JPH02301272A - Picture display system - Google Patents

Abstract

PURPOSE:To prevent baking caused when a picture with a smaller size than the screen size is displayed by displaying a blank area caused when the pattern size after conversion is smaller than the screen size in terms of a prescribed luminance signal and chrominance signal. CONSTITUTION:A video signal by the high definition television system such as a MUSE base band signal is converted into a video signal of the existing television system such as an NTSC signal by reducing number of scanning lines without changing the aspect ratio and displayed, then a margin area is caused to the upper side and/or lower side of a picture region on the screen. Then a brightness level of the space area is brought into a level nearly equal to the brightness level of the picture area and displayed at a hue not so remarkable so as to average the brightness level of the entire screen thereby preventing the baking of the screen caused by the partial use of the screen.

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention provides video signals based on high-definition television system.
The present invention relates to an image display system that converts into a video signal and displays it according to the current television system, and particularly relates to processing of blank areas that occur when displaying an image smaller than the screen.

[Prior art] As a new television system to replace the current television system, it not only improves picture and sound quality, but also provides advanced visual psychological effects such as a sense of realism and powerful windows that far exceeds that of the current television system. High-definition television systems, such as high-definition systems, have been proposed.

Since the high-definition system is significantly different from current television systems, such as the NTSC system, in screen format, scanning system, audio system, etc., high-definition signals cannot be reproduced as they are using a receiver based on the NTSC system. For this reason, differences in the number of scanning lines, aspect ratio, field frequency, etc. between both systems are absorbed and the high-definition signal is converted to NTSC.
High-definition/NTS to convert to signal and display
A C converter (down converter) has been proposed.

Figure 7 is a diagram showing an example of displaying the output of the down converter on an NTSC screen.
This is a mode in which the 1032 effective scanning lines of the SE signal are reduced to 173:344 and allocated among the 485 effective scanning lines of the NTSC system, and an NTSC output is obtained without changing the aspect ratio of 16:9 of the high-definition system. According to this mode, the aspect ratio of the NTSC system is 4:3 (16:3).
12), a margin area of about 10% of the effective number of scanning lines appears at the top and bottom of the screen, but since the horizontal direction matches that of a high-definition screen, it is possible to obtain an image with the intended composition in high-definition. .

[Problem to be solved by the invention]

By the way, in the conventional example mentioned above, the blank areas that occur at the top and bottom of the screen are displayed with a black signal, so if this display continues for a long time, the degree of fatigue of the phosphor in the picture tube will differ between the blank area and the image area. Therefore, when normal display using the entire screen is performed, there is a problem that the margin area becomes bright and streaks appear at the boundary of the area. This is what is called CRT burn-in.

An object of the present invention is to prevent burn-in phenomenon that occurs when displaying an image smaller than the screen.

[Means for Solving the Problems] The present invention provides an image display system in which an image according to a high-definition television system is displayed on a screen according to the current television system by converting the number of scanning lines. A blank area that occurs when the size is smaller than the screen size is displayed using a predetermined luminance signal and color signal.

[For production]

Video signal based on high-definition television system, e.g. MU
When the SE baseband signal is converted to a video signal according to the current television system, such as an NTSC signal, by reducing the number of scanning lines without changing the aspect ratio and displayed, the upper and/or lower part of the image area on the screen A blank area appears.

Therefore, the present invention aims to average the brightness level of the entire screen by setting the brightness level of this margin area to approximately the same level as the brightness level of the image area and displaying it in an inconspicuous hue. Prevent screen burn-in caused by manual use.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of an image display method according to the present invention. This embodiment shows an example in which a MUSE signal obtained by band-compressing a high-definition signal for satellite broadcasting is converted into an NTSC signal and displayed.

In FIG. 1, a MUSE baseband signal received by a BS antenna and obtained through a BS tuner passes through a low-pass filter 1 with a cut-off frequency of 8.15 MHz, and then is converted into a digital signal by an AD converter 2. The sampling frequency in the AD converter 2 is the MUSE resampling frequency of 16.2 MHz.

The MUSE signal converted into a digital signal by the AD converter 2 is de-emphasized by a de-emphasis circuit 3 and then supplied to a vertical filter 4 .

The vertical filter 4 generates a 1-line signal from 3 lines of the MUSE signal, reduces the 1032 effective scanning lines of the MUSE signal to 173 344 lines, and generates a luminance signal Y9 color signal R-Y and B of each line. -Y is supplied to the time axis buffer 5. The time axis buffer 5 is a field memory that sequentially stores luminance signals and color difference signals for one field. , 15.12 (=16.2X14/1
5) Read the signal from the storage location by means of a successive address signal RA having a clock frequency of MHz. For details of the scanning line conversion in the vertical filter 4 and the time axis buffer 5, please refer to Japanese Patent Application No. 63-242605 (title of invention = "M
USE-NTSC Conversion System").

The signal read out from the time axis buffer 5 by the successive address signal RA is added with a blanking signal by the NTSC formatter 6 and becomes an NTSC video signal.
Furthermore, after being converted into an analog signal by the DA converter 7 which samples the signal with a frequency of 7.56 MHz, the NTS
The signal is supplied to the C receiver 8.

On the other hand, the MU converted into a digital signal by the AD converter 2
The SE signal is supplied to the MUSE timing generation circuit 9. This MUSE timing generation circuit 9 detects a horizontal synchronization signal and a frame pulse as a vertical synchronization signal from the MUSE signal, generates various timing signals, and outputs various timing signals to the AD converter 2. The vertical filter 42 is supplied to the time axis buffer 5 and the NTSC timing generation circuit 1O, which will be described later.

The horizontal synchronization signal is inserted into each line of the MUSE transmission signal from the 1st sample point to the 11th sample point with the polarity reversed for each line, and from this horizontal synchronization signal 16.2M
Regenerate the Hz resampled signal. Further, the frame pulse is inserted into each frame of the MUSE transmission signal using two lines.

Since the waveforms of these two lines have opposite polarities, they can be easily distinguished from the video signal, and thereby the frame pulse (-vertical synchronization signal) can be detected accurately.

The NTSC timing generation circuit 10 generates various timing signals based on the synchronization signal detected by the MUSE timing generation circuit 9 and the generated timing signal, and outputs successive addresses at a frequency of 15.12 MHz to the time axis buffer 5. A signal RA, horizontal and vertical synchronizing signals HD and VD are supplied to the NTSC formatter 6 and NTSC receiver 8, and a sampling signal SP2 with a frequency of 7.56 MHz is supplied to the DA converter 7.

FIG. 2 is a block diagram showing a partial configuration of the NTSC timing generation circuit 10, showing a circuit that generates the timing signal TM, successive address signal RA, horizontal synchronization signal HD, and vertical synchronization signal VD.

This circuit generates a plurality of timing signals T based on the outputs of horizontal and vertical counters 20 and 21 and vertical counter 21.
a-Tn, a plurality of image display timing generation circuits 22a to 22n, and a plurality of timing signals T a -T;
a selector 23 that selects any one timing signal from n and outputs it as a timing signal TM; a successive address generator that generates a successive address signal RA for the time axis buffer 5 based on the output of the horizontal counter 20 and the timing signal TM; It consists of a circuit 24 and a synchronization signal generation circuit 25 that generates horizontal and vertical synchronization signals HD and VD from the outputs of both counters 20 and 21.

The horizontal counter 20 divides the 15.12 MHz input clock signal to 15.75 KHz (= 15.12 MHz
z/960) horizontal scanning signal, and vertical counter 2
Supply to 1. The vertical counter 21 counts the horizontal scanning signals to output line data indicating line numbers for 1 fields, and outputs it to the image display timing generation circuits 22a to 22n. Timing generation circuit 22
A to 22n generate timing signals Ta to Tn having mutually different phases based on the supplied line data.

The timing signal Ta-Tn has 344 lines per frame (1 frame) in order to display the video signal stored in the time axis buffer 5 using 344 lines out of 485 effective scanning lines (1 frame) of the NTSC system. These signals are at level "1" during one field (172 lines), and are generated with a phase shift of a plurality of lines from each other, as shown in the waveform diagram of FIG. The selector 23 selects a plurality of timing signals Ta-T.
One timing signal is selected from n and outputted as a timing signal TM. The selection of the timing signals Ta-Tn in the selector 23 may be performed randomly, for example, in connection with power-on of the system.

The timing signal TM selected in this way is supplied to the successive address generation circuit 24. The successive address generation circuit 24 outputs an address signal RA that is reset every time the timing signal TM arrives and increases sequentially from the first value at a frequency of 15.12 MHz, and supplies it to the time axis buffer 5 to generate 344 signals (1 frame). 172 fields) is read out.

FIG. 4 is a block diagram showing the configuration of the NTSC formatter 6, which adds the first and second selectors 30 and 31, the margin level generator 32, the blanking level generator 33, and the horizontal and vertical synchronizing signals HD and VD. It consists of an OR circuit 34 that generates a blanking signal BL.

The first selector 30 switches between the video signal read from the time axis buffer 5 and the video signal output from the margin level generator 32 using the above-mentioned timing signal TM, and the period when the timing signal TM is at level "1" is a time period. The timing signal TM inputs the video signal from the axis buffer 5 at the level "
0'', the video signal from the margin level generator 32 is output. Therefore, the output of the margin level generator 32 is set to the same level as the brightness level of the image area,
If the hue is also inconspicuous, the brightness level of the entire screen is averaged, and screen burn-in is reduced compared to the conventional method in which blank areas are displayed at a black level.

The second selector 31 switches the output from the first selector 30 and the output from the blanking level generator 33 using the blanking signal BL, and outputs the blanking signal B.
During the period when L is level “1”, blanking level generator 3
The blanking level signal from the selector 30 is selected during the period of level "0", and the video signal from the selector 30 is selected during the period of level "0", and the blanking signal is added to the video signal and output.

Next, the operation of this embodiment having such a configuration will be explained.

The MUSE baseband signal input through the BS tuner is subjected to 3-line/1-line conversion by the vertical filter 4 to generate 344 effective scanning lines from 1032 effective scanning lines. The generated luminance signal Y° and color difference signals RY and BY of each line are sequentially written into the time axis buffer 5. The signal written in the time axis buffer 5 is read out by the successive address signal RA which is output while the timing signal TM is at level "1", and is supplied to the NTSC formatter 6. In NTSC format Tsuta 6,
The video signal of the margin area and the blanking signal are added and output as an NTSC video signal.

By the way, since the timing signal TM is a signal selected from among the plurality of timing signals Ta-TnO as described above, for example, if the timing signal Ta is selected, the fifth timing signal TM is selected.
As shown in figure (a), an image is displayed at the top of the screen,
Furthermore, if the timing signal Tn is selected, an image is displayed at the bottom of the screen as shown in FIG. Therefore, by appropriately switching the timing signal TM, the positional relationship between the image area and the margin area can be variously changed on the screen, and screen burn-in caused by fixing the margin area can be reduced.

Also, the brightness signal Y9 is set to the margin level generator 32.
If the color signals R-Y and B-Y can be changed arbitrarily, and the brightness level of the margin area is set to the same level as the brightness level of the image area, the brightness level of the margin area will be reduced compared to when the margin area is displayed at the black level. screen burn-in is reduced.

FIG. 6 is a block diagram showing another embodiment of the NTSC timing generation circuit 10. This embodiment uses a plurality of image display timing generation circuits 22a to 22 in the configuration shown in FIG.
An image display timing generation circuit 22 and an n-1 stage shift register 26 for delaying the output of the generation circuit 22 are provided in place of the generation circuit 22 and the shift register 26.
The configuration is such that each output is supplied to the selector 23 as a timing signal Ta-Tn.

〔Effect of the invention〕

According to the image display method according to the present invention, the brightness level of the blank area that occurs when displaying an image smaller than the screen is set to approximately the same level as the brightness level of the image area, thereby reducing the brightness level of the entire screen. Averaging can be achieved,
It is possible to prevent burn-in caused by partial use of the screen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the image display method according to the present invention, FIG. 2 is a block diagram showing a partial configuration of the NTSC timing generation circuit in FIG. 1, and FIG. 3 is the operation of FIG. 2. FIG. 4 is a block diagram showing the NTSC formatter in FIG. 1. FIG. 5 is a diagram showing an example of displaying an image projected on an NTSC receiver according to the present invention. A block diagram showing another embodiment of the timing generation circuit. FIG. 7 is a diagram showing a display example of an image displayed on an NTSC receiver according to the conventional method. Patent applicant Pioneer Corporation Waveform diagram Figure 3 Screen display example Figure 5 NTSC timing generation circuit Figure 2 NTSC formatter Figure 4 Other examples of NTSC timing generation circuit Figure 6 Conventional screen display example Figure 7

Claims (1)

[Claims] In an image display method in which an image according to a high-definition television method is displayed on a screen according to the current television method after converting the number of scanning lines, the image size after the conversion is larger than the screen size. An image display method characterized by displaying a margin area that occurs when the area is small using a predetermined luminance signal and color signal.