JPS6350187A - Video recording and reproducing device - Google Patents

Abstract

PURPOSE:To contrive to prevent deterioration of CN ratio and to prevent malfunction of video apparatus such as a television etc. by providing a switching circuit that replaces pulse signals with area of horizontal synchronizing signals. CONSTITUTION:A change-over switch that replaces horizontal synchronizing signals utilizing accurate 15.734 KHz of AFC. A circuit 12 that forms low conversion frequency from horizontal synchronizing signals is oscillated at 2.52 MHz by horizontal synchronizing signals of 15.734 KHz separated by a horizontal synchronizing separator circuit 11 and then 1/4 frequency divided by a circuit 13 that forms low conversion frequency from horizontal synchronizing signals to make 629 KHz. Further, 629 KHz is 1/40 frequency divided by a circuit 14 that forms the same pulse with synchronizing signals from low conversion frequency, and accurate pulse signals of 15.734 KHz is formed, and signals of the horizontal synchronizing separator circuit 11 and signals of the circuit 14 are comparative detected. Horizontal synchronizing signals are replaced utilizing output signals of the circuit 14 at this time. Thereby, malfunction of video apparatus such as a television etc. and deterioration of SN ratio can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a video recording and reproducing device.

(Prior Art) In recent years, video recording and playback devices, especially video tape recorders (
There has been a remarkable improvement in the image quality of VTRs (hereinafter abbreviated as VTRs). Along with this, importance has been placed on the SN ratio, which is a measure of the image quality of a VTR. Conventionally, the luminance signal is output as is after processing the horizontal synchronization signal, so the horizontal synchronization signal is distorted or contains noise components.

FIGS. 4 and 5 show a block diagram of a reproduction system, input signals, and output signals of a conventional video recording and reproduction apparatus.

In FIG. 4, 41 is a video head that reproduces the FM signal recorded on the tape, 42 is a head amplifier that amplifies the low output of the reproduction signal reproduced by the video head 41;
43 is a block for processing the reproduced luminance signal; 44
is a block that processes the reproduced color signal. Fifth
In the figure, 51 is a video input signal, and 52 is a video output signal obtained by recording and reproducing a luminance signal.

The operation of the video recording and reproducing apparatus configured as above will be explained.

The reproduced signal is amplified to an appropriate size by the head amplifier 7D42 and separated into a luminance signal and a color signal. The separated signals are subjected to luminance signal processing and color signal processing, and are combined and output.

(Problems to be Solved by the Invention) In the above configuration, the frequency correction circuit introduced to accommodate diversifying image quality preferences causes distortion in the horizontal synchronization signal, causing malfunctions in video equipment such as televisions. do. Furthermore, if noise components are included due to dubbing, there is a drawback that the SN ratio deteriorates.

The purpose of the present invention is to eliminate the drawbacks of the conventional technology and to achieve horizontal synchronization by replacing the 15.734 kHz pulse signal of automatic frequency control (hereinafter abbreviated as AFC) with the horizontal synchronization signal after luminance signal processing in the reproduction system. It is an object of the present invention to provide a video recording and reproducing device in which signal distortion and noise components are removed, thereby preventing malfunction of video equipment and deterioration of the S/N ratio.

(Means for Solving the Problems) The video recording and reproducing apparatus of the present invention includes a horizontal synchronizing signal separation circuit that separates a horizontal synchronizing signal from a reproduced video signal, and a low frequency conversion frequency of a color signal based on the horizontal synchronizing signal. This switch circuit includes a signal processing circuit that forms a fundamental frequency, a pulse forming circuit that forms a pulse signal identical to the horizontal synchronization signal based on the fundamental frequency, and a switch circuit that replaces the pulse signal with the area of the horizontal synchronization signal. The output is output as a horizontal synchronization signal.

(Function) The present invention prevents deterioration of the SN ratio by replacing the horizontal synchronizing signal after luminance signal processing in the reproduction system and the 15.734 kHz pulse signal of the AFC with a changeover switch, and improves the signal-to-noise ratio of televisions, etc. This makes it possible to prevent malfunctions of video equipment.

(Example) An example of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 is a block diagram of a first embodiment of the present invention. In the figure, 1 is a head amplifier that amplifies the reproduced signal, 2 is a luminance signal processing block, 3 is a color signal processing block, 4 is an AFC circuit in the color signal processing block, and 5
is the horizontal synchronization signal after luminance signal processing and AFC of 15.73
A changeover switch to change the 4 kHz base signal,
6 is an output booster.

Regarding the video recording and reproducing apparatus configured as described above, the second
The operation will be explained with reference to the figure and FIG. 73. FIG. 2 shows a block diaphragm for extracting the 15.734 kHz /4' pulse signal of the AFC. The circuit 12 that forms the conversion frequency oscillates at 2.52 MHz, and then the circuit 13 that forms the conversion frequency lower than the horizontal synchronization signal divides the frequency by A to create 629 kHz, and then synchronizes the conversion frequency lower than the horizontal synchronization signal. Circuit 14 that forms the same route as the signal
Divide 629 kHz by 1/40 and get 15°734
An accurate pulse signal of kHz is generated, and a comparison circuit 15 compares and detects the signal of the horizontal synchronization separation circuit 11 and the signal of the circuit 14. The output signal of the circuit 14 at that time is used to replace the horizontal synchronization signal.

FIG. 3 shows a signal in which the horizontal synchronization signal is replaced and a signal in which the horizontal synchronization signal is not replaced. In the figure, 21 is an output waveform when the horizontal synchronization signal is not replaced, and includes a distortion noise component of the horizontal synchronization signal. Replace 22 with the synchronization signal in Figure 82/IP Luz Signal 16 (7) 1
This is the output waveform when the 5.734 kHz Nockles signal and horizontal synchronization signal are replaced.There is no distortion of the horizontal synchronization signal, and it does not contain noise components, so there is no malfunction of video equipment and no deterioration of the S/N ratio. It becomes less.

As described above, according to this embodiment, the AFC accuracy is 15.
By providing a changeover switch that switches horizontal synchronization signals using 734 kHz, it is possible to prevent malfunctions of video equipment such as televisions and deterioration of the S/N ratio.

(Effects of the Invention) According to the present invention, it is possible to prevent deterioration of the SN ratio and malfunction of video equipment, and it is also possible to prevent the malfunction of video equipment recorded conventionally, and the practical effects thereof are great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of the same essential parts, and FIG.
B) is a waveform diagram of a signal with and without horizontal synchronization signal replacement, Figure 4 is a block diagram of the playback system of a conventional video recording and playback device, and Figure 5 (4), a3) is the same. FIG. 3 is a waveform diagram of a video input signal and an output signal. 1... Head amplifier, 2... Luminance signal processing block, 3... Color signal processing block, 4... AFC circuit,
5... Selector switch, 6... Output increase device, 11...
・Horizontal synchronization separation circuit, 12.13...Circuit that forms a low frequency conversion frequency from the horizontal synchronization signal, 14...Circuit that forms the same Noculus as the synchronization signal from the low conversion frequency, 1
5... Comparison circuit, 16... Norms signal, 21.2
2...Output waveform. Figure 1 Figure 2 Figure 3 (A) CB) Figure 4 Figure 5 (A) CB)

Claims (1)

[Claims] a horizontal synchronization signal separation circuit that separates a horizontal synchronization signal from a reproduced video signal; a signal processing circuit that forms a fundamental frequency of a low frequency conversion frequency of a color signal based on the horizontal synchronization signal; A video recording device comprising: a pulse forming circuit that forms a pulse signal identical to the signal; and a switch circuit that replaces the pulse signal with a horizontal synchronization signal area, and outputs the output of the switch circuit as a horizontal synchronization signal. playback device.