JPH0636254B2 - Magnetic recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus (hereinafter referred to as VTR) having an automatic tracking control system.

[Prior Art] FIG. 7 shows, for example, Japanese Patent Publication No. 55-51256 and Japanese Patent Publication No. 55-512.
It is a block diagram which shows the structure of the conventional automatic tracking control system of the VTR shown by the 57th publication.

In the figure, (1) is a magnetic tape on which a video signal (2) and a control signal (3) used for a tracking servo during reproduction are recorded. (4A) and (4B) are rotating heads,
These video signals are reproduced, and these rotary heads (4A) and (4B) are mounted on a rotary drum (6), controlled by a drum motor drive circuit (7), and rotated by a drum motor (8) to a predetermined rotation speed. It is rotated at a constant speed by a number. (5) is a fixed control head, which reproduces the control signal (3).

(10) is a frequency generator that generates a frequency signal (hereinafter referred to as FG signal) proportional to the rotation speed.
A capstan motor drive control circuit (hereinafter referred to as a CP motor drive control circuit) to which an FG signal generated by (0) is added (11) is controlled by a capstan motor (hereinafter referred to as a CP motor) (9) The pulley (12),
The magnetic tape (1) is driven in the direction of arrow a via the belt (13) and the capstan (14).

Reference numeral (16) is a control signal amplifying circuit, and (17) is a phase comparing circuit, which receives the control signal amplified by the amplifying circuit (16) as one input. (20) is a phase adjustment circuit, a rotary phase signal obtained by detecting the magnet piece (18) attached to the rotary drum (6) by a fixed detection head (19),
That is, the phases of the rotation angle signals of the both rotary heads (4A) and (4B) are adjusted, and the phase adjustment signal is supplied to the phase comparison circuit (17).
The other input of. The error signal of the phase comparison circuit (17) is applied to the CP motor drive control circuit (11).

Reference numeral (21) is a rotary transformer, and (22) is a head amplifier, which takes out the video FM signal reproduced by the rotary heads (4A), (4B), amplifies it, and adds it to the envelope detection circuit (23). (24) is a peak hold circuit, and the head amplifier (2
The output of 2) is added and the maximum value of the envelope signal is held. Reference numeral (25) is a comparator, to which the envelope detection signal output from the envelope detection circuit (23) and the output signal from the peak hold circuit (24) are applied.

(26) is a differentiating circuit to which the output of the comparator (25) is applied. (27) is a flip-flop circuit, which is the differentiation circuit
The positive and negative output voltage polarities are inverted by the output of (26). (28)
Is an integrator circuit, which integrates the output of the flip-flop circuit (27) and outputs the phase adjustment circuit (20) according to the output polarity.
Control the phase of. (29) is a gate circuit.

Next, the operation of the above configuration will be described.

The FM signal generated by the frequency generator (10) is applied to the CP motor drive control circuit (11) so that the CP motor
(9) is driven and controlled, and the magnetic tape (1) is passed through the pulley (12), the belt (13) and the capstan (14) to move the magnetic tape (1) to the arrow a in FIG.
Direction drive, drum motor drive circuit (7)
The drum motor (8) is driven to rotate at a predetermined rotation speed via the. At this time, the control signal reproduced by the control head (5) and amplified by the control signal amplification circuit (16) is applied to one input of the phase comparison circuit (17), and the other of this phase comparison circuit (17) is also added. A signal whose phase has been adjusted by the phase adjusting circuit (20) by the rotational phase signal detected by the fixed detection head (19) of the magnet piece (18) attached to the rotating drum (6) is added to the input of the.

The error signal of the phase comparison circuit (17) is applied to the CP motor drive control circuit (11) to finely control the CP motor (9) driven near the predetermined speed by this drive control circuit (11). To control the running of the magnetic tape (1) to the rotating head (4
The rotation phase of A) and (4B) and the reproduction phase of the control signal (3) are controlled so as to have a phase relationship determined by the phase adjustment circuit (20). As a result, the rotary heads (4A), (4B) scan on the fixed relative position of the track of the video signal (2) determined by the phase adjusting circuit (20).

On the other hand, the video F reproduced by the rotating heads (4A) and (4B)
The M signal is taken out by the rotary transformer (21) and amplified by the head amplifier (22) to be detected by the envelope detection circuit (2
The envelope signal input to 3) and detected here is applied to the comparator (25).

The output of the head amplifier (22) is the peak hold circuit (24).
The output of this peak hold circuit (24) and the output of the envelope detection circuit (23) are also added to the comparator (2
Added to 5). In this comparator (25), the output voltage (Vp) of the peak hold circuit (24) and the output voltage (Ve) of the envelope detection circuit (23) are compared, and the voltage difference is set to an appropriately set threshold ( Determine whether it is smaller or larger than e ₀ ).

Then, the output of the comparator (25) is applied to the differentiating circuit (26) and positive and negative pulses are generated every time the output of the comparator (25) is inverted. The flip-flop circuit (27) is triggered only by the negative pulse of the differentiating circuit (26) to invert between the positive and negative output voltage levels. The output of the flip-flop circuit (27) is added to the integration circuit (28) and integrated, and converted into an increase / decrease signal according to the output voltage polarity of the flip-flop circuit (27) to control the phase of the phase adjustment circuit (20). To do.

Now, when the output voltage of the flip-flop circuit (27) is at a positive voltage level and the output of the integration circuit (28) is in the increasing direction when the phase of the phase adjustment circuit (20) is as shown in FIG. The phase of the adjusting circuit (20) changes in the increasing directions of (b) and (c). Accordingly, the output of the envelope detection circuit (23) sequentially increases, goes through the maximum envelope value shown by the broken line (30) in FIG. 8 and then decreases again, and the phase of the phase adjustment circuit (20) changes.
When the state of (d) is reached, the output voltage (Ve) of the envelope detection circuit (23) and the output voltage (Vp) of the peak hold circuit (24) which is the maximum envelope voltage shown by the broken line (30) in FIG. The difference between the comparator and the comparator (2
Since it becomes the predetermined threshold value of 5), the comparator (25) inverts from the positive level to the negative level, and accordingly, the differentiating circuit (26) generates a negative pulse to set the flip-flop circuit (27) to the negative voltage level. Invert. As a result, the output of the integrating circuit (28) begins to decrease, and the phase of the phase adjustment circuit (20) decreases again.
Change from (d) to (c).

As described above, the phase of the phase adjustment circuit (20) is (b) in FIG.
→ It is controlled so that it varies between (d) and the output voltage of the envelope detection circuit (23) varies between the voltages shown by the broken lines (30) and (31), and the threshold value (e ₀ ) is adjusted appropriately. Tracking adjustment is automatically performed by setting.

[Problems to be Solved by the Invention] Since the conventional VTR is configured as described above, although it has a provisional automatic tracking adjustment function, its tracking performance is low and practically not used in an actual VTR. .
In particular, VHS high-definition system (hereinafter referred to as HIFI)
Since tracking control of only a video signal is performed in a VTR of a system in which a video signal is recorded and reproduced on a surface layer portion of a magnetic surface of a magnetic tape and a HIFI portion on a deep layer portion in different heads like a video, HIFI
There was a problem that the S / N of the audio deteriorated due to insufficient tracking of some parts.

The present invention has been made in order to solve the above-mentioned problems, and even in a deep recording type HIFIVTR, or in a read-only VTR that adopts a wide head in which special playback functions such as still and slow are emphasized, It is an object of the present invention to provide a VTR capable of performing automatic tracking adjustment with extremely high performance.

[Means for Solving Problems] A VTR according to the present invention is a composite envelope detection output signal of a video signal and a HIFI signal, a video signal and an H signal.
The present invention is characterized in that the output difference between the IFI signal and the combined peak hold output signal is compared with a predetermined threshold value to perform tracking adjustment.

[Operation] According to the present invention, the peak hold of the peak hold circuit for storing the maximum values of the envelopes of the video signal and the HIFI signal while adding the reproduction envelope detection output signals of the video signal and the HIFI signal at a predetermined ratio The values are added at the predetermined ratio, and it is detected whether or not the output difference between the addition envelope output signal and the addition peak hold output signal exceeds a predetermined threshold value, and the tracking phase is automatically adjusted.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an automatic tracking control system for a VTR according to an embodiment of the present invention. In FIG. 1, (1) to (29) have the same configuration as the conventional example shown in FIG. Therefore, the same reference numerals are given and the description thereof is omitted.

In FIG. 1, (104A) and (104B) are rotary HIFI heads provided on a rotary drum (6), and these are, as shown in FIG. 2, one rotary drum (6) and a rotary video head (4A). ),(Four
Installed with B). Reference numeral (122) is a HIFI head amplifier, which amplifies the deeply recorded HIFI signal.
(123) is a HIFI signal envelope detection circuit, (124) is a peak hold circuit that holds the maximum value of the HIFI signal envelope, (125) is a voltage divider that makes the envelope detection output signal of the video signal 1 / m, ( 126) is a voltage divider that sets the peak hold value of the peak hold circuit (24) that holds the maximum envelope value of the video signal to 1 / m, (1
27) is 1 / the envelope detection output signal of the HIFI signal.
A voltage divider (128) for setting the peak hold value of the peak hold circuit (124) for holding the envelope maximum value of the HIFI signal to 1 / n.

(129) is an adder for adding the divided output of the peak hold maximum value of each of the video signal and HIFI signal, and (130) is an adder for adding the divided output of the envelope detection output signal of each of the video signal and HIFI signal. is there.

Fig. 2 shows the mounting state of each head as seen from the top of the rotating drum (6). The rotating video head (4A),
(4B) and the rotary HIFI heads (104A) and (104B) are accurately attached to the rotary drum (6) at an indexing position of 180 °. Also, rotating video heads (4A), (4B) and rotating HIF
Fig. 4 shows the level difference on the drum side of I head (104A), (104B)
As shown in (a), it is fixed while maintaining a constant value, for example, 16μ.

FIG. 3 is a diagram showing the recording state in the thickness direction of the tape. The head gear width (g0) is about 0.9μ and the rotation is wide.
The IFI heads (104A) and (104B) record the audio signal deeply, and the rotary video heads (4A) and (4B) record the video signal on the surface layer, which has a narrow head gear width (g1) of about 0.3 μ. In addition, the video heads (4A), (4B) and the HIFI heads (104A), (104B) are the headgear widths (g) described above.
In addition to 0) and (g1), the azimuth angle and the frequency for FM recording are different.

Next, the operation of the above configuration will be described.

First, the video signal on the magnetic tape (1) is detected by the rotary video heads (4A), (4B), amplified by the video head amplifier (22) via the rotary transformer (21), and this FM video signal is enveloped. It is detected by the detection circuit (23). The output of this envelope detection circuit (23) is the rotating video head (4
It changes as shown in FIG. 8 depending on the relative positions of A) and (4B) and the video recording track on the magnetic tape (1). The FM video signal is also applied to the peak hold circuit (24), and the peak hold circuit (24) sequentially detects and holds the maximum value of the output envelope of the head amplifier (22).
Finally, the video head (4A), (4B) is the optimum value on the tape which is the maximum value of the envelope, for example, (x) in Fig. 4 (a).
Hold the value when the point or (y) point is reached.

Next, the HIFI signal on the magnetic tape (1) is rotated HIF.
I-Head (104A), (104B) detected, rotary transformer
Amplified by HIFI head amplifier (122) via (21),
This HIFI video signal is an envelope detection circuit (123)
Is detected by. The output of the envelope detection output circuit (123) also changes in a manner similar to that of FIG. 8 depending on the relative position to the HIFI recording track on the magnetic tape (1) as in the case of the above video signal. The HIFI signal is also applied to the peak hold circuit (124) and sequentially detects and holds the maximum value of the output envelope of the HIFI head amplifier (122) as in the case of the video signal. Eventually H
IFI heads (104A) and (104B) are HIFs on magnetic tape (1)
Holds the value of the state in which all I-tracks are traced.

At this time, when the VTR recorded is exactly the same as the recorded VTR, as shown in FIG. 4 (a), the maximum value of the envelope of the video signal and the maximum value of the envelope of the HIFI signal are
Since it is (t0) and coincides with each other, the maximum value of either the video signal or the HIFI signal may be obtained. However, as shown in FIG. 4 (b), when reproducing a magnetic tape recorded by another VTR, the maximum value of the video signal envelope (t1) and the maximum value of the HIFI signal envelope (t2) are different. V that realizes a tracking control system that automatically sets the optimum value (t3) between (t1) and (t2)
The actual response of TR is shown in FIGS. 5 (a) and 5 (b). That is, the optimum tracking position is pursued from both the video signal and the HIFI signal, and the tracking position with good image quality and sound quality is always set as shown in FIG. 5 (b).

In FIG. 1, the video envelope detection output (23) is divided by a voltage divider (125), while the HIFI envelope detection output (123) is divided by a voltage divider (127), and both are added (13).
0) is added to obtain a composite envelope signal. Also, the video signal peak hold output (24) is divided by the voltage divider (126), while the HIFI peak hold output (124) is divided by the voltage divider (12).
The voltage is divided by 8), and both are added by an adder (129) to obtain a combined peak hold signal.

Then, both the composite envelope output (130) and the composite peak hold output (129) are added to the comparator (125). Here, the voltage difference between the combined peak hold output voltage (Vp) that is the output of the adder (129) and the combined envelope detection output (Ve) that is the output of the adder (130) is a threshold value set appropriately. Determine whether it is smaller or larger than the voltage (e ₀ ),
When Vp-Ve <e ₀ , the output voltage becomes positive voltage (V1) and Vp-Ve <
When it is e ₀ , it becomes a negative voltage (V2).

Then, when the difference between the output voltage (Vp) of the adder (129) and the output voltage (Ve) of the adder (130) increases and exceeds the above threshold value (e ₀ ), the comparator (25) Tracking during playback is controlled by utilizing the fact that the output voltage changes from a positive voltage to a negative voltage.

Next, this operation will be described with reference to the waveform chart of FIG.

(A) in FIG. 6 is a rotating video head (4A), (4B) and rotating HI.
Video signal of FI head (104A), (104B) and magnetic tape (1)
The positional relationship with the recording track of (2) is shown in FIG.
(B), (C), (D), (E), (F) are synthetic envelope detection output circuits
The output waveform of (130), the output waveform of the comparator (25), the output waveform of the differentiating circuit (26), the output waveform of the flip-flop circuit (27), and the output waveform of the integrating circuit (28) are shown.

When the rotary heads (4A), (4B), (104A) and (104B) scan the position of the magnetic tape (1), the synthetic envelope detection output (B) is at the lowest level. The output (E) of the flip-flop circuit (27) is at the negative voltage level, and the output of the integrator circuit (28)
(F) is in the decreasing direction, and the phase adjustment circuit (20), the phase comparison circuit (17), and the CP motor drive control circuit (11) are controlled to
Decrease the number of rotations of the motor (9) to rotate the heads (4A), (4B), (10
4A) and (104B) are moved from the state of (1) to the position of (2), and
It will move to the state of (3).

When the position (3) is scanned, the broken line (the hold voltage of the combined peak hold circuit composed of the adder (129) (
Since the difference between the voltage shown in 1) and the output voltage of the composite envelope circuit composed of the adder (130) becomes the voltage level shown by the broken line (2) which is the inversion level of the comparator (25), the comparator ( The output of 25) is inverted to a positive voltage. However, at this time, since the output of the differentiating circuit (26) becomes a positive pulse, the flip-flop is not inverted.

Furthermore, when the rotary head (4A), (4B), (104A), (104B) scans the position (4) and the composite envelope detection output starts decreasing after reaching the maximum level and scans the position (5), Since the threshold voltage shown by the broken line (3) which is the inversion level of the comparator (25) when the voltage difference between the composite peak hold voltage and the composite envelope voltage increases, the output of the comparator (25) changes from positive to positive. Inverts to a negative voltage. Along with this, the differentiating circuit (26) generates a negative pulse, the flip-flop circuit (27) is triggered to invert to a positive voltage, and the output of the integrating circuit (28) is changed to increase the voltage.

The output signal of the integrator circuit (28) shown in FIG. 6 (F) is applied to the phase comparator circuit (17) via the phase adjusting circuit (20), and is directed in the direction of increasing the rotation speed of the CP motor (9). The envelope output begins to increase again.

After that, when the rotary heads (4A), (4B), (104A), and (104B) scan the position (7) through the position (6), the flip-flop circuit (27) again becomes a negative level. Will be reversed and the tape speed will be reduced again. As described above, the relative position of the rotary heads (4A), (4B), (104A), (104B) and the recording track of the magnetic tape (1) is such that the output voltage of the composite envelope is always the broken lines (1) and (3 ) Is controlled so that it fluctuates between voltage levels. Finally, as shown in FIG. 5 (b), control is performed so that the trace position is always brought to the combined peak value point of the envelope of the video signal and the envelope of the HIFI signal.

In the above embodiment, as shown in FIG. 4, a VTR using a video head having a width of 48 .mu. Narrower than the video track width defined by the VHS format is taken as an example, but the present invention is not limited to this.

Further, it is not limited to the VHS method. VTR equipped with two types of heads, one for video signals, one for HIFI signals, and one for different head widths, such as deep layer recording and surface layer recording
It can be widely used in any tracking control system.

[Effects of the Invention] As described above, according to the present invention, it is not necessary to perform the troublesome tracking adjustment at the time of reproduction by the manual volume, and the tracking adjustment can be automated. In order to scan the optimum tracking position, even if it is a deep recording type HIFIVTR, or if it is a VTR dedicated for playback that uses a wide head that emphasizes special playback functions such as still and slow, it exhibits excellent tracking performance. In addition, it is possible to achieve good effects if the image and sound can be reproduced well.

[Brief description of drawings]

FIG. 1 is a block diagram showing the construction of an automatic tracking control system for a VTR according to an embodiment of the present invention, and FIG. 2 is a diagram showing a head attachment state of a rotary drum of a VHS type HIFIVTR as seen from above, FIG. The figure shows the state of deep and surface recording, Fig. 4 (a) shows the details of the head and track running conditions during self-recording and reproduction, and the waveform chart of the envelope, and Fig. 4 (b) shows that of self-recording. Details and driving waveforms of the head and track, Fig. 5 (a), (b)
Is an actual envelope waveform diagram, FIG. 6 is an output waveform diagram of each part, FIG. 7 is a block diagram showing a configuration of a conventional VTR automatic tracking control system, and FIG. 8 shows a relationship between a tracking phase and an envelope voltage. It is a figure. (4A), (4B) ... Rotating video head, (6) …… Rotating drum,
(8) …… Drum motor, (9) …… CP motor, (17) …… Phase comparison circuit, (20) …… Phase adjustment circuit, (23) …… Envelope detection circuit, (24) …… Peak hold Circuit, (25) ……
Comparator, (26) …… differential circuit, (27) …… flip-flop circuit, (28) …… integrator circuit, (104A), (104B) …… rotating HIFI head, (123) …… HIFI envelope detection circuit, ( 124) ... Peak hold circuit, (129), (130) ...
… Adder. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An envelope detection circuit for detecting an envelope of a video signal reproduced by a rotating video head,
A peak hold circuit for holding the maximum value of the envelope of the reproduced video signal by the rotating video head, a high-eye envelope detection circuit for detecting the envelope of the reproduced high-fidelity signal by the rotating high-fidelity head, and a reproduction of the envelope of the high-fidelity signal reproduced by the rotating high-feet head. A peak hold circuit for holding the maximum value, an adder for adding the output signal of the envelope detection circuit and the output signal of the high-fibre envelope detection circuit, an adder for adding the output signals of both peak hold circuits, and A detection circuit for comparing the outputs of the two adders to detect whether or not the difference exceeds a predetermined threshold value, and the relative positions of the rotary video head and the rotary high-eye head and the magnetic tape are detected by the output of the detection circuit. Control the relationship and re Magnetic recording and reproducing apparatus characterized by being configured to perform tracking control when.