JP2002270018A - Front light and front light integration type touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front light and a front light integration type touch panel capable of effectively emitting light to the lower side of the front light. SOLUTION: This front light 15 comprises a transparent light guide plate 3 and a light source 4 disposed on a light entering surface 16 of an end face thereof. The upper surface of the guide plate 3 is entirely flat, and the lower surface of the guide plate 3 alternately has inclined surfaces 18 for internally reflecting the light entered from the entering surface 16 downward and horizontal surfaces 17 for emitting the light reflected by the inclined surfaces 18 outward, and the angle between the horizontal surfaces 17 and the inclined surfaces 18 is 90 deg. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a front light and a front light integrated touch panel device. The front light and the front light-integrated touch panel device according to the present invention include a cordless telephone, a mobile phone, a calculator, a sub-notebook personal computer, a PDA (personal
Digital assistants), digital cameras, video cameras, commercial communication devices, and other portable electronic devices having a reflective liquid crystal display are particularly suitable.

[0002]

2. Description of the Related Art Conventionally, small and light portable electronic devices having a liquid crystal display have been developed and commercialized. In portable electronic devices, a reflective liquid crystal display is sometimes used to reduce power consumption. The reflection type liquid crystal display is suitable for a portable electronic device in addition to the point that power consumption is small by not using a backlight, and also that it is excellent in visibility under external light when used outdoors.

In order to use a reflective liquid crystal display in an environment such as indoors or at night where sufficient external light cannot be obtained, it is necessary to illuminate the reflective liquid crystal display from the front side. A front light, which is a lighting device in which a light source is positioned above the light source, is used.

As a front light, a light guide plate is arranged on a display surface of a reflection type liquid crystal display in parallel with the reflection type liquid crystal display, and light from a light source such as a cold cathode tube or an LED is transmitted from an end surface of the light guide plate. In general, the light is radiated onto the surface of a reflection-type liquid crystal display. One surface of the light guide plate has a light diffusion function for emitting light incident from the end surface to the liquid crystal display surface. As the light diffusion function, there is a function of forming a large number of fine prisms or microlenses on the upper surface of the light guide plate, or performing a fine matting process to diffuse light.

However, when a light diffusing function is provided on the upper surface of the light guide plate, if a transparent touch panel is laminated on the upper surface of the light guide plate, the light diffusion function surface of the light guide plate cannot contact the air layer. Prisms and microlenses with light diffusion function,
Since the matted part guides the incident light from the end face downward by reflection at the interface with the air layer, when laminating the light guide plate and the transparent touch panel without passing through the air layer,
The light diffusion function surface can hardly exhibit its effect.

In addition, a strong load is applied to the upper surface of the light guide plate by an input pen or the like at the time of input to the touch panel, and the fine shape formed on the upper surface of the light guide plate is easily broken by this load. This is an inappropriate configuration for a touch panel.

Therefore, a front light has been proposed in which a large number of fine projections are formed on the lower surface of the light guide plate and light is emitted from the side surfaces of the projections.

[0008]

However, in the above-mentioned front light, the light emitted from the side surface of the projection formed on the lower surface of the light guide plate is directed to the reflection type liquid crystal display surface disposed below the front light. There is a problem that the light travels in a direction close to parallel and hardly enters the reflection type liquid crystal display.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a front light and a front light integrated touch panel device capable of solving the above-mentioned problems and effectively emitting light below the front light. I do.

[0010]

SUMMARY OF THE INVENTION A front light and a front light-integrated touch panel device according to the present invention are configured as follows to achieve the above object.

That is, the front light according to the present invention is a front light comprising a transparent light guide plate and a light source disposed on a light incident surface which is an end face thereof, wherein the upper surface of the light guide plate is entirely flat. The lower surface of the light guide plate has, alternately, an inclined surface for internally reflecting light incident from the light incident surface in a downward direction and a horizontal surface for emitting light reflected on the inclined surface to the outside, and the angle between the horizontal surface and the inclined surface is It was configured to be less than 90 °.

Further, in the above invention, the angle between the light incident surface on which the light source of the light guide plate is disposed and the upper surface of the light guide plate is 90 °.
And the angle α between the horizontal plane and the inclined plane on the lower surface of the light guide plate.
Is (90 ° −β) /, where β is the critical angle of the light guide plate.
It may be configured to satisfy the relationship of 2 <α <90 ° −β.

Further, in the above invention, a low reflection layer having a lower refractive index than the light guide plate and a higher refractive index than the air layer may be formed on the lower surface of the light guide plate.

Further, in the above invention, the light guide plate may have a thickness of 0.3 to 2.0 mm.

Further, in the above invention, the horizontal plane on the lower surface of the light guide plate has an angle of 1 to 5 ° with respect to the upper surface of the light guide plate so that the thickness of the light guide plate increases as the distance from the light incident surface increases. It may be configured as follows.

According to a further aspect of the present invention, there is provided a touch panel device integrated with a front light, wherein a reflection type liquid crystal display, the front light according to any one of claims 1 to 5, and a transparent touch panel are sequentially laminated. The lower part of the transparent touch panel was laminated via a transparent resin layer.

[0017]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of a front light integrated touch panel device of the present invention. FIG.
1 is a perspective view showing an embodiment of a portable electronic device incorporating a front light integrated touch panel device of the present invention. FIG. 3 is a perspective view showing another embodiment of a portable electronic device incorporating the front light integrated touch panel device of the present invention. FIG. 4 is a sectional view showing an embodiment of the front light integrated touch panel device of the present invention.
FIG. 5 is a sectional view showing a shape of a light guide plate used for the front light of the present invention. 7 to 10 are cross-sectional views showing the shape of the light guide plate used for the front light of the present invention. FIG. 11 is a sectional view showing another embodiment of the front light integrated touch panel device of the present invention. In the figure, 1 is a portable electronic device, 2 is a front light integrated touch panel device, 3 is a light guide plate, 4 is a light source, 5 is a reflection type liquid crystal display, 6 is a reflection plate, 7 is a liquid crystal display unit, and 8 is a support. , 9 is an upper electrode plate, 10 is an insulating member, 11 is a lower electrode plate, 12 is a transparent resin layer, 13 is a low reflection layer, 14 is a transparent touch panel, 15 is a front light, 16 is a light incident surface,
17 is a horizontal plane, 18 is an inclined plane, and 19 is incident light.

The front light 15 of the present invention is a front light 15 comprising a transparent light guide plate 3 and a light source 4 disposed on a light incident surface 16 which is an end face thereof. The lower surface of the light guide plate 3 has alternately inclined surfaces 18 for internally reflecting light incident from the light incident surface 16 downward and horizontal surfaces 17 for emitting light reflected by the inclined surfaces 18 to the outside. , The angle between the horizontal surface 17 and the inclined surface 18 is less than 90 °. (See FIG. 1).

Front light integrated touch panel device 2
Is applied to the portable electronic device 1 including the reflective liquid crystal display 5 and the transparent touch panel 14, such as a cordless telephone, a mobile phone, a calculator, a sub-notebook personal computer, a PDA, a digital camera, a video camera, and a commercial communication device. .

FIG. 2 shows an example of a portable electronic device incorporating the front light integrated type touch panel device of the present invention. The portable electronic device 1 realizes an input function by a transparent touch panel 14 which is a pen input device installed at the top of the liquid crystal display unit 7. Portable electronic device 1 shown in FIG.
Has a keyboard as an input device, and the liquid crystal display unit 7 also has a transparent touch panel 14 as an input device.

Front light integrated touch panel device 2
Is a reflective liquid crystal display 5, a front light 15 including the light guide plate 3 and the light source 4, and a transparent touch panel 14.
May be combined at least (see FIG. 1).

As the transparent touch panel 14, what is called a resistive film type may be used. The resistive film method includes a lower electrode plate 11 made of an insulating substrate such as a glass plate provided with a lower electrode made of a transparent conductive film and dot-shaped spacers on the surface, and a film provided with an upper electrode made of a transparent conductive film. The transparent touch panel 14 has a structure in which an upper electrode plate 9 made of an insulating substrate is laminated and a part of the panel surface is pressed from the input surface side so that both electrodes are brought into contact to be electrically connected and input. is there. Further, as the transparent touch panel 14, a touch panel of a capacitance type, an optical type, or the like may be used.

As the lower electrode plate 11 of the transparent touch panel 14, a film with electrodes similar to the upper electrode plate 9 may be used. This method is called a film type, and the weight can be reduced by using a film instead of glass as the lower electrode plate 11.
Has the advantage that it is not easily broken. The film-type transparent touch panel 14 is generally formed by laminating a transparent resin plate made of a transparent resin such as an acrylic resin or a polycarbonate resin as the support 8 below the lower electrode plate 11 in order to impart rigidity to the transparent touch panel 14 itself. Used.

Transparent touch panel 14 and front light 1
5 is laminated via a transparent resin layer 12 made of a transparent adhesive or a transparent gel (see FIG. 1). With this configuration, the air layer existing between the transparent touch panel 14 and the front light 15 can be omitted. The refractive index of air (1.0) and the refractive index of glass or transparent resin (1.
4 to 1.7), the transmittance is reduced when an air layer exists between the lower electrode plate 11 and the light guide plate 3. Therefore, the transmittance can be improved by laminating the light guide plate 3 and the transparent touch panel 14 with the transparent resin layer 12 so as not to pass through the air layer.
As the transparent adhesive layer, it is preferable to use a material having a refractive index similar to that of the light guide plate 3 or a refractive index between the light guide plate 3 and the lower electrode substrate of the transparent touch panel 14.

When a film-type transparent touch panel 14 is used, the support 8 may be omitted and the front light 15 may be laminated via the transparent resin layer 12 (see FIG. 4). With this configuration, the support 8 of the lower electrode plate 11 of the transparent touch panel 14 is used in combination with the light guide plate 3 of the front light 15, and the air layer between the support 8 and the light guide plate 3 is removed. , The transmittance can be improved. Since the film-type transparent touch panel 14 has a flexible structure, the transparent touch panel 14 and the light guide plate 3 can be easily laminated.

In the reflective liquid crystal display 5, external light passes through the light guide plate 3 of the front light 15 and the reflective liquid crystal display 5 from the uppermost transparent touch panel 14 side, is reflected by the reflective plate 6, and is again reflected by the reflective liquid crystal display. 5. The light passes through the light guide plate 3 and the transparent touch panel 14 and is emitted. Since the path of the external light passes through each component of the front light-integrated touch panel device 2 twice, the transmittance is considerably low. Therefore, omitting the two layers of the air layer and the support 8 contributes to an improvement in transmittance. In particular, the air layer
Since the difference in the refractive index is large as compared with the light guide plate 3 and the transparent resin layer 12, the loss due to the reflection at the interface between the air layer and other layers is large. Therefore, if the air layer can be omitted, the transmittance can be greatly improved.

Next, the front light 15 will be described. The front light 15 includes at least the transparent light guide plate 3 and the light source 4 disposed on an end face thereof.

Since the light guide plate 3 is disposed so as to be superimposed on the reflective liquid crystal display 5, it is required that the light guide plate 3 has sufficient light transmittance and does not hinder the visibility of the liquid crystal display.

The light guide plate 3 is preferably made of a transparent resin. As the transparent resin, acrylonitrile-styrene copolymer resin excellent in transparency and light guide property, cellulose acetobutyrate resin, cellulose propionate resin, polymethylpentene resin, polycarbonate resin, polystyrene resin, polyester resin and the like are used. be able to.

As for the shape of the light guide plate 3, the upper surface of the light guide plate 3 is entirely flat, and the lower surface of the light guide plate 3 is
Inclined surface 18 for internally reflecting light incident from 6 downward
And the horizontal surface 17 for emitting the light reflected by the inclined surface 18 to the outside are formed alternately, and the angle between the horizontal surface 17 and the inclined surface 18 is formed to be less than 90 ° (see FIG. 5).

With such a configuration, the light emitted from the light source 4 is incident on the light incident surface 16 which is the end side surface of the light guide plate 3.
From the light guide plate 3 and totally reflected by the inner surface of the light guide plate 3 according to Snell's law.
Is guided to the end face opposite to. Therefore, in order to emit light from the lower surface of the light guide plate 3, the light guide plate 3
A large number of horizontal planes 17 having a surface parallel or slightly inclined with the upper surface of the light guide plate 3 and a large number of inclined surfaces 18 having a surface which is sharply inclined with respect to the upper surface of the light guide plate 3 are provided alternately.

FIG. 5 is a sectional view showing a case where the angle α between the horizontal plane 17 and the inclined surface 18 (hereinafter referred to as an inclined angle) is an acute angle of less than 90 °. In this case, light traveling in the light guide plate 3 is reflected by the inclined surface 18 and emitted from the horizontal surface 17 on the lower surface. Since the emitted light can be set at an angle almost perpendicular to the liquid crystal display, the amount of light incident on the liquid crystal display can be increased.

Accordingly, the light emitted from the light source 4 enters the light guide plate 3 from the light incident portion of the light guide plate 3 and is internally reflected between the upper surface of the light guide plate 3 and the horizontal plane 17 on the lower surface of the light guide plate 3. And the light hitting the inclined surface 18 on the lower surface of the light guide plate 3 is reflected and guided to the horizontal surface 17 to the lower side of the light guide plate 3 toward the reflective liquid crystal display 5. Emit. The light emitted from the front light 15 passes through the liquid crystal layer, is reflected by the light reflection layer below the liquid crystal, passes through the liquid crystal layer again, passes through the light guide plate 3 and the touch panel, and goes out of the front light integrated touch panel device 2. Emit.

FIG. 6 shows the angle α between the horizontal plane 17 and the inclined plane 18.
Is a cross-sectional view when the angle is 90 °. In this case, light traveling in the light guide plate 3 is emitted from the vertical inclined surface 18. The emitted light enters the liquid crystal display at a shallow angle that is substantially parallel to the liquid crystal display. Therefore, it is difficult to sufficiently obtain the amount of light that enters the reflective liquid crystal display 5.

The optimum value of the inclination angle α varies depending on the angle distribution of the ray density of the incident light. The angle of the emitted light is also determined by the inclination angle. For example, when an acrylic plate having a refractive index of 1.49 is used as the light guide plate 3, the critical angle β with the air layer is about 42.2 °. Therefore, light incident in a direction perpendicular to the light incident surface 16 is
By designing the inclination angle α to be less than 47.8 ° (90 ° −42.2 °), the light is totally reflected by the inclined surface 18 and is all emitted downward (see FIG. 7). Therefore, a relationship of α <90 ° −β is established between the inclination angle α and the critical angle β.

On the other hand, when the inclination angle α is, for example, 20
When the angle is a relatively acute angle of about °, light incident in a direction perpendicular to the light incident surface 16 is reflected by the inclined surface 18 and travels to the horizontal plane 17. However, if the horizontal surface 17 is perpendicular to the light incident surface 16, the light is incident at an angle of 50 ° larger than the critical angle, so that the light is totally reflected by the horizontal surface 17 and returned to the inside of the light guide plate 3. (See FIG. 8).

Therefore, in order for light incident in a direction perpendicular to the light incident surface 16 to be reflected by the inclined surface 18 and emitted directly from the horizontal surface 17, the angle of the inclined surface 18 must be 23.
It is necessary to be 9 ° or more and less than 47.8. Therefore, the relationship α> (90 ° −β) / 2 holds. Note that at around 23.9 ° shown above, light emitted from the light guide plate 3 has a shallow angle almost parallel to the liquid crystal display surface, so that effective light is emitted to the reflective liquid crystal display 5. No (see FIG. 9).

As described above, the design of the inclined surface 18 depends on how the incident light 1 is increased in order to enhance the visibility of the liquid crystal display.
This is performed in consideration of various factors such as the material characteristics of the light guide plate 3 and the liquid crystal and the position of each component, in consideration of whether the light 9 is emitted to the liquid crystal display surface.

The angle of the horizontal plane 17 is preferably parallel to the upper surface of the light guide plate 3. However, this causes a large difference in the thickness of the light guide plate 3 between the light incident surface 16 side and the opposite light incident surface 16 side. For example, assuming that the distance in the incident direction of the light guide plate 3 is 60 mm, the height of the inclined surface 18 is 10 μm, and the pitch of each step is 300 μm, the light incident surface 16 side and the anti-light incident surface 16 side of the light guide plate 3 are thick. The difference in height is 2 mm. Then, the thickness of the light guide plate 3 becomes 2 mm or more. It is not preferable that the thickness of the light guide plate 3 is 2 mm or more for the front light 15 integrated type touch panel for the purpose of thinning. Also, if the thickness on the anti-light incident surface 16 side becomes too thin,
Molding becomes difficult. Further, even if the molding process can be performed, the strength may be insufficient. Therefore, an angle may be provided so that the upper surface of the light guide plate 3 and the horizontal plane 17 are non-parallel so that the thickness of the light guide plate 3 increases as the distance from the light entrance surface 16 increases. The angle is suitably in the range of 1 to 5 ° (see FIG. 10). With such a configuration, the thickness of the light guide plate 3 on the side opposite to the light entrance surface 16 can be easily formed and maintain the strength.

Although FIGS. 1 and 4 show an example in which the interval between the continuous horizontal plane 17 and the inclined plane 18 is equally distributed, the horizontal plane 17 is used to make the light emission more uniform.
The configuration may be such that the interval between the and the inclined surface 18 is different from each other.

The light source 4 is disposed on an end surface of the light guide plate 3 which is the light incident surface 16. The light source 4 is arranged on at least one side of the light guide plate 3. As the light source 4, a cold cathode tube, an LED, or the like may be used. When using an LED as the light source 4, a plurality of LEDs
Are preferably used in a line. Further, a rod-shaped light guide in which an LED is arranged on an end face can be used as a line light source.

In order to efficiently collect the light emitted from the light source 4 on the light incident surface 16 of the light guide plate 3, a reflector may be provided. As the reflector, a metal plate having a material that reflects light specularly on the surface, such as silver, aluminum, platinum, nickel, and chromium, is preferably used. In particular, a silver or aluminum surface coated with a vacuum deposition method or a sputtering method is preferable. In addition, a light diffusing material such as TiO ₂ , BaSO ₄ , SiO ₄ or the like mixed in a resin such as polyester, or a light diffusing reflector 6 having a light diffusing property obtained by foaming a resin such as polyester, A conductive film may be used.

In the front light-integrated touch panel device 2 of the present invention, the transparent touch panel 14 is disposed at the upper part and the reflective liquid crystal display 5 is disposed at the lower part. If the distance is too large, parallax occurs, and the display position and the input position are shifted. Accordingly, the thickness of the light guide plate 3 is a factor that increases the distance between the reflective liquid crystal display 5 and the transparent touch panel 14, and therefore, the thinner is preferable. And considering the luminous efficiency, the thickness of the light guide plate 3 is
Desirably, it is 0.3 to 2.0 mm. In particular, light source 4
When a cold cathode tube is used, the light incident surface 16 is about 1.0 mm even if the diameter of the cold cathode tube serving as the light source 4 is small.
A range of 1.0 to 2.0 mm is desirable. Further, when an LED is used as the light source 4, it is desirable to set the range of 0.3 to 1.0 mm. If it is less than 0.3 mm, it is difficult to process the light guide plate, and it is difficult to take in sufficient light from the end face. On the other hand, if it exceeds 2.0 mm, the thickness of the front light 15 becomes too large, and the parallax becomes too large. In addition, front light 15
The purpose of the device incorporating the is impaired.

The transmittance of the front light 15 can be improved by forming a low reflection layer 13 having a lower refractive index than the light guide plate 3 and a higher refractive index than the air layer on the lower surface of the light guide plate 3 (see FIG. 11). ).

To form the low reflection layer 13, there is a method of forming a low refractive film on the lower surface of the light guide plate 3. The low refraction film is
It is preferable to form a material having a low refractive index by directly treating the surface of the resin as the light guide plate 3. The low refraction film is made of an inorganic material such as MgF
₂ (refractive index: 1.38) or SiO2
₂ (refractive index: 1.46), and can be formed by a vacuum evaporation method or the like. Further, it can be formed by a plasma polymerization method or a coating method such as dip using a fluorine-based monomer which is an organic substance.

Further, a film having a refractive index lower than the refractive index of the light guide plate 3 is laminated on the lower surface of the light guide plate 3 using a transparent adhesive having a refractive index not less than the film and not more than the light guide plate 3. May form the low reflection layer 13.

Since the upper surface of the light guide plate 3 has an interface with the air layer, surface reflection causes a decrease in transmittance. Therefore, by forming the low reflection layer 13 on this surface, the reflectance at the interface can be reduced and the transmittance can be improved.

As described above, the light emitted from the light source 4 enters the light guide plate 3 from the light incident portion of the light guide plate 3, and the light between the upper surface of the light guide plate 3 and the horizontal surface 17 on the lower surface of the light guide plate 3. The internal reflection is repeated between the light guide plate 3 and the light guide plate 3, and the light hitting the inclined surface 18 on the lower surface of the light guide plate 3 is reflected and guided to the horizontal plane 17, and the reflective liquid crystal on the lower side of the light guide plate 3 is reflected. Light is emitted to the display 5 side. The light emitted from the front light 15 passes through the liquid crystal layer, is reflected by the light reflecting layer below the liquid crystal, passes through the liquid crystal layer again, passes through the light guide plate 3 and the touch panel, and passes through the front light integrated touch panel device 2.
Out of the device. Therefore, the liquid crystal display can be recognized even in an environment where sufficient external light cannot be obtained in a device using the reflective liquid crystal display 5.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An upper electrode film having a thickness of 150 μm on which an upper transparent electrode made of indium oxide and tin oxide is formed on the lower side, and a lower electrode film having a thickness of 100 μm on which a lower transparent electrode made of indium oxide and tin oxide are formed on the upper side. The side electrode film and a spacer made of a transparent resin (area occupancy of 0.1
%, A height of 3 μm), and a touch panel whose periphery is adhered to each other with a double-sided adhesive tape so as to face each other is prepared.

Under the touch panel, a light guide plate of a front light was bonded using a transparent adhesive having a thickness of 30 μm to form a front light integrated with a touch panel.

The light guide plate used was an acrylic resin having a refractive index of 1.49. 65m distance from the light entrance surface of the light guide plate to the light entrance surface
m, the thickness of the light guide plate is 1.0 mm on the light incident surface side, 0.5 mm on the opposite side of the light incident surface, the angle between the horizontal plane and the inclined surface on the lower surface of the light guide plate is 47.5 °, and the thickness of the light guide plate is The angle between the upper surface and the horizontal plane was 3 °. Further, a low reflection layer made of SiO ₂ was formed on the surface of the horizontal surface and the inclined surface on the lower surface of the light guide plate.

The front light-integrated touch panel device thus obtained can uniformly emit the light of the light source of the front light to the lower side of the front light, and has excellent visibility of the liquid crystal display. Was something.

[0054]

Since the present invention has the above-described structure, it has the following effects.

The front light according to the present invention is a front light comprising a transparent light guide plate and a light source disposed on a light incident surface which is an end face thereof, wherein the upper surface of the light guide plate is entirely flat. The lower surface has alternately inclined surfaces for internally reflecting light incident from the light incident surface in the downward direction and horizontal surfaces for emitting light reflected by the inclined surface to the outside, and the angle between the horizontal surface and the inclined surface is 90 °. Since it is configured to be less than the above, light can be effectively emitted to the lower side of the front light.

According to the present invention, there is provided a front light integrated touch panel device comprising: a reflection type liquid crystal display; a front light according to any one of claims 1 to 5; Since the lower part of the transparent touch panel is configured to be laminated with the transparent resin layer interposed therebetween, light can be effectively emitted to the lower side of the front light, and the liquid crystal display has excellent visibility. is there.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a front light-integrated touch panel device of the present invention.

FIG. 2 is a perspective view showing one embodiment of a portable electronic device incorporating the front light-integrated touch panel device of the present invention.

FIG. 3 is a perspective view showing another embodiment of a portable electronic device incorporating the front light integrated touch panel device of the present invention.

FIG. 4 is a sectional view showing an embodiment of the front light integrated touch panel device of the present invention.

FIG. 5 is a sectional view showing a shape of a light guide plate used for the front light according to the present invention.

FIG. 6 is a cross-sectional view showing a shape of a light guide plate used for a conventional front light.

FIG. 7 is a sectional view showing a shape of a light guide plate used for the front light of the present invention.

FIG. 8 is a sectional view showing a shape of a light guide plate used for the front light according to the present invention.

FIG. 9 is a sectional view showing a shape of a light guide plate used for the front light according to the present invention.

FIG. 10 is a sectional view showing a shape of a light guide plate used for the front light according to the present invention.

FIG. 11 is a cross-sectional view showing another embodiment of the front light integrated touch panel device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable electronic device 2 Front light integrated touch panel device 3 Light guide plate 4 Light source 5 Reflection type liquid crystal display 6 Reflection plate 7 Liquid crystal display part 8 Support body 9 Upper electrode plate 10 Insulation member 11 Lower electrode plate 12 Transparent resin layer 13 Low reflection Layer 14 Transparent touch panel 15 Front light 16 Light incident surface 17 Horizontal surface 18 Inclined surface 19 Incident light

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G09F 9/00 336 G09F 9/00 336B 5G435 H01H 36/00 H01H 36/00 L // F21Y 103: 00 F21Y 103: 00

Claims (6)

[Claims] 1. A front light comprising a transparent light guide plate and a light source disposed on a light incident surface which is an end face thereof, wherein the upper surface of the light guide plate is entirely flat and the lower surface of the light guide plate is light incident. Having an inclined surface for internally reflecting light incident from the surface in a downward direction and a horizontal surface for emitting light reflected by the inclined surface to the outside, wherein the angle between the horizontal surface and the inclined surface is less than 90 °. Features a front light. 2. An angle between a light incident surface on which a light source of the light guide plate is disposed and an upper surface of the light guide plate is 90 °, and an angle α between a horizontal plane and an inclined surface on a lower surface of the light guide plate is a critical angle of the light guide plate. 2. The front light according to claim 1, wherein, when the angle is β, the relationship (90 ° −β) / 2 <α <90 ° −β is satisfied. 3. 3. The front light according to claim 1, wherein a low reflection layer having a lower refractive index than the light guide plate and a higher refractive index than the air layer is formed on a lower surface of the light guide plate. 4. The front light according to claim 1, wherein the light guide plate has a thickness of 0.3 to 2.0 mm. 5. The light guide plate according to claim 1, wherein a horizontal plane on a lower surface of the light guide plate has an angle of 1 to 5 ° with respect to an upper surface of the light guide plate so that the thickness of the light guide plate increases as the distance from the light incident surface increases.
The front light according to any of the above. 6. A reflective liquid crystal display, and a reflective liquid crystal display.
5. The front light integrated touch panel device, wherein the front light described in any one of 5 and a transparent touch panel are sequentially laminated, and an upper part of the front light and a lower part of the transparent touch panel are laminated via a transparent resin layer. .