JPS62188004A - Magnetic disk erasing device - Google Patents

Abstract

PURPOSE:To erase information by simple constitution without any residual magnetism by providing a disk rotating mechanism and an AC generator which rotates according to the rotation of a disk to a magnetic disk erasing device which employs an AC magnetic erasure system and exciting an erasing head with an alternating current generated by the generator. CONSTITUTION:A magnetic disk 15 is put in a disk jacket 14 and a center core 16 and a center core bearing 13 which is attracted by a magnet, etc., are made to penetrate them; and a disk driving shaft 12 is fitted to the bearing 13 which projects downward and the 1st gear 11 for rotating the disk 15 is fitted to the disk driving shaft 12. Then, the 2nd gear 19 is engaged with the gear 11, the AC gear 20 is provided thereto, and a wrong erasure preventive switch 21, an extension part 21a, and a wrong erasure preventive claw 23 are provided thereto. The jacket 14, on the other hand, is provided with the AC demagnetization type magnetic erasing head 18 which faces a pressure pad 17 is provided to the jacket 14 and is allowed to move in tracking directions A and B. Then, the disk 15 and generator 20 are rotated in synchronism with each other to excite the head 18 through a signal line 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk erasing device, and more specifically,
A magnetic disk erasing device using an AC demagnetization method is used.

(Prior Art) Magnetic disks are used in various fields because of their simplicity and portability. For example, 8-inch and 5-inch magnetic disks (also called floppy disks) are
It is widely used as a storage device in personal computers, word processors, etc. A magnetic disk is a storage device in which information can be written and read, and its recording method has conventionally been saturation recording. For this reason, independent erasing heads are not used, but are attached to both sides of the recording/reproducing head, and are used to narrow the recording width.

This may be sufficient in the case of recording/reproducing digital data of 0 and 1. However, in the case of 2-inch magnetic disks used in electronic still cameras and the like, video and audio signals are recorded in analog format rather than digital data. Therefore, when re-recording image signals, beautiful images cannot be obtained unless the previously recorded signals are completely erased.

Therefore, various attempts have been made to completely demagnetize a 2-inch magnetic disk.

Another method of erasing recorded information all at once is to insert the information recording medium with its jacket into a case that generates a strong alternating current magnetic field. This method is used to erase video cassettes and audio cassettes all at once, but it requires a fairly large-scale device.

FIG. 5 is a diagram showing a conventional example of a magnetic disk erasing device, and shows an example of the configuration of an erasing head section (Japanese Patent Laid-Open No. 59-1
10007). Two sets of excitation coils as shown in the figure are wound around the erasing head 1, and a pad 3 presses against the magnetic disk 2 from above to bring the erasing head 1 into contact with the information recording surface of the magnetic disk 2. There is. In this state, alternating current signals as shown in FIGS. 6(a) and 6(b) are applied to the erasing head 1 to erase information.

FIG. 6(a) shows a sine wave alternating current, and FIG. 6(b) shows a rectangular wave alternating current. In both cases, alternating current with a constant amplitude is applied during the period T1, and the amplitude is gradually reduced during the subsequent period T2 so that no residual magnetism remains.

(Problems to be Solved by the Invention) In the case of the conventional AC demagnetization method, an AC signal generation circuit that generates AC is required as described above, and therefore a power supply for driving the circuit is required. Moreover, since it is necessary to gradually attenuate the amplitude of the AC signal, a complicated control circuit is required.

The present invention has been made in view of these points, and
The purpose is, first, to realize a magnetic disk erasing device that can erase information without an external power source, and second, to realize a magnetic disk erasing device that can erase information with a simple configuration and without leaving any residual magnetism. There is a particular thing.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, provides a magnetic disk erasing device using an AC degaussing method, which includes a rotation mechanism that rotates a magnetic disk, and a rotation mechanism that rotates as the magnetic disk rotates. The present invention is characterized in that the erasing head is configured to include an alternating current generator, and to excite the erasing head by the alternating current generated by the alternating current generator.

(Function) The present invention includes a rotation mechanism that rotates a magnetic disk and an AC generator 1Rm that rotates as the magnetic disk rotates.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of main parts showing an embodiment of the present invention. Only the magnetic disk jacket portion is shown in cross section. In the figure, 11 is a first gear that rotates the magnetic disk;
12 is a disk drive shaft attached to the rotation center of the first gear 11; 13 is a UI at the other end of the disk drive shaft 12;
This is the center core receiver installed in A. 14 is a magnetic disk jacket, 15 is a magnetic disk built in the magnetic disk jacket 14, and 16 is a center core of the magnetic disk 15. The center core receiver 13 and the center core 16 are fitted together, for example, by the attractive force of a magnet, so that rotational force is transmitted thereto.

Reference numeral 17 represents a pad that presses the magnetic disk 15, and reference numeral 18 represents an AC demagnetization type erasing head that comes into contact with the information recording surface of the magnetic disk 15. The erasing head 18 has a transfer #J (not shown).
The mechanism allows movement in the tracking direction (direction of arrow A-8 in the figure). 19 is a second gear meshing with the first tooth 1111; 20 is the second gear 19;
It is an alternator that is rotated by. The alternating current voltage generated by the alternating current generator 20 is applied to the erasing head 18 via an erroneous erasing prevention switch 21 and a signal line 22. Reference numeral 23 denotes an erroneous erasure prevention claw formed on the magnetic disk jacket 14. The operation of the device configured as described above will be explained as follows.

In the state shown in the figure, when the disk drive shaft 12 attached to the center core 16 is rotated in the direction of the arrow, the rotational force is generated as an alternating current via the first gear 11 → second gear 19. I!
The AC power is transmitted to the generator 20, and the AC power generator 20 starts generating electricity.

When the accidental erasure prevention claw 23 is not removed, the extendable portion 21a of the accidental erasure prevention switch 21 is pressed by the accidental erasure prevention claw 23, and the contact switch is in the A-on position. Therefore, the output (alternating current voltage) of the alternator 20 is applied to the erasing head 18 via the signal line 22. The erasing head 18 generates an alternating current magnetic field according to the applied alternating current, and erases the recorded information on the track in contact with the magnetic disk 15.

FIG. 2 is a diagram showing an example of the configuration of the electric circuit section.

Components that are the same as those in FIG. 1 are indicated with the same It@.

The erasing head 18 includes an excitation winding 18a, and an excitation winding 18a.
A gap 180 is provided at the tip of the core 18b to avoid one turn shot. When the mW erasure prevention claw 23 (see FIG. 1) on the magnetic disk jacket is not removed, the contact of the accidental erasure prevention switch 21 is engaged.

Therefore, the excitation winding 18a is excited by the output of the AC generator 20, and the erasing head 18 generates an AC magnetic field for erasing information. On the other hand, the accidental erasure prevention claw 23 of the magnetic disk jacket
is removed, the extendable portion 21a (see FIG. 1) of the accidental erasure prevention switch 21 has fully extended upward, and the contact is not pressed and is turned off. Therefore, even if an alternating voltage is generated in the alternator 20, the excitation winding 18
a is never excited.

In the above-described erasing operation, while the magnetic disk 15 is being rotated and a signal sufficient for erasing information is being sent to the erasing head 18, once the magnetic disk 15 has rotated once or more, the rotation is gradually lowered. As a result, the amplitude of the alternating current generated by the alternating current generator 20 gradually decreases, and the same effect as the erasing operation described with reference to FIGS. 5 and 6 can be obtained, and complete information erasure without residual magnetism can be achieved.

In the above description, no particular mention was made of the rotation mechanism for rotating the magnetic disk 15, but it may be possible to rotate the magnetic disk 15 by hand, for example. In addition, any rotation mechanism that can rotate the magnetic disk may be used. Further, in the above description, a track erasing type head is used as the erasing head 18, but it is also possible to erase all tracks simultaneously. For example, if the erasing head shown in FIG. 3 has an erasing width W larger than the entire track range, it is possible to erase all the tracks at once.

Further, in the above description, an example was given in which the erasing head is provided independently, but it can also be used as a recording/reproducing head. Furthermore, the connection, arrangement, and reduction ratio between the disk drive shaft 12 and the alternating current generator 20 are not limited to the example shown in FIG. The settings and arrangement can be made in consideration of the number of poles of the machine, the setting of the erasure frequency, etc.

According to the present invention, since the rotation of the magnetic disk 15 and the rotation of the alternator 20 are synchronized, the erasing wavelength on the same circumference of the magnetic disk 15 is constant regardless of the rotation speed. Therefore, the rotation control of the drive of the magnetic disk 15 is as follows.
There is no need to strictly control during normal recording/reproduction. Due to this, it is conceivable to erase manually (by turning by hand).

Adopting the hand-cranking method has the advantage that information can be erased without the need for power.

FIG. 4 is a block diagram showing another embodiment of the present invention. In the figure, 30 is a chassis, 31 is a magnetic disk holder into which a magnetic disk jacket is inserted, and 32 is a lid.

The magnetic disk holders 31 and M32 are arranged as shown by the arrow A-A in the figure.
It is configured to be rotatable in the ' direction. 33 is ff132
A hand-cranked rotating handle attached to the side; 34 a center core presser that rotates while pressing a magnetic disk center core (not shown); 35 a pressing force for pressing the center core presser 34; The pressure spring 36 is a pad that presses the mounted magnetic disk.

37 is a window provided on the lower surface of the magnetic disk holder 31;
Reference numeral 38 denotes an accidental erasure prevention claw detection window provided on the same surface.

39 is a center core receiver, 40 is the center core receiver 3
A first gear 41 rotates coaxially with the first gear 4.
42 is a third gear that rotates coaxially with the second gear 41, and 43 is a fourth gear that meshes with the third gear 42. 44 is an alternator with a fourth gear 43 attached to its rotating shaft; 45 is an accidental erasure prevention claw 38;
An accidental erasure prevention switch installed in a position corresponding to 4.
Reference numeral 5a denotes an extendable portion thereof, and 46 an erase head to which alternating current voltage sent from an alternating current generator 44 is applied via an accidental erase prevention switch 45.

The erasing head 46 uses an all-track erasing type head in which the gap 46a is well defined as shown in the figure. Reference numeral 47 denotes a wiring connecting the erroneous erasure prevention switch 45° alternating current generator 44 and the erasing head 46. The operation of the device configured as described above will be explained as follows.

First, a magnetic disk jacket (not shown) is attached to the magnetic disk holder 31, and then the lid 32 is closed. As a result, one end of the center core of the magnetic disk is fitted into the center core receiver 39 by the attractive force of a magnet, and the other end of the center core is fitted into the center core presser 34. As a result, when the rotation handle 33 is turned, the first gear 40 also rotates together with the magnetic disk. on the other hand,
When the lid 32 is closed, the pad 36 presses against a magnetic disk (not shown), and its information recording surface comes into contact with the erasing head 46.

*If the accidental erasure prevention claw of the magnetic disk jacket that has been erased is not removed, the accidental erasure prevention claw pushes the extension/contraction part 45a of the accidental erasure prevention switch 45, turning on the contact. Therefore, in this state, if the magnetic disk is rotated one or more times by manually turning the rotary handle 33, the recorded information will be completely erased. Furthermore, in order not to leave any residual magnetism, the rotary handle 33 may be turned gradually and slowly, and finally the magnetic disk jacket may be removed.

If the accidental erasure prevention claw of the attached magnetic disk jacket had been removed, the contact point would be off because the extendable portion 45a of the accidental erasure prevention switch 45 would not be pressed. Therefore, since no AC voltage is applied to the erasing head 46,
Information is not erased even if the magnetic disk is rotated.

In the above description, the gap 46 is used as the erase head 46.
Although an all-track erasing type with a longer a is shown, an erasing head with a narrow gap that can erase only a specific track and a tracking mechanism that moves the erasing head in one racking direction may also be used.

In the embodiment shown in FIG. 4, in order to stabilize the rotation and slowly decelerate it, a flywheel should be attached to any of the gear trains 40 to 43, or a rotor with a large rotational moment should be attached to the rotor of the AC generator Ml 144. Just use it. Furthermore, in the above-described embodiment, operability can be improved by adding a mechanism (for example, a low current consumption type LED indicator) to indicate that the rotation of the magnetic disk has reached an erasable frequency.

(Effects of the Invention) As described in detail above, according to the present invention, by providing a rotation mechanism that rotates a magnetic disk and an alternator that rotates with the rotation of the magnetic disk, there is no need for an external power source. Accordingly, it is possible to realize a magnetic disk erasing device that can erase information using an AC demagnetization method. Further, according to the present invention, information can be erased without leaving residual magnetism by operating the rotating mechanism to rotate gradually and slowly.

Other advantages include that it can be realized at low cost, and is compact and convenient to carry. Also, since it is equipped with an erroneous erasure prevention mechanism, there is no possibility of erroneous erasure.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main part of an embodiment of the present invention, FIG. 2 is a diagram showing an example of the configuration of an electric circuit, FIG. 3 is an outline diagram of the erasing head, and FIG. FIG. 5 is a diagram showing a conventional AC demagnetization method, and FIG. 6 is a diagram showing an AC voltage waveform applied to the erasing head. 1.18.46...Erasing head 2.15...Magnetic disk 3.17.36...Pad 11.20.40-43...Gear 12...Drive shaft 13.39... Center core receiver 14... Magnetic disk jacket 16... Center core 20.44... Alternator 21.45... Erase prevention switch 21a, 45a... Telescopic part 22.47... Signal a 23... Accidental erasure prevention claw 3
0... Chassis 31... Magnetic disk holder 32... Lid 33... Rotating handle 34
... Center core presser 35 ... Pressure spring 37 ... Window 38 ... Erroneous erasure prevention claw detection window 46a ... Gap patent applicant Roku Konishi Photo Industry Co., Ltd. Representative Patent attorney Fuji Ijima Extraterritorial 1 person Figure 11.19 i Gear 17;
Pad 1bj center core 23i
Erroneous erasure prevention turtle Figure 2 Figure 3 Figure 5 Figure 6 (A) (B)

Claims (1)

[Claims] In a magnetic disk erasing device using an AC degaussing method,
A magnetic disk comprising: a rotation mechanism that rotates a magnetic disk; and an alternator that rotates as the magnetic disk rotates; and an erase head is excited by alternating current generated by the alternator. erasing device.