JPH09230327A - Liquid crystal display - Google Patents

Abstract

(57) Abstract: Even if a pair of transparent substrates are misaligned when they are bonded to each other, the opening area of each pixel can be made uniform, thereby making it possible to make the color balance of the displayed image uniform. , So that a color image having a desired hue can be obtained. An upper glass substrate in a liquid crystal display device for displaying a color image by diffracting light from a light source unit with a hologram at different diffraction angles for each wavelength and condensing the light on pixels corresponding to each color of a liquid crystal cell. Each of the two sides of the opening 18a of the black matrix 18 formed on the side and the corresponding side of the wiring line 16 formed on the lower glass substrate corresponding to the side are defined by a pair of glass substrates. It is set to be equal to or larger than the positioning accuracy of. Therefore, even if a position is generated when the glass substrates are opposed to each other, the opening 15a does not overlap the wiring line 13 and the opening area of each pixel can be made uniform, whereby the color balance of the image displayed. Can be made uniform.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art In a liquid crystal display device, as shown in FIG.
The parallel light from the light source unit 1 is diffracted by the hologram 2 at different diffraction angles for each wavelength of red (R), green (G), and blue (B), and is focused on the pixels of the liquid crystal display panel 3 corresponding to each color. By doing so, there is a structure in which a color image is displayed. In this case, the light source unit 1 has a structure in which the light source 5 is arranged at the focal position of the reflector 4 formed of a paraboloid, and the light generated from the light source 5 is reflected by the reflector 4 as light parallel to the optical axis 6. There is. The hologram 2 diffracts any wavelength of R, G, and B with one diffraction grating, and diffracts at different diffraction angles depending on each wavelength, and the parallel light from the light source unit 1 has a predetermined angle (for example, 40 °
Is arranged so as to be incident at an angle of. The liquid crystal display panel 3 includes a liquid crystal cell (liquid crystal element) 7, an incident side polarizing plate 8 provided on the incident side of the liquid crystal cell 7, and an emitting side polarizing plate 9 provided on the emitting side of the liquid crystal cell 7. Has become. As shown in FIG. 4, the liquid crystal cell 7 encloses a liquid crystal 12 between a pair of transparent glass substrates 10 and 11, and
A drive voltage is applied to the transparent electrodes 13 and 14 formed on the facing surfaces of the glass substrates 10 and 11, respectively, to control the light transmission state.

The detailed structure of the liquid crystal cell 7 is as follows. That is, a pair of glass substrates 1 facing each other
IT having a thin film transistor (TFT) 15 is provided on the facing surface of one (lower) glass substrate 10 of 0 and 11.
Pixel electrodes 13 made of a transparent conductive material such as O are arrayed and formed in a dot matrix shape, and wiring lines 16 such as gates, drains / sources are formed in a grid shape so as to surround each pixel electrode 13, An alignment film 17 is formed so as to cover the pixel electrodes 13 and the wiring lines 16. A common electrode 14 made of a transparent conductive material such as ITO is formed on the opposite surface of the other (upper) glass substrate 11, and the common electrode 14 is also formed.
A black matrix 18 is formed in a lattice pattern on the substrate, and an alignment film 19 is formed so as to cover the common electrode 14 and the black matrix 18. Then, while the openings 18a of the black matrix 18 and the pixel electrodes 13 are opposed to each other, the pair of glass substrates 10 and 11 are bonded together via a sealant (not shown), and then the pair of glass substrates is bonded. The liquid crystal 12 is enclosed in the region surrounded by the substrates 10 and 11 and the sealing material to form the liquid crystal cell 7, and the region where the opening 18a and the pixel electrode 13 face each other forms each pixel. The wiring lines 16 are gate wirings in the vertical direction and drain / source wirings in the horizontal direction. The vertical and horizontal wiring lines 16 intersect without contacting each other.

[0004]

However, in such a liquid crystal display device, when the parallel light from the light source unit 1 is diffracted by the hologram 2 for each wavelength and condensed on the pixel corresponding to each color of the liquid crystal cell 7. Since the light of each wavelength to be condensed has a width (for example, the light of R wavelength has a certain width), the wavelength of the light to be condensed is slightly different between the central portion and the peripheral portion of each pixel. . Therefore, the opening 18 of each pixel
If the opening 18a overlaps the wiring line 14 due to the displacement of a, and the opening area differs from pixel to pixel, the color balance (color) of the displayed image changes due to the change in the opening area. There is a problem that a color image of a desired color cannot be obtained. In order to overcome such a problem, when the pair of glass substrates 10 and 11 are bonded together, it is sufficient to prevent the positional deviation, but there is a limit to the positioning accuracy, and in reality, there is a limit. ± 8.5
A displacement of about μm occurs.

An object of the present invention is to make the aperture area of each pixel uniform even if a positional deviation occurs when a pair of transparent substrates are bonded together, thereby making it possible to make the color balance of the displayed image uniform. So that a color image having a desired hue can be obtained.

[0006]

According to the first aspect of the present invention,
In a liquid crystal display device that displays a color image by diffracting the light from the light source part at different diffraction angles for each wavelength by a hologram and condensing it on the pixel corresponding to each color of the liquid crystal element, the liquid crystal element encapsulates the liquid crystal. Among the pair of transparent substrates, pixel electrodes having thin film transistors are formed in an array on the opposing surface of one transparent substrate, and wiring lines are formed so as to surround these pixel electrodes.
A common electrode and a black matrix are formed on the opposing surface of the other transparent substrate, and a region where each opening of the black matrix and each pixel electrode face each other forms the pixel, and each side of the opening corresponds to each side. Since each planar distance between each side of the wiring line is set to be equal to or larger than the alignment accuracy of the pair of transparent substrates, even when the pair of transparent substrates face each other, a position occurs.
The openings do not overlap the wiring line, and the opening area of each pixel can be made uniform, which makes it possible to make the color balance of the displayed image uniform and to obtain a color image of a desired hue. Can be obtained.

According to the second aspect of the present invention, the hologram and the liquid crystal element are aligned so that the light of each wavelength diffracted by the hologram is focused on the opening of the black matrix. When the hologram is diffracted at different diffraction angles for each wavelength and condensed on the pixel corresponding to each color of the liquid crystal element, even if the wavelength of the condensed light is slightly different between the central part and the peripheral part of each pixel, Since the aperture area of each pixel is uniform, the light of each wavelength diffracted by the hologram can be made to enter each pixel in a substantially constant state, so that the hue of the displayed image does not change and the color The balance can be made uniform, and a color image having a desired hue can be obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the liquid crystal display device of the present invention will be described below with reference to FIGS. 1 and 2. The same parts as those of the conventional example shown in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted. In this liquid crystal display device, collimated light from the light source unit 1 is diffracted by the hologram 2 at different diffraction angles for each wavelength of R, G, and B, and is collected in pixels corresponding to each color of the liquid crystal display panel 3 as in the conventional case. By illuminating, a color image is displayed. The liquid crystal cell 7 of the liquid crystal display panel 3 is similar to the conventional example in that a liquid crystal 12 is sealed between a pair of upper and lower glass substrates 10 and 11, and a pixel electrode 13 is provided on the opposite surface of the lower glass substrate 10. The TFT 12 and the wiring line 16 are formed so as to be covered with the alignment film 17, and the common electrode 14 and the black matrix 18 are formed on the upper glass substrate 11.
Are formed so as to be covered with the alignment film 19. And FIG.
As shown in FIG. 3, the sides of the openings 18a of the black matrix 18 formed on the upper glass substrate 11 and the corresponding sides of the wiring lines 16 formed on the lower glass substrate 10 are two-dimensional. Each space S is set to be equal to or larger than the alignment accuracy (± 8.5 μm) of the pair of glass substrates 10 and 11, respectively. Further, among the sides of the opening 18a, the lower side corresponding to the TFT 12 is T
It is separated from the upper side of the FT 12 by a length equal to or more than the alignment accuracy (± 8.5 μm) of the pair of glass substrates 10 and 11. The wiring line 16 is formed with the same width as the conventional example.

By the way, the hologram 2 is one which diffracts any wavelength of R, G and B by one diffraction grating and diffracts at different diffraction angles according to each wavelength, as in the conventional example. The parallel light from the portion 1 is incident at a predetermined angle (for example, an angle of about 40 °), and the incident light is diffracted to be incident on the pixels of the liquid crystal cell 7 corresponding to the respective colors. That is, this hologram 2
Of the liquid crystal cell 7 has a structure in which unit holograms corresponding to unit pixels each having three pixels corresponding to three colors of R, G, and B as one set are periodically arranged. The hologram 2 and the liquid crystal cell 7 are arranged such that the light of each wavelength diffracted by the hologram 2 has the opening 1 of the black matrix 18.
It is aligned so that the light is focused on 8a. That is, the principal ray of each of the R, G, and B wavelength components diffracted by the hologram 2 (for example, the light of a specific R wavelength among the R wavelength components) is at the center of the pixel corresponding to each color of the liquid crystal cell 7. The hologram 2 is arranged with respect to the liquid crystal cell 7 so as to focus light on the liquid crystal cell 7.

In the liquid crystal cell 7 of such a liquid crystal display device, each side of the opening 18a of the black matrix 18 formed in the upper glass substrate 11 and the wiring line 16 formed in the lower glass substrate 10 are formed. The planar spacing S from each corresponding side is set to be equal to or greater than the alignment accuracy (± 8.5 μm) of the pair of glass substrates 10 and 11, and the lower side of the opening 18a. Is TF
Since the alignment accuracy (± 8.5 μm) of the pair of glass substrates 10 and 11 is equal to or greater than the upper side of T12, the pixel electrode 1 of the lower glass substrate 10 is separated.
3 and the black matrix 18 of the upper glass substrate 11
When a pair of upper and lower glass substrates 10 and 11 are attached to each other with the opening 18a of the glass substrate 1 facing each other,
Even if 0 and 11 are relatively misaligned, the misalignment can be suppressed within the range of the alignment accuracy of about ± 8.5 μm. Therefore, the opening 1 of the upper glass substrate 11 is opened.
8a is the wiring line 16 of the lower glass substrate 10 and the TFT
It is possible to make the opening area of each pixel uniform without overlapping with 12.

That is, when the relative positional displacement between the pair of glass substrates 10 and 11 is only in the left-right direction, FIG.
As shown in (a) and FIG. 2 (b), even if the opening 18a shifts in the left-right direction, the opening 18a does not overlap the wiring line 16 for the gate, and the pair of glass substrates 10 and 11 does not overlap each other. When the relative displacement is only in the front-rear direction, as shown in FIGS. 2 (c) and 2 (d), even if the opening 18a is displaced in the front-rear direction, the opening 18a is used for the drain / source. The wiring lines 16 and the TFT 12 do not overlap with each other, and further, the pair of glass substrates 10 and 11 are provided.
Even if the relative displacement of the
As shown in (a) to FIG. 2 (d), even if the opening 18a shifts in the front-rear direction and the left-right direction, the opening 18a does not overlap the wiring lines 16 and the TFTs 12. Therefore, the opening area of each pixel becomes uniform.

As described above, in the liquid crystal display device using the liquid crystal cell 7, the parallel light from the light source unit 1 is diffracted by the hologram 2 at different diffraction angles for each wavelength to form a pixel corresponding to each color of the liquid crystal cell 7. When the light is focused, the wavelength of the focused light is slightly different between the central portion and the peripheral portion of each pixel because there is a width in the focused light. Since the light beams of the respective wavelengths diffracted by the light beams are aligned so as to be focused on the opening portion 18a of the black matrix 18, the opening portion 18a is displaced due to the relative displacement of the pair of glass substrates 10 and 11. However, since the aperture area of each pixel of the liquid crystal cell 7 is uniform as described above, the light of each wavelength diffracted by the hologram 2 is allowed to enter the aperture 18a of each pixel in a substantially constant state. Can, Therefore does not change the color of an image to be displayed, it is possible to equalize the color balance, it is possible to obtain a color image of a desired hue.

In the above embodiment, the wiring line 16
Is formed with the same width as the conventional example, but not limited to this,
It is desirable to form the width of the wiring line 16 to the minimum width that can be manufactured. By thus narrowing the width of the wiring line 16 as much as possible, the opening 18a of the black matrix 18 can be formed large, the light utilization efficiency can be increased, and a clear and bright image can be obtained. . Further, in the above-described embodiment, the case where the color image displayed on the liquid crystal display panel 3 is directly observed has been described. However, a projection lens is arranged on the exit side of the liquid crystal display panel 3, and the projection lens is used for the liquid crystal display panel 3. It can also be applied to a liquid crystal projector that observes a displayed color image by enlarging and projecting it on a screen.

[0014]

As described above, according to the first aspect of the present invention, a pair of transparent substrates are provided so as to have a plane interval between each side of the opening and each side of the wiring line corresponding thereto. Since it is set to be equal to or larger than the alignment accuracy of, even if a position occurs when the pair of transparent substrates are opposed to each other, the opening does not overlap the wiring line, and the opening area of each pixel is made uniform. As a result, it is possible to make the color balance of the displayed image uniform, and to obtain a color image having a desired hue. Further, according to the second aspect of the invention, the hologram and the liquid crystal element are aligned so that the light of each wavelength diffracted by the hologram is focused on the opening of the black matrix. When the light is diffracted at different diffraction angles depending on the wavelength to be condensed on the pixel corresponding to each color of the liquid crystal element, even if the wavelength of the condensed light is slightly different between the central part and the peripheral part of each pixel, Since the aperture area of the pixel is uniform, the light of each wavelength diffracted by the hologram can be made to enter each pixel in a substantially constant state, so that the hue of the displayed image does not change and the color balance is not changed. Can be made uniform, and a color image having a desired hue can be obtained.

[Brief description of drawings]

FIG. 1 is an enlarged plan view of an essential part of a liquid crystal cell used in a liquid crystal display device of the present invention.

2A and 2B show a positional deviation state when a pair of glass substrates of the liquid crystal cell of FIG. 1 are bonded together, FIG. 2A is an enlarged plan view of an essential part in a state where an upper glass substrate is leftwardly displaced; ) Is an enlarged plan view of an essential part in a state where the upper glass substrate is displaced in the right direction, (c) is an enlarged plan view of an essential part in a state in which the upper glass substrate is displaced in the front direction, and (d) is an upper part. The principal part enlarged plan view in the state where the glass substrate was displaced to the back direction.

FIG. 3 is an overall configuration diagram showing an example of a liquid crystal display device.

FIG. 4 is an enlarged cross-sectional view of a main part of the liquid crystal cell shown in FIG.

[Explanation of symbols]

 1 Light Source Section 2 Hologram 7 Liquid Crystal Cell 10, 11 Glass Substrate 12 Liquid Crystal 13 Pixel Electrode 14 Common Electrode 15 TFT 16 Wiring Line 18 Black Matrix 18a Opening

Claims (2)

[Claims] 1. A liquid crystal display device for displaying a color image by diffracting light from a light source part at a diffraction angle different for each wavelength by a hologram and condensing it on a pixel corresponding to each color of a liquid crystal element. The element has a pair of transparent substrates in which liquid crystal is sealed, pixel electrodes having thin film transistors are arranged in an array on the opposing surface of one transparent substrate, and a wiring line is formed surrounding each pixel electrode. A common electrode and a black matrix are formed on the opposite surface of the other transparent substrate, and a region where the opening of the black matrix and the pixel electrode face each other forms the pixel,
Moreover, each planar distance between each side of the opening and each corresponding side of the wiring line is set to be equal to or larger than the alignment accuracy of the pair of transparent substrates. Liquid crystal display device. 2. The hologram and the liquid crystal element are aligned so that light of each wavelength diffracted by the hologram is focused on the opening of the black matrix. Liquid crystal display device.