JPS6381601A - Magnetic recording and erasing circuit - Google Patents

Abstract

PURPOSE:To erase tracks in a short time to the level where rerecording is possible by supplying an erasion signal having specified frequency and current through a erasion signal generation means and making a magnetic head move in a diameter direction of a magnetic disk. CONSTITUTION:When all the tracking erasion keys of an operation part 104 are operated, the magnetic head 56 is moved to a center of an No0 track, etc., by a control circuit 12, a switch 52 is connected to a contact point (a) and a switch 45 is switched off. By controlling with the aid of the circuit 12 the erasion signal whose first frequency is higher than an FM chroma signal having the lowest frequency and which is higher than a recording current is supplied to the head 56, which is made to move in a central direction of a disk 60, from an FM amplifier 24 at a necessary speed. Next, between the first frequency and a second frequency which is higher than the maximum of an FM signal frequency the frequency is made to later gradationally, in three gradations, and the erasion signal which is higher than the recording current executes the erasion, so that the respective tracks of the disk 60 are erased in a short time to the level where rerecording is possible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic recording erasing circuit for erasing signals recorded on a magnetic disk, and particularly for erasing signals recorded on tracks of a magnetic disk over the entire trunk. The present invention relates to a magnetic recording erasing circuit for erasing data.

[Background of the invention]

Recently, imaging devices such as solid-state image sensors and image pickup tubes have been combined with recording devices that use magnetic recording media such as magnetic disks, which are inexpensive and have a relatively large storage capacity, to take still images of subjects. An electronic still camera system has been developed in which images are recorded on a magnetic recording medium and images are reproduced using a separate television system or printer.

We also proposed a magnetic recording and reproducing device that photographs a still image recorded on a visible recording medium such as ordinary film or photographic paper with a television camera, and records a video signal representing the still image on such a magnetic recording medium. has been done.

In these electronic still cameras and magnetic recording/reproducing devices, for example, a video signal representing one frame of a still image is sequentially recorded on each track of a plurality of tracks formed on a magnetic disk. There is also a demand for erasing and re-recording video signals on such magnetic disks on which video signals have been recorded. In particular, when recording video signals representing new still images on a magnetic disk that no longer needs to store still images, it is possible to re-record all video signals recorded on the magnetic disk. It is necessary to erase it to the level that is possible.

One recording method uses the band from OMHz to 12MHz, and the band below 2.5MHz is used as a line-sequential color difference signal,
Furthermore, a band larger than this is used for the luminance signal, and one field of video signal is recorded on one track using the FM modulation method. When erasing a track on which a video signal having such a frequency spectrum is recorded, it has been considered to erase one track using a signal whose frequency is continuously changed from a low frequency to a question frequency.

However, as is well known, signals with low frequency components magnetize to a relatively deep position in the magnetic layer of a magnetic recording medium, so in order to sufficiently erase this, the low frequency erase signal must be swept with a sufficiently long frequency sweep period. must be given. Therefore, it takes a long time to effectively erase a recorded video signal, and the method of recording such an erase signal on a track-by-track basis requires a long waiting time before transferring the magnetic head to the next trunk. It also requires. For this reason, it takes a considerable amount of time, for example, about 50 hours, to erase all 50 tracks recorded on a 47φ video disc.
It took about 0 seconds.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of these circumstances, it is an object of the present invention to provide a magnetic recording erasing circuit that can effectively erase all signals recorded on the entire magnetic disk in a short period of time.

[Summary of the invention]

In order to achieve the above object, the present invention includes a magnetic recording erasing circuit for erasing tracks of a magnetic recording medium on which a plurality of frequency-multiplexed signals are recorded, in which the magnetic recording medium is rotationally driven. A recording means for recording a signal on each track, and a first frequency that is lower than the upper limit of the recording frequency band of the magnetic head of the recording means and higher than the center frequency of a signal with a lower frequency among the plurality of signals;
an erase signal generating means that generates an erase signal whose frequency is varied in a frequency range up to a second frequency higher than the upper limit of the recording frequency band and supplies the erase signal to the magnetic head; .

current setting means for setting the current value of the erase signal to be larger than the optimum recording current value of the magnetic head during recording; and stepwise changing the frequency of the erase signal output from the erase signal generating means when erasing the recorded signal. and setting the current value of the erase signal higher than the optimum recording current value of the magnetic head in the recording means, and at each step of the stepwise change in the frequency of the erase signal, the erase signal of a constant frequency is set. Controls the recording means, erasure signal generating means, and current setting so that the magnetic head of the recording means is supplied with the magnetic head, and the magnetic head is moved in the radial direction of the magnetic disk, so that recording is performed over all tracks each time. The invention is characterized in that it is equipped with a control means for controlling.

〔Example〕

Hereinafter, a preferred embodiment of the magnetic recording/erasing circuit according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a magnetic recording/reproducing apparatus to which the present invention is applied. In the same figure, for example, primary color signals R, G, B output from a television camera etc. and a composite synchronization signal C5Vn
c is a luminance signal Y and a color difference signal R-Y by the decoder 10.
, B-Y.

The color difference signals R-Y and B-Y output from the decoder 10 are input to the FM modulator 38 via the analog switch 1).

The analog switch 1) is alternately switched every horizontal scanning period (H) by a switching pulse SP, and creates a line-sequential color difference signal based on the color difference signals RY and BY.

The FM modulator 24 is a circuit that performs FM modulation on the luminance signal Y and generates an erasure signal as will be described in detail later. As shown in FIG. 2, the signal band spectrum is centered around 7 MHz, with the sync tip level 26 set at 6 MHz, and the white peak level 28 set at 7.5 MHz. The FM luminance signal output from the FM modulator 24 passes through a high-pass filter (HPF) 32 and undergoes frequency axis correction in a frequency characteristic correction circuit 37 before being input to the mixing circuit 34 . The frequency of the high-pass filter 32 is approximately 2.5 MHz.
It has frequency characteristics that allow the above signals to pass through. Furthermore, the signal passing through the high-pass filter 32 can be bypassed via an analog switch 33 that is turned on and off by a control signal 93 output from the control circuit 12. The FM modulator 38 performs FM modulation on the line-sequential color difference signal input via the analog switch 1). As shown in Figure 2, the signal band spectrum is 2.5MHz or less,
The center frequencies are set to 1.2 MHz for the color difference signal RY and 1.3 MHz for the color difference signal B-Y. FM
The FM line sequential color difference signal output from the modulator 38 passes through a low-pass filter (LPF) 42 and is then sent to the frequency characteristic correction circuit 4.
3, frequency axis correction is performed, and the signal is input to the mixing circuit 34 via an analog switch 45 that turns on and off in response to a control signal 95 output from the control circuit 12.

The low-pass filter 42 has frequency characteristics that allow signals having a frequency of 2.5 MHz or less to pass therethrough. Note that the composite synchronization signal C5□0 is input to the FM modulators 24 and 38.

The mixing circuit 34 is a circuit that mixes the FM luminance signal output from the frequency characteristic correction circuit 37 and the FM line sequential color difference signal output from the frequency characteristic correction circuit 43 and synthesizes it into an FM video signal for recording. The output signal is sent to the recording amplifier 48
is input. Recording F output from recording amplifier 48
The M video signal is the control signal 9 output from the control circuit 12.
The signal is supplied to the magnetic head 56 via an analog switch 52 which switches in response to signal 6.

The magnetic head 56 is movable in the radial direction R along the recording surface 62 of the magnetic disk 60 by a step motor 65, as conceptually indicated by a dashed line 64. The step motor 65 has four phases A, A, B, driving pulses are given. The moving direction of the magnetic head 56 is determined by the rotating direction of the step motor 65, and the moving distance of the magnetic head 56 is proportional to its rotation angle. For example, this is per pulse of the shift pulse of the step motor 65.

The step motor 65 rotates about 18 degrees, thereby moving the magnetic head 56 about 5 μm. Therefore, 20 shift pulses result in a transfer of 100 μm (1 track).

Here, one shift pulse means one change in the excitation pattern by four-phase drive pulses consisting of A phase, W phase, B phase, and ■ phase, as shown in FIG. When moving the magnetic head 56 in the forward direction, the excitation pattern is changed to 1001-1)00-01)0 for every shift pulse.
-001), and when transferring in the opposite direction, the excitation pattern is changed in the reverse order.

The magnetic disk 60 is connected to the rotating shaft 6 of a spindle motor 66.
8 is removably attached. The spindle motor 66 is
It is rotationally driven by the motor drive circuit 70, and uses a frequency signal obtained from the frequency signal generating section to steadily rotate at a predetermined speed, 3.600 rpm in this example.

The tracks formed on the magnetic disk 60 are composed of a recording track in an area for recording signals and a guide band in an area for separating adjacent trunks, and the width W1 of the recording track is approximately 60 μm. , the width W2 of the guide band is approximately 40 μm.

A detector 74 is arranged near the core 72 of the magnetic disk 60. This detects the timing mark formed on the core 72 and makes one rotation per rotation of the magnetic disk 60.
Generates a pulsed phase synchronization signal PG. The control circuit 12 controls the motor drive circuit 70 using this phase synchronization signal PG, and adjusts the rotational phase of the magnetic disk 60.

The magnetic head 56 is a recording/reproducing head in this embodiment, and during reproduction, the reproduced FM video signal is inputted to the reproduction amplifier 78 via the contact of the analog switch 52. The reproduced FM video signal output from the regenerative amplifier 78 is demodulated by a reproducing circuit 82 and then input to a video monitor device 84 . As a result, the magnetic disk 60
The FM video signal recorded on the FM video signal can be reproduced as a visible video. Note that the magnetic head 56 is a single type magnetic head, and a head gap of about 60 μm is formed.

Incidentally, in this embodiment, the magnetic head 56 having the reproduction characteristics shown in FIG. 4 is used. In the figure, the horizontal axis indicates frequency, and the vertical axis indicates reproduction voltage. The recording frequency band of the magnetic head 56 is about 0.5 MI (z to 7.5 MHz), and the reproduction voltage of the magnetic head 56 is about 1.15 m VP at the center frequency (1.25 MHz) of the FM line sequential color difference signal. -P, whereas it is approximately 0.36 mV at the center frequency (6.75 MHz) of the FM brightness signal.In this way, the FM video signal recorded on the magnetic disk 60 by the magnetic head 56 is Of these, the FM line sequential color difference signal is reproduced with a voltage approximately 10 dB higher than the FM luminance signal.

The reproduced FM video signal output from the reproduction amplifier 78 is also input to an envelope detector 86 that detects the envelope of the FM video signal read from the magnetic disk 60 by the magnetic head 56. The envelope detection signal output from the envelope detector 86 is used to search for tracks on the magnetic disk 60. When the magnetic head 56 is moved in the radial direction R of the magnetic disk 60, the position where the envelope detection signal shows a peak is the center of the track where the FM video signal is recorded. The control device 12 controls the motor drive circuit 58 based on the signal from the envelope detector 86, and controls the magnetic head 5.
6 is placed on the center of a predetermined trunk, and the recording track is checked.

FIG. 5 shows the relationship between the tracks formed on the magnetic disk 60 and the home position HP (original position or standby position) of the magnetic head 56. Fifty trunks are provided concentrically on the magnetic recording surface 62 of the magnetic disk 60, and tracks from tlhl to 50 are attached in order from the outer trunk. Further, on the recording surface 62 of the magnetic disk 60, in addition to the tracks, for example, data signals other than video signals may be recorded, or track blocks 1 to IV may be recorded.
If a defective track occurs on the trunk of the h50, on which video signals cannot be recorded normally, a preliminary track to be used as a replacement is located further outside track number 1.
Several tracks are each formed further inside the track depth 50. These trunks are arranged in order from the outermost part of the truck than the other. N+L 1
..., N1 in order from the innermost one from track depth 50)
A track number of 51, N[L52... is attached. The home position HP is located on the outermost side of the magnetic disk 60.

This home position HP is not attached to the magnetic disk 60, but is an extreme position assigned on the movement path of the magnetic head 56. Home position HP
is sensed by the home position switch. Moving the magnetic head 56 from the outer circumferential side to the inner circumferential side of the magnetic disk 60 is forward feeding, and moving in the opposite direction is called reverse feeding.

The control circuit 12 is a circuit that unifies and controls the operation of the entire apparatus, and instructions from the operator are inputted from the operation unit 104 through key operations. The operation unit 104 includes, for example, a recording key for instructing recording on the magnetic disk 60, a head transfer key for instructing transfer of the magnetic head, a track erase key for instructing erasure of recording in units of tracks, and a signal for all recording tracks. It includes an all-track erase key that instructs to perform erasing.

Next, FIG. 6 shows a specific configuration of the FM modulator 24 for the luminance signal Y, and also shows a schematic configuration of the high-pass filter 32 and the frequency characteristic correction circuit 37. FM modulator 24
includes a frequency oscillator 200, which in this example is a model AN-630 supplied by Matsushita Electric Industrial Co., Ltd.
It is realized using an integrated circuit such as 6. Integrated circuit 200 includes a multi-by-break, the oscillation frequency of which depends on the capacitor C3 connected between terminals 8 and 9 and the current flowing into terminal 12.

The luminance signal Y output from the decoder 10 is input to the 0; chip I6 of the integrated circuit 200 via the capacitor C1.
Composite synchronization signal CSYI'le is input to terminal 5 via capacitor C2. Based on these signals input to the terminal 16 and the terminal 5, the integrated circuit 200 outputs the FMAff degree signal as the end signal 1 as described later. This FM luminance signal is input to the base terminal of the transistor Q2, and thereby the FM luminance signal is output to the high-pass filter 32 at the subsequent stage via a capacitor C4 and a resistor R5 which are connected in series to the emitter terminal of the transistor Q2.

The high-pass filter 32 includes coils L1, L2 and a capacitor C.
A resistor RI8 is connected in parallel to the outside of the output side of the high-pass filter 32. Furthermore, the cancellation signal, which will be described later, is sent to a high-pass filter 32.
The signal is input to the frequency characteristic correction circuit 37 via an analog switch 33 and a resistor R33 connected to the output side of the capacitor C4 of the FM modulator 24 and the output side of the high-pass filter 32. It has become. The current value of the erase signal outputted via the analog switch 33 is approximately 1.2 with respect to the optimum recording current value of the magnetic head 56.
The resistance values of the resistor R5 of the FM modulator 24 and the resistor R33 are determined to be more than twice as large. A variable resistor R19 is connected in parallel to the output side of the frequency characteristic correction circuit 37.
By adjusting the variable resistor R19, the level of the FM luminance signal is set to be approximately 20 dB higher in voltage than the FM line sequential color difference signal.

Further, from the control circuit 12, an output permission signal 91 for permitting the output of the FM brightness signal or the erase signal output from the terminal 1) of the integrated circuit 200 is inputted to the base terminal of the transistor Q1 through the resistor R1, and further to the collector thereof. The signal is input to the base terminal of the transistor Q2 via the terminal.

As a result, when the output permission signal 91 outputted from the control circuit 12 becomes low level, for example, the transistor Q1 becomes m
As a result, transistor Q2 is turned off, so that no signal is output from terminal 1).

The current flowing into the terminal 12 of the integrated circuit 200 is mainly caused by the conduction of the transistor Q5 through the variable resistor R6 and the resistor R7.
and variable resistance R10 and resistance R1) depending on conduction of transistor Q4. The variable resistor R6 and the resistor R7 are adjusted according to the value of the capacitor C3 so that the brightness level 26 of the luminance signal Y becomes 6 MHz. Similarly, variable resistor RIO and resistor R1) are
Adjustment is made to define a difference of 1.5 MHz from 6 MHz so that the white peak level 28 of the luminance signal Y becomes 7.5 MHz.

When the transistor Q5 is in a conductive state, a current determined by the variable resistor R6 and the resistor R7 flows through the terminal 12 of the integrated circuit 200, and a 6 MHz OFMRi degree signal with a center frequency of 6 MHz is output as a sync chip to the terminal 1). When the level of the luminance signal Y input from the decoder 10 to the terminal 16 of the integrated circuit 200 changes, the signal levels at the terminals 14 and 15 change accordingly, causing the transistor Q3 to conduct accordingly. In response to conduction of transistor Q3, transistor Q4 also conducts, and an output current flowing through its emitter follower (variable resistor RIO and resistor R1) is supplied to terminal 12 of integrated circuit 200. Therefore, the current flowing into the terminal 12 of the integrated circuit 200 is controlled according to the degree of conduction of the transistor Q4, and thereby the frequency of the FM luminance signal outputted to the terminal 1) is controlled from the center frequency of 6 MHz to 7.5 MHz. Change.

Incidentally, the terminal 12 of the integrated circuit 200 is further provided with an integrated circuit drive circuit 202 that sets the frequency of the signal used for erasing the recorded signal.

The integrated circuit drive circuit 202 includes transistors Q7, Q8,
It consists of Q9 and QIO, and resistors R14, R15, R16 and R17 connected to each collector terminal, respectively. In this embodiment, when erasing a recorded signal, the current determined by the resistors R14, R15, R16, and R17 when the transistors Q7, Q8, Q9, and QIO are turned on flows into the terminal 12 of the integrated circuit 200. It has become. This allows terminal 1) of the integrated circuit 200 to
For example, when transistor Q7 is made conductive, approximately 7M
Hz (first frequency) is output, and when transistor Q8 is turned on, the frequency is about 10.5 MHz.
An erase signal of about 14 MHz is output when the transistor Q9 is made conductive, and an erase signal of about 20 MHz is output when the transistor QIO is made conductive.
(second frequency) is output.

In this way, the first frequency of the erase signal is set to about 7 MHz, which is near the upper limit of the frequency that can be recorded by the magnetic head 56, and the second frequency is set to about 20 MHz. The frequency of the erasure signal is set to increase stepwise in the range from the first frequency to the second frequency.

Furthermore, when outputting the erase signal from the integrated circuit 200, the pace of the transistor Q6 is controlled from the f1)1 circuit 12 so that the current flowing into the terminal 12 is not influenced by the brightness signal Y at the terminals 14 and 15. A low-level erase signal 90 is output to the terminal 89 to turn off the transistor Q3.

Transistors Q7, Q8, Q of integrated circuit drive circuit 202
9 and QIO base terminals 94, 96, 98 and 10
0 is sequentially supplied with an erase drive signal 92 from the control circuit 12. In this embodiment, for example, the control circuit 12 uses the operation unit 1 to erase all video signals recorded on 50 tracks from track Hiro 1 to track Nα50.
In response to the operation of the all-track erase key No. 04, for example, as shown in FIG.
A low level erase drive signal 92 is provided to the base terminal 94 of transistor Q7 of FM modulator 24. This results in
Transistor Q7 conducts and terminal 12 of integrated circuit 200
A current of a predetermined value flows into the terminal 1), and an erase signal of about 7 MHz is output from the terminal 1 for a period T1. Thereafter, in order to similarly erase 50 tracks, during a period T2 from time t1 to time t2, which is shorter than the period T1, an erase drive signal 92 is sent from the control circuit 12 to the base terminal 96 of the transistor Q8 of the FM modulator 24. is supplied, and as a result,
An approximately 10.5 MHz erase signal is output from terminal 1) over period T2.

Further, during a period T3 from time t2 to time t3, the erase drive signal 92 is supplied from the control circuit 12 to the base terminal 98 of the transistor Q9 of the FM modulator 24, and during a period T4 from time t3 to time t4, the transistor Q
An erase drive signal 92 is supplied to the base terminal 100 of the IO. As a result, an approximately 14 MHz cancellation signal is transmitted from terminal 1) of the integrated circuit 200 of the FM modulator 24 during the period T3.
Erasing signals of about 20 MHz are sequentially output only during period T4. Then, these erase signals are sequentially transmitted to the transistor Q
It is amplified by 2. The output level is set to the same level as the normal FM brightness signal, and the erase signal is outputted via the analog switch 33, so that the magnetic head 56 receives approximately 1.2 times or more of the optimum recording current value. Current is supplied.

Next, referring to FIG. 8, the operation of the magnetic recording/reproducing apparatus having the above configuration will be described. The spindle motor 66 is constantly rotating at a predetermined speed of 3.60 rpm. In the normal state, the analog switch 52 is in the illustrated connection state (contact b
)It is in. Therefore, if a video signal is recorded on the magnetic disk 60, the video is reproduced on the monitor device 84 through the reproduction amplifier 78 and the reproduction circuit 82.

Operate the head transfer key on the operation unit 104 to move the magnetic head 5.
6 is placed at an empty track position on the magnetic disk 60. This is done by the control circuit 12 controlling the motor drive circuit 58 in response to the head transfer key, and the control circuit engineer 2 determines whether the track is unrecorded via the envelope detector 86. This is done by detecting the reproduction output of the magnetic head 56.

When the magnetic head 56 is placed on the empty track, the operator operates the recording key on the operation unit 104.

As a result, first, the composite synchronization signal C5ync and the luminance signal Y output from the decoder 10 are FM-modulated by the FM modulator 24, and then the FM luminance signal output from the FM modulator 24 is processed by the high-pass filter 32 and frequency characteristic correction. The signal is input to the mixing circuit 34 via the circuit 37. Further, the chroma signal C1, that is, the color difference signal R output from the decoder 10
-Y and B-Y are converted into line-sequential color difference signals by the analog switch 1), and then FM-modulated by the FM modulator 38. The FM line sequential color difference signal output from the FM modulator 38 is input to the mixing circuit 34 via the low-pass filter 42 and the frequency characteristic correction circuit 43, where it is mixed with the FM luminance signal.

Regulation according to this? 1) The circuit 12 outputs the control signal 96 to switch the analog switch 52 to the contact a opposite to that shown in the figure for a period of 1 V from the phase synchronization signal PC. Therefore, the recording FM video signal output from the mixing circuit 34 is
The signal is supplied to a magnetic head 56 via a recording amplifier 48 and an analog switch 52, and one field of video signals is recorded on one track of a magnetic disk 60. The reproduction output of the magnetic head 56 is output via the restored analog switch 52 (
It is visualized on the monitor device 84 via the contact b), thereby allowing the recording state of the track to be confirmed. Then, while such operations are repeated, field video signals are sequentially recorded on the empty trunks of the magnetic disk 60.

For example, if the user wishes to erase all of the video signals recorded on the magnetic disk 60 in this manner, the user operates the all trunk erase key on the operation unit 104. The control circuit 12 performs tracking control in response to this, so that the magnetic head 56 is placed, for example, on the center of the track at track level 0. Next, the control circuit 12 first outputs a control signal 96 to switch the analog switch 52 to contact a, and then outputs a control signal 95 to turn off the analog switch 45.
control so that the FM line sequential color difference signal is not input to the mixing circuit 34.

Then, the control circuit 12 outputs the erase signal 90, the output permission signal 91, and the control signal 93 to the FM modulator 24 during the period T1 from time tQ to tl, and further outputs the erase signal 90, the output permission signal 91, and the control signal 93 to the base terminal 94 of the transistor Q7 of the integrated circuit drive circuit 202. An erase drive signal 92 is output. As a result, FM modulator 2
An erase signal of about 7 MHz is output from the terminal 1) of the integrated circuit 200 of No. 4, and the erase signal is supplied to the magnetic head 56 via the analog switch 52. In addition, in accordance with this, for example, three
A step motor drive signal 57 for outputting only 1,020 drive pulses of 00PPS is supplied. The motor drive circuit 58 receives this step motor drive signal 57, controls the step motor 65, and as shown in FIG. While the magnetic disk 60 makes one rotation (1/60 second), it is moved from the position shown by a distance E1)1) of about 15 μm to the position shown by reference numeral 56B on the inner circumferential side. Furthermore, the magnetic head 56 is moved approximately 15 μm by the step motor 65 from the position 56B to the inner position 56C during one rotation of the magnetic disk 60. Therefore, the magnetic head 56 is moved approximately 60 μm while the magnetic disk 60 rotates four times by the step motor 65, and during this time the magnetic head 56 is moved by the recording track 62A of the track 0 and the guide band 66.
The erase signal is recorded in a spiral over a 2B area. Thereafter, the motor drive circuit 58 controls the step motor 65 to move the magnetic head 56 to the center position 56D of the recording track 62A of the trunk stream 51. As a result, the magnetic head 56 is moved by the step motor 65 to the recording track 6 of the track 1) ho.
Approximately 5.100 μm from the center position of 2A to the center position of recording track 62A of the track of trunk place 51
The distance L1 is transferred in about 3.40 seconds.

That is, the erase drive signal 92 is output from the control circuit 2 to the base terminal 94 of the transistor Q7 of the FM modulator 24 for a period T1 of approximately 3.40 seconds during which the magnetic head 56 is being moved on the track.

Next, the control circuit 12 outputs the erase drive signal 92 to the base terminal 96 of the transistor Q8 of the integrated circuit drive circuit 202 during a period T2 from time t1 to time t2. As a result, an approximately 10.5 MHz erasing signal is output from terminal 1) of the integrated circuit 200 of the FM modulator 24, and the erasing signal is supplied to the magnetic head 56 via the analog switch 52.

In addition, in accordance with this, the control circuit 12 sends a motor drive circuit 58 to transport the magnetic head 56 placed on the track of the trunk space 51 in the reverse direction to its original position on the track O. For example, a step motor drive signal 57 is supplied that outputs only 1,020 drive pulses for reverse feeding of 600 PPS. The motor drive circuit 58 receives this step motor drive signal 57 and controls the step motor 65 to move the magnetic head 56 located at the center of the recording track 62A of the track width 51 from the position 56D to the magnetic disk. 6
While 0 rotates once, it is transferred about 30 μm to the outer circumferential side. Further, the magnetic head 56 is moved further toward the outer circumference by about 60 μm while the magnetic disk 60 rotates twice by the step motor 65.
During this period, an erase signal is spirally recorded on the recording track 62A of the trunk of the track 51 and on the trunk on the outer circumferential side. Thereafter, the motor drive circuit 58 controls the step motor 65 to move the magnetic head 56 to the track block 51.
The distance L1 from the track tlkLo to the original position of the track tlkLo is transferred in about 1.7 seconds, and an erase signal is recorded in a spiral shape during that time. That is, the erase drive signal 92 is output from the control circuit 12 to the base terminal 96 of the transistor Q8 of the FM modulator 24 for a period T2 of approximately 1.7 seconds during which the magnetic head 56 is being moved on the track.

Then, the control circuit 12 operates during a period T from time t2 to time t3.
3, the transistor Q of the integrated circuit drive circuit 202
An erase drive signal 92 is outputted to a base terminal 98 of 9. As a result, an approximately 14 MHz erasing signal is output from terminal 1) of the integrated circuit 200 of the FM modulator 24, and the erasing signal is supplied to the magnetic head 56 via the analog switch 52.

In addition, in accordance with this, the control circuit 12 also includes a motor drive circuit 5.
8 is supplied with a step motor drive signal 57 that outputs, for example, 1,020 drive pulses for sequential feeding of 600 PPS. The motor drive circuit 58 receives this step motor drive signal 57 and controls the step motor 65 to move the magnetic head 56 so that the magnetic disk 60 is
While rotating, it is moved about 30 μm toward the inner circumferential side from the position indicated by reference numeral 56A on the track of track block 0. Thereafter, the motor drive circuit 58 controls the step motor 65 to move the magnetic head 56 from the track NaO over the trunk of the track 51 in about 1.7 seconds as before, and records the erase signal in a spiral shape during that time. let That is, the erase drive signal 92 is outputted from the control circuit 12 to the base terminal 98 of the transistor Q9 of the FM modulator 24 for a period T3 of approximately 1.7 seconds during which the magnetic head 56 is being moved on the track.

Furthermore, the control circuit 12 controls the transistor QIO of the integrated circuit drive circuit 202 during a period T4 from time t3 to time t4.
An erase drive signal 92 is output to the base terminal 100 of the . As a result, an approximately 20 MHz erase signal is output from terminal 1) of the integrated circuit 200 of the FM modulator 24, and the erase signal is supplied to the magnetic head 56 via the analog switch 52.

In addition, in accordance with this, the control circuit 12 also includes a motor drive circuit 5.
8 is supplied with a step motor drive signal 57 for outputting only 1,020 drive pulses for reverse feed of 600 PPS, for example. The motor drive circuit 58 receives this step motor drive signal 57 and controls the step motor 65 to move the magnetic head 56 from the track space 51 to the trunk I.
It is moved on a track of kO in about 1.7 seconds as before, and an erasure signal is recorded in a spiral shape during that time.

That is, the erase drive signal 92 is outputted from the control circuit 12 to the base terminal 100 of the transistor QIQ of the FM modulator 24 for a period T4 of approximately 1.7 seconds during which the magnetic head 56 is being moved on the track.

As described above, in the magnetic recording/erasing circuit of this embodiment, the FM data recorded on the 50 tracks of the magnetic disk
When erasing a video signal, first, in period T1, all tracks are erased with an erase signal having a lower frequency (first frequency) than the lowest frequency FM chroma signal and a current value larger than the optimum recording current value of the magnetic head. FM chroma signal of about 3
．． The signal is erased for only 4 seconds, and then the frequency is increased in three steps from T2 to T4, and the FM brightness signal of all trunks is erased for about 1.7 seconds each time. It is possible to erase 50 tracks in only 8.5 seconds.In this way, the first frequency of the erase signal is set near the upper value of the frequency recordable by the magnetic head, and By setting the frequency higher than the lowest frequency signal among multiple target signals,
Erasing time is reduced.

Furthermore, in this embodiment, the current value of the erase signal was set higher than the optimum recording current value of the magnetic head in the range from the first frequency (approximately 7 MHz) to the second frequency (approximately 20 MHz); however, this is not limited to this. First, the current value of only the erasing signal at least at the first frequency may be set high.

Furthermore, by setting the start and end positions of recording of the erasure signal on the trunk where the video signal indicating the still image is not recorded, the video signal can be erased.

For example, it is not affected by damage caused by stamping of the magnetic head.

In this embodiment, a circuit for generating an erasure signal is provided in the FM modulator 24 for the luminance signal. In this case, there is an advantage that the frequency oscillation circuit can be used for FM modulating the luminance signal, but the frequency oscillation circuit is not necessarily limited to this, and may be provided in the FM modulator 38 for color difference signals, for example. Further, an oscillation circuit separate from these FM modulators may be provided. still,
Using an FM modulator has the advantage that the circuit configuration does not become complicated.

FIG. 9 shows a schematic configuration of another embodiment of a magnetic recording/reproducing apparatus to which the present invention is applied. In FIG. 9, the same elements as those shown in FIG. 1 are designated by the same reference numerals.
Explanation of the elements will be omitted. In the figure, the recording FM video signal output from the mixing circuit 34 is input to two recording amplifiers 106 and 108, of which the signal output from the recording amplifier 106 is transmitted through the contact a of the analog switch 1)0. and is supplied to the first magnetic head 61A of the magnetic head 61. Further, the signal output from the recording amplifier 108 is supplied to the second magnetic head 61B of the magnetic head 61 via the contact C of the analog switch 1)0.

The analog switch 1)0 operates in response to a control signal 97 from the control circuit 12, and is switched to contacts A and D shown in the figure during playback, and switched to contacts A and C when recording a signal. It will be done.

The magnetic head 6E is a two-head type magnetic head integrally constructed with two magnetic heads each having a heald gap of about 60 μm, and the heald gap of the first magnetic head 61A of the magnetic head 61 is and a second magnetic head 61
There is a distance of about 100 μm from the head gap of B.

The magnetic head 61 records an old video signal on each of the two tracks and reproduces one field of video signal recorded on each of the two trunks. Furthermore, by using only one magnetic head, it is possible to record or reproduce the same signal as with a single type magnetic head.

In this embodiment, the first magnetic head 6 of the magnetic head 61
The magnetic heads 1A and the second magnetic head 61B each having the same reproduction characteristics as shown in FIG. 4 are used.

The regenerative amplifier 1) 2 is connected to the first magnetic head 61 of the magnetic head 61.
The reproduction amplifier 1) 4 amplifies the reproduced FM video signal of the field reproduced by the second magnetic head 61.
The reproduced FM video signal of the field reproduced by B is amplified. The reproduced FM video signal outputted from the reproduced amplifier 1) 2 is supplied to the contact point a of the analog switch 13, and the reproduced FM video signal outputted from the reproduced amplifier 1) 4 is supplied to the contact point a.

The analog switch 13 receives the control signal 99 output from the control circuit 12 and sends each reproduced FM video signal reproduced from the two tracks to the envelope detector 86.
The output is switched alternately every 1■.

The reproducing circuit 83 performs a
The FM video signal is converted into an SC video signal so that the video monitor device 84 can reproduce a still image based on the reproduced FM video signal.

The control circuit 15 is a circuit that unifies and controls the operation of the entire apparatus, and in addition to the various controls described in the above embodiments, particularly controls the recording and reproduction of fields or frames by the magnetic head 61.

Next, with reference to FIG. 10, the operation of the magnetic recording/reproducing apparatus having the above configuration will be described. The spindle motor 66 is constantly rotating at a predetermined speed of 3,600 rpm. Analog switch 1) 0 is in the connection state shown in the figure (
At contact b, contact d). Therefore, if a video signal is recorded on the magnetic disk 60, the video is transmitted to the reproduction amplifier 1.
) 2.1) 4 and the reproduction circuit 83 to the video monitor device 84 .

The user operates the forward/end transfer key on the operation unit 104 to place the magnetic head 61 at the two empty trunk positions of the magnetic disk 60. This is done by the control circuit 12° controlling the motor drive circuit 58 in response to the head transfer key, and whether the two trunks are unrecorded or not.
This is performed by the control circuit 12 detecting the reproduction output of the magnetic head 61 via the envelope detector 86.

When the magnetic head 61 is placed on the empty track, the operator operates the recording key on the operation unit 104.

As a result, first, the composite synchronization signal C5ync and the luminance signal Y output from the decoder IO are FM-modulated by the FM modulator 24, and then the FM luminance signal output from the FM modulator 24 is processed by the high-pass filter 32 and the frequency characteristic correction circuit. The signal is inputted to the mixing circuit 34 via 37. Further, the chroma signal C1, that is, the color difference signal R- output from the decoder 10
After Y and B-Y are converted into line-sequential color difference signals by the analog switch 1), they are FM-modulated by the FM modulator 38. The FM line sequential color difference signal outputted from the FM modulator 38 is input to the mixing circuit 34 via the low-pass filter 42 and the frequency characteristic correction circuit 43, where it is mixed with the FMg degree signal.

In accordance with this, the control circuit 12 outputs a control signal 96 to switch the analog switch 52 from the phase synchronization signal PC to the contact point a and the contact point C, which are opposite to those shown in the figure, for an IV period.

Therefore, the recording FM video signal output from the mixing circuit 34 is sent to the recording amplifiers 106 and 108 and the analog switch 1.
) 0 to the magnetic head 61, and the F-field video signal is recorded on two tracks of the magnetic disk 60 as a frame signal. The reproduction output of the magnetic head 61 is output from the restored analog switch 1) 0 (contact b, contact d
) and reproduction amplifiers 1) 2, 1) 4, and are visualized on the video monitor device 84, thereby allowing the recording state of the track to be confirmed. Then, while such operations are repeated, frame video signals are sequentially recorded on the empty trunk of the magnetic disk 60.

For example, if it is desired to erase all of the video signals recorded on the magnetic disk 60 in this manner, the all-track erase key on the operation unit 104 is operated. In response to this, the control circuit performs tracking fa control, and the first
For example, the magnetic head 61A is placed on the center of the track 1Vh-1, and the second magnetic head 61B is placed on the track lbo.
They are placed over the center of the trunk. Next, the control circuit 12 first outputs a control signal 96 to switch the analog switch 1) 0 to contact a and contact C, and further outputs a control signal 95 to switch the analog switch 1) 0 to contact a and contact C.
is controlled to be in the OFF state so that the FM line sequential color difference signal is not input to the mixing circuit 34. Then, an erase signal 90, an output permission signal 91, and a control signal 93 are outputted from the control circuit 12 to the FM modulator 24, and the base terminal 94 of the transistor Q7 of the integrated circuit drive circuit 202 of the FM modulator 24 is connected to the sixth As shown in the figure, at time t.

The erase drive signal 92 is output in a period T1 from time t1. As a result, integrated circuit 200 of FM modulator 24
An erase signal of approximately 7 MHz is output from the terminal 1) of the magnetic head 61, and the erase signal is supplied to the magnetic head 61 via the analog switch 1)0. In conjunction with this, the control circuit 12 supplies the motor drive circuit 58 with a step motor drive signal 57 that outputs, for example, 1,040 drive pulses for sequential feeding of 600 PPS. Motor drive circuit 58
receives this step motor drive signal 57, controls the step motor 65, and as shown in FIG. During one rotation of the magnetic disk 60, the magnetic head 61A is moved from the position 161A to the position 161B on the inner circumference side by about 30 μm.
Transport it over a distance of m. At the same time, the other second magnetic head 61B of the magnetic head 61 disposed at the center of the recording track 62A of track 1) kLO is rotated once while the magnetic disk 60 rotates from the position 162A. It is transferred approximately 30 μm to the position indicated by reference numeral 162B on the inner circumferential side. As a result, the magnetic head 61
is transferred by about 60 μm during two rotations of the magnetic disk 60, and an erase signal of about 7 MHz is spirally recorded in the area of the recording track 62A and guide band 62B of the two tracks. Hereinafter, the first magnetic head 61A of the magnetic head 61 is moved by the step motor 65 to the recording track 62A of the track 62A on the inner track side 51.
The second magnetic head 61B is moved to the center position 61C, and the second magnetic head 61B is moved to the center position 162C of the recording track 62A of track l1h52. In this way, the step motor 65 causes the first magnetic head 61A of the magnetic head 61 to move the recording tracks from the track floor -1 to the trunk floor 51, and the second magnetic head 61B to move the recording tracks from the track 1) to the track 52, respectively. Approximately 5,20 to the center position of 62A
While being transferred over a distance L2 of 0 μm in approximately 1.73 seconds,
During this time, an erasure signal is recorded in a spiral manner. That is, the erase signal drive signal 92 is sent from the control circuit 12 to the base terminal 94 of the transistor Q7 of the FM modulator 24 for a period T1 of about 1.73 seconds while the magnetic head 6e is being moved on the track.
is output.

Next, the control circuit 12 outputs the erase drive signal 92 to the base terminal 96 of the transistor Q8 of the integrated circuit drive circuit 202 during a period T2 from time t1 to time t2. As a result, an approximately 10.5 MHz erasing signal is output from the terminal 1) of the integrated circuit 200 of the FM modulator 24, and the erasing signal is supplied to the magnetic head 61 via the analog switch 1)0. In addition, in accordance with this, the control circuit 12 sends a motor drive circuit 58 to the motor drive circuit 58 for transferring the magnetic head 61 to the original position of the track fish-1, 0, for example, 1, 2.
A step motor drive signal 57 is supplied that outputs only 1,040 drive pulses for reverse feeding of 00PPS. The motor drive circuit 58 receives this step motor drive signal 57 and controls the step motor 65, and while the magnetic disk 60 rotates once, the motor drive circuit 58 controls the step motor 65 to drive the first magnetic head of the magnetic head 61 disposed at the center of the trunk of the track space 51 while the magnetic disk 60 rotates once. rad 6
The second magnetic heads 61B disposed in the tracks 1A and 52 are each moved about 60 μm toward the outer periphery. As a result, the magnetic head 61 is moved by the step motor 6.
5, the magnetic disk 60 rotates approximately 12 times during two rotations.
The erase signal of about 10.5 MHz is recorded in a spiral pattern on the track 51, 52 and the outer track. Hereinafter, the motor drive circuit 58 is a step motor 65.
control the magnetic field 61, track depth 51.52
The distance L2 from the truck 1 to the original position of the truck 0-1,0 is transferred in about 0.87 seconds, and
During this time, an erasure signal is recorded in a spiral manner. That is, the erase drive signal 92 is output from the control circuit 12 to the base terminal 96 of the transistor Q8 of the FM modulator 24 for a period T2 of approximately 0.87 seconds during which the magnetic head 61 is being moved on the track.

Then, the control circuit 12 operates during a period T from time t2 to time t3.
3, the transistor Q of the integrated circuit drive circuit 202
An erase drive signal 92 is outputted to a base terminal 98 of 9. As a result, an approximately 14 MHz erase signal is output from the terminal 1) of the integrated circuit 200 of the FM modulator 24, and the erase signal is supplied to the magnetic head 61 via the analog switch 1)0. Further, in accordance with this, the control circuit 12 supplies the motor drive circuit 58 with a step motor drive signal 57 that causes the motor drive circuit 58 to output, for example, 1.040 drive pulses for sequential feeding of 1,200 PPS. The motor drive circuit 58 receives this step motor drive signal 57, controls the step motor 65, and moves the magnetic head 61 by about 60 μm during one rotation of the magnetic disk 60, as described above, while moving the magnetic head 61 to the track position -1,0. Truck to truck disease 51.52
The erase signal is moved over the track in about 0.87 seconds, and an erase signal is recorded in a spiral shape during that time. That is, control circuit 1
2 to the base terminal 98 of the transistor Q9 of the FM modulator 24, an erase drive signal 92 is output for a period T3 of approximately 0.87 seconds during which the magnetic head 56 is being moved on the track.

Furthermore, the control circuit 12 controls the 1-transistor QI of the integrated circuit drive circuit 202 during a period T4 from time t3 to time t4.
An erase drive signal 92 is output to the base terminal 100 of the transistor O.

As a result, terminal 1) of the integrated circuit 200 of the FM modulator 24
An erase signal of approximately 20 MHz is output from the magnetic head 61 via the analog switch 1)0.
In addition, in accordance with this, the control circuit 12 supplies a step motor drive signal 57 to the motor drive circuit 5, which outputs, for example, 1.040 drive pulses for reverse feeding of 1,200 PPS. . Motor drive circuit 5
8 receives this step motor drive signal 57 and controls the step motor 65 to move the magnetic head 61 to the track floor 5.
The distance L2 from 1.52 to the original position of the trunk at trunk depth -1,0 is transferred in about 0.87 seconds, and an erasure signal is recorded in a spiral shape during that time. ffp, the erase drive signal 92 is output from the control circuit 12 to the base terminal 100 of the transistor QIO of the FM modulator 24 for a period T4 of about 0.87 seconds while the magnetic head 61 is being transported on the trunk. .

As described above, in the magnetic recording/erasing circuit of this embodiment, the FM data recorded on the 50 trunks of the magnetic disk
When erasing a video signal, first, during period TI, all trunks are erased using an erasing signal with a frequency (first frequency) higher than the lowest frequency FM chroma signal and with a current value larger than the optimum recording current value of the magnetic head. FM chroma signal about 1
．． It is erased for 73 seconds, and then further erased from period T2 to period T.
4, the frequency was increased in three steps and the FM brightness signal of all trunks was erased for about 0.87 seconds each time, so it was about 4.3
Fifty tracks can be erased in just seconds.

In this way, the first frequency of erasure (i) is set near the upper limit of the frequency recordable by the magnetic head, and is set higher than the signal with the lowest frequency among the multiple signals to be erased. By doing so, the erasing time is shortened.

In addition, in this embodiment, in the range from the first frequency (approximately 7 MHz) to the second frequency (approximately 20 MHz), the current value of the erase signal 1 is set higher than the optimal recording current value of the magnetic head. However, the present invention is not limited to this, and the current value of only the erasing signal at least at the first frequency may be set to be high.

Furthermore, erasure (start and end position of recording of item g,
By setting a video signal representing a still image on a track where it is not recorded, the video signal is not affected by damage caused by, for example, the stamping of a still image head.

In this embodiment, a circuit for generating an erasure signal is provided in the FM modulator 24 for the luminance signal. In this case, there is an advantage that the frequency oscillation circuit can be used for FM modulating the luminance signal, but the frequency oscillation circuit is not necessarily limited to this, and may be provided in the FM modulator 38 for color difference signals, for example. Furthermore, an oscillation circuit separate from these FM modulators may be provided.
Using an FM modulator has the advantage that the circuit configuration does not become complicated.

〔Effect of the invention〕

As explained above, in the magnetic recording erasing circuit according to the present invention, when erasing a recorded signal, the frequency of the erasing signal outputted from the erasing signal generating means is changed stepwise, and the current value of the erasing signal is changed in the recording means. The recording current value is set to be larger than the optimum recording current value of the magnetic head, and at each stage of the gradual change in the frequency of the erase signal, an erase signal of a constant frequency is supplied to the magnetic head of the recording means, and the magnetic head is set to the magnetic head of the magnetic disk. Since the recording means and the erasing signal generating means are controlled so as to record on all trunks each time while moving in the longitudinal direction, the signal recorded on the entire magnetic recording medium can be re-recorded. It is possible to erase everything effectively and in a short time.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of a magnetic recording/reproducing device to which the present invention is applied, Fig. 2 is a characteristic diagram showing an example of the frequency spectrum of a video signal, and Fig. 3 is a step motor drive pulse and excitation pattern. Figure 4 is a frequency characteristic diagram showing the reproduction characteristics of the magnetic head. Figure 5 is a diagram showing the track arrangement and home position of the magnetic disk. Figure 6 is the brightness shown in Figure 1. A circuit diagram showing the specific configuration of the FM modulator for signals, FIG. 7 is an explanatory diagram of the erasure signal output from the FM modulator for luminance signals shown in FIG. 6, and FIG. 8 is a diagram showing the magnetic head transfer. FIG. 9 is a block diagram showing the overall configuration of another embodiment of a magnetic recording/reproducing apparatus to which the present invention is applied, and FIG. 10 is an explanatory diagram regarding the movement of the magnetic head. 12... Control circuit, 24.38... FM modulator, 5
6... Magnetic head, 60... Magnetic disk, 104
. . . Operation unit, 200 . . . Oscillator, 202 . . . Integrated circuit drive circuit.

Claims (7)

[Claims] (1) In a magnetic recording erasing circuit that erases tracks of a magnetic recording medium on which a plurality of frequency-multiplexed signals are recorded, recording is performed in which the magnetic recording medium is rotationally driven and a signal is recorded on each track of the magnetic recording medium. and a first frequency that is lower than the upper limit of the recording frequency band of the magnetic head of the recording means and higher than the center frequency of a signal with a lower frequency among the plurality of signals, and lower than the upper limit of the recording frequency band of the recording means. an erasing signal generating means that generates an erasing signal whose frequency is varied in a frequency range up to a second frequency, and supplies the erasing signal to a magnetic head; and a magnetic head when recording a current value of the erasing signal at least at the first frequency. current setting means for setting the current value to be larger than the optimum recording current value of the recording current; and changing the frequency of the erasing signal outputted from the erasing signal generating means in stages when erasing the recorded signal; The recording current value is set higher than the optimum recording current value of the magnetic head in the recording means, and an erasing signal of a constant frequency is supplied to the magnetic head of the recording means at each stage of a stepwise change in the frequency of the erasing signal. The present invention is characterized by comprising a recording means for recording over all tracks each time while moving the head in the radial direction of the magnetic recording medium, and a control means for controlling the erase signal generating means and the current setting means. A magnetic recording erasing circuit. (2) Among the plurality of signals, the signal with a low frequency is a chroma signal of a video signal, and the high frequency signal is a luminance signal of a video signal.
) The magnetic recording erasing circuit described in item 2. (3) The magnetic recording/erasing circuit according to claim (1), wherein the first frequency of the erasing signal is close to an upper limit of a frequency recordable by a magnetic head. (4) The magnetic recording erasing circuit according to claim 1, wherein the first frequency of the erasing signal is selected approximately within the modulation frequency range of the luminance signal. (5) The magnetic recording/erasing circuit according to claim (1), wherein the current value of the erasing signal at the first frequency is at least 1.2 times the optimum recording current value. (6) The magnetic recording/erasing circuit according to claim (2), wherein the chroma signal is recorded with a voltage lowered by about 20 dB with respect to the luminance signal during recording. (7) The chroma signal has a band of approximately 0 to 2.5 MHz, the luminance signal has a band of approximately 2.5 to 12 MHz, and the first frequency has a band of approximately 6 to 7.
5MHz range, and said second frequency is 20MHz.
The magnetic recording erasing circuit according to claim 2, characterized in that the magnetic recording erasing circuit is selected to be equal to or larger than z.