JP2017204799A - Image projection apparatus and image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projection apparatus that keeps the brightness of a projected image constant without displaying a test pattern even when a correlation between a measured value of a light-quantity sensor and an amount of correction to a quantity of light changes during video projection.SOLUTION: An image projection apparatus that projects an image onto a projection surface, comprising: light source means; light modulation means that modulates light from the light source means; image processing means that generates an image signal to be input to the light modulation means; light-quantity measuring means that measures a quantity of light modulated by the light modulation means; contribution degree storage means that stores a contribution degree, which is a degree to which light from the light source means reaches the light-quantity measuring means via the light modulation means; update means that updates a contribution degree stored in the contribution degree storage means; and control means that controls the brightness of an image to be projected onto the projection surface, using the contribution degree.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image projection apparatus that controls light source means or light modulation means.

  An image projection apparatus such as a projector modulates light from a light source with a light modulation element and can project an arbitrary image on a projection surface. A light source used in the image projection apparatus includes a lamp and an LED, and a light modulation element includes a liquid crystal panel.

  However, it is known that in such an image projection apparatus, the brightness of the projected image changes due to the temporal change of the light source and the light modulation element. Therefore, in order to keep the brightness of the projection image constant, it is necessary to detect the brightness of the projection image and perform control to keep the brightness constant.

  In Patent Document 1, a reference light amount is corrected for each solid light source based on the sensor contribution stored for each solid light source, and lighting control is performed for each solid light source to suppress variations in the light amount emitted by each solid light source. A possible projection display apparatus is disclosed.

  Japanese Patent Laid-Open No. 2004-26883 discloses uneven display of an image by performing dimming control using dimming amounts and correction patterns associated with a plurality of luminance distribution patterns defined from the dynamic range and average luminance of image data. A reducing projector is disclosed.

Japanese Patent No. 5075452 Japanese Patent No. 4353151

  However, in the conventional technique disclosed in Patent Document 1 described above, when the sensor contribution of each solid light source is acquired, the solid light sources are sequentially turned on, and thus the sensor contribution cannot be acquired during video projection. Therefore, when a change in sensor contribution occurs during image projection, it is impossible to correctly suppress variations in the amount of light emitted by each solid-state light source. Further, the usability is lowered because the respective solid-state light sources are sequentially turned on.

  Also, with the prior art disclosed in Patent Document 2, correct correction cannot be performed when the correlation between the combination of image data patterns, the dimming amount, and the correction pattern changes.

  Therefore, an object of the present invention is to keep the brightness of the projected image constant without displaying the test pattern even when the correlation between the measurement value of the light amount sensor and the light amount correction amount changes during video projection. An object of the present invention is to provide an image projection apparatus that is made possible.

In order to achieve the above object, an image projection apparatus according to the present invention includes:
An image projection apparatus for projecting an image onto a projection surface, a light source means, a light modulation means for modulating light from the light source means, an image processing means for generating an image signal to be input to the light modulation means, A light amount measuring unit that measures the amount of light modulated by the light modulating unit, and a contribution degree storage unit that stores a contribution degree that is the degree to which the light from the light source unit reaches the light amount measuring unit via the light modulating unit. And updating means for updating the contribution degree stored in the contribution degree storage means, and control means for controlling the brightness of the image projected on the projection surface using the contribution degree.

  According to the present invention, it is possible to provide an image projection apparatus capable of keeping the brightness of a projected image constant even when the correlation between a measurement value of a light amount sensor and a light amount correction amount changes during video projection. Can do.

Schematic showing the configuration of Example 1 The figure which showed the display image area | region and contribution of Example 1. The figure which showed the display image area | region and contribution of Example 1. 7 is a flowchart illustrating a brightness control method for a projected image according to the first embodiment. The flowchart which showed the brightness correction method of Example 1. Schematic showing the configuration of Example 2 Schematic which shows the structure of the light source unit of Example 2. FIG. Schematic showing the configuration of Example 3 Schematic showing the configuration of the light sensor group The figure which showed the display image area and contribution of Example 3 Flowchart showing the brightness correction method of the third embodiment

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them.

[Example 1]
Hereinafter, the image projection apparatus according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic diagram showing the configuration of the projector 1 in this embodiment.

  According to the projector 1 of the present embodiment, an image projection apparatus that can keep the brightness of a projected image constant even when the correlation between the measurement value of the light amount sensor and the light amount correction amount changes during video projection. Can be provided.

  As shown in FIG. 1, the projector 1 (image projection apparatus) projects an image on a projection surface such as a screen. The projector 1 includes a lamp unit 10 (light source means), an illumination optical system 20, a liquid crystal panel unit 30 (light modulation means), an image processing engine 40 (image processing means), a light quantity sensor 50 (light quantity measurement means), and an EEPROM 60 (storage means). ) And a control circuit 70 (control means). In the present embodiment, the projector 1 will be described as a reflective liquid crystal projector, but the present invention can also be applied to other image projection apparatuses such as a DLP (Digital Light Processing) projector.

  The lamp unit 10 includes a light source driving circuit 11 and a lamp 12 (light source). The light source drive circuit 11 controls the power supplied to the lamp 12 in accordance with a control signal from the control circuit 70. The lamp 12 is driven by the light source driving circuit 11 and supplies light.

  The illumination optical system 20 includes a color separation optical system 21 and a color synthesis optical system 22. The color separation optical system separates the light from the lamp unit 10 (lamp 12) into RGB according to the wavelength, and separates the light separated into each color into the liquid crystal panel unit 30 for each RGB color (R: 30a, G: 30b, B: 30c). Lead to. The color synthesis optical system 22 synthesizes the RGB color lights modulated by the liquid crystal panel unit 30 and guides them to a projection optical system (not shown). Further, part of the light synthesized by the color synthesis optical system 22 is guided to the light quantity sensor 50. The light guided to the projection optical system is projected on the projection surface after the image formation position, the projection magnification, etc. are changed by the projection optical system.

  The liquid crystal panel unit 30 includes a panel drive circuit 31 (31a, 31b, 31c) and a liquid crystal panel 32 (32a, 32b, 32c), and modulates light according to a display image. The panel drive circuit 31 outputs drive signals to the liquid crystal panel 32 in accordance with the RGB color image signals IS output from the image processing engine 40. The liquid crystal panel 32 is driven by the panel drive circuit 31 and modulates the RGB color lights guided by the color separation optical system 21 and guides them to the color synthesis optical system 22.

  The image processing engine 40 (image processing means) includes an image conversion unit 41, an image analysis unit 42, and an image correction unit 43. The image conversion unit 41 converts the video signal VS into an image signal IS according to various setting values that change the display state of the image, such as brightness, contrast, or color adjustment. The video signal VS is an HDMI (registered trademark) signal, a DVI signal, an RGB signal, or a component signal output from the image supply device 100 (external device) such as a personal computer, a DVD player, a video deck, or a TV tuner. Various video signals.

  The various set values are values that change the display state of the image, such as brightness, contrast, γ, or color adjustment. Then, the image conversion unit 41 outputs the image signal IS to the image analysis unit 42 and the image correction unit 43. The image analysis unit 42 divides the image into a plurality of regions with respect to the image signal IS input from the image conversion unit 41, and analyzes the luminance distribution of the image from the histogram of each region. The luminance distribution analysis result of each region is output to the correction unit 71 of the control circuit 70. The image correction unit 43 performs image conversion on the image signal IS converted by the image conversion unit 41 in accordance with the correction value of the brightness of the image output from the correction unit 71 of the control circuit 70, and after image conversion The image signal IS is output to the panel drive circuit 31.

  As described above, the image processing engine 40 converts the external input signal VS into the image signal IS to be displayed on the liquid crystal panel unit 30 (30a, 30b, 30c), and outputs it to the panel drive circuit 31 (31a, 31b, 31c). To do.

  The light amount sensor 50 is configured to measure the amount of light modulated by the light modulation unit 20, and includes a photodiode 51, an ADC 52 (A / D converter), and a light reduction unit 53. The installation position of the light quantity sensor 50 is a position where the light from the lamp 12 modulated by the liquid crystal panel 32 can be measured. The photodiode 51 outputs a voltage corresponding to the light guided by the color synthesis optical system 22 to the ADC 52. The ADC 52 converts the input voltage into a digital signal and outputs it to the control circuit 70. The light reduction unit 53 is installed between the color synthesis optical system 22 and the photodiode 51 and reduces the amount of light incident on the photodiode 51.

  With such a configuration, the light quantity sensor 50 can output a value (voltage) corresponding to the brightness (light quantity) of the projection image of the projector 1. In this embodiment, the light amount sensor 50 adjusts the amount of light incident on the photodiode 51 using the dimming unit 53, but is not limited to this. When the photodiode 51 having a wide dynamic range is used in the light quantity sensor 50, it is not necessary to provide the light reduction unit 53.

  The light quantity sensor 50 is arranged so as to measure the light synthesized by the color synthesis optical system 22 and traveling in a direction different from the projection direction. However, the present invention is not limited to this. The light amount sensor 50 may be configured to measure the light amount by being arranged in the projection direction, or may measure the light amount of the projection surface. Thus, the installation location of the light quantity sensor 50 can be changed as appropriate.

  The EEPROM 60 includes a control information storage unit 61, a contribution degree storage unit 62, and a contribution degree update information storage unit 63, and inputs / outputs data according to instructions from the control circuit 70. The control information storage unit 61 stores information used in the control for keeping the brightness of the projection image constant performed by the control unit 71. The contribution degree storage unit 62 stores the contribution degree of each region of the display image divided by the image analysis unit 42 and the measurement value of the light amount sensor 50. Further, the contribution update information storage unit 63 stores a set of the luminance distribution analysis result of each region of the divided display image output from the image analysis unit 42 and the measurement value of the light quantity sensor 50.

  The control circuit 70 includes a correction unit 71, a determination unit 72, and an update unit 73, and performs control to keep the brightness of the projected image constant. The correction unit 71 determines the brightness of the projected image based on the luminance distribution analysis result of each area of the display image output from the image analysis unit 42, the contribution stored in the contribution storage unit 62, and the measurement value of the light quantity sensor 50. A control signal is output to the light source driving circuit 11 and the panel driving circuit 31 so that is constant. The determination unit 72 determines that the current contribution degree and the change in the contribution degree stored in the contribution degree storage unit 62 and that the information necessary for the update is prepared in the contribution degree update information storage unit 63 are sent to the update unit 73. An update start signal is output.

  When the update unit 73 detects the update start signal from the determination unit 72, the update unit 73 updates the contribution degree stored in the contribution degree storage unit 62 from the information stored in the contribution degree update information storage unit 63. Therefore, the correction unit 71 can control the brightness of the projected image to be constant by using the updated contribution even when the contribution changes.

  Next, the brightness control method of the projection image of the image projection apparatus according to the present embodiment will be described.

  In this embodiment, as shown in FIG. 2, the display image is divided into 3 × 3 9 areas, each area is referred to as an A to I area, and the degree of contribution corresponding to each area is a to i. Further, the contribution to the light amount sensor 50 due to factors other than the display image is j. Note that the number of divisions and the shape of the display image area are not limited thereto.

  With reference to FIGS. 3A to 3C, a data table used for image brightness correction stored in the EEPROM 60 will be described.

FIG. 3A is a data table showing the increment of the output value of the light quantity sensor 50 given by the luminance PB of one pixel (pixel), and is used when obtaining the increment EV _N of the output value of the light quantity sensor 50 for each region. .

  FIG. 3B stores the contribution n, which is the degree to which the light that has passed through each of the divided areas A to I of the display image reaches the light quantity sensor 50, and the measurement value j of the light quantity sensor 50 when displaying all black. This is a data table.

FIG. 3C is a data table showing the relationship between the correction value Bri of the image brightness and the amount of power change cPow _n supplied to the lamp 12, and is used when correcting the image brightness by light source control.

FIG. 3D is a data table showing the relationship between the image brightness correction value Bri and the γ value change amount cγ _n set in the liquid crystal panel 32. The image brightness is corrected by tone control. Used when.

  Next, a method for correcting a change in image brightness will be described with reference to FIG.

FIG. 4 is a flowchart showing an image brightness correction method according to this embodiment.
Each step of FIG. 4 is mainly executed based on a command from the correction unit 71 of the control circuit 70. The correction start condition is that correction is always performed while the lamp unit 10 of the projector 1 is in the lighting state, but is not limited thereto.

  When the control is started, first, in step S101, the measurement value of the light amount sensor 50 is acquired, and the difference between the measurement value and the reference value stored in the control information storage unit 61 is stored in the control information storage unit 61. It is determined whether the threshold value is exceeded. If the threshold value is exceeded, it is determined that a change in brightness has occurred, and the process proceeds to step S102. If it does not exceed the threshold, it is determined that no change in brightness has occurred, and the control is terminated.

  Next, in step S102, projection is performed using the luminance distribution of each area of the display image acquired by the image analysis unit 42, the measurement value of the light amount sensor 50, and the information stored in the control information storage unit 61 and the contribution storage unit 62. Control to keep the brightness of the image constant. Details of the control performed in S102 will be described later.

  In S103, the measurement value of the light quantity sensor 50 is acquired again, and it is determined whether the difference between the measurement value and the reference value stored in the control information storage unit 61 exceeds a threshold value. If it exceeds the threshold value, it is determined that the control in S102 has failed, and the process proceeds to S104. If it does not exceed the threshold value, it is determined that the control in S102 is successful, and the control is terminated.

  In S104, it is determined whether the number of consecutive failures in the determination result in S103 exceeds a threshold value. When it exceeds the threshold value, it is determined that the current contribution degree of the projector 1 has changed from the contribution degree stored in the contribution degree storage unit 62, and the process proceeds to S105. If it does not exceed the threshold, it is determined that the contribution has not changed, and the process proceeds to S102.

  In S <b> 105, the determination unit 72 determines whether information necessary for the contribution update is complete in the contribution update information storage unit 63. If it is determined that the information necessary for the contribution update is available, the process proceeds to S106. If it is determined that the information necessary for the contribution update is not complete, the process waits until it is complete. The condition for gathering information necessary for the contribution update is that the set of image information of each highly independent area is equal to or greater than the number of divided areas + 1.

  In S106, the contribution is updated based on the information stored in the contribution update information storage unit 63. Details of the control performed in S106 will be described later.

  By performing the control of S101 to S106 in this way, it is possible to keep the brightness of the projected image constant even when the correlation between the measurement value of the light amount sensor and the light amount correction amount changes during video projection. .

  Next, with reference to FIG. 5, the control performed in S102 to keep the brightness of the projection image constant will be described. Each step in FIG. 5 is mainly executed based on a command from the correction unit 71.

  When the correction of image brightness is started, first, in step S102a, the image conversion unit 41 converts a video signal VS supplied from an image supply device such as a personal computer (not shown) into an image signal IS. This conversion is executed according to various setting values that change the display state of the image, such as brightness, contrast, or color adjustment. The image conversion unit 41 outputs the image signal IS to the image analysis unit 42 and the image correction unit 43.

Subsequently, the image analysis unit 42 calculates a histogram His _N (N = A to I) of each of the A to I regions (for each image region) with respect to the image signal input from the image conversion unit 41. And output to the correction unit 71 of the control circuit 70. At this time, the image correction unit 43 outputs to the panel drive circuit 31 an image signal IS that has been subjected to image brightness correction in accordance with the γ value set for the image signal IS converted by the image conversion unit 41. To do. The panel drive circuit 31 drives the liquid crystal panel 32 in accordance with the image signal IS and modulates the light from the lamp 12 to display an image on the projection surface.

Subsequently, in step S102b, the CPU 251 uses the histogram His _N calculated in step S102a and the data table of FIG. 3A set in the control information storage unit 61 to output the light amount sensor 50 for each region. A value increment EV _N (increase / decrease amount) is calculated. The increment EV _N of the output value of the light quantity sensor 50 for each region is expressed as the following equation (1).

In Expression (1), His _NPB is the number of pixels of the luminance PB included in the region N, IV _PB is the increment of the output value of the light quantity sensor at the luminance PB of one pixel (1 pixel), and Grad is the maximum luminance value. In this way, the CPU 251 calculates the increase / decrease amount of the output value (measurement value) of the light amount sensor 50 for each region of the image using the histogram.

Subsequently, in step S102c, the correction unit 71 calculates the predicted output value PSV of the light amount sensor 50. The predicted output value PSV of the light quantity sensor 50 is the increment EV _N of the output value of the light quantity sensor 50 calculated in step S102b, the contributions a to i set in the region N shown in the data table of FIG. And it is calculated based on the output value j of the light quantity sensor 50 at the time of all black display. Further, the predicted output value PSV of the light quantity sensor 50 is expressed as the following equation (2).

In Expression (2), a to i are contributions set in the areas A to I, and j is an output value of the light amount sensor at the time of all black display. In this way, the control unit 71 calculates the predicted output value PSV of the light quantity sensor 50 based on the increase / decrease amount (increase / decrease EV _N ).

  Next, in step S <b> 102 d, the light amount sensor 50 measures the light amount of the image displayed in step S <b> 102 a and outputs a light amount sensor value SV that is an output value (measurement value) to the control unit 71. Subsequently, in step S102e, the control unit 71 calculates a correction value Bri of the brightness of the image. The image brightness correction value Bri is based on the predicted output value PSV of the light quantity sensor 50 calculated in step S102c and the output value (light quantity sensor value SV) of the light quantity sensor 50 measured in step S404. It is calculated and expressed as the following formula (3).

As described above, the control unit 71 calculates the correction value using the measured value (light amount sensor value SV) of the light amount sensor 50 and the predicted output value PSV.

  Subsequently, in step S102f, the control unit 71 determines whether or not light source control is possible for the image brightness correction value Bri calculated in step S102e. If light source control is possible, the process proceeds to step S102g. On the other hand, when the light source control is impossible, the control unit 71 outputs the image brightness correction value Bri to the image correction circuit 233, and proceeds to step S102h. Here, when the light source control is impossible, for example, when the lamp light amount is increased, the supply power of the lamp 12 exceeds 100%, or when the lamp light amount is decreased, the lamp 12 is supplied. This is a case where the power is set to the lower limit value.

  In step S102g, the control unit 71 uses the data table of FIG. 3C stored in the control information storage unit 61 to calculate the lamp 12 from the correction value Bri of the image brightness calculated in step S102e. The amount of change in power supply is calculated. Then, the power supplied to the lamp 12 is obtained. Then, the control unit 71 outputs a light amount control signal corresponding to the power supplied to the lamp 12 to the light source driving circuit 11. The light source driving circuit 11 controls the power supplied to the lamp 12 based on the light amount control signal output from the control unit 71.

  In step S102h, the control unit 71 uses the data table of FIG. 4 stored in the image correction unit 43 to change the γ value from the brightness correction value Bri output from the control unit 71 in step S102f. The quantity cγn is calculated and the γ value is set.

  By the control as described above, the brightness of the image projected on the projection surface is adjusted (corrected). In the present embodiment, the correction of the brightness of the image projected on the projection surface is realized by the combined use of the light source control and the color tone control. is there. In the present embodiment, the predicted output value of the light quantity sensor 40 is calculated using the histogram for each region of the projected image, but the present invention is not limited to this. The predicted output value of the light quantity sensor 40 can be changed as appropriate, for example, by calculating using the average luminance for each region. Moreover, the numerical formula shown in the present embodiment shows an example of the control, and is not limited to these.

Next, the contribution update method performed in S106 will be described. The update of the degree of contribution is expressed by using a set of “increment EV _LN of the output value of the light amount sensor 50 for each region” and “output value SV _L of the light amount sensor 50” of a plurality of (divided region number + 1 or more) display images L. It is calculated as (4) to (6).

In the formula _(4), SV 1 ~SV _l is the measured value of the light amount sensor 40 at the time of image display L. EV _LN is the increment of the output value of the light amount sensor 50 for each area obtained from the display image information and Equation 1. A1 to j1 are the contributions after the update. An expression obtained by converting Expression (4) into a matrix form is shown in Expression (5).

Since y is a measured value of the light quantity sensor 40 when the image L is displayed and A is an increment of the output value of the light quantity sensor 50 for each region, it is a known value. Here, the unknown value to be obtained is the updated contribution degree x, which is calculated by solving the equation (5).

  Further, when the least square method is used in consideration of the error in the measured values of y and A, the updated contribution x can be obtained by using Equation (6).

Here, A ^T represents a transposed matrix of the matrix A, and A ⁻¹ represents an inverse matrix of the matrix A. In this way, by using a set of “increment EV _LN of the output value of the light amount sensor 50 for each region” and “output value SV _L of the light amount sensor 50” of the plurality of display images, the contribution degree even during image projection. Can be updated.

  As described above, according to the projector 1, the brightness of the projected image is made constant by controlling the light amount of the lamp 12 and the modulation amount of the liquid crystal panel 32 even when the brightness of the projected image changes during the video projection. It becomes possible to keep. Further, by updating the contribution degree using the input image information and the output value of the light amount sensor 50, it is possible to suppress the change in the brightness of the projected image due to the change in each element constituting the projector 1.

[Example 2]
Hereinafter, an image projection apparatus according to a second embodiment of the present invention will be described with reference to FIGS.
According to the projector 2 of the present embodiment, even when a plurality of light sources are used, the change in the correlation between the measurement value of the light amount sensor generated during video projection and the light amount correction amount is corrected, and the brightness of the projected image is adjusted. It is possible to provide an image projection apparatus that can be kept constant.

FIG. 6 is a schematic diagram showing the configuration of the projector 2 in this embodiment.
In FIG. 6, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The projector 2 and the projector 1 are different from each other in that the lamp unit 10 is replaced with the light source unit 210, and other configurations are the same.

The configuration of the light source unit 210 will be described with reference to FIG.
The light source unit 210 includes a light source driving circuit 211, an LED unit 212, an LED 213, and a dichroic mirror 214. The light source control circuit 211 controls the power supplied to each LED 213 according to the control signal from the control circuit 70. At this time, the supplied power may be controlled for each block in which the plurality of LEDs 213 are combined. The LED unit 212 holds a plurality of LEDs 213 for each of RGB. The LEDs 213 individually emit light based on the power supplied from the light source driving circuit 211.

  The light emitted by the LED 213 is guided to the illumination optical system 20 through the following optical path for each color. The R light passes through the dichroic mirror 214a, is reflected by the dichroic mirror 214b, and is guided to the illumination optical system 20 in the right direction in FIG. The G light passes through both the dichroic mirrors 214a and 214b and is guided to the illumination optical system 20 in the right direction in FIG. The B light is reflected by the dichroic mirror 214a, passes through the dichroic mirror 214b, and is guided to the illumination optical system 20 in the right direction in FIG. The light guided to the illumination optical system 20 follows the same optical path as in the first embodiment. Note that the optical system shown in the light source unit 210 of the present embodiment is an example, and is not limited to these.

  Next, control for correcting a change in the correlation between the measurement value of the light amount sensor generated during video projection and the light amount correction amount even when a plurality of light sources in the present embodiment is used will be described.

  First, the display image area is divided for each area where each LED 213 illuminates the liquid crystal panel 31. Next, the contribution degree of each divided area is stored in the contribution degree storage unit 62. After that, brightness control and contribution update can be performed by performing the brightness correction procedure and the contribution correction procedure in the same manner as the method described in the first embodiment.

  As described above, according to the projector 2, the display image area is divided into areas in which the LEDs 213 illuminate the liquid crystal panel 31, so that even when a plurality of light sources are used, projection images generated during video projection are displayed. It becomes possible to keep the brightness constant. In addition, it is possible to suppress a change in the brightness of the projected image due to a change in each element constituting the projector 2.

[Example 3]
An image projection apparatus according to the third embodiment of the present invention will be described below with reference to FIGS.
According to the projector 3 of the present embodiment, a plurality of light quantity sensors are used, the change in the correlation between the measurement value of the light quantity sensor generated during video projection and the light quantity correction amount is corrected, and the brightness of the projected image is kept constant. It is possible to provide an image projection apparatus that makes it possible.

FIG. 8 is a schematic diagram showing the configuration of the projector 3 in this embodiment.
In FIG. 8, the same parts as those in the second embodiment are denoted by the same reference numerals, and redundant description is omitted. The projector 3 and the projector 2 are different from each other in that the light quantity sensor 50 and the EEPROM 60 are replaced with the light quantity sensor group 350 and the EEPROM 360, and other configurations are the same.

  The configuration of the light quantity sensor group 350 will be described with reference to FIG. The light quantity sensor group 350 includes a photodiode unit 351, an ADC 352, and a light reduction unit 353. The photodiode unit includes a plurality of photodiodes 351a and a photodiode holding unit 351b, and outputs a voltage corresponding to the light guided to each photodiode 351a by the color synthesis optical system 22 to the ADC 252. The ADC 252 converts the voltage input from the plurality of photodiodes 351 a into a digital signal and outputs the digital signal to the control circuit 70.

  The light reducing unit 353 is installed between the color synthesis optical system 22 and the photodiode unit 351 and reduces the amount of light incident on the photodiode 351 unit. With such a configuration, the light amount sensor 350 can output a value (voltage) corresponding to the brightness (light amount) of the projection image of the projector 3.

  Note that the photodiode unit 351 including a plurality of light quantity sensors may be used in place of a CMOS sensor, a CCD sensor, or the like.

  Next, the configuration of the EEPROM 360 will be described. The EEPROM 360 includes a control information storage unit 361, a contribution degree storage unit 362, and a contribution degree update information storage unit 363, and inputs / outputs data according to instructions from the control circuit 70. The control information storage unit 361 stores information used in the control for keeping the brightness of the projected image constant performed by the control unit 71. The contribution degree storage unit 362 stores the contribution degree of each region of the display image divided by the image analysis unit 42 and the measurement value of each photodiode 351a (351a1 to am). In addition, the contribution update information storage unit 363 stores a set of luminance distribution analysis results of each area of the divided display image output from the image analysis unit 42 and measurement values of the photodiodes 351a (351a1 to am).

  The contribution rate of each photodiode 351 for each display image area stored in the contribution storage unit 362 of the EEPROM 360 is shown in FIG. The contribution ratio of each photodiode for each display image area is determined by the contribution degree am to im, which is the degree that the light that has passed through each of the divided areas A to I of the display image reaches each photodiode unit 351am, and all black display It is the data table which memorize | stored the measured value jm of the light quantity sensor 50 at the time. The information stored in the control information storage unit 361 of the EEPROM 360 is the same as that described in the first embodiment.

Next, a brightness control method will be described.
The image brightness correction method is different in that the processing shown in S102 and S106 in FIG. 5 is replaced with S3102 shown in FIG. 11 and equations (7) to (12) described later, and other processing is shown in FIG. It is the same as the control method shown.

With reference to FIG. 11, the control for keeping the brightness of the projection image constant in S3102 will be described.
Each step of FIG. 11 is mainly executed based on a command from the correction unit 71. When the correction of image brightness is started, first, in step S3102a, the image conversion unit 41 converts a video signal VS supplied from an image supply device such as a personal computer (not shown) into an image signal IS. This conversion is executed according to various setting values that change the display state of the image, such as brightness, contrast, or color adjustment. The image conversion unit 41 outputs the image signal IS to the image analysis unit 42 and the image correction unit 43.

Subsequently, the image analysis unit 42 calculates a histogram His _N (N = A to I) of each of the A to I regions (for each image region) with respect to the image signal input from the image conversion unit 41. And output to the correction unit 71 of the control circuit 70. At this time, the image correction unit 43 outputs to the panel drive circuit 31 an image signal IS that has been subjected to image brightness correction in accordance with the γ value set for the image signal IS converted by the image conversion unit 41. To do. The panel drive circuit 31 drives the liquid crystal panel 32 in accordance with the image signal IS and modulates the light from the lamp 12 to display an image on the projection surface.

Next, step S3102b will be described. In S3102b, the CPU 251 uses the histogram His _N calculated in Step S3102a and the data table of FIG. 3A set in the control information storage unit 361 to calculate the output value of the photodiode unit 351 for each region. Increase / decrease amount EV _N is calculated. Decrease amount EV _N of the output value of the photodiode unit 351 for each area is expressed by the following equation (7).

In Expression (7), His _NPB is the number of pixels of the luminance PB included in the region N, IV _PB is the increment of the output value of the light quantity sensor at the luminance PB of one pixel (1 pixel), and Grad is the maximum luminance value. As described above, the CPU 251 calculates the increase / decrease amount of the output value (measurement value) of the photodiode unit 351 for each region of the image using the histogram.

Subsequently, in step S3102c, the correction unit 71 calculates a predicted output value PSV _M of the photodiode unit 351a _M (M is a photodiode unit number 1 to m). Photodiode unit predicted output value PSV _M of 351a _M, the photo increments EV _N of the output value of the diode unit 351, contribution is set to a region N _a M through i _M, and, in the all black display photodiode unit 351 It is calculated based on the output value j _M. Further, the predicted output value PSV _M of the photodiode unit 351a _M is expressed as the following equation (8).

In Expression (8), a _{M to} i _M are contributions set in the regions A to I of the photodiode 351a _M , and j _M is an output value of the photodiode 351 _M at the time of all black display. In this way, the control unit 71 calculates the predicted output value PSV _M of the photodiode unit 351 based on the increase / decrease amount (increase / decrease EV _N ).

Next, at step S3102d, the photodiode unit 351, the light intensity of the displayed image in step S3102a is measured and outputs the light amount sensor value SV _M which is the output value (measured value) to the controller 71.

Subsequently, in step S3102e, the control unit 71 calculates a correction value Bri for the brightness of the image. Brightness correction value Bri images are predicted output value PSV _M photodiode unit 351a _M, and is calculated based on the output value of the photodiode unit 351 _M (light amount sensor value SV _M), the following equation (9 ).

As described above, the control unit 71 calculates the correction value using the measured value (light quantity sensor value SV _M ) of the photodiode unit 351 and the predicted output value PSV _M.

The calculation of equal Bri was equated the contribution to brightness correction value Bri of formula (9) in all the photodiodes units 351 _M of the image, for obtaining and weighted for each photodiode unit 351 _M The method can be changed as appropriate.

  Subsequently, in step S3102f, the control unit 71 determines whether or not light source control is possible for the image brightness correction value Bri calculated in step S3102e. If the light source control is possible, the process proceeds to step S3102g. On the other hand, when the light source control is impossible, the control unit 71 outputs the image brightness correction value Bri to the image correction circuit 233, and the process proceeds to step S3102h3. Here, when the light source control is impossible, for example, when the lamp light amount is increased, the supply power of the lamp 12 exceeds 100%, or when the lamp light amount is decreased, the lamp 12 is supplied. This is a case where the power is set to the lower limit value.

  In step S3102g, the control unit 71 uses the data table of FIG. 3C stored in the control information storage unit 361 to calculate the amount of change in the power supplied to the lamp 12 from the image brightness correction value Bri. The power supplied to the lamp 12 is obtained. Then, the control unit 71 outputs a light amount control signal corresponding to the power supplied to the lamp 12 to the light source driving circuit 11. The light source driving circuit 11 controls the power supplied to the lamp 12 based on the light amount control signal output from the control unit 71.

  In step S3102h, the control unit 71 uses the data brightness correction value Bri output from the control unit 71 in step S3102f using the data table of FIG. 3D stored in the image correction unit 43. The γ value change amount cγn is calculated, and the γ value is set.

  By the control as described above, the brightness of the image projected on the projection surface is adjusted (corrected). In the present embodiment, the correction of the brightness of the image projected on the projection surface is realized by the combined use of the light source control and the color tone control. is there. In this embodiment, a lamp is used as a light source. However, an LD, an LED, or the like may be used, and the method shown in Embodiment 2 may be used in combination. In addition, the numerical formula shown in the present embodiment shows an example of control, and is not limited to these.

Next, the contribution update method performed in S106 will be described. The update of the contribution is performed by “increment EV _LN of the output value of the photodiode unit 351 for each region” and “output of the photodiode unit 351a _M ” for a plurality of (number of divided regions + 1 or more) display images L (L = 1 to 1). It is calculated _| required like Formula (10)-(12) using the group of value SVLM.

In Expression (10), SV _LM is a measured value of the photodiode unit 351a _M when the image L is displayed. EV _LN is the increment of the output value of the photodiode unit 351 for each region N when the display image L is displayed, which is obtained from the display image information and Expression 1. _Then, a M _~j M (M is 1 to m) is the contribution of the photodiode unit 351a _M updated. An expression obtained by converting Expression (10) into a matrix form is shown in Expression (11).

Since y is a measured value of the light quantity sensor M when the image L is displayed and A is an increment of the output value of the photodiode unit 351 calculated from the histogram of the region N when the image L is displayed, it is a known value. Here, the unknown value to be obtained is the contribution x of the updated photodiode unit 351a _M , and is calculated by solving the equation (11). Further, when the least square method is used in consideration of the error in the measured values of y and A, the updated contribution x can be obtained by using Equation (12).

Here, A ^T represents a transposed matrix of the matrix A, and A ⁻¹ represents an inverse matrix of the matrix A. In this way, a set of “increment EV _LN of the output value of the photodiode unit 351a for each region when the multiple display image L is displayed” and “the output value SV _LM of each photodiode unit 351 when the multiple display image L is displayed”. By using it, the contribution can be updated even during video projection.

  As described above, according to the projector 1, the brightness of the projected image is made constant by controlling the light amount of the lamp 12 and the modulation amount of the liquid crystal panel 32 even when the brightness of the projected image changes during the video projection. It becomes possible to keep. In addition, by updating the contribution using the input image information and the output value of the photodiode unit 351, it is possible to suppress a change in the brightness of the projected image due to a change in each element constituting the projector 1. .

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1, 2, 3 housings, 10, 210 lamp units (light source means),
11 Light source drive circuit, 12 lamp, 212 LED unit, 213 LED,
214 dichroic mirror, 20 illumination optical system, 21 color separation optical system,
22 color synthesis optical system, 30 liquid crystal panel unit (light modulation means),
31 panel drive circuit, 32 liquid crystal panel, 40 image processing engine (image processing means),
41 image conversion unit, 42 image analysis unit, 43 image correction unit,
50 light quantity sensor (light quantity measuring means), 350 light quantity sensor group, 51 photodiode,
351 photodiode unit, 52, 352 ADC, 53, 353 dimming unit,
60, 360 EEPROM (storage means), 61 control information storage unit,
62 contribution degree storage unit, 63 contribution degree update information storage unit, 70 control circuit (control means),
71 Correction unit, 72 Determination unit, 73 Update unit

Claims (21)

An image projection device for projecting an image onto a projection surface, and a light source means;
Light modulating means for modulating light from the light source means;
Image processing means for generating an image signal for input to the light modulation means;
A light amount measuring means for measuring the amount of light modulated by the light modulating means;
Contribution degree storage means for storing a contribution degree that is the degree to which the light from the light source means reaches the light amount measurement means via the light modulation means;
Update means for updating the contribution degree stored in the contribution degree storage means;
An image projection apparatus comprising: control means for controlling brightness of an image projected on a projection surface using the contribution degree. The image projection apparatus according to claim 1, wherein the image processing unit further includes an image analysis unit that acquires image information. The image projection apparatus according to claim 1, wherein the image information acquired by the image analysis unit is an image luminance distribution. 4. The image projection apparatus according to claim 1, wherein the image analysis unit divides an image formation area of the input image into a plurality of areas and acquires image information of each area. 5. 5. The image projection apparatus according to claim 1, wherein the contribution degree storage unit stores the contribution degree in units of regions obtained by dividing a display image into a plurality of areas. The said control means controls the brightness of the image projected on a projection surface using the image information of each said area | region, the said contribution, and the light quantity measurement value which is a measurement value of the said light quantity measurement means. The image projection device according to any one of claims 1 to 5. The update means further includes contribution update information storage means for storing image information of each area of the input image and the light quantity measurement value measured when the input image is displayed. The image projection device according to claim 6. The image projection apparatus according to claim 1, further comprising a determination unit that determines a change in the contribution degree. The image projecting apparatus according to claim 1, wherein the update unit updates the contribution degree according to a determination unit. The determination unit notifies the update unit of the update start of the contribution when the contribution update is necessary and the set of image information of each region having high independence is prepared in the contribution update information storage unit. The image projection apparatus according to any one of claims 1 to 9, wherein the image projection apparatus includes: The control means corrects the brightness of the image projected on the projection surface by outputting a control signal generated using the contribution to the light source means or the image processing means. The image projection device according to claim 1, wherein the image projection device is a feature. The image projecting apparatus according to claim 1, wherein the contribution degree storage unit stores a contribution degree in consideration of an influence of a contribution ratio by an optical system. 13. The image projection apparatus according to claim 1, wherein the contribution degree storage unit stores a contribution degree in consideration of an influence of a contribution rate by keystone correction. The image projection apparatus has an external light quantity measuring unit that measures the light quantity outside the image projection apparatus,
The control means uses the image information of each region, the contribution, a light quantity measurement value that is a measurement value of the light quantity measurement means, and an external light quantity measurement value that is a measurement value of the external light quantity measurement means. The image projection apparatus according to claim 1, wherein brightness of an image projected on the image is controlled. The image projection apparatus includes a luminance adjustment storage unit that stores a luminance adjustment value;
The said control means controls the brightness of the image projected on a projection surface using the value memorize | stored in the said brightness adjustment memory | storage means, The Claim 1 thru | or 14 characterized by the above-mentioned. Image projection device. The image projection apparatus according to claim 1, wherein the control unit switches between valid / invalidity of brightness control of an image projected on a projection surface. The image projection apparatus according to claim 1, wherein the light source unit includes a plurality of light source units. The contribution degree storage means stores a contribution degree storage means for storing a contribution degree which is a degree that light from the plurality of light source means reaches the light amount measurement means via a light modulation means. The image projection device according to 17. The image projection apparatus according to claim 1, wherein the light quantity measuring unit includes a plurality of light quantity measuring units. The contribution degree storage means stores contribution degree storage means for storing the contribution degrees of the plurality of light quantity measurement means, each of which is the degree that the light from the light source means reaches the plurality of light quantity measurement means via the light modulation means. The image projection apparatus according to claim 19. The control means uses the image information of each region, the contributions of the plurality of light quantity measurement means, and a plurality of light quantity measurement values that are measurement values of the plurality of light quantity measurement means, and brightness of an image projected on the projection surface. 21. The image projection apparatus according to claim 20, wherein the image projection apparatus is controlled.