JP2000250034A - Display device and portable information device using display device - Google Patents

Abstract

(57) [Problem] To provide an air layer between a light guide layer and a protective layer, which increases the thickness of the entire device and reduces the size and size of the device.
A mechanism that keeps the air layer from becoming an obstacle to weight reduction
If the strength is insufficient, there are problems such as light leaking from the light guide layer and light interference occurring in the air layer, resulting in poor display visibility. SOLUTION: The front light illumination plate 2 includes a reflective liquid crystal panel 1 and a front light illumination plate 2. The front light illumination plate 2 includes a light guide layer 6 made of a transparent flat plate having a convex rib 5, and a light guide layer 6. And a protective layer 7 which is made of a material having a lower refractive index than the material described above and is provided in close contact with the light guide layer 6, so that the conventional air layer 118 needs to be formed in order to satisfy the condition of total reflection. With a simple configuration, the front light illumination plate 2 can be made thinner and lighter, and a predetermined strength and good display visibility can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having a front light illuminating plate for illuminating a liquid crystal panel, and a portable information device having the display device.

[0002]

2. Description of the Related Art Hitherto, liquid crystal display devices have been widely used as information display media for mobile phones and other portable information devices as display devices that operate with very small power. However, when this liquid crystal display device is used at night or in a dark environment, the display is dark because the light for reflection is weak, and the visibility is extremely poor. Therefore, as an effective means for illuminating the display unit with low power even at night or in a dark environment, a front light, that is, a lighting device arranged on the front side of the liquid crystal display device has been proposed, which will be described later. JP-A-10-1886
No. 36 discloses this.

Further, as a light source of a liquid crystal display device used for electronic equipment such as a portable telephone and a portable information device, a linear light source such as a fluorescent lamp, a light emitting diode (LED) operating at low power, a miniature light bulb, and the like are used. Are widely used. In the case of a fluorescent lamp, a white light source can be easily obtained.
On the other hand, when an LED or a miniature bulb is used, a special mechanism such as a booster is not required as compared with a fluorescent lamp, and it is light and compact. Also, since high frequency and high voltage are not used,
Excellent safety and does not become a source of radio interference. further,
Power control is easy, and low power consumption applications can be easily handled. In particular, the LED has a semi-permanent life, and has recently been formed to be able to emit red, green, blue, a mixture thereof, and white. When a light bulb is used, the life is shortened, but it is inexpensive and can be easily replaced. For this reason, in devices that value portability, L is used as the light source.
Point light sources such as EDs and miniature bulbs have been used.

When a front light is used for a display device,
In order to uniformly illuminate the entire surface of the liquid crystal panel, a light guide plate or a light guide layer for converting the light from the linear light source or the point light source into a uniform planar light source is generally used. Japanese Patent Application Laid-open No.
No. 0-188636. 11A and 11B are a plan view and an AA cross-sectional view schematically showing a mobile phone provided with a conventional display device, and FIG. 12 is a cross-sectional view showing a conventional display device. In FIG. 11, reference numeral 101 denotes a substrate on which various electronic components are mounted; 102, a liquid crystal panel disposed on the substrate 101;
It is a protection panel arranged on the upper part of. Reference numeral 104 denotes a front case, 105 denotes a rear case, 106 denotes a shield case, 107 denotes a key, 108 denotes a flip, 109 denotes a microphone, 110 denotes a receiver, 111 denotes a battery, and 112 denotes an antenna. Here, the mobile phone is required to be thin, but as shown in FIG. 11B, the substrate 101 is arranged over almost the entire length of the mobile phone, and the battery 111 is provided on the back side, and the liquid crystal panel is provided on the front side. Since the battery 102 is disposed, the battery 11 is required to reduce the thickness.
Reducing the thickness of the liquid crystal panel 1 or the liquid crystal panel 102 leads to a reduction in thickness. In recent years, miniaturization and thinning have progressed, and even in the case where the thickness is as thin as 0.1 mm, it is currently being evaluated in the industry.

Next, in FIG. 12, reference numeral 113 denotes a front light illuminating plate which is disposed opposite to the front surface of the liquid crystal panel 102 and illuminates the liquid crystal panel 102. The front light illuminating plate 113 is a light guide layer 11 made of a transparent flat plate having a convex rib 116 for diffusing a light ray 115 emitted from a light source 114 disposed on an end face and irradiating the liquid crystal panel 102 with the light ray 115.
7 and a protective layer 119 disposed on the front side of the light guide layer 117 with the air layer 118 interposed therebetween.

Next, the operation will be described. Light 115 emitted from the light source 114 is introduced into the light guide layer 117 and propagates through the light guide layer 117 at the interface with the air layer 118 while being totally reflected. Then, the light rays 115 incident on the convex ribs 116 are emitted toward the liquid crystal panel 102, and are illuminated uniformly to enhance the visibility.

[0007]

Since the conventional display device is constructed as described above, the light guide layer 117 and the protective layer 1 are formed.
An air layer 118 must be provided between the light guide layer 117 and the light guide layer 117 and the protective layer 119. A mechanism for holding the air layer 118 must be provided. If the mechanism is not achieved, the protective layer 119 is deformed by pressure or vibration to come into contact with the light guide layer 117, and light leaks from the light guide layer 117, There was a problem that light interference occurred in the air layer 118 and display visibility deteriorated.

[0008] Further, the portable information equipment having such a display device has another problem that, for the same reason, it is an obstacle to further reduction in size and weight, and display visibility is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to obtain a display device having good display visibility while further reducing the size and weight.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a portable information device having good display visibility while further reducing the size and weight.

[0011]

An illumination plate for a front light of a display device according to the present invention is arranged such that a back surface thereof is opposed to a front surface of the liquid crystal panel, and diffuses an introduced light beam to the liquid crystal panel. A transparent plate-shaped light guide layer having a light diffusion shape portion to be irradiated, and a transparent material having a lower refractive index than the material of the light guide layer, which is in close contact with substantially the entire front surface of the light guide layer. And a protective layer provided.

A lighting plate for a front light of a portable information device according to the present invention is arranged such that a back surface thereof is opposed to a front surface of the liquid crystal panel, and a light diffusing shape for diffusing introduced light and irradiating the liquid crystal panel. A transparent plate-shaped light guide layer having a portion, and a protective layer made of a transparent material having a lower refractive index than the material of the light guide layer and provided in close contact with substantially the entire front surface of the light guide layer. It has.

In the portable information device according to the present invention, the surface of the protective layer has an arbitrary curved shape.

In the display device according to the present invention, the light guide layer and the protective layer are made of a resin material, and are integrally formed by two-color molding.

In the display device according to the present invention, the protective layer is formed on the front surface of the light guide layer by printing or painting.

In the portable information device according to the present invention, a light source for emitting a light beam introduced into the light guide layer is mounted on the substrate, and light is emitted from the light source on an end face of the light guide layer. A light introducing means for introducing a light beam into the light guide layer is provided.

In the display device according to the present invention, the light diffusion shape portion is formed by projecting a plurality of inclined steps in the thickness direction of the light guide layer, and is protected from above when the liquid crystal panel is operated for display. The inclination of the inclined step is formed such that extraneous light incident through the layer and the light guide layer is bent toward the liquid crystal panel.

In the portable information device according to the present invention, the light diffusing shape portion is formed by projecting a plurality of inclined steps in the thickness direction of the light guide layer. The inclination of the inclined step is formed so that extraneous light incident through the protective layer and the light guide layer is bent toward the liquid crystal panel.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. A display device of a mobile phone as a portable information device will be described as an example. FIG. 1 shows Embodiment 1 of the present invention.
FIG. 1 is a cross-sectional view showing a display device according to the present invention. In the figure, reference numeral 1 denotes a liquid crystal panel, and 2 denotes a front light illuminating plate which is disposed to face the front surface of the liquid crystal panel 1 and illuminates the panel.
The front light illuminating plate 2 is a light guide made of a transparent flat plate having a convex rib (light diffusion shape portion) 5 for diffusing a light beam 4 emitted from a light source 3 disposed on an end surface and irradiating the liquid crystal panel 1 with the light beam. The light guide layer 6 includes a layer 6 and a protective layer 7 made of a transparent material having a lower refractive index than the material of the light guide layer 6 and provided in close contact with substantially the entire front surface of the light guide layer 6.

The light guide layer 6 and the protective layer 7 may be made of, for example, a transparent resin such as an acrylic resin, a polycarbonate resin, or an amorphous polyolefin resin, or an inorganic transparent material such as glass. The protective layer 7 is formed on the light guide layer 6 such that the light 4 introduced into the light guide layer 6 is totally reflected toward the liquid crystal panel 1 at the interface with the protective layer 7.
It is necessary to use a material having a refractive index lower than that of the material.

When the light guide layer 6 and the protective layer 7 are formed by resin molding, the light guide layer 6 and the protective layer 7 may be integrally molded by two-color molding, or may be formed by a two-color molding.
Can be laminated on the light guide layer 6 by printing or painting and brought into close contact.

Each of the convex ribs 5 has a rectangular cross section in the thickness direction of the light guide layer 6, and is formed parallel to each other in a direction perpendicular to the plane of FIG. As the light source 3, an LED, a miniature bulb, or the like can be used as a point light source. The other components of the mobile phone (not shown) are the same as those of the prior art, and the description is omitted.

Next, the operation will be described. The light beam 4 incident on the light guide layer 6 propagates through the light guide layer 6. At this time, since the protective layer 7 is made of a material having a lower refractive index than the material of the light guide layer 6, the total reflection condition is set. Thus, the light is propagated while being totally reflected toward the liquid crystal panel 1 at the interface with the protective layer 7. Then, the light beam 4 incident into the convex rib 5 is emitted toward the reflective liquid crystal panel 1 and illuminates the light uniformly, so that the visibility can be improved. Further, since the light guide layer 6 and the protective layer 7 are closely adhered and laminated, the scratches that occur with the use of the display device are damaged on the front side of the front light illumination plate 2, that is, not on the light guide layer 6 but on the protective layer 7. Often occurs on the surface of the. For this reason, the light beam 4 propagating through the light guide layer 6
Are not emitted from the scratches to generate a bright line or a bright point, and good display performance can be obtained.

As described above, according to the first embodiment, the light guide layer 6 and the protective layer 7 having a lower refractive index than this.
Are formed in close contact with each other to form the front light illuminating plate 2, so that the conventional air layer 11
8 need not be formed, and the light guide layer 6 and the protective layer 7
Are integrated, it is possible to have a strong configuration, and it is not necessary to provide a mechanism for holding the air layer.

Accordingly, the effect of obtaining a predetermined strength and good display visibility can be obtained while reducing the thickness and weight of the front light illumination plate 2 with a simple configuration. In particular, although recent mobile phones have already been considerably reduced in thickness and weight, as a result of creating a prototype in which the present invention is applied to a mobile phone, further reduction in thickness and weight can be achieved. It was confirmed that the display device could be reduced in thickness by about 1 mm and reduced in weight by about 1.5 g in terms of a liquid crystal panel equivalent to 1.6 inches.

Further, since the light guide layer 6 and the protective layer 7 are integrally molded by two-color molding or formed by printing or painting, both can be accurately and easily adhered and laminated. The reflection condition can be easily obtained, and the effect of realizing cost reduction by mass production can be obtained.

In the first embodiment, the description has been made assuming that the convex rib 5 is provided as the light diffusing shape portion. However, the shape is not limited as long as the light beam 4 can be diffused. As shown, a large number of convex protrusions (light diffusion shape portions) 8 formed in a substantially columnar shape may be provided on the light guide layer 6. Here, FIG. 2 is a cross-sectional view showing a light guide layer having convex protrusions.

Also, as an application example of the display device according to the present invention, a portable telephone as a portable information device has been described as an example. However, the present invention is not limited to this, and other portable information devices or watches, cameras, data terminal devices, etc. It is also possible to apply to various electronic devices.

Embodiment 2 FIG. 3 is a sectional view showing a display device according to Embodiment 2 of the present invention. The same or corresponding members as those already described are denoted by the same reference numerals, and redundant description will be omitted as appropriate. In FIG. 3, 7a
Is a protective layer whose surface is formed into a predetermined curved shape, which is formed so as to have a design that is compatible with a portion other than the front light illuminating plate 2 of a mobile phone (not shown) which often has a curved shape. It is. Other configurations and operations are the same as those in the first embodiment.

As described above, according to the second embodiment, an object on which the display device is to be installed (for example, a portable telephone).
Since it can be formed so as to conform to the design, it is possible to obtain an effect of providing an ideal shape in design to the installation object.

Embodiment 3 FIG. 4 is a cross-sectional view showing Embodiment 3 of the present invention, taking a mobile phone as an example. In FIG. 4, reference numeral 9 denotes a substrate on which various electronic components and a liquid crystal panel 1 and a light source 3 which constitute a portable information device (not shown) are mounted, and reference numeral 10 denotes an end face of the light guide layer 6;
Is a light guide (light introducing means) for causing the light beam 4 emitted from the light source to enter the light guide layer 6, and for example, a triangular prism-shaped optical prism can be used. When the light guide 10 is formed in close contact with the light guide layer 6, it is desirable to form the light guide from a material having substantially the same refractive index. Further, the light guide layer 6 and the light guide 10 can be formed integrally. Other configurations are the same as those in the first embodiment.

Next, the operation will be described. The light path 4 of the light beam 4 from the light source 3 is converted by the light guide 10 and introduced into the light guide layer 6. The introduced light beam 4 propagates in the light guide layer 6 while being totally reflected at the interface with the protective layer 7. Then, the light beam 4 that has entered the convex rib 5 is emitted toward the reflective liquid crystal panel 1 and illuminates the light uniformly, thereby enhancing the visibility.

As described above, according to the third embodiment, the light guide 10 is disposed on the end face of the light guide layer 6, and the light guide 4 is formed so that the light path of the light beam 4 can be converted and introduced into the light guide layer 6. Therefore, it is not necessary to dispose the light source 3 on the end face of the light guide layer 6, and the light source 3 can be mounted on the substrate 9. This eliminates the need for wiring from the substrate, which is required when the light source 3 is disposed on the end face of the light guide layer 6, thereby simplifying the structure of the display device and preventing a failure due to disconnection or the like. Is obtained.

Embodiment 4 FIG. 5 is a cross-sectional view showing a use state of the display device according to Embodiment 4 of the present invention, and shows how a liquid crystal panel is illuminated using external light. FIG. 6 is an enlarged sectional view showing the inclined step portion of the light guide layer when external light can be effectively used, and FIG. 7 is an enlarged sectional view showing the inclined step portion of the light guide layer when external light cannot be used effectively. In the figure, reference numeral 11 denotes a front surface of the light guide layer 6 and a plurality of rib-shaped inclined steps which are formed so as to protrude in the thickness direction thereof. In general, when a liquid crystal panel of a portable information device is operated for display, a large majority of external light is incident on the liquid crystal panel from above, whether indoors or outdoors. The inclined step portion 11 shown in FIG. 6 is formed such that the external light incident from above is bent toward the liquid crystal panel 1, and the inclined step portion 11 shown in FIG. The inclination is formed so as to bend toward the liquid crystal panel 1 side.

Next, the operation will be described. When the light source 3 is not used as the front light illumination, the liquid crystal panel 1 is illuminated using the external light 13. Since the external light 13 is light from sunlight or indoor lighting, the external light 13 is usually light from above the liquid crystal panel in a state where the liquid crystal panel is operated and displayed. Further, since the front light illumination plate 2 and the liquid crystal panel 1 are substantially parallel to each other, when the external light 13 is mirror-reflected to the liquid crystal panel 1 and guided toward the eyes in order to brighten the display, the external light 13 ′ The surface of the front light illuminating plate 2 is also reflected in the direction of the eyes by specular reflection, and the external light 13, ie, sunlight or light from indoor lighting, directly enters the eyes, so-called reflection occurs, and visibility becomes extremely poor. . Therefore, by setting the inclination direction or angle of the inclined step portion 11 as shown in FIGS.
It is possible to guide the liquid crystal panel 1 by effectively using the external light 13. In addition, since the reflected light from the liquid crystal panel 1 is also reflected in a direction substantially parallel to the normal line of the front light illuminating plate 2, the amount of the light rays 14 emitted to the eyes among the external light applied to the reflective liquid crystal panel Also increase. Furthermore, since the direction of the light ray 14 emitted in the direction of the eyes and the direction of the reflected light 15 reflected by the specular reflection on the surface of the front light illumination plate 2 are different, the sunlight on the surface of the front light illumination plate 2 and the image of indoor lighting are reflected. Is no longer included. Thus, the external light 13 can be effectively used, and a bright and easy-to-view display without reflection can be provided.

On the other hand, when the inclination direction or angle of the inclined step portion 11 is set as shown in FIG. 7, the external light 13 is blocked by the head or the body of the person 12 viewing the liquid crystal display, and the external light 13 is effectively used. It can be seen that the display cannot be used, and the display becomes difficult to see. Further, if external light 13 is incident from above, the reflected light from the liquid crystal panel 1 is emitted downward from the reflected light reflected by the protective layer 7 from the incident external light 13.
Poor visibility. Therefore, as described above, it is desirable to set the inclination direction or angle of the inclined step portion 11 as shown in FIG.

As described above, according to the fourth embodiment, since the external light 13 incident from above is inclined so as to bend toward the liquid crystal panel 1, it is emitted to the viewer 12 who views the liquid crystal display. The light beam 14 is directed in a direction substantially parallel to the normal line of the front light illuminating plate 2, so that the external light 13 can be effectively used, and an effect of providing a bright and easy-to-view display can be obtained.

In the fourth embodiment, the inclined step portion 11 of the light guide layer 6 is described as being provided on the surface on the protective layer 7 side. However, the present invention is not limited to this. Is also good. In this case, it is desirable to set the inclination direction or angle of the inclined step portion 11 as shown in FIG. This is because, when set as shown in FIG. 9, the external light 13 is blocked by the head or body of the person 12 viewing the liquid crystal display and is not effectively used, so that the display becomes difficult to see.
Also, when external light is incident from above, the visibility deteriorates as in the case of FIG. Here, FIG. 8 is an enlarged sectional view showing another inclined step portion of the light guide layer when external light can be effectively used, and FIG.
FIG. 4 is an enlarged cross-sectional view showing an inclined step portion of the light guide layer when external light cannot be used effectively.

Further, in the fourth embodiment, the protective layer 7 having a planar surface is shown. However, the present invention is not limited to this. For example, as shown in FIG. By coating the protective layer 7b with a certain thickness on the step 11, the shape may be similar to the inclined step 11. In this case, since the protective layer 7b can be formed extremely thin by printing, painting, or the like, further reduction in the material and weight can be expected. Here, FIG. 10 is an enlarged sectional view showing the protective layer coated on the light guide layer. Since the pitch at which the inclined steps 11 are formed is extremely small, the viewer 12 of the liquid crystal display does not feel uncomfortable with the surface of the protective layer 7b.

[0040]

As described above, according to the present invention, a protective layer made of a material having a lower refractive index than the material of the light guide layer is provided in close contact with almost the entire front surface of the light guide layer, Since the lighting plate for the front light is configured, it is not necessary to form an air layer as in the past in order to satisfy the condition of total reflection, and the front light lighting plate is made thinner and lighter with a simple configuration. There is an effect that a predetermined strength and good display visibility can be obtained.

According to the present invention, a protective layer made of a material having a lower refractive index than the material of the light guide layer is brought into close contact with substantially the entire front surface of the light guide layer in the display section of the portable upper device. The lighting plate for the front light is provided, so that it is not necessary to form an air layer as in the prior art. This has the effect that good display visibility can be obtained.

According to the present invention, since the surface of the protective layer has an arbitrary curved shape, the object to be installed on the display device (for example,
(E.g., a mobile phone) can be formed so as to conform to the design, so that there is an effect that the object to be installed can be provided with an ideal design.

According to the present invention, the light guide layer and the protective layer are
Since they are formed by color molding, they can be easily and closely adhered to each other with high accuracy, and furthermore, there is an effect that cost reduction by mass production can be realized.

According to the present invention, since the protective layer is provided on the light guide layer by printing or painting, the thin protective layer can be easily and precisely adhered and laminated on the light guide layer. This has the effect of realizing cost reduction.

According to the present invention, a light source for supplying a light beam to be incident on the light guide layer is mounted on the substrate, and light introducing means for introducing the light beam of the light source into the light guide layer is provided on an end face of the light guide layer. This eliminates the need for wiring from the substrate, which was required when arranging a light source on the end face of the light guide layer. This simplifies the structure of the display device and prevents failure due to disconnection and the like. There is.

According to the present invention, the light diffusing shape portion is formed by projecting a plurality of inclined steps in the thickness direction of the light guide layer. Since the light is inclined so as to bend toward the liquid crystal panel, the light reflected from the liquid crystal panel is in a direction almost parallel to the normal line of the front light illuminating plate. There are effects that can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a light guide layer having convex protrusions.

FIG. 3 is a sectional view showing a display device according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a display device according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a use state of a display device according to a fourth embodiment of the present invention.

FIG. 6 is an enlarged sectional view showing an inclined step portion of the light guide layer when external light can be effectively used.

FIG. 7 is an enlarged sectional view showing an inclined step portion of the light guide layer when external light cannot be used effectively.

FIG. 8 is an enlarged sectional view showing another inclined step portion of the light guide layer when external light can be effectively used.

FIG. 9 is an enlarged sectional view showing an inclined step portion of the light guide layer when external light cannot be used effectively.

FIG. 10 is an enlarged sectional view showing a protective layer coated on a light guide layer.

FIGS. 11A and 11B are a plan view and a cross-sectional view taken along line AA, respectively, of a mobile phone having a conventional display device.

FIG. 12 is a cross-sectional view illustrating a conventional display device.

[Explanation of symbols]

1 reflective liquid crystal panel, 2 front light illumination board, 3
Light source, 4,14 light beam, 5 convex rib (light diffusion shape part), 6 light guide layer, 7, 7a, 7b protective layer, 8 convex protrusion (light diffusion shape part), 9 substrate, 10 light guide (light Introducing means), 11 inclined stepped part, 12 person who sees liquid crystal display, 13
Outside light.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomohiro Sasakawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Mitsuo Inoue 2-3-2 Marunouchi 3-chome, Chiyoda-ku, Tokyo F-term (reference) in Ryo Denki Co., Ltd.

Claims (8)

[Claims] 1. A display device comprising a liquid crystal panel and a front light illuminating plate disposed on a front side of the liquid crystal panel and illuminating a front surface of the liquid crystal panel, wherein the front light illuminating plate is on a rear side. A transparent plate-shaped light-guiding layer having a light-diffusing shape part for dispersing an introduced light beam and irradiating the liquid-crystal panel, and a material for the light-guiding layer. And a protective layer made of a transparent material having a lower refractive index than the light guide layer and provided in close contact with substantially the entire front surface of the light guide layer. 2. A board on which various electronic components constituting a portable information terminal are mounted, a liquid crystal panel provided on the board and constituting a display section of the portable information terminal, and a front side of the liquid crystal panel. And a front light illuminating plate provided to illuminate the front surface of the liquid crystal panel, wherein the front light illuminating plate is disposed with the back side facing the front surface of the liquid crystal panel, and A transparent plate-shaped light-guiding layer having a light-diffusing shape part for diffusing the light beam to be irradiated to the liquid crystal panel, and a transparent material having a lower refractive index than the material of the light-guiding layer. A portable information device, comprising: a protective layer provided in close contact with substantially the entire front surface of the optical layer. 3. The portable information device according to claim 2, wherein the surface of the protective layer has an arbitrary curved shape. 4. The light guide layer and the protective layer are made of a resin material,
2. The display device according to claim 1, wherein the display device is integrally formed by two-color molding. 5. The display device according to claim 1, wherein the protective layer is formed on the front surface of the light guide layer by printing or painting. 6. A light source for emitting a light beam introduced into the light guide layer is mounted on the substrate, and a light beam emitted from the light source is applied to an end surface of the light guide layer to the light guide layer. 3. The portable information device according to claim 2, further comprising a light introducing means for introducing light. 7. The light diffusing shape portion is formed by projecting a plurality of inclined steps in the thickness direction of the light guide layer, and when the liquid crystal panel performs a display operation, the protective layer and the light guide layer are formed from above. 2. The display device according to claim 1, wherein the inclination of the inclined step is formed so that extraneous light incident through the liquid crystal panel is bent toward the liquid crystal panel. 3. 8. The light diffusion shape portion is formed by projecting a plurality of inclined steps in the thickness direction of the light guide layer. When the liquid crystal panel is operated for display, the protection layer and the light guide layer are formed from above. 3. The portable information device according to claim 2, wherein the inclination of the inclined step is formed so that extraneous light incident through the liquid crystal panel is bent toward the liquid crystal panel.