JP2000163007A - Liquid crystal projection type multi-screen display device and drive control circuit for the same device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the luminance difference among respective liquid crystal display devices to be caused by the variation in light outputs and secular changes of respective lamp light sources of a liquid crystal projection type multi-screen display device. SOLUTION: In the liquid crystal projection type display device in which plural liquid crystal display devices are arranged, this device is provided with a means 106 generating a signal for measurement (d) for displaying a picture for measurement for measuring the luminance of screens, a luminance detecting means 107 for detecting the luminance of the screens, a storage means 109 storing a luminance detection signal (f) and a luminance control means 111 outputting the signal of the lowest luminance among luminance control signals (a) from other display devices and the luminance detection signal (f) as a reference luminance signal (e), this device is made so as to control the luminace of a liquid crystal display part 105 while making the reference luminace signal (e) a luminance signal becoming the reference of a signal processing means 103 and a liquid crystal driving means 104 and also to perform luminance controls of the whole of the multi-screen display device by outputting the reference luminance signal (e) of itself to other display devices as the luminance control signal (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection type multi-plane display device suitable for displaying a signal output from a single or a plurality of signal sources in an enlarged manner by using a plurality of liquid crystal projection type display devices. Related to a drive control circuit.

[0002]

2. Description of the Related Art In a multi-screen display system using a plurality of display devices, when a signal output from a signal source is enlarged and displayed, the brightness, contrast, and contrast between adjacent display devices are reduced.
A slight difference in image quality, such as hue, is one factor in lowering the image quality of the enlarged and displayed image.

[0003] In particular, in a display device using a cathode ray tube,
When a high-luminance image is displayed for a long time, burn-in of the cathode-ray tube occurs, and in order to prevent this, luminance control for lowering the luminance and displaying an image is usually performed. However, when such luminance control is performed, when a partially high-luminance image is enlarged and displayed by the multi-screen display system, the display device that enlarges and displays the high-luminance portion reduces the luminance by the above-described luminance control. As a result, a partial image is displayed, and as a result, the brightness differs between a display device adjacent to the display device and the brightness of which is not reduced, and the brightness differs between a part of the enlarged display image and another part. As shown in Japanese Patent Application Laid-Open No. 08-228319, another display device connected to a brightness control system of an adjacent display device and connected to a brightness control signal obtained by one of the display devices. And by controlling the brightness of the connected display devices as a set, the difference in brightness between adjacent display devices is suppressed.

The control of image quality between adjacent display devices is effective when a CRT display device is used as the display device.

[0005] However, when a plurality of liquid crystal projection display devices are used as a display device constituting a multi-screen display system, the light source for a liquid crystal projection television and its cooling technology are described in Toshiba Review Vol. 52 No. 6 (1997). As shown, the maximum luminance depends on the lamp light source light output, the light output has a specific variation, and the lamp light source light output decreases with the elapsed lighting time, and is halved in approximately several thousand hours. It is known.

[0006] Such a decrease in lamp light source light output cannot be detected by replacing it with another physical quantity like the beam current versus luminance characteristic of a CRT display device.
It is difficult to output to the outside like a conventional brightness control signal.

[0007] From the above factors, in the prior art described above, when a liquid crystal projection display device is used as a display device,
It is not possible to reduce the difference in luminance due to the variation in the light output of the lamp light source of each display device and the aging thereof, leading to the deterioration of the image quality of the enlarged and displayed image.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal projection type multi-surface display device capable of reducing the variation in the light output of the lamp light source of the liquid crystal projection display device and the difference in luminance caused by aging. An object of the present invention is to provide a drive control circuit of the device.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a liquid crystal projection type display device in which a large screen composed of the display screens of the respective display devices is formed to form a signal source. A liquid crystal projection type multi-screen display device that displays an image of a signal output from the LCD generates a measurement signal for displaying a specific measurement image in order to measure screen brightness on each liquid crystal projection type display device. Signal generating means, a luminance detecting means comprising a photoelectric cell for detecting the luminance of the screen on which the measurement image is displayed, a storing means for storing the luminance detecting signal detected by the luminance detecting means, Brightness control means for outputting the lowest brightness signal of the brightness control signal from the device and its own brightness detection signal as a reference brightness signal, Controlling the luminance of the liquid crystal display section as a reference luminance signal of the signal processing means and the liquid crystal driving means, and outputting the reference luminance signal of itself to another display device as a luminance control signal, thereby controlling the entire multi-screen display device. Brightness control was performed.

Further, according to the present invention, a plurality of liquid crystal projection display devices are arranged to form a large screen including the display screen of each of the display devices, and to display an image of a signal output from a signal source. In a liquid crystal projection type multi-panel display device, a signal generating means for generating a measurement signal for displaying a specific measurement image for measuring screen brightness on the display device, and a screen for displaying the specific measurement image Brightness detection means for detecting brightness,
Storage means for storing a luminance detection signal detected by the luminance detection means, and luminance control means for outputting, as a reference luminance signal, a signal having the lowest luminance among the luminance control signals from the individual display devices and its own luminance detection signal Controlling the brightness of the light source using the reference brightness signal as a reference signal of the brightness of the light source, and outputting the own reference brightness signal to another display device as a brightness control signal, thereby controlling the brightness of the entire multi-screen display device. To do.

According to the present invention, each display device is set to a luminance measurement state different from a normal image display state, and a specific measurement image such as a white signal is displayed on the entire screen.
The screen brightness in this state is measured by a brightness detection device including a photoelectric cell provided near the screen, and the brightness detection signal is recorded in a storage element. As a result, the screen luminance detection signal of each display device, that is, the luminance measurement result is recorded in the storage element of each display device.

Further, in a normal image display state, a signal having the lowest luminance is selected from a luminance control signal from each display device and a result of measuring the screen luminance of the own device, and the selected signal is set as a reference luminance signal. Alternatively, the luminance of the light source is controlled. Further, it outputs its own reference luminance signal as a luminance control signal to the outside, and each display means performs a luminance control based on the luminance control signal from another display device and its own luminance measurement result to perform a multi-screen display device. Performs overall brightness control.

As described above, a plurality of liquid crystal projection display devices are arranged to form a large screen including the display screen of each of the display devices, and a liquid crystal projection display device displays an image of a signal output from a signal source. In a multi-panel display device, it is possible to reduce the luminance difference between the individual display devices and to improve the image quality of an enlarged and displayed image.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a liquid crystal projection display device (hereinafter, simply referred to as a display device in many cases) constituting a multi-screen display device according to a first embodiment of the present invention. In FIG. 1, a display device 1
00 denotes an enlargement processing circuit 101 and a signal switching SW 102
, A signal processing circuit 103, a liquid crystal driving circuit 104, a liquid crystal display section 105, a signal generating circuit 106, a light detecting element 107, a light detecting circuit 108, a storage circuit 109, a control circuit 110, and a brightness control circuit. Circuit 111 and brightness control SW
112, an input video signal input terminal T1, and a luminance control signal input / output terminal T2.

The display device according to the present invention has two operation states, a normal state for displaying a normal image and a screen luminance measurement state for measuring screen luminance.

The enlargement processing circuit 101 selects a signal of a portion to be displayed for each display device from the input image signal,
A function of enlarging this signal as a signal of the display device is provided.

A signal switching SW 102 selects an image signal from the enlargement processing circuit 101 in a normal state for displaying a normal image, and measures a specific luminance from the signal generation circuit 106 in a screen luminance measurement state for measuring screen luminance. It has a function of selecting a measurement signal for displaying an image for use and transmitting one of the signals to the subsequent stage.

The signal processing circuit 103 includes a signal switching SW 10
2 has a function of processing the image signal or the measurement signal sent from 2 into a signal suitable for displaying on the liquid crystal display unit.

The liquid crystal driving circuit 104 includes the signal processing circuit 10
3 has a function of driving the liquid crystal by the image signal or the measurement signal sent from the control unit 3.

The liquid crystal display unit 105 is a display unit in which a plurality of liquid crystal display elements are arranged in a matrix, and displays an image for each display device.

The signal generating circuit 106 generates a measurement signal for displaying a specific measurement image for measuring the screen luminance on the liquid crystal display unit when the screen luminance is measured. The measurement image may be, for example, an entire white image.

The light detecting element 107 is constituted by using, for example, a photoelectric conversion element, and is disposed in the vicinity of an unillustrated image on a screen as long as it does not block light, and detects screen luminance.

The light detection circuit 108 converts the output of the light detection element 107 into a signal corresponding to the output, for example, a DC voltage signal, and outputs the signal to the storage circuit 109.

The storage circuit 109 holds the signal from the light detection circuit 108 as a luminance detection signal.

The control circuit 110 controls the operation of each component of the liquid crystal projection display 100.

The luminance control circuit 111 includes a luminance detection signal f held by the storage circuit 109 obtained in the screen luminance measurement state and a luminance control signal a of another display device supplied from the luminance control signal input / output terminal T2. And the reference luminance signal e
Is generated. The reference luminance signal e is formed by selecting the signal with the lowest luminance from the luminance detection signal f and the luminance control signal a. Further, the reference luminance signal e is output to another display device as a luminance control signal of its own display device.

The luminance control SW 112 selects the reference luminance signal e from the luminance control circuit 111 in the normal state, selects the constant voltage Es in the screen luminance measurement state, and outputs the luminance signals of the signal processing circuit 103 and the liquid crystal drive circuit 104. Control.

An image signal to be displayed on the display device is input to the input terminal T1.

A luminance control signal a from another display device is input to the luminance control signal input / output terminal T2, and a reference luminance signal of the own display device is output to another display device as a luminance control signal a. You.

Hereinafter, the operation of the display device according to the present embodiment will be described. First, in the screen luminance measurement state, the control circuit 110 causes the signal switching SW 102 to move to the signal generation circuit 106 side and the luminance control SW 112 to move to the constant voltage Es.
Set to the side. In this state, the luminance measurement signal d, for example, an entire white signal is output from the signal generation circuit 106 to the signal switching SW.
The signal is output to a circuit at a subsequent stage via 102. The luminance measurement signal d is supplied with a constant voltage Es via a luminance control SW 112, passes through a signal processing circuit 103 set at a constant luminance control, for example, a maximum luminance, and a liquid crystal driving circuit 104, and outputs a white signal on the entire liquid crystal display unit 105. Is formed on the screen and is displayed on the screen by the projection light transmitted through the liquid crystal display unit 105.

The light detecting element 107 is arranged in the vicinity of the image on the screen as far as the image is not shielded, photoelectrically converts the screen luminance in the above state, and supplies the screen luminance to the light detecting circuit 108.

The light detection circuit 108 outputs a signal corresponding to the output, for example, a DC voltage signal to the storage circuit 109, and the storage circuit 109 holds the signal as a luminance detection signal f.

The luminance control circuit 111 includes a luminance detection signal f held by the storage circuit 109 obtained in the screen luminance measurement state and a luminance control signal a of another display device supplied from the luminance control signal input / output terminal T2. From the reference luminance signal e.

Here, the configuration of the luminance control circuit 11 will be described with reference to FIG. FIG. 2 is a block diagram showing a specific example of the brightness control circuit 111 of the liquid crystal projection display device 100 shown in FIG. 1, and portions corresponding to FIG. 1 are denoted by the same reference numerals.

The luminance control circuit 111 includes a comparison circuit 1111
And a buffer 1112 connected as shown. The luminance control signal a from another display device is input to the luminance control signal input / output terminal T2, and the luminance control signal a of this display device is output to another display device.

The luminance detection signal f held by the storage circuit 109 is input to the luminance detection signal input terminal T3.

A reference luminance signal output terminal T4 outputs a luminance detection signal f and a reference luminance signal e generated from a luminance control signal a of another display device supplied from a luminance control signal input / output terminal T2. .

The comparison circuit 1111 corresponds to the storage circuit 10 shown in FIG.
9 is selected as the reference luminance signal e from the luminance detection signal f supplied from 9 and the luminance control signal a from another display device supplied from the luminance control signal input / output terminal T2. It is supplied to the processing circuit 103 and the liquid crystal drive circuit 104.

Further, when the own brightness detection signal f has a lower level than the brightness control signal a from another display device supplied from the brightness control signal input / output terminal T2 and indicates a lower brightness, this brightness detection signal f The signal f becomes the reference luminance signal e. The buffer 15 sends the reference luminance signal e as the luminance control signal a to the luminance control circuit of another display device via the luminance control signal input / output terminal T2.

Thus, the luminance detection signal f of each display device can be obtained in accordance with the state of the light source, and each of the display devices constituting the multi-surface display device is the most of all the display devices. The reference luminance signal of the display device with low luminance will be used as the common reference luminance signal e, and the luminance of other bright display devices will be reduced by the reference luminance signal e, regardless of the state of the light source of each display device. The luminance difference on each screen can be reduced.

On the other hand, in the normal state, the control circuit 110 causes the signal switching SW 102 to move to the enlargement processing circuit 101 side.
Further, the brightness control SW 112 is set on the brightness control circuit 111 side. The input video signal b from the input terminal T1 is supplied to the enlargement processing circuit 101, subjected to enlargement processing, and output.

The output video signal c of the enlargement processing circuit 101 is
The image is supplied from the signal switching SW 102 to the signal processing circuit 103, passes through the liquid crystal drive circuit 104, forms an image on the liquid crystal display 105, and is projected on the screen (not shown) by the projection light transmitted through the liquid crystal display 105. Is displayed.

At this time, the signal processing circuit 103 and the liquid crystal driving circuit 104 are connected to the luminance control circuit 111 as described later.
Is supplied via the luminance control SW 102, and an image whose luminance is controlled by the reference luminance signal e is displayed on the screen.

As described above, according to this embodiment,
Among the plurality of display devices constituting the multi-screen display device, the brightness of the other display device can be controlled so as to be equal to the brightness of the display device with the lowest brightness, and the image quality of the enlarged and displayed image can be greatly reduced. Can be improved.

The configuration of a liquid crystal projection display device according to a second embodiment of the present invention will be described with reference to FIG. The display device 100 ′ according to this embodiment includes:
The configuration is such that the signal processing circuit 103 and the liquid crystal driving circuit 104 are driven using a predetermined reference luminance signal, and a lamp power supply circuit 113 controlled by the reference luminance signal e obtained by the luminance control circuit 111 is provided. Features. Other configurations are almost the same as those of the first embodiment.

That is, in the display device 100 ′ according to the present embodiment, the output of the brightness control SW 112 is supplied not to the signal processing circuit 103 and the liquid crystal driving circuit 104 but to the lamp power supply circuit 113.

The operation state is also divided into two states, a normal state and a screen luminance measurement state, and the operation of each part in each operation state is the same as in the first embodiment. The only difference is that the brightness control is performed not by the signal processing circuit 103 and the liquid crystal driving circuit 104 but by the lamp power supply circuit 113.

In the screen luminance measurement state, the lamp power supply circuit 113 is driven by the constant voltage Es, and the luminance signal at that time is stored in the storage circuit 109 as the luminance detection signal f. On the other hand, in the normal state, the reference luminance signal e is obtained using the luminance detection signal f measured in the screen luminance measurement state, the power supplied to the lamp power supply circuit 113 is controlled, the lamp luminance is controlled, and the entire display device 100 ′ is controlled. Is performed in substantially the same manner as in the first embodiment.

In this embodiment, similarly to the first embodiment, the reference luminance signal e of the luminance control circuit of the darkest display device among the display devices is supplied to each display device as the luminance control signal a. With this brightness control signal a, the power supplied from the lamp power supply circuit 113 to the lamp light source in other bright display devices is reduced, the lamp brightness is reduced, and the brightness is adjusted to the darkest display device.

As described above, if this embodiment is selected,
As in the first embodiment, the brightness of the other display devices can be controlled to be equal to the brightness of the display device with the lowest brightness among the plurality of display devices constituting the multi-screen display device, The image quality of the enlarged and displayed image can be greatly improved. Furthermore, according to this embodiment, the liquid crystal display unit 105 can use the entire displayable luminance range, and the efficiency of use of light from the light source is increased. As a result, the power consumption of the light source can be reduced. it can.

[0051]

According to the liquid crystal projection type multi-screen display device of the present invention, it is possible to reduce the variation in the light output of the lamp light source of the liquid crystal projection display device and the difference in luminance due to aging, and to improve the image quality of the enlarged and displayed image. It can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a liquid crystal projection display device that constitutes a multi-screen display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration example of a luminance control circuit in FIG. 1;

FIG. 3 is a block diagram showing a configuration of a liquid crystal projection display device constituting a multi-screen display device according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100, 100 'liquid crystal projection display device 101 enlargement processing circuit 102 signal switching circuit 103 signal processing circuit 104 liquid crystal drive circuit 105 liquid crystal display unit 106 signal generation circuit 107 photodetector 108 photodetector 109 storage circuit 110 control circuit 111 brightness control Circuit 112 Luminance control signal terminal 113 Luminance control SW 1111 Comparison circuit 1112 Buffer a Luminance control signal b Input video signal c Output video signal d Measurement signal e Reference luminance signal f Luminance detection signal T1 Video signal input terminal T2 Luminance control signal input / output Terminal T3 Luminance detection signal input terminal T4 Reference luminance signal output terminal

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G09F 9/00 G09F 9/00 H04N 5/74 H04N 5/74 Z 9/31 9/31 A F-term (reference) 2H093 NC13 NC49 NC53 ND09 ND39 NG02 5C058 BA01 BA05 BA06 BA23 BB11 BB25 EA03 EA26 EA51 5C060 AA15 DB03 GD01 HA18 HB19 HB26 HD02 JA11 JB06 5C080 AA10 BB06 CC03 DD05 EE29 FF09 GG01 AGG12 GG12 AGG12 GG09 GG12 GG09 GG12 A LL15

Claims (4)

[Claims] 1. A liquid crystal projection system in which a plurality of liquid crystal projection type display devices are arranged to form a large screen including a display screen of each of the display devices, and an image of a signal output from a signal source is displayed. In a multi-screen display device, a signal generating means for generating a measurement signal for displaying a specific measurement image for measuring screen luminance on the display device, and detecting a screen luminance when the specific measurement image is displayed Brightness detection means, storage means for storing a brightness detection signal detected by the brightness detection means, and the lowest brightness signal among the brightness control signal from each display device and its own brightness detection signal as a reference brightness signal Brightness control means for outputting the reference brightness signal as a reference brightness signal for the signal processing means and the liquid crystal drive means to control the brightness of the liquid crystal display. In both cases, the brightness control of the entire multi-screen display device is performed by outputting its own reference brightness signal as a brightness control signal to another display device. 2. A liquid crystal projection system in which a plurality of liquid crystal projection display devices are arranged to form a large screen including a display screen of each of the display devices, and an image of a signal output from a signal source is displayed. In a multi-screen display device, a signal generating means for generating a measurement signal for displaying a specific measurement image for measuring screen luminance on the display device, and detecting a screen luminance when the specific measurement image is displayed Brightness detection means, storage means for storing a brightness detection signal detected by the brightness detection means, and the lowest brightness signal among the brightness control signal from each display device and its own brightness detection signal as a reference brightness signal Brightness control means for controlling the brightness of the light source using the reference brightness signal as a reference signal of the brightness of the light source. A liquid crystal projection type multi-panel display device characterized in that brightness of the entire multi-panel display device is controlled by outputting the control signal to another display device. 3. A liquid crystal projection system in which a plurality of liquid crystal projection display devices are arranged to form a large screen including a display screen of each of the display devices, and an image of a signal output from a signal source is displayed. In a drive control circuit of the multi-screen display device, a signal generating means for generating a measurement signal for displaying a specific measurement image for measuring screen brightness on the display device, and a screen for displaying the specific measurement image Brightness detection means for detecting brightness, storage means for storing a brightness detection signal detected by the brightness detection means, and a brightness control signal from each display device and a signal having the lowest brightness among its own brightness detection signals. Brightness control means for outputting as a reference brightness signal, wherein the reference brightness signal is used as a reference brightness signal for the signal processing means and the liquid crystal driving means. A driving control circuit for a liquid crystal projection type multi-display device, wherein the luminance control of the whole multi-display device is performed by outputting its own reference luminance signal to another display device as a luminance control signal. 4. A liquid crystal projection system in which a plurality of liquid crystal projection display devices are arranged to form a large screen including a display screen of each of the display devices, and an image of a signal output from a signal source is displayed. In a drive control circuit of the multi-screen display device, a signal generating means for generating a measurement signal for displaying a specific measurement image for measuring screen brightness on the display device, and a screen for displaying the specific measurement image Brightness detection means for detecting brightness, storage means for storing a brightness detection signal detected by the brightness detection means, and a brightness control signal from each display device and a signal having the lowest brightness among its own brightness detection signals. Brightness control means for outputting as a reference brightness signal, controlling the brightness of the light source using the reference brightness signal as a reference signal of the brightness of the light source, A drive control circuit for a liquid crystal projection type multi-display device, wherein a luminance signal is output to another display device as a luminance control signal to control the luminance of the whole multi-display device.