JPH03259680A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the picture quality by moving a video head in response to a curve of a track pattern so as to allow the head to trace the track accurately. CONSTITUTION:A reference sawtooth wave generating circuit 7 generates a reference sawtooth wave with a period based on a detection pulse and an in- track pattern control circuit 12 moves a video head perpendicularly to a track pattern at a prescribed point based on a prescribed reference sawtooth wave in a track. Thus, an envelope of a reproduction output at a point when the video head 10 is moved. The in-track pattern control circuit 12 moves the video head 10 in a direction increasing the envelope and moves the video head 10 further by a minimum step. Then an optimum trace pattern maximizing the envelope of the reproduction output from the video head 10 is obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a magnetic recording/reproducing device, and in particular, it relates to a magnetic recording/reproducing device, and particularly to a magnetic tape with poor track pattern linearity.
The present invention relates to a magnetic recording/reproducing device that enables reliable head tracing.

(Prior Art) Conventionally, when a home video tape recorder (hereinafter referred to as a VTR) plays back a magnetic tape recorded on another VTR, it is necessary to adjust tracking defects caused by mechanical errors. There is a need. The reproduction control pulse from the control head and a predetermined reference signal are phase-compared by a phase comparator, and the rotation of the capstan motor is controlled based on the output of the phase comparator. The reference signal is delayed by the monostable multivibrator and then given to the phase comparator, and the user can adjust the time constant of the monostable multivibrator to
Tracking adjustments are being made. Furthermore, recently, VTRs that employ software servo and have a gain tracking adjustment function in which tracking operations are processed by digital calculations have become popular. These tracking adjustments allow the video head to accurately trace the magnetic tape tracks.

However, track pattern linearity may deteriorate due to variations in mechanical accuracy and adjustment errors in the tape running system. In this case, even if the tracking adjustment described above is performed, the video head cannot reliably trace the recording track because the trace pattern is linear. One possible solution to this problem is to increase the head width of the video head, but recently there has been a demand for reducing the head width of the video head in order to improve image quality. There was a problem in that tracing was not performed reliably and noise was generated.

(Problems to be Solved by the Invention) As described above, in the conventional magnetic recording and reproducing device described above, when the linearity of the track pattern deteriorates, noise is generated due to the reduction in the head width. was there.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a magnetic recording and reproducing device that can improve image quality when reproducing a magnetic tape whose track pattern has deteriorated linearity by performing head tracing according to the track pattern.

[Structure of the Invention] (Means for Solving the Problems) A magnetic recording and reproducing device according to the present invention includes a video head attached thereto, and a piezoelectric device that displaces the video head in a direction perpendicular to a track pattern based on a drive signal. an envelope detection circuit that detects the envelope of the playback output of the video head, a reference sawtooth wave generation circuit that generates a sawtooth wave corresponding to the playback mode, and an envelope detection circuit that detects the envelope of the playback output of the video head; By displacing the head by a predetermined amount and storing the envelope detection output at each point, the amount of displacement for obtaining the maximum envelope value at each point is determined, and the amount of displacement is made to correspond to the track pattern based on this amount of displacement. an in-track pattern control circuit that outputs a pattern output for displacing the video head; and an in-track pattern control circuit that creates the drive signal based on the output of the in-track pattern control circuit and the output of the reference sawtooth wave generation circuit, and applies the drive signal to the piezoelectric element. A piezoelectric element drive circuit is provided.

(Function) In the present invention, the in-track pattern control circuit outputs a pattern output to the piezoelectric element drive circuit, and moves the video head by a predetermined amount in the vertical direction (width direction) at a predetermined point.
Displace it to. The intra-track pattern control circuit compares the envelope detection output level before and after the displacement of the video head for each point. The control circuit within the track pattern is
From this comparison result, the amount of displacement that maximizes the envelope detection output is determined, and the final pattern output is applied to the piezoelectric element drive circuit to obtain an optimal trace pattern.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 is an explanatory diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention.

The rotation of the capstan motor 1 is transmitted to the capstan 2, and the rotation of the capstan 2 causes the magnetic tape 4 to run between it and the pinch roller 3.

The rotation of the capstan motor 1 is detected by a rotation detection circuit 5. The rotation detection circuit 5 also detects the rotation of the rotation cylinder 6 and outputs a detection pulse to the reference sawtooth wave generation circuit 7. The reference sawtooth wave generating circuit 7 generates a reference sawtooth wave having a period based on the detection pulse and outputs it to the mix amplifier 8. That is, the rotation detection circuit 5 counts how many rotation pulses (FG pulses) are generated from the capstan 2 during the rotation period of the rotation cylinder 60, and
Determine the playback tape speed (playback mode). The reference sawtooth wave generating circuit 7 generates a sawtooth wave signal according to the playback mode, and does not generate a sawtooth wave during normal playback at the same tape speed as during recording. When the tape speed is twice that during recording, a sawtooth wave is generated that sequentially displaces the tape from the start of the trace and displaces it by one track pitch at the end of the trace. In the case of n-times speed playback, a sawtooth wave is generated that displaces the track pitch (n-1> track pitch. In addition, in the case of slow playback, at 1/n tape speed, the sawtooth wave is generated in the opposite direction to that at n-times speed.
1) The displacement is equal to the track pitch.

A piezoelectric element 9 with one end fixed is attached to the rotating cylinder 6, and a video head 10 is attached to the other end of the piezoelectric element 9.
is installed. The state of the piezoelectric element 9 changes based on the drive signal, thereby making it possible to displace the video head 10 perpendicularly to the track pattern. The playback output from the video head 10 is given to an envelope detection circuit 11. The envelope detection circuit 11 performs envelope detection on the reproduction output of the video head 10 and outputs the result to the intra-track pattern control circuit 12 .

The intra-track pattern control circuit 12 is configured to output a pattern output for displacing the video head 10. The in-track pattern control circuit 12 has a storage device (not shown) to store the envelope value from the envelope detection circuit 11, and compares the envelope values before and after the displacement of the video head 10 at the same point in the track. Accordingly, the optimum trace position at this point is determined and the pattern output is changed. The intra-track pattern control circuit 12 performs this process for all points within the track to determine the optimum trace pattern, and outputs the final pattern output to the mix amplifier 8.

The mix amplifier 8 adds and amplifies the reference sawtooth wave and the pattern output, and outputs the result to the piezoelectric element drive circuit 13. The piezoelectric element drive circuit 13 outputs a drive signal based on the output of the mix amplifier 8. As described above, this drive signal changes the state of the piezoelectric element 9, causing the video head 10 provided at the tip to be displaced.

Next, the operation of the magnetic recording/reproducing apparatus configured as described above will be explained with reference to FIGS. 2 and 3. FIG. 2 is an operation flowchart of the intra-track pattern control circuit 12, and FIG. 3 is an explanatory diagram showing the trace pattern of the video head 10.

Assume now that the linearity of the track pattern has deteriorated as shown in FIG. When playback starts, as shown in FIG. 3(a), the video head 10
trace in a linear pattern. First, in step S1 of FIG. 2, the in-track pattern control circuit 12 outputs a pattern output for displacing the video head 10 by the minimum step to the mix amplifier 8. The reference sawtooth wave generation circuit 7 is given a detection pulse corresponding to the rotation of the capstan motor 1 and the rotation cylinder 6 from the rotation detection circuit 5, and generates a reference sawtooth wave having a period based on this detection pulse. , in-track pattern control circuit 12
displaces the video head at a predetermined point within the track based on a predetermined reference sawtooth. Electronic element drive circuit 13
applies a drive signal to the piezoelectric element 9 to displace the video head 1o by a minimum step perpendicular to the track pattern as shown in FIG. 3(b).

As a result, the envelope of the playback output at the point where the video head 1o is displaced changes.

The envelope detection circuit 11 performs envelope detection on the reproduced output and supplies it to the intra-track pattern control circuit 12 . The intra-track pattern control circuit 12 determines whether the envelope of the displacement point has become larger in the next step S2. If the envelope value has become larger, the envelope value is stored in the next step S3.

The in-track pattern control circuit 12 performs steps s2 to S.
In loop 4, compare the envelope sizes of all points.

Once the envelopes of all points have been compared, in the next step S5, the displacement direction is reversed and a similar comparison is performed. In other words, the intra-track pattern control circuit 12 outputs a predetermined pattern output to control the video head 10 to the third position.
6. Then, step S2,
Processing similar to S3 is performed to compare envelopes for each point and store envelope values. When the same processing is completed at all points, the in-track pattern control circuit 12 displaces the video head 10 in the direction in which the envelope becomes larger, and further displaces the video head 10 by the minimum step (see FIG. 3(C)). ).

Similar to the previous time, the envelopes of the displacement points are compared in step S2, and if the envelope becomes larger, the step number (2 in this case) and envelope value are stored for each point in step S3. When the comparison at all points is completed in step S4, the displacement direction is reversed in the next step S5. In this case as well, the envelopes are compared in the same way as last time. When it is determined by this comparison that the envelope value at a predetermined point has converged, the amount of displacement (number of steps) at this point is determined. For example, at the point where the video head 10 starts to be displaced, it is determined that a large envelope value will be obtained if the video head 10 is displaced by the minimum step, as shown in FIG. 3(C).

As shown in FIGS. 3(d) and 3(e), similar operations are repeated to displace the video head 10 one step at a time, and the envelopes at each point are compared. Step S6
When the envelope values of all points converge at , the video head 10 obtains the maximum envelope for each point.
The amount of displacement (number of steps) is determined, and the final pattern output is output to the piezoelectric element drive circuit 13. In this way, as shown in FIG. 3(d), an optimal trace pattern is obtained in which the envelope of the playback output from the video radar 10 is maximized.

In this way, in this embodiment, the video head 10 is vertically displaced one step at a time at each point of the track pattern, and the step amount for obtaining the maximum envelope value at each point is determined by comparing it with the previous envelope value. and have obtained the final trace pattern. Even when reproducing a magnetic tape with poor track pattern linearity, the video head 10 reliably traces the recording track, so no noise is generated even if the head width is reduced.

[Effects of the Invention] As explained above, according to the present invention, since the video head is displaced according to the track pattern, the track can be accurately traced, and the image quality can be improved. has.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the magnetic recording/reproducing device according to the present invention, FIG. 2 is an operation flowchart of the in-track pattern control circuit 12, and FIG. 3 is an explanatory diagram showing a trace pattern in the embodiment. . 5... Rotation detection circuit, 7... Reference sawtooth wave generation circuit, 8... Mix amplifier, 9... Piezoelectric element, 10...
...Video head, 11...Envelope detection circuit,
12... In-track pattern control circuit, 13... Piezoelectric element drive circuit. 2nd figure 1! End panu change width Figure 3

Claims (1)

[Claims] A piezoelectric element to which a video head is attached, which displaces the video head in a direction perpendicular to a track pattern based on a drive signal, and an envelope detection circuit which detects an envelope of a playback output of the video head. , a reference sawtooth wave generation circuit that generates a sawtooth wave corresponding to a playback mode, and a circuit that displaces the video head by a predetermined amount for each point set in the track pattern, and stores the envelope detection output at each point. an in-track pattern control circuit that calculates a displacement amount to obtain a maximum envelope value at each point, and outputs a pattern output for displacing the video head in accordance with the track pattern based on the displacement amount; , a piezoelectric element drive circuit that creates the drive signal based on the output of the in-track pattern control circuit and the output of the reference sawtooth wave generation circuit and supplies it to the piezoelectric element. Device.