JP2005266462A - Projector device and color correction method in projector device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector device wherein color correction can be realized in accordance with the luminance variance of reflected light of all projected image light. <P>SOLUTION: The projector device which displays a color image by successively projecting image light in two or more colors formed by an image forming element 4, to a screen 5 is provided with; a sensor 10 capable of detecting luminance of reflected light of image light in each color individually projected to the screen 5; a first memory 11 wherein luminance information of reflected light in each color detected by the sensor 10 is stored; a second memory 12 wherein reference luminance information of reflected light predetermined for each color is stored; a color correction data generation part 13 for generating color correction data by comparing luminance information with reference luminance information; and a color correction circuit 14 for correcting an image signal inputted to the image forming element 4 on the basis of color correction data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to color correction of a projector apparatus.

In the case of a projector that displays a color image by sequentially projecting red (R), green (G), and blue (B) image light onto a projection surface, the projection surface does not necessarily have a predetermined reflection characteristic. Depending on the reflection characteristics of the projection surface, the color reproducibility decreases. In addition, color reproducibility also decreases due to the influence of ambient light (ambient light). Therefore, conventionally, the brightness (intensity) of the reflected light of the image light projected on the projection surface is detected for each wavelength, and color correction is performed based on the detection result. More specifically, the reflected light is spectrally decomposed into three primary colors of R, G, and B using a diffraction grating and a prism, the brightness of each color light is detected by a color sensor, and the brightness of each color light is adjusted to be as equal as possible. By doing so, color reproducibility is improved. Here, a color sensor mounted on a general projector includes a red sensor for detecting the luminance of light in the 660 nm band, a green sensor for detecting the luminance of light in the 540 nm band, and the luminance of light in the 460 nm band. It is comprised from three monochromatic sensors, such as a blue sensor for detecting. The characteristics of each monochrome sensor are shown in FIG. The details of the color correction of the projector as described above are disclosed in Patent Document 1, for example.
JP 2003-323610 A

  Since the image light projected by a conventional projector contains only the three primary colors R, G, and B, color correction based on the detection result of an inexpensive color sensor composed of the three single color filters as described above is also used. Necessary and sufficient. However, among recent projectors, there are projectors that project color lights other than R, G, and B as independent image lights in order to improve color reproducibility. In such a projector, the color correction based on the detection result of the color sensor composed of the three single color filters as described above is insufficient, and color light other than R, G, and B is projected independently. However, the effect may not be sufficiently obtained. For example, even when yellow (Ye) image light is projected in addition to R, G, and B image light, none of the red, green, and blue sensors reacts to yellow (Ye). Therefore, even if color correction is performed based on the brightness of reflected light detected by the red sensor, green sensor, and blue sensor, an accurate correction result cannot be obtained, and sufficient color reproducibility cannot be achieved.

  An object of the present invention is to provide a projector device and a color correction method capable of realizing color correction corresponding to luminance changes of all color lights included in projected image light.

  According to the present invention, two or more colors of image light projected by the projector device to display a color image are individually projected on a projection surface to detect the brightness of the reflected light, and the detected brightness of the reflected light of each color is detected. The color correction data is generated by comparing with the reference brightness of each reflected light held in advance, and the image signal is corrected based on the generated color correction data. Therefore, not only when the image light of the three primary colors is projected, but also when the image light of a color other than the three primary colors is projected, the luminance change of the reflected light of all the image lights is detected, and appropriate color correction is performed. Executed. As a specific method of color correction, the actual brightness balance is the same as the preset reference brightness balance by comparing the detected actual reflected light brightness with the preset reference brightness. Thus, a method for correcting luminance information in an image signal is considered as an example.

  The detection means for detecting the brightness of the reflected light is sufficient if it can detect the brightness of the projected image light of two or more colors, but it is desirable that the brightness of the entire visible light can be detected. . This is because if the detection means can detect the luminance of the entire visible light range, it can detect the luminance of various lights that affect the color reproducibility of the display image and reflect the detection results in the color correction. It is. For example, in an environment where ambient light such as room light or sunlight is incident on the projection surface, the brightness of ambient light reflected by the projection surface is detected, and the detection result is reflected in color correction. More accurate color correction can be realized. From the above viewpoint, there are sensors using photodiodes, phototransistors, CCDs (Charge Coupled Devices), CMOSs (Complementary Metal Oxide Semiconductors), PSDs (Position Sencing Devices), etc. that do not have wavelength selection means such as color filters. Suitable as detection means.

  According to the present invention, it is possible to perform color correction corresponding to the luminance change of the reflected light of all image light projected from the projector device.

  Hereinafter, an example of an embodiment of the projector apparatus of the present invention will be described in detail. FIG. 1 is a block diagram schematically showing the configuration of the projector apparatus of this example. The projector device of this example is separated by the color wheel 2 as a light source device 1, a color wheel 2 as time-division color separation means for color-separating light (white light) emitted from the light source device 1 in a time division manner. A TIR prism (total reflection prism) 3 that reflects each color light toward an image forming element 4 to be described later and transmits the image light formed by the image forming element 4 as it is, and each color light reflected by the TIR prism 3 An image forming element 4 that spatially modulates light based on an image signal to form image light, a projection lens 6 that magnifies and projects image light transmitted through the TIR prism 3 toward a screen 5 as a projection surface, and a screen The sensor 10 for detecting the brightness of the reflected light reflected by 5 and information on the brightness of the reflected light detected by the sensor 10 are held. Information stored in the first memory 11, the second memory 12 in which information relating to the reference luminance to be compared with the luminance information held in the first memory 11 is held, and information held in the first memory 11 and the second memory 12 A color correction data generation unit 13 that generates color correction data based on the color correction data, and a color correction circuit 14 that corrects an image signal input to the image forming element 4 based on the color correction data.

  The light source device 1 includes a light source composed of a high-pressure discharge lamp such as a metal halide lamp, a xenon lamp, or a mercury lamp, and a reflector provided around the light source. The reflector has, for example, a spheroidal reflection surface, and condenses light emitted in all directions from a light source disposed in the vicinity of the first focal point in the vicinity of the second focal point. But the shape of the reflective surface of a reflector is not specifically limited, What is necessary is just a shape which can inject the light radiated | emitted from the light source into the color wheel 2 efficiently.

  The color wheel 2 has a substantially fan-shaped red filter that transmits only red light, a substantially fan-shaped green filter that transmits only green light, a substantially fan-shaped blue filter that transmits only blue light, and only yellow light. A substantially fan-shaped yellow filter is arranged at intervals of 90 degrees. The color wheel 2 is disposed in the vicinity of the condensing point by the reflector of the light source device 1 (in the vicinity of the second focal point when the reflector has a spheroidal reflection surface) and is circumferentially driven by a drive mechanism (not shown). To be rotated. Therefore, the light (white light) emitted from the light source device 1 enters each color filter of the color wheel 2 and is separated into red light, green light, blue light, and yellow light in a time-sharing manner, and is transmitted to the TIR prism 3 with a predetermined amount. Incident at an incident angle.

  The TIR prism 3 is arranged so that the incident angle of the light transmitted through the color wheel 2 with respect to the total reflection surface exceeds the critical angle and the incident angle with respect to the total reflection surface of the light reflected by the image forming element 4 does not exceed the critical angle. Has been. Accordingly, each color light color-separated in a time division manner by the color wheel 2 is reflected by the total reflection surface of the TIR prism 3 and irradiated to the image forming element 4, and light (image light) reflected by the image forming element 4 is It passes through the total reflection surface as it is.

  The image forming element 4 is a reflective liquid crystal panel or DLP (registered trademark), and cells or micromirrors corresponding to each pixel of a projected image are individually driven according to an input image signal and irradiated. Each color light is spatially modulated to form image light of each color of R, G, B, Ye. The R, G, B, and Ye image lights formed by the image forming element 4 pass through the total reflection surface of the TRI prism 3 and enter the projection lens 6 as described above, and are sequentially projected toward the screen 5. The As a result, it is recognized as a full-color image by human eyes due to the afterimage phenomenon.

  The sensor 10 is a photoelectric conversion element that outputs a voltage corresponding to the luminance of incident light, and a photodiode is used in this example. The value of the voltage output from the sensor 10 is stored in the first memory 11 as luminance information, and a luminance table is created. Further, the second memory 12 stores a value of voltage (reference luminance information) output from the sensor 10 when the image light of each color of R, G, B, Ye is individually projected on a white body (white screen). ) Is previously stored. However, the first memory 11 and the second memory 12 do not need to be two physically independent memories, but one area in the same memory is used as the first memory 11 and the other area is used as the second memory 12. You can also

  The color correction data generation unit 13 normalizes the luminance table held in the first memory 11 based on the reference luminance table held in the second memory 12 to create a normalization table, and the generated normalization The table is output to the color correction circuit 14 as color correction data. Specifically, the actual R, G, B, Ye reflected light brightness shown in the brightness table and the ideal R, G, B, Ye reflected light brightness shown in the reference brightness table are as follows. And the result is used as a normalization table. For example, when image light is projected onto a screen (for example, a gray screen) having a uniform reflection efficiency for the entire visible light region, R, G, B, and Ye are absorbed at substantially the same rate. Therefore, as shown in FIG. 2, the current brightness of R, G, B, Ye shown in the brightness table is substantially uniform with respect to the brightness of R, G, B, Ye shown in the reference brightness table. The result is lowered. Therefore, the ratio of the luminance of R, G, B, Ye shown in the luminance table to the luminance of R, G, B, Ye shown in the reference luminance table is constant, and the normalization table as shown in FIG. can get.

  On the other hand, when image light is projected on a screen having poor reflection efficiency only for light in a certain wavelength region, for example, a screen having poor reflection efficiency for light in the vicinity of a wavelength of 580 nm (so-called yellow), among R, G, B, and Ye, A relatively large amount of Ye is absorbed. Therefore, as shown in FIG. 3, the current R, G, and B luminances shown in the luminance table are the same as the R, G, and B luminances shown in the reference luminance table, but the current luminance shown in the luminance table. The brightness of Ye is lower than the brightness of Ye shown in the reference brightness table. Therefore, when the ratio of the luminance of R, G, B, Ye shown in the luminance table and the luminance of R, G, B, Ye shown in the reference luminance table is calculated, a normalization table as shown in FIG. can get. Here, when Ye is absorbed in a relatively large amount and the luminance of Ye is reduced, it is perceived by human eyes that B, which is a complementary color of Ye, has increased rather than Ye decreasing. However, since the brightness of R, G, and B does not actually change, even if a single color sensor that individually detects the brightness of R, G, and B is provided, the brightness change is not detected, and color correction is not performed. . On the other hand, the sensor 10 does not have a wavelength selection unit such as a color filter, and can detect the luminance of light in the entire visible light region. Therefore, not only the reflected light of R, G, and B but also the brightness of the reflected light other than these is detected, the decrease in the brightness is detected, and an appropriate normalization table is created.

  The color correction circuit 14 processes the image signal according to the color correction data input from the color correction data generation unit 13 and outputs the processed image signal to the image forming element 4. Specifically, when a normalization table as shown in FIG. 2 is created, the current R, G, B, Ye luminances are ideal R, G, B, It has the same balance as the brightness of Ye, and there is no need for color correction. Therefore, the color correction circuit 14 outputs the input image signal as it is to the image forming element 4. On the other hand, when the normalization table as shown in FIG. 3 is created, any one or more of R, G, B, Ye is lower than the ideal luminance, which is good. Color correction is necessary to ensure a good color reproducibility. Therefore, the color correction circuit 14 uses the luminance information in the image signal so as to lower the luminance of a color other than the color whose luminance is reduced in the normalization table or the luminance of the complementary color of the color whose luminance is reduced. to correct. For example, when the normalization table as shown in FIG. 3 is created, the brightness of Ye is lowered, so that all the brightness of R, G, and B are lowered according to the brightness of Ye, or Ye The luminance of B which is a complementary color is lowered according to the luminance of Ye.

  The color correction process in the projector apparatus of the present example having the above configuration will be described in order with reference to FIG.

  First, the color wheel 2 shown in FIG. 1 rotates, the red filter is inserted into the optical path, and R image light is projected onto the screen 5. Next, the brightness of the reflected light (R reflected light) of the R image light projected on the screen 5 is detected by the sensor 10 and stored in the first memory 11 (step 1). Next, a green filter is inserted into the optical path, and the brightness of the reflected light (G reflected light) of the G image light projected on the screen 5 is detected by the sensor 10 and stored in the first memory 11 (step 2). . Next, a blue filter is inserted into the optical path, and the brightness of the reflected light (B reflected light) of the B image light is detected by the sensor 10 and stored in the first memory 11 (step 3). Finally, a yellow filter is inserted into the optical path, and the brightness of the reflected image light (Ye reflected light) of Ye is detected by the sensor 10 and stored in the first memory 11 (step 4). But the execution order of the processes 1-4 can be changed arbitrarily. In short, it is only necessary to sequentially project two or more colors of image light projected to display a full-color image and detect the brightness of each reflected light by the sensor 10, and the projection order of the image light is an essential condition. Absent. While steps 1 to 4 are being performed, an image signal that has passed through the color correction circuit 14 is input to the image forming element 4 by switching the switch 20 shown in FIG. Further, the image forming element 4 is driven at the maximum output.

  Next, a luminance table is created based on the information (luminance information) indicating the luminance of the current R, G, B, Ye reflected light obtained in the above steps 1 to 4 and held in the first memory 11 ( Step 5).

  Next, the color correction data generation unit 13 creates a normalization table based on the luminance table created in the above step 5 and the reference luminance table previously stored in the second memory 12 (step 6). The color correction data is output to the color correction circuit 14 (step 7). Since the normalization table creation method has already been described, the description thereof is omitted here.

  Subsequently, the necessity for color correction is determined by the color correction circuit 14 (step 8). Specifically, if the luminances of the reflected light of R, G, B, Ye shown in the normalization table input as color correction data are the same, it is determined that no color correction is necessary, and the input The processed image signal is output as it is to the image forming element 4 (step 9). On the other hand, if at least one of the luminances of the reflected light of R, G, B, Ye shown in the normalization table input as color correction data is relatively low, color correction is necessary. The luminance information in the image signal is corrected so that the luminance of a color other than the low-luminance color is reduced or the luminance of the complementary color of the color is reduced, and the corrected image signal is output to the image forming element 4 (Step 10).

  In this example, the embodiment of the projector apparatus of the present invention has been described by taking as an example the case where Ye image light is projected in addition to R, G, and B image light. However, the color of the projected image light in addition to the R, G, and B image light is not limited to Ye, and can be arbitrarily selected as necessary. For example, light blue or purple image light can be projected. In order to change the color of the projected image light, the color wheel 2 shown in FIG. 1 may be replaced with a color wheel capable of separating desired color light. Since the projector apparatus of the present invention includes a sensor that does not have wavelength selectivity and can detect the luminance of light in the entire visible light region, any image light of any color is projected. It is obvious from the description so far that it is possible to detect a decrease in luminance of light and realize appropriate color correction.

  In this example, an example in which a photodiode is used as a sensor for detecting the brightness of reflected light has been described. However, the sensor may be any element that can output a voltage corresponding to the luminance of incident light, and may be, for example, a phototransistor, CCD, CMOS, PSD, or the like. When a CCD, CMOS, PSD, or the like is provided for the purpose of realizing autofocus and distortion correction, they can also be used as luminance detection means.

  When the reference luminance table or the luminance table is created, more accurate color correction can be realized by performing an operation of subtracting the luminance detected by the sensor in a state where image light is not projected. This is because the luminance detected by the sensor when no image light is projected is the luminance of the reflected light of the ambient light, and if this luminance is subtracted, it is based only on the change caused by the projection of the image light. This is because correction can be performed. Further, assuming that the ambient light is light having the luminance detected by the sensor and the hue and saturation on the color matrix (hue ring) obtained from the luminance table, it may be reflected in the generation of correction data. it can. For example, when the image light of R, G, B, Ye is projected onto the projection surface, if the brightness of the reflected light of Ye is low (or the brightness of the reflected light of B is high), the image light is not projected. Sometimes the projection surface appears blue. Therefore, color reproducibility can be further improved by applying color correction that cancels out the blueness of the projection surface.

  In addition, when white light is independently projected for the purpose of supplementing the amount of light, if the projection surface has some color, the reflected light of the white light also has the color of the projection surface. Therefore, it may be corrected so that the human eye recognizes white by projecting colored light according to the brightness of the reflected light of white light. Here, the reflected light of the white light can be considered as light having all the luminances of the reflected lights of the other colored lights.

It is a block diagram which shows typically the structural example of the projector apparatus of this invention. It is explanatory drawing which shows typically the relationship between the reflection luminance at the time of projecting image light on a screen with bad reflection efficiency, a reference | standard reflection luminance, and the normalized reflection luminance. It is explanatory drawing which shows typically the relationship between the reflective brightness at the time of projecting image light on the screen where only the reflective efficiency with respect to yellow is bad, reference | standard reflected brightness, and normalized reflected brightness. It is process drawing which shows an example of the color correction method of this invention. It is a figure which shows the characteristic of each single color sensor which comprises the conventional color sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source device 2 Color wheel 3 TIR prism 4 Image formation element 5 Screen 6 Projection lens 10 Sensor 11 1st memory 12 2nd memory 13 Color correction data generation part 14 Color correction circuit 20 Switch

Claims (9)

A projector device that sequentially projects image light of two or more colors formed by an image forming element onto a projection surface to display a color image,
Detection means capable of detecting the brightness of the reflected light of the image light of each color individually projected on the projection surface;
First storage means for storing information indicating the luminance of reflected light of each color detected by the detection means;
Second storage means in which information indicating the reference luminance of the reflected light determined for each color is stored in advance;
Color correction data generating means for generating color correction data by comparing the information stored in the first storage means with the information stored in the second storage means;
A projector apparatus comprising color correction means for correcting an image signal input to the image forming element based on the color correction data.   The information stored in the first storage means is the periphery reflected by the projection surface in a state in which no image light is projected on the projection surface from the luminance of the reflected light of each color detected by the detection means. The projector device according to claim 1, wherein the projector device indicates a luminance obtained by subtracting the luminance of light.   The information stored in the second storage means indicates the brightness of the reflected light of each color detected by the detection means when the image light of each color is individually projected onto a white projection surface. Item 3. The projector device according to Item 2.   The projector apparatus according to claim 1, wherein, in addition to red, green, and blue image light, image light having a color other than red, green, and blue is projected.   The projector device according to claim 4, wherein the image light of a color other than red, green, and blue is yellow image light. A color correction method in a projector device for displaying a color image by sequentially projecting image light of two or more colors formed by an image forming element onto a projection surface,
Sequentially projecting the image light of the two or more colors on the projection surface;
A step of detecting the brightness of the reflected light of the image light projected onto the projection surface each time image light of a different color is projected onto the projection surface;
Comparing the detected brightness of the reflected light of each color with a reference brightness predetermined for each color to generate color correction data;
A color correction method in a projector apparatus, comprising a step of correcting an image signal input to the image forming element based on the generated color correction data. Detecting brightness of reflected light of ambient light reflected by the projection surface in a state where no image light is projected on the projection surface;
Subtracting the brightness of the reflected light of the ambient light from the brightness of the reflected light of the image light projected on the projection surface;
The color correction method in the projector device according to claim 6, wherein the color correction data is generated by comparing the luminance obtained by the subtraction with the reference luminance.   The image light of two or more colors projected on the projection surface includes image light of colors other than red, green, and blue in addition to image light of red, green, and blue. Item 8. A color correction method in the projector device according to Item 7.   The color correction method in the projector device according to claim 8, wherein the image light of a color other than red, green, and blue is yellow image light.

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