JP3849249B2 - Liquid crystal display - Google Patents

Liquid crystal display Download PDF

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Publication number
JP3849249B2
JP3849249B2 JP26423897A JP26423897A JP3849249B2 JP 3849249 B2 JP3849249 B2 JP 3849249B2 JP 26423897 A JP26423897 A JP 26423897A JP 26423897 A JP26423897 A JP 26423897A JP 3849249 B2 JP3849249 B2 JP 3849249B2
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Japan
Prior art keywords
light
liquid crystal
crystal display
front
surface
Prior art date
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Expired - Fee Related
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JP26423897A
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Japanese (ja)
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JPH11110131A (en
Inventor
哲志 吉田
学 武居
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カシオ計算機株式会社
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Priority to JP26423897A priority Critical patent/JP3849249B2/en
Publication of JPH11110131A publication Critical patent/JPH11110131A/en
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device that performs both a display using external light and a display using light from a light source, and includes a touch input panel on the front surface.
[0002]
[Prior art]
As a liquid crystal display device, there is a so-called two-way display type that performs both a display using external light such as natural light and indoor illumination light and a display using light from a light source provided in the display device.
[0003]
As the two-way display type liquid crystal display device, there is a conventional one in which a transflective plate is provided on the rear side of the liquid crystal display element, and a backlight is disposed behind the transflective plate. In general, a light guide plate that emits incident light from an end face to the front surface and a light source such as a fluorescent lamp disposed so as to face the end face of the light guide plate is used.
[0004]
This liquid crystal display device performs reflective display that uses external light when sufficient external light is obtained, and turns on the backlight when sufficient external light is not obtained. In the reflective display using external light, the light reflected from the transflective plate out of the external light incident from the front surface of the liquid crystal display element is transmitted again through the liquid crystal display element. To exit. In a transmissive display that uses light from a backlight, light that has passed through a semi-transmissive reflection plate out of light from the backlight becomes incident light on the liquid crystal display element, and the light is transmitted through the liquid crystal display element. The light is emitted to the front surface.
[0005]
Some of the two-way display type liquid crystal display devices have a screen as a touch input surface. In this type of liquid crystal display device, a transparent touch input panel is disposed on the front side of the liquid crystal display element. ing.
[0006]
The touch input panel includes a plurality of touch input units that are turned on by a touch operation, arranged in a matrix, a transparent substrate, a transparent front sheet facing the front surface of the substrate, and a front surface of the substrate. And transparent electrodes facing each other provided on the rear surface of the front sheet.
[0007]
The touch input panel includes a touch type in which electrodes are contacted by touch operation and arranged in a matrix, and a touch input unit in which the capacitance value between the electrodes is changed in a matrix by touch operation. Some are of the electrostatic capacitance type arranged.
[0008]
[Problems to be solved by the invention]
However, the conventional two-way display type liquid crystal display device has low light use efficiency in both display using external light and display using light from the backlight, and therefore uses external light. There is a problem that the display is dark both when the light from the backlight is used.
[0009]
This is because the transflective plate reflects and transmits incident light at a reflectance / transmittance according to its characteristics. Therefore, in a reflective display using external light, the front polarizing plate, the liquid crystal display element, and the rear Of the light that passes through the side polarizing plate in order and enters the transflective plate, an amount of light corresponding to the transmissivity of the transflective plate is transmitted to the rear side to become loss light, and the backlight light This is because, in the transmissive display using the light, an amount of light corresponding to the reflectance of the transflective plate out of the light from the backlight is reflected by the transflective plate and becomes lost light.
[0010]
Further, the conventional two-way display type liquid crystal display device having the touch input panel described above includes a transflective plate and a backlight arranged on the rear surface side of the liquid crystal display element, and the touch input panel on the front side of the liquid crystal display element. Therefore, there is a problem that the display device becomes thick and the manufacturing cost becomes high.
[0011]
The present invention is a two-way display type that performs both a display using external light and a display using light from a light source. The touch input panel is provided on the front surface, and both external light and light from the light source are provided. A high-efficiency liquid crystal display device that can brighten both a display using external light and a display using light from a light source, and can reduce the manufacturing cost while reducing the thickness. Is intended to provide.
[0012]
[Means for Solving the Problems]
  The liquid crystal display device of the present invention is provided on the front side of a liquid crystal display element having a high reflectance reflecting means on the rear side.It has a flat front surface and a rear surface that are inclined to face each other, and an end surface that intersects these two surfaces, and emits incident light from the front surface and incident light from the end surface to the rear surface, respectively, from the rear surface. A light guide plate that emits incident light to the front surface, a transparent front sheet having a uniform thickness that faces the front surface of the light guide plate, and a front surface of the light guide plate and a rear surface of the front sheet that face each other. Consisting of a transparent electrode,Incident light from the front surface and incident light from the end surface are emitted to the rear surface and incident on the liquid crystal display element, and the light emitted from the liquid crystal display element incident on the rear surface is guided to the front surface. A touch input panel is arranged, and a light source is arranged to face the end face of the touch input panel.
[0013]
This liquid crystal display device is of a two-way display type that performs both a display using external light and a display using light from a light source. When using external light, the liquid crystal display device is placed on the front surface of the liquid crystal display element. External light incident on the touch panel arranged from the front surface is transmitted through the touch panel and emitted to the rear surface, and the light enters the liquid crystal display element and is reflected by the reflecting means on the rear surface side to be front of the liquid crystal display element. Is incident on the touch panel from its rear surface, passes through the touch panel, and exits to the front surface of the display device.
[0014]
Further, when using light from the light source, light from the light source is taken into the touch panel from its end face, guided by the touch panel and emitted to the rear face, and the light enters the liquid crystal display element and The light is reflected by the reflecting means and emitted to the front surface of the liquid crystal display element, is incident on the touch panel from its rear surface, passes through the touch panel, and is emitted to the front surface of the display device.
[0015]
That is, this liquid crystal display device performs reflective display both when using external light and when using light from a light source. Therefore, the reflecting means reflects incident light with high reflectance. It's okay.
[0016]
For this reason, according to this liquid crystal display device, both external light and light from the light source can be used with high efficiency. Therefore, even when displaying using external light, display using the light from the light source is performed. In this case, a sufficiently bright display can be obtained.
[0017]
Moreover, this liquid crystal display device has a touch input panel having the above-mentioned light guide property arranged on the front side of the liquid crystal display element, and a light source is arranged facing the end face of the touch input panel. Compared with a conventional liquid crystal display device in which a transflective plate and a backlight are disposed on the rear surface side of the liquid crystal display element and a touch input panel is disposed on the front surface side, the thickness of the entire display device can be reduced. At the same time, the manufacturing cost can be reduced.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The liquid crystal display device according to the present invention emits incident light from the front surface and incident light from the end surface to the front surface side of the liquid crystal display element having a high-reflectance reflecting means on the rear surface side, respectively. A touch input panel having a light guide property for emitting light emitted from the liquid crystal display element that enters the device and incident on the rear surface to the front surface is disposed, and a light source is disposed to face the end surface of the touch input panel. As a result, both the display using external light and the display using light from the light source are brightened, and the thickness is reduced and the manufacturing cost is reduced.
[0019]
In the liquid crystal display device of the present invention, the touch input panel includes, for example, a light guide plate that emits incident light from the front surface and incident light from the end surface to the rear surface, and emits incident light from the rear surface to the front surface, The transparent front sheet facing the front surface of the light guide plate, and the transparent electrodes facing each other provided respectively on the front surface of the light guide plate and the rear surface of the front sheet, and with such a configuration, The touch input panel can have the above-described light guiding property.
[0020]
The light guide plate of the touch input panel may be a transparent plate. When a light guide plate made of this transparent plate is used, it is desirable that the front sheet of the touch input panel has light diffusibility. In this way, even when a specular reflector having excellent reflectivity is used as the reflecting means, the outside scene such as the face of the display observer and the object behind it can be reflected on the reflecting surface of the reflecting means. There is no reflection.
[0021]
In addition, the light guide plate of the touch input panel has light scattering properties. Due to the scattering properties, incident light from the front surface and incident light from the end surface are emitted to the rear surface, and incident light from the rear surface is emitted to the front surface. If the light guide plate made of this scattering plate is used, the reflection of the outside scene can be prevented.
[0022]
Furthermore, in the liquid crystal display device according to the present invention, between the rear surface of the touch input panel and the reflecting means, the transmitted light has a luminance distribution in which the luminance of the emitted light in the direction perpendicular to the front surface of the liquid crystal display element is high. It is desirable to provide an optical member that emits light, and in this way, a display with high front luminance can be obtained.
[0023]
【Example】
FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention, in which the left side is the upper edge side of the screen and the right side is the lower edge side of the screen.
The liquid crystal display device includes a liquid crystal display element 10, a touch input panel 20 disposed on the front side of the liquid crystal display element 10, and a light source 28 disposed to face an end surface of the touch input panel 20. Yes.
[0024]
The liquid crystal display element 10 is a TN (twisted nematic) mode reflective liquid crystal display element, and includes a liquid crystal cell 11, a front polarizing plate 18a and a rear polarizing plate 18b disposed across the liquid crystal cell 11, The reflector plate 19 is disposed behind the rear polarizing plate 18b as reflecting means.
[0025]
The liquid crystal cell 11 is of an active matrix type, for example, and a plurality of transparent pixels arranged in a matrix form on the inner surface of the rear substrate 11b of the pair of front and rear transparent substrates (glass substrates) 11a and 11b. An electrode 12 is formed, and an alignment film 13b is provided thereon.
[0026]
Although not shown in the figure, active elements made of TFTs (thin film transistors) are provided on the inner surface of the rear substrate 11b so as to correspond to the respective pixel electrodes 12, and gates are provided on the TFTs in the respective pixel electrode rows. A gate line for supplying a signal and a data line for supplying a data signal to the TFT of each pixel electrode row are wired, and each pixel electrode 12 is connected to a TFT corresponding to the electrode. Yes.
[0027]
On the other hand, on the inner surface of the front substrate 11a, red, green, and blue color filters 14R, 14G, and 14B are alternately arranged corresponding to the pixel electrodes 12, and these color filters 14R and 14G are provided. , 14B is formed with a single film-like transparent counter electrode 15 facing all of the pixel electrodes 13, and an alignment film 13a is provided thereon. Although not shown in the drawing, the color filters 14R, 14G, and 14B are covered with a transparent protective film (insulating film), and the counter electrode 15 is formed on the protective film.
[0028]
The pair of substrates 11a and 11b are joined via a frame-shaped sealing material 16, and a liquid crystal layer 17 is provided in a region surrounded by the sealing material 16 between the substrates 11a and 11b. Yes.
[0029]
The molecules of the liquid crystal of the liquid crystal layer 17 are regulated by the alignment films 13a and 13b in the alignment direction in the vicinity of the substrates 11a and 11b, respectively, and at a predetermined twist angle (for example, approximately 90 °) between the substrates 11a and 11b. The front-side polarizing plate 18a and the rear-side polarizing plate 18b are attached to the front and back surfaces of the liquid crystal cell 11 so that the directions of their transmission axes are substantially orthogonal to each other or substantially parallel to each other. .
[0030]
The reflector 19 disposed behind the rear polarizing plate 18b is a reflector that reflects incident light with high reflectivity. In this embodiment, a specular reflector having the highest reflectivity is used. Yes.
[0031]
On the other hand, the touch input panel 20 disposed on the front side of the liquid crystal display element 10 emits incident light from the front surface and incident light from the end surface to the rear surface and enters the liquid crystal display element 10 and It has a light guide property to emit light emitted from the liquid crystal display element 10 incident on the rear surface to the front surface.
[0032]
The touch input panel 20 used in this embodiment is of a contact type in which a plurality of touch input units in which electrodes come into contact with each other by a touch operation are arranged in a matrix, and incident light from the front surface and incident light from the end surface Are respectively emitted to the rear surface and incident light from the rear surface is emitted to the front surface, the front sheet 22 facing the front surface of the light guide plate 21 with a gap, and the front surface of the light guide plate 21 It consists of a plurality of transparent electrodes 23, 24 facing each other provided on the rear surface of the front sheet 22 (surface facing the light guide plate 21).
[0033]
The light guide plate 21 is a wedge-shaped transparent plate whose front surface is inclined so as to be closer to the rear surface from one end to the other end. This is a light capturing surface (hereinafter referred to as a light source light capturing end surface). In the drawing, the inclination of the front surface of the light guide plate 21 is exaggerated, but the inclination angle (angle with respect to the rear surface) is in the range of 1 ° to 10 °, preferably in the range of 2 ° to 5 °, and more preferably. It is set in the range of 3 ° to 4 °.
[0034]
The front sheet 22 is a flexible transparent sheet, and in this embodiment, a diffusion plate that diffuses and emits transmitted light is used. The light diffusibility of the front sheet 22 is set so that the diffusion state of the transmitted light is within a range where an image displayed by the liquid crystal display element 10 can be visually recognized with sufficient clarity.
[0035]
The front sheet 22 is regulated on the front side of the light guide plate 21 by a plurality of gap members 25 made of a granular transparent material interposed between the front sheet 22 and the light guide plate 21. 21 is arranged in parallel with the front surface of 21, and is bonded to the light guide plate 21 via a frame-like spacer 26 at the peripheral edge.
[0036]
The plurality of transparent electrodes 23 provided on the front surface of the light guide plate 21 are provided on the rear surface of the belt-like electrode along one direction (the vertical direction of the screen in FIG. 1) formed in parallel with each other and on the rear surface of the front sheet 22. The plurality of transparent electrodes 24 are strip electrodes along a direction orthogonal to the strip electrode 23 on the light guide plate 21 side (the horizontal direction of the screen in FIG. 1), and the portions where these electrodes 23 and 24 face each other are Each of the electrodes 24 on the side of the front sheet 22 is brought into contact with the electrode 23 on the side of the light guide plate 21 due to the bending deformation of the front sheet 22 by a touch operation. The identification of each touch input unit of the touch input panel is displayed by the liquid crystal display element 10.
[0037]
Further, in this embodiment, the prism sheet 27 is provided on the rear surface of the touch input panel 20 as an optical member that emits transmitted light as light having a high luminance distribution in the direction perpendicular to the front surface of the liquid crystal display element 10. Is provided.
[0038]
The prism sheet 27 is formed by forming a plurality of horizontally long prism portions 27a along the width direction on one surface of a transparent plate so as to be parallel to each other in the width direction. , And has a right-angled triangular cross-sectional shape in which one side surface is vertical and the other side surface is inclined.
[0039]
Note that the arrangement pitch of the prism portions 27a of the prism sheet 27 is set to be substantially equal to or smaller than the arrangement pitch of the pixel regions of the liquid crystal display element 10. In the example shown in FIG. 1, the arrangement pitch of the prism portions 27 a is approximately 1 / 1.5 of the arrangement pitch of the pixel region of the liquid crystal display element 10.
[0040]
The prism sheet 27 faces the flat surface opposite to the prism forming surface to the rear surface of the light guide plate 21 of the touch input panel 20, and the length direction of each prism portion 27 a is taken in the light source light of the light guide plate 21. It is attached to the rear surface of the light guide plate 21 with a transparent adhesive (which may be a double-sided adhesive sheet) (not shown) so that it is parallel to the end face and the vertical side surface of each prism portion 27a is directed toward the light source light capturing end face. ing.
[0041]
The light guide plate 21 and the prism sheet 27 are formed of a transparent material such as an acrylic resin, and it is desirable that the refractive indexes of the respective lights be the same. The adhesive includes the light guide plate 21 and the prism. It is preferable to use a sheet having substantially the same refractive index as that of the sheet 27.
[0042]
As described above, if the refractive indexes of the light guide plate 21 and the prism sheet 27 and the pressure-sensitive adhesive are substantially the same, the light transmission path from one side of the light guide plate 21 and the prism sheet 27 to the other side of the light guide plate 21 and the prism sheet 27 It can be a linear path with little refraction, reflection and scattering.
[0043]
The touch input panel 20 is arranged on the front side of the liquid crystal display element 10 with the light source light capturing end face of the light guide plate 21 facing the main capturing direction of external light.
[0044]
That is, when using external light, the two-way display type liquid crystal display device is mainly exposed from the direction inclined to the upper edge side of the screen with respect to the direction perpendicular to the screen, like the normal reflection type liquid crystal display device. Since the screen is used in a direction in which bright external light is obtained so as to capture light, in this embodiment, the touch input panel 20 is used as the main light capturing direction of the light source light. It is provided toward the upper edge of the screen.
[0045]
The touch input panel 20 is not shown in a state where the top of each prism portion 27a of the prism sheet 27 provided on the rear surface thereof is in contact with or close to the front surface of the liquid crystal display element 10 (the front surface of the front polarizing plate 18a). It is supported by the support means.
[0046]
Further, the light source 28 has a straight tubular fluorescent lamp 28a having a length extending over the entire length of the light source light capturing end face of the touch input panel 20 and directs light emitted from the fluorescent lamp 28a to the periphery thereof toward the touch input panel 20. The reflector 29 is in the shape of an elliptic cylinder having a light exit on one side.
[0047]
The light source 28 is arranged on the side of the light guide plate 21 of the touch input panel 20 with the exit of the reflector 29 facing the light source light capturing end surface of the touch input panel 20.
[0048]
This liquid crystal display device is of a two-way display type that performs both a display using outside light and a display using light from the light source 28. The light source 28 has a sufficiently bright external light. Used when not available.
[0049]
First, a display using light from the light source 28 will be described. The light from the light source 28 is guided to the touch input panel 20 disposed on the front side of the liquid crystal display element 10 as indicated by an arrow L1 in FIG. The light is taken into the light plate 21 from its end face, guided through the light guide plate 21, emitted to the rear surface of the light guide plate 21, and enters the liquid crystal display element 10.
[0050]
In this case, light from the light source 28 is incident on the light guide plate 21 at various incident angles from the light source light capturing end surface. The front surface of the light guide plate 21 is a rear surface from the light source light capturing end side toward the opposite side. Since the gap between the front surface of the light guide plate 21 and the front sheet 22 disposed on the front surface side is an air layer, the light guide plate 21 extends from the light source light capturing end surface. Of the light incident on the front surface of the light guide plate 21 is totally reflected at the interface between the front surface of the light guide plate 21 (the front surface of the electrode 23 where the transparent electrode 23 is formed) and the air layer. The light guide plate 21 is guided in the rear surface direction.
[0051]
Of the light incident from the light source light capturing end surface, the light traveling toward the rear surface of the light guide plate 21 and the light totally reflected by the front surface of the light guide plate 21 are transmitted from the rear surface of the light guide plate 21 to the prism sheet 27. The light enters the prism portion 27a.
[0052]
As described above, the prism portion 27a has a right-angled triangular cross-sectional shape in which one side surface is vertical and the other side surface is inclined, and the vertical side surface is the direction of the light source light capturing end surface of the light guide plate 21. Therefore, the light incident on each prism portion 27a is incident on the inclined surfaces of these prism portions 27a from the direction facing the inclined surfaces (perpendicular side surface direction). The light incident on the inclined surface of the prism portion 27a, that is, the interface between the air layer between the liquid crystal display element 10 and the inclined surface, is larger than the total reflection angle critical angle (nearly perpendicular). And enters the liquid crystal display element 10 as light having a smaller angle with respect to the vertical direction. That is, the light that passes through the prism sheet 27 and enters the liquid crystal display element 10 is light having a luminance distribution in which the luminance of the light emitted in the direction perpendicular to the front surface of the liquid crystal display element 10 is high.
[0053]
The light incident on the inclined surface of the prism portion 27a at an angle smaller than the total reflection angle critical angle is totally reflected on the inclined surface, but the light is reflected on the front surface of the light guide plate 21. Light incident on another prism portion 27a and incident on the inclined surface of the prism portion 27a at an angle larger than the total reflection angle critical angle is transmitted through the interface, and light in a direction in which the angle with respect to the vertical direction is reduced. Therefore, most of the light from the light source 28 taken into the light guide plate 21 enters the liquid crystal display element 10 without causing a loss.
[0054]
The light incident on the liquid crystal display element 10 is first absorbed by the front polarizing plate 18a with light having a polarization component along the absorption axis, and becomes linearly polarized light with a polarization component along the transmission axis. Incident.
[0055]
The light that has entered the liquid crystal cell 11 is absorbed by the color filters 14R, 14G, and 14bB to be colored red, green, and blue, and is birefringent in the process of passing through the liquid crystal layer 17. Accordingly, the polarization state is changed and emitted to the rear surface of the liquid crystal cell 11.
[0056]
The light transmitted through the liquid crystal cell 11 is incident on the rear polarizing plate 18b. Among the light, the light of the polarization component along the transmission axis of the rear polarizing plate 18b is transmitted through the rear polarizing plate 18b. The image light is reflected by the reflecting plate 19, passes through the rear polarizing plate 18 b, the liquid crystal cell 11, and the front polarizing plate 18 a and is emitted to the front surface of the liquid crystal display element 10.
[0057]
Then, the light emitted to the front surface of the liquid crystal display element 10 is refracted in the direction closer to the vertical direction by the prism sheet 27 and becomes light having a luminance distribution in which the luminance of the light emitted in the vertical direction is higher. The light enters the touch input panel 20 from its rear surface, passes through the touch input panel 20 in the thickness direction, is diffused by the front sheet 22 and is emitted to the front surface of the display device.
[0058]
Next, display using external light will be described. At this time, external light incident on the liquid crystal display device from the front as indicated by an arrow L2 in FIG. 1 causes the touch input panel 20 to move in the thickness direction. Then, the light passes through the prism sheet 27 and enters the liquid crystal display element 10.
[0059]
In this case, the external light incident on the touch input panel 20 from the front surface is diffused by the front sheet 22 of the touch input panel 20, but the main light capturing direction of the external light (the screen is perpendicular to the screen). The direction inclined toward the upper edge side) is the direction of the light source light capturing end side of the touch input panel 20, and the prism sheet 27 has the vertical side surface of each prism portion 27a in the direction of the light source light capturing end surface. Since the light transmitted through the touch input panel 20 is refracted by each prism portion 27a of the prism sheet 27, the light in the direction in which the angle with respect to the direction perpendicular to the front surface of the liquid crystal display element 10 is reduced, That is, the light emitted in the vertical direction is incident on the liquid crystal display element 10 as light having a high luminance distribution.
[0060]
After this, it is the same as when using the light from the light source 28 described above, and the light incident on the liquid crystal display element 10 passes through the front polarizing plate 18a and enters the liquid crystal cell 11, and the liquid crystal cell 11 Of the light emitted to the rear surface, the light of the polarization component along the transmission axis of the rear polarizing plate 18b is transmitted through the rear polarizing plate 18b to become image light, and this image light is reflected by the reflecting plate 19, The light passes through the rear polarizing plate 18b, the liquid crystal cell 11, and the front polarizing plate 18a and is emitted to the front surface of the liquid crystal display element 10.
[0061]
Then, the light emitted to the front surface of the liquid crystal display element 10 is refracted in a direction closer to the vertical direction by the prism sheet 27 and becomes a light having a luminance distribution in which the luminance of the light emitted in the vertical direction is higher. The light enters the input panel 20 from its rear surface, passes through the touch input panel 20 in the thickness direction, and is emitted as diffused light to the front surface of the display device.
[0062]
That is, the liquid crystal display device performs reflective display both when using outside light and when using light from the light source 28. Therefore, the reflection plate 19 reflects incident light with high reflectivity. You can make it.
[0063]
For this reason, according to this liquid crystal display device, both external light and light from the light source 28 can be used with high efficiency. Therefore, when displaying using external light, the light from the light source 28 is used. When displaying, a sufficiently bright display can be obtained.
[0064]
In addition, the liquid crystal display device emits incident light from the front surface and incident light from the end surface to the rear surface of the liquid crystal display device 10 and makes it incident on the liquid crystal display device 10 and incident on the rear surface. A touch input panel 20 having a light guide property for emitting light emitted from the liquid crystal display element 10 to the front surface is disposed, and a light source 28 is disposed opposite to an end surface of the touch input panel 20. Compared with conventional liquid crystal display devices that have a transflective reflector and backlight on the back side of the device and a touch input panel on the front side, the overall thickness of the display device can be reduced, and manufacturing is possible. Cost can be reduced.
[0065]
In the above embodiment, the touch input panel 20 includes the light guide plate 21 that emits the incident light from the front surface and the incident light from the end surface to the rear surface and the incident light from the rear surface to the front surface. Since it is composed of a transparent front sheet 22 facing the front surface of the light plate 21 and transparent electrodes 23 and 24 facing each other provided on the front surface of the light guide plate 21 and the rear surface of the front sheet 22, respectively. The touch input panel 20 can have the above-described light guiding properties.
[0066]
Further, in the above embodiment, since the front sheet 22 of the touch input panel 20 is a light diffusing diffuser, the light transmitted through the touch input panel 20 is diffused and emitted to the front surface of the display device. Therefore, even when a specular reflector excellent in reflectivity is used as the reflector 19 disposed on the rear surface side of the liquid crystal display element 10, an external scene such as a display observer's face or an object behind the reflector is reflected on the reflector 19. There is no reflection of the so-called outside scene.
[0067]
The light diffusibility of the front sheet 22 is set so that the diffusion state of the transmitted light is within a range where an image displayed by the liquid crystal display element 10 can be viewed with sufficient clarity as described above. Therefore, even if the light emitted to the front surface of the liquid crystal display device is diffused, an image with good image quality with very little blur is observed.
[0068]
Furthermore, in the above-described embodiment, between the rear surface of the touch input panel 20 and the liquid crystal display element 10, the transmitted light is emitted as light having a high luminance distribution in which the light emitted in the direction perpendicular to the front surface of the liquid crystal display element 10 is high. Since the outgoing prism sheet 27 is provided, the incident light is made incident on the liquid crystal display element 10 as light of the luminance distribution and the reflection plate 19, both when using external light and when using light from the light source 28. The light that is reflected by the light and emitted to the front surface of the liquid crystal display element 10 can be incident on the touch input panel 20 as light having a luminance distribution in which the luminance of the light emitted in the vertical direction is higher. The luminance distribution of the light that is transmitted through the input panel 20 and diffused and emitted to the front surface is set to a distribution with high luminance of the light emitted in the vertical direction, so that a display with high front luminance can be obtained.
[0069]
Further, in the liquid crystal display device, since the emitted light is light having a high luminance distribution in the vertical direction, the display contrast is reduced due to reflection of external light on the front surface of the touch input panel 20 (front surface of the front sheet 22). There is almost no.
[0070]
That is, since external light is incident mainly from a direction inclined to the upper edge side of the screen with respect to a direction perpendicular to the screen, most of the external light reflected on the front surface of the front touch input panel 20 is a broken line in FIG. As indicated by the arrows, the light is directed obliquely at a reflection angle corresponding to the incident angle with respect to the touch input panel 20, but the light emitted from the liquid crystal display device uses light from the light source 28 even in display using external light. Even in the display, the light emitted in the direction perpendicular to the front surface of the liquid crystal display element 10 is light having a high luminance distribution.
[0071]
The display image of the liquid crystal display device is observed from the front direction with respect to the screen, that is, near the direction perpendicular to the front surface of the liquid crystal display element 10, but according to the liquid crystal display device, the display image is observed from the front direction. Most of the light that is emitted is from the liquid crystal display device and almost no reflected light that is reflected from the front surface of the touch input panel 20 in the oblique direction is visible. The surface reflection light reflected from the front surface is not superimposed and the contrast is not deteriorated.
[0072]
Further, the liquid crystal display device performs a reflective display both when using outside light and when using light from the light source 28, so that the liquid crystal display can be compared with a conventional two-way display type liquid crystal display device. The degree of freedom in designing the element 10 is increased, and the element 10 can be designed easily.
[0073]
That is, in the conventional two-way display type liquid crystal display device, the display using the outside light is the reflection type display, the display using the backlight light is the transmission type display, and the reflection type display using the outside light is used. In this case, incident light from the front side is transmitted through the liquid crystal display device and reflected, and the light is transmitted again through the liquid crystal display device and emitted to the front side, whereas transmission using the light of the backlight is used. In the type display, incident light from the rear side is transmitted through the liquid crystal display device and emitted to the front side, so that the display color difference caused by the difference in the light transmission path between the reflection type display and the transmission type display is compensated. Thus, it is necessary to design a liquid crystal display device.
[0074]
In this respect, in the liquid crystal display device of the above embodiment, both the display using the external light and the display using the light from the light source 28 are the reflective display, and the light transmission path is almost the same in both displays. The design of the liquid crystal display element 10 is easy.
[0075]
FIG. 2 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention, in which the left side is the upper edge side of the screen and the right side is the lower edge side of the screen.
In the liquid crystal display device of this embodiment, the liquid crystal display element 10 has a configuration in which reflecting means is provided on the rear surface side of the liquid crystal cell 11 and a polarizing plate 18a is disposed only on the front surface side of the liquid crystal cell 11. The configuration is the same as that of the first embodiment described above.
[0076]
In this embodiment, an electrode (in this case, a pixel electrode) provided on the inner surface of the rear substrate 11b of the liquid crystal cell 11 is a reflective electrode 12a made of a highly reflective mirror metal film, and this electrode 12a also serves as a reflecting means. ing.
[0077]
In this liquid crystal display device, the liquid crystal passes through the touch input panel 20 and the prism sheet 27 as indicated by arrows L1 and L2 in FIG. Light incident on the display element 10 and transmitted through the polarizing plate 18a and incident on the liquid crystal cell 11 is transmitted through the color filters 14R, 14G and 14bB and the liquid crystal layer 17 and reflected by the reflective electrode 12a. The light of the polarization component along the transmission axis of the polarizing plate 18 a passes through the polarizing plate 18 a and is emitted to the front surface of the liquid crystal display element 10 as image light.
[0078]
Then, the light emitted to the front surface of the liquid crystal display element 10 is refracted in a direction closer to the vertical direction by the prism sheet 27 and is incident on the touch input panel 20 from the rear surface, and is transmitted through the touch input panel 20. The diffused light is emitted to the front surface of the display device.
[0079]
That is, the liquid crystal display device of this embodiment also performs a reflective display both when using external light and when using light from the light source 28, and therefore, on the inner surface of the rear substrate 11b of the liquid crystal cell 11. The provided reflective electrode 12a may reflect incident light with a high reflectivity. Therefore, a sufficiently bright display can be obtained both when displaying using external light and when using light from the light source 28. Obtainable.
[0080]
In addition, in this embodiment, the liquid crystal display element 10 has a configuration in which the polarizing plate 18a is disposed only on the front side of the liquid crystal cell 11, so that when using outside light or using light from the light source 28, The number of times the incident light is transmitted through the polarizing plate before being emitted to the front surface of the apparatus is one time in the incident path and one time in the output path. Therefore, compared to the first embodiment described above, the polarizing plate is used. Light absorption can be reduced, light utilization efficiency can be increased, and the display can be further brightened.
[0081]
Further, in the liquid crystal display device of this embodiment, the same touch input panel 20 as that used in the first embodiment is arranged on the front surface side of the liquid crystal display element 10, but the liquid crystal display element 10 is arranged on the rear side. The polarizing plate is not provided, and the electrode provided on the inner surface of the rear substrate 11b of the liquid crystal cell 11 is used as a reflective electrode 12a. The electrode 12a also serves as a reflective film. Furthermore, the thickness of the entire apparatus can be reduced, and the manufacturing cost can be reduced.
[0082]
Also in this embodiment, since the light transmitted through the touch input panel 20 and emitted to the front surface is diffused by the front sheet (diffuser plate) 22 of the touch input panel 20, the reflecting means is the specular reflection electrode 12a. However, there is no reflection of the outside scene.
[0083]
Further, in the above-described embodiment, the prism sheet 27 is provided between the rear surface of the touch input panel 20 and the liquid crystal display element 10, so that both the front light and the light from the light source 28 are used. A display with high luminance can be obtained, and there is almost no decrease in display contrast due to the surface reflection of external light reflected on the front surface of the touch input panel 20 as indicated by a broken line arrow in FIG.
[0084]
In the second embodiment, the electrode provided on the inner surface of the rear substrate 11b of the liquid crystal cell 11 is the reflective electrode 12a. However, the electrode 12a is a transparent electrode, and a reflector or the like is provided on the outer surface of the rear substrate 11b. Reflecting means may be arranged.
[0085]
In the first and second embodiments described above, the front sheet 22 of the touch input panel 20 is provided with light diffusibility. However, the light transmitted through the touch input panel 20 in the thickness direction is the same as that of the light guide plate 21. Since it is also scattered by the gap material 25 interspersed with the front sheet 22 in a scattered state, if the distribution amount of the gap material 25 is increased to some extent, the front sheet 22 does not have light diffusibility. In addition, the light emitted to the front surface of the display device due to scattering of the transmitted light by the gap member 25 can be diffused light, and the above-described reflection of the outside scene can be prevented.
[0086]
Further, the reflection of the outside scene can also be prevented by providing the reflecting plate 19 or the reflecting electrode 12a with diffuse reflection within a range where the reflectance is not lowered so much. In that case, the touch input panel 20 is diffused with light. It does not have to have sex.
[0087]
FIG. 3 is a sectional view of a liquid crystal display device according to a third embodiment of the present invention, in which the left side is the upper edge side of the screen and the right side is the lower edge side of the screen.
The liquid crystal display device of this embodiment includes two polarizing plates 18a and 18b. The liquid crystal display element 10 includes a liquid crystal cell 11, a back side polarizing plate 18b disposed on the rear surface side, and a back side thereof. The front polarizing plate 18a is used for the front sheet of the touch input panel 20 that is arranged on the front side of the liquid crystal display element 10 and is composed of the reflector 19 arranged. Other configurations are the same as those of the first embodiment described above.
[0088]
In this embodiment, the front sheet of the touch input panel 20 may be composed of only the front polarizing plate 18a. For example, the front sheet is formed by laminating a diffusion plate (not shown) on the polarizing plate 18a. Those having light diffusibility are desirable.
[0089]
In the liquid crystal display device of this embodiment, since the front polarizing plate 18a is on the front surface of the touch input panel 20, when the light from the light source 28 is used, as shown by the arrow L1 in FIG. Light that enters the liquid crystal display element 10 through the prism sheet 27 enters the liquid crystal cell 11 without being subjected to the polarization action by the polarizing plate.
[0090]
Therefore, when using the light from the light source 28, the light incident on the liquid crystal cell 11 is simply absorbed by the color filters 14R, 14G, and 14bB in the absorption wavelength region and colored red, green, and blue. The optical change due to the birefringence of the liquid crystal layer 17 does not occur, and the unpolarized light is emitted to the rear surface of the liquid crystal cell 11.
[0091]
Then, this light is absorbed by the rear polarizing plate 18b with the polarized light component along the absorption axis thereof to become linearly polarized light, reflected by the reflecting plate 19, and transmitted again through the rear polarizing plate 18b. The light enters the cell 11 from the rear surface side.
[0092]
At this time, since the light incident on the liquid crystal cell 11 is linearly polarized light, this light changes its polarization state according to the birefringence of the liquid crystal layer 17 and is emitted to the front surface of the liquid crystal display element 10.
[0093]
Then, the light emitted to the front surface of the liquid crystal display element 10 passes through the prism sheet 27 and enters the touch input panel 20 from the rear surface, and among the light, the front polarizing plate which is the front sheet of the touch input panel 20 The light of the polarization component along the transmission axis 18a passes through the polarizing plate 18a and becomes image light, which is emitted to the front surface of the display device.
[0094]
When using external light, as shown by the arrow L2 in FIG. 3, incident external light is polarized light along the absorption axis by the front polarizing plate 18a that is the front sheet of the touch input panel 20. Is absorbed into the linearly polarized light, which passes through the touch input panel 20 and the prism sheet 27 and enters the liquid crystal display element 10.
[0095]
For this reason, when using external light, the light incident on the liquid crystal display element 10 is absorbed by the color filters 14R, 14G, and 14bB in the process of passing through the liquid crystal cell 11, and red, green, While being colored blue, the polarization state is changed according to the birefringence of the liquid crystal layer 17, and the light of the polarization component along the transmission axis of the rear polarizing plate 18b of the light is transmitted through the rear polarizing plate 18b. Image light.
[0096]
Then, the image light is reflected by the reflection plate 19, is transmitted through the rear polarizing plate 18 b and the liquid crystal cell 11, is emitted to the front surface of the liquid crystal display element 10, and is transmitted through the prism sheet 27 and the touch input panel 20. Then, the light is emitted to the front surface of the display device.
[0097]
That is, the liquid crystal display device of this embodiment also performs a reflective display when using outside light and using light from the light source 28. Therefore, the reflection plate 19 provided in the liquid crystal display element 10 is The incident light may be reflected with a high reflectance, and therefore a sufficiently bright display can be obtained both when displaying using external light and when using light from the light source 28.
[0098]
Moreover, in this embodiment, the liquid crystal display element 10 has a configuration in which the polarizing plate 18b is disposed only on the rear surface side of the liquid crystal cell 11, and the front polarizing plate 18a is provided on the front surface of the touch input panel 20 as its front sheet. The number of times the incident light is transmitted through the polarizing plate until it is emitted to the front surface of the device is four times when using outside light (transmitting the front side polarizing plate 18a and the rear side polarizing plate 18b twice each). However, when the light from the light source 28 is used, the light passes through the rear polarizing plate 18b twice and the front polarizing plate 18a only once. Therefore, the light source 21 is compared with the first embodiment described above. The light absorption by the polarizing plate when using the light from the light source can be reduced, and the display using the light from the light source 21 can be further brightened.
[0099]
Further, in the liquid crystal display device of this embodiment, the touch input panel 20 is disposed on the front side of the liquid crystal display element 10, but the liquid crystal display element 10 is not provided with a front polarizing plate, and the touch input panel 20 Since the front sheet is the front polarizing plate 18a, the thickness of the entire apparatus can be made thinner than that of the first embodiment, and the manufacturing cost can be reduced.
[0100]
In the liquid crystal display device of this embodiment, the front sheet of the touch input panel 20 is a front polarizing plate 18a. As the front sheet, a light diffusing property is obtained by laminating a diffusion plate on the polarizing plate 18a. If it is used, the light transmitted through the touch input panel 20 and emitted to the front surface is diffused by the polarizing plate 18a, so that even if the reflecting means is the specular reflection plate 19, an external scene is reflected. There is no.
[0101]
Further, in the above-described embodiment, the prism sheet 27 is provided between the rear surface of the touch input panel 20 and the liquid crystal display element 10, so that both the front light and the light from the light source 28 are used. A display with high luminance can be obtained, and there is almost no decrease in display contrast due to surface reflection of external light reflected on the front surface of the touch input panel 20 as indicated by a dashed arrow in FIG.
[0102]
FIG. 4 is a sectional view of a liquid crystal display device according to a fourth embodiment of the present invention, in which the left side is the upper edge side of the screen and the right side is the lower edge side of the screen.
In the liquid crystal display device of this embodiment, the touch input panel 30 using the light scattering plate 31 having light scattering properties is disposed on the front side of the liquid crystal display element 10, and the other configuration is the first embodiment described above. Same as example.
[0103]
The touch input panel 30 used in this embodiment is a contact type in which a plurality of touch input units that are in contact with each other by a touch operation are arranged in a matrix, and includes incident light from the front surface and incident light from the end surface. Are respectively emitted from the rear surface and incident light from the rear surface is emitted to the front surface, a front sheet 32 facing the front surface of the light guide plate 31 with a gap therebetween, and the front surface of the light guide plate 31. It consists of a plurality of transparent electrodes 33, 34 facing each other provided on the rear surface of the front sheet 32 (surface facing the light guide plate 31).
[0104]
The light guide plate 31 is a flat scattering plate made of a light scattering polymer. Due to the light scattering property, the incident light from the front surface and the incident light from the end surface are emitted to the rear surface, and the incident light from the rear surface is transmitted to the front surface. To exit.
[0105]
The plate thickness of the light guide plate 31 is within a range in which the diffused state of scattered light transmitted through the light guide plate 31 in the thickness direction and emitted can be visually recognized with sufficient clarity. Is set to
[0106]
That is, the light guide plate 31 made of the light scattering polymer has a light guide property for guiding incident light from any direction while scattering the incident light, but the degree of scattering corresponds to the light guide distance. Therefore, the diffusion state of the scattered light that is transmitted through the light guide plate 31 in the thickness direction and emitted can be arbitrarily set by selecting the thickness of the light guide plate 31.
[0107]
Further, the front sheet 32 is a flexible transparent sheet having no light diffusibility, and the front sheet 32 is a granular transparent interposed on the front side of the light guide plate 31 in a dotted state therebetween. The gap between the light guide plate 31 is regulated by a plurality of gap members 35 made of a body, and is arranged in parallel with the front surface of the light guide plate 31, and is adhered to the light guide plate 31 via a frame-like spacer 36 at the peripheral edge. Yes.
[0108]
Further, the plurality of transparent electrodes 33 provided on the front surface of the light guide plate 31 are a strip-like electrode formed in parallel with one direction, and the plurality of transparent electrodes 34 provided on the rear surface of the front sheet 32 are guided. This is a belt-like electrode extending in a direction orthogonal to the belt-like electrode 33 on the optical plate 31 side, and the portions where these electrodes 33 and 34 are opposed to each other are the electrodes 34 on the front sheet 32 side due to the bending deformation of the front sheet 32 by a touch operation. Is a touch input unit that comes into contact with the electrode 33 on the light guide plate 31 side and is turned on.
[0109]
Further, in this embodiment, the optical member that emits transmitted light as light having a high luminance distribution on the rear surface of the touch input panel 30 in the direction perpendicular to the front surface of the liquid crystal display element 10 is described above. The same prism sheet 27 as that used in the first embodiment is provided.
[0110]
The prism sheet 27 has a flat surface opposite to the prism forming surface facing the rear surface of the light guide plate 31 of the touch input panel 30, and the length direction of each prism portion 27 a is set to one end surface of the light guide plate 31. The prisms 27a are affixed to the rear surface of the light guide plate 31 with a transparent adhesive (not shown) (which may be a double-sided adhesive sheet) with the prisms 27a facing in the direction of the end faces.
[0111]
The adhesive for attaching the light guide plate 31 and the prism sheet 27 desirably has a refractive index close to the refractive index of both the light guide plate 31 and the prism sheet 27, and an adhesive having such a refractive index is used. For example, the light transmission path from one of the light guide plate 31 and the prism sheet 27 to the other has almost no light refraction at the interface between them, and reflection and scattering at the interface between the light guide plate 31 and the prism sheet 27 occur. There can be almost no linear path.
[0112]
The touch input panel 30 has one end surface of the light guide plate 31, that is, an end surface in a direction facing the vertical side surface of each prism portion 27 a of the prism sheet 27, the main light capturing direction (on the screen). It is arranged on the front side of the liquid crystal display element 10 toward the edge side, and is the same as that used in the first embodiment on the side of the touch input panel 30 so as to face the end face of the light guide plate 31. A light source 28 is arranged.
[0113]
The display operation of the liquid crystal display device will be described. When light from the light source 28 is used, the light from the light source 28 is applied to the light guide plate 31 of the touch input panel 30 as shown by an arrow L1 in FIG. Then, the light is guided through the light guide plate 31 while being scattered repeatedly, emitted to the rear surface of the light guide plate 21 and incident on the liquid crystal display element 10.
[0114]
In this case, the light guided in the light guide plate 31 is scattered in various directions, but the gap between the front surface of the light guide plate 31 and the front sheet 32 disposed on the front surface side becomes an air layer. Therefore, most of the scattered light toward the front surface of the light guide plate 31 is totally reflected at the interface between the front surface of the light guide plate 31 (the front surface of the electrode 33 in the portion where the transparent electrode 33 is formed) and the air layer. Therefore, most of the light guided in the light guide plate 31 is emitted from the entire area to the rear surface of the light guide plate 31.
[0115]
The scattered light emitted to the rear surface of the light guide plate 31 enters the prism sheet 27 and is refracted by each prism portion 27a, and is light in a direction whose angle with respect to the direction perpendicular to the front surface of the liquid crystal display element 10 is reduced, that is, The light emitted in the vertical direction is incident on the liquid crystal display element 10 as light having a high luminance distribution.
[0116]
The light incident on the liquid crystal display element 10 is absorbed by the front polarizing plate 18a by the polarized light component along the absorption axis thereof, and becomes the linearly polarized light of the polarizing plate component along the transmission axis. In the process of transmitting light, the color filters 14R, 14G, and 14bB absorb the light in the absorption wavelength region to color red, green, and blue, change the polarization state according to the birefringence of the liquid crystal layer 17, and Among them, the light of the polarization component along the transmission axis of the rear polarizing plate 18b passes through the rear polarizing plate 18b and becomes image light.
[0117]
The image light is reflected by the reflection plate 19, passes through the liquid crystal display element 10, and exits to the front surface. Then, this light is refracted by the prism sheet 27 in a direction closer to the vertical direction, and enters the touch input panel 20 as light having a luminance distribution in which the luminance of the light emitted in the vertical direction is higher. The light is scattered by the light guide plate 31 and is emitted to the front surface of the display device as diffused light.
[0118]
When using external light, the external light incident on the liquid crystal display device from the front side as indicated by an arrow L2 in FIG. 4 is transmitted through the touch input panel 30 in the thickness direction, and further the prism sheet 27. And enters the liquid crystal display element 10.
[0119]
Also at this time, the external light incident on the touch input panel 30 from the front surface is scattered by the light guide plate 31 of the touch input panel 20 and emitted to the back surface, but the light is refracted by the prism sheet 27, The light emitted in the direction perpendicular to the front surface of the liquid crystal display element 10 is incident on the liquid crystal display element 10 as light having a high luminance distribution.
[0120]
After this, it is the same as when using the light from the light source 28 described above, and the light incident on the liquid crystal display element 10 passes through the front polarizing plate 18a and enters the liquid crystal cell 11, and the liquid crystal cell 11 Of the light emitted to the rear surface, the light of the polarization component along the transmission axis of the rear polarizing plate 18b is transmitted through the rear polarizing plate 18b and becomes image light.
[0121]
The image light is reflected by the reflection plate 19, passes through the liquid crystal display element 10, and exits to the front surface. Then, this light is refracted by the prism sheet 27 in a direction closer to the vertical direction, and enters the touch input panel 20 as light having a luminance distribution in which the luminance of the light emitted in the vertical direction is higher. The light is scattered by the light guide plate 31 and is emitted to the front surface of the display device as diffused light.
[0122]
That is, the liquid crystal display device of this embodiment also performs a reflective display when using outside light and using light from the light source 28. Therefore, the reflection plate 19 provided in the liquid crystal display element 10 is The incident light may be reflected with a high degree of reflection, and therefore a sufficiently bright display can be obtained both when displaying using external light and when using light from the light source 28. .
[0123]
Further, in the liquid crystal display device of this embodiment, the light guide plate 31 of the touch input panel 30 is a scattering plate made of a light diffusing polymer, and the incident light from the front surface and the incident light from the end surface are respectively reflected on the rear surface by the scattering property. Since the incident light from the rear surface is emitted to the front surface, the light transmitted through the touch input panel 30 and emitted to the front surface is scattered by the light guide plate 31 to be diffused light on the front surface of the display device. Therefore, even if the reflecting means is the surface reflecting plate 19, no reflection of the outside scene occurs.
[0124]
As described above, the light scattering property of the light guide plate 31 is such that the diffusion state of the scattered light that is transmitted through the light guide plate 31 in the thickness direction and emitted is sufficiently clear for the image displayed by the liquid crystal display element 10. Therefore, even if the light emitted to the front surface of the liquid crystal display device is diffused, a good quality image with very little blur is observed.
[0125]
Further, in the above-described embodiment, the prism sheet 27 is provided between the rear surface of the touch input panel 30 and the liquid crystal display element 10, so that both the front light and the light from the light source 28 are used. A display with high luminance can be obtained, and there is almost no decrease in display contrast due to surface reflection of external light reflected on the front surface of the touch input panel 30 as indicated by a dashed arrow in FIG.
[0126]
In the liquid crystal display device of the fourth embodiment, as the liquid crystal display element 10, polarizing plates 18a and 18b are disposed on the front side and the rear side of the liquid crystal cell 11, respectively, and reflected behind the rear polarizing plate 18b. Although the liquid crystal display element 10 having the plate 19 is used, the liquid crystal display element 10 may be provided with a reflecting means on the rear surface side (the inner surface or the outer surface of the rear substrate 11b) and the polarizing plate 18a only on the front surface side. .
[0127]
Further, the liquid crystal display element 10 may not include the front polarizing plate 18a, and may have a configuration in which the polarizing plate 18b and the reflection plate 19 are disposed on the rear surface side of the liquid crystal cell 11. In this case, the front sheet of the touch input panel 30 is used. 32 may be the front polarizing plate 18a.
[0128]
In addition, the touch input panels 20 and 30 used in the first to fourth embodiments described above are of a contact type in which touch input portions where electrodes come into contact with each other by a touch operation are arranged in a matrix. The input panel may be of a capacitance type in which touch input units whose capacitance values between electrodes change by a touch operation are arranged in a matrix.
[0129]
Further, in the first to fourth embodiments, the prism sheet 27 is used as an optical member for emitting transmitted light as light having a luminance distribution with high luminance of light emitted in a direction perpendicular to the front surface of the liquid crystal display element 10. Although this optical member is used, for example, a lens sheet in which a plurality of condensing lens portions made of cylindrical lenses are formed in parallel with each other in the width direction, or a surface perpendicular to the plate surface and along a specific direction. Directed scattering that shows scattering with respect to light incident at an incident angle in an angle range tilted by a predetermined angle or more, and hardly shows scattering with respect to light incident at an angle of incidence smaller than the predetermined angle. A scattering sheet having properties may be used.
[0130]
In addition, if the said optical member is between the rear surface of the touch input panel 20, and the reflection means of the liquid crystal display element 10, between the liquid crystal cell 11 and the front side polarizing plate 18a, the liquid crystal cell 11 and the rear side polarizing plate 18b, , Or between the rear polarizing plate 18b and the reflecting means, and when the front luminance of the display is not a problem, the optical member may be omitted.
[0131]
In the liquid crystal display device of each of the above embodiments, a light source 28 that uses a straight fluorescent lamp 28a is used as the light source 28 arranged on the side of the touch input panels 20 and 30. An LED array in which LEDs (light emitting diodes) are aligned may be used.
[0132]
Further, the liquid crystal display element 10 used in each of the above embodiments is of an active matrix type, but the liquid crystal display element 10 may be of a simple matrix type, and the present invention is of a TN type. The liquid crystal display device is not limited to an STN (super twisted nematic) liquid crystal display device in which liquid crystal molecules of a liquid crystal display element are twisted with a twist angle of 180 ° to 270 °, and a color filter using a birefringence effect of liquid crystal. The present invention can also be applied to a birefringence effect type liquid crystal display device that obtains a colored display without using it.
[0133]
【The invention's effect】
  The liquid crystal display device of the present invention is provided on the front side of a liquid crystal display element having a high reflectance reflecting means on the rear side.It has a flat front surface and a rear surface that are inclined to face each other, and an end surface that intersects these two surfaces, and emits incident light from the front surface and incident light from the end surface to the rear surface, respectively, from the rear surface. A light guide plate that emits incident light to the front surface, a transparent front sheet having a uniform thickness that faces the front surface of the light guide plate, and a front surface of the light guide plate and a rear surface of the front sheet that face each other. Consisting of a transparent electrode,Incident light from the front surface and incident light from the end surface are emitted to the rear surface and incident on the liquid crystal display element, and the light emitted from the liquid crystal display element incident on the rear surface is guided to the front surface. Since the touch input panel is arranged and the light source is arranged to face the end face of the touch input panel, it is possible to brighten both the display using the external light and the display using the light from the light source. In addition, while being provided with a touch input panel on the front surface, it is possible to reduce the thickness and reduce the manufacturing cost.
[0134]
  In the liquid crystal display device of the present invention,The touch panel is preferably composed of a light guide plate having a flat front surface and a rear surface that are inclined to face each other, and a transparent front sheet having a uniform thickness. A display is obtained.
[0135]
Further, when a transparent plate is used for the light guide plate of the touch input panel, if the front sheet of the touch input panel has light diffusibility, a specular reflector having excellent reflectivity may be used as the reflecting means. , No reflection of the outside scene.
[0136]
In addition, the light guide plate of the touch input panel has a light scattering property. Due to the scattering property, incident light from the front surface and incident light from the end surface are emitted to the rear surface, and incident light from the rear surface is emitted to the front surface. If the scattering plate is used, the reflection of the outside scene can be prevented.
[0137]
  Furthermore, in the liquid crystal display device according to the present invention, light having a luminance distribution in which transmitted light is emitted in a direction perpendicular to the front surface of the liquid crystal display element between the rear surface of the touch input panel and the reflecting means. If an optical member that emits as is provided, a display with high front luminance can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the invention.
FIG. 2 is a sectional view of a liquid crystal display device according to a second embodiment of the invention.
FIG. 3 is a cross-sectional view of a liquid crystal display device according to a third embodiment of the invention.
FIG. 4 is a sectional view of a liquid crystal display device according to a fourth embodiment of the invention.
[Explanation of symbols]
10 ... Liquid crystal display element
11 ... Liquid crystal cell
12, 13 ... Transparent electrode
12a ... reflective electrode
17 ... Liquid crystal layer
18a: Front polarizing plate
18b: Rear polarizing plate
19 ... Reflector
20 ... Touch input panel
21 ... Light guide plate (transparent plate)
22 ... Surface sheet (diffusion plate)
23, 24 ... Transparent electrodes
27 ... Prism sheet (optical member)
28 ... Light source
30 ... Touch input panel
31 ... Light guide plate (scattering plate)
32 ... surface sheet
33, 34 ... Transparent electrodes

Claims (4)

  1.   On the front side of the liquid crystal display element having a high-reflectance reflecting means on the back side, the flat front and back surfaces that are inclined to face each other, and end faces that intersect these two sides, A light guide plate that emits incident light and incident light from the end surface to the rear surface and emits incident light from the rear surface to the front surface, and a transparent front sheet with a uniform thickness facing the front surface of the light guide plate, It consists of transparent electrodes facing each other provided on the front surface of the light guide plate and the rear surface of the front sheet, respectively, and incident light from the front surface and incident light from the end surface are emitted to the rear surface to the liquid crystal display element. A touch input panel having a light guide property for emitting light emitted from the liquid crystal display element incident on the rear surface to the front surface is disposed, and a light source is disposed to face the end surface of the touch input panel. A liquid crystal display device according to symptoms.
  2.   The liquid crystal display device according to claim 1, wherein a front sheet of the touch input panel has light diffusibility.
  3.   The light guide plate of the touch input panel includes a light scattering plate. Due to the scattering property, the incident light from the front surface and the incident light from the end surface are emitted to the rear surface, and the incident light from the rear surface is emitted to the front surface. The liquid crystal display device according to claim 1, comprising a plate.
  4.   An optical member is provided between the rear surface of the touch input panel and the reflecting means to emit transmitted light as light having a luminance distribution with high luminance of emitted light in a direction perpendicular to the front surface of the liquid crystal display element. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device.
JP26423897A 1997-09-29 1997-09-29 Liquid crystal display Expired - Fee Related JP3849249B2 (en)

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JP3849249B2 true JP3849249B2 (en) 2006-11-22

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