JPS6037482B2 - speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device, and is particularly applicable to a magnetic disk device in which a carriage equipped with a magnetic head is run in order to cause a magnetic head to reach a desired track on a magnetic disk. The present invention relates to a suitable speed control device.

In magnetic disk drives, it is possible to control the moving speed of the carriage while it reaches the target stop position.
It will probably be done.

In other words, in order to quickly reach the target stop position and suppress vibration, the moving speed of the carriage is controlled along an ideal deceleration curve, and after reaching the vicinity of the target stop position, the carriage is It performs positioning control.

FIG. 1 shows a speed control section of a magnetic disk device that performs such control.

In the figure, 1 is a rotating disk-shaped medium, 2 is an arm with a magnetic head attached to its tip, etc., 3 is a carriage that supports a plurality of arms 2 and is movable in the radial direction of the medium 1, 4 - is provided at the rear end of the carriage 3 and the field device 42
5 is a position detector that detects the reproduced signal from the servo head; 6 differentiates the output A of the position detector 6 and integrates the energization signal of the drive coil 4, and calculates the difference between the two. a speed detector that obtains a speed signal B by mutual interpolation;
7 is a pulse generation circuit that shapes the output A of the position detector 5 and outputs a pulse signal C; 8 is a pulse generation circuit that is set as an initial value to the movement distance to the target position given from the control logic circuit 9, and then outputted from the pulse generation circuit 7; 10 is a compensation value circuit that is set by the output C of the pulse generation circuit 7 and integrates the output B of the speed detector 6; 11 is a D/A converter of the count output of the subtraction counter 8 and an analog circuit; A D/A converter that outputs a quantity counting signal E, 1
2 is an addition circuit 13 that outputs a sum signal F obtained by adding the output D of the correction value circuit 10 and the count signal E of the D/A converter;
14 is a nonlinear circuit that generates a target speed signal according to the sum signal F from the adder circuit 12, 14 is a subtraction circuit that outputs a difference signal between the output B of the speed detector 6 and the target speed signal from the nonlinear circuit, and 15 is a subtraction circuit that generates a target speed signal according to the sum signal F from the adder circuit 12. This is a power amplifier that amplifies the power of the difference signal from the subtraction circuit 14 and applies it to the drive coil 4.

On one surface of the medium 1, servo information consisting of odd number signals and corner number signals alternately arranged in the same circular shape at a predetermined pitch is recorded.

Therefore, the position detector 5 detects the difference between the odd number track signal component and the corner number track signal component of this servo information reproduced by the servo head, and outputs it as a servo signal A.

That is, if the servo head is located exactly between the odd numbered track and the corner numbered track, the odd numbered track signal component and the corner numbered track signal component are equal in magnitude, so the servo signal A is "0". It is. Furthermore, when the servo head deviates from this position, the servo signal A shifts in the positive or negative direction and changes almost proportionally, and if it deviates even further, it passes through a maximum or minimum value and becomes a response in the signal component of the next track.

As a result, the servo signal A becomes a sine wave as shown in FIG. 2A. By differentiating a portion of such servo signal A that is close to a straight line, highly accurate speed signals can be obtained at intervals,
A continuous speed signal is obtained by integrating the amount of current flowing through the drive coil 4, which provides an acceleration force for the carriage 3.

Therefore, the speed detector 6 interpolates between discrete speed signals obtained by differentiating the servo signal A using the integral value of the output of the current detector 16, and as shown in FIG. Outputs speed signal B.

On the other hand, regarding the signal representing the position, first the servo signal A
The pulse generation circuit 7 detects a portion close to “0” among them,
A pulse signal C shown in FIG. 2C is generated. Next, the subtraction counter 8 counts this pulse signal C, but the number of track crossings to the target stopping point is initially set in the subtraction counter 8, and the counting direction is negative.
The output E of this subtraction counter shown in Figure E represents the current position relative to the target stopping point in track numbers. In other words, this output E does not represent a position that changes smoothly. Therefore, the darkness correction value circuit 10 generates a continuous minute darkness correction value signal D shown in FIG. 20 by integrating the speed signal B every time during the period in which the operation of the subtraction counter 8 is stopped.

Then, the subtraction counter 8 via the D/A converter 11
The output E of 1 and this darkness correction value signal D are added in an adder circuit 12 to obtain a continuous position signal F shown in FIG. 2F. Thereafter, the nonlinear circuit 13 generates a target speed signal in response to the position signal F, and then the subtraction circuit 14 detects the difference between the speed signal B and the target speed signal, and the difference signal is sent to the drive coil via the power amplifier 15. 4. Now, in the speed control section as described above, the operation of the compensation value circuit 10 will now be looked at in detail.

This correction value circuit integrates the speed signal every time it crosses one track from the servo head, but the accuracy varies depending on how this integration interval is controlled and determined. In the conventional method, as shown in FIG.
, there are two slice levels SH near the 0 level,
SL is set, and the interpolation value circuit performs integration only when one slice level is higher than SH and when the other slice level is lower than SL.

In other words, a pulse signal as shown in Fig. 3C is obtained and the integral amount is reset using this, but if the accuracy near the 0 level decreases due to noise being added to the servo signal A, The disadvantage is that the integration time changes, causing errors.

Another follow-up method, as shown in Fig. 4, is to set a certain time after crossing the slice level as an integration prohibited section; in detail, the servo signal A changes from the positive side to the negative side. A signal having a pulse width of a certain period of time after crossing the slice level SH when changing from the negative side to the positive side, and a certain period of time after crossing the slice level SL when changing from the negative side to the positive side (Fig. 2C ′). In this case, there is a drawback that the ratio between the integration time and the inhibition time is not constant for each integration, and the maximum value of the integral value is not constant as shown in FIG. 4D. SUMMARY OF THE INVENTION An object of the present invention is to provide a speed control device employing a compensation value generation method that does not have the drawbacks of the conventional methods. This purpose is to provide a position reading means for generating a sine wave signal representing the local position of the movable member by reading each servo information recorded at a predetermined pitch on the running surface of the movable member, and a moving speed of the movable member. speed signal generating means for generating a signal;
A counting means for counting the output of the position argument means, a correction value generating means for integrating the moving speed signal for each section in which the contents of the counting means are unchanged, and the output of the counting means and the correction value. A speed control device comprising: an adding means for adding the output of the generating means; and a driving means for accelerating the movable member based on the deviation between the target speed determined according to the output of the adding means and the moving speed signal. The interpolation value generating means includes an integrating circuit and a pulse generating circuit that is synchronized with the operation of the counting means and generates a pulse having a variable width according to the moving speed signal, and the interpolated value generating means is provided with an integral This is achieved by controlling the integration time of the circuit, and one embodiment will be described in detail below with reference to the drawings. FIG. 5 is a diagram showing an example of the configuration of the darkness correction value circuit improved according to the present invention.

The configuration other than the darkening value circuit is as shown in FIG. 1, so the explanation thereof will be omitted.

In Fig. 5, MM is a monostable multipipulator, B
, B, C are low resistors, capacitors, and resistors for making variable the time constant that determines the output pulse width of the monostable multipipulator MM, ASW is an analog switch circuit, OPA is an operational amplifier, and R3 , R4, and C2 are resistors and capacitors forming a circuit that performs an integral operation in conjunction with the operational amplifier OPA, 20 to 22 are input terminals, and 23 is an output terminal.

A pulse signal C is applied from the pulse generating circuit 7 shown in FIG.
The monostable multipipulator MM immediately inverts the output C''.

Then, after the amount of charge or discharge of the capacitor C reaches a predetermined value, the output C'' is inverted again and returns to the original state.Now, considering the charging and discharging time of the capacitor C,
First, the capacitor C, is connected to the power supply +V via the resistor R, and is therefore charged and discharged by the current passing through the resistor R.

In addition, the capacitor C is connected to the input terminal 20 via the resistor R2.
A speed signal B is applied to this input terminal 20 from a speed detector 6 shown in FIG.

Therefore, the current passing through resistor R2 also charges and discharges capacitor C. That is, in this embodiment, the charging and discharging of the capacitor C is accelerated by the current passing through the resistor R2.

For example, if the speed signal B is large, the charging and discharging current of the capacitor C increases, and the time required for the amount of charging and discharging to reach a predetermined value decreases. In other words, the pulse width of the output pulse C'' from the monostable multipipulator MM changes in inverse proportion to the speed signal B. Therefore, the output pulse 〇' is changed to the analog switch ASW.
In addition, by controlling the opening and closing of the capacitor C2, the short-circuit time between both ends of the capacitor C2 can be made variable. Needless to say, when the analog switch ASW is open, the amount of charge in this capacitor C2 corresponds to the integral value of the speed signal B applied to the two input terminals, and the analog switch ASW
When the capacitor C2 is closed, the capacitor C2 is rapidly discharged, and the integral value (charged amount) held until then is reset.

As a result, the time required for the servo head to move the distance of one track, in other words, the analog switch The time during which the analog switch ASW is closed is controlled by the output C'' of the pipelator MM so that it is inversely proportional to the moving speed.Therefore, the analog switch ASW becomes a link, and the time for performing the integral operation is also inversely proportional to the moving speed. Then, an integral is performed every time it travels a certain distance.

Therefore, the integral value signal of the speed signal B output to the terminal 23, that is, the darkness compensation value signal D, always has a constant final value due to each integral operation.

Moreover, unlike the conventional method, the reset pulse is not obtained by the section narrowed by two slice levels SH and SL close to zero of the servo signal A, but in the present invention, the influence of noise contained in the servo signal A is avoided. It is possible to obtain stable operation by As described above, according to the present invention, it is possible to provide a speed control device with high accuracy and operational stability.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the subordinate structure of the speed control unit in a magnetic disk drive, Fig. 2 is a diagram showing the operation signals of the speed control unit shown in Fig. 1, and Figs. FIG. 5 is a diagram showing operation signals for explaining the operation of the value circuit, and FIG. 5 is a diagram showing the configuration of the interpolation value circuit according to the present invention. 5...position detector, 6...speed detector, 7...pulse creation circuit, 8...subtraction counter, 10...interpolation value Circuit, 11...
D/A converter, 12...addition circuit, 13.
...Nonlinear circuit, 14...Subtraction circuit, 1
5...Power amplifier, A...Servo signal, B...
・Speed signal, C...Pulse signal, D...
・Darkening value signal, E...Count value signal, R, ~R4
...Resistance, C, ~C ...Capacitor,
MM・・・Monostable multipipulator, ASW・
...Analog switch, OPA...Operation amplifier. Figure 1 Winter 4 Box Tomo Z diagram *3 Figure Tsutomu S diagram

Claims (1)

[Claims] 1. Position reading means that reads each servo signal recorded at a predetermined pitch on the running surface of the movable member and generates a sine wave signal representing the local position of the movable member, and speed signal generating means that generates a moving speed signal of the movable member. a counting means for counting the output of the position reading means; an interpolated value generating means for integrating the moving speed signal for each section in which the contents of the counting means remain unchanged; and an output of the counting means and the interpolated value generating means. and a driving means for accelerating and decelerating a movable member based on a deviation between a target speed determined according to the output of the adding means and the moving speed signal. The interpolated value generating means includes an integrating circuit and a pulse generating circuit that synchronizes with the operation of the counting means and generates a pulse having a variable width according to the moving speed signal, and the interpolated value generating means is provided with an integral circuit based on the output of the pulse generating circuit. A speed control device characterized by controlling the integration time of a circuit.