and 11c for forming a liquid crystal layer 12.
And the retardation plate 49 and the polarizing plate 18 on the electrode substrate 11a side which is the display surface side.
Although only one retardation plate 49 (not shown in FIG. 37) is provided in FIG. 43, it may be two or more, or may not be provided.

In the electrode substrate 11a, a color filter 38 is provided on a glass substrate 14a having a light transmitting property, a transparent electrode 15a (scanning line) is provided thereon, and a liquid crystal is formed so as to cover the transparent electrode 15a. An alignment film 16a is formed. An insulating film or the like may be formed on the electrode substrate 11a if necessary. The color filter 38 is not shown in FIG.

On the other hand, the electrode substrate 11c is the glass substrate 14
An insulating film 19 is formed on b, a reflective electrode (reflecting plate) 17a is further formed thereon, and a liquid crystal alignment film 16b is formed so as to cover the reflective electrode 17a. A plurality of uneven portions are formed on the surface of the insulating film 19, and a plurality of uneven portions are also formed on the surface of the reflective electrode 17a covering the insulating film 19.

The reflection electrode 17a serves both as a liquid crystal drive electrode for driving the liquid crystal layer 12 and as a reflection plate. As the reflective electrode 17a, aluminum (A
l) A reflective electrode is used. In addition, the insulating film 19
Is formed of an organic resist, and contact holes and irregularities in this insulating film 19 are formed by photolithography described later. The glass substrate 14a
14b, transparent electrodes 15a and 15b, and liquid crystal alignment film 1
The material and forming method of 6a and 16b are the same as those in the first embodiment.

Regarding the method of forming the electrode substrate 11c,
This will be described in more detail based on FIGS. 44 (a) to 44 (e).

First, as shown in FIG. 44A, the insulating film 19 is formed by coating the entire surface of the glass substrate 14b with the organic resist and baking it. Then, as shown in FIG. 44B, ultraviolet rays 3 are applied to the insulating film 19 through the mask 30.
Irradiate 0a. As a result, the portion of the insulating film 19 irradiated with the ultraviolet rays 30a is removed, and the irradiated portion of the ultraviolet rays 30a is formed into a predetermined pattern as shown in FIG.

Next, as shown in FIG. 44 (d), the insulating film 19 formed in a predetermined pattern is subjected to heat treatment at 180 ° and baked to cause heat drop in the organic resist. Let Due to this heat sag, the uneven portion 19a
To form.

Finally, as shown in FIG. 44 (e), aluminum (Al) is vacuum-deposited so as to cover the uneven portion 19a. As a result, the reflective electrode 17a having the uneven portion formed on the surface is formed along the uneven portion 19a. Note that in FIGS. 44A to 44E, the insulating film 1
9 is formed as an uneven portion 19a having a predetermined pattern, but as shown in FIGS. 37 and 43, the uneven portion may be formed only on the surface of the insulating film 19.

The electrode substrate 11c and the electrode substrate 11a thus obtained are arranged so that the liquid crystal alignment films 16a.
6b are opposed to each other, and the rubbing treatment directions are arranged antiparallel to each other, and they are bonded together using an adhesive. Further, glass bead spacers (not shown) having a particle diameter of 4.5 μm are previously dispersed between the electrode substrates 11a and 11c in order to make the intervals of the voids formed by the electrode substrates 11a and 11c uniform. ing. Then, the liquid crystal layer 12 is formed by introducing liquid crystal into the voids by vacuum deaeration. The material of the liquid crystal layer 12 is the same as that of the first embodiment.

The reflective liquid crystal cell 10a of the present embodiment is manufactured as described above, but the manufacturing steps and manufacturing conditions other than those described above are the same as those of the reflective liquid crystal cell 10 of the first embodiment. Therefore, it is omitted.

The reflective electrode 17 on the electrode substrate 11c.
The pattern of the uneven portion formed on the surface a (that is, the pattern of the uneven portion 19a of the insulating film 19) is irregularly formed to diffusely reflect incident light incident on the reflective liquid crystal cell 10a in a specific direction. Is formed.

The uneven portion of the insulating film 19 preferably has a difference between the apex of the convex portion and the bottom surface of the concave portion of 0.1 μm to 2 μm. When the difference between the peak of the convex portion and the bottom surface of the concave portion in the concave-convex portion is within this range, incident light can be diffused without affecting the alignment of liquid crystal molecules and the cell thickness of the liquid crystal cell.

The reflection electrode 17a thus formed
4 is compared with the reflection characteristic of a standard white plate (MGO) that exhibits a diffuse reflection characteristic almost similar to that of paper.
It will be described based on 5. Above MGO (and paper etc.)
Indicates a reflection characteristic showing isotropicity as shown by a broken line graph M in the figure. On the other hand, the reflective electrode 17a
(MRS) is ± 30 as shown by the solid line graph N in the figure.
It has a diffuse reflection characteristic showing directivity at an angle of °.

An image can be observed even when light is incident on the reflection type liquid crystal cell 10a having the reflection electrode 17a from a direction other than the regular reflection direction. The reflection characteristics of the reflection electrode 17a are not limited to the characteristics shown in FIG. 45, and the design of the reflection electrode 17a can be changed as appropriate to meet the type of equipment used for the reflection type LCD. It is possible to correspond to the characteristics.

Further, since the reflection electrode 17a is formed so as to be adjacent to the liquid crystal layer 12 in the reflection type liquid crystal cell 10a, the reflection plate is in contact with the back side of the reflection type liquid crystal cell 10a (the light guide 24a). Compared with the case where it is formed on the surface opposite to the side surface), the occurrence of parallax due to the glass substrate 14b can be eliminated. Therefore, the obtained reflective LCD
In the above, it is possible to suppress the double reflection of the image. Moreover, the configuration of the reflective liquid crystal cell 10a can be simplified.

The reflective electrode 17 according to the present embodiment.
As shown in FIGS. 37 and 43, a may be a polarization mode in which the reflective liquid crystal cell 10a has a polarizing plate 18, and as shown in FIG. It may be a reflective liquid crystal cell (without a polarizing plate). The basic structure of this reflective liquid crystal cell is almost the same as that of the reflective liquid crystal cell 10a, and therefore detailed description thereof is omitted.

Next, the pixel structure arranged in the liquid crystal cell 10a will be described. As shown in FIG.
The reflective liquid crystal cell 10a is the reflective liquid crystal cell 10a.
A plurality of scanning lines 54 are formed along the longitudinal direction of the, and a plurality of signal lines 55 are formed in a direction orthogonal to the direction in which the scanning lines 54 are formed. And
The plurality of pixels 56 ... Corresponding to the grid pattern formed by the scanning lines 54 and the signal lines 55.
Are formed.

One pixel 56 consists of red (R), green (G), and
Pixel electrode 5 corresponding to three blue (B) color filters
It consists of 6a. These pixel electrodes 56a are arranged in the order of R, G, B along the direction in which the scanning lines 54 are formed.

As for the shape of the reflection type liquid crystal cell 10a, in the present embodiment, a diagonal 6.5 type size (vertical WL =
58 mm, width LL = 154.5 mm), 54 scanning lines X
m = 240, and the number of signal lines 55 is Yn = 640. The pitch PL of the pixels 56 arranged in the reflective liquid crystal cell 10a is 0.24 mm (R, G, B). A black matrix (not shown) (hereinafter abbreviated as BM) is formed around the pixels 56 so as to have a width of 8 μm.

In the reflective LCD according to this embodiment,
The reflective liquid crystal cell 10a and the front light 20a described above.
It is a combination of and. Here, in the front light 20a, the pitch of the flat portion 21 and the inclined portion 22 of the light guide 24a is 0.21 mm as described above, which is smaller than the pitch of the scanning lines 54, that is, the BM. Therefore, B in the reflective liquid crystal cell 10a is
The pitch of M and the pitch of the groove of the inclined portion 22 can be shifted. When these pitches are deviated, it is possible to suppress the generation of moire fringes due to the interference between the BM and the inclined portion 22. Therefore, the display quality of the obtained reflective LCD can be improved.

In the structure of the light guide 24a described above, the pitch of the flat portions 21 and the inclined portions 22 is smaller than the pitch of the scanning lines 54 ...
It may be larger than the pitch. That is, in order to suppress the generation of moire fringes, the pitch of the grooves of the inclined portion 22 and the pitch of the BM may be deviated.

Here, the width w1 of the flat portion 21 and the inclined portion 22
The sum of the width w2 and the width w2 of the groove is defined as the pitch of the grooves of the inclined portion 22.
Further, the BM is formed so as to shield the scanning lines 54 and the signal lines 55. However, since the scanning lines 54 are parallel to the groove of the inclined portion 22, the scanning lines 54 ... The pitch P1 is the pitch of BM.

In order for the pitch of the grooves of the inclined portion 22 and the pitch of the BM to be displaced, it is sufficient that the above w3 and P1 do not match (w3 ≠ P1), but the relationship between w3 and P1 is as follows. Is particularly preferably w3 has a width greater than twice P1 (w3> 2P1) or w3 has a width smaller than half P1 (w3 <1 / 2P1).

If the relationship between w3 and P1 deviates from the above range, the groove pitch of the inclined portion 22 and the BM pitch may deviate from each other. Is possible. Therefore, it is not preferable because the generation of moire fringes cannot be effectively suppressed.

The width w1 of the flat portion 21 and the width w2 of the inclined portion 22, the sum w3 of these w1 and w2, the angle of the inclined portion 22 and the like in this embodiment are limited to the above numerical values. Instead, it may be formed according to the pixel structure of the reflective liquid crystal cell 10a used.

In this embodiment, the direction away from the light source 26 (first direction) is used to average the luminance distribution.
This is dealt with by reducing the pitch of the flat portion 21, but the sum of the pitches of the flat portion 21 and the inclined portion 22 may be reduced by changing the angle of the inclined portion 22 instead of the pitch. . For example, the flat portion 21 is made small, and the angle α formed by the flat portion 21 and the inclined portion 22 is set to the light source 26.
The sum of the pitches of the flat portion 21 and the inclined portion 22 can be reduced by reducing the distance in the direction away from (first direction). Even in this case, since the incident light can be efficiently emitted to the inclined portion 22 in the direction (first direction) away from the light source 26, the luminance distribution can be averaged.

Furthermore, the reflective LC according to the present embodiment
D denotes the front light 2a in addition to the front light 20a having the above-described configuration and the reflective liquid crystal cell 10a having the above-described configuration.
0a and the reflective liquid crystal cell 10a, an antireflection film as a second light guide is arranged.

This antireflection film will be described. In the reflection type LCD, as shown in FIG. 37, an interface (first emission surface) between the polarizing plate 18 arranged in the reflection type liquid crystal cell 10a and the light guide 24a. Then, the antireflection film 13 as the antireflection film is adhered.

As the antireflection film 13, an antireflection film (trade name: TAC-HC / AR) manufactured by Nitto Denko Corporation is used in this embodiment. The antireflection film 13 is a multilayer structure film having a four-layer structure. Specifically, a triacetyl cellulose (TAC) film is used as a base material layer, and a MgF2 layer as a first layer, a CeF3 layer as a second layer, a TiO2 layer as a third layer, and a MgF2 layer as a fourth layer. It is the antireflection film 13 in which each layer is formed.

The TAC film has a refractive index nt = 1.
At 51, the thickness is 100 μm. Also, the first layer M
The gF2 layer has a refractive index nm = 1.38 and a thickness of about 100 n.
m, the second CeF3 layer has a refractive index nC = 2.30 and a thickness of about 120 nm, and the third TiO2 layer has a refractive index nti =
The thickness of the MgF2 layer of 1.63 is about 120 nm and the fourth layer is
The refractive index n = 1.38 and the thickness is about 100 nm.
These first to fourth layers are sequentially formed on the TAC film of the base material layer by a vacuum deposition method.

Further, at the time of adhering to the front light 20a, an acrylic adhesive layer having a refractive index n1 substantially the same as the refractive index n2 of the acrylic material used for the light guide 24a is formed. ing. Therefore, the antireflection effect can be improved without substantially changing the light input / output conditions in the light guide 24a, and the unevenness of the luminance distribution and the occurrence of the rainbow color spectrum can be prevented.

The TAC film of the first layer is not an essential structure for the antireflection film 13. For example, the second to fourth layers except the first layer are used as the light guide 24a. You may laminate directly. However, in this case, the manufacturing cost may increase slightly.

[0215] The antireflection film 13 of the above-mentioned multilayer structure film.
Is λ / 4−λ for incident light of wavelength λ = 550 nm.
The configuration is a / 2-λ / 4-λ / 4 wave plate.
Therefore, the antireflection film 13 can act as the antireflection film 13 in a wide wavelength band.

In the above-mentioned light guide 24a, the light guide 24a
The inclined portion 22 formed on the surface (interface 23) of a is
It functions as a minute light source unit for the reflective liquid crystal cell 10a. Therefore, the reflective liquid crystal cell 10a is irradiated with light from the inclined portion 22, but the interface 28, which is a surface facing the interface between the light guide 24a and the reflective liquid crystal cell 10a, that is, the interface 23. At the inclined portion 2
About 4% of the light from 2 is reflected and becomes reflected light.

Due to the generation of this reflected light, a reflected image is formed from the interface 28 to the interface 23 side. for that reason,
This reflected image and the image on the inclined portion 22 interfere or diffract with each other, resulting in uneven brightness distribution and iridescent spectrum on the surface of the reflective LCD as viewed by an observer.

However, in the reflective LCD according to the present embodiment, the antireflection film (antireflection film 13) is provided between the reflective liquid crystal cell 10a and the front light 20a, that is, on the interface 28 side of the light guide 24a. ) Is arranged, it is possible to suppress the generation of reflected light generated by the incident light from the inclined portion 22 being reflected at the interface 28.

Therefore, it is possible to prevent interference or diffraction between the image on the inclined portion 22 acting as the minute light source portion and the reflected image reflected on the interface 28 side. for that reason,
It is possible to prevent the unevenness of the luminance distribution on the display observed on the observer side (the interface 23 side) and the occurrence of rainbow color spectrum.

Comparing the brightness distribution of the display in the reflective LCD of the present embodiment with and without the antireflection film 13, as shown in FIG. The graph C when the antireflection film 13 is arranged is more uniform and uniform in brightness distribution than the graph D when 13 is not arranged, and the brightness itself is also improved. Recognize.

Further, the antireflection film 13 having the above structure
Since the commercially available one can be used as it is, it is possible to suppress an increase in the manufacturing cost of the front light 20a. Therefore, inexpensive front light 2
It is possible to obtain 0a and a reflective LCD having the same.

Further, the light guide 24a which is the first light guide.
Since the antireflection film 13 is adhered with an adhesive having a refractive index n1 substantially equal to the refractive index n2 of, the antireflection effect is improved without substantially changing the input / output conditions of light in the light guide 24a. be able to.

The structure and material of the antireflection film 13 are not limited to those described above. For example, as the structure of the wave plate, λ /
The configuration may be 4-λ / 2-λ / 2-λ / 2-λ / 4. With such a structure of the wave plate, the antireflection effect can be obtained in a wider wavelength band. Further, it may be an antireflection film having a single layer structure of a λ / 4 wavelength plate. However, in this case, the wavelength band in which the antireflection effect is obtained may be narrowed.

As described above, as the pitch between the flat portion 21 and the inclined portion 22 formed on the surface (interface 23) of the light guide 24a increases in the direction away from the light source 26 (first direction). By making it small, the amount of reflected light reflected by the inclined portion 22 can be increased in the direction away from the light source as compared with the conventional case. Therefore, the luminance distribution at the interface 23 (first emission surface) of the light guide 24a can be averaged.

Further, the flat portion 21 and the inclined portion 2 formed on the interface 23 of the light guide 24a in the front light 20a.
2 is formed smaller than the pitch of the reflection type liquid crystal cell 10a, the moire fringes caused by the interference of light by the BM formed around the pixels 56 and the groove of the inclined portion 22. Occurrence can be suppressed. Therefore, it is possible to prevent the display quality of the reflective LCD from deteriorating.

Further, by providing an antireflection film (antireflection film 13) between the reflective liquid crystal cell 10a and the front light 20a, the interface 23 of the light guide 24a is provided.
It is possible to prevent the unevenness of the luminance distribution and the occurrence of iridescent spectrum in the. Therefore, it is possible to obtain a reflective liquid crystal LCD that is brighter and has a higher display quality.

In addition, by forming an uneven portion on the reflective electrode 17a in the reflective liquid crystal cell 10a, incident light is diffused without affecting the orientation of liquid crystal molecules and the cell thickness. Therefore, an image can be observed even when light is incident on the reflective liquid crystal cell 10a from a direction other than the regular reflection direction.

[Embodiment 12] The following description will discuss still another embodiment of the present invention with reference to FIGS. 49 and 50. In addition,
The components having the same functions as those described in each of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 49, the reflection type LCD of the present embodiment has the same basic structure as that of the second embodiment, but is provided between the reflection type liquid crystal cell 10 and the front light system 51. The difference is that an antireflection film (antireflection film) 13 which is a third light guide (optical means) is arranged.

The antireflection film 13 is the same as that used in the first embodiment. The description of the antireflection film 13, the reflective liquid crystal cell 10, and the front light system 51 will be omitted because they have been described in the second and eleventh embodiments.

In the present embodiment, the antireflection film 13 has the third light guide in addition to the light guide 24 which is the first light guide and the light guide 40 which is the second light guide. It functions as a body.

When the antireflection film 13 is not formed, the light from the inclined portion 22 formed on the interface 23 (first emission surface) of the first light guide 24 is the second light guide. About 4% is reflected by the bottom surface (second surface) 42 of 40 to become reflected light. Inclined portion 22 formed by this reflected light
Image and the inclined portion 22 of the light guide 24 interfere with each other, and as a result, the interface 28 of the light guide 24.
The unevenness of the luminance distribution occurs on the (second emission surface).

Therefore, the reflective LC according to the present embodiment
In D, the same antireflection film 13 as in Embodiment 11 is arranged between the bottom surface 42 of the second light guide 40 and the surface of the reflective liquid crystal cell 10 on the display surface side. The arrangement of the antireflection film 13 can effectively suppress the generation of the reflected light. Therefore, it is possible to realize a reflective LCD that suppresses unevenness in the luminance distribution at the interface 28 and can realize high-quality display.

The antireflection film 13 is used as a reflection type LCD.
Comparing the case of arranging with No. and the case of not arranging, as shown in FIGS. 50 (a) and (b), as compared with FIG.
FIG. 50A showing the luminance distribution in the case where the antireflection film 13 is arranged has a luminance peak pitch p that is substantially equal over the entire bottom surface 42 of the second light guide 40 and a luminance peak. The unevenness of the luminance distribution is reduced due to the gentle slope. Therefore, it can be seen that the state of the brightness distribution is improved. Note that the measurement conditions at this time have been described in Embodiment 2 above with reference to FIG.

The antireflection film 13 has a second
The antireflection film 13 is adhered with an adhesive having a refractive index n4 which is substantially equal to the refractive index n3 of the light guide 40. Therefore, the antireflection effect can be improved without substantially changing the input / output conditions of the light in the second light guide 40.

Further, the antireflection film 13 having the above structure.
As for the above, since a commercially available one can be used as it is, an increase in the manufacturing cost of the front light system 51 can be suppressed. Therefore, an inexpensive front light system 51 and a reflective LC including the same are provided.
D can be obtained.

Further, another front lighting device according to the present invention
In order to solve the above problems,
Front lighting provided and used in front of the illuminated object
In the device, the light guide is an input device that receives light from a light source.
A projecting surface and a first emitting surface that emits light toward an object to be illuminated.
And the reflected light from the illuminated object that faces the first emission surface.
And a second emission surface for emitting
The second emission surface mainly receives the light from the light source as the first emission surface.
Slope that reflects toward the
It has a shape in which flat parts that transmit light are alternately arranged.
And the projection of the inclined part on the incident surface.
Is greater than the sum of the projections of the flat part above.
It has a feature.

According to the above structure, the above-mentioned light guide body is inclined.
The sum of the projections of the parts is larger than the sum of the projections of the flat parts.
Therefore, when the entrance surface is viewed from the normal direction, the second exit surface
The sloping part of is visible. This makes it possible to
From the surface facing the entrance surface, as seen in a directional lighting device
The problem that a lot of light goes out of the light guide
Does not live As a result, the incident light from the light source is effectively used.
be able to.

The front lighting device according to the present invention has the above-mentioned configuration.
In addition, the sum of the projections of the inclined part with respect to the incident surface is
It is characterized in that it is equal to the incident surface.

According to the above construction, the sum of the projections of the inclined portion is
Since it is equal to the incident surface, when the incident surface is viewed from the normal direction,
Is visible only in the inclined portion of the second emission surface. That
Therefore, of the light incident from the incident surface, the component perpendicular to the incident surface
Are all directly incident on the inclined part and directed to the first exit surface.
And reflect. As a result, the light utilization efficiency is improved from the conventional configuration.
Can be significantly improved.

[0241]

As described above, in the front illumination device according to the present invention, the light guide body has the incident surface on which light is incident from the light source and the first emission surface on which light is emitted toward the object to be illuminated. And a second emission surface that faces the first emission surface and emits reflected light from the illuminated object, and the second emission surface is mainly reflected light from the illuminated object. A flat portion that transmits light and a slant portion that is inclined in the same direction at a constant angle with respect to the flat portion and that mainly reflects the light from the light source toward the first emission surface are alternately arranged. It has a shape, and the distance between the first emitting surface and each of the inclined portions on the second emitting surface is substantially uniform.

According to the above structure, in the light guide, the distance from the inclined portion to the first emission surface, that is, the distance to the object to be illuminated is constant. Therefore, the front illumination device of the present invention can illuminate an object to be illuminated uniformly, and can realize a bright and even high-quality display even when sufficient ambient light cannot be obtained. Produce an effect.

As described above, the other front illumination device according to the present invention has the light source and the light guide body arranged in front of the object to be illuminated, and the light guide body emits light from the light source. An incident surface on which light is incident, a first emission surface that emits light toward the object to be illuminated, and a second emission surface that opposes the first emission surface and that emits reflected light from the object to be illuminated. An emission surface, and the second emission surface, an inclined portion that mainly reflects light from the light source toward the first emission surface,
Flat portions that mainly transmit reflected light from the object to be illuminated are alternately formed, and a line that connects the portions where the inclined portions and the flat portions contact in a ridge shape is parallel to the first emission surface. It is a composition.

According to the above construction, in the light guide, the line connecting the portions where the inclined portion and the flat portion contact with each other in a ridge shape is parallel to the first emission surface. for that reason,
The front lighting device of the present invention is capable of uniformly illuminating an object to be illuminated, and even when sufficient ambient light cannot be obtained,
It is possible to realize a high-quality display that is bright and has no unevenness.

In addition to the above-mentioned structure, the front illumination device according to the present invention further suppresses reflection of light from the second emission surface on the first emission surface on the first emission surface. This is a configuration including optical means.

According to the above arrangement, since the optical means is further provided, it is possible to suppress the generation of reflected light generated by the incident light from the inclined portion being reflected by the second surface.
Therefore, it is possible to prevent interference or diffraction between the image on the inclined portion acting as the minute light source portion and the reflected image due to the reflected light. Therefore, there is an effect that it is possible to prevent the unevenness of the luminance distribution on the display observed on the observer side (the second emission surface) and the generation of the rainbow color spectrum.

The front illumination device according to the present invention has, in addition to the above structure, a structure in which the optical means is an antireflection film.

According to the above construction, since the commercially available antireflection film (antireflection film) can be used as it is as the optical means, an increase in the manufacturing cost of the front illumination device can be suppressed. Therefore, it is possible to provide an inexpensive front lighting device.

In the front lighting device according to the present invention, in addition to the above structure, the antireflection film is bonded to the light guide body with an adhesive having a refractive index substantially equal to that of the light guide body. It has a structure.

According to the above construction, the antireflection film is adhered by the adhesive having a refractive index almost equal to that of the light guide, so that the light input / output conditions in the light guide are substantially unchanged. This has the effect of improving the antireflection effect.

As described above, the reflective liquid crystal display device according to the present invention has the front illumination device having the above-mentioned configuration arranged on the front surface.

According to the above structure, since the front lighting device is arranged in front of the reflective liquid crystal display device, a reflective liquid crystal display device that can always realize a bright and high-quality display regardless of the surrounding environment is provided. There is an effect that can be done.

The reflection type liquid crystal display device according to the present invention has a structure in which, in addition to the above structure, the front illumination device is detachable.

According to the above structure, when the reflection type liquid crystal display device is used with the front illumination device turned on, the reflection type liquid crystal display device is placed in the front, and when the front illumination device is not required,
The reflective liquid crystal display device can be removed so that only the reflective liquid crystal display device is formed. This makes it possible to provide a reflection-type liquid crystal display device that can always realize a bright display without obstructing the incidence of ambient light by the front illumination device when the front illumination device is not required. Play.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a reflective LCD according to an embodiment of the present invention.

FIG. 2 is a view showing a shape of a light guide of a front light included in the reflective LCD, and FIG. 2 (a) is a plan view of the light guide seen from above in a normal direction of a flat portion. (B) is
The side view of the light guide seen from the direction normal to the incident surface, FIG.
[FIG. 3] is a cross-sectional view of the light guide body taken along a cross section whose normal line is the longitudinal direction of the light source.

3 (a) to (c) are explanatory diagrams showing the behavior of light from a light source inside a light guide.

FIG. 4 is an explanatory diagram showing a behavior of light reflected by a reflective plate of a reflective LCD.

FIG. 5 is an explanatory diagram of a measurement system for measuring the light intensity of the front light.

FIG. 6 is a graph showing a measurement result of light intensity of the front light.

FIG. 7A is an explanatory diagram showing a relationship between light emitted from the light-emitting display and ambient light, and FIG.
FIG. 4 is an explanatory diagram showing a relationship between light emitted from the reflective LCD and ambient light.

FIG. 8 is a sectional view showing a configuration of a reflective LCD according to another embodiment of the present invention.

9A is a front light system included in the reflective LCD shown in FIG. 8, in which the distance from the inclined portion of the light guide to the surface serving as the emission surface of the front light system is uniform. A cross-sectional view showing that, FIG.
For comparison, in the front light included in the reflective LCD of the above-described embodiment, it is a cross-sectional view showing that the distance from the inclined portion to the surface serving as the emission surface of the front light is not uniform.

FIGS. 10A and 10B are explanatory views showing a measurement system for measuring the luminance distribution of the illumination light according to the configurations shown in FIGS. 9A and 9B, respectively.

11A and 11B are graphs showing measurement results of the luminance distribution of illumination light with the configurations shown in FIGS. 9A and 9B, respectively.

FIG. 12 is a cross-sectional view showing a configuration of a reflective LCD according to still another embodiment of the present invention.

13 is a schematic diagram showing a behavior of light in a front light system included in the reflective LCD shown in FIG.

14 is a graph showing measurement results of luminance distribution of illumination light of the front light system included in the reflective LCD shown in FIG.

FIG. 15 is an explanatory diagram showing the principle of image blurring or blurring in a reflective LCD according to still another embodiment of the present invention.

FIG. 16 is an enlarged cross-sectional view showing a part of an inclined portion of the light guide of the reflection type LCD, showing a configuration in which a metal reflection film is provided on the inclined portion.

FIGS. 17A to 17E are cross-sectional views showing a step of forming the metal reflection film.

FIG. 18 is a schematic diagram showing a behavior of light when the metal reflection film is not provided.

19 is a cross-sectional view showing a modified example of the configuration shown in FIG.

FIG. 20 is a cross-sectional view showing a configuration of a reflective LCD according to still another embodiment of the present invention.

FIG. 21 is a schematic diagram showing a behavior of light between a light guide and an optical compensation plate in the reflective LCD.

22 shows a structure of a reflective LCD as a modified example of the structure shown in FIG. 20, and FIG. 22 (a) is a sectional view of the reflective LCD, FIG. 22 (b) and FIG. 22 (c). FIG. 3 is a cross-sectional view showing a configuration example of an optical compensation plate of this reflective LCD.

FIG. 23 is a cross-sectional view showing a configuration of a touch panel included in a reflective LCD according to still another embodiment of the present invention.

FIG. 24 is a cross-sectional view of the touch panel and a plan view of reflective electrodes provided on the touch panel.

FIG. 25 is a plan view showing a configuration for detecting coordinates of a position pressed by a pen on the touch panel.

FIG. 26 is a cross-sectional view showing a state in which a part of the touch panel is pressed by a pen.

FIG. 27 is a cross-sectional view showing a configuration of a reflective LCD according to still another embodiment of the present invention.

28 is an explanatory diagram for explaining a condition for totally reflecting the light incident from the incident surface in the inclined portion in the light guide body of the reflective LCD shown in FIG. 27.

29 is a graph showing the light-collecting characteristics of the prism sheet included in the reflective LCD shown in FIG.

30 (a) and 30 (b) are explanatory views showing another configuration example applicable to the reflection type LCD shown in FIG. 27 for limiting the spread of incident light.

31 (a) to 31 (c) are cross-sectional views showing the behavior of light in the light guide body, together with the structure of the light guide body provided in a reflective LCD according to still another embodiment of the present invention. It is a figure.

FIG. 32 is a cross-sectional view showing a configuration of a reflective LCD as still another embodiment of the present invention.

33 is an explanatory diagram for explaining a condition of a tilt angle of an incident surface of the front light of the reflective LCD shown in FIG. 32.

FIG. 34 is a perspective view showing a configuration of a reflective LCD according to still another embodiment of the present invention.

FIG. 35 is a perspective view showing a usage example of a lighting device according to still another embodiment of the present invention.

FIG. 36 is a plan view showing an example of use of the lighting device shown in FIG. 35.

FIG. 37 is a cross-sectional view showing a configuration of a reflective LCD according to still another embodiment of the present invention.

38 shows the shape of the light guide body of the front light included in the reflective LCD shown in FIG. 37, and FIG.
Is a plan view of the light guide seen from above in the normal direction of the flat portion, (b) of the figure is a cross-sectional view of the light guide seen from the direction of the normal of the incident surface, and (c) of FIG. It is sectional drawing which cut | disconnected the optical body by the cross section which makes the longitudinal direction of the light source the normal.

39 is an explanatory diagram illustrating a configuration of a flat portion and an inclined portion in the light guide body shown in FIG. 38.

FIGS. 40 (a) and 40 (b) are explanatory views showing the behavior of the light from the light source in the light guide.

41 is a graph showing the relationship between the distance from the light source and the brightness in the front light included in the reflective LCD shown in FIG. 37.

42 is a graph showing the characteristics of the angle of emitted light in the front light included in the reflective LCD shown in FIG.

43 is a cross-sectional view showing the configuration of a reflective liquid crystal cell included in the reflective LCD shown in FIG. 37.

44A to 44E are process diagrams showing a method of forming a reflective electrode in the reflective liquid crystal cell shown in FIG. 43.

45 is a graph showing the reflectance angle dependence of the reflective electrode in the reflective liquid crystal cell shown in FIG. 43.

FIG. 46 is a cross-sectional view showing another example of the reflective liquid crystal cell shown in FIG. 43.

47. Pixels in the reflective liquid crystal cell shown in FIG. 43,
It is a top view showing composition of a scanning line and a signal line.

48 is a graph showing luminance and luminance distribution characteristics of emitted light in the front light included in the reflective LCD shown in FIG. 37.

FIG. 49 is a cross-sectional view showing the configuration of a reflective LCD according to still another embodiment of the invention.

50 (a) and 50 (b) are graphs showing measurement results of luminance distribution of illumination light in a front light and a conventional front light included in the reflective LCD shown in FIG. 49, respectively.

FIG. 51 is a cross-sectional view showing a schematic configuration of a conventional reflective LCD with auxiliary illumination and a behavior of light in the reflective LCD.

FIG. 52 is a cross-sectional view showing a behavior of light in the conventional reflective LCD.

[Explanation of symbols]

10 Liquid crystal cell (reflection type liquid crystal element) 12 Liquid crystal layer 13 Antireflection film (antireflection film, optical means) 17 Reflector 18 Polarizer 19 Insulating film 20 Front light (front lighting device) 21 Flat part 22 Inclined part 23 Interface (second emission surface) 24 Light Guide (First Light Guide) 25 Incident surface 26 light source 27 Reflector (Condensing means) 28 Interface (first emission surface) 42 Bottom surface (first emission surface)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G02F 1/1335 G02F 1/1335 1/13357 1/13357 G09F 9/00 336 G09F 9/00 336B // F21Y 103: 00 F21Y 103 : 00 (72) Inventor Takeshi Ebi 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture (56) References JP-A-62-73206 (JP, A) JP-A-61-34583 (JP, A) ) JP-A-6-331823 (JP, A) JP-A-4-307515 (JP, A) Actual Kaihei 2-85422 (JP, U) JP-B-36-22835 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) F21V 8/00 G02B 5/00-6/00 G02F 1/00 F21Y 103: 00

Claims (7)

(57) [Claims] 1. A front illumination device comprising a light source and a light guide, which is arranged in front of an object to be illuminated and used, wherein the light guide has an incident surface on which light is incident from a light source and an object to be illuminated. The second emission surface includes a first emission surface that emits light toward the first emission surface and a second emission surface that faces the first emission surface and that emits reflected light from the object to be illuminated. The surface is tilted at a constant angle in the same direction with respect to the flat portion that mainly transmits the reflected light from the object to be illuminated, and mainly the light from the light source is directed toward the first emission surface. The front is characterized in that it has a shape in which reflecting inclined portions are alternately arranged, and that the distance between each of the inclined portions on the first emitting surface and the second emitting surface is substantially uniform. Lighting equipment. 2. The light source and the light source are arranged in front of the object to be illuminated.
Has a light guide, the light guide has a plane of incidence of the light from the light source,
A first emission surface for emitting light toward the object to be illuminated, to face the first light exit surface, with and a second emission surface for emitting the reflected light from the illuminated object , to the second emission surface, and primarily the inclined portion for reflecting light from the light source toward the first light exit surface, a flat portion mainly transmitting the reflected light from the <br/> illuminated object Formed alternately
The ridge-shaped portion and the flat portion are connected to each other in a ridge shape.
The front lighting device is characterized in that a line is parallel to the first emission surface . 3. The second exiting surface is formed on the first exit surface.
Suppresses reflection of light from the emission surface on the first emission surface
2. An optical means for providing the optical information according to claim 1,
Is the front lighting device described in 2. 4. The front lighting device according to claim 3, wherein the optical means is an antireflection film . 5. The antireflection film has a bending property of the light guide body.
The above-mentioned light guide is made by an adhesive having a refractive index almost equal to the bending rate.
The front lighting device according to claim 4, wherein the front lighting device is bonded to a body . 6. The front according to any one of claims 1 to 5.
Reflection, wherein Rukoto such be placed in front of the Teruaki Ho device
Type liquid crystal display device. 7. The reflective liquid crystal display device according to claim 6, wherein the front illumination device is detachable .