JPH0764529A - Multi-display device - Google Patents

Abstract

PURPOSE:To perform the whole adjustment only by adjusting the picture quality of a reference core by detecting reference voltages of black and white levels from the cathode stage of the CRT of a core, and performing feedback control on each core so as to make the voltages of black and white levels coincide with that of the reference core. CONSTITUTION:The voltage amplitude of a video signal to which a reference signal is inserted is decided at a contrast control circuit 8, and the black level of it at a luminance control circuit 9, and it is voltage-amplified at a CRT driving circuit 10, and is applied to the cathode of the CRT 11, then, an image can be displayed. While, the voltage of the cathode is inputted to a comparison control circuit 18 via detecting resistors 12, 13, and the white level and the black level detected from the cathode of each core can be taken out. The feedback control is applied to the contrast control circuit 8 and the luminance control circuit 9 of each core so as to make the white level and the black level of each core coincide with that of the reference core 1d setting the reference core as, for example, 1d. In this way, the black level and the white level of each core can always coincide with that of the reference core.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Multi-display device
Adjusting the brightness and contrast of the entire multi-display.

[0002]

2. Description of the Related Art A multi-display that stacks up a TV set to form one screen has a shorter depth and relatively higher brightness than a large screen of front projection type or rear projection type. It has become popular. Individual television sets (hereinafter referred to as cores) have been put into practical use as CRT-type direct-viewing type and projection type. Among them, the projection type is often used because the screen is flat and the joints between the cores are thin compared to the direct-view type.

Some multi-displays include, for example, four cores 1a to 1d as shown in FIG. FIG. 3 is a diagram showing a system configuration example of the multi-display in FIG. 40 is an image enlarging device, 14a-
14d and 41 are video signal input terminals, and 1a to 1d are cores. A video signal is output from the image enlarging device 40 and added to the core 1a in the upper left portion so that the first half of the horizontal and vertical scanning periods of the normal video signal is displayed on the full screen. Similarly, in the core 1b at the upper right, the image enlarging device 40 is arranged so that the latter half of the horizontal scanning period and the first half of the vertical scanning period of the video signal are displayed in full screen.
The video signal output is added from. Similar processing is performed on the cores 1c and 1d.

Here, the brightness and contrast of the entire multi-display including the cores 1a to 1d are strictly adjusted for each core by a serviceman so that there is no brightness difference between the cores at the time of initial adjustment, and the adjusted values are set. Is fixed. For this reason, it is not possible for the user to freely adjust the brightness, contrast, hue, etc., as in a single TV set. On the other hand, in Japanese Patent Laid-Open No. 4-285992, a photodetector detects a reference signal inserted in an overscan period of a video signal,
The detection level of each core is controlled to match the detection level of the reference core, and the overall contrast is changed by adjusting the contrast of the reference core.

[0005]

In the above-mentioned prior art, only the white level is detected and the contrast is adjusted, but the brightness adjustment and the hue adjustment are not particularly mentioned.

[0006]

Therefore, in the present invention, the reference signal voltages of the black level and the white level are detected from the cathode stage of the CRT of the core, and the detected black level voltage and the white level voltage of each core are used as the reference. Feedback control each core to match that of the core.

[0007]

[Operation] As a result, the contrast, brightness, and
The contrast, brightness, hue, and image quality of the entire multi-display can be adjusted simply by adjusting the hue and image quality.

[0008]

FIG. 1 shows the first embodiment of the present invention. Here, in order to simplify the description, a case where four cores as shown in FIG. 3 are used will be described as an example.

FIG. 1 includes cores 1a to 1d, a white level reference power supply 2, a black level reference power supply 3, a timing generation circuit 4, a contrast adjustment power supply 5, a brightness adjustment power supply 6, and a comparison control circuit 18. The cores 1a to 1d include a reference signal insertion block 19, a contrast control circuit 8, a brightness control circuit 9,
It comprises a CRT (cathode ray tube) drive circuit 10 and a CRT 11.

The operation is as follows.

The core 1a ...
Reference signal insertion S in the reference signal insertion block 19 of 1d
W7 is switched and connected to terminals 15, 16 and 17. A white level reference power supply 2 is applied to the terminal 15, a black level reference power supply 3 is applied to the terminal 17, and an external video signal is applied to the terminal 16. As a result, as shown in FIG. 4, a reference signal having a white level and a black level is inserted into the contrast control circuit 8 to form a video signal, for example, inserted in the overscan period. Since the white level reference power supply 2 and the black level reference power supply 3 are commonly applied to each core, the same reference signal is inserted into each core.

The video signal into which the reference signal has been inserted has the voltage amplitude determined by the contrast control circuit 8 and the black level determined by the brightness control circuit 9 and voltage-amplified by the CRT (cathode ray tube) drive circuit 10 to produce the cathode of the CRT 11. Applied to the CR
An image is displayed by the light emitted from T11.

On the other hand, the voltage of the cathode is detected by the detection resistors 12, 1.
3 is input to the comparison control circuit 18. The comparison control circuit 18 extracts the white level and the black level detected from the cathode of each core. Then, the reference core is, for example, 1d
As a result, the contrast control circuit 8 and the brightness control circuit 9 of each core are feedback-controlled so that the white level and the black level of each core match those of the reference core 1d. As a result, the black level and the white level of each core always match the black level and the white level of the reference core.

For example, as shown in FIG. 5, the comparison control circuit 18 is mainly composed of a microcomputer 70 and A / D converters 71a, 7a.
1b, 71c, 71d, and D / A converters 73a, 7
4a, 73b, 74b, 73c, 74c.

A / D converters 71a, 71b, 71
c, 71d, core 1a, core 1b, core 1c, core 1
A video signal detected through the resistors 12 and 13 is input from the cathode of d. A / D converters 71a, 71b,
The conversion timings of 71c and 71d are, of course, the reference signal insertion positions of the white level and the black level, and the conversion timing pulse is, for example, horizontal / vertical synchronization (Hsync, Vsy).
nc) may be an interrupt signal of the microcomputer 70 and may be generated by software. Of course, a dedicated logic circuit may be used. This A / D converter 71a, 71b, 71
The white level and the black level are A / D converted by c and 71d and taken into the microcomputer 70. Microcomputer 70 using FIG.
The concept of the operation of is shown.

There is information on the white level and the black level of the core 1a, the core 1b, the core 1c, and the core 1d fetched by the microcomputer 70. Of these, the black level information is directly input to the comparators 22a, 22b, 22c. The white level and the black level are taken as a difference to obtain the amplitude level information from the comparator 21.
a, 21b, 21c. Here, the information of the black level and the amplitude level of the core d is compared with the comparators 22a, 22b,
It becomes the reference information of 22c, 21a, 21b, and 21c.
That is, the output of the comparators 22a, 22b, 22c becomes the black level control information of each core, and the comparators 21a, 21b
The outputs of b and 21c become control information of the amplitude level of each core. The black level control information controls the brightness and the amplitude level information controls the contrast. Of course, what has been described so far is the software processing of the microcomputer 70. Actually, as shown in FIG. 5, for example, the black level control information (corresponding to the output of the comparator 22a) of the core 1a is D
The A / A converter 74a converts the analog voltage to control the brightness control circuit 9 of the core 1a, and the amplitude level control information (corresponding to the output of the comparator 21a) is supplied to the D / A converter 7.
It is converted into an analog voltage by 3a and controls the contrast control circuit 8 of the core 1a. The same applies to the cores 1b and 1c.

Here, the control voltage of the contrast control circuit 8 and the brightness control circuit 9 are changed by the contrast adjusting power source 5 and the brightness adjusting power source 6 to change the white level and the black level of the reference core 1d. At this time, by the above feedback control,
The black level and white level of each core will change at the same time. That is, it is possible to change the contrast and brightness of the entire multi-display simply by changing the contrast and brightness of the reference core.

FIG. 7 shows a second embodiment of the present invention. The feature of this embodiment is that the hue of the entire multi-display can be changed. Similar to the first embodiment, a case where four cores as shown in FIG. 2 are used will be described as an example to simplify the description.

FIG. 7 shows cores 101a to 101d, white level reference power supply 2, black level reference power supply 3, timing generation circuit 4, voltage amplitude adjusting power supplies 105R, 105G and 105.
B, DC level adjusting power supply 106R, 106G, 106
B is composed of a comparison control circuit 118. Cores 101a-10
1d is a reference signal insertion block 119R, 119G, 1
19B, voltage variable amplifiers 108R, 108G, 108
B, clamp circuits 109R, 109G, 109B, CR
T (cathode ray tube) drive circuit 110R, 110G, 110
B, CRT 111R, 111G, 111B.

The operation is as follows.

The input of the cores 101a to 101d is, for example, R
Let's say GB. Terminals 114aR, 114aG, 114aB
The reference signals of the RGB image signals applied to the reference signals are respectively inserted in the reference signal insertion blocks 119R, 119G, and 119B. The details of the reference signal insertion block are the same as those in the first embodiment, and the description thereof will be omitted.

The RGB video signals into which the reference signals are inserted are voltage variable amplifiers 108R, 108G, 10 respectively.
The voltage amplitude at 8B is clamp circuits 109R, 109G,
The DC level is determined by 109B, the voltage is amplified by the CRT (cathode ray tube) drive circuits 110R, 110G, 110B, the voltage is applied to the cathodes of the CRTs 111R, 111G, 111B, and the images are emitted from the CRTs 111R, 111G, 111B. Is displayed.

On the other hand, the cathode voltage is the detection resistance 12R,
It is input to the comparison control circuit 118 via 12G, 12B, 13R, 13G and 13B. The comparison control circuit 118 extracts the white level and the black level of each RGB detected from the cathode of each core. The reference core is, for example, 1d, and the voltage variable amplifiers 108R, 108G, 108B and the clamp circuit 10 of each core are arranged so that the white level and the black level of each core RGB match that of the reference core 1d.
Feedback control is performed on 9R, 109G, and 109B.
Therefore, the white level and the black level of each core RGB always match the white level and the black level of the reference core RGB.

The comparison control circuit 118 may be, for example, the circuit shown in FIG. Needless to say, the number of A / D converters and D / A converters is increased so as to correspond to the RGB signals of each core. The operation of the circuit itself is the same as that of the first embodiment, so its explanation is omitted.

Here, for example, the voltage amplitude adjusting power supply 105
The control voltage of the variable voltage amplifier 108R is changed by R, and the voltage amplitude of R of the reference core 1d is changed. At this time, the voltage amplitude of R of each core also changes at the same time by the feedback control. That is, the hue of the entire multi-display can be changed only by changing the RGB voltage amplitudes of the reference core. It goes without saying that the same operation as the voltage amplitude can be performed on the DC levels of RGB.

FIG. 8 shows a third embodiment of the present invention. The feature of this embodiment is that the image quality of the entire multi-display is adjusted. The circuit configuration of FIG. 8 is largely different from that of FIG. 1 in that the image quality adjustment circuit is feedback-controlled.

Differences from FIG. 1 will be described. The image signal into which the reference signal is inserted by the reference signal insertion block 19 is applied to the CRT 11 through the image quality adjustment circuit 20, the aperture correction, the contrast control circuit 8, the brightness control circuit 9, and the CRT drive circuit 10.

The reference signal detected from the cathode through the resistors 12 and 13 is input to the comparison control circuit. The configuration of the comparison control circuit 218 may be the same as that shown in FIG. 5, for example. Of course, since there is only one output, it goes without saying that the number of A / D converters should be one for each core. On the other hand, since the reference signal detected from the cathode through the resistors 12 and 13 has been subjected to aperture correction by the image quality adjustment circuit, it has a waveform with overshoot ΔVo and undershoot ΔVu as shown in FIG. In the A / D converters 71a, 71b, 71c, 71d of the comparison control circuit 218, this reference signal is A / D converted at the timing of the A / D conversion pulse of FIG. The microcomputer 70 obtains the overshoot ΔVo and the undershoot ΔVu from the A / D converted values. Then, the image quality adjustment circuit 20 of each core is feedback-controlled so that the overshoot ΔVo and the undershoot ΔVu of each core match those of the reference core.

Therefore, the image quality of each core always matches the image quality of the reference core.

When the control voltage of the image quality adjusting circuit 20 is changed by the image quality adjusting power source 21, the overshoot ΔVo and the undershoot ΔVu of the reference core 1d are changed. At this time, the amount of overshoot and undershoot of each core also changes at the same time due to the feedback control. That is, the image quality of the entire multi-display can be adjusted only by adjusting the image quality of the reference core.
Although only the horizontal direction is described in the present embodiment, the waveform of the reference signal shown in FIG. 10 may be used for the vertical direction, for example.

For example, the reference signal is inserted for 5 horizontal scanning cycles, and the A / D conversion is performed by the A / D conversion pulse 1 for each horizontal scanning cycle.
If it is performed with 1 to 8 l, the difference between 3 l and 5 l becomes the overshoot ΔV. As in the case of the horizontal direction, the image quality adjustment circuit is feedback-controlled so that the ΔV of the reference core matches that of each core, and by changing the ΔV of the reference core, the image quality of the entire vertical multi-display can be changed. it can. Needless to say, the image quality adjusting circuit at this time uses a circuit capable of adjusting the vertical overshoot or the like.

Although the multi-display using the CRT type core has been described above as an example, the same effect can be realized in the multi-display including the core using the liquid crystal panel. At this time, the drive voltage of the liquid crystal panel may be detected instead of the CRT drive voltage. In addition to the multi-display consisting of 4 cores, 6 or 12
It goes without saying that any number of cores such as 24 and 24 may be used.

[0033]

According to the present invention, it is possible to easily perform contrast adjustment, brightness adjustment, hue adjustment, and image quality adjustment of the entire multi-display.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing installation of an image display device.

FIG. 3 is a block diagram showing a configuration of a multi-display.

FIG. 4 is a timing diagram showing a reference signal.

5 is a configuration diagram of a comparison control circuit 18. FIG.

FIG. 6 is an explanatory diagram of an operation concept of the microcomputer 70.

FIG. 7 is a diagram showing a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a third embodiment of the present invention.

FIG. 9 is a waveform diagram of a reference signal for explaining the operation of the third embodiment.

FIG. 10 is a waveform diagram of a reference signal for explaining the operation of the third embodiment.

[Explanation of symbols]

1a to 1d, 101a to 101d, 201a to 201d
... Core, 18, 118, 218 ... Comparison control circuit, 2 ... White level reference power supply, 3 ... Black level reference power supply, 19 ... Reference signal insertion block, 8 ... Contrast control circuit, 9 ... Luminance control circuit, 10, 110R, 110G, 110B ... CR
T drive circuit, 11, 111R, 111G, 111B ... C
RT, 4 ... Timing generation circuit, 5 ... Contrast adjustment power supply, 6 ... Luminance adjustment power supply, 108R, 108G, 1
08B ... Voltage variable amplifier, 109R, 109G, 109
B ... Clamp circuit, 105R, 105G, 105B ... Voltage amplitude adjusting power supply, 106R, 106G, 106B ... D
C level adjustment power supply, 7 ... Reference signal insertion SW, 40 ...
Image enlarging device, 70 ... Microcomputer, 71a, 71b, 71
c, 71d ... A / D converter, 73a, 73b, 73
c, 73d, 74a, 74b, 74c, 74d ... D / A
converter.

Claims (3)

[Claims] 1. A multi-display device which displays a single image by combining a plurality of image display devices (cores), and which corresponds to the contrast and brightness control of each core, during a blanking period of a video signal or overscan. A reference signal insertion circuit for inserting a reference signal in a period, a detection circuit for detecting the reference signal of each core after contrast and brightness control, and an arbitrary one of the cores as a reference core, A comparison control circuit that compares the reference signal extracted after the contrast and brightness control of the reference core with the reference signal extracted after the contrast and brightness control of each core except the reference core, and outputs the comparison result; A contrast and brightness control circuit for controlling the contrast and brightness of each core except the reference core at the output of the comparison control circuit; A multi-display in which a contrast / brightness simultaneous control circuit including a contrast / brightness control circuit for controlling the contrast / brightness of the quasi-core and a control circuit for controlling the contrast / brightness control circuit of the reference core is provided. apparatus. 2. A multi-display device for displaying a single image by combining a plurality of image display devices (cores), in which RGB amplitude control and RGB DC level control of each core are performed during a blanking period of a video signal. Alternatively, in a period corresponding to overscan, a reference signal insertion circuit that inserts a reference signal, a detection circuit that detects the reference signal of each core separately for RGB after RGB amplitude control and RGB DC level control, and among the cores, An arbitrary one core is used as a reference core, and an RGB reference signal extracted after RGB amplitude control and RGB DC level control of the reference core, and RGB amplitude control and RGB DC level control of each core except the reference core are extracted. The reference core is divided by an output of the comparison control circuit that compares the RGB reference signal and outputs the result of the comparison. An RGB amplitude and RGB DC level control circuit that controls the RGB amplitude and RGB DC level of each core; an RGB amplitude and RGB DC level control circuit that controls the RGB amplitude and RGB DC level of the reference core; And a control circuit for controlling the RGB amplitude and RGB DC level control circuit of, and an RGB amplitude and RGB DC level simultaneous control circuit comprising the multi-display device. 3. A multi-display device for displaying a single image by combining a plurality of image display devices (cores), in a blanking period of a video signal or during a period corresponding to overscan before image quality control of each core. A reference signal insertion circuit for inserting a reference signal, a detection circuit for detecting the reference signal of each core after image quality control, and an arbitrary one of the cores as a reference core, and an image quality of the reference core A comparison control circuit for comparing the reference signal taken out after the control and the reference signal taken out after the image quality control of each core except the reference core and outputting the result of the comparison, and an output of the comparison control circuit, An image control circuit that controls the image quality of each core except the reference core, an image quality control circuit that controls the image quality of the reference core, and a control circuit that controls the image quality control circuit of the reference core. Multi-display apparatus characterized in that a simultaneous control circuit.