JPH0344371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus such as a video tape recorder using a rotating magnetic head, and in particular,
The present invention relates to a magnetic recording and reproducing apparatus that automatically performs tracking control by mechanically shifting a rotating magnetic head substantially in the direction of a rotation axis.

In a rotating head video tape recorder (hereinafter referred to as VTR), which is a type of magnetic recording and reproducing device that uses a rotating magnetic head, a magnetic tape (so-called video tape) is arranged diagonally around the rotating magnetic head in a spiral line. The so-called helical scan type, which is wound around and guided so as to form a section, is common.

An example of a rotary head device used in this type of VTR is shown in FIG. In FIG. 1, a rotary head device 1 consists of upper and lower drums 2 and 3, with the lower drum 3 being fixed to the chassis of a VTR, etc.
The upper drum 2 is moved by a motor 4 or the like, for example, by an arrow A.
rotationally driven in the direction. This rotating upper drum 2
(Also called rotating drum). One or more video heads 5 are attached to the. A magnetic tape (videotape) 6 is wound diagonally around the outer peripheral surfaces of the upper and lower drums 2 and 3, for example, along the tape guide step 7 of the fixed lower drum 3, and is guided and run in the direction of arrow B, for example. being driven.

Next, FIG. 2 shows an example of a video track pattern recorded and formed on the magnetic tape 6, in which the tape running direction is in the direction of arrow B, and the moving direction of the rotating video head 5 on the magnetic tape is in the direction of arrow A. , the video track is, for example, track T ₁ ,
T ₂ , T ₃ , T ₄ . . . are sequentially recorded at a constant pitch p while drawing a diagonal pattern from the bottom end of the tape to the upper left in the figure. Furthermore, control pulses (CTL pulses) Pct are recorded and formed corresponding to these tracks T.

By the way, in order to accurately trace (scan) the video head 5 with respect to the recording track T during reproduction, the head 5 is connected via an electro-mechanical conversion element such as a bimorph plate 8, as shown in FIG. By attaching it to the rotating upper drum 2 and supplying a drive signal to the electrodes attached to both sides of the bimorph plate 8 during playback, the video head 5 is moved in the track width direction, that is, in the rotational axis direction perpendicular to the rotational scanning direction ( Automatic tracking control is performed to shift the position in the direction of arrow C).

An example of this automatic tracking control will be explained with reference to FIG. 4.

In FIG. 4, the configuration of the control circuit system is roughly divided into three blocks: a dynamic tracking control circuit section 11, a jumping control circuit section 12, and a slope correction circuit section 13.

First, the dynamic tracking control circuit section 11 is for correcting poor linearity of the recorded video track T itself and minute head deviations caused by mechanical disturbance vibration of the head. The correction operation is performed while constantly detecting the position of the video head 5 relative to the video head 5 using the reproduced video signal RF from the video head 5. That is, by supplying the output from the oscillator 14 to the bimorph plate 8, the video head 5 is forcibly vibrated to perform a so-called wobbling operation, and the reproduced video signal RF from the video head at this time is , and is sent to an envelope detector 16 via an input terminal 15, and the obtained envelope waveform signal (level detection signal) is sent to a balanced modulator 17, for example. This balanced modulator 17 includes:
An excitation signal for wobbling operation is supplied from the oscillator 14, and this signal and the envelope waveform signal are balancedly modulated, so that
An error signal (track deviation detection signal) corresponding to the direction and amount of deviation of the video head with respect to the video track T is obtained. and,
This error signal is sent to the oscillator 14 by the adder 18.
The signal is added and synthesized with the signals from the dynamic tracking control circuit 11, and is sent to the adder 19 as an output signal of the dynamic tracking control circuit 11.

Next, the jumping control circuit unit 12 causes the contact start position on the magnetic tape 6 when the head 5 comes into contact with the magnetic tape 6 to start the tracing operation during reproduction to match the start position of the video track T. It is for controlling. Further, the tilt correction circuit section 13 is for making the tilt angle of the head locus coincide with the video track T. These controls are mainly used to control the recorded video track T when playing back at a tape speed different from the tape running speed at the time of recording, for example, during so-called slow motion playback, quick motion playback, or still playback. On the other hand, this control is performed to correct the fact that the trace locus of the head 5 deviates in a certain relationship.

For example, the broken line in Figure 2 shows 1/2
The head trajectory U during slow playback is shown, and the pitch of this head trajectory U in the tape running direction B is 1/2 of the pitch p of the video track T, which is 1
Since the head locus U moves in the opposite direction to the tape running direction by p/2 every time head tracing is performed, jumping correction of the head 5 is required once for every two tracings.

Furthermore, since the inclination angle of the head trajectory U differs from the inclination angle of the video track T, it is also necessary to correct the inclination angle to shift the head 5 in proportion to the trace length. For this reason, the jumping control circuit section 12 outputs a jumping control signal whose voltage level is switched every time τ for tracing one track, as shown in FIG. 5A.
As shown in FIG. 5B, the slope correction circuit section 13 outputs a sawtooth waveform slope correction signal that increases the head deviation amount in proportion to time within one trace time τ. Then, these jumping control signals, tilt correction signals, and the output signal from the dynamic tracking control circuit 11 are added by an adder 19, and the bimorph drive circuit 2
0 to the bimorph plate 8, the head 5 is shifted in the C direction (track width direction), and the head locus U is made to coincide with the center of the video track T.

Here, the information required for the above-mentioned jumping control and tilt correction is obtained from the tape running system shown in FIG. That is, in the running system of the magnetic tape 6, with the rotary head device 1 as the reference position,
A full erase head 21 for erasing the full width of the tape is disposed on the upstream side in the track running direction B, and an audio/CTL head device 24 in which an audio head 22 and a control head (CTL head) 23 are integrated is disposed on the downstream side. is,
Further downstream of the head device 24, a capstan 25 and a pinch roller 26 are arranged to drive the magnetic tape 6. In order to detect the rotational position of the rotary upper drum 2 of the rotary head device 1, particularly the position at which the video head 5 starts contacting with the tape,
Alternatively, a rotation detection pulse generator 28 is provided to detect head switching rotational positions when two or more video heads are used. In addition, in order to detect the tape running speed, for example, the rotational speed of the capstan 25 or the pinch roller 2
A kind of rotation detector 29 is provided which generates pulses with a frequency depending on the rotational speed of 6. Then, the rotation detection pulse generator 28 generates a switching pulse signal which becomes a head switching signal, for example.
Psw, a CTL pulse Pct from the CLT head 23, and a pulse signal PFG with a frequency proportional to the tape running speed from the rotation detector 29 are transmitted to the jumping control circuit section 12 and the tilt correction circuit section 1, respectively.
3.

By the way, the jumping control circuit section 12 among these controls the trace start position of the head with respect to the tip of the video track.
If the VTR is incompatible, the position of the track on the tape and the CTL pulse Pct may be misaligned, or an error may occur in the amount of jumping correction due to the effects of tape elongation or temperature characteristics. Since the jumping control system is an open loop, the above error is not corrected. Moreover, when the head starts tracing, it is a transition period when the dynamic tracking control begins to operate, so tracking correction is only performed by the jumping control.
For example, 1V period (1 vertical scanning period) in the reproduced signal
The disadvantage is that noise is always mixed in at the front end of the camera, making the reproduced image unsightly.

The present invention eliminates such conventional drawbacks and automatically corrects the above jumping correction using a simple circuit configuration when the above jumping correction at the start of head tracing has an error with respect to the actual tape track pattern. It is an object of the present invention to provide a magnetic recording/reproducing apparatus which can eliminate errors and perform the above-mentioned jumping correction in accordance with an actual track pattern.

That is, the feature of the magnetic recording/reproducing apparatus according to the present invention is that the magnetic head is attached to the rotating body of the rotating magnetic head via an electro-mechanical conversion element, and a control signal to the electro-mechanical conversion element is used to control the rotation of the rotary head apparatus. In a magnetic recording and reproducing apparatus configured to control the position of the magnetic head in the track width direction with respect to a recording track on a magnetic tape that is guided and guided while being wrapped around the magnetic tape, there is a magnetic recording and reproducing apparatus configured to control the position of the magnetic head in the track width direction with respect to a recording track on a magnetic tape that is guided and guided while being wrapped around the magnetic tape. a jumping control signal for correcting the deviation between the start end position of the recording track and the contact start position of the magnetic head according to the tape running speed; A signal obtained by adding the error signal obtained by detecting the head deviation and the jumping error signal obtained by sampling at a time after a short delay from the contact start time is supplied to the electro-mechanical conversion element. This is to perform jumping correction.

Hereinafter, preferred embodiments of the present invention will be described.
This will be explained with reference to the drawings.

FIG. 6 is a block circuit diagram showing the main parts of the magnetic recording/reproducing apparatus according to the present invention and for explaining the principle of operation.

In this FIG. 6, the dynamic tracking control circuit section 11 includes an oscillator 1, similar to the conventional example shown in FIG.
4, envelope detector 16, balanced modulator 17,
and an adder 18, and the balanced modulator 17 outputs the track deviation detection signal (referred to as error signal ER) according to the direction and amount of deviation of the head with respect to the track.
The tilt correction circuit section 13 also performs the same function as described above.

The jumping control circuit section 30 has a jumping control circuit 32 that performs the same function as the jumping control circuit section 12 shown in FIG. It is provided. First, the delay circuit 33 delays the head switching pulse P _SW by a predetermined time to form a sampling pulse signal SP, which is sent to the control terminal of the sample hold circuit 34 . The input terminal of this sample and hold circuit 34 is supplied with the error signal ER of the dynamic tracking control circuit section 11 . This error signal ER is sampled by the sampling pulse signal SP, held, and integrated by an integrating circuit 35 to become a jumping error signal JE. This signal JE is sent to the adder 36 and the jumping control circuit 32
This signal is added to the output signal from the jumping control circuit section 30 to become the final signal for the jumping correction, and is output from the jumping control circuit section 30.

The output signal from this jumping control circuit section 30 is sent to an adder 19, where it is added to the signal from the dynamic jumping control circuit section 11 and the signal from the slope correction circuit section 13, and is added to the bimorph drive circuit section. 20 and the like to the bimorph plate 8.

FIG. 7 is a circuit diagram showing a specific example of the jumping control circuit section 30, and parts corresponding to those in FIG. 6 are given the same reference numerals. This seventh
The operation of the circuit shown in the figure will be explained with reference to the time chart of FIG.

First, the switching pulse P _SW obtained for head switching by detecting the rotational position of the rotating drum described above is delayed by a predetermined short time Δτ in the delay circuit 33, and the switching pulse P SW as shown in FIG. It becomes P _SW D. This delayed pulse P _SW D is differentiated by a differentiating circuit 41 consisting of a capacitor and a resistor to become a sampling pulse signal SP, which is sent to a control terminal of a gate circuit 42 . The gate circuit 42 includes a capacitor 43 and an operational amplifier 44 as well as a sample hold circuit 34.
It consists of Next, the error signal (tracking deviation detection signal) ER is sent to the gate circuit 42, sampled by the sampling pulse signal SP, held by the capacitor 43, and sent to the integrating circuit 35 via the gate circuit 45. being sent. The connection point between this gate circuit 45 and the integration circuit 35 is grounded via another gate circuit 46, and these gate circuits 45, 46
One side contains the above switching pulse P _SW , and the other side contains a pulse obtained by inverting the above pulse P _SW using an inverter.
P _SW is supplied respectively. Therefore,
The hold voltage signal to the integrating circuit 35 is as shown in FIG.
Be like _VH . This hold voltage signal V _H is
The signal is integrated by the integrating circuit 35, and the jumping error signal JE shown in FIG. 8 is obtained. This jumping error signal JE is sent to the adder 36, added to the output signal from the jumping control circuit 32, and sent to the adder 36 described above.

By the way, various configurations are known as the jumping control circuit 32, but for example, as shown in FIG. 53.
That is, the up-down counter 51 receives a pulse signal FG with a frequency proportional to the tape speed.
Counting starts from the rising edge (or falling edge) of the CTL pulse Pct from the CTL head 23, and this counting operation is performed using the tape running direction discrimination signal F/F/2, which reverses the tape running direction between the forward direction and the reverse direction. Depending on R, either addition (up count) or subtraction (down count) is selected.
The count output from the up-down counter 51 is converted into an analog voltage signal by a DA converter 52, and sampled and held in a sample hold circuit 53 at the head switching timing by the switching pulse _PSW . Therefore, a jumping control signal can be obtained that provides a predetermined amount of jumping depending on the tape running speed.

Here, in the upper part of FIG. 8, a part of the pattern on the magnetic tape (track tip, near the head contact start position) is schematically shown, and the solid line indicates the center line of the video track T. The broken lines each indicate the center line of the video head trajectory when no correction is performed during 1/2 slow playback. Since the above-mentioned jumping control circuit 32 performs the above-mentioned 1/2 pitch jumping control for each one of the two traces, if this is applied on the magnetic tape, the positions of the above-mentioned solid line and virtual line can be adjusted. This means that we are performing an operation that sequentially traces the following. If the head trajectory is arranged as shown by the broken line due to tape distortion or other causes with respect to the track positions of these solid lines and virtual lines, the error between these lines is added as an offset to the jumping control amount. , a delay circuit 33, a sample hold circuit 34, and an integration circuit 35, which are the characteristics of the present invention, are used. In other words, due to the above-mentioned dynamic tracking control operation, a substantial deviation between the track and the head is detected as the error signal, but immediately after the head starts contacting, it is in a transient unstable state, so the head The error signal ER is sampled and held at a timing delayed by the delay circuit 33 by a predetermined short time, ie, a short time Δτ longer than the time required for the dynamic tracking operation to stabilize, from the contact start point. Then, this sampled voltage _VH is integrated to form a jumping error signal JE, which is added to the jumping control signal to correct the error. Note that if this correction is excessive, the error signal ER appears on the negative side, and it goes without saying that the optimum correction is automatically performed.

As is clear from the above explanation, according to the present invention, due to the effects of tape distortion, VTR compatibility, etc.
Even if an error occurs in the jumping control itself, closed-loop control is performed in which correction is performed based on an error signal from the dynamic tracking control circuit that detects the amount of head deviation relative to the track. The functions of the camera can be improved and good reproduced images can be obtained. Moreover, by using the signals from the dynamic tracking control circuit, the circuit configuration becomes extremely simple.
Functionality can be improved at low cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a rotary head device;
Figure 2 shows the recorded video track and CTL
A front view of a magnetic tape showing pulses, FIG. 3 is a partially cutaway perspective view showing an example of how a video head is mounted, FIG. 4 is a block diagram showing an example of the configuration of a tracking control system, and FIG. 5 shows jumping control and tilting. This is a time chart for explaining each correction operation. 6 to 8 show essential parts of an embodiment of the present invention, FIG. 6 is a block circuit diagram showing the basic configuration, FIG. 7 is a circuit diagram showing a specific example of the jumping control circuit section, and FIG. The figure is a time chart for explaining the operation. 1... Rotating head device, 2... Rotating upper drum, 5...
Video head, 6... Magnetic tape, 11... Dynamic tracking control circuit section, 13... Slope correction circuit section, 3
0... Jumping control circuit section, 32... Jumping control circuit, 33... Delay circuit, 34... Sample hold circuit, 35... Integrating circuit.

Claims (1)

[Claims] 1 The magnetic head is attached to the rotating body of the rotating magnetic head device via an electrical-mechanical conversion element, and the electrical
A magnetic device configured to control the position of the magnetic head in the track width direction with respect to a recording track on a magnetic tape that is guided and guided while being wound around the rotary head device by a control signal to a mechanical transducer. In the recording/reproducing apparatus, a jumping control signal is provided for correcting the deviation between the starting end position of the recording track and the contact start position of the magnetic head according to the tape running speed during reproduction, and a jumping control signal is provided based on the reproduction signal from the magnetic head. A signal obtained by adding an error signal obtained by detecting the deviation of the magnetic head with respect to the recording track and a jumping error signal obtained by sampling at a time after a short delay from the contact start time is added to the electric field. A magnetic recording/reproducing device characterized by performing jumping correction by supplying a signal to a mechanical transducer.