JPS6194212A - Detecting circuit for defective insulation of magnetic head - Google Patents

Abstract

PURPOSE:To detect the defective insulation with a simple circuit constitution by biasing an external frame of a magnetic head to the zero potential as long as a fixed level of bias voltage is impressed to said external frame or the bias voltage is impressed to an internal element itself of the magnetic head and then monitoring the current flowing to the frame by a logical circuit. CONSTITUTION:The voltage VB1 obtained by dividing the power supply voltage VB (DC5-10V) by resistors R1 and R2 is applied to a comparator 8 as the reference voltage. Then the voltage VB2 applied to the terminal at the other side is monitored. Under such conditions, data are read out of a recording medium through a magnetic film 3 for magnetic head core and a conductor film 4 for coil. Then these data are reproduced by a reproducing circuit 7 via terminals 5a and 5b, and the reproduced data 2 are sent to a control part. If a defectively insulated area is detected within a magnetic head, the voltage drop is produced to a resistor RD owing to a fault current Ii flowing through a leak resistance RI. Then a defective voltage detecting signal 1 is sent to the control part in the form of an output of a comparator 8 when the drop of the VB2 is less than the VB1. Thus the defective insulation is detected with the magnetic head.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an insulation failure detection circuit for a magnetic head that detects a current flowing in an external frame using a logic circuit whose operating point is determined in advance at a predetermined bias voltage. Regarding.

Magnetic heads used in magnetic tape devices and magnetic disk devices, which are often used as external storage devices for information processing devices, have undergone various improvements and improvements, and compact, high-performance devices have been put into practical use. became.

In this way, the more compact and high-performance a product becomes, the more defects such as dielectric breakdown may occur inside it.

It is difficult to determine whether or not there is a defective part inside.

Being able to identify such defective locations using a simple method is an important matter in ensuring higher quality data.

[Conventional technology]

FIG. 2 shows a schematic diagram of a conventional magnetic head, and FIG. 3 shows a schematic diagram of a recent thin film head.

``Magnetic heads are generally capable of performing one or more of the functions of reading, writing, and erasing data on magnetic tape media, and with the development of thin film technology, small and high-performance heads that apply these technologies have been developed. Products with high performance can now be put into practical use.

In magnetic heads before the introduction of thin film technology, a magnetic circuit was constructed by winding a wire 2 around a core 1, as shown in FIG. The insulation of the wire rods 2 of this method can be strengthened individually, and therefore problems of poor insulation inside the magnetic head hardly occur.

However, when magnetic heads began to be manufactured using thin film technology as shown in Figure 3, various manufacturing problems occurred, such as pinholes in the thin films (magnetic film 3, conductive film 4, etc.) and dielectric breakdown due to static electricity. and internal elements such as the magnetic film 3 and the conductive film 4,
Insulation failures began to occur between the external frames (not shown) covering these.

That is, the thin film magnetic head is as shown in FIG.

Generally, a magnetic film 3 for a magnetic helad core and a conductive film 4 for a coil are formed on a suitable insulating substrate (not shown) by vapor deposition, sputtering, plating, or the like.

This makes it possible to realize a fine and highly accurate shape.

[Problem that the invention seeks to solve]

If there is an insulation defect between the internal elements and the external frame of the thin film magnetic helmet formed as described above, current from the outside will flow into the internal elements.

This will generate noise and cause data errors.

However, it is very difficult to determine whether this noise is due to a defect in the recording medium or a defect in the magnetic head, and there is a problem in that it requires a great deal of effort to find out the cause.

[Means for solving problems]

An object of the present invention is to realize a novel insulation defect detection circuit for a magnetic head that solves the above-mentioned problems. The magnetic head according to the present invention includes a logic circuit whose operating point is determined in advance, connects the bias voltage setting terminal to the external frame, and detects insulation failure of the magnetic head by detecting a change in bias potential. This problem is solved by an insulation failure detection circuit.

[Effect]

In other words, if a constant bias voltage is applied to the external frame of the magnetic head, or if a bias voltage is applied to the internal elements of the magnetic head itself, then the frame is biased to zero potential and the current flows through the external frame. By monitoring with logic circuits.

Insulation abnormalities can be easily detected with a simple circuit configuration.

〔Example〕

The gist of the present invention will be specifically explained below with reference to an embodiment shown in FIG.

FIG. 1 shows an embodiment of an insulation failure detection circuit according to the invention. The same symbols indicate the same objects throughout the figures.

In this embodiment, a constant bias voltage VB is applied to the external frame 6.
2 is applied.

The resistor RD is a load resistance for detecting an abnormal current It (the current direction is shown by a solid arrow) flowing through a leak resistance RI (a part shown by a dotted line) at a location with poor insulation. Note that a connection point a indicates a connection point between the lead of the resistor RD and the external frame 6.

On the other hand, the capacitor Cp is used to set the frame 6 at an alternating current ground potential and to prevent the comparator 8 from malfunctioning due to noise.

The comparator 8 has a power supply voltage VB (
A voltage VBI obtained by dividing DC 5v-10v) by resistors R1 and R2 is applied, and a voltage VB2 applied to the other terminal is monitored.

In this state, data is read from the recording medium (not shown) using the magnetic film 3 for the magnetic core and the conductive film 4 for the coil, and is reproduced by the reproducing circuit 7 via the terminals 5a and 5b. is sent to a control unit (not shown).

On the other hand, at this time, if there is an insulation defect in the magnetic head, an abnormal current If flowing through the leakage resistor RE causes the resistor R to
A voltage drop occurs in D, and the drop in voltage VB2 becomes voltage VBI
If the voltage falls below this level, the comparator 8 outputs an abnormal voltage detection signal (2) to a control section (not shown) to detect an insulation failure of the magnetic head.

The above-mentioned detection circuit is permanently installed in a device equipped with a magnetic head, and whenever data is read, the data is used to constantly monitor insulation defects in the magnetic head.

〔Effect of the invention〕

According to the present invention as described above, it is possible to clearly isolate insulation defects in a magnetic head with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of an insulation failure detection circuit according to the present invention. FIG. 2 is a schematic diagram of a conventional magnetic head. Figure 3 is a schematic diagram of a recent thin film head. are shown respectively. In fig. 1 is the core, 2 is the coil. 3 is a magnetic film, 4 is a conductive film. 5. 5a and 5b are terminals, 6 is external frame. 7 is a reproduction circuit 2, 8 is a comparator. No.1

Claims (1)

[Claims] A detection circuit for detecting insulation failure between the element and the external frame of a magnetic head, the magnetic head having an element for recording/reproducing information on a recording medium and an external frame provided to cover the element. , which has a bias voltage setting terminal and includes a logic circuit whose operating point is predetermined at a predetermined bias voltage, connects the bias voltage setting terminal to the external frame, and detects a change in the bias potential. A magnetic head insulation defect detection circuit characterized by detecting an insulation defect in a magnetic head.