JPH0648564Y2 - Magnetic head polarity discrimination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a device capable of discriminating the polarity of, for example, a magnetic head for digital magnetic recording, especially a head for a floppy disk drive (FDD).

[Conventional technology]

As magnetic heads used for FDD, tunnel erase type and straddle erase type magnetic heads are mainly used, and both are READ / WRITE for signal writing and reading.
The (R / W) head and the ERASE (ER) head for erasing both sides of the signal written by the R / W head in a direct current are integrated. Since a direct current is applied to the ER coil, it gives a slight DC bias to the R / W head. Recently, the number of double-sided FDDs is increasing, and in this case it is necessary to manage the polarities of the front and back heads in a fixed relationship, and it is necessary to determine the polarities of each head.

Conventionally, the polarity of the magnetic head is discriminated by applying an oscillator output to the magnetic head and detecting the leakage magnetic flux from the sliding surface of the recording medium of the magnetic head with a detection probe having a magnetic core winding. Above, a method of comparing the phases of the input voltage and the output voltage is performed.

[Problems to be solved by the invention]

However, this method has a drawback that it requires a large device such as an oscillator and an oscilloscope and that each device is difficult to handle and that measurement errors are likely to occur, resulting in poor workability.

[Means for solving problems]

The present invention eliminates these drawbacks and provides an inexpensive magnetic head polarity discriminating device which enables anyone to easily discriminate the polarity of the magnetic head. A means for applying a voltage, a detection probe having a magnetic core wound, a first amplifier circuit for amplifying the voltage applied to the magnetic head, and the output of the first amplifier circuit in a positive direction in a sine wave. The first pulse shaping circuit that slices at a predetermined level that has a wider amplitude in the negative direction, the second amplification circuit for amplifying the detection voltage by the detection probe, and the output of the second amplification circuit in the sine wave A second pulse shaping circuit that slices at a predetermined level where the amplitude is wider in the negative direction than in the positive direction, a logical product circuit that obtains the logical product of the outputs of the first and second pulse shaping circuits, and the output of the logical product circuit. A rectifier circuit for rectifying, and a comparator circuit for comparing the reference voltage output of the rectifier circuit, is characterized in that it comprises a display circuit for displaying the output of the comparator circuit.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a magnetic head polarity discriminating apparatus according to the present invention, and FIG. 2 shows waveforms of respective parts for explaining the operation thereof.

In FIGS. 1 and 2, first, a sine wave voltage is applied to the magnetic head 11 from the oscillation circuit 13. At the same time, the applied voltage is amplified by the amplifier 14 and then shaped by the pulse shaping circuit 15 into a rectangular wave '. On the other hand, the leakage magnetic flux from the sliding surface of the recording medium of the magnetic head 11 is detected by the detection probe 12 having a winding on the magnetic core, the output of the detection probe 12 is amplified by the amplifier 14 ', and then pulse shaping is performed. The circuit 15 'shapes the rectangular wave'.

Next, the logical product of the outputs' and 'of the pulse shaping circuits 15 and 15' is obtained by the logical product circuit 16.

The output of the detection probe 12 is 180 as shown by the broken line when the polarities of the magnetic head 11 are different as shown in FIG.
° Sine waves with different phases are obtained, and the waveform 'which is amplified and pulse-shaped is also a rectangular wave with 180 degrees different phase as shown by the broken line.

Therefore, when the output voltage of the magnetic head 11 and the output of the detection probe 12 have the same phase as shown in FIG. When the phase of the applied voltage and the output of the detection probe 12 differ by 180 °, it becomes like the broken line.

Further, the output of the AND circuit 16 is rectified by the rectifier circuit 17 and then compared with the reference voltage by the comparator circuit 18, whereby the display circuit 19 can display whether the phase is the same or different by 180 °.

In the actual circuit, as shown in Fig. 2, the pulse shaping circuit 1
It is desirable that the slice level of 5,15 'be slightly shifted from the center level of the sine wave. According to this, the pulse widths of the obtained square waves ′ and ′ in the positive direction are narrower than the pulse width in the negative direction, and the output of the AND circuit 16 in the case of the opposite phase is It maintains a zero level and operates stably.

Further, in the above description, the phase of the applied voltage of the magnetic head 11 is compared with the phase of the output of the detection probe 12 as it is. Also in this case, when the output of the logic circuit 16 does not reach the zero level, it is desirable to compare the applied voltages of the magnetic head 11 after the phases are matched through the phase shift circuit.

[Effect of device]

As described above, according to the present invention, it is possible to construct a polarity discriminating device by combining a simple circuit without the need for an expensive device, and anyone can confidently and easily polarize the magnetic head. It can be discriminated and is very effective in practice.

In particular, since a slight amount of phase fluctuation can be tolerated despite the use of the sine wave voltage, there is an advantage that the polarity can be accurately determined by a stable operation. As a result, a highly reliable magnetic head polarity discriminating apparatus can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a magnetic head polarity discriminating apparatus according to the present invention, and FIG. 2 is a waveform diagram of each part for explaining the operation of the same embodiment. 11 …… Magnetic head, 12 …… Detection probe, 13 …… Oscillation circuit, 15,15 ′ …… Pulse shaping circuit, 16 …… AND circuit, 17…
… Rectifier circuit.

Claims (1)

[Scope of utility model registration request] 1. A means for applying a sinusoidal voltage to a magnetic head, a detection probe having a magnetic core wound, a first amplifier circuit for amplifying the voltage applied to the magnetic head, and the first amplifier circuit. A first pulse shaping circuit for slicing the output of the one amplifier circuit at a predetermined level in which the amplitude of the sine wave is wider in the negative direction than in the positive direction, and a second amplifier circuit for amplifying the voltage detected by the detection probe. And a second pulse shaping circuit for slicing the output of the second amplifier circuit at a predetermined level in which the amplitude of the sine wave is wider in the negative direction than in the positive direction, and the outputs of the first and second pulse shaping circuits AND circuit for obtaining the logical product of R, a rectifier circuit for rectifying the output of the AND circuit, a comparator circuit for comparing the output of the rectifier circuit with a reference voltage, and a display for displaying the output of the comparator circuit Magnetic head polarity discriminating apparatus which comprises a road.