JPS59207049A - Motor driving device of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To make a movable member and its control circuit unnecessary by changing the driving voltage or the driving time of a motor, which drives a tape, in accordance with the output of a tape speed control signal or a video output signal from one head, at least, at a tape stop time. CONSTITUTION:A control signal out of output signals from a head 2 is taken out by a band-pass filter 6 after passing through a preamplifier 4. This control signal passes an amplifier 7 and is inputted to sample holding circuits 8. The output for trace start of the head 2 and the output just before trace end are held in two sample holding circuits 8 respectively. Outputs of sample holding circuits 8 are inputted to averaging circuits 9 for the purpose of reducing the influence of noise due to drop-out or the like. Outputs of averaging circuits 9 are inputted to a differential amplifier 10. The output of this differential amplifier 10 is inputted to a motor drive amplifier 11 to drive a motor 12 for driving the tape.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a plurality of rotating heads. The present invention relates to a tape drive device for a magnetic recording/reproducing device, and particularly relates to a tape drive device for intermittently running a still image or a tape for slow motion reproduction.

[Background of the invention]

Conventionally, magnetic recording and reproducing devices record video signals and signals for tape speed control during playback on tracks that are inclined with respect to the longitudinal direction of the tape by sequentially using multiple rotating heads with different azimuth angles. A method to do this is known. This tape speed control method will be explained using the track trace pattern of the head during reproduction shown in FIG. 1 is a tape, 2 is a rotary head, and 3 is a track recorded on the tape 1. In each track 3, control signals are recorded in addition to video signals. By recording this control signal with a different frequency and phase for each track, it is possible to separate it from the signals of adjacent tracks. FIG. 1 shows a four-frequency system in which signals are recorded by changing the frequency for each trunk 3. Now, considering that the rotary head 2 is tracing the track 3 in which the control signal of the frequency f3 is recorded, the output signals of the rotary head 2 include the video signal, the control signal of the frequency f3, and the frequencies fs, fa. The control signal from the adjacent track where the control signal of is recorded is obtained. When the rotary head 2 traces the center of the track 3, the output level of the control signal from the adjacent track is the same, but when the rotating head 2 traces off the center of the track 3, the output level of the control signal from the adjacent track is equal. The output level will differ.

By detecting the difference in the output levels of the control signals from adjacent tracks and changing the running speed of the tape 1 in accordance with this difference, the rotary head 2 always traces the center of the track 3.

Next, a conventional variable speed reproduction method using this system will be described. Normally, when playing still images or slow motion from a magnetic tape recorded using the azimuth recording method, only the tape running speed is different from that during recording, so the rotating head 2 is moved at an inclination that is different from that of the track 3. This will be traced on tape 1. Therefore, the rotary head 2 traces not only the track 3 recorded at the same azimuth angle, but also the track 3 recorded at a different azimuth angle. is not regenerated due to the azimuth effect. Therefore, tracks 3. of the same azimuth angle. The rate at which all the rotary heads 2 trace is different, and as the rate decreases, the level of the reproduced signal also decreases, making it easier for noise to occur in the reproduced screen.

Conventionally, the head base on which the rotary head 2 is mounted is constructed of a movable member, and the head itself is actuated in accordance with the control signal output from the adjacent trunk.
Even if the speed of the track 3 is different from that during recording, the head 2 always traces the center of the track 3 to achieve variable speed playback.

However, this method has disadvantages in that the head base must be constructed of movable members, and that its control circuit requires a large space, making it expensive and disadvantageous in reducing size and weight.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, and aims to provide a tape drive device for a magnetic recording/reproducing device that can be made inexpensive, small, and lightweight by eliminating the need for movable members and their control circuits. .

[Summary of the invention]

In order to achieve the above object, the present invention provides a magnetic recording/reproducing device capable of performing variable speed playback by intermittently running a tape, in which the tape speed from at least one head when the tape is stopped is The apparatus is equipped with means for completely changing the driving voltage or driving time of the motor that drives the tape in accordance with the output of the control signal or the video output signal.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of the tape drive device of the present invention.
In the figure, the same reference numerals as in FIG. 1 indicate the same parts. The output signal from the head 2 includes a video signal and a control signal. Of these signals, the video signal is input to the video playback circuit 5 through the preamplifier 4, and the control signal is input to the video reproduction circuit 5 through the preamplifier 4. After passing through, it is extracted by a bandpass filter 6. This control signal is input to the sample hold circuit 8 after passing through the amplifier 7'f. The two sample and hold circuits 8 hold the output of the head 2 at the start of tracing and the output immediately before the end of tracing, respectively. A 30H2 signal is used as the sampling pulse at this time. Normally, when the tape is stopped, head 2 is connected to trunk 3.
Although the above will be traced several times, the output of the sample and hold circuit 8 is input to the averaging circuit 9 in order to reduce the influence of noise such as dropout. For example, an integrator or the like may be used as the averaging circuit 9. The output of this averaging circuit 9 is input to a differential amplifier 10.

The output of this differential amplifier 10 is the motor drive amplifier 11
and drives the tape drive motor 12. Furthermore, the motor drive amplifier 11 is equipped with a monomulti 13.
The monomulti 13 is set and output when it receives a tape running start signal.

Next, the operation of an example of the apparatus of the present invention described above will be explained.
- Generally, when variable speed playback is performed using only two heads 2, two different tracks are played alternately when the tape is stopped, which tends to cause the playback screen to shake, but with double azimuth heads, the tape Since only one track is played when stopped, the playback screen does not shake.

On the other hand, when the tape is run from a stopped state, voltage is applied to the motor 12 that drives the tape.
The magnitude and application time of this applied voltage are usually fixed so that the tape feed amount is exactly one frame. If the tape feed amount changes and the tape stop position changes, the relative positional relationship between the head 2 and the track will change.
There are parts where the head output signal drops significantly, but if the head output signal falls below a certain level, noise will occur on the screen, so it is necessary to increase the accuracy of stopping the tape during intermittent running as much as possible. However, in a transitional state from normal playback to variable speed playback with intermittent tape feeding, the tape stop position is not necessarily optimal. In this state, if a constant applied voltage and applied time are applied to the motor 12 and the tape runs intermittently, noise will always occur on the screen and the screen will be difficult to see repeatedly. For this reason, the present invention determines the optimum feed amount, applied voltage, and application time from the head output signal when the tape is stopped. That is, when the head 2 is tracing a track in which a control signal with a frequency of 13 as shown in FIG. ) and the level just before the end of the trace (1=1+), they are the same when there is no track shift, but different when there is trunk shift. Let the level of the head output signal at the start of the track be vto, and the level just before the end of the trace be Vguchi, and the difference between these levels E (=vto V
The track deviation A with respect to t+) is expressed as shown in FIG.

This relational characteristic is set in the differential amplifier IO.

Based on this level difference E, motor 1 during the next intermittent running
Two applied voltages are set. Since the motor 12 is driven according to this set value, a stable tape stop position can always be obtained.

Note that in the above example, the voltage application time to the motor 12 is kept constant and the magnitude of the applied voltage is changed according to the track deviation. When changing the difference amplifier 1
The configuration may be such that the output time width of the monomulti is changed depending on the output of the monomulti. Furthermore, when detecting a track deviation from a video signal, a low pass filter may be installed instead of the bandpass filter 6, and a detection circuit for detecting the envelope of the video signal may be installed instead of the amplifier 7.

〔Effect of the invention〕

As described above, according to the present invention, variable speed reproduction is possible with a simple circuit configuration, so that the cost and weight of the magnetic recording and reproducing apparatus can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining a track trace pattern of a head in a magnetic recording/reproducing device, FIG. 2 is a configuration diagram showing an embodiment of the device of the present invention, and FIG. 3 is a diagram of a differential amplifier used in the device of the present invention. In the characteristic diagram, 1... tape, 2... head, 3... track, 4... preamplifier, 6...
・Band pass filter, 7...Amplifier,...Sample hold circuit, 9...Averaging circuit, 10...Differential amplifier, 11...Motor drive amplifier, 12...
Motor, 13...Mono multi. Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] In a magnetic recording and reproducing device capable of performing variable speed playback by intermittently running a tape, the output of a tape speed control signal or a video output signal from a head in at least one direction when the tape is stopped. A motor drive device for a magnetic recording/reproducing device that is equipped with a means for changing the drive voltage or drive time of a motor that drives a tape according to the motor.