CN100385305C - Lighting screen and display device equipped with the lighting screen - Google Patents

Abstract

In the lighting screen and the display device equipped with the lighting screen disclosed in the present invention, the light guide body (32) has an incident surface (34), an edge (32a) formed on the side opposite to the above-mentioned incident surface (34), and emits light from the An emission surface (33) of light introduced by the incident surface (34), and an optical surface (35) having a surface opposite to the emission surface (33). The above-mentioned optical surface (35) is continuously formed by a plurality of optical elements, and each optical element directs part of the light introduced from the above-mentioned incident surface (34) toward the side of the above-mentioned edge (32a) along a small line parallel to the above-mentioned emitting surface (33). A curved surface (35a) for angular refraction, and an inclined surface (35c) for refracting light refracted on the curved surface (35a) toward the emitting surface (33) side.

Description

Lighting screen and display device equipped with the lighting screen

technical field

The present invention relates to an illuminating panel and a display device equipped with the illuminating panel, and more particularly, to an illuminating panel having a light concentrating function of concentrating and emitting incident light introduced from a light source or outside.

Background technique

For example, in a liquid crystal display device, since the liquid crystal display itself has no self-luminous ability, an illuminating panel is arranged as a rear light on the back side of the liquid crystal display. FIG. 24 is a partial side view showing an example of such a conventional liquid crystal display device. This liquid crystal display device has a liquid crystal display panel 1 and an illumination panel 11 arranged on the back side opposite to the front surface on the viewing side.

The structure of the liquid crystal display screen 1 is that the surface side glass substrate 2 and the back side glass substrate 3 are pasted through a nearly square sealing material (not shown), and liquid crystals (not shown) are sealed in the space surrounded by the two glass substrates 2, 3 and the sealing material. As shown in the figure), the front side polarizing plate 4 is pasted on the surface of the front side glass substrate 2, and the back side polarizing plate 5 is pasted on the back side of the back side glass substrate 3.

The lighting panel 11 has a light guide plate 12 provided on the back side of the liquid crystal display 1 . The light guide plate 12 is a plane square shape, and the surface opposite to the liquid crystal display 1 is used as the emission surface 13 of the emitted light, and a predetermined end surface (left end surface in FIG. 24 ) is used as the incident surface 14 of the incident light. The back surface of 13 is an inclined surface 15 inclined so that the thickness of the light guide plate 12 becomes gradually thinner as it goes from the incident surface 14 side to the edge 12a side opposite to the incident surface 14 side.

A reflection plate 16 is attached to the inclined surface 15 of the light guide plate 12 . A cold cathode tube (light source) 17 is provided at a position facing the incident surface 14 of the light guide plate 12 . One end of the reflective sheet 18 covering the cold cathode tube 17 is attached to the surface of the light guide plate 12 on the incident surface 14 side, and the other end is attached to the back of the reflector 16 on the incident surface 14 side.

The light emitted from the cold cathode tube 17 and the light reflected by the reflective sheet 18 enter the incident surface 14 of the light guide plate 12 . The incident light travels from the incident surface 14 side to the edge 12a side in the light guide plate 12 (light guide), is reflected by the reflection plate 16, is emitted from the emission surface 13 of the light guide plate 12, and is incident on the inside of the liquid crystal display 1, from which The liquid crystal display 1 is illuminated from the inside side. Thus, image light corresponding to display driving of the liquid crystal display 1 is emitted from the surface of the liquid crystal display 1 .

However, in the conventional liquid crystal display device described above, the amount of light emitted from the emitting surface 13 of the light guide plate 12 can be made uniform, and the brightness distribution emitted from the surface of the liquid crystal display 1 can be made uniform. Next, this will be described. On the inclined surface 15 of the light guide plate 12, a plurality of dot-like dimming patterns of black ink are set so that the density of the dot-like black patterns gradually becomes smaller as the distance from the incident surface 14 decreases, in other words, it is proportional to the distance from the incident surface 14 , the absorption rate of incident light decreases.

That is, in the vicinity of the cold cathode tube 17, since the intensity of the light reflected by the reflection plate 16 of the light guide plate 12 and emitted from the emission surface 13 to the liquid crystal display panel 1 is high, in order to increase the absorption of the light reflected by the reflection plate 16, The density of the black patterns formed on the inclined surface 15 of the light guide plate 12 increases, but as the distance away from the cold cathode tube 17, the intensity of the light reflected by the reflector 16 decreases, so in order to make the absorptivity gradually smaller, it gradually decreases in The density of the black patterns formed on the inclined surface 15 of the light guide plate 12 makes the intensity of the light emitted from the emitting surface 13 of the light guide plate 12 uniform on the entire surface.

However, in the above-mentioned conventional liquid crystal display device, since a plurality of dot-shaped dimming patterns of black ink are provided on the inclined surface 15 of the light guide plate 12, light is absorbed by the dimming patterns, and the light utilization efficiency is poor, and the brightness is reduced.

content of the invention

Therefore, an object of the present invention is to provide a lighting panel with high light utilization efficiency and a display device using the lighting panel.

In this invention, an optical surface formed by connecting a plurality of optical elements is provided on the light guide plate. A curved surface that reflects at an angle, and an inclined surface that refracts light refracted on the curved surface toward the above-mentioned emitting surface side.

According to this invention, by using the curved surface formed on the light guide plate and the optical surface having the inclined surface, the light introduced from the incident surface can be fully reflected on the emission surface side of the light guide plate at the terminal side far from the incident surface of the light guide plate, so that Improve light utilization efficiency.

Description of drawings

FIG. 1 is a side view of main parts of a liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating an optical surface of the light guide plate shown in FIG. 1 .

FIG. 3 is a diagram illustrating refraction of light incident from an incident surface of the light guide plate having the optical surface shown in FIG. 2 .

FIG. 4 is a view explaining the reflection effect of the optical surface of the light guide plate having the optical surface shown in FIG. 2 .

FIG. 5 is a diagram explaining the transmissive action of light on which perpendicular light is incident on a transmissive and diffuser plate instead of the diffuser plate shown in FIG. 1 .

FIG. 6 is a diagram explaining the light transmission effect when oblique light is incident on a transmission and diffusion plate instead of the diffusion plate shown in FIG. 1 .

FIG. 7 is a diagram illustrating light emitted from a light emitting surface of the light guide plate having the optical surface shown in FIG. 2 .

Fig. 8 is a side view of a main part of a liquid crystal display device according to Example 2 of the present invention.

FIG. 9 is an enlarged side view showing Modification 1 of the optical sheet shown in FIG. 8 .

FIG. 10 is an enlarged side view showing Modification 2 of the optical sheet shown in FIG. 8 .

FIG. 11 is an enlarged side view showing Modification 3 of the optical sheet shown in FIG. 8 .

FIG. 12 is an enlarged side view showing Modification 4 of the optical sheet shown in FIG. 8 .

FIG. 13 is an enlarged side view showing Modification 5 of the optical sheet shown in FIG. 8 , illustrating another fourth example of the optical sheet.

Fig. 14 is a side view of main parts of a liquid crystal display device according to Example 3 of the present invention.

Fig. 15 is a side view of a main part of a liquid crystal display device according to Embodiment 4 of the present invention.

FIG. 16 is a diagram illustrating a state in which light incident on the light guide plate from a point light source is emitted from a virtual plane Q. FIG.

Fig. 17 is a partial schematic perspective view illustrating a liquid crystal display device according to Embodiment 5 of the present invention.

FIG. 18 is a diagram illustrating a state in which light incident on a light guide plate from a point light source is emitted from a virtual plane Q in the embodiment shown in FIG. 17 .

Fig. 19 is a side view of main parts of a liquid crystal display device according to Embodiment 6 of the present invention.

Fig. 20 is a diagram for explaining the action of the light-condensing sheet shown in Fig. 19 .

Fig. 21 is a diagram showing Modification 1 of the lighting panel shown in Fig. 19 .

Fig. 22 is a diagram showing Modification 2 of the lighting panel shown in Fig. 19 .

Fig. 23 is a partial schematic perspective view illustrating a liquid crystal display device according to Embodiment 5 of the present invention.

Fig. 24 is a partial side view of an example of a conventional liquid crystal display device.

Detailed ways

<First embodiment>

FIG. 1 is a side view showing main parts of a liquid crystal display device according to Embodiment 1 of the present invention. This liquid crystal display device includes a liquid crystal display panel 21 , an illuminating panel 31 arranged on the back side opposite to the viewing side surface, and a diffuser plate 41 arranged between the two panels 21 , 31 .

The structure of the liquid crystal display panel 21 is that the front side glass substrate 22 and the back side glass substrate 23 are pasted through a nearly square sealing material (not shown), and the space enclosed by the two glass substrates 22, 23 and the sealing material is sealed with liquid crystal ( not shown), the front side polarizing plate 24 is pasted on the front side glass substrate 22 , and the back side polarizing plate 25 is pasted on the back side of the back side glass substrate 23 .

The liquid crystal display 21 can be any one of effective matrix shape, simple matrix shape, fan shape, etc., and its display mode can be TN (twisted nematic) mode, STN (super twisted nematic) mode, ECB (birefringence effect) mode, dynamic scattered effect mode , the method of using a ferroelectric liquid crystal, etc., as long as it is a method of controlling the transmittance of light.

The lighting panel 31 has a light guide plate 32 provided on the back side of the liquid crystal display 21 . The light guide plate 32 is a plane square shape, and the surface opposite to the liquid crystal display 21 is used as the emission surface 33 of the emitted light, and a predetermined end surface (the left end surface in FIG. 1 ) is used as the incident surface 34 of the incident light. The surface opposite to the surface 33 serves as the optical surface 35 . In addition, let the surface which opposes the incident surface 34 be the edge 32a. As shown in FIG. 1 , the optical surface 35 as a whole has the thickness of the light guide plate 32 by bending the inner side of the emitting surface 33 to the side of the light guide plate 32. Basically, it gradually becomes thicker and then gradually becomes thinner as the side of the incident surface 34 moves toward the side of the edge 32a. The shape of the so-called ship-bottom shape and the shape of its optical surface are the greatest features of the present invention, and will be described in detail later.

A reflective layer 36 is formed on the optical surface 35 of the light guide plate 32 . A cold cathode tube 37 serving as a light source is provided at a position facing the incident surface 34 of the light guide plate 32 . One end of the reflective sheet 38 covering the cold cathode tube 37 is attached to the surface of the light guide plate 32 on the incident surface 34 side, and the other end is attached to the back of the reflector 36 on the incident surface 34 side.

Next, the optical surface 35 of the light guide plate 32 will be described based on FIG. 2 . Optical surface 35 is a surface on which a plurality of optical elements are continuously provided in the order of curved surface 35a, flat surface 35b, and inclined surface 35c from incident surface 34 (left side in FIG. 2 ) toward edge 32a. The plane 35b becomes a plane parallel to the emission surface 33 .

The length of a group of optical elements composed of the curved surface 35a, the flat surface 35b and the inclined surface 35c is about 20-500 μm. If it becomes larger gradually as it is farther away from the incident surface 34, the penetration efficiency becomes better. corresponding effects can be obtained.

The plane 35b is a plane parallel to the emission surface 33 . The inclination angle of the flat surface 35b with respect to the inclined surface 35c is the same, and is set to an appropriate angle within a range of about 40 to 50°. The height H of the inclined surface 35 c relative to the flat surface 35 b gradually increases as the distance from the incident surface 34 increases. The typical height H of the inclined surface 35 c is about 20 to 50 μm at most, but it is set to an appropriate value according to the planar size of the light guide plate 32 and is not limited thereto.

The curved surfaces 35a have the same length. The length of the plane 35 b gradually becomes shorter as it gets away from the incident surface 34 . That is, the height H of the inclined surface 35 c increases in proportion to the distance from the incident surface 24 , and the length of the flat surface 35 b becomes shorter in proportion to the distance from the incident surface 34 . Therefore, reflected (refracted) at the inclined surface 35c, the amount of light toward the emitting surface 33 increases exponentially in proportion to the distance from the incident surface 34 .

Each optical element is arranged in the order of curved surface 35a, plane 35b and inclined surface 35c from the incident surface 34 side of light guide plate 32, and the inclined surface of the optical element adjacent to its incident surface 34 side (the left side of Fig. 2) of its curved surface 35a 35c continuous setting. The curved surface 35a is not limited, but typically the cross section of the curved surface is arc-shaped, and the radius of curvature thereof is, for example, about 0.1 to 2.0 mm. In this way, the curved surface 35a is inclined downward to the right in FIG. 2 .

Here, as an example, the height H of the nth inclined surface 35c from the incident surface 34 side to the plane 35b is an(n+1)/2 (wherein, a is an arbitrary number, n is a natural number, and the initial height of the incident surface 34 side is The inclined surface 35c is 1). Like this, the brightness uniformity of the emission surface 33 can be realized by making the height H of the inclined surface 35c to the plane 35b gradually larger as it moves away from the incident surface 34. As mentioned above, as shown in FIG. 1, the optical surface 35 becomes The boat-bottom shape in which the thickness of the light guide plate 32 gradually becomes thicker from the incident surface 34 side to the edge 32 a side and then gradually becomes thinner is also for improving the brightness uniformity of the emitting surface 33 .

In FIG. 1 , the angle of the emitting surface 33 with respect to the incident surface 34 is generally 90°. However, in order to obtain better light extraction efficiency, the angle may also be slightly smaller than 90°. That is, if the light incident on the light guide plate 32 from the incident surface 34 goes straight, and is directly reflected on the inclined surface 35c of the incident surface 34 and the opposite optical surface 35, only this area becomes bright, and other areas become dark. The incident light travels while repeatedly reflecting on the curved surface 35 a and the flat surface 35 b of the emitting surface 33 and the optical surface 35 . If the incident surface 34 has a certain angle with respect to the emitting surface 33 , the light extraction efficiency can be improved. Usually, this angle is greater than 80° and less than 90°, but it can also be less than 100° and less than 90°. The ratio of reflections is sufficient.

The light guide plate 32 with the above structure can be manufactured by emission compression molding made of transparent resin such as acrylic resin with good light penetration. In addition, the reflective layer 36 shown in FIG. 1 can be bent and pasted on the optical surface 35 of the light guide plate 32 along the shape of the metal foil made of Al, Ag, Cr, etc., but it can also be formed by sputtering or vapor deposition. On the optical surface 35 of the light guide plate 32, a metal film such as Al, Ag, Cr, etc. is formed. The edge 32a of the light guide plate 32 is preferably as thin as possible to prevent light leakage, and a reflective layer may be formed on the outside if necessary.

Here, since the liquid crystal display device of this embodiment is a transmissive and reflective type, first, the function of the light guide plate 32 when it is adopted as a transmissive type will be described with reference to FIG. 3 . Wherein, the thickness of the light guide plate 32 in FIG. 3 is appropriate, and the reflective layer 36 shown in FIG. 1 is omitted.

When the liquid crystal display device of this embodiment is adopted as a transmissive type, light incident on the incident surface 34 shown in FIG. The light indicated by the arrow A is reflected on the inclined surface 35c, the angle is converted into a direction almost perpendicular to the emitting surface 33, and emitted from the emitting surface 33 in a direction almost perpendicular.

The light indicated by the arrow B is reflected on the emission surface 33 and enters the curved surface 35a. At this time, the curved surface 35a is not parallel to the emitting surface 33, and is inclined to the lower right in FIG. Therefore, the light indicated by the arrow B enters the inclined surface 35c that is blocked by the curved surface 35a for reflection.

In this way, the curved surface 35a that descends toward the side opposite to the incident surface 34 is provided on the optical element in order to make the traveling direction of the light of the arrow B reflected on the curved surface 35a of each optical element close to the direction parallel to the plane 35b of the same group and reliably enter to the same set of inclined surfaces 35c. Next, the light incident on the inclined surface 35 c is reflected by the inclined surface 35 c, the angle is converted to a direction substantially perpendicular to the emission surface 33 , and emitted from the emission surface 33 in a direction substantially perpendicular.

The light indicated by arrow C travels in the direction from the incident surface 34 side to the edge 32a side in the light guide plate 32 through reflection on the plane 35b and repeated reflection on the emission surface 33 , that is, the right direction in FIG. 3 . Then, the advancing light is finally the same as the light shown by the arrow A, and is emitted from the emitting surface 33 reflected on the inclined surface 35c in an almost vertical direction, or the same as the light shown by the arrow B, after being reflected by the curved surface 35a, it is The same group of inclined surfaces 35c reflects and emits from the emitting surface 33 in a substantially vertical direction.

In this way, the light shown by the arrows A, B, and C is finally reflected on a certain inclined surface 35c, and emitted from the emission surface 33 in a substantially vertical direction. At this time, the height H of the inclined surface 35c of each optical element relative to the flat surface 35b gradually increases from the incident surface 34 side to the edge 32a side shown in FIG. 1 . Accordingly, the area of the inclined surface 35c gradually increases from the incident surface 34 side to the edge 32a side. In this way, even if the amount of light decreases as the distance from the incident surface 34 increases, the amount of light emitted from the emitting surface 33 becomes uniform because the area of the inclined surface 35c becomes larger.

Next, the function of the illuminating panel 31 when the liquid crystal display device shown in FIG. 1 is adopted as a reflective type will be described.

As shown as representative arrows D, E, F in FIG. 4 , external light is incident on the emission surface 33 . At this time, refraction at the emitting surface 33 is ignored. In addition, the external light indicated by arrows D, E, and F are mutually parallel lights, and are incident on the emission surface 33 at an incident angle d from the upper right to the lower left in FIG. 4 .

In addition, the external light shown by the arrow D is reflected on the plane 35b (actually, at the part corresponding to this position of the reflective layer 36, but for the sake of simplicity of description, the position of the light guide plate 32 is used for description. Hereinafter, the same is true for other positions. .) reflection, emitted from the emitting surface 33. At this time, the reflection on the plane 35b is regular reflection. Therefore, the external light indicated by the arrow D enters the plane 35b at an incident angle d, and is reflected at a reflection angle d, and the reflection angle is 2d.

External light indicated by arrow E is reflected on the right side in FIG. 4 on the curved surface 35 a and is emitted from the emitting surface 33 . At this time, the curved surface 35a is inclined to the lower right in FIG. 4, and the reflection angle k on the curved surface 35a is smaller than the reflection angle 2d on the flat surface 35b.

The light indicated by the arrow F is reflected on the left side in FIG. 4 in the curved surface 35 a, and is emitted from the emission surface 33 . At this time, the curved surface 35a is inclined to the lower right in FIG. The angle f is smaller than the reflection angle e on the right side of the curved surface 35a.

Like this, in Fig. 4, from the upper right to the lower left, the external light shown in the arrows D, E, and F shown in the arrows D, E, and F that are incident on the emission surface 33 in parallel is reflected, or is reflected at a reflection angle smaller than the reflection angle during the regular reflection and is emitted from the emission surface. Face 33 launches. At this time, the angle of reflection at the curved surface 35a gradually decreases as it goes to the left in FIG. Taper to the left.

Thereby, even if the external light shown by the arrows D, E, and F incident to the emitting surface 33 is parallel to each other, the external light shown by the arrows D, E, and F emitted from the emitting surface 33 is in the direction perpendicular to the emitting surface 33. The slightly left side of Figure 4 focuses the light.

Next, a case where the liquid crystal display device shown in FIG. 1 is adopted as a transmissive type will be described. When the cold cathode tube 37 is turned on, the light emitted from the cold cathode tube 37 and the light emitted from the reflective sheet 38 enter the incident surface 34 of the light guide plate 32 . This incident light travels within the light guide plate 32 as indicated by representative arrows A, B, and C in FIG. 3 .

Next, as described above, the light indicated by the arrows A, B, and C is finally reflected on a certain inclined surface 35c, and emitted from the emission surface 33 in a substantially vertical direction. Therefore, almost all of the light incident on the incident surface 34 is finally reflected on a certain inclined surface 35c, and emitted from the emitting surface 33 in a substantially vertical direction.

At this time, as shown in FIG. 2 , the height H of the inclined surface 35 c relative to the flat surfaces 35 b of the same group gradually increases from the incident surface 34 side to the edge 32 a side. Accordingly, the area of the inclined surface 35c gradually increases from the incident surface 34 side to the edge 32a side.

In this way, even if the amount of light decreases as the distance from the cold cathode tube 37 increases, the amount of light emitted from the emitting surface 33 becomes uniform because the area of the inclined surface 35c becomes larger. At this time, almost all the light incident on the incident surface 34 is reflected on a certain inclined surface 35c, and emitted from the emitting surface 33 in a nearly vertical direction, so that the light utilization efficiency is high, and the brightness can be improved.

The light emitted from the emitting surface 33 of the light guide plate 32 in a substantially vertical direction penetrates the diffuser plate 41 and diffuses, and enters the back of the liquid crystal display 21 , and illuminates the liquid crystal display 21 from the back side. Thus, image light corresponding to the display driving of the liquid crystal display 21 is emitted from the surface of the liquid crystal display 21 .

As described above, when the liquid crystal display device shown in FIG. 1 is adopted as a transmissive type, the light utilization efficiency of the illuminating panel 31 is high, the luminance can be increased, and the luminance can be made uniform, so that the display quality can be improved.

On the other hand, when this liquid crystal display device is adopted as a reflective type, external light is utilized without lighting the cold cathode tube 37 . That is, external light incident on the surface of the liquid crystal display 21 from its front side penetrates the liquid crystal display 21 , diffuses while passing through the diffusion plate 41 , enters the emitting surface 33 of the light guide plate 32 , and is reflected by the reflector 36 .

Contrary to the above, the reflected light is emitted from the emitting surface 33 of the light guide plate 32 , diffuses while passing through the diffusion plate 41 , enters the back of the liquid crystal display 21 , and illuminates the liquid crystal display 21 from the back side. Thus, image light corresponding to the display driving of the liquid crystal display 21 is emitted from the surface of the liquid crystal display 21 .

Here, a case where this liquid crystal display device is actually adopted as a reflective type will be described. In the actual use state, when the upper end side of the screen of the liquid crystal display 21 is located at the right end side of FIG. The picture of 21 is positive, that is, the direction perpendicular to the picture, or the direction slightly below (the left side in FIG. 1 ) to watch the picture.

Therefore, if the liquid crystal display screen 21 is tilted in order to mainly obtain the external light from upper right to lower left as shown in FIG. As shown, it is incident on the emitting surface 33 of the light guide plate 32 . Refraction at the emission surface 33 is also neglected here. In addition, the external lights indicated by arrows D, E, and F are mutually parallel lights.

The external light shown by the arrows D, E, and F incident on the emitting surface 33 of the light guide plate 32 is reflected or reflected at a reflection angle smaller than the reflection angle during the regular reflection as described above, and emitted from the emitting surface 33. . At this time, the angle of reflection at the curved surface 35a gradually decreases as it goes to the left in FIG. Going to the left gradually becomes smaller.

Therefore, even if the external light shown by the arrows D, E, and F incident on the emitting surface 33 is parallel to each other, the external light shown by the arrows D, E, and F emitted from the emitting surface 33 is in the direction perpendicular to the emitting surface 33. The slightly left side of 4 spotlights. Then, if these external lights pass through the diffuser plate 41 and the liquid crystal display 21 as they are, the image light will gather in the direction of the screen of the liquid crystal display 21, that is, slightly below the vertical screen direction (left side in FIG. 1 ). light and emit.

Like this, when this liquid crystal display device is actually adopted as a reflective type, based on the external light from the upper right to the lower left of FIG. The direction of the left side in Fig. 1) condenses light and emits image light. At this time, the emission direction of the image light is the viewing direction, so that a brighter image can be obtained.

The diffusion plate 41 improves the in-plane uniformity of transmitted light and reflected light both when it is adopted as a transmissive type and when it is adopted as a reflective type, so as to adjust the viewing angle. Used to alleviate double-mapping.

In addition, when the filling material is used to make the surface of the diffuser plate 41 into a convex-convex shape, the incident angle and incident range of the external light taken in by the convex-concave shape can be extended to all directions, and the double reflection can be further reduced due to the high diffusivity. .

In addition, instead of using the diffusion plate 41, a filler having a refractive index different from that of the adhesive may be mixed into the adhesive for bonding the rear polarizing plate 25 of the liquid crystal display 21 to the rear glass substrate 23, so that the adhesive has Diffusion function. Alternatively, an adhesive having such a diffusion function may be used, and the diffusion plate 41 may be used.

In addition, a penetrating and diffusing plate 42 shown in FIG. 5 may be used instead of the general diffusing plate 41 . The transmissive and diffuser plate 42 is constituted by alternately arranging transmissive layers 43 made of a colorless transparent resin or the like and diffusion layers 44 made of a white transparent resin or the like.

At this time, the thickness of the penetrating and diffusing plate 42 is constant, but both the penetrating layer 43 and the diffusing layer 44 face the same direction (in this case, from the upper right side to the lower left side in FIG. 5 ) with respect to the penetrating and diffusing plate 42. tilt. In addition, in FIG. 5 , the upper right portion of the diffusion layer 44 and the lower left portion of the diffusion layer 44 on the right side are connected or overlapped in the right direction.

As shown in FIG. 3 , when adopted as a penetrating type, the light emitted from the emitting surface 33 of the light guide plate 32 in an almost vertical direction is shown by the arrow in FIG. Refraction), diffuse in the diffusion layer 44 of the penetration and diffusion plate 42 and emit from the surface of the transmission and diffusion plate 42.

At this time, since the upper right portion of the diffusion layer 44 in FIG. 5 and the lower left portion of the diffusion layer 44 on the right side are connected or overlapped in the left and right directions, all the light emitted from the emission surface 33 of the light guide plate 32 in an almost vertical direction Diffusion is ensured in one of the diffusion layers 44 of the penetration and diffusion plate 42 .

On the other hand, when it is adopted as a reflective type, as shown by the solid line arrow in FIG. The penetration layer 43 of the diffuser plate 42 .

The transmitted light is reflected on the optical surface 35 of the light guide plate 32 as indicated by the arrows in FIG. 4 . This reflected light is shown by the dotted line arrow in Fig. 6 (ignoring the refraction of the inside and the surface of the penetration and diffusion plate 42.), diffuses in the diffusion layer 44 of the penetration and diffusion plate 42, and from the penetration and diffusion plate 42 surface emission.

At this time, also because the upper right part of the diffusion layer 44 and the lower left part of the diffusion layer 44 on the right side in FIG. A certain diffusion layer 44 of the diffusion plate 42 diffuses reliably.

Here, the optical surface 35 of the light guide plate 32 is not limited to the optical surface shown in FIG. 2 . For example, referring to FIG. 2 , the inclination angle of the plane 35b to the inclined surface 35c of each optical element is in the range of about 40° to 50°, and gradually increases from the incident surface 34 side to the edge 32a side.

In addition, the length of each optical element which consists of the curved surface 35a, the flat surface 35b, and the inclined surface 35c may differ. For example, by making the lengths of the curved surface 35a and the flat surface 35b constant and the height H of the inclined surface 35c different, the lengths of a set of optical elements composed of the curved surface 35a, the flat surface 35b, and the inclined surface 35c are made different. However, at this time, the length of one set of optical elements constituted by the curved surface 35a, the flat surface 35b, and the inclined surface 35c is in the range of about 20 to 500 μm.

However, the light shown by the arrows A, B, and C is finally reflected on a certain inclined surface 35c, and the light emitted from the emitting surface 33 in an almost vertical direction is not almost all the light incident on the incident surface 34 shown in FIG. , but part of it. That is, part of the light reflected on the curved surface 35 a and the flat surface 35 b is emitted from the emission surface 33 as it is.

Therefore, as shown by the one-dot dash line in Fig. 7, in the virtual plane P that is all vertical to the emission surface 33 and the incident surface 34 of the light guide plate 32, the light reflected on the inclined surface 35c is as shown by the solid line arrow, from the emission surface 33 The part of the light emitted in the almost vertical direction, but reflected by the curved surface 35a and the flat surface 35b, is emitted from the emitting surface 33 of the light guide plate 32 in a laterally inclined direction away from the incident surface 34 as indicated by the dotted arrow.

Thereby, almost all the light incident on the incident surface 34 can be emitted from the emitting surface 33, and good light utilization efficiency can be obtained. In addition, according to the difference in the area of the inclined surface 35c, it can be reflected on the inclined surface 35c and emitted from the emitting surface 33. The amount of light emitted is uniform. But, as shown by the dotted arrow in Fig. 7, there is light emitted from the emitting surface 33 of the light guide plate 32 toward the side oblique direction away from its incident surface 34, if the light is gathered, the peak brightness of the front of the liquid crystal display 21 Larger, the light utilization efficiency can be further improved. An embodiment is shown below that can collect light emitted from the emitting face 33 of the light guide plate 32 in a laterally oblique direction away from the incident face 34 thereof.

Example 2

Fig. 8 is a side view showing main parts of a liquid crystal display device according to Embodiment 2 of the present invention. Similar to the first embodiment, this liquid crystal display device has a liquid crystal display panel 21 and an illumination panel 31 disposed on the back side opposite to the viewing side surface. However, between the liquid crystal display panel 21 and the illumination panel 31 of this embodiment, an optical sheet 51 is disposed instead of the diffusion plate 41 of the first embodiment. The characteristic of this embodiment is the function of the optical sheet 51, and the following description will focus on the characteristic part. In addition, in the following description, the same reference numerals are assigned to the same constituent elements as those in Embodiment 1, and description thereof will be omitted.

The optical thin plate 51 is rectangular in plan, and the surface opposite to the liquid crystal display 21 is a plane 52 , and the inner surface opposite to the plane 52 is an optical surface 53 . The optical surface 53 is composed of two inclined surfaces 53b, 53d of grooves having a substantially trapezoidal cross-section formed at regular intervals, a flat surface 53a on the upper side, and a flat surface 53c between the two grooves. That is, the optical surface 53 is a surface on which a plurality of optical elements including a flat surface 53a, an inclined surface 53b, a flat surface 53c, and an inclined surface 53d are successively provided sequentially from the incident surface 34 side to the edge 32a side of the optical plate 32. The shape of the optical surface 53 is completely the same in the vertical direction as that of the paper of FIG.

The planes 52 , 53 a , and 53 c are planes parallel to the emission surface 33 of the light guide plate 32 . The angle of inclination with respect to the plane 52 (the plane parallel to the light-emitting surface 33 of the light guide plate 32 ) of the inclined plane 53 b is the same, and the plane 52 is almost perpendicular to the plane 52 or an inclined plane close to the vertical plane. The inclination angle of the inclined surface 53d with respect to the plane 52 is the same, and is set to an appropriate angle within a range of about 30° to 50°.

The length of a group of optical elements composed of the plane 53a, the inclined surface 53b, the plane 53c and the inclined surface 53d is almost the same as the pixel pitch of the liquid crystal display 21, or one of the integer parts of the same pixel pitch. The optical sheet 51 having the above-mentioned structure can be manufactured by emission compression molding using a transparent resin having good light penetration such as acrylic resin as a material.

The optical sheet 51 has the function of concentrating the light emitted obliquely from the emitting surface 33 of the light guide plate 32 toward the edge 32 a on the front side of the liquid crystal display 21 . Next, the function of the optical sheet 51 will be described with reference to FIG. 9 . Light emitted from the emitting surface 33 of the light guide plate 32 shown in FIG. 8 penetrates the optical sheet 51 as indicated by arrows J, K, and L in FIG. 9 . Wherein, the light shown by arrows J and K, as shown by the solid line arrows in FIG. The optical sheet 51 emits from the plane 52 of the optical sheet 51 in a nearly vertical direction.

As shown by the dotted arrow in Figure 7, the light shown by the arrow L is emitted in an oblique direction from the incident surface 34 side toward the edge 32a side from the emitting surface 33 of the light guide plate 32, and is incident on the inclined surface 53b of the optical thin plate 51. 53d is reflected, the angle is changed to a nearly vertical direction on the plane 52 of the optical thin plate 51, and emitted from the plane 52 of the optical thin plate 51 to the vertical direction.

In this way, light indicated by arrows J, K, and L is emitted from the plane 52 of the optical sheet 51 in a direction substantially perpendicular thereto. Therefore, most of the light incident on the incident surface 34 of the light guide body 32 is finally emitted from the plane 52 of the optical sheet 51 in an almost vertical direction. As a result, the peak luminance of the front surface of the liquid crystal display 21 can be increased, and good light utilization efficiency can be obtained.

However, if described with reference to FIG. 9, the optical surface 53 of the optical thin plate 51 preferably has flat surfaces 53a, 53c for passing the light shown by the arrows J and K as they are, and inclined surfaces for the light shown by the incident arrow L. 53b and an inclined surface 53d for reflecting the incident light indicated by the arrow L. Thereby, the optical surface 53 of the optical thin plate 51, for example as shown in FIG. and the surface of the inclined surface 53d.

For example, as shown in FIG. 12, the inclined surface 53d for reflecting light incident on the inclined surface 53b may be an arcuate curved surface. In this case, since the light reflected by the inclined surface 53d can be collected and emitted from the plane 52 in a direction almost perpendicular thereto, the peak luminance of the front surface of the liquid crystal display 21 can be further increased.

For example, as shown in FIG. 13 , the surface indicated by reference numeral 53a may be an inclined surface whose inclination angle with respect to the plane 53c (the surface parallel to the emitting surface 33 of the light guide plate 32 ) is less than about 20°. For example, if the inclination angle of the plane 53c to the inclined surface 53a is set to 20°, and the refractive index of the optical sheet 51 (its material is acrylic resin) is set to 1.49, as shown by the arrow in FIG. The light emitted from the emitting surface 33 of the light plate 32 in a direction perpendicular thereto and incident on the inclined surface 53 a is emitted from the flat surface 52 at an angle θ (10.06°) to the perpendicular thereto. In addition, if the angle θ=±10° is defined as a substantially vertical direction, the inclination angle of the inclined surface 53a with respect to the plane 53c may be smaller than about 20°.

Next, a case where the liquid crystal display device shown in FIG. 9 is adopted as a transmissive type will be described. If the cold cathode tube 37 is turned on, the light emitted from the cold cathode tube 37 and the light reflected by the reflective sheet 38 are incident on the incident surface 34 of the light guide plate 32, travel in the light guide plate 32, and reflect on the optical surface 35 of the light guide plate 32 .

As shown by the solid line arrow in FIG. 7 , the part of the reflected light reflected from the optical surface 35 of the light guide plate 32 is emitted from the emitting surface 33 to a direction almost perpendicular thereto, as shown in FIG. 9 as representative arrows J and K, Portions that pass through the flat surfaces 53 a and 53 c of the optical sheet 51 as they are are emitted from the flat surface 52 of the optical sheet 51 in a direction almost perpendicular thereto.

As shown by the dotted arrow in FIG. 7 , most of the remaining reflected light reflected on the optical surface 35 of the light guide plate 32 is emitted from the emitting surface 33 of the light guide plate 32 toward a sideways oblique direction away from its incident surface 34 , as shown in FIG. 9 As indicated by a representative arrow L, it is incident on the inclined surface 53b of the optical sheet 51, reflected on the inclined surface 53d, and emitted from the plane 52 of the optical sheet 51 in a direction substantially perpendicular thereto.

In the case of the second embodiment, most of the light emitted from the cold cathode tube 37 and incident on the incident surface 34 of the light guide plate 32 is finally emitted from the plane 52 of the optical sheet 51 in a direction almost perpendicular thereto. At this time, as shown in FIG. 2, the height H of the inclined surface 35c increases in proportion to the distance from the incident surface 34, and the length of the plane 35b becomes shorter in proportion to the distance from the incident surface 34. The amount of light directed towards the emitting surface 33 increases exponentially in proportion to the distance from the incident surface 34 . In this way, even if the amount of light decreases as the distance from the cold cathode tube 37 decreases, since the amount of light emitted from the emitting surface 33 is uniform, the light utilization efficiency is high, and the luminance can be increased, and the luminance can also be made uniform.

Light emitted from the plane 52 of the optical sheet 51 in a direction substantially perpendicular thereto enters the back of the liquid crystal display 21 and illuminates the liquid crystal display 21 from the back side thereof. Thus, image light corresponding to the display driving of the liquid crystal display 21 is emitted from the surface of the liquid crystal display 21 .

As described above, when the liquid crystal display device shown in FIG. 8 is adopted as a transmissive type, the light utilization efficiency of the illuminating panel 31 can be improved, the luminance can be increased, and the luminance can be made uniform, so that the display quality can be improved.

On the other hand, when this liquid crystal display device is adopted as a reflective type, external light is utilized without lighting the cold cathode tube 37 . That is, external light incident on the surface of the liquid crystal display 21 from its front side penetrates the liquid crystal display 21 , passes through the optical sheet 51 , enters the emitting surface 33 of the light guide plate 32 , and is reflected on the reflective layer 36 . At this time, external light such as natural light and indoor light penetrates through the portions corresponding to the flat surfaces 53 a and 53 c of the optical sheet 41 with almost no change in angle.

Contrary to the above, the reflected light is emitted from the emitting surface 33 of the light guide plate 32, penetrates the optical sheet 51, enters the back of the liquid crystal display 21, and illuminates the liquid crystal display 21 from the back side. Thus, image light corresponding to display driving of the liquid crystal display 21 is emitted from the surface of the liquid crystal display 21 . In this case, the double reflection can be reduced by using the optical sheet 51 .

Example 3

As shown in Fig. 1 and Fig. 8, above-mentioned embodiment 1 and embodiment 2 have explained the situation that the illumination screen 31 is arranged on the inner side of liquid crystal display screen 21, but not limited to this, the implementation of the present invention as shown in Fig. 14 In Example 3, the illuminating panel 31 may be arranged on the front side of the liquid crystal display 21 .

At this time, the emitting surface 33 of the light guide plate 32 of the illuminating panel 31 is regarded as the rear side, and the optical surface 35 is regarded as the front side. In addition, a reflective layer 36 is provided on the optical surface 35 of the light guide plate 32 . Between the liquid crystal display panel 21 and the lighting panel 31, the same optical sheet 51 as in the second embodiment is disposed. In the optical thin plate 51 , its plane 52 is opposite to the liquid crystal display 21 . A flat reflector 55 is provided on the back side of the liquid crystal display panel 21 .

Next, a case where the liquid crystal display device shown in FIG. 14 is adopted as a transmissive type will be described. Once the cold cathode tube 37 is turned on, the light emitted from the cold cathode tube 37 and the light reflected by the reflective sheet 38 are incident on the incident surface 34 of the light guide plate 32 . Similar to Embodiment 2, most of the incident light is emitted from the emitting surface 33 of the light guide plate 32 and then emitted from the plane 52 of the optical sheet 51 in a direction almost perpendicular thereto.

The emitted light passes through the liquid crystal display 21 and is reflected on the emitting plate 55 . The reflected light is incident on the back of the liquid crystal display 21 and irradiates the liquid crystal display 21 from the back. Image light corresponding to display driving is emitted from the surface of the liquid crystal display panel 21 . The image light passes through the optical sheet 51 and passes through the light guide plate 32 . Thus, the penetrating image light can be seen.

On the other hand, when the liquid crystal display device shown in FIG. 14 is adopted as a reflective type, external light is used without lighting the cold cathode tube 37 . That is, external light incident on the optical surface 35 of the light guide plate 32 from its surface passes through the light guide plate 32 , passes through the optical thin plate 41 , passes through the liquid crystal display 21 , and is reflected by the reflector 55 .

The reflected light enters the back surface of the liquid crystal display panel 21 and irradiates the liquid crystal display panel 21 from the back surface side. Thus, image light corresponding to display driving is emitted from the surface of the liquid crystal display panel 21 . The image light passes through the optical sheet 51 and passes through the light guide plate 32 . Thus, the penetrating image light can be seen.

However, in the liquid crystal display device shown in FIG. 14, when it is adopted as a transmissive type and when it is adopted as a reflective type, since the light passes through the liquid crystal display panel 21 twice, the polarizing plate may be on the front side or the back side. one of. In addition, instead of using the reflector 55 , the electrodes for display pixels provided on the rear surface of the rear glass substrate 23 may be formed of reflective metal.

Example 4

The above-mentioned embodiments have described the case where a line light source such as a cold cathode tube is used as a light source, but it is not limited thereto, and a point light source such as a light emitting diode may also be used. FIG. 15 shows that one light emitting diode 51 is arranged at a position facing the longitudinal central portion of the incident surface 34 of the light guide plate 32 of the liquid crystal display device. If a plurality of light emitting diodes 51 are arranged in parallel along the longitudinal direction of the incident surface 34, the same luminance as that of a line light source can be obtained.

However, in the case of the cold-cathode tube 37 as the line light source, the light emitted from the cold-cathode tube 37 can uniformly illuminate the entire incident surface 34 of the light guide plate 32 . On the other hand, in the case of the light emitting diode 51 as a point light source, the incident surface 34 of the light guide plate 32 cannot be uniformly illuminated with the light emitted from the light emitting diode 61 .

Therefore, in the case of using the light emitting diode 61, in the imaginary plane Q shown by the one-dot dash line in FIG. Of the light emitted by the light emitting diode 61 , only the light that is vertically incident on the flat incident surface 34 is emitted in a direction perpendicular to the emitting surface 33 , and the rest of the light is emitted at an angle oblique to the virtual plane Q. That is, of the light emitted from the point light source, the light that is perpendicularly incident on other than the incident surface 34 is emitted obliquely to the left and right within the virtual plane Q as indicated by the dotted arrow.

Therefore, as shown in FIG. 15 , in the emitting surface 34 of the light guide plate 32, the luminance indicated by the label N on both sides of the area indicated by the label M almost opposite to the light-emitting diode 51 is greatly reduced, and the light utilization efficiency is poor. Furthermore, brightness unevenness occurs. As a result, display unevenness occurs on the liquid crystal display.

Therefore, Embodiment 5 of the present invention which can avoid such brightness unevenness will be described below.

Example 5

Fig. 17 is a partial schematic plan view illustrating a liquid crystal display device according to Embodiment 5 of the present invention.

The liquid crystal display device of this embodiment is basically the same as that shown in FIG. 15 , and one light emitting diode 61 is arranged at a position facing the longitudinal center of the incident surface 34 of the light guide plate 32 of the liquid crystal display device. However, in this case, the inclined surface 35c of each optical element forming the optical surface of the light guide plate 32 is a surface having a wave-like convex-concave shape in the longitudinal direction (direction parallel to the incident surface 34). As an example of the waveform shape of the inclined surface 35c of each optical element, when the amplitude is a, a sinusoidal curve with a wavelength λ of 2aπ is suitable, but not limited thereto, and the wavelength λ may be 1 to 10 times the amplitude a.

In this way, if the inclined surface 35c of each optical element has a wave shape, in the imaginary surface Q (a surface parallel to the incident surface 34 on the emission side of the emission surface 33) shown by the one-dot dash line in FIG. As shown, the light emitted from the light emitting diode 61 is not only the light that is vertically incident on the incident surface 34, but part of the light that is obliquely incident on the incident surface 34 is also perpendicularly incident on the wave-shaped inclined surface 35c of each light source element. Since the light perpendicularly incident on the inclined surface 35c is reflected in a direction perpendicular to the emitting surface 33 of the light guide plate 32, the intensity of the emitted light in the viewing direction becomes large, and the emitted light emitted from the emitting surface 33 of the light guide plate 32 uniform in strength.

In the embodiment shown in FIG. 17, the centerline of the wave-shaped inclined surface 35c formed on the light guide plate 32 is formed in a straight line parallel to the incident surface 34, but it is not limited thereto. For example, the centerline of the wave-shaped inclined surface 35c is The shape of an arc or an ellipse centered on the light source 61 can be appropriately changed. In addition, in each inclined surface 34, the phase of the wave may be shifted in the width direction of the light guide plate 34, and the pitch of the wave may be different.

Here, if we examine FIG. 18 in more detail, as indicated by the dotted arrows, the other part of the light reflected by the inclined surface 35c of each wave-shaped optical element travels obliquely to the left and right within the virtual plane Q, so only this part of the light Intensity is uneven.

Therefore, Embodiment 6 of the present invention in which light can be emitted more uniformly from the emitting surface 34 of the light guide plate 32 will be described below.

Example 6

Fig. 16 is an arrow view showing a main part of an illumination panel 31 according to Embodiment 6 of the present invention. In this illuminating panel 31 , a condensing sheet 62 is disposed between the light guide plate 32 and the optical sheet 51 , and one light emitting diode 61 is disposed at a position facing the longitudinal center of the incident surface 34 of the light guide plate 32 .

The light-condensing thin plate 62 is in the shape of a plane square, and its structure is to use the surface opposite to the light guide plate 32 as a plane 63. On this plane 6, a plurality of single-sided surfaces extending in a direction perpendicular to the incident surface 34 of the light guide plate 32 are arranged side by side. Convex lens bar portion 64 . The surface of the single-convex lens strip portion 64 may have a cross-sectional circular shape or may have a cross-sectional elliptical shape. The light concentrating thin plate 62 with such a structure can be manufactured by emission compression molding made of transparent resin such as acrylic resin with good light penetration. The light concentrating thin plate 62 can also have its flat surface 63 attached to the emitting surface 33 of the light guide plate 32 .

In Fig. 18, as shown by the solid line arrows, as shown by the dotted line arrows, the light emitted from the emitting surface 33 of the light guide plate 32 to its left and right oblique directions in the virtual plane Q is as shown by the solid line arrows in Fig. 20. The single-sided convex lens strips 64 of the sheet 62 condense light to the central side of each convex lens strip 64 and emit light in a direction almost perpendicular to the plane 63 of the light-condensing sheet 62 . That is, as shown by the solid line and dotted line arrows in FIG. 18 , the light emitted from the emitting surface 33 of the light guide plate 32 in a direction parallel to its incident surface 34 is condensed by the light-condensing thin plate 62 , and moves toward the direction parallel to the virtual plane Q within the virtual plane Q. The plane 63 of the light-condensing sheet 62 is refracted in a direction almost vertical (a direction parallel to the solid arrow).

Therefore, even if the light emitted from the light-emitting diode 61 cannot uniformly illuminate the incident surface 34 of the light guide plate 32, the light can be further uniformly emitted from the plane 63 of the light-condensing thin plate 62, and the light utilization efficiency is high, and the brightness is also uniform. As a result, occurrence of display unevenness on the liquid crystal display can be avoided. In addition, in the above, the incident surface 34 of the light guide plate 32 may have the same wave shape as the inclined surface 35c, but it is necessary to pay attention to the uniformity of the light quantity density incident on the light guide plate 32 .

On the other hand, when the liquid crystal display device having the illuminating panel 31 shown in FIG. 19 is adopted as a reflective type, since there is no vertex on the surface of the single-sided convex lens strip portion 64 of the light concentrating sheet 62, the light extraction efficiency is very good. .

FIG. 21 shows a modified example of the sixth embodiment. In this embodiment, a light concentrating portion 62A having the same structure as the light concentrating sheet 62 shown in FIG. 19 is integrally formed on the surface of the light guide plate 32 . In addition, FIG. 22 shows another modified example of the sixth embodiment. In this modified example, the optical sheet 51 is disposed between the light guide plate 32 and the condensing sheet 62 . The condensing sheet 62 and the optical sheet 51 are respectively the same as those shown in FIG. 19 .

In addition, although not shown in the figure, it is also possible to have the function of the optical thin plate 51, that is, the function of converting the light emitted from the emitting surface 33 of the light guide plate 32 toward the edge 32a in a lateral oblique direction to a direction almost perpendicular to the emitting surface 33. And, the light concentrating thin plate 62 has the function that, in the plane parallel to the incident surface 34 of the light guide plate 32 (in the plane of the virtual plane Q), the light emitted obliquely from the emission surface 33 of the light guide plate 32 is converted into The emitting surface 33 is oriented almost vertically to the functional optical film. Such an optical film is not limited to the embodiment, for example, the optical sheet 41 and the light-concentrating sheet 52 shown in FIG. 22 may be integrated in close contact with each plane.

In addition, in the cases shown in FIG. 19 , FIG. 21 and FIG. 22 , cold cathode tubes (line light sources) may be used instead of the light emitting diodes 61 . In such a case, the luminance can be further improved by utilizing the light-condensing effect of the light-condensing sheet 62 in a direction parallel to the incident surface 34 of the light guide body 32 .

In addition, when employing a light emitting diode as a light source, it is not limited to one, but a plurality of them may be arranged. At this time, even if the light emitting diode itself has dispersion, it can be identified by the wave shape of the inclined surface 35 c of the light guide plate 32 . In this case, white or full-color display can be performed as long as light-emitting diodes of each color emitting light in three primary colors are used as light-emitting diodes. Example 7 is such an example.

Example 7

23 is a longitudinal arrangement of a plurality of LEDs of different light emitting colors, for example, three LEDs 61R, 61G, and 61B emitting red, green, and blue light along the incident surface 34 of the light guide plate 32 . At this time, by appropriately dimming the three light emitting diodes 61R, 61G, and 61B, colors other than the single light emitting color of the light emitting diodes can be obtained by mixing colors.

In the case of this embodiment, full-color display can be performed without color filters by sequentially combining field-sequential drive control units that emit red light, green light, and blue light in synchronization with the driving of the liquid crystal display. That is, initially, each pixel of the liquid crystal display is driven at a level corresponding to red display data, and the light-emitting diode 61R is lighted for a certain time at the same time as this, and then each pixel of the liquid crystal display is respectively driven at a level corresponding to green display data. Drive, light the light-emitting diode 61G for a certain time with the same time as this, then, drive each pixel of the liquid crystal display with the level corresponding to the blue display data respectively, light the light-emitting diode 61B for a certain time with the same time as this, By performing so-called field sequential drive, full-color display is possible without color filters.

As described above, according to Invention 1, the light introduced from the incident surface can be sufficiently refracted to the light guide plate even at the end surface far from the incident surface of the light guide plate by using the curved surface and the optical surface having the inclined surface formed on the light guide plate. The emitting surface side, so that the light utilization efficiency can be improved.

According to the second invention, the inclined surface extending in a direction substantially parallel to the incident surface can refract the light introduced from the point light source in a direction parallel to the incident surface, so that light utilization efficiency can be improved.

According to Invention 3, since the optical thin plate converts the light emitted obliquely from the emitting surface of the light guide plate toward the edge side to a direction almost perpendicular to the emitting surface of the light guide plate, light utilization efficiency can be improved.

Claims (23)

1. liquid crystal indicator lighting screen has:

Light source (37,61);

Light conductor (32), by incident from the plane of incidence (34) of the light of above-mentioned light source (37,61) emission, at the edge (32a) that forms with the opposed side of the above-mentioned plane of incidence (34), the surface of emission (33) of the light that imports from the above-mentioned plane of incidence (34) of emission and, have optical surface (a 35) formation with opposed of the above-mentioned surface of emission (33);

It is characterized in that,

Above-mentioned optical surface (35) is made of continuously a plurality of optical elements, each optical element has: the part light that will import from the above-mentioned plane of incidence (34) towards above-mentioned edge (32a) side shape forming the curved surface (35a) that low-angle mode reflects with the face that is parallel to the above-mentioned surface of emission (33), and will be in the light of this curved surface (35a) reflection dip plane (35c) to the above-mentioned surface of emission (33) lateral reflection.

2. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

The curved surface of above-mentioned each optical element (35a) is the curved surface that descends gradually from the above-mentioned edge of the above-mentioned surface of emission (33) side direction (32a) side.

3. liquid crystal indicator lighting screen as claimed in claim 2 is characterized in that:

The curved surface of above-mentioned each optical element (35a) is that the cross section is circular-arc.

4. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

Above-mentioned each optical element has plane (35b) between above-mentioned curved surface (35a) and above-mentioned dip plane (35c).

5. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

For the height of the above-mentioned dip plane (35c) of above-mentioned optical element, the aspect ratio that is positioned at above-mentioned edge (32a) side is positioned at the height height of the above-mentioned plane of incidence (34) side.

6. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

Height from the dip plane (32a) of the above-mentioned plane of incidence (34) n above-mentioned optical elements with respect to above-mentioned plane (35b) is an (n+1)/2, and wherein, a be several arbitrarily.

7. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

The thickness at above-mentioned edge (32a) is littler than the thickness of the above-mentioned plane of incidence (34), and has thick between the above-mentioned plane of incidence (34) and above-mentioned edge (32a).

8. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

The above-mentioned dip plane (35c) of above-mentioned each light-guide device is about 40～50 ° to the angle of inclination of above-mentioned plane (35b).

9. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

About the angle of inclination with respect to above-mentioned plane (35b), the above-mentioned dip plane (35c) of above-mentioned each light-guide device, above-mentioned edge (32a) side is bigger than the above-mentioned plane of incidence (34) side.

10. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

The length of above-mentioned each optical element is identical in fact.

11. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

About the length of above-mentioned each optical element, above-mentioned edge (32a) side is littler than the above-mentioned plane of incidence (34) side.

12. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that:

Above-mentioned liquid crystal indicator also has the optical sheet (51) of the surface of emission (33) side that is configured in above-mentioned light guide plate (32) with lighting screen, this optical sheet (51) penetrates to almost perpendicular to the light of the direction emission of this surface of emission (33) from the surface of emission (33) former state of above-mentioned light guide plate (32), will the light from the surface of emission (33) of above-mentioned light guide plate (32) towards the emission of above-mentioned edge (32a) lateral tilt direction be transformed to from the surface of above-mentioned optical sheet (51) to almost perpendicular to the light of the direction emission of the surface of emission (33) of above-mentioned light guide plate (32).

13. liquid crystal indicator lighting screen as claimed in claim 12 is characterized in that:

Have the face side that is configured in above-mentioned optical sheet (51), and the optically focused thin plate (61) of the either party between above-mentioned light guide plate (32) and the above-mentioned optical sheet (51); This optically focused thin plate (61) will be in the face parallel with the plane of incidence (34) of above-mentioned light guide plate (32) be transformed to from the surface of this optically focused thin plate (61) to almost perpendicular to the light of the direction emission of the surface of emission (33) of above-mentioned light guide plate (32) from the light of the surface of emission (33) the adipping emission of above-mentioned light guide plate (32).

14. liquid crystal indicator lighting screen as claimed in claim 1 is characterized in that, has the optical sheet (51) of the surface of emission side that is configured in above-mentioned light guide plate (32),

Above-mentioned optical sheet (51) former state penetrates from the surface of emission (33) of above-mentioned light guide plate (32) to almost perpendicular to the light of the direction emission of this surface of emission (33), will the light from the surface of emission (33) of above-mentioned light guide plate (32) towards the emission of above-mentioned edge (32a) lateral tilt direction be transformed to from the surface of above-mentioned optical sheet (51) to almost perpendicular to the light of the direction emission of the surface of emission (33) of above-mentioned light guide plate (32).

15. liquid crystal indicator lighting screen as claimed in claim 14 is characterized in that:

The surface of above-mentioned optical sheet (51) is the plane (52) parallel with the surface of emission (33) of above-mentioned light guide plate (32), the inside of above-mentioned optical sheet (51) is made of continuously a plurality of optical elements, and above-mentioned each collective optics has: the plane parallel with the surface of emission (33) of above-mentioned light guide plate (32) (53a, 53c) and will the light from the surface of emission (33) of above-mentioned light guide plate (32) towards the emission of above-mentioned edge (32a) lateral tilt direction be reflected into from the surface of above-mentioned optical sheet (51) to the dip plane (53d) of vertical direction emission.

16. liquid crystal indicator lighting screen as claimed in claim 14 is characterized in that:

Also has the face side that is configured in above-mentioned optical sheet (51), and the optically focused thin plate (61) of the either party between above-mentioned light guide plate (32) and the above-mentioned optical sheet (51), the light that this optically focused thin plate (61) will be launched from the surface of emission (33) adipping of above-mentioned light guide plate (32) in the face (Q) parallel with the plane of incidence (34) of above-mentioned light guide plate (32) is transformed to the light of launching to almost vertical with the surface of emission (33) of above-mentioned light guide plate (32) direction from the surface of this optically focused thin plate (61).

17. liquid crystal indicator lighting screen as claimed in claim 16 is characterized in that:

Above-mentioned optically focused thin plate (61) is made of to the convex lens bar portion (64) of extending perpendicular to the direction of the plane of incidence (34) of above-mentioned light guide plate (32) side by side a plurality of.

18. a liquid crystal indicator has:

Display screen (21), have the displayed image of watching the surface and with opposed the inside, this surface;

Lighting screen (31) is configured in the either party of the face side and the inside side of above-mentioned display screen (21),

It is characterized in that:

Above-mentioned lighting screen (31) comprises light source (37,61);

Light conductor (32), by incident from the plane of incidence (34) of the light of above-mentioned light source (37,61) emission, at the edge (32a) that forms with the opposed side of the above-mentioned plane of incidence (34), the surface of emission (33) of the light that imports from the above-mentioned plane of incidence (34) of emission and, have optical surface (a 35) formation with opposed of the above-mentioned surface of emission (33)

Above-mentioned optical surface (35) is connected by a plurality of optical elements and constitutes, each optical element have the part light that will import from the above-mentioned plane of incidence (34) towards above-mentioned edge (32a) side to form curved surface (35a) that low-angle mode reflects and will be in the light of this curved surface (35a) reflection dip plane (35c) to the above-mentioned surface of emission (33) lateral reflection with the face that is parallel to the above-mentioned surface of emission (33).

19. liquid crystal indicator as claimed in claim 18 is characterized in that, has

Be configured in the optical sheet (51) with the surface of emission (33) side of above-mentioned light guide plate (32),

This optical sheet (51) former state penetrates from the surface of emission (33) of above-mentioned light guide plate (32) to almost perpendicular to the light of the direction emission of this surface of emission (33), will the light from the surface of emission (33) of above-mentioned light guide plate (32) towards the emission of above-mentioned edge (32a) adipping be transformed to from the surface of above-mentioned optical sheet (51) to the light of almost vertical with the surface of emission (33) of above-mentioned light guide plate (32) direction emission.

20. liquid crystal indicator as claimed in claim 19 is characterized in that:

The surface of above-mentioned optical sheet (51) is the plane (52) parallel with the surface of emission (33) of above-mentioned light guide plate (32), be made of continuously a plurality of optical elements in the inside of above-mentioned optical sheet (51), above-mentioned each collective optics has: the plane parallel with the surface of emission (33) of above-mentioned light guide plate (32) (53a, 53c) and will the light from the surface of emission (33) of above-mentioned light guide plate (32) towards the emission of above-mentioned edge (32a) lateral tilt direction be reflected into from the surface of above-mentioned optical sheet (51) to the dip plane (53d) of vertical direction emission.

21. liquid crystal indicator as claimed in claim 19 is characterized in that:

Has the face side that is configured in above-mentioned optical sheet (51), and the optically focused thin plate (61) of the either party between above-mentioned light guide plate (32) and the above-mentioned optical sheet (51), the light that this optically focused thin plate (61) optically focused is launched to the direction parallel with its plane of incidence (34) from the surface of emission (33) of above-mentioned light guide plate (32).

22. liquid crystal indicator as claimed in claim 21 is characterized in that:

Above-mentioned optically focused thin plate (61) is made of to the convex lens bar portion (64) of extending perpendicular to the direction of the plane of incidence (34) of above-mentioned light guide plate (32) side by side a plurality of.

23. liquid crystal indicator as claimed in claim 19 is characterized in that:

Above-mentioned optical sheet (51) have will the emission from the surface of emission (33) of above-mentioned LGP (32) towards above-mentioned edge (32a) lateral tilt direction light be transformed to from the surface of above-mentioned optical sheet (51) to the function of the light of almost vertical with the surface of emission (33) of above-mentioned LGP (32) direction emission, and will be the face (Q) parallel with the incident face (34) of above-mentioned LGP (32) in be transformed to from the surface of this optical sheet (61) to the function of the light of almost launching perpendicular to the direction of the surface of emission (33) of above-mentioned LGP (32) from the light of the surface of emission (33) the adipping emission of above-mentioned LGP (32).

Images