JPH05110970A - Projective liquid crystal projection - Google Patents

Abstract

PURPOSE:To keep the white balance of a display picture optimum. CONSTITUTION:Light of a light source 1 is separated into colors, and these separated color light R, G, and B are thrown to liquid crystal panels 8 to 10, and light of a picture consisting of liquid crystal panels 8 to 10 is synthesized and is projected on a screen by a projection lens 11. In this projective liquid crystal projection, intensities of incident light of liquid crystal panels 8 to 10 are detected by first to third optical sensors 13 to 15, and a microcomputer 19 calculates a light intensity ratio of R, G, and B of the light from the light source 1 based on these detected intensities of light and variably controls transmittances of liquid crystal panels 8 to 10 in accordance with this light intensity ratio to automatically adjust the white balance of the picture displayed on a screen. Thus, the white balance of the display picture is kept well even if the light intensity ratio of R, G, and B of light from the light source is broken.

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 projection capable of displaying an image on a large screen, and more specifically to a projection type liquid crystal projection which automatically adjusts the white balance of a display screen to maintain it optimally. It is about.

[0002]

2. Description of the Related Art Conventionally, this type of projection type liquid crystal projection has, for example, a structure shown in FIG. -G of incident light on the optical axes of the mirror 2 and the light source 1
A second dichroic mirror 3 that reflects (green) in the same direction as the R reflection direction, and a first dichroic mirror 3 that reflects incident light (B) in the same direction as the R reflection direction on the same optical axis. On the optical axis of the second mirror 5 and the second mirror 5 that reflects the reflected light of the mirror 4 and the first dichroic mirror 2 at a right angle and is parallel to the optical axis of the light source 1. On the optical axis of the third dichroic mirror 6 that reflects the reflected light of the second dichroic mirror 3 and makes it the same direction as the reflected light of the second mirror 5, and the optical axis of the second mirror 5, There is provided a fourth dichroic mirror 7 which reflects the reflected light of the first mirror 4 and makes it in the same direction as the reflected light of the second mirror 5.

Since the image projected on the screen is composed of the pixels of the R, G and B liquid crystal panels 8, 9 and 10, for example, the R liquid crystal panel 8 has a second mirror 5 and a third dichroic. The liquid crystal panel of G is arranged between the second dichroic mirror 3 and the third dichroic mirror 6, and the liquid crystal panel of B is arranged between the second dichroic mirror 3 and the first dichroic mirror 3. The mirror 4
It is placed between and.

The lights of the respective colors of the image formed by the liquid crystal panels 8, 9 and 10 are combined by the dichroic mirror and the mirror and projected on the screen by the projection lens 11.

Further, the projection type liquid crystal projection is provided with a video signal processing circuit 12 for driving and controlling each pixel of each of the liquid crystal panels 8, 9 and 10, and an input video signal (R, G, B) is provided. In order to obtain each color image by the video signal), the input video signal is subjected to predetermined signal processing, and the pixels of the liquid crystal panels 8, 9, 10 are driven according to the processed signal to form a display image. Is becoming

[0006]

In the projection type liquid crystal projection described above, a metal halide lamp is used as the light source 1 from the viewpoint of high brightness. However, during the life of the metal halide lamp, for example, the use time elapses. As a result, the light spectrum changes, the emission intensity ratio of R, G, and B collapses, and the white balance of the image obtained by combining the three primary colors of R, G, and B may deteriorate.

The present invention has been made in view of the above problems, and an object thereof is to obtain R, G, and R from a metal halide lamp.
The drive of each liquid crystal panel is controlled according to the emission intensity ratio of B,
An object of the present invention is to provide a projection-type liquid crystal projection capable of maintaining the white balance of a display image in an optimum state.

[0008]

In order to achieve the above object, the present invention separates the light of a light source to irradiate each liquid crystal panel and drives the pixels of each liquid crystal panel according to a predetermined image. In the projection type liquid crystal projection in which the R, G, B lights that have passed through the respective liquid crystal panels are combined and projected on a screen, a plurality of optical sensors for detecting the respective incident lights of the respective liquid crystal panels, and these optical sensors are used. Control means (A / D conversion section, microcomputer and D / A conversion section) for calculating the intensity of the incident light from the detection signal and outputting a control signal according to the calculated light intensity ratio, and each of the liquid crystal panels. And a video signal processing circuit for driving and controlling the pixels according to an input video signal and controlling the transmittance of the liquid crystal panel by an output control signal of the control means.

[0009]

With the above structure, the detection signals from the respective photosensors are digitally converted by the D / A conversion section, and the intensity of the incident light of each liquid crystal panel is calculated by the microcomputer based on these digital conversion data. Moreover, the light intensity ratio of each color (R, G, B), that is, the light intensity ratio of the light from the light source is calculated from this calculated value.

When the calculated light intensity ratio deviates from the original light intensity ratio, for example, when the white balance of the projected image is lost, the data for changing the drive voltage of each liquid crystal panel according to the deviation is the above D. The analog conversion is performed by the / A converter.

These analog-converted signals are input to a video signal processing circuit, the pixels of each liquid crystal panel are driven by this video signal processing circuit in accordance with the input video signal, and the drive voltage of each liquid crystal panel is converted to those analog signals. It can be changed by the converted signal.

That is, the intensity ratio of each color of the light source is monitored by the intensity of the incident light of each liquid crystal panel, and the light intensity ratio of R, G, B of the light from the light source 1 is destroyed, and, for example, the incident light of the liquid crystal panel is broken. When the intensity of the liquid crystal is weak, the transmittance of the liquid crystal panel is increased.

As a result, even if the intensity ratio of the incident light of each liquid crystal panel is broken, the light intensity ratio of R, G, B of the predetermined image projected on the screen is kept in the optimum state.
The white balance of the predetermined image is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the figure, the same parts as those in FIG.

In FIG. 1, the projection type liquid crystal projection includes first to third photosensors (for example, photodiodes) 13, 14, 15 for detecting the intensity of incident light of each liquid crystal panel 8, 9, 10. , Each optical sensor 13, 1
First to digitally convert the detection signals of 4 and 15 respectively
Through the third A / D converters 16, 17, 18, and R of the light from the light source 1 based on these digitally converted light intensity data,
The light intensity ratios of G and B are calculated, and each of the above liquid crystals is adjusted so that the calculated light intensity ratio becomes a predetermined value (the light intensity ratio of the light (R, G, B) of the light source 1 at the beginning). A microcomputer 19 for outputting data for controlling the transmittance of the panels 8, 9, 10 and first to third D / A converters 20, 21, 22 for analog-converting the data from the microcomputer 19, respectively. And the video signal processing circuit 1 shown in FIG.
In addition to the function of 2, the function of changing the drive voltage of each pixel of the liquid crystal panels 8, 9 and 10 in accordance with the analog-converted control signal to change the transmittance of each of the liquid crystal panels 8, 9 and 10. And a video signal processing circuit 23 having

The first to third optical sensors 13,
Although the reference numerals 14 and 15 are arranged near the liquid crystal panels 8, 9 and 10, any locations may be used as long as they do not interfere with the image configuration of the liquid crystal panels.

If a color image based on the input video signal is projected on the screen by the display operation of the projection type liquid crystal projection having the above-mentioned configuration, the light of the light source 1 is color-separated, and the color-separated R, The G and B lights are incident on the liquid crystal panels 8, 9, and 10, respectively.

The input video signals (R, G, B video signals) are subjected to predetermined signal processing by the video signal processing circuit 23, and the liquid crystal panels 8, 9, 10 are processed according to the input video signals.
Each pixel of is driven. As a result, an image corresponding to the input video signal is formed on each of the liquid crystal panels 8, 9 and 10, and the image is projected in color on the screen.

At this time, the emission intensity of the metal halide lamp of the light source 1, that is, the emission intensity of each of R, G, B is the first.
Since it is detected by the third optical sensor, the light intensity ratio of R, G, B is calculated by the detected values by the microcomputer, and for example, this light intensity ratio is compared with a predetermined value, and the optimum value is obtained. Whether or not it is in a state, that is, whether or not the white balance of the image displayed on the screen is not broken is determined.

Here, when the metal halide lamp of the light source 1 is new, that is, when the emission intensity ratio of R, G and B is not broken for the projection type liquid crystal projection, the microcomputer 19 is in the optimum state. The judgment is made, and each liquid crystal panel 8, 9, 1
Data for varying the drive voltage for controlling each pixel of 0 is not output.

Therefore, as in the conventional case, the video signal processing circuit 23 responds to the input video signal by the respective liquid crystal panels 8, 9 ,.
Since 10 is driven and controlled, the white balance of the color image projected on the screen remains good.

However, due to the elapsed time of use of the metal halide lamp, R,
The emission intensity of G and B may change and this emission intensity ratio may collapse.

Then, the first to third optical sensors 1 described above
The microcomputer 19 calculates the R, G, and B light intensity ratios based on the detection signals of 3, 14, and 15, and compares the calculated light emission intensity ratio with a predetermined value. The collapse of is determined.

Further, in the microcomputer 19, when the light intensity of R is lowered due to the collapse of the detected emission intensity ratio, the transmittance of the R liquid crystal panel 8 is increased. The variable amount of the drive voltage of 8 is calculated, and the variable amount data is output.

The calculated data is analog-converted by the D / A converter 20 and input to the video signal processing circuit 23. Therefore, in the video signal processing circuit 23, when driving the pixels of each of the liquid crystal panels 8, 9 and 10 by the input video signal, control is performed so as to increase the drive voltage of the R liquid crystal panel 8.

This increases the transmittance of the R liquid crystal panel 8 and compensates for the decrease in the R light intensity.
The R light of the image projected on the screen becomes bright, and the white balance of the entire image is maintained well.

In this way, the light intensity of the incident light (R, G, B) of each liquid crystal panel 8, 9, 10 is detected, and the R, G, B light intensity ratio of the light of the light source 1 is detected by these light detections. Is monitored and the light transmittance is varied by controlling the driving voltage of each liquid crystal panel so that the light intensity ratio is optimized when the light intensity ratio is broken. Therefore, the metal halide lamp of the light source 1 is controlled. Even if the emission intensity ratio of the liquid crystal panels changes with the lapse of its use time, the liquid crystal panels 8, 9, 10 are changed according to the change.
Since the transmissivity of V is varied, the white balance of the display image on the screen is automatically adjusted to maintain the optimum state.

Further, in the above embodiment, for example, when the projection type liquid crystal projection is shipped, the R,
It can be used for measuring and adjusting the light intensity ratio of G and B, that is, white balance, and the adjustment is easy and easy.

[0029]

As described above, according to the present invention, the light of the light source is color-separated and the color-separated R, G, and B lights respectively form a display image. In the projection type liquid crystal projection that irradiates the panel, synthesizes the light passing through each of the liquid crystal panels and projects it on the screen, the intensity of the incident light of each of the liquid crystal panels is detected, and these detection signals detect the light from the light source. A control signal for calculating the light intensity ratio of R, G, B and varying the transmitted light of each liquid crystal panel according to the light intensity ratio is obtained, and each of the liquid crystals is obtained according to the input video signal. The panel is drive-controlled, and the drive voltage of each liquid crystal panel is variably controlled according to the control signal so that the white balance of the image displayed on the screen is automatically corrected. R from, G, even if the light intensity ratio of B is lost, it is possible to hold the white balance of a display image on the screen to an optimum state, it is possible to always display satisfactory images on a turn screen.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a projection type liquid crystal projection showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional projection type liquid crystal projection.

[Explanation of symbols]

 1 light source (metal halide lamp) 2 first dichroic mirror 3 second dichroic mirror 4 first mirror 5 second mirror 6 third dichroic mirror 7 fourth dichroic mirror 8 liquid crystal panel (for R) ) 9 liquid crystal panel (for G) 10 liquid crystal panel (for B) 11 projection lens 12, 23 video signal processing circuit 13 first optical sensor (for R) 14 second optical sensor (for G) 15 third light Sensor (for B) 16, 17, 18 A / D converter 19 Microcomputer 20, 21, 22 D / A converter

Claims (1)

[Claims] 1. Color separation of light from a light source is applied to each liquid crystal panel, and pixels of each liquid crystal panel are driven according to a predetermined image so that R, G, and B light passing through the respective liquid crystal panels is driven. In a projection type liquid crystal projection for synthesizing and projecting on a screen, a plurality of light detecting means for respectively detecting the incident light of each liquid crystal panel, and calculating the intensity of the incident light by a detection signal by the plurality of light detecting means, Control means for outputting a control signal according to the calculated light intensity ratio, drive control of pixels of each of the liquid crystal panels according to an input video signal, and transmittance of the liquid crystal panel by an output control signal of the control means. And a video processing unit for controlling the intensity ratio of each color of the light source by the intensity of the incident light of each liquid crystal panel, and the transmitted light of each liquid crystal panel can be transmitted according to the light intensity ratio. Possible and to a projection type liquid crystal projection, characterized in that to automatically adjust the white balance of a given image that is projected on the screen.