JPS61160819A - Magnetic recorder of intermittent recording system - Google Patents

Abstract

PURPOSE:To check the head clogging state for each intermittent recording by reproducing the signal in the next intermittent drive period which was recorded while a magnetic tape driven intermittently is at pause and checking the presence or absence or a reproduction signal. CONSTITUTION:When an RF gate pulse has a fall after the recording is carried out by a rotary magnetic head 2a by an amount equal to a field, a capstan motor drive circuit 4 works to start a capstan motor 3. As shown by the charts (D) and (D), the motor 3 is energized forward, intermittently and then reversely. When a head switching pulse following to the one that made the head 2a perform the signal recording is supplied, a gate circuit 7 is cut off. Then the head 2a reads the track recorded in an immediately preceding stage out of a magnetic tape. When the head 2a has a clogging state, no reproduction signal is delivered from a reproduction amplifier 10. Thus the supply of the vertical synchronizing signal is cut off to a monostable multivibrator 16. Then the vibrator 16 delivers a high-level signal to turn on a display device 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intermittent recording type magnetic recording device that can detect clogging of a single rotation magnetic head at an early stage.

[Conventional technology]

Many banks and large-scale retail stores are equipped with video cameras for surveillance purposes, but in order to record for a longer time than home video tape recorders, tapes are run intermittently at regular intervals. It seems that video tape recorders that employ an intermittent recording method that records still images are often used.

[Problem that the invention seeks to solve]

In the above-mentioned conventional intermittent recording type magnetic recording device, only one of the rotating magnetic heads of a pair is used for intermittent recording, but in contrast to the chip which performs one intermittent recording, the rotating magnetic head is constantly used. It also rotates for a long time, so problems such as clogging must be detected early to avoid interruptions in recording.However, conventionally, clogging occurs in the rotating magnetic head. Since it is only possible to determine whether or not the recording has been made by playing back the recorded tape cassette, there are problems such as cleaning of a clogged rotating magnetic head may be too late.

[Means for solving problems]

This invention solves the above problems.

An intermittent recording magnetic recording device that runs a magnetic tape intermittently and records signals on the magnetic tape while the tape is stopped. It has a reproducing means for reproducing the signal read by the magnetic head, and a notifying means for detecting the presence or absence of the reproducing output of the reproducing means and notifying the occurrence of clogging of the rotating magnetic head when the reproducing output is not obtained. The main points are as follows.

[Effect]

This invention reproduces the signal recorded when the magnetic tape fed during one intermittent run stops during the first intermittent run, and detects clogging of the rotating magnetic head based on the presence or absence of the playback signal. .

〔Example〕

Embodiments of the present invention will be described below with reference to one drawing. 1 and 2 are a schematic configuration diagram and a signal waveform diagram of each part of the circuit, respectively, showing an embodiment of an intermittent recording type magnetic recording apparatus of the present invention.

An intermittent recording type magnetic recording device 1 shown in FIG.
b, a pair of rotating magnetic heads 2a, 2 in the head drum 2;
Among the rotating magnetic heads 2a, only one of the rotating magnetic heads 2a is used for still image recording.

Intermittent running of the magnetic tape requires highly accurate tape feeding, and therefore, starting and stopping the capstan motor 3 requires advanced servo technology.

4 is a capstan motor drive circuit which operates at the falling edge of the RF gate pulse output from the gate pulse generation circuit 5 which divides the head switching pulse according to the field skip ratio, and drives the capstan motor for a certain period of time. After motor 3 is started in forward rotation, it is driven at a constant low speed by intermittent energization, firstly, braking is performed by starting in reverse rotation, and once it is brought to a complete stop, it is rotated to the target rotation angle using a fine movement pulse. It is configured to allow No need 1. The intermittent rotation angle of the capstan Tanabata 3 is strictly controlled by a rotary encoder 3bK using a highly accurate slit disk 3a.

By the way, still image recording on stopped magnetic tape is done using RF
The recording is performed during the gate pulse period, and for this reason, a gate circuit 7 is provided in front of the recording amplifier circuit 6, which is operated by the RF gate pulse and allows the recording signal to pass through. The recording amplifier circuit 6 has a step-up transformer 80 first winding g8.
A rotary transformer 9 is interposed between the secondary winding (li18b) of the step-up transformer 8 and the rotating magnetic heads 2a, 2b.

In addition, the tertiary winding 8C of the step-up transformer 8 has
A reproducing amplifier circuit 10 is connected, and this reproducing amplifier circuit 10 is configured to be inverted by a polarity inverting circuit 11 and operated by nine RF gate pulses, so that the output of the recording amplifier circuit 6 is directly connected to the reproducing amplifier circuit 10. It is not supplied to the regenerative amplifier circuit IO.

A sync separation circuit 14 is connected to the regenerative amplifier circuit 10 via a limiter circuit 12 and a demodulation circuit 13. Of the horizontal and vertical sync signals separated by the sync separation circuit 14, a vertical sync signal is The configuration is such that the signal is supplied to a monostable multivibrator 16 via a waveform shaping circuit 15 at the next stage.

The monostable multivibrator 16 is a retriggerable type in which the holding state is changed by trigger input.

The retention time is set to several times the time required for one intermittent recording. Reference numeral 17 is a nine-point indicator connected to the Q output terminal of the monostable multivibrator 16, as described later.
It lights up when the rotating magnetic head 2a becomes clogged. Note that the reproduction amplifier circuit 10° limiter circuit 12, demodulation circuit 13, etc. constitute the reproduction means, and the synchronous separation circuit 14. A waveform shaping circuit 15, a monostable multivibrator 16, a clogging indicator 17, etc. constitute the notification means t.

Now, when performing intermittent recording with a field skip ratio of 8,
The RF gate pulse, which is the output of the gate pulse generation circuit 5, is supplied to the gate circuit 7 at a cycle that is one-eighth of the head switching pulse. In this example, the RF gate pulses straddle either side of the IIvA head switching pulse, so that <, R
Recording for one field is performed by the rotating magnetic head 2a switched by the head switching pulse corresponding to the center of the F gate pulse. That is, gate circuit 7
The recording signal passed through the recording amplifier circuit 6. The magnetic head 2alC is supplied for one rotation through a step-up transformer 8 and a rotary transformer 9 in sequence.

When the RF gate pulse falls after one field has been recorded by the rotating magnetic head 2a, the capstan motor drive circuit 4 is activated and the capstan motor 3 is activated. The capstan motor 3 is energized in the forward direction, then intermittently and then in the reverse direction, as shown in FIG.
When signal recording is executed and the next head switching pulse after the 9th head switching pulse is supplied, the gate circuit 7 is in a cut-off state and the one-rotation magnetic head 2a starts running on the track recorded immediately before. This means reading from the magnetic tape.

If the rotating magnetic head 2& is operating normally without any clogging, the rotary magnetic head 2& is operating normally.9. A reproduction signal is supplied to a reproduction amplifier circuit 10 via a step-up transformer 8, and a limiter circuit 12. The signal is demodulated via the demodulation circuit 13.

The output of the demodulation circuit 13 is as follows.

The vertical synchronization signal is separated and extracted in the synchronization separation circuit 14, and the vertical synchronization signal passed through the waveform shaping circuit 15f triggers the monostable multivibrator 16. Therefore, when the rotating magnetic head 2a is not clogged, the Q output terminal of the monostable multivibrator 16 is always at a low level, and the clog indicator 17 does not operate.

On the other hand, if the one-rotation magnetic head 2a becomes clogged 9,
Since the reproduction amplifier circuit IO does not output a reproduction signal, the supply of the vertical synchronization signal to the monostable multivibrator 16 is also cut off. As a result, the monostable multivibrator 16
The Q
Outputs a high level signal from the output terminal. As a result, the clogging indicator 17 operates, and the occurrence of the clogging 9 is displayed by lighting.

In this way, the intermittent recording type magnetic recording device 1 is constructed.

The signal is reproduced by the same rotary magnetic head 2a as the signal recorded immediately before, and clogging of the rotary magnetic head 2a can be reliably detected based on the presence or absence of the vertical synchronization signal in the reproduced signal.

In the above embodiment, the horizontal synchronization signal is separated in the synchronization separation circuit 14, and the horizontal synchronization signal separated by one is sent to the counting circuit (
(not shown), and when the counted value reaches a certain value, the monostable multivibrator 16 can be triggered.

〔Effect of the invention〕

As explained above, according to the present invention, the signals recorded when the magnetic tape that is fed during one intermittent run is stopped are reproduced during the first intermittent run period, and the signals are regenerated depending on the presence or absence of the playback signal. Since the configuration detects clogging of the rotating magnetic head, it is possible to check for clogging of the rotating magnetic head each time intermittent recording is performed, and the rotating magnetic head does not start until playback after recording to the tape cassette is completed. This provides excellent effects such as being able to reliably prevent inconveniences such as noticing that the magnetic head is clogged.

[Brief explanation of drawings]

FIG. 1.2 is a schematic configuration diagram and a signal waveform diagram of various parts of the circuit, respectively, showing an embodiment of an intermittent recording type magnetic recording device of the present invention. DESCRIPTION OF SYMBOLS 1... Intermittent recording type magnetic recording device, 2a... Rotating magnetic head, 10... Reproduction amplifier circuit, 12... Limiter circuit, 13... Demodulation circuit, 14... Synchronization separation circuit, 15 ... Waveform shaping circuit, 16... Monostable multivibrator, 17... Clogging 9 indicator.

Claims (1)

[Claims] This is an intermittent recording magnetic recording device that runs a magnetic tape intermittently and records signals on the magnetic tape while it is stopped. Intermittent recording comprising a reproduction means for reproducing a signal read by a magnetic head, and a notification means for detecting the presence or absence of a reproduction output of the reproduction means and notifying the occurrence of clogging of a rotating magnetic head when no reproduction output is obtained. method magnetic recording device.