JPH02276007A - Magnetic head - Google Patents

Abstract

PURPOSE:To prevent the malfunction or destruction of a signal amplifying circuit due to static electricity, and to improve the reliability of a magnetic recording/reproducing device by providing a metallic case to prevent the static electricity at a magnetic head. CONSTITUTION:Double metallic cases 8 and 9 in a similar temple bell shape equipped with aperture parts 8a and 9a at the tops, which are mutually electrically insulated by an insulating member 7, is provided, and ground terminals 10 and 11 are fixed so that the hem inner periphery and hem outer periphery of the inner and outer metallic cases 8 and 9 may be linearly symmetrical with respect to a center axis. By the change of the magnetic field of the magnetic card and the magnetic tape, the electromotive force of a coil 3 conforming to the magnetic flux change generated at a core 2 is outputted from a signal output terminal 4. At such a time the inner metallic case 8 electrically shields the core 2 and the coil 3 from the outside, and the outer metallic case 9 applys the static electricity charged on the magnetic card and the magnetic tape to the ground circuit separately provided from the signal amplifying circuit. Thus the reliable magnetic head without generating malfunction can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic head for recording or reproducing data on a magnetic card or magnetic tape.

(Prior Art) A conventional magnetic head will be explained with reference to the cross-sectional view of FIG. In the figure, a conventional magnetic head has a coil 3 wound around a triangular core 2 of a percussion instrument in a bell-shaped metal case 1 with an opening 1a at the tip. The two signal terminals 4 connected to both ends of the coil 3 are inserted so as to be exposed from the opening 1a of the metal case 1 and protrude from the hem of the metal case 1, and fixed with a resin 5, and further, A ground terminal 6 is fixed to the outer periphery of the hem of the metal case 1 described above.

The operation of the magnetic head configured as described above will be explained by taking the reproduction time as an example.

When the tip of the magnetic head is brought into contact with a magnetic card or magnetic tape and then moved in a predetermined direction, a magnetic flux change occurs in the core 2 that is in contact with the magnetic field in response to a change in the magnetic field recorded on the head. A change in potential is induced in the coil 3. This induced power is output from the signal output terminal 4 of the magnetic head. The metal case 1 is connected to the core 2 from the outside. It is for electrically and mechanically shielding the coil 3, and a ground terminal 6 connected thereto is connected to the ground circuit of the signal amplification circuit.

(Problem to be Solved by the Invention) However, in the above configuration, the metal case 1 is connected to the ground circuit of the signal amplification circuit via the ground terminal 6, so the magnetic card or magnetic tape is charged. In this case, the charge flows from the metal case 1 through the ground terminal 6 into the signal amplification circuit, causing malfunction of the circuit or, in severe cases, destroying the semiconductor.

The present invention solves the above problems and provides a reliable magnetic head that does not malfunction.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a metal case for removing static electricity, which is electrically insulated from the metal case for shielding, on the outside of the metal case for shielding. be.

(Function) With the above configuration, even if the magnetic card or magnetic tape is charged, the static electricity can flow from the antistatic metal case to a grounding circuit that is separate from the grounding circuit of the signal amplification circuit. Since it does not flow into the shielding metal case, malfunction of the signal amplification circuit and destruction of semiconductors are eliminated.

(Example) An example of the present invention will be described with reference to FIG. In the same figure, the difference between this embodiment and the conventional example shown in FIG. The metal cases 8 and 9 were replaced with double metal cases 8 and 9 having similar bell shapes, and ground terminals 10 and 11 were fixed to the inner circumference and outer circumference of the hem of the inner and outer metal cases 8 and 9 so as to be symmetrical about the central axis. It is something. Since the rest is the same as the conventional example, the same components are given the same reference numerals and their explanations are omitted.

First, a method of mounting the magnetic head configured as described above will be explained. Once the magnetic head is attached to the magnetic recording/reproducing device, the signal output terminal 4 is connected to the signal amplification circuit, the ground terminal 10 of the inner metal case 8 is connected to the common ground circuit of the signal amplification circuit, and the ground terminal of the outer metal case 9 is connected to the common ground circuit of the signal amplification circuit. 11 are each connected to a separate ground circuit.

Next, the operation of the magnetic head mounted in this manner will be explained.

The electromotive force of the coil 3 is outputted from the signal output terminal 4 in accordance with the change in magnetic flux generated in the core 2 due to the change in the magnetic field of the magnetic card or magnetic tape. The inner metal case 8 is connected to the core 2 from the outside. The coil 3 is electrically shielded, and the outer metal case 9 causes static electricity charged on the magnetic card or magnetic tape to flow through the signal amplification circuit and a separate grounding circuit to eliminate the static electricity.

(Effects of the Invention) As explained above, according to the present invention, since the magnetic head is provided with a metal case for preventing static electricity, it is possible to prevent malfunction or destruction of the signal amplification circuit due to static electricity.
The reliability of the magnetic recording/reproducing device can be improved.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of magnetic heads showing an embodiment according to the present invention and a conventional example, respectively. 1.8.9...Metal case, la, 8a. 9a...Opening, 2...Core, 3...Coil, 4...Signal output terminal, 5...Resin, 6,
10°11... Earth terminal. Patent applicant: Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] In a magnetic head, a coil wound around a core is housed in a metal case, fixed with resin, and has a signal output terminal connected to both ends of the coil and a ground terminal fixed to the metal case. A magnetic head characterized by having a double metal case electrically insulated from each other and having a ground terminal fixed to each.