JPH06326938A - Television receiver - Google Patents

Abstract

PURPOSE:To obtain picture formation appropriate to each of an NTSC signal and a high-vision signal and to secure the dynamic range of a high-vision signal processing circuit connected to the post stage. CONSTITUTION:An output from an NTSC signal processing circuit consisting of a video amplifier circuit 1, a band amplifier circuit 2, a color synchronizing circuit 3, a color demodulating circuit 4, and an RGB conversion circuit 5 is converted into a high-vision signal format by a signal conversion circuit 7. An output from a high-vision signal processing circuit consisting of a contrast circuit 9, a hue adjusting circuit 10, a picture quality adjusting circuit 11, an RGB conversion circuit 12, and a brightness adjusting circuit 13 is added to blanking and supplied to a CRT 16 through a driving circuit 15. A signal selecting circuit 8 selects the output of the NTSC signal processing circuit or a high-vision signal and inputs the selected signal to the circuit 9. A detection signal from an anode current detecting circuit 17 is selectively applied to the NTSC signal processing circuit or the high-vision signal processing circuit by a switching circuit 18 in accordance with a receiving mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to switching of feedback information relating to a modulation degree or an amplification degree of a television receiver corresponding to a plurality of different signal formats.

[0002]

2. Description of the Related Art Television receivers compatible with NTSC signals and high-definition television signals (high-definition signals) have been developed. FIG. 2 shows the structure of the television receiver. An NTSC composite television signal is supplied to the terminal (a), and a high-definition signal is supplied to the terminal (b). NTSC input from terminal (a)
The signal is subjected to contrast and image quality adjustment by the video amplifier circuit 1. The NTSC signal introduced from the terminal (a) is supplied to the band amplification circuit 2. The band amplification circuit 2 separates the color burst signal, supplies it to the color synchronization circuit 3, separates the chroma signal and supplies it to the color demodulation circuit 4. The color synchronization circuit 3 reproduces the color subcarrier and the color subcarrier is supplied to the color demodulation circuit 4. The color demodulation circuit 4 adjusts the color density and color tone, demodulates the color difference signal, and converts the color difference signal to RGB.
It is supplied to the conversion circuit 5. A luminance signal is also supplied from the video amplifier circuit 1 to the RGB conversion circuit 5. This makes RG
The B conversion circuit 5 generates R, G, B signals and supplies them to the brightness adjustment circuit 6. The brightness-adjusted R, G, and B signals are input to the signal conversion circuit 7. This signal conversion circuit 7
Then, the R, G, B signals of the NTSC system are format-converted into a luminance signal Y and color signals PR, PB as high-definition signals. The converted luminance signal Y and color difference signal PR
, PB are input to the input signal selection circuit 8. The high-definition signals (Y, PR, PB) are input to the input signal selection circuit 8 from the previous terminal (b).

The signal selected by the signal selection circuit 8 is subsequently processed as a high-definition signal by a high-definition signal processing circuit and supplied to a color cathode ray tube (CRT) 16. The high-definition signal output from the signal selection circuit 8 is adjusted by the contrast circuit 9, and then the luminance signal (Y) is adjusted by the image quality adjustment circuit 11, and the color difference signal P
The hues of R and PB are adjusted by the hue adjusting circuit 10. The brightness signal adjusted by the image quality adjustment circuit 11 is input to the RGB conversion circuit 12. The R, G, B conversion circuit 12 has a color difference signal PR adjusted by the hue adjustment circuit 10 described above.
, PB are also supplied. The RGB conversion circuit 12
The R, G, B signals are generated and supplied to the brightness adjustment circuit 13. The brightness-adjusted R, G, and B signals are input to the blanking addition circuit 14 to be subjected to blanking and CR.
It is supplied to the cathode ray tube 16 through the T drive circuit 15 and displayed.

The anode current detection circuit 17 detects an abnormal increase in brightness and detects a change in the anode current. If an excessive amount of anode current flows, the high voltage circuit will be overloaded and the deflection circuit etc. will be destroyed. The anode current is detected by the anode current detection circuit 17, and this detection signal is negatively fed back to the brightness detection circuit 13 (control by this feedback is called an automatic brightness limiting circuit (ABL)). Alternatively, the anode current detection signal from the anode current detection circuit 17 is negatively fed back to the contrast adjusting circuit 9 and the brightness adjusting circuit 13 (control by this feedback is called an automatic brightness contrast limiting circuit (ABCL)).
This control loop is an important factor in determining the image quality of the television receiver.

In the above television receiver, N
When receiving a TSC signal, NTS after various controls
Ideally, the C signal is supplied to the CRT 16 as it is. However, since it is supplied to the CRT 16 through the high-definition signal processing circuit in the latter stage and a negative feedback such as ABCL is applied, part of the high-definition signal processing acts on the NTSC signal, and an image unique to NTSC cannot be obtained.

[0006]

In a television receiver capable of handling an NTSC signal and a high-definition signal, the NTSC signal is converted into a signal which can be processed by a high-definition signal processing circuit and is supplied to a CRT through the high-definition signal processing circuit. ing. For this reason, it is necessary to perform the NTSC signal processing in the previous stage in consideration of the ABCL functioning only with the high-definition signal processing circuit and the dynamic range of the circuit, which causes a problem of complicated signal control.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a television receiver capable of making a picture adapted to each of the NTSC signal and the high-definition signal and ensuring the dynamic range of the high-definition signal processing circuit in the subsequent stage. And

[0008]

The present invention provides a means for independently switching and supplying negative feedback information such as ABCL from a CRT to an NTSC signal processing section and a high-definition signal processing section.

[0009]

With the above-described means, it is possible to make a picture adapted to each of the NTSC signal and the high-definition signal, and to secure the dynamic range of the high-definition signal processing circuit in the subsequent stage.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The same parts as those in FIG. 2 will be described with the same reference numerals. N for the terminal (a)
A composite television signal of the TSC system is supplied, and a high-definition signal is supplied to the terminal (b). Terminal (a)
The image amplification circuit 1 adjusts the contrast and image quality of the NTSC signal input from. The NTSC signal introduced from the terminal (a) is supplied to the band amplification circuit 2. In the band amplification circuit 2, the color burst signal is separated and supplied to the color synchronization circuit 3, the chroma signal is separated, and the color demodulation circuit 4 is separated.
Supply to. The color synchronization circuit 3 reproduces the color subcarrier and the color subcarrier is supplied to the color demodulation circuit 4. The color demodulation circuit 4 adjusts the color density and color tone, demodulates the color difference signal, and supplies the color difference signal to the RGB conversion circuit 5. RGB
The conversion circuit 5 is also supplied with the luminance signal from the video amplification circuit 1. As a result, the RGB conversion circuit 5 generates R, G, B signals and supplies them to the brightness adjustment circuit 6. The brightness-adjusted R, G, and B signals are input to the signal conversion circuit 7.

The image amplification circuit 1, the band amplification circuit 2, the color synchronization circuit 3, the color demodulation circuit 4, and the RGB conversion circuit 5 constitute an NTSC signal processing circuit, and an ABL or ABCL control loop is constructed. That is, the detection output of the anode current detection circuit 17 is passed through the switching circuit 18 to the brightness adjustment circuit 6, or the brightness adjustment circuit 6 and the video amplification circuit 1.
Can be supplied to the gain control end of the.

In the signal conversion circuit 7, the NTSC system R,
The G and B signals are format-converted into a luminance signal Y and color signals PR and PB as high definition signals. The converted luminance signal Y and color difference signals PR and PB are input to the input signal selection circuit 8. The high-definition signals (Y, PR, PB) are input to the input signal selection circuit 8 from the previous terminal (b).

The signal selected by the signal selection circuit 8 is subsequently processed as a high-definition signal by a high-definition signal processing circuit and supplied to a color cathode ray tube (CRT) 16. The high-definition signal output from the signal selection circuit 8 is adjusted by the contrast circuit 9, and then the luminance signal (Y) is adjusted by the image quality adjustment circuit 11, and the color difference signal P
The hues of R and PB are adjusted by the hue adjusting circuit 10. The brightness signal adjusted by the image quality adjustment circuit 11 is input to the RGB conversion circuit 12. The R, G, B conversion circuit 12 has a color difference signal PR adjusted by the hue adjustment circuit 10 described above.
, PB are also supplied. The RGB conversion circuit 12
The R, G, B signals are generated and supplied to the brightness adjustment circuit 13. The brightness-adjusted R, G, and B signals are input to the blanking addition circuit 14 to be subjected to blanking and CR.
It is supplied to the cathode ray tube 16 through the T drive circuit 15 and displayed.

The anode current detection circuit 17 detects that the brightness is abnormally high, and detects a change in the anode current. This detection signal is input to the switching circuit 18. The detection signal is negatively fed back (ABL) to the brightness detection circuit 13 or negatively fed back (ABCL) to the contrast adjustment circuit 9 and the brightness adjustment circuit 13.

The switching circuit 18 is controlled by the reception mode signal given from the terminal 19, and when processing and displaying the NTSC signal, the anode current is negatively fed back to the NTSC signal processing circuit to process the high-definition signal. The anode current is negatively fed back to the high-definition signal processing circuit.

As described above, if the ABCL negative feedback information is switched and used, and the degree of modulation and the degree of amplification of the high-definition signal processing circuit are set to "1" when the NTSC signal is received, NT
Since the signal controlled by the SC signal processing circuit is directly supplied to the CRT, it is possible to create an NTSC picture without considering the high-definition signal processing circuit in the subsequent stage. Moreover, since the output signal of the NTSC signal processing circuit in the front stage is limited, the dynamic range of the high definition signal processing circuit in the rear stage can be sufficiently secured and the signal saturation can be reduced.

[0017]

As described above, according to the present invention,
It is possible to create pictures that are suitable for NTSC signals and high-definition signals, and to secure the dynamic range of the high-definition signal processing circuit in the subsequent stage.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit of a conventional television receiver.

[Explanation of symbols]

1 ... Video amplification circuit, 2 ... Band amplification circuit, 3 ... Color synchronization circuit, 4 ... Color demodulation circuit, 5 ... RGB conversion circuit, 6 ... Brightness adjustment circuit, 7 ... Signal conversion circuit, 8 ... Input signal selection circuit,
9 ... Contrast circuit, 10 ... Color adjustment circuit, 11 ...
Image quality adjustment circuit, 12 ... RGB conversion circuit, 13 ... Brightness adjustment circuit, 14 ... Blanking addition circuit, 15 ... CRT drive circuit, 16 ... CRT, 17 ... Anode current detection circuit, 18 ... Switching circuit.

Claims (2)

[Claims] 1. A television having a plurality of video signal processing units independently corresponding to respective formats of a plurality of different video signals, wherein at least one video signal processing unit among the video signal processing units is commonly used. In the John receiver, the feedback information about the modulation degree or amplification degree of the video signal,
It is provided with means for switching and supplying the plurality of video signal processing units according to a reception processing mode, and for controlling the feedback information, realizing a signal processing unique to the plurality of different video signals. Television receiver to do. 2. The television receiver according to claim 1, wherein the feedback information is an anode current detection signal of a cathode ray tube which is a display unit.