JP2004304479A - Projection video display device, luminance control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a sense of discomfort given to eyes caused by uneven luminance and an external light or the like on a screen . <P>SOLUTION: A two-dimensional sensor such as a CCD camera provided in the inside of a projection video display apparatus (projector) acquires projection image information and feeds back the information to carry out luminance control thereby suppressing uneven luminance of a projected image caused by projection distance, size, angle, and an optical characteristic of the display device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projection display apparatus that acquires projection image information and suppresses luminance unevenness of an image from the information, a luminance control method, and a program.
[0002]
[Prior art]
Image devices used for the projection type image display device (projector) include a CRT, a liquid crystal, and a DMD (Digital Micromirror Device). In the method using a CRT, images displayed on three CRTs of R, G, and B are separately projected, and are superimposed and displayed on a screen.
2. Description of the Related Art Projectors using liquid crystal include a method of transmitting light from behind and a method of reflecting light from the front. When classified according to the number of liquid crystal devices to be used, the liquid crystal devices are classified into a single-panel type and a three-panel type. The DMD is a reflection type, and a projector using the DMD is called a DLP projector.
[0003]
A method for correcting distortion in a projector includes a method for correcting distortion of a projected image (Patent Document 1) and a method for adjusting luminance, convergence, and geometric distortion (Patent Document 2).
[0004]
[Patent Document 1]
JP-A-8-271852 [Patent Document 2]
JP-A-10-93984
[Problems to be solved by the invention]
The most important thing in the projector industry is "brightness", and at present it is competing with manufacturers to develop bright models. However, depending on the actual usage environment of the user, the brightness may be a bottleneck, and may cause discomfort due to the appearance of glare, uneven brightness, or external light.
The present invention aims to prevent these.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a projector, comprising: a luminance information acquisition unit for acquiring luminance information of an image projected on a screen; and a luminance distribution obtained from the luminance information acquired by the luminance information acquisition unit. Signal processing means.
[0007]
According to a second aspect of the present invention, in the projector according to the first aspect, the signal processing unit includes a unit that performs image correction, a unit that holds video signal information in a memory, and a unit that stores the luminance information in a memory. The image processing apparatus further includes a holding unit and a luminance improving unit that selects a reference value from the luminance information and adjusts the luminance distribution to the reference value.
[0008]
According to a third aspect of the present invention, in the projector according to the second aspect, the brightness improving unit extracts a minimum brightness value from the brightness information, and a brightness value of the brightness information and the brightness minimum value. A first subtraction means for performing subtraction between the first subtraction means and a luminance value of the video signal and a result of the first subtraction means. And a means for replacing the luminance value of the video signal with the result of the second subtraction means.
[0009]
According to a fourth aspect of the present invention, there is provided a brightness control method, wherein a video signal storing step of storing a video signal in a memory; a brightness information obtaining step of obtaining brightness information of an image projected on a screen; A luminance information storing step of storing, a reference value determining step of selecting a reference value from the luminance information, a first subtraction step of subtracting a luminance value of the luminance information from the reference value, and a first subtraction step And a second subtraction step of subtracting the luminance value of the video signal from the result of the first subtraction step, and storing the luminance value of the video signal in the second And a luminance correction step of replacing the result with the result of the subtraction step.
[0010]
The invention according to claim 5 is the brightness control method according to claim 4, wherein the reference value determining step selects a minimum brightness value of the brightness information as a reference value.
[0011]
A brightness control program according to a sixth aspect of the present invention includes a video signal storing process of storing a video signal in a memory, a brightness information obtaining process of obtaining brightness information of an image projected on a screen, and a process of storing the brightness information in a memory. Luminance information storage processing to be stored, reference value determination processing for selecting a reference value from the luminance information, first subtraction processing for subtracting the luminance value of the luminance information from the reference value, and first subtraction step Subtracting the result of the first subtraction step from the luminance value of the video signal and the result of the first subtraction step; storing the luminance value of the video signal in the second And a brightness correction process for replacing the brightness value with a brightness value obtained by the subtraction process.
[0012]
According to a seventh aspect of the present invention, there is provided the brightness control program according to the sixth aspect, wherein the reference value determination process selects a minimum brightness value of the brightness information as a reference value.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
<First embodiment>
FIG. 1 shows a configuration diagram of the first embodiment.
FIG. 1 shows the configuration of a general projection display device. The basic configuration is a lamp 102, a display device 103, a projection lens 104, and a signal processing circuit 105. Here, the display device 103 is a liquid crystal device. The input video signal is subjected to A / D conversion, then converted from the input resolution to a display resolution equivalent to that of the liquid crystal device by the signal processing circuit 105, and output to the display device 103 through γ correction and D / A conversion. Is done.
In the present invention, a two-dimensional sensor 106 such as a CCD camera is provided inside, so that projection image information (coordinates / luminance) can be obtained. The two-dimensional sensor 106 is installed in a direction corresponding to the direction of the viewer. When installing at other positions, the measured luminance is corrected.
[0014]
The brightness information acquired by the sensor is generally an image having uneven brightness depending on the position of the projection screen as shown in FIG.
In FIG. 2, X represents the horizontal coordinate of the image, Y represents the vertical coordinate, and Z represents the luminance.
In the present invention, the luminance unevenness is controlled by controlling the luminance in the signal processing circuit so that the Z value in FIG. 2 is constant, that is, ab ≒ 0 in all the coordinates in FIG.
[0015]
FIG. 3 shows a block diagram of the signal processing circuit 105.
The signal processing circuit 105 includes an A / D converter 301, a signal processing unit 302, a CPU 303, a frame memory 304, an LUT 305, a frame memory 306, and a control circuit 307.
[0016]
The input video signal is 100% white, that is, a signal of MAX luminance that can be projected by the display device. This is an optimal test signal, and the test signal may not be limited to this.
[0017]
The video signal is passed from the A / D converter 301 to the signal processing unit 302 and is converted to the same display resolution as that of the liquid crystal device. The frame memory 304 stores data converted to the display resolution, the frame memory 306 stores data captured by the two-dimensional sensor, and the LUT (Look Up Table) 305 stores difference data necessary for luminance control. You.
The operation timing of the two-dimensional sensor is controlled by the control circuit 307.
[0018]
At this time, the data stored in the three memories is equivalent to the display resolution. First, data for one frame acquired by the two-dimensional sensor is stored in the frame memory 2. Next, the MAX value (this is Zmax) and the MIN value (this is Zmin) in the data stored in the frame memory are obtained, and the difference data αxy calculated in (1) is sequentially stored in the LUT in the memory. I do. Note that xy represents coordinates (for example, when the display resolution is XGA (Extended Graphics Array), x = 1024 and y = 768).
[0019]
αxy = (data in frame memory 2) Zxy−Zmin (1)
[0020]
Finally, the data calculated in (2) is output to the display device via the signal processing circuit.
[0021]
(Data stored in frame memory 1) βxy-αxy (2)
[0022]
Accordingly, Zmax = Zmin in theory, and the visual luminance distribution can be kept constant without depending on the projection distance, size, and angle of the projector.
In other words, the luminance distribution on the screen is concentrated on Zmin.
[0023]
Thus, an inexpensive and small projector having a brightness control function can be realized.
[0024]
A case in which lamp output control is performed in combination with the above embodiment will be considered.
By storing the relationship between the minimum luminance value captured by the sensor and the optimum lamp voltage in the LUT, it becomes possible to automatically maintain the optimum brightness.
As a result, power saving of the product and a long life of the lamp can be realized.
[0025]
<Second embodiment>
FIG. 4 shows a three-plate structure employing the present invention.
The difference between the present embodiment and the first embodiment is an optical system. The optical system includes an integrator 401, condenser lenses 402 to 404, liquid crystal devices 405 to 407, dichroic mirrors 408 and 409, mirrors 410 to 413, and a dichroic prism 414. The liquid crystal device may be the same as the display device 103 used in the first embodiment.
[0026]
Light emitted from the lamp 102 passes through the integrator 401 and is decomposed into BGR by dichroic mirrors 408 and 409. The BRG lights enter the liquid crystal devices 405 to 407 from the condenser lenses 402 to 404 and are combined by the dichroic prism 414.
The projector acquires the luminance information of the screen 107 with the two-dimensional sensor 106, performs the same processing as in the first embodiment with the signal processing circuit 105, and transmits the correction information to the three liquid crystal devices 405 to 407.
[0027]
As a result, it is possible to realize a projector that can be easily refined as compared with a single-panel system in which three color liquid crystal cells (R, G, B) are formed in one panel.
[0028]
【The invention's effect】
As described above, by using the present invention, it is possible to provide a stable image regardless of the usage environment of the projection display device, and to maintain a high level of quality.
If the lamp output can be controlled, power consumption can be reduced, and the life of the lamp can be extended.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a first embodiment.
FIG. 2 is a diagram illustrating an example of a luminance distribution of a projection image.
FIG. 3 is a block diagram illustrating a configuration of a signal processing circuit.
FIG. 4
FIG. 9 is a block diagram illustrating a configuration of a second embodiment.
[Explanation of symbols]
Reference Signs List 101 Projector 103 Display device 105 Signal processing circuit 106 Two-dimensional sensor

Claims (7)

Brightness information obtaining means for obtaining brightness information of the image projected on the screen,
A projection-type video display device, comprising: a signal processing unit configured to make uniform a luminance distribution obtained from the luminance information acquired by the luminance information acquiring unit. The signal processing means,
Means for performing image correction;
Means for holding video signal information in a memory;
Means for holding the luminance information in a memory;
2. The projection display apparatus according to claim 1, further comprising: a luminance improving unit that selects a reference value from the luminance information and adjusts the luminance distribution to the reference value. 3. The brightness improving means includes:
Means for extracting a minimum luminance value from the luminance information,
First subtraction means for subtracting the luminance value of the luminance information from the luminance minimum value;
Means for holding the result of the first subtraction means in a memory;
Second subtraction means for subtracting the luminance value of the video signal from the result of the first subtraction means;
3. The projection type image display device according to claim 2, further comprising: means for replacing a luminance value of the video signal with a result of the second subtraction means. A video signal storing step of storing the video signal in a memory,
A luminance information obtaining step of obtaining luminance information of an image projected on the screen,
A luminance information storing step of storing the luminance information in a memory,
A reference value determining step of selecting a reference value from the luminance information,
A first subtraction step of subtracting the luminance value of the luminance information from the reference value;
A subtraction result storing step of storing a result of the first subtraction step in a memory;
A second subtraction step of subtracting the luminance value of the video signal from the result of the first subtraction step;
A brightness correction step of replacing a brightness value of the video signal with a result of the second subtraction step. The brightness control method according to claim 4, wherein the reference value determination step selects a lowest brightness value of the brightness information as a reference value. A video signal storage process for storing a video signal in a memory;
Brightness information acquisition processing for acquiring brightness information of an image projected on the screen,
Brightness information storage processing for storing the brightness information in a memory;
A reference value determination process of selecting a reference value from the luminance information,
A first subtraction process for subtracting a luminance value of the luminance information from the reference value;
Subtraction result storing processing for storing the result of the first subtraction step in a memory;
A second subtraction process for subtracting the luminance value of the video signal from the result of the first subtraction process;
A brightness correction process for replacing a brightness value of the video signal with a brightness value obtained by the second subtraction process. The computer-readable storage medium according to claim 6, wherein the reference value determination process selects a minimum luminance value of the luminance information as a reference value.

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