JPH02281249A - Liquid crystal projection - Google Patents

Abstract

PURPOSE:To automatically correct color temperature by comparing a value detected by a color temperature detecting element provided on a position where light transmit ting an area with maximum light transmissivity on each liquid crystal panel and each light quantity control part condenses with a reference color temperature and controlling the quantity of the light transmitting the light quantity control part. CONSTITUTION:After split red, blue and green light beams transmit the area of maxi mum light transmissivity on the liquid crystal panels 13 to 15 and the light quantity control parts 10 to 12 provided before or after the liquid crystal panels, they are condensed in the position on which the color temperature detecting element 16 is provided. The color temperature detecting element 16 detects the color temperature of the condensed light, and it is compared with a previously set reference color tempera ture by the color temperature comparing means 17. Then, a light quantity control part driving means 18 decides whose light quantity is to be controlled among red, blue and green lights, and outputs a control signal to the light quantity control parts 10 to 12 which the light of color that is to be quantity-controlled transmits, thereby controlling the quantity of the light transmitting the light quantity control part. Thus, the light of color that is to be quantity-controlled is automatically controlled to correct the color temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a liquid crystal projection that can automatically correct color temperature.

<Prior Art> Conventionally, liquid crystal projection has no means for correcting color temperature. Therefore, the color temperature in liquid crystal projection depends on the color temperature of the lamp serving as the light source and the accuracy of the liquid crystal panel transmission characteristics.

<Problems to be Solved by the Invention> As described above, the color temperature in liquid crystal projection depends on the color temperature of the light source lamp and the accuracy of the liquid crystal panel transmission characteristics. Therefore, the color temperature of the light source lamp,
The transmission characteristics of the liquid crystal panel and the mounting of the dichroic mirror that separates and focuses the light from the light source lamp must be created with extremely high accuracy and transmission characteristics, which raises the problem of high manufacturing costs. be.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a liquid crystal projection device that can automatically correct color temperature.

Means for Solving the Problems> In order to achieve the above object, the present invention separates light from a light source into three colors of red, blue, and green, and divides the separated red, blue, and green lights into each color. The three colors of red, blue, and green light that have passed through each of the above liquid crystal panels are focused,
In liquid crystal projection that is enlarged and projected using a lens, a region of maximum transmittance is provided in the light transmitting part of each of the liquid crystal panels, and a light amount control part whose transmittance is controlled by a control signal is provided before or after each of the liquid crystal panels. A region of maximum transmittance of each liquid crystal panel and each light emitted are provided.

Then, the color temperature detected by the color temperature detection element and the preset reference color temperature are compared by the color temperature comparison means. Then, based on the comparison result from the color temperature comparison means, the light quantity control unit driving means,
It is determined which of the three colors of red, blue, and green light that needs to be controlled in light intensity, and a control signal is sent to the light intensity control unit through which the light of the color whose light intensity should be controlled is transmitted. is output, and the amount of light transmitted through this light amount control section is controlled. Therefore, the amount of light of the color whose amount should be controlled is automatically controlled, and the color temperature is corrected.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a sectional view of a liquid crystal projection according to the invention. l is a light source lamp, 2 is a condenser lens, 3.4.5 is a total reflection mirror, 6, 7, 8.9 are dichroic mirrors,
10, 11.12 are light control panels, 13, 14.15
16 is a liquid crystal panel, and 16 is a color temperature detection element for detecting the color temperature of the focused light at a position where the light transmitted through the color temperature amount control section is focused, and the color detected by the color temperature detection element is provided. A color temperature comparison means is provided to compare the temperature with a preset reference color temperature, and based on the comparison result from the color temperature comparison means, which of the three colors of red, blue, and green light is divided is provided. It determines whether it is necessary to control the amount of light of the color, outputs a control signal to the light amount control section through which the light of the color whose light amount is to be controlled passes through, and controls the amount of light that passes through this light amount control section. The present invention is characterized in that it is provided with a light amount control unit driving means for controlling the amount of light.

<Operation> The light from the light source is split into three colors, red, blue, and green, and each of the split red, blue, and green lights is transmitted through a liquid crystal panel that has a region of maximum transmittance in its light-transmitting area. The area of maximum transmittance above,
After passing through a light amount control section that is provided before or after the liquid crystal panel and whose transmittance is controlled by a control signal,
The light is focused at the position where the color temperature detection element is provided. The color temperature detection element detects the color temperature of the condensed light, 17 is a color temperature comparison control circuit;
8 is a light amount control panel drive circuit, and 19 is a lens for enlarging the image. The light amount control panel 1011.12 is a panel that can control the transmittance of the destination through alternating current voltage. Further, at the position of the light transmitting portion of each liquid crystal panel 13, 14, 15, a region of maximum transmittance (hereinafter referred to as maximum transmittance region) that transmits all incident light is provided.

The liquid crystal projection having the above configuration operates as follows. The light emitted from the light source lamp 1 is collected by a condensing lens 2, becomes a parallel beam of light, and is reflected by a total reflection mirror 3 into a beam 1.
Reach dichroic mirror 6. It is assumed that this dichroic mirror 6 is, for example, a dichroic mirror having spectral characteristics of red reflection. Then, the red single-wavelength light reflected by the dichroic mirror 6 is reflected by the total reflection mirror 5 toward the light amount control panel 10, and reaches the light amount control panel IO.

On the other hand, the light that does not contain the red wavelength and has passed through the dichroic mirror 6 reaches the dichroic mirror 7. It is assumed that this dichroic mirror 7 is, for example, a dichroic mirror having spectral characteristics of blue reflection. Then,
The single-wavelength blue light beam reflected by the dichroic mirror 7 reaches the light amount control panel 11 . On the other hand, the light that does not include the red wavelength and the blue wavelength (that is, the green single-wavelength light) that has passed through the dichroic mirror 7 reaches the light amount control panel 12 .

The red single-wavelength light that has reached the light amount control panel IO passes through the light amount control panel 10 and the red liquid crystal panel 13 and reaches the dichroic mirror 8. This dichroic mirror 8 is, for example, a dichroic mirror having a blue reflection spectral characteristic. Therefore, the red single-wavelength light incident on the dichroic mirror 8 is transmitted through the dichroic mirror 8. On the other hand, the blue single wavelength that has reached the light amount control panel 11 passes through the light amount control panel 11 and the blue liquid crystal panel 14 and reaches the dichroic mirror 8 . As described above, the dichroic mirror 8 reflects light having a spectral characteristic of blue reflection, for example.

The red single-wavelength light and the blue single-wavelength light transmitted through the dichroic mirror 9 are condensed together, and the green single-wavelength light reflected by the dichroic mirror 9 is condensed into one. be illuminated. This focused light then passes through the lens 19.
The liquid crystal panel 13 for red color is enlarged and projected by
A color image is projected on a screen or the like by combining the display contents of , the display contents of the blue liquid crystal panel 14, and the display contents of the green liquid crystal panel 15.

As described above, when the display contents of each liquid crystal panel 13, 14, 15 are combined and a color image is projected, the color temperature is detected as follows. That is, the red single-wavelength light beam reflected by the dichroic mirror 6, transmitted through the maximum transmittance region of the light amount control panel IO and the liquid crystal panel 13 for red color, and further transmitted through the dichroic mirror 8.9 is transmitted to the color temperature detection element 16. is input. In addition, since the dichroic mirror 7 reflects the maximum transmittance area of the light amount control panel 11 and the blue liquid crystal panel 14, the blue single-wavelength light incident on the dichroic mirror 8 is reflected by this dichroic mirror. It is reflected at 8. The single-wavelength red light transmitted through the dichroic mirror 8 and the single-wavelength blue light reflected by the dichroic mirror 8 are condensed into one and reach the dichroic mirror 9.

It is assumed that the dichroic mirror 9 is, for example, a dichroic mirror having spectral characteristics of green reflection. Then, the light, which is the single-wavelength red light and the single-wavelength blue light that have reached the dichroic mirror 9, is transmitted through the dichroic mirror 9 as it is because it does not include the green wavelength. On the other hand, the green single-wavelength light that has reached the light amount control panel 12 passes through the light amount control panel 12 and the line liquid crystal panel 15, is reflected by the total reflection mirror 4, and reaches the dichroic mirror 9. As described above, this dichroic mirror 9 is a dichroic mirror having a spectral characteristic of green reflection, for example, so it transmits a single wavelength of green that is incident on the dichroic mirror 9, and is further reflected by the dichroic mirror 8 and then reflected by the dichroic mirror 9. The blue single-wavelength light beam that has passed through is input to the color temperature detection element 16.

Further, the green light that is transmitted through the dichroic mirror 6.7, transmitted through the maximum transmittance area of the light amount control panel 12 and the liquid crystal panel 15 for green color, is reflected by the total reflection mirror 4, and further reflected by the dichroic mirror 9. A light flux of the wavelength is input to the color temperature detection element 16. In this way, the light incident on the color temperature detection element 16 is equal to +3.14 for each liquid crystal panel.
．． Since the single-wavelength red, blue, and green lights that have passed through the maximum transmittance regions of the LCD panels 15 are condensed into one light, the light that is incident on the color temperature detection element 16 is transmitted through each of the liquid crystal panels 13, 14, . This is white light that does not depend on the display contents of No. 15 (hereinafter referred to as reproduced white light).

In this way, the color temperature of the reproduced white light incident on the color temperature detection element 16 is detected by the color temperature detection element 16 and converted into an electric signal according to the color temperature. This converted electrical signal is then sent to the color temperature comparison control circuit 1.
7 is input. Then, the color temperature comparison control circuit 17 compares the color temperature based on the input electric signal and the color temperature of the standard white level, and outputs a control signal according to the difference in color temperature to the light amount control panel drive circuit 18. do.

When the light amount control panel driving circuit 18 determines that the amount of light of the red wavelength is large, for example, based on the control signal from the color temperature comparison control circuit 17, the amount of light transmitted through the liquid crystal panel 13 for red color is determined to be large. A light amount control signal for red is output to the light amount control panel 10 that controls the light amount. Then, the transmittance of the light amount control panel 10 is controlled in accordance with this light amount control signal for red, and the amount of light of the red wavelength is reduced. For example, if it is determined that the amount of blue wavelength light is large, the light amount control panel 1
1, a light amount control signal for blue color is output.

Then, the transmittance of the light amount control panel 11 is controlled in accordance with this light amount control signal for blue color, and the amount of light of the blue wavelength is reduced.

In addition, for example, since we have determined that the amount of light in the green wavelength is low, the color temperature of the light source lamp, the transmission characteristics of the liquid crystal panel, and the accuracy of the installation of the dichroic mirror are low, so the predetermined color Even if the temperature cannot be obtained, the color temperature can be automatically corrected to obtain a predetermined color temperature.

Therefore, the accuracy of the color temperature of the light source lamp, the transmission characteristics of the liquid crystal panel, the mounting accuracy and transmission characteristics of the dichroic mirror, etc., may be low to some extent as long as the color temperature can be corrected as described above. Manufacturing costs can be lowered. In addition, it becomes possible to use light sources and liquid crystal panels that were previously unusable due to low accuracy and were unable to obtain a predetermined color temperature.

In the above embodiment, the dichroic mirror 6 is a dichroic mirror having a red reflection spectral characteristic, the dichroic mirror 7 is a dichroic mirror having a blue reflection spectral characteristic, and the dichroic mirror 8 is a dichroic mirror having a blue reflection spectral characteristic. When the dichroic mirror 9 is a dichroic mirror having a green reflection spectral characteristic, a light amount control signal for green is output to the light amount control panel I2. Then, the transmittance of the light amount control panel 12 is controlled in accordance with this light amount control signal for green, and the amount of light of the green wavelength is increased.

In this way, after the light intensity of the single wavelength light is changed and color temperature correction is automatically performed, the color temperature detection element 16
The color temperature of the reproduced white light is detected, and if it is necessary to correct the color temperature again, the color temperature correction is performed.

As described above, in this embodiment, the color temperature comparison control circuit 17 compares the color temperature of the reproduced white light detected by the color temperature detection element 16 and the color temperature of the standard white level. Then, the light amount control panel drive circuit 1 determines which of the three colors of red, blue, and green light to control the amount of light, based on a control signal corresponding to the difference in color temperature.
8, the light amount control panel drive circuit 18 determines the transmittance of the light amount control panel through which the light of the color whose light amount is to be controlled is transmitted.
The mirror is controlled based on the light intensity control panel. However, the invention is not limited thereto. In short, dichroic mirror 6.7 separates the light into three colors, red, blue, and green, and dichroic mirror 8
．． Any combination may be used as long as white is reproduced by 9.

<Effects of the Invention> As is clear from the above, the liquid crystal projection of the present invention is provided with a light amount control section, a color temperature detection element, a color temperature comparison means, and a light amount control section driving means. A region of maximum transmittance is provided in the light transmitting portion of each liquid crystal panel through which light from a light source separated into light passes through, and a region of maximum transmittance is provided in the light transmittance portion of each liquid crystal panel, and The light that has passed through the transmittance area is focused on a position where the color temperature detection element is provided, the color temperature of the focused light is detected by the color temperature detection element, and the color temperature detection element detects the color temperature of the focused light. The color temperature detected by the color temperature and the reference color temperature set in advance are compared by the color temperature comparison means, and the light quantity control unit driving means compares the color temperature detected by the color temperature with a reference color temperature set in advance. Determines which of the three colors of blue and green light whose light intensity needs to be controlled, and outputs a control signal to the light intensity control unit through which the light of the color whose light intensity should be controlled passes through. Then, the amount of light transmitted through this light amount control section was controlled.
A color for which the amount of light should be automatically controlled is determined, and the amount of light of that color is automatically controlled to correct the color temperature.

Therefore, even if the accuracy of the color temperature of the light source lamp, the transmission characteristics of the liquid crystal panel, and the mounting accuracy of the glaucroic mirror are low to some extent, a predetermined color temperature can be obtained even if the precision of the transmission characteristics is low to some extent, and manufacturing costs can be reduced. I can do it. In addition, it becomes possible to use light sources and liquid crystal panels that were previously unusable due to their low precision.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the liquid crystal production according to the present invention. l...Light source lamp, 3,4.5...Total reflection mirror 6
．． 7,8.9... Guicroic mirror 0.11.12
... Light amount control panel, 3.14.15... Liquid crystal panel, 6... Color temperature detection element, 7... Color temperature comparison control circuit, 8... Light amount control panel drive circuit.

Claims (1)

[Claims] (1) The light from the light source is split into three colors: red, blue, and green, and the split red, blue, and green light is incident on a liquid crystal panel corresponding to each color, and after passing through each of the above liquid crystal panels. red, blue,
In liquid crystal projection, in which light of three colors of green is condensed, magnified by a lens, and projected, an area of maximum transmittance is provided in the light transmitting part of each of the liquid crystal panels, and a control signal is sent before or after each of the liquid crystal panels. A light amount control section whose transmittance is controlled by is provided, and the color temperature of the condensed light is adjusted in the area of the maximum transmittance of each of the liquid crystal panels and at the position where the light transmitted through each of the light amount control sections is condensed. A color temperature detection element is provided to detect the color temperature, and a color temperature comparison means is provided to compare the color temperature detected by the color temperature detection element with a reference color temperature set in advance, and a comparison result from the color temperature comparison means is provided. Based on this, it is determined which of the three colors of red, blue, and green light needs to be controlled in light quantity, and the light quantity control is performed so that the light of the color whose light quantity should be controlled is transmitted. 1. A liquid crystal projection device comprising a light amount control unit driving means for outputting a control signal to the light amount control unit and controlling the amount of light transmitted through the light amount control unit.