JPH08205049A - Video display device - Google Patents

Abstract

PURPOSE: To realize a display device in which the operation start point of a current limit circuit for a current supplied to a plasma display panel(PDP) is selected for a moving image or a still image, the operation start is quickened in the case of a still image so as to attain easy to see pattern and the deterioration in the PDP is suppressed. CONSTITUTION: An APC circuit section 2 controls luminance/contrast so that the current supplied to a PDP used for a display device 3 does not exceed a required current. A mean luminance level detection section 4 detects the mean luminance level of all picture elements of one pattern and records them to a memory section 5 and the data are given to a discrimination section 6, in which the data are compared with data recorded previously. When there is a difference over a required value in this comparison, the operation start point of the APC circuit section 2 is delayed via an APC circuit control section 8. Or the switching function between a moving image and a still image is provided to a remote commander and the signal representing the difference is received by a remote command signal reception section 7 and given to the discrimination section 6, in which the signal is discriminated, and in the case of a moving image, the operation start point of the APC circuit section 2 is delayed similarly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video display device, and more particularly to switching the operation starting point of a current limiting circuit supplied to a display device depending on whether an input signal is a still image or a moving image.

[0002]

2. Description of the Related Art In a video display device using a plasma display panel (hereinafter abbreviated as PDP) as a display, when a large number of pixels are lit with high brightness, the temperature of the PDP rises due to plasma discharge for lighting. However, this may shorten the life of the display. Therefore, an APC circuit (automati) that measures the current supplied to the PDP and controls the brightness and contrast so that this current does not exceed the set value.
This APC circuit is equipped with a c power control circuit, and the input video signal level is the required display rate (the brightness level of the all-white video signal, which is the integrated value of the brightness levels of the video signals of all pixels on one screen). (The ratio to the integrated value of)) or more.

[0003]

However, from the viewpoint of the visibility of the image, the desired operation starting point of the APC circuit should be different depending on the content of the image. In view of such a point, the present invention switches the operation start point (display rate value) of the APC circuit depending on whether the displayed image is a still image or a moving image,
It is to make it easy to see the image and to make the PDP last longer.

[0004]

In order to solve the above-mentioned problems, the present invention provides a video display device provided with a power control circuit for controlling the power supplied to a display device so as not to exceed a required value. , An average luminance level detecting section for detecting an average luminance level of video signals of all pixels, a memory section for recording data from the average luminance level detecting section at required time intervals, and a memory section for reading the data recorded in the memory section. A discriminating unit for discriminating the presence or absence of a difference by comparing with the data recorded next in the unit, and a control unit for controlling the average luminance level detecting unit, the memory unit and the discriminating unit. The present invention provides a video display device in which the starting point of current limitation of the power control circuit is switched based on the above.

[0005]

With the above construction, in the video display device according to the present invention, the operation start point of the APC circuit is automatically switched depending on whether the input video signal is a still image or a moving image, or It is switched by required operation, delays the operation start point of the APC circuit when displaying a moving image, raises the average brightness to display a powerful image, and accelerates the operation start point of the APC circuit when displaying a still image, lowers the average brightness, Makes the image easier to see and prolongs the life of the display.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video display device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of essential parts of an embodiment of a video display device according to the present invention. In the figure, reference numeral 1 denotes a video signal input unit for inputting a television broadcast, a video signal from a computer device, or the like. Two
Is an APC circuit unit that detects the electric power supplied to the PDP used for the display device 3 by detecting the consumption current, and controls the brightness and contrast so that this current falls within required values. The APC circuit unit 2 operates when the signal level of the input video signal is equal to or higher than the required display rate. An average brightness level detector 4 detects the average brightness level of the video signals of all the pixels of one screen input from the video signal input unit 1. A memory unit 5 records data from the average brightness level detection unit 4 at required time intervals. A discriminating unit 6 reads the data previously recorded in the memory unit 5, compares it with the data recorded in the memory unit 5 this time, and discriminates whether there is a difference.
Reference numeral 7 denotes a remote control (hereinafter abbreviated as remote controller) signal receiving unit, which receives a signal emitted from the remote control device and inputs it to the discriminating unit 6. An APC circuit control unit 8 switches the starting point of the current limiting operation of the APC circuit unit 2 based on the signal from the determination unit 6. A control unit 9 controls each unit.

Next, the operation of the image display device according to the present invention will be described. A video signal such as a television broadcast or a video signal from a computer device is input from the video signal input unit 1 and amplified to an appropriate signal level, and the APC circuit unit 2
It is applied to the display device 3 composed of a PDP via the to display an image. The APC circuit unit 2 detects the current supplied to the PDP and controls the brightness and the contrast so as to be within the required values. This operation requires the display rate of the video signal from the video signal input unit 1. It is done when the rate is over. The video signal from the video signal input unit 1 is also input to the average brightness level detection unit 4 to detect the average brightness level of the video signals of all pixels on one screen. This detection is performed for a required time interval or for each field, and this data is recorded in the memory unit 5 via the control unit 9. At the time of this data recording, the previously recorded data is read from the memory unit 5,
The data recorded this time is input to the determination unit 6, the two data are compared, and if there is a difference between the data, it is determined that the video is moving, that is, the video signal of the moving image is input, If there is no difference between the data, it is determined that a still image has been input.

The signal from the discriminating section 6 is sent to the A through the control section 9.
It is input to the PC circuit control unit 8, and the APC circuit control unit 8 operates the APC circuit unit 2 at a display rate a or more in the case of a still image (A) as shown in FIG. In B), the APC circuit unit 2 is operated at the display rate b or more. The display rate is set to, for example, a = 20%, b = 40%. The "maximum brightness level" on the vertical axis in FIG. 2 represents the upper limit value of the brightness level of the video signal of each pixel. When the display rate is higher than a or b, the amplitude of the video signal of all pixels is compressed. , Compressing the brightness / contrast and controlling the current supplied to the PDP to a required value or less. As a result, in the case of a still image such as a computer image, the operation of the APC circuit 2 is accelerated (starts the operation at a low display rate), brightness and contrast are suppressed, glare is eliminated to make the screen easier to see, and at the same time. The deterioration of the PDP is prevented so that the PDP lasts longer. On the other hand, in the case of a moving image such as a television image, the brightness and the contrast are increased to display a powerful image.

In the above, the operation starting point of the APC circuit section 2 is switched based on the display rate of the input video signal. However, the main body of the display device or the remote control device is provided with a moving image / still image switching button or the like. The operation start point may be switched by operating a button. In this case, the discriminator 6 receives signals from the remote controller via the remote controller signal receiver 7 and the like.
Enter in, and in case of "still image", display rate a or more, "movie"
In the case of 1, the APC circuit control unit 8 switches so that the APC circuit unit 2 operates at the display rate b or more. It should be noted that if the average brightness level detection unit 4 performs detection on a field-by-field basis, for example, in a television broadcast news program, the brightness / contrast is suppressed on the subtitle screen, and a field relay screen or the like is displayed. When switched to, the brightness / contrast rises almost at the same time, and a powerful image can be displayed.

[0010]

As described above, according to the image display apparatus of the present invention, the starting point of the current limiting operation of the APC circuit section is switched depending on whether the image signal is a moving image or a still image, and In the case of (1), the image is displayed with a high brightness and a sufficient contrast, and in the case of a still image, the brightness / contrast is lowered, and the image is easy to see because there is no glare, and at the same time, the PDP lasts longer.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an embodiment of a video display device according to the present invention.

FIG. 2 is a diagram for explaining an APC operation of the image display device according to the present invention.

[Explanation of symbols]

 1 Video Signal Input Section 2 APC Circuit Section 3 Display (Plasma Display Panel) 4 Average Brightness Level Detection Section 5 Memory Section 6 Discrimination Section 7 Remote Control Signal Reception Section 8 APC Circuit Control Section 9 Control Section

Claims (6)

[Claims] 1. A video display device provided with a power control circuit for controlling power supplied to a display device so as not to exceed a required value, and an average brightness for detecting an average brightness level of video signals of all pixels of one screen. Whether there is a difference between the level detection unit and the memory unit that records the data from the average brightness level detection unit at a required time interval, and the data recorded in the memory unit is read and compared with the data recorded next in the memory unit. And a control unit that controls the average brightness level detection unit, the memory unit, and the determination unit, and switches the starting point of the current limit of the power control circuit based on the signal from the determination unit. Video display device. 2. A power control circuit control unit for controlling the power control circuit is provided, and the power control circuit integrates the luminance levels of the video signals of all the pixels of one screen with a signal without a difference from the determination unit. When the ratio of the value to the integrated value of the brightness level of the all-white video signal is greater than or equal to the first set value, the signal of the difference from the determination unit causes the brightness of the video signal of all pixels of one screen. Switching is performed via the power control circuit control unit so that the operation is performed at a second set value which is higher than the first set value in a ratio of the integrated value of the level to the integrated value of the brightness level of the all-white video signal. The image display device according to claim 1, wherein 3. The image display device according to claim 2, wherein the first set value is approximately 20% and the second set value is approximately 40%. 4. A still image mode / moving image mode switching unit is provided, the discrimination unit discriminates a signal from the switching unit, and a still image mode difference signal is output to discriminate the moving image mode. 2. A signal with a difference is output according to claim 1,
The video display device according to claim 2 or 3. 5. A remote control device for remotely controlling the video display device is provided with a function of switching between the still image mode and the moving image mode, and the video display device is provided with a remote control signal receiving section for receiving a signal from the remote control device. The image display device according to claim 4, wherein the signal received by the remote control signal receiving unit is input to the determining unit. 6. The image according to claim 1, claim 2, claim 3, claim 4, or claim 5, wherein the data from the average brightness level detector is recorded in the memory unit for each screen. Display device.