JP2017168901A - Multi-screen display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-screen display device that can maintain white chromaticity in a video to be displayed on a multi-screen almost constant before operating time reaches certain time and suppress brightness of the video from deteriorating largely after the operating time reaches the certain time, so as to prevent the brightness and the chromaticity from becoming uneven.SOLUTION: When minimum maintenance rates for red light, green light and blue light do not include minimum maintenance rates below a threshold, brightness of the red light, the green light and the blue light is controlled based on the minimum maintenance rates for the red light, the green light and the blue light. When the minimum maintenance rates for the red light, the green light and the blue light include the minimum maintenance rates below the threshold, brightness of the light having the minimum maintenance rate below the threshold is controlled based on the minimum maintenance rate for the light. When the minimum maintenance rates for the red light, the green light and the blue light include the minimum maintenance rates which are not below the threshold, brightness of the light having the minimum maintenance rate which is not below the threshold is controlled based on the threshold.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a multi-screen display device.

  In a multi-screen display device, a plurality of screens respectively provided in a plurality of video display devices are combined, and a large-scale multi-screen is configured by a plurality of combined screens, and the multi-screen configured Is displayed on the screen. In some images displayed on a multi-screen, color reproducibility is regarded as important and color reproducibility is not regarded as important. The images where color reproducibility is important are camera images, television images, and the like. A video whose color reproducibility is not regarded as important is based on primary colors such as a communication system diagram and an operation system diagram.

  Each of the plurality of video display devices is, for example, a projection video display device. In a projection display apparatus, light emitted from a light source is converted into image light by an image display device, image light generated by the conversion is irradiated on the back of the screen, and an image is projected onto the screen. As a result, the screen becomes a screen that displays a color image.

  In recent years, light-emitting diodes (LEDs) have been widely used as light sources in order to reduce the power consumption of the projection display apparatus and extend the life of the projection display apparatus. For example, a red LED, a green LED, and a blue LED are used as the light source. When red LED, green LED and blue LED are used as light source, red light, green light and blue light emitted by red LED, green LED and blue LED respectively are synthesized by dichroic mirror, dichroic prism, etc. The generated combined light is modulated by an image display device such as a digital mirror device (DMD), the image light generated by the modulation is irradiated on the back of the screen, and a color image is projected on the screen. As a result, the screen becomes a screen that displays a color image.

  LEDs used as light sources have individual differences with respect to their characteristics. For this reason, when the LED is used as a light source, the luminance and the luminance are increased when the use of the multi-screen display device is started or when the use time of the multi-screen display device is increased in the images displayed on the plurality of screens. The chromaticity may become uneven. In a multi-screen display device, a multi-screen is composed of a plurality of combined screens. Therefore, if the luminance and chromaticity are uneven in the video displayed on the plurality of screens, the multi-screen display device The unevenness of luminance and chromaticity in the displayed video is conspicuous, and the sense of unity of the plurality of screens is impaired. For this reason, when the LED is used as a light source, each of the plurality of video display devices is adjusted so that the luminance and chromaticity are uniform in the video displayed on the plurality of screens.

  In the technique described in Patent Document 1, when a power button is turned on, luminance / chromaticity sensors provided in each of a plurality of liquid crystal projectors provided in the liquid crystal display device are operated, and the measurement result is an ideal white color. The chromaticity correction is performed so as to be within the range of the above, and each of the plurality of projectors is adjusted to the lowest luminance among the plurality of luminances of each of the plurality of projectors. Thereby, the brightness and chromaticity of the entire screen constituted by a plurality of projectors are always uniform.

  Further, in the technique described in Patent Document 2, the target luminance of the entire multi-screen is obtained from two luminance / chromaticity data respectively provided in the master projection display device and the slave projection display device provided in the multi-screen display device.・ Chromaticity is calculated, and a correction coefficient for generating the calculated target luminance and chromaticity is calculated in each of the master projection display device and the slave projection display device, and an image is input using the calculated correction coefficient as input. Luminance and chromaticity correction is performed on the signal. Thereby, the adjustment is automatically performed so that the difference in luminance and chromaticity between the master projection display device and the slave projection display device is reduced.

Japanese Patent Laid-Open No. 10-90645 Japanese Patent No. 4823660

  The light emitting units included in the red LED, the green LED, and the blue LED have different structures and are made of different materials. For this reason, the red LED, the green LED, and the blue LED have different lifetimes, and have different characteristics with respect to the rate at which the luminance decreases as the usage time increases. Moreover, the lifetime which LED has changes with the environment where LED is used, and becomes short, so that the temperature of the environment where LED is used becomes high. Further, when the LED is driven by the pulse width modulation method, the lifetime of the LED becomes shorter as the duty ratio of the drive signal increases and the ratio of the LED lighting time to the LED blinking period increases. Therefore, when the red LED, the green LED, and the blue LED are used as the light source, the amount of decrease in luminance of the red light, the green light, and the blue light is different from each other.

  For this reason, when the red LED, the green LED, and the blue LED are used as the light source, when the adjustment for maintaining the white chromaticity substantially constant as in the technique described in Patent Document 1 is performed, the red LED is used. The luminance of the remaining light is lowered in accordance with the luminance of the light, the luminance of which is the lowest among the light, green light and blue light, and the luminance balance of the red light, green light and blue light is maintained. Therefore, the luminance is greatly reduced in each of the plurality of screens, and the luminance is greatly reduced in the multi-screen. This problem also occurs when the red LED, green LED, and blue LED are replaced with three or more LEDs other than the red LED, green LED, and blue LED.

  The present invention is made to solve this problem. The problem to be solved by the present invention is that, in a video displayed on a multi-screen, the chromaticity of white is maintained almost constant before the usage time reaches a certain time, and the usage time reaches a certain time. After that, it is to suppress the luminance from greatly decreasing and to suppress the luminance and chromaticity from becoming non-uniform.

  The multi-screen display device includes m video display devices. m is an integer of 2 or more.

  Each of the m video display devices includes a screen, first to nth light emitting diodes, an optical sensor, and a luminance control unit. n is an integer of 3 or more.

  The screen constitutes a multi-screen.

  The first to nth light emitting diodes emit first to nth lights having different colors, respectively.

  The photosensor measures first to nth luminance values indicating luminances of the first to nth lights, respectively.

  The brightness control unit performs the following control.

  (1) The first to nth luminance maintenance ratios are calculated. The i-th luminance maintenance ratio is a ratio of the i-th luminance value to the i-th initial luminance value when i is 1 to n.

  (2) The first to nth minimum maintenance rates are acquired. The i-th minimum maintenance ratio is the lowest value among the m number of i-th luminance maintenance ratios calculated in the m video display devices when i is 1 to n, respectively.

  (3) A threshold common to the first to n-th minimum maintenance rates is set.

  (4) When the first to nth minimum maintenance rates do not include the minimum maintenance rate below the threshold, the luminance values indicating the luminances of the light emitted by the first to nth light emitting diodes are respectively The brightness of light emitted by the first to nth light emitting diodes is controlled so that the initial brightness value up to the nth is multiplied by the lowest value among the first to nth minimum maintenance rates. The

  (5) When the first to nth minimum maintenance rates include the jth minimum maintenance rate below the threshold, the luminance value indicating the luminance of light emitted by the jth light emitting diode is the jth initial luminance. The brightness of the light emitted by the jth light emitting diode is controlled so that the value is multiplied by the jth minimum maintenance factor. When the first to nth minimum maintenance ratios further include the kth minimum maintenance ratio that does not fall below the threshold value, the brightness value indicating the brightness of the light emitted by the kth light emitting diode is the kth initial brightness value. The brightness of the light emitted by the kth light emitting diode is controlled so as to be multiplied by a threshold value.

  In each of the m video display devices, the luminance of the n lights is controlled based on a threshold value common to the m video display devices or the lowest value among the first to nth minimum maintenance rates. For this reason, the luminance and chromaticity change in the same manner in the images displayed on the m screens. Therefore, in the video displayed on the multi-screen, the luminance and chromaticity are suppressed from becoming non-uniform as the usage time increases.

  Further, in each of the m video display devices, the first to n-th minimum maintenance ratios common to the n pieces of light are before the minimum maintenance ratios of n pieces are less than the threshold. The brightness of the light emitted by each of the first to nth light emitting diodes is controlled based on the lowest value of these. Therefore, until the usage time reaches a certain time, the white chromaticity is maintained substantially constant in the video displayed on each of the m screens, and the white chromaticity is substantially constant in the video displayed on the multi-screen. Maintained constant.

  Further, in each of the m video display devices, after the n minimum maintenance rates include the minimum maintenance rate below the threshold, the luminance of light having the minimum maintenance rate below the threshold becomes the minimum maintenance rate. Based on the threshold, the brightness of the light having the lowest maintenance rate that is not below the threshold is controlled. For this reason, in each of the m video display devices, it is suppressed that the luminance of the light having the lowest maintenance rate that is not below the threshold value is greatly reduced, and the luminance displayed in the video displayed on each of the m screens is greatly reduced. To suppress the luminance from being greatly reduced in the video displayed on the multi-screen.

  As a result, in the video displayed on the multi-screen, the chromaticity of white is maintained almost constant before the usage time reaches a certain time, and the brightness greatly decreases after the usage time reaches a certain time. Is suppressed, and the luminance and chromaticity are suppressed from becoming non-uniform.

It is a schematic diagram which shows a multiscreen display apparatus. It is a schematic diagram which shows a multiscreen display apparatus. It is a graph which shows the example of the change by the usage time of the brightness | luminance maintenance factor in a master apparatus. It is a graph which shows the example of the change by the usage time of the brightness | luminance maintenance factor in a slave apparatus. It is a graph which shows the example of the change by the usage time of the brightness | luminance maintenance factor used as the minimum maintenance factor. It is a flowchart which shows the flow of acquisition of the minimum maintenance rate in a master apparatus. It is a flowchart which shows the flow of acquisition of the minimum maintenance rate in a slave apparatus. It is a flowchart which shows the flow of the brightness | luminance control in a master apparatus. It is a graph which shows the example of the change by the usage time of the luminance maintenance rate after luminance control was performed. It is a graph which shows the example of the change by the usage time of the brightness | luminance maintenance factor after the brightness | luminance control was performed in the multiscreen display apparatus in which the technique described in Unexamined-Japanese-Patent No. 10-90645 was used. It is a graph which shows the example of the change by the usage time of the brightness | luminance maintenance factor used as the minimum maintenance factor. It is a graph which shows the change by the usage time of the brightness | luminance maintenance factor after luminance control was performed.

1 Multi-Screen Display Device FIGS. 1 and 2 are schematic views showing a multi-screen display device according to this embodiment. FIG. 1 shows hardware included in a multi-screen display device. FIG. 2 shows a luminance control system provided in the multi-screen display device.

  A multi-screen display device 100 shown in each of FIGS. 1 and 2 is a master projection video display device (hereinafter referred to as “master device”) 104m, and a slave projection video display device (hereinafter referred to as “slave device”). 104s and a communication cable 106 are provided.

  The master device 104m includes a light source 108m, a dichroic mirror 110m, a relay lens 112m, an internal total reflection (TIR) prism 114m, a digital mirror device (DMD) 116m, a projection lens 118m, a screen 120m, a three primary color light sensor 122m, a processing circuit 124m, and a memory. A device 126m and a processing circuit 128m are provided. The light source 108m includes a red light emitting diode (LED) 132m, a green LED 134m, and a blue LED 136m. The processing circuit 124m, the storage device 126m, and the processing circuit 128m constitute the luminance control unit 140m shown in FIG.

  The slave device 104s includes a light source 108s, a dichroic mirror 110s, a relay lens 112s, a TIR prism 114s, a DMD 116s, a projection lens 118s, a screen 120s, a three primary color light sensor 122s, a processing circuit 124s, and a storage device 126s. The light source 108s includes a red LED 132s, a green LED 134s, and a blue LED 136s. The processing circuit 124s and the storage device 126s constitute the luminance control unit 140s shown in FIG.

  The light source 108s, the dichroic mirror 110s, the relay lens 112s, the TIR prism 114s, the DMD 116s, the projection lens 118s, the screen 120s, and the three primary color light sensors 122s provided in the slave device 104s are respectively the light source 108m, the dichroic mirror 110m, The relay lens 112m, the TIR prism 114m, the DMD 116m, the projection lens 118m, the screen 120m, and the three primary color light sensors 122m are the same.

  The multi-screen display device 100 includes two projection video display devices, a master device 104m and a slave device 104s, and has a multi-screen 144. The multi screen 144 is composed of screens 120m and 120s. In the multi-screen display device 100, a master device 104m and a slave device 104s are combined. In the multi-screen 144, the screens 120m and 120s are combined. Two projection display apparatuses may be replaced with three or more projection display apparatuses. The luminance control by the luminance control unit 140m or 140s may be performed in a video display device that is not a projection video display device.

2 Master Device and Slave Device In the master device 104m, the red LED 132m, the green LED 134m, and the blue LED 136m emit red light 148m, green light 150m, and blue light 152m, respectively. The red LED 132m, the green LED 134m, and the blue LED 136m may be replaced with three or more LEDs that respectively emit three or more lights having different colors other than the red LED, the green LED, and the blue LED.

  The time when the light source 108m emits light is the first lighting time when the red LED 132m emits red light 148m, the second lighting time when the green LED 134m emits green light 150m, and the third lighting time when the blue LED 136m emits blue light 152m. Time-divided.

  The dichroic mirror 110m combines the emitted red light 148m, green light 150m, and blue light 152m to generate combined light 156m. The dichroic mirror 110m has a reflecting surface that reflects light having a specific wavelength and transmits other light. Each of red light 148m, green light 150m, and blue light 152m included in combined light 156m travels on a common optical path. The dichroic mirror 110m may be replaced with another type of light combining optical system. For example, the dichroic mirror 110m may be replaced with a dichroic prism.

  The generated combined light 156m passes through the relay lens 112m and the TIR prism 114m, and is irradiated to the DMD 116m. When the synthesized light 156m passes through the TIR prism 114m, the synthesized light 156m is reflected on the total reflection surface of the TIR prism 114m. The optical system including the relay lens 112m and the TIR prism 114m may be replaced with another optical system.

  The DMD 116m modulates the irradiated combined light 156m and generates the on-light 160m and the off-light 162m in each of the first lighting time, the second lighting time, and the third lighting time, whereby the red light 148m, On light 160m and off light 162m are generated for each of the green light 150m and the blue light 152m. When the DMD 116m modulates the composite light 156m, the tilt of the micromirror provided in the DMD 116m changes according to the video signal input to the DMD 116m, and the reflection direction of the irradiated composite light 156m changes. When the gain when the video signal is amplified becomes large and the video signal inputted to the DMD 116m becomes large, the time for generating the on-light 160m becomes long and the luminance becomes high. The DMD 116m may be replaced with another type of image display device.

  The on-light 160m passes through the projection lens 118m and is irradiated on the screen 120m. Thereby, a color image is projected onto the screen 120m. As a result, the screen 120m becomes a screen that displays a color image. The optical system including the projection lens 118m may be replaced with another optical system.

  The off-light 162m is received by the three primary color light sensors 122m arranged on the optical path. The three primary color light sensors 122m measure stimulus values X, Y, and Z indicating the color of the received off-light 162m. The stimulus values X, Y and Z are colorimetric values in the XYZ color system. The stimulus value Y is a luminance value indicating luminance. If the light sensor used for the initial adjustment described later is different from the light sensor used for the adjustment in use, which will be described later, the light sensor used for the adjustment in use measures only the luminance value. Also good. When the optical sensor used for the initial adjustment described later is different from the optical sensor used for the adjustment in use described later, the optical sensor used for the adjustment in use may measure only the luminance value.

  DMD 116m generates off light 162m for each of red light 148m, green light 150m, and blue light 152m. For this reason, the three primary color light sensors 122m receive the off-light 162m, thereby causing the red light 148m, the green light 150m, and the blue light 152m to indicate the colors of the red light 148m, the green light 150m, and the blue light 152m, respectively. The tristimulus value data DSTm including Y and Z is measured. The measured tristimulus value data DSTm is always output. From the tristimulus value data DSTm, the luminance values of the red light 148m, the green light 150m, and the blue light 152m indicating the luminance of the red light 148m, the green light 150m, and the blue light 152m, respectively, are derived, and the red light 148m, the green light 150m, and The chromaticity values of the red light 148m, the green light 150m, and the blue light 152m, which respectively indicate the chromaticity of the blue light 152m, are derived. Therefore, the three primary color light sensors 122m can measure the luminance value and the chromaticity value of each of the red light 148m, the green light 150m, and the blue light 152m. While the master device 104m is used, the three primary color light sensors 122m constantly monitor the luminance change and chromaticity change of each of the red light 148m, the green light 150m, and the blue light 152m.

  The dichroic mirror 110m advances a common optical path for the red light 148m, the green light 150m, and the blue light 152m. For this reason, a change in luminance and a change in chromaticity of each of the red light 148m, the green light 150m, and the blue light 152m are monitored by the single primary color light sensor 122m. This reduces the cost of the components that make up the master device 104m, and places the photosensors to monitor the luminance and chromaticity changes of each of the red light 148m, green light 150m and blue light 152m. This contributes to reducing the restrictions.

  The three primary color light sensors 122m receive off light 162m that is not irradiated on the screen 120m. For this reason, the monitoring of the change in luminance and the change in chromaticity does not hinder the display of the color image on the screen 120m and is not easily affected by the surrounding environment such as outside light.

  The processing circuit 124m controls the modulation of the combined light 156m in the DMD 116m.

  The light source 108s, the dichroic mirror 110s, the relay lens 112s, the TIR prism 114s, the digital mirror device 116s, the projection lens 118s, the screen 120s, and the three primary color light sensors 122s provided in the slave device 104s are respectively the light source 108m and dichroic provided in the master device 104m. The mirror 110m, the relay lens 112m, the TIR prism 114m, the digital mirror device 116m, the projection lens 118m, the screen 120m, and the three primary color light sensors 122m operate. For this reason, in the slave device 104s, the red LED 132s, the green LED 134s, and the blue LED 136s emit red light 148s, green light 150s, and blue light 152s, respectively. In addition, the dichroic mirror 110s combines the emitted red light 148s, green light 150s, and blue light 152s to generate combined light 156s. Further, the DMD 116s modulates the irradiated combined light 156s, and generates on-light 160s and off-light 162s for each of the red light 148s, the green light 150s, and the blue light 152s. The on light 160s is applied to the screen 120s. The three primary color light sensors 122s receive off-light 162s and include stimulation values X, Y, and Z of red light 148s, green light 150s, and blue light 152s indicating the colors of red light 148s, green light 150s, and blue light 152s, respectively. Tristimulus value data DSTs are measured.

  The processing circuit 124m is communicably connected to the processing circuit 124s through the communication cable 106. The processing circuit 124m communicates with the processing circuit 124s in accordance with a communication standard such as RS232C.

3 Adjustment of Multi-Screen Display Device In the multi-screen display device 100, initial adjustment is performed when the use of the multi-screen display device 100 is started, and the multi-screen display device 100 is still in use after the use of the multi-screen display device 100 is started. Adjustments are always made.

  In the initial adjustment, the luminance and chromaticity in the video displayed on each of the screens 120m and 120s are brought close to the target luminance and the target chromaticity, respectively. As a result, the luminance and chromaticity in the video displayed on the screen 120s are changed. The brightness and chromaticity of the video displayed on the screen 120m are brought close to each other, and the brightness and chromaticity are made uniform on the multi-screen 144.

  In the adjustment in use, the luminance and chromaticity change from the target luminance and the target chromaticity in the images displayed on the screens 120m and 120s, respectively, but the luminance and chromaticity in the image displayed on the screen 120s respectively. The brightness and chromaticity in the video displayed on the screen 120m are brought close to each other, and the brightness and chromaticity are made uniform in the multi-screen 144.

4 Initial Adjustment For the master device 104m, when the master device 104m is manufactured in the factory, red, green and blue images are displayed on the screen 120m, and the displayed red, green and Tristimulus value data SCRm including red stimulus values X, Y, and Z, green stimulus values X, Y, and Z, and blue stimulus values X, Y, and Z indicating the colors of the blue image, respectively, is measured. The measured tristimulus value data SCRm is stored in the storage device 126m. The tristimulus value data SCRm indicates display characteristics of the master device 104m such as a color range (hereinafter referred to as “color reproduction range of the master device 104m”) that can be displayed on the screen 120m by the master device 104m.

  Regarding the slave device 104s, when the slave device 104s is manufactured in the factory, red, green, and blue images are displayed on the screen 120s, and the displayed red, green, and blue images are displayed by a measuring instrument such as a color analyzer. Tristimulus value data SCRs including red stimulus values X, Y and Z indicating the colors, green stimulus values X, Y and Z and blue stimulus values X, Y and Z, respectively, are measured. The measured tristimulus value data SCRs are stored in the storage device 126s. The tristimulus value data SCRs indicates display characteristics of the slave device 104s such as a color range that the slave device 104s can display on the screen 120s (hereinafter referred to as “color reproduction range of the slave device 104s”).

  The processing circuit 128m acquires the tristimulus value data SCRm stored in the storage device 126m, and communicates the tristimulus value data SCRs stored in the storage device 126s between the processing circuit 124m and the processing circuit 124s. Get using.

  The processing circuit 128m calculates a common color reproduction range from the acquired tristimulus value data SCRm and SCRs, and calculates target luminance and target chromaticity in the multi-screen 144 from the calculated common color reproduction range. The common color reproduction range is a range in which the color reproduction range of the master device 104m and the color reproduction range of the slave device 104s overlap. The target luminance and the target chromaticity are the luminance and chromaticity at the positions of main vertices of the contour lines surrounding the common color reproduction range in the xy chromaticity diagram, respectively. A method for calculating the target luminance and the target chromaticity is also described in Japanese Patent No. 4823660. The method for calculating the target luminance and the target chromaticity may be changed.

  Based on the calculated target luminance and target chromaticity and tristimulus value data SCRm, the processing circuit 124m corrects the input video signal so that the target luminance and target chromaticity are obtained in the video displayed on the screen 120m. Then, the corrected video signal is input to the DMD 116m.

  The processing circuit 124s acquires the calculated target luminance and target chromaticity using communication between the processing circuit 124m and the processing circuit 124s, and based on the acquired target luminance and target chromaticity and the tristimulus values SCRs. Then, the input video signal is corrected so that the target luminance and the target chromaticity can be obtained in the video displayed on the screen 120s, and the corrected video signal is input to the DMD 116s.

  Thereby, when the use of the multi-screen display device 100 is started, the luminance and chromaticity in the images displayed on the screens 120m and 120s are brought close to the target luminance and the target chromaticity, respectively, and are displayed on the screen 120s. The luminance and chromaticity in the video are brought close to the luminance and chromaticity in the video displayed on the screen 120m, respectively, and the luminance and chromaticity are uniform in the video displayed on the multi-screen 144.

  The initial adjustment may be performed by other methods.

5 Adjustment in use 5.1 Necessity of adjustment in use When the use of the multi-screen display device 100 is started by the initial adjustment, the brightness and chromaticity in the images displayed on the screens 120m and 120s are changed. The brightness and chromaticity in the video displayed on the screen 120s are brought close to the target brightness and chromaticity, respectively, and the brightness and chromaticity in the video displayed on the screen 120m are brought close to each other. It becomes uniform.

  However, the luminance of each of the red light 148m, the green light 150m, the blue light 152m, the red light 148s, the green light 150s, and the blue light 152s decreases as the usage time of the multi-screen display device 100 increases. For this reason, in the video displayed on each of the screens 120m and 120s, the luminance decreases from the target luminance and the chromaticity changes from the target chromaticity as the usage time increases. For this reason, the luminance and chromaticity of the video displayed on the multi-screen 144 may be uneven.

  Therefore, even if the adjustment in use is performed and the luminance and chromaticity are changed from the target luminance and the target chromaticity in the images displayed on the screens 120m and 120s, the video displayed on the screen 120s. The luminance and chromaticity in the image are brought close to the luminance and chromaticity in the image displayed on the screen 120m, respectively, and the luminance and chromaticity in the image displayed on the multi-screen 144 are made uniform. Adjustment in use is preferably performed at all times while the multi-screen display device 100 is being used.

5.2 Minimum Maintenance Rate FIG. 3 is a graph showing an example of a change in luminance maintenance rate depending on usage time in the master device.

  In FIG. 3, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. FIG. 3 shows a life curve 166m of the red LED 132m, a life curve 168m of the green LED 134m, and a life curve 170m of the blue LED 136m when the same current I is applied to each of the red LED 132m, the green LED 134m, and the blue LED 136m. The lifetime curves 166m, 168m, and 170m indicate changes in the luminance maintenance ratio Rm of the red light 148m, the luminance maintenance ratio Gm of the green light 150m, and the luminance maintenance ratio Bm of the blue light 152m, respectively, depending on usage time. The luminance maintenance rates Rm, Gm, and Bm are ratios of the luminance values in use of the red light 148m, the green light 150m, and the blue light 152m to the initial luminance values of the red light 148m, the green light 150m, and the blue light 152m, respectively. The initial luminance values of the red light 148m, the green light 150m, and the blue light 152m are measured when the use of the multi-screen display device 100 is started. The life curve 166m is obtained when the duty ratio DC of the drive signal is 25% and the junction temperature Tj is 85 ° C. The life curve 168m is obtained when the duty ratio DC of the drive signal is 50% and the junction temperature Tj is 105 ° C. The life curve 170m is obtained when the duty ratio DC of the drive signal is 25% and the junction temperature Tj is 125 ° C. The junction temperature Tj is the temperature of the light emitting layer of the LED chip.

  FIG. 4 is a graph illustrating an example of a change in the luminance maintenance rate according to usage time in the slave device.

  In FIG. 4, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. FIG. 4 shows a life curve 166s of the red LED 132s, a life curve 168s of the green LED 134s, and a life curve 170s of the blue LED 136s when the same current I is supplied to each of the red LED 132s, the green LED 134s, and the blue LED 136s. The lifetime curves 166s, 168s, and 170s show changes in usage time of the luminance maintenance rate Rs of the red light 148s, the luminance maintenance rate Gs of the green light 150s, and the luminance maintenance rate Bs of the blue light 152s, respectively. The luminance maintenance rates Rs, Gs, and Bs are ratios of the luminance values in use of the red light 148s, the green light 150s, and the blue light 152s to the initial luminance values of the red light 148s, the green light 150s, and the blue light 152s, respectively. The initial luminance values of the red light 148 s, the green light 150 s, and the blue light 152 s are measured when the use of the multi-screen display device 100 is started. The life curve 166 s is obtained when the duty ratio DC of the drive signal is 25% and the junction temperature Tj is 60 ° C. The lifetime curve 168s is obtained when the duty ratio DC of the drive signal is 50% and the junction temperature Tj is 125 ° C. The life curve 170 s is obtained when the duty ratio DC of the drive signal is 25% and the junction temperature Tj is 105 ° C.

  Generally speaking, the lifetime of the red LED used as the light source in the projection display apparatus is shorter than that of each of the green LED and the blue LED used as the light source in the projection display apparatus. Therefore, as shown in FIG. 3, the lifetime of the red LED 132m is shorter than the lifetime of each of the green LED 134m and the blue LED 136m, and the luminance maintenance rate Rm decreases more rapidly than each of the luminance maintenance rates Gm and Bm. Further, as shown in FIG. 4, the lifetime of the red LED 132s is shorter than the lifetime of each of the green LED 134s and the blue LED 136s, and the luminance maintenance rate Rs decreases more rapidly than each of the luminance maintenance rates Gs and Bs.

  Generally speaking, the lifetime of an LED becomes shorter as the junction temperature Tj increases. Therefore, as shown in FIGS. 3 and 4, the lifetime of the red LED 132m having a junction temperature Tj of 85 ° C. is shorter than that of the red LED 132s having a junction temperature Tj of 60 ° C., and the luminance maintenance ratio Rm It decreases rapidly from the rate Rs. Moreover, the lifetime of the green LED 134s whose junction temperature Tj is 125 ° C. is shorter than the lifetime of the green LED 134m whose junction temperature Tj is 105 ° C., and the luminance maintenance rate Gs decreases more rapidly than the luminance maintenance rate Gm. Furthermore, the lifetime of the blue LED 136m with a junction temperature Tj of 125 ° C. is shorter than the lifetime of the blue LED 136s with a junction temperature Tj of 105 ° C., and the luminance maintenance rate Bm decreases more rapidly than the luminance maintenance rate Bs.

  The luminance values of the red light 148m, the green light 150m and the blue light 152m are indicated by the stimulation values Y of the red light 148m, the green light 150m and the blue light 152m included in the tristimulus value data DSTm, respectively. The luminance values of 150 s and blue light 152 s are indicated by stimulation values Y of red light 148 s, green light 150 s, and blue light 152 s included in the tristimulus value data DSTs, respectively. Accordingly, the life curves 166m, 168m, and 170m show changes in the stimulus values Y of the red light 148m, the green light 150m, and the blue light 152m included in the tristimulus value data DSTm, respectively, and the life curves 166s, 168s, and 170s. Indicates changes in the stimulation value Y of the red light 148 s, the green light 150 s, and the blue light 152 s included in the tristimulus value data DSTs, depending on the usage time.

  In each of the red light 148m, the green light 150m, and the blue light 152m, the rate of change indicating the change of the stimulus value Y included in the tristimulus value data DSTm with the usage time is the stimulus value X and the stimulus value X included in the tristimulus value data DSTm. It is almost the same as the rate of change indicating the change of each Z with the usage time. Therefore, in each of the red light 148m, the green light 150m, and the blue light 152m, the ratio of the stimulus values X, Y, and Z included in the tristimulus value data DSTm hardly changes depending on the use time. This indicates that the chromaticity of each of the red light 148m, the green light 150m, and the blue light 152m hardly changes depending on the use time. The chromaticity of each of the red light 148 s, the green light 150 s, and the blue light 152 s hardly changes depending on the usage time.

  FIG. 5 is a graph showing an example of a change in the luminance maintenance ratio that is the minimum maintenance ratio depending on the usage time.

  In FIG. 5, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. The life curve 174 shown in FIG. 5 coincides with the life curve 166m that decreases most rapidly among the life curves 166m shown in FIG. 3 and the life curve 166s shown in FIG. 4, and the red light 148m and 148s. The change by the usage time of the brightness | luminance maintenance factor Rm used as the minimum maintenance factor Rmin is shown. The life curve 176 shown in FIG. 5 coincides with the life curve 168s that decreases most rapidly among the life curves 168m shown in FIG. 3 and the life curve 168s shown in FIG. The change by the usage time of the brightness | luminance maintenance factor Gs used as the minimum maintenance factor Gmin is shown. The life curve 178 shown in FIG. 5 coincides with the life curve 170 m that decreases most rapidly among the life curves 170 m shown in FIG. 3 and the life curves 170 s shown in FIG. The change with the usage time of the brightness | luminance maintenance factor Bm used as the minimum maintenance factor Bmin is shown.

  The brightness of each of the red light 148m, the green light 150m, the blue light 152m, the red light 148s, the green light 150s, and the blue light 152s is such that the brightness value of each light is changed to the initial brightness value of each light. Although it can be controlled to be lower than the product of the brightness maintenance factor, the brightness value of each light is controlled to be higher than the initial brightness value of each light multiplied by the brightness maintenance factor of each light. It is not possible.

  Therefore, the minimum maintenance rate Rmin, which is the lowest value of the luminance maintenance rates Rm and Rs, is acquired, and the luminance values of the red light 148m and 148s are set to the initial luminance values of the red light 148m and 148s, respectively. Control must be done so that it is less than or equal to the product multiplied. Further, the minimum maintenance rate Gmin, which is the lowest value of the luminance maintenance rates Gm and Gs, is acquired, and the luminance values of the green light 150 m and 150 s are multiplied by the initial luminance values of the green light 150 m and 150 s, respectively, by the minimum maintenance rate Gmin. Control must be done to be less than Further, the lowest maintenance rate Bmin, which is the lowest value of the luminance maintenance rates Bm and Bs, is acquired, and the luminance values of the blue light 152m and 152s are multiplied by the initial luminance values of the blue light 152m and 152s, respectively, by the minimum maintenance rate Bmin. Control must be done to be less than For example, control must be performed so that the luminance values of red light 148m and 148s are less than or equal to the initial luminance values of red light 148m and 148s multiplied by the minimum maintenance factor Rmin indicated by life curve 174, respectively. . Control must be performed so that the luminance values of the green light 150 m and 150 s are equal to or less than the initial luminance value of the green light 150 m and 150 s multiplied by the minimum maintenance rate Gmin indicated by the life curve 176. Furthermore, control must be performed so that the luminance values of the blue light 152m and 152s are equal to or less than the initial luminance value of the blue light 152m and 152s multiplied by the minimum maintenance rate Bmin indicated by the lifetime curve 178.

  When the control is performed in this way, the luminances of the red light 148s, the green light 150s, and the blue light 152s can be controlled in the same manner as the luminances of the red light 148m, the green light 150m, and the blue light 152m, respectively. For this reason, the brightness | luminance and chromaticity in the image | video displayed on the screen 120s can be changed similarly to the brightness | luminance and chromaticity in the image | video displayed on the screen 120s, respectively. Therefore, it is possible to suppress the luminance and chromaticity from becoming uneven in the video displayed on the multi-screen 144.

  However, when the control is performed in this way, the ratio of the luminance of the red light 148m, the luminance of the green light 150m, and the luminance of the blue light 152m changes as the usage time becomes longer, and in the video displayed on the screen 120m The chromaticity of white changes. Further, as the usage time becomes longer, the ratio of the luminance of the red light 148s, the luminance of the green light 150s, and the luminance of the blue light 152s changes, and the white chromaticity changes in the image displayed on the screen 120s.

  Therefore, until the minimum value among the minimum maintenance rates Rmin, Gmin, and Bmin is specified and the usage time reaches a certain time, red light 148m, green light 150m, blue light 152m, red light 148s, green light 150s and The luminance of each light that is each of the blue light 152s is controlled such that the luminance value of each light is obtained by multiplying the initial luminance value of each light by the specified minimum value.

  When the control is performed in this way, until the usage time reaches a certain amount of time, the control is similarly performed based on the lowest common brightness of the red light 148m, the green light 150m, and the blue light 152m. For this reason, it is suppressed that the ratio of the brightness | luminance of red light 148m, the brightness | luminance of green light 150m, and the brightness | luminance of blue light 152m changes as use time becomes long, and as use time becomes long in the image | video displayed on the screen 120m. The change in chromaticity is suppressed. Further, until the usage time reaches a certain time, the luminance of each of the red light 148 s, the green light 150 s, and the blue light 152 s is controlled based on the lowest common value. For this reason, it is suppressed that the ratio of the brightness | luminance of red light 148s, the brightness | luminance of green light 150s, and the brightness | luminance of blue light 152s changes as use time becomes long, and use time becomes long in the image | video displayed on the screen 120s. The change in chromaticity is suppressed.

5.3 Acquisition of Minimum Maintenance Rate in Master Device FIG. 6 is a flowchart showing a flow of acquisition of the minimum maintenance rate in the master device.

  In step S101 shown in FIG. 6, the processing circuit 124m calculates the luminance maintenance rates Rm, Gm, and Bm from the initial tristimulus value data DSTm and the in-use tristimulus value data DSTm, and transmits them to the processing circuit 128m. To do. Thereby, the processing circuit 128m acquires the luminance maintenance rates Rm, Gm, and Bm. Transmission of the luminance maintenance rates Rm, Gm, and Bm is always performed.

  In subsequent step S102, the processing circuit 128m receives the luminance maintenance rates Rs, Gs, and Bs from the processing circuit 124s by using communication between the processing circuit 124m and the processing circuit 124s. As a result, the processing circuit 128m acquires the luminance maintenance rates Rs, Gs, and Bs.

  In subsequent step S103, the processing circuit 128m calculates the minimum maintenance rate Rmin from the acquired luminance maintenance rates Rm and Rs, calculates the minimum maintenance rate Gmin from the acquired luminance maintenance rates Gm and Gs, and acquires the acquired luminance maintenance rate. The minimum maintenance ratio Bmin is calculated from Bm and Bs.

  In subsequent step S104, the processing circuit 128m transmits the calculated minimum maintenance rates Rmin, Gmin, and Bmin to the processing circuit 124s using communication between the processing circuit 124m and the processing circuit 124s.

5.4 Acquisition of Minimum Maintenance Rate in Slave Device FIG. 7 is a flowchart showing a flow of acquisition of the minimum maintenance rate in the slave device.

  In step S111 shown in FIG. 7, the processing circuit 124s calculates the luminance maintenance rates Rs, Gs, and Bs from the initial tristimulus value data DSTs and the in-use tristimulus value data DSTs.

  In the subsequent step S112, the processing circuit 124s transmits the luminance maintenance rates Rs, Gs, and Bs to the processing circuit 128m using communication between the processing circuit 124m and the processing circuit 124s. Transmission of the luminance maintenance rates Rs, Gs, and Bs is always performed.

  In subsequent step S113, the processing circuit 124s receives the minimum maintenance ratios Rmin, Gmin, and Bmin from the processing circuit 128m by using communication between the processing circuit 124m and the processing circuit 124s.

5.5 Brightness Control in Master and Slave Devices FIG. 8 is a flowchart showing the flow of brightness control in the master device.

  FIG. 9 is a graph illustrating an example of a change in the luminance maintenance rate depending on the usage time after the luminance control is performed.

  In FIG. 9, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. Curves 188, 190, and 192 after control shown in FIG. 9 show changes in the luminance maintenance ratios of the red light 148m, the green light 150m, and the blue light 152m with the use time after the luminance is controlled, respectively. The change by the usage time of the brightness | luminance maintenance factor of red light 148s, green light 150s, and blue light 152s after this control is performed is shown.

  In step S121 shown in FIG. 8, the processing circuit 128m sets a threshold value Lvth common to the minimum maintenance rates Rmin, Gmin, and Bmin. Each of FIG. 5 and FIG. 9 shows a threshold line 184 indicating the threshold Lvth when the threshold Lvth is 90%.

  In the subsequent step S122, if the processing circuit 124m determines that any of the three minimum maintenance rates Rmin, Gmin, and Bmin has fallen below the threshold Lvth, the process proceeds to step S124. If not, the process is performed. Proceed to step S123.

  In step S123, the processing circuit 124m specifies the lowest value among the minimum maintenance rates Rmin, Gmin, and Bmin, and the luminance values of the on-light 160m of the red light 148m, the green light 150m, and the blue light 152m are respectively red light 148m. Identifies the brightness of red light 148m, green light 150m and blue light 152m on light 160m so that the initial brightness value of green light 150m and blue light 152m on initial light 160m is multiplied by the specified minimum value. Control is performed on the basis of the lowest value, and the process proceeds again to step S122. The brightness is controlled by setting the gain when the video signal is amplified. When the changes in the minimum maintenance rates Rmin, Gmin and Bmin depending on the usage time are shown by life curves 174, 176 and 178 shown in FIG. 5, respectively, the minimum maintenance rate Rmin is the lowest of the minimum maintenance rates Rmin, Gmin and Bmin. Since the brightness of each of the red light 148m, the green light 150m, and the blue light 152m is controlled based on the minimum maintenance rate Rmin, before the use time T1 when the brightness maintenance rate Rmin falls below the threshold value Lvth, FIG. As shown in FIG. 9 and FIG. 9, each of the post-control curves 188, 190, and 192 matches the life curve 174.

  Before the use time T1 when the minimum maintenance rates Rmin, Gmin, and Bmin include the minimum maintenance rate below the threshold value Lvth by steps S122 and S123, the luminances of the red light 148m, the green light 150m, and the blue light 152m are common. Control based on the lowest value. Thereby, before the use time T1, the ratio of the luminance of the red light 148m, the luminance of the green light 150m, and the luminance of the blue light 152m hardly changes, and the chromaticity of white is almost constant in the image displayed on the screen 120m. Maintained.

  In step S124, the processing circuit 124m advances the process to step S125 for the first color whose minimum maintenance rate is lower than the threshold value Lvth, and the second color and the third color whose minimum maintenance rate is not lower than the threshold value Lvth. For color, the process proceeds to step S126. When the changes in the minimum maintenance rates Rmin, Gmin and Bmin due to usage time are shown by the life curves 174, 176 and 178 shown in FIG. 5, respectively, the first color is red and the second color is green The third color is blue.

  In step S125, the processing circuit 124m determines that the luminance value of the first color light on light 160m is the initial luminance value of the first color light on light 160m, and the minimum maintenance ratio of the first color light. The luminance of the on-light 160m of the first color light is controlled based on the minimum maintenance rate of the first color light so as to be multiplied by. In step S126, the processing circuit 124m causes the brightness value of the on-light 160m of the second color light to be obtained by multiplying the initial brightness value of the on-light 160m of the second color light by the threshold Lvth. The brightness of the on light 160m of the second color light is controlled based on the threshold value Lvth, and the brightness value of the on light 160m of the third color light is the initial brightness value of the on light 160m of the third color light. Based on the threshold value Lvth, the brightness of the ON light 160m of the third color light is controlled so as to be multiplied by the threshold value Lvth. When changes in the minimum maintenance rates Rmin, Gmin, and Bmin depending on the usage time are shown by life curves 174, 176, and 178 shown in FIG. 5, respectively, the luminance maintenance rate Gmin falls below the threshold value Lvth after the usage time T1. Before the use time T2, the luminance of the red light 148m is controlled based on the minimum maintenance ratio of the red light, and the luminance of each of the green light 150m and the blue light 152m is controlled based on the threshold value Lvth. As shown in FIG. 9, the post-control curve 188 matches the life curve 174, and each of the post-control curves 190 and 192 matches the threshold line 184.

  In subsequent step S127, if the processing circuit 124m determines that any of the remaining two minimum maintenance ratios has fallen below the threshold Lvth, the process proceeds to step S128. If not, the process is performed again in step S126. Proceed to

  In step S128, the processing circuit 124m advances the process to step S129 for the second color whose minimum maintenance rate is lower than the threshold value Lvth, and processes the third color whose minimum maintenance rate is not lower than the threshold value Lvth. Proceed to step S130.

  In step S129, the processing circuit 124m determines that the luminance value of the second color light ON light 160m is the initial luminance value of the second color light ON light 160m and the minimum maintenance ratio of the second color light. The brightness of the on-light 160m of the second color light is controlled based on the minimum maintenance rate of the second color light so as to be multiplied by. In step S130, the processing circuit 124m causes the luminance value of the on-light 160m of the third color light to be obtained by multiplying the initial luminance value of the on-light 160m of the third color light by the threshold Lvth. The luminance of the on light 160m of the third color light is controlled based on the threshold value Lvth. When changes in the minimum maintenance rates Rmin, Gmin, and Bmin depending on the usage time are shown by life curves 174, 176, and 178 shown in FIG. 5, respectively, the luminance maintenance rate Bmin falls below the threshold value Lvth after the usage time T2. Before the use time T3, the luminance of the green light 150m is controlled based on the minimum maintenance ratio of the green light, and the luminance of the blue light 152m is controlled based on the threshold value Lvth, so as shown in FIGS. In addition, the post-control curve 190 matches the life curve 176, and the post-control curve 192 matches the threshold line 184. The state where the post-control curve 188 matches the life curve 174 is also maintained.

  In the subsequent step S131, if the processing circuit 124m determines that the remaining one minimum maintenance ratio has fallen below the threshold value Lvth, the process proceeds to step S132, and if not, the process proceeds to step S130 again.

  In step S132, the processing circuit 124m multiplies the initial luminance of the third color light on-light 160m by the third color light on-light 160m by the minimum maintenance rate of the third color light. Therefore, the ON light 160m of the third color light is controlled based on the minimum maintenance rate of the third color light. When the changes in the minimum maintenance rates Rmin, Gmin, and Bmin depending on the use time are shown by the life curves 174, 176, and 178 shown in FIG. 5, respectively, after the use time T3, the luminance of the blue light 152m becomes blue light. Since the control is based on the minimum maintenance rate Bm, the post-control curve 192 matches the life curve 178 as shown in FIGS. The state where the post-control curves 188 and 190 coincide with the life curves 174 and 176, respectively, is also maintained.

  From step S124 to S132, every time light having a minimum maintenance ratio lower than the threshold value is generated, control of the luminance of the generated light is started based on the minimum maintenance ratio of the light, and the minimum maintenance level that does not fall below the threshold value Lvth The brightness of the light having the rate is controlled based on the threshold value Lvth. For this reason, when the minimum maintenance rates Rmin, Gmin, and Bmin include the minimum maintenance rate below the threshold Lvth, the brightness of light having the minimum maintenance rate below the threshold is controlled based on the minimum maintenance rate of the light. When the minimum maintenance rates Rmin, Gmin, and Bmin further include a minimum maintenance rate that does not fall below the threshold value Lvth, the luminance of light having the minimum maintenance rate that does not fall below the threshold value Lvth is controlled based on the threshold value Lvth.

  After the use time T1 in which the minimum maintenance rates Rmin, Gmin, and Bmin include the minimum maintenance rate below the threshold value Lvth through steps S124 to S132, the luminance of light having the minimum maintenance rate below the threshold value Lvth is Is controlled based on the minimum maintenance ratio, but the luminance of light having the minimum maintenance ratio not lower than the threshold value Lvth is controlled based on the threshold value Lvth. For this reason, it is suppressed that the brightness | luminance of the light which has the minimum maintenance factor which is not less than threshold value Lvth falls significantly, and it suppresses that a brightness | luminance falls largely in the image | video displayed on the screen 120m.

  The description of the brightness control in the master device 104m is as follows: the master device 104m, the processing circuit 124m, the screen 120m, the red light 148m, the green light 150m, and the blue light 152m are respectively the slave device 104s, the processing circuit 124s, the screen 120s, and the red. The explanation of the brightness control in the slave device 104s is made by reading the light 148s, the green light 150s, and the blue light 152s. In the slave device 104s, the threshold Lvth is set in the processing circuit 124s.

  When the above-described brightness control is performed in each of the master device 104m and the slave device 104s, the threshold value Lvth or the minimum value of the minimum maintenance rates Rmin, Gmin, and Bmin in which the red light 148m and 148s have the same brightness. The brightness of each of the green lights 150m and 150s is controlled based on the common threshold Lvth or the lowest of the minimum maintenance rates Rmin, Gmin and Bmin, and the brightness of each of the blue lights 152m and 152s is controlled. Control is performed based on a common threshold Lvth or a minimum value among minimum maintenance rates Rmin, Gmin, and Bmin. For this reason, the luminance and chromaticity in the image displayed on the screen 120s change in the same manner as the luminance and chromaticity in the image displayed on the screen 120m, respectively. Therefore, the luminance and chromaticity are suppressed from becoming non-uniform as the usage time increases in the video displayed on the multi-screen 144.

5.6 Contrast with Prior Art According to the multi-screen display device 100 of this embodiment, the chromaticity of white in the images displayed on the screens 120m and 120s has a white chromaticity until the usage time reaches a certain time. It is maintained almost constant. Further, after the usage time reaches a certain time, the ratio of the luminance of the red light 148m, the luminance of the green light 150m, and the luminance of the blue light 152m is allowed to change, and the luminance of the red light 148s and the green light 150s. And the ratio of the luminance of the blue light 152s are allowed to change, the white chromaticity gradually changes in the images displayed on the screens 120m and 120s, respectively. However, after the usage time reaches a certain amount of time, in each of the master device 104m and the slave device 104s, the color light having a relatively high luminance maintenance rate has a relatively low luminance maintenance rate. It does not follow the brightness of the light and does not decrease greatly. For this reason, the brightness of the video displayed on each of the screens 120m and 120s is not greatly reduced, and the brightness of the video displayed on the multi-screen 144 is not greatly reduced, and the gradation of the video displayed on the multi-screen 144 is increased. It can be enriched.

  FIG. 10 is a graph showing an example of a change in the luminance maintenance rate according to the usage time after the luminance control is performed in the multi-screen display device using the technique described in Japanese Patent Laid-Open No. 10-90645.

  In FIG. 10, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. Curves 196, 198, and 200 after control shown in FIG. 10 indicate changes in the luminance maintenance ratios of red light, green light, and blue light depending on usage time after the luminance is controlled, respectively.

  In the multi-screen display device, the chromaticity of white is always kept constant in the video displayed on each of the screen provided in the master device and the screen provided in the slave device. However, in each of the master device and the slave device, the luminance of light having a relatively high luminance maintenance rate is significantly reduced following the luminance of light having a relatively low luminance maintenance rate. For example, as shown in FIG. 10, each of the post-control curves 198 and 200 matches the lifetime curve 174, and the luminance of each of the green light and the blue light follows the luminance of the red light. For this reason, the luminance of the video displayed on each of the screen provided in the master device and the screen provided in the slave device is greatly reduced, and the luminance is greatly reduced in the video displayed on the multi-screen.

  Due to such a difference, according to the multi-screen display device 100 of this embodiment, when a video that is based on the primary colors such as the communication system diagram and the operation system diagram and whose color reproducibility is not important is displayed on the multi-screen 144. In the video displayed on the multi-screen 144, the luminance and chromaticity are suppressed from becoming non-uniform, and the time until the luminance is reduced to a specific luminance in the video displayed on each of the screens 120m and 120s, For example, the time until the luminance becomes half of the initial luminance increases. For this reason, the number of times of exchanging the master device 104m or the slave device 104s decreases, the number of times of exchanging only the light source 108m or 108s decreases, and the cost required for maintaining the multi-screen display device 100 decreases.

6 Three or more projection image display devices When two projection image display devices are replaced with three or more projection image display devices, the brightness of red light calculated in the first projection image display device A first process is performed to set the lowest value of the maintenance ratio and the luminance maintenance ratio of the red light calculated in the second projection display apparatus to the lowest maintenance ratio of the first red light. The i-th process of setting the minimum value of the minimum maintenance ratio of red light and the brightness maintenance ratio of red light calculated in the (i + 1) -th projection image display apparatus to i is the minimum maintenance ratio of red light. 2,..., N−1, and the calculated minimum maintenance rate of the (n−1) th red light is acquired as the minimum maintenance rate of red light that is the basis of control. The minimum maintenance rate of green light and the minimum maintenance rate of blue light are obtained in the same manner.

7 Threshold When the threshold Lvth is 90% as shown in FIGS. 5 and 9, each of the minimum maintenance rates Rmin, Gmin, and Bmin falls below the threshold Lvth before the usage time reaches 100,000 hours. . For example, the minimum maintenance rate Rmin falls below the threshold Lvth when the usage time reaches 1,700 hours, and the minimum maintenance rate Gmin falls below the threshold Lvth when the usage time reaches 10,500 hours. Falls below the threshold Lvth when the usage time reaches 65,000 hours.

  FIG. 11 is a graph illustrating an example of a change in the luminance maintenance ratio that is the minimum maintenance ratio depending on the usage time.

  In FIG. 11, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. The life curves 204, 206 and 208 shown in FIG. 11 are the same as the life curves 174, 176 and 178 shown in FIG. 5, respectively. FIG. 11 shows a threshold line 212 indicating the threshold Lvth when the threshold Lvth is 60%.

  The threshold value Lvth may be other than 90%, or may be 60% as shown in FIG. As shown in FIG. 11, when the threshold value Lvth is 60%, the minimum maintenance rate Rmin is lower than the threshold value Lvth when the usage time reaches 25,000 hours. However, each of the minimum maintenance rates Gmin and Bmin does not fall below the threshold Lvth before the usage time reaches 100,000 hours.

  FIG. 12 is a graph illustrating an example of a change in the luminance maintenance rate depending on the usage time after the luminance control is performed.

  In FIG. 12, the horizontal axis represents the usage time, and the vertical axis represents the luminance maintenance rate. The post-control curves 216, 218, and 220 shown in FIG. 12 indicate the luminance maintenance rates of the red light 148m, the green light 150m, and the blue light 152m after the luminance is controlled when the threshold value Lvth is 60%. The change with the use time of is shown.

  When the threshold Lvth is 60%, as shown in FIG. 12, before the usage time reaches 25,000 hours, the luminance of each of the red light 148m, the green light 150m, and the blue light 152m is red light 148m and It is controlled based on the minimum maintenance rate of 148s. After the usage time reaches 25,000 hours, the luminance of the red light 148m is controlled based on the minimum maintenance ratio of the red light 148m and 148s, and the luminance of each of the green light 150m and the blue light 152m is the threshold value Lvth. Controlled based on Therefore, the usage time for maintaining the white chromaticity substantially constant in the image displayed on the screen 120m is extended to 25,000 hours. In addition, after the usage time reaches 25,000 hours, the luminance of the red light 148m decreases, so the white chromaticity gradually changes in the image displayed on the screen 120m, but the green light 150m and the blue light Since the brightness of each of the lights 152m does not greatly decrease, the brightness of the video displayed on the screen 120m does not decrease significantly, and finally the case described in Japanese Patent Laid-Open No. 10-90645 is used. High brightness can be obtained. The same can be said for the screen 120s.

  When the threshold Lvth is 0%, the white chromaticity is always displayed in the image displayed on the screen 120m until the red LED 132m, the green LED 134m, and the blue LED m reach the end of their life after the use of the multi-screen display device 100 is started. Maintained constant. In addition, the white chromaticity is always maintained constant in the image displayed on the screen 120s until the red LED 132s, the green LED 134s, and the blue LED 136s reach the end of their life after the use of the multi-screen display device 100 is started. On the other hand, when the threshold Lvth is 100%, the white chromaticity in the image displayed on the screen 120m from the start of use of the multi-screen display device 100 until the red LED 132m, the green LED 134m, and the blue LED 136m reach the end of their lives. However, the luminance of each of the red light 148m, the green light 150m, and the blue light 152m is maintained at the highest luminance within the range where the luminance and chromaticity can be made uniform in the multi-screen 144. Further, the white chromaticity in the image displayed on the screen 120s gradually changes until the red LED 132s, the green LED 134s, and the blue LED 136s reach the end of life after the use of the multi-screen display device 100 is started, but the red light 148s. The brightness of each of the green light 150 s and the blue light 152 s is maintained at the highest brightness within a range where the brightness and chromaticity can be made uniform in the multi-screen 144. Therefore, by selecting the threshold value Lvth from 0% and 100%, a method for making the luminance and chromaticity uniform in the multi-screen 144 can be arbitrarily selected.

8 Accuracy of the three primary color light sensors In order for the adjustment after use to be properly performed, the three primary color light sensor 122m has a rate of change indicating the change of the stimulus values X, Y and Z included in the tristimulus value data DSTm depending on the usage time. Each of them must have an accuracy that is almost the same as the rate of change indicating the change of the stimulus values X, Y, and Z of the video displayed on the screen 120m depending on the usage time. In addition, the three primary color light sensor 122s has the rate of change indicating the change of the stimulus values X, Y, and Z included in the tristimulus value data DSTs depending on the usage time of the stimulus values X, Y, and Z of the image displayed on the screen 120s, respectively. It must have an accuracy that is almost the same as the rate of change indicating the change with time of use.

  When the initial adjustment based on the tristimulus value data SCRm and SCRs stored in advance is performed, the ratio of the stimulus values X, Y, and Z included in the tristimulus value data DSTm is displayed on the screen 120m. The ratio of the stimulus values X, Y and Z may be different, and for each of the stimulus values X, Y and Z, the stimulus value of red light 148m, the stimulus value of green light 150m and the blue light included in the tristimulus value data DSTm The stimulus value ratio of 152m is different from the stimulus value of the red image displayed on the screen 120m, the stimulus value of the green image displayed on the screen 120m, and the stimulus value of the blue image displayed on the screen 120m. Also good. Further, the ratio of the stimulus values X, Y and Z included in the tristimulus value data DSTs may be different from the ratio of the stimulus values X, Y and Z of the image displayed on the screen 120s, and the stimulus values X, Y and Z The ratio of the stimulation value of the red light 148s, the stimulation value of the green light 150s, and the stimulation value of the blue light 152s included in the tristimulus value data DSTs is the stimulation value of the red image displayed on the screen 120s, and the screen 120s. May be different from the ratio of the stimulus value of the green image displayed on the screen and the stimulus value of the blue image displayed on the screen 120s. In this case, the chromaticity values of the red light 148m, the green light 150m, and the blue light 152m derived from the tristimulus value data DSTm are different from the chromaticity values of the red, green, and blue images displayed on the screen 120m, respectively. The ratio of the luminance value of the red light 148m, the luminance value of the green light 150m, and the luminance value of the blue light 152m derived from the tristimulus value data DSTm is displayed on the screen 120m. This is different from the ratio of the luminance value of the green image and the luminance value of the blue image displayed on the screen 120m. Further, the chromaticity values of the red light 148 s, the green light 150 s, and the blue light 152 s derived from the tristimulus value data DSTs are different from the chromaticity values of the red, green, and blue images displayed on the screen 120 s, respectively. The ratio of the luminance value of the red light 148s derived from the value data DSTs, the luminance value of the green light 150s and the luminance value of the blue light 152s is the luminance value of the red video displayed on the screen 120s, and the green displayed on the screen 120s. And the ratio of the luminance value of the blue image displayed on the screen 120s.

  However, preferably, the three primary color light sensor 122m has a ratio of the stimulus values X, Y, and Z included in the tristimulus value data DSTm substantially the same as the ratio of the stimulus values X, Y, and Z of the image displayed on the screen 120m. Thus, for each of the stimulation values X, Y and Z, a red image in which the stimulation value of the red light 148m, the stimulation value of the green light 150m and the ratio of the blue light 152m included in the tristimulus value data DSTm is displayed on the screen 120m. And the ratio of the stimulation value of the green image displayed on the screen 120m and the stimulation value of the blue image displayed on the screen 120m. Further, the three primary color light sensor 122s has a ratio of stimulus values X, Y and Z included in the tristimulus value data DSTs substantially the same as a ratio of stimulus values X, Y and Z of the image displayed on the screen 120s. For each of the values X, Y, and Z, the stimulation value of the red video in which the stimulation value of the red light 148m, the stimulation value of the green light 150m, and the ratio of the blue light 152m included in the tristimulus value data DSTs is displayed on the screen 120s. The high accuracy of the degree is substantially the same as the ratio of the stimulus value of the green image displayed on the screen 120s and the stimulus value of the blue image displayed on the screen 120s. In this case, the chromaticity values of the red light 148m, the green light 150m, and the blue light 152m derived from the tristimulus value data DSTm are substantially the same as the chromaticity values of the red, green, and blue images displayed on the screen 120m, respectively. The ratio of the luminance value of the red light 148m, the luminance value of the green light 150m, and the luminance value of the blue light 152m derived from the tristimulus value data DSTm is respectively the luminance value of the red video displayed on the screen 120m, the screen The ratio of the luminance value of the green image displayed at 120 m and the luminance value of the blue image displayed on the screen 120 m is substantially the same. Further, the chromaticity values of the red light 148s, the green light 150s and the blue light 152s derived from the tristimulus value data DSTs are substantially the same as the chromaticity values of the red, green and blue images displayed on the screen 120s, The ratio of the luminance value of the red light 148s, the luminance value of the green light 150s and the luminance value of the blue light 152s derived from the tristimulus value data DSTs is displayed on the screen 120s, the luminance value of the red image displayed on the screen 120s. The ratio of the luminance value of the green image and the luminance value of the blue image displayed on the screen 120s is almost the same.

  When each of the three primary color light sensors 122m and 122s has such high accuracy, the stimulus values X, Y, and Z of the image displayed on the screen 120m are accurately identified from the tristimulus value data DSTm, and the tristimulus value data The stimulus values X, Y and Z of the video displayed on the screen 120s from the DSTs are specified with high accuracy. Therefore, initial adjustment may be performed based on the tristimulus value data DSTm and the tristimulus value data DSTs instead of the tristimulus value data SCRm and SCRs. That is, the tristimulus value data SCRm and SCRs need not be stored in the storage devices 126m and 126s, respectively, and the tristimulus value data SCRm and SCRs need not be measured for the master device 104m and the slave device 104s, respectively. Thereby, in the environment where the multi-screen display device 100 is actually installed, the initial adjustment is performed based on the stimulus values X, Y, and Z of the video displayed on each of the screens 120m and 120s. Accurately done. This advantage is particularly noticeable when the temperature of the environment where the multi-screen display device 100 is actually installed differs greatly from the temperature of the environment where the multi-screen display device 100 is manufactured, and the multi-screen display device 100 is actually installed. This is particularly significant when the junction temperature Tj in the environment in which the multi-screen display device 100 is manufactured differs greatly from the junction temperature Tj in the environment of the factory that manufactures the multi-screen display device 100. This is because the junction temperature Tj greatly affects the luminance of the light emitted from the LED.

  In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

  100 multi-screen display device, 104 m master projection type video display device (master device), 104 s slave projection type video display device (slave device), 110 m, 110 s dichroic mirror, 116 m, 116 s digital mirror device (DMD), 120 m, 120 s screen 122m, 122s Three primary color light sensors, 132m, 132s Red LED, 134m, 134s Green LED, 136m, 136s Blue LED, 140m, 140s Brightness control unit.

Claims (3)

m video display devices in which m is an integer greater than or equal to 2,
Each of the m video display devices includes:
Screens constituting a multi-screen;
1st to nth light emitting diodes, each emitting 1st to nth light having an integer of 3 or more and different colors,
A photosensor for measuring first to nth brightness values respectively indicating the brightness of the first to nth lights;
(1) The first to nth luminance maintenance in which the i-th luminance maintenance ratio is the ratio of the i-th luminance value to the i-th initial luminance value when i is each of 1 to n. (2) out of m i-th luminance maintenance ratios where the i-th minimum maintenance ratio is calculated in each of the m video display devices when i is each of 1 to n. (1) the first to n-th minimum maintenance rates are obtained, (3) a threshold value common to the first to n-th minimum maintenance rates is set, and (4) the first to When the minimum maintenance rate up to the nth does not include the minimum maintenance rate below the threshold, the brightness values indicating the brightness of the light emitted by the first to nth light emitting diodes are respectively 1st to nth. The initial luminance value is multiplied by the lowest value among the first to nth minimum maintenance rates. In this case, the brightness of the light emitted by the first to nth light emitting diodes is controlled, and (5) the first to nth minimum maintenance ratio includes the jth minimum maintenance ratio below the threshold. The light emitted by the jth light emitting diode so that the luminance value indicating the luminance of the light emitted by the jth light emitting diode is the jth initial luminance value multiplied by the jth minimum maintenance factor. A luminance value indicating the luminance of light emitted by the kth light-emitting diode when the first to nth minimum maintenance rates further include a kth minimum maintenance rate that does not fall below the threshold. A brightness control unit that controls the brightness of light emitted by the kth light emitting diode so that is multiplied by the threshold value to the kth initial brightness value;
A multi-screen display device comprising: The first to nth light emitting diodes are a red light emitting diode, a green light emitting diode, and a blue light emitting diode that emit red light, green light, and blue light, respectively.
The first to nth lights are the red light, the green light, and the blue light,
The multi-screen display device according to claim 1, further comprising a light combining optical system that combines the red light, the green light, and the blue light, and advances a common optical path for the red light, the green light, and the blue light. Each of the m video display devices includes:
A digital mirror that modulates each of the first to nth lights and generates on-light that is irradiated onto the screen and off-light that is received by the photosensor for each of the first to nth lights The device,
The multi-screen display device according to claim 1, further comprising:

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