SU1552226A1 - Device for shaping signal for correction of speed of magnetic heat - Google Patents

Abstract

The invention relates to a magnetic recording technique, namely, to devices for feeding magnetic heads at predetermined addresses in magnetic disk drives. The purpose of the invention is to improve the accuracy of the formation of the correction signal of the speed of movement of the magnetic heads. The magnetic head 1 is connected to the input of the amplifier 2 with adjustable gain, the output of which is connected to the group of demodulators 4-7. The control inputs of the demodulators 4-7 are connected to the outputs of the gate signal unit 3. A full-wave rectifier 11, 12, a summing amplifier 13 and a smoothing filter 14 are introduced into the device, which also contains a summing amplifier 8 and differential amplifiers 9, 10. 4 4 Il.

Description

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This invention relates to a magnetic recording technique, in particular, to devices for feeding magnetic heads.

at specified addresses in magnetic disk drives.

The aim of the invention is to improve the accuracy of the formation of the movement speed correction signal.

Fig. 1 shows a functional diagram of the device for generating a signal for correcting the speed of movement of magnetic heads; 2 shows timing diagrams for his work; in FIG. 3, the graphs of the influence of the edge effect of magnetic signals on the output of the devices ;; positioning of the magnetic heads (a -; asceppe speed; b - speedy 1 h on the tachometer; and - real speed); Fig. 4 is a functional diagram of a device for positioning magnetic heads.

The device contains a magnetic head 1 (MG) connected to the input of amplifier 2 with adjustable gain factor, an output connected to the unit 3 by gating signals and demodulators 4-7 each output of the unit 3 gating signals connected to the corresponding control input of demodulators 4-7, the outputs of which are connected to the inputs of summing amplifier 8, the output connected to the control of amplifier 2 with an adjustable gain level, the outputs of demodulators 4, 5 and 6, 7 are connected in pairs to the inputs of differential amplifiers Firs 9 and 10, the outputs of which through two half-period rectifiers 11 and I2 are connected to the inputs of summing amplifier 13, the output of which is connected to a smoothing filter 14. The positioning device (figure 4) contains a position signal generator 13, a tachometer 16, a digital-analogue converter ( D / A converter) 17 and differential amplifier 18.

The device works as follows.

When the tracks with servo signals are crossed, the magnetic head 1 sequentially reads the signals that are fed to the amplifier 2 with an adjustable gain factor, where they are amplified to a level sufficient for the gating unit 3 to operate, which is extracted from the reproducing 22264

of the input signal of the clock pulses and generates a sequence of pulses for selective analysis of the amplitude of the position pulses by demodulators 4-7. Signals proportional to the amplitude of the positional pulses from the outputs of demodulators 4-7 are fed to the inputs of summing amplifier 8, depending on the result of the summation, the gain of amplifier 2 with adjustable gain varies. With demodulators 4 and 5, the signals arrive at

, r inputs of the differential amplifier 9, and from demodulators 6 and 7 - to the inputs of the differential amplifier 10. At the outputs of the differential amplifiers 9 and 10, signals are put, no magnetic head on the track

(figa, b), corresponding to the difference of amplitudes at the outputs of the demodulators, and the signals at the outputs of the amplifiers 9 and 10 are shifted by 90 relative to each other. Position signals are rectified by half-wave rectifiers 11 and 12 (Fig. 2c, d) and are fed to the inputs of summing amplifier 13, the signal (Fig. 2d) from whose output is smoothed by filter 14, at the output of which a signal is formed (Fig. 2e) proportional to the absolute value of the position signals. The broken line in figure 2 shows the signal provided that the width is equal

35 MG clearance pitch tracks. The solid line shows the signal, provided that the effective width of the gap MG is greater than the pitch of the tracks.

The signal generated at the output of the device can be used to correct the speed signal in MG positioning devices. Fig. 3 shows the effect of the edge effect MG (the effective width of the gap MG is greater than the width of the track) on the signal from the output of the tachometer of the magnetic heads positioning device (figure 4). The positioning device is calculated in such a way that acceleration under the full current of the carriage with MG occurs until the signal from the output of the tachometer is comparable with the level of the specified speed from the DAC. Under the influence of the edge effect, the slope of the position signal decreases and, consequently, the velocity signal decreases. Thus, the magnitude of the speedy

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Ti on the tachometer actually displays the MG movement at a higher speed, which leads to an increase in the acceleration time and the actual carriage speed of the MG with the calculated one exceeded. The generated correction signal can eliminate this drawback. Depending on the level of the correction signal, for example, the reference voltage of the DAC may vary, i.e. when the speed signal changes due to the influence of the edge effect, the signal itself of the specified speed changes in such a way that the calculated positioning law is restored. There may be other options for using the correction signal obtained using the proposed device, for example, using an amplifier with an adjustable gain factor in the tachometer circuit, the adjustable link of which is controlled by the correction signal.

Formula

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A device for generating a signal for correcting the speed of movement of magnetic heads, comprising a magnetic head connected to the input of an amplifier with an adjustable coefficient

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gain, four demodulators, a gating signal unit, and two differential amplifiers, with the inputs of the demodulators and the gating unit

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the signals are interconnected and connected to the output of the amplifier with an adjustable gain factor; the outputs of the gate signal unit

U is connected to the control inputs of the corresponding demodulators whose outputs are connected to the inputs of a summing amplifier, the output of which, in turn, is connected to the control

15 schm. an amplifier with adjustable gain, the inputs of differential amplifiers are pairwise connecting yen to demodulator outputs, characterized in that

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To improve the accuracy of the formation

the signal of the velocity correction, the first and the second full-wave rectifiers and the second summing amplifier, and the smoothing filter are introduced into it, and the inputs of the second summing amplifier are connected through the corresponding full-wave rectifiers with the outputs of the first and second differential amplifiers

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Claims (1)

Claim A device for generating a signal for correcting the speed of movement of magnetic heads, comprising a magnetic head connected to an input of an amplifier with an adjustable gain, four demodulators, a block of strobe signals and two differential amplifiers, the inputs of the demodulators and a block of strobe signals being connected to each other and connected to the output of an amplifier with an adjustable gain, the outputs of the block of strobe signals 10 are connected to the control inputs of the corresponding demodulators, inputs x are connected to the inputs of a summing amplifier, the output of which, in turn, is connected to the control input of an amplifier with an adjustable gain, the inputs of differential amplifiers are paired with the outputs of demodulators, characterized in that, in order to increase the accuracy of signal formation correction moving speed, introduced in it the first and second full-wave rectifier and the second summing amplifier, and smoothing filter ²⁵ is alive, the second inputs of the summing amplifier is connected via a suitable e half-wave rectifiers with outputs of the first and second differential amplifiers — 30 lei, and the output of the second summing amplifier through a smoothing filter is connected to the output of the device.