JPH01258278A - Method and device for driving magnetic head - Google Patents

Abstract

PURPOSE:To attain control to follow a speed setting value by calculating a speed ratio between the speed setting value of a speed setting table in a magnetic head and an equivalent real speed and executing feed-back control for a product between the speed setting value and speed ratio as a speed command. CONSTITUTION:A position signal S is outputted by the rotation of an access motor M and in each moving of one track, a pulse signal D is outputted to a timer TM. The timer TM counts the period of the pulse signal D in a suitable number and the period is outputted to a speed ratio calculating circuit RAT. The circuit RAT calculates the equivalent real speed from a track pitch and the average value of the period and the speed ratio is obtained between the speed setting value, which is sent from a storing part ROM, and the equivalent speed. Next, by a multiplying circuit MUL, the product between the speed ratio of a register RGV and the speed setting value of a register RGR is given to an adding circuit ADD as the speed command and the feed-back control is executed to a motor driving circuit MDR. Thus, a speed error, which is caused by the gain error of a speed detecting circuit and the inclination error of the position signal, is erased and the control can be executed with following the speed setting value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic head/rad drive method and a magnetic head drive device for positioning and driving a magnetic head/rad on a track in a magnetic disk device.

(Prior Art) In a magnetic disk drive, a step motor, voice coil motor, DC motor, or the like is generally used as a drive source for accessing a magnetic head to a predetermined track position. Although the drive control circuit of the step motor has a relatively simple structure, the access speed is slow, so a voice coil motor or a DC motor is often used in devices that perform high-speed access.

In the case of a DC motor, an encoder is simultaneously used to obtain speed information for step-by-track operation and positioning operation to a specified track position. Encoders are generally
It consists of a slit disk that has slits corresponding to the track pitch and rotates together with the motor shaft, and a photo sensor.
Detects motor operating position information. Then, this motion position information is differentiated to generate velocity information.

FIG. 2 is a block diagram showing an example of a conventional magnetic head speed control circuit when magnetic head/rad positioning is performed using a DC motor.

In the figure, M is an access motor, CPU is a microprocessor, ROM is a storage section that stores a speed setting value VO that sets the speed of motor M, DAC is a DA converter, ADD is an adder circuit, and a storage section. The speed setting value vO of the digital value in the ROM is the D-A converter DAC.
is converted into an analog speed setting signal A and applied to the (+) terminal of the adder circuit ADD. E is an encoder that detects the position signal of the motor M, which includes a slit disk and a photo sensor (both not shown) attached to the shaft of the motor M.
It outputs an analog position signal that changes depending on the position of the slit. POS is an amplifier circuit that amplifies the position signal and shapes the waveform.
The speed signal B is applied to the (-) terminal of the adder circuit ADD. Addition circuit AD
D is the speed difference between speed setting signal A and speed signal B (A-B)
Calculate. AMP is an amplifier circuit that amplifies the speed difference (A-B), MDR is a motor drive circuit, and motor drive circuit MD
R receives the speed difference (A-B) and the rotation direction signal DS,
The rotational speed of motor M is set in the specified rotational direction and the speed difference (A
- Increase or decrease according to B).

FIG. 3 is a detailed diagram of the speed detection circuit VD, and FIG. 4 is an explanatory diagram of the operation of the speed detection circuit VD.

The position signal S is a sinusoidal signal whose waveform is shaped by the amplifier circuit PO8. If the respective linear portions are defined as straight lines La and Lb, then the absolute value of the slope of the straight lines La and Lb becomes the speed signal.

DIF is a differentiation circuit that differentiates the position signal S and outputs a speed signal, and ABS is an absolute value circuit that calculates the absolute value of the differential value. Since the non-linear portion of the position signal S does not represent speed, it cannot be used to calculate the speed signal. INT is an integrating circuit for obtaining a speed signal for the non-linear portion of the position signal S. The torque of the motor M is TS, the current value is 11, the angular velocity is ω, the inertia of the rotating mechanism is Jl, and the torque constant is 1 hour, t, then the torque T is expressed as TmK i w J tv, and the angular velocity ω is,
Since it is expressed as ω-(K/J) f i d t , the speed signal can be obtained by integrating the detected current i of the motor M.

CPI and CF2 are comparison circuits, OR is an OR gate, and comparison circuits CPI and CP2 are each a threshold value VTR.

VTL is used as a comparison standard, and the position signal S is set to each threshold value VT.
When the level is between L and VT)l, the select signal C output from the OR gate is set to 0'', and when it is off, it is set to 1.
”. SW is an analog switch, and select signal C
When is "0", the straight line La.

Select the speed signal B1 of the absolute value circuit ABS that differentiates Lb, and when it is "0", switch to the integration circuit INT and output the speed signal B
Select 2. A speed signal B is obtained by combining these speed signals B1 and 82.

PUL is a pulse generation circuit, and the position signal S is 0 potential V r
A pulse signal is generated every time it crosses ef'.

CT is a counter that counts pulse signals.

Next, the operation of the circuit shown in FIG. 2 will be explained.

The speed control of a magnetic disk device needs to be controlled according to commands in order to reduce variations between devices such as the average access time representing the access speed, but in particular, deceleration control and stop operation control are This must be done accurately to minimize the settling time.

FIG. 5 is a diagram showing the relationship between the number of moving tracks and the speed when the magnetic head moves over n tracks.

The speed setting value vO is stored in the storage unit ROM as a speed setting table, and its value is set according to the number of remaining moving tracks based on the difference between the desired number of moving tracks and the number of moved tracks.

vl is the speed characteristic of the motor M when it is controlled faithfully to the speed setting value vO, and v2 is the speed characteristic of the motor M when the speed is controlled to the speed setting value VO.
V3 is slower than the speed setting value vO of the motor M.
This is the speed characteristic when each is controlled faster.

The speed setting value vO is sent from the microprocessor CPU according to the remaining number of moving tracks, is converted into an analog value by the D-A converter DAC, and is sent to the adder circuit ADD.
added to. On the other hand, the speed detection circuit VD calculates an analog speed signal B from the position signal S of the motor M and the detected current i, and provides negative feedback to the addition circuit ADD, which calculates the mutual speed difference (A-B). do. Motor drive circuit M
DR controls the speed by accelerating the motor M when the speed difference (A-B) is positive and decelerating it when it is negative. and counter C
T counts the pulse signals each time the magnetic head passes a track, and the microprocessor CPU advances the track number in the speed table every time it is counted, and sets the speed setting value v.
O are read out sequentially.

(Problem to be Solved by the Invention) However, in the above speed control, the speed of the access motor when the magnetic head is in positioning operation is
The speed signal of the speed detection circuit calculated from the position signal is controlled to follow the speed setting value of the speed table, so gain errors of the speed detection circuit, errors in the slope of the position signal, etc. are not considered to be speed errors. Therefore, there is a problem in that the speed of the access motor does not necessarily follow the speed setting value.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a magnetic head driving method and a magnetic head driving device that eliminate speed errors of an access motor caused by gain errors in a speed detection circuit and errors in slope of a position signal. .

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a first invention based on a speed setting table that sets the moving speed between each track of the magnetic head and an access motor. A magnetic head of a magnetic disk device that feedback-controls the speed of an access motor based on speed detection information, counts the number of tracks moved by a pulse signal each time the magnetic head opposes a track position, and controls the positioning of the magnetic head to a target track. In the driving method, the equivalent actual speed of the magnetic head is calculated based on the cycle and track pitch of an appropriate number of the pulse signals when the magnetic head moves, and the speed of the speed setting table corresponding to the movement drive is calculated. The speed ratio between the set value and the equivalent actual speed is calculated in advance, the product of the speed set value and the speed ratio is calculated for each pulse signal, the value of the product is used as a speed command, and the speed command is The present invention has adopted a magnetic head driving method in which the speed detection information is negatively fed back. In the second invention, there is provided a storage unit storing a speed setting table that sets the moving speed between each track of the magnetic head, a speed detection circuit that detects speed information of an access motor, and a speed detection circuit that detects speed information of an access motor; A magnetic disk drive comprising: a pulse generating circuit that generates a pulse signal every time a magnetic head faces a track; and a counter that counts the number of tracks moved in response to the pulse signal, and controls the moving speed to control the positioning of a magnetic head on a track. In the magnetic head driving device, the equivalent actual speed of the magnetic head is calculated based on the cycle and track pitch of an appropriate number of the pulse signals, and the setting value of the moving speed corresponding to the calculation of the equivalent actual speed and the equivalent actual speed are calculated. a speed ratio calculation circuit that calculates in advance a speed ratio of the access motor; a speed command generation circuit that calculates the product of the speed setting value read from the storage unit and the speed ratio to generate a speed command for the access motor; The present invention provides a magnetic head drive device including an adder circuit that generates a drive control signal for an access motor by negatively feeding back the speed information with respect to a speed command.

(Function) According to the first invention, for an appropriate number of pulse signals when the magnetic head moves, the equivalent actual speed of the magnetic head is calculated from the equivalent period and track pitch, and this equivalent actual speed is calculated based on the equivalent period and track pitch. The speed ratio between the speed setting value in the speed setting table that caused the speed and the equivalent actual speed is calculated, and when controlling the track position of the magnetic head, the product of the speed setting value and the speed ratio is calculated in sequence, and the The value becomes the speed command,
Feedback control is performed according to the speed command. According to the second invention, when the magnetic head moves, the speed ratio calculation circuit calculates the equivalent actual value of the magnetic head based on the equivalent period and track pitch of the appropriate pulse signal generated from the pulse generation circuit. The speed is calculated, and the speed ratio between the speed setting value of the speed setting table that gave this equivalent actual speed and the equivalent actual speed is calculated, and when controlling the track position of the magnetic head, the speed command generation circuit stores the speed The product of the speed setting value of the section and the speed ratio is calculated to generate a speed command, and the adding circuit provides negative feedback of the speed information from the speed detection circuit to the speed command to generate a drive control signal for the access motor. generated.

(Embodiment) FIG. 1 is a block diagram of a magnetic head speed control circuit showing an embodiment of the present invention.

In this figure, the same parts as those in the circuit of FIG. 2 are designated by the same reference numerals, and the different parts will be mainly explained below.

TM is a timer that counts the pulse period t of the pulse generating circuit. RAT is a speed ratio calculating circuit that calculates an appropriate number of pulse signals from the pulse generation port HpUL when moving the magnetic head from an equivalent period tA obtained by averaging the period t by the timer TM and a track pitch p. The equivalent actual speed VA of the magnetic head is calculated, and the speed ratio VO/VA between the speed setting value VO of the storage ROM that brought about each pulse signal and the equivalent actual speed VA is calculated. RGR is its speed ratio V
A register for storing O/V^, RGV is a register for storing the speed setting value VO of the storage section ROM each time it is read. MUL is a multiplication circuit as a speed command generation circuit, and the product V of the values VO/VA and vO of each register RGR, RGv
Calculate O(VO/VA) and convert to D-A converter DAC
I: Give.

CPUA is a microprocessor that presides over and controls this speed control circuit.

Comparing the circuit of the present invention with the conventional circuit, in the conventional circuit of FIG. 2, the analog value A of the speed setting value vO is given to the (+) terminal of the adder circuit ADD, and the speed detection circuit VD If the speed signal B according to This error is compensated by the equivalent actual speed VA to make the speed of the motor M match the speed setting value vO, and the speed signal B is the product of the actual speed of the motor M and VA/VO. Therefore, the product VO(
By supplying VO/VA) to the adder circuit ADD as a speed command value, control is achieved in which errors in the speed signal B are compensated for.

Next, the operation of the circuit shown in FIG. 1 will be explained.

When the motor M rotates, a position signal S is generated as shown in FIG.
is output, and a pulse signal is output to the timer TM every time the track moves one track. The timer TM counts the period of an appropriate number of pulse signals and outputs the counted value to the speed ratio calculation circuit RAT.The speed detection circuit RAT calculates the equivalent actual speed VA from the average value tA of the track pitch p and the period t. is the formula, V
Calculated by A-p/tA.

The speed ratio calculation circuit RAT calculates the speed ratio VO/V based on the speed setting value vO read from the storage unit ROM and the equivalent actual speed VA.
Calculate A.

The pulse signals are counted by a counter CT, and based on this count, the microprocessor CPU calculates the number of remaining tracks to be moved to the desired track,
A speed setting value VO is set in the register RGV according to the value.

The speed ratio VO/of the register RGR is calculated by the multiplier circuit MUL.
The product VO (V
o/VA) is calculated, and the result is converted to D-A converter D.
It is converted into an analog value by AC and given to the adder circuit ADD as a speed command value. Thereafter, the speed is controlled in the same manner as in FIG.

In addition, the speed ratio VO between the speed setting value VO and the equivalent actual speed VA
/VA does not need to be calculated every time a seek operation is performed, but only needs to be calculated once immediately after power is turned on.

(Effects of the Invention) As explained above, according to the present invention, the equivalent actual speed is calculated in advance from the period of the pulse signal each time the magnetic head moves between tracks, and when seeking, the equivalent actual speed and the speed setting value are calculated in advance. Since the read value of the speed setting table is corrected by the reciprocal of the speed ratio between the speed setting table and the speed setting table and this is used as the speed command, control that follows the speed setting value becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic head speed control circuit showing an embodiment of the present invention, FIG. 2 is a block diagram of a conventional magnetic head speed control circuit, FIG. 3 is a detailed diagram of a speed detection circuit, and FIG. FIG. 5, which is an explanatory diagram of the operation of the speed detection circuit, is a diagram showing the relationship between the number of moving tracks and the moving speed. M...Access motor, CPUA...Microprocessor, ROM...Storage unit, VD...Speed detection circuit, PUL...Pulse generation circuit, CT...Counter,
RAT...speed ratio calculation circuit, MUL...multiplication circuit,
ADD...addition circuit. Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Yoshi 1) Takashi Sei

Claims (2)

[Claims] (1) The speed of the access motor is feedback-controlled based on the speed setting table that sets the moving speed between each track of the magnetic head and based on the speed detection information of the access motor, and a pulse is generated every time the magnetic head faces the track position. In a method for driving a magnetic head of a magnetic disk device, which controls the positioning of a magnetic head on a target track by counting the number of moving tracks based on signals, the period and track pitch of an appropriate number of pulse signals when the magnetic head moves are determined. calculate the equivalent actual speed of the magnetic head, calculate in advance the speed ratio of the speed setting value of the speed setting table corresponding to the movement drive and the equivalent actual speed, and calculate the speed setting value for each pulse signal. and the speed ratio, the value of the product is used as a speed command, and the speed detection information is negatively fed back to the speed command. (2) A storage unit that stores a speed setting table that sets the moving speed between each track of the magnetic head, a speed detection circuit that detects speed information of the access motor, and a pulse that is generated every time the magnetic head faces a track. A magnetic head drive device for a magnetic disk device comprising a pulse generation circuit that generates a signal and a counter that counts the number of tracks moved in response to the pulse signal, and controls the movement speed to control the positioning of the magnetic head on the track, The equivalent actual speed of the magnetic head is calculated based on the cycle and track pitch of an appropriate number of the pulse signals, and the speed ratio between the set value of the moving speed and the equivalent actual speed corresponding to the calculation of the equivalent actual speed is determined in advance. a speed ratio calculation circuit that calculates the speed ratio; a speed command generation circuit that calculates the product of the speed setting value read from the storage unit and the speed ratio to generate a speed command for the access motor; 1. A magnetic head drive device comprising: an addition circuit that generates a drive control signal for an access motor by negative feedback of speed information.