JPH06113314A - Liquid crystal display projector - Google Patents

Abstract

PURPOSE:To prevent the lightness of a video image on a screen from being changed or the color reproducibility from being deteriorated due to a change in the lightness of a light source and a coloring characteristic. CONSTITUTION:When the lightness of a metallic halide lamp is decreased, a green light 17G detected by a green color photodetection element 30G is decreased and a comparison voltage V4 (G-GO) is decreased. A green color balance adjustment circuit 45G controls the light transmittivity of a green liquid crystal display panel 46G be increased. When the color reproducibility of the metallic halide lamp is changed, red and green balance adjustment circuits 45R, 45G control the light transmittivity of red and green liquid crystal display panels 46R, 46G to cancel the change in the color balance of the metallic halide lamp. According to the control in such a manner, the change in the lightness of a video image on the screen and the deterioration in the color reproducibility due to the change in the lightness and the coloring characteristic of the metallic halide lamp 12 are prevented.

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 projector for projecting image light on a screen, and more particularly to a liquid crystal display projector suitable for use with a light source whose secular change is large.

[0002]

2. Description of the Related Art Conventionally, in a liquid crystal display projector using a liquid crystal display panel, an illumination light is condensed and transmitted from a light source to an image light by a liquid crystal panel having polarizing plates arranged in front and rear,
An image is displayed on the screen by enlarging and projecting the image light on the screen through the projection lens. In such a liquid crystal display projector, a high brightness and high efficiency lamp (hereinafter referred to as an HID lamp) is used as a light source. A metal halide lamp is generally used as the HID lamp.

FIG. 11 is a block diagram showing a lamp lighting portion of a liquid crystal display projector using such a metal halide lamp.

Reference numeral 91 is a lamp lighting circuit for lighting the metal halide lamp 92, and the metal halide lamp 92 is lit by the power supply voltage from the lamp lighting circuit. Illumination light from the metal halide lamp 92 is reflected by the reflector 93, and is condensed and transmitted to a liquid crystal panel having polarizing plates arranged in front and rear.

A photo coupler 95 is provided in a path for applying a power supply voltage to the metal halide lamp 92 of the lamp lighting circuit 91.
Has been inserted. The photo coupler 95 supplies an output voltage corresponding to the power supply voltage applied to the metal halide lamp 92 to the lighting detection port 97 of the microcomputer 96. As a result, the microcomputer 96 detects the lighting of the metal halide lamp 92 corresponding to the output voltage from the photo coupler 95.

In such a liquid crystal display projector, even if a predetermined time has elapsed after the power source voltage was applied to the metal halide lamp 92 of the lamp lighting circuit 91, the detection result of the microcomputer 96 is the metal halide lamp 92.
When is not lit, it is determined that the metal halide lamp 92 has burned out, and the lamp is replaced.

Here, the metal halide lamp is superior to the halogen lamp in high brightness and color rendering,
There is a drawback in that the color development characteristic deteriorates greatly as compared with the halogen lamp with the total elapsed time of lighting the lamp. Therefore, the color reproducibility of the image on the screen deteriorates as the lamp lighting time elapses. Since the brightness of the metal halide lamp decreases with the elapsed lighting time of the lamp,
At the end of the lamp life, the image on the screen becomes dark.

In addition, since it takes some time for the metal halide lamp to reach the stable emission region after lighting, it is necessary to correct the color reproduction during that period, but there is some variation in the time until the stable emission region is reached. It is difficult to correct accurately.

[0009]

In the above-mentioned conventional liquid crystal display projector, since the brightness and the coloring characteristics of the light source change depending on the total lamp lighting elapsed time, the brightness of the image on the screen changes and the color reproduction is changed. The property had deteriorated. In addition, since it takes some time for the light source to reach the stable emission area after lighting, it is necessary to correct the color reproduction during that time, but there is some variation in the time until the stable emission area is reached, and there is some correction. Is difficult to do.

Therefore, the present invention eliminates the above problems,
An object of the present invention is to provide a liquid crystal display projector capable of preventing the brightness of an image on a screen from changing and the color reproducibility from deteriorating due to changes in the brightness of a light source and a color development characteristic.

[0011]

A liquid crystal display projector according to a first aspect of the present invention forms image light by transmitting illumination light from a light source to an incident side polarization plate, a liquid crystal panel and an emission side polarization plate. A liquid crystal display projector adapted to project the image light on a screen, and a red, blue and green light output detecting element for respectively detecting red, blue and green light outputs of illumination light from the light source, And a control circuit that adjusts the white balance of the liquid crystal panel based on the detection results from the red, blue, and green light output detection elements.

[0012]

According to this structure, the red, blue and green light output detecting elements detect the red, blue and green light outputs of the illumination light from the light source, respectively, and the control circuit detects the red, blue and green light outputs. Since the white balance of the liquid crystal panel is adjusted based on the detection result from the light output detection element, the brightness of the image on the screen may be changed or the color reproducibility may be deteriorated due to the change of the brightness of the light source or the coloring characteristics. Can be prevented.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of a liquid crystal display projector according to the present invention. FIG. 1 is a circuit diagram of an image projection unit, FIG. 2 is a sectional view of the image projection unit, and FIG. 3 is the liquid crystal of FIG. It is a top view of a module. First, it demonstrates using FIG.

In FIG. 2, the light source 11 of the image projection unit 10
Is composed of a metal halide lamp 12 and a reflector 13, and is attached to a housing 14. A reflector 12 is arranged behind the metal halide lamp 12. The reflector 13 reflects the illumination light emitted rearward from the metal halide lamp 12 toward the visible light reflecting mirror 15 inside the housing 14. The visible light reflecting mirror 15 absorbs and removes the infrared light and the ultraviolet light components to some extent and emits the light toward the filter 16 inside the housing 14.

The filter 16 removes infrared light from the illumination light to some extent and emits it. On the optical axis 17 of the light emitted from the filter 16, a green reflection spectroscopic dichroic mirror 18, which is inclined by 45 degrees with respect to the optical axis 17, is fixedly arranged inside the housing 14. The green reflection spectroscopic dichroic mirror 18 reflects only the green light 17G and transmits other color lights. The green light 17G reflected by the green reflection spectroscopic dichroic mirror 18 is reflected by the reflection mirror 19 arranged at an angle of 45 degrees with respect to the green light 17G, and enters the green liquid crystal module 20.

Red reflection spectral dichroic mirror 21
Is arranged at an angle of 45 degrees with respect to the color light transmitted through the green reflection spectral dichroic mirror 18, reflects only the red light 17R out of the transmitted color light, and reflects the other color light (blue light 17G).
Is transparent. Red reflection spectroscopic dichroic mirror 21
The red light 17R reflected from the liquid crystal is used for the green liquid crystal module 22.
Incident on.

The blue light 17B transmitted through the green reflection spectral dichroic mirror 21 enters the blue liquid crystal module 23.

The green light 24G emitted from the liquid crystal module 20 for green and the red light 24G emitted from the liquid crystal module 22 for red are arranged in a red reflection combination dichroic inclined at 45 degrees with respect to the optical axis of the green light 24G. The light is combined by the mirror 25 and emitted as combined light (24R + 24G).

The blue light 24B emitted from the blue liquid crystal module 23 is reflected by the reflection mirror 26 which is arranged at an angle of 45 degrees with respect to the optical axis of the blue light 24B.

The combined light (24R + 24G) combined by the red reflection combining dichroic mirror 25 and the blue light 24B reflected by the reflection mirror 26 are combined light (24R + 24).
G) is combined by a red-green reflective combining dichroic mirror 27 arranged at an angle of 45 degrees with respect to the optical axis, and emitted as image light 28. The projection lens 29 magnifies the image light 28 from the red-green reflection / synthesis dichroic mirror 27 and projects it on the screen.

Red, green and blue liquid crystal modules 22, 2
Red, green, and blue light 17R, 17G, and 17B for 0 and 23
Red, green and blue light detecting elements 30R,
30G and 30B are provided, respectively.

The structure of the red liquid crystal module 22 will be described below with reference to FIG.

In FIG. 3, the liquid crystal module 22 for red color is used.
A liquid crystal panel holding plate 32 holds a liquid crystal panel section 31 composed of an incident side polarization plate, a liquid crystal panel and an emission side polarization plate. Below the liquid crystal panel portion 31 of the liquid crystal panel holding plate 32, a red light detection element 30R is provided. The red light 17R from the green reflection spectral dichroic mirror 21 is applied to the circular area 33 including the liquid crystal panel section 31 and the red light detection element 30R.

The circuit section of the image projection section will be described below with reference to FIG.

In FIG. 1, the red, green, and blue light detection elements 30R, 30G, and 30B are supplied with the DC voltage V1 at one end, and the other ends are connected to the input terminals of the amplifiers 41R, 41G, and 41B, respectively. , Resistors R1, R2, R3
Is connected to the reference potential point via. As a result, the blue light detection elements 30R, 30G, and 30B are respectively red,
Detecting green and blue light 17R, 17G, 17B respectively,
Red, green, and blue detection voltages V2R, V2G, and
V2B is supplied to the input terminals of the amplifiers 41R, 41G, 41B. The amplifiers 41R, 41G and 41B amplify the red, green and blue detection voltages V2R, V2G and V2B to obtain red, green and
The blue detection voltages V3R, V3G and V3B are output.

The comparator 42 compares the green detection voltage V3G with the green reference voltage V0G, and supplies the comparison voltage V4 (G-GO) of the comparison result to the green balance adjusting circuit 45G of the control circuit 45.

The comparator 43 compares the red detection voltage V3R with the green detection voltage V3G, and supplies the comparison voltage V4 (RG) of the comparison result to the red balance adjustment circuit 45R of the control circuit 45.

The comparator 44 compares the blue detection voltage V3B with the green detection voltage V3G, and supplies the comparison voltage V4 (BG) of the comparison result to the blue balance adjustment circuit 45R of the control circuit 45.

The control circuit 45 is composed of red, blue and green balance adjusting circuits 45R, 45G and 45B,
The white balance and brightness of the red, blue and blue liquid crystal panels 46R, 46G and 46B are adjusted.

The green balance adjusting circuit 45G compares the comparison voltage V4 (G-GO) with the corresponding initial setting value, and sets the control voltage V5G corresponding to the comparison result to the green liquid crystal module 20 (see FIG. 2). LCD panel 46 for green
It is supplied to G to control the light transmittance of the green liquid crystal panel 46G.

The red balance adjusting circuit 45R compares the comparison voltage V4 (RG) with the corresponding initial setting value,
The control voltage V5R corresponding to this comparison result is supplied to the red liquid crystal panel 46R of the red liquid crystal module 22 (see FIG. 2) to control the light transmittance of the red liquid crystal panel 46R.

The blue balance adjusting circuit 45B compares the comparison voltage V4 (BG) with the corresponding initial setting value,
A control voltage V5B corresponding to this comparison result is supplied to the blue liquid crystal module 23 (see FIG. 2) to control the light transmittance of the blue liquid crystal panel 46B.

Green detection voltage V3G from amplifier 41R
Is supplied to the integration timer 48 of the microcomputer 47. The integration timer 48 is a key input or a halide lamp 12
The total lighting time of the metal halide lamp 12 (see FIG. 2) is calculated by counting the time when the green detection voltage V3G is at a high level after being reset by the removal of Display in a way that is visible to the user.

The operation of such an embodiment will be described below.

When the brightness of the metal halide lamp 12 is lowered, the green light 17R detected by the green light detecting element 30G is lowered and the comparison voltage V4 (G-GO) is lowered. Then green balance adjustment circuit 45G
Controls to increase the light transmittance of the green liquid crystal panel 46G. When the brightness of the green component of the metal halide lamp 12 increases, the green light 17R detected by the green light detecting element 30G rises, and the comparison voltage V4 (G-G) increases.
O) will rise. Then, the green balance adjusting circuit 45G controls so that the light transmittance of the green liquid crystal panel 46G decreases.

When the color reproducibility of the metal halide lamp 12 changes, the comparison voltages V4 (B-G) and V4 (R-
G) will change. Then, the red and blue balance adjusting circuits 45R and 45G control the light transmittances of the red and blue green liquid crystal panels 46R and 46G, respectively, so as to cancel the change in the color balance of the metal halide lamp 12. By such control, it is possible to prevent the brightness of the image on the screen from being changed and the color reproducibility from being deteriorated due to the change in the brightness of the metal halide lamp 12 and the change in the coloring characteristic.

Further, according to such an embodiment, it is possible to prevent the brightness of the image on the screen from being changed or the color reproducibility from being deteriorated due to the change of the brightness or the coloring characteristic of the metal halide lamp 12. Because it is possible, once the brightness and white balance are adjusted, the brightness and color development characteristics of the metal halide lamp 12 do not need to be adjusted to adjust the brightness and white balance, which is very convenient for the user. Become.

Further, since the total lighting time of the metal halide lamp 12 can be displayed on the life indicator 49, it is convenient to replace the metal halide lamp 12.

FIG. 4 is a block diagram showing a modification of the circuit system of the microcomputer 47 and the life indicator 49 of the embodiment of FIG. 1, and the same components as those of the embodiment of FIG. Omitted.

The green light detecting element 30G detects the green light 17G from the metal halide lamp 12 and causes the green detection voltage V2G of this detection result to be integrated timer 58 of the microcomputer 57. The timer reset circuit 51 of the microcomputer 57 is supplied with the detection signal a1 that detects the removal of the halide lamp 12. The timer reset circuit 51 resets the integration timer 58 when the detection signal a1 detects removal of the metal halide lamp 12. Accordingly, the integration timer 48 calculates the total lighting time of the metal halide lamp 12 (see FIG. 2) by counting the time when the green detection voltage V2G is at the high level, and the calculation result is the life of the metal halide lamp 12. When the time corresponding to is reached, the light emitting diode 59, which is a life indicator, is caused to emit light.

On the other hand, the lamp replacement frequency memory of the microcomputer 55 counts and stores the number of lamp replacements based on the detection signal a1 which detects the removal of the halide lamp 12, and stores the calculation result of the lighting time from the integrating timer 48. Then, the stored calculation results of the number of times of lamp replacement and the lighting time are displayed on the display device.

The lamp lighting circuit 50 turns on the metal halide lamp 12 and confirms that the lamp is turned on by the green detection voltage V2G.

According to this modification, the light emitting diode 59 can indicate that the metal halide lamp 12 has come.

FIG. 5 is a plan view of a red liquid crystal module showing another modification of the embodiment shown in FIG.

In the liquid crystal module 60 for red color, the liquid crystal panel portion 61 is held by the liquid crystal panel holding plate 62. Below the liquid crystal panel portion 61 of the liquid crystal panel holding plate 62, a red light detection element 64 is provided. A red filter 65 is provided on the front surface of the red light detection element 64. The red light R from the green reflection spectral dichroic mirror is applied to the circular area 63 including the liquid crystal panel section 61 and the red filter 65. Other than this, the liquid crystal module is also provided with a filter corresponding to the color.

According to such a modification, the filter 65
As a result, it is possible to prevent unnecessary light from being input to the red light detection element 64. Therefore, the brightness of the image on the screen may be changed or the color reproducibility may be deteriorated due to the change in the brightness of the metal halide lamp or the coloring characteristics. Can be corrected more accurately.

FIG. 6 is a plan view of a red liquid crystal module showing still another modification of the embodiment shown in FIG.

The red light detecting elements 74 are provided above, below, and to the left and right of the liquid crystal panel portion 71 of the liquid crystal panel holding plate 72 of the red liquid crystal module 70. The red light from the green reflection spectral dichroic mirror is applied to the circular area 73 including the liquid crystal panel section 71 and the red light detection element 74. Other than this, the liquid crystal module has the same configuration.

According to such an embodiment, the same effect as that of the embodiment of FIG. 1 can be obtained, and the detection results of the red light detecting elements 74 are averaged vertically and horizontally to obtain a more accurate metal halide. By detecting the brightness and color development characteristics of the lamp, it is possible to more accurately correct changes in the brightness of the image on the screen and deterioration of color reproducibility due to changes in the brightness and color development characteristics of the metal halide lamp. .

7 and 8 show another embodiment of the liquid crystal display projector according to the present invention, FIG. 7 is a sectional view of the image projection portion, and FIG. 8 shows the red, green, and blue light detection elements of FIG. It is an enlarged view which shows and its peripheral part. The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof is omitted.

As shown in FIG. 7, the difference between the embodiment of FIG. 1 is that a portion of the housing 104 between the visible light reflecting mirror 15 and the filter 16 is extended, and the light detecting portion 105 is provided in this portion.
Is provided.

The photodetecting section 100 is provided with an attenuation filter 101 and bandpass filters 103 corresponding to red, green and blue in front of the red, green and blue photodetecting elements 103R, 103G and 103B, respectively. The light from is directly detected.

Red, green, and blue photodetectors 103R, 10
As shown in FIG. 8, 3G and 103B are arranged between the visible light reflecting mirror 15 and the filter 16 in three directions. The band pass filter 103 shown in FIG. 7 is classified according to the positions of the red, green, and blue light detection elements 103R, 103G, and 103B.

Even in such an embodiment, since the red, blue and green light outputs of the illumination light from the metal halide lamp 12 similar to those of the embodiment of FIG. 1 can be detected respectively, the same effect as in FIG. 1 can be obtained. To be

9 and 10 show another embodiment of the liquid crystal display projector according to the present invention. FIG. 9 is a configuration diagram of an image projection unit, and FIG. 10 is a plan view of the liquid crystal module of FIG. .

In FIG. 9, the liquid crystal display projector 201 of this embodiment uses a three-color integrated liquid crystal module 202. Illumination light a2 from the light source 203 passes through the liquid crystal module 203 and enters the lens 205 as image light b2. The lens 205 refracts the image light b2 and projects it on the screen 206 as image light c2.

In the red liquid crystal module 203, as shown in FIG. 10, the color liquid crystal panel section 204 is held by the liquid crystal panel holding plate 211. Below the liquid crystal panel portion 61 of the liquid crystal panel holding plate 211, red, blue, and green light detection elements 212R, 212G, and 212B are provided. Red, blue, green light detection elements 212R, 212
G, 212B has red, blue and green filters 213 on the front.
R, 213G, 213B (see FIG. 9) are provided. Illumination light a2 from the light source 203 is emitted from the color liquid crystal panel section 204 and the red, blue and green filters 213R and 213.
The region 214 including G and 213B is irradiated.

The color liquid crystal panel section 204 adjusts the white balance and brightness of the color liquid crystal panel section 204 based on the detection results of the red, blue, and green light detection elements 212R, 212G, and 212B. .

According to such an embodiment, the same effect as in FIG. 1 can be obtained.

[0061]

As described above, according to the present invention, it is possible to prevent the brightness of the image on the screen from being changed or the color reproducibility to be deteriorated due to the change of the brightness of the light source or the color development characteristic. Therefore, once the brightness and the white balance are adjusted, the brightness and the white balance of the light source are not changed to adjust the brightness and the white balance, which is very convenient for the user.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a liquid crystal display projector according to the present invention.

FIG. 2 is a sectional view of an image projection unit.

FIG. 3 is a plan view of the liquid crystal module of FIG.

FIG. 4 is a block diagram showing a modification of the circuit system of the microcomputer and the life indicator of the embodiment of FIG.

5 is a plan view of a liquid crystal module showing another modification of the embodiment of FIG.

6 is a plan view of a liquid crystal module showing still another modification of the embodiment of FIG.

FIG. 7 is a cross-sectional view of a video projection unit showing another embodiment of the liquid crystal display projector according to the present invention.

FIG. 8 is an enlarged view showing the red, green, and blue light detection elements of FIG. 7 and a peripheral portion thereof.

FIG. 9 is a configuration diagram of a video projection unit showing another embodiment of the liquid crystal display projector according to the present invention.

10 is a plan view of the liquid crystal module of FIG.

FIG. 11 is a block diagram showing a lamp lighting unit of a conventional liquid crystal display projector.

[Explanation of symbols]

 30R, 30G, 30B Red, green, blue light detection element 45 Control circuit 46R, 46G, 46B Red, blue, blue liquid crystal panel

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[Procedure amendment]

[Submission date] October 14, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 6]

[Figure 8]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 5]

[Figure 4]

[Figure 7]

[Figure 9]

[Figure 10]

FIG. 11

Claims (2)

[Claims] 1. A liquid crystal display projector in which image light is formed by transmitting illumination light from a light source through an incident side polarization plate, a liquid crystal panel and an emission side polarization plate, and the image light is projected on a screen. , Red, blue and green light output detecting elements for respectively detecting the red, blue and green light outputs of the illumination light from the light source, and based on the detection results from the red, blue and green light output detecting elements A liquid crystal display projector comprising: a control circuit for adjusting white balance of the liquid crystal panel. 2. A liquid crystal display projector, wherein image light is formed by transmitting illumination light from a light source through an incident side polarization plate, a liquid crystal panel and an emission side polarization plate, and the image light is projected on a screen. A light output detection element for detecting the light output of the illumination light from the light source, and a light source lighting detection circuit for counting the lighting time of the light source based on the detection result from the light output detection element and determining the life of the light source. A liquid crystal display projector, comprising: a light source life display means for displaying a result of the life judgment of the light source from the light source lighting detection circuit.