JPS6196555A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To always obtain a constant intermittent running quantity irrespective of an ambient temperature by attenuating a crest value of a damping pulse in accordance with elapsed time after a driving pulse has been supplied. CONSTITUTION:A magnetic recording and reproducing device 21 is provided with a controlling circuit 22 for supplying a pulse to a capstan motor driving circuit 2b. This circuit 22 consists of a charging and discharging circuit 22a, and an attenuating circuit 22b for attenuating a crest value of a damping pulse in accordance with an output voltage of this circuit 22a. A capacitor C of the circuit 22a starts to charge, when a driving pulse is applied, and starts to discharge through a resistance R in a trailing edge part of the driving pulse. Therefore, the crest value of the damping pulse supplied to the circuit 2b is attenuated by following up a terminal voltage of the capacitor C. In this way, the circuit 22 attenuates the crest value of the damping pulse by a prescribed attenuation factor as the time elapses after the driving pulse has been supplied, and a damping effect corresponding to a tape running load is obtained, therefore, a constant intermittent running quantity is obtained irrespective of an ambient temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus in which the amount of intermittent running of a magnetic tape during slow reproduction is always constant.

[Conventional technology]

In slow playback in the magnetic recording playback bag fK, a slow motion image is obtained by intermittently driving the capstan motor and repeating still image playback and standard playback. The starting and stopping of the capstan motor must be controlled in conjunction with the rotating magnetic head. If the intermittent feeding of the tape by the capstan motor is not accurate, noise bars will increase in the reproduced image and the image quality will deteriorate. Therefore, the stability of the tape running system is important.

The conventional magnetic recording and reproducing bag shown in FIG. 3 [1 is a capstan motor 2a for rotating two capstan shafts during slow reproduction
At the same time, the capstan motor 2alC is intermittently driven almost synchronously with the roll motor 3a, which rotates the tape reel 3 on the tape winding side. The capstan motor 2a is driven by a capstan motor drive circuit 2b, and the reel motor 3a is driven by a reel motor drive circuit 3b, but these drive circuits 2b and 3b are controlled by an IC-based drive device 4. are doing.

During slow playback, the monostable multivibrator 6 is operated by the head switching pulse shown in FIG. Ru. Since the output of the flip-flop circuit 70 is supplied to the comparator circuit 9 directly or via the monostable multivibrator 8, the output of the comparator circuit 9 is the output of the monostable multivibrator 8, as shown in FIG. The pulse is connected for a holding time T.

This pulse is supplied to the capstan motor drive circuit 2b via the diode D as a drive pulse for the capstan motor 2a.

The capstan/motor drive circuit 2b applies a positive polarity voltage having a peak value corresponding to the magnitude of the 1MA pulse to the capstan motor 2a, thereby driving the capstan motor 2a in normal rotation.

By the way, the control pulse shown in FIG. ), the monostable multivibrator 12 delays T3 time, and then
As shown in F), the signal is further delayed by the monostable multivibrator 13 for 14 hours as a low level signal.

The output of the monostable multivibrator 13 is the amplifier circuit 1.
4 and applied to the base of transistor Q.

Therefore, the transistor Q is rendered non-conductive for a time T, and the diode D in the OR gate circuit 17 is
) is supplied to the capstan motor 2a.

In response to this braking pulse, the capstan motor drive circuit 2b applies a negative polarity voltage having a peak value corresponding to the magnitude of the braking pulse to the capstan motor 2a,
Brake the capstan motor 2a. That is, in the output of the OR gate circuit 17, as shown in FIG. 4, driving pulses and braking pulses appear alternately.1. The magnetic tape 10 is intermittently moved by driving and braking the capstan motor 2a, while the monostable multivibrator 15 connected to the diode Ds changes the set output of the flip-flop circuit 7 to 1.
A monostable multivibrator 18 with a 3-hour delay causes
It is triggered and stops the delay operation at the rising edge of the braking pulse. Therefore, the drive pulse of the reel motor 3a, which is the output of the amplifier circuit 16, is as shown in Fig. 4 σ).
The signal waveform is such that it rises at the falling edge of the drive pulse of the capstan motor 2a and falls at the falling edge of the braking pulse.

That is, the reel motor 3a is connected to the capstan motor 2&
It is driven intermittently almost in synchronization with the intermittent drive.

This prevents the magnetic tape 10 from sagging or abnormal tension during slow playback.

[Problem 2 to be Solved by the Invention] In the conventional magnetic recording/reproducing device 1 described above, the magnetic tape 10 wound around the tape reel 3 exhibits different running characteristics depending on the ambient temperature. The tape running load applied to the capstan motor 2 differs depending on the time of day and the low temperature of winter, making it difficult to maintain the tape intermittent running amount at an appropriate value during slow playback, especially when the motor is braked after detecting a control pulse. There is a problem in that variations in the time control at cause disturbances and noise in slow-motion playback images, which adversely affect slow-motion playback.

That is, when the ambient temperature is high, the tape running load is small, and when the braking pulse is output a certain period of time after the control pulse is detected, the magnetic tape 10
However, there was a problem in that the slow playback was disrupted because a constant amount of intermittent travel could not be ensured when the amount of travel exceeded the appropriate amount. In addition, when the ambient temperature is low, the tape running load is large, and even if a braking pulse is output a certain period of time after the control pulse is detected, the running distance of the magnetic tape 10 is less than the appropriate amount, and the tape runs intermittently. Similar problems were occurring because the quantity could not be secured.

[Means for solving problems]

This invention solves the above problems by using a driving pulse followed by a braking pulse! A magnetic recording and reproducing device that performs slow playback by intermittently running a tape using a capstan motor to which voltages of different polarities are applied, and after a drive pulse is supplied to the capstan motor, recording is performed on the magnetic tape. The peak value of a braking pulse that is supplied after a certain period of time from the time when the control pulse is detected is determined as follows:
The gist of this invention is to provide a control circuit that attenuates at a predetermined attenuation rate and obtains a braking effect commensurate with the tape running load.

[Effect]

This invention provides a method of attenuating the peak value of a braking pulse that is supplied after a certain period of time after detecting a control pulse from the magnetic tape during intermittent running of a magnetic tape during slow playback, in accordance with the elapse of time after supplying a drive pulse. To always obtain a constant intermittent running amount regardless of the degree of travel.

〔Example〕

Hereinafter, the real m-sequence of the present invention will be explained with reference to FIG. 1.2. FIG. 1.2 is a circuit diagram and a signal waveform diagram of each part of the circuit, respectively, showing an embodiment of the magnetic recording/reproducing apparatus of the present invention. In FIG. 1, the same components as in FIG. 3 are given the same reference numerals.

In FIG. 1, a magnetic recording/reproducing device 21 is provided with a control circuit 22 that attenuates a braking pulse supplied to a capstan motor drive circuit 2b. This control circuit 22 includes a charging/discharging circuit 22a that exhibits charging/discharging characteristics according to the time from when a driving pulse is supplied to the capstan motor drive circuit 2b until a braking pulse is applied, and this charging/discharging circuit. 22a
The damping circuit 22b attenuates the peak value of the braking pulse according to the output voltage of the braking pulse.

The charging/discharging circuit 22a connects a reverse current blocking diode D to a signal line branched from the anode side of the diode D, and connects the diode D to the cathode of this diode.

It has a configuration in which a parallel connection circuit of a resistor R and a capacitor C is connected. The attenuation circuit 22b includes a backflow blocking diode Ds connected to a signal line branched from the anode side of the diode D, and a common collector type transistor Q whose emitter is connected to the cathode of the diode Ds. ,
The above-mentioned positive terminal of the capacitor C is connected to the above-mentioned pace.

The capacitor C in the charging/discharging port path 22m starts charging when the driving pulse is applied, and resists R at the trailing edge of the driving pulse.
Therefore, the discharge of capacitor C starts
During the dry period, the pace potential of transistor Q1 drops exponentially. Therefore, the peak value of the braking pulse supplied to the capstan motor drive circuit 2b attenuates in accordance with the terminal voltage of the capacitor C, and as shown in FIG. 2G),
The signal waveform is as shown in (H).

Therefore, when the ambient temperature is high and the tape running load is small, the time from application of the drive pulse to detection of the control pulse is shortened.

Braking pulses are usually output earlier than usual. Therefore, the peak value of the braking pulse in this case is large, and a large braking force can be applied to fast tape feeding.

On the other hand, if the ambient temperature is low and the tape running load is large, the time from the application of the drive pulse to the detection of the control pulse will be longer.

Braking pulses are usually output later. Therefore.

In this case, the peak value of the braking pulse is small, and gentle braking can be applied to slow tape feeding.

In this way, the magnetic recording and reproducing device 21, after the drive pulse is supplied to the capstan motor drive circuit 2b,
The control circuit 22 attenuates the peak value of the braking pulse supplied after a certain period of time from the time when the control pulse recorded on the fH tape 10 is detected at a predetermined attenuation rate as time passes after the drive pulse is supplied, Since the structure has been designed to obtain a braking effect commensurate with the tape running load, early braking pulses can be applied even if the tape running load fluctuates depending on the ambient temperature.
By increasing the wave height ring and reducing the wave height value for the slower braking pulse, an appropriate braking effect can be obtained depending on the tape running speed, and a constant intermittent running amount can be obtained regardless of the ambient temperature. High-quality slow playback with little noise is possible.

〔Effect of the invention〕

As explained above, according to the present invention, after a driving pulse is supplied to the cab stan motor, the peak value of the braking pulse that is supplied after a certain period of time from the time when the control pulse recorded on the magnetic tape is detected is calculated. , attenuate at a predetermined attenuation rate over time after supplying the drive pulse,
Since the structure is designed to obtain a braking effect commensurate with the tape running load, even if the tape running load changes depending on the ambient temperature, an early braking pulse will increase the peak value, and a late braking pulse will increase the peak value by 1ViL. 'jfr: By making it small, an appropriate braking effect can be obtained according to the tape running speed, a constant intermittent running amount can be obtained regardless of the ambient temperature, and high-quality slow playback with little noise is possible. It has a great effect.

[Brief explanation of the drawing]

Figures 1 and 2 are a circuit diagram and signal waveform diagrams of various parts of the circuit, respectively, showing an embodiment of the magnetic recording/reproducing device of the present invention.
．． FIG. 4 is a circuit diagram and a signal waveform diagram of each part of the circuit, respectively, showing an example of a conventional magnetic recording/reproducing device. 2... Capstan motor, 2b... Capstan motor drive circuit, 4... Drive device, 10... Magnetic tape, 21... Magnetic recording/reproducing device, 22... Control circuit.

Claims (1)

[Claims] A magnetic recording and reproducing device that performs slow playback by intermittently running a tape using a capstan motor to which voltages of different polarities are applied according to a drive pulse and a subsequent braking pulse, wherein the drive pulse is supplied to the capstan motor. After that, the peak value of the braking pulse that is supplied after a certain period of time from the time when the control pulse recorded on the magnetic tape is detected is attenuated at a predetermined attenuation rate as time elapses after the drive pulse is supplied, and the tape runs. A magnetic recording/reproducing device equipped with a control circuit that obtains a braking effect commensurate with the load.