JPS58141472A - Speed control signal generating circuit for magnetic head - Google Patents

Abstract

PURPOSE:To keep the output amplitude of an integrator constant to prevent the increment of the access time or the degradation of the transition response after arrival to a target cylinder, by applying a compensating voltage corresponding to the position of a magnetic head to the integrator. CONSTITUTION:An integrator 7 consists of an integrating circuit 24 and an integrating capcitor 25 and is provided with a switch 17 which short-circuits the integrating capacitor 25. A counter 21 generates an output signal indicating the current position of the magnetic head even during movement of the magnetic head, and this output signal is applied to a PROM 22. Data obtained by converting a value, which is proportional to a required compensation quantity corresponding to the position of the magnetic head, to a binary is written in the PROM 22, and the output is supplied to a DA converter 23. This DA converter 23 converts the input signal to an analog voltage to generate the correcting voltage, and this voltage is inputted to the integrating circuit 24 together with a speed signal 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head speed control circuit for a magnetic disk device.

Positioning of the magnetic head of a magnetic disk When moving the circuit-like magnetic head to a required position, the magnetic head is controlled to be accelerated to a predetermined speed and then decelerated by 9 degrees. The speed during deceleration follows a predetermined reference speed, but this rounded reference speed signal is determined by the number n of tracks to be moved in the deviation register IK as shown in FIG. Each time it passes, it is subtracted by one cylinder pulse. The output of the difference register is compared with a preset value N by a comparator 2. If the D7 arrangement register output is larger than the numerical value N! The multiplexer t3 selects a constant value N, and when the differential register output is less than N, selects the differential register output itself and sends it to the DA* converter 4.

The DA converter converts this into a stepped analog voltage lO as shown in FIG. A speed signal 5 and a set signal 6 are applied to the integrator 7. Reset signal line, difference register If the output n is larger than N, it is a normal pressure reset state, and if the output n is less than N, a cylinder pulse is added and the integrator is reset by the cylinder pulse, so the integrator The output becomes a sawtooth waveform 11 as shown in FIG. The adder 8 subtracts the output of the integrator 7 from the output of the Dm transform-4, and generates at the output terminal 9 an output signal 12 that smoothly decreases as the magnetic head moves as shown in FIG. This output signal is further applied to a non-linear circuit (not shown) to form a velocity reference signal which decreases as the magnetic head moves in proportion to approximately the square root of the distance to the target track.

Here, since the input to the integrator is a speed signal, an output proportional to the amount of movement of the magnetic head is generated, but the integrator is reset every time one track passes by the cylinder pulse. This integrator produces an output signal proportional to the track spacing if the pulse width of the cylinder pulse is sufficiently small compared to the one-track transit time. In addition, when the integrator toggle interval is normally constant, the integrator output O envelope 4113 is always constant as shown in 1lIIt3HK, but in some cases, a method called an electronic termimeter is used to obtain the speed signal, and various parameters are used. The integrator output amplitude 14 changes as shown in FIG. 3 due to variations in position. Jin's electronic tachometer uses a magnetic disk device that has a disk surface called a servo surface on which positioning rounding information is written in advance, and differentiates the position signal obtained by demodulating the read signal from the servo surface to determine a good signal. This method is well known in the art and is a good technique to obtain a speed signal from a rounded voice by moving a magnetic head; This pigeon coop position signal changes into a triangular waveform as the magnetic head moves. The slope of this position signal with respect to the magnetic head displacement and
The force constant of the voice coil motor changes with the position of the magnetic head due to various causes, and therefore the speed signal II! The output amplitude of the integrator that receives the speed signal as input is no longer constant. If the 4IK integrator output amplitude 14 increases as shown in Fig. 3 near the target cylinder, the speed reference signal will decrease, and the access time will become longer; conversely, if it decreases near the target cylinder, the speed reference signal will decrease. This increases, and the excessive fluid response becomes simple after reaching the target cylinder.

The present invention eliminates the above-mentioned drawbacks by applying a correction voltage to the integrator according to the position of the magnetic head to keep the integrator output amplitude constant. A speed control circuit is provided.

According to the present invention, a DA converter that converts a signal of the difference between the current position and a target position of the magnetic head, and a
It has an integrator that generates a sawtooth waveform every time a track passes, and an adder that adds the output signal of the DA converter and the output signal of the integrator, and the output signal of the adder is used as a speed signal. In the speed control signal generation circuit for the magnetic head, there is a counter that indicates the position of the magnetic head, a programmable read-only memory in which a correction amount corresponding to the position is written in advance, and a correction voltage that outputs the correction amount from the read-only memory. There is obtained a magnetic head speed control signal generating circuit characterized in that it has a second ODA converter for converting the second ODA converter into an ODA converter, and is configured to supply a correction voltage from the other DA converter to the integrator.

Next, an embodiment of the present invention will be described with reference to the drawings. One embodiment of the present invention is almost the same as the speed control signal generation circuit for the magnetic head shown in the first WJK, so a detailed explanation thereof will be omitted.
A correction voltage is supplied to keep the integrator output amplitude constant.

No. 411 shows a main part in an embodiment of the present invention.

At No. 41g1, the integrator 7 is provided with an integration circuit J4 and an integration content t25, and is further provided with a switch 17 that short-circuits the integration capacitor 25.

On the other hand, the counter 21 is supplied with the cylinder pulse 18, but the logic signal 1919 is 2 depending on the moving direction of the magnetic head.
0 is added, if moving in one direction it is added, and if moving in the opposite direction it is subtracted. Even when the magnetic head is moving, the counter 21 generates an output signal indicating the current position of the magnetic head and is applied to the PROMzz K. The FROM 22 is written with data obtained by converting a value proportional to the necessary correction amount corresponding to the position of the magnetic head into a binary number, and supplies its output to the DRAM converter 23. This 9
The human converter 23 converts the input signal into an analog voltage, generates a correction voltage, and inputs it to the integration circuit 24 together with the speed signal 16. A reset signal 15 is further applied to the integrator 7, and by closing the switch 17, the integration capacitor t25 is short-circuited and the integration circuit 24 is reset. In this way, if a correction voltage corresponding to the position of the magnetic head is applied to the integrator along with the speed signal, the amplitude of the IIK integrator output shown in FIG.
3 can be kept constant.

As explained above, the present invention maintains a constant integral output amplitude by applying a correction voltage to the integrator according to the position of the magnetic head, thereby preventing an increase in access time or deterioration of transient response after reaching the target cylinder. effective.

[Brief explanation of the drawing]

Figure 1 is a boot diagram showing a part of the speed reference signal generation circuit, Figure 2 is the output waveform of each part of the boot diagram in Figure 1, and Figure 3 is a boot diagram showing a part of the speed reference signal generation circuit.
The figure shows the envelope line of the integrator output signal, and FIG. 4 shows the main parts of the s-koji example of the present invention.

Claims (1)

[Claims] A DA converter that converts the difference signal between the current position and the target position of the magnetic head into a DA converter, an integrator that generates a sawtooth waveform every time the magnetic head passes one track, and an output signal of the DA converter and the front #2. A magnetic head speed control signal generation circuit that includes an adder that adds the output signal of the integrator and the output signal of the adder as a speed signal, and a counter that indicates the position of the magnetic head, and a counter that corresponds to the position. Progera that promised the amount of correction in advance! Pull read-only memory and the read-only memory
and another L)A converter that converts the correction amount from the only memory into a correction voltage, and the correction voltage from the other ODA converter is supplied to the integrator. Directly connected to head speed control signal generation.