JPH0344372B2 - - 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
One or more video heads 5 are attached to the video head (also referred to as a rotating drum). 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 head 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 upward to the left in the figure. In addition, in response to these tracks T, control pulses (CTL
Pulse) Pct is recorded and formed.

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, there is control performed to correct the deviation of the trace locus of the head 5 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. Also,
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. Therefore, the jumping control circuit section 12
As shown in FIG. 5A, a jumping control signal is outputted from which the voltage level is switched every time τ for tracing one track, and the slope correction circuit 13 outputs a jumping control signal as shown in FIG. 5B. In addition, a sawtooth waveform slope correction signal is output that increases the head deviation amount in proportion to time within one trace time τ. 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 sent to the bimorph board 8 via the bimorph drive circuit 20 to drive the head. 5 in the direction of arrow C (track width direction) to align the head locus U 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 a reference position, a full erase head 21 for erasing the full width of the tape is located upstream in the tape running direction B, and an audio head 22 and a control head (CTL) are located downstream.
audio head) 23/
CTL head devices 24 are arranged, and further downstream of the head devices 24, a capstan 25 and a pinch roller 26 are arranged to run the magnetic tape 6. Rotating head device 1
The rotation detection pulse is used to detect the rotational position of the rotating upper drum 2, especially the position at which the video head 5 starts contacting with the tape, or to detect the rotational position for switching heads when two or more video heads are used. A generator 28 is provided. In addition, in order to detect the tape running speed, for example, the rotational speed of the capstan 25 or the pinch roller 26 is detected.
A kind of rotation detector 29 is provided which generates pulses with a frequency depending on the rotational speed of the motor. and,
For example, a switching pulse signal _PSW , which is a head switching signal, from the rotation detection pulse generator 28,
The CTL pulse Pct from the CTL head 23 and the pulse signal _PFG having a frequency proportional to the tape running speed from the rotation detector 29 are supplied to the jumping control circuit section 12 and the tilt correction circuit section 13, respectively.

Incidentally, the tilt correction circuit section 13 is configured as shown in FIG. 6, for example. First, the pulse signal _PFG , which has a frequency proportional to the rotational speed of the capstan 25 for driving the tape running, and therefore proportional to the tape running speed, is made to have a constant pulse width by a monomulti (vibrator) circuit 32, A type of frequency-voltage conversion process is performed by integrating the signal in the integrating circuit 33. The voltage output from the integrating circuit 33 is supplied to one terminal of a changeover switch 34 and to the other terminal r of the changeover switch 34 via an inverter 35. This changeover switch 34 is controlled by a tape direction changeover signal F/R indicating whether the tape running direction is forward or reverse, and is connected to the terminal side when it is in the forward direction, for example. The output signal from the changeover switch 34 is passed through the voltage shift circuit 38 to the integration circuit 3 for forming the sawtooth wave described above.
I am sending it to 6th. FIG. 6 shows an example in which two integrating circuits 36a and 36b are provided corresponding to a rotary head device using two video heads. The integration circuits 36a and 36b are reset to zero in response to switching pulses _PSW for these two video heads. In this case, the pulse P _SW is sent as is to one integrating circuit 36a, and the pulse _SW obtained by inverting the pulse P _SW by the inverter 37 is sent to the other integrating circuit 36b. These integrating circuits 36a,
36b respectively output tilt angle correction signals as shown in FIG. 5B, for example. This figure 5B
Here, the signals from the two integrating circuits 36a and 36b are displayed together.

In the conventional slope correction circuit section 13 as described above, since an analog circuit is used in the main part of the circuit configuration, it is troublesome to adjust the time constants of the integrating circuits 33, 36a, 36b, etc. It is difficult to convert it into a circuit (IC) or LSI.

The present invention has been made in view of these conventional circumstances, and it forms the above-mentioned slope correction signal through digital arithmetic processing, simplifies or eliminates circuit adjustment, and facilitates integration into ICs, especially LSIs. The object of the present invention is to provide a magnetic recording/reproducing device equipped with a tracking control circuit system.

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/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 head, means for outputting a first pulse signal at a frequency; an oscillator for outputting a second pulse signal at a frequency corresponding to a standard tape speed; and a processing circuit section that outputs a signal for correcting the inclination angle of the scanning locus of the magnetic head relative to the magnetic head, and converts the output signal from the processing circuit section into, for example, an analog voltage signal to
The purpose is to perform tilt correction by supplying the signal to a mechanical transducer.

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

FIG. 7 shows the basic configuration of a slope correction circuit section 40 as a main part of an embodiment of the present invention, which is used in the slope correction circuit section 13 of FIG. 4 above, and other parts are configured in the same manner as in FIG. do it.

In FIG. 7, the pulse signal P _FG has a frequency corresponding to the tape speed by detecting the rotation of the capstan, etc., as described above, and is sent to the first counter circuit 41 as a count input signal. Supplied. In addition, a switching pulse that has timing information at the time when the head starts contacting the tape is generated by detecting the rotational position of the rotating drum.
P _SW is supplied to the first counter circuit 41 and the second counter circuit 42 as a reset signal (zero clear signal), respectively. Next, the oscillator 43 generates a pulse signal with a frequency equal to the above P _FG at standard tape speed, so-called normal speed.
It generates P _N and is supplied to the second counter circuit 42 as a count input signal.
Furthermore, these first and second counter circuits 4
The count output from 1 and 42 is sent to the addition/subtraction circuit 44.
Either addition or subtraction operation is selected in accordance with a tape direction determination signal F/R which is supplied to the tape direction determination signal F/R and is inverted depending on whether the tape running direction is forward or reverse. The digital output signal from the addition/subtraction circuit 44 is then converted to a digital-to-analog converter (D
- A converter) 45 converts it into an analog voltage signal, thereby obtaining the above-mentioned slope correction signal.

Here, in the time chart of Fig. 8, the pulse signal P _FG of the frequency corresponding to the tape speed is
A first count data signal CFG is obtained by counting with the counter circuit 41, and a second count data signal _CFG is obtained by counting the pulse signal _PN with a frequency corresponding to the standard speed with a second counter circuit 42.
C _N is obtained. These count data signals
For example, by subtracting C _FG and C _N in the addition/subtraction circuit 44, a digital signal D _SL for tilt correction is obtained.
is obtained. Therefore, in the case of normal playback that does not require tilt correction, the subtracted digital signal _DSL is always 0, and the tilt angle correction described above is not performed. It goes without saying that the above-mentioned counting operation is cleared to zero (reset) by the switching pulse signal _PSW .

Next, FIG. 9 shows an example of a circuit that embodies such a basic configuration. In FIG. 9, the oscillation output from a high frequency oscillator 43 is divided by a frequency divider 46, and a pulse signal P _N of a frequency corresponding to the normal speed (for example, 900 Hz) is counted by a second counter circuit 42. For example, 4-bit count data of Q0 to Q3 is output. The first counter circuit 41 outputs, for example, 6-bit count data Q0 to Q5, and each of these bits is input to an exclusive OR circuit (exclusive OR circuit) E0R0 to E0R.
5 to terminals B0 to B5 of a circuit 47 for adding and subtracting with jumping data. A signal obtained by inverting the tape direction determination signal F/R by an inverter 49 is supplied to these E0R0 to E0R5, respectively, and this signal is also supplied to the addition/subtraction switching terminal C of the addition/subtraction circuit 47. For example, 5-bit jumping control data signals J0-J4 from the aforementioned jumping control circuit section 12 are supplied to input terminals A0-A4 of the addition/subtraction circuit 47, respectively. here,
The addition/subtraction circuit 44 shown in FIG. 7 is shown divided into an addition/subtraction circuit 47 and a subtraction circuit 48 in FIG. 9. Then, the output terminals S0 to S of the addition/subtraction circuit 47
6-bit data from output terminals Q0-Q3 of the second counter circuit 42 is supplied to input terminals B0-B3 of the subtraction circuit 48. Then, the difference between them is sent to the DA converter 45.

Various other specific circuit configurations are possible.

As is clear from the above description, according to the present invention, since the slope correction circuit section is configured with a digital circuit, it can be relatively easily implemented as an LSI, and when applied to an automatic tracking control circuit system, it can be used in common. The above-mentioned P _FG , P _SW , etc. can be used as signals for the circuit, the overall configuration is simplified, no adjustment can be easily achieved, and the influence of temperature characteristics is extremely small compared to analog circuits.

[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. Time chart for explaining each correction operation, No. 6
The figure is a block circuit diagram showing an example of the slope correction circuit section. 7 to 9 show embodiments of the present invention, and FIG. 7 is a block circuit diagram showing the basic configuration;
Figure 8 is a time chart for explaining the operation.
FIG. 9 is a block circuit diagram showing a more specific example of the circuit configuration. 1... Rotating head device, 2... Rotating upper drum, 5...
Video head, 6... Magnetic tape, 40... Slope correction circuit, 41... First counter circuit, 42... Second counter circuit, 43... Oscillator, 44... Addition/subtraction circuit, 45... DA converter.

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 recording device configured to control the position of a magnetic head in a 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 playback device, means for outputting a first pulse signal with a frequency corresponding to the actual tape running speed, an oscillator for outputting a second pulse signal with a frequency corresponding to the standard tape speed, and a means for outputting a first pulse signal with a frequency corresponding to the standard tape speed; a processing circuit unit that performs counting and arithmetic processing on the second pulse signal and outputs a signal for correcting the inclination angle of the scanning locus of the magnetic head with respect to the recording track, and outputs the output signal from the processing circuit unit to A magnetic recording/reproducing device characterized by supplying a signal to a conversion element.