JPH1062798A - Diffraction type liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently utilize the refractive index anisotropy of a liquid crystal material by providing the display panel with striped electrodes consisting of signal electrodes formed by connecting every other electrodes among plural parallel arranged linear electrodes to each other and reference electrodes formed by connecting the electrodes exclusive of these signal electrodes with each other. SOLUTION: Data lines 20 and control lines 21 are connected by interlayer insulating films at the intersection points and thin-film transistors 22 are arranged at each of the respective pixels. The plural transparent electrodes extending in a longitudinal direction are arranged at a pitch of order to induce diffraction to visible light within the respective pixels. Every other pieces of such transparent electrodes are connected, by which the signal electrodes 23 are constituted. The reference electrode lines 25 formed in correspondence to the respective pixel arrays arranged in a transverse direction are connected to the electrodes which do not constitute the signal electrodes 23 among the linear transparent electrodes, by which the reference electrodes 26 having the plural transparent electrodes connected to the reference electrode lines 25 are constituted. Oriented films 27 covering the signal electrodes 23 and the reference electrodes 26 are formed and a liquid crystal layer 40 is held between the oriented films 27 and 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display panel that controls transmission and blocking of light by utilizing diffraction of light.

[0002]

2. Description of the Related Art The structure and principle of a liquid crystal display panel utilizing a diffraction phenomenon will be described with reference to FIGS.

FIG. 8A is a partial sectional view of a diffraction type liquid crystal display panel. Two transparent substrates 50 and 53 are arranged facing each other. On the opposing surface of the transparent substrate 50, a plurality of elongate transparent electrodes 5 extending in a direction perpendicular to the plane of the drawing are shown.
1 is formed in a striped pattern. For example, the transparent electrode 51
Is about 5 μm, and the width of the gap is about 15 μm. An alignment film 52 is formed on the opposing surface of the transparent substrate 50 so as to cover the transparent electrode 51.

The transparent electrode 5 is also provided on the opposite surface of the transparent substrate 53.
A transparent electrode 54 similar to 1 is formed. Transparent electrode 5
Numeral 4 is configured to be located substantially at the center of the gap between the transparent electrodes 51 on the transparent substrate 50 side. A 5 μm-wide band-shaped region B in which a transparent electrode is formed only on one of the transparent substrates 50 and 53 and a 5 μm-wide band-shaped region A in which no transparent electrode is formed on any of the substrates are shown in FIG. Are alternately arranged in the horizontal direction. The arrangement pitch of these two kinds of band-shaped regions is about 10 μm, which is a pitch small enough to diffract visible light. An alignment film 55 is formed on the opposite surface of the transparent substrate 53 so as to cover the transparent electrode 54.

A liquid crystal layer 56 containing liquid crystal molecules having a positive dielectric anisotropy is sandwiched between the alignment films 52 and 55. The alignment films 52 and 55 are subjected to an alignment process in a direction parallel to the longitudinal direction of the transparent electrode 51. Liquid crystal layer 5
Small circles 57 described in 6 schematically show the arrangement state of the liquid crystal molecules. The liquid crystal molecules are arranged homogeneously, and the major axis direction is parallel to the longitudinal direction of the transparent electrode 51.

FIG. 8B shows an arrangement state of liquid crystal molecules when a voltage is applied between the transparent electrodes 51 and 54. In a region A where neither of the transparent electrodes 51 and 54 is formed, an electric field is generated in a direction oblique to the substrate surface. The liquid crystal molecules are tilted so that their major axes are parallel to the electric field, and their major axes are oblique to the substrate surface, as schematically shown by a rectangle 57a.

Further, in the region B where one of the transparent electrodes 51 and 54 is formed, an electric field of sufficient strength is not generated, so that the liquid crystal molecules, as schematically shown by a small circle 57b, The arrangement state parallel to 51 is maintained.

When passing through the region B of the liquid crystal layer 56, the linearly polarized light having a polarization component parallel to the longitudinal direction of the transparent electrode 51 feels the refractive index of the liquid crystal molecules with respect to the extraordinary ray, and the region A
Feels the refractive index for ordinary light when passing through.

When passing through the region B of the liquid crystal layer 56, the linearly polarized light having a polarization component perpendicular to the longitudinal direction of the transparent electrode 51 feels the refractive index of the liquid crystal molecules with respect to ordinary light. In addition, the user feels an intermediate refractive index between the refractive index for the extraordinary ray and the refractive index for the extraordinary ray. Therefore, the transparent electrode 5
A diffraction phenomenon occurs for any linearly polarized light having a polarization component parallel and perpendicular to one longitudinal direction.

FIG. 9 is a schematic view of a projection type display device using one diffraction type liquid crystal display panel. The collimated light is emitted from the light source 80 and enters the diffraction type liquid crystal display panel 81. Light transmitted through the liquid crystal display panel 81 is condensed by the condenser lens 82 and enters the light shielding plate 84. Light shield plate 84
The through hole 85 is provided at a position P ₀ of zero-order diffracted light transmitted through the liquid crystal display panel 81 is collected. Higher order diffracted light that is higher than the first order diffracted light is shielded by the light shielding plate 84.
For example primary and second order diffracted light is irradiated to the position P ₁ and P ₂ on the respective light shielding plates.

The light passing through the through-hole 85 is transmitted to the projection lens 8.
3 is projected on the screen 86. The intensity of diffraction can be controlled by changing the voltage between the transparent electrodes 51 and 54 shown in FIG. 8A, and the amount of light projected on the screen 86 can be adjusted.

[0012]

In order to obtain high contrast in a projection type liquid crystal display device utilizing diffracted light, it is necessary to efficiently diffract incident light.

In the case of the diffraction type liquid crystal display panel shown in FIG.
In the state of FIG. 8B, the refractive index anisotropy Δn of the liquid crystal material can be sufficiently used for linearly polarized light having a polarization component parallel to the longitudinal direction of the transparent electrode 51.
On the other hand, for linearly polarized light having only a polarization component perpendicular to the longitudinal direction of the transparent electrode 51, the refractive index anisotropy Δn of the liquid crystal material cannot be sufficiently utilized. For this reason, the diffraction intensity becomes weak, and it becomes difficult to obtain high contrast.

An object of the present invention is to provide a liquid crystal display panel capable of fully utilizing the refractive index anisotropy of a liquid crystal material.

[0015]

According to one aspect of the present invention, at least one of a pair of transparent substrates is formed on a pair of transparent substrates, and at least one of the pair of substrates is formed on a facing surface of at least one of the pair of substrates. Of a plurality of linear electrodes arranged in parallel at a pitch that causes a diffraction phenomenon with respect to light, a signal electrode in which every other electrode is connected to one another and an electrode other than the signal electrode are mutually connected. A striped electrode composed of a connected reference electrode, an alignment film formed on at least one of the pair of substrates, and a liquid crystal layer sandwiched between the pair of substrates. A liquid crystal display panel having the same is provided.

When a voltage is applied between the signal electrode and the reference electrode, an electric field having a component parallel to the substrate surface is generated in the liquid crystal layer corresponding to the gap between the linear electrodes. Under the influence of this electric field, many liquid crystal molecules rotate along a plane parallel to the substrate surface. No strong electric field is generated in the liquid crystal layer corresponding to the linear electrode. The liquid crystal molecules in this portion substantially maintain the initial alignment.

In the region corresponding to the linear electrode and the region corresponding to the gap in the liquid crystal layer, the arrangement of the liquid crystal molecules is different from each other, so that the refractive index periodically changes in the substrate plane. Therefore, the liquid crystal layer functions as a diffraction grating.

When the liquid crystal molecules in the liquid crystal layer have a positive dielectric anisotropy, the angle between the longitudinal direction of the linear electrode and the alignment direction given to the alignment film is less than 0 °. It is preferable that the angle be as large as 45 ° or less.

By setting the angle between the longitudinal direction of the linear electrode and the orientation direction to be larger than 0 °, the direction of rotation of the liquid crystal molecules when a voltage is applied can be determined. By setting the angle to 45 ° or less, the difference in the refractive index between the region corresponding to the linear electrode of the liquid crystal layer and the region corresponding to the gap can be sufficiently increased.

When the liquid crystal molecules in the liquid crystal layer have negative dielectric anisotropy, the angle between the longitudinal direction of the linear electrode and the alignment direction given to the alignment film is 45 ° or more. And less than 90 °.

By making the angle between the longitudinal direction of the linear electrode and the orientation direction smaller than 90 °, the direction of rotation of the liquid crystal molecules when applying a voltage can be determined. By setting the angle to 45 ° or more, the difference in the refractive index between the region corresponding to the linear electrode and the region corresponding to the gap in the liquid crystal layer can be sufficiently increased.

[0022]

FIG. 1A is a plan view of one substrate of a liquid crystal display panel according to an embodiment of the present invention. FIG.
The plurality of data lines 20 extending in the vertical direction and the plurality of control lines 21 extending in the horizontal direction of FIG. The data line 20 and the control line 21 are mutually insulated by an interlayer insulating film at the intersection. An area surrounded by two data lines 20 and two control lines 21 adjacent to each other is one pixel. A thin film transistor (TFT) 22 is arranged for each pixel.

In each pixel, a plurality of linear transparent electrodes extending in the vertical direction in the figure are arranged at a pitch on the order of causing a diffraction phenomenon with respect to visible light. The signal electrodes 23 are configured by connecting every other one of the plurality of transparent electrodes.
Hereinafter, the longitudinal direction of the linear transparent electrode is referred to as “slit direction of the diffraction grating”.

The gate electrode 22 G of the TFT 22 is connected to the corresponding control line 21. The source region 22S is connected to a signal electrode 23 formed on an interlayer insulating film covering the TFT 22 via a contact hole 24S. The drain region 22D is connected to the corresponding data line 20 via a contact hole 24D formed in the interlayer insulating film.

One reference electrode line 25 is formed corresponding to each pixel column arranged in the horizontal direction in the drawing. Reference electrode wire 2
Reference numeral 5 is connected to an electrode which does not constitute the signal electrode 23 among the linear transparent electrodes formed in the pixel. Reference electrode 2 having a plurality of transparent electrodes connected to reference electrode line 25
6 are configured.

The other substrate of the liquid crystal display panel is also shown in FIG.
It has the same configuration as the substrate of (A). The signal electrodes and the reference electrodes of the two substrates are disposed so as to face each other.

FIG. 1B is a dashed line B1 of FIG.
1 shows a cross-sectional view of the liquid crystal display panel at -B1. The transparent substrates 1 and 10 are arranged facing each other. On the opposing surface of the transparent substrate 1, a comb-shaped signal electrode 23 and a reference electrode 26 made of indium tin oxide (ITO) are formed. An alignment film 27 is formed to cover the signal electrode 23 and the reference electrode 26.

Similarly, a signal electrode 33 and a reference electrode 36 are formed on the opposing surface of the transparent substrate 10. The signal electrode 33 is positioned so as to face the signal electrode 23, and the reference electrode 36 is positioned so as to face the reference electrode 26. An alignment film 37 is formed so as to cover the signal electrode 33 and the reference electrode 36. A liquid crystal layer 40 containing liquid crystal molecules having a positive refractive index anisotropy is sandwiched between the alignment films 27 and 37. The alignment directions of the alignment films 27 and 37 are substantially parallel to the slit direction of the diffraction grating. As schematically shown by a small circle 41, the arrangement state of the liquid crystal molecules is a homogeneous arrangement in which the major axis is parallel to the slit direction of the diffraction grating.

In the state shown in FIG. 1B, the refractive index of the liquid crystal layer 40 is uniform irrespective of the location, and does not function as a diffraction grating. Therefore, the incident light incident from the substrate 1 goes straight as it is and exits from the substrate 10 side.

FIG. 2 shows the arrangement of liquid crystal molecules when a constant voltage is applied to the signal electrodes 23 and 33 with reference to the potentials of the reference electrodes 26 and 36 of the liquid crystal display panel shown in FIG. .

An electric field is generated in a region between the reference electrode 26 and the signal electrode 23 (hereinafter referred to as a "gap region") in a direction perpendicular to the slit direction of the diffraction grating. Under the influence of the electric field, the liquid crystal molecules existing in the gap region rotate, and the major axis thereof is made orthogonal to the slit direction of the diffraction grating as schematically shown by a rectangle 41a. Reference electrode 2
6 or a region corresponding to the signal electrode 23 (hereinafter, referred to as “electrode region”), no large lateral electric field is generated. For this reason, the liquid crystal molecules maintain the initial alignment state as schematically shown by the small circle 41b.

Consider a case where linearly polarized light having only a polarization component parallel to the slit direction of the diffraction grating is incident from the substrate 1 side. Light propagating through the electrode region of the liquid crystal layer 40 is:
The liquid crystal molecules have a refractive index substantially equal to the refractive index for extraordinary rays, and the light propagating in the gap region of the liquid crystal layer 40 has a refractive index substantially equal to the refractive index for the ordinary rays of liquid crystal molecules.

Next, consider linearly polarized light having only a polarization component perpendicular to the slit direction of the diffraction grating. The light propagating through the electrode region of the liquid crystal layer 40 has a refractive index substantially equal to the refractive index of the liquid crystal molecules with respect to ordinary light, and
The light propagating through the gap region has a refractive index substantially equal to the refractive index of the liquid crystal molecules for extraordinary rays.

The difference in the refractive index between the light propagating through the electrode region of the liquid crystal layer 40 and the light propagating through the gap region between the liquid crystal layer 40 and the extraordinary ray is determined by the liquid crystal layer 40 acting as a diffraction grating. It is almost equal to the difference from the refractive index. Therefore, the refractive index anisotropy Δn of the liquid crystal molecules can be sufficiently utilized.

In the above embodiment, the alignment direction of the alignment films 27 and 37 is substantially parallel to the slit direction of the diffraction grating. In this case, the signal electrodes 23 and 33 and the reference electrode 26,
When a voltage is applied between the liquid crystal layer 36 and the liquid crystal layer 36, the liquid crystal molecules in the gap region of the liquid crystal layer 40 rotate about 90 ° along a plane parallel to the substrate surface, but the direction of the rotation is not determined. For this reason, two regions where the directions of rotation of the liquid crystal molecules are different from each other may be formed. In the vicinity of the boundary between these two regions, the alignment state of the liquid crystal molecules becomes unstable, which causes deterioration of display characteristics.

By slightly shifting the alignment direction of the alignment films 27 and 37 and the slit direction of the diffraction grating from the parallel state, the rotation direction of the liquid crystal molecules when a voltage is applied can be determined. A preferred range of the angle between the orientation direction and the slit direction is 2 ° or more, and a more preferred range is 5 ° or more.

Also, if this angle is too large, FIG.
When the voltage shown in (1) is applied, the difference in the refractive index between the gap region and the electrode region of the liquid crystal layer 40 becomes small. In order to sufficiently increase the refractive index difference when a voltage is applied, it is preferable that the angle between the alignment direction and the slit direction be 45 ° or less.

In order to evaluate the display characteristics of the liquid crystal display panel according to the first embodiment, a liquid crystal display in which only one signal electrode and one reference electrode are formed on each substrate without dividing the substrate surface into pixels. A panel was prepared.

The signal electrodes 23 and 33 and the reference electrodes 26 and 3
6 is a method of forming a 0.8 μm thick ITO film on the entire surface,
It was formed by patterning. The width of the electrode portion is 7 μm, and the width of the gap portion is 4 μm, that is, the pitch is 11 μm. The ITO film is formed by using Ar and O ₂ as sputtering gas.
Using ITO as the target and a pressure of 4
The sputtering was performed at × 10 ⁻³ Torr, discharge power of 1.2 kW, and film formation temperature of room temperature. The patterning of the ITO film is performed by covering the surface of the ITO film with a resist pattern corresponding to the shapes of the signal electrode and the reference electrode, and using an etchant at a temperature of 45 ° C. in which hydrochloric acid, nitric acid and water are mixed at a ratio of 2: 1: 1. For 60 seconds. After patterning the ITO film, the surface of the substrate was washed with acetone and water, and heat-treated for 1 hour.

The alignment films 27 and 37 were formed by applying JALS-214R8 manufactured by Japan Synthetic Rubber Co., Ltd. on a substrate, and then performing a rubbing process in a direction at an angle of 5 ° to the slit direction of the diffraction grating. .

As a liquid crystal material, a nematic liquid crystal material ZLI-2293 manufactured by Merck with positive refractive index anisotropy was used. In the liquid crystal layer 40, a spacer SP20525 (5.25 μm in diameter) manufactured by Sekisui Fine Chemical was dispersed. The cell gap (liquid crystal layer 40) of this liquid crystal display panel
Was about 5.2 μm.

This liquid crystal display panel was applied to a projection type display device shown in FIG. 9 and the contrast was measured. Light source 80
Is a He-Ne laser emitting linearly polarized light, and the capture angle is 2
°. Here, the capture angle of 2 ° refers to the liquid crystal display panel 8.
It is assumed that transmitted light emitted in a direction having an angle of 1 degree or less with respect to the normal direction of 1 is transmitted through the through hole 85 of the light shielding plate 84 and transmitted light emitted in a direction of 1 degree or more is blocked. means.

When the liquid crystal display panel was driven at 5.1 V, the contrast was 190 when the polarization direction was parallel to and perpendicular to the slit direction of the diffraction grating.
Could be obtained. The diffraction angle of the first-order diffracted light is 3.
1 °.

Next, a second embodiment will be described with reference to FIG. In the first embodiment, a liquid crystal material having a positive refractive index anisotropy is used. In the second embodiment, a liquid crystal material having a negative refractive index anisotropy is used. The basic configuration of the liquid crystal display panel is the same as the configuration of the liquid crystal display panel according to the first embodiment shown in FIG. The orientation direction of the orientation films 27 and 37 is substantially perpendicular to the slit direction of the diffraction grating.

FIG. 3A shows an arrangement state of liquid crystal molecules when no voltage is applied. As schematically shown by a rectangle 41A,
The major axis of the liquid crystal molecules is substantially orthogonal to the slit direction of the diffraction grating. At this time, the liquid crystal layer 40 does not act as a diffraction grating.

FIG. 3B shows an arrangement state of liquid crystal molecules when a voltage is applied. The liquid crystal molecules in the gap region of the liquid crystal layer 40 are
It rotates along a plane parallel to the substrate surface under the influence of the electric field in the substrate surface direction. As schematically shown by the small circle 41Aa, the major axis of the liquid crystal molecules is substantially parallel to the slit direction of the diffraction grating. The liquid crystal molecules in the electrode region of the liquid crystal layer 40 maintain the initial alignment state as schematically shown by the rectangle 41Ab.

In the state shown in FIG. 3B, the liquid crystal layer 40 functions as a diffraction grating as in the case of FIG. Further, the refractive index anisotropy Δn of the liquid crystal molecules can be sufficiently utilized. In order to determine the direction of rotation of the liquid crystal molecules when voltage is applied, it is preferable that the angle between the alignment direction of the alignment films 27 and 37 and the slit direction of the diffraction grating is slightly shifted from 90 °. A preferable range of the shift angle is 88 ° or less, and a more preferable range is 85 ° or less. In order to make full use of the refractive index anisotropy Δn of the liquid crystal molecules, it is preferable that this angle is 45 ° or more.

In order to evaluate the display characteristics of the liquid crystal display panel according to the second embodiment, a liquid crystal display in which only one signal electrode and one reference electrode are formed on each substrate without dividing the substrate surface into pixels. A panel was prepared.

The angle between the alignment direction of the alignment films 27 and 37 and the slit direction of the diffraction grating was set to 85 °. As a liquid crystal material, a nematic liquid crystal material ZLI-4318 manufactured by Merck having a negative refractive index anisotropy was used. The liquid crystal layer 40 includes a spacer SP2055 made by Sekisui Fine Chemical.
0 (5.50 μm in diameter) was dispersed. The cell gap (the thickness of the liquid crystal layer 40) of this liquid crystal display panel is about 5.4 μm.
m.

The contrast of this liquid crystal display panel was measured in the same manner as in the first embodiment. When the liquid crystal display panel was driven at 6.8 V, a contrast of 230 could be obtained both when the polarization direction was parallel to and perpendicular to the slit direction of the diffraction grating. The diffraction angle of the first-order diffracted light was 3.3 °.

Next, a third embodiment will be described with reference to FIG. In the liquid crystal display panel according to the third embodiment, the signal electrode 2 of the liquid crystal display panel shown in FIG.
The dielectric film 28 is formed on the surface of the liquid crystal layer 40 side of the reference electrode 3 and the reference electrode 26 except for the region near the region closest to the adjacent electrode. A similar dielectric film 38 is formed on the surfaces of the signal electrode 33 and the reference electrode 36. Dielectric film 2
The dielectric constants of 8 and 38 are smaller than the maximum dielectric constant of the liquid crystal molecules. Other configurations are the same as those of the liquid crystal display panel according to the first embodiment.

In the liquid crystal display panel shown in FIG. 1B, when a voltage is applied, an electric field having a component parallel to the substrate surface is generated in a gap region between the signal electrode 23 and the reference electrode 26. Further, also in the electrode region, an electric field is generated in a direction oblique to the substrate surface. Some liquid crystal molecules in the electrode region rotate in the substrate plane under the influence of the oblique electric field,
And it rises obliquely to the substrate surface. This becomes a factor of weakening the diffraction intensity by the liquid crystal layer 40.

As shown in FIG. 4, by forming the dielectric films 28 and 38 having a dielectric constant smaller than the maximum dielectric constant of the liquid crystal molecules, the electric field in the electrode region of the liquid crystal layer 40 can be reduced. . Therefore, the influence of the rotation and rising of the liquid crystal molecules in the electrode region of the liquid crystal layer 40 can be reduced.

In order to evaluate the display characteristics of the liquid crystal display panel according to the third embodiment, a liquid crystal display in which only one signal electrode and one reference electrode are formed on each substrate without dividing the substrate surface into pixels. A panel was prepared.

As the dielectric films 28 and 38, Optmer PC-302 made of Japan Synthetic Rubber having a relative dielectric constant of 3.2 and a thickness of 1.4 μm was used. The optomer is also used as an etching mask for patterning the signal electrodes 23 and 33 and the reference electrodes 26 and 36.

The ITO film was etched under the same conditions as in the manufacture of the liquid crystal display panel for evaluation experiment of the first embodiment, and the signal electrodes 23 and 33 and the reference electrodes 26 and 36 were patterned. Under these conditions, the side surfaces of the signal electrode 23 and the reference electrode 26,
In addition, electrodes were obtained in which the side surfaces of the signal electrode 33 and the reference electrode 36 slightly protruded from the ends of the dielectric films 28 and 38, respectively. When the width of the dielectric films 28 and 38 is set to 6.5 μm, the signal electrodes 23 and 33 and the reference electrodes 26 and 36 are formed.
Became about 7 μm. Other components are the same as the liquid crystal display panel for evaluation experiment of the first embodiment.

The contrast of the liquid crystal display panel was measured by the same method as in the first embodiment. When the liquid crystal display panel was driven at 5.1 V, a contrast of 240 was obtained both when the polarization direction was parallel to and perpendicular to the slit direction of the diffraction grating. The diffraction angle of the first-order diffracted light was 3.5 °. As described above, the contrast can be increased by forming the dielectric film on a part of the surface of the signal electrode and the reference electrode.

Next, a fourth embodiment will be described with reference to FIG. In the liquid crystal display panels according to the first to third embodiments, it is necessary to form TFTs on both of the two substrates. In the liquid crystal display panel according to the fourth embodiment, a part of the alignment film 27 corresponding to the signal electrode 23 is removed to form an opening. The alignment film 37 also has the alignment film 2
An opening is formed at a position corresponding to the opening 7. In the liquid crystal layer 40, conductive spacers 42A and 42B are dispersed.

The spacers 42A located in the openings formed in the alignment films 27 and 37 electrically connect the signal electrodes 23 and 33. Since the voltage applied to the signal electrode 23 is also applied to the signal electrode 33, it is not necessary to form a TFT on the substrate 10 side. Since TFTs need only be formed on one substrate, manufacturing costs can be reduced.

In the first to fourth embodiments, the case where the signal electrode and the reference electrode are formed on both of the two substrates has been described, but they may be formed on only one of the substrates. Also,
The alignment film may be formed only on one substrate. In addition, the case where the transmission type liquid crystal display panel is manufactured by making both substrates transparent has been described. However, a reflection type liquid crystal display panel may be provided by providing a light reflection film on the opposite surface of one substrate.

FIG. 6 is a schematic view of a projection type color display device using a liquid crystal display panel according to any one of the first to fourth embodiments. The light source 60 emits coherent white collimated light. The white light emitted from the light source 60 is totally reflected by the mirror 61 and enters the dichroic mirror 62. The dichroic mirror 62 reflects red light and transmits green and blue light. Dichroic mirror 6
The blue light among the light transmitted through 2 is a dichroic mirror 6
The green light reflected by 3 passes through the dichroic mirror 63. In this manner, the white light emitted from the light source 60 is separated into red, green, and blue light.

The red light reflected by the dichroic mirror 62 is totally reflected by the mirror 65 and is returned to the liquid crystal display panel 6 for red.
8 is incident. The blue light reflected by the dichroic mirror 63 enters the liquid crystal display panel 69 for blue, and the green light transmitted through the dichroic mirror 63 enters the liquid crystal display panel 70 for green.

Each of the liquid crystal display panels 68, 69 and 70
This is a liquid crystal display panel according to any one of the first to fourth embodiments. The red, green, and blue liquid crystal display panels 68, 69, and 70 respectively have a center wavelength of red light of 629 nm, a center wavelength of green light of 555 nm, and a center wavelength of blue light of 481 nm.
The thickness is suitable for light of nm.

Liquid crystal display panels 68 and 69 for red, green and blue
And 70 are condensed by mutually equivalent lenses 73, 74 and 75, and are combined into light beams having a common optical axis by dichroic mirrors 66, 67 and mirror 64. A light shielding plate 71 is arranged at a position corresponding to the focal point of the lenses 73, 74 and 75. The light-shielding plate 71 has a pinhole at the intersection with the optical axis, transmits the 0th-order diffracted light transmitted through the liquid crystal display panels 68, 69, and 70, and blocks the first-order or higher-order diffracted light. Light shield 7
The light transmitted through one pinhole is projected on a screen by a projection lens 72.

As described above, by applying the liquid crystal display panel according to the embodiment of the present invention to a projection type color display device, it is possible to perform color display with high contrast.

In the first to fourth embodiments, the case where a diffraction type liquid crystal display panel is manufactured has been described. However, a direct-view type liquid crystal display panel can be formed by a configuration similar to that of the above embodiment.

FIG. 7 shows an example of a direct-view type liquid crystal display panel. The basic configuration is the same as that of the liquid crystal display panel according to the first embodiment shown in FIGS.
The widths of the gaps 3 and 33 and the reference electrodes 26 and 36 are different. In the liquid crystal display panel shown in FIG. 7, the width of the signal electrodes 23 and 33 and the reference electrodes 26 and 36 is about 5 μm, and the width of the gap is about 10 μm. That is, the arrangement pitch is about 15 μm. At such a pitch, diffraction of visible light hardly occurs.

The polarizing plates 2 and 12 are disposed on the outer surfaces of the substrates 1 and 10, respectively. The polarizing axis of the polarizing plate 2 is orthogonal to the slit direction, and the polarizing axis of the polarizing plate 12 is parallel to the slit direction.

When no voltage is applied, all liquid crystal molecules
Since the light is linearly polarized by the polarizing plate 2 because it is arranged in parallel to the slit direction, the light goes straight as it is and the polarizing plate 12
Cannot be transmitted. Therefore, black display is performed.

When a voltage is applied, the liquid crystal molecules in the gap region of the liquid crystal layer 40 rotate in the plane of the substrate as schematically shown by the cylinder 41a. The rotation angle can be controlled by the applied voltage. When the angle between the polarization axis of the linearly polarized light transmitted through the polarizing plate 2 and the long axis of the liquid crystal molecules is other than 0 ° or 90 °, the polarization axis of the light propagating through the gap region of the liquid crystal layer 40 depends on this angle. Turn. For this reason, some light passes through the polarizing plate 12. By controlling the applied voltage to change the turning angle, it is possible to control the light transmission amount in the gap region.

Light propagating in the electrode region of the liquid crystal layer 40 does not rotate even in the state where a voltage is applied. Therefore, the electrode region is always in a black display state.

By changing the applied voltage to control the amount of light incident on the gap region in the pixel, it can be used as a direct-view type liquid crystal display panel.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0074]

As described above, according to the present invention,
By rotating the liquid crystal molecules in the striped region along a plane parallel to the substrate surface, the liquid crystal layer can function as a diffraction grating. Also, the refractive index anisotropy Δn of the liquid crystal molecules
Can be fully utilized. Therefore, a large diffraction intensity can be obtained, and a projection type liquid crystal display device having high contrast can be manufactured.

[Brief description of the drawings]

FIG. 1 is a plan view of one substrate of a liquid crystal display panel according to a first embodiment of the present invention, and a cross-sectional view of the liquid crystal display panel.

FIG. 2 is a sectional view of the liquid crystal display panel according to the first embodiment of the present invention when a voltage is applied.

FIG. 3 is a sectional view of a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a liquid crystal display panel according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a liquid crystal display panel according to a fourth embodiment of the present invention.

FIG. 6 is a schematic view of a projection type color display device using a liquid crystal display panel according to an embodiment of the present invention.

FIG. 7 is a sectional view of a direct-view type liquid crystal display panel similar to the first embodiment.

FIG. 8 is a sectional view of a diffraction type liquid crystal display panel according to a conventional example.

FIG. 9 is a schematic diagram of a projection display device using a diffraction type liquid crystal display panel.

[Explanation of symbols]

 1, 10 Transparent substrate 2, 12 Polarizer 20 Data line 21 Control line 22 TFT 23, 33 Signal electrode 24S, 24D Contact hole 25 Reference electrode line 26, 36 Reference electrode 27, 37 Alignment film 28, 38 Dielectric film 40 Liquid crystal Layer 41 Liquid crystal molecule 42A, 42B Conductive spacer 50, 53 Transparent substrate 51, 54 Transparent electrode 52, 55 Alignment film 56 Liquid crystal layer 57 Liquid crystal molecule 60 Light source 61, 64, 65 Mirror 62, 63, 66, 67 Dichroic mirror 68, 69, 70 Liquid crystal display panel 71 Light shield plate 72 Projection lens 73, 74, 75 Lens 80 Light source 81 Liquid crystal display panel 82 Condenser lens 83 Projection lens 84 Light shield plate 85 Through hole 86 Screen

Claims (7)

[Claims] 1. A pitch which is formed on a pair of transparent substrates, at least one of which is transparent, and which is formed on a surface of at least one of the pair of substrates which causes a diffraction phenomenon with respect to visible light. Of a plurality of linear electrodes arranged in parallel,
A signal electrode in which every other electrode is connected to each other, a striped electrode composed of a reference electrode in which electrodes other than the signal electrode are connected to each other, and at least one of the pair of substrates And a liquid crystal layer sandwiched between the pair of substrates. 2. The liquid crystal molecules in the liquid crystal layer have a positive dielectric anisotropy, and the angle between the longitudinal direction of the linear electrode and the alignment direction given to the alignment film is less than 0 °. 2. The liquid crystal display panel according to claim 1, wherein the angle is larger than 45 °. 3. The liquid crystal molecules in the liquid crystal layer have negative dielectric anisotropy, and an angle between a longitudinal direction of the linear electrode and an alignment direction given to the alignment film is 45 ° or more. And 90 °
The liquid crystal display panel according to claim 1, wherein the liquid crystal display panel is smaller than the liquid crystal display panel. 4. The surface of the linear electrode covers a region other than a region closest to an adjacent linear electrode, and has a dielectric constant smaller than a maximum dielectric constant of liquid crystal molecules in the liquid crystal layer. The liquid crystal display panel according to any one of claims 1 to 3, further comprising a dielectric film. 5. The signal electrode and the reference electrode are formed for each of a plurality of pixels arranged in a matrix on the pair of substrate surfaces, and further formed on an opposing surface of the one substrate, and in a row direction. A reference line interconnecting the reference electrodes of the pixels in each of the arranged pixel columns; and a data line formed on the facing surface of the one substrate and arranged corresponding to each of the pixel columns arranged in the column direction. A plurality of control lines formed on the facing surface of the one substrate and corresponding to the respective pixel columns arranged in the row direction; and on the facing surface of the one substrate, corresponding to the pixels. 5. The switching element according to claim 1, further comprising a switching element formed and connected to the signal electrode of the corresponding pixel and the data line corresponding to the pixel, and controlled to be opened and closed by a signal applied to the corresponding control line. The liquid crystal display panel according to any one of the above. 6. The semiconductor device according to claim 1, further comprising a pair of substrates formed on a facing surface of the other substrate on which the signal electrode and the reference electrode are not formed, and formed at positions corresponding to the signal electrode and the reference electrode, respectively. The liquid crystal display panel according to claim 5, further comprising another signal electrode and another reference electrode. 7. The liquid crystal display panel according to claim 6, further comprising a conductive member for electrically connecting said signal electrode and said another signal electrode for each pixel.