JPH0676424A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To make other recording and reproducing devices incapable of reproducing due to unworkability of phase control by disturbing synchronism of positive polarity of a recording control pulse obtained from a reference signal at the recording time and working the phase control with a reference of negative polarity at the reproducing time. CONSTITUTION:The synchronism of positive polarity of the recording control pulse obtained by a reference of a rise of the reference signal having a fixed period is disturbed by a modulation circuit 9. Then, the control pulse 5 inverted by an inverter 10 and then recorded by a control pulse R/P head 11 is amplified by an amplifier 12 and is reproduced to be a control pulse 6. Moreover, the pulse 6 after processing it by a waveform shaping circuit 13 is inverted by an inverter 10, and only negative polarity is read out to be a control pulse 7 for phase control. Thus, at the time of recording, the synchronism of positive polarity of the recording control puse is disturbed, and at the time of reproducing, the phase control is worked with the reference of negative polarity, thus making other recording and reproducing devices incapable of the phase control and hence incapable of reproducing and copying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus which can be used for those whose phase is controlled based on the phase of a control pulse.

[0002]

2. Description of the Related Art FIG. 2 shows a control pulse and phase control of a conventional magnetic recording / reproducing apparatus. In FIG. 2, 1 is a reference signal having a constant period of 30 Hz, 2 is a control pulse for recording, 3 is a control pulse for reproducing, and 4 is a control pulse for phase control.
Further, FIG. 4 shows the flow until the phase control of the conventional magnetic recording / reproducing apparatus is performed. In FIG. 4, 1 is 3
A reference signal having a constant cycle of 0 Hz is shown, 2 is a control pulse during recording, 11 is a control R / P head, and 12 is a control R / P head.
Is an amplifier, 3 is a control pulse for reproduction, 13 is a waveform shaping, and 4 is a control pulse for phase control.

The operation of the magnetic recording / reproducing apparatus having the above structure will be described below.

In this magnetic recording / reproducing apparatus, the control of 2 is performed with reference to the rising edge of the reference signal of 1 having a constant period of 30 Hz.
The control pulse is recorded by 11 control R / P heads, and 3 is a reproduction control pulse amplified by 12 amplifiers. 4 is 1 control pulse of 3
3 is a control pulse for phase control in which only the positive polarity of the control pulse waveform-shaped according to 3 is read.
In addition, the rise of the reference signal of 1 30 Hz constant cycle and 4
The phase control is performed when the rising edges of the control pulse for phase control of 1) coincide with each other.

[0005]

However, in the above-mentioned conventional structure, even if important contents are recorded, other magnetic recording / reproducing apparatus can perform phase control and easily reproduce or copy. There was a drawback that it would be possible.

The present invention solves the above-mentioned conventional problems by disturbing the synchronism of the positive polarity of the recording control pulse obtained from the reference signal during recording, and keeping the synchrony of the negative polarity constant with the reference signal. It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of preventing phase control from being applied to other magnetic recording / reproducing apparatuses by performing phase control with reference to negative polarity during reproduction.

[0007]

In order to solve the above problems, the present invention disturbs the synchronism of the positive polarity of the control pulse for recording obtained from the reference signal at the time of recording, and the synchronism of the negative polarity is the reference signal. And keep it constant. During reproduction, the phase control is performed with reference to the negative polarity.

[0008]

By disturbing the positive polarity synchronism of the recording control pulse obtained from the reference signal at the time of recording by the above-mentioned means, the recording in the above-mentioned state is phase-shifted in other magnetic recording / reproducing apparatus. I try not to take control.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a control pulse and phase control of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.
FIG. 3 shows the flow until the phase control of the magnetic recording / reproducing apparatus of the present invention. In these figures, the same parts as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 1 of the present embodiment, 5 is a control pulse that disturbs the positive polarity synchronism of the control pulse and is recorded by reversing, 6 is a control pulse when 5 is reproduced, and 7 is a negative pulse. A reference control pulse for phase control is shown, and 8 is a control pulse for phase control when 5 is reproduced by a conventional magnetic recording / reproducing apparatus. Also, FIG.
9 is a modulation circuit and 10 is an inverter.

The operation of the magnetic recording / reproducing apparatus having the above structure will be described below.

In this magnetic recording / reproducing apparatus, the synchronism of the positive polarity of the recording control pulse obtained on the basis of the rising edge of the reference signal of 30 Hz constant period is disturbed by the modulation circuit of 9, and the inversion of 10 is performed. A control pulse of 5 is recorded by the control R / P head of 11 which is inverted by the control pulse, and 6 is a control pulse of 5 which is amplified by a 12 amplifier and reproduced. The control pulse of 7 is a waveform in which the control pulse of 6 is shaped by 13 and the control pulse of 10 is inverted.
It is a control pulse for phase control in which only the negative polarity is read by reversing the pulse by using the control pulse. The phase control is performed when the rising edge of the reference signal having a constant period of 30 Hz at 1 and the rising edge of the control pulse for phase control at 7 coincide with each other. 8
5 is reproduced by the conventional magnetic recording / reproducing apparatus, but it is understood that the rising edge of the control pulse does not coincide with the rising edge of the reference signal of 1 having a constant period of 30 Hz. Therefore, no phase control is required.

As described above, according to the present embodiment, by disturbing the synchronism of the positive polarity of the control pulse for recording obtained from the reference signal at the time of recording, the phase control can be performed in other magnetic recording / reproducing apparatus. It can be prevented.

In this embodiment, one reference signal is 30
Although the frequency is set to 30 Hz, needless to say, 30 Hz is equivalent regardless of the frequency.

Needless to say, the width of the other control pulses is not limited to the constant width.

[0015]

As described above, according to the present invention, the synchronism of the positive polarity of the recording control pulse obtained from the reference signal during recording is disturbed, and the synchronism of the negative polarity is kept constant with the reference signal. To do. During reproduction, the phase is controlled with reference to the negative polarity. Therefore, it is possible to realize a magnetic recording / reproducing apparatus in which reproduction and copying cannot be performed because phase control is not applied in other magnetic recording / reproducing apparatuses.

[Brief description of drawings]

FIG. 1 is a diagram showing a control pulse and a phase control of a magnetic recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram showing a control pulse and a phase control of a conventional magnetic recording / reproducing apparatus.

FIG. 3 is a diagram showing a flow until phase control of the magnetic recording / reproducing apparatus of the present invention is applied.

FIG. 4 is a diagram showing a flow until phase control is applied to a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 9 Modulation circuit 10 Inverter 11 Control pulse R / P head 12 Amplifier 13 Waveform shaping

Claims (1)

[Claims] 1. In a magnetic recording / reproducing apparatus for controlling the phase based on a control pulse recorded on a magnetic tape, the positive polarity synchronism of a recording control pulse obtained from a reference signal during recording is disturbed. The magnetic recording / reproducing apparatus is characterized in that the synchronism of the negative polarity is kept constant with the reference signal and the phase is controlled with the negative polarity as a reference during reproduction.