JPS6083202A - Erasing device for magnetic recording information - Google Patents

Abstract

PURPOSE:To erase not only high frequency record, but also low frequency record easily and efficiently by supplying an erasing current to a magnetic head while increasing the frequency gradually. CONSTITUTION:When a magnetic head 10 is positioned on a track on a disk 1 to be erased in erasure mode selection, a switch 11 is placed at a side 11b, a switch 12 is set at a side 12b, and a switch 13 is connected to a side 13a. A voltage generating circuit 20 is operated in this state to generate a voltage shown by a straight line A, i.e. voltage which increases linearly from Vs to Ve in a time T (1.66sec) when the disk 1 makes 100 turns. Then, a voltage-frequency converter 21 generates a rectangular wave which varies in frequency from (fs) (e.g. 2MHz) to (fe) (e.g. 20MHz) according to the generated voltage. At this time, an analog gate 15 is on for said period T. Consequently, record on a specific track on the disk 1 is erased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in a magnetic recording information erasing device for erasing information recorded on a magnetic recording medium of a magnetic recording/reproducing device used in an electronic camera or the like.

[Prior art]

As the erasing means in conventional magnetic recording information erasing devices of this type, the high frequency erasing method has been most often used. This high-frequency erasing method demagnetizes and erases recorded information on a magnetized magnetic recording medium by supplying a high-frequency current with a constant frequency of about five times the maximum recording frequency to a magnetic head dedicated to erasing. It is a means.

However, the above-mentioned high frequency erasing method is effective for high frequency recorded information recorded in a region where the depth in the thickness direction of the magnetic recording medium involved in recording is relatively shallow. but,
Low-frequency recorded information that is recorded even in a relatively deep region in the thickness direction of a magnetic recording medium is difficult to erase using the above-mentioned high-frequency erasing method because the high-frequency component reaches only a shallow part of the magnetic material. be. Particularly in recent years, as efforts have been made to improve the coercive force of magnetic recording media, the above erasing has become increasingly difficult. Therefore, in order to erase low frequency recorded information, it was necessary to design an erase head exclusively for low frequencies and to supply a large erase current to the head.

By the way, in those that use magnetic tape as a magnetic recording medium, an erasing head is usually provided separately from the recording/reproducing head to perform erasing and then re-recording. In those using a recording medium (hereinafter referred to as a disk), direct override is performed. The reason for this is that digital recording is the mainstream for discs, and in the case of digital recording, there is little signal deterioration even with direct overriding. However, when recording analog signals on a disk, an erasing head is required as in the case of the magnetic tape. However, in the case of a disk, unlike in the case of a magnetic tape, it is necessary to move the magnetic head in a direction perpendicular to the recording track, so if an erase head is provided, the erase head must be ranked to 1 along with the recording/reproducing head. However, the configuration becomes extremely complicated.

〔the purpose〕

An object of the present invention is to provide a head information erasing device which can easily and efficiently erase not only high frequency recorded information but also low frequency recorded information, and which erases recording/reproducing heads.

〔overview〕

In order to achieve the above object, the present invention is characterized by the following configuration. Of course, the signals recorded on the magnetic recording medium driven by the recording medium drive motor are
The present invention is characterized in that erasing is performed by supplying an erasing current to the magnetic head while gradually increasing the frequency of the erasing current supplied to the magnetic head.

〔Example〕

FIG. 1 is a diagram showing a circuit configuration of an embodiment in which the present invention is applied to an electronic still camera. 1 in the figure is a disk,
The rotating shaft 3 of the disk drive motor 2 is loaded. The rotation of the disk drive motor 2 is controlled as follows. That is, the rotation pulse S detected by the rotation pulse detector 4
1 is an FM modulation circuit 6 in the motor rotation servo circuit 5.
The phase is compared with the vertical synchronization signal @S2 separated and extracted from.

The motor supply current supplied from the power supply 7 is controlled by the output signal from the 1c motor rotation servo circuit 5 in accordance with the phase difference, and this controlled current is applied to the power switch 8.
It is supplied to the motor 2 via a motor power amplifier 9. As a result, the rotational speed and phase of motor 2 become synchronized with vertical synchronization signal $2.

The magnetic head 10 performs recording, reproducing and erasing on the disk 1 which is rotationally driven by the motor 2 which is servoed in this manner as described below.

When the recording mode is selected, the switch 11 is connected to the 11a side, the switch 12 is connected to the 12a side, and the switch 13 is connected to the 13a side. As a result, the video signal input terminal 14
The video signal S3 input from
Modulated. Then, the FM modulated signal is transmitted to the analog gate 1 in which only the disk-rotation period valve is turned ON by the gate opening/closing signal s4 generated from the motor rotation servo circuit 5.
5, the signal is amplified by a recording amplifier 16, and then the disk 1 is rotated by a magnetic head 10.
recorded in

In the reproduction mode selection poem, the switch 13 is connected to the 13b side. Therefore, the signal reproduced by the magnetic head 10 is supplied to the FM demodulation circuit 18 via the reproduction amplifier 17, demodulated by the FM demodulation circuit 18 into a video signal S3, and then outputted from the video signal output terminal 19. be done.

When selecting the erase mode, the switch 11 is turned to the 11b side while the magnetic head 1o is positioned on the track to be erased on the disk 1.

The switch 12 is connected to the 12b side, and the switch 13 is connected to the 13a side. When the voltage generating circuit 20 is operated in this state, the voltage as shown by the straight line A in FIG.
sec), a voltage is generated that increases linearly from Vs to Ve. Then, according to this voltage, the voltage-frequency converter 21 outputs a frequency of fs (for example, 2 MHz).
A rectangular wave that changes from 1 to 20 MHz is generated. At this time, the analog gate 15 is in the ON state only for the period (3) described above. As a result, the frequency output from the voltage-frequency converter 21 changes. The rectangular wave passes through the analog gate 15, is amplified by the amplifier 16, and then is supplied to the magnetic head 10. As a result, the recording on a predetermined track of the disk 1 is erased.

In this manner, according to the present device, erasing is performed while gradually increasing the frequency of the erasing current during erasing, so that a relatively low frequency erasing current is supplied to the magnetic head 10 at the beginning of erasing. Therefore, the low frequency recorded information recorded in the deep region of the disk 1 in the thickness direction is erased. Since the frequency of the erasing current gradually increases with the passage of time, high-frequency recorded information recorded in the shallow depth region of the disk 1 in the thickness direction is also erased.

Note that the present invention is not limited to the above-described embodiment. For example, in the embodiment described above, the voltage generated from the voltage generating circuit 20 was a voltage that increased continuously as shown in FIG. 2(a), but it was a voltage that increased stepwise as shown in FIG. 2(b). There may be. At this time, the output of the voltage-frequency converter 21 becomes a rectangular We wave whose frequency increases stepwise.

Here, T1 in FIG. 2(b). T2. It is desirable to select the time T3 to be an integral multiple of the time required for one rotation of the disk 1. That is, by doing this, the time control of voltage conversion, etc. in the voltage-frequency converter 20) can be performed using the same clock as the motor rotation, etc., which simplifies the configuration, and also makes it possible to stop the erasing operation in the middle of a track. Since it is X, it is possible to perform more precise erasing and the erasing characteristics are improved.

Also, the frequency f1 of the erase current selected in FIG. 2(b). f2. f3. -fn should not be mutual v) t: An integer multiple relationship. This is because the tree method performs erasing by increasing the frequency of the erasing current stepwise from low frequency to high frequency and overwriting it. This is because a mismatch in either case is a necessary condition for not leaving a specific frequency component on the disc. From this point, even when the voltage is changed continuously as shown in Figure 2 (a), the increase is non-linear as shown in curve B of Figure 2 (a) rather than linear increase as shown in straight line A. It would be better to let them do so. Such a voltage change can be easily achieved by using the charging characteristics of a capacitor.

FIG. 3 is a diagram showing a circuit configuration of another embodiment of the present invention. The difference between this embodiment and the previous embodiment is that, in the previous embodiment, the output of the voltage generation circuit 20 was input to the voltage-frequency converter 21 during erasing to obtain an erase current whose frequency changes. By inputting the output of the voltage generation circuit 20 to the FM modulation circuit 6, an erasing current whose frequency changes according to the output of the voltage generation circuit 20 is obtained. According to this embodiment, the voltage-frequency converter 21
This has the advantage of simplifying the configuration.

3 is the same as that in FIG. 1 other than the above, so the same parts are given the same reference numerals and the explanation will be omitted.

〔Effect of the invention〕

According to the present invention, an erasing current is supplied to the magnetic head while gradually increasing the frequency of the erasing current supplied to the magnetic head, while gradually increasing the frequency of the erasing current supplied to the magnetic head. Since erasing is carried out using the method, it is possible to easily and efficiently erase not only high-frequency records but also low-frequency records, and furthermore, it is possible to provide a magnetic recording information erasing device with a simple configuration in which the recording/reproducing head can be used as an erasing head. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing a circuit configuration of an embodiment in which the present invention is applied to an electronic still camera, FIG. 2(a) is an explanatory diagram of the operation of FIG. 1, and FIG. 2(b) is a modification of the above embodiment. FIG. 3 is a diagram showing the circuit configuration of another embodiment of the present invention. 1... Disk, 2... Disk drive motor, 4...
... Rotating pulse detector, 10... Magnetic head, 15.
...Analog gate. Applicant's agent Patent attorney Atsushi Tsuboi

Claims (2)

[Claims] (1) A magnetic recording medium, a motor that drives the magnetic recording medium, a magnetic head driven by the motor that erases information recorded on the magnetic recording medium, and an erasing current supplied to the magnetic head. 1. A magnetically recorded information erasing device comprising means for gradually increasing the frequency of the magnetic recording information. (2) The magnetically recorded information erasing device according to claim (1), wherein the magnetic head also serves as a recording/reproducing head.