JPH08221849A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE: To stabilize a control signal for intermittent recording by delaying the next starting pulse by a delay time obtained by a prescribed calculation of an overrun FG pulse after impressing a braking pulse. CONSTITUTION: A starting pulse is generated in synchronization with a head changeover pulse by a starting pulse generating circuit 10 to start up a capstan motor 4. An FG pulse from an FG 6 is counted by a recording CTL making circuit 17, and the control signal is recorded on a tape 5 at prescribed timing via a control head 9. The FG pulse is counted, and when it becomes a prescribed count, a braking pulse is generated by a braking pulse generating circuit 10 to stop the capstan motor 4. When the capstan motor 4 overruns a prescribed value, an overrun FG pulse is counted by an FG counter 18, and then the starting pulse is delayed by a delay time obtained by multiplying the counted value by a prescribed coefft. by a starting phase calculating circuit 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermittent magnetic recording / reproducing apparatus which repeats running / stopping of a magnetic tape, slow-moves the magnetic tape, and writes a recording signal during a running period for long-term recording / reproducing. .

[0002]

2. Description of the Related Art A constant magnetic tape is used in an intermittent magnetic recording / reproducing apparatus for recording / reproducing for a long time by repeating running / stopping of the magnetic tape or slow running of the magnetic tape and writing a recording signal during the running period. There is an apparatus shown in FIG. 1 as an apparatus for recording a stable control signal in (Japanese Patent Application No. 6-266780).

With this device, the pulse of the frequency generator (1) (hereinafter referred to as FG) attached to the capstan motor is counted by the FG counter (2), and the voltage is applied to the control head (3) according to this count value. By applying, the control signal is accurately recorded according to the moving amount of the magnetic tape.

In such an intermittent magnetic recording / reproducing apparatus, as shown in FIG. 2, the start timing (b) of the intermittently driven capstan motor is always output in the same phase with respect to the head switching signal (a). Therefore, when the capstan motor fluctuates, the phase relationship between the recorded image and the control signal (f) cannot be kept equal.

For example, when an overrun of two FG signal pulses occurs during braking of the capstan motor during the first recording of the first field, the recording control signal is created by accurately counting the number of FG pulses. FG pulse 2 from the dotted line part shown in (f) to maintain a constant period.
It is recorded one minute before (solid line part).

However, since the recording phase of the video signal is constant with respect to the head switching signal, the video signal with respect to the recorded control signal is out of phase.

If the recording in such a state continues, the level of the output video signal at the time of reproduction fluctuates, and an unstable reproduced image is generated, which causes noise to appear on the screen.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in a magnetic recording / reproducing apparatus for intermittent recording, a recording control signal and a recording control signal are generated even if the intermittent feeding amount of a magnetic tape fluctuates. A technical issue is to keep the phase of a recorded video signal constant.

[0009]

In order to solve the above-mentioned problems, the present invention provides a cap for driving a magnetic tape in an intermittent magnetic recording apparatus for intermittently running a magnetic recording medium for recording during a running period. A stun motor, a frequency generator that generates a signal of a frequency proportional to the rotation speed of the capstan motor, a start pulse generation circuit that generates a start pulse of the capstan motor, and a braking pulse of the capstan motor. A braking pulse generating circuit, a counter for counting the output signal of the frequency generator generated in a predetermined period after the braking pulse is generated, a control head for recording a control signal on the magnetic recording medium, and a counter for changing the value of the counter. And a starting phase calculation circuit for calculating the phase of the drive pulse to be generated next and outputting it to the drive pulse generation circuit. The activation phase arithmetic circuit is characterized in that delaying the generation timing of the start pulse by a predetermined number multiplied value to the counter value.

[0010]

The magnetic recording / reproducing apparatus of the present invention counts the output signals of the frequency generator generated after the generation of the braking pulse and before the generation of the driving pulse, and delays the timing of supplying the control signal in accordance with this value. By doing so, even if the intermittent feed amount of the magnetic tape fluctuates, the phases of the recording control signal and the recording video signal can be kept constant.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetic recording apparatus according to the present invention will be described in detail below with reference to FIGS.

FIG. 3 is a block diagram of the magnetic recording / reproducing apparatus of the present invention.

In the figure, (4) is a capstan motor for running the magnetic tape (5), to which the FG (6) is attached.

The FG (6) generates two pulses having a phase delay of 90 degrees at a frequency proportional to the rotation speed of the capstan motor (4).

A magnetic head (7) records / reproduces a video signal on / from the magnetic tape (5).

Reference numeral (8) is a head drum motor, which rotationally drives the cylinder drum to which the magnetic head (7) is attached.

A control head (9) records a control signal on a control track on the magnetic tape (5).

(10) is a start pulse generation circuit which generates a capstan start pulse of a predetermined width in synchronization with the head switching pulse in the intermittent recording mode.

A braking pulse generation circuit (11) counts the FG pulse output from the FG (6) in order to stop the tape at a predetermined position after the capstan motor is activated in the intermittent recording mode. Then, a capstan braking pulse is generated.

(12) is a capstan motor rotation control circuit for rotating the capstan motor at a predetermined speed and phase.

(13) is a head drum motor rotation control circuit, which controls the rotation of the head drum motor.

A recording / reproducing control circuit (14) controls the magnetic head (7) to a recording state or a reading state.

Reference numeral (15) is an OR gate, which outputs the outputs of the starting pulse generating circuit (10), the braking pulse generating circuit (11) and the capstan motor rotation control circuit (12) to the capstan motor (4) during intermittent driving. introduce.

A switch (16) switches the output of the OR gate (15) at the time of intermittent driving and the capstan motor rotation control signal at the time of continuous driving to the capstan motor.

(17) is a recording CTL creating circuit, which counts the output pulse of FG (6) by an internal counter,
A control signal with an accurate cycle is created for the value of the count.

Reference numeral (18) is an FG counter, which is reset even at the falling edge of the output signal of the braking pulse generation circuit (11) and counts FG pulses for a predetermined period.
This count value is sent to the starting phase calculation circuit (19).

The starting phase calculating circuit (19) calculates the timing of the next starting pulse based on the count value of the FG counter (18) (a calculation method will be described later), and outputs it to the starting pulse generating circuit (10).

The above-mentioned device emits the signals of the respective parts shown in the timing chart of FIG.

In this timing chart, (a)
Is a head switching pulse, which switches channels 1 and 2 of the rotary magnetic head (7) based on this signal.

(B) is a start pulse, which is an output signal from the start pulse generating circuit (10). (C) is the output of the braking pulse generation circuit (11).

(D) is the output pulse of the capstan FG.

Here, the numeral above the FG output pulse (d) indicates the output value of the FG counter (18).

(E) is a recording mode signal, which actually puts the magnetic head in a recording state.

(F) is a control signal generation circuit (1
It is an output signal of 7) and is applied to the control head (9).

When the recording operation is started in the intermittent mode, the start pulse generator (10) creates a start pulse (b) with the head switching signal as a reference, and the capstan motor (4) is started.

When the capstan motor (4) starts rotating, the FG (6) attached to the capstan motor (4) outputs an FG output pulse (d). This pulse is counted by the counter in the recording CTL creating circuit (17), and when it reaches a predetermined value (6 in this case), the recording CTL creating circuit (17) outputs an H-level voltage to tape the N-pole magnetic field. To record.

At the same time, the braking pulse generation circuit (1
The pulse of the FG pulse (6) is counted in 1), and when it reaches a predetermined value (11 in this case), a braking pulse (c) is added to the capstan motor (4) to stop the capstan motor (4). .

Then, also in the next intermittent feed, similarly, the start pulse generating circuit (10) creates a start pulse (b) based on the head switching pulse (a), and starts the capstan motor (4).

When the capstan motor (4) starts rotating, FG pulse is output from the FG (6) attached to it. This is counted by a counter inside the recording CTL creating circuit (17), and when the count value reaches a predetermined value (21 in this case), an L level voltage is output and the S pole magnetic field is recorded on the tape.

Further, in the braking pulse generation circuit (11), FG
Count the number of pulses of the pulse and set a predetermined value (2 in this case)
When 4) is reached, the braking pulse (C) is output to the capstan motor (4).

When the capstan motor (4) stops normally, the FG pulse shown by the solid line in FIG. 4 (d) is output, but when the capstan motor (4) overruns, it is indicated by the dotted line in (d). The FG pulse shown is output.
In this case, it is a diagram in the case where two FG pulses are overrun.

If the subsequent intermittent feed is started by the start pulse having the phase shown by the dotted line (b), the FG pulse is also (d).
Occurs from the position indicated by the dotted line. Then, the recording control signal rises at the position of the dotted line (f), and the phase of the recording control pulse with respect to the tape position recorded this time is shifted from the phase recorded in the previous time.

Therefore, the FG pulse of the overrun portion is counted by the FG counter (18), and the phase of the starting pulse generated next by the starting phase calculating circuit (19) is calculated based on this count value (2 in this case). Ask for.

Since 2 pulses are output at the previous feed, the starting phase is delayed by 2 FG pulses. However, since the FG pulse is proportional to the rotation speed of the capstan motor, the FG pulse has a constant cycle. is not.

Therefore, the period of the overrun FG pulse is obtained in advance by an experiment or the like and is stored in advance in the starting phase calculation circuit as a predetermined value, and the delay time is obtained by multiplying this by the value of the FG counter.

If the number of FG pulses of the previous feeding is less than a predetermined number (24 in this case), a phase for obtaining a time starting pulse (negative delay time) multiplied by a number less than the above-mentioned predetermined value Proceed.

The next start pulse is generated by outputting this value to the start pulse generation circuit (10).

Needless to say, the above system can be realized by using either a general-purpose logic integrated circuit, a dedicated integrated circuit, or a microcomputer.

[0049]

As described above, according to the magnetic recording apparatus of the present invention, even if there is a slight change in the intermittent feed, the recording CTL is generated.
Since the video signal can be recorded in the same phase as the signal, a uniform video can be obtained without causing the level fluctuation of the output video signal even when the recorded portion is reproduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional magnetic recording / reproducing apparatus.

FIG. 2 is a timing chart showing signals at various parts of a conventional magnetic recording device.

FIG. 3 is a block diagram of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 4 is a timing chart showing signals of various parts of the magnetic recording apparatus of the present invention.

[Explanation of symbols]

 1 frequency generator 2 FG counter 3 control head 4 capstan motor 5 magnetic tape 6 frequency generator 7 magnetic head 8 head drum motor 9 control head 10 start pulse generation circuit 11 braking pulse generation circuit 12 capstan motor rotation control circuit 13 head Drum motor rotation control circuit 14 Recording / reproduction control circuit 15 OR gate 16 Switch 17 Recording control signal generation circuit 18 FG counter 19 Start phase calculation circuit

Claims (2)

[Claims] 1. An intermittent magnetic recording apparatus for intermittently running a magnetic recording medium for recording during a running period, wherein a capstan motor for driving a magnetic tape and a frequency proportional to the rotational speed of the capstan motor are used. A frequency generator that generates a signal, a start pulse generation circuit that generates a start pulse of the capstan motor, a braking pulse generation circuit that generates a braking pulse of the capstan motor, and a predetermined period after the generation of the braking pulse And a starter phase calculation circuit that calculates the phase of the drive pulse to be generated next according to the value of the counter and outputs the calculated drive pulse to the drive pulse generation circuit. Recording / playback device. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the starting phase calculation circuit delays the generation timing of the starting pulse by a value obtained by multiplying the value of the counter by a predetermined number.