JP2001133774A - Surface light emitting body, reflection type liquid crystal display device, and electronic appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance as a surface light emitting body by preventing sticking of dust on the inclined face of a light guide plate and by preventing formation of a double image. SOLUTION: A wedge-like groove 22D consisting of a gentle slope part 22a in a planar stripe-shape and a steep slope part 22b, and a flat part 22e adjacent to the groove 22D are formed on the surface of a light guide plate 22, and this structure is repeatedly formed in the left and right directions of the figure. The direction of the normal line H2 of the slope in the gentle slope part 22a is controlled to the direction (upper left direction in the figure) not facing the main observation direction α, and the angle θ2 of the slope of the gentle slope part 22a and the main observation direction α is controlled to a range from 0 deg. to 70 deg.. A transparent flat member 24 consisting of an acrylic resin or the like is optically adhered to the surface of the light guide plate 22 with an adhesive having the same refractive index as that of the light guide plate so as to cover at least the effective face and the transmission face of the light guide plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light-emitting device, a reflective display device, and an electronic apparatus, and more particularly to a display device disposed on the front side of a display surface for illuminating the display surface at night or the like. The present invention relates to a structure of a planar illuminant suitable for being configured as a front light, and a reflective display device and an electronic apparatus including the same.

[0002]

2. Description of the Related Art A reflection type liquid crystal display panel having low power consumption is conventionally used for portable equipment and the like, but there is a problem that a display cannot be seen in a dark place such as at night. On the other hand, the transmissive liquid crystal display panel is equipped with a backlight so that the display can be viewed in a dark place. There is a problem that the display is difficult to see.

In order to solve the above-mentioned problems, a light guide plate is provided in front of a reflection type liquid crystal display panel, and light from a light source such as a cold-cathode tube arranged near an end of the light guide plate is transmitted through the light guide plate. And a liquid crystal display device with a front light, which is a planar light-emitting body that allows the display to be viewed in dark places by irradiating light from the surface of the light guide plate toward the liquid crystal display panel. Have been. In a liquid crystal display device equipped with a front light, the liquid crystal display panel can be viewed through the light guide plate in the daytime, so that the liquid crystal display panel can be used as a normal reflective liquid crystal display panel. And the display can be made visible.

FIG. 7 shows a schematic structure of a conventional front light 120 having a flat upper surface of a light guide plate. Front light 12
Reference numeral 0 denotes a light source 121 such as a cold cathode tube, and a light guide plate 122 made of a high refractive index material such as an acrylic resin formed in a plate shape so as to introduce light from the light source 121 from the end face 122d and guide the light to the right side in the drawing. And a reflector 123 arranged so as to surround the light source 121. A gentle slope portion (working surface portion) 1 having a gentle inclination angle on the surface of the light guide plate 122.
Wedge-shaped groove 122D formed from steep slope portion 122b having a steeper inclination angle than 22a and gentle slope portion 122a.
And a flat portion 122e adjacent to the groove 122D are formed periodically toward the right side in the figure. These grooves 122D
The flat portion 122e is configured to extend in a stripe shape in the direction of the paper of the drawing. Here, the normal H12 of the inclined surface of the gentle slope portion 122a is provided so as to face the main observation direction α, that is, to face the near side of the liquid crystal display device. On the other hand, the back surface 122c of the light guide plate 122 is formed flat.

When light from the light source 121 is introduced into the light guide plate 122, the light is totally reflected on the inner surface of the light guide plate 122,
The light is transmitted to the right side in the figure.
22A is emitted downward from the rear surface 122c. For this reason, light can be irradiated downward on the plate surface of the light guide plate 122. When the light guide plate 122 is viewed from above the light guide plate 122, the light guide plate 122 itself is formed of a transparent material, so that the light guide plate 122 can be transmitted and the display below the light guide plate 122 can be viewed.

[0006]

In the above-described front light 120, since the inclined surfaces 122a and 122b are formed on the surface of the light guide plate, dust easily adheres to the inclined surfaces 122a and 122b, and the visibility of the display is improved. There is a problem of worsening. In addition, there is a problem that the light guide plate surface is scratched in an attempt to forcibly wipe off and remove the adhered dust, and light is scattered on the scratches, thereby deteriorating the visibility of the display.

In the reflection type liquid crystal display device provided with the front light 120, strong external light such as sunlight or fluorescent light exists in a specific direction, and external light in a direction other than the specific direction. Is weak, specifically, when the external light L exists in the direction as shown in FIG. 7, and when the external light in other directions is weak, there is a problem that the image is observed twice.

FIG. 8 schematically illustrates a problem of a double image when the front light 120 is used. At this time, the liquid crystal panel is formed on the upper substrate 160 and the lower substrate 170 by the liquid crystal layer 15.
A reflection type liquid crystal panel in which a reflection layer is formed on the upper surface of the lower substrate 170 sandwiching 0. The built-in light source is the light guide plate 12
2, the light guided into the light guide plate from the light source is turned downward by the light guide plate 122, and the light guide plate lower surface 1
Emitted from 22c and guided to the liquid crystal panel. The light guided to the inside of the liquid crystal panel is reflected when reaching the reflection layer in the liquid crystal panel, goes out of the liquid crystal panel, passes through the inside of the light guide plate 122 and is emitted to the outside of the light guide plate, and is observed by the eyes of the observer. Reach.

In a state where the display is observed with ordinary ambient light having no remarkably strong external light in a specific direction, light from various directions passing through the light guide plate 122 is transmitted to the display section X as shown in FIG. The light is reflected, transmitted through the liquid crystal layer 150, the upper substrate 160, and the inside of the light guide plate 122, emitted to the outside of the light guide plate at an emission angle θ _OUT , and reaches the eyes of the observer. At this time, the display is observed at the same position as the display unit X.

However, when viewing the liquid crystal display device, as shown in FIG. 8B, strong light incident at an incident angle θ _IN from a specific direction (the back side of the front light) is used.
2. When transmitted through the upper substrate 160 and the liquid crystal layer 150, reflected at the display unit X, transmitted through the liquid crystal layer 150, the upper substrate 160 and the light guide plate 122, and emitted to the outside of the light guide plate, Through the gentle slope 122a on the light plate surface,
When the light is emitted to the outside of the light guide plate at the emission angle θ _OUT , the image is observed as if there is an image in the adjacent part Y slightly separated from the display part X toward the observer. As a result, the image is double-viewed so that the display exists in both the original display portion X and the adjacent portion Y farther from the display portion X. Further, the longer the distance between the display portion X and the gentle slope portion (working surface portion) 122a, the greater the distance of the double image. For example, the thickness of the light guide plate 122 is about 1 mm, and the depth of the groove 122D is smaller. 10 to several tens of μm, thickness of upper substrate 160 is 500 μm
The distance between the light guide plate 122 and the upper substrate 160 is 500 μm
In the case where the thickness of the liquid crystal layer 150 is several μm, a deviation of several pixels (several hundred μm to several mm) occurs depending on the incident angle. Naturally, the stronger the light incident at the incident angle θ _IN , the more clearly the image seen in the adjacent portion Y can be seen, and if the light is weak, the image cannot be seen.

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent dust from adhering to an inclined surface formed on the surface of a light guide plate, thereby improving the performance as a planar light-emitting body. Is to improve.

It is a further object of the present invention to improve the performance as a planar illuminant by preventing double images.

[0013]

Means for Solving the Problems A first means taken by the present invention to solve the above problems is to introduce a light source and light emitted from the light source from an end face, and to transmit the light along a light guiding direction. A light guide plate formed so as to gradually emit from one plate surface, and on the plate surface of the light guide plate, the direction of light emitted by the light source is changed inside the light guide plate and the one A plurality of working surface portions for emitting illumination light by emitting from the plate surface, and a plurality of transmission surface portions configured to confine light emitted from the light source in the light guide plate and to allow the light guide plate to be seen through are arranged. In the planar light emitting device, a flat plate member that covers at least the working surface portion and the transmission surface portion of the light guide plate is disposed on the surface of the light guide plate.

[0014] The planar light-emitting body may be configured such that, in a predetermined direction on the plate surface of the light guide plate, the grooves having the gently inclined working surface and the steeply inclined transmission surface and the flat transmission surface are alternately formed. Desirably, it is formed repeatedly. Such a repetitive structure makes it possible to make visibility deterioration due to unevenness on the plate surface less noticeable.

According to this measure taken by the present invention, by disposing a transparent flat plate member covering at least the working surface portion and the transmission surface portion of the light guide plate on the light guide plate surface, the inclined surface portion formed on the light guide plate surface Since the adhesion of dust to the upper part can be prevented, the visibility of the display can be improved.

Further, in the planar light emitting device according to the present invention, the light guide plate and the flat plate member have the same refractive index, and the light guide plate and the flat plate member are optically bonded to each other, so that the upper surface of the light guide plate is formed. In addition, deterioration of visibility due to light reflection on the lower surface of the flat plate member can be made inconspicuous.

In the planar light emitting device according to the present invention, the working surface portion may have a predetermined inclination angle in which the normal direction of the inclined surface of the working surface portion is set to be opposite to a main observation direction in the plate surface shape. The direction of the light is changed using the total reflection of the light according to the inclination angle, and the light is emitted to the outside to obtain the illumination light.

In the planar light emitting device according to the present invention, the working surface portion has an angle between the inclined surface of the working surface portion and a main observation direction set within a range of 0 ° to 70 ° on the plate surface. An inclined surface having a predetermined inclination angle may be used. In this case, a double image can be further prevented. The reason why double images can be prevented will be described later.

In the planar light emitting device according to the present invention, the working surface portion has a predetermined inclination angle on the plate surface, the normal of the inclined surface of the working surface portion being set to a direction not facing the main observation direction. It may be an inclined surface portion having. In this case, a double image can be further prevented. The reason why double images can be prevented will be described later.

The second means adopted by the present invention is formed so that a light source and light emitted from the light source are introduced from an end face and the light is gradually emitted from one of the plate faces along the light guide direction. A light guide plate, and inside the light guide plate, an operating surface portion for changing the direction of light emitted from the light source inside the light guide plate and emitting light from the one plate surface to form illumination light. A plurality of hollow portions are formed.

It is preferable that the planar luminous body is formed by periodically forming the hollow portion having the working surface portion inside the light guide plate. With such a periodic structure, the deterioration of visibility due to the formation of the hollow portion can be made inconspicuous.

According to this measure taken by the present invention, by forming a hollow portion having a working surface inside the light guide plate,
Since the inclined surface portion of the light guide plate is formed only inside the light guide plate,
Since dust can be prevented from adhering to the inclined surface of the light guide plate, display visibility can be improved.

In the planar light emitting device according to the present invention, the working surface portion may have a predetermined inclination angle in the plate shape, the normal line of the inclined surface of the working surface portion being set to a direction opposite to a main observation direction. The direction of the light is changed using the total reflection of the light according to the inclination angle, and the light is emitted to the outside to obtain the illumination light.

In the planar light emitting device according to the present invention, the angle between the inclined surface of the working surface and the main observation direction is set in the range of 0 ° to 70 ° on the plate surface. An inclined surface having a predetermined inclination angle may be used. In this case, a double image can be further prevented. The reason why double images can be prevented will be described later.

In the planar light emitting device according to the present invention, the working surface portion has a predetermined inclination angle on the plate surface, the normal of the inclined surface of the working surface portion being set to a direction not facing the main observation direction. It may be an inclined surface portion having. In this case, a double image can be further prevented. The reason why double images can be prevented will be described later.

According to each of the above-mentioned means adopted by the present invention, a transparent flat plate member covering at least the operation surface portion and the transmission surface portion of the light guide plate is disposed on the surface of the light guide plate, or a hollow plate having an operation surface portion inside the light guide plate. By forming the portion, it is possible to prevent dust from adhering to the inclined surface portion of the light guide plate, so that the visibility of display can be improved.

In particular, when the angle between the inclined surface of the working surface portion and the main observation direction is set in the range of 0 ° to 70 °, or the normal direction of the inclined surface of the working surface portion is the main observation direction. If the direction is set so as not to be opposite to the direction, a double image can be prevented.

[0028] In any one of the above planar light-emitting bodies of the present invention, it is preferable that the light source and the light guide plate are configured as front lights arranged on the front side of a display surface of a reflective display device. Here, usually, the working surface portion is provided as an inclined surface on or near the other plate surface opposite to the one plate surface that emits illumination light in the light guide plate. The present invention is particularly effective in such a case as preventing dust from adhering to the inclined surface formed on the light guide plate or preventing double images.

Further, by providing this planar light-emitting body on the front side of the display surface, it is possible to constitute a reflective display device that can be visually recognized even in a dark place. Further, by providing the planar light emitter on the front side of the display surface, various electronic devices having a display surface that can be visually recognized even in a dark place can be configured.

Here, when the angle between the inclined surface of the working surface of the light guide plate and the main observation direction is set in the range of 0 ° to 70 °, or the normal of the inclined surface of the working surface of the light guide plate is set. The reason why double images can be prevented when the direction is set so as not to face the main observation direction will be described.

In order to solve the problem of the double image described above, the present inventor pays particular attention to the angle of the incident angle θ _IN of the external light and the angle of the inclination angle θa of the working surface, and carries out various studies and experiments. results superimposed, angle of incident angle theta _iN external light when the double image occurs was investigated that depends on the tilt angle θa of action surface.

FIG. 9 shows a reflection type liquid crystal display device provided with the front light 120 as shown in FIG. 7 when the inclination angle θa of the gentle slope portion (working surface portion) 122a is 43 degrees. Is a graph showing the relationship between the angle of incident angle θ _IN of external light and the angle of emission angle θ _OUT when a double image is formed on the observer side from the display unit X when obliquely viewing the image toward the observer. It is.

From the graph of FIG. 9, it can be seen that a gentle slope portion (working surface portion).
If 122a of θa is 43 °, theta in the direction of _{I N} is 45 theta _OUT when ° is 20 °, theta _OUT when the theta _IN is 25 ° in the direction of 0 °, further theta _IN is 10 ° Θ _OUT is −
The direction is 20 °. When there is strong incident light from the direction of θ _IN, a double image occurs when the display is viewed from the direction of θ _OUT . Specifically, θ _OUT is 20 °, 0 °,
FIG. 10 is a simplified diagram illustrating the appearance of a double image seen when the display is viewed from the direction of −20 °. In the same figure, the display viewed with normal ambient light is shown as the light in the θ _OUT1 direction, and the light that appears as a double image due to the strong external light is shown as the light in the θ _OUT2 direction. In FIG. 10A, the display viewed with normal ambient light is θ.
_{When OUT1} is viewed from the direction of 20 °, if strong external light L is in the direction of _θIN of 45 °, light will be emitted in the direction of _θOUT2 of 20 °, so the double image will be in the Y position. Will be visible. Similarly, when viewed from the direction where θ _OUT is 0 ° and −20 °, the appearance of the double image Y due to the light in the θ _OUT2 direction generated due to the strong external light L is shown in FIG. , FIG. 10 (c)
Shown in At this time, the larger the angle of θ _IN, the larger the shift of the double image.

Based on the results shown in FIG. 9, the present inventor has made further studies and experiments. As a result, if the display section X is viewed from the direction in which θ _OUT becomes negative,
When the angle between the inclined surface of the working surface of the light guide plate and the main observation direction is set in the range of 0 ° to 70 °, or the direction of the normal of the inclined surface of the working surface of the light guide plate is the main observation direction. When the liquid crystal display device is tilted toward the observer when viewed in a direction not facing the direction, a double image cannot be formed in front of the display unit (observer side). I found out that I could not see it.

[0035]

Next, an embodiment according to the present invention will be described in detail. FIGS. 1 to 4 show front lights 10, 20, 3 which are embodiments of a planar light-emitting body according to the present invention.
It is a schematic sectional drawing which shows the structure of 0, 40 typically.

First Embodiment FIG. 1 is a schematic sectional view schematically showing a structure of a front light 10 which is an embodiment of a planar light emitting device according to the present invention.
The front light 10 includes a light source 11 composed of a cold cathode tube or the like.
And a transparent light guide plate 12 made of an acrylic resin, a polycarbonate resin, or the like, and a reflector 13 surrounding the light source 11. On the surface of the light guide plate 12, a gentle slope portion (working surface portion) 12a and a steep slope portion 1 having a planar stripe shape are provided.
A wedge-shaped groove 12D formed from 2b and a flat portion 12e adjacent to the groove 12D are provided, and are formed repeatedly in the left-right direction in the figure. Here, the direction of the normal H1 of the inclined surface of the gentle slope portion (working surface portion) 12a is set to a direction (upper right direction in the figure) facing the main observation direction α. The back surface 12c of the light guide plate 12 is a flat surface. In the light guide plate 12, the light emitted from the light source 11 is radiated downward by using the total reflection at the gentle slope 12a, and the illumination light 12A can be obtained. A transparent flat plate member 14 having the same refractive index as that of the light guide plate 12 made of acrylic resin, polycarbonate resin or the like is provided on the surface of the light guide plate 12 so as to cover at least the working surface portion and the transmission surface portion of the light guide plate.
Are optically bonded with an acrylic or epoxy adhesive having the same refractive index as the light guide plate 12. Flat plate member 14
Is formed of a transparent material, so that the visibility of the display is not affected even if the flat plate member 14 is arranged. By disposing such a transparent flat plate member 14, the inclined surface portion 1
Since dust can be prevented from adhering to 2a and 12b, the visibility of display can be improved.

Second Embodiment FIG. 2 is a schematic sectional view schematically showing a structure of a front light 20 which is an embodiment of a planar light emitting device according to the present invention. The front light 20 is a light source 2 composed of a cold cathode tube or the like.
1, a transparent light guide plate 22 configured to introduce light from an end face 22d and made of an acrylic resin or a polycarbonate resin, and a reflective plate 23 surrounding the light source 21. On the surface of the light guide plate 22, a wedge-shaped groove 22D formed by a flat stripe-shaped gentle slope portion (working surface portion) 22a and a steep slope portion 22b, and a groove 22D
Is provided adjacent to the flat portion 22e, and the flat portion 22e is formed repeatedly in the horizontal direction in the figure. Here, the direction of the normal H2 of the inclined surface of the gentle slope portion (working surface portion) 22a is set so as not to face the main observation direction α (upper left direction in the figure), and the inclined surface of the gentle slope portion 22a and the main observation direction are set. The angle θ ₂ formed with α is set in the range of 0 ° to 70 °. The back surface 22c of the light guide plate 22 is a flat surface. In the light guide plate 22, the light emitted from the light source 21 is radiated downward by using the total reflection at the gentle slope portion 22a, and the illumination light 22A can be obtained. On the surface of the light guide plate 22, a flat plate member 24 having the same refractive index as the transparent light guide plate 22 made of an acrylic resin, a polycarbonate resin or the like so as to cover at least the working surface portion and the transmission surface portion of the light guide plate.
Are optically bonded with an acrylic or epoxy adhesive having the same refractive index as the light guide plate 22. Since the flat plate member 24 is formed of a transparent material, the placement of the flat plate member 24 does not affect the visibility of display. By disposing such a transparent flat plate member 24, the inclined surface portion 22a
And 22b can be prevented from adhering dust.
The visibility of the display can be improved. Further, in the present embodiment, the direction of the normal H2 of the inclined surface of the gentle slope portion (working surface portion) 22a is set to a direction not facing the main observation direction α (upper left direction in the drawing), and the inclination of the gentle slope portion 22a is set. Since the angle θ ₂ between the surface and the main observation direction α is set in the range of 0 ° to 70 °, when viewing the liquid crystal display device provided with the present embodiment, strong external light is mainly emitted in the main observation direction α. Even when external light is present in a direction opposite to the above and the external light in other directions is weak, the image is not double-observed, so that the visibility of the display can be improved.

Third Embodiment FIG. 3 is a schematic sectional view schematically showing a structure of a front light 30 which is an embodiment of a planar light emitting device according to the present invention. The front light 30 is a light source 3 composed of a cold cathode tube or the like.
1, a transparent light guide plate 32 configured to introduce light from an end face 32d and made of an acrylic resin or a polycarbonate resin, and a reflective plate 33 surrounding the light source 31. Inside the light guide plate 32, a gentle slope portion (working surface portion) 32a of a plane stripe shape, a steep slope portion 32
b and a hollow portion 3 having a triangular cross section having a flat surface portion 32f.
2D is repeatedly formed in the horizontal direction in the figure. The hollow portion 32D is formed closer to the front surface 32e than the rear surface 32c of the light guide plate. Here, a gentle slope portion (action surface portion) 32
The direction of the normal H3 of the inclined surface a is set to a direction (upper right direction in the figure) facing the main observation direction α. Also,
The front surface 32e and the back surface 32c of the light guide plate 32 are flat surfaces. In the light guide plate 32, the light emitted from the light source 31 is radiated downward by using the total reflection at the gentle slope portion 32a, and the illumination light 32A can be obtained. Inclined surface part 3
By forming the 2a and the steep slope portion 32b inside the light guide plate 32, dust can be prevented from adhering to the slope portions 32a and 32b, so that the visibility of the display can be improved.

Fourth Embodiment FIG. 4 is a schematic sectional view schematically showing a structure of a front light 40 which is an embodiment of a planar light emitting device according to the present invention. The front light 40 is a light source 4 composed of a cold cathode tube or the like.
1, a transparent light guide plate 42 configured to introduce light from an end face 42d and made of an acrylic resin or a polycarbonate resin, and a reflective plate 43 surrounding the light source 41. Inside the light guide plate 42, a gentle slope portion (operating surface portion) 42a of a plane stripe shape, a steep slope portion 42
b and a hollow portion 4 having a triangular cross section having a flat surface portion 42f.
2D is repeatedly formed in the horizontal direction in the figure. The hollow portion 42D is formed closer to the front surface 42e than the rear surface 42c of the light guide plate. Here, a gentle slope portion (action surface portion) 42
The direction of the normal H4 of the inclined surface a is set so as not to face the main observation direction α (upper left direction in the figure), and the angle θ ₄ between the inclined surface of the gentle slope portion 42a and the main observation direction α.
Is set in the range of 0 ° to 70 °. The front surface 42e and the back surface 42c of the light guide plate 42 are flat surfaces. In the light guide plate 42, the light emitted from the light source 41 is radiated downward using the total reflection at the gentle slope portion 42a, so that the illumination light 42A can be obtained. Inclined surface 42
By forming the a and the steep slope portion 42b inside the light guide plate 42, dust can be prevented from adhering to the slope portions 42a and 42b, so that the visibility of display can be improved. Further, in the present embodiment, the direction of the normal H4 of the inclined surface of the gentle slope portion (working surface portion) 42a is set to a direction not facing the main observation direction α (upper left direction in the figure), and the gentle slope portion 42a is inclined. Since the angle θ ₄ formed between the surface and the main viewing direction α is set in the range of 0 ° to 70 °, when viewing the liquid crystal display device provided with the present embodiment, strong external light is emitted in the main viewing direction α. Even when external light is present in a direction opposite to the above and the external light in other directions is weak, the image is not double-observed, so that the visibility of the display can be improved.

In the first to fourth embodiments,
Although the working surface portion is configured with respect to the light guide plate formed near the surface on the viewer side, the present invention is not limited to the light guide plate having such a shape, and the vicinity of one of the front and back surfaces of the light guide plate is preferred. What is necessary is just to form the working surface for forming the illumination light and the transmitting surface for making the light guide plate transparent. Further, both the working surface portion and the transmission surface portion may be curved surfaces instead of flat surfaces. Further, the working surface portions need not be arranged in a stripe shape as described above, and may be dispersed and arranged in various forms within the plate surface of the light guide plate. Even in the light guide plate having such various shapes, a transparent flat plate member covering at least the working surface portion and the transmission surface portion of the light guide plate is disposed on the light guide plate surface, or the hollow portion having the working surface portion inside the light guide plate is provided. By forming
Since dust can be prevented from adhering to the inclined surface of the light guide plate, visibility as a planar light-emitting body can be improved. Further, by setting the direction of the normal line of the inclined surface of the working surface portion so as not to be opposed to the main observation direction, or by setting the angle between the inclined surface of the working surface portion and the main observation direction in the range of 0 ° to 70 °. When viewing a reflective display device provided with the present invention, strong external light exists in a direction opposite to the main observation direction, and even when external light in other directions is weak, an image is observed twice. , The visibility of the display can be further improved.

FIG. 5 shows a configuration example of a liquid crystal display or an electronic device using the front light 10 of the first embodiment. In this configuration example, the front light 10
A reflection type liquid crystal display device 100 is arranged behind the display. In the liquid crystal display device 100, a liquid crystal layer 103 is sealed in a liquid crystal cell in which a substrate 101 and a counter substrate 102 are bonded with a sealant interposed therebetween. A pixel electrode 101a also serving as a reflective layer is formed on the inner surface of the substrate 101, and a transparent counter electrode 102a is formed on the inner surface of the counter substrate 102.

The light guide plate 1 of the front light 10 is located at a front position substantially corresponding to the effective display area of the liquid crystal display device 100.
2 are arranged. The light emitted from the light source 11 of the front light 10 is reflected by the gentle slope as described above, introduced into the liquid crystal display device 100, reflected by the pixel electrode 101a, and introduced again into the light guide plate 12. Are transmitted through the light guide plate 12 and emitted to the outside.

At this time, since the transparent flat plate member 14 is formed on the surface of the light guide plate 12 so as to cover at least the working surface portion and the transmission surface portion of the light guide plate as described above, the dust on the inclined surface portion of the light guide plate is formed. Can be prevented, so that the visibility of the display can be improved. In the present embodiment, the front light 10 is replaced with the second to fourth lights.
The front lights 20, 30, and 40 of the embodiment may be applied. In particular, when either the front light 20 or the front light 40 is applied, the direction of the normal of the inclined surface of the gentle slope portion (working surface portion) is set so as not to face the main observation direction, and the inclined surface of the gentle slope portion is also set. Is set in the range of 0 ° to 70 °, and when viewing the liquid crystal display device, strong external light is present in a direction opposite to the main viewing direction, and in other directions, Even when the external light is weak, the image will not be observed twice,
Further, the visibility of the display can be improved.

Other Embodiments of Electronic Apparatus Next, the front light 1 of the first to fourth embodiments will be described.
A specific example of an electronic device including any one of 0, 20, 30, and 40 will be described.

FIG. 6A is a perspective view showing an example of a portable telephone. In FIG. 6A, reference numeral 200 denotes a mobile phone main body, and reference numeral 201 denotes a liquid crystal display unit using any of the front lights 10, 20, 30, and 40 of the first to fourth embodiments.

FIG. 6B is a perspective view showing an example of a portable information processing device such as a word processor or a personal computer. Fig. 6 (b)
In the figure, 300 is an information processing apparatus, 301 is an input unit such as a keyboard, 303 is an information processing main body, and 302 is the front lights 10, 20, 3 of the first to fourth embodiments.
A liquid crystal display unit using either 0 or 40 is shown.

FIG. 6C is a perspective view showing an example of a wristwatch-type electronic device. In FIG. 6C, reference numeral 400 denotes a watch main body, and reference numeral 401 denotes a liquid crystal display unit using any of the front lights 10, 20, 30, and 40 of the first to fourth embodiments.

Each of the electronic devices shown in FIGS. 7A to 7C is a front light 1 of the first to fourth embodiments.
Since it is provided with a liquid crystal display unit using any one of 0, 20, 30, and 40, it is possible to prevent dust from adhering to the inclined surface of the light guide plate, so that the display quality is excellent. Become. In particular, when either the front light 20 or 40 is used, the image is not double-viewed even when viewing the liquid crystal display unit, so that the visibility of the display can be further improved.

[0049]

As described above, according to the present invention, a transparent flat plate member covering at least the working surface portion and the transmission surface portion of the light guide plate is disposed on the light guide plate surface, or a hollow having a slope portion inside the light guide plate. By forming the portion, it is possible to prevent dust from adhering to the inclined surface portion of the light guide plate, so that the visibility of display can be improved. Further, by setting the direction of the normal line of the inclined surface of the working surface portion to a direction not facing the main observation direction, or by setting the angle between the inclined surface of the working surface portion and the main observation direction within the range of 0 ° to 70 °. When viewing a reflective display device provided with the present invention, strong external light exists in a direction opposite to the main observation direction, and even when external light in other directions is weak, an image is observed twice. , The visibility of the display can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view schematically showing a structure of a front light as an embodiment of a planar light-emitting body according to the present invention.

FIG. 2 is a schematic cross-sectional view schematically showing a structure of a front light as an embodiment of a planar light-emitting body according to the present invention.

FIG. 3 is a schematic cross-sectional view schematically showing a structure of a front light as an embodiment of a planar light-emitting body according to the present invention.

FIG. 4 is a schematic cross-sectional view schematically showing a structure of a front light as an embodiment of a planar light-emitting body according to the present invention.

FIG. 5 is a schematic configuration diagram schematically showing a structure in which a front light is arranged on the front surface of a reflection type liquid crystal display device as a configuration example of a liquid crystal display or an electronic device using the embodiment.

6A is a diagram illustrating an example of a mobile phone using the embodiment, FIG. 6B is a diagram illustrating an example of a portable information processing device using the embodiment, and FIG. c) is a diagram showing an example of a wristwatch-type electronic device using the embodiment.

FIG. 7 is a schematic sectional view showing the structure of a conventional front light.

FIGS. 8A and 8B are explanatory diagrams showing a problem of double images in a conventional front light.

FIG. 9 is a graph showing the relationship between the angle of incident angle θ _IN of external light in a conventional front light and the angle of emission angle θ _OUT when a double image is formed on the viewer side from the display unit X. It is.

FIGS. 10A to 10C are explanatory diagrams showing a problem of a double image in a conventional front light.

[Explanation of symbols]

10, 20, 30, 40 Front light 11, 21, 31, 41 Light source 12, 22, 32, 42 Light guide plate 12a, 22a Slowly inclined surface (working surface) 12b, 22b Steeply inclined surface (transmission surface) 12D, 22D groove 32a , 42a gentle slope portion (action surface portion) 32b, 42b steep slope portion 32D, 42D hollow portion 12c, 22c, 32c, 42c back surface 12d, 22d, 32d, 42d end surface 12e, 22e flat portion (transmission surface portion) 32e, 42e surface 32f, 42f Surface portion 12A, 22A, 32A, 42A Illumination light 13, 23, 33, 43 Reflector 14, 24 Flat plate member α Main observation direction H1, H2, H3, H4 Normal line θ ₂ , θ ₄ of slope of working surface Angle formed between working surface and main viewing direction 100 Liquid crystal display

Claims (14)

[Claims] 1. A light guide, comprising: a light source; and a light guide plate formed to introduce light emitted from the light source from an end face and to gradually emit the light from one of the plate faces along a light guide direction. On a plate surface of a light plate, a plurality of working surface portions for changing the direction of light emitted from the light source inside the light guide plate and emitting from one of the plate surfaces to form illumination light, and light emitted from the light source. In the light guide plate, and a plurality of transmission surface portions arranged so as to be able to see through the light guide plate are arranged, and at least the working surface portion of the light guide plate and the transmission surface are arranged on the light guide plate surface. A planar light-emitting body, comprising a transparent plate member covering a surface portion. 2. The planar light emitting device according to claim 1, wherein
In a predetermined direction on the plate surface of the light guide plate, the operation surface portion having a gentle inclination, the groove having the transmission surface portion having a steep inclination, and the flat transmission surface portion are alternately and repeatedly formed. Planar luminous body. 3. The planar light emitting device according to claim 1, wherein the light guide plate and the flat plate member have the same refractive index, and the light guide plate and the flat plate member are optically bonded. body. 4. One of claims 1 to 3
In the paragraph, the action surface portion is an inclined surface portion having a predetermined inclination angle set in a direction in which a normal line of the inclined surface of the action surface portion is opposed to a main observation direction in the plate surface shape. A planar light-emitting body. 5. The method according to claim 1, wherein:
In the item, the operating surface portion is an inclined surface portion having a predetermined inclination angle on the plate surface, wherein an angle between the inclined surface of the operating surface portion and a main observation direction is set in a range of 0 ° to 70 °. A planar light-emitting body, comprising: 6. Any one of claims 1 to 3
In the paragraph, the action surface portion is an inclined surface portion having a predetermined inclination angle set on the plate surface such that a normal line of the inclined surface of the action surface portion is not opposed to a main observation direction. A planar light-emitting body. 7. A light guide, comprising: a light source; and a light guide plate formed to introduce light emitted from the light source from an end face and to gradually emit the light from one plate surface along a light guide direction. Inside the light plate, the direction of the light emitted by the light source is changed inside the light guide plate, and a plurality of hollow portions having an operation surface portion for forming illumination light emitted from the one plate surface are formed. Characteristic planar light emitter. 8. The planar light emitting device according to claim 7, wherein:
The planar light-emitting body, wherein the hollow portion having the working surface portion is periodically formed repeatedly inside the light guide plate. 9. The operating surface portion according to claim 7, wherein, in the plate surface shape, a predetermined normal direction of an inclined surface of the operating surface portion is set to a direction opposite to a main observation direction. A planar light-emitting body, which is an inclined surface having an inclined angle. 10. The operating surface portion according to claim 7, wherein an angle between an inclined surface of the operating surface portion and a main observation direction is set in a range of 0 ° to 70 ° on the plate surface. A planar light-emitting body, characterized in that the planar light-emitting body has a predetermined inclined angle. 11. The operating surface portion according to claim 7, wherein a normal direction of an inclined surface of the operating surface portion on the plate surface is set to a direction not facing a main observation direction. A planar light-emitting body, which is an inclined surface having an inclined angle. 12. The method according to claim 1, wherein the light source and the light guide plate are configured as a front light disposed on a front side of a display surface of a reflective display device. Characteristic planar light emitter. 13. A reflective display device comprising the planar light emitting device according to claim 12 on a front side of a display surface. 14. An electronic apparatus, comprising: the planar light emitting device according to claim 12 on a front side of a display surface.