JPH05188359A - Liquid crystal display device and input device - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display device whose contrast is satisfactory, and which is free from an uneven display by using a parallax-obviating member plate as a substrate of the upper side, providing a polarizing plate on only the lower side-substrate side, and using a liquid crystal having a polychromatic pigment as its liquid crystal. CONSTITUTION:When an electric signal is applied to electrodes 4, 5, a major axis of a liquid crystal molecule and a polychromatic pigment in a liquid crystal composition substance layer 8 is arrayed in the same direction as an incident light, and a backlight beam 10 transmits through a liquid crystal display device. When the electrid signal is not applied to the electrodes 4, 5, the major axis of the liquid crystal molecule and the polychromatic pigment is orthogonal to an optical axis of the backlight beam 10, and also, a polarization transmission axis of a polarizing plate 3 makes an array which becomes parallel, therefore, the backlight beam 10 does not transmit through the liquid crystal display device. Therefore, usually a liquid crystal display is executed by using two pieces of polarizing plates, but since providing only one piece of polarizing plate on a lower substrate 7 side is enough, the contrast of the liquid crystal display device is not lowered, and an uneven display is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and an input device using the same, and more particularly to a liquid crystal display device and an input device having no parallax and no uneven contrast.

[0002]

2. Description of the Related Art As one of computer input devices, there is a handwriting input device 30 as shown in FIG. This handwriting input device 3
In the case of 0, normally, the tablet 25 and the liquid crystal display device 20 are integrally laminated. The liquid crystal display device 20 is configured such that the liquid crystal layer 8 is sandwiched between the upper substrate 13 and the lower substrate 7, the tablet 25 is placed on the upper substrate 13, and the upper portion thereof is covered with the cover material 17. In this handwriting input device 30, when the position B displayed in the liquid crystal layer 8 is pointed by the tip of the pen 18, the pointing position C of the pen 18 is changed because of the thickness of the cover material 17 and the upper substrate 13. It is not directly above B, but at a shifted position. That is, a difference occurs between the positions B and C (hereinafter, this is referred to as a parallax shift), and the liquid crystal display position B is displayed.
There is a problem that the position of the pen 18 is not accurately input.

In order to improve this parallax shift, a method of arranging an optical guide (optical fiber) on the surface of the handwriting input device has been proposed in Japanese Patent Laid-Open No. 63-26721. This prior art is one in which a large number of optical fibers are bundled and sliced into a plate shape (fiber plate) with a thickness of about 1 mm and placed on the surface of the handwriting input device. Although the parallax shift caused by the thickness of the cover material (17 in FIG. 6, usually a glass plate) can be eliminated, the parallax shift caused by the thickness of the upper substrate (13 in FIG. 6) inside the liquid crystal display device 20 can be eliminated. There is a problem that it cannot be resolved.

As an example in which a fiber plate, which is one of parallax eliminating members, is used as an upper substrate inside a liquid crystal display device, a lecture paper on applied physics related lectures in 1979, 30p-
B-6, JP-A-51-25099, JP-A-56-
117217, JP-A-58-95378,
There is Japanese Patent Laid-Open No. 2-136826.

These prior arts, as shown in FIG.
A fiber plate 1 as an upper substrate inside the liquid crystal display device.
And use polarizing plates (polarizers) 2 and 3 as fiber plates 1
Above and below the lower substrate 7. Reference numeral 4 is an electrode in the X direction provided on the lower side of the upper substrate 1, reference numeral 5 is an electrode in the Y direction provided on the upper side of the lower substrate 7, and the upper substrate 1 and the lower substrate 7 are Sandwich the spacer 9,
A liquid crystal is sealed between these substrates 1 and 7. The driving means 6 controls the voltage applied to the electrodes 4 and 5 to draw a desired pattern on the liquid crystal layer 8. Reference numeral 10 is a backlight light.

[0006]

If this conventional liquid crystal display device described above is used as a display device of a handwriting input device, the following problems occur. (1) Since the liquid crystal display device is sandwiched between two polarizing plates,
Due to the effect of birefringence due to strain in the fiber plate, a sufficient dark state is not formed, the contrast is lowered, and the screen becomes difficult to see.

(2) Since the fiber plate is sandwiched between two polarizing plates, unevenness occurs in how the strain is applied in the fiber plate, display unevenness occurs, and the screen becomes difficult to see. ..

An object of the present invention is to provide a liquid crystal display device and an input device which prevent a reduction in contrast and display unevenness and have a small parallax shift.

[0009]

The above object is to configure the upper substrate inside the liquid crystal display device with a parallax eliminating member such as a fiber plate or a lens array, and use one polarizing plate only on the lower substrate side. Achieved by adopting a liquid crystal composition material with polarization characteristics (for example, containing a polychromatic dye having anisotropy in absorption of visible light in the major axis direction and the minor axis direction of liquid crystal molecules) To be done.

The above object is also to provide a lens array on the lower substrate inside the liquid crystal display device, a light source for the backlight at the focal position of the lens, and a diffusion material (diffusion sheet) on the surface of the upper substrate.
It is also achieved by disposing g.

[0011]

The pattern displayed on the lower electrode of the upper substrate is directly displayed on the surface of the fiber plate or lens array which is the upper substrate. Since a liquid crystal material having a polarization characteristic is used, the polarizing plate on the upper substrate side, which was necessary in the past, is not required, and the contrast is improved and the display unevenness is eliminated. When this liquid crystal display device is used as a handwriting input device, the parallax shift caused by the thickness of the upper substrate is eliminated. Further, even when the lens array has a characteristic that a pattern is imaged on the lens surface, the same effect as above can be realized.

In the invention using the lens array on the lower substrate, the light transmitted through the lens array becomes parallel light, and what is displayed on the electrodes is directly imaged on the diffusing material on the upper substrate. Therefore, it is possible to realize a liquid crystal display device and a handwriting input device that have no display unevenness, good contrast, and no parallax shift.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view schematically showing a transmissive liquid crystal display device according to a first embodiment of the present invention. 1 is a fiber plate on which an upper substrate is formed, 3 is a polarizing plate, 4 and 5 are electrodes of an XY matrix, 6 is a driving means for applying an electric signal to the electrodes 4 and 5, and 7 is a lower substrate (in this embodiment, glass). A plate is used.), 8 is a layer of a liquid crystal composition substance, which contains, in addition to liquid crystal molecules, a polychromatic dye having anisotropy in absorption of visible light in the major axis direction and the minor axis direction of the molecule. .. Reference numeral 9 is a spacer for holding the liquid crystal composition layer 8, and 10 is incident light from a backlight. The liquid crystal is aligned parallel to the substrate surface by rubbing treatment, and the polarization transmission axis of the polarizing plate is set parallel to the rubbing direction.

Now, when an electric signal is applied to the electrodes 4 and 5,
The long axes of the liquid crystal molecules and the polychromatic dye in the liquid crystal composition layer 8 are aligned in the same direction as the incident light, and the backlight light 10 passes through the liquid crystal display device. When an electric signal is not applied to the upper electrodes 4 and 5, the long axes of the liquid crystal molecules and the polychromatic dye are orthogonal to the optical axis of the backlight light, and the polarization transmission axis of the polarizing plate 3 is parallel. Therefore, the backlight 10 does not pass through the liquid crystal display device.

For this reason, the conventional liquid crystal display using two polarizing plates is provided on the lower substrate 7 side in this embodiment.
Since it suffices to provide only one sheet, the contrast of the liquid crystal display device does not decrease and there is no display unevenness. Moreover, the handwriting input device using this liquid crystal display device does not cause parallax displacement. The example of using the polarizing plate 3 on the lower substrate 7 side has been described above.
It can be easily realized even without the polarizing plate 3.

FIG. 2 is a side sectional view schematically showing a reflective liquid crystal display device according to a second embodiment of the present invention. Since the basic structure is almost the same as that of the first embodiment shown in FIG. 1, corresponding parts are designated by the same reference numerals. The difference from the first embodiment is that the polarizing plate 3 and the backlight 10 are absent, and the reflector 11
Is provided. In this case, the driving method of the liquid crystal display device is a TN (twisted nematic) type, and the twist angle is 9
0 degree or more. As a result, the present embodiment has the same effect as that of the first embodiment, and further has the effect of eliminating the double image peculiar to the reflective liquid crystal display device. in this case,
When no electric signal is applied, the liquid crystal has a twisted orientation, and the liquid crystal molecules and the polychromatic dye have various orientations in the plane of the substrate to absorb light and become dark. On the other hand, when an electric signal is applied, the rising direction of the liquid crystal molecules is aligned with the long axis direction of the polychromatic molecules, and the liquid crystal molecules are in a bright state. Such a principle has already been shown by White and Taylor (Journal of Applied Physics, Vol. 45, page 4718 (1974)).

Although the case where there is no polarizing plate has been described above, the polarizing plate may be used on the lower substrate side if the liquid crystal is not twisted. In this case as well, the above-mentioned effect is obtained.

FIG. 3 is a side sectional view schematically showing a liquid crystal display device according to a third embodiment of the present invention. In this embodiment, a lens array is used as an upper substrate. FIG. 4 shows FIG.
It is an enlarged view of the A portion of FIG. Since the basic structure is almost the same as that of the first embodiment shown in FIG. 1, corresponding parts are designated by the same reference numerals. The difference from the first embodiment of FIG. 1 is that a lens array 12 is used as an upper substrate, in which what is displayed on the electrode forms an image on the surface of the lens. With this configuration, what was displayed at the position D in the liquid crystal 8 is re-displayed at the position E by the lens array, and there is no parallax displacement,
A display device having good contrast and no display unevenness can be realized.

FIG. 5 is a side sectional view schematically showing a liquid crystal display device according to a fourth embodiment of the present invention. In this embodiment, a lens array is used for the lower substrate. The difference from the first embodiment shown in FIG. 1 is that the upper substrate 13, the lens array 14 constituting the lower substrate, and the back position arranged at the focal position of the lens array (f in FIG. 5 is the focal length of the lens array). The light source 15 and the diffusing material 16 disposed on the upper substrate 13.

With the above structure, the electrodes 4, 5
Since the image displayed on the screen is imaged on the diffusing material 16, the first
The same effect as the embodiment can be obtained.

FIG. 8 shows an example of an application system using the liquid crystal display device of the present invention. The handwriting input device 30 is configured by integrally stacking the tablet 25 and the liquid crystal display device 20 having the above-described configuration. The coordinates input by handwriting with the pen 18 are sent from the tablet 25 to the computer 35,
The data processed by the computer 35 is sent to the liquid crystal display device 20 and displayed at the position designated by the pen 18 or at an arbitrary position. In the conventional system, what is input by the pen at point C in FIG. 6 is input at point F in FIG. 8 by using the liquid crystal display device of this embodiment. That is, there is no parallax shift.

Note that in FIG. 8, data transmission between the tablet 25 and the computer 35 and between the computer 35 and the liquid crystal display device 20 may be performed using a signal line, or may be performed using a wireless connection. It goes without saying that you may do so. Further, when the tablet has a large thickness, as shown in FIG. 9, if the configuration of the handwriting input device 30 is reversed and the tablet 25 is arranged below the liquid crystal display device 20, the parallax displacement due to the thickness of the tablet is eliminated. Further, in the device 40 in FIG. 10, the electrodes 4, 5 in the liquid crystal display device 20, the liquid crystal composition layer 8 and the coordinate detection sensor of the tablet are arranged in the same plane. Even with this configuration, the parallax shift is eliminated.

[0023]

According to the present invention, the contrast is good,
A liquid crystal display device having no display unevenness, and particularly a reflection type liquid crystal display device without double reflection can be configured. Further, the handwriting input device in which the tablet and the liquid crystal display device of the present invention are integrally laminated has no parallax shift.

[Brief description of drawings]

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

FIG. 2 is a side sectional view schematically showing a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a side sectional view schematically showing a liquid crystal display device according to a third embodiment of the present invention.

FIG. 4 is an enlarged view of a portion A in FIG.

FIG. 5 is a side sectional view schematically showing a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a conventional handwriting input device.

FIG. 7 is a side sectional view schematically showing a conventional liquid crystal display device.

FIG. 8 is a configuration diagram of an application system using a liquid crystal display device.

FIG. 9 is a configuration diagram of another handwriting input device using a liquid crystal display device.

FIG. 10 is a configuration diagram of a device in which a display element of a liquid crystal display device and a coordinate detection sensor of a tablet are arranged on the same plane.

[Explanation of symbols]

1 ... Fiber plate, 2 ... Polarizing plate, 3 ... Polarizing plate, 4
... electrodes, 5 ... electrodes, 6 ... driving means, 7 ... lower substrate, 8 ...
Liquid crystal composition layer, 10 ... Backlight light, 11 ... Reflector, 12 ... Lens array, 13 ... Upper substrate, 14 ... Lens array, 15 ... Light source, 16 ... Diffusing material, 17 ... Cover
Material, 18 ... Pen, 20 ... Liquid crystal display device, 25 ... Tablet, 30 ... Handwriting input device, 35 ... Calculator, 40 ... Device in which the display element of the liquid crystal display device and the coordinate detection sensor of the tablet are arranged on the same plane.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Kondo 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (13)

[Claims] 1. A liquid crystal composition material layer having a positive dielectric anisotropy and a chiral material is sandwiched between two substrates, and
In a liquid crystal display device in which XY matrix electrodes are provided on these substrates, a parallax eliminating member plate is used as the upper substrate, a polarizing plate is provided only on the lower substrate side, and a liquid crystal having a polychromatic dye is used as the liquid crystal. A liquid crystal display device characterized by the above. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal composition substance has a twisted molecular orientation. 3. The liquid crystal display device according to claim 2, wherein the twist angle of the molecular orientation of the liquid crystal is 90 degrees or more. 4. The liquid crystal display device according to claim 1, wherein the parallax eliminating member plate is a lens array, and a diffusing material is provided thereon. 5. The liquid crystal display device according to claim 1, wherein the parallax eliminating member plate is an integrated plate of minute light guide paths. 6. The liquid crystal display device according to claim 1, wherein a lens array is used as the lower substrate, and a diffusion material is provided on the upper substrate. 7. The liquid crystal according to claim 1, wherein the coordinate detecting means, the calculating means for processing the detected values of the coordinates designated by the coordinate designating means, and the processing data are displayed. An input device comprising a display device. 8. The input device according to claim 7, wherein the liquid crystal display device and the coordinate detecting means are integrally laminated. 9. In a liquid crystal display device in which a layer of a liquid crystal composition substance is sandwiched between two substrates, a liquid crystal having a polychromatic dye is used as the liquid crystal, and a polarizing plate is provided only on the lower substrate side,
A liquid crystal display device using a parallax eliminating member plate as an upper substrate. 10. A liquid crystal display device in which a layer of a liquid crystal composition material is sandwiched between two substrates, a fiber plate is used as an upper substrate, a reflector is provided below a lower substrate, and a polychromatic dye is included as liquid crystal. A liquid crystal display device using liquid crystal and not using a polarizing plate. 11. A liquid crystal display device in which a layer of a liquid crystal composition material is sandwiched between two substrates, and XY matrix electrodes are provided on these substrates, and a lens array that directly displays the pattern appearing on the electrodes as an upper substrate on the surface. And a liquid crystal having a polychromatic pigment is used as the liquid crystal, and a backlight for illuminating the liquid crystal pattern from behind is provided without using a polarizing plate. 12. A liquid crystal display device in which a layer of a liquid crystal composition material is sandwiched between two substrates, a lens array is used as a lower substrate, and a polarizing plate is provided only on the lower side of the lower substrate to have a polarization characteristic as a liquid crystal. Using a liquid crystal, the backlight source is placed at the focal position of the lens array on the back side of the lower substrate,
A liquid crystal display device, wherein an upper side of an upper substrate is covered with a diffusion sheet. 13. A hand characterized in that the liquid crystal display device according to any one of claims 9 to 11 and a tablet for detecting a coordinate position pointed by an operator by a coordinate pointing means are integrally laminated. Book input device.