JP2000347157A - Projection display device - Google Patents

Abstract

(57) [Problem] To provide a projection type display device using a liquid crystal device as a light modulating device, which has high color reproducibility in a halftone of a color image and is bright even if the liquid crystal device changes in temperature. Display images with good contrast. SOLUTION: Liquid crystal modules 1R, 1G, 1B (light modulating means) used in a projection type display device have liquid crystal light valves 100R, 100G, 100B (liquid crystal device) and a change in refractive index anisotropy with temperature change. Uses a retardation plate 53 having optical anisotropy equivalent to that of the liquid crystal device 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device using a liquid crystal device. For more information,
The present invention relates to a technology for improving display performance in a projection display device.

[0002]

2. Description of the Related Art In a liquid crystal device used for various display devices, an electric field is applied to a liquid crystal sealed between a pair of substrates to control an alignment state of the liquid crystal. For example, when the liquid crystal device 100 shown in FIG. 3 is configured in the TN mode, if the rubbing direction is set to intersect between a pair of substrates (the active matrix substrate 3 and the opposing substrate 4), the liquid crystal 39 will It is twisted at a predetermined angle. Such a twist alignment is released by applying an electric field to the liquid crystal 39 between the substrates. Therefore, depending on whether or not an electric field is externally applied between the substrates, the alignment state of the liquid crystal 39 can be controlled for each region (pixel) where the pixel electrode 8 is formed. Further, the degree of the twist orientation can be changed by the applied electric field. Therefore, in the case of the transmissive liquid crystal device 100, as shown in FIG. 11A, the light from the lamp unit 1120 of the white light source is adjusted to a predetermined linearly polarized light by the polarizing plate 51 on the incident side. rear,
The linearly polarized light that enters the liquid crystal layer of the liquid crystal device 100 and passes through a certain region is emitted as elliptically polarized light with its transmission polarization axis twisted, but is not shown, but is linearly polarized light that passes through another region. The light exits without the transmitted polarization axis being twisted. The light emitted from the liquid crystal device 100 as elliptically polarized light is converted into linearly polarized light by the retardation plate 53.
Here, the light passing through the retardation plate 53 and the linearly polarized light passing through the polarizing plate 51 on the incident side have orthogonal transmission polarization axes, so that the polarizing plate 51 on the incident side and the polarizing plate 52 on the emitting side are orthogonal to each other. Are arranged so that their transmission polarization axes are orthogonal to each other (normally white), the liquid crystal 39 twists the transmission polarization axis through the polarizing plate disposed on the emission side of the liquid crystal device 100. Only the linearly polarized light. On the contrary,
If the exit-side polarizing plate is arranged so that the entrance-side polarizing plate and the transmission polarization axis are parallel (normally black), the light passing through the polarizing plate arranged on the exit side of the liquid crystal device 100 can be It is only linearly polarized light whose transmission polarization axis is not twisted by the liquid crystal 39. Therefore, arbitrary information can be displayed by controlling these polarization states for each pixel.

[0003] The transmission type liquid crystal device 10 constructed as described above.
The projection type display device using 0 is configured as shown in FIG. The projection display device 1100 projects a color image in an enlarged manner, and includes a liquid crystal device 100, polarizing plates 51, and 5.
2 and liquid crystal modules 1R, 1
G and 1B are prepared, and each liquid crystal device 100 is set to R (red),
Transmission light valve 100 for G (green) and B (blue)
Used as R, 100G, 100B. Therefore, no color filter is formed in the liquid crystal device used for this type of display device. In this projection display device 1100, when light is emitted from a lamp unit 1120 of a white light source such as a metal halide lamp, three mirrors 1
106 and two dichroic mirrors 1108 cause light from the lamp unit 1120 to be R, G, and B light.
The light components R, G, and B corresponding to the primary colors are separated (light separating means), and the corresponding light valves 100R, 100G, 10
0B (liquid crystal device). The light components R, G, and B corresponding to the three primary colors modulated by the liquid crystal modules 1R, 1G, and 1B (light modulating means) each including the light valves 100R, 100G, and 100B are transmitted to the dichroic prism 1112 (light combining means). After being incident from three directions and synthesized again, it is projected as a color image on a screen 1120 or the like via a projection lens 1114 (projection means).

[0004]

However, in the projection type display device 1100, the lamp unit 11 which is a light source is used.
Since the projector 20 emits very strong light, the liquid crystal module 1
R, 1G, and 1B raise the temperature, and as a result, there is a problem that the refractive index anisotropy of the liquid crystal changes and the contrast characteristic and the color reproducibility in halftone are deteriorated.

[0005] The reason will be described in detail below. First, FIG.
FIG. 12A shows the relationship between the voltage applied to the liquid crystal device 100 and the transmittance of the liquid crystal device 100 alone without the phase difference plate 53 at room temperature, and FIG. 12B shows the arrangement of the phase difference plate 53 at room temperature. In the liquid crystal modules 1R, 1G, and 1B, the relationship between the voltage applied to the liquid crystal device 100 and the transmittance in this state is shown.
By arranging the retardation plate 53 in accordance with the refractive index anisotropy of the liquid crystal device 100 at normal temperature, the solid line L in FIG.
The transmittance-applied voltage characteristic as shown by 21 is secured. Therefore, even when the temperature of the liquid crystal device 100 rises and the refractive index anisotropy of the liquid crystal changes, as shown in FIG. 12C, even when the transmittance-applied voltage characteristic of the liquid crystal device 100 alone changes. In order to perform the same correction for the changed characteristic as when the phase difference plate 53 is at room temperature, the solid line L2 in FIG.
As shown by 2, the transmittance-applied voltage characteristics of the liquid crystal modules 1R, 1G, and 1B greatly change. That is, FIG.
In FIG. 1 (B), when the temperature becomes high, the polarizing plate 51 on the incident side is used.
When the linearly polarized light transmitted through the liquid crystal device 100 is modulated by the liquid crystal device 100, the degree of modulation changes from room temperature. Therefore, after passing through the phase difference plate 53, the light state is not the same as at room temperature. This is because the amount of light passing through the exit-side polarizing plate 52 changes significantly. As a result, the transmittance shown in FIG.
-The applied voltage characteristic changes depending on the temperature, the color reproducibility in halftone is reduced, and as shown in FIG.
Contrast also varies with temperature.

Further, in the projection type display device 1100, since different color lights are incident on the liquid crystal modules 1R, 1G and 1B, they are incident on the liquid crystal modules 1R, 1G and 1B (each of the light valves 100R, 100G and 100B). The wavelength λ of each light of R, G, B is λR, λG, λB, respectively, the thickness d of the liquid crystal layer in each light valve 100R, 100G, 100B is dR, dG, dB, respectively, and each light valve 100R, 100G , 100B, the refractive index anisotropy Δn of the liquid crystal used was ΔnR, ΔnG, ΔnB, respectively.
In the electric field control birefringence mode, the following equation (ΔnR × dR) / λR = (ΔnG × dG) / λG = (ΔnB
× dB) / λB = 1/2 λR = 0.610 μm λG = 0.545 μm λB = 0.450 μm. However, changing the thickness d of the liquid crystal layer or the refractive index anisotropy Δn of the liquid crystal depending on which one of the light valves 100R, 100G, and 100B is used for the liquid crystal device 100 causes a decrease in production efficiency. Therefore,
Conventionally, since the liquid crystal device 100 having the same configuration is used as the light valves 100R, 100G, and 100B, between the light valves 100R, 100G, and 100B,
FIG. 14 shows the relationship between the applied voltage and the transmittance for each color.
As shown by the alternate long and short dash line LR, dotted line LG, and solid line LR, there is a large difference in the transmittance of the incident color light versus the applied voltage when the applied voltage is increased from the lighting state to the off state. Therefore, the conventional projection display device 1100
Then, there is a problem that the color reproducibility in the halftone is low.

[0007] In view of the above problems, an object of the present invention is to provide:
In a projection display device using a liquid crystal device as a light modulating means, even if there is a temperature change in the liquid crystal device, a color image having high color reproducibility in a halftone of a color image and displaying a bright, high-contrast image. It is to provide a configuration that can be used.

Another object of the present invention is to provide a projection type display device using a liquid crystal device as a light modulating means, which has high color reproducibility in a halftone of a color image even if the liquid crystal device changes in temperature. It is an object of the present invention to provide a structure capable of displaying a bright and high-contrast image.

A further object of the present invention is to provide a light modulating means adapted to the color of incident light, whereby the color reproducibility in a halftone of a color image can be further improved. is there.

[0010]

In order to solve the above-mentioned problems, the present invention provides a light source, a color separation means for separating light from the light source into a plurality of color lights, and a plurality of color lights separated by the color separation means. Projection type having a plurality of light modulating means for modulating the color light, a color synthesizing means for synthesizing the color light modulated by the plurality of light modulating means, and a projecting means for projecting the light synthesized by the color synthesizing means. In the display device, the plurality of light modulating units have a liquid crystal device in which liquid crystal is sandwiched between a pair of substrates, and a change in refractive index anisotropy with respect to a temperature change has optical anisotropy equivalent to that of the liquid crystal device. Modulation characteristic correction means.

In this type of technical field, the light modulating means sets the refractive index anisotropy of the liquid crystal used in the liquid crystal device, the thickness of the liquid crystal layer in the liquid crystal device, and the main wavelength of the color light incident on the liquid crystal device to Δn. , D, and λ, when the liquid crystal device is configured as a transmission type, the liquid crystal device is configured to substantially satisfy the following expression (Δn × d) / λ = 1/2 in the electric field control birefringence mode. Is configured as a reflection type, it is configured to substantially satisfy the following expression (Δn × d) / λ = 1/4. In the specification of the present application, the refractive index anisotropy Δn refers to a value obtained by subtracting a refractive index in a direction perpendicular to a refractive index in a direction parallel to an optical axis of a crystal, and a degree in which the refractive index varies depending on the direction. Say.

Here, when the temperature of the liquid crystal changes, the refractive index anisotropy of the liquid crystal also changes, and the retardation changes. However, in the present invention, in order to compensate for such a change in retardation, a retardation plate having a change in refractive index anisotropy with respect to a temperature change having an optical anisotropy equivalent to that of the liquid crystal device is provided on the optical axis of the device. Since the modulation characteristic correction means such as the above is arranged, even if the liquid crystal of the liquid crystal device has a temperature change and its refractive index anisotropy changes, with this temperature change,
The modulation characteristic correcting means also shows a change in the refractive index anisotropy similarly to the liquid crystal device. Therefore, the change in the refractive index anisotropy of the liquid crystal device due to the temperature change is canceled out and compensated by the modulation characteristic correction means. And a bright, high-contrast image can be displayed.

In the present invention, the plurality of light modulating means may have the same relationship between the transmittance or reflectance of the color light modulated by each light modulating means and the voltage applied to the liquid crystal device by the modulation characteristic correcting means. It is preferable that it is comprised so that it may become.

In the present invention, the color separation means separates, for example, light from the light source into blue light, red light, and green light. In this case, as the plurality of light modulating means,
Light modulating means for blue light for modulating the incoming blue light, light modulating means for red light for modulating the incoming red light, and light modulating means for green light for modulating the incoming green light; Will be used.

In the liquid crystal device used in such a projection type display device, the liquid crystal is subjected to an electric field control birefringence mode (ECD / ECD).
Electrically Controlled Bi
Preferably, it is used in a reference mode. In such a mode, the interval between the substrates (the thickness of the liquid crystal layer) can be reduced, so that the response speed can be improved. Also, there is an advantage that the influence (disclination) of a horizontal electric field can be suppressed in the liquid crystal layer.

[0016]

Embodiments of the present invention will be described with reference to the drawings. Note that the liquid crystal device according to this embodiment has the same basic configuration as a liquid crystal device and a projection display device, and therefore, portions having common functions are denoted by the same reference numerals.

Embodiment 1 (Overall Configuration of Liquid Crystal Device) FIG. 1 is a plan view of a liquid crystal device according to the present embodiment as viewed from a counter substrate side. FIG. 2 is a cross-sectional view of the liquid crystal device taken along the line HH 'in FIG.
FIG. 3 is a cross-sectional view of an end portion of a panel showing an active matrix substrate, a counter substrate, and a bonding structure of these substrates used in the liquid crystal device of the present embodiment.

As shown in FIGS. 1, 2 and 3, in a liquid crystal device 100 used for a projection display device or the like, pixel electrodes 8 are formed in a matrix on the surface of a substrate 30 made of quartz glass or heat-resistant glass. Active matrix substrate 3
And a counter substrate 4 in which a counter electrode 32 is formed on the surface of a substrate 31 such as quartz glass or heat-resistant glass, and a liquid crystal 39 sealed and sandwiched between these substrates. The pixel electrode 8 is formed of a transparent conductive film such as an ITO film when the liquid crystal device 100 is of a transmission type, and is formed of a reflective film such as an aluminum film when the liquid crystal device 100 is of a reflection type. .

Active matrix substrate 3 and counter substrate 4
Are bonded together via a predetermined gap (the thickness d of the liquid crystal layer / see FIG. 3) by a gap material-containing sealing material 59 formed along the outer peripheral edge of the counter substrate 4. Also,
Between the active matrix substrate 3 and the counter substrate 4,
The liquid crystal sealing area 4 is formed by the sealing material 59 containing the gap material.
0 is defined, and the liquid crystal 39
Is enclosed.

The opposing substrate 4 is an active matrix substrate 3
And the peripheral portion of the active matrix substrate 3 is bonded to the outer periphery of the counter substrate 4 so as to protrude. Therefore, the drive circuits (the scan line drive circuit 70 and the data line drive circuit 60) and the input / output terminals 45 of the active matrix substrate 3 are exposed from the counter substrate 4. Here, since the sealing material 59 is partially interrupted, the liquid crystal injection port 241 is formed by the interrupted portion. For this reason, after the opposing substrate 4 and the active matrix substrate 3 are bonded to each other, if the inner region of the sealing material 59 is set in a reduced pressure state, the liquid crystal 39 can be injected under reduced pressure from the liquid crystal injection port 241, and after the liquid crystal 39 is sealed, The liquid crystal injection port 241 may be closed with the sealant 242. Note that the active matrix substrate 3 has a structure in which
A light-shielding film 55 for cutting off the screen display area 7 is formed. Further, a light-shielding film 6 is formed on the counter substrate 4 in a region corresponding to a boundary region between the pixel electrodes 8 of the active matrix substrate 3.

The liquid crystal device 100 of this embodiment is for color display, but does not have a color filter.

When the liquid crystal device 100 is formed of a transmission type, the surface on the light incident side and the light emitting side of the counter substrate 4 and the active matrix substrate 3 are provided in accordance with the normally white mode / normally black mode. , Polarizing plate 5
1, 52 are arranged in a predetermined direction. Further, in the example shown in this figure, a phase difference plate 53 (modulation characteristic correction means) described later is arranged between the liquid crystal device 100 and the polarizing plate 52 on the emission side.

As will be described later, when the liquid crystal device 100 is formed of a reflection type, a polarizing plate is disposed only on the light incident side of the opposing substrate 4 and the active matrix substrate 3.

Here, in the liquid crystal device 100, the ECB
When the mode is used, the wavelength λ of the incident light, the refractive index anisotropy Δn of the liquid crystal, and the thickness d of the liquid crystal layer are expressed by the following formula (Δn × d) / λ = 1/2 in the case of the transmission type. In the case of the reflection type, it is configured to substantially satisfy the following expression (Δn × d) / λ = 1/4.

In the liquid crystal device 100 configured as described above, in the active matrix substrate 3, the pixel electrode 8 and the counter electrode 32 are connected to each other by a data line (not shown) and an image signal applied to the pixel electrode 8 via the TFT 10. During this period, the alignment state of the liquid crystal 39 is controlled for each pixel, and a predetermined image corresponding to the image signal is displayed. Therefore, in the active matrix substrate 3, it is necessary to supply an image signal to the pixel electrode 8 via the data line and the TFT 10 and to apply a predetermined potential to the counter electrode 32. Therefore, in the liquid crystal device 100, the active matrix substrate 3
The first electrode 47 for vertical conduction made of an aluminum film (light-shielding material) is formed on a portion of the surface of the surface opposite to each corner of the opposing substrate 4 with the aid of a process of forming a data line or the like. ing. On the other hand, at each corner of the opposing substrate 4, ITO is formed with the help of the process of forming the opposing electrode 4.
Second electrode 4 made of a film (light transmitting material) for vertical conduction
8 are formed. Further, the first electrode 47 and the second electrode 48 for vertical conduction are electrically connected by a conductive material 56 in which conductive particles such as silver powder and gold-plated fiber are mixed with an epoxy resin-based adhesive component. Conducted. Therefore, in the liquid crystal device 100, the active matrix substrate 3 is connected only to the active matrix substrate 3 without connecting the flexible wiring substrate or the like to each of the active matrix substrate 3 and the counter substrate 4. A predetermined signal can be inputted to both the counter substrate 4 and the counter substrate 4.

To manufacture the liquid crystal device 100 having such a configuration, the counter electrode 32 and the light shielding film 6 are formed on the surface of the substrate 31.
Are sequentially formed, and an alignment film 49 made of a polyimide resin or the like is formed on the surfaces of the light shielding film 6 and the counter electrode 32.
On the other hand, in order to form the active matrix substrate 3, after the TFT 10 and the pixel electrode 8 are sequentially formed on the surface of the quartz glass 31, an alignment film 46 made of a polyimide resin or the like is also formed on the surface of the pixel electrode 8.

Next, an uncured sealing material 59 containing a gap material is applied onto the surface of the active matrix substrate 3 while being discharged from a dispenser. On the surface of the active matrix substrate 3, an uncured conductive material 56 for vertical conduction is applied while being discharged from a dot-type dispenser on the outer periphery of the surface of the active matrix substrate 3 slightly beyond the application region. In the present embodiment, as the conductive material 56, a material obtained by mixing conductive particles such as silver powder and gold-plated fiber with an epoxy resin-based adhesive component having photocurability is used. As the sealing material 59 containing the gap material, similarly to the conductive material 56, an epoxy resin-based adhesive component having photocurability, for example, an inorganic or organic fiber having a predetermined diameter, such as a product name 3025 manufactured by Three Bond Co., Ltd. Alternatively, a material containing about 5% of a gap material composed of a sphere is used.

Next, the vertical conductive second electrode 48 formed on the counter substrate 4 is opposed to the vertical conductive first electrode 47 formed on the active matrix substrate 3. After the opposing substrate 4 and the active matrix substrate 3 are aligned, the active matrix substrate 3
While pressing the opposing substrate 4 toward, ultraviolet rays are irradiated from the opposing substrate 4 side, and the conductive material 56 and the sealing material 59 are cured. As a result, the opposing substrate 4 and the active matrix substrate 3 are bonded together with a predetermined gap therebetween, and
The first electrode 47 for vertical conduction formed on the active matrix substrate 3 and the second electrode 48 for vertical conduction formed on the counter substrate 4 are electrically connected via the conductive material 56. .

In manufacturing the liquid crystal device 100 in this manner, in order to configure the liquid crystal device 100 in a homogeneous electric field control birefringence mode, in the present embodiment, both the active matrix substrate 3 and the opposing substrate 4 are used. Then, the alignment films 46 and 49 subjected to the parallel alignment processing are formed. Therefore, between the active matrix substrate 3 and the opposing substrate 4, the liquid crystal 39 has a homogeneous alignment in which liquid crystal molecules are parallel to both substrate surfaces and oriented in the same direction. Here, as the liquid crystal, dielectric anisotropy Δε
Uses a positive nematic liquid crystal. This dielectric anisotropy Δ
ε refers to a value obtained by subtracting the dielectric constant in the vertical direction from the dielectric constant in the direction parallel to the arrangement direction of the crystal molecules, and refers to the degree to which the dielectric constant varies depending on the direction.

For example, an alignment film 4 in which both the active matrix substrate 3 and the counter substrate 4 are subjected to a parallel alignment process
6 and 49, and the thickness d of the liquid crystal layer is set to 1.9.
It is set to 4 μm, and the dielectric anisotropy Δε is 3.
0, NI point (clearing point) is 91 ° C., viscosity is 12 cps,
A material having a refractive index anisotropy Δn of 0.1332 is used.

The liquid crystal device 100 is of the HAN type (Hyb).
(rid-Aligned Nematic) In the case of the electric field control birefringence mode, one of the active matrix substrate 3 and the counter substrate 4 is formed with an alignment film subjected to a parallel alignment process, and the other substrate is subjected to a vertical alignment process. Oriented alignment films may be formed. In this case, between the active matrix substrate 3 and the counter substrate 4,
The liquid crystal 39 has a hybrid alignment in which liquid crystal molecules are arranged parallel to one substrate surface and perpendicular to the other substrate, and the entire molecular arrangement is bent by 90 ° between both substrates. Here, as the liquid crystal 39, either a nematic liquid crystal having a positive dielectric anisotropy or a negative nematic liquid crystal may be used.

In such a mode, the interval between the substrates (the thickness of the liquid crystal layer) can be reduced, so that the response speed can be improved. Also, there is an advantage that the influence (disclination) of a horizontal electric field can be suppressed in the liquid crystal layer.

FIG. 4 is a block diagram schematically showing the configuration of the liquid crystal device 100.

As shown in FIG. 4, a TFT 10 for pixel switching connected to the data line 90 and the scanning line 91 is provided on the active matrix substrate 3.
There is a liquid crystal cell 94 to which an image signal is input from the data line 90 through the LCD. For the data line 90, a data line drive circuit 60 including a shift register 84, a level shifter 85, a video line 87, and an analog switch 86 is formed. For the scanning line 91, a scanning line driving circuit 7 including a shift register 88 and a level shifter 89
0 is formed.

In the pixel area, a storage capacitor 40 (capacitive element) is formed between the storage capacitor 40 and the capacitor line 92.
The liquid crystal cell 94 has a function of improving charge retention characteristics. Incidentally, the storage capacitor 40 may be formed between the scanning line 91 and the preceding stage.

Here, when the liquid crystal device 100 is configured as a reflective type, the pixel electrode 8 is configured as a reflective electrode such as an aluminum film.

(Overall Configuration of Projection Display Device) A projection display device using the transmission type liquid crystal device 100 configured as described above is configured as shown in FIG.

FIG. 5 is a schematic configuration diagram of a projection type display device using a transmission type liquid crystal device.

The projection type display device 1100 shown in FIG.
A liquid crystal module 1R, 1G, 1L includes a liquid crystal device 100, polarizing plates 51 and 52, and a phase difference plate 53 described with reference to FIGS.
B (light modulating means) are prepared, and each liquid crystal device is set to R
Used as transmission light valves 100R, 100G, and 100B for (red), G (green), and B (blue). Therefore,
No color filter is formed in the liquid crystal device used for this type of display device. This projection display device 110
0, when light is emitted from a lamp unit 1120 of a white light source such as a metal halide lamp, three mirrors 1106 and two dichroic mirrors 110 are provided.
8, light from the lamp unit 1120 is R, G,
The light components are separated into light components R, G, and B corresponding to the three primary colors B (light separation means), and the corresponding light valves 100R, 100R
G, 100B (liquid crystal device). At this time,
Since the blue light component B has a long optical path, the blue light component B is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an emission lens 1124 in order to prevent light loss. Then, the liquid crystal modules 1R, 1G, 1
Light components R, G, and B corresponding to the three primary colors modulated by the B light valves 100R, 100G, and 100B, respectively.
Are incident on a dichroic prism 1112 (light combining means) from three directions and are combined again, after which the projection lens 1
Screen 1120 via 114 (enlarged projection optical system)
Is projected as a color image.

FIGS. 6 (A) and 6 (B) are schematic diagrams each showing a state where the light modulation effect does not change before and after the temperature rise in each liquid crystal module (light modulation means) used in the projection type display device to which the present invention is applied. FIG.

When performing display in this manner, the liquid crystal modules 1R, 1G, and 1B (light modulating means) convert the light R, G, and B from the lamp unit 1120 and the light separating means as described below. Modulate. First, as shown in FIG. 6A, the light from the lamp unit 1120 of the white light source is separated into each color R, G, and B, and is then adjusted to a predetermined linearly polarized light by the incident-side polarizing plate 51. In this state, the linearly polarized light that enters the liquid crystal layer of each of the light valves 100R, 100G, and 100B (the liquid crystal device 100) and transmits through a certain region is emitted as elliptically polarized light while the transmission polarization axis is twisted. Although not shown, the linearly polarized light that has passed through other regions is emitted without the transmitted polarization axis being twisted.
And each light valve 100R, 100G, 100B
The light emitted as elliptically polarized light from is converted into linearly polarized light by the phase difference plate 53. Here, the light that has passed through the phase difference plate 53 and the linearly polarized light that has passed through the polarizing plate 51 on the incident side are:
Since the transmission polarization axes are orthogonal to each other, if the incident-side polarization plate 51 and the emission-side polarization plate 52 are arranged so that their transmission polarization axes are orthogonal to each other (normally white), the liquid crystal device 10
The light passing through the polarizing plate disposed on the exit side of the liquid crystal 3
9 is only linearly polarized light whose transmission polarization axis is twisted. On the other hand, if the exit-side polarizing plate is arranged so that the incident-side polarizing plate and the transmission polarization axis are parallel (normally black), the polarizing plate arranged on the exit side of the liquid crystal device 100 can be used. Only linearly polarized light whose transmitted polarization axis has not been twisted by the liquid crystal 39 passes through. Therefore, arbitrary information can be displayed by controlling these polarization states for each pixel.

(Measures for Temperature Change of Liquid Crystal Module / Light Modulating Means) Here, the liquid crystal modules 1R, 1G, and 1B have a phase difference so that modulation can be performed properly even when the temperature is increased by light from the lamp unit 1120. As the plate 53, one having a refractive index anisotropy as described below is used.

First, in the present embodiment, FIG. 7A shows a liquid crystal device 1 as a single liquid crystal device 100 without a retardation plate 53 at normal temperature.
FIG. 7B shows the relationship between the applied voltage to 00 and the transmittance.
Liquid crystal device 1 with a retardation plate 53 at room temperature
In the liquid crystal modules 1R, 1G, and 1B, the retardation plate 53 is arranged in accordance with the refractive index anisotropy of the liquid crystal device 100 at normal temperature, as indicated by a solid line L11 indicating the relationship between the applied voltage to 00 and the transmittance. As a result, proper transmittance-applied voltage characteristics are secured.

In this embodiment, the phase difference plate 53 is
The temperature of the light valves 100R, 100G, 100B (the liquid crystal device 100) rises, and the refractive index anisotropy of the liquid crystal changes,
As shown in FIG. 7C, the transmittance of the liquid crystal device 100 alone.
-A uniaxially stretched polymer film having a refractive index anisotropy that compensates for such a change in the refractive index anisotropy even when the applied voltage characteristic changes. That is, as the retardation plate 53, one having a change in refractive index anisotropy with respect to a temperature change equivalent to that of the light valves 100R, 100G, and 100B alone is used. For this reason, in this embodiment, the light valve 1
When the refractive index anisotropy changes due to the temperature rise of 00R, 100G, and 100B, the phase difference plate 53 also increases the temperature and the refractive index anisotropy changes. Therefore, as shown by the solid line 12 in FIG. Even after the temperature rises, the liquid crystal modules 1R, 1G,
The transmittance-applied voltage characteristic when viewed as 1B is equivalent to the characteristic before the temperature rise (the characteristic indicated by the solid line L11 in FIG. 7B).

Therefore, as shown in FIG. 6B, when the linearly polarized light transmitted through the polarizing plate 51 on the incident side is modulated by the liquid crystal device 100, even if the degree of modulation changes from room temperature. The change is canceled by the phase difference plate 53 and corrected, and the light is emitted as linearly polarized light. Therefore, even if there is a temperature change, the light amount emitted from the polarizing plate 52 on the emission side does not change. Further, since the transmittance-applied voltage characteristic does not change even when the condition optimally set at normal temperature becomes high, the contrast characteristic does not change.

(Measures for Matching Liquid Crystal Module / Light Modulating Means to Each Color) Further, in the present embodiment, each liquid crystal module 1
Since the light incident on R, 1G, and 1B is different, the liquid crystal modules 1R, 1G, and 1B are configured to match these colors.

That is, in the projection type display device 1100,
Since different color lights are incident on the liquid crystal modules 1R, 1G, and 1B, respectively, the wavelength λ of each of the R, G, and B light incident on each of the liquid crystal modules 1R, 1G, and 1B (each of the light valves 100R, 100G, and 100B) is determined. ΛR, λG, λB respectively
And the thickness d of the liquid crystal layer in each of the light valves 100R, 100G, 100B is dR, dG, dB, respectively.
The refractive index anisotropy Δn of the liquid crystal used for each of the light valves 100R, 100G, 100B is represented by ΔnR, ΔnG, Δn, respectively.
When B is set, in the ECB mode, the following equation is used: (ΔnR × dR) / λR = (ΔnG × dG) / λG = (ΔnB
× dB) / λB = 1/2 λR = 0.610 μm λG = 0.545 μm λB = 0.450 μm, but each light valve 100R, 10R
Having different configurations for 0G and 100B causes a decrease in production efficiency. Therefore, in the present embodiment, the retardation plate 53 used in each of the liquid crystal modules 1R, 1G, and 1B is shown in FIG.
4 each light valve 100R, 100G, 100B
Is used to correct the characteristic difference. That is, in the present embodiment, in each of the liquid crystal modules 1R, 1G, and 1B, the refractive index anisotropy Δn of the liquid crystal is 0.1332, the thickness d of the liquid crystal layer is 1.94 μm, and the dielectric anisotropy Δε of the liquid crystal is 3 .
0, since the NI point (clearing point) is 91 ° C. and the viscosity is 12 cps, any of the light valves 100R, 100G,
100B also has a retardation Δnd of 0.258, whereas the light valve 100G has a Δnd / λG of 0.47.
3, light valves 100R, 100B
Δnd / λR and Δnd / λB are 0.423, respectively.
0.573. Therefore, in this embodiment, Δn / between the light valves 100R, 100G, and 100B.
A phase difference plate 53 capable of absorbing and compensating for the difference in λ is used.
Therefore, according to the present embodiment, each light valve 100R, 1
This is equivalent to adjusting the retardation in accordance with the main wavelength of light incident on 00G and 100B.

FIG. 8 shows the transmittance of each color R, G, B.
-As shown by the alternate long and short dash line LR, dotted line LG and solid line LR, the applied light voltage characteristics of each light valve 100R, 100G, 10G
0B, the transmittance for the color light modulated by each of the liquid crystal modules 1R, 1G, and 1B and the light valves 100R and 100R, even if the main wavelengths of the incoming light are different.
The relationship (modulation characteristic) between G and 100B and the applied voltage is the same between the liquid crystal modules 1R, 1G and 1B. Therefore, according to the projection display device 11002 of the present embodiment, the color reproducibility in the halftone of the color image can be improved.

In this embodiment, the liquid crystal module 1R,
Since the configuration as the liquid crystal device 100 is common between 1G and 1B, only the presence or absence and type of the phase difference plate 53 are different.
When manufacturing each of the light valves 100R, 100G, and 100B, there is an advantage that the distance between the substrates (the thickness d of the liquid crystal layer) and the liquid crystal material can be made the same.

[Embodiment 2] In the above embodiment, a transmissive liquid crystal device 100 is used. However, the present invention is applied to a case where a reflection type liquid crystal device 100 is used to form a projection display device. Is also good.

FIG. 9 is a schematic structural view of a projection type display device using a reflection type liquid crystal device.

As shown in FIG. 9, the reflection type liquid crystal device 10
0, the light source unit 110 and the integrator lens 12 along the system optical axis L.
0, polarization illumination device 140 including polarization conversion element 130
And a polarizing beam splitter 200 that reflects the polarized light beam emitted from the polarized light illuminating device 140 by the S-polarized light beam reflecting surface 201, and blue light (B) of the light reflected from the S-polarized light reflecting surface 201 of the polarized beam splitter 200. ) And a reflection type light valve 100B that modulates the separated blue light (B).
, A dichroic mirror 413 that reflects and separates the red light (R) component of the light beam after the blue light is separated, and a liquid crystal module 1B (light modulation unit) that separates the separated red light (R). Modulating reflective light valve 10
A liquid crystal module 1R (light modulating means) having an OR, a liquid crystal module 1G (light modulating means) having a reflective light valve 100G for modulating the remaining green light (G) passing through the dichroic mirror 413, and three lights. The light modulated by the valves 1R, 1G, and 1B is applied to the dichroic mirrors 412, 413 and the polarization beam splitter 20.
0 (synthesizing means), and the synthesized light is
A magnified projection optical system 50 comprising a projection lens for projecting at 00
0 (projection means).

The above three reflective light valves 1R, 1R
G and 1B and the liquid crystal modules 1R, 1G and 1B are basically the same as those in the first embodiment, but the reflection type liquid crystal device 100 is used and the projection type display device 2 is used.
In the case of configuring the liquid crystal device 100, as shown in FIG. 10, of the two surfaces of the liquid crystal device 100, the side on which the polarizing plate 51 is disposed is the light incident side and the light output side. 53 may be arranged.

[Other Embodiments] In the third embodiment and the first and second modifications thereof, means for correcting the modulation characteristics of the liquid crystal modules 1R, 1G, and 1B (light modulation means) are provided. Although the retardation plate 53 is used, a liquid crystal cell in which liquid crystal is sandwiched between a pair of substrates may be used as long as it has such optical anisotropy.

In each of the above embodiments, an active matrix type liquid crystal device has been described as an example. However, the present invention may be applied to a display device using a passive matrix type liquid crystal device.

[0056]

As described above, when the temperature of the liquid crystal changes in the liquid crystal device used for the projection display device, the refractive index anisotropy of the liquid crystal also changes, and the retardation changes. In order to compensate for such a change in retardation, a modulation characteristic correcting unit having a change in refractive index anisotropy with respect to a temperature change having optical anisotropy equivalent to that of a liquid crystal device is arranged on the optical axis of the device. For this reason, even if the liquid crystal of the liquid crystal device has a temperature change and its refractive index anisotropy changes, the modulation characteristic correction means also has the same refractive index anisotropy as the liquid crystal device. The modulation characteristic correcting means compensates for the change in the refractive index anisotropy of the liquid crystal device due to the change and the temperature change. Therefore, even if there is a temperature change in the liquid crystal device,
A color image with high color reproducibility in a halftone of a color image, and a bright image with good contrast can be displayed.

[Brief description of the drawings]

FIG. 1 is a plan view of a liquid crystal device viewed from a counter substrate side.

FIG. 2 is a cross-sectional view of the liquid crystal device taken along the line HH ′ in FIG.

3 is a cross-sectional view of an end portion of a panel showing an active matrix substrate and a counter substrate used in the liquid crystal device shown in FIG. 1 and a bonding structure of these substrates.

FIG. 4 is a block diagram schematically illustrating a configuration of a liquid crystal device.

FIG. 5 is a schematic configuration diagram of a projection display device using a transmission type liquid crystal device.

FIGS. 6A and 6B are schematic diagrams each showing a state in which a light modulation effect does not change before and after a temperature rise in each liquid crystal module (light modulation unit) used in a projection display device to which the present invention is applied. FIG.

FIG. 7 (A), (B), (C), (D)
In each liquid crystal module (light modulating means) used in the projection type display device to which the present invention is applied, the liquid crystal device alone before the temperature rise, the liquid crystal module before the temperature rise, the liquid crystal device alone after the temperature rise, and the liquid crystal device after the temperature rise 4 is a graph schematically showing a relationship between a transmittance of a liquid crystal module device and an applied voltage.

FIG. 8 is a graph showing the relationship between the transmittance for the color light modulated by each liquid crystal module and the voltage applied to the liquid crystal device in each liquid crystal module (light modulating means) used in the projection type display device to which the present invention is applied. is there.

FIG. 9 is a schematic configuration diagram of a projection display device using a reflective liquid crystal device.

FIG. 10 is a cross-sectional view illustrating a configuration of a liquid crystal module using a reflective liquid crystal device.

FIGS. 11A and 11B are diagrams each schematically showing a state in which a light modulation action changes before and after a temperature rise in each liquid crystal module (light modulation means) used in a conventional projection display device. FIG.

12 (A), (B), (C), and (D) show a liquid crystal module (light modulating means) used in a conventional projection display device, a liquid crystal device alone before a temperature rise,
4 is a graph schematically showing the relationship between the transmittance and the applied voltage of the liquid crystal module before the temperature rise, the single liquid crystal device after the temperature rise, and the liquid crystal module device after the temperature rise.

FIGS. 13A and 13B are graphs showing how the relationship between transmittance and applied voltage changes with temperature in each liquid crystal module (light modulating means) used in a conventional projection display device. And a graph showing how the contrast changes with temperature.

FIG. 14 is a graph showing the relationship between the transmittance for the color light modulated by each liquid crystal module and the voltage applied to the liquid crystal device in each liquid crystal module (light modulation means) used in the conventional projection display device.

[Explanation of symbols]

 1R, 1G, 1B Liquid crystal module (light modulating means) 3 Active matrix substrate 4 Counter substrate 8 Pixel electrode 10 TFT for pixel switching 30, 31 Substrate 32 Counter electrode 39 Liquid crystal 51, 52 Polarizing plate 53 Phase difference plate (Modulation characteristic correction Means) 100 Liquid crystal device 100R, 100G, 100B Light valve 1100, 2100 Projection display device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA15 HA13 HA16 HA18 HA21 HA22 HA24 HA28 JA09 MA20 2H093 NA16 NA62 NC34 ND58 NE06 NF09 NG02

Claims (4)

[Claims] A light source; a color separation unit configured to separate the light from the light source into a plurality of color lights; a plurality of light modulation units configured to modulate the plurality of color lights separated by the color separation unit; In a projection display device including a color combining unit that combines the color lights modulated by the modulation unit and a projection unit that projects the light combined by the color combining unit, the plurality of light modulation units include a pair of substrates. A liquid crystal device having a liquid crystal interposed therebetween, and a modulation characteristic correcting means having a change in refractive index anisotropy with temperature change having an optical anisotropy equivalent to that of the liquid crystal. apparatus. 2. The liquid crystal device according to claim 1, wherein the plurality of light modulating units are configured to have a relationship between a transmittance or a reflectance of the color light modulated by each of the light modulating units and a voltage applied to the liquid crystal device. Characterized in that they are configured to be equal to each other. 3. The color separation unit according to claim 1, wherein the color separation unit separates light from the light source into red light, green light, and blue light, and the plurality of light modulation units receive red light. A projection display device comprising: a light modulating means for red light; a light modulating means for green light on which green light is incident; and a light modulating means for blue light on which blue light is incident. 4. The method according to claim 1, wherein
The liquid crystal device is used in an electric field control birefringence mode.