JPH0710108B2 - Playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention mixes a reproduction luminance signal and a reproduction carrier color signal and passes them through a common comb filter to remove crosstalk components from adjacent tracks. The present invention relates to a reproducing device.

[Outline of Invention]

The present invention is a reproducing apparatus in which a reproduction luminance signal and a reproduction carrier color signal are mixed and passed through a common comb filter to remove crosstalk components from adjacent tracks for each of them, and there is no reproduction carrier color signal. Occasionally, the reproduction luminance signal is prevented from being mixed with the output of the reproduction carrier color signal system to prevent the S / N of the reproduction luminance signal from deteriorating or the reproduction luminance signal to be beaten.

[Conventional technology]

Fig. 3 shows a rotating magnetic head type video tape recorder (VT
2 shows an example of a reproduction device of R).

In the figure, (1) is a magnetic tape, for example NTSC
The system color video signal is recorded as one diagonal track per field.

For example, the luminance signal is FM-modulated with a sync tip level of 4.2 MHz and a white peak level of 5.4 MHz and recorded in the form of an FM luminance signal. In this case, the FM modulation carrier frequency is shifted by 1 / 2fH (fH is a horizontal frequency) every 1 field (1 track), and the crosstalk component from the adjacent track and the main signal component from the original track are frequency interleaved. To be in a relationship.

The carrier color signal has a color subcarrier frequency of 3.58, for example.
The frequency is converted to the low frequency side of the FM luminance signal from MHz to about 743 KHz, and recorded in the form of the low frequency conversion carrier color signal.
In this case, at the time of frequency conversion, a so-called PI recording method is adopted in which the phase of the signal is inverted by 180 ° for each track and recorded, and the crosstalk component from the adjacent track and the main signal component from the original track are adopted. And have a frequency interleave relationship.

Further, in FIG. 3, (2A) and (2B) are rotating magnetic heads, and the recording tracks on the magnetic tape are sequentially scanned by these rotating magnetic heads (2A) and (2B), and these rotating magnetic heads are sequentially scanned. From (2A) and (2B), a composite signal of the FM luminance signal and the low-frequency conversion carrier color signal can be obtained.

This composite signal is supplied to the high-pass filter (4) via the reproduction amplifier (3), and the FM luminance signal is extracted from this. The FM luminance signal from this high pass filter (4) is
FM demodulation is carried out by the FM demodulation circuit (5), and the demodulated output, that is, the luminance signal is taken out through the low pass filter (6). The luminance signal extracted from the low-pass filter (6) has the main signal component Y from the original track and the crosstalk component Y _C from the adjacent track. It has a frequency interleave relationship with Y _C. The luminance signal taken out from the low pass filter (6) is supplied to the adder (7).

The combined signal from the rotating magnetic heads (2A) and (2B) is supplied to the low-pass filter (8) through the reproduction amplifier (3), and the low-frequency conversion carrier color signal is taken out from this.
The low-pass conversion carrier color signal from the low-pass filter (8) is returned to the carrier color signal of the original color subcarrier frequency of 3.58 MHz in the frequency conversion circuit (9), and this is transferred to the ACC circuit (1
0), taken out through the bandpass filter (11). The carrier color signal extracted from the bandpass filter (11) has a main signal component C from the original track and a crosstalk component C _C from an adjacent track. The frequency is interleaved with the talk component C _C. The carrier color signal taken out from the band pass filter (11) is supplied to the adder (7).

The mixed signal of the luminance signal (Y + Y _C ) and the carrier color signal (C + C _C ) from the adder (7) is fed by the delay circuit (12A) having a delay time of one horizontal period and the adder (12B). It is supplied to a so-called C-type comb filter (12), and the main signal component C of the carrier color signal and the crosstalk component Y _{C of the} luminance signal are extracted at the output side thereof.

The signal (C +) extracted from this comb-shaped filter (12)
Y _C ) is supplied to a trap circuit (13) for absorbing and attenuating the color subcarrier frequency (3.58 MHz) to extract the crosstalk component Y _C of the luminance signal, which is passed through a limiter (14) to a subtractor (15). ) Is supplied to. The subtractor (15) has a luminance signal (Y +) extracted from the low-pass filter (6).
Y _C ) is supplied, and the crosstalk component Y _C of the luminance signal is removed in the subtractor (15). Then, the main signal component Y of the luminance signal is extracted from the subtractor (15) and supplied to the adder (16).

In addition, the signal (C
+ Y _C ) is supplied to a bandpass filter (17) that allows the carrier color signal to pass, and the main signal component C of the carrier color signal is extracted from this bandpass filter (17) and supplied to an adder (16). . In the adder (16), the main signal component Y of the luminance signal and the main signal component C of the carrier color signal are added,
This added signal (Y + C), that is, the color video signal based on only the main signal component from which the crosstalk component has been removed is led to the output terminal (18).

Thus, according to the example of FIG. 3, the reproduction luminance signal (Y +
By mixing Y _C ) and the reproduced carrier color signal (C + C _C ) and passing them through a common comb filter (12), the crosstalk components Y _C and C _{C for each} are removed. The reproducing apparatus as shown in FIG. 3 is an example of a prior application, Japanese Patent Application No. 53-15, filed by the present applicant.
7,816 (Japanese Patent Application Laid-Open No. 55-82,583, Japanese Patent Application No. 59-244,096)
No. etc.

[Problems to be solved by the invention]

By the way, in the reproducing apparatus as shown in FIG. 3, for example, when a black and white video signal is recorded on the magnetic tape (1), that is, a carrier color signal is not recorded, the following problems occur. That is, when there is no reproduced carrier color signal, the ACC circuit (10) becomes full gain, and the noise at this time is mixed into the luminance signal via the adder (7), and the S /
N deteriorates. Further, when the ACC circuit (10) has a full gain, the distortion of the frequency conversion circuit (9) mixes with the reproduction luminance signal to cause a beat. In particular, 2.83MHz (4.32MHz−74
A frequency signal of 3 × 2 KHz) mixes with the playback luminance signal and causes a beat.

In view of such a point, the present invention, when there is no reproduction carrier color signal,
It is intended to prevent the deterioration of the S / N of the reproduction luminance signal and the occurrence of a beat in the reproduction luminance signal.

[Means for solving problems]

In order to solve the above-mentioned problems, the reproducing apparatus according to the present invention adopts the following configuration, for example, as shown in FIG.

When reproducing the color signal recorded so that the crosstalk component from the adjacent track of each of the luminance signal and the carrier color signal is frequency-interleaved with respect to the main signal component from the original track, each of the adjacent tracks is reproduced. A common comb-shaped filter (1
2) through which the crosstalk component is removed, a color killer circuit (21) provided before the mixing stage (7) of the reproduction carrier color signal system and the comb filter. The color killer detection circuit (25) provided at the output stage of the reproduction carrier color signal and the section corresponding to the burst signal of the reproduction carrier color signal are
Control signal generating means (26) for generating a control signal (SS) for disabling the color killer operation of the color killer circuit regardless of the detection output of the color killer detection circuit.
And the color killer circuit is activated when there is no reproduction carrier color signal, and the color killer circuit is deactivated in a section corresponding to the burst signal of the reproduction carrier color signal. Playback device.

[Action]

When there is no reproduction carrier color signal, the color killer circuit (21) provided in the preceding stage of the mixing stage (7) with the reproduction brightness signal of the reproduction carrier color signal system is in the operating state, and the reproduction carrier color signal system is included in the reproduction carrier color signal system. The output of will not be mixed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, the output of the band pass filter (11) is supplied to the fixed terminal on the A side of the switching switch (21) which constitutes the color killer circuit. The DC potential V _C of the carrier color signal is supplied from the terminal (22) to the B-side fixed terminal of the switching switch (21). Then, the signal obtained from the switching switch (21) is supplied to the adder (7).

The output of the band pass filter (17) is supplied to the adder (16) via the auto color killer circuit (23). In this auto color killer circuit (23), the burst signal level is detected, and when the detection level is below a predetermined level, it is in an operating state and the output of the band pass filter (17) is not supplied to the adder (16). It

The output of the bandpass filter (17) is supplied to the ACC detection circuit (24). The detection circuit (24) detects the burst signal level and controls the gain of the ACC circuit (10) based on the detection signal.

The output of the band pass filter (17) is supplied to the auto color killer detection circuit (25). In the detection circuit (25), the burst signal level is detected, and the output side thereof has a low level "0" when the detection level is below a predetermined level, and a high level "1" when the detection level is above the predetermined level.
Detection signal ▲ ▼ is output, and this detection signal ▲
▼ is supplied to one input side of the OR circuit (26). The other input side of the OR circuit (26) is supplied from the terminal (27) with the burst flag BFLG which becomes the high level "1" corresponding to the burst period. And this OR circuit (2
The output of 6) is supplied to the switching switch (21) as the switching control signal S _S. In this case, the switching switch (21) is connected to the A side when the switching control signal S _S is at the high level "1", and is connected to the B side when the switching control signal S _S is at the low level "0".

The present example is constructed as described above, and the others are constructed in the same manner as the example of FIG.

In the above structure, a color video signal is recorded on the magnetic tape (1), and when the color video signal is reproduced, the carrier color signal (C + C _C ) is taken out from the band pass filter (11).

The control signal S _S is always at a high level "1" during the burst period, and the switching switch (21) is connected to the terminal on the A side during the burst period. Therefore, when reproducing a color video signal, the band pass filter (17) is used during the burst period.
A burst signal of a predetermined level or higher is obtained, the detection signal ▲ ▼ of the detection circuit (25) becomes high level "1", and the control signal S _S always becomes high level "1". Therefore, the switching switch (21 ) Remains connected to the A side. Therefore, the carrier color signal (C + C _C ) taken out from the band pass filter (11) is supplied to the adder (7) via the switching switch (21), and accordingly, from the band pass filter (17), As in the example of FIG. 3, the main component signal C of the carrier color signal is extracted. Further, in this case, since the burst signal of a predetermined level or more is obtained from the band pass filter (17) in the burst period, the auto color killer circuit (23) does not operate and the carrier color signal from the band pass filter (17) is not operated. The main component signal C is an auto color killer circuit (2
It is supplied to the adder (16) via 3). Then, an addition signal (Y + C), that is, a color video signal is derived from the output terminal (18).

On the other hand, a black-and-white video signal is recorded on the magnetic tape (1), and the band-pass filter (1
The carrier color signal is not picked up from 1).

The control signal S _S is always at the high level "1" during the burst period, and the switching switch (21) is connected to the terminal on the A side during the burst period. However, when reproducing a black and white video signal,
In the burst period, the bandpass filter (17) cannot obtain a burst signal of a predetermined level or higher, the detection signal ▲ ▼ of the detection circuit (25) becomes low level "0", and the control signal S _S becomes high level only in the burst period. Therefore, the switching switch (21) is connected to the A side only during the burst period and remains connected to the B side during the other periods. Therefore, the output of the band pass filter (11) is not supplied to the adder (7) during the period other than the burst period. In this case, the gain of the ACC circuit (10) is
The output of the bandpass filter (11) is noise because it is set to full gain by the control of 4).

Also, in this case, during the burst period, since the burst signal above the predetermined level cannot be obtained from the bandpass filter (17), the auto color killer circuit (23) is in the operating state and the output of the bandpass filter (17) is the adder. (16)
Not supplied to. Incidentally, there is noise in the burst period of the output of the bandpass filter (17). Therefore, in this case, only the main signal component Y of the luminance signal, that is, the monochrome video signal is derived at the output terminal (18).

Thus, according to this example, when there is no reproduction carrier color signal,
Since the output of the band pass filter (11) is not supplied to the adder (7) except for the burst period,
Noise caused by the ACC circuit (10) having a full gain is not mixed in the reproduction luminance signal by the adder (7), and it is possible to prevent the S / N of the reproduction luminance signal from being deteriorated. Further, the distortion of the frequency conversion circuit (7) due to the full gain of the ACC circuit (10) is not mixed in the reproduction luminance signal by the adder (7), and the beat can be prevented from occurring in the reproduction luminance signal. it can. Furthermore, when there is no reproduction carrier color signal, noise is output from the band pass filter (17) especially during the burst period. At this time, since the auto color killer circuit (23) is in the operating state, this noise is added. The device (16) can prevent it from being mixed into the reproduction luminance signal.

Next, FIG. 2 shows another embodiment of the present invention.
In FIG. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, the output of the bandpass filter (11) is supplied to the adder (7) via the connection switch (31).

The output of the bandpass filter (11) is supplied to the fixed terminal on the B side of the switching switch (32). The output of the band pass filter (17) is supplied to the fixed terminal on the A side of the switching switch (32). Then, the signal obtained from the switching switch (32) is supplied to the adder (16) via the auto color killer circuit (23).

The output of the switching switch (32) is supplied to the auto color killer detection circuit (25), and the detection signal from this
▼ is a connection switch (31) and a switching switch (32)
As a control signal. In this case, the connection switch (31) is turned on when the detection signal {circle over (1)} is high level "1" and turned off when it is low level "0". Further, the switching switch (32) is connected to the A side when the detection signal ▲ ▼ is at the high level "1", and is connected to the B side when the detection signal ▲ ▼ is at the low level "0".

The example of FIG. 2 is configured as described above, and the others are configured similarly to the example of FIG.

In the above structure, the carrier color signal (C + C _C ) is taken out from the band pass filter (11) at the time of reproducing the color video signal.

During reproduction of this color video signal, since a burst signal of a predetermined level or higher is obtained from the switching switch (32) during the burst period, the detection signal of the detection circuit (25) ▲ ▼
Becomes a high level "1", the connection switch (31) is turned on, and the switching switch (32) remains connected to the A side. Therefore, the carrier color signal (C + C _C ) taken out from the band pass filter (11) is supplied to the adder (7) via the connection switch (31). Therefore, the main signal component C of the carrier color signal is taken out from the band pass filter (17) as in the example of FIG. Also, in this case, during the burst period, the switching switch (3
Since a burst signal of a predetermined level or higher is obtained via 2), the auto color killer circuit (23) does not operate, and the main signal component C of the carrier color signal from the band pass filter (17) is obtained.
Is supplied to the adder (16) via the switching switch (32) and the auto color killer circuit (23). Then, an addition signal (Y + C), that is, a color video signal is derived from the output terminal (18).

On the other hand, during reproduction of a black and white video signal, a burst signal of a predetermined level or higher cannot be obtained from the switching switch (32) during the burst period, and the detection signal of the detection circuit (25) ▲ ▼
Becomes a low level "0", the connection switch (31) is turned off, and the switching switch (32) remains connected to the B side. Therefore, the output of the band pass filter (11) is the adder (7).
Is not supplied to, but is output via the switching switch (32). In this case, since the gain of the ACC circuit (10) is full gain, the output of the bandpass filter (11) is noise.

Further, in this case, during the burst period, since the burst signal of the predetermined level or more cannot be obtained from the switching switch (32), the auto color killer circuit (23) is in the operating state, and the output of the band pass filter (11) is the adder (11). 16) is not supplied. Therefore, in this case, the output terminal (1
In 8), only the main signal component Y of the luminance signal, that is, the monochrome video signal is derived.

Thus, according to the example of FIG. 2, when there is no reproduction carrier color signal, the output of the bandpass filter (11) is added by the adder (7).
Therefore, it is possible to prevent the deterioration of the S / N of the reproduction luminance signal and the occurrence of a beat in the reproduction luminance signal, as in the example of FIG. Further, when there is no reproduced carrier color signal, the automatic color killer circuit (23) is activated, so that it is possible to prevent unnecessary noise from being added to the luminance signal by the adder (16).

〔The invention's effect〕

According to the present invention described above, when there is no reproduction carrier color signal, the reproduction luminance signal is prevented from being mixed with the output of the reproduction carrier color signal system.
It is possible to prevent the deterioration of N and the occurrence of a beat in the reproduction luminance signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a block diagram of an example of a reproducing apparatus. (7) is an adder, (10) is an ACC circuit, (12) is a comb filter, (21) is a switching switch, (23) is an automatic color killer circuit, (24) is an ACC detection circuit, and (25) is an automatic switch. It is a color killer detection circuit.

Claims (1)

[Claims] 1. When reproducing a color signal recorded so that a crosstalk component from an adjacent track is processed so as to be frequency interleaved with respect to a main signal component from an original track for each of a luminance signal and a carrier color signal. ,
In a reproducing apparatus adapted to remove the crosstalk component by mixing a reproduction luminance signal containing a crosstalk component from each of the adjacent tracks and a reproduction carrier color signal and passing through a common comb filter, A color killer circuit provided before the mixing stage of the signal system, a color killer detection circuit provided at the output stage of the reproduction carrier color signal of the comb filter, and a burst signal of the reproduction carrier color signal The section to do is
Control signal generating means for generating a control signal for disabling the color killer operation of the color killer circuit regardless of the detection output of the color killer detection circuit, and the color killer when there is no reproduction carrier color signal. A reproducing apparatus characterized in that the circuit is set to an operating state and the color killer circuit is set to an inoperative state in a section corresponding to the burst signal of the reproduction carrier color signal.