JPH10123477A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the liquid crystal projector in which the brightness of a reproduced picture is emphasized and the white color chromaticity does not vary with the opening of a panel and the kind of a lamp. SOLUTION: The projector is provided with a white color component signal computing circuit 10 which generates white color component signals W from three color chrominance signals R, G and B, subtracting circuits 11, 12 and 13 which respectively subtract the signals W from the signals R, G and B and output color driving signals RD, GD and BD and a multiplying circuit 14 which multiplies the value equivalent to (transmission light quantity of color liquid crystal panel)/(transmission light quantity of luminance liquid crystal panel) with the signals W and outputs luminance driving signals YD. Thus, the ratio between the white color components and the color components becomes the same as the color signals R, G and B and the faithfulness of a reproducing is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector having a luminance liquid crystal panel and a color liquid crystal panel, and combining and projecting light transmitted through both panels.

[0002]

2. Description of the Related Art FIGS.
FIG. 21 is a configuration diagram showing this type of conventional liquid crystal projector described in Japanese Patent Application Laid-Open No. 6030, in which FIG. 21 shows the entire configuration of an optical system, and FIG. 22 shows the configuration of both liquid crystal panels, particularly the distribution of pixels. In the figure, 1 is a lamp for a light source such as a metal halide lamp, 2 is a reflector, 3 is a polarizing beam splitter for separating light from the lamp 1 into a P wave and an S wave, 4 and 5 are reflection mirrors, 6 is The opening degree of the liquid crystal panel for luminance is controlled by the luminance signal Y.
Reference numeral 7 denotes a color liquid crystal panel, as shown in FIG. 22 (2), in which pixels of the R, G, and B primary colors are uniformly distributed, and the color liquid crystal panel RY / GY / BY The driving degree of the opening is controlled for each pixel of each color. Numeral 8 denotes a polarizing beam splitter for synthesizing the lights LY, LR, LG and LB transmitted through the panels 6 and 7, and 9 denotes a projection lens.

Next, the operation will be described. The light generated by the lamp 1 is reflected by the reflector 2, illuminates the front surface, and enters the separation polarizing beam splitter 3. The light incident on the separation polarizing beam splitter 3 is separated into a P-wave and an S-wave here, and the S-wave is reflected by the reflection mirror 4 and is incident on the luminance liquid crystal panel 6. The P wave is reflected by the reflection mirror 5 and enters the color liquid crystal panel 7. The light transmitted through both panels 6 and 7 is converted into a polarizing beam splitter 8 for synthesis.
And is projected onto a screen (not shown) via the projection lens 9.

On the other hand, in the signal processing system, a white component signal is created from three color signals of R, G and B, which are video signals to be reproduced, and the signal Y is used to drive and control the luminance liquid crystal panel 6. In the luminance liquid crystal panel 6, the opening degree of each pixel changes according to the magnitude of the signal Y, and the intensity of the transmitted light LY is controlled. In addition, the driving of the color liquid crystal panel 7 is controlled by a signal RY / GY / BY obtained by subtracting the signal Y from the original color signal. In the color liquid crystal panel 7, these three signals RY / GY / BY allow R, G, B
Of each pixel changes, and each transmitted light LR, L
The intensity of G and LB is controlled. As described above, the light LY and the light LR, the light LR, the light LG transmitted through the panels 6 and 7 that are driven and controlled,
By synthesizing the LB and irradiating the screen, an image corresponding to the original video signal can be reproduced on the screen.

[0005]

As described above, a conventional liquid crystal projector has a configuration in which a transmitted image of a luminance liquid crystal panel and a transmitted light of a color liquid crystal panel are combined to obtain a reproduced image. In this case, various problems occur due to differences in transmission chromaticity characteristics and transmission light amounts of the liquid crystal panel itself.

That is, since the liquid crystal panel for color has a color filter corresponding to each color in contrast to the liquid crystal panel for luminance, if the liquid crystal itself is made of the same material, the amount of transmitted light as the panel is inferior to the former. . As a result, the illuminance ratio between the white component and the color component irradiated on the screen is different from the ratio of both components in the original video signal, and the fidelity of reproduction is reduced.

Further, the low amount of transmitted light of the color liquid crystal panel directly leads to a reduction in the brightness of the reproduced image, which hinders the improvement of the function as a liquid crystal projector. Further, in connection with the chromaticity characteristics of the lamp light source, the transmission chromaticity characteristics of the liquid crystal panel are affected by the degree of opening of the panel, and the chromaticity of white changes according to the degree of opening of the panel, and thus the brightness. However, there is a disadvantage in that the reproduction image quality is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended that the white component and the color component in the original video signal be irrespective of the difference in the amount of transmitted light between the luminance and color panels. It is an object of the present invention to obtain a liquid crystal projector capable of obtaining a high-fidelity reproduced image maintaining the same ratio. Another object of the present invention is to provide a liquid crystal projector capable of enhancing the brightness of a reproduced image. Still another object of the present invention is to provide a liquid crystal projector in which the white chromaticity does not change depending on the opening degree of the panel and the type of lamp.

[0009]

According to a first aspect of the present invention, there is provided a liquid crystal projector for generating a white component signal from three color signals, and subtracting the white component signal from the three color signals. And a multiplying circuit for multiplying the white component signal by a predetermined constant smaller than 1 and outputting the multiplied signal as a luminance driving signal.

In the liquid crystal projector according to a second aspect of the present invention, the predetermined constant is set to (the transmitted light amount of the color liquid crystal panel) / (the luminance liquid crystal panel) when both panels are fully opened. (Amount of transmitted light).

According to a third aspect of the present invention, there is provided a liquid crystal projector for generating a white component signal from three color signals, and subtracting the white component signal from the three color signals to obtain three color signals. A subtraction circuit that outputs a drive signal,
A white detection circuit for detecting whether or not the composite color of the three color signals is white; and, when the white color is not detected, multiplying the white component signal by a predetermined first constant smaller than 1 to generate a luminance drive signal. And a switching multiplying circuit for multiplying the white component signal by a predetermined second constant larger than the first constant and outputting as the luminance drive signal when the white color is detected. .

According to a fourth aspect of the present invention, in the liquid crystal projector according to the third aspect, the first constant is set to ((the amount of transmitted light of the color liquid crystal panel) / (the liquid crystal for luminance) when both panels are fully opened. (The amount of light transmitted through the panel).

Further, a liquid crystal projector according to claim 5 is the liquid crystal projector according to claim 3 or 4, wherein the second constant is set to 1.

According to a sixth aspect of the present invention, in the liquid crystal projector according to the third or fourth aspect, the second constant has a value that increases as the white component signal increases.

According to a seventh aspect of the present invention, there is provided a liquid crystal projector, comprising: a white component signal operation circuit for generating a white component signal from three color signals; and a subtraction circuit for subtracting and outputting the white component signals from the three color signals. A first gain conversion circuit for converting and outputting the gain of the white component signal;
When the output signal of the gain conversion circuit is below the predetermined upper limit level, it is output as it is as a luminance drive signal, and when the output signal of the first gain conversion circuit exceeds the upper limit level, the signal of the upper limit level is converted to the above-mentioned signal. A clipping circuit that outputs a luminance drive signal and outputs an amount exceeding the upper limit level as an overflow signal, a second gain conversion circuit that converts and outputs a gain of the overflow signal, and an output of the three colors of the subtraction circuit An adder circuit is provided that adds the output signals of the second gain conversion circuit to the signals and outputs the signals as color drive signals of three colors.

In the liquid crystal projector according to the present invention, the first gain conversion circuit may be configured as follows.
The multiplication circuit includes a multiplication circuit that multiplies the white component signal by a predetermined third constant larger than 1 and outputs the multiplied signal, and a step-down circuit that reduces the output signal of the multiplication circuit to an arbitrary level and outputs the signal.

According to a ninth aspect of the present invention, in the liquid crystal projector according to the eighth aspect, the third constant is set to (((the amount of transmitted light of the color liquid crystal panel) / (the luminance This is a value corresponding to (the amount of light transmitted through the liquid crystal panel)) + 1.

According to a tenth aspect of the present invention, in the liquid crystal projector according to the eighth or ninth aspect, the second gain conversion circuit is configured by a multiplication circuit that multiplies an overflow signal by the following constant and outputs the result. The above constant is a value corresponding to (the amount of transmitted light of the liquid crystal panel for luminance) / (the amount of transmitted light of the liquid crystal panel for color) when both panels are driven fully open.

The liquid crystal projector according to claim 11 is the liquid crystal projector according to any one of claims 7 to 10, wherein a switching circuit is inserted between the white component signal operation circuit and the first gain conversion circuit, and a three-color signal processing circuit is provided. And a white detection circuit for detecting whether or not the composite color of the color signal is white. The white component signal is input to the first gain conversion circuit only when the white color is detected. A signal obtained by multiplying the component signal by a predetermined fourth constant smaller than 1 is directly output as a luminance drive signal.

According to a twelfth aspect of the present invention, in the liquid crystal projector according to the eleventh aspect, the fourth constant is set to ((the amount of transmitted light of the color liquid crystal panel) / (the liquid crystal for luminance) when both panels are fully opened. (The amount of light transmitted through the panel).

According to a thirteenth aspect of the invention, there is provided a liquid crystal projector comprising:
A white component signal operation circuit that creates a white component signal from a color signal and outputs the signal as a luminance drive signal; a subtraction circuit that subtracts and outputs the white component signal from the three color signals; and an output of the subtraction circuit It is provided with a gain conversion circuit that converts the gain of the signal and outputs it as three color drive signals.

According to a fourteenth aspect of the present invention, in the liquid crystal projector according to the thirteenth aspect, the gain conversion circuit includes a gain conversion unit having a conversion characteristic in which an output signal increases with the following gradient with respect to an increase in an input signal; The output signal from the gain conversion unit is configured by an upper limit unit that limits the output signal at a predetermined upper limit level. The above gradient is (the amount of transmitted light of the liquid crystal panel for luminance) when both panels are fully opened.
(The amount of light transmitted through the color liquid crystal panel).

According to a fifteenth aspect of the present invention, in the liquid crystal projector according to the fourteenth aspect, the (output / input) gradient at a relatively high level portion in the conversion characteristic region at or below the upper limit level of the gain conversion section. It is set lower than the value described in the item 14.

In a liquid crystal projector according to a sixteenth aspect of the present invention, in the thirteenth aspect, the gain conversion circuit outputs the input signal in a relatively low level portion from 0 to a predetermined value in response to the rise of the input signal. The signal has a conversion characteristic in which the signal rises at the following gradient, and in a relatively high level portion where the input signal is from the predetermined value to the input maximum value, the output signal is lower than the following gradient with respect to the rise of the input signal. It has a conversion characteristic that rises with a gradient and reaches a panel fully open level, and the gradient is (transmission light amount of the luminance liquid crystal panel) / (transmission of the color liquid crystal panel) when both panels are driven fully open. (Light amount).

[0025] The liquid crystal projector according to the seventeenth aspect is characterized in that:
A white component signal calculation circuit that generates a white component signal from a color signal of a color and outputs the white component signal as a luminance drive signal; a subtraction circuit that subtracts the white component signal from the three color signals and outputs the white component signal; A white chromaticity conversion circuit that performs gain conversion on the conversion characteristics of each of the three colors R, G, and B and outputs the result.
And an adder circuit for adding the output signal of the subtraction circuit and the output signal of the white chromaticity conversion circuit for each of R, G, and B colors and outputting three color drive signals.

In the liquid crystal projector according to the eighteenth aspect of the present invention, the white chromaticity conversion circuit according to the seventeenth aspect is configured to suppress a change in chromaticity of white transmitted light due to a change in intensity of a driving signal in the liquid crystal panel. The conversion characteristics are set.

Further, in the liquid crystal projector according to claim 19, the white chromaticity conversion circuit according to claim 18 includes:
For the R and G colors, the output signal is always zero, and for the B color, gain conversion is performed so that the output signal increases as the input signal increases.

In the liquid crystal projector according to a twentieth aspect, the white chromaticity conversion circuit according to the seventeenth aspect is configured such that the chromaticity of the white transmitted light that differs depending on the type of the light source or the liquid crystal panel matches the desired white chromaticity. That is, the conversion characteristics are set so as to perform the conversion.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a circuit diagram showing a configuration of a liquid crystal projector according to Embodiment 1 of the present invention, particularly, a signal processing system thereof. The configuration of the optical system is the same as that of the prior art shown in FIGS. In FIG. 1, reference numeral 10 denotes a white component signal calculation circuit that creates a white component signal W from the input three color signals R, G, and B. The white component signal calculation circuit 10 normally detects a signal of the minimum level from the input color signals R, G, and B, and outputs this as a white component signal W. 11, 12, 13
Is a subtraction circuit that subtracts the white component signal W from the color signals R, G, and B and outputs the three color drive signals RD, GD, and BD to be supplied to the liquid crystal panel 7 for color. The liquid crystal panel 6 for luminance is multiplied by a predetermined constant.
Is a multiplication circuit that outputs a luminance drive signal YD to be supplied to the multiplication circuit. The constants of the multiplication circuit 14 are as follows:
7 is fully opened, a value corresponding to (the amount of transmitted light of the color liquid crystal panel 7) / (the amount of transmitted light of the luminance liquid crystal panel 6). As an example, it is set to 0.5.

Note that the ratio of the amount of transmitted light in the above equation is not only due to the difference in transmittance between the panels 6 and 7 itself, but also
The value includes a value resulting from a difference in transmittance (reflection) of other optical components existing on the optical path of both panels. The signals R, G, B, YD, RD, GD, BD
Each of the values fluctuates with the value corresponding to the fully open (opening 100%) drive of the panels 6 and 7 as its maximum value.

Next, the operation will be described with reference to FIG. FIG.
Is a color signal R which is an input signal to the liquid crystal projector,
G, B and a white component signal W, a luminance drive signal YD, a color drive signal RD, GD, BD created by the respective arithmetic means constituting the liquid crystal projector, and a polarizing beam splitter 8 for transmission through both panels 6 and 7 for synthesis. FIG. 7 is a diagram showing levels of light combined by the above and panel transmitted combined light in comparison with a conventional case.

First, the conventional case shown in FIG. 1A will be described. When the color signals R, G, and B shown in the leftmost column of FIG. It outputs a level signal, here, a white component signal W at the level of the color signal B. Then, the white component signal W is output as it is as the luminance drive signal YD. Also, the subtraction circuits 11, 12, and 13 use the values obtained by subtracting the white component signals W from the respective color signals R, G, and B (the values indicated by the dotted lines at the top of the white component signal W column) as they are. Output as drive signals RD, GD, BD.

Next, as described above, there is a difference in the amount of transmitted light between the two liquid crystal panels 6 and 7. For example, the amount of transmitted light of the color liquid crystal panel 7 is one of that of the luminance liquid crystal panel 6.
/ 2. Accordingly, as shown in the rightmost column of FIG. 2, the transmitted light LY of the luminance liquid crystal panel 6 has a value corresponding to the level of the luminance drive signal YD (here, it is expressed by the same magnitude of 1: 1). On the other hand, the transmitted light LR, LG, LB of the color liquid crystal panel 7 becomes the color drive signal RD, GD, BD.
, And the white component (LY) and the color components (LR, LG, L) in the combined panel transmitted light obtained by adding both.
B) is different from the ratio of both components in the original color signals R, G, B. In other words, the reproduced image has low saturation with reduced color components.

On the other hand, in the case of the present invention (FIG. 1) shown in FIG. 2 (2), the multiplication circuit 14 is provided so that a value obtained by multiplying the white component signal W by 0.5 is used as the luminance drive signal YD. As shown in the rightmost column of FIG. 2B, the brightness is reduced as a whole, but the white component (LY) and the color components (LR, LG, LB) in the panel transmitted composite light are supplied to the luminance liquid crystal panel 6 as shown in the rightmost column of FIG. ) Is the same as the ratio of the two components in the original color signals R, G, and B, so that a reproduced image in which the chroma is faithfully reproduced is obtained.

In the multiplication circuit 14 of FIG. 1, the constant is equivalent to (the transmitted light amount of the color liquid crystal panel 7) / (the transmitted light amount of the luminance liquid crystal panel 6) when both panels are driven fully open. Value was set to 0.5 as an example, but 1
A value larger than the above value in a smaller range, for example, 0.6 to
It may be set to about 0.7. In this case, it is possible to balance the two requirements of ensuring the brightness of the reproduced image and faithfully reproducing the saturation at an appropriate ratio.

Embodiment 2 FIG. 3 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 2 of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated. In the first embodiment, there is a disadvantage that the brightness of the reproduced image is reduced in order to achieve the fidelity reproduction of the saturation. However, in the second embodiment, achromatic colors (white, gray, black, etc.) are used. Only when a color signal (having no color) is input, the brightness of the reproduced image is increased, the contrast with respect to white is increased, and the resolution of white characters and the like is improved.

In FIG. 3, reference numeral 15 denotes a white detection circuit for detecting whether or not the composite color of the color signals R, G, and B is white (achromatic). In this case, each output signal R of the subtraction circuits 11, 12, and 13 is used.
Determine whether D, GD, and BD are all zero (actually, set an extremely low threshold value and determine whether it is less than the threshold value)
Then, when both are zero, the signal SW is output. 16 and 1
Reference numeral 7 denotes first and second multipliers, and reference numeral 18 switches which of the first and second multipliers 16 and 17 is inserted between the white component signal operation circuit 10 and the liquid crystal panel 6 for luminance. The switching operation is performed by a switch in accordance with an output signal from the white color detection circuit 15. Then, a switching multiplication circuit 19 is constituted by the multipliers 16 and 17 and the switching unit 18.

The constant (first constant) of the first multiplier 16 is (the transmitted light amount of the color liquid crystal panel 7) / (the liquid crystal for luminance) when both panels 6 and 7 are driven fully open. (Corresponding to the amount of light transmitted through panel 6), here 0.5
Is set to Further, the constant of the second multiplier 17 (second
Is set to 1.0.

Next, the operation will be described with reference to FIG. FIG.
FIG. 3 is a diagram showing each signal and each level of panel transmitted / combined light in the same manner as in FIG. 2 in comparison with the conventional case. First, FIG. 4A illustrates a case where a conventionally input color signal forms chromatic light, that is, a case where there is a difference between the levels of the color signals R, G, and B. In this case, the ratio between the white component (LY) and the color components (LR, LG, LB) in the combined panel transmitted light is the same as that described with reference to FIG. B is different from the ratio of both components, and there is a problem that the saturation of the reproduced image is reduced. FIG. 4 (1-2) shows a conventional case where the input color signals form achromatic light, that is, the color signals R,
This is the case where there is no difference between the levels G and B. in this case,
Since all of the color drive signals RD, GD, and BD become zero,
The above-described change in the ratio of the white component / color component does not matter, and the transmitted light LY corresponding to the white component signal W of the color signals R, G, and B is obtained.

Next, FIG. 4 (2-1) shows the present invention (FIG. 3).
Is a case where color signals R, G, and B, which become chromatic light, are input. In this case, among the output signals of the subtraction circuits 11, 12, and 13, the signals RD and GD are not zero.
5 does not output the white detection signal SW.
Is operated to the position where the first multiplier 16 is selected.
As a result, the white component signal W from the white component signal calculation circuit 10 is halved by the first multiplier 16 in the same manner as described with reference to FIG. Since the light is supplied to the panel 6, the influence of the difference in the amount of transmitted light between the panels 6 and 7 is corrected, and the white component (LY) and the color components (LR, LG,
LB) is the same as the ratio of both components in the color signals R, G, and B, so that faithful reproduction of saturation can be achieved.

FIG. 4 (2-2) shows a case where the color signals R, G, and B which become achromatic light in the present invention are input. In this case, the output signals RD, GD of the subtraction circuits 11, 12, 13
Since any one of BD becomes zero, the white detection circuit 15 detects this and outputs a signal SW. Accordingly, the switch 1
8 operates to select the second multiplier 17 instead of the first multiplier 16. As a result, transmitted light LY corresponding to the white component signal W of the color signals R, G, and B is obtained in the same manner as described with reference to FIG.

As described above, in the liquid crystal projector according to the second embodiment, when the input color signals R, G, and B are chromatic light, the saturation is maintained without changing the ratio of the white component / color component. It is possible to obtain a reproduced image that faithfully reproduces, and, when the input signal is achromatic light, it is possible to obtain a bright reproduced image with increased contrast by making full use of the transmitted light capability of the liquid crystal panel 6 for luminance. That is.

The white detection circuit 15 in FIG. 3 receives the output signals of the subtraction circuits 11, 12, and 13 and performs white detection by determining whether or not these signals are both zero. On the other hand, a method may be employed in which white signals are detected by directly inputting the color signals R, G, and B and determining whether or not the levels of these signals are the same.

In the first multiplier 16 of FIG. 3, the constant (first constant) is calculated by dividing (the transmitted light amount of the color liquid crystal panel 7) / (luminance for luminance) when both panels are driven fully open. (Amount of light transmitted through the liquid crystal panel 6).
5, but a value larger than the above value within a range smaller than the constant (second constant) of the second multiplier 17, for example,
It may be set to about 0.6 to 0.7, so that the two requirements of securing the brightness and faithfully reproducing the saturation of the chromatic reproduction image may be balanced at an appropriate ratio. Further, in the second multiplier 17 of FIG. 3, the constant (the second constant) is set to 1.0. However, in consideration of the balance with the signal processing amount of the chromatic reproduced image, the first multiplier 17 is used. May be set to a numerical value other than 1.0 in a range larger than the constant. Needless to say, the amount of transmitted light also differs depending on the type of liquid crystal panel. Therefore, the real number needs to be set in consideration of the type of liquid crystal panel.

FIG. 5A shows a modification of the circuit shown in FIG.
The difference from FIG. 3 is the second multiplier 17a. That is, in FIG. 3, the second constant of the second multiplier 17 is always constant at 1.0 regardless of the magnitude of the white component signal W which is the input signal. But,
The value increases as the white component signal W increases. This will be described in more detail with reference to FIG.
A constant line 0 of a fixed dotted line 17 corresponds to the conversion characteristic of the second multiplier 17 of FIG. 3, while the second multiplier 17a of FIG.
The conversion characteristic 17a is a characteristic indicated by a solid line in the figure, which starts from 0.5, which is the gradient (first constant) of the first multiplier 16, and gradually increases the gradient.

By employing the configuration shown in FIG. 5,
Visual unnaturalness based on the above-described constant switching is reduced. That is, when the switching and multiplying circuit 19 is switched in a range where the brightness is relatively low as a human visual characteristic, a portion having chroma (without white detection) becomes a surrounding portion having no chroma (with white detection). It looks unnaturally dark in comparison. Therefore, the circuit of FIG. 5 reduces the difference in the constants due to the switching in the region where the brightness is low (the white component signal W is low), and increases the difference as the brightness increases. It is alleviating the naturalness.

Embodiment 3 By the way, in a liquid crystal projector, there is a demand for arbitrarily adjusting the white brightness of a reproduced image in order to adapt to the usage environment, for example, the brightness of the image reproduction site or the user's preference.
In this case, the level of the luminance drive signal YD may be adjusted. However, since the luminance liquid crystal panel 6 performs opening control with 50% of the amount of light from the lamp 1 as incident light in the first place, the brightness is further increased. We cannot meet the demand for growth.
The liquid crystal projector according to the third embodiment of the present invention satisfies the above-mentioned requirement by effectively using the transmitted light of the color liquid crystal panel 7. FIG. 6 is a circuit diagram showing the configuration of the signal processing system. It is. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

In the figure, reference numeral 20 denotes a multiplication circuit for multiplying the white component signal W by a predetermined constant and outputting the multiplied signal, and 21 denotes a multiplication circuit 2
This is a step-down circuit that steps down an output signal of 0 to an arbitrary level and outputs the same. Here, a volume (variable resistor) is used. Then, a first gain conversion circuit 22 is constituted by the multiplication circuit 20 and the step-down circuit 21. The constant (third constant) of the multiplying circuit 20 is ((the amount of transmitted light of the color liquid crystal panel 7) when both panels 6 and 7 are driven fully open /
(The amount of transmitted light of the liquid crystal panel 6 for brightness)) A value corresponding to +1 (here, 1.5) is set. Also, the step-down circuit 2
Although 1 can be stepped down to an arbitrary level, for the sake of convenience of the description of the operation to be described later, when the input is stepped down to 1/3, the gain is adjusted. When the pressure drops to 3/3), it is the same position.

Reference numeral 23 denotes a limiter which outputs an output W1 = K · W (K is a constant determined by a third constant of the multiplication circuit 20 and a gain adjustment position of the step-down circuit 21) of the first gain conversion circuit 22 to a luminance driving signal. and it outputs the maximum value YD _max (corresponding to 100% opening) the range of the luminance drive signal YD. 2
Reference numeral 4 denotes a subtraction circuit for calculating the difference between the input and output of the limiter 23 and outputting the result as an overflow signal Y1.
And a subtraction circuit 24 constitute a clip circuit 25. 26
Is a second gain conversion circuit that multiplies the output of the subtraction circuit 24 by the following constant and outputs the result as a boost signal C1. Here, the constant of the second gain conversion circuit 26 is (transmitted light amount of liquid crystal panel 6 for luminance) / (transmitted light amount of liquid crystal panel 7 for color) when both panels 6 and 7 are driven to the full open state. The corresponding value is set to 2.0 here as a specific example.

27, 28, and 29 are subtraction circuits 11, 12,
This is an addition circuit that adds the boost signal C1 from the second gain conversion circuit 26 to the 13 output signals R1, G1, and B1 and outputs them as color drive signals RD, GD, and BD.

Next, the operation will be described. First, FIG. 7 shows the first gain conversion circuit 22 and the clip circuit 2 shown in FIG.
5 shows the input-output characteristics of the portion 5, where the horizontal axis represents the input signal W to the first gain conversion circuit 22 and the vertical axis represents the output signal YD from the clip circuit 25. Is a volume (step-down circuit 2) that the user adjusts to obtain the desired brightness.
The gain adjustment position of 1) is shown. First gain conversion circuit 2
2 output / input = W1 / W = K is 0.5, 1.
This corresponds to the cases of 0 and 1.5.

Next, with reference to FIGS. 7 and 8, the state of each signal and the combined light transmitted through the panel at each gain adjustment position will be described. First, the case of the gain adjustment position, that is, the case where the brightness is relatively suppressed. Now, a white component signal operation circuit 10 is obtained from the input color signals R, G, B.
Assuming that the level of the white component signal W created by the above is Wp (S _{max in the} figure is the upper limit of the input signal), the first gain conversion circuit 22 calculates this as W1 = K · Wp = 0.5W
The gain is converted to p. In this case, the level is supplied to the luminance liquid crystal panel 6 as the luminance drive signal YD without being limited by the limiter 23. Accordingly, when the output Y1 of the subtraction circuit 24 is 0, the outputs R1, G1, and B1 from the subtraction circuits 11, 12, and 13 are supplied to the color liquid crystal panel 7 as the color drive signals RD, GD, and BD at the same level. Is done. As a result, the operation is exactly the same as described above with reference to FIG. 2B, and the brightness is relatively low, but has the same white component / color component ratio as the original color signals R, G, and B. A reproduced image is obtained.

Next, in the case where the gain adjustment position is set to the position, the level of the white component signal W is set to the same Wp
Therefore, as can be seen from FIG. 7, there is no limit operation of the limiter 23. Accordingly, in the same manner as in the case of the operation mode, the transmitted light LY is doubled by the gain conversion to twice the luminance drive signal YD, and the reproduced image having a relatively bright white component is adjusted as adjusted. can get.

Next, the operation when the gain adjustment position is set will be described. In this case, the first gain conversion circuit 22 sets the level Wp of the input white component signal W to 1.5.
The gain is doubled and output as a signal W1 (corresponding to the characteristic of K = 1.5 including the extension of the dotted line in FIG. 7). In the limiter 23, the input signal W1 is set to its own limit value YD.
Since more than _max, keep the output to YD = YD _max. As a result, the subtraction circuit 24 sets the level of the point P in FIG.
An overflow signal Y1 having a level different from _max is output. In the luminance driving signal of FIG. 8, a hatched portion corresponds to the overflow signal Y1.

The overflow signal Y1 is double-gain-converted by the second gain conversion circuit 26 and output as a boost signal C1. Here, the conditions required in both signals are as follows. That is, in order to obtain the same amount of transmitted light in the color liquid crystal panel 7 as the amount of transmitted light obtained when the signal Y1 is supplied to the luminance liquid crystal panel 6, all the R, G, and B pixels of the color liquid crystal panel 7 are used. The signal level commonly supplied to this is C1. Therefore, as described above, the second
The conversion constant of the gain conversion circuit 26 is set to 2.0, which is a value corresponding to the transmitted light amount ratio between the panels 6 and 7.

The boost signal C1 is added to the output signals R1, G1, and B1 from the subtraction circuits 11, 12, and 13 by adding circuits 27, 28, and 29, respectively, and the added output is used as the color drive signal RD, GD and BD are supplied to the color liquid crystal panel 7. In the color drive signal shown in FIG. 8, the hatched portion corresponding to the hatched dotted line corresponds to the boost signal C1.

[0057] Therefore, as shown in the rightmost column of FIG. 8, among the panel transmitted combined light, the transmitted light intensity for the liquid crystal panel 6 is remains in transmitted light LY when fed a limited maximum value YD _max The overflow exceeding the maximum value is compensated for on the color liquid crystal panel 7 side (corresponding to the transmitted light LC hatched with dotted oblique lines in the figure), and the real white component LW of the combined light is determined by the user in the gain adjustment position. Thus, 100% of the intended brightness is realized.

Note that the constants set by the first gain conversion circuit 22 and the second gain conversion circuit 26 in FIG. 6 are not limited to the values described above. As described above, it can be appropriately changed within a certain range.

FIG. 9 shows a modification of the circuit of FIG. FIG.
The same parts as those in FIG. 6 are denoted by the same reference numerals. 6 is different from FIG. 6 in that the white detection circuit 15 and the first multiplier 16
And switches 18a and 18b. Switch 18
Reference numerals a and 18b denote interlocking switches. When the white detection circuit 15 outputs the white detection signal SW, the first gain conversion circuit 22 and the clip circuit 25 described with reference to FIG. When 15 does not output the white detection signal SW, it operates to select the circuit of the first multiplier 16 described in FIG.

Therefore, when the circuit shown in FIG. 9 is employed, a faithful reproduced color can be realized for the chromatic portion without changing the saturation by the input color signal, and only the white portion meets the user's request. A reproduced image of any brightness can be obtained. For example, without affecting the background screen,
It is possible to respond to a request to adjust the brightness of only the title character on a white background as desired.

Embodiment 4 FIG. 10 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 4 of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.
In the fourth embodiment, since the transmitted light amount of the color liquid crystal panel 7 is lower than the transmitted light amount of the luminance liquid crystal panel 6, the reproduced image is reproduced as it is with the original color signals R, G, B. Is improved by devising a processing system for a color drive signal.

In the figure, reference numerals 30, 31, and 32 denote gain conversion circuits inserted on the output sides of the subtraction circuits 11, 12, and 13, respectively. As an example of the gain conversion circuit 30 for the color signal R, as shown in FIG. Gain conversion unit having a conversion characteristic in which the output signal rises at a predetermined gradient with respect to the rise of the input signal R1 so as to obtain an appropriate input-output characteristic, and the output signal from the gain conversion unit is converted to a predetermined upper limit level. R
There is an upper limit limiting unit for limiting with _Dmax . In the figure, S _max
Is the upper limit of the input signal. Here, as the above-mentioned predetermined gradient, when both panels 6 and 7 are driven to the full open state,
A value corresponding to (the amount of transmitted light of the liquid crystal panel 6 for luminance) / (the amount of transmitted light of the liquid crystal panel 7 for color), specifically, K =
2.0 is set.

Next, the operation will be described with reference to FIGS. FIG. 13 shows the level of each signal and the panel transmitted combined light when the conditions of the input color signals R, G, and B are changed. However, FIG. 1A shows a conventional case without a gain conversion circuit for comparison, and the description of itself is omitted. FIG. 13 (2-1) shows the color signal R,
G and B are the cases where both the brightness and the saturation correspond to a relatively medium level. Assuming that the signal R1 output by subtracting the white component signal W from the color signal R by the subtraction circuit 11 is at the level of R1p shown in FIG. 11, the gain conversion circuit 30 outputs the input signal R1 (= R1p ) With K = 2.0
The conversion is performed with a conversion characteristic having a gradient of, that is, the gain is converted to 2.0 times, and the level is output without any upper limit and supplied to the color liquid crystal panel 7 as a color drive signal RD.

As a result, as shown in the color drive signal of FIG. 13 (2-1), the level of the signal RD becomes lower than that of the prior art (FIG. 13 (1)).
And the transmitted light LR in the final panel transmitted combined light is also 2.0 times that of the conventional panel, and the white component / color component ratio of the original color signals R, G, and B is Reproduced images with the same ratio are obtained. In other words, the problem that the saturation of the reproduced image is reduced because the transmitted light amount of the color liquid crystal panel 7 is lower than that of the luminance liquid crystal panel 6 is solved.

Next, FIG. 13 (2-2) shows the color signals R, G,
When the brightness of B increases from (2-1), the level of the white component signal W increases accordingly, but the level of the signal R1 output from the subtraction circuit 11 is the same as in the case of (2-1). (R1 = R1p). Therefore, there is no change in the operating point of the gain conversion circuit 30 shown in FIG. 11, and as shown in the right end column of FIG. 11, panel transmitted combined light having a saturation faithful to the original signal is obtained.

Next, FIG. 13 (2-3) shows the operation when the saturation of the color signals R, G and B has increased from (2-2). In this case, the level of the color signal R is not different from the case of (2-2), but the level of the white component signal W is reduced.
As a result, the level of the signal R1, which is the output of the subtraction circuit 11, increases and R1 = R1q, and the operating point of the gain conversion circuit 30 falls within the upper limit region (FIG. 11). As a result, FIG.
3 As shown in the color drive signals (2-3), the color drive signals RD = RD _max that is reduced to the limit value is supplied to a color liquid crystal panel 7, the panel transmission combined light only transmitted light LR component It will be slightly cut.

FIG. 12 is a diagram that has been studied as a measure for alleviating the deterioration in the quality of the reproduced image based on the cut of the signal RD described with reference to FIG. 13 (2-3). That is, the slope portion of the gain conversion characteristic of the gain conversion circuit 30 is formed into a broken line shape having different slope portions (K = 2.0 and K = 0.5 in the figure). As can be seen from the figure, even at the level of R1 = R1q described above, the upper limit value RD _max
, The linearity of the reproduction characteristics is somewhat inferior, but the degradation of the reproduced image quality can be alleviated as a whole.

Instead of artificially creating the color signals R, G, and B themselves, a signal created via a video camera, such as a video signal of a television broadcast, generally has a saturation that is not compared with that of a video signal. As far as TV signals are handled,
It can be said that there is almost no operation timing to reach the upper limit region shown by (2-3). Therefore, the invention according to the fourth embodiment, which eliminates the decrease in the chroma of the reproduced image due to the difference in the amount of transmitted light between the panels 6 and 7, is effectively used in the field of multi-paths handling video signals. To demonstrate.

[0069] Incidentally, the conversion characteristics of the gain conversion circuit, for example, as shown in FIG. 14, by setting the polygonal line characteristic such that the output is the upper limit value RD _max when the input signal has reached its maximum value S _max If this is the case, the linearity of the reproduction characteristics is slightly degraded, but it is possible to reliably prevent the quality of the reproduced image from being lowered due to the cut of the signal RD.

Embodiment 5 FIG. FIG. 15 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 5 of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.
The fifth embodiment is intended to eliminate degradation in the quality of a reproduced image caused by the transmitted white chromaticity characteristics of the liquid crystal panel itself and the white chromaticity characteristics of the light source.

In FIG. 15, reference numerals 33, 34 and 35 denote boost signals YR, YG and YB by performing gain conversion using the white component signal W from the white component signal operation circuit 10 as an input signal and conversion characteristics for each of the three colors R, G and B. White chromaticity conversion circuits 36, 37, and 38 are subtraction circuits 11, 12, 13
Output signals R1, G1, B1 from the white chromaticity conversion circuits 33, 34, 35, respectively, boost signals YR, YG, Y
This is an addition circuit that adds B and outputs the resulting signals as color drive signals RD, GD, and BD.

Next, the operation will be described with reference to FIG. Although a specific example will be described later, in this case, as shown in FIG. 15, the conversion characteristics of each white chromaticity conversion circuit are such that the outputs of the white chromaticity conversion circuits 33 and 34 are always zero and the white chromaticity conversion circuit The description will be made on the assumption that only the circuit 35 has a characteristic in which the output signal increases as the input signal increases. FIG. 16 shows a case where the brightness (brightness) of the input color signals R, G, and B changes in a conventional case (when no white chromaticity conversion circuit is provided).
This will be described in comparison with.

FIGS. 11A and 11B show the conventional cases where the brightness is low and the brightness is high, respectively.
Since all of B are occupied by the white component signal W and there is no white chromaticity conversion circuit, the panel transmitted combined light is only the transmitted light LY from the luminance liquid crystal panel 6, and the transmitted light LR and LG from the color liquid crystal panel 7. , LB are both zero. Therefore, as shown in the chromaticity diagram of FIG. 17, for example, as the transmission white chromaticity characteristic of the luminance liquid crystal panel 6 itself, there is a tendency that the so-called color temperature decreases as the drive control opening increases. (A general liquid crystal panel), the hue of the reproduced image is shifted depending on the brightness of the white color, which is not preferable as the image quality.

On the other hand, when the white chromaticity conversion circuit shown in FIG. 15 is provided, the input color signals R, G, and B are output as shown in (2-1) and (2-2) of FIG. White component signal W
, But the color drive signal B of color B
D is created, and the transmitted light LB from the color liquid crystal panel 7 is added to the panel transmitted synthesized light. And this transmitted light LB
Increases as the magnitude of the white component signal W, that is, the brightness of the color signals R, G, and B, increases, and compensates for the shift due to the opening degree of the white chromaticity of the luminance liquid crystal panel 6 itself as a whole.

FIG. 18 shows the white chromaticity obtained to compensate for the above-described shift due to the opening based on the transmission white chromaticity characteristics when the opening of the luminance liquid crystal panel 6 is changed (FIG. 17). This is a gain conversion characteristic of the conversion circuit 35. Note that FIG.
Is a fifth embodiment of the present invention provided with a white chromaticity conversion circuit.
Are quantitatively shown in the case where is applied. In the figure, points □ and point 無 indicate the cases where there is no adjustment by the white chromaticity conversion circuit and the case where the adjustment is made (both are 100% open). That is, it is understood that the adjustment by the white chromaticity conversion circuit almost eliminates the decrease in the white color temperature due to the increase in the opening degree.

FIG. 20 explains the outline of the case where the same invention shown in FIG. 15 is applied for the purpose of eliminating the deterioration of the reproduced image quality caused by the white chromaticity characteristic of the light source. That is, the white chromaticity (color temperature) differs depending on the type of the lamp constituting the light source. The figure shows this situation on a chromaticity diagram. In the figure, a point □ is a metal halide lamp, and a point で is a halogen lamp, both of which show light transmitted through a liquid crystal panel whose opening is controlled to 100%. ing. In this case as well, by appropriately setting the respective gain conversion characteristics of the white chromaticity conversion circuits 33, 34, and 35 in FIG. Chromaticity (color temperature) can be obtained.

In each of the above embodiments, the case where the color liquid crystal panel 7 is applied to the liquid crystal projector composed of one panel shown in FIG. 22B has been described. Is further divided into three optical paths, each of which is provided with a color liquid crystal panel dedicated to R, G, and B, and is similarly applied to a liquid crystal projector of a type that is driven and controlled by color drive signals RD, GD, and BD, respectively. And have the same effect.

[0078]

As described above, in the liquid crystal projector according to the first aspect, a white component signal calculation circuit for generating a white component signal from three color signals, and the white component signal from the three color signals. A subtraction circuit that subtracts each of the signals to output three color drive signals;
Since the multiplication circuit for multiplying by a smaller predetermined constant and outputting the result as a luminance drive signal is provided, a decrease in chroma in a reproduced image due to a difference in transmitted light amount between the two liquid crystal panels is suppressed.

Further, in the liquid crystal projector according to the second aspect, the predetermined constant is set to (transmitted light amount of the color liquid crystal panel) / (transmitted light amount of the luminance liquid crystal panel) when both panels are driven fully open. Since the values are equivalent, a reproduced image having the same saturation as the input color signal can be obtained regardless of the difference in the amount of transmitted light between the two liquid crystal panels.

In the liquid crystal projector according to the third aspect, a white component signal calculation circuit for generating a white component signal from the three color signals, and subtracting the white component signal from the three color signals respectively to produce three color signals. A subtraction circuit that outputs a color drive signal; a white detection circuit that detects whether the composite color of the three color signals is white; and a first first signal that is smaller than 1 when the white component is not detected. Is multiplied by the constant and the result is output as a luminance drive signal. When the white color is detected, the white component signal is multiplied by a predetermined second constant larger than the first constant and output as the luminance drive signal. Since the switching multiplying circuit is provided, when the input color signal is a chromatic color, a decrease in the saturation of the reproduced image due to the difference in the amount of transmitted light between the two liquid crystal panels is suppressed, and the input color signal is achromatic ( For color) brightness of the reproduced image increases.

In the liquid crystal projector according to the fourth aspect, the first constant is (transmitted light amount of the color liquid crystal panel) / (transmitted light amount of the luminance liquid crystal panel) when both panels are fully opened. Therefore, a reproduced image having the same saturation as the input color signal can be obtained regardless of the difference in the amount of transmitted light between the two liquid crystal panels.

Further, in the liquid crystal projector according to the fifth aspect, since the second constant is set to 1, a bright reproduced image can be obtained by effectively utilizing the transmitted light amount of the luminance liquid crystal panel.

In the liquid crystal projector according to the sixth aspect, since the second constant is set to a value that increases as the white component signal increases, visual unnaturalness due to the constant switching is reduced.

In the liquid crystal projector according to the seventh aspect, a white component signal operation circuit for generating a white component signal from three color signals, and subtraction for subtracting and outputting the white component signals from the three color signals, respectively. A first gain conversion circuit for converting the gain of the white component signal and outputting the converted signal;
When the output signal of the first gain conversion circuit is equal to or lower than the predetermined upper limit level, it is output as it is as a luminance drive signal. When the output signal of the first gain conversion circuit exceeds the upper limit level, the luminance drive signal is output. A clip circuit that outputs a signal as the luminance drive signal and outputs an amount exceeding the upper limit level as an overflow signal, a second gain conversion circuit that converts and outputs a gain of the overflow signal, and a subtraction circuit. The output signal of the second gain conversion circuit is added to the color output signal to obtain 3
Since it has an addition circuit that outputs it as a color drive signal for the color,
A reproduced image with a desired brightness can be obtained by using a liquid crystal panel for luminance or, if necessary, a liquid crystal panel for color.

Further, in the liquid crystal projector according to the eighth aspect, the first gain conversion circuit converts the white component signal into one.
A multiplication circuit configured to multiply and output a larger predetermined third constant and a step-down circuit configured to step down an output signal of the multiplication circuit to an arbitrary level and output the same are adjusted in order to obtain a desired brightness. It will be easier.

In the liquid crystal projector according to the ninth aspect, the third constant is set to ((the amount of transmitted light of the liquid crystal panel for color) / (the amount of transmitted light of the liquid crystal panel for luminance) when both panels are fully opened. )) Since the value is set to +1, the brightness can be adjusted in accordance with the difference in the amount of transmitted light between the two liquid crystal panels.

In the liquid crystal projector according to the tenth aspect, the second gain conversion circuit is constituted by a multiplication circuit that multiplies the overflow signal by the following constant and outputs the result.
The constant was a value equivalent to (the amount of light transmitted through the liquid crystal panel for luminance) / (the amount of light transmitted through the liquid crystal panel for color) when both panels were driven fully open. At a precise level corresponding to the adjusted desired brightness.

Further, in the liquid crystal projector according to the eleventh aspect, a switching circuit is inserted between the white component signal operation circuit and the first gain conversion circuit, and the composite color of the three color signals is white. And a white component signal which is output only when the white color is detected.
When the white color is not detected, a signal obtained by multiplying the white component signal by a predetermined fourth constant smaller than 1 is directly output as a luminance drive signal. , A reproduced image having a desired brightness can be obtained.

Further, in the liquid crystal projector according to the twelfth aspect, the fourth constant is (transmitted light amount of the color liquid crystal panel) / (transmitted light amount of the luminance liquid crystal panel) when both panels are fully opened. Therefore, a reproduced image having the same saturation as the input signal can be obtained for the chromatic color portion.

In the liquid crystal projector according to the thirteenth aspect, a white component signal calculation circuit for generating a white component signal from three color signals and outputting the white component signal as a luminance drive signal, and converting the white component signal from the three color signals, respectively. A subtraction circuit for performing subtraction and output, and a gain conversion circuit for converting the gain of an output signal of the subtraction circuit and outputting the result as color drive signals of three colors are provided, so that the saturation of a reproduced image can be enhanced and adjusted. Become.

In the liquid crystal projector according to the fourteenth aspect, the gain conversion circuit includes a gain conversion section having a conversion characteristic in which an output signal rises with the following gradient with respect to an increase in an input signal; And an upper limiter for limiting the output signal at a predetermined upper limit level. The gradient is (transmitted light amount of the liquid crystal panel for luminance) / (transmitted light amount of the liquid crystal panel for color) when both panels are driven fully open. ), It is possible to eliminate the decrease in the chroma in the reproduced image due to the difference in the amount of transmitted light between the two liquid crystal panels without suppressing the brightness.

In the liquid crystal projector according to the fifteenth aspect, the (output / input) gradient in the relatively high level portion is set low in the conversion characteristic region below the upper limit level of the gain conversion section. It is possible to alleviate a decrease in image quality due to a saturation phenomenon of the color drive signal during enhancement.

Further, in the liquid crystal projector according to the sixteenth aspect, the gain conversion circuit is arranged such that, when the input signal is at a relatively low level from 0 to a predetermined value, the output signal has the following gradient with respect to the rise of the input signal. In the relatively high level portion where the input signal is from the predetermined value to the input maximum value, the output signal rises at a slope lower than the following slope in response to the rise of the input signal. It has a conversion characteristic that reaches the fully open level, and the gradient is
When both panels are driven fully open, a value equivalent to (the amount of light transmitted through the liquid crystal panel for luminance) / (the amount of light transmitted through the liquid crystal panel for color) is used to prevent saturation of the color drive signal when saturation is enhanced. can do.

In the liquid crystal projector according to the seventeenth aspect, a white component signal operation circuit for generating a white component signal from three color signals and outputting the white component signal as a luminance drive signal, and converting the white component signal from the three color signals into the white signal, respectively. A subtraction circuit for subtracting and outputting the signal, receiving the white component signal, and inputting R, G, B3
A white chromaticity conversion circuit that performs gain conversion based on conversion characteristics for each color and outputs the result, and adds an output signal of the subtraction circuit and an output signal of the white chromaticity conversion circuit for each of R, G, and B colors to obtain 3
Since it has an addition circuit that outputs it as a color drive signal for the color,
Arbitrary correction of white chromaticity becomes possible.

In the liquid crystal projector according to the eighteenth aspect, the white chromaticity conversion circuit sets the conversion characteristic so as to suppress a change in chromaticity of white transmitted light due to a change in intensity of a drive signal in the liquid crystal panel. Therefore, a reproduced image having a desired white chromaticity is always obtained regardless of the opening degree of the liquid crystal panel.

In the liquid crystal projector according to the nineteenth aspect, the white chromaticity conversion circuit is arranged such that the output signal is always zero for the R and G colors, and the output signal increases with the input signal for the B color. Since gain conversion is performed, gain conversion characteristics for compensating for a shift in white chromaticity due to the degree of opening of the liquid crystal panel can be easily obtained.

Further, in the liquid crystal projector according to the twentieth aspect, the white chromaticity conversion circuit adjusts the chromaticity of the white transmitted light that differs depending on the type of the light source or the liquid crystal panel so as to match the desired white chromaticity. Since the conversion characteristics are set, a high-quality reproduced image having a desired white chromaticity can always be obtained regardless of the type of the light source or the liquid crystal panel.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating an operation of the liquid crystal projector using the circuit of FIG.

FIG. 3 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 2 of the present invention.

FIG. 4 is a diagram illustrating an operation of the liquid crystal projector by the circuit of FIG.

FIG. 5 is a diagram showing a modification of the second embodiment.

FIG. 6 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 3 of the present invention.

FIG. 7 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 8 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 9 is a diagram showing a modification of the third embodiment.

FIG. 10 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 4 of the present invention.

11 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 12 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 13 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 14 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 15 is a circuit diagram showing a configuration of a signal processing system of a liquid crystal projector according to Embodiment 5 of the present invention.

FIG. 16 is a diagram illustrating the operation of the liquid crystal projector using the circuit of FIG.

FIG. 17 is a diagram illustrating a change in white chromaticity of transmitted light when an opening of a liquid crystal panel is changed.

18 is a diagram illustrating details of gain conversion characteristics of the white chromaticity conversion circuit 35 of FIG.

19 is a diagram illustrating an effect of the liquid crystal projector by the circuit of FIG.

FIG. 20 shows a liquid crystal projector using the circuit of FIG.
It is a figure explaining the effect at the time of applying for the purpose of compensating for white chromaticity difference of a lamp.

FIG. 21 is a configuration diagram showing a conventional liquid crystal projector.

FIG. 22 is a diagram showing a configuration of a liquid crystal panel for luminance 6 and a liquid crystal panel for color 7, particularly a distribution state of pixels thereof.

[Explanation of symbols]

Reference Signs List 1 lamp, 6 luminance liquid crystal panel, 7 color liquid crystal panel, 10 white component signal operation circuit, 11, 12, 1
3 subtraction circuit, 14 multiplication circuit, 15 white detection circuit,
16 first multiplier, 17, 17a second multiplier, 1
8, 18a, 18b switching device, 19 switching multiplying circuit, 2
0 multiplication circuit, 21 step-down circuit, 22 first gain conversion circuit, 23 limiter, 24 subtraction circuit, 25 clip circuit, 26 second gain conversion circuit, 27, 28,
29 addition circuit, 30, 31, 32 gain conversion circuit,
33, 34, 35 White chromaticity conversion circuit, 36, 37, 3
8 Addition circuit, R, G, B color signal, W white component signal, YD luminance drive signal, RD, GD, BD color drive signal, LY luminance transmitted light, LR, LG, LB color transmitted light.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teruo Miyamoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Tomoyuki Kanda 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Inside Rishi Electric Co., Ltd. (72) Inventor Yasuhito Nai 2-3-2 Marunouchi, Chiyoda-ku, Tokyo

Claims (20)

[Claims] 1. A light source for separating light from a light source, a liquid crystal panel for luminance on one optical path, and a liquid crystal panel for color on the other optical path, respectively, based on R, G, and B color signals. A liquid crystal projector that creates a luminance drive signal for driving the luminance liquid crystal panel and R, G, and B color drive signals for driving the color liquid crystal panel, and combines and projects light transmitted through both panels. In the above, a white component signal operation circuit for creating a white component signal from the three color signals, a subtraction circuit for subtracting the white component signal from the three color signals and outputting the same as the three color drive signals, And a multiplying circuit for multiplying the white component signal by a predetermined constant smaller than 1 and outputting the multiplied signal as the luminance drive signal. 2. The method according to claim 1, wherein the predetermined constant is a value corresponding to (the amount of light transmitted through the liquid crystal panel for color) / (the amount of light transmitted through the liquid crystal panel for luminance) when both panels are driven fully open. The liquid crystal projector according to claim 1. 3. Separating light from a light source, a luminance liquid crystal panel is provided on one of the optical paths, and a color liquid crystal panel is provided on the other optical path, based on color signals of R, G, and B colors. A liquid crystal projector that creates a luminance drive signal for driving the luminance liquid crystal panel and R, G, and B color drive signals for driving the color liquid crystal panel, and combines and projects light transmitted through both panels. In the above, a white component signal operation circuit for creating a white component signal from the three color signals, a subtraction circuit for subtracting the white component signal from the three color signals and outputting the same as the three color drive signals, A white detection circuit for detecting whether or not the composite color of the three color signals is white; and, when the white color is not detected, multiplying the white component signal by a predetermined first constant smaller than 1 to drive the luminance. As a signal A switching multiplying circuit for multiplying the white component signal by a predetermined second constant larger than the first constant and outputting the luminance component as the luminance drive signal when the white color is detected. Liquid crystal projector. 4. The method according to claim 1, wherein the first constant is a value corresponding to (the amount of light transmitted through the liquid crystal panel for color) / (the amount of light transmitted through the liquid crystal panel for luminance) when both panels are driven fully open. The liquid crystal projector according to claim 3, wherein 5. The liquid crystal projector according to claim 3, wherein the second constant is set to 1. 6. The liquid crystal projector according to claim 3, wherein the second constant is a value that increases as the white component signal increases. 7. A light source for separating light from a light source, a liquid crystal panel for luminance on one optical path, and a liquid crystal panel for color on the other optical path, respectively, based on color signals of R, G, and B colors. A liquid crystal projector that generates a luminance drive signal for driving the luminance liquid crystal panel and R, G, and B color drive signals for driving the color liquid crystal panel, and combines and projects light transmitted through both panels. In the above, a white component signal calculation circuit for generating a white component signal from the three color signals, a subtraction circuit for subtracting and outputting the white component signals from the three color signals, and converting a gain of the white component signal A first gain conversion circuit that outputs
When the output signal of the first gain conversion circuit is equal to or lower than a predetermined upper limit level, the signal is output as it is as the luminance drive signal, and when the output signal of the first gain conversion circuit exceeds the upper limit level, the upper limit level And a clipping circuit that outputs the signal as the luminance drive signal and outputs an amount exceeding the upper limit level as an overflow signal, a second gain conversion circuit that converts and outputs the gain of the overflow signal, and a subtraction circuit. A liquid crystal projector comprising an addition circuit for adding output signals of the second gain conversion circuit to output signals of three colors, respectively, and outputting the added signals as color drive signals of the three colors. 8. A multiplying circuit for multiplying a white component signal by a predetermined third constant greater than 1 and outputting the first gain converting circuit, and an output signal of the multiplying circuit stepped down to an arbitrary level for output. 8. The liquid crystal projector according to claim 7, wherein said liquid crystal projector is constituted by a step-down circuit. 9. The third constant is a value corresponding to ((the amount of transmitted light of the liquid crystal panel for color) / (the amount of transmitted light of the liquid crystal panel for luminance)) + 1 when both panels are driven fully open. The liquid crystal projector according to claim 8, wherein: 10. The liquid crystal projector according to claim 8, wherein the second gain conversion circuit is configured by a multiplication circuit that multiplies the overflow signal by the following constant and outputs the result. The constant is when both panels are driven fully open,
A value corresponding to (the transmitted light amount of the luminance liquid crystal panel) / (the transmitted light amount of the color liquid crystal panel) is used. 11. A white detection circuit which inserts a switching circuit between a white component signal operation circuit and a first gain conversion circuit and detects whether or not a composite color of three color signals is white. Only when the white color is detected, the white component signal is input to the first gain conversion circuit. When the white color is not detected, the white component signal is multiplied by a predetermined fourth constant smaller than 1 to directly drive the luminance. 11. The liquid crystal projector according to claim 7, wherein the liquid crystal projector outputs a signal. 12. The method according to claim 1, wherein the fourth constant is a value corresponding to (the amount of light transmitted through the liquid crystal panel for color) / (the amount of light transmitted through the liquid crystal panel for luminance) when both panels are driven to the full open state. The liquid crystal projector according to claim 11, wherein 13. A light source for separating light from a light source, a liquid crystal panel for luminance on one optical path, and a liquid crystal panel for color on the other optical path, respectively, based on color signals of R, G, and B colors. A liquid crystal projector that creates a luminance drive signal for driving the luminance liquid crystal panel and R, G, and B color drive signals for driving the color liquid crystal panel, and combines and projects light transmitted through both panels. , A white component signal operation circuit that creates a white component signal from the three color signals and outputs the white component signal as the luminance drive signal, a subtraction circuit that subtracts and outputs the white component signal from the three color signals, respectively, A liquid crystal projector comprising a gain conversion circuit that converts the gain of an output signal of the subtraction circuit and outputs the result as the three color drive signals. 14. A gain conversion circuit, comprising: a gain conversion section having a conversion characteristic in which an output signal rises at the following gradient with respect to an increase in an input signal; and limiting an output signal from the gain conversion section to a predetermined upper limit level. 14. The liquid crystal projector according to claim 13, wherein the liquid crystal projector is constituted by an upper limit restricting unit.
The gradient is a value corresponding to (the amount of light transmitted through the liquid crystal panel for luminance) / (the amount of light transmitted through the liquid crystal panel for color) when both panels are driven fully open. 15. A conversion characteristic region of a gain conversion section below an upper limit level, wherein an (output / input) gradient in a relatively high level portion is set lower than the value described in claim 14. The liquid crystal projector according to claim 14. 16. The gain conversion circuit has a conversion characteristic in which the output signal rises with the following gradient with respect to the rise of the input signal in a relatively low level portion of the input signal from 0 to a predetermined value. In a relatively high level portion where the input signal is from the predetermined value to the input maximum value, the output signal has a conversion characteristic in which the output signal rises with a gradient lower than the following gradient to reach the panel fully open level with respect to the rise of the input signal. The liquid crystal projector according to claim 13, wherein: The gradient is
When both panels are driven fully open, a value corresponding to (the amount of transmitted light of the liquid crystal panel for luminance) / (the amount of transmitted light of the liquid crystal panel for color) is used. 17. A light source for separating light from a light source, a liquid crystal panel for luminance on one optical path, and a liquid crystal panel for color on the other optical path, respectively, based on color signals of R, G, and B colors. A liquid crystal projector that creates a luminance drive signal for driving the luminance liquid crystal panel and R, G, and B color drive signals for driving the color liquid crystal panel, and combines and projects light transmitted through both panels. In the above, a white component signal operation circuit that creates a white component signal from the three color signals and outputs the white component signal as the luminance drive signal, a subtraction circuit that subtracts and outputs the white component signal from the three color signals, Input white component signal, and R, G, B
A white chromaticity conversion circuit that performs gain conversion with conversion characteristics for three colors and outputs the result, and adds an output signal of the subtraction circuit and an output signal of the white chromaticity conversion circuit for each of R, G, and B colors, and A liquid crystal projector comprising an addition circuit that outputs three color drive signals. 18. The white chromaticity conversion circuit has a conversion characteristic set so as to suppress a change in chromaticity of white transmitted light due to a change in intensity of a drive signal in a liquid crystal panel. Item 18. A liquid crystal projector according to Item 17. 19. The white chromaticity conversion circuit is characterized in that gain conversion is performed so that the output signal is always zero for R and G colors and the output signal is increased for B color as the input signal increases. The liquid crystal projector according to claim 18, wherein 20. The white chromaticity conversion circuit sets the conversion characteristics so that the chromaticity of white transmitted light that differs depending on the type of the light source or the liquid crystal panel matches the desired white chromaticity. The liquid crystal projector according to claim 17, wherein: