JP2003021830A - Projection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type liquid crystal display device which is small-sized and inexpensive, has a high light utilization rate and can enhance the luminance. SOLUTION: In a projection type liquid crystal display device A, white light from a white light source 1 is separated into two P-polarized light and S-polarized light having the directions of polarization orthogonal to each other by using a polarizing beam splitter 9. The S-polarized light is made to pass a rotary two-color color filter 7 which allows two colors R and B to alternately pass through, and then luminance modulation is performed with a first liquid crystal light valve 12 to obtain optical modulation signals of two colors R and B. The P-polarized light is converted to S- polarized light by passing through a phase difference plate 10, and then only color G is allowed to pass through a G filter 16 by using a second liquid crystal light valve 15 to obtain an optical modulation signal of the color G. These optical modulation signals are optically combined by a dichroic prism 13 to form a color image, which is magnified and projected through a projection lens 18. This projection type liquid crystal display device is constituted in a smaller size at a lower cost in comparison with a three CCD type device and improves the light utilization efficiency and the luminance in comparison with a single-plate type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type liquid crystal which uses a liquid crystal display panel as a light valve to modulate light from a light source in accordance with image information and then forms a projection image on a screen by a projection lens. The present invention relates to a display device.

[0002]

2. Description of the Related Art A conventional general projection type liquid crystal display device is a single plate type device which realizes full color by using one liquid crystal display panel, and white light is separated into three primary colors of light. There is a three-plate system in which the luminance signal is modulated by three monochrome liquid crystal display panels corresponding to three colors, and then the color image obtained by combining these light modulation signals is projected on the screen by the projection lens. is there.

FIG. 6 is a block diagram of a single-panel projection type liquid crystal display device using a conventional liquid crystal display panel with a color filter. FIG. 7 is a schematic diagram showing an array of colors of a color filter used in the single plate type of FIG.

In a conventional single-panel projection type liquid crystal display device using a liquid crystal display panel with a color filter, as shown in FIG. 6, white light emitted from a white light source 102 is condensed by a condenser mirror 101. After that, the cold mirror 103 and the UVIR cut filter 104 remove unnecessary ultraviolet light and infrared light. Next, the condenser lens 11
The light is condensed by 1 and enters the liquid crystal display panel 118 on which the color filter 119 is mounted, is subjected to light modulation corresponding to image information, and is projected on a screen (not shown) via the projection lens 117. It As a result, a full-color projection image is formed on the screen.

In this system, the color filter 119 is
The color filters 119 are composed of color filters of R, G, and B arranged as shown in FIG.
However, there is a problem that it is difficult to obtain high brightness because of low transmittance. Further, since 3 pixels are required for colorization, there is a problem that a high-resolution projected image cannot be expected.

Next, FIG. 8 is a configuration diagram of a conventional single-panel projection type liquid crystal display device using a reflection-type liquid crystal display panel, and FIG. 9 is a diagram showing the colors of the color filters used in the single-plate type of FIG. It is a schematic diagram which shows the arrangement | sequence of. In addition, FIG.
FIG. 9 is a luminance response characteristic diagram of each of R, G, and B colors obtained by the single plate type of FIG. 8.

The single-plate projection type liquid crystal display device shown in these figures adopts a system in which a rotating plate is provided in front of one light valve and RGB three primary color filters are arranged on this rotating plate for colorization. is doing. This system has already been realized by DMD (Digital Micromirror Device).

When this rotating plate is used in a single-panel projection type liquid crystal display device using a conventional reflection type liquid crystal display panel, as shown in FIG. After being collected at, cold mirror 10
3 and UVIR cut filter 104 removes unnecessary ultraviolet light and infrared light. Next, after passing through a color filter 120 that produces three primary colors from white light over time, it is condensed by a condenser lens 111, folded back by a polarization beam splitter 123, and made incident on a reflection type liquid crystal display panel 122. The reflected light subjected to the corresponding modulation is guided to the projection lens 117.

As shown in FIG. 9, the color filters 120 are arranged such that R, G, and B color filters are arranged concentrically, and the rotation frequency of the drive motor 121 is changed to a reflection type liquid crystal display panel 122. A color image is obtained by rotating the color filter 120 at the same frequency as the vertical driving frequency of.

Therefore, the rotational speed of the color filter 120 and the vertical driving frequency of the reflective liquid crystal display panel 122 are
A frequency three times as high as the vertical drive frequency of the image to be projected is required, and it is necessary to operate at high speed. Therefore, the luminance response characteristics of each color of R, G, and B obtained as the reflected light from the reflection type liquid crystal display panel 122 becomes a triangular wave characteristic as shown in FIG. 10, which is obtained by mixing these colors. In addition, there is a problem that color images have color unevenness and it is difficult to obtain high brightness.

On the other hand, as shown in FIG. 11, in the conventional three-panel projection type liquid crystal display panel, after the white light emitted from the white light source 102 is condensed by the condenser mirror 101, the cold mirror 103 and the UVIR. Unnecessary ultraviolet light and infrared light are removed by the cut filter 104, separated into three RGB colors by the dichroic mirrors 105, 106 and 107, reflected by the reflection mirrors 108 and 109, and then separated into three lights corresponding to the respective lights. LCD display panel 1
Light modulation is performed by 10, 112, and 113, and thereafter, the light is optically combined by the color combining prism 115 to generate a full-color image.

In the above-mentioned three-plate type, approximately three times as much brightness can be obtained under the same conditions as in the single-plate type, and high definition can be easily achieved. However, there is a problem that the number of parts increases and the light synthesizing method becomes complicated, resulting in high cost.

[0013]

As described above, in the projection type liquid crystal display device of the related art, in the transmission type single plate type, the color filter absorbs and reflects the irradiation light.
There is a problem that it is difficult to increase the brightness and the resolution is poor at the same time. Further, in the single plate type using the reflection type liquid crystal display panel, it is necessary to increase the rotation frequency of the color filter and the vertical drive frequency of the reflection type liquid crystal display panel. There is a problem that uniformity occurs and it is difficult to increase the brightness. Further, in the three-plate type, the number of parts is increased and the light synthesizing means is complicated, so that there is a problem that the cost is high and the device is large.

Therefore, an object of the present invention is to solve the above problems, to provide a projection type liquid crystal display device which can realize a small size and a low price, and at the same time have a high light utilization rate and a high brightness. is there.

[0015]

In order to solve the above problems, the present invention provides a projection type liquid crystal display in which light from a light source is modulated by a liquid crystal light valve in accordance with image information and projected by a projection lens. In the device, a polarization splitting unit that splits the light from the light source into two linearly polarized lights whose polarization directions are orthogonal to each other, and one of the linearly polarized lights split by the polarization splitting unit A rotary two-color color filter that produces a light flux of two-color components over time, a first liquid crystal light valve that transmits or reflects the light flux that has passed through the rotary two-color color filter according to a luminance signal, and the polarization separation. A monochromatic color filter for separating the light flux of the remaining one color component of the three primary colors of light from the other linearly polarized light separated by the means, and this monochromatic color filter A second liquid crystal light valve for the separated light is transmitted or reflected according to the luminance signal, the first
And an image synthesizing unit for synthesizing the two-color image and the single-color image respectively output from the second liquid crystal light valve to obtain a color image, and a projecting unit for enlarging and projecting the image synthesized by the image synthesizing unit. It is characterized by being.

Here, in order to align the polarization directions of the separated linearly polarized light, a π / 2 phase difference plate is arranged on the incident side of the first liquid crystal light valve or the second liquid crystal light valve. do it.

Next, according to the present invention, in a projection liquid crystal display device using a reflection type liquid crystal light valve, linearly polarized light generating means for converting light from the light source into linearly polarized light having a uniform polarization direction. A color separating unit that separates the linearly polarized light generated by the linearly polarized light generating unit into two color components of the three primary colors of light and the remaining one color component; Rotation type 2 that creates a light flux of two color components of the three primary colors of light from a light flux of color components over time
A color color filter, a first liquid crystal light valve that reflects the light flux that has passed through the rotary two-color color filter according to a luminance signal, and a light flux of the remaining one color component separated by the color separation means as a luminance signal. The second to reflect accordingly
The liquid crystal light valve, the image synthesizing means for synthesizing the two-color image and the single-color image respectively output from the first and second liquid crystal light valves to obtain a color image, and the image synthesized by the image synthesizing means is enlarged. It has a projection means for projecting.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection type liquid crystal display device to which the present invention is applied will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic configuration diagram showing an optical system of a projection type liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of the color filter, and FIG. 3 is a luminance response characteristic diagram thereof.

First, referring to FIG. 1, in the projection type liquid crystal display device A of this example, white light from the white light source 2 is converted into two linearly polarized lights whose polarization directions are orthogonal to each other by the polarization beam splitter 9. After passing one light beam, for example, S-polarized light, through a rotary filter 7 that separates it into certain P-polarized light and S-polarized light and alternately passes two colors of R and B,
Brightness modulation is performed by the liquid crystal light valve 12 to obtain R and B two-color light modulation signals. The other P-polarized light, which is the other linearly-polarized light, passes through the π / 2 phase difference plate 10 to be P-polarized light, and then only the G-color light passes through the G filter 16. G
The color light is converted into a G-color light modulation signal by the second liquid crystal light valve 15. The R, B, and G light modulation signals are photosynthesized by the dichroic prism 13 to form a color image, which is projected through a projection lens 18 onto a screen (not shown).

More specifically, the white light from the white light source 2 is collected forward by the condenser mirror 1, condensed by the condenser lens 3, and then collected by the cold mirror 4 and the UVIR cut filter 5. The infrared light is removed to become only visible light, and two linearly polarized lights P and S whose polarization directions are orthogonal to each other by the polarization beam splitter 9.
Is separated into

S separated by the polarization beam splitter 9
After the wave component is reflected by the reflection mirror 8, the wave component passes through the rotary filter 7 in which the R and B filters of the configuration shown in FIG. 2 are alternately arranged, and is condensed by the condenser lens 11.
It is added to the first liquid crystal light valve 12. The rotary filter 7 controls the rotation speed of the drive motor 6 so that R
It is a filter that alternately passes the colors B and B.

On the other hand, the P-wave component from the polarization beam splitter 9 is converted from P-wave to S-wave by the phase difference plate 10, and then reflected by the reflection mirror 17 to be reflected by the G-color filter 16.
Then, only the G color passes and is condensed by the condenser lens 14 and then added to the second liquid crystal light valve 15.

The dichroic prism 13 has R and B
The second liquid crystal light valve 1 and the light emitted from the first liquid crystal light valve 12 have a characteristic of passing G and reflecting G.
The emitted lights of No. 5 are combined by the dichroic prism 13 and enlarged and projected by the projection lens 18.

At this time, the vertical drive frequency of the first liquid crystal light valve 12 is set to be twice the vertical drive frequency of the second liquid crystal light valve 15 to synchronize the full-color RGB three-color modulation signals. You can get a video.

FIG. 3 shows the second liquid crystal display panel 15 at this time.
It shows that the luminance characteristics of R and B obtained in step 1 are obtained. Since the rotation frequency of the rotary filter 7 and the vertical drive frequency of the second liquid crystal light valve can be suppressed low, good luminance response characteristics can be obtained. .

FIG. 4 shows a modification of the projection type liquid crystal display device A shown in FIG. 1. In the projection type liquid crystal display device B shown here, the phase difference plate 10 in FIG. It is arranged on the side of the rotary plate 7 having a filter, and the same effect as the projection type liquid crystal display device A according to the first embodiment can be obtained.

In each of the above examples, the S-wave component is guided to the first liquid crystal light valve 12 and the P-wave component is guided to the second liquid crystal light valve 15, but the reverse is true. Polarization separation may be performed.

(Second Embodiment) The present invention has been described above based on an embodiment using a transmissive liquid crystal light valve, but the same applies to the case where a reflective liquid crystal light valve is used. With the above configuration, the same effect can be obtained.

FIG. 5 is a schematic configuration diagram showing an example of an optical system of a projection type liquid crystal display device using a reflection type liquid crystal light valve to which the present invention is applied. As shown in this figure, the projection type liquid crystal display device C emits light from a white light source 2 and a condenser mirror 1
It has a linearly polarized light generation unit 21 for converting the light reflected by and obtained through the condenser lens 3 into linearly polarized light having a uniform polarization direction. For example, P-polarized light is obtained by the linearly-polarized light generation unit 21. P-polarized light is
Color filter 2 reflected by cold mirror 4
Guided to 2. The color filter 22 is a color separation unit that separates the P-polarized light into two color components R and B of the three primary colors of light and the remaining one color component G.

2 separated by color filter 22
From the light fluxes of the color components R and B, the rotary two-color filter 7
Thus, the light fluxes of the two color components R and B are produced with time. Each of the R and B luminous fluxes passes through a dichroic mirror 23, which serves as a polarized light separating means, and is reflected first
Incident on the liquid crystal light valve 24, is subjected to the modulation corresponding to the image information, and is reflected in a state in which the polarization direction is rotated by 90 degrees, and is again reflected by the dichroic mirror 23.
To the dichroic prism 13, which is an image synthesizing means.

On the other hand, the light flux of the remaining one-color component G separated by the color filter 22 enters the second liquid crystal light valve 26 through the reflection mirror 25 and undergoes the modulation corresponding to the image information. The dichroic prism 13 receives the light and reflects it while rotating the polarization direction by 90 degrees.
Incident on.

In the dichroic prism 13, the modulated lights of the respective colors are combined to form a color image.
It is enlarged and projected on the screen through the projection lens 18.

[0034]

As described above, according to the projection type liquid crystal display device of the present invention, a full-color image can be obtained with two liquid crystal light valves, so that the conventional three liquid crystal light valves are used. Compared to the three-plate type, the structure is simpler and the manufacturing cost is lower.

Further, since all the two linearly polarized lights (P wave and S wave) are used, the light utilization rate is very high and a projected image with high brightness can be realized.

Further, since the vertical driving frequency of the liquid crystal light valve can be suppressed lower than that of the conventional single plate type, the luminance response characteristic of the liquid crystal light valve can be improved. Therefore, a color image with good color purity can be obtained and high brightness can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical system of a first embodiment of a projection type liquid crystal display device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a rotary two-color filter shown in FIG.

FIG. 3 is a luminance characteristic diagram obtained by the projection type liquid crystal display device of FIG.

FIG. 4 is a schematic configuration diagram showing an optical system of a modified example of the projection type liquid crystal display device of FIG.

FIG. 5 is a schematic configuration diagram showing an optical system of a projection type liquid crystal display device according to a second example of the present invention.

FIG. 6 is a configuration diagram showing a configuration of a general single-panel type projection type liquid crystal display device using a conventional color filter.

FIG. 7 is a schematic diagram showing an arrangement example of the color filters of FIG.

FIG. 8 is a configuration diagram showing a configuration of a single plate type projection type liquid crystal display device using a reflection type liquid crystal display panel.

9 is a schematic diagram showing an arrangement of color filters used in the projection type liquid crystal display device of FIG.

10 is a luminance characteristic diagram obtained by the projection type liquid crystal display device of FIG.

FIG. 11 is a configuration diagram showing a configuration of a conventional general three-plate type projection type liquid crystal display device.

[Explanation of symbols]

A, B, C projection type liquid crystal display device 1 Focusing mirror 2 White light source 3, 11, 14 condenser lens 4 cold mirror 5 UVIR cut filter 6 drive motor 7 Rotating 2-color filter 8,17 Reflective mirror 9 Polarizing beam splitter 10 π / 2 retardation plate 12, 15 Liquid crystal light valve 13 Dichroic prism 16 color filters 18 Projection lens 21 Linearly polarized light generation unit 22 Color filter 23 Dichroic mirror 24 First reflective liquid crystal light valve 25 reflective mirror 26 Second reflective liquid crystal light valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 33/12 G03B 33/12 H04N 9/31 H04N 9/31 C F term (reference) 2H088 EA15 HA12 HA13 HA16 HA20 MA06 2H091 FA02Z FA05X FA10Z FA11Z FD26 LA11 LA15 LA17 5C060 BC03 HC16 HC17 HC22

Claims (3)

[Claims] 1. A projection type liquid crystal display device in which light from a light source is modulated by a liquid crystal light valve in accordance with image information and projected by a projection lens, wherein light from the light source has polarization directions orthogonal to each other. A polarized light splitting means for splitting the light into two linearly polarized light, and a rotary two-color color filter for temporally producing a light flux of two color components of the three primary colors of the light from one linearly polarized light split by this polarized light splitting means Of the three primary colors of light, a first liquid crystal light valve that transmits or reflects the light flux that has passed through the rotary two-color filter according to a luminance signal, and the other linearly polarized light that is separated by the polarization separating unit. , A monochromatic color filter that separates the remaining light flux of one color component, and the light separated by this monochromatic color filter is transmitted or reflected according to the luminance signal. A second liquid crystal light valve, an image synthesizing unit for synthesizing a two-color image and a single-color image respectively output from the first and second liquid crystal light valves to obtain a color image, and an image synthesized by the image synthesizing unit. A projection type liquid crystal display device, comprising: a projection means for enlarging and projecting. 2. The projection type liquid crystal display device according to claim 1, wherein a π / 2 retardation plate is arranged on an incident side of the first liquid crystal light valve or the second liquid crystal light valve. 3. A projection type liquid crystal display device in which light from a light source is modulated by a liquid crystal light valve in accordance with image information and projected by a projection lens, wherein the light from the light source has a uniform polarization direction. Linearly polarized light generating means for converting the linearly polarized light, and color separation means for separating the linearly polarized light generated by the linearly polarized light generating means into two color components of the three primary colors of light and the remaining one color component A rotary two-color color filter that produces a light flux of two color components of the three primary colors of light from the light flux of the two color components separated by the color separation means with time; A first liquid crystal light valve that reflects the generated light flux according to a luminance signal, and a second liquid crystal light valve that reflects the remaining light flux of one color component separated by the color separation means according to the luminance signal. An image synthesizing means for synthesizing a two-color image and a single-color image respectively output from the first and second liquid crystal light valves to obtain a color image, and a projection means for enlarging and projecting the image synthesized by the image synthesizing means. And a projection type liquid crystal display device.