JPH04326865A - Horizontal blanking circuit - Google Patents

Abstract

PURPOSE:To obtain the horizontal blanking signal of proper pulse width in accordance with an input signal in respect of the horizontal blanking circuit of a high definition television receiver, etc., to input various kinds of high definition television video signals different in their blanking periods for every input signal. CONSTITUTION:The subject circuit is constituted of an input signal detection circuit 3 to output a detection signal corresponding to the input video signal from the difference of the frequency of a horizontal synchronizing signal from a synchronizing separator circuit 15, a microcomputer 4 for control to output a switching signal on the detection signal, a first monostable multivibrator 1 to generate the horizontal blanking signal to be used in common for both a studio standard base band signal and an MUSE decoder output signal, a second monostable multivibrator 2 to generate the horizontal blanking signal for an NTSC-HD converter output signal, and a horizontal blanking signal switching circuit 5 to switch the output signals from each of the monostable multivibrators by the switching signal from the microcomputer 4 for control.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to horizontal blanking circuits of high-definition receivers or high-definition display monitors that use various high-definition signals with different horizontal blanking periods for each signal as input video signals. The present invention relates to a horizontal blanking circuit that generates a pulse-width horizontal blanking signal.

0002

2. Description of the Related Art A conventional horizontal blanking circuit is shown in FIG. In the figure, 11 is a studio standard baseband signal (hereinafter referred to as "video A") input line, and 12 is an MU
13 is an input line for the SE decoder output signal (hereinafter referred to as "video B"), 13 is an input line for the NTSC-HD converter output signal (hereinafter referred to as "video C"), 14 is an input video signal switching circuit, 15 is an input line The input video signal switching circuit 1
4, a sync separation circuit separates the sync signal from the video signal; 16 separates the horizontal sync signal (HD) from the sync separation circuit 15;
); 17, a waveform shaping circuit that shapes the horizontal pulse obtained from the horizontal deflection circuit 16 and outputs it as a horizontal blanking pulse; 18, the horizontal blanking pulse is a video signal; This is a video circuit that is superimposed on the There are the above-mentioned types of video signals that are generally referred to as high-definition signals. Here, video A is a video signal from a high-definition VTR and high-definition DISK, video B is a video signal obtained by decoding broadcast waves from satellites or cables, etc., and video C is a high-definition video signal obtained by decoding broadcast waves from satellites or cables, etc. This is a video signal converted by a converter into a signal. The horizontal blanking periods of these video signals are different from each other as shown in FIGS. 2(A to C). A conventional horizontal blanking signal for such a video signal is as shown in FIG. 2(D).
This is a signal with a constant pulse width that matches video C (C in the same figure), which has the longest blanking period. This blanking signal is obtained by shaping the horizontal pulse generated by the horizontal deflection circuit 16 into a waveform having the same pulse width so as to provide sufficient blanking. The horizontal deflection circuit 16 is a general term for a horizontal oscillation circuit, a horizontal output circuit, a flyback transformer, etc., and the horizontal pulse can be obtained from the horizontal output circuit or the flyback transformer.

0003

As mentioned above, the conventional horizontal blanking signal is a signal with a constant pulse width that matches the video signal with the longest blanking period. A)], blanking is applied to the effective video signal portion. Therefore, the video signal in such a portion is erased without being reproduced on the screen. Conversely, if the pulse width of the horizontal blanking signal is matched to that of video A, blanking will be insufficient in video C, and folding of scanning lines will appear at the left and right edges of the screen. SUMMARY OF THE INVENTION An object of the present invention is to provide a horizontal blanking circuit that generates a horizontal blanking signal with an appropriate pulse width depending on the type of signal, in order to improve this drawback.

0004

[Means for Solving the Problems] The present invention provides a studio standard baseband signal, a MUSE decoder output signal and an N
In the horizontal blanking circuit of a high-definition receiver or high-definition display monitor that receives each TSC-HD converter output signal as an input signal, it is possible to detect which input signal is the input signal from the difference in frequency of the horizontal synchronization signal input from the synchronization separation circuit. , outputs the same detection signal when the input signal is the studio standard baseband signal or the MUSE decoder output signal, and outputs the same detection signal when the input signal is the studio standard baseband signal or the MUSE decoder output signal;
an input signal detection circuit that outputs a different detection signal when the C-HD converter output signal is detected; a control microcomputer that outputs a switching signal based on the detection signal from the input signal detection circuit; and a horizontal deflection control circuit. A horizontal pulse from the circuit is input as a trigger pulse, and a horizontal blanking signal common to both the studio standard baseband signal and the MUSE decoder output signal and a horizontal blanking signal for the NTSC-HD converter output signal are separately and independently generated. The output signal from the first monostable multivibrator is supplied to one end of the fixed end, and the output signal from the first monostable multivibrator is supplied to the other end of the fixed end. A switching circuit that supplies the output signal from the two monostable multivibrators, and a switching circuit that supplies one of the horizontal blanking signals taken out from the movable end to the video circuit by switching with a switching signal from the control microcomputer. This provides a blanking circuit.

[0005]

[Operation] A first monostable multivibrator that generates a horizontal blanking signal with a pulse width that is compatible with video A and video B, and a second monostable multivibrator that generates a horizontal blanking signal with a pulse width that is compatible with video C. A monostable multivibrator is provided, which switches each input signal and supplies it to the video output circuit.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A horizontal blanking circuit according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts showing an embodiment of a horizontal blanking circuit according to the present invention. In the figure, the same parts as in FIG. 3 are given the same reference numerals, and 1 is a horizontal blanking signal having a pulse width suitable for video A and video B, using the horizontal pulse from the horizontal deflection circuit 16 as a trigger pulse. 2 is a first monostable multivibrator (hereinafter referred to as "first M.M.") that generates a horizontal blanking signal suitable for video C. 3 detects which video signal it is from the frequency of the horizontal synchronization signal (HD) (code 6) from the sync separation circuit 15 and outputs a detection signal (hereinafter referred to as "second M.M"). 7) an input signal detection circuit for detecting; 4 a control microcomputer that outputs a switching signal based on the detection signal; 5 switching signals from the first M/M1 and the second M/M2 using the switching signal; This is a horizontal blanking signal switching circuit that supplies a horizontal blanking signal suitable for the input video signal to the video circuit 18.

Next, the operation of the present invention will be explained. The input signal detection circuit 3 detects the type of input signal from the difference in frequency of the horizontal synchronizing signal as described above, and the frequency is 33.75 kHz for video A and video B, and 31.47 kHz for video C. It is. As for the detection signal, the former is a high level output (H) and the latter is a low level output (L) (or vice versa). The control microcomputer 4 switches the horizontal blanking signal switching circuit 5 using a switching signal according to the detection signal. The horizontal blanking signal switching circuit 5 has a first M.M. and a second M.M.
Since the horizontal blanking signal is supplied from M and M, a horizontal blanking signal suitable for the input selected video signal is supplied to the video circuit 18. The horizontal blanking signal generated by the first M/M1 is a signal whose pulse width is equal to the blanking period of video B (4.44 μS), or a signal whose pulse width is equal to the blanking period of video A and video B (3.77 μS). There is a signal with a pulse width of 4.44 μS). In the former case, since it is not completely compatible with video A, some of the conventional problems described above remain, but it is definitely an improvement over the conventional method. In addition, by using a monostable multivibrator, Figure 3
Waveform shaping like this is not necessary.

[0008]

As explained above, according to the present invention, the studio standard baseband signal, the MUSE decoder output signal, and the NTSC-HD converter output signal, etc.
Horizontal blanking in high-definition receivers, etc. that input video signals with different horizontal blanking periods for each signal is determined by the type of input video signal and set to an appropriate pulse width, so horizontal blanking with a constant pulse width is always performed. This method solves the problem of erasing effective video signal components caused by conventional methods that use ranking signals, and greatly contributes to improving the performance of high-definition receivers, high-definition display monitors, and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram of essential parts showing an embodiment of a horizontal blanking circuit according to the present invention.

[Figure 2] Horizontal blanking period for various video signals (
A to C) and a horizontal blanking signal (D).

FIG. 3 is a block diagram of main parts showing an embodiment of a conventional horizontal blanking circuit.

[Explanation of symbols]

1 First monostable multivibrator 2
Second monostable multivibrator 3 Input signal detection circuit 4 Control microcomputer 5 Horizontal blanking signal switching circuit 6 Horizontal synchronization signal line 7 Detection signal line 11 Studio standard baseband signal input line 12
Input line 13 N of MUSE decoder output signal
Input line 14 of TSC-HD converter output signal
Input video signal switching circuit 15 Sync separation circuit 16 Horizontal deflection circuit 17 Waveform shaping circuit 18 Video circuit

Claims (1)

[Claims] [Claim 1] Studio standard baseband signal and MU
In a horizontal blanking circuit of a high-definition receiver or a high-definition display monitor that receives an SE decoder output signal and an NTSC-HD converter output signal as input signals, the horizontal blanking circuit of a high-definition receiver or high-definition display monitor receives an SE decoder output signal and an NTSC-HD converter output signal as input signals. When the input signal is the studio standard baseband signal or the MUSE decoder output signal, the same detection signal is output, and when the input signal is the NTSC-HD converter output signal, a different detection signal is output. an input signal detection circuit that outputs a detection signal; a control microcomputer that outputs a switching signal based on the detection signal from the input signal detection circuit; and a horizontal pulse from the horizontal deflection circuit that is input as a trigger pulse;
A horizontal blanking signal common to both the studio standard baseband signal and the MUSE decoder output signal, and the N
A first monostable multivibrator and a second monostable multivibrator each independently generate a horizontal blanking signal for the TSC-HD converter output signal, and a fixed end of the first monostable multivibrator. by supplying an output signal from the second monostable multivibrator to the other end of the fixed end, and switching by a switching signal from the control microcomputer, either horizontal A horizontal blanking circuit comprising a switching circuit that supplies a blanking signal to a video circuit.