JPH08328147A - Projection type image display device - Google Patents

Abstract

PURPOSE: To precisely correct the luminance unevenness over the whole area of input video signal level, and perform a correction in conformation to the projecting direction and setting state of a projection type image display device. CONSTITUTION: This device has a memory device 4 in which a projected screen is preliminarily divided into grid form, and correction data corresponding thereto are inputted, and the address synchronous with an input video signal is inputted to the memory device from an address counter 3, thereby, the correction data are read in order. The primary color signal outputted from a signal processing circuit 9 is digitalized by an A/D converter 11, modified in amplitude and DC level by a correcting arithmetic circuit 10 according to the correction data which is the output of the memory device 4, and turned to analogue by a D/A converter 12 to form a video signal in which the luminance unevenness is corrected over the whole area of input level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device having an arithmetic circuit for correcting uneven brightness.

[0002]

2. Description of the Related Art In recent years, it has been proposed to incorporate a circuit for improving the unevenness of R, G, B monochromatic brightness on a screen and the unevenness of color due to superposition of these in a projection type image display device.

For example, a projection type image display device incorporating a conventional luminance unevenness and color unevenness correction circuit disclosed in Japanese Patent Laid-Open No. 61-243495 will be described with reference to the drawings. FIG. 7 is a block diagram of a brightness unevenness and color unevenness correction circuit of a conventional projection type image display device.

In FIG. 7, the address of the memory device 58 is the vertical sync signal input and the output signal of the phase locked loop circuit 56 that generates a clock signal synchronized with the horizontal sync signal input through the horizontal sync signal input terminal 54. Terminal 55
It is determined by an address counter 57 that sequentially specifies an address to be operated by a vertical synchronizing signal via.

The memory device 58 stores correction data calculated in advance from the brightness data for each area obtained by appropriately dividing the screen on which the projection image display device is projected, and the address counter 57 of the memory device 58 stores the correction data. The memory data at the designated address is transferred to the D / A converter 59.
Is converted into an analog signal.

Further, the video signal input through the video signal input terminal 51 is modulated by the output signal of the D / A converter in the adder circuit 52 at a DC level in accordance with the variation in luminance in each area. , Is output via the video signal output terminal. In this way, it is possible to correct luminance unevenness and color unevenness on the screen.

[0007]

However, in the projection type image display device having the conventional structure as described above, the correction means is limited to the modulation of the DC level, and therefore the correct correction is made for the correction data. It is difficult to correct luminance unevenness and color unevenness corresponding to a wide range of input video signals from a low signal level area to a high signal level area, which is limited to one point at the video signal level when the brightness data is acquired.

Further, in the projection type image display device,
It is required to support the switching of the projection direction such as the back direction and the switching of the device installation state such as floor-standing and ceiling-mounting. Since the position of the unevenness on the screen also differs depending on the projection direction and the installation state, it is necessary to make a corresponding correction.

The present invention has been made in consideration of the above points, and corrects the unevenness in brightness and the unevenness in color over the entire input video signal level with high accuracy, and further, the projection direction and the installation state of the projection type image display apparatus. It is an object of the present invention to provide a projection-type image display device capable of performing correction corresponding to the above.

[0010]

In order to solve the above problems, the projection type image display apparatus of the first invention of the present invention is
A memory device that stores digital data for correcting unevenness in the brightness of a projected image on a screen for a video signal of at least one color of R, G, and B, and a correction calculation that modulates the video signal with the digital data read from the memory device. Circuit and A to convert video signal from analog to digital
An A / D converter and a D / A converter for converting the corrected image signal from digital to analog.

The projection type image display apparatus according to the second aspect of the present invention stores digital data for correcting luminance unevenness of a projected image on a screen for a video signal of at least one color of R, G and B, and A memory device capable of specifying a read start position and a read direction; a correction arithmetic circuit for modulating a video signal with digital data read from the memory device; an A / D converter for converting the video signal from analog to digital; A D / A converter for converting the calculated video signal from digital to analog is provided.

[0012]

According to the present invention, since the input video signal is modulated by both the amplitude and the direct current level by the above-mentioned structure, the luminance unevenness corresponding to the wide range of the input video signal from the low signal level region to the high signal level region is obtained. It is possible to correct color unevenness.

Further, even when the unevenness of the projected image changes due to the projection direction or the installation state, by reading the correction data of the memory device by designating the read position and the read direction of the address of the memory device for storing the correction data,
It is possible to correct luminance unevenness and color unevenness corresponding to changes in the position of unevenness.

[0014]

【Example】

(Embodiment 1) First, a projection type image display apparatus according to an embodiment of the first aspect of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a projection type image display device in an embodiment of the first invention of the present invention.

In FIG. 1, reference numeral 1 denotes a video signal input terminal, and 9
Is a signal processing circuit, 11 is an A / D converter, 2 is R, G, B
Corresponding to the three-phase clock input terminal, 3 is an address counter, 4 is a memory device for storing correction data, 5 is a decoding circuit, 10 is a correction arithmetic circuit, and 6a is a correction arithmetic circuit for multiplying an input video signal by the correction data. A digital multiplier for performing 6b is a digital adder for adding the input video signal and the correction data, 12 is a D / A converter, and 7 is a drive circuit for the display element (the display element is not shown).

The operation of the projection type image display apparatus having the above-mentioned structure according to the first embodiment of the present invention will be described below.

The video signal input from the video signal input terminal 1 is converted by the signal processing circuit 9 into R, G, B primary color video signals. The correction data of R, G, B obtained by dividing the projection screen into a checkerboard pattern and measuring the color unevenness in each region is input to the memory device 4 in advance. The address counter 3 generates an address signal corresponding to a position where the projection screen is divided from the synchronization signal, and inputs this address signal to the memory device 4 to cause the memory device 4 to generate R, G corresponding to the position on the projection screen. , B correction data is read. The digital data read from the memory device 4 is input to the correction arithmetic circuit 10 including the digital multiplier 6a and the digital adder 6b, and the output signal of the signal processing circuit 9 is digitized by the A / D converter 11 R,
At least one color of the G and B primary color video signals is multiplied by the correction data by the digital multiplier 6a and added by the correction data by the digital adder 6b, and the output signal is analogized by the D / A converter 12, By modulating both the amplitude and DC level of the signal, accurate correction corresponding to a wide range of input video signal levels from low signal level to high signal level is performed.

FIG. 2 is a conceptual diagram showing the principle of luminance correction by modulating the amplitude and DC level of a video signal.

In FIG. 2, the horizontal axis represents the input signal level and the vertical axis represents the brightness of the projection screen. A case will be described in which the curve a is the input signal-luminance characteristic of the projection-type image display device before the correction and the curve is corrected like the ideal curve c.

First, when the amplitude of the curve a is modulated, it is possible to correct the characteristic such that the slope matches the ideal curve c as shown by the curve b.

Further, when the direct current level is modulated on the curve b, the characteristics can be matched with the ideal curve c, and an appropriate input signal-luminance characteristic can be obtained for all input signal levels. By performing this for all areas on the screen, a projection screen without uneven brightness can be obtained. In addition, by correcting at least one of R, G, and B and matching the characteristics with other colors, it is possible to remove color unevenness on the screen.

FIG. 3 is a block diagram for explaining a method of creating correction data input to the memory device 4. A raster signal is input from the video signal input terminal 1 while changing the signal level, and an image is projected on the screen 21 by the projection type image display device. The screen 2 by the imaging unit 22
The brightness data of R, G, and B on 1 is acquired. The screen 21 is divided into several hundred areas in a grid pattern in advance, and the uneven brightness and the uneven color are corrected for each area. The correction data creation unit 23 first calculates a representative value of the R, G, B brightness data for each area from the captured R, G, B brightness data.

Further, in order to perform the correction as described above with reference to FIG. 2, the correction data and the DC level necessary for performing the amplitude modulation of the video signal for each corresponding area from the representative values of the brightness data. Both of the correction data necessary for the modulation of R are created for R, G, and B. The correction data for modulating the amplitude and DC level of the created video signal is output from the correction data output terminal 24 to the memory device 4.

FIGS. 4 and 5 are block diagrams and timing charts for explaining writing and reading of correction data to and from the memory device 4 corresponding to R, G, and B primary color video signals using a three-phase clock signal. Is.

In FIG. 5, R1, G1, and B1 are correction data for the first area obtained by dividing the projection screen, and R2, G2, and B2.
Indicates the correction data of the second area located next to the first area on the projection screen, and R1.
The correction data are stored in the order of G1, B1, R2, G2, B2 .... When the address signal output from the address counter 3 is input to the memory device 4, the memory device 4 outputs R, G, and B correction data.
The output correction data becomes a data string like the output memory data of FIG.

As shown in FIG. 4, these memory data are input to the decoding circuit 5. Three-phase clock generator 3
An original clock as shown in FIG. 1 to FIG. 5 is divided into three, and three-phase clock signals of R, G, and B in which the phases of the respective clocks are shifted by 1/3 are input to the decoding circuit 5, and R, G, By reading the memory data at the rising timing of each three-phase clock of B, the correction data of each of R, G, and B is output from the output terminals 32a, 32b, and 32c. By using the three-phase clock in this way, the memory device 4 can be shared for the R, G, and B primary color signals.

As described above, according to the present embodiment, the video signal is modulated by both the amplitude and the DC level, so that the uneven brightness and the uneven color are widely corrected from the low signal level region to the high signal level region. It becomes possible. Also R,
By using the three-phase clock signal corresponding to each of the G and B video signals, the number of memory devices can be reduced and the economical efficiency can be improved.

(Embodiment 2) FIG. 6 is a block diagram of a projection type image display apparatus according to an embodiment of the second invention of the present invention. The same parts as those of the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

In FIG. 6, 3 is an address counter, 4
Reference numeral 1 is a read start position input terminal for designating the read position of the memory device 4, and 42 is an up-count / down-count designating input terminal for designating the read direction of the memory device 4.

The operation of the projection type image display apparatus in the second embodiment of the present invention having the above construction will be described.

The video signal input from the video signal input terminal 1 is converted into R, G, B primary color signals by the signal processing circuit 9. The correction data of R, G, B obtained by dividing the projection screen into a checkerboard pattern and measuring the color unevenness in each region is input to the memory device 4 in advance.

In the address counter 3, the read start address of the memory device 4 is designated by the read start position input terminal 41, and the read direction of the memory device 4 is designated by the up count / down count designation input terminal 42.

Further, the address counter 3 generates an address signal corresponding to a position where the projection screen is divided from the synchronization signal, and inputs this address signal to the memory device 4 to correspond to the position on the projection screen from the memory device 4. The corrected R, G, and B correction data are read out.

The memory device 4 stores correction data corresponding to the positions of the R, G, and B luminance unevenness on the screen in advance. When the projection type image display device is switched between front projection and rear projection, The uneven pattern is reversed in the horizontal direction. In order to deal with this, by controlling the input signals of the read start position input terminal 41 and the up count / down count designation input terminal 42, the order of the addresses for reading the correction data from the memory device 4 is inverted in the horizontal direction. .

Similarly, when the installation state of the projection type image display apparatus such as floor-standing or ceiling-mounting is switched, the unevenness pattern is inverted in the vertical direction, so the read start position input terminal 41 and the up-count / down-count designation input terminal 4
By controlling the signal No. 2, the order of the addresses for reading the correction data from the memory device 4 is inverted in the vertical direction.

As described above, the correction data corresponding to the uneven brightness and the uneven color of the projection screen, which change depending on the projection system and the installation state, are sequentially read from the memory device 4.

Digital data read from the memory device 4 is input to a correction arithmetic circuit 10 composed of a digital multiplier 6a and a digital adder 6b, and an output signal of the signal processing circuit 9 is digitized by an A / D converter 11 to obtain R. , G, B
Digital multiplier 6 for at least one color of the primary color signal of
By multiplying the correction data by a and the correction data by the digital adder 6b, the output signal is analogized by the D / A converter 12, and both the amplitude and the DC level of the video signal are modulated, Performs accurate correction for a wide range of input video signal levels from low signal level to high signal level.

As described above, according to the present embodiment, by modulating the video signal with both the amplitude and the DC level, the luminance corresponding to the wide range of the input video signal from the low signal level region to the high signal level region is obtained. It is possible to correct unevenness and color unevenness. Furthermore, by using an address counter that can determine the read start address of the memory device with the read start position input terminal and the read direction with the up count / down count designation input terminal, It is possible to perform correction corresponding to the switching of the projection direction such as the front direction and the rear direction of the model image display device, and the switching of the device installation state such as floor mounting and ceiling suspension.

Further, by using a three-phase clock signal corresponding to each of the R, G and B video signals, the number of memory devices can be reduced and the economical efficiency can be improved.

[0040]

As described above, according to the projection-type image display device of the present invention, a memory device for storing data for correcting unevenness in brightness and color of projected images on the R, G, and B projection surfaces is provided. An A / D converter for digitizing a video signal, and correction data for digital data read from the memory device for at least one color of the R, G, B video signals output from the A / D converter. Supports a wide range of input video signal levels from a low signal level region to a high signal level region by including a correction operation circuit that performs both multiplication and addition and a D / A converter that converts the output of the correction operation circuit into an analog signal. It is possible to correct uneven brightness and uneven color.

Further, a memory device in which correction data is repeatedly stored in the order of R, G, B, a three-phase clock generator, R,
By providing each of the G and B latch units, the number of memory devices can be reduced, and it is possible to correct color unevenness and brightness unevenness at low cost.

Further, the read start address of the memory device is determined by the read start position input terminal, the read counter is determined by the up count / down count designation input terminal, and the projected image on the projection plane of each of R, G and B is displayed. A memory device that stores data that corrects uneven brightness and color, and A / that digitizes video signals.
A correction operation for performing both multiplication and addition with the correction data for at least one color of the R, G, and B video signals output from the A / D converter with the D converter and the digital data read from the memory device. By providing a circuit and a D / A converter that converts the output of the correction operation circuit into an analog signal, correction of luminance unevenness and color unevenness corresponding to a wide range of input video signal levels from a low signal level region to a high signal level region can be performed. It will be possible.

Further, in the projection type image display device, it is necessary to switch the projection direction such as the front direction and the back direction, and to switch the device installation state such as floor mounting or ceiling mounting, but it is possible to make a correction corresponding to this. . Further, by providing a memory device that stores repetitive correction data in the order of R, G, B, and a decoding circuit for separating the three-phase clock, R, G, B, it is possible to reduce the number of memories and at low cost.
It is possible to correct color unevenness and brightness unevenness.

[Brief description of drawings]

FIG. 1 is a block diagram of a projection-type image display device according to an embodiment of the first invention of the present invention.

FIG. 2 is a conceptual diagram showing the principle of brightness correction by modulating the amplitude and DC level of a video signal.

FIG. 3 is a block diagram for explaining a method of creating correction data to be input to a memory device.

FIG. 4 is a block diagram for explaining a method of reading from a memory device when using a three-phase clock.

FIG. 5 is a timing diagram illustrating a method of reading from a memory device when using a three-phase clock.

FIG. 6 is a block diagram of a projection-type image display device in one embodiment of the second invention of the present invention.

FIG. 7 is a principle diagram of a conventional projection-type image display device.

[Explanation of symbols]

 1 video signal input terminal 2 three-phase clock input terminal 3 address counter 4 memory device 5 decoding circuit 6a digital multiplier 6b digital adder 7 drive circuit 8 video signal output terminal 9 signal processing circuit 10 correction arithmetic circuit 11 A / D converter 12 D / A converter 41 Read start position input terminal 42 Up count / down count designation input terminal

Claims (6)

[Claims] 1. A memory device storing digital data for correcting uneven brightness of a projected image on a screen for a video signal of at least one color of R, G, and B, and the video signal is modulated by the digital data read from the memory device. And an A / D converter for converting a video signal from analog to digital, and a D / A converter for converting the corrected and calculated video signal from digital to analog,
A projection-type image display device characterized by modulating both the amplitude and DC level of a video signal for at least one color of the R, G, B video signals. 2. Modulation of the amplitude and DC level of the video signal,
2. The projection type image display device according to claim 1, wherein each of them is performed by using a multiplication circuit and an addition circuit. 3. For reading from a memory device,
The projection-type image display device according to claim 1, wherein a three-phase clock signal corresponding to each of the R, G, and B video signals is used. 4. A memory device for storing digital data for correcting luminance unevenness of a projected image on a screen for a video signal of at least one color of R, G, B and capable of designating a read start position and a read direction. A correction arithmetic circuit that modulates a video signal with digital data read from a memory device, an A / D converter that converts the video signal from analog to digital, and a D / A that converts the corrected video signal from digital to analog Equipped with a converter,
A projection-type image display device characterized by modulating both the amplitude and DC level of a video signal for at least one color of the R, G, B video signals. 5. Modulation of the amplitude and DC level of the video signal,
5. The projection type image display device according to claim 4, wherein each of them is performed using a multiplication circuit and an addition circuit. 6. Regarding reading from a memory device,
The projection type image display device according to claim 4, wherein a three-phase clock signal corresponding to each of the R, G, and B video signals is used.