JPH04170703A - Magnetic head - Google Patents

Abstract

PURPOSE:To suppress noise due to flyback and to make S/N of a servo signal high by providing a read/write coil and a coil for readout of the servo signal of which the resonance frequencies are set to be in prescribed relationships with a data signal and the servo signal respectively. CONSTITUTION:A read/write coil 2 and a coil 3 for readout of a servo signal are wound round for a magnetic core 1 having one read/write gap. The resonance frequency of the coil 2 is set to be the frequency of a data signal or above, and the resonance frequency of the coil 3 is set to be the frequency of the servo signal or above and the frequency of the data signal or below by the number of winds of the coil and the electrostatic capacity of an amplifier in the next stage. While the waveform of the voltage E1 across the coil 2 shows a large voltage fluctuation due to flyback each time the waveform 12 of a write current Iw changes over, noise due to the flyback is reduced effectively in regard to the waveform of the voltage E2 across the coil 3. Thereby the burden on an amplifier 8 and an LPF 9 in the succeeding stages is reduced and S/N of the servo signal can be made excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head, and particularly to a magnetic head used in a deep servo type magnetic recording device.

[Conventional technology]

In recent years, magnetic recording devices such as Flo-7B disk devices,
The storage capacity is increasing, and along with this, the track density is being improved, but it has become necessary to position the magnetic head using a tracking servo.

When adopting a data surface servo method for tracking servo, such as in a floppy disk device, the sector servo method or deep servo (Embedded 5e
rvo) method is used.

In the sector servo method, each track of a magnetic recording medium is divided into multiple sectors, a servo signal is recorded at the beginning of each sector, and the servo signal is read out and tracked accordingly for positioning the magnetic field.・It is a method of performing Soking Saho.

The deep servo method is a method in which data signals are recorded on the surface layer of a magnetic recording medium, and servo signals previously recorded on the deep layer are read out and tracking servo is performed in accordance with the servo signals.

Since tracking servo control is possible over the entire circumference of the magnetic recording medium, this method has higher positioning accuracy than the sector servo method, and has the advantage that a servo signal detection circuit and the like can be omitted.

[Problem to be solved by the invention]

In the deep servo method described above, during a data read operation, it is possible to perform tracking servo control over the entire circumference of the magnetic recording medium using a magnetic head having one read/write gap. For a write operation, a magnetic head is required that has two gaps: a dedicated gap for reading servo signals and a normal read/write gap. however,
Recently, a method has been developed that uses a magnetic head having one read/write gap as shown in FIG. 4 and enables tracking servo control by a circuit as shown in FIG. 5.

FIG. 4 is a plan view showing an example of a conventional magnetic head, and FIG. 5 is a block diagram showing an example of a servo system using the example of FIG. 4.

In the example shown in FIGS. 4 and 5, a read/write coil 16 wound around a magnetic core 15 is connected to one read/write (R/'W> circuit), as in the case of a normal floppy disk device. At the same time, it is connected to the amplifier 20 in parallel, and even when the read/write circuit 19 is writing data, the magnetic core 15 reproduces the servo signal read from the deep part of the magnetic recording medium. The output is amplified by an amplifier 23 as necessary, and only low-frequency component servo signals are separated by several stages of low-pass filters 21 and 23, and then sent to a servo control circuit 24.
and controls the actuator 25 for positioning the magnetic head.

However, the flyback noise generated when the polarity of the current flowing through the read/write coil 16 is switched has a very large potential of approximately +80 dB relative to the servo signal to be reproduced, so a wide dynamic range is required for the amplifier 20. It also has difficult problems such as the need for multiple stages of low-pass filters.

[Means to solve the problem]

The magnetic head of the present invention is a magnetic head used in a deep servo type magnetic recording device, and includes a magnetic core having one read/write gap, and a resonant frequency wound around the magnetic core that is higher than the frequency of a data signal. and a servo signal reading coil whose resonance frequency is set to a frequency higher than the frequency of the servo signal and lower than the frequency of the data signal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a plan view showing one embodiment of the present invention, and Fig. 2 is a plan view showing an embodiment of the present invention.
FIG. 2 is a block diagram showing an example of a servo system using the illustrated embodiment.

In the embodiment shown in FIG. 1, two coils, a read/write coil 2 and a servo signal reading coil 3, are wound around a magnetic core 1 having one read/write gear knob. The read/write coil 2 has a resonance frequency set to a frequency higher than the frequency of the data signal. On the other hand, the servo signal reading coil 3 is set so that its resonance frequency is higher than the servo signal frequency and lower than the data signal frequency, depending on the number of turns of the coil or the capacitance of the next stage amplifier. .

FIG. 2 is a program diagram showing an example of a servo system using the embodiment shown in FIG.

As shown in FIG. 2, the read/write coil 2 is connected to a read/write (R/W) circuit 7 to perform normal read/write operations. The output signal of the servo signal reading coil 3 is amplified by an amplifier 8 and sent to a low-pass filter 9, where only the low frequency component of the servo signal is separated and sent to the servo control circuit 1°. It controls the actuator 11 for head positioning.

FIG. 3 is a waveform diagram showing the write current and the terminal voltage of each coil in the circuit of FIG. 2.

As shown in FIG. 3, every time the waveform 12 of the write current Iw switches, the waveform 13 of the voltage E1 across the read/write coil 2 shows a very large voltage fluctuation due to flyback, and the servo signal Indicates a situation where playback is difficult. However, in the waveform 14 of the voltage E2 across the servo signal reading coil 3, noise due to flyback is extremely effectively reduced. As a result, the burden on the subsequent amplifier 8 and low-pass filter 9 can be significantly reduced, and a good S/N ratio of the servo signal can be obtained.

〔Effect of the invention〕

As explained above, the magnetic head of the present invention has a read/write coil whose resonance frequency is set to a frequency higher than the frequency of the theta signal, and a resonant frequency set to a frequency higher than the frequency of the servo signal and lower than the frequency of the theta signal. By providing two coils, the servo signal readout coil and the servo signal readout coil, the flybar 2. ．． This has the effect of being able to extremely effectively reduce the noise caused by the servo signal, which greatly reduces the burden on the subsequent amplifier and low-pass filter, and also improves the S/N ratio of the servo signal. It has the effect of being able to do something like this.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of the present invention, and Fig. 2 is a plan view showing an embodiment of the present invention.
A block diagram showing an example of a servo system using the embodiment shown in the figure,
Fig. 3 is a waveform diagram showing the write current and terminal voltage of each coil in the circuit of Fig. 2, Fig. 4 is a plan view showing an example of a conventional magnetic head, and Fig. 5 uses the example of Fig. 4. FIG. 2 is a block diagram showing an example of a servo system. 1・15・・・Magnetic core, 2・16・・・・・・
Read/write coil, 3... Servo signal reading coil, 7/19... Read/write (R, y'
W) Circuit, 8・20・22...Amplifier, 9・
2123...-Low pass filter, 10.24.
... Servo control circuit, 11.25 ... Actuator.

Claims (1)

[Claims] 1. A magnetic head used in a deep servo type magnetic recording device, which comprises a magnetic core having one read/write gap, a read/write coil wound around the magnetic core, and a servo signal readout. A magnetic head characterized by comprising a coil for use. 2. A magnetic head used in a deep servo type magnetic recording device, which includes a magnetic core having one read/write gap and a resonance frequency wound around the magnetic core set to a frequency higher than the frequency of the data signal. A magnetic head comprising: a read/write coil; and a servo signal reading coil whose resonance frequency is set to a frequency higher than the frequency of the servo signal and lower than the frequency of the data signal.