JP4010509B2 - Touch-input type LCD device - Google Patents

Description

  The present invention relates to a touch-input type liquid crystal display device that suppresses reflected light from an indoor fluorescent lamp or the like, or reflected light caused by outside light outdoors, and has high contrast and high visibility.

Conventionally, a touch input type liquid crystal display device includes a liquid crystal display 2 below the transparent touch panel 1, and the transparent touch panel 1 includes a movable side sheet 20 and a fixed side sheet 21 disposed via a space layer 7. In some cases, an upper polarizing plate 8 and a lower polarizing plate 9 are arranged on the upper and lower surfaces of the liquid crystal display 2 (see FIG. 4 ).

In addition, in order to increase the contrast, instead of arranging the upper polarizing plate 8 on the upper surface of the liquid crystal display 2, there is also one in which the upper polarizing plate 8 is arranged on the upper surface of the movable side sheet 20 of the transparent touch panel 1 (see FIG. 5 ). .

However, in the touch-input type liquid crystal display device having the above-described configuration, the mobile phone having the touch-input type liquid crystal display device is used in a room with a fluorescent lamp 504 as shown in FIG. 6 or outdoors as shown in FIG. When an input operation is performed with the pen 503 or 501 on the personal computer 502 or the portable terminal 500, the interface between the space layer of the transparent touch panel 1 of the liquid crystal display device and the fixed electrode portion provided on the upper surface of the fixed sheet and the transparent Since there is reflection of light at two places on the uppermost surface of the touch panel 1, the display screen is very difficult to see. This is because when light passes from a medium having a low refractive index to a medium having a high refractive index, the larger the difference in the refractive index, the more the light is reflected at the interface.

  In the case of the configuration in which the upper polarizing plate 8 is arranged on the upper surface of the movable side sheet 20 of the transparent touch panel 1, there is a method of preventing the reflected light by forming the upper surface of the upper polarizing plate 8 in a satin shape, but sufficiently suppressing the reflected light. I can't.

  Accordingly, an object of the present invention is to provide a touch-input type liquid crystal display device having low reflection, high contrast, and high visibility even in a room with a fluorescent lamp or the like and by solving the above problems. It is.

To achieve the above object, according to the present invention, in a touch input type liquid crystal display device having a liquid crystal display under the transparent touch panel, a phase delay of ¼ wavelength is given to incident light having a central wavelength in the visible region. And an upper optical phase difference film having a movable electrode portion on the lower surface, a transparent resin plate having optical isotropy on the upper surface, and a phase delay of ¼ wavelength with respect to the incident light having the central wavelength in the visible region An upper polarizing plate is disposed on the upper surface of the transparent touch panel in which a lower optical phase difference film having a fixed electrode portion is sequentially disposed through an isotropic film, and a lower layer is disposed on the lower surface of the liquid crystal display. A polarizing plate is disposed, and an angle formed by an optical axis of the upper optical retardation film and an absorption axis of the upper polarizing plate is about 45 °, and the lower optical retardation film is Of the linearly polarized light emitted from the liquid crystal display and the linearly polarized light desired to be emitted from the apparatus surface is about 45 °, and the optical axis of the upper optical retardation film and the lower optical position are The angle of the optical axis of the retardation film is about 90 °, and the angle between the linearly polarized light emitted from the liquid crystal display and the absorption axis of the upper polarizing plate is 90 °. The fixed electrode portion is formed directly on the optical isotropic film.

  Since the touch-input type liquid crystal display device according to the present invention is configured and operated as described above, the following effects can be obtained.

  That is, by arranging the angle formed by the absorption axis of the upper polarizing plate and the optical axis of the upper optical retardation film to be about 45 °, it becomes circularly polarized light or substantially circularly polarized light and enters the space layer of the transparent touch panel and is reflected. Since the circularly polarized light or substantially circularly polarized light passes through the upper optical retardation film again and becomes linearly polarized light perpendicular to the transmission axis of the upper polarizing plate, reflected light is suppressed. Here, the absorption axis of the upper polarizing plate 8 is an axis parallel to the stretching direction of the film material. The light passing through the upper polarizing plate 8 is polarized and exits from the upper polarizing plate 8 as linearly polarized light only in a direction orthogonal to the absorption axis. The axis orthogonal to the absorption axis is called the transmission axis. In order for this upper polarizing plate 8 to transmit linearly polarized light, the direction of the transmission axis must match. The linearly polarized light whose directions do not match cannot pass through the upper polarizing plate 8.

  In addition, the linearly polarized light emitted from the liquid crystal display should be emitted from the surface of the apparatus so that the optical axis of the lower optical retardation film is at an angle of about 90 ° with respect to the optical axis of the upper optical retardation film. By placing it between the transparent touch panel and the liquid crystal display so that it is at an angle of about 45 ° to the linearly polarized light, it suppresses the coloring of the display screen when viewed from the viewer side, and has high contrast and no color. A display screen is obtained. Of the linearly polarized light emitted from the liquid crystal display, the linearly polarized light that is desired to be emitted from the surface of the apparatus has a relationship of forming an angle of 90 ° with the absorption axis of the upper polarizing plate.

  By the above improvement, the liquid crystal display provided with the transparent touch panel according to the present invention can obtain a display screen with high contrast and very good visibility with little reflection even in a room with a fluorescent lamp or the like.

  Since the present invention is configured and operated as described above, the upper polarizing plate and the respective layers behind it suppress reflected light from indoor fluorescent lamps and reflected light caused by outside light outdoors, and have high contrast. Thus, a highly visible touch input type liquid crystal display device can be obtained.

  Hereinafter, a touch input type liquid crystal display device according to various embodiments of the present invention and a manufacturing method thereof will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view illustrating a resistive touch type liquid crystal display device (reflection type STN) according to the present invention.

In the figure, 1 is the above transparent touch panel, 2 is a liquid crystal display, 3 is a movable electrode part, 4 is an upper optical phase difference film, 5 is a fixed electrode part, 6 is a lower optical phase difference film, 7 is a space layer, 8 is An upper polarizing plate, 9 is a lower polarizing plate, 10 is a spacer, 12 is an optical isotropic film , 14 is an optical compensation phase difference plate, 15 is a reflection plate, and 16 is a transparent resin plate.

  The movable electrode portion 3 is composed of a transparent transparent conductive film 3a, a lead wire 3b, and the like. As a material for forming the movable electrode section 3, tin oxide, indium oxide, antimony oxide, zinc oxide, cadmium oxide, metal oxides such as indium tin oxide (ITO), and the like are mainly composed of these metal oxides. There are a composite film, gold, silver, copper, tin, nickel, aluminum, palladium, and the like.

  The upper optical retardation film 4 has a function of changing linearly polarized light into circularly polarized light or substantially circularly polarized light by giving a temporal phase shift to two orthogonally polarized light components obtained by decomposing the linearly polarized light. Is a transparent film having a function of delaying the phase by ¼ wavelength with respect to incident light having a central wavelength in the visible region. That is, by using the upper optical phase difference film 4, one of two orthogonally polarized light components obtained by decomposing linearly polarized light causes a quarter wavelength of the center wavelength of the visible region of about 550 nm, that is, a phase delay of about 138 nm. . In this case, if the amplitudes of the two orthogonally polarized components are equal, the circularly polarized light is obtained. Otherwise, the elliptically polarized light is obtained. Here, “the central wavelength of the visible region is about 550 nm” is, for example, that the central wavelength of the visible region is about 550 nm. The reason why the central wavelength is about 550 nm is as follows. That is, when the central wavelength of the visible region is considered in relation to the human visibility curve, the human visible light region is about 400 nm to 700 nm, and the peak of visibility is about 550 nm. This is because by suppressing light reflection at a wavelength of 550 nm, it is possible to prevent the human eye from feeling the reflection.

  The upper optical phase difference film 4 also has a function as an input part of a touch panel pen or a finger, and therefore must have flexibility in order to facilitate input.

  Moreover, since the upper optical phase difference film 4 is processed at a high temperature when the movable electrode portion 3 is formed and the circuit is formed, the film material to be used is required to have a heat resistance of 150 ° C. or higher. In a film material having a low thermal deformation temperature (in other words, less than 150 ° C. as will be described later), the retardation value, which is a phase delay value of two-component polarized light, is changed by high-temperature treatment, and the touch according to the embodiment of the present invention. In the configuration of the input type liquid crystal display device, the visibility of the display screen is poor. However, it has been found that a film material having a higher thermal deformation temperature (in other words, 150 ° C. or higher as will be described later) has a smaller change in retardation value during high-temperature processing to a practically negligible level. Examples of such a material include a uniaxially stretched polymer film having a heat distortion temperature of 150 ° C. or higher, such as polyarylate, polyethersulfone, norbornene resin, or polysulfone. In particular, the film material is preferably uniaxially stretched polyarylate, polyethersulfone, or polysulfone film having a heat distortion temperature of 170 ° C. or higher.

  The reason why a film material having a heat deformation temperature of 150 ° C. or higher is used as the film material of the upper optical retardation film 4 and the reason why it is preferable to have a heat deformation temperature of 170 ° C. or higher will be described in detail below. .

  First, the reason why a film material having a heat deformation temperature of 150 ° C. or higher is used as the film material of the upper optical retardation film 4 will be described below.

  In general, when heat equal to or higher than the heat deformation temperature of the film material of the upper optical retardation film 4 is applied to the film material of the upper optical retardation film 4, the film material of the upper optical retardation film 4 is deformed or distorted by the heat. Causes deterioration. In that case, the upper optical retardation film 4 cannot maintain a quarter-wave retardation (retardation), and as a result, it is not possible to suppress reflection or obtain an accurate image. Therefore, the film material that can be used is limited by the temperature of each heat treatment described later performed on the upper optical retardation film 4 in the present embodiment.

  Even if the heat distortion temperature of the film material of the upper optical retardation film 4 is low (for example, less than 150 ° C.), if the heat treatment is performed at a temperature lower than the lower heat deformation temperature, the film of the upper optical retardation film 4 due to the heat is used. The material is not deformed or deteriorated, but in that case, of course, the meaning of the heat treatment is lost, that is, a number of effects obtained by the heat treatment as described later cannot be obtained. The heat treatment for manufacturing the upper optical retardation film 4 will be described below in the order of steps, that is, in the order of heat treatment (1) to heat treatment (3).

Heat treatment (1)
Usually, in order to continuously manufacture a large number of upper optical retardation films 4 of a liquid crystal display device, one film material corresponding to one or any number of upper optical retardation films 4 is continuously connected. Roll-shaped film material is prepared. In order to remove the residual solvent in the film material before forming the transparent conductive film constituting a part of the movable electrode portion 3 on such a roll-shaped film material, it is necessary to perform a heat treatment at a high temperature for a predetermined time. There is. This is because if the residual solvent is present in the film material, it becomes impossible to stably form the transparent conductive film on the film material. Therefore, after removing the residual solvent in the film material, in order to form a transparent conductive film having excellent stability and high strength on the film material, the residual solvent is kept at a high temperature of 150 ° C. or higher for a predetermined time. It is necessary to form a transparent conductive film on the film material after the heat treatment for removing the film. This is because the residual solvent cannot be sufficiently removed at temperatures below 150 ° C., and a transparent conductive film having excellent stability and high strength cannot be formed on the film material. Therefore, in order to remove the residual solvent in the film material, the heat distortion temperature of the film material, that is, the upper optical retardation film 4 needs to be 150 ° C. or higher.

Heat treatment (2)
After forming the transparent conductive film on the film material as described above, in order to form a desired circuit connected to the transparent conductive film already formed on the roll-shaped film material, first, A roll-shaped film material is cut into a single sheet to obtain a film material sheet for the upper optical retardation film 4. And the heat processing for making the dimensional error at the time of circuit formation as small as possible is performed with respect to this film raw material sheet | seat as needed. This heat treatment is desirably performed at 100 ° C. or higher and lower than 130 ° C. for about 1 hour. Therefore, the heat deformation temperature of the film material needs to be 130 ° C. or higher, and preferably 150 ° C. or higher is sufficient.

Heat treatment (3)
At the time of forming a circuit on the film material sheet, high temperature drying is performed for curing the binder and removing the solvent of the ink that has formed the desired circuit connected to the transparent conductive film. This high temperature drying is performed at 100 ° C. or higher and lower than 150 ° C. for 30 to 60 minutes. Therefore, the thermal deformation temperature of the film material needs to be 150 ° C. or higher.

  Thus, in order to perform the various heat treatments (1) to (3) described above, the film material of the upper optical retardation film 4 is a uniaxially stretched polymer film having a heat deformation temperature of 150 ° C. or higher, For example, polyarylate, polyethersulfone, polysulfone, or norbornene-based resin may be used. As the film material, uniaxially stretched polyarylate, polyethersulfone, polysulfone film or the like having a heat distortion temperature of 170 ° C. or higher is particularly preferable. As described above, if the heat distortion temperature of the film material is 150 ° C. or higher, it can be applied to various heat treatments. However, by performing the heat treatment at 170 ° C. or higher before forming the transparent conductive film, ) Is sufficiently performed, a more stable transparent electrode can be obtained. In order to perform heat treatment at 170 ° C. or higher, the thermal deformation temperature of the film material needs to be 170 ° C. or higher, which is higher than the heat treatment temperature.

Further, the member 19 depicted in FIG. 1 includes an upper optical phase difference film 4 that supports both electrodes 3 and 5, a portion around the space layer 7 sandwiched between the movable electrode 3 and the fixed electrode 5, and a fixed electrode. This is a double-sided tape 19 for adhering a base material directly forming the part 5. Instead of the double-sided tape 19, an adhesive material may be used. Examples of the adhesive used in the adhesive material or the double-sided tape 19 include acrylic, epoxy, urethane, and copolymers thereof. As the double-sided tape, for example, 532 manufactured by Nitto Denko may be used.

  The fixed electrode portion 5 is configured by a transparent conductive film 5a, a lead wire 5b, and the like, like the movable electrode portion 3. The material for forming the fixed electrode portion 5 includes tin oxide, indium oxide, antimony oxide, zinc oxide, cadmium oxide, oxides such as indium tin oxide (ITO), and composites mainly composed of these metal oxides. There are a film, gold, silver, copper, tin, nickel, aluminum, aluminum, or palladium.

A transparent optically isotropic film 12 ( see FIG. 1 ) is used as a substrate on which the fixed electrode portion 5 is directly formed.

  The transparent optical isotropic film 12 that directly forms the fixed electrode portion 5 is also subjected to a high temperature treatment in the formation of the fixed electrode portion 5 and the circuit formation, similarly to the upper optical retardation film 4.

  Next, when the fixed electrode portion 5 including the transparent conductive film is not directly provided on the lower optical retardation film 6, that is, when the fixed electrode portion 5 including the transparent conductive film is formed on the optical isotropic film 12. The following characteristics are required.

  As a material of the lower optical retardation film 6 not provided with a transparent conductive film, a uniaxially stretched transparent polymer film having a heat distortion temperature of 130 ° C. or higher, such as polycarbonate, polyarylate, polyethersulfone, Examples include norbornene resins and polysulfone. In this case, since the heat treatments (1) to (3) as described for the production of the upper optical retardation film 4 are not relevant, it is not necessary to have a heat distortion temperature of 150 ° C. or higher. However, a heat distortion temperature of 130 ° C. or higher is still necessary. This is because if the heat distortion temperature is less than 130 ° C., the retardation value may change over time.

  On the other hand, as the optically isotropic film 12 forming the fixed electrode portion 5, an unstretched polymer film having a heat distortion temperature of 150 ° C. or higher, for example, polyarylate, polyethersulfone, polysulfone, or norbornene resin Etc. are preferred. This is because the optically isotropic film 12 does not have a retardation value, so there is no problem in that respect, but still each heat treatment (1) as described for the production of the upper optical retardation film 4. This is because a heat deformation temperature of 150 ° C. or higher that can withstand it is necessary because of (3) to (3).

  Thus, by using the lower optical retardation film 6 and the optically isotropic film 12 instead of the glass substrate, the weight can be reduced as compared with the case of using the glass substrate.

In the present invention, priority is given to pressing stability and durability over thickness reduction , and optical isotropy is provided between the optical isotropic film 12 and the lower optical retardation film 6 (see FIG. 1 ) . A transparent resin plate 16 is disposed.

  As the material of the transparent resin plate 16 having optical isotropy, for example, a resin having excellent transparency such as polycarbonate, acrylic or polystyrene is used. The thickness of the transparent resin plate 16 having optical isotropy is, for example, 0.3 to 5.0 mm. If the thickness is less than 0.3 mm, the stability and durability of pressing deteriorate, and deformation such as a depression tends to occur due to repeated input. Moreover, when it exceeds 5.0 mm, it will become heavier than glass and it is not effective as a portable apparatus.

  On the other hand, a large number of spacers 10 are formed between the movable electrode portion 3 and the fixed electrode portion 5 that are arranged to face each other. By pressing the upper optical phase difference film 4 with a finger or a pen, the spacer 10 The movable electrode unit 3 contacts the fixed electrode unit 5 in an area where there is no input, and input is performed.

  In addition, the spacer 10 in the figure is exaggerated for easy understanding, and it is difficult to actually recognize it with the eyes. As an actual example, the height of each spacer 10 is 1 to 15 μm, the outer diameter of the cylinder that is each spacer 10 is 30 to 100 μm, and the spacers 10 are arranged at a constant value interval of 0.1 mm to 10 mm. ing.

  The upper polarizing plate 8 is disposed on the upper surface of the upper optical retardation film 4, and the absorption axis thereof is disposed at an angle of about 45 ° with respect to the optical axis of the upper optical retardation film 4. Here, about 45 ° is for changing linearly polarized light into circularly polarized light or substantially circularly polarized light, and is allowed to ± 3 °. By arranging in this way, the amplitudes of the two orthogonally polarized light components become equal, and the linearly polarized light that has passed through the upper optical retardation film 4 becomes circularly polarized light or substantially circularly polarized light.

  Here, the reason why the absorption axis of the upper polarizing plate 8 is allowed to be ± 3 ° with respect to 45 ° with respect to the optical axis of the upper optical retardation film 4 will be described.

  When the absorption axis of the upper polarizing plate 8 is not arranged so as to form an angle of 45 ° with respect to the optical axis of the upper optical retardation film 4, the linearly polarized light incident on the upper optical retardation film 4 is Instead of circularly polarized light, it becomes elliptically polarized light.

  Thereafter, the circularly polarized light that has returned by reflection passes through the upper optical phase difference film 4 again, and is emitted as linearly polarized light from the upper surface of the upper optical phase difference film 4, while the elliptically polarized light that has returned by reflection has an upper optical phase difference film. 4 is emitted as elliptically polarized light that is close to linearly polarized light from the upper surface of 4. In the case of perfect linearly polarized light, the light is not emitted from the upper surface of the upper polarizing plate 8 since it is orthogonal to the transmission axis (such as a slit) of the upper polarizing plate 8, and the reflected light can be suppressed as a result. . On the other hand, when the light does not become completely linearly polarized light as described above, the emission perpendicular to the transmission axis of the upper polarizing plate 8 can be stopped, but the component coincident with the transmission axis of the upper polarizing plate 8 8 is emitted from the upper surface. In other words, extra reflections remain.

  However, if the absorption axis of the upper polarizer 8 is not within an angle of 45 ° with respect to the optical axis of the upper optical retardation film 4, it is almost circularly polarized (that is, substantially circularly polarized) as long as it is within ± 3 °. This is the same, and the reflected light finally emitted from the upper surface of the upper polarizing plate 8 (the upper surface of the liquid crystal display device) can be ignored.

  Next, as a material of the upper polarizing plate 8, generally, polyvinyl alcohol is impregnated with a dichroic dye such as iodine or a dye and stretched, and cellulose-based protection such as triacetylcellulose is applied to both front and back surfaces. A flexible polarizing plate with a thickness of 200 μm covered with a film is used. An example of such an upper polarizing plate 8 is “Nitto Denko HEG1425DU”.

  By disposing the transparent touch panel 1 and the upper polarizing plate 8 in such a configuration, reflected light caused by light incident from the outside can be suppressed as follows.

  Incident light from the viewer side passes through the upper polarizing plate 8 and becomes linearly polarized light. When this linearly polarized light passes through the upper optical phase difference film 4 that gives a phase delay of ¼ wavelength with respect to incident light having a central wavelength inclined by about 45 ° with respect to the absorption axis of the upper polarizing plate 8, the linearly polarized light becomes The two polarization components are orthogonal to each other and have the same amplitude, and one of the polarization components causes a phase delay of ¼ wavelength. As a result, it changes from linearly polarized light to circularly polarized light or substantially circularly polarized light. Then, the circularly polarized light or the substantially circularly polarized light reflected at the interface between the space layer 7 and the fixed electrode portion 5 having the largest refractive index difference at the interface passes through the upper optical retardation film 4 again. The light that has passed through the upper optical retardation film 4 changes from circularly polarized light or substantially circularly polarized light to linearly polarized light. At this time, the linearly polarized light changes by 90 ° with respect to the linearly polarized light that first passes through the upper polarizing plate 8. The light does not pass through because the linearly polarized light is substantially perpendicular to the transmission axis of the upper polarizing plate 8. Therefore, the reflected light is suppressed.

  The substantially circularly polarized light here is in a state very close to circularly polarized light. When the optical axis of the upper optical retardation film 4 is at an angle of 45 ° with respect to the absorption axis of the upper polarizing plate 8, circularly polarized light is obtained, and otherwise, it is elliptically polarized light. In the above embodiment of the present invention, the upper polarizing plate 8 and the upper optical retardation film 4 are arranged with a tolerance of ± 3 ° with respect to the angle. “Substantially circularly polarized light” is elliptically polarized light within the allowable range of ± 3 °. The optical axis of the upper optical retardation film 4 is an axis parallel to the stretching direction of the film material of the upper optical retardation film 4 that is a raw material.

  Moreover, the absorption axis (or absorption axis) of the upper polarizing plate 8 is an axis parallel to the stretching direction of the film material. The light passing through the upper polarizing plate 8 is polarized and exits from the upper polarizing plate 8 as linearly polarized light only in a direction orthogonal to the absorption axis.

  The axis orthogonal to the absorption axis is called the transmission axis. In order for this upper polarizing plate 8 to transmit linearly polarized light, the direction of the transmission axis must match. The linearly polarized light whose directions do not match cannot pass through the upper polarizing plate 8.

  The linearly polarized light emitted from the liquid crystal display 2 is converted into linearly polarized light by the polarizing plate (in this case, the lower polarizing plate) as described above, and then passes through the liquid crystal display 2 as described above. For example, in the normally white display mode, light is emitted so as to coincide with the transmission axis of the upper polarizing plate 8 below the threshold voltage, and does not coincide with the transmission axis of the upper polarizing plate 8 when the threshold voltage is exceeded. It has been emitted. In the case of the normally black display mode, conversely, when the threshold voltage is exceeded, the light is emitted so as to coincide with the transmission axis of the upper polarizing plate 8 and not to coincide with the transmission axis of the upper polarizing plate 8 below the threshold voltage. To exit.

  Similarly to the absorption axis of the upper polarizing plate 8, the absorption axis (or absorption axis) of the lower polarizing plate 9 is an axis parallel to the stretching direction of the film material. Light passing through the lower polarizing plate 9 is polarized and emitted from the lower polarizing plate 9 as linearly polarized light only in a direction orthogonal to the absorption axis.

  Further, in order to suppress coloring when the display screen of the liquid crystal display device is viewed from the observer side, the incident light having the center wavelength is 1 / b between the upper optical phase difference film 4 of the transparent touch panel 1 and the liquid crystal display 2. A lower optical phase difference film 6 that gives a phase delay of four wavelengths is disposed.

  At this time, the optical axis of the upper optical phase difference film 4 and the optical axis of the lower side optical phase difference film 6 are arranged to be about 90 °. Here, about 90 ° means that circularly polarized light or substantially circularly polarized light after passing through the lower optical phase difference film 6 is changed to linearly polarized light by the upper optical phase difference film 4 and is allowed to be ± 3 °. .

  Furthermore, it arrange | positions so that the optical axis of the lower side optical phase difference film 6 may be set to about 45 degrees with respect to the linearly polarized light to emit from the apparatus surface among the linearly polarized light emitted from the liquid crystal display 2. FIG. Here, about 45 ° is for changing linearly polarized light into circularly polarized light or substantially circularly polarized light, and is allowed to ± 3 °. In addition, in the case of the structure using the lower optical phase difference film 6 provided with the fixed electrode part 5 on the upper surface, since it suppresses coloring of the display screen and becomes a part of the transparent touch panel 1, a new optical phase difference film is provided. There is no need to add. Of the linearly polarized light emitted from the liquid crystal display 2, the linearly polarized light that is desired to be emitted from the surface of the device has a relationship of forming an angle of 90 ° with the absorption axis of the upper polarizing plate 8.

  The liquid crystal display system used for the liquid crystal display 2 includes a transmissive and reflective TN liquid crystal display system, a transmissive and reflective STN display system, and the like. The lower optical retardation film 6 may be arranged so that an angle formed with the optical axis of the lower optical retardation film 6 is about 45 ° with respect to the linearly polarized light desired to be emitted from the surface of the apparatus. .

In the liquid crystal display system shown in FIG. 1, reference numeral 15 denotes a reflector. In the liquid crystal display system shown in FIG. 4, 13 is a backlight light guide plate. FIG. 2 shows an edge light surface emitting device that is a general structure of the backlight light guide plate 13. In FIG. 2, 13a represents a line light source, 13c represents a light guide plate, 13d represents a light reflection plate, 13e represents a light scattering layer, and 13b represents a diffusion sheet. The light guided from the line light source 13a into the light guide plate 13c is emitted from the front surface (upper surface in FIG. 2) of the light guide plate 13c by the light scattering layer 13e and the light reflecting plate 13d formed on the lower surface of the light guide plate 13c. . Further, the light emitted from the light guide plate 13c is caused to emit surface light uniformly as a whole by the diffusion sheet 13b installed on the upper surface of the light guide plate 13c.

In the case of the transmission type and reflection type STN liquid crystal display systems, as a configuration of the liquid crystal display 2, in addition to the liquid crystal cell 2a, as shown in FIG. The phase difference plate 14 is disposed on the upper surface of the liquid crystal cell 2a.

  In the case of a general TN liquid crystal display, as shown in FIG. 3, the light emitted from the backlight light guide plate 13 passes through the polarizing plate 9 and becomes linearly polarized light. When this linearly polarized light passes through the liquid crystal display 2 below the threshold voltage, it becomes 90 ° twisted linearly polarized light. Further, the linearly polarized light that has passed through the lower optical retardation film 6 becomes circularly polarized light, and returns to linearly polarized light again by the upper optical retardation film 4. At this time, since the angle of the optical axis of the two optical retardation films is about 90 °, the direction of this linearly polarized light is orthogonal to the absorption axis of the upper polarizing plate 8 in the normally white display mode. That is, it coincides with the transmission axis. Therefore, this linearly polarized light can pass through the polarizing plate 8 and reach the observer.

  While the present invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.

1 is a cross-sectional view showing a resistive touch-type liquid crystal display device (reflection type STN) according to the present invention. It is explanatory drawing of a backlight light-guide plate. It is explanatory drawing of the transmission axis direction and optical axis direction in the touch input-type liquid crystal display device (TN) which concerns on this invention. It is sectional drawing which shows an example of the liquid crystal display device provided with the conventional general transparent touch panel. It is sectional drawing which shows another example of the liquid crystal display provided with the conventional general transparent touch panel. It is explanatory drawing for demonstrating a state when using the portable personal computer which has the conventional liquid crystal display device of FIG. 4 in a room with a fluorescent lamp. FIG. 6 is an explanatory diagram for explaining a state when the portable terminal having the conventional liquid crystal display device of FIG. 5 is used outdoors.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Said transparent touch panel 2 Liquid crystal display 3 Movable electrode part 4 Upper side optical phase difference film 5 Fixed electrode part 6 Lower side optical phase difference film 7 Spatial layer 8 Upper side polarizing plate 9 Lower side polarizing plate 10 Spacer 12 Optical isotropic film 13 Back Light light guide plate 13a Line light source 13b Diffusion sheet 13c Light guide plate 13d Light reflection plate 13e Light scattering layer 14 Optical compensation phase difference plate 15 Reflection plate 16 Transparent resin plate 19 Double-sided tape 20 Movable side sheet 21 Fixed side sheet 500 Portable terminal 501 Pen 502 Portable personal computer 503 Pen 504 Fluorescent light

Claims (1)

In a touch input type liquid crystal display device having a liquid crystal display under the transparent touch panel,
  An upper optical phase difference film that gives a phase delay of ¼ wavelength to incident light having a central wavelength in the visible region and includes a movable electrode portion on the lower surface; and ¼ wavelength with respect to incident light having the central wavelength in the visible region A transparent resin plate having an optical isotropy on the upper surface and a lower optical retardation film provided with a fixed electrode portion through the optical isotropy film in order on the upper surface and disposed through a space layer An upper polarizing plate is disposed on the upper surface of the touch panel, a lower polarizing plate is disposed on the lower surface of the liquid crystal display, and an angle formed by the optical axis of the upper optical retardation film and the absorption axis of the upper polarizing plate is about 45 °. The angle between the optical axis of the lower optical retardation film and the linearly polarized light emitted from the liquid crystal display and desired to be emitted from the surface of the device is about 45 °, and the upper The angle between the optical axis of the optical retardation film and the optical axis of the lower optical retardation film is about 90 °. Of the linearly polarized light emitted from the liquid crystal display, the linearly polarized light to be emitted from the device surface and the upper polarized light The angle formed by the absorption axis of the plate is 90 °,
  A touch-input type liquid crystal display device in which the fixed electrode portion is directly formed on the optical isotropic film.

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