JPH0644539A - Cassette type magnetic head demagnetizer - Google Patents

Abstract

PURPOSE:To provide a cassette type magnetic head demagnetizer capable of demagnetizing the magnetic zone of the magnetic head of a magnetic recording or reproducing device very efficiently by a rotary magnet using a permanent magnet. CONSTITUTION:A demagnetizing rotary magnet 12 constituted of the permanent magnet is incorporated in a cassette type case 1 and placed movably, back and forth so that the rotary magnet 12 is rotated in a direction opposed to that of a magnetic head 10 and made close to and away from the magnetic head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette type magnetic head degaussing device for degaussing the magnetic field of a magnetic head of a magnetic recording or reproducing apparatus.

[0002]

2. Description of the Related Art Generally, a magnetic head of a magnetic recording / reproducing apparatus is magnetized at the time of recording / reproducing, and the recording / reproducing characteristics are deteriorated by voice distortion, noise, etc., which makes it necessary to demagnetize the magnetic head.

Conventionally, a cassette type degaussing device for degaussing a magnetic head of this type uses an electromagnet wound with an exciting coil as a degaussing magnet, and the electromagnet is fixedly provided so as to face the magnetic head at regular intervals. The electromagnet is excited by an oscillating current from an oscillating circuit using an alkaline battery or the like as a power source, and an alternating magnetic field generated thereby is applied to the magnetic head to perform degaussing.

[0004]

In the above conventional cassette type degaussing device, a DC power source such as a battery is required to generate an alternating magnetic field in the electromagnet, and the power source voltage is inevitably lowered due to exhaustion of the battery. It has a drawback that it may not operate normally and the battery must be replaced.

Further, a large number of semiconductor elements forming an oscillation circuit, capacitors, resistors and the like must be incorporated, which causes a problem of high cost including production labor.

[0006]

In order to solve the above problems, the present invention rotates a degaussing magnet using a permanent magnet and approaches and separates the N and S magnetic poles while alternately facing the magnetic heads magnetized. Was periodically repeated to perform degaussing.

Further, according to the present invention, an eccentric rotary wheel is used as a drive source of the rotary magnet, and the rotary magnet is pressed against the eccentric rotary wheel by a spring so that the rotary magnet follows the eccentric amount of the eccentric rotary wheel to reciprocate. While rotating while moving,
A cam that slides on the shaft of the rotating magnet is provided on the inner surface of the cassette type case to guide the reciprocating motion.

In the present invention, the elastic force of the spring causes the rotating magnet to stand by at the position farthest from the magnetic head.

[0009]

According to the present invention, when the demagnetizing magnet is rotated, the N and S magnetic poles of the rotating magnet alternately face the magnetic head and apply an alternating magnetic field, while depending on the amount of eccentricity of the eccentric rotating wheel. The approach and separation of the rotating magnets are repeated periodically, thereby making the magnetic force applied to the magnetic head strong and weak and ideally demagnetizing the magnetic head.

Further, by using the eccentric rotating wheel as the drive source of the rotating magnet, the rotating magnet can be rotated and easily moved toward and away from the magnetic head (reciprocating motion) simultaneously and easily.

Further, the rotating magnet is reciprocally held by a spring so that the rotating magnet can be held by the holding force when the degaussing device is mounted on the magnetic recording / reproducing device or when the rotation of the reel shaft is stopped. Reverse magnetization from the rotating magnet to the magnetic head is prevented by making the magnetic head stand by at the farthest position from the magnetic head.

[0012]

Embodiments of the present invention will be described in detail below with reference to FIGS.

The cassette type magnetic head degaussing apparatus uses a cassette type case having the same shape as an existing standard cassette tape, and FIG. 1 is a plan view showing the internal structure of the cassette type case 1 with the upper lid removed.

Reference numerals 6 and 7 in the figure denote first and second rotating members, respectively, which are rotated by reel shafts 2 and 3 of a magnetic recording or reproducing device (not shown).
The second drive rotary wheel, and the first and second drive rotary wheels 6 and 7
Respectively have reel bearing holes 4 and 5 into which the reel shafts 2 and 3 are engaged, respectively, and the rotational driving of the reel shafts 2 and 3 is performed through the reel bearing holes 4 and 5 by the first and second drive rotating wheels. Transfer to 6 and 7.

Reference numeral 8 denotes a third drive rotating wheel which is rotated by the first and second drive rotating wheels 6 and 7, and the third drive rotating wheel 8 is the first and second drive rotating wheels 6 and 7 (reel shaft). It is arranged so as to engage with the first and second driving rotary wheels 6 and 7, respectively, on the intermediate line of 2 and 3), that is, on the center line L of the magnetic head 10 of the magnetic recording and reproducing apparatus. Preferably the third drive rotary wheel 8
Is larger in diameter than the first and second drive rotating wheels 6 and 7.

On the other hand, the third drive rotary wheel 8 and the magnetic head 1
An eccentric rotary wheel 11 which is a drive source of a rotary magnet 15 which will be described later is arranged between 0 and 0, and a fourth drive rotary wheel 9 is provided at an eccentric position of the eccentric rotary wheel 11.

As shown in FIGS. 2A and 2B, the fourth drive rotary wheel 9 is arranged on the center line L of the magnetic head 10 and engaged with the third drive rotary wheel 8 to make the third drive rotary wheel 8 Eccentric rotary wheel 1 around the shaft of the fourth drive rotary wheel 9
Install so that 1 rotates eccentrically.

The fourth drive rotary wheel 9 is the third drive rotary wheel 8
The diameter is made sufficiently smaller to increase the eccentric rotation speed of the eccentric rotary wheel 11 and increase the rotation speed of the rotary magnet 12 described later.

The first to fourth drive rotary wheels 6 to 9 are means for transmitting the rotational drive of the reel shafts 2 and 3 of the magnetic recording and reproducing apparatus to the eccentric rotary wheel 11, and other known transmission means are used. be able to.

The first to fourth drive rotary wheels 6 to 9 formed as described above may be gears, for example, or friction rotary wheels such as rubber rollers may be used.

Further, the eccentric rotary wheel 11 and the magnetic head 10
Rotating magnet 1 having an axis on the center line L between
2 is arranged so that its peripheral surface faces the magnetic head 10, and the rotating magnet 1 is coaxial with the rotating magnet 12.
A drive rotary wheel 13 that rotates integrally with the motor 2 is provided, and the magnet drive rotary wheel 13 is engaged with the eccentric rotary wheel 11 on the center line L to transmit the rotation of the eccentric rotary wheel 11 to the rotary magnet 12.

The eccentric rotary wheel 11 and the magnet drive rotary wheel 13 can be constituted by gears or friction rotary wheels such as rubber rollers as described above. Alternatively, the drive wheel 13 may not be provided, and the eccentric rotary wheel 11 and the rotary magnet 12 may be brought into direct frictional contact to obtain rotation.

As shown in FIG. 4, the rotating magnet 12 is used.
Is a permanent magnet, which is preferably shaped like a disk and is polarized into N and S poles on its diameter line.
At this time, a plurality of N and S poles may be alternately arranged along the peripheral surface of the rotating magnet 12.

Further, groove-shaped cams 15 having an elliptical locus in the direction of the center line L of the magnetic head 10 are provided on the upper and lower lids of the cassette type case 1, and the rotary magnet 1 is attached to the cams 15.
2 and the shaft 14 of the magnet driving rotary wheel 13 are slidably engaged with each other, and the rotary magnet 1 is followed according to the amount of eccentricity of the eccentric rotary wheel 11.
Guide 2 to reciprocate along an elliptical locus.

Although not shown, the cam 15 is provided linearly on the center line L of the magnetic head 10, and the rotary magnet 12 is provided.
It is also possible to reciprocate in a straight line.

The magnetic head 1 is placed in the cassette type case 1.
A spring 16 made of a plate or a wire rod that is located in front of 0 and crosses the center line L is provided side by side, and a pair of spring stoppers 17 that abut against the end surface of the spring 16 in the same cassette type case 1.
Is provided, and a pair of support pins 18 for slidably sandwiching both ends of the spring 17 are provided inside the spring stopper 17, and the shaft 14 of the rotary magnet 12 is elastically supported at the central portion of the spring 16. The magnet driving rotary wheel 13 is constantly brought into pressure contact with the eccentric rotary wheel 11 in the groove-shaped cam 15 by a holding force. The rotary magnet 12 is directly brought into frictional contact with the eccentric rotary wheel without using the drive rotary wheel 13.

When the long diameter portion of the eccentric rotary wheel 11 and the magnet driving rotary wheel 13 are engaged, the spring 16 is pressed by the shaft 14 and flexes (reduces) in an arc shape with the smallest curved surface radius ratio, or eccentric rotation. When the minor diameter portion of the wheel 11 and the magnet drive rotating wheel 13 are engaged, they bend (expand) in an arc shape at the largest curved surface radius ratio, and during this bending movement, both ends of the spring 16 are guided by the support pins 18 to expand and contract. To do. Spring stop 17
When the cassette type magnetic head degaussing device for preventing the displacement of the spring 16 at the time of expansion and contraction is loaded in the magnetic recording or reproducing device, the rotating magnet 12 is at the position most separated from the magnetic head 10 by the elastic force of the spring 16. Waiting That is, the eccentric rotating wheel 11 is pressed by the rotating magnet 12 by the elastic force of the spring 16 and is constantly rotated so that its short diameter portion faces the rotating magnet 12, and as a result, the rotating magnet 12 is rotated.
Has been moved to a position farthest from the magnetic head 10.

By the rotational drive of the reel shafts 2 and 3, the rotational drive is given to the eccentric rotary wheel 11 through the first to fourth drive rotary wheels 6 to 9 to eccentrically rotate the eccentric rotary wheel 11, and the eccentric rotary wheel. Magnet driven rotating wheel 1 following the eccentricity of 11
While rotating 3, the cam 15 reciprocates by the guide of the cam 15. As a result, the rotating magnet 12 rotates and repeatedly approaches and separates from the magnetic head 10 to demagnetize the magnetic head 10.

When the rotation drive of the reel shafts 2 and 3 is stopped, the above series of operations is immediately stopped, and after this stop, the elastic force of the spring 16 is applied to the eccentric rotation wheel 11 via the magnet drive rotation wheel 13. Is corrected to a state in which the minor axis portion of the eccentric rotary wheel 11 and the magnet driving rotary wheel 13 are engaged, and in response to this, the position where the rotary magnet 12 engages the minor axis portion of the eccentric rotary wheel 11, that is, the magnetic field. The head 10 is pushed back and held at the standby position farthest from the head 10.

[0030]

According to the present invention, by rotating a rotating magnet made of a permanent magnet, the N and S magnetic poles of the rotating magnet alternately face the magnetic head to give an alternating magnetic field, and the eccentric rotating wheel is rotated. By periodically repeating the approach and separation of the rotating magnet according to the amount of eccentricity, the strength of the magnetic force applied to the magnetic head can be obtained, and thereby the magnetic head can be efficiently demagnetized.

Further, according to the present invention, by using the eccentric rotating wheel as the drive source of the rotary magnet, the rotation of the rotary magnet and the approach and separation (reciprocating motion) with respect to the magnetic head can be performed properly and easily at the same time. When the demagnetizing device is mounted on the magnetic recording / reproducing device or when the reel shaft is not driven to rotate, the rotating magnet is magnetically supported by elastically holding the rotating magnet by a spring capable of reciprocating the magnetic head. Since it stands by at the position farthest from the head, reverse magnetization from the demagnetizing magnet to the magnetic head can be effectively prevented.

According to the present invention, while rotating the rotating magnet facing the magnetic head, the magnetic head is demagnetized by repeatedly approaching and separating the magnetic head, thereby incorporating a circuit board constituting an oscillation circuit as in the prior art. Therefore, the battery is eliminated, so that the production labor can be simplified and the production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing an internal structure of a cassette type magnetic head degaussing device according to an embodiment of the present invention.

2A is a plan view showing a main part of the cassette type magnetic head degaussing device shown in FIG. 1 in a state where a rotating magnet is close to a magnetic head. FIG.

FIG. 2B is a plan view showing a state where the rotating magnet shown in FIG. 2A is separated from the magnetic head.

FIG. 3 is a sectional view showing a main part of the cassette type magnetic head degaussing device shown in FIG. 2A.

FIG. 4 is a plan view illustrating a rotary magnet.

[Explanation of symbols]

 1 Cassette type case 2, 3 Reel shaft 10 Magnetic head 11 Eccentric rotating wheel 12 Rotating magnet 15 Cam 16 Spring

Claims (3)

[Claims] 1. A degaussing device for a magnetic head of a cassette type, wherein a degaussing magnet is incorporated in a cassette type case, and the cassette type case is loaded into a magnetic recording or reproducing apparatus to demagnetize a magnetic field of a magnetic head. Is formed by a rotary wheel made of a permanent magnet, and the demagnetizing rotary magnet is arranged to reciprocate so as to approach and separate from the magnetic head while rotating facing the magnetic head. Magnetic head degaussing device. 2. A cassette type magnetic head degaussing device for degaussing magnetism of a magnetic head by incorporating a degaussing magnet in a cassette type case and loading the cassette type case in a magnetic recording or reproducing apparatus. A rotating wheel that eccentrically rotates using a reel shaft of a magnetic recording or reproducing device as a drive source and a demagnetizing rotating magnet that is composed of a permanent magnet that rotates facing the magnetic head are provided inside the rotating magnet, and the rotating magnet is eccentric by a spring. The rotary magnet is placed in pressure contact with the rotating wheel, and the rotating magnet is installed so as to reciprocate while following the eccentric amount of the eccentric rotating wheel by the elastic force of the spring, and the rotating magnet is mounted on the inner surface of the cassette type case. A cassette type magnetic head degaussing device comprising a cam that slides on a shaft to guide the reciprocating motion. 3. The cassette type magnetic head degaussing device according to claim 2, wherein the rotating magnet is made to stand by at the position farthest from the magnetic head by the elastic force of the spring.