JPS6015864A - Recording signal processing circuit of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the waveform distortion, frequency characteristics and S/N by outputting the 1st and 2nd differentiation signal from an input luminance signal band adding a signal of a low level from which noise is eliminated to a luminance signal from which a high frequency component including noise is eliminated so as to output the result. CONSTITUTION:A high pass filter 12 differentiates the luminance signal and outputs the 1st differentiation signal, which is differentiated further by the 2nd high pass filter 13 and the result is given to an amplifier 14. The amplifier 14 amplifies the 2nd differentiation signal and gives the result to a slice circuit 15, which sets its slice level and outputs a signal from which a low level signal including noise is eliminated. The signal is inverted at an inverter 16, the level is adjusted by a variable resistor 20 and the result is given to a mixing circuit 18. On the other hand, a low pass filter 17 outputs a signal (e) which is formed by eliminating a high frequency component from the inputted luminance signal and gives the result to the other input of the mixing circuit 18. The mixing circuit 18 adds the signal of the original waveform to a signal whose waveform is inverted and outputs a luminance signal where noise component is eliminated and waveform distortion and frequency characteristic are improved to an output terminal 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording signal processing circuit for a magnetic recording/reproducing device, and in particular to improvement of waveform distortion and S/N of a video signal during recording in a home video tape recorder (hereinafter referred to as VTR). The present invention relates to a recording signal processing circuit that performs.

FIG. 1 is a block diagram for signal processing in a recording system of a conventional VTR. As shown in FIG. 1, in a conventional VTR, a video signal applied to an input terminal 1 is applied to a low-pass filter 2 to extract a luminance signal, and this luminance signal is sent to a clamp circuit 3. Pre-emphasis circuit 4. After being converted into an FM signal by an FM modulator 6 via a white/dark clip circuit 5, it is fed to a recording amplifier 7 for amplification, and is recorded on a magnetic tape from an output terminal 8 via a video head (not shown). . On the other hand, although the reproduction system is not shown, the FM signal obtained from the head is amplified by a reproduction amplifier, and the reproduction brightness is adjusted through a phase equalization circuit, a dropout compensation circuit, an FM demodulator, a pre-emphasis circuit, a noise canceller circuit, etc. I'm getting a signal. Normally, various circuit technologies are used to improve image quality so that the waveform of the video signal when recorded and played back approximates the original video signal waveform. There was a drawback that deterioration of N was unavoidable. In particular, when dubbing is performed, the resulting deterioration is added, resulting in a significant deterioration of image quality.

Therefore, the main object of the present invention is to improve the frequency characteristics of a luminance signal in a recording system of a magnetic recording/reproducing device.

An object of the present invention is to provide a recording signal processing circuit for a magnetic recording/reproducing device that can significantly improve phase characteristics and S/N.

To summarize this invention, the luminance signal separated in the recording system is passed through the M7 bypass filter to create a seventh-order differential signal (1), and the M2 bypass filter is passed through the M2 bypass filter to create a second-order differential signal, which is then amplified and waveform-shaped. A differential correction signal is created by removing a low-level component including noise, and the differential correction signal is added to a luminance signal obtained by removing a high-frequency component including noise from the original luminance signal.

The above objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

FIG. 2 is a schematic block diagram of an embodiment of the present invention,
FIG. 3 is a waveform diagram of each part of FIG. 2.

Next, the structure and operation of an embodiment of the present invention will be described with reference to FIGS. 2 and 3. The luminance signal ('M3
The signal shown in FIG. 2A is applied to the first bypass filter 12 and the low-pass filter 17 via the input terminal 11 shown in FIG. The bypass filter 12 differentiates the luminance signal and outputs a first differential signal shown in FIG. 3(b). This first
The differential signal is further applied to the second bypass filter 13, which further differentiates the first differential signal shown in FIG. The amplifier 14 amplifies the second differential signal and sends the signal shown in FIG. 3(C) to the slice circuit 15.
give to The slice circuit 15 sets its slice level to the level shown by the dotted line in FIG. 3(C), and outputs a signal having the waveform shown in FIG. 3(d) from which the low level portion including noise is removed. This signal is applied to the inverter 16, the polarity of which is inverted and applied to the variable resistor 2o. The variable resistor 20 adjusts the level of the signal and supplies it to the mixing circuit 18.

On the other hand, the low-pass filter 17 removes high-frequency components from the input luminance signal as shown in FIG. 3(e).
is output and applied to the other input of the mixing circuit 18. The mixing circuit 18 adds the signal with the waveform not shown in FIG. 3<e> and the signal whose polarity is inverted from the waveform shown in FIG. 3(d).
The output terminal 19 outputs a luminance signal as shown in FIG. 3(f) in which the noise component has been removed and the system distortion two-frequency characteristics have been improved.
Output to. rPp! output from output terminal 19! l!
The signal is sent to the clamp circuit 3 shown in FIG. Pre-emphasis circuit 4. FM via white/dark clip circuit 5
After being applied to a modulator 6 and subjected to FM modulation, it is sent to a recording amplifier 7.
is amplified and fed to the head.

As described above, according to the present invention, first and second differential signals are output from an input luminance signal, and low differential signals including noise are output.
Since the high-frequency component containing the noise from which the novel portion has been removed is added to the removed luminance signal and output, it is possible to improve the waveform distortion 9 frequency characteristics and S/N.

Therefore, it can be effectively used when the input video signal has deteriorated S/N, waveform distortion, and frequency characteristics, especially when dubbing is performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a recording system used in a conventional magnetic recording/reproducing device. FIG. 2 is a schematic block diagram of an embodiment of the present invention. FIG. 3 shows various parts of FIG. In the figure, 2.17 is a low-pass filter, 12, 13
14 is a bypass filter, 14 is an amplifier, 15 is a slice circuit, 16 is an inverter, 181 is a mixing circuit, and 20 is a variable resistor. Agent Masuo Daikun Figure 1 Figure 2 Name Figure 3

Claims (1)

[Scope of Claims] A first bypass filter that passes a high-frequency component of a luminance signal separated in a recording system and outputs a first differential signal, a first bypass filter that passes a high-frequency component of the output of the first bypass filter. a second bypass filter for outputting a second differential signal; and a waveform shaping means for outputting a differential correction signal obtained by amplifying and waveform shaping the output of the second bypass filter to remove a low-level portion including noise. A magnetic recording and reproducing apparatus, comprising: a low-pass filter that outputs a luminance signal obtained by removing high-frequency components including noise from the separated luminance signal; and a mixing means that mixes the output of the waveform shaping means and the output of the low-pass filter. Recording signal processing circuit.