JP2000048618A - Lighting panel and display device using the same - Google Patents

Abstract

(57) [Problem] To provide a display device which performs a two-way display in which both a display using external light and a display using light from a lighting panel are sufficiently bright. A liquid crystal display element is provided with an incident end face for taking in light from a light source section, a plurality of step faces, and a plurality of step faces for emitting light taken in from the incident end face. And the pitch P of the step surfaces 15 is constant and the height s of each step surface 15 is substantially equal.
3, a first light guide 11 having a front surface provided with a reflection film 16 on each of the plurality of step surfaces 14;
The light emitted from the step surface 15 is taken in, the light is emitted forward, the incident light from the front is emitted from the back surface, and the reflection film 16 on the step surface 14 of the first light guide is taken.
A second light guide 20 that emits the light incident on the rear surface and reflected by the second light guide forward is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sidelight type lighting panel and a display device using the same.

[0002]

2. Description of the Related Art As a lighting panel which emits light from the front, there is a panel called a sidelight type. Conventionally, this sidelight-type lighting panel is composed of a light guide that takes in light from an end face and emits the light to the front side, and a light source unit arranged on the side of the end face of the light guide. ing. Note that a straight tube fluorescent lamp, an LED array in which a plurality of LEDs (light emitting diodes) are arranged, and the like are used for the light source unit.

In general, a flat transparent plate made of acrylic resin or the like is used for the light guide, at least one end of which is an incident end for taking in light from the light source unit, and the front is a front end. , And an emission surface of the light taken in from the incident end surface.

The light guide takes in the light from the light source from the incident end face, and guides the light in the length direction of the light guide while refracting the light by the front surface and the back surface (interface with outside air) of the light guide. , From almost the entire front surface.

The illumination panel is used as a backlight of a display device using a transmissive display means such as a liquid crystal display element for controlling transmission of light and displaying, and for example, a liquid crystal display using a liquid crystal display element. The device has a configuration in which the lighting panel is arranged to face behind the liquid crystal display element.

[0006] The display device provided with the illumination panel performs only a transmission type display using illumination light (light from a light source unit) emitted from the illumination panel, and a transmission type display using the illumination light. There is a so-called two-way display type which performs both display using external light such as natural light or indoor light, and a conventional two-way display device includes the display means and the lighting panel disposed behind the display means. A semi-transmissive reflection plate is arranged between them.

This two-way display device performs reflection type display utilizing external light when sufficient external light can be obtained, and performs the above-mentioned illumination panel when external light having sufficient brightness cannot be obtained. Is turned on to perform a transmissive display using illumination light (light from the light source unit) emitted from the illumination panel. In the case of a reflective display using external light,
The display is performed by the light that is incident from the front of the display means and is reflected by the semi-transmissive reflector out of the external light transmitted through the display means, passes through the display means again, and is emitted forward.

Further, the transmissive display using the illumination light is performed by turning on a light source of the illumination panel, guiding light from the light source by the light guide, and emitting the light from the front surface thereof. At this time, of the illumination light emitted from the illumination panel, light transmitted through the semi-transmissive reflection plate becomes incident light on the display means, and the light is transmitted through the display means and emitted forward to display. Is performed.

[0009]

SUMMARY OF THE INVENTION However, the above-mentioned conventional 2
The way display device has a problem that a bright display cannot be obtained both when using external light and when using illumination light emitted from the illumination panel.

This is because the conventional lighting panel does not have a function of reflecting external light incident from the front and emitting the light forward.
Therefore, a semi-transmissive reflection plate is indispensable for a two-way display type display device.

[0011] The semi-transmissive reflection plate has its reflection /
In reflection-type displays that use external light to reflect and transmit incident light according to the transmittance characteristics, the amount of incident external light that corresponds to the transmittance of the semi-transmissive reflective plate is equal to that of the semi-transmissive reflective plate. In the transmissive display using illumination light, an amount of light corresponding to the reflectance of the semi-transmissive reflector of the illumination light emitted from the illumination panel is transmitted through the semi-transmissive reflective plate. It is reflected and becomes loss light.

Therefore, the conventional two-way display device has low light use efficiency both in the reflective display using external light and in the transmissive display using illumination light.
Both displays become dark.

According to the present invention, the light from the light source unit disposed on the side can be emitted forward, the external light incident from the front can be reflected and emitted forward, and the light from the light source unit can be emitted. An object of the present invention is to provide a lighting panel that can obtain high-luminance and uniform-luminance distribution emission light both when emitting light and when reflecting and emitting external light incident from the front. is there.

Further, the present invention sufficiently brightens both a reflective display using external light and a transmissive display using light from a light source unit, and furthermore, in any of the displays, the brightness is increased. It is an object of the present invention to provide a two-way display device capable of displaying a good image without unevenness.

[0015]

A lighting panel according to the present invention comprises an incident end face for taking in light incident from the side, a plurality of step surfaces, and a plurality of step surfaces connecting these step surfaces. A step-shaped surface having a constant pitch of the step surfaces, and a height of these step surfaces being substantially equal to each other, and a front surface provided with a reflective film over substantially the entire surface of each of the plurality of step surfaces; A first light guide that emits light captured from the incident end face from the plurality of step surfaces and reflects light incident from the front forward by the reflection film on the plurality of step surfaces; A light source unit disposed on the side of the incident end face of the light guide, and light emitted from the plurality of step surfaces of the first light guide disposed on the front side of the first light guide And emits the light forward, while entering from the front. A second light guide that emits light from the back surface and reflects light incident on the back surface by the reflection films on the plurality of step surfaces of the first light guide and emits light forward. It is a feature.

In this lighting panel, light from a light source unit disposed on the side of the incident end face of the first light guide is taken into the first light guide from the incident end face, and the light is guided. The light guide is guided in the length direction of the light guide while being refracted by the plurality of step surfaces of the light body front surface, that is, the plurality of step surfaces of the step shape surface, and emitted from the plurality of step surfaces of the step shape surface, and the light is emitted by the second step. The light is introduced into the light guide from the back, and is emitted forward from the front of the second light guide.

Further, the lighting panel takes in external light entering from the front thereof from the front surface of the second light guide, emits the light to the rear side of the second light guide, and emits the light. The reflected light is reflected by the reflective films provided on the plurality of step surfaces of the first light guide, and the reflected light is taken into the second light guide from the back surface, and the front surface of the second light guide is From the front.

That is, this lighting panel has a function of emitting light from a light source unit disposed on the side forward, and a function of reflecting external light incident from the front and emitting the light forward. .

In this lighting panel, the front surface of the first light guide is formed as a step-shaped surface including a plurality of step surfaces and a plurality of step surfaces connecting these step surfaces. Light that is introduced into the first light guide from its incident end face and guided through this light guide is emitted from any of the plurality of step surfaces and is taken into the second light guide from its back surface, Since the light is emitted forward from the front surface of the second light guide, light from the light source unit can be efficiently emitted forward, and high-brightness emitted light can be obtained.

In addition, since the pitch of the plurality of step surfaces of the stepped surface of the first light guide is constant, the interval between the light beams emitted from these step surfaces is substantially constant.
Since the heights of the plurality of step surfaces are substantially equal, and thus the areas of the step surfaces, that is, the light emission areas, are substantially equal, the amounts of light emitted from the plurality of step surfaces are substantially equal. Therefore, the light emitted from the plurality of step surfaces of the first light guide and taken into the second light guide from the back surface, and the light emitted forward from the front surface of the second light guide is uniform. It is light with a great luminance distribution.

Furthermore, the first light guide has a front surface formed in a stepped shape surface. Since a reflection film is provided on substantially the entire surface of each of the plurality of step surfaces, the first light guide is formed. The shape of the first light guide viewed from the front is such that a plurality of reflection films provided on the plurality of step surfaces sandwich an extremely narrow region corresponding to the plurality of step surfaces. The shapes are lined up. Further, since the pitches of the plurality of step surfaces are constant and the widths of the plurality of step surfaces (the width in the length direction of the light guide) between these step surfaces are equal, the plurality of reflection films are formed. Are also constant in width and spacing.

Therefore, the first light guide has almost the same reflection characteristics with respect to external light incident from the front as a flat-plate-shaped reflector, and efficiently reflects external light incident from the front. The reflected light having a uniform luminance distribution is emitted forward.

Therefore, according to the lighting panel of the present invention, it is possible to emit the light from the light source unit disposed on the side forward and reflect the external light incident from the front and emit the light forward. In addition, both when the light from the light source unit is emitted and when the external light incident from the front is reflected and emitted, it is possible to obtain the emitted light having a high luminance and a uniform luminance distribution.

Further, the display device of the present invention comprises a transmissive display means for controlling and displaying light transmission, and an illumination panel arranged opposite to the back side of the display means, wherein the illumination panel is provided. An incident end face for taking in light incident from the side, a plurality of step surfaces and a plurality of step surfaces connecting these step surfaces, and the pitch of the plurality of step surfaces is constant and the height of the plurality of step surfaces And a front surface on which a reflection film is provided over substantially the entire surface on each of the plurality of step surfaces, and emits light taken in from the incident end surface from the plurality of step surfaces. A first light guide for reflecting light incident from the front by the reflection films on the plurality of stepped surfaces; and a light source disposed on a side of the incident end face of the first light guide. And a part disposed on the front side of the first light guide Taking in light emitted from the plurality of step surfaces of the first light guide and emitting the light forward, and emitting incident light from the front from the back surface, And a second light guide that emits light that is reflected by the reflective films on the plurality of stepped surfaces and enters from the back surface to the front.

That is, in this display device, the above-described illumination panel of the present invention is disposed on the back side of the transmission type display means. According to this display device, the illumination panel emits light from the light source unit disposed on the side forward and reflects external light incident from the front and emits the light forward. The two-way display can be performed without using.

In addition, when the illumination panel emits light from the light source unit or reflects and emits external light incident from the front, it emits light with high luminance and uniform luminance distribution. Therefore, both the reflective display using external light and the transmissive display using light from the light source unit are sufficiently brightened, and a good image without luminance unevenness is obtained in any display. Can be displayed.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, a lighting panel according to the present invention includes an incident end face for taking in light incident from the side, a plurality of step surfaces, and a plurality of step surfaces connecting these step surfaces. A plurality of stepped surfaces having a constant pitch and a plurality of stepped surfaces having substantially equal heights, and a front surface having a reflection film provided on substantially the entire surface of each of the plurality of stepped surfaces. A first light guide that emits light captured from the incident end face from the plurality of step surfaces and reflects light incident from the front forward by the reflective film on the plurality of step surfaces; A light source unit is arranged on the side of the incident end face of the first light guide, and the light emitted from the plurality of step surfaces is taken in on the front side of the first light guide, and the light is directed forward. Outgoing light, and forward incoming light from the back. By arranging a second light guide that emits light that is reflected by the reflective films on the plurality of step surfaces and that enters from the back surface, the light from the light source unit disposed on the side is forwarded. And can reflect external light incident from the front and emit the light forward.
When the light is emitted from the light source unit and when the external light entering from the front is reflected and emitted, it is possible to obtain the emitted light having a high luminance and a uniform luminance distribution.

Further, the display device of the present invention, by disposing the illumination panel of the present invention behind the transmissive display means, utilizes the reflective display utilizing external light and the illumination light from the light source unit. The display of both the transmissive type and the transmissive type is made sufficiently bright, and a good image without luminance unevenness can be displayed in any of the displays.

In the lighting panel according to the present invention, the first
Preferably, the back surface of the light guide is a flat surface, and the plurality of step surfaces are respectively parallel to each other, and the plurality of step surfaces are respectively parallel to each other. It is possible to obtain emitted light having a suitable luminance distribution.

The step-shaped surface of the first light guide includes a plurality of step surfaces and a plurality of step surfaces connecting these step surfaces, and the pitch of the step surfaces is constant. As long as the heights of the plurality of step surfaces are substantially equal, any of the following shapes may be used.

That is, in the step-shaped surface, the plurality of step surfaces are substantially parallel to the back surface of the first light guide, and the plurality of step surfaces are formed on the back surface of the first light guide. It may be formed in a shape that is substantially perpendicular to the first light guide. In this case, a reflective surface substantially parallel to the back surface of the first light guide may be formed by the reflective films provided on the plurality of step surfaces. Can, and
When the first light guide is viewed from the front thereof, the step surface is hardly visible, so that the first light guide can have a reflection characteristic closer to a flat plate-like reflector.

Further, in the step-shaped surface, the plurality of step surfaces are substantially parallel to the back surface of the first light guide, and the plurality of step surfaces are the back surface of the first light guide. It may be formed in a shape inclined at a predetermined angle with respect to the normal line. In this case, the reflection film provided on the plurality of step surfaces forms a reflection surface substantially parallel to the back surface of the first light guide. While forming
It is possible to increase the area of the step surface compared to the case where the step surface is formed perpendicular to the back surface of the light guide, emit more light from the plurality of step surfaces, and increase the intensity thereof. it can.

[0033] Further, the step-shaped surface may be such that the plurality of step surfaces increase the distance from the rear surface of the first light guide to the rear surface from the base end to the front end of the step surface. The plurality of step surfaces may be formed in a shape that is substantially perpendicular to the back surface of the first light guide,
In that case, the area of the step surface is increased as compared with the case where the step surface is formed in parallel to the back surface of the light guide, and more light is emitted from the plurality of step surfaces to reduce the intensity. In addition, the height of the first light guide is made substantially invisible when the first light guide is viewed from the front, so that the first light guide has a reflection characteristic closer to a flat plate-like reflector. Can be given.

Still further, in the step-shaped surface, the plurality of step surfaces increase a distance between the rear surface of the first light guide and the rear surface from a base end to a front end of the step surface. And the plurality of step surfaces may be formed in a shape inclined at a predetermined angle with respect to a normal to the back surface of the first light guide. The area can be further increased, and more light can be emitted from the plurality of step surfaces to increase the intensity.

As described above, when the plurality of step surfaces are inclined surfaces, the inclination angle of the step surface with respect to the normal to the back surface of the first light guide is determined by the difference between the step surface and the step surface. When the direction in which the angle is large is a positive angle, and the direction in which the angle between the step surface and the step surface is small is a negative angle, it is preferable that the angle be in the range of −5 ° to 60 °. By setting the inclination angle of the step surface to
Light guided through the light guide body and emitted from the plurality of step surfaces can be efficiently emitted without being totally reflected by the step surfaces.

Further, as described above, when the plurality of step surfaces are inclined surfaces, the inclination angle of the step surface with respect to the back surface of the first light guide is desirably 10 ° or less. If the inclination angle of the step surface is at this level, external light incident from the front can be reflected forward by the reflection films provided on the plurality of step surfaces.

Further, the incident end face of the first light guide is:
Although it may be a surface perpendicular to the back surface of the first light guide,
It is preferable that the first light guide has an inclined surface inclined at a predetermined angle with respect to a normal to the back surface of the first light guide.

If the incident end surface is an inclined surface, of the light from the light source unit, light incident on the incident end surface from a direction substantially parallel to the back surface of the first light guide body will also be incident on the incident end surface. Since the light is refracted and enters the first light guide, most of the light taken into the first light guide from the incident end face is
By guiding the light guide within the light guide while being refracted by the plurality of step surfaces and the light guide back surface, light of higher intensity can be emitted from the plurality of step surfaces. It is possible to efficiently emit light forward and obtain high-luminance emitted light.

When the incident end face of the first light guide is an inclined surface, the angle of inclination of the incident end face should be 60 ° or less with respect to the normal to the back surface of the first light guide. Desirably,
By setting the angle of inclination of the incident end face in this way, light from the light source section can be efficiently taken into the first light guide without being totally reflected by the incident end face.

In the lighting panel according to the present invention, the second light guide has, on its back surface, an incident surface for taking in light emitted from the plurality of step surfaces of the first light guide, and the incident surface. It is preferable to have a configuration having a plurality of projection-shaped incident portions having a refraction surface for refracting light incident from the front toward the front, and by using the second light guide having such a configuration, Most of the light emitted from the plurality of step surfaces of the first light guide can be taken into the second light guide without loss and emitted forward, and the emitted light can be increased in a predetermined direction. It can be a light having a luminance distribution with directivity and emitted with luminance.

[0041]

1 to 3 show a first embodiment of the present invention. FIG. 1 is a side view of a two-way display device having a lighting panel, and FIG. 2 is an enlarged side view of a part of the lighting panel. Figure,
FIG. 3 is a side view of a first light guide of the lighting panel.

The display device of this embodiment uses a liquid crystal display element as a transmissive display means for controlling the transmission of light to perform display. As shown in FIG.
And an illumination panel 10 arranged opposite to the back surface of the liquid crystal display element 1.

Although the internal structure of the liquid crystal display element 1 is not shown, an active matrix type or a simple matrix type in which a plurality of pixel portions for controlling the transmission of light by applying a voltage are formed in a matrix. Things.

The lighting panel 10 will be described.
As shown in FIGS. 1 and 2, this lighting panel 10
A first light guide 11, a light source unit 17 disposed on the side of the first light guide 11, and a second light guide disposed on the front side of the first light guide 11 It consists of 20.

The first light guide 11 is a transparent plate made of an acrylic resin or the like. As shown in FIG. 3, the back surface 11a has a flat surface, and one end surface is formed from the side. Incident end face 1 for taking incident light (light from light source unit 14)
It is 2.

The front surface of the first light guide 11 has a plurality of step surfaces 14 which are substantially parallel to each other and whose height is changed so as to decrease the distance from the rear surface 11a in a direction away from the incident end surface 12. And a plurality of step surfaces 15 having extremely small heights connecting these step surfaces 14, the step-shaped surface 1.
3 is formed.

The step-shaped surface 13 is formed such that the pitch of the plurality of step surfaces 15 is constant and the height of these step surfaces 15 is substantially equal. Each step surface 14 between the step surface 15 and the last step surface 15 closest to the other end of the light guide 11 is
All of them are formed to have the same width (width in the light guide length direction).

The highest step surface (hereinafter referred to as the first step surface) between the first step surface 15 and the incident end surface 12 among the plurality of step surfaces 14 and the last step surface 1
The width of the lowest step surface (hereinafter, referred to as the last step surface) between 5 and the other end of the light guide 11 is arbitrarily set.

In this embodiment, the step-shaped surface 1
3, the plurality of step surfaces 14 are substantially parallel to the back surface 11a of the first light guide 11, and the plurality of step surfaces 15 are respectively provided on the back surface 11a of the first light guide 11. It is formed in a shape that is almost perpendicular to it.

The first light guide 11 is, as shown in FIG.
The length of the light guide is L, the height of the incident end face 12 is d1, the height of the other end face is d2, and the distance from the first step surface 15 to the edge of the light guide 11 on the incident end face 12 side is a. Assuming that the distance from the last step surface 15 to the other end of the light guide 11 is b, the pitch of the plurality of step surfaces 15 is P, and the height of these step surfaces 15 is s, the following equation (1) s = P (d1−d2) / {L− (a + b)} (1) However, the pitch P between the plurality of step surfaces 15 is preferably in the range of 5 to 500 μm.

On the plurality of step surfaces 14, 14a, 14b of the step-shaped surface 13 of the first light guide 11, a high light reflectivity such as aluminum or silver is provided over almost the entire surface. A reflective film 16 made of a metal vapor-deposited film having
Are light emitting surfaces on which the reflective film 16 is not formed.

The first light guide 11 receives light from the light source 17 disposed on the side thereof from the incident end face 12, and transmits the light received from the incident end face 12 to the step-shaped surface 13. Light emitted from the plurality of step surfaces 15 and incident from the front is reflected forward by the reflection film 16 on the plurality of step surfaces 14.

The light source section 17 includes a straight tubular fluorescent lamp 18 having a length extending over the entire length of the incident end face 12 of the first light guide 11.
And a reflector 19 for reflecting light emitted from the fluorescent lamp 18.
The side of the incident end face 12 of the light guide 11
2 are arranged opposite to each other. The light source unit 17
Is not limited to a device using a fluorescent lamp, but may be a device using an LED array in which a plurality of LEDs (light emitting diodes) are arranged.

On the other hand, the second light guide 20 disposed on the front side of the first light guide 11 takes in the light emitted from the plurality of stepped surfaces 15 of the first light guide 11 and receives the light. The light is emitted forward, and the light incident from the front is emitted from the rear surface. It has the function of emitting light to

The second light guide 20 is a transparent plate made of an acrylic resin or the like having substantially the same width as the first light guide 11, and has a front surface as shown in FIGS. Is a flat surface, and a plurality of projection-like incident portions 21 for taking in light emitted from the plurality of step surfaces 15 of the first light guide 11 are formed integrally at a constant pitch on the back surface. .

Each of the plurality of incident portions 21 has a triangular cross-sectional shape, and has a horizontally long projection shape extending over the entire width of the second light guide 20. An incident surface 21a for taking in light emitted from the step surface 15 of the first light guide 11 is provided, and the other side surface is a refracting surface 21b for refracting light incident from the incident surface 21a forward. .

As shown in FIG. 2, the incident surface 21a and the refraction surface 21b of the incident portion 21 are different from each other in the angles α and β with respect to the normal H2 of the front surface of the second light guide 20. The angle α of the incident surface 21a with respect to the normal H2 is set, for example, in the range of 5 ° to 25 °, and the angle β of the refraction surface 21b with respect to the normal H2 is, for example, 20 ° to 50 °.
° is set in the range.

The length direction of the plurality of incident portions 21 on the back surface of the second light guide 20 is made parallel to the length direction of the plurality of step surfaces 15 of the first light guide 11. With the incident surface 21a, which is one side surface of the incident portion 21 facing the step face 15 of the first light guide 11, the tips of the plurality of incident portions 21 are connected to the first light guide. It is arranged on the front surface side of the first light guide 11 so as to be close to or coincide with the surface of the reflection film 16 on the plurality of step surfaces 14 or the extension surface thereof.

The first light guide 11 has an imaginary line passing through the leading edges of the plurality of step surfaces 14 and an imaginary line passing through the tops of the plurality of incident portions 21 of the second light guide 20. It is arranged to be inclined in the longitudinal direction so as to be substantially parallel to

Therefore, the plurality of step surfaces 1 of the light guide 11
The distance between the reflective film 16 on the light guide 4 and the tops of the plurality of incident portions 21 of the second light guide 20 differs depending on the position of the incident portion 21 facing the stepped surface 14.
Is located at the base end side of the step surface 14 (left side in the figure).
The distance increases as the distance from the step surface 14 increases, and the distance decreases as the position facing the incident portion 21 approaches the front end side (the right side in the figure) of the step surface 14.

The gap between the first light guide 11 and the second light guide 20 is an air layer, and these light guides 11 and 20 are illustrated at their respective peripheral portions. Not joined via spacers.

Further, the plurality of incident portions 21 of the second light guide 20 are provided at a pitch smaller than the pitch P of the plurality of step surfaces 15 of the first light guide 11,
Therefore, the incident portions 21 of the second light guide 20 are respectively provided with respect to the respective step surfaces 15 of the first light guide 11.
Are at least one or more.

In FIG. 1, for convenience, the second light guide 2
Although the light-incident part 21 is greatly enlarged, the pitch of the light-incident part 21 is substantially the same as the pixel pitch of the liquid crystal display element 1 (arrangement pitch of a plurality of pixel parts) or is smaller than the pixel pitch. Is also set small.

Then, in the liquid crystal display device shown in FIG.
The illumination panel 10 is disposed behind the liquid crystal display element 1 with the light source 17 disposed side facing the main direction of external light.

That is, in the two-way display type liquid crystal display device, when external light is used, similarly to a normal reflection type liquid crystal display device, the direction inclined toward the upper edge of the screen (bright) is similar to the normal direction of the screen. Since the screen is used so as to mainly take in external light from the direction in which external light is obtained), in this embodiment,
The illuminating panel 10 is arranged such that the light source unit 17 is arranged such that the arrangement side of the light source unit 17 is directed to the upper edge side of the screen, which is the main direction of capturing external light, that is, the upper edge side (left side in FIG.

The above liquid crystal display device performs reflection type display utilizing external light when external light of sufficient brightness is obtained,
When external light of sufficient brightness cannot be obtained, the light source unit 17 of the lighting panel 10 is turned on to turn on the lighting panel 10.
Is a two-way display type that performs a transmissive display using illumination light emitted from the light source unit 17 (light from the light source unit 17). Light emitted from the illumination panel 10 enters the liquid crystal display element 1, and the light is transmitted through the liquid crystal display element 1 and emitted forward.

In the case of a reflection type display using external light, external light incident on the liquid crystal display element 1 from the front thereof is transmitted through the liquid crystal display element 1 and reflected by the illumination panel 10, and the reflected light is reflected. The light again passes through the liquid crystal display element 1 and is emitted forward.

First, a description will be given of a transmissive display using illumination light from the illumination panel 10. The illumination panel 10 includes a light source unit 17 arranged on the side of the incident end face 12 of the first light guide 11. From the light incident surface 12 of the first light guide 11, and the light is transmitted to the first light guide 11 through a plurality of light guide front surfaces, that is, a plurality of steps 13, as shown by the solid line in FIGS. 1 and 2. Step surface 14 and light guide back surface 11a
The light is guided in the length direction of the light guide while being refracted by the light source, emitted from the plurality of step surfaces 15 of the step-shaped surface 13, and the light is taken into the second light guide 20 from the back surface thereof, and the
Out of the light guide 20 from the front.

That is, the light from the light source unit 17 is incident on the first light guide 11 from the incident end face 11a at various incident angles, and goes to the plurality of step surfaces 14 of the step-shaped surface 13 among them. Light is reflected by the reflection film 16 on the step surface 14 and refracted, and light traveling toward the light guide back surface 11a is totally reflected and refracted at the interface between the back surface 11a and the outside air (air). While being guided in the length direction of the first light guide 11 by repetition, the light enters the step surface 15 of the step-shaped surface 13 and exits from the step surface 15.

In this embodiment, the light guide back 1
1a is refracted by total reflection at the interface between the back surface 11a and the outside air, but a reflection plate or a reflection film is provided on the back surface 11a of the first light guide, and the back surface 11a is provided. May be reflected by the reflection plate or the reflection film to be refracted. In this case, light guided inside the first light guide 11 leaks to the back side thereof. It can be prevented more reliably.

The plurality of step surfaces 15 of the first light guide 11
Is emitted from the incident surface 21a into a plurality of projecting incident portions 21 formed on the back surface of the second light guide 20.

It is to be noted that, among the light beams emitted from the plurality of step surfaces 15, as shown in FIG. 2, some light beams are emitted toward the next step surface 14. The light is reflected by the upper reflective film 16 and is incident on the incident portion 21 facing the step surface 14.

In this case, in this embodiment, as described above, the plurality of incident portions 21 of the second light guide 20 are
By providing the light guide 11 at a pitch smaller than the pitch P of the plurality of step surfaces 15 of the first light guide 11, the second light guide 20 is provided for each of the step surfaces 15 of the first light guide 11.
Because at least one or more of the incident portions 21 are opposed to each other, most of the light emitted from the plurality of stepped surfaces 15 of the first light guide 11 can be transmitted from the plurality of incident portions 21 to the second guide without loss. The light can be taken into the light body 20 and emitted forward from the front surface.

The plurality of incident portions 21 of the second light guide 20
The light taken in from the incident surface 21a is refracted by the refracting surface 21b and the light guide 1 opposite to the incident surface 21a, respectively.
The light is totally reflected at the interface with the air layer between the first light guide 20 and the second light guide 20 and is refracted in the direction toward the front surface of the second light guide 20. Light is emitted forward from the front.

The main emission direction of the light emitted from the front surface of the second light guide 20 is determined according to the inclination angle β of the refraction surface 21 of the incident portion 18, and the inclination angle β of the refraction surface 21
By selecting, it is possible to emit light with a luminance distribution having high directivity with high luminance in a predetermined direction.

In this embodiment, as described above,
The inclination angle β of the second optical interface 18b is set to 20 ° to 50 °.
.Degree., The incident light from the incident surface 21a is refracted in the vicinity of the direction along the normal H2 of the front surface of the second light guide 20 (front direction). From the front surface of the light guide 17, light having a luminance distribution with high directivity having high luminance in the front direction is emitted.

Light emitted forward from the front surface of the second light guide 20, that is, light emitted from the illumination panel 10, enters the liquid crystal display device 1 from the back surface and passes through the liquid crystal display device 1. Then, the light is emitted forward.

Next, a description will be given of a display using external light. In this case, external light incident from the front of the liquid crystal display element 1 passes through the liquid crystal display element 1 and passes through the second panel of the illumination panel 10. The light enters the light guide 20 from the front.

In this embodiment, as described above, the illuminating panel 10 is mounted on the upper edge side of the screen (the upper side of the liquid crystal display element 1), which is the main direction in which external light of the liquid crystal display device is taken in. (Edge side).
The external light that enters the light guide 20 mainly enters from the side where the light source unit 17 is disposed.

External light incident on the second light guide 20 from the front thereof is moved along the thickness direction of the second light guide 20 along the path shown by broken lines in FIGS. The light is transmitted and exits from the incident surface 21a and the refraction surface 21b of the plurality of incident portions 21 on the rear surface thereof, and is output from the plurality of step surfaces 14 of the first light guide 11.
The light is reflected by the upper reflective film 16.

Since the external light is incident at various angles of incidence, the light incident on the second light guide 20 from the front is incident on the incident surface 21a and the refraction surface 21b of the plurality of incident portions 21 on the rear. Are incident on the incident surface 21a and the refracting surface 21b at an angle smaller than the critical angle for total reflection (closer to the vertical). Refraction surface 21b and light guide 1
The light passes through the interface between the air layer 1 and the air layer 20 and is refracted at a refraction angle corresponding to the angle of incidence on the interface, and is emitted to the back side.

On the other hand, the incident surface 21a and the refraction surface 21
b is incident at an angle between the incident surface 21a and the refraction surface 21b and the air layer, but is totally reflected at the interface between the incident surface 21a and the air layer. The totally reflected light enters the refraction surface 21b having a different inclination angle on the reflection side, passes through the interface between the refraction surface 21b and the air layer, and is refracted at a refraction angle corresponding to the incidence angle on the interface. Out to the back side.

The light totally reflected at the interface between the refraction surface 21b and the air layer is incident on the incidence surface 21a having a different inclination angle on the reflection side, and the light is reflected at the interface between the incidence surface 21a and the air layer. The light is transmitted, refracted at a refraction angle corresponding to the angle of incidence on the interface, and emitted to the rear side.

For this reason, most of the external light that has entered the second light guide 20 from its front surface is emitted to the rear side without any loss, and is located on the plurality of step surfaces 14 of the first light guide 11. Is reflected by the reflective film 16.

The reflected light reflected by the reflection films 16 on the plurality of step surfaces 14 of the first light guide 11 is taken into the second light guide 20 from the back surface thereof. Is transmitted in the thickness direction and emitted from the front to the front.

At this time, the light reflected by the reflection film 16 on the plurality of step surfaces 14 of the first light guide 11 is transmitted to the second light guide 20 from the plurality of incident portions 21 on the back surface thereof. Of the light, the light that enters the incident surface 21a and the refracting surface 21b of the incident portion 21 at an angle smaller than the critical angle for total reflection is included in the incident surface 21a and the refracting surface 21b.
Through the interface with the air layer between the light guides 11 and 20 and the second
And is refracted toward the front surface of the second light guide 20 at a refraction angle corresponding to the angle of incidence on the interface,
The light exits from the front surface of the light guide 20.

The incident surface 21a and the refraction surface 21
Light incident at an angle larger than the critical angle for total reflection with respect to b is totally reflected at the interface between the incident surface 21a and the refraction surface 21b and the air layer, but the light totally reflected at these interfaces is adjacent. The light enters the incident surface 21a or the refracting surface 21b of the other incident portion 21 and is incident on the incident surface 21a or the refracting surface 21b.
b through the interface between the air layer and the second light guide 20, and enters the second light guide 20, and is refracted toward the front surface of the second light guide 20 at a refraction angle corresponding to the angle of incidence on the interface. , This light guide 20
Out of the front of the device.

For this reason, most of the light reflected by the reflection films 16 on the plurality of step surfaces 14 of the first light guide 11 is taken into the second light guide 20 from the back without loss. The light is emitted forward from the front.

The reflected light emitted from the front surface of the second light guide 20 is high-intensity light obtained by condensing light incident on the second light guide 20 from the front thereof. The emitted light is also light having a luminance distribution in which the luminance of light emitted in the front direction of the light guide 17 is high.

The reflected light emitted forward from the front surface of the second light guide 20 enters the liquid crystal display device 1 from the rear surface, passes through the liquid crystal display device 1, and is emitted forward. .

That is, the lighting panel 10 has a function of emitting light from the light source unit 17 disposed on the side thereof, and a function of reflecting external light incident from the front and emitting the light forward. are doing.

Then, in the lighting panel 10,
The front surface of the first light guide 11 is formed on a step-shaped surface 13 composed of a plurality of step surfaces 14 and a plurality of step surfaces 15 connecting these step surfaces 14. 1
1, the light guide 11
Light guided inside is emitted from any one of the plurality of step surfaces 15 and is taken into the second light guide 20 from the back surface, and is emitted forward from the front surface of the second light guide 20. Therefore, the light from the light source unit 17 can be efficiently emitted forward, and high-luminance emitted light can be obtained.

Moreover, since the pitch of the plurality of step surfaces 15 of the step-shaped surface 13 of the first light guide 11 is constant, the interval between the light beams emitted from these step surfaces 15 is substantially constant. Further, since the heights s of the plurality of step surfaces 15 are substantially equal, and therefore, the areas of these step surfaces 15, that is, the light emission areas, are substantially equal, the height
5 have substantially equal amounts of light.

For this reason, the light is emitted from the plurality of step surfaces 15 of the first light guide 11 and is taken into the second light guide 20 from the rear surface thereof, from the front of the second light guide 20 to the front. Is light having a uniform luminance distribution.

Further, the first light guide 11 has a front surface formed on a stepped surface 13, and a reflective film 16 is provided on substantially the entire surface of each of the plurality of step surfaces 14. Therefore, the shape of the first light guide 11 viewed from the front thereof is such that the plurality of reflection films 16 provided on the plurality of step surfaces 14 are formed by the plurality of step surfaces 1.
The shape is such that an extremely narrow region corresponding to No. 5 is sandwiched. Further, the pitch of the plurality of step surfaces 15 is constant, and therefore, the width of the plurality of step surfaces 14 between these step surfaces 15 (the width in the length direction of the light guide 11) is equal. The width and interval of the plurality of reflection films 16 are also constant.

For this reason, the first light guide 11 has almost the same reflection characteristics with respect to the external light entering from the front as the flat-plate-like reflector, and efficiently reflects the external light entering from the front. It reflects well and emits reflected light having a uniform luminance distribution forward.

In this embodiment, the step-shaped surface 13 of the first light guide 11 is divided into a plurality of stepped surfaces 14 substantially parallel to the back surface 11a of the light guide and a plurality of stepped surfaces 15
Is formed in a shape substantially perpendicular to the back surface 11a of the light guide, so that the reflection film 16 provided on the plurality of step surfaces 14 makes the back surface of the first light guide 11 substantially parallel to the back surface. Since the reflecting surface can be formed, and the step surface is hardly seen when the first light guide is viewed from the front thereof, the first light guide 11 is provided with a flat plate-like reflecting plate. Reflection characteristics close to the above.

Therefore, according to the lighting panel of the present invention, it is possible to emit the light from the light source unit disposed on the side forward and reflect the external light incident from the front to emit the light forward. In addition, both when the light from the light source unit is emitted and when the external light incident from the front is reflected and emitted, it is possible to obtain the emitted light having a high luminance and a uniform luminance distribution.

The illumination panel 10 has a second light guide 20 disposed on the front side of the first light guide 11 and a plurality of steps of the first light guide 11 on the back. Since a plurality of projecting incident portions 21 having an incident surface 21a for taking in light emitted from the surface 15 and a refraction surface 21b for refracting light incident from the incident surface 21a forward are formed, Most of the light emitted from the plurality of step surfaces 15 of the first light guide 11 can be taken into the second light guide 20 without any loss and emitted forward, and the emitted light is directed in a predetermined direction. Light with a luminance distribution having directivity and emitted with high luminance can be obtained.

The display device comprises a liquid crystal display element 1
The above-mentioned lighting panel 10 is arranged on the back side of the display device. According to this display device, the lighting panel 10
Since the light from the light source unit 17 disposed on the side is emitted forward and the external light incident from the front is reflected and emitted forward, a two-way display can be performed without using a semi-transmissive reflector. it can.

In addition, when the illumination panel 10 emits light from the light source unit 17 and reflects and emits external light incident from the front, it emits light with high luminance and a uniform luminance distribution. Since the light is emitted, both the reflective display using external light and the transmissive display using light from the light source unit are sufficiently brightened. Images can be displayed.

Further, as described above, since the illumination panel 10 emits light having a luminance distribution in which the light emitted in a predetermined direction has a high luminance, the luminance of the light emitted from the illumination panel 10 in the front direction is reduced. By designing to emit light with a high luminance distribution (designing the inclination angles of the incident surface 21a and the refraction surface 21b of the incident portion 21 of the second light guide 20)
An image with high front luminance can be displayed.

Note that the lighting panel 10 of the first embodiment is used.
Is a step-shaped surface 13 on the front surface of the first light guide 11, a plurality of step surfaces 14 are all substantially parallel to the light guide back surface 11a, and a plurality of step surfaces 15 are respectively formed by the light guide back surface 11a.
Are formed in a shape substantially perpendicular to the stepped surface, but the stepped surface 13 has a plurality of step surfaces 14 and these step surfaces 1.
4 is formed into another shape as long as the shape is formed of a plurality of step surfaces 15 connecting the plurality of step surfaces 4 and the pitch P of the step surfaces 15 is constant and the heights s of the step surfaces 15 are substantially equal. May be.

Further, the incident end face 12 of the first light guide 11 is connected to the first light guide 1 as in the first embodiment.
The incident end face 12 may be an inclined face inclined at a predetermined angle with respect to a normal to the rear face of the first light guide 11, although it may be a face perpendicular to the back face 11 a of the first light guide body 11.

FIG. 4 is a first embodiment showing a second embodiment of the present invention.
5 is an enlarged view of a part of the light guide 11 shown in FIG. In this embodiment, the stepped surface 13 on the front surface of the first light guide 11 and the plurality of stepped surfaces 14 are connected to the first light guide 1.
1 is substantially parallel to the back surface 11a, and the plurality of step surfaces 1
Reference numeral 5 denotes a first light guide formed so as to be inclined at a predetermined angle θs with respect to a normal H1 to the back surface 11a of the first light guide.

The light guide 11 of this embodiment is different from the first embodiment in the configuration of the stair-shaped surface 13 except for the shape of the step-shaped surface 13. A reference numeral is attached and omitted.

According to the light guide 11, the first light guide 11 is formed by the reflection film 16 provided on the plurality of step surfaces 15.
Forming a reflective surface substantially parallel to the back surface 11a of the
As compared with the case where the step surface 15 is formed perpendicular to the light guide back surface 11a as in the first embodiment described above, the area of the step surface 15 is increased, and A large amount of light can be emitted to increase the intensity.

When the plurality of step surfaces 15 are inclined surfaces as described above, the inclination angle θs of the step surface 15 with respect to the normal line H 1 of the back surface 11 a of the first light guide 11 is as shown in FIG. When the direction in which the angle between the step surface 14 and the step surface 15 increases is a positive angle, and the direction in which the angle between the step surface 14 and the step surface 15 decreases is a negative angle, In the range of 5 ° to 60 °, more preferably 25 °
It is preferable to set the inclination angle θs of the step surface 15 in the range of up to 30 ° (θs = approximately 27 ° in FIG. 5). Light emitted from the plurality of step surfaces 15 is transmitted to the step surface 15.
(Interface between the step surface 15 and the air layer between the light guides 11 and 20)
Thus, the light can be emitted efficiently without total reflection.

In the light guide 11 of this embodiment, as shown in FIG. 5, the pitch of the plurality of step surfaces 15 is P, and the width of the step surface 14 (the lower end of one adjacent step surface 15 and the other step surface 15). Is the distance from the upper end of the suffix P ′ to P ′, the above equation (1) “s
= P (d1−d2) / {L− (a + b)} ”, P = P ′ + stan θs (where θs = −5 ° to 60
°) and can be designed based on the replaced equation.

FIG. 6 shows a third embodiment of the present invention.
FIG. 3 is a side view of the light guide 11 of the first embodiment.
The stepped surface 13 on the front surface of the light guide 11 is replaced with the plurality of step surfaces 14 in the same manner as in the second embodiment.
1 is substantially parallel to the back surface 11a, and the plurality of step surfaces 1
5 is formed in a shape inclined at a predetermined angle θs with respect to a normal line H1 of the back surface 11a of the first light guide, and
The incident end face 12 of the first light guide 11 is a slope inclined at a predetermined angle θa with respect to a normal H1 to the back surface 11a of the light guide 11.

The light guide 11 of this embodiment is different from the first embodiment in the configuration of the light guide 11 except that the shape of the stepped surface 13 is different from that of the first embodiment. A reference numeral is attached and omitted.

According to the light guide 11, the first light guide 11 is formed by the reflection film 16 provided on the plurality of step surfaces 15.
Forming a reflective surface substantially parallel to the back surface 11a of the
As in the second embodiment, more light can be emitted from the plurality of step surfaces 15 to increase the intensity thereof, and further, a light source unit disposed on the side of the incident end surface 12. 17 (see FIG. 1) can be emitted more efficiently forward to obtain high-luminance emission light.

That is, when the incident end face 12 of the first light guide 11 is a plane perpendicular to the back surface 11a of the light guide, the first light guide of the light from the light source 17 is used. Light incident from a direction substantially parallel to the back surface 11a of the body 11,
The light passes through the interface between the incident end face 12 and the outside air (air) with almost no refraction and enters the light guide 11, and the light is guided inside the light guide 11 substantially parallel to the back surface 11 a thereof.

[0114] Of the light, the light traveling toward the plurality of step surfaces 15 is emitted from the step surfaces 15, but is higher than the height of the last step surface 15 closest to the other end of the light guide 11. Is low, that is, the light traveling in the area near the light guide back surface 11a is refracted at a very small angle even if it enters the light guide back surface 11a in the process. The light is guided to the other end of the light guide 11 without being incident on the step surface 15.

However, the first light guide 11 of this embodiment
Since the incident end surface 12 is inclined at a predetermined angle θa with respect to the normal H2 of the back surface 11a of the light guide, the back surface of the first light guide 11 of the light from the light source 17 is Light incident on the incident end face 12 from a direction substantially parallel to 11a is also refracted at the incident end face 12 and enters the first light guide 11 as shown by the path indicated by the solid line in FIG.

Therefore, according to the light guide 11, most of the light taken into the light guide 11 from the incident end face 12 is reflected by the reflection film 16 on the plurality of step surfaces 14 and the light guide back surface 11a. By guiding the inside of the light guide 11 while being refracted, it is possible to emit light of higher intensity from the plurality of step surfaces 15, so that the light from the light source unit is more efficiently emitted forward, It is possible to obtain emission light with luminance.

When the incident end face 12 is an inclined plane, the inclination angle θa of the incident end face is desirably 60 ° or less with respect to the normal H 1 of the back surface 11 a of the first light guide 11. By setting the inclination angle θa of the incident end face 12 in this manner, the first light guide can be efficiently performed without totally reflecting the light from the light source unit 17 on the incident end face 12 (the interface with the outside air). It can be taken into the body 11.

As described above, the first light guide 11 having the incident end face 12 as an inclined surface is provided with the first light guide 11 as shown in FIG.
The distance from the first step surface 15 closest to 2 to the edge of the light guide 11 on the incident end surface 12 side is a, and the first step surface 15
And a distance to the upper end of the incident end face 12 is a ′,
The above equation (1) "s = P (d1 -d2) / ｛L- (a +
b)｝ ”can be designed based on an equation in which a is replaced by a = a ′ + d1 tan θa (where θa ≦ 60 °).

The light guide 11 shown in FIG.
And the plurality of stepped surfaces 15 are inclined at inclination angles of θa and θs with respect to the normal line H1 of the light guide back surface 11a, respectively.
Let a and a in the equation be a = a '+ d1 tan θa (where θ
a ≦ 60 °), P = P ′ + s tan θs (where θs =
−5 ° to 60 °).

In this embodiment, the incident end face 12
As shown in FIG. 6, the inclined surface is inclined so as to retreat toward the other end of the light guide plate 11 toward the upper end, but the incident end surface 12 is opposite to the lower end in FIG. The light guide plate 11 may have an inclined surface that is inclined so as to recede in the other end direction. In this case, the angle of inclination of the incident end surface is also set with respect to the normal line H1 of the back surface 11a of the first light guide 11. 60
° or less is desirable.

FIG. 7 shows a fourth embodiment of the present invention.
8 is a side view of the light guide 11, and FIG. In this embodiment, the stepped surface 13 on the front surface of the first light guide 11 has a plurality of step surfaces 14 between the step surfaces 15.
The plurality of step surfaces 15 are inclined with respect to the back surface 11a of the first light guide 11 in a direction to increase the distance from the back surface 11a from the base end to the tip of the step surface 14.
Are formed so as to be substantially perpendicular to the back surface 11a of the first light guide 11.

In this embodiment, the first stepped surface 15
The highest first step surface 14 between the light guide body 11 and the last step surface 14 between the last step surface 15 and the other end of the light guide 11 is substantially the same as the light guide back surface 11a. They are formed on parallel surfaces.

The light guide 11 of this embodiment is different from that of the first embodiment in the shape of the stair-shaped surface 13 except for the shape of the step-shaped surface 13. Attached and omitted.

According to the light guide 11, the plurality of step surfaces 14 between the step surfaces 15 correspond to the back surface 11 a of the light guide back surface 11 a from the base end of the step surface 14 to the front end. Is inclined in the direction to increase the distance between
As compared with the case where the step surface 14 is formed parallel to the light guide back surface a as in the embodiment, the area of the step surface 15 is increased, and more light is emitted from the plurality of step surfaces. As a result, the strength can be increased.

Further, since the plurality of step surfaces 15 are substantially perpendicular to the back surface 11a of the light guide, the step surfaces 15 are almost invisible when the first light guide 11 is viewed from the front. In this way, the first light guide 11 can have reflection characteristics closer to those of a flat plate-like reflector.

As described above, when the plurality of step surfaces 14 are inclined surfaces, the inclination angle of the step surface 14 with respect to the back surface 11a of the first light guide 11 is desirably 10 ° or less. If the inclination angle of the step surface 14 is at this level, external light incident from the front can be reflected forward by the reflection films 16 provided on the plurality of step surfaces 14.

As shown in FIG. 6, the light guide 11 of this embodiment has a light guide length L, a height of the incident end face 12, a height of the other end face d 2, and a distance from the first stepped face 15. Light guide 11
A, the distance from the last stepped surface 15 to the other end of the light guide 11 is b, the pitch between the plurality of stepped surfaces 15 is P, Assuming that the height of the step 15 is s and the inclination angle θp of the step surface 14 with respect to the back surface 11a of the light guide is the following equation (2): s = [{(d1−d2) / [L− (a + b)]} + tan θp ] P can be designed based on (2). However, the pitch P of the plurality of step surfaces 15 is preferably in the range of 5 to 500 μm, and the inclination angle θp of the step surface 14 is desirably 10 ° or less.

FIG. 9 shows a first embodiment of the fifth embodiment of the present invention.
10 is an enlarged view of a part of the light guide 11 shown in FIG. In this embodiment, a step-shaped surface 13 on the front surface of the first light guide 11 is replaced with a plurality of step surfaces 14 between the step surfaces 15.
Are inclined at a predetermined angle with respect to the back surface 11a of the first light guide 11 in a direction in which the distance from the back surface 11a is increased from the base end of the step surface 14 toward the tip thereof, and The step surface 15 is formed in a shape inclined at a predetermined angle with respect to a normal line of the back surface 11a of the first light guide 11.

In this embodiment, the first stepped surface 15
The highest first step surface 14 between the light guide body 11 and the last step surface 14 between the last step surface 15 and the other end of the light guide 11 is substantially the same as the light guide back surface 11a. They are formed on parallel surfaces.

The light guide 11 of this embodiment is different from that of the first embodiment in the shape of the stair-shaped surface 13 except for the shape of the step-shaped surface 13. Attached and omitted.

According to the light guide 11, the plurality of step surfaces 14 between the step surfaces 15 correspond to the rear surface 11 a of the light guide back surface 11 a from the base end of the step surface 14 toward the front end. And the plurality of step surfaces 15 are inclined with respect to the normal H1 of the light guide back surface 11a, so that the area of the step surfaces 15 is further increased, More light can be emitted from the plurality of step surfaces 15 to increase the intensity.

In this embodiment, the inclination angle θp of the step surface 14 with respect to the back surface 11a of the first light guide 11 is desirably 10 ° or less as in the fourth embodiment. When the inclination angle of the light 14 is at this level, external light incident from the front can be reflected forward by the reflection film 16 provided on the plurality of step surfaces 14.

Also, the back surface 11a of the first light guide 11
The inclination angle θs of the step surface 15 with respect to the normal H1 is
As in the second or third embodiment, -5 ° to 60 °
, More preferably in the range of 25 ° to 30 ° (FIG. 10).
In this case, it is preferable that θs = about 27 °). By setting the inclination angle θs of the step surface 15 in this manner,
Light guided through the first light guide 11 and emitted from the plurality of step surfaces 15 can be efficiently emitted without being totally reflected by the step surfaces 15.

In the light guide 11 of this embodiment, as shown in FIG. 10, the pitch of the plurality of step surfaces 15 is P, and the width of the step surface 14 (the lower end of one adjacent step surface 15 and the other step surface 15). If the distance from the upper end of the suffix P) is P ′, the above equation (2) “s
= [{(D1 -d2) / [L- (a + b)]} + tan θ
p] P ”, P = P ′ + s tan θs (where θs = −5 ° to 60
°) and can be designed based on the replaced equation.

FIG. 11 shows the intensity distribution of the light emitted from the step surface 15 of the first light guide plate 11 of the first embodiment and the fifth embodiment described above, and FIG. Intensity distribution of light emitted from the step surface 15 in the light guide plate of the embodiment of the present invention,
(B) is an intensity distribution of light emitted from the step surface 15 in the light guide plate of the fifth embodiment.

This intensity distribution is obtained by measuring the intensity of the light emitted from the step surface 15 from various angles, and in FIG. 11A and FIG. The direction of the incident end face of the light body 11, 90 ° is the back surface 11 of the light guide plate 11.
The direction along the normal H1 of a, that is, 180 ° is the direction of the other end of the light guide plate 11.

As can be seen by comparing the above two intensity distributions, the intensity distribution of the light emitted from the step surface 15 in the light guide plate of the fifth embodiment shown in FIG. Compared with the intensity distribution of the light emitted from the step surface 15 in the light guide plate of the first embodiment,
(In the direction of °) is a much stronger intensity distribution.

Note that the light guide 11 of the fourth embodiment shown in FIGS. 7 and 8 and the light guide 11 of the fifth embodiment shown in FIGS. Although the light guide 11 is formed perpendicular to the back surface a of the light guide, the incident end face 12 of these light guides 11 is also provided with the back surface 11a of the light guide 11a as in the third embodiment shown in FIG. Is inclined at a predetermined angle θa (preferably 10 ° or less) with respect to the normal H1 of the first light guide 11 from the incident end face 12.
It is possible to guide the inside of the light guide 11 while refracting most of the light taken in by the plurality of step surfaces 14 and the light guide back surface 11a, and emit light with higher intensity from the plurality of step surfaces 15. it can.

Further, as shown in FIG. 1, an illumination panel using the first light guide 11 of the second to fifth embodiments is also provided as follows.
The light source unit 1 is located on the side of the incident end face 12 of the first light guide 11.
7 and the second light guide 20 is arranged on the front side of the first light guide 11.
Is not limited to the configuration shown in FIG.

For example, the second light guide 20 has a plurality of incident portions 21 formed on the rear surface thereof at intervals, and the light guide rear surface between these incident portions 21 is connected to the first light guide 20. Light body 11
The input and output surfaces may be opposed to the reflection film 16 on each of the step surfaces 14 at an inclination angle substantially parallel to or close to the reflection film 16.

The display device shown in FIG. 1 uses a liquid crystal display element 1 as a display means.
It can be applied to other electro-optical display devices and display devices using a translucent image printing film or the like as a display means, and the lighting panel of the present invention is not limited to display devices, but can be used for various purposes. Can be widely used.

[0142]

The illumination panel according to the present invention comprises an incident end face for taking in light incident from the side, a plurality of step surfaces, and a plurality of step surfaces connecting these step surfaces, and the pitch of the plurality of step surfaces. And a front surface on which a plurality of step surfaces are formed on a step-like surface having substantially the same height, and a reflection film is provided on substantially the entire surface of each of the plurality of step surfaces. A first light guide that emits the reflected light from the plurality of step surfaces and reflects light incident from the front forward by the reflection film on the plurality of step surfaces, and the first light guide A light source unit is arranged on the side of the incident end face of the first light guide, and the light emitted from the plurality of step surfaces is taken in and emitted forward from the front surface of the first light guide, and the light is emitted from the front. Emit incident light from the back and reflect on the plurality of steps Since the second light guide that emits light that is reflected by the film and enters from the rear surface forward is disposed, light from the light source unit disposed on the side is emitted forward and From the light source unit, and when the external light incident from the front is reflected and emitted, high brightness and Outgoing light having a uniform luminance distribution can be obtained.

In the display device of the present invention, the illumination panel of the present invention is disposed behind the transmissive display means. Therefore, the reflective display using external light and the illumination light from the light source unit are provided. Both the display and the transmissive display to be used can be made sufficiently bright, and a good image without luminance unevenness can be displayed in either display.

In the lighting panel of the present invention, the first
Preferably, the back surface of the light guide is a flat surface, and the plurality of step surfaces are respectively parallel to each other, and the plurality of step surfaces are respectively parallel to each other. It is possible to obtain emitted light having a suitable luminance distribution.

In this lighting panel, the first
The step-shaped surface of the light guide, the plurality of step surfaces are substantially parallel to the back surface of the first light guide, and the plurality of step surfaces are formed on the back surface of the first light guide. If it is formed in a shape that is substantially perpendicular to the first light guide, a reflection surface substantially parallel to the back surface of the first light guide can be formed by the reflection films provided on the plurality of step surfaces. When the light guide is viewed from the front, the step surface is hardly visible, so that the first light guide can have reflection characteristics closer to those of a flat plate-like reflector.

Further, the step-shaped surface may be formed such that the plurality of step surfaces are substantially parallel to the back surface of the first light guide, and the plurality of step surfaces are the back surface of the first light guide. If it is formed in a shape inclined at a predetermined angle with respect to the normal line, a reflection surface substantially parallel to the back surface of the first light guide is formed by the reflection film provided on the plurality of step surfaces, and the step surface is formed. As compared with the case where the surface is formed perpendicular to the back surface of the light guide, the area of the step surface can be increased, more light can be emitted from the plurality of step surfaces, and the intensity can be increased.

[0147] Further, the step-shaped surface may be formed such that the plurality of step surfaces increase the distance between the back surface of the first light guide and the rear surface from the base end to the front end of the step surface. If the plurality of step surfaces are formed in a shape substantially perpendicular to the back surface of the first light guide, the step surfaces are formed parallel to the back surface of the light guide. When the area of the stepped surface is increased as compared with the case, more light is emitted from the plurality of stepped surfaces, the intensity is increased, and when the first light guide is viewed from the front thereof. By making the step surface hardly visible, the first light guide can have reflection characteristics closer to those of a flat plate-shaped reflector.

Further, the step-shaped surface is formed such that the plurality of step surfaces increase the distance from the rear surface of the first light guide to the rear surface from the base end to the front end of the step surface. Direction, and the plurality of step surfaces are formed in a shape inclined at a predetermined angle with respect to a normal to the back surface of the first light guide, so that the area of the step surface is further increased, More light can be emitted from the plurality of step surfaces to increase the intensity.

As described above, in the case where the plurality of step surfaces are inclined surfaces, the inclination angle of the step surface with respect to the normal to the back surface of the first light guide is defined as the angle between the step surface and the step surface. When the direction in which the angle is large is a positive angle, and the direction in which the angle between the step surface and the step surface is small is a negative angle, it is preferable that the angle be in the range of −5 ° to 60 °. By setting the inclination angle of the step surface to
Light guided through the light guide body and emitted from the plurality of step surfaces can be efficiently emitted without being totally reflected by the step surfaces.

Further, as described above, when the plurality of step surfaces are inclined surfaces, the inclination angle of the step surface with respect to the back surface of the first light guide is desirably 10 ° or less. If the inclination angle of the step surface is at this level, external light incident from the front can be reflected forward by the reflection films provided on the plurality of step surfaces.

Furthermore, the incident end face of the first light guide is:
Although it may be a surface perpendicular to the back surface of the first light guide,
If the inclined surface is inclined at a predetermined angle with respect to the normal to the back surface of the first light guide, the first light out of the light from the light source unit may be used.
Light incident on the incident end face from a direction substantially parallel to the back surface of the light guide is also refracted at the incident end face and enters the first light guide. Most of the captured light is guided through the light guide while being refracted by the plurality of step surfaces and the back surface of the light guide, and higher intensity light can be emitted from the plurality of step surfaces. The light from the light source section can be emitted more efficiently forward, and high-brightness emitted light can be obtained.

When the incident end face of the first light guide is an inclined surface, the angle of inclination of the incident end face should be 60 ° or less with respect to the normal to the back surface of the first light guide. Desirably,
By setting the angle of inclination of the incident end face in this way, light from the light source section can be efficiently taken into the first light guide without being totally reflected by the incident end face.

Further, in the lighting panel of the present invention, the second light guide has, on its back surface, an incident surface for taking in light emitted from the plurality of step surfaces of the first light guide, and the incident surface. It is preferable to have a configuration having a plurality of projection-shaped incident portions having a refraction surface for refracting light incident from the front toward the front, and by using the second light guide having such a configuration, Most of the light emitted from the plurality of step surfaces of the first light guide can be taken into the second light guide without loss and emitted forward, and the emitted light can be increased in a predetermined direction. It can be a light having a luminance distribution with directivity and emitted with luminance.

[Brief description of the drawings]

FIG. 1 is a side view of a two-way display device including an illumination panel according to a first embodiment of the present invention.

FIG. 2 is an enlarged side view of a part of the lighting panel.

FIG. 3 is a side view of a first light guide of the lighting panel.

FIG. 4 is a side view of a first light guide showing a second embodiment of the present invention.

FIG. 5 is an enlarged view of a part of FIG. 4;

FIG. 6 is a side view of a first light guide showing a third embodiment of the present invention.

FIG. 7 is a side view of a first light guide showing a fourth embodiment of the present invention.

FIG. 8 is an enlarged view of a part of FIG. 7;

FIG. 9 is a side view of a first light guide showing a fourth embodiment of the present invention.

FIG. 10 is an enlarged view of a part of FIG. 9;

FIG. 11 is a diagram showing an intensity distribution of light emitted from a step surface of a first light guide plate according to the first embodiment and the fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element 10 ... Illumination panel 11 ... 1st light guide 12 ... Incident end face 13 ... Stepped surface 14 ... Step surface 15 ... Step surface 16 ... Reflection film 17 ... Light source part 20 ... 2nd light guide 21 incident part 21a incident surface 21b refracting surface

Claims (12)

[Claims] 1. An input end face for taking in light incident from the side, a plurality of step surfaces and a plurality of step surfaces connecting these step surfaces, and a pitch of said plurality of step surfaces is constant. A plurality of stepped surfaces having substantially equal heights, a plurality of stepped surfaces each having a front surface provided with a reflective film over substantially the entire surface thereof; and A first light guide that emits light from the stepped surface of the light guide and is incident from the front by the reflection film on the plurality of step surfaces; and a side of the incident end face of the first light guide. And a light source unit disposed on the front side of the first light guide, receives light emitted from the plurality of step surfaces of the first light guide, and emits the light forward. , Outgoing incident light from the front from the back, the first light guide A second light guide that emits light that is reflected by the reflective films on the plurality of step surfaces and enters from the rear surface toward the front. 2. A back surface of the first light guide is a flat surface,
The lighting panel according to claim 1, wherein the plurality of step surfaces are parallel to each other, and the plurality of step surfaces are parallel to each other. 3. The plurality of step surfaces are substantially parallel to the back surface of the first light guide, and the plurality of step surfaces are substantially perpendicular to the back surface of the first light guide. The lighting panel according to claim 2, wherein: 4. The plurality of step surfaces are substantially parallel to a back surface of the first light guide, and the plurality of step surfaces are predetermined with respect to a normal to a back surface of the first light guide. The lighting panel according to claim 2, wherein the lighting panel is inclined at an angle. 5. The method according to claim 1, wherein the plurality of step surfaces are inclined with respect to a back surface of the first light guide in a direction to increase a distance from the back surface toward a front end from a base end of the step surface. The lighting panel according to claim 2, wherein the plurality of step surfaces are substantially perpendicular to a back surface of the first light guide. 6. The stepped surface is inclined with respect to a back surface of the first light guide in a direction of increasing a distance from the back surface toward a tip end from a base end of the step surface, The lighting panel according to claim 2, wherein the plurality of step surfaces are inclined at a predetermined angle with respect to a normal to a back surface of the first light guide. 7. The inclination angle of the stepped surface with respect to the normal to the back surface of the first light guide is such that a direction in which the angle formed between the stepped surface and the stepped surface increases is a positive angle, The lighting panel according to claim 4, wherein, when a direction in which the angle formed by the step surface decreases becomes a negative angle, the angle is in a range of −5 ° to 60 °. 8. The lighting panel according to claim 5, wherein an inclination angle of the step surface with respect to a back surface of the first light guide is 10 ° or less. 9. The illumination according to claim 2, wherein the incident end face of the first light guide is inclined at a predetermined angle with respect to a normal to a back surface of the first light guide. panel. 10. The lighting panel according to claim 9, wherein an angle of inclination of the incident end face with respect to a normal to a back surface of the first light guide is 60 ° or less. 11. The second light guide has, on its back surface, an incident surface for taking in light emitted from the plurality of step surfaces of the first light guide, and a light incident from the incident surface forward. The lighting panel according to claim 1, further comprising a plurality of projecting incident portions having a refracting surface that refracts the light toward the light source. 12. A display device comprising: a transmissive display means for controlling transmission of light for display; and an illumination panel arranged opposite to a back side of the display means, wherein the illumination panel receives light incident from the side. Consisting of a plurality of step surfaces and a plurality of step surfaces connecting these step surfaces,
And a front surface in which the pitch of the plurality of step surfaces is constant, the height of these step surfaces is substantially equal to each other, and a reflection film is provided on substantially the entire surface of each of the plurality of step surfaces. A first light guide that emits light taken in from the incident end face from the plurality of step faces, and reflects light incident from the front forward by the reflection film on the plurality of step faces; A light source unit disposed on the side of the incident end face of the first light guide; and a light source unit disposed on a front side of the first light guide, from the plurality of step surfaces of the first light guide. While taking in the emitted light and emitting the light forward, the incident light from the front is emitted from the back surface, and is reflected by the reflective films on the plurality of step surfaces of the first light guide from the back surface. And the second light guide that emits the incident light forward. Characteristic display device.