SU1478251A1 - Automatic gain control circuit for servodata playback channel of magnetic head positioner - Google Patents

Abstract

The invention relates to the field of computer technology, information storage technology, namely, devices for positioning magnetic heads in magnetic disk drives. The invention extends the functionality of an automatic servo reproduction channel gain adjustment circuit. The signal read by the magnetic head 1 is fed to the amplifier 2 with an adjustable gain factor. The peak detector 3, together with the synch pulse shaper 4, extracts the sync pulses from the reproduced signal, of which the gating pulse shaper 5 forms two series of pulses. The formed series alternately opens the first and second analog switches 6 and 7 for analysis by the first or second demodulators 8 and 9. The signals from the outputs of the first and second demodulators 8 and 9 and the first and second analog inverters 10 and 11 are rectified first, second, the third and fourth rectifiers 12, 13, 14, and 15. The values obtained are added up by summing amplifier 16 and compared in comparator 17 with the reference voltage. 2 Il.

Description

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The invention relates to computer technology, information storage technology, and specifically to magnetic head positioning devices in magnetic disk drives.

The purpose of the invention is to expand the functionality.

1 shows a functional diagram of the device; figure 2 - the shape and location of the servo signals used in this device.

The device contains a magnetic head 1, an amplifier 2 with adjustable gain, a detector of 3 peaks, a shaper 4 clock pulses, a shaper 5 gating pulses, the first and second analog switches 6 and 7, the first and second demodulators 8 and 9, from the first to the fourth rectifiers, 12-15, first 10 and second 11 analog inverters, comparator 17 and summing amplifier 16.

When crossing tracks with servo signals, the magnetic head, the working gap of which is equal to twice the width of the tracks, sequentially reads the signals shown in Fig. 2. At the maximum value of the flow rate of the DP 1 position (negative or positive value), the value of the DP 2 flow rate is zero and vice versa, i.e. at any location of the magnetic head 1, the sum of the absolute values of DP 1 and DP 2 remains unchanged.

The device works as follows.

The signal read by magnetic head 1 is fed to amplifier 2 with adjustable gain, where it is amplified to a level sufficient for the detector to operate 3 peaks, which, together with the shaper 4 sync pulses, separate the sync pulses from the reproduced signal, from which the shaper 5 gates form two series of pulses. Each series corresponds to a specific flow rate. The formed series alternately opens the first and second analog switches 6 and 7 for analyzing the first 8 or second 9 demodulators, the amplitudes and polarities of the respective position rates. Signals proportional to the magnitude and polarity of the flow rates are inverted by the first and second analog inverters 10 and 11. The signals from the output

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The first and second demodulators and the first and second analog inverters are rectified by the first, second, third, and fourth rectifiers to form the absolute value of the amplitude of the flow rates. The values obtained are added together by summing amplifier 16 and compared in comparator 17 with reference voltage. Any deviation of the sum of the absolute values of the positioned signals from the reference voltage causes a decrease or increase in the gain of amplifier 2.

Claims (1)

Invention Formula The automatic gain control circuit of the servo information playback device of the magnetic heads positioning device, containing an amplifier with adjustable gain, the control input of which is connected to the output of the voltage comparator, one output of which is connected to the reference voltage bus, and the other is connected to the output of the summing amplifier, amplifier output with adjustable gain is connected to the inputs of the first and second analog switches and through the peak detector to the sync driver. All the outputs of which are connected to the input of the gating pulse former, each of the two outputs of which is connected to the control inputs of the first and second analog switches, the outputs of which are connected to the inputs of the first and second demodulators, in order to extend the functionality , the first and second analog inverters and the first to fourth rectifiers are introduced into it, and the output of the first demodulator is connected through the first analog inverter and the first rectifier connected in series with the first stroke and summing amplifier via a second rectifier - to the second input of the summing amplifier, the output of the second demodulator is coupled via series connected second analog inverter and the third rectifier to the third input of the summing amplifier via a fourth and a rectifier - a fourth input of the summing amplifier. / 7 + 7 P + 2 / 7 + 3/7 + 4 № №Ь & т Jwjv l 0 -Wi SL CS4 A “A SD -JVV 4W - y 4L but F1U /./