JP2008026800A - Image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display apparatus free from occurrence of such a symptom that a screen is burned black even when an image is displayed by an interlaced scanning method by inserting a black signal between video signals of respective scanning lines. <P>SOLUTION: The image display apparatus comprises: a means 4 for converting an input video signal of the interlaced scanning method into a video signal of a progressive scanning method; a creating means 5 for creating two field signals of the interlaced scanning method from the converted video signal; and a display screen 13 formed of fixed pixels. The apparatus further comprises: a means 5 for inserting a black signal or an achromatic signal at a voltage different from that of the black signal between the video signals of the respective scanning signals for the field signals created by the creating means 5; and a switching means 5 for switching between the black signal and the achromatic signal for insertion every two field signals, and is so configured as to perform displaying on the display screen 13 by the interlaced scanning method by the field signal where the black signal is inserted between the video signals of the respective scanning signals and/or the field signal where the achromatic signal is inserted between the video signals of the respective scanning signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention converts an input interlace scanning video signal into a progressive scanning video signal, creates two interlace scanning field signals from the converted video signal, and is formed by fixed pixels. The present invention relates to an image display device that displays on a display screen.

Currently, television receivers for consumers use image display devices (liquid crystal display devices and plasma display panels) from CRT (Cathode Ray Tube) to fixed pixels by digitizing video signals (broadcast signals) and increasing the screen size. Etc.) has been replaced.
From the standpoint of making pictures according to the environment used by viewers in monitors for commercial use, the engineers in broadcasting stations are also requesting the replacement of CRTs with image display devices using liquid crystal panels. Is expensive.

FIG. 5 is a schematic diagram illustrating a partially enlarged example of the display unit of the liquid crystal display device.
In the display unit 20 of the liquid crystal display device, a large number of liquid crystal pixel electrodes 24 are arranged in a matrix, and one terminal of a TFT (Thin Film Transistor) 23 is connected to each pixel electrode 24. The other terminal of each TFT 23 is connected to each signal electrode 21, and the gate of each TFT 23 is connected to each scanning electrode 25.
Each scanning electrode 25 is line-sequentially selected and turned on by a scanning circuit (not shown), and in synchronization with this, a data signal for display from a data signal circuit (not shown) is applied to each signal electrode 21. One screen is displayed.
Such processing is repeated at a period of 1/60 seconds or 1/30 seconds, for example, and an image is displayed. In addition, a display unit 20 is provided for each of the three primary colors to perform color display.

  The CRT is an impulse type that emits light in pulses only at the moment when a voltage corresponding to a data signal is applied. In order to prevent video signal band compression and image flicker (flicker) by scanning, an interlace scanning method is used. Is displayed. In the interlace scanning method, as shown in FIG. 6, the first field obtained by extracting the video signal of the odd-numbered scanning lines from the complete image signal (frame signal) of one screen and the video signal of the even-numbered scanning lines. Are separated into the extracted second field and displayed every 1/60 seconds, and a video signal corresponding to a frame signal having a period of 1/30 seconds is displayed.

  On the other hand, an image display device using fixed pixels such as a liquid crystal display device is a hold type in which pixels emit light continuously for a time during which a voltage corresponding to a data signal is applied, and prevents image flicker. Since it is not necessary, it is displayed by a progressive scanning (sequential scanning) method. In progressive scanning, video signals for each scanning line are sequentially extracted from the first image from the complete image signal (frame signal) of one screen and displayed, and video signals for 1/30 second period frame signals are displayed. ing.

However, for business use, there is a strong demand for displaying an interlaced scanning video signal as it is without converting the video signal input by the interlaced scanning method into a progressive scanning video signal. (Especially video editing engineers).
At present, in order to cover the above-mentioned demand, the display is performed by the line doubler mode in which a complete image signal (frame signal) of one screen is displayed twice every 1/60 seconds. However, there is a problem that this is not an official display method from the viewpoint of the CRT concept of displaying the original video signal.

As a solution to the above-described problems, Patent Documents 1 and 2 disclose, from a complete image signal (frame signal) of one screen, an image of an odd (even) number of scanning lines as shown in FIG. In the interlaced scanning method, a black signal is inserted between the video signals for each scanning line in the first (2) field from which the signals are extracted (in the even (odd) number of empty scanning lines to which no video signal is added). A technique for displaying is disclosed.
JP 2002-132220 A JP 2000-206492 A

However, when the techniques disclosed in Patent Documents 1 and 2 are simply used, the problem is that the luminance is reduced to half, the problem that the gamma characteristic of the screen is changed by inserting the black signal, and the black signal. There is a problem that a phenomenon that the screen is burnt black occurs by periodically inserting the image.
The present invention has been made in view of the above-described circumstances, and even when a black signal is inserted between video signals for each scanning line of a field and displayed by an interlace scanning method, the black signal is frequently generated. It is an object of the present invention to provide an image display apparatus that does not cause a symptom that a screen is burnt black by being periodically inserted.

Further, the present invention provides an image display device in which the gamma characteristic of the screen is not changed by inserting a black signal even when a black signal is inserted between video signals for each scanning line of the field and displayed by an interlace scanning method. The purpose is to provide.
It is another object of the present invention to provide an image display device in which luminance is not lowered even when a black signal is inserted between video signals for each scanning line of a field and displayed by an interlace scanning method.

  An image display apparatus according to the present invention includes a means for converting an input interlaced scanning video signal into a progressive scanning video signal, and two interlaced scanning field signals from the video signal converted by the means. In an image display device comprising a creation means for creating a display screen and a display screen formed by fixed pixels, a black signal or a voltage different from the black signal is generated between video signals for each scanning line of the field signal created by the creation means. A field signal in which a black signal is inserted between the video signals for each scanning line, and a means for inserting the black signal or the achromatic signal inserted by the means into two field signals. And / or display on the display screen by an interlaced scanning method using a field signal in which an achromatic signal is inserted between video signals for each scanning line. And wherein the are.

  In this image display device, the converting means converts the input interlace scanning video signal into the progressive scanning video signal, and the creating means converts the interlace scanning two signals from the converted video signal. A field signal is created and the display screen is formed by fixed pixels. The means for inserting inserts a black signal or an achromatic signal having a voltage different from the black signal between the video signals for each scanning line of the field signal created by the creating means, and the means for switching selects the black signal or achromatic color to be inserted. The signal is switched every two field signals. Then, a field signal in which a black signal is inserted between the video signals for each scanning line and / or a field signal in which an achromatic signal is inserted between the video signals for each scanning line is displayed on the display screen by an interlace scanning method. .

  An image display apparatus according to the present invention comprises means for storing different gamma curves for gamma correction for the field signal into which the black signal is inserted and the field signal into which the achromatic signal is inserted, respectively, The apparatus further comprises means for gamma correcting each of the field signal into which the black signal is inserted and the field signal into which the achromatic signal is inserted based on different gamma curves stored therein.

  In this image display device, the means for storing stores different gamma curves for gamma correction of the field signal into which the black signal is inserted and the field signal into which the achromatic signal is inserted, and means for gamma correction. Then, based on the different gamma curves stored therein, the field signal in which the black signal is inserted and the field signal in which the achromatic signal is inserted are respectively subjected to gamma correction.

  The image display apparatus according to the present invention further comprises switching means for switching between display by the interlace scanning method and display by the progressive scanning method, and the display screen is a liquid crystal display screen having a backlight, and the switching means. When the display is switched to the display using the interlace scanning method, the backlight is configured to be brighter than when the display is switched to the progressive scanning method.

  In this image display device, the switching unit switches between display by the interlace scanning method and display by the progressive scanning method. The display screen is a liquid crystal display screen having a backlight. When the switching unit is switched to the display using the interlace scanning method, the backlight is brightened compared to the case where the switching is switched to the progressive scanning method.

  According to the image display device of the present invention, even when a black signal is inserted between video signals for each scanning line of a field and displayed by an interlace scanning method, the black signal is inserted periodically at a high frequency. It is possible to realize an image display device capable of improving the phenomenon that the screen is burnt black.

  According to the image display device of the present invention, even when a black signal is inserted between video signals for each scanning line of the field and displayed by the interlace scanning method, the gamma characteristic of the screen is changed by inserting the black signal. It is possible to realize an image display device that does not. In addition, in the liquid crystal display device, it is possible to support both the display by the interlace scanning method and the display by the progressive scanning method. In addition, a normal 2.2 power gamma curve can be reproduced for each frame.

  According to the image display device of the present invention, it is possible to realize an image display device in which the luminance does not decrease even when a black signal is inserted between video signals for each scanning line of the field and displayed by the interlace scanning method. .

Hereinafter, the present invention will be described with reference to the drawings showing embodiments thereof.
FIG. 1 is a block diagram showing a main configuration of a liquid crystal display device which is an embodiment of an image display device according to the present invention.
In this liquid crystal display device, the video signal input from the video input terminal VIDEO IN or the color difference signal input terminal YPBPR IN is switched and input by the AV SW circuit 1 (RGB signals can also be input). The video signal switched and input by the AV SW circuit 1 is converted into a digital signal by the analog / digital converter 2 and converted into a desired color space signal by the color space conversion circuit 3.

The color space signal converted by the color space conversion circuit 3 is input to an IP (interlace / progressive) conversion circuit 4 and converted from an interlace signal to a progressive signal. The progressive signal converted by the IP conversion circuit 4 is converted by the scaling circuit 5 into the number of pixels corresponding to the resolution of an LCD (Liquid Crystal Display) 13.
In the scaling circuit 5, the first (2) obtained by extracting the video signal of the odd (even) number of scanning lines from the complete image signal (frame signal) of one screen by the progressive signal as shown in FIG. A field is created, and the black signal or achromatic signal created by the black signal creation / insertion circuit 9 is inserted between the video signals for each scanning line (creation means, insertion means). The achromatic signal is a signal having a level slightly higher than black (for example, 10/255).

  The scaling circuit 5 switches (switches) the black signal and the achromatic signal every two fields when inserting the black signal or the achromatic signal between the video signals for each scanning line. That is, when a black signal is inserted into the first and second fields of one frame, an achromatic signal is inserted into the first and second fields of the next one frame. In addition, when a black signal is inserted into the second field of one frame and the first field of the next one frame, there is nothing in the second field of the next one frame and the first field of the next next frame. Insert a color signal. As a result, it is possible to prevent the black signal from being periodically displayed on the same pixel of the LCD 13 at a high frequency, and to prevent a symptom that the screen is burnt black.

  Further, the gamma correction curve for inserting the black signal and the gamma correction curve for inserting the achromatic signal are stored in the gamma curve storage circuit 12, and each field signal output from the scaling circuit 5 is stored. The gamma correction is executed while switching the gamma correction curve by the gamma curve switching circuit 6. The gamma curve storage circuit 12 also stores a standard 2.2 power gamma correction curve, and the gamma curve switching circuit 6 executes standard gamma correction as necessary.

Here, as shown in FIG. 2, the gamma correction curve B when the black signal is inserted and the gamma correction curve A when the achromatic signal is inserted are a correction curve C of 2.2 power in one frame. By switching to an appropriate correction curve, the video can be reproduced with a standard 2.2 power gamma without a sense of incongruity. 3 and 4 are charts showing specific numerical examples of the gamma correction curves A and B. FIG.
Each gamma-corrected field signal by the gamma curve switching circuit 6 is displayed on the LCD 13 through the LCD controller 7 by the interlace scanning method.

The microcomputer 10 controls each circuit described above with timing, and changes the setting in each circuit in accordance with the operation in the operation unit 11.
When the display using the interlace scanning method is selected in the operation unit 11, the microcomputer 10 controls each circuit so that each circuit operates as described above.

  When the display by the progressive scanning method is selected in the operation unit 11, the microcomputer 10 stops the black signal generation / insertion circuit 9, causes the scaling circuit 5 to generate a progressive signal, and causes the gamma curve switching circuit 6 to perform the standard operation. Perform gamma correction for. The progressive signal after the gamma correction is displayed on the LCD 13 through the LCD controller 7.

  When the display by the interlace scanning method as described above is selected in the operation unit 11, the microcomputer 10 transmits the brightness of the backlight 14 to the backlight control circuit 8 through the LCD controller 7 according to the progressive scanning method. For example, the display is doubled compared to the display. This prevents the screen brightness from being halved by inserting a black signal when displaying by the interlace scanning method, and the backlight 14 is interlocked with the above-described interlace / progressive display switching. The brightness of the can be prevented from changing.

It is a block diagram which shows the principal part structure of the liquid crystal display device which is embodiment of the image display apparatus which concerns on this invention. It is a characteristic view showing an example of a gamma correction curve of the image display device according to the present invention. It is a graph which shows the specific numerical example of a gamma correction curve. It is a graph which shows the specific numerical example of a gamma correction curve. It is a schematic diagram which expands and shows the example of the display part of a liquid crystal display device partially. It is explanatory drawing for demonstrating the display by an interlace scanning system.

Explanation of symbols

2 Analog / digital converter 3 Color space conversion circuit 4 IP conversion circuit (conversion means)
5 Scaling circuit (creating means, inserting means, switching means)
6 Gamma Curve Switching Circuit 7 LCD Controller 8 Backlight Control Circuit 9 Black Signal Creation Insertion Circuit 10 Microcomputer 11 Operation Unit 12 Gamma Curve Storage Circuit 13 LCD (Display Screen)
14 Backlight

Claims (3)

Means for converting an input interlace scanning video signal into a progressive scanning video signal; creation means for creating two interlace scanning field signals from the video signal converted by the means; fixed pixels; In an image display device comprising a display screen formed by
A means for inserting a black signal or an achromatic signal having a voltage different from the black signal between video signals for each scanning line of the field signal created by the creating means, and two black signals or achromatic signals inserted by the means. Switching means for each field signal, and interlaced by a field signal in which a black signal is inserted between video signals for each scanning line and / or a field signal in which an achromatic signal is inserted between video signals for each scanning line An image display device configured to display on the display screen by a scanning method.   Based on the different gamma curves stored by the means for storing gamma curves different from each other for gamma correction of the field signal in which the black signal is inserted and the field signal in which the achromatic signal is inserted, The image display apparatus according to claim 1, further comprising gamma correction means for each of the field signal into which the black signal is inserted and the field signal into which the achromatic signal is inserted.   The apparatus further comprises switching means for switching between display by the interlace scanning method and display by the progressive scanning method, and the display screen is a liquid crystal display screen having a backlight, and the switching means switches to display by the interlace scanning method. 3. The image display device according to claim 1, wherein the backlight is configured to be brighter than in the case of switching to the progressive scanning method.

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