JP3801573B2 - projector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video display device such as a data projector.
[0002]
[Prior art]
In recent years, there has been an increasing demand for further improvements in brightness and color reproducibility in video display devices such as data projectors used when giving presentations in companies or schools.
[0003]
FIG. 5 is a configuration diagram showing an example of a projector using a reflective display element and a color wheel as an example of a conventional video display device.
[0004]
In FIG. 5, reference numeral 53 denotes a reflective display element, which is recently known as DMD (Digital Micromirror Device), LCOS (Liquid Crystal On Silicon), or the like. Reference numeral 56 denotes a light source for irradiating the reflective display element 53, and 57 denotes a color wheel including at least three kinds of color filters that transmit red, blue, and green color lights. By allowing the emitted light to pass therethrough, the light is divided into red, blue, and green, and irradiated to the reflective display element 53. 50 is an input terminal for the input video signal Vin, and 51 is a signal processing circuit section for the input video signal Vin. Reference numeral 52 denotes a drive control unit for driving the reflective display element 53, which converts and controls the output video signal from the signal processing circuit unit 51 into a signal format for driving the reflective display element 53, and rotates the color wheel 55. In synchronism, for example, while red light is passing, the red component of the video signal component acts to drive the reflective display element 53. The same applies to blue and green. Reference numeral 54 denotes a projection lens, and the red, blue, and green lights reflected by the reflective display element 53 are projected through the projection lens 54.
[0005]
Next, the details of the color wheel will be described with reference to FIGS. 6A and 6B.
[0006]
FIG. 6A is a plan view showing a configuration of a three-divided color wheel. In FIG. 6A, the three-segment color wheel 70 includes, as an example, a red color filter 72 that passes red light, a blue color filter 73 that passes blue light, and a green color filter 74 that passes green light. It consists of.
[0007]
FIG. 6B is a plan view showing a configuration of a four-divided color wheel. In FIG. 6B, in addition to the red color filter 72, the blue color filter 73, and the green color filter 74, the white color that passes white light, that is, red, blue, and green light is added to the four-divided color wheel 55. A color filter 71 is provided. In particular, in a data projector mainly intended for presentation, a four-division color wheel 55 provided with a white color filter 71 is used because high luminance is required. When the four-division color wheel 55 is used, the white color component pixel is driven by the drive control unit 52 as white separately from red, blue, and green, so that in addition to red, blue, and green, white As a result, the luminance is increased by increasing the amount of light emitted from the white portion of the image to the pixel.
[0008]
However, the four-divided color filter 55 is smaller than the three-divided color filter 70 in that the total divided angle of each of the red, blue, and green color filters is reduced by the angle of the white color filter 71. The irradiation time of each color light of red, blue, and green with respect to a pixel that is not included is shorter than the irradiation time of each color light of red, blue, green, and white with respect to a pixel that includes a white component. As a result, the brightness of the video portion that does not include the white component in the projected video screen is darker than the brightness of the video portion that includes the white component. In addition, as the division angle of the white color filter 71 is increased, the brightness ratio is further increased.
[0009]
It is also empirically known that dark image portions that exist simultaneously in a bright screen appear darker due to brightness contrast among human visual characteristics. That is, for example, a portion with a color other than white on a screen with a bright white background is recognized as a darker color.
[0010]
Furthermore, depending on the visual characteristics, for intermediate colors such as yellow, cyan, and magenta, there is a phenomenon in which the intermediate color portion that appears dark when brightness contrast occurs appears to be a different color due to the change in hue. Is particularly noticeable for yellow, yellow that appears dark is rather perceived as dark green.
[0011]
As described above, the luminance can be increased as the division angle of the white color filter 71 in the four-division color wheel 55 is increased. However, the above phenomenon becomes more apparent.
[0012]
A video display device that interprets the above phenomenon as being caused by the average luminance level of the screen and improves the contrast of the screen based on the average luminance level of the screen is known (for example, see Patent Document 1). FIG. 7 is a block diagram showing an electric circuit configuration of such a conventional video display device.
[0013]
In FIG. 7, reference numeral 81 denotes a luminance level determination unit, and 82 denotes a luminance level distribution detection unit. Reference numeral 83 denotes a control unit (CPU) that generates a control signal for controlling a control operation point for the input video signal Vin from the input terminal 50 in accordance with the result detected by the luminance level distribution detection unit 82. Reference numeral 84 denotes a control signal. This is an operating point control unit that performs operating point control on the input video signal Vin based on the output signal of the unit 83.
[0014]
Next, the operation of the conventional video display apparatus configured as described above will be described.
[0015]
In FIG. 7, the luminance level determination unit 81 determines the luminance level of the input video signal 50, and outputs an average luminance level for each scanning line as an example. The luminance level distribution detection unit 82 detects the distribution state of the average luminance level in the entire screen based on the average luminance level for each scanning line obtained in the luminance level determination unit 81. As an example, the luminance level distribution detection unit 82 divides the luminance level range into a plurality of ranges and provides a counter for each of the divided ranges, and the average luminance level of each scanning line is in which range of the plurality of ranges. The distribution state is detected by increasing the count value representing the distribution of the range depending on whether it is included. As a result, for example, when the average luminance level is concentrated and distributed in a high range, the control unit 83 outputs a control signal for causing the input video signal Vin to perform a white expansion operation. On the other hand, when the average luminance level is low, the control unit 83 outputs a control signal for performing a black compression operation on the input video signal Vin. The operating point control unit 84 performs white expansion or black compression operation on the input video signal Vin in accordance with a control signal from the control unit 83 to improve the contrast of the screen.
[0016]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-115018
[0017]
[Problems to be solved by the invention]
However, in the conventional configuration described above, since the signal correction operation point control for the input video signal is performed based on the average luminance level, pixels that do not contain a white component are also subject to luminance level detection. Even if the screen has few components, the problem is that if the brightness level is high, the correction is performed, the problem is that correction is also performed for color components that do not need to be corrected, There has been a problem that correction cannot be performed selectively only for color components.
[0018]
The present invention solves the above-mentioned conventional problems, and its object is to improve the brightness of the intermediate color and the change in hue due to visual characteristics when the brightness is increased by the white color filter. projector Is to provide.
[0019]
[Means for Solving the Problems]
The present invention corrects the level or hue for a specific color component, for example, an intermediate color, according to the distribution state of a specific color component, that is, the distribution state of a white component, for example, instead of the average luminance level of the screen. It corrects a decrease in brightness due to the color components constituting the pixel and corrects a change in hue due to visual characteristics. The configuration for this is shown below.
[0020]
To achieve the above object, according to the present invention. projector A color component separation / extraction unit that separates and extracts each color component constituting the pixel of each pixel of the input video signal; White among each color component Detect the distribution of color components in the screen White A color component distribution detector; White Control signal generating means for generating a correction control signal for a specific color component according to the output signal of the color component distribution detecting section, and output from the color component separation detecting section based on the correction control signal output from the control signal generating means. And a video signal correction unit that corrects an input video signal based on an output signal from the calculation control unit.
[0021]
According to this configuration, a specific color component in the input video signal is separated and extracted, White By detecting the distribution of color components in the screen, instead of the average luminance level of the screen, White Depending on the distribution state of the color components, it is possible to correct a specific color component, for example, an intermediate color.
[0022]
According to the present invention projector The control signal generating means preferably generates a correction control signal for correcting the level of a specific color component.
[0023]
According to this configuration, it is possible to correct, for example, a decrease in brightness of the intermediate color as the specific color component by selectively changing the gain with respect to the specific color component that appears darker.
[0024]
In the video display device according to the present invention, it is preferable that the control signal generating means generates a correction control signal for correcting the hue of a specific color component.
[0025]
According to this configuration, White The hue change due to the visual characteristic can be corrected by selectively changing the hue with respect to a specific color component that changes in hue due to the visual characteristic depending on the distribution state of the color component in the screen.
[0026]
Further, according to the present invention projector In the control signal generating means, White It is preferable to generate a correction control signal corresponding to the output signal from the color component separation and extraction unit in addition to the output signal from the color component distribution detection unit.
[0027]
According to this configuration, the degree of correction can be changed according to the distribution state of the specific color component and the level or hue of the specific color component, and as a result, optimal correction can be performed for each pixel.
[0029]
According to this configuration, in addition to the red, blue, and green color filters that are normally used for projectors, the white color filter that is normally used to achieve high brightness is affected by white light that increases the amount of light emitted. Appropriate correction can be performed according to the distribution state of the white component in the screen for a specific pixel that does not include a white component that becomes relatively dark with respect to the pixel that includes the component. Faithfully reproduces brightness and hue.
[0030]
Further, according to the present invention projector In White The color component distribution detection unit divides one screen into a plurality of areas, and White The distribution state of the color component is detected, and the control signal generating means White It is preferable to generate a correction control signal corresponding to the distribution state of the color components.
[0031]
According to this configuration, in the input video signal White By detecting the color distribution state as a spatial distribution state detection in which one screen is divided into a plurality of regions, each region according to the distribution state of each spatial region for a specific color that requires correction It is possible to perform correction every time, and it is possible to appropriately correct the brightness and hue for each finer spatial area.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0033]
(Embodiment 1)
FIG. 1 relates to the first embodiment of the present invention. projector It is a block diagram which shows the electric circuit structure.
[0034]
In FIG. 1, reference numerals 10, 11, and 12 denote input terminals. In this embodiment, a red video signal Rin, a green video signal Gin, and a blue video signal Bin (hereinafter, Rin, Gin, and Bin are collectively shown). (Referred to as an input video signal), but other forms in which a luminance signal and a color difference signal are input may be used.
[0035]
Reference numeral 1 denotes a color component separation / extraction unit that separates and extracts specific color components a, b, c, and d constituting the input video signal. In this embodiment, “a” is a magenta color component, “b” is a cyan component, “c” is a yellow component, and “d” is a white component. However, a specific color component other than these components can be separately extracted and corrected. The color components are separated and extracted.
[0036]
Reference numeral 2 denotes a white component distribution detection unit, which divides the signal level into a plurality of ranges and counts which of the plurality of ranges the output signal level of the color component separation / extraction unit 1 is included in. m, n, x, and y are signals indicating the distribution state of the occurrence frequency in each range when the signal level of the white component d is divided into four ranges in the white component distribution detection unit 2. Note that the pixels to be detected by the white component distribution detection unit 2 are preferably all pixels in one screen, but representative pixels thinned out in the horizontal and vertical directions may be used.
[0037]
Reference numeral 4 denotes a gain control signal generator as a control signal generator, and a specific color corresponding to the frequency m, frequency n, frequency x, frequency y, and white component d, which are output signals of the white component distribution detector 2. As a correction control signal for correcting the component level, a yellow component correction gain value p1, a cyan component correction gain value q1, a magenta component correction gain value s1, and a white component correction gain value t1 are generated. In the present embodiment, the white component distribution detector 2 divides the signal level into four ranges, but it is desirable to determine the number of divisions according to the accuracy with which correction is performed. Further, the range to be divided does not need to be equal, and is desirably determined according to the accuracy with which correction is performed.
[0038]
Reference numeral 5 denotes an arithmetic control unit, which converts each color component a to d that is an output signal of the color component separation output unit 1 based on each specific color component correction gain value p1 to t1 that is an output signal of the gain control signal generation unit 4. A level of a specific color component is corrected by performing a multiplication process. The arithmetic control unit 5 includes multipliers 20, 21, 22, and 23. u, v1, w1, and z1 are corrections obtained as a result of multiplication by the multiplier 23, the multiplier 20, the multiplier 21, and the multiplier 22, respectively. Value. The multiplier 20 outputs a correction value for the yellow component by multiplying the yellow component correction gain value p1 by the yellow component c. Similarly, the multipliers 21 and 22 and the multiplier 23 output the correction value w1, the correction value z1, and the correction value u for the cyan color component, the magenta color component, and the white color component, respectively.
[0039]
Reference numeral 6 denotes a video signal correction unit. The correction value u, the correction value v1, the correction value w1, and the correction value z1 obtained by the calculation control unit 5 are used as a red video signal Rin, a green video signal Gin, and a blue video signal Bin. Is added to correct the signal level. The video signal correction unit 6 includes adders 24, 25, 26, 27, 28, 29, 30 and 31. When correcting the white component, the correction level u is added to Rin, Gin, and Bin to correct the signal level. When correcting the yellow component, the correction value v1 is set only to Rin and Gin. The signal level is corrected by adding. Similarly, with respect to the correction value w1 and the correction value z1, input video signals to be subjected to addition differ depending on the color component to be corrected.
[0040]
Reference numerals 13, 14, and 15 denote output terminals to which the red video signal Rout, the green video signal Gout, and the blue video signal Bout corrected by the video signal correction unit 6, respectively, are output.
[0041]
Next, the operation of the video display apparatus configured as described above will be described with reference to FIGS. 3 and 4 in addition to FIG.
[0042]
FIG. 3 is a diagram showing signal levels of Rin, Gin, and Bin color signals that are input video signals in FIG. 41 indicates the Rin signal level, 42 indicates the Gin signal level, and 43 indicates the Bin signal level. Reference numeral 46 denotes a signal portion that is equally included in the Rin, Gin, and Bin color signals, that is, a white component. Reference numeral 45 denotes a portion where the signal components of Rin and Gin are equal, that is, a yellow component. Reference numeral 44 denotes a single color component of Gin. Although not shown in FIG. 3, similarly, a signal portion including Gin and Bin equal to each other is a cyan color component, and a signal portion including Rin and Bin equal to each other is a magenta color component.
[0043]
First, in the color component separation and extraction unit 1 in FIG. 1, each color component described in FIG. 3 is separated and extracted by comparing the signal levels of Rin, Gin, and Bin, and a magenta color component a, cyan color component b, Output as yellow component c and white component d. The white component distribution detection unit 2 detects the signal level of the white component d, and increases the count value of the range included depending on which of the preset four divided ranges is included.
[0044]
FIG. 4 is a diagram illustrating the frequency of occurrence with respect to the signal level for explaining an example of the operation of the white component distribution detection unit 2. In FIG. 4, the signal level is divided into four ranges of 65 to 68, and the occurrence frequency of the range to which the white component d belongs is counted up depending on which range the white component d belongs to. A similar operation is performed on pixels in one screen, and as a result, frequency m, frequency n, frequency x, and frequency y are obtained.
[0045]
The gain control signal generation unit 4 generates correction gain values p1 to t1 for each color component according to the generation frequency m, frequency n, frequency x, and frequency y for each divided range, which is the output signal of the white component distribution detection unit 2. To do. As shown in FIG. 4, when the distribution is concentrated in a region where the signal level of the white component is high, that is, when there is a lot of bright white in the screen, the intermediate color looks dark, so the correction gain The value p1, the correction gain value q1, and the correction gain value s1 are set so as to increase the signal level of the color component. In particular, when yellow looks particularly dark, an appropriate correction result can be obtained by setting the correction gain value p1 of the yellow component larger than the correction gain values for the other color components.
[0046]
On the other hand, for example, when the frequency m and the frequency n are small values, that is, on a screen with a small amount of bright white components and a large amount of components other than white in the screen, the white signal component can be reduced to use the white color filter. As a result, the relative brightness of the video portion other than white can be improved without significantly reducing the brightness of the entire screen. In this case, the gain control signal generation unit 4 can be realized by setting the correction gain value t1 to a negative value.
[0047]
Furthermore, by inputting the white component d to the gain control signal generation unit 4, the correction gain value can be changed even in accordance with the signal level of the white component. For example, when the distribution state of the white component is as shown in FIG. 4, the intermediate color looks dark and the hue appears to have changed. In this case, when the white component d of the pixel is small, the correction gain value of the intermediate color component is increased and the correction gain value t1 of the white component is set small. That is, the white component 46 in FIG. 3 is decreased and the correction gain value for the yellow component 45, that is, the intermediate color component is increased.
[0048]
In this way, an optimum gain correction value can be obtained for each pixel, the color purity of the intermediate color can be increased, and the brightness and hue change of the intermediate color on a bright screen can be improved.
[0049]
As described above, according to the present embodiment, a specific color component of the input video signal is separated and extracted, and as a result, White By detecting the distribution state of the color components in the screen, the brightness can be improved by selectively performing level correction on a specific color component that appears darker.
[0050]
(Embodiment 2)
FIG. 2 relates to the second embodiment of the present invention. projector It is a block diagram which shows the electric circuit structure. In the first embodiment described above. projector The same reference numerals are given to the same components, and detailed description thereof is omitted.
[0051]
The present embodiment differs from the configuration of the first embodiment in that a hue control signal generation unit 7 is provided instead of the gain control signal generation unit 4, and an adder 28, an adder 30 in the video signal correction unit 6, Instead of the adder 31, a subtracter 28b, a subtracter 30b, and a subtractor 31b are provided.
[0052]
Next, the operation of the video signal display device configured as described above will be described.
[0053]
First, as in the first embodiment, each color component in the video input signal is separated and extracted by the color component separation and extraction unit 1, and the distribution state of the frequency of occurrence of the white component d in the screen is detected by the white component distribution detection unit 2. .
[0054]
The hue control signal generation unit 7 (control signal generation means) is magenta separated by the color component separation / extraction unit 1 according to the frequency m, frequency n, frequency x, and frequency y obtained by the white component distribution extraction unit 2. Hue correction gain values p2, q2, and s2 are generated as correction control signals for changing the hue with respect to the color component a, cyan component b, and yellow component c, respectively. The white component correction gain value t1 is a signal similar to that in the first embodiment.
[0055]
The hue correction gain values p2 to s2 and the white component correction gain value t1 are multiplied by the multipliers 20 to 22 in the calculation control unit 5 with respect to each output signal of the color component separation and extraction unit 1, as in the first embodiment. Processing is performed. As a result, a hue correction value v2, a hue correction value w2, and a hue correction value z2 for correcting the hue are obtained. The hue correction values v2 to z2 are added and subtracted with Rin, Gin, and Bin by the adders 27, 29, and 32 and the subtractors 28, 30, and 31 in the video signal correction unit 6.
[0056]
In the present embodiment, for example, when correcting the hue of the yellow component, if the hue correction gain value v2 is a positive value, the adder 27 functions as an adder and the subtractor 28b functions as a subtractor. When the correction gain value v2 is a negative value, the adder 27 functions as a subtracter and the subtractor 28b functions as an adder. Similarly, the adders 29 and 32 and the subtractors 30b and 31b perform addition / subtraction processing according to the polarities of the hue correction gain values w2 and z2.
[0057]
As an example, the case where the distribution state of the white component occurrence frequency in the screen is as shown in FIG. 4 will be described. In this case, since there are many bright white components, the white light emphasis effect by using the white color wheel 71 becomes remarkable. As a result, the image portion other than white looks dark and the hue changes depending on human visual characteristics. It appears and is recognized as a color different from the original color. In that case, by correcting the hue of each color component in the pixels constituting the video portion other than white, the signal of the pixel is corrected so that the apparent hue change cannot be recognized.
[0058]
For example, when the color components constituting a certain pixel are only yellow and white components, the appearance is recognized as pale yellow when there is no white light enhancement effect, but when white light is enhanced, the visual characteristics are It looks dark due to lightness contrast, and as a result, it is perceived as close to green rather than yellow. In this case, the white component correction gain value t1 is lowered, and at the same time, the yellow component hue correction gain value p2 is set to a positive value. As a result, the adder 27 adds the red signal level to Rin, the subtractor 28b subtracts Gin, and corrects the hue to the red side to recognize the apparent color as green. Correct the phenomenon so that it looks yellow.
[0059]
Similarly, when hue correction is performed on the green side in some cases, the hue correction gain value p2 of the yellow component is set to a negative value so that addition is performed for Gin and subtraction processing is performed for Rin. As a result, the hue can be corrected to the green side.
[0060]
Furthermore, by inputting the white component d to the hue control signal generator 7, the hue correction gain value can be changed according to the signal level of the white component. For example, when the distribution state of the white component is as shown in FIG. 4 and the white component d of the pixel is small, the hue correction of the intermediate color component is performed, and at the same time, the correction gain value t1 of the white component is set small. . In other words, by reducing the white component in the pixel, it is possible to increase the composition ratio of the intermediate color component and to improve the hue correction effect by performing the hue correction described above, and to perform the optimum hue correction for each pixel. Can be bright Many white components It is possible to improve the apparent hue change of the intermediate color on the screen.
[0061]
As described above, according to this embodiment, White The apparent hue change can be corrected by selectively changing the hue with respect to a specific color component that looks different and changes its hue according to the distribution state of the color components in the screen.
[0062]
Although the white component distribution detection unit 2 has been described as detecting the white component distribution in the above embodiment, a specific color component distribution other than the white component may be detected.
[0063]
In the above embodiment, the white component distribution detection unit 2 has been described as detecting the distribution state of the occurrence frequency of the white component in one screen. However, one screen is divided into a plurality of spatial regions and each region is divided. The gain control signal generation unit 4 and / or the hue control signal generation unit 7 may generate a correction gain value corresponding to the distribution state for each region. Good.
[0064]
In the above embodiment, either the gain control signal generator 4 or the hue control signal generator 7 is provided. projector However, the gain control signal generator 4 and the hue control signal generator 7 may be used in combination.
[0065]
【The invention's effect】
As described above, according to the present invention, the input video signal White component and non-white Separate and extract specific color components Of white component By detecting the distribution state and obtaining a correction gain value for a specific color component such as the intermediate color that has been separated and extracted, the brightness of the intermediate color and the change in hue due to visual characteristics when the brightness is increased by the color filter for white are improved. projector It is possible to provide a special effect.
[Brief description of the drawings]
FIG. 1 relates to the first embodiment of the present invention. projector The block diagram which shows the electric circuit constitution of
FIG. 2 relates to a second embodiment of the present invention. projector The block diagram which shows the electric circuit constitution of
FIG. 3 is a diagram showing an example of signal levels of each color component of an input video signal for explaining operations of the first and second embodiments of the present invention.
FIG. 4 is a diagram for explaining the operation of the first and second embodiments of the present invention. White component Of distribution example of occurrence frequency with respect to signal level
Fig. 5 Conventional projector Of a projector using a reflective display element and a color wheel as an application example
FIG. 6A is a plan view showing the configuration of a three-division color wheel
FIG. 6B is a plan view showing the configuration of a four-division color wheel.
Fig. 7 Conventional projector The block diagram which shows the electric circuit constitution of
[Explanation of symbols]
1 color component separation and extraction unit
2 White component distribution extraction unit
4 Gain control signal generator (control signal generator)
5 Operation control unit
6 Video signal correction unit
7 Hue control signal generator (control signal generator)

Claims (5)

A color component separation and extraction unit that separates and extracts each color component constituting each pixel of the input video signal;
And white color component distribution detecting unit which detects the distribution in the screen of the white color component among the color components extracted,
A control signal generating means for generating a correction control signal for a particular color component in accordance with the output signal of the white color component distribution detecting unit,
An arithmetic control unit that performs an operation on each color component output from the color component separation detection unit based on a correction control signal output from the control signal generation unit;
A projector comprising: a video signal correction unit that corrects the input video signal based on an output signal from the arithmetic control unit. Said control signal generating means, a projector according to claim 1, wherein for generating a correction control signal for correcting the level of the white color component.   The projector according to claim 1, wherein the control signal generating unit generates a correction control signal for correcting a hue of the specific color component. Said control signal generating means, any one claim of claims 1 to 3, generates a correction control signal corresponding to the output signal from the addition to an output signal of the white color component distribution detecting unit the color component separation extraction unit Projector . The white color component distribution detecting unit detects the distribution of the white color component for each of the areas by dividing a single screen into a plurality of regions, said control signal generating means, the said white color component in each of the areas The projector according to any one of claims 1 to 4 , wherein a correction control signal corresponding to a distribution state is generated.

Images