JPH08304757A - Liquid crystal display device and projection type display device - Google Patents

Abstract

PURPOSE: To provide a liquid crystal panel with which the transmitted light quantity is made nearly equal without changing the thickness of a liquid crystal layer in each region of respective colors. CONSTITUTION: This liquid crystal display device has two substrates 35, 36 which are two parallel arranged substrates 30A, 30B and one substrate of which is delineated with two regions varying in the peak wavelength of transmitted light, electrodes 32, 33 which are respectively formed on the surfaces of these two substrates 35, 36 and impress electric fields independently on the two regions of the space held therebetween, oriented films 37, 38 which are formed on the surfaces on the opposite surface sides of the two substrates 35, 36, the liquid crystal layer 31 which is held by the two substrates 35, 36 and a voltage impressing means for impressing voltages on the electrodes 32, 33. The oriented films 37, 38 are subjected to orientation treatments in such a manner that twist angles varying from each other are imparted on the liquid crystal molecules of the liquid crystal layer 31 in the two regions. The voltage impressing means impresses the voltages of the magnitude varying from each other on the electrodes 32, 33 for impressing the electric fields respectively on the two regions. The magnitude of the voltages is so selected that the contrast ratio in the two regions is made more uniform than when the equal voltage is impressed on the electrodes.

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 a projection type display device. 2. Description of the Related Art In recent years, as a display device for a personal computer, a word processor, or the like, a lightweight and thin liquid crystal display device which can be driven by a battery has been remarkably adopted in place of a large-sized and power-consuming CRT. This liquid crystal display device also has a growing demand for color display from monochrome display,
Furthermore, high quality color display is required.

[0002]

2. Description of the Related Art In a color liquid crystal panel, linearly polarized light of each color of red, blue and green is rotated by the birefringence of a liquid crystal layer. The optical rotation in the polarization direction is effective at Δnd / λ. Here, Δn is the refractive index anisotropy with respect to light propagating in the liquid crystal layer in the normal direction, d
Is the thickness of the liquid crystal layer (Δnd is the retardation), and λ is the wavelength of light propagating through the liquid crystal layer. For this reason, blue light having a short wavelength can be changed in polarization direction to a larger extent.

Particularly, in a normally black mode liquid crystal panel, if Δnd is selected to be optimum for light of one wavelength, light of other wavelengths is not completely black when no voltage is applied. , And the contrast decreases. In order to prevent a decrease in contrast, it is necessary to make the optical rotations in the polarization direction equal regardless of the wavelength. A multi-gap type liquid crystal panel that realizes this has been proposed.

FIG. 8 shows the structure of a conventional multi-gap type liquid crystal panel. The liquid crystal layer 131 is sandwiched between a pair of glass substrates 134 in which an alignment film 132 and a transparent electrode 133 are laminated. One glass substrate 134 and transparent electrode 133
A color filter 135 is inserted between and. Symbols B, G, and R in the figure indicate regions that transmit blue, green, and red light, respectively. The thickness of the color filter 135 is formed to be thinner in the order of B, G, and R.
That is, the thickness of the liquid crystal layer 131 increases in the order of the blue portion, the green portion, and the red portion.

By changing the thickness d of the liquid crystal layer 131 for each color region, Δnd / λ even if the wavelength λ is different.
Is to be constant. By making Δnd / λ constant, it is possible to equalize the optical rotation in each color region.

[0006]

In the multi-gap type liquid crystal panel, it is usually necessary to make the thickness of the color filter different for each color area. However, a color filter having a different thickness is manufactured for each color area. Is difficult to do.

An object of the present invention is to provide a liquid crystal panel capable of making the amount of transmitted light of each color substantially equal without changing the thickness of the liquid crystal layer for each color region. Another object of the present invention is to provide a liquid crystal panel having substantially the same contrast ratio for each color.

[0008]

According to one aspect of the present invention, there are two substrates arranged in parallel at regular intervals, and at least one of the two substrates has a peak of transmitted light. Corresponding to at least the two regions of a space formed between the two substrates in which at least two regions having different wavelengths are defined, and the surfaces of the two substrates, and sandwiched between the two substrates. An electrode capable of independently applying an electric field to a region to be formed, an alignment film formed on the surfaces of the two substrates facing each other, a liquid crystal layer sandwiched between the two substrates, A voltage applying unit for applying a voltage to the electrodes, and the alignment film is aligned so that different twist angles are given to liquid crystal molecules of the liquid crystal layer in regions corresponding to the two regions. Has been processed and the voltage application Are applied to the electrodes corresponding to the two regions with different magnitudes of voltage applied to the electrodes, respectively, and the magnitude of the voltage is larger than that when the contrast ratio in the two regions is equal. Also provided is a liquid crystal display device selected to be uniform.

According to another aspect of the present invention, at least three regions having different peak wavelengths of transmitted light are defined on the one substrate, and the electrodes are independently provided in the three regions. An electric field can be applied, and one of the alignment films is subjected to alignment treatment in the same direction in the regions corresponding to two of the three regions and in different directions in the other regions. , The other alignment film has the same direction in a region corresponding to two regions of a combination different from the combination in which the one alignment film is subjected to the alignment treatment in the one of the three regions,
In another region, orientation treatment in different directions is performed, and
3. The area is provided with three different twist angles.
The liquid crystal display device described in 1. is provided.

According to another aspect of the present invention, there are two substrates arranged in parallel at regular intervals, and at least one of the two substrates has a different peak wavelength of transmitted light. Two substrates in which two regions are defined, and the two substrates respectively formed on the surfaces of the two substrates.
An electrode capable of independently applying an electric field to a region corresponding to the two regions in a space sandwiched between the two substrates, and an alignment film formed on the surfaces of the two substrates facing each other. ,
A liquid crystal layer sandwiched between the two substrates, wherein the alignment film has a region corresponding to the two regions,
The liquid crystal molecules of the liquid crystal layer are oriented so that different twist angles are given to each other, and the twist angles of the liquid crystal molecules in the liquid phase layer in the regions corresponding to the two regions are the same as those of the liquid crystal layer. In the area corresponding to the two areas,
When linearly polarized light having a wavelength equal to the peak wavelength of transmitted light in each region enters from the normal direction of the liquid crystal layer, it becomes linearly polarized light on the exit side surface of the liquid crystal layer, and polarization on the incident side surface. There is provided a liquid crystal display device in which an angle formed between the direction and the polarization direction on the emission side surface is selected to be equal in the areas corresponding to the two areas.

According to another aspect of the present invention, an optical system for generating collimated first and second lights having mutually different peak wavelengths and an optical system on the optical axes of the first and second lights are provided. Twisted nematic type first and second liquid crystal panels that are respectively arranged and have polarizing plates on the incident side surface and the output side surface, and change the light transmittance according to a signal from the outside, and the first and second liquid crystal panels. And a color synthesizing means for synthesizing light transmitted through the liquid crystal panel on a common optical axis, the first and second liquid crystal panels have liquid crystal layer thicknesses substantially equal to each other, and twist angles of liquid crystal molecules are equal to each other. Differently, the first and second liquid crystal panels are provided with first and second retardation films having birefringence, respectively, and the first and second retardation films have different refractive indices. The product Δnd of the anisotropic Δn and the film thickness d, and the retardation of the retardation film. At least one of the angles θ formed by the phase axis and the polarization axis of the polarizing plate disposed on the exit side surface is different, and the product Δnd and the angle θ are such that the contrast ratio of light transmitted through the liquid crystal panel is Provided is a projection display device which is selected to be more uniform than in the case where no retardation film is provided in the first and second liquid crystal panels.

According to another aspect of the present invention, an optical system for generating collimated first and second lights having mutually different peak wavelengths and an optical system on the optical axes of the first and second lights are provided. Twisted nematic type first and second liquid crystal display panels that are respectively arranged and change the light transmittance according to a signal from the outside, and a common optical axis for the light transmitted through the first and second liquid crystal display panels. The first and second liquid crystal panels have substantially the same thickness of liquid crystal layers and different twist angles of liquid crystal molecules.
And the twist angle of the second liquid crystal panel, when linearly polarized light having the peak wavelengths of the first and second lights respectively enters the liquid crystal layers of the first and second liquid crystal panels from the normal direction, The surface on the exit side of the liquid crystal layer becomes linearly polarized light, and the angles formed by the polarization direction on the entrance side and the polarization direction on the exit side are selected to be equal in the first and second liquid crystal panels. The projection display device is provided.

[0013]

[Operation] The optical rotation of light propagating in the liquid crystal layer in the normal direction is Δ
It becomes a function of nd / λ. Here, Δn is the refractive index anisotropy of the liquid crystal layer with respect to light propagating in the normal direction of the liquid crystal layer, d is the thickness of the liquid crystal layer, and λ is the wavelength of light. If the twist angle of the liquid crystal layer is different, Δn is different. If the twist angle is set for each area so that Δnd / λ of each area is constant with respect to the light of the wavelength that transmits the area, the optical rotation of each area The degrees can be equal.

When the same drive voltage is applied to regions having different twist angles, the contrast ratio in each region becomes uneven. This is because liquid crystal molecules are less likely to tilt as the twist angle becomes smaller. The contrast ratio can be made uniform by changing the drive voltage for each region having a different twist angle and setting an appropriate voltage.

By providing the substrate with three regions having different peak wavelengths of transmitted light, full-color display is possible.
By performing the alignment treatment in the same direction in two of the three regions of each alignment film and changing the combination of the regions subjected to the alignment treatment in the same direction for the two alignment films, 3
Different types of twist angles can be given.

In the projection display device capable of displaying at least two colors, the liquid crystal panel is independent for each display color.
Also in this case, the optical rotation in each liquid crystal panel can be made equal by setting the twist angle so that Δnd / λ of each liquid crystal panel becomes constant.

Further, by providing a retardation film to each liquid crystal panel and adjusting the retardation of the retardation film or the angle between the slow axis and the polarization axis of the retardation film, the contrast ratio of each liquid crystal panel can be improved. Can be uniform with each other.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a liquid crystal display device according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view of a liquid crystal display device. The liquid crystal layer 31 is enclosed between the two substrates 30A and 30B. Polarizing plates 39 and 40 are arranged outside the substrates 30A and 30B, respectively. The substrate 30B includes a glass substrate 36, a transparent electrode 33, and an alignment film 38. The transparent electrode 33 and the alignment film 38 are formed on the glass substrate 3
6 is laminated in this order on the liquid crystal layer 31 side surface.

The substrate 30A is composed of a glass substrate 35, a color filter 34, a transparent electrode 32, and an alignment film 37. Regions R, G, and B that respectively transmit red light, green light, and blue light are formed in the color filter 34. The color filter 34 is the glass substrate 3
5 is disposed on the liquid crystal layer 31 side surface.

The transparent electrode 32 is formed on the color filter 34 independently for each of the regions R, G and B. The alignment film 37 is formed so as to cover the surfaces of the transparent electrode 32 and the color filter 34.

White light is incident from the lower side of the substrate in the normal direction of FIG. 1 and is linearly polarized by the polarizing plate 39. The linearly polarized light is filtered by the color filter 34, and the light transmitted through the regions R, G, B becomes colored light having peak wavelengths in the red, green, and blue wavelength regions, respectively. The light filtered by the color filter 34 propagates through the liquid crystal layer 31 and reaches the polarizing plate 40. Of the light reaching the polarizing plate 40, only the component in the polarization axis direction of the polarizing plate 40 passes through the polarizing plate 40.

2A, 2B and 2C show the polarization axis of the polarizing plate and the alignment direction of the alignment film in the regions B, G and R of the liquid crystal panel shown in FIG. 1, respectively. The straight lines P and A in the figure respectively represent the incident side polarization plate 39 and the emission side polarization plate 40 of FIG.
Shows the polarization axis of. As shown in FIGS. 2A to 2C, the two polarizing plates are arranged in crossed Nicols so that the polarization axes P and A are orthogonal to each other.

As shown in FIG. 2A, in the area B,
Alignment direction R _B2 of the alignment film of the alignment direction R _B1 and the exit side of the alignment film of the incident side is alignment treatment in parallel to the polarization axis A of the polarization axis P and the exit side of the respective incident-side. The twist angle T _B is 90 °.

As shown in FIG. 2B, in the area G,
The alignment direction R _G1 of the alignment film on the incident side is displaced clockwise from the polarization axis on the incidence side in the figure, and the alignment direction R _G2 of the alignment film on the emission side is counterclockwise in the figure than the polarization axis A on the emission side. The alignment treatment is performed so that the shift angles are the same and the shift angles are equal. Therefore, the twist angle T _G becomes an angle smaller than 90 °. Also, the bisector of the twist angle T _G intersects the polarization axes P and A at 45 °.

As shown in FIG. 2C, in the region R,
Alignment treatment is performed so that the deviation angles of the alignment directions R _R1 and R _R2 of the incident-side and exit-side alignment films from the polarization axes P and A become larger than that in the region G. For this reason, the twist angle T _R
Becomes smaller than the twist angle T _G. The deviation angle between the alignment direction and the polarization axis is the same on the incident side and the emission side, and the bisector of the twist angle T _R intersects the polarization axes P and A at 45 °.

As described above, the twist angle is different for each of the regions R, G, and B, and the alignment treatment is performed so that the bisectors of the twist angle intersect with the polarization axis at an angle of 45 ° in each region.
Next, a method of aligning the alignment film in three different directions will be described. After forming the alignment film on the surface of the glass substrate, only one of the regions R, G and B is exposed and the other regions are covered with a resist pattern. As the resist, for example, Microposit S1808 manufactured by Shipley Co. is used. After covering with the resist pattern, rubbing is performed in a desired direction. As a result, the exposed region on the surface of the alignment film is subjected to the alignment treatment.

This process is performed for other regions as well, and the alignment process in a desired direction is performed for each region. By performing rubbing a total of three times, the regions R, G, and B can be subjected to alignment treatments in different directions.

Next, the light transmission characteristics of the liquid crystal panel shown in FIGS. 1 and 2 will be described. Table 1 shows, for each wavelength, the relationship between the twist angle and the thickness of the liquid crystal layer so that the linearly polarized light that has entered the liquid crystal layer in the normal direction is output as linearly polarized light that has been rotated by 90 °.

[0030]

[Table 1] For example, when the thickness of the liquid crystal layer is 3.5 μm, the wavelength 420
nm blue light, wavelength 550 nm green light, and wavelength 61
The polarization direction of 0 nm red light has a twist angle of 9
Rotate 90 ° at 0 °, 60 °, and 40 °. When the thickness of the liquid crystal layer is 3.1 μm, the wavelength is 420 nm.
Blue light, wavelength 550nm green light, and wavelength 610n
The twist angle of the red light of m is 80
Rotate 90 ° at °, 40 °, and 0 °.

That is, in FIG. 1, the thickness of the liquid crystal layer 31 is 3.5 μm, and in FIG. 2, the twist angle T _B ,
If T _G and T _R are 90 °, 60 °, and 40 °, respectively, the polarization direction is 9 in all the regions R, G, and B.
It can be rotated by 0 °. In this way, the optical rotation in the polarization direction can be made constant by making the thickness of the liquid crystal layer uniform and changing the twist angle for each region where the peak wavelength of transmitted light differs.

Since the optical rotations of the respective color regions are equal to each other, the amounts of transmitted light of the respective colors transmitted through the liquid crystal panel are substantially equal to each other, and a good white balance can be obtained.
Next, the drive voltage of the liquid crystal panel will be described with reference to FIG.

FIG. 3 shows the contrast ratio and the drive voltage with respect to the twist angle. The horizontal axis is the twist angle in degrees
, The left vertical axis represents the contrast ratio, and the right vertical axis represents the drive voltage in the unit V. The symbol ● in the figure indicates a drive voltage of 5V.
The contrast ratio is shown when it is kept constant, and the symbol ◯ shows the driving voltage when the contrast ratio becomes 100.

The liquid crystal used is a trifluorescent liquid crystal made by Chisso which can be driven at a low voltage, and the alignment film is LC-made by Hitachi Chemical.
102, and the contrast ratio is based on the normally white mode.

Here, the normally white mode is a mode in which the amount of transmitted light is maximum when no voltage is applied. When no voltage is applied, the long axis direction of the liquid crystal molecules is substantially along the substrate surface, and the refractive index anisotropy with respect to the light propagating in the liquid crystal layer in the normal direction becomes the largest. Therefore, the optical rotation in the polarization direction is maximized. That is, if the polarizing plates on the incident side and the outgoing side are arranged so that their polarization axes are substantially orthogonal to each other,
Enters normally white mode.

The contrast ratio means the ratio of the amount of transmitted light when voltage is applied to the amount of transmitted light when no voltage is applied.
When the drive voltage is constant, the contrast ratio becomes lower as the twist angle becomes smaller. When a voltage is applied to the liquid crystal panel, the long axes of the liquid crystal molecules are tilted so that they are perpendicular to the substrate surface, but they are not completely vertical and the refractive index anisotropy for light propagating in the substrate normal direction remains. . Due to the remaining refractive index anisotropy, the linearly polarized light incident on the liquid crystal layer becomes elliptically polarized light, and a part of the light is blocked by the polarizing plate on the emission side. Therefore, the transmittance does not become 100% when the voltage is applied, and the contrast ratio becomes low.

When the twist angle becomes smaller, the liquid crystal molecules are less likely to tilt, and the residual refractive index anisotropy becomes large.
It is considered that the contrast ratio becomes low. Therefore,
If the same voltage is applied to the electrodes corresponding to the regions R, G, and B, the contrast ratio of each color will not be equal.

In order to make the contrast ratio of each color the same, it is necessary to increase the drive voltage as the twist angle becomes smaller, as indicated by the symbol ◯ in FIG. For example,
The twist angles of the regions R, G, and B are 40 ° and 60, respectively.
At 90 ° and 90 °, equal contrast ratios can be obtained by setting the voltages applied to the electrodes corresponding to the regions R, G, and B to 2.2: 1.8: 1, respectively.

When the voltage applied to the region B is 1, the voltage applied to the regions G and R is 1.6 to
If it is set to 2.0 and 2.0 to 2.4, it will be possible to obtain substantially equal contrast ratios that are not a problem in practical use. Further, when the twist angles of the regions R, G, and B are changed, the ratio of the driving voltage is strictly different, but if the conditions of the above voltage ratio are satisfied, a substantially equal contrast ratio that does not pose a problem in practical use can be obtained. Will be possible. It should be noted that the display characteristics will be improved by merely increasing or decreasing the applied voltage in the direction in which the contrast ratios of the respective areas are mutually uniform.

Next, a modified example of the above embodiment will be described with reference to FIGS. 4A, 4B, and 4C show the relationship between the polarization axis and the alignment direction in regions B, G, and R, respectively.

As shown in FIG. 4A, in the area B,
The polarization axis P on the incident side is parallel to the alignment direction R _B1 on the incident side, and the polarization axis A on the exit side is parallel to the alignment direction R _B2 on the emission side. Therefore, the twist angle T _B becomes 90 °.

As shown in FIG. 4B, in the area G,
The polarization axis P on the incident side and the orientation direction R _G1 on the incident side are parallel to each other. The exit side alignment direction R _G2 is a direction in which the entrance side alignment direction R _G1 is inclined by 60 ° in the clockwise direction in the drawing. Therefore, the twist angle T _G becomes 60 °.

As shown in FIG. 4C, in the region R,
The emitting side alignment direction R _R2 is the emitting side alignment direction R _G2 of the region G.
Parallel to. The incident side alignment direction R _R1 is a direction in which the exit side alignment direction R _R2 is inclined 40 ° counterclockwise in the drawing. Thus the twist angle T _R becomes 40 °.

In this way, since the orientation directions R _B1 and R _{G1 on} the incident side and the orientation directions R _G2 and R _R2 on the emission side are parallel to each other, each orientation film has two different orientation treatments. Will be applied. When the alignment treatment is performed by rubbing, the number of times of rubbing can be reduced to two.

When the orientation direction shown in FIG.
, The angle between the bisector of the twist angle T _B and the polarization axis is 45 °, but in the regions G and R, the bisector of the twist angles T _G and T _R and the polarization axis are formed. 45 corners
It doesn't become °. When the angle formed by the polarization axis P on the incident side and the bisector of the twist angle is 45 °, the linearly polarized light is rotated most efficiently. When the angle between the polarization axis P on the incident side and the bisector of the twist angle is other than 45 °, the optical rotation is small.

Therefore, in the regions G and R, the elliptically polarized light is not the linearly polarized light which is rotated by 90 ° on the exit side surface of the liquid crystal layer. However, since the deviation of the bisector of the twist angle from the ideal direction is slight, it is considered that this elliptically polarized light is very long and close to linearly polarized light. Therefore, it is considered that a sufficiently high transmittance can be obtained when no voltage is applied even when the alignment direction shown in FIG. 4 is provided.

FIG. 5 is a process chart for explaining a method of giving the alignment film the orientation shown in FIG. Note that FIG.
Although only the substrate on the incident side is shown, the orientation process can be performed on the substrate on the emitting side by the same method.

As shown in FIG. 5A, a color filter 34 and a transparent electrode 32 are laminated on the surface of a glass substrate 35,
An alignment film 37 is formed on this. The alignment film 37 is
It has a two-layer structure of a lower layer alignment film 37A and an upper layer alignment film 37B. For example, an alignment film PI-400 manufactured by Ube Industries is used as the lower-layer alignment film 37A, and an alignment film JALS-214 manufactured by JSR is used as the upper-layer alignment film 37B. The surface of the upper alignment film 37B is rubbed with the brush 50 in the alignment direction R _R1 shown in FIG. 4C.

As shown in FIG. 5B, a resist film is applied on the surface of the upper alignment film 37B to remove the resist film on the regions G and B, and a resist pattern 41 is formed. The upper alignment film 37B is partially etched using the resist pattern 41 as an etching mask to expose the surfaces of the regions G and B of the lower alignment film 37A. For example, as an etchant, an alkaline developer of resist (for example, MF-319) is used.
Etc.) is used.

The exposed surface of the lower layer alignment film 37A is shown in FIG.
Rubbing is performed with the brush 50 in the direction of the orientation direction R _B1 of A. As shown in FIG. 5C, the resist pattern 41 is removed. The alignment film 37 has an upper alignment film 37B in the region R.
And the alignment direction formed in the lower alignment film 37A in the regions G and B. In this way, the alignment film can have two different alignment directions.

Next, another embodiment will be described with reference to FIGS. FIG. 6 is a schematic view of a projection type display device in another embodiment. The projection display device includes a white light generator 60, a color separator 70, a liquid crystal panel 80, a color synthesizer 90, and a projection lens 100.

The white light generator 60 includes a metal halide lamp 61, a dichroic reflector 62, and a reflection mirror 6.
3 and a heat ray ultraviolet ray cut filter 64. The dichroic reflector 62 transmits infrared rays and collimates the remaining white light emitted from the metal halide lamp 61. The reflection mirror 63 reflects the collimated light and guides it to the heat ray ultraviolet ray cut filter 64. The heat ray ultraviolet ray cut filter 64 cuts the heat ray and the ultraviolet ray component in the white light.

The color separation section 70 is composed of the dichroic mirror 7
1, 72 and a reflection mirror 73. The dichroic mirror 71 reflects only the short-wavelength component corresponding to blue of the white light emitted from the white-light generating unit 60 and transmits the other long-wavelength components. The dichroic mirror 72 reflects only the short wavelength component corresponding to green of the light transmitted through the dichroic mirror 71 and transmits the long wavelength component corresponding to red.

The reflection mirror 73 reflects the light of the blue component reflected by the dichroic mirror 71 and guides it to the liquid crystal panel section 80. The liquid crystal panel section 80 includes condenser lenses 81B, 81G, 81R, a liquid crystal panel 82B, and
It is composed of 82G and 82R. Each of the condenser lenses 81B, 81G, and 81R includes a color separation unit 7
The blue component light, the green component light, and the red component light separated by 0 are incident. The liquid crystal panels 82B, 82G, and 82R have condenser lenses 81B, 81G, and 8 respectively.
The light transmitted through 1R is incident.

The color synthesizing section 90 comprises a reflecting mirror 91 and dichroic mirrors 92 and 93. The dichroic mirror 92 transmits the blue component light that has passed through the liquid crystal panel 82B, reflects the green component light that has passed through the liquid crystal panel 82G, and combines both light fluxes on the same optical axis.
The reflection mirror 91 reflects the red component light transmitted through the liquid crystal panel 82R and guides it to the dichroic mirror 93.

The dichroic mirror 93 transmits the blue component light and the green component light combined by the dichroic mirror 92, reflects the red component light reflected by the reflection mirror 91, and combines all the light fluxes on the same optical axis. To do. The projection lens 100 projects the light combined by the light combining unit 90 onto the projection surface.

The liquid crystal layers of the liquid crystal panels 82B, 82G and 82R have the same thickness, for example, 3.5 μm. At this time, in order to equalize the optical rotation of the light propagating through the liquid crystal layer of each liquid crystal panel, the liquid crystal panels 82B, 82G, and 82R are formed.
The twist angles of 90 degrees, 60 degrees, and 40 degrees are respectively set. In this way, by equalizing the thickness of the liquid crystal layer of the liquid crystal panel for each color and adjusting the twist angle appropriately, it is possible to equalize the optical rotation of the light propagating through the liquid crystal layer.
If the optical rotations are equal, the amount of transmitted light of each color is almost equal.

Since the twist angle of the liquid crystal panel for each color is changed, when each liquid crystal panel is driven with the same voltage, the contrast ratio of each color is different, as described in FIG. In order to make the contrast ratio of each color equal, the drive voltage for each liquid crystal panel may be changed as described above. A retardation film may be used to make the contrast ratios equal. Hereinafter, a method of adjusting the contrast ratio using the retardation film will be described.

FIG. 7A shows a cross section of a liquid crystal panel provided with a retardation film. The liquid crystal layer 31 is sandwiched between the substrates 30A and 30B. Although not shown in the figure, the substrate 3
Transparent electrodes and alignment films are formed on 0A and 30B. Polarizing plates 39 and 4 are provided outside the substrates 30A and 30B.
0 is arranged. A retardation film 42 is inserted between the substrate 30B and the polarizing plate 40.

When linearly polarized light is incident on the liquid crystal layer 31 from the lower side of the figure, the incident light is rotated when propagating through the liquid crystal layer 31. The light emitted from the liquid crystal layer 31 is the phase difference film 4
It is incident on 2 and is further rotated. Thus, the retardation film 42 has a function of compensating for the shortage of the optical rotation due to the liquid crystal layer 31.

FIG. 7B shows the contrast ratio when a retardation film is applied to the liquid crystal panel. The polarization axis P of the polarization plate on the incident side and the polarization axis A of the polarization plate on the emission side are orthogonal to each other,
An angle formed by the alignment direction R ₁ of the alignment film on the incident side and the alignment direction R ₂ of the alignment film on the output side, that is, a twist angle is 45 °, and the liquid crystal used is a trifluorescent liquid crystal. A halogen lamp was used as the light source, and a Canon liquid crystal luminance meter was used as the measuring device, and the viewing angle characteristics were obtained from the output corrected for luminosity.

In the in-plane direction of the retardation film, the angle θ between the direction (slow axis) D having the largest refractive index and the polarization axis A, or the retardation Δnd of the retardation film.
Was changed to obtain the contrast ratio on the front side. Hereinafter, the angle θ formed by the slow axis D and the polarization axis A will be referred to as the installation angle of the retardation film.

The horizontal axis of FIG. 7B represents the installation angle θ of the retardation film in the unit of “degree”, and the vertical axis represents the front contrast ratio. Curves a, b, and c in the figure indicate that retardation Δnd of the retardation film is 109 nm and 61 n, respectively.
The contrast ratio when m and 22 nm are shown.

When the retardation Δnd is 109 nm and the installation angle θ of the retardation film is increased from 0, the contrast ratio gradually increases, and reaches the maximum value when the installation angle θ is about 7 °. When the installation angle θ is further increased, the contrast ratio gradually decreases.

A similar tendency is obtained when the retardation Δnd is 61 nm, and the contrast ratio becomes maximum when the installation angle θ is about 15 °. Retardation Δnd is 22 nm
In this case, the contrast ratio monotonically increases with respect to the installation angle θ when the installation angle θ is in the range of 0 to 20 °. In this case, 2
It is considered that the maximum value is obtained at an installation angle of 0 ° or more.

From FIG. 7B, it is understood that the contrast ratio can be changed by changing the retardation or the installation angle of the retardation film applied to the liquid crystal panel. Therefore, by providing a retardation film to each of the liquid crystal panels 82B, 82G, and 82R for each color of the projection display apparatus shown in FIG. 6 and adjusting the retardation or the installation angle of the retardation film, the contrast ratio of each color can be improved. It can be adjusted to be uniform.

In the above embodiment, the case where the transmitted light amounts of the three primary colors of blue, green and red are controlled to perform full color display has been described. However, in the above embodiment, the transmitted light amounts of at least two colors of light are controlled to achieve color display. It is also effective when displayed.

The present invention has been described above with reference to the 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.

[0069]

As described above, according to the present invention,
Even if the thickness of the liquid crystal layer is uniform, the twist angle can be adjusted so that the optical rotations of the light beams of different wavelengths propagating in the normal direction of the liquid crystal layer become substantially equal to each other. Since the optical rotations can be made equal, it is possible to make the amounts of transmitted light of each wavelength almost equal. By changing the voltage applied to the liquid crystal layer for each twist angle, it is possible to make the contrast ratios by the light of each wavelength almost equal.

Since the thickness of the liquid crystal layer can be made uniform, the manufacturing process of the liquid crystal panel can be simplified and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal panel according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram for explaining a polarization axis direction and an alignment direction of the liquid crystal panel of FIG.

3 is a graph showing a contrast ratio and a drive voltage of the liquid crystal panel of FIG. 1 with respect to a twist angle.

FIG. 4 is a diagram for explaining a polarization axis direction and an orientation direction of a liquid phase panel according to a modified example of the embodiment shown in FIG.

5 is a cross-sectional view of a substrate for explaining an alignment treatment process of the liquid phase panel shown in FIG.

FIG. 6 is a schematic view of a projection display device according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view of a liquid crystal panel provided with a retardation film, and a graph showing a contrast ratio when the liquid crystal panel is provided with a retardation film, with respect to an installation angle of the retardation film.

FIG. 8 is a sectional view of a multi-gap type liquid crystal panel according to a conventional example.

[Explanation of symbols]

 30A, 30B Substrate 31 Liquid crystal layer 32, 33 Transparent electrode 34 Color filter 35, 36 Glass substrate 37, 38 Alignment film 39, 40 Polarizing plate 41 Resist pattern 42 Phase difference film 50 Brush 60 White light generating part 61 Metal halide lamp 62 Dichroic reflector 63, 73, 91 Reflection mirror 64 Heat ray ultraviolet ray cut filter 70 Color separation section 71, 72, 92, 93 Dichroic mirror 80 Liquid crystal panel section 81B, 81G, 81R Condenser lens 82B, 82G, 82R Liquid crystal panel 90 Color composition section 100 Projection lens 131 Liquid Crystal Layer 132 Alignment Film 133 Transparent Electrode 134 Glass Substrate 135 Color Filter

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsumi Omuro 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Yoji Suzuki, 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (6)

[Claims] 1. A pair of substrates arranged in parallel at regular intervals, wherein at least one of the two substrates defines at least two regions having different peak wavelengths of transmitted light. An electric field can be independently applied to two substrates and regions formed respectively on the surfaces of the two substrates and corresponding to at least the two regions in a space sandwiched between the two substrates. An electrode, an alignment film formed on the surfaces of the two substrates opposite to each other, a liquid crystal layer sandwiched between the two substrates, and a voltage applying means for applying a voltage to the electrodes. The alignment film is aligned so that different twist angles are imparted to liquid crystal molecules of the liquid crystal layer in regions corresponding to the two regions, and the voltage applying unit is configured to To the area corresponding to one area Voltages having different magnitudes are applied to the electrodes to which an electric field is applied, and the magnitudes of the voltages are made uniform so that the contrast ratio in the two regions is more uniform than that when an equal voltage is applied to the electrodes. Liquid crystal display device selected for. 2. At least three regions having different peak wavelengths of transmitted light are defined on the one substrate, and the electrodes can independently apply an electric field to the three regions, Among the alignment films, one alignment film is subjected to alignment treatment in the same direction in the regions corresponding to two regions of the three regions and in different directions in the other regions, and the other alignment film is Of the three regions, the one alignment film is subjected to the alignment treatment in the same direction, and the region corresponding to two regions of different combinations is subjected to the alignment treatment in the same direction, and the other regions are subjected to the alignment treatment in different directions. The liquid crystal display device according to claim 1, wherein three different twist angles are given to one region. 3. Two substrates arranged in parallel at regular intervals, wherein at least one of the two substrates defines at least two regions having different peak wavelengths of transmitted light. Two substrates and electrodes formed respectively on the surfaces of the two substrates and capable of independently applying an electric field to regions corresponding to the two regions of a space sandwiched between the two substrates. And an alignment film formed on the surfaces of the two substrates facing each other, and a liquid crystal layer sandwiched between the two substrates, wherein the alignment film corresponds to the two regions. In the region, the liquid crystal molecules of the liquid crystal layer are subjected to alignment treatment so that different twist angles are imparted to each other, and the twist angle of the liquid crystal molecules in the liquid phase layer in the regions corresponding to the two regions is Corresponds to the two areas of liquid crystal layer When linearly polarized light with a wavelength equal to the peak wavelength of the transmitted light in each region is incident on each region from the normal direction of the liquid crystal layer, it becomes linearly polarized light on the exit side surface of the liquid crystal layer and the incident side The liquid crystal display device is selected such that the angle formed by the polarization direction in the plane of 1 and the polarization direction in the plane on the exit side is equal in the regions corresponding to the two regions. 4. The liquid crystal display device according to claim 3, wherein the angle formed is 90 °. 5. An optical system for generating collimated first and second lights having mutually different peak wavelengths, and an optical system disposed on the optical axes of the first and second lights, respectively, for incident side and emission. A first and a second liquid crystal panel of twisted nematic type, which has a polarizing plate on the side surface and changes the light transmittance according to a signal from the outside, and a light transmitted through the first and second liquid crystal panels. A color synthesizing means for synthesizing on a common optical axis, wherein the first and second liquid crystal panels have substantially the same liquid crystal layer thickness and different twist angles of liquid crystal molecules, The first and second retardation films each having birefringence are provided in the liquid crystal panel of 1., and the first and second retardation films have a refractive index anisotropy Δn.
And the film thickness d, and the angle θ between the slow axis of the retardation film and the polarization axis of the polarizing plate arranged on the exit side surface.
At least one of them is different, and the product Δnd and the angle θ are more uniform in the contrast ratio of light transmitted through the liquid crystal panel than in the case where no retardation film is provided in the first and second liquid crystal panels. The projection display device that is selected to be realized. 6. An optical system for generating collimated first and second lights having mutually different peak wavelengths, and a signal from the outside arranged on the optical axes of the first and second lights, respectively. Twist nematic first and second liquid crystal display panels that change the light transmittance thereof, and color synthesizing means for synthesizing the light transmitted through the first and second liquid crystal display panels on a common optical axis. The first and second liquid crystal panels have substantially the same thickness of liquid crystal layers and different twist angles of liquid crystal molecules, and the twist angles of the first and second liquid crystal panels are the same as those of the first and second liquid crystal panels. When the linearly polarized light having the peak wavelength of the second light is incident on the liquid crystal layers of the first and second liquid crystal panels from the normal direction, the linearly polarized light becomes the linearly polarized light on the exit side surface of the liquid crystal layer and is incident. Direction on the side surface and exit side The angle between the polarization direction in the plane is, the projection display device is selected to be equal in the first and second liquid crystal panels.