JP2006047464A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an image quality in total, preventing color variations of three prime colors of R, G and B and deterioration of luminance and contrast of a projected image due to external light, by using an LED light source and a liquid crystal panel. <P>SOLUTION: The apparatus comprises; a light source unit 19 which is the LED light source; an LCD panel 18; a parameter detecting means for detecting a change amount of a predetermined parameter relating to a color or luminance of the projected image on a screen by illumination light modulated in the LCD panel 18; and a CPU 16 for controlling and correcting at least color balance of the illumination light emitted by the light source unit 19 between the color balance and a γ curve which is used when the light is modulated in the LCD panel 18, according to the change amount of the predetermined parameter which is detected by the parameter detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image projection apparatus.

Conventionally, a liquid crystal projector using a liquid crystal panel has problems such as variations in hues of RGB three primary colors and a decrease in luminance or contrast of a projected image due to external light, and various display image improvement techniques have been proposed.
For example, Patent Document 1 describes a technique for correcting a change in color temperature due to a temperature rise of a lamp as a light source so that the color temperature of a liquid crystal projector can be maintained within a certain range.
Patent Document 2 describes a technique for correcting the hue of a projected image in accordance with the brightness and hue of ambient light of a liquid crystal projector.
In Patent Document 3, in a liquid crystal projector, the peripheral light amount is detected to control the power of the light source lamp, thereby reducing power consumption, adjusting the brightness by adjusting the light source lamp, and extending the life of the light source lamp. Techniques to make it possible are described.
Patent Document 4 describes a technique for appropriately correcting the image quality of a projected image of a liquid crystal projector in accordance with the projection environment such as the brightness and hue of the periphery and the image projection surface.
In Patent Document 5, in a projection-type liquid crystal projector, the luminance level of a video signal for the entire screen is detected for each screen, and light from the light source is spatially distributed according to the luminance level of the video signal for the entire screen. A technique for blocking and adjusting the level of a video signal sent to a liquid crystal panel so as to obtain a large contrast is described.
Patent Document 6 describes a technique for detecting the amount of light around the liquid crystal projector device, blocking light with an optical shutter in accordance with the detected amount of light, and suppressing a decrease in contrast due to black floating. .
Patent Document 7 describes a technique for measuring an applied voltage-transmittance characteristic of a liquid crystal panel and performing gamma correction according to correction data based on the result.
Japanese Patent Laid-Open No. 2003-228867 describes a variation in hue of a liquid crystal projector, in which when adjusting the characteristics of a gamma curve to improve the color reproducibility of a projected image, the level of a plurality of locations on the gamma curve can be adjusted. In addition, there is described a technique for making it possible to improve a hue in a halftone, and for performing adjustment automatically to shorten the adjustment time.
In Patent Document 9, a target color gamut is calculated based on a target profile selected by a user, color conversion is performed based on environment information from a projector profile and a color light sensor, and a gamma is calculated using a predetermined calculation formula. A technique for performing the correction is described.
In Patent Document 10, color information of a projected image is captured by a color sensor, and color conversion processing for matching the appearance of colors is performed based on the color space of the input image and the color space on the projection surface, and the color of the input image is changed. A technique for correcting and correcting a corrected color image as necessary is described.
Patent Document 11 measures the brightness (luminance) of the screen and its surroundings, and sets the gradation of the projector output according to the measurement result. Specifically, the brightness setting and the gamma setting are changed. By doing so, a technique for always providing appropriate gradation expression is described.
Japanese Patent Laid-Open No. 08-149494 JP 2000-66166 A JP 2000-131668 A JP 2002-311503 A JP 2002-365607 A JP 2003-107422 A JP-A-6-217239 Japanese Patent Laid-Open No. 2001-16602 JP 2002-247401 A JP 2003-323610 A JP 2003-324670 A

However, the above-described conventional techniques individually approach the above-described problems (variation of hues of the three primary colors of RGB and reduction in luminance or contrast due to external light of the projected image), thereby realizing total image quality improvement. It is not a thing.
In recent years, a liquid crystal projector including an LED light source that generates white light using RGB (Primary Emitting Diode) LEDs (Light Emitting Diodes) has been studied. However, the above prior art is based on a liquid crystal projector that uses a lamp that emits white light as a light source, and has a problem that it is not suitable for a liquid crystal projector that uses an LED light source.

  The present invention has been made in consideration of such circumstances, and its purpose is to use LED light sources and liquid crystal panels to reduce variations in the hues of RGB three primary colors and to reduce the brightness or contrast of projected images due to external light. An object of the present invention is to provide an image projection apparatus capable of realizing a total image quality improvement.

  In order to solve the above problems, an image projection apparatus according to the present invention is an image projection apparatus that projects an image corresponding to input image information onto a screen, and has a color balance that is a luminance distribution for each wavelength band. Light source means for emitting controllable illumination light, spatial modulation means for modulating the illumination light emitted by the light source means based on the image information, and projection means for projecting the illumination light modulated by the spatial modulation means on a screen And a parameter detection unit that detects a change amount of a predetermined parameter related to a color or luminance of an image projected on the screen by the projection unit, and the light source unit is configured to respond to the change amount of the predetermined parameter detected by the parameter detection unit. Control means for correcting and controlling at least the color balance of the illumination light among the color balance of the emitted illumination light and the γ curve used for modulation by the spatial modulation means It is characterized by having a.

  The image projection apparatus according to the present invention further includes image information monitoring means for obtaining an average value of luminance values of the input image information, and the change amount of the predetermined parameter is the luminance obtained by the image information monitoring means. It is a change amount of the average value of the value, and the control means performs control according to whether or not the luminance value average value has fallen below a predetermined threshold value.

  In the image projection apparatus according to the present invention, the control unit reduces the amount of illumination light emitted by the light source unit when the average luminance value obtained by the image information monitoring unit falls below a predetermined threshold value. The γ curve used for modulation by the spatial modulation means is corrected so as to cancel the change in the color balance of the illumination light emitted by the light source means caused by reducing the amount of emitted illumination light. And

  The image projection apparatus according to the present invention further includes image information monitoring means for obtaining a color distribution of the input image information, and the change amount of the predetermined parameter is a change in the color distribution obtained by the image information monitoring means. The control means performs control according to whether or not the amount of change in the color distribution exceeds a predetermined threshold value.

  In the image projecting device according to the present invention, the control means determines the color balance of the illumination light emitted by the light source means when the change amount of the color distribution exceeds a predetermined threshold value. When modulating by the spatial modulation means so as to cancel the change in the color balance of the illumination light emitted by the light source means, which is generated by correcting the color distribution and correcting the color balance of the illumination light to be emitted. The gamma curve used for the correction is corrected.

  The image projection apparatus according to the present invention further includes an external light quantity sensor that detects an external light quantity in an environment where the image projection apparatus is installed, and the change amount of the predetermined parameter is detected by the external light quantity sensor. The amount of change in the amount of external light is controlled, and the control means performs control according to whether the amount of change in the amount of external light exceeds a predetermined threshold.

  In the image projection apparatus according to the present invention, the control unit increases the amount of illumination light emitted by the light source unit when the amount of external light obtained by the external light amount sensor exceeds a predetermined threshold. Correcting the γ curve used for modulation by the spatial modulation means so as to cancel the change in the color balance of the illumination light emitted by the light source means caused by increasing the amount of illumination light emitted. Features.

  The image projection apparatus according to the present invention further includes a temperature sensor that detects a temperature of the spatial modulation unit or the vicinity thereof, and the change amount of the predetermined parameter is a change amount of the temperature detected by the temperature sensor, The control means performs control according to whether or not the amount of change in temperature exceeds a predetermined threshold value.

  In the image projection apparatus according to the present invention, the control means generates the spatial modulation means that is generated in accordance with the temperature change when the temperature of the spatial modulation means obtained by the temperature sensor or a nearby temperature exceeds a predetermined threshold. Corrects the γ curve used in the modulation by the spatial modulation means so as to cancel the change in the color balance of the illumination light modulated by the illumination light, and corrects the illumination light of the spatial modulation means generated by correcting the γ curve. The light amount of the illumination light emitted from the light source means is corrected so as to cancel the change in the light amount.

  The image projection apparatus according to the present invention further includes a first color sensor that detects a color balance of illumination light emitted from the light source means, and the first color sensor detects the amount of change in the predetermined parameter. The color balance change amount, wherein the control means performs control according to whether the color balance change amount exceeds a predetermined threshold value.

  In the image projection apparatus according to the present invention, the control means is configured such that the color balance of the illumination light emitted by the light source means when the change amount of the color balance detected by the first color sensor exceeds a predetermined threshold value. So as to cancel the change in the light intensity of the illumination light of the spatial modulation means generated by correcting the γ curve. The light quantity of the illumination light emitted from the light source means is corrected.

  In the image projection apparatus according to the present invention, a first color sensor for detecting the color balance of the illumination light emitted from the light source means, and a second color sensor for detecting the color balance of the illumination light modulated by the spatial modulation means. Calibration means for re-determining a γ curve used for modulation by the spatial modulation means based on the color sensor and the color balance detected by the first color sensor and the color balance detected by the second color sensor It further has these.

  In the image projection apparatus according to the present invention, the calibration means recalculates the γ curve when the light source means is replaced.

  The image projection apparatus according to the present invention further includes a light source identification information reading unit that detects identification information of the light source unit, and the calibration unit uses the detection result of the light source identification information reading unit, It is characterized by detecting that the light source means has been replaced.

  In the image projection apparatus according to the present invention, the calibration means recalculates the γ curve when the spatial modulation means is replaced.

  The image projection apparatus according to the present invention further includes panel identification information reading means for detecting identification information of the spatial modulation means, and the calibration means uses a detection result of the panel identification information reading means, It is detected that the spatial modulation means has been replaced.

  According to the present invention, using an LED light source and a liquid crystal panel, it is possible to realize a total image quality improvement with respect to variations in hues of the three primary colors of RGB and a decrease in brightness or contrast of a projected image due to external light.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a liquid crystal projector system according to an embodiment of the present invention. In FIG. 1, the liquid crystal projector system includes an image projector 1 and a screen 2.

  In the image projection apparatus 1 of FIG. 1, an image signal such as an analog RGB signal from a personal computer or a video signal such as a television (NTSC) is input to the signal input unit 11. The signal input unit 11 performs predetermined processing such as synchronization separation and Y / C separation on the input video signal according to the form of the input signal, and the signal of the processing result is converted to the A / D converter 12 or the video. Output to the decoder 13. The A / D converter 12 or the video decoder 13 converts the input signal into digital data and outputs the digital data to the digital signal processing & color conversion processing unit 14.

  The digital signal processing & color conversion processing unit 14 has a pixel size (for example, XGA: 1024 × 768 dots) corresponding to the number of pixels of an LCD (Liquid Crystal Display) panel (liquid crystal panel) for the input digital video data. Predetermined processing such as scaling for performing resolution conversion, trapezoidal (keystone) correction, color space conversion, and the like is performed, and a signal of the processing result is output to an adaptive gamma correction unit (adaptive γ correction unit) 15.

  The CPU (central processing unit) 16 has a function of controlling each unit of the image projector 1. The CPU 16 outputs a control signal for γ correction to the adaptive gamma correction unit 15. The adaptive γ correction unit 15 performs γ correction processing on the input signal from the digital signal processing & color conversion processing unit 14 based on the control signal from the CPU 16, and outputs the processing result signal to the LCD signal processing unit & panel Output to the drive processing unit 17.

  In the LCD signal processing unit & panel drive processing unit 17, the LCD signal processing unit performs predetermined processing such as liquid crystal surface unevenness correction on the input signal from the adaptive γ correction unit 15. The signal resulting from this processing is converted into an analog signal and AC inverted by a liquid crystal driver, and is output to the LCD panel 18 as an AC inverted video signal. The panel drive processing unit generates a drive clock, a drive timing signal, and the like for the LCD panel 18 and outputs them to the LCD panel 18. The LCD panel 18 displays an image using the timing signal and the AC inverted video signal from the LCD signal processing unit & panel drive processing unit 17.

  The illumination light from the light source unit 19 is incident on the LCD panel 18 via the illumination lens 20. The image displayed on the LCD panel 18 is projected onto the screen 2 through the projection lens 21 by illumination light from the light source unit 19.

The current control unit 22 controls the current supplied to the light source unit 19 based on a control signal from the CPU 16.
The light source unit 19 is provided with an RGB color sensor 23. The R, G, and B output signals from the RGB color sensor 23 are digitized by the R, G, and B A / D converters 24 and input to the CPU 16 as color sensor 1 data.

The LCD panel 18 is provided with a temperature sensor 25. An output signal from the temperature sensor 25 is digitized by the A / D converter 26 and input to the CPU 16 as temperature sensor data.
The projection lens 21 is provided with an RGB color sensor 27. R, G, and B output signals from the RGB color sensor 27 are digitized by the R, G, and B A / D converters 28 and input to the CPU 16 as color sensor 2 data.

  The projection surface ambient light amount sensor 29 is a light amount sensor for detecting the light amount around the projection surface of the screen 2. An output signal from the projection surface ambient light amount sensor 29 is digitized by the A / D converter 30 and input to the CPU 16 as ambient light amount sensor data.

2 and 3 are views showing the structure of the light source unit 19 shown in FIG. 1, FIG. 2 is a plan view, and FIG. 3 is a longitudinal sectional view taken along the center line A of FIG. FIG. 4 is a block diagram showing an electrical configuration of the light source unit 19 shown in FIG.
As shown in FIGS. 2 and 3, the light source unit 19 is a light guide that is a rectangular optical means constituted by a T-shaped optical surface attached to a rod holder 51 that is a rotatable holder. The rod member 52 is rotated by a rotary motor 53 as a driving means, and a plurality of LEDs 55 (L1 to Ln in FIG. 4) as light emitters of RGB three primary colors arranged on the inner periphery of an LED substrate 54 formed in a drum shape, The light source is characterized in that the light guide rod member 52 is sequentially switched in accordance with the rotation of the light guide rod member 52 and is lit in pulses.

  Further, a rotation sensor 56 for detecting the rotation position of the rod holder 51 is disposed near the side surface of the rod holder 51. The rotation sensor 56 is mounted on the LED board 54 in accordance with a rotation position detection signal from the rotation sensor 56. By selectively supplying drive control signals to the respective LED drive circuits D1 to Dn (see FIG. 4) on the control circuit board 57 for driving the respective LEDs 55 (light emission timing control circuit 71, drive LED selection circuit 72). ), The LED 55 that is the incident end surface P1 of the light guide rod member 52, that is, the incident surface position of the parallel rod 58, is controlled to be turned on sequentially. The driving current of the LED 55 by the LED driving circuits D1 to Dn at this time is based on the adaptive light source current control signal from the CPU 16 so that the light emission amount of the LED 55 is optimized by the LED driving current control circuit 73 of the current control unit 22. Be controlled. The LED drive current control circuit 73 receives data held in the light source information memory 74 and a signal obtained by analogizing an adaptive light source current control signal by a D / A converter (DAC) 75. These input signals The reference voltage generation circuit 81 generates a reference voltage for controlling the LED driving current.

Light that has entered the parallel rod 58 from the incident end face P <b> 1 is guided into the tapered rod 64 by the reflecting prism 63. Then, a Kohler illumination optical system that forms an optical pupil on the LCD panel 18 by the illumination lens 20 is configured using the emission end face P2 of the light guide rod member 52 as a virtual light source.
The rotary motor 53 is driven by a motor drive circuit 76. The light source unit 19 is formed on the base 61 and includes a heat sink 62 for heat dissipation.

  In this way, a plurality of LEDs 55 are sequentially switched to emit light, and the relative positional relationship with the parallel rod 58 that takes in the radiated light is shifted while being selected in accordance with the light emission switching of the LEDs 55, thereby effectively increasing the brightness of the LEDs. Thus, light with a high light quantity and a high degree of parallelism can be obtained from the light guide rod member 52.

  In this configuration, the relative position of the LED 55 and the parallel rod 58 is changed by rotating the parallel rod 58 and the light guide rod member 52, but it can also be realized by moving the light emitting device side. However, from the viewpoint of supplying power to the light emitting device, it is preferable to move the parallel rod 58 and the light guide rod member 52 from the viewpoint of reliability. In this case, for example, the light intensity distribution in the emission end face P2 of the light guide rod member 52 is less uneven if the length of the light guide rod member 52 is long. Since it can be regarded as a rectangular upper surface light source, critical illumination in which the surface of the LCD panel 18 that is an object to be irradiated and the emission end surface P2 of the light guide rod member 52 are conjugated may be performed. Since the peripheral portion of the emission end face P2 is projected onto the object to be illuminated, illumination unevenness occurs. Since it actually rotates, the illumination area has a circular shape, and depending on the rotational speed, the peripheral part is not known for the purpose of viewing, but at a certain moment, the peripheral part of the light guide rod exit end face P2 is unevenly illuminated, and from time to time, The illumination unevenness changes within the region, and cannot be applied to a display device that performs gradation expression in a time division manner.

  On the other hand, in the case of Koehler illumination that converts the angular intensity distribution of the light beam emitted from the light guide rod member 52 into the position intensity distribution in the illumination area as in this configuration, even if the light guide rod member 52 changes, Since the angular intensity distribution of the light beam emitted from the light guide rod member 52 does not change, an illumination device with small illumination unevenness in the illumination area can be realized.

  With the above-described configuration, the light source unit 19 is an embodiment of light source means for emitting illumination light whose color balance, which is a luminance distribution for each wavelength band (R, G, B, etc.) can be controlled.

  Next, operations related to adaptive control by the digital signal processing & color conversion processing unit 14 and the CPU 16 shown in FIG. 1 will be described in detail.

[First Embodiment]
FIG. 5 is a block diagram showing a configuration of an APL (Average Brightness Level) calculation unit 100 provided in the digital signal processing & color conversion processing unit 14. In FIG. 5, the luminance calculation & addition / average circuit unit 101 uses the input RGB data of a predetermined number of bits to calculate the luminance obtained from the human visibility according to the equation (1).
Y = 0.3R + 0.59G + 0.11B (1)

The calculation period generation circuit 102 calculates a calculation period based on the horizontal synchronization signal, the vertical synchronization signal, and the dot clock that are separated from the input video signal, and outputs the calculation period to the luminance calculation & addition / average circuit unit 101.
The line thinning amount calculation circuit 103 calculates the line thinning amount based on the horizontal synchronization signal, the vertical synchronization signal and the dot clock that are separated and generated from the input video signal, and the thinning amount designation data from the CPU 16.
The dot thinning amount calculation circuit 104 calculates the dot thinning amount based on the horizontal synchronization signal, the vertical synchronization signal, the dot clock, and the thinning amount designation data from the CPU 16 that are separated and generated from the input video signal.
The selector / synthesis circuit 105 obtains a data thinning amount based on the line thinning amount calculated by the line thinning amount calculation circuit 103 and the dot thinning amount calculated by the dot thinning amount calculation circuit 104, and performs a luminance calculation & addition / average circuit. Output to the unit 101.

  The luminance calculation / addition / average circuit unit 101 is based on the calculation period from the calculation period generation circuit 102, the data thinning-out amount from the selector / synthesis circuit 105, and the luminance calculated by the above equation (1) within one screen. The average value (APL) of the brightness levels is calculated, and the calculated brightness data (APL data) is output to the CPU 16.

  The CPU 16 compares the APL data with preset threshold value data. Based on the comparison result, the light emission amount of the light source unit 19 is controlled. Specifically, when the average luminance level is less than or equal to the dark threshold value, the light emission amount of the light source unit 19 is lowered, and when it is within the intermediate threshold range, the current light emission amount of the light source unit 19 is maintained and within the bright threshold range. Increases the light emission amount of the light source unit 19. The CPU 16 generates light amount correction data for correcting the light emission amount of the light source unit 19 and outputs it to the light source unit 19 as an adaptive light source current control signal. In the light source unit 19, the LED drive current control circuit 73 corrects the light emission amount by controlling the LED drive current based on the light amount correction data from the CPU 16.

  The threshold value to be compared with the above APL data is prepared in advance for each input video signal mode (NTSC video mode, PC mode, etc.) and projector display mode (DVD cinema mode, etc.) and stored in a threshold table. And can be switched as appropriate. Further, the threshold value may be individually adjusted by the user. Further, the threshold data may be held in the CPU 16, or the CPU 16 may read the threshold data from an external storage element (for example, ROM).

FIG. 6 is a graph showing an example of the drive current vs. light emission intensity characteristics of the light source unit 19.
As shown in FIG. 6, in the light source unit 19 using LEDs, there is a problem that when the drive current correction is performed so as to increase the light emission amount, the light emission intensity differs for each color of RGB and the color balance is lost. is there.
Therefore, the CPU 16 holds in advance data on the driving current versus light emission intensity characteristics of the LEDs used for the light source, and based on this characteristic data and the color sensor 1 data and color sensor 2 data acquired from the color sensors 23 and 27, the light source When the color balance of the light emitted from the unit 19 is properly maintained, the same γ correction is performed for both of the RGB colors. On the other hand, when the color balance is lost, the γ for each color of RGB is maintained so that the color balance is properly maintained. Make corrections. For example, when the red (R) luminance is reduced by the drive current correction for the light source unit 19, γ correction data that increases the red luminance is generated and output to the adaptive γ correction unit 15. The adaptive γ correction unit 15 performs γ correction for increasing the luminance of red based on the γ correction data from the CPU 16. As a result, optimal γ correction according to the average luminance level of the input video signal and the light emission amount of the light source unit 19 is performed.

FIG. 7 is a flowchart for explaining the operation of the CPU 16 related to adaptive control based on the above-described APL (average luminance level).
In FIG. 7, first, the CPU 16 performs initial setting (step S1). In this initial setting, the light amount correction amount H is set to zero. Further, the dark threshold value T1 and the bright threshold value T2 are read from the threshold value table and set. In addition, data of drive current vs. light emission intensity characteristics is read from the memory and set. In addition, default values are set for the γ correction values R-γ, G-γ, and B-γ of RGB.

  Next, the CPU 16 acquires APL data from the APL calculation unit 100 (step S2). Next, the average luminance level of the acquired APL data is compared with the dark threshold value T1 (step S3). As a result, when the average luminance level is smaller than the dark threshold value T1 (YES in step S3), it is determined that the light emission amount of the light source unit 19 is decreased in order to prevent black floating (step S4).

  On the other hand, when the average luminance level is equal to or higher than the dark threshold T1 (NO in step S3), the average luminance level is compared with the bright threshold T2 in step S5. As a result, when the average luminance level is larger than the bright threshold value T2 (YES in step S5), it is determined that the light emission amount of the light source unit 19 is increased in order to prevent white sink (step S6). If the average luminance level is less than or equal to the bright threshold T2 (NO in step S5), the process proceeds directly to step S7.

  Next, in step S <b> 7, the CPU 16 generates light amount correction data for correcting the light emission amount of the light source unit 19 based on the threshold determination result. As a result, when the average luminance level <T1, light amount correction data for reducing the light emission amount is generated. When T1 <average luminance level <T2, default data is used as light amount correction data. When the average luminance level> T2, light amount correction data for increasing the light amount is generated. Next, the CPU 16 outputs the generated light amount correction data to the light source unit 19 as an adaptive light source current control signal (step S8). Thereby, the light emission amount of the light source unit 19 is corrected.

  Next, the CPU 16 acquires ambient light amount sensor data, color sensor 1 data, color sensor 2 data, and temperature sensor data (step S9). Next, it is determined whether or not the γ curve needs to be switched based on the acquired sensor data (step S10). As a result, if switching is unnecessary, the default data is selected (step S11), and the adaptive γ correction unit 15 is instructed to select default data by the γ correction curve selection signal (step S12).

On the other hand, if it is necessary to switch the γ curve, the process proceeds to step S13, where each of the RGB colors is maintained in order to maintain an appropriate color balance based on the drive current versus emission intensity characteristic data, the color sensor 1 data, and the color sensor 2 data. A gamma correction value for each is calculated. For example, in the case of an LED having the characteristics as shown in FIG. 6, when the light emission amount of R is increased, the luminance of R reaches a peak at a certain driving current value, and thereafter the luminance does not increase even when the driving current is increased. The desired luminance cannot be obtained. Therefore, in order to correct the shortage, a γ correction value for generating a γ curve that increases the luminance of R is calculated. Next, γ correction data is generated based on the calculated γ correction value for each color (step S14). Next, the γ correction data is output to the adaptive γ correction unit 15 (step S15).
Thereby, the color balance changed by the correction of the light emission amount of the light source unit 19 according to the average luminance level is appropriately maintained by the γ correction.

[Second Embodiment]
FIG. 8 is a block diagram illustrating a configuration of the color distribution calculation unit 200 included in the digital signal processing & color conversion processing unit 14. In FIG. 8, the color distribution calculation circuit 201 calculates color distribution data (X, Y, Z) by using the input RGB data having a predetermined number of bits according to the equation (2).
X = 2.76R + 1.75G + 1.13B
Y = 1.00R + 4.59G + 5.59B
Z = 0.00R + 0.05G + 5.59B
... (2)

The calculation period generation circuit 203 calculates a calculation period based on the horizontal synchronization signal, the vertical synchronization signal, and the dot clock that are separated and generated from the input video signal, and outputs the calculation period to the chromaticity calculation & addition circuit 202.
The line thinning amount calculation circuit 204 calculates the line thinning amount based on the horizontal synchronizing signal, the vertical synchronizing signal and the dot clock that are separated and generated from the input video signal, and the thinning amount designation data from the CPU 16.
The dot thinning amount calculation circuit 205 calculates the dot thinning amount based on the horizontal synchronization signal, the vertical synchronization signal and the dot clock that are separated and generated from the input video signal, and the thinning amount designation data from the CPU 16.
The selector / synthesis circuit 206 obtains a data thinning amount based on the line thinning amount calculated by the line thinning amount calculation circuit 204 and the dot thinning amount calculated by the dot thinning amount calculation circuit 205, and the chromaticity calculation & addition circuit 202. Output to.

Next, the chromaticity calculation & addition circuit 202 includes the calculation period from the calculation period generation circuit 102, the data decimation amount from the selector / synthesis circuit 105, and the color distribution data (X, Y, Z) is used to calculate chromaticity data (x, y) that represents the distribution of chromaticity levels in one screen according to equation (3). The chromaticity data (x, y) is output to the CPU 16.
x = X / X + Y + Z, y = Y / X + Y + Z (3)

  The CPU 16 compares the chromaticity data with preset threshold data. Based on the comparison result, the light emission amount of the light source unit 19 is controlled. Specifically, it is determined whether the chromaticity distribution specific gravity is within the red-side threshold, the green-side threshold, or the blue-side threshold, and the color related to the corresponding threshold based on the determination result Increase the amount of light emitted from the LED. For example, when the color of the input video signal is distributed on the green side, light amount correction data for increasing the light emission amount of the green LED and decreasing the light emission amount of the red and blue LEDs is generated, and the adaptive light source current is generated. It outputs to the light source unit 19 as a control signal. In the light source unit 19, the LED drive current control circuit 73 corrects the light emission amount by controlling the LED drive current based on the light amount correction data from the CPU 16.

  The threshold value to be compared with the above chromaticity data is prepared in advance for each mode in which the color reproduction range is different, such as the mode of the input video signal, for example, the NTSC chromaticity of the video input or the sRGB chromaticity of the digital camera. It is stored and stored in a threshold table so that it can be switched appropriately. Further, the threshold value may be individually adjusted by the user. Further, the threshold data may be held in the CPU 16, or the CPU 16 may read the threshold data from an external storage element (for example, ROM).

FIG. 9 is a graph showing an example of the chromaticity distribution characteristics of the light source unit 19.
In the light source unit 19 having the drive current vs. light emission intensity characteristics of FIG. 6 described above, when the drive current correction is performed so as to increase the light emission amount of the LED as described above, the light emission intensity differs for each color of RGB. Balance is lost. As shown in FIG. 9, for example, when the light emission amount of the green LED is increased, there is a problem that the green light emission color is shifted to the blue side.

  Therefore, the CPU 16 does not disturb the color balance and chromaticity distribution of the light emitted from the light source unit 19 based on the data of the driving current versus the emission intensity characteristic of the LED used for the light source, and the color sensor 1 data and the color sensor 2 data. Γ correction is performed adaptively.

FIG. 10 is a flowchart for explaining the operation of the CPU 16 related to the adaptive control based on the chromaticity described above.
In FIG. 10, first, the CPU 16 performs initial setting (step S21). In this initial setting, the R light amount correction amount Rh is set to 0, the G light amount correction amount Gh is set to 0, and the B light amount correction amount Bh is set to 0. Further, the R chromaticity threshold value (Rx, Ry), the G chromaticity threshold value (Gx, Gy), and the B chromaticity threshold value (Bx, By) are read from the threshold value table and set. In addition, data of drive current vs. light emission intensity characteristics is read from the memory and set. In addition, default values are set for the γ correction values R-γ, G-γ, and B-γ of RGB.

  Next, the CPU 16 acquires chromaticity data (x, y) from the color distribution calculation unit 200 (step S22). Next, the acquired chromaticity data (x, y) is compared with the R chromaticity threshold value (Rx, Ry) (step S23). As a result, when the chromaticity data (x, y) is larger than the R chromaticity threshold value (Rx, Ry) (YES in step S23), R is dominant image data, so the light emission amount of the R LED is increased. Is determined (step S24).

  On the other hand, when the chromaticity data (x, y) is equal to or less than the R chromaticity threshold (Rx, Ry) (NO in step S23), the chromaticity data (x, y) and the G chromaticity threshold (Gx, Y) are determined in step S25. Gy). As a result, if the chromaticity data (x, y) is larger than the G chromaticity threshold value (Gx, Gy) (YES in step S25), G is the dominant image data, so the light emission amount of the G LED is increased. Is determined (step S26).

  On the other hand, when the chromaticity data (x, y) is equal to or less than the G chromaticity threshold (Gx, Gy) (NO in step S25), the chromaticity data (x, y) and the B chromaticity threshold (Bx, Y) are determined in step S27. By). As a result, when the chromaticity data (x, y) is larger than the B chromaticity threshold value (Bx, By) (YES in step S27), B is dominant image data, so the light emission amount of the B LED is increased. Is determined (step S28). If the chromaticity data (x, y) is equal to or less than the B chromaticity threshold (Bx, By) (step S27 is NO), the process proceeds to step S29 as it is.

  Next, in step S29, the CPU 16 generates light amount correction data for correcting the light emission amounts of the RGB LEDs of the light source unit 19 based on the threshold determination result. As a result, when the light emission amount of the R LED is increased, light amount correction data for increasing the light emission amount of the R LED is generated. When the light emission amount of the G LED is increased, light amount correction data for increasing the light emission amount of the G LED is generated. When the light emission amount of the B LED is increased, light amount correction data for increasing the light emission amount of the G LED is generated. When none of the RGB LEDs increases the light emission amount, the default data is used as the light amount correction data.

  Since the light source unit 19 is a light source capable of controlling the light emission amounts individually for RGB, the light emission amount of the dominant color LED in the image data is increased based on the chromaticity data, and the light emission amounts of the other color LEDs are as follows. Set to default value. For example, in the case of image data in which R is dominant, the light emission amount of the R LED is increased, and the light emission amounts of other G and B color LEDs are set to default values. As a result, the dynamic range of display luminance can be increased and overall power saving can be realized.

  Next, the CPU 16 outputs the generated light amount correction data to the light source unit 19 as an adaptive light source current control signal (step S30). Thereby, the light emission amount of the LED of the corresponding color of the light source unit 19 is corrected.

  Next, the CPU 16 acquires ambient light amount sensor data, color sensor 1 data, color sensor 2 data, and temperature sensor data (step S31). Next, it is determined whether or not it is necessary to switch the γ curve based on the acquired sensor data (step S32). As a result, if switching is unnecessary, the default data is selected (step S33), and the adaptive γ correction unit 15 is instructed to select default data by the γ correction curve selection signal (step S34).

On the other hand, if it is necessary to switch the γ curve, the process proceeds to step S35, where each of the RGB colors is maintained in order to maintain an appropriate color balance based on the drive current versus emission intensity characteristic data, the color sensor 1 data, and the color sensor 2 data. A gamma correction value for each is calculated. Next, γ correction data is generated based on the calculated γ correction value for each color (step S36). Next, the γ correction data is output to the adaptive γ correction unit 15 (step S37).
As a result, the color balance changed by correcting the light emission amounts of the RGB LEDs of the light source unit 19 in accordance with the chromaticity is appropriately maintained by the γ correction.

[Third Embodiment]
FIG. 11 is a block diagram showing a configuration related to adaptive control based on the amount of external light or the amount of change in the LCD panel ambient temperature.
First, the operation of the CPU 16 related to adaptive control based on the amount of change in the amount of external light will be described with reference to FIG. In FIG. 11, an external light quantity sensor 29-1 detects the quantity of light around the surface of the screen 2, which is the projection plane of the image projection apparatus 1 shown in FIG. Since the detected data is an analog current value, it is converted into an analog voltage value by the IV conversion unit 29-2, digitized by the A / D converter 30, and input to the CPU 16 as ambient light amount sensor data. Is done.

  In the CPU 16, the light amount change calculation unit 301 calculates a light amount change amount for a predetermined time set in the detection time setting unit 302. The data comparison calculation unit 303 compares predetermined threshold data preset in the threshold data storage unit 304 with the light amount change amount calculated by the light amount change calculation unit 301. Based on the comparison result, correction data corresponding to the amount of change in the amount of ambient light on the projection surface is generated.

  The correction data is correction data for the drive current and γ curve of the light source unit 19 and is generated so as to obtain an optimal display. Specifically, the CPU 16 increases the amount of illumination light emitted by the light source unit 19 and the amount of illumination light emitted when the outside light amount by the outside light amount sensor 29-1 exceeds a predetermined threshold. The γ curve used for the modulation by the LCD panel 18 is corrected so as to cancel out the change in the color balance of the illumination light emitted from the light source unit 19 that is generated by increasing.

  Next, the operation of the CPU 16 related to adaptive control based on the amount of change in the LCD panel ambient temperature will be described with reference to FIG. In FIG. 11, an LCD panel ambient temperature sensor 25-1 detects the ambient temperature of the LCD panel 18 shown in FIG. Since the detected data is an analog current value, it is converted to an analog voltage value by the IV conversion unit 25-2, digitized by the A / D converter 26, and input to the CPU 16 as temperature sensor data. The

  In the CPU 16, the temperature change calculation unit 311 calculates a temperature change amount for a predetermined time set in the detection time setting unit 302. The data comparison calculation unit 312 compares predetermined threshold data preset in the threshold data storage unit 313 with the temperature change amount calculated by the temperature change calculation unit 311. Based on the comparison result, correction data corresponding to the amount of change in the ambient temperature of the LCD panel 18 is generated.

  The correction data is correction data for the drive current and γ curve of the light source unit 19 and is generated so as to obtain an optimal display. Specifically, when the temperature by the LCD panel ambient temperature sensor 25-1 exceeds a predetermined threshold, the CPU 16 cancels the change in the color balance of the illumination light that is modulated by the LCD panel 18 that occurs with this temperature change. Thus, the light source unit 19 emits the light so as to correct the γ curve used for modulation by the LCD panel 18 and to cancel the change in the amount of illumination light of the LCD panel 18 caused by correcting the γ curve. Correct the amount of illumination light.

  Each parameter selector or supervising section 320 in FIG. 11 selects either correction data corresponding to the amount of change in the projection plane ambient light amount or correction data corresponding to the amount of change in the LCD panel ambient temperature, or both. Performs processing to control correction data. The CPU 16 corrects the drive current and γ curve of the light source unit 19 based on the output result of each parameter selector or supervising unit 320.

  The threshold data may be held inside the CPU 16 as shown in FIG. 11 or the CPU 16 may read the threshold data from an external storage element (for example, ROM).

[Fourth Embodiment]
FIG. 12 is a block diagram showing a configuration related to adaptive control based on the amount of change in the color distribution of light emitted from the light source unit 19.
The RGB color sensor 23-1 detects the amount of light of each RGB color of the light from the light source unit 19. Since the detected data is an analog current value, it is converted into an analog voltage value by each IV conversion unit 23-2, and then digitized by the A / D converter 24 to the CPU 16 as color sensor 1 data. Entered.

  In the CPU 16, the color distribution change calculation unit 401 calculates the change amount of the color distribution at a predetermined time set in the detection time setting unit 402. The data comparison calculation unit 403 compares predetermined threshold data preset in the threshold data storage unit 404 with the color distribution change amount calculated by the color distribution change calculation unit 401. Based on the comparison result, correction data corresponding to the amount of change in the color distribution of the light generated from the light source unit 19 is generated.

  The correction data is correction data for the drive current and γ curve of the light source unit 19 and is generated so as to obtain an optimal display. Specifically, the CPU 16 sets the LCD panel so as to cancel the change in the color balance of the illumination light emitted from the light source unit 19 when the change amount of the color balance detected by the RGB color sensor 23 exceeds a predetermined threshold. The amount of illumination light emitted by the light source unit 19 is corrected so that the change in the amount of illumination light of the LCD panel 18 caused by correcting the γ curve is corrected while correcting the γ curve used for modulation at 18. to correct.

  Each parameter selector or supervising unit 420 in FIG. 12 selects either correction data for each RGB color in the correction data corresponding to the amount of change in the color distribution of light generated from the light source unit 19, or A process for controlling a plurality of correction data is performed. The CPU 16 corrects the drive current and the γ curve of the light source unit 19 based on the output result of each parameter selector or control unit 420.

  Note that the threshold data may be held in the CPU 16 as shown in FIG. 12, or the CPU 16 may read the threshold data from an external storage element (for example, ROM).

[Fifth Embodiment]
FIG. 13 is a block diagram showing a configuration relating to automatic calibration by replacement of the light source unit 19 or the LCD panel 18.
The RGB color sensors 23-1 detect the light amounts of the RGB colors of the light from the light source unit 19, and the detected data are converted into analog voltage values by the respective IV conversion units 23-2. It is digitized by the A / D converter 24 and input to the CPU 16 as color sensor 1 data.
The RGB color sensor 27-1 detects the RGB light amounts of the projection light from the LCD panel 18, and these detected data are converted into analog voltage values by the IV conversion units 27-2. , Digitized by the A / D converter 28 and input to the CPU 16 as the color sensor 2 data.

  In the CPU 16, the replacement detection unit 501 reads the unit identification information from the light source unit 19 and compares it with the past reading result to determine whether the light source unit 19 is replaced. Further, the panel identification information is read from the LCD panel 18 and compared with the past reading result, thereby determining whether or not the LCD panel 18 is replaced. When it is detected that the light source unit 19 or the LCD panel 18 is exchanged, an exchange notification signal is output to the start setting unit 502. When the start setting unit 502 receives the exchange notification signal, the start setting unit 502 outputs a calculation start signal to the color distribution calculation units 503 and 504.

  When receiving the calculation start signal, the color distribution calculation units 503 and 504 start the color distribution calculation. The color distribution calculation unit 503 calculates chromaticity data using the color sensor 1 data. The color distribution calculation unit 504 calculates chromaticity data using the color sensor 2 data. Each chromaticity data calculated by the color distribution calculation units 503 and 504 is input to the data comparison calculation unit 505.

The data comparison calculation unit 505 compares the chromaticity data from the color distribution calculation unit 503 with the chromaticity data from the color distribution calculation unit 504 and outputs the comparison result to the calibration data calculation unit 506. The calibration data calculation unit 506 generates γ correction data based on the comparison result from the data comparison calculation unit 505 in order to keep the color balance appropriate. The CPU 16 outputs the γ correction data to the adaptive γ correction unit 15.
Thereby, when the light source unit 19 or the LCD panel 18 is replaced, calibration is automatically performed so as to obtain an appropriate color balance.

  The γ correction data may be prepared in advance and stored in a storage unit such as an external RAM, and may be selected from the data, or a plurality of γ correction data created by the adaptive γ correction unit 15 may be selected. An optimum curve may be selected from the curves based on the chromaticity data comparison result in the CPU 16.

  Further, the calibration by exchanging the light source unit 19 has a light emission characteristic that depends on the type of LED when the light source unit is replaced with a different type of light source unit even when the variation in individual light emission characteristics of the same type of light source unit is corrected. The present invention can also be applied when correcting to an optimal γ curve.

[Explanation about correction of γ curve]
14 to 20 are waveform diagrams for explaining correction of the γ curve.
A waveform a in FIG. 14 represents the correction characteristic of “γ = 0.45” on the image transmission side transmitted from a broadcasting station or the like. This is based on the assumption that the photoelectric conversion characteristic of “γ = 2.2” in the CRT (CRT) shown by the waveform b in FIG. 15 is that the correction of “γ = 0.45” is performed on the video signal on the broadcasting station side. This is because the normal value of γ in NTSC is set to 2.2.

  On the other hand, the LCD display device has a unique VT (applied voltage versus transmittance) characteristic for each panel (waveform c in FIG. 16). Accordingly, in order to perform linear display as shown by the waveform e in FIG. 18 by the LCD panel 18, it is necessary to perform reverse correction as shown by the waveform d in FIG. That is, in order to perform linear display of the waveform e in FIG. 18, the correction of “waveform b + waveform d = waveform f (FIG. 19)” may be performed.

  In the embodiment according to the present invention, γ correction is performed by correcting the waveform f in FIG. That is, correction is performed on the correction curve of the waveform f in FIG. 19 based on information obtained by each parameter detection unit of the above-described embodiment. For example, when the average luminance level of the input video signal is high (within the bright threshold range), the waveform f is corrected so as to perform white expansion indicated by the waveform g. On the other hand, when the average luminance level is low (within the dark threshold range), the waveform f is corrected so as to be subjected to black expansion indicated by the waveform h. Thereby, a favorable display with high contrast can be performed. Further, by correcting the light emission amount of the LED for each color of RGB, it is possible to maintain an optimal color balance for the light from the light source unit 19 and to display with excellent quality.

  As described above, according to the embodiment of the present invention, the average luminance of the input video signal, the luminance level of the projection image, the luminance level of the light source, the amount of external light, or the ambient temperature of the LED panel is detected, and an optimal γ correction + By performing (V-T correction) and controlling the light emission intensity of the light source, it is possible to realize gradation display, color reproduction display (color temperature control), and power saving optimum for the LED light source.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

It is a block diagram which shows the structure of the liquid-crystal projector system which concerns on one Embodiment of this invention. It is a top view which shows the structure of the light source unit 19 shown in FIG. It is sectional drawing which shows the structure of the light source unit 19 shown in FIG. It is a block diagram which shows the electrical structure of the light source unit 19 shown in FIG. It is a block diagram which shows the structure of the APL calculating part 100 with which the digital signal processing & color conversion process part 14 shown in FIG. 6 is a graph showing an example of drive current versus light emission intensity characteristics of the light source unit 19. FIG. It is a flowchart for demonstrating operation | movement of CPU16 which concerns on the adaptive control based on APL (average luminance level). It is a block diagram which shows the structure of the color distribution calculating part 200 with which the digital signal processing & color conversion process part 14 shown in FIG. 6 is a graph showing an example of chromaticity distribution characteristics of the light source unit 19. FIG. It is a flowchart for demonstrating operation | movement of CPU16 which concerns on the adaptive control based on chromaticity. It is a block diagram which shows the structure concerning the adaptive control based on the variation | change_quantity of the amount of external light, or LCD panel ambient temperature. 4 is a block diagram showing a configuration related to adaptive control based on a change amount of a color distribution of light emitted from a light source unit 19. FIG. 3 is a block diagram showing a configuration relating to automatic calibration by replacement of a light source unit 19 or an LCD panel 18. FIG. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention. It is a wave form diagram for explaining amendment of γ curve concerning an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image projector, 11 ... Signal input part, 12, 24, 26, 28, 30 ... A / D converter, 13 ... Video decoder, 14 ... Digital signal processing & color conversion process part, 15 ... Adaptive gamma correction part, 16 ... CPU, 17 ... LCD signal processing unit & panel drive processing unit, 18 ... LCD panel, 19 ... light source unit, 20 ... illumination lens, 21 ... projection lens, 22 ... current control unit, 23 ... RGB color sensor, 25 DESCRIPTION OF SYMBOLS ... Temperature sensor 27 ... RGB color sensor 29 ... Projection surface surrounding light quantity sensor 100 ... Average brightness level calculating part 200 ... Color distribution calculating part 301 ... Light quantity change calculating part 401 ... Color distribution change calculating part 501 ... Exchange detection unit, 506... Calibration data calculation unit.

Claims (16)

An image projection apparatus that projects an image according to input image information on a screen,
Light source means for emitting illumination light capable of controlling color balance, which is a luminance distribution for each wavelength band;
Spatial modulation means for modulating the illumination light emitted by the light source means based on the image information;
Projection means for projecting illumination light modulated by the spatial modulation means onto a screen;
Parameter detecting means for detecting a change amount of a predetermined parameter relating to a color or luminance of an image projected on the screen by the projecting means;
According to the change amount of the predetermined parameter detected by the parameter detecting means, at least the color balance of the illumination light out of the color balance of the illumination light emitted by the light source means and the γ curve used for modulation by the spatial modulation means is corrected. Control means for controlling
An image projection apparatus comprising: Image information monitoring means for obtaining an average value of luminance values of the input image information;
The change amount of the predetermined parameter is a change amount of the average brightness value obtained by the image information monitoring unit,
The control means includes
The image projection apparatus according to claim 1, wherein control is performed according to whether or not the average luminance value is below a predetermined threshold. The control means includes
The light source generated by reducing the amount of illumination light emitted by the light source means and reducing the amount of illumination light emitted when the average luminance value obtained by the image information monitoring means falls below a predetermined threshold value The image projection apparatus according to claim 2, wherein a γ curve used for modulation by the spatial modulation unit is corrected so as to cancel a change in color balance of illumination light emitted by the unit. Image information monitoring means for obtaining a color distribution of the input image information;
The change amount of the predetermined parameter is a change amount of the color distribution obtained by the image information monitoring unit,
The control means includes
The image projection apparatus according to claim 1, wherein control is performed according to whether or not a change amount of the color distribution exceeds a predetermined threshold value. The control means includes
When the amount of change in the color distribution exceeds a predetermined threshold, the color balance of the illumination light emitted by the light source means is corrected according to the color distribution of the input image information, and the color of the illumination light emitted 5. The γ curve used for modulation by the spatial modulation means is corrected so as to cancel out a change in color balance of illumination light emitted from the light source means, which is generated by correcting the balance. The image projection apparatus described in 1. An external light amount sensor for detecting the amount of external light in the environment where the image projection apparatus is installed;
The change amount of the predetermined parameter is a change amount of the external light amount detected by the external light amount sensor,
The control means includes
The image projection apparatus according to claim 1, wherein control is performed in accordance with whether or not the amount of change in the amount of external light exceeds a predetermined threshold. The control means includes
When the external light quantity obtained by the external light quantity sensor exceeds a predetermined threshold, the light quantity emitted from the light source means is increased, and the light quantity of the emitted illumination light is increased. The image projection apparatus according to claim 6, wherein a γ curve used for modulation by the spatial modulation unit is corrected so as to cancel a change in color balance of illumination light emitted from the light source unit. A temperature sensor for detecting the temperature of the spatial modulation means or the vicinity thereof;
The change amount of the predetermined parameter is a change amount of the temperature detected by the temperature sensor,
The control means includes
The image projection apparatus according to claim 1, wherein control is performed in accordance with whether or not the temperature change amount exceeds a predetermined threshold value. The control means includes
When the temperature of the spatial modulation unit obtained by the temperature sensor or the temperature in the vicinity thereof exceeds a predetermined threshold value, the change in the color balance of the illumination light modulated by the spatial modulation unit generated with the temperature change is offset. The light source means emits so as to correct the γ curve used for modulation by the spatial modulation means and to cancel the change in the amount of illumination light of the spatial modulation means caused by correcting the γ curve. The image projection apparatus according to claim 8, wherein the amount of illumination light is corrected. A first color sensor for detecting a color balance of illumination light emitted by the light source means;
The change amount of the predetermined parameter is a change amount of the color balance detected by the first color sensor,
The control means includes
The image projection apparatus according to claim 1, wherein control is performed according to whether or not the amount of change in the color balance exceeds a predetermined threshold value. The control means includes
When the spatial modulation means modulates the change of the color balance of the illumination light emitted by the light source means when the change amount of the color balance detected by the first color sensor exceeds a predetermined threshold value. And correcting the amount of illumination light emitted by the light source means so as to cancel the change in the amount of illumination light of the spatial modulation means caused by correcting the γ curve. The image projection apparatus according to claim 10. A first color sensor for detecting a color balance of illumination light emitted by the light source means;
A second color sensor for detecting a color balance of the illumination light modulated by the spatial modulation means;
And a calibration unit for re-determining a γ curve used for modulation by the spatial modulation unit based on the color balance detected by the first color sensor and the color balance detected by the second color sensor. The image projection apparatus according to claim 1.   The image projection apparatus according to claim 12, wherein the calibration unit recalculates the γ curve when the light source unit is replaced. Further comprising light source identification information reading means for detecting identification information of the light source means,
The image projection apparatus according to claim 13, wherein the calibration unit detects that the light source unit has been replaced using a detection result of the light source identification information reading unit.   The image projection apparatus according to claim 12, wherein the calibration unit recalculates the γ curve when the spatial modulation unit is replaced. It further has panel identification information reading means for detecting identification information possessed by the spatial modulation means,
The image projection apparatus according to claim 15, wherein the calibration unit detects that the spatial modulation unit has been replaced using a detection result of the panel identification information reading unit.

Images