JPH09121323A - Video signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video signal processor with which the detailed feeling of picture quality is not damaged and the amplitude of video signals is held even when dubbing is repeated in a magnetic video recording and reproducing device. SOLUTION: The amplitude frequency characteristics of a picture quality control circuit 9 are controlled by a pulse prepared from the output of a horizontal synchronizing separator circuit 11 by a pulse signal generating circuit 12 so that overshoot can be suppressed for the horizontal synchronizing signal section of a regenerative luminance signal and the rear edge section of a horizontal synchronizing signal and prescribed signal processing can be performed to the video signal section. Thus, the video signal processor, with which the detailed feeling of picture quality is not damaged and the amplitude of video signals is held even when dubbing is repeated, can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device in a video magnetic recording / reproducing device (hereinafter abbreviated as VTR) for recording / reproducing video signals.

[0002]

2. Description of the Related Art Hereinafter, reproduction signal processing of a conventional VTR video signal processing apparatus will be described with reference to the drawings.

FIG. 4A is a block diagram showing a configuration of a reproduction signal processing of a conventional VTR. In FIG. 4A, 1 is an input terminal to which a signal is input from a head amplifier (not shown), 2 is a frequency modulation signal demodulation circuit that demodulates the frequency modulation signal input from the input terminal 1 into a baseband signal, Reference numeral 3 is a de-emphasis circuit for returning the emphasized signal to the original, 4 is an amplitude frequency characteristic correction circuit for correcting the amplitude frequency characteristic, 8 is a low pass filter, 10 is an output amplifier, and 14 is an output terminal.

The operation of the conventional video signal processing device configured as described above will be described below.

The output signal of the head amplifier is input from the input terminal 1 to the frequency modulation signal demodulation circuit 2. The video signal demodulated from the frequency modulation signal to the baseband signal by the frequency modulation signal demodulation circuit 2 is input to the de-emphasis circuit 3 having the inverse characteristic of the emphasis characteristic in the recording signal processing. The output of the de-emphasis circuit 3 is input to the low pass filter 8 after the amplitude frequency characteristic is corrected by the amplitude frequency characteristic correction circuit 4. The output of the low-pass filter 8 is output from the output terminal 14 via the output amplifier 10.

In the VTR, the lack of detail due to the lack of the band is compensated by emphasizing the amplitude of the high frequency in the amplitude frequency characteristic correction circuit 4. However, by emphasizing the amplitude of the high frequency band, the reproduced signal has an overshoot as shown in FIG. 4B.

FIG. 5A shows an example of an automatic video signal amplitude control device (hereinafter abbreviated as AGC) used for VTR recording signal processing. Hereinafter, this AGC will be described with reference to FIGS. 5 (a) and 5 (b).

The video signal input from the input terminal 21 is
The amplitude is controlled by the amplitude control circuit 22 so that the maximum value of the signal obtained by adding the key pulse to the output of the clamp circuit 24 by the key pulse addition circuit 27 becomes constant, and the signal is output from the output terminal 29. The key pulse is generated by a key pulse generating circuit 26 which generates a rectangular pulse having a predetermined width from the output of the horizontal synchronizing signal separating circuit 25.

When performing dubbing on a VTR, as shown in FIG.
The output of the output terminal 14 of (a) is input to the input terminal 21 of (a) of FIG.

[0010]

However, FIG.
When a reproduced signal with overshoot as shown in (b) is input to the AGC circuit as shown in FIG. 5 (a), the key pulse is added to the overshoot portion at the trailing edge portion of the horizontal synchronizing signal. The tip of the overshoot is detected as the maximum value, and the output amplitude of the AGC becomes lower than the amplitude of the input reproduction signal (see FIG. 6B). Therefore, there is a problem that the amplitude of the video signal is reduced each time dubbing is repeated.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a video signal processing apparatus which does not impair the sense of detail in image quality and maintains the amplitude of the video signal even when dubbing is repeated. To do.

[0012]

In order to achieve the above object, the present invention provides a horizontal synchronizing signal separating circuit for separating a horizontal synchronizing signal and an output of the horizontal synchronizing signal separating circuit as an input to a leading edge of the horizontal synchronizing signal. A pulse generation circuit that outputs a rectangular pulse of a predetermined width by using as a trigger, and an image quality adjustment circuit that exhibits a predetermined amplitude frequency characteristic according to external control, and the image quality adjustment circuit controls the output signal of the pulse generation circuit. As a signal,
Since the pulse generation period has the first amplitude frequency characteristic and the pulse generation circuit has the second amplitude frequency characteristic other than the pulse generation period, the horizontal synchronization signal portion of the reproduction luminance signal and the horizontal synchronization signal The edge portion suppresses overshoot, and the video signal portion is subjected to predetermined signal processing.

Further, a horizontal synchronizing signal separating circuit for separating the horizontal synchronizing signal and a pulse generating circuit for receiving the output of the horizontal synchronizing signal separating circuit as an input and outputting a rectangular pulse of a predetermined width by using the leading edge of the horizontal synchronizing signal as a trigger. An all-pass filter circuit whose frequency characteristics of amplitude and group delay are flat in the video signal band, a low-pass filter circuit having the same delay time as the all-pass filter circuit and a predetermined cutoff frequency, and an output of the all-pass filter circuit And a switch circuit that receives the output of the low-pass filter circuit as an input,
The output of the low-pass filter circuit is selected during the pulse generation period of the pulse generation circuit in the switch circuit, and the output of the all-pass filter circuit is selected during periods other than the pulse generation period of the pulse generation circuit. The signal portion and the trailing edge portion of the horizontal synchronizing signal suppress overshoot, and the video signal portion is subjected to predetermined signal processing.

Further, a horizontal synchronizing signal separating circuit for separating the horizontal synchronizing signal and a pulse generating circuit for receiving the output of the horizontal synchronizing signal separating circuit as an input and outputting a rectangular pulse of a predetermined width by using the leading edge of the horizontal synchronizing signal as a trigger. And an amplitude frequency characteristic correction circuit, and a switch circuit that receives the output of the frequency characteristic correction circuit and the input of the frequency characteristic correction circuit as input. During the pulse generation period of the pulse generation circuit in the switch circuit, the input of the frequency characteristic correction circuit , And by selecting the output of the frequency characteristic correction circuit during periods other than the pulse generation period of the pulse generation circuit, the horizontal synchronization signal portion of the reproduction luminance signal and the trailing edge portion of the horizontal synchronization signal suppress overshoot.
The video signal portion is for performing predetermined signal processing.

Further, by switching the amplitude frequency characteristics between the horizontal synchronizing signal portion of the reproduction luminance signal and the trailing edge portion of the horizontal synchronizing signal, and the video signal portion, the horizontal synchronizing signal portion of the reproducing luminance signal and the rear synchronizing portion of the horizontal synchronizing signal are switched. The edge portion suppresses overshoot, and the video signal portion is subjected to predetermined signal processing.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention uses a horizontal synchronizing signal separation circuit and an output of the horizontal synchronizing signal separation circuit as an input, and a predetermined width by using a leading edge of the horizontal synchronizing signal as a trigger. Pulse generator circuit that outputs the rectangular pulse of
An image quality adjustment circuit that exhibits a predetermined amplitude frequency characteristic in accordance with control from the outside is provided, and the image quality adjustment circuit uses the output signal of the pulse generation circuit as a control signal and sets the first amplitude frequency characteristic during the pulse generation period. By having the second amplitude frequency characteristic other than the pulse generation period of the pulse generation circuit, overshoot is suppressed in the horizontal synchronizing signal portion of the reproduction luminance signal and the trailing edge portion of the horizontal synchronizing signal, and the video signal portion is suppressed. Is a video signal processing device characterized by performing a predetermined signal processing, and has an effect that the detail of the image quality is not impaired and the amplitude of the video signal is maintained even if dubbing is repeated.

According to a second aspect of the present invention, the horizontal synchronizing signal separating circuit and the output of the horizontal synchronizing signal separating circuit are input, and a rectangular pulse of a predetermined width is triggered by the leading edge of the horizontal synchronizing signal. A pulse generating circuit for outputting, an all-pass filter circuit having flat frequency characteristics of amplitude and group delay within a video signal band, a low-pass filter circuit having the same delay time as the all-pass filter circuit and having a predetermined cutoff frequency, A switch circuit that receives the output of the all-pass filter circuit and the output of the low-pass filter circuit as input, and selects the output of the low-pass filter circuit during the pulse generation period of the pulse generation circuit in the switch circuit to generate the pulse. By selecting the output of the all-pass filter circuit except during the pulse generation period of the circuit, The horizontal synchronizing signal portion of the signal and the trailing edge portion of the horizontal synchronizing signal suppress overshoot, and the video signal portion is a video signal processing device characterized by performing predetermined signal processing, without impairing the sense of detail of image quality, In addition, the amplitude of the video signal is maintained even if the dubbing is repeated.

According to a third aspect of the present invention, the horizontal synchronizing signal separation circuit and the output of the horizontal synchronizing signal separation circuit are input, and a rectangular pulse of a predetermined width is triggered by the leading edge of the horizontal synchronizing signal. A pulse generation circuit for outputting, an amplitude frequency characteristic correction circuit, and a switch circuit that receives an output of the frequency characteristic correction circuit and an input of the frequency characteristic correction circuit as input, and a pulse generation period of the pulse generation circuit in the switch circuit. In, by selecting the input of the frequency characteristic correction circuit, by selecting the output of the frequency characteristic correction circuit other than the pulse generation period of the pulse generation circuit,
A video signal processing device characterized by suppressing overshoot in the horizontal synchronizing signal portion of the reproduction luminance signal and the trailing edge portion of the horizontal synchronizing signal, and performing a predetermined signal processing in the video signal portion. In addition, the amplitude of the video signal is maintained even if the dubbing is repeated.

According to a fourth aspect of the present invention, the amplitude frequency characteristic is switched between the horizontal synchronizing signal portion of the reproduced luminance signal, the trailing edge portion of the horizontal synchronizing signal, and the video signal portion, whereby the reproduced luminance signal is reproduced. A video signal processing device characterized in that the horizontal sync signal portion and the trailing edge portion of the horizontal sync signal suppress overshoot, and the video signal portion is subjected to predetermined signal processing. This has the effect that the amplitude of the video signal is maintained even if the above is repeated.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1A is a block diagram showing a configuration of reproduction signal processing of a video signal processing apparatus of the present invention. Further, FIG. 3B shows the signal waveform of each part of FIG.

In FIG. 1, the same components as those in the prior art are designated by the same reference numerals and the description thereof will be omitted. 9
Is an image quality adjustment circuit that has an amplitude frequency characteristic that suppresses overshoot during the pulse generation period, and that has a flat amplitude frequency characteristic within the video band except for the pulse generation period, and 12 is a horizontal sync signal portion and a trailing edge portion of the horizontal sync signal. Is a pulse signal generation circuit that generates a pulse signal that is narrower than the width obtained by adding.

The operation of the present embodiment configured as described above will be described below.

The output signal of the head amplifier is input from the input terminal 1 to the frequency modulation signal demodulation circuit 2. The video signal demodulated from the frequency modulation signal to the baseband signal by the frequency modulation signal demodulation circuit 2 is input to the de-emphasis circuit 3 having the inverse characteristic of the emphasis characteristic in the recording signal processing. The amplitude frequency characteristic of the output of the de-emphasis circuit 3 is corrected by the amplitude frequency characteristic correcting circuit 4. The output of the amplitude frequency characteristic correction circuit 4 is input to the image quality adjustment circuit 9 through the low pass filter 8. The output of the image quality adjusting circuit 9 is input to the low-pass filter 8, passes through the output amplifier 10, and is output from the output terminal 14. The amplitude frequency characteristic of the image quality adjusting circuit 9 is wider than the width of the horizontal synchronizing signal portion with the leading edge of the output of the horizontal synchronizing separating circuit 11 that receives the output of the low pass filter circuit 8 as a trigger. It is controlled by the output of the pulse signal generating circuit 12 which generates a pulse signal having a width narrower than the width of the trailing edge of the signal.

The image quality adjusting circuit 9 includes a pulse signal generating circuit 1
By the control of No. 2, the pulse frequency has an amplitude frequency characteristic that suppresses overshoot, and the pulse frequency has a flat amplitude frequency characteristic in the video band except the pulse generation period.

As described above, according to the present embodiment, a horizontal sync signal and a reproduction signal without overshoot can be obtained only in the trailing edge portion of the horizontal sync signal, and the dubbing is repeated without impairing the detail feeling of the image quality. A reproduced signal with no decrease in amplitude can be obtained.

(Embodiment 2) FIG. 2A is a block diagram showing a configuration of reproduction signal processing of a video signal processing apparatus of the present invention. Further, FIG. 3B shows the signal waveform of each part of FIG.

In FIG. 2, the same components as those of the prior art are designated by the same reference numerals and the description thereof will be omitted. 5
Is an all-pass filter.

The operation of this embodiment will be described below. The output signal of the head amplifier is input from the input terminal 1 to the frequency modulation signal demodulation circuit 2. The video signal demodulated from the frequency modulation signal to the baseband signal by the frequency modulation signal demodulation circuit 2 is input to the de-emphasis circuit 3 having the inverse characteristic of the emphasis characteristic in the recording signal processing. The amplitude frequency characteristic of the output of the de-emphasis circuit 3 is corrected by the amplitude frequency characteristic correcting circuit 4. The output of the amplitude frequency characteristic correction circuit 4 is input to the all-pass filter 5 and the low-pass filter 6. The outputs of the all-pass filter 5 and the low-pass filter 6 are input to the switch circuit 7, the output of the switch circuit 7 is input to the low-pass filter 8, and is output from the output terminal 14 via the output amplifier 10. The switch circuit 7 is triggered by the leading edge of the output of the horizontal sync separation circuit 11 which receives the output of the low-pass filter 8 as a trigger, and is wider than the width of the horizontal sync signal portion and the horizontal sync signal portion and the trailing edge portion of the horizontal sync signal. It is controlled by the output of the pulse signal generation circuit 12 which generates a pulse signal narrower than the added width.

The delay times of the all-pass filter 5 and the low-pass filter 6 are equal, the all-pass filter 5 has a flat amplitude frequency characteristic in the video band, and the low-pass filter 6 has an amplitude frequency characteristic of suppressing overshoot of the reproduced signal. In the switch circuit 7, the output of the pulse signal generating circuit 12 selects the output of the low-pass filter 6 that suppresses overshoot in the horizontal synchronizing signal portion of the video signal and the trailing edge portion of the horizontal synchronizing signal, and the video signal portion is the all-pass filter 5 Output is selected.

As described above, according to the present embodiment, a reproduction signal without overshoot can be obtained only in the horizontal synchronizing signal portion and the trailing edge portion of the horizontal synchronizing signal, the detail feeling of the image quality is not deteriorated, and the dubbing is repeated. However, a reproduced signal with no decrease in amplitude can be obtained.

(Embodiment 3) FIG. 3A is a block diagram showing a configuration of reproduction signal processing of a video signal processing apparatus of the present invention. Further, FIG. 3B shows the signal waveform of each part of FIG.

In FIG. 3, the same components as those in the prior art are designated by the same reference numerals and the description thereof will be omitted. 1
A switch circuit 3 selects either the output of the de-emphasis circuit 3 or the output of the amplitude frequency characteristic correction circuit 4 under the control of the pulse signal generation circuit 12.

The operation of the present embodiment configured as above will be described below.

The output signal of the head amplifier is input from the input terminal 1 to the frequency modulation signal demodulation circuit 2. The video signal demodulated from the frequency modulation signal to the baseband signal by the frequency modulation signal demodulation circuit 2 is input to the de-emphasis circuit 3 having the inverse characteristic of the emphasis characteristic in the recording signal processing. The amplitude frequency characteristic of the output of the de-emphasis circuit 3 is corrected by the amplitude frequency characteristic correcting circuit 4. The switch circuit 13 receives the output of the amplitude frequency characteristic correction circuit 4 and the output of the de-emphasis circuit 3, and its output is the horizontal synchronization triggered by the leading edge of the output of the horizontal synchronization separation circuit 11 which receives the output of the low pass filter 8. It is controlled by the output of the pulse signal generating circuit 12 which generates a pulse signal wider than the width of the signal portion and narrower than the width of the horizontal synchronizing signal portion and the trailing edge portion of the horizontal synchronizing signal. The output of the switch circuit 13 is input to the low pass filter 8, and the output of the low pass filter 8 is output from the output terminal 14 via the output amplifier 10. In the switch circuit 13, the output of the de-emphasis circuit 3 in which the amplitude frequency characteristic is not corrected is selected by the output of the pulse signal generation circuit 12 for the horizontal synchronizing signal portion of the video signal and the trailing edge portion of the horizontal synchronizing signal.
For the video signal portion, the output of the amplitude frequency characteristic correction circuit 4 whose amplitude frequency characteristic has been corrected is selected.

As described above, according to the present embodiment, a reproduction signal without overshoot can be obtained only in the horizontal synchronizing signal portion and the trailing edge portion of the horizontal synchronizing signal, the detail feeling of the image quality is not deteriorated, and the dubbing is repeated. However, a reproduced signal with no decrease in amplitude can be obtained.

[0036]

As described above, according to the present invention, the excellent effect that the detail feeling of the image quality is not impaired and the amplitude is maintained even if the dubbing is repeated.

[Brief description of the drawings]

FIG. 1A is a block diagram of a reproduction system of a video signal processing device according to a first embodiment of the present invention. FIG. 1B is a signal waveform diagram of each part of a reproduction system of a video signal processing device according to the first embodiment of the present invention.

FIG. 2A is a block diagram of a reproduction system of a video signal processing device according to the second embodiment of the present invention. FIG. 2B is a signal waveform diagram of each part of the reproduction system of the video signal processing device according to the second embodiment of the present invention.

3A is a block diagram of a reproduction system of a video signal processing device according to a third embodiment of the present invention. FIG. 3B is a signal waveform diagram of each part of the reproduction system of the video signal processing device according to the third embodiment of the present invention.

FIG. 4A is a block diagram of a reproduction system of a conventional video signal processing device. FIG. 4B is a signal waveform diagram of each part of the reproduction system of the conventional video signal processing device.

5A is a block diagram of a conventional automatic video signal amplitude control device. FIG. 5B is a signal waveform diagram of each part of the conventional automatic video signal amplitude control device.

FIG. 6 is an output waveform diagram of a key pulse addition circuit when various signals are input to the conventional automatic video signal amplitude control device

[Explanation of symbols]

 1 Input terminal 2 Frequency modulation signal demodulation circuit 3 De-emphasis circuit 4 Amplitude frequency characteristic correction circuit 5 All pass filter 6 Low pass filter 7 Switch circuit 8 Low pass filter 9 Image quality adjustment circuit 10 Output amplifier 11 Horizontal sync separation circuit 12 Pulse signal generation circuit 13 Switch Circuit 14 output terminal

Claims (4)

[Claims] 1. A horizontal sync signal separation circuit for separating a horizontal sync signal, and pulse generation for outputting a rectangular pulse of a predetermined width by using an output of the horizontal sync signal separation circuit as an input and by using a leading edge of the horizontal sync signal as a trigger. A circuit and an image quality adjusting circuit that exhibits a predetermined amplitude frequency characteristic according to control from the outside, the image quality adjusting circuit uses the output signal of the pulse generating circuit as a control signal, and has a first amplitude during the pulse generating period. By having a frequency characteristic and a second amplitude frequency characteristic other than the pulse generation period of the pulse generation circuit, overshoot is suppressed in the horizontal synchronizing signal portion of the reproduction luminance signal and the trailing edge portion of the horizontal synchronizing signal, A video signal processing device, wherein a video signal portion is subjected to predetermined signal processing. 2. A horizontal synchronizing signal separating circuit for separating a horizontal synchronizing signal, and a pulse generator which receives an output of the horizontal synchronizing signal separating circuit as an input and outputs a rectangular pulse of a predetermined width by using a leading edge of the horizontal synchronizing signal as a trigger. A circuit, an all-pass filter circuit having flat frequency characteristics of amplitude and group delay within a video signal band, a low-pass filter circuit having the same delay time as the all-pass filter circuit and having a predetermined cutoff frequency, and the all-pass filter A switch circuit that receives the output of the circuit and the output of the low-pass filter circuit as an input, and in the pulse generation period of the pulse generation circuit in the switch circuit, the output of the low-pass filter circuit is selected, and the pulse of the pulse generation circuit is selected. By selecting the output of the all-pass filter circuit except the generation period, A video signal processing device characterized in that a horizontal synchronizing signal portion and a trailing edge portion of the horizontal synchronizing signal suppress overshoot and the video signal portion is subjected to predetermined signal processing. 3. A horizontal sync signal separation circuit for separating a horizontal sync signal, and a pulse generator which receives an output of the horizontal sync signal separation circuit as an input and outputs a rectangular pulse of a predetermined width by using a leading edge of the horizontal sync signal as a trigger. A circuit, an amplitude frequency characteristic correction circuit, and a switch circuit having an input of the output of the frequency characteristic correction circuit and an input of the frequency characteristic correction circuit,
In the pulse generation period of the pulse generation circuit in the switch circuit, by selecting the input of the frequency characteristic correction circuit, by selecting the output of the frequency characteristic correction circuit other than the pulse generation period of the pulse generation circuit, A video signal processing device characterized in that a horizontal synchronizing signal portion of a reproduction luminance signal and a trailing edge portion of the horizontal synchronizing signal suppress overshoot, and a video signal portion is subjected to predetermined signal processing. 4. A horizontal synchronizing signal portion of the reproduced luminance signal, a trailing edge portion of the horizontal synchronizing signal, and a trailing edge portion of the horizontal synchronizing signal by switching the amplitude frequency characteristic between the video signal portion. A video signal processing device characterized in that a part suppresses overshoot and a video signal part performs a predetermined signal processing.