JP2000162594A - Front light integrated type transparent touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front light integrated type touch panel sufficiently irradiating a beam on a reflection type liquid crystal display without lowering transmissivity. SOLUTION: The transparent touch panel 13 provided with an upper part electrode plate 9 forming an upper part electrode on a lower surface of a film like insulation substrate and a lower part electrode plate 11 forming a lower part electrode on the upper surface of the planar or film like insulation substrate having a minute rugged part 8 on the upper surface, and oppositely arranging the upper part electrode plate 9 and the lower part electrode plate 11 between the electrodes through an air layer is used, and a light transmission plate 3 is stuck to the rear of the transparent touch panel 13 each other through an adhesive layer 12 or a repeelable sheet, and by arranging a light source 4 on the end surface of the light transmission plate 3, the transparent touch panel 13 is integrated with the front light 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cordless telephone, a portable telephone, a calculator, a notebook computer, a PDA (personal digital assistant), a digital camera,
The present invention relates to a front light-integrated touch panel used in a reflection type liquid crystal display such as a video camera and a commercial communication device, and a portable electronic device including a touch panel.

[0002]

2. Description of the Related Art Heretofore, small and lightweight portable electronic devices having a liquid crystal display section 7 have been developed and commercialized. The transmissive liquid crystal display used for the liquid crystal display unit 7 requires a backlight, and the portable electronic device 1 uses a battery such as a dry battery or a rechargeable battery as a power source. However, notebook computers, PDAs, digital cameras, etc.
Since a color display is required and a backlight using a high-brightness cold-cathode tube as a light source needs to be used, the power consumption of the backlight increases and the driving time of the battery is significantly impaired.

[0003] In order to reduce power consumption in portable electronic devices, use of a reflective liquid crystal display which does not require a backlight has been studied and commercialized. 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.

However, in order to use a reflective liquid crystal display in an environment where sufficient external light cannot be obtained, such as indoors or at night, it is necessary to illuminate the reflective liquid crystal display from the front side. Therefore, a method has been proposed in which a flat illumination (front light) is arranged in front of the reflection type liquid crystal display to share the ambient light and the front light (for example, S).
ID, 95 digest, 375 pages, CYTai, H. Zou, P.
K.Tai). The front light is such that a light source such as a cold cathode ray tube is provided on an end surface of a light guide plate made of a transparent resin or the like, and fine irregularities 8 such as prisms are formed on the front surface of the light guide plate (see FIG. 4). Light rays taken in from the end face of the light guide plate are guided to the back while being totally reflected in the light guide plate, and a part thereof is reflected by the fine unevenness 8 at an angle at which light is easily emitted to the reflective liquid crystal display side of the light guide plate, Light is emitted from the light guide plate to irradiate the reflective liquid crystal display.

Conventionally, portable electronic devices often have an input function from a liquid crystal display surface by disposing a transparent touch panel in front of a transmissive liquid crystal display. The transparent touch panel has an upper electrode plate 9 in which an upper electrode made of a transparent conductive film is formed on the lower surface of a film-shaped insulating substrate, and a lower electrode made of a transparent conductive film formed on the upper surface of the plate-shaped or film-shaped insulating substrate. And a lower electrode plate 11 having a structure in which the upper electrode plate 9 and the lower electrode plate 11 are opposed to each other via an air layer between the electrodes, and a part of the panel surface is pressed from the input surface side. By doing so, the two electrodes are brought into contact to be electrically connected and input. With respect to this touch panel, it has been proposed to bond the transmissive liquid crystal display with an adhesive layer or a removable sheet (for example, Japanese Patent Application Laid-Open No. 61-131).
314). This is because if an air layer exists even slightly between the transparent touch panel and the transmissive liquid crystal display, the transmittance decreases due to surface reflection at the interface with the air layer.

[0006]

However, the touch panel having the above configuration cannot be attached to a reflective liquid crystal display using the front light having the above configuration as an illumination source. This is because the fine irregularities 8 of the light guide plate of the front light cause a part of the light rays taken in from the end face of the light guide plate to be reflected by the interface with the air layer and output to the reflective liquid crystal display side. This is because if the air layer disappears due to the attachment of the touch panel to the front surface of the light plate, the fine unevenness 8 cannot emit light to the reflective liquid crystal display side (see FIG. 5).

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a front light integrated touch panel capable of sufficiently irradiating a reflective liquid crystal display without lowering the transmittance, in order to solve the above problems. Is to do.

[0008]

In order to achieve the above object, a front light integrated touch panel according to the present invention comprises an upper electrode plate having an upper electrode formed on a lower surface of a film-shaped insulating substrate; A lower electrode plate on which a lower electrode is formed on the upper surface of a plate-shaped or film-shaped insulating substrate having a portion, wherein the upper electrode plate and the lower electrode plate are arranged to face each other via an air layer between the electrodes. Using a touch panel, a light guide plate was attached to the back surface of the transparent touch panel via an adhesive layer or a re-peelable sheet, and a light source was arranged on an end surface of the light guide plate to integrate the transparent touch panel and the front light.

In the configuration of the front light integrated touch panel, the concave portion of the fine uneven portion is constituted by a large number of fine depressions formed on the entire upper surface of the insulating substrate.

[0010] Further, the recess is configured such that the area ratio at a position away from the light source is larger than the area ratio near the light source.

In the above-mentioned structure of the front light-integrated touch panel, the film-like insulating substrate having fine irregularities is formed by a large number of transparent fine beads kneaded before forming the film-like insulating substrate. The structure was such that fine projections were formed.

In the above-mentioned structure of the front light-integrated touch panel, the projections of the fine irregularities are formed as a coating by coating or printing an ink containing transparent fine beads. .

Further, the coating is formed in a dot gradation pattern in which the area ratio at a position distant from the light source is larger than the area ratio near the light source.

[0014]

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

FIG. 1 is a sectional view showing an embodiment of a portable electronic device incorporating a front light integrated touch panel of the present invention, and FIG. 2 is a sectional view of a portable electronic device incorporating a front light integrated touch panel 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 of the present invention, and FIG. 6 is a view for explaining the front light integrated touch panel of the present invention. It is. In the figure, 1 is a portable electronic device, 2 is a front light, 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, 8 is a fine uneven portion, 9 is An upper electrode plate, 10 is a peripheral adhesive layer, 11 is a lower electrode plate, 12 is an adhesive layer, and 13 is a transparent touch panel.

The front light integrated touch panel according to the present invention comprises a front light 2 having a light guide plate 3 and a light source 4.
Of a light guide plate and a transparent touch panel 13 through an adhesive layer 12 or a re-peelable sheet, and a cordless phone, a mobile phone, a calculator, a sub-notebook personal computer,
The present invention is applied to a portable electronic device 1 having a reflective liquid crystal display, such as a PDA (Personal Digital Assistant), a digital camera, a video camera, and a commercial communication device (see FIG. 1). For example, the portable electronic device 1 shown in FIG. 2 realizes an input function by the transparent touch panel 13 which is a pen input device installed at the top of the display unit. Further, the portable electronic device 1 shown in FIG. 3 has a keyboard as an input device, and also has a transparent touch panel 13 as an input device on a display surface.

The transparent touch panel 13 of the present invention has an upper electrode plate 9 in which an upper electrode made of a transparent conductive film is formed on the lower surface of a film-like insulating substrate, and a transparent conductive film on the upper surface of the plate-like or film-like insulating substrate. A lower electrode plate 11 on which a lower electrode made of a film is formed, wherein the upper electrode plate 9 and the lower electrode plate 11 are arranged to face each other via an air layer between the electrodes, and the panel surface is arranged from the input surface side. Is used in which both electrodes are brought into contact by pressing a part of the input to input. Note that only a transparent resin is used as the material of the film-shaped insulating substrate, but glass can be used as the material of the plate-shaped insulating substrate in addition to the transparent resin. The gap between the electrodes is formed by a spacer, and the upper electrode plate 9
The peripheral portion of the lower electrode plate 11 is adhered by a peripheral adhesive layer 10 such as a double-sided tape.

When a film-shaped insulating substrate is used for the lower electrode plate 11, an acrylic resin or polycarbonate is usually provided below the lower electrode plate 11 to provide rigidity to the transparent touch panel 13 itself. The structure is such that a transparent resin plate made of a transparent resin such as a resin is bonded. However, when the light guide plate 3 of the front light 2 is bonded to the transparent touch panel 13 as in the present invention, a support may be used in combination with the light guide plate 3 as shown in FIG. 6, and the support may be omitted.

The reason why the transparent touch panel 13 and the light guide plate 3 are bonded to each other via the adhesive layer 12 or the removable sheet is to eliminate an air layer existing between the transparent touch panel 13 and the light guide plate 3. Since there is a large difference between the refractive index of air (1.0) and the refractive index of glass or transparent resin (1.4 to 1.7), if an air layer exists between the lower electrode plate 11 and the light guide plate 3, the transmittance will be higher. Becomes lower. Therefore, the light guide plate 3 and the transparent touch panel 13 are bonded together with the adhesive layer 12 or the re-peelable sheet, and the transmittance is improved by omitting the air layer between them. The pressure-sensitive adhesive layer 12 is formed by applying a general transparent pressure-sensitive adhesive. Examples of the adhesive include acrylic resins such as acrylate copolymers, urethane resins, silicone resins, and rubber resins. The removable sheet is formed by forming a transparent polymer adhesive into a gel sheet. Examples of the polymer adhesive include urethane, acrylic, and natural polymer materials.

In the reflection type liquid crystal display 5, external light passes through the light guide plate 3 and the reflection type liquid crystal display 5 from the uppermost transparent touch panel 13 side, is reflected by the reflection plate 6 arranged on the back surface, and is again reflected by the reflection type liquid crystal display. Display 5,
The light passes through the light guide plate 3 and the transparent touch panel 13 and is emitted.
As described above, since the path of the external light passes twice through each component of the display unit, the overall transmittance is considerably lower than that in the case of using a transmissive liquid crystal display. Therefore, it is important to use the reflective liquid crystal display 5 to eliminate the air layer between the light guide plate 3 and the transparent touch panel 13 and improve the transmittance. If the support is omitted as described above in addition to the air layer, the transmittance can be further improved.

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. Light guide plate 3
As the material of the transparency, acrylonitrile-styrene copolymer resin excellent in light guide, polymethyl methacrylate resin, cellulose acetobutyrate resin, cellulose propionate resin, polymethylpentene resin, polycarbonate resin, polystyrene resin, A polyester resin, glass, or the like can be used.

The thickness of the light guide plate 3 is 0.3 to 2.0 mm.
According to the present invention, the transparent touch panel 13 is arranged on the reflective liquid crystal display 5 via the light guide plate 3. However, if the distance between the reflective liquid crystal display 5 and the input surface of the transparent touch panel 13 is too large, parallax occurs,
The display position and the input position are shifted. Therefore, the light guide plate 3
The distance between the reflective liquid crystal display 5 and the input surface of the transparent touch panel 13 is maintained at 3.0 mm or less by reducing the thickness of the transparent liquid crystal display as described above. If the thickness of the light guide plate 3 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 the distance exceeds 2.0 mm, in addition to the problem of parallax, the thickness of the lighting device is increased and the weight is increased, so that portability is lacking. As the shape of the light guide plate 3, in addition to a flat plate having a uniform thickness, a wedge shape or the like can be used.

The light guide plate 3 has no fine unevenness 8 formed on its upper surface, or even if the fine unevenness 8 is formed, the air layer disappears by bonding to the transparent touch panel 13. If available, it can be used. In any case, the light beam which is taken in from the end face portion and reaches the front surface of the light guide plate 3 is incident on the transparent touch panel 13 via the adhesive layer 12 or the removable sheet. Transparent touch panel 1
Most of the light rays incident on the light guide plate 3 are totally reflected on the surface of the lower electrode plate 11, that is, at the interface between the lower electrode and the air layer. Is sent to the end face opposite to the light-incident end face. A part of the light beam incident on the transparent touch panel 13 is generated by the lower electrode formed on the insulating substrate because the insulating substrate of the lower electrode plate 11 according to the present invention has the fine unevenness 8 on the upper surface. Since the interface with the air layer also has a fine uneven shape, the light is reflected not at total reflection but at an angle at which light is easily emitted toward the reflective liquid crystal display side (FIG. 6).
reference). By arranging such a front light-integrated touch panel on the reflective liquid crystal display 5, it is possible to sufficiently irradiate the reflective liquid crystal display 5.

The concave portion of the fine uneven portion 8 can be formed of a large number of fine depressions formed on the entire upper surface of the insulating substrate of the lower electrode plate 11. The fine dent is formed in an arbitrary shape that can reflect light at an angle at which light can easily be emitted toward the reflective liquid crystal display, for example, a mortar shape. Examples of the method for forming fine depressions include a method in which the surface is processed by applying heat and pressure with an uneven roll during or after molding of an insulating substrate, and a method in which the insulating substrate is a resin plate molded by a mold. There is a method in which a shape corresponding to the depression is provided on the cavity surface formed by the shaping sheet so as to be formed at the time of molding the insulating substrate. The depression has a diameter of 5 to 40 μm in order to have sufficient light transmittance when using external light and not to attenuate the visibility of the liquid crystal display unit 7.
It is preferred that

Further, it is preferable that the fine dents have a larger area ratio at a position away from the light source 4 than an area ratio near the light source 4. To change the area ratio of fine depressions,
The size of the depression or the pitch is changed depending on the distance from the light source 4. By doing so, it is possible to control the light emission balance of the fine irregularities 8, and it is possible to uniformly illuminate the reflective liquid crystal display 5.

The film-shaped insulating substrate having the fine irregularities 8 has a large number of fine projections formed by the presence of transparent fine beads kneaded before forming the film-shaped insulating substrate. can do. For the beads, a resin similar to the material of the insulating substrate or having a small difference in refractive index is used in order to maintain the transmittance of the insulating substrate itself to some extent. Each bead present on the film surface may be completely covered with the resin constituting the film, or may be partially exposed without being covered with the resin constituting the film. The beads preferably have a diameter of 5 to 40 μm in order to have sufficient light transmittance when using external light and not to attenuate the visibility of the liquid crystal display unit 7.

The projections of the fine irregularities 8 can be formed as a film by coating or printing an ink containing transparent fine beads. The beads are made of resin or glass which is similar to the material of the insulating substrate or has a small difference in refractive index in order to maintain the transmittance of the insulating substrate itself to some extent. Each bead present on the surface of the film may be completely covered with the film, or may be partially exposed without being covered with the film. The beads are
It has sufficient light transmittance when using external light, and has a liquid crystal display 7
5-40μ in diameter to avoid attenuating the visibility of
m is preferable.

The coating of the ink containing the transparent beads is preferably formed in a dot gradation pattern in which the area ratio at a position away from the light source 4 is larger than the area ratio near the light source 4. To change the area ratio of the coating, the size of the dot is changed or the pitch is changed depending on the distance from the light source 4. By doing so, it is possible to control the light emission balance of the fine irregularities 8, and it is possible to uniformly illuminate the reflective liquid crystal display 5. In order to form a gradation pattern, a printing method such as a gravure printing method or a screen printing method may be used. The shape of the dot is not particularly limited, and may be an arbitrary shape such as a circle or a polygon.

The light source 4 is arranged on an end face of the light guide plate 3. The light source 4 is arranged on at least one side of the light guide plate 3. Light source 4
For example, a cold cathode tube, an LED, or the like may be used. In the case of a cathode ray tube, a straight tube, an L-shape over two adjacent sides, and a U-shape over three adjacent sides can be used.

In order to efficiently collect the light emitted from the light source 4 on the light incident end face 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 resin such as polyester mixed with a light-diffusing substance such as TiO2 ↓, BaSO4 ↓, SiO4 ↓, or a light-diffusing reflective plate 6 provided with a light-diffusing property by foaming a resin such as polyester, A conductive film may be used.

As described above, the lower electrode plate 11 of the transparent touch panel 13 has the lower electrode formed on the upper surface of the plate-shaped or film-shaped insulating substrate having the fine unevenness 8 on the upper surface. Since the light is reflected at an angle where light is easily emitted toward the reflective liquid crystal display at the interface between the light guide plate 3 and the air layer, the light guide plate 3 of the front light 2 and the transparent touch panel 13 are bonded together with the adhesive layer 12 or the removable sheet. In this case, the reflection type liquid crystal display 5 can be sufficiently irradiated.

[0032]

The front light-integrated touch panel of the present invention has the above-described configuration and operation, and has the following effects.

That is, since the back surface of the transparent touch panel is bonded via the transparent light guide plate, the air layer between the lower electrode plate and the light guide plate can be eliminated, and the transmission by surface reflection at the interface with the air layer can be eliminated. The rate does not decrease.
In addition, since the lower electrode plate has the lower electrode formed on the upper surface of the insulating substrate having fine irregularities on the upper surface,
Even if the transparent light guide plate is not in contact with the air layer on the front surface, the reflection type liquid crystal display can be sufficiently irradiated by reflection at the interface between the electrode surface of the lower electrode plate and the air layer.

[Brief description of the drawings]

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

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

FIG. 4 is a cross-sectional view showing one embodiment of a configuration of a conventional front light.

FIG. 5 is a diagram illustrating a case where a touch panel is attached to a conventional front light.

FIG. 6 is a diagram illustrating a front light integrated touch panel according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable electronic device 2 Front light 3 Light guide plate 4 Light source 5 Reflection type liquid crystal display 6 Reflection plate 7 Liquid crystal display part 8 Fine unevenness 9 Upper electrode plate 10 Peripheral adhesive layer 11 Lower electrode plate 12 Adhesive layer 13 Transparent touch panel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H089 QA16 TA06 TA17 TA18 TA20 UA09 2H091 FA14Z FA23Z FA41Z FB02 FC02 FC12 GA17 LA16 MA10 5G006 FB14 FB17 JA01 JB03 JB05 JB07 JF23 JF27 5G023 AA12 CA19 CA30

Claims (6)

[Claims] An upper electrode plate having an upper electrode formed on the lower surface of a film-shaped insulating substrate, and a lower electrode having a lower electrode formed on the upper surface of a plate-shaped or film-shaped insulating substrate having fine irregularities on the upper surface. Using a transparent touch panel in which an upper electrode plate and a lower electrode plate are arranged between the electrodes with an air layer interposed therebetween, and a light guide plate on the rear surface of the transparent touch panel via an adhesive layer or a re-peelable sheet. A transparent touch panel integrated with a front light, wherein the transparent touch panel and the front light are integrated by bonding and arranging a light source on an end face of the light guide plate. 2. The front light-integrated transparent touch panel according to claim 1, wherein the concave portion of the fine concave / convex portion comprises a large number of fine concave portions formed on the entire upper surface of the insulating substrate. 3. The front light-integrated transparent touch panel according to claim 2, wherein the fine dent has a larger area ratio at a position apart from the light source than an area ratio near the light source. 4. A film-like insulating substrate having fine irregularities, in which a large number of fine protrusions are formed due to the presence of transparent fine beads kneaded before forming the film-like insulating substrate. The transparent touch panel integrated with a front light according to claim 1. 5. The front light-integrated transparent touch panel according to claim 1, wherein the projections of the fine irregularities are formed as a film by coating or printing an ink containing transparent fine beads. 6. The front light-integrated transparent touch panel according to claim 5, wherein the coating is formed with a dot gradation pattern in which the area ratio at a position away from the light source is larger than the area ratio near the light source.