JPH03198597A - Color video signal reproducing device - Google Patents

Abstract

PURPOSE:To suppress the increase in a phase modulation error of a chroma signal by providing three frequency converters using each conversion frequency signal from three oscillators and converting the frequency and outputting selectively an output signal from the 1st and 3rd frequency converter. CONSTITUTION:An output signal from a 1st frequency converter 6 and a 3rd frequency converter 13 is selectively outputted in response to the reproduction speed. For example, at normal reproduction, a moving contact (d) of a switch SW1 is connected to a fixed contact (a) and a moving contact (g) of a switch SW2 is connected to a fixed contact (e). At high speed reproduction, the moving contact (d) of the switch SW1 is thrown to a fixed contact (b) or (c) and the moving contact (g) of the switch SW2 is connected to a fixed contact (f). In the case of the U standards for reproduction and recording systems, the moving contact (d) of the switch SW1 is connected to a fixed contact (b) or (c). Thus, a phase modulation error of a chrominance carrier signal after conversion by the phase converter due to an increase in the phase fluctuation of a low frequency conversion chrominance carrier signal at high speed reproduction especially is not increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color video signal reproducing device suitable for application to a VTR or the like using a low frequency conversion carrier color signal recording method.

[Summary of the invention]

The present invention includes: a first frequency converter that converts the frequency of a low frequency conversion carrier color signal reproduced from a recording medium to a high frequency frequency; a first oscillator that generates an oscillation signal of a predetermined frequency; The phase of the oscillation signal from the first oscillator is synchronized with the phase of the output signal of the first frequency converter to obtain a first frequency signal for conversion, and the first frequency signal for conversion is converted into a first frequency signal. a phase adjuster that supplies the converter; a second frequency converter that converts the frequency of the low-pass conversion carrier color signal to a high-pass frequency using a second conversion frequency signal from a second oscillator; a third frequency converter that converts the frequency of the output signal of the second frequency converter to a low frequency using a third conversion frequency signal from a third oscillator, and By selectively outputting the first frequency converter and the third frequency converter, the increase in the phase variation of the low-frequency converted carrier color signal during high-speed reproduction causes This is to prevent the phase modulation error of the carrier color signal from increasing.

[Conventional technology]

A conventional example in which dubbing is performed using two VTRs of the J-conversion carrier color signal recording system will be described below with reference to FIG.

In Fig. 2, (31) and (32) are the playback side and recording side VTRs (here, U standard VTR), respectively, and the playback side VTR (31) has only the color signal processing circuit of the playback circuit. On the recording side VTR (32), only the color signal processing circuit of the recording circuit is shown.

Here, the running speed of the magnetic tape and the rotation speed of the rotating magnetic head in VTRs (31) and (32) are
Recording the reproduced color video signal from one magnetic tape onto another magnetic tape when the speed and number of rotations are respectively set to n times the standard speed (however, n = 1゜2.3...) This will be referred to as n-times speed dubbing. Also, in recording and reproduction, terms such as n-times speed playback and n-times speed recording are used. Incidentally, the cases where n≧2 are collectively referred to as high-speed dubbing. Also, high-speed recording and playback of n≧2, respectively.
This is called high-speed playback.

First, the color signal processing circuit of the reproduction circuit of the reproduction VTR (31) will be explained. (1) A rotating magnetic head reproduces a color video signal recorded on an inclined track of a magnetic tape. This color video signal is a multiplexed signal of an FM luminance signal and a low frequency conversion carrier color signal. The reproduced color image signal is supplied to a low pass filter (3) and a bypass filter (4) through a regenerative amplifier (2), respectively.

The low-pass filter (3) converts the reproduced color video signal from the reproduced amplifier (2) into a color subcarrier frequency of 68
A carrier color signal (hereinafter referred to as a chroma signal) of 8kllzXn is extracted. On the other hand, bypass filter (4)
From the reproduced color video signal from the reproduced amplifier (2), 3.8MHz
n FMgMg signals are output. This FM brightness signal is
Although illustration and description thereof are omitted, the signal is supplied to the luminance signal processing circuit.

(5) is an automatic chroma control amplifier (hereinafter referred to as ACC amplifier) whose gain is controlled by a control signal from the automatic chroma control error detector (hereinafter referred to as ACC detector) (9).
Adjust the difference in saturation for each head channel. (6)
is a frequency converter, where 4.27 from the automatic phase control error detector (hereinafter referred to as APC detector) (8)
A chroma signal with a color subcarrier frequency of 3.58Ml1zXn is obtained by multiplying the MHzXn carrier wave signal and the 688kHzXn Nori07 signal from the ACC amplifier (5). This chroma signal of 3.58M)lzXn is passed through a bandpass filter (7) to the recording V T
The signal is supplied to R (32) via the transmission line (14), and is also supplied to the APC detector (8) and the ACC detector (9).

The APC detector (8) is a bandpass filter (7)
The burst signal in the chroma signal of 3.58 Ml1zX n from the oscillator (1
0), and a voltage controlled oscillator that generates a carrier wave signal with an oscillation frequency of 4.27MH2Xn, which is controlled by the phase comparison output device. .

The ACC detector (9) compares the amplitude of the burst signal in the chroma signal of 3.58M)lzXn from the bandpass filter (7) and the oscillation signal of 3.58M)lzXn from the oscillator (10). , and supplies a control signal to the ACC amplifier (5) according to the level difference to control its gain.

Next, the color signal processing circuit of the reproduction circuit of the recording side VTR (32) will be explained. (16) is an ACC amplifier,
Through the transmission line (22) and input terminal T2, the reproduction VT
The gain of the chroma signal supplied from R (31) is controlled by the control signal from the ACC detector (17),
Adjust the difference in saturation for each head channel.

The ACC detector (17) detects the ACC amplifier (16) based on the level difference between the burst signal in the chroma signal from the ACC amplifier (16) and the oscillation signal of an oscillator whose oscillation frequency is 3.58 Mflz (not shown). The gain is controlled to adjust the difference in saturation for each head channel.

(18) is a frequency converter, which outputs 4 from the oscillator (20).
．． 27MIIzX n carrier wave signal and ACC amplifier (
3 from 16). Multiply the chroma signal of $5'8 MIIz X n to obtain the chroma signal of 688ktlzXn. The frequency of the oscillator (20) is controlled by a control signal from an automatic frequency control error detector (hereinafter referred to as AFC detector) (21). AFC detector (21
) oscillates based on the phase fluctuation of the horizontal synchronization signal separated from the luminance signal of the color video signal to be recorded! H(20
) controls the oscillation frequency of

3.58MHzX output from the frequency converter (18)
The n chroma signals are outputted via a low-pass filter (19). Although not shown in the figure, the low frequency converted chroma signal from the chroma signal processing circuit is mixed with the FM luminance signal from the luminance signal processing circuit, passed through a recording amplifier, and is tilted onto a magnetic tape by a rotating magnetic head. It is recorded to form a track.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional color video signal reproducing device, the carrier signal supplied to the frequency converter (6) is a burst signal in the chroma signal from the bandpass filter (7) and an oscillation signal from the oscillator (1o). Since this is a signal whose frequency is controlled by the phase difference, there is no problem during 1x speed playback where n = 1, but when playing back at high speed where n≧2, the phase fluctuation of the chroma signal increases, so the phase may not be completely locked. In this case, after frequency conversion of the chroma signal by the frequency converter, the phase modulation error of the chroma signal increases.

In view of this, the present invention proposes a color video signal reproducing apparatus that does not increase phase modulation errors of chroma signals even during high-speed reproduction.

[Means to solve the problem]

The present invention includes a first frequency converter (6) that converts the frequency of a low frequency conversion carrier color signal reproduced from a recording medium to a high frequency frequency, and a first oscillator that generates an oscillation signal of a predetermined frequency. (10) and the phase of the oscillation signal from the first oscillator (10) is synchronized with the phase of the output J signal of the first frequency converter (6) to obtain a first conversion frequency signal. , a phase adjuster (8) that supplies the first frequency signal for conversion to the first frequency converter (6), and a phase adjuster (8) that supplies the first frequency signal for conversion to the first frequency converter (6), and a phase adjuster (8) that supplies the first frequency signal for conversion to the first frequency converter (6); A second frequency converter (11) converts the frequency signal to a high frequency using a conversion frequency signal, and a third oscillator (15B) converts the frequency of the output signal of the second frequency converter (11) to a high frequency. A third converter that converts to a lower frequency using the third conversion frequency signal of
frequency converter (13), depending on the playback speed,
The first frequency converter (6) and the third frequency converter (1
The output signal from 3) is selectively output.

[Operation] According to the present invention described above, the output signals from the first frequency converter (6) and the third frequency Pi converter (13) are selectively outputted depending on the playback speed.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. , the redundant explanation will be omitted.

FIG. 1 shows an embodiment of a color video signal reproducing apparatus according to the present invention.

In the following, parts of the embodiment shown in FIG. 1 that are different from the conventional example shown in FIG. 2 will be explained. (11) is a frequency converter,
688kHz x n chroma signal from ACC amplifier (5) and 4.27MHz x n from oscillator (15)
Multiply the carrier signal. The chroma signal of 3.58 M1lzX n from this frequency converter (11) is supplied to a frequency converter (13) via a bandpass filter (12). The frequency converter (13) is an oscillator (15B
) is converted into a chroma signal of frequency BXn by multiplying the carrier signal of frequency FXn from the bandpass filter (12) by the chroma signal of 3.58 MIIzX n from the bandpass filter (12). This converted BXn chroma signal is supplied to a low pass filter (14).

By arbitrarily selecting the oscillation frequency FXn of the oscillator (15B), a low-pass converted carrier color signal with an arbitrary color subcarrier frequency BXn can be obtained from the low-pass filter (14). According to the Umatic standard, when F=4.27 MIIz, a carrier color signal with a color subcarrier frequency of 688 kHz is output from the low-pass filter (4).

In this case, the oscillators (15A) and (15B) can be shared.

For Betamax standard, F = 4.27MtLz
The Xn crystal oscillator and the phase of its oscillation signal are supplied with a horizontal synchronizing signal extracted from the reproduced color video signal and a signal switching pulse of the rotating magnetic head, and the phase is inverted every horizontal period, and the phase of the oscillation signal is inverted every horizontal period. a phase control circuit that reverses the phase between the oscillator (15B)
All you have to do is configure.

Vf (in the case of the S standard, the phase of the crystal oscillator of F = 4.21 MHz The oscillator (15B) may be configured from a phase control circuit that reverses the direction of change of the oscillator (15B).

Now, there is a selector switch SW on the playback VTR (31) side.
1 is provided, and its fixed contacts a, b, and c are connected to a band pass filter (7), a low pass filter (14), and a CC, respectively.
It is connected to each output side of the amplifier (5), and its movable contact is connected to the movable contact g of the switch SW2 when provided on the recording side VTR (32) through the transmission line (22). Fixed contacts e and f of the changeover switch SW2 are connected to the input side of the ACC amplifier (16) and the output side of the low-pass filter (9), respectively.

First, during normal playback (1x speed playback), switch S
The movable contact d of W1 is connected to the fixed contact a, and the switch S
The movable contact g of W2 is connected to the fixed contact e. At this time, the band pass filter (7) of the reproduction VTR (31)
) is supplied to the ACC amplifier (16) of the recording VTR (32) through the transmission path (22).

During high-speed playback, the movable contact d of the selector switch S W +
is connected to the fixed contact S or C, and the movable contact g of the changeover switch SW2 is connected to the fixed contact f.

If both the playback and recording methods are U standard, selector switch S
The movable contact d of W1 is connected to the fixed contact C. The playback system is U standard and the recording system is Betamax or VH3.
In this case, the movable contact d of the changeover switch SWI is connected to the fixed contact s.

〔Effect of the invention〕

According to the present invention described above, the first converter converts the frequency of the low-band conversion carrier color signal reproduced from the recording medium to a high-band frequency.
a frequency converter, a first oscillator that generates an oscillation signal of a predetermined frequency, and a first oscillator that synchronizes the phase of the oscillation signal from the first oscillator with the phase of the output signal of the first frequency converter. a phase modulator that obtains a first conversion frequency signal and supplies the first conversion frequency signal to a first frequency converter;
The frequency of the low-pass converted carrier chrominance signal is
a second frequency converter that converts the frequency of the output signal of the second frequency converter to a high frequency using a conversion frequency signal from a third oscillator; and a third frequency converter that converts the frequency to a lower frequency.
By selectively outputting the frequency converter and the third frequency converter, the carrier color after conversion by the phase converter increases due to the increase in the phase variation of the low frequency converted carrier color signal especially during high-speed reproduction. The phase modulation error of the signal does not increase.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. (6) is a frequency converter, (8) is an ACC detector, (10) is an oscillator, (11) and (13) are frequency converters, and (15) is an oscillator. Agent Hidemori Matsukuma

Claims (1)

[Scope of Claims] A first frequency converter that converts the frequency of a low frequency conversion carrier color signal reproduced from a recording medium to a high frequency frequency, and a first oscillator that generates an oscillation signal of a predetermined frequency. , synchronizing the phase of the oscillation signal from the first oscillator with the phase of the output signal of the first frequency converter to obtain a first conversion frequency signal; a phase modulator that supplies the first frequency converter to the first frequency converter; a frequency converter, and a third frequency converter that converts the frequency of the output signal of the second frequency converter to a low frequency using a third conversion frequency signal from a third oscillator. A color video signal reproducing device comprising: selectively outputting signals from the first frequency converter and the third frequency converter according to a reproduction speed.