JPH0388588A - Scanning converting circuit for television video signal - Google Patents

Abstract

PURPOSE:To prevent the seizure of only the center part by providing a level shifting part for shifting a blanking level extending over a prescribed range of the head and the end of a television video signal of an NTSC system whose scanning conversion is ended to a prescribed value between a white level and a black level. CONSTITUTION:In a time base compressing circuit 19, original signals and interpolating signals Y, Y', (R-Y), (R-Y)', (B-Y), and (B-Y) supplied from a Y, C interpolating circuit 18 are written in six pieces of line memories under a timing signal of an NTSC system, and read out under a timing signal of an HDTV system, by which a time base is compressed to 1/2. The signals whose scanning conversion by this scanning line interpolation and the time base compression is ended are supplied to a level shifting circuit 20 of the next stage. In this level shifting circuit 20, a blanking level extending over a prescribed range of the head and the end of a video signal on each line whose scanning conversion is ended is shifted to a prescribed value between a white level and a black level, passes through D/A converters 21a, 21b and 21c and supplied to a matrix circuit 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a scan conversion circuit for television video signals installed in a high-definition television (HDTV) receiver.

(Conventional technology) High-definition television (1), which has been put into practical use recently, uses a high-definition television (HDTV) system, in which each frame consists of 1,125 scanning lines at a rate of 30 frames per second. It is configured to be displayed on a display device with an aspect ratio of 9:16. In addition, in the existing NTSC television signal, one frame of screen consisting of 525 scanning lines is displayed at a rate of 30 frames per second on a display device with an aspect ratio of 3:4. .

(Problem to be Solved by the Invention) In order to display an existing NTSC television screen on the above-mentioned HDTV system display device, it is necessary to incorporate an amplifier converter for converting the NTSC television signal into HDTV television (K). However, since such an up-converter is complicated and expensive, there is a problem that the entire display device becomes complicated and expensive.

Therefore, as a next-best measure, we used a scan converter with a relatively simple configuration to apply scan line interpolation and time axis compression to the NTSC television signal, thereby converting it to HDTV.
Similar to a television signal, 2) a method for displaying the signal by converting it into a television signal with twice the horizontal scanning frequency (1,050 lines/frame) can be considered.

However, in the method using a scan converter as described above, since the aspect ratio of HDTV is larger than that of NTSC, areas of black level (blanking level) appear on both sides of the screen while displaying an NTSC signal. , deterioration (referred to as "burn-in") caused by electron beam irradiation occurs only in the central portion. As a result, when displaying the original HDTV signal, there is a problem in that brightness unevenness occurs due to the difference in the progress of deterioration between the central portion and the left and right peripheral portions of the display screen.

(Means for Solving the Problems) A scan conversion circuit for a television video signal according to the present invention performs scanning line interpolation and time axis compression on an NTSC television video signal to generate an image with twice the horizontal scanning frequency. (3) Shifting the blanking level over a predetermined range at the beginning and end of the video signal on each scanning line after scan conversion to a signal to a predetermined value between the self level and the black level. and a level shift section, and is configured to prevent burn-in only in the central portion when displaying an NTSC signal.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

(Embodiment) FIG. 1 shows the configuration of a scan conversion circuit for television video signals according to an embodiment of the present invention in a display device CR for HDTV.
It is a block diagram shown with T.

In FIG. 1, IN is an input terminal for an NTSC video signal to be scan converted, 11 is a synchronization separation circuit, 12 is an NTSC timing generation circuit, 13 is an HDTV timing generation circuit, 14 is an A/D conversion circuit, and 15 is a Motion adaptive Y/
C separation circuit, 16 is a motion detection circuit, 17 is a Y and C signal processing circuit, 18 is a Y and C interpolation circuit, 19 is a time axis compression circuit, 20 is a level shift circuit, and 21a to 21C are D/C signal processing circuits.
The A conversion circuit 22 is a matrix circuit.

The horizontal synchronization signal and vertical synchronization signal (4) included in the NTSC video signal supplied to the input terminal IN are separated by the synchronization separation circuit 11, and the NTSC tying generation circuit 1
2. This NTSC system timing generation circuit 1
2, various timing signals are created from the horizontal synchronization signal and the vertical synchronization signal, and distributed to each circuit such as the Y/C separation circuit 15.

In addition, the HDTV timing generation circuit 13 uses NTSC.
Various timing signals are generated based on the system timing signal, and these timing signals are supplied to each circuit such as the time axis compression circuit 19 and A/D conversion circuits 212 to 210.

NTS whose synchronization signal is separated in the synchronization separation circuit 11
The C video signal is processed by the A/D conversion circuit 14 at a predetermined sampling rate, for example, a frequency four times that of the color subcarrier (
4fsc), and is converted into a digital video signal and supplied to a motion adaptive Y/C separation circuit 15 and a motion detection circuit 16. The motion detection circuit 15 receives an NTSC signal system signal.
A built-in frame memory is used to detect movement on the display screen from the magnitude of the inter-frame difference signal, and this detection result is used to determine the motion
) The responsive Y/C separation circuit 15 and the Y/C interpolation circuit 18 are notified. The motion adaptive Y/C separation circuit 15 includes a Y/C separation section (<C type filter) that utilizes the correlation between adjacent lines and a Y/C separation section that utilizes the correlation between adjacent frames. , the luminance signal and the color signal output from each of these Y/C separators are combined or selected according to the magnitude of movement notified from the motion detection circuit 16,
As the final luminance signal Y and color signal C, Y and C are sent to the next stage.
The signal is supplied to the signal processing section 17.

In the Y, C signal processing section 17, a luminance signal Y and color difference signals R-Y, BY are generated by color demodulation from the luminance signal Y and color signal C supplied from the Y/C separation circuit 15, and these are subjected to contour processing. After being subjected to processing such as correction, it is supplied to the Y and C interpolation circuit 18 at the next stage.

The Y, C interpolation circuit 18 includes an interline interpolation section that generates an interpolation line from the previous and next lines in a field, and an interfield interpolation section that outputs an adjacent line of an adjacent field as an interpolation line. The interpolation line of the luminance signal and chrominance signal (6>) output from each interpolator is selected as the base or the interpolation line according to the magnitude of the movement notified from the motion detection circuit 16, and the original signal Y,
(RY), (B-Y) and the interpolated signal Y", (
RY)'' and (B-Y)' to the time axis compression circuit 19 at the next stage.

In the time axis compression circuit 19, the original signal and the interpolated signal Y, Y'(1'1-Y) supplied from the previous stage y, c interpolation circuit 18 are combined.
, (RY)', (B-Y), (BY)'' are written into six line memories under the NTSC system timing signal, and are sequentially output under the HDTV system timing signal. As a result, the time axis is compressed to 1/2. The signal that has been scan-converted by scanning line interpolation and time-base compression is supplied to the level shift circuit 20 at the next stage. In this level shift circuit 20, the blanking level over a predetermined range at the beginning and end of the video signal on each scan-converted line is shifted to a predetermined value (ffi) between the white level and the black level, and the blanking level is shifted to a predetermined value (ffi) between the white level and black level. The signal is supplied to the matrix circuit 22 via 21a, 21b, and 2ICs.

The original luminance signal Y and the interpolated luminance signal Y for one life of the NTSC system are as illustrated as waveforms (A) and (B) in Fig. 2, and these have a sampling rate of In the case of 4fsc, 14.3 Mllz (7) Written to the memory for time axis compression in synchronization with the write clock signal. The luminance signals Y and Y′ written in this memory for time axis compression are 8fsc・(16/9)・(3/4)
The luminance signal is read out in synchronization with a read clock signal of −38.2 MHz, and becomes a time-axis compressed luminance signal as illustrated in waveform (C). Waveform (D) is a level shift command supplied from the HDTV timing generation circuit 13 to the level shift 1 circuit 20.

In the level shift circuit 2o receiving this command, as illustrated in waveform (E), the blanking level over a predetermined range at the beginning and end of the video signal on each scan-converted line is between the white level and the black level. is output while being shifted to a predetermined value.

Therefore, as shown in FIG.
The signal has an aspect ratio of 9 when a level shift area is added, which is shown with diagonal lines on the left and right sides of the display area with an original aspect ratio of 3:4.
Displayed on the 16 HDTV display screen (8). The shift level is set to a value approximately equal to the average value of the blanking level (black level) and the white level. Further, as the color of this shift level, an appropriate color such as green can be selected according to the viewer's preference.

(Effects of the Invention) As explained in detail above, the scan conversion circuit for television video signals according to the present invention is capable of converting scan-converted NTSC signals.
The configuration includes a level shift unit that shifts the blanking level over a predetermined range at the beginning and end of a television video signal of the NTSC system to a predetermined value between the white level and the black level. The effect is that burn-in can be prevented only in certain parts.

[Brief explanation of drawings]

1 is a block diagram showing the configuration of a scan conversion circuit for television video signals according to an embodiment of the present invention together with an HDTV display device CRT; FIG. 2 is a waveform diagram for explaining the operation of FIG. 1; FIG. 3 is a conceptual diagram showing a display screen of the television signal (9) converted by the scan conversion circuit of FIG. IN...Input terminal for NTSC television signal to be scan converted, 11...Sync separation circuit, 12...NTS
C-system timing generation circuit, 13...HDTV-system timing generation circuit, 14...A/D conversion circuit, 15...Y
/C separation circuit, 17...y, c processing circuit, 18.
...y-c interpolation circuit, 19...time axis compression circuit, 20
...Level shift circuit, 21a-21c...D/A
Conversion circuit, 22...matrix circuit.

Claims (1)

[Claims] A scan conversion unit performs scan line interpolation and time axis compression on an NTSC television video signal to convert it into a video signal with twice the horizontal scanning frequency, and the beginning of the scan-converted video signal on each scan line. and a level shift section that shifts a blanking level over a predetermined range at the end to a predetermined value intermediate between a white level and a black level.