JPH0289262A - Positioning device - Google Patents

Abstract

PURPOSE:To attain stable speed control by providing the title device with a speed profile table for always showing a trapezoidal shape independently of the number of strokes and forming a constant speed area between the accelerating area and decelerating area of a motor. CONSTITUTION:A microcomputer 4 stores a command value for controlling a speed in seeking as the table of a difference (the number of residual tracks to be seeked) between the number of tracks to be seeked and the number of tracks practically driven in the form of a speed profile. Since the speed profile table stored in the microcomputer 4 is always trapazoidal shape independently of the number of strokes, the speed command value is applied to a motor driving/controlling circuit 6 through a D/A converter 5. Thereby, the current interference of acceleration/deceleration can be suppressed by always forming a constant speed area by speed control independently of the length of a stroke and the generation of residual vibration can be suppressed at the end of seeking. Consequently, stable rapid access can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a positioning device for moving a magnetic head onto a desired track on a magnetic disk in a magnetic recording/reproducing device or the like.

(Prior Art) Conventionally, a positioning device for moving a magnetic head onto a desired track on a magnetic disk is configured as shown in FIG. First, the number of tracks that have been moved is counted from the position signal, and the microcomputer (hereinafter referred to as microcomputer) 4 calculates the remaining number of tracks to be sought ((number of tracks to be sought) - (number of tracks that have already been moved) according to the stored speed profile table. Outputs the speed command value according to the number of tracks)). The D/A converter 5 converts the speed command value into an analog signal and outputs it to the motor drive/control port "J".
Output to Pt6. The motor drive/control circuit 6 converts the analog signal into a current to control the speed of the positioning motor 7. The speed profile table stored in the microcomputer 4 has time on the horizontal axis and speed on the vertical axis, as shown in Figure 3, and when there are many tracks to move, the seek pattern is trapezoidal. With this speed profile, seek when the number of tracks to be moved is small is a triangular speed profile, and speed control is performed to drive each.

(Problem M to be solved by the invention) However, in the conventional positioning device described above, in the case of speed control such as the trapezoidal drive in FIG.
As shown in the figure, the motor current waveform becomes a stable current waveform with a constant speed (maximum speed) region between the acceleration region and the deceleration region, and the motor movement is stable, but it is driven in a triangular shape. In the case of speed control, acceleration and deceleration change rapidly, and as shown in Figure 5, the motor current waveform also tends to vibrate as the acceleration and deceleration currents interfere with each other. There are problems in that the movement becomes unstable, the residual vibration at the end of the seek becomes longer, and unstable phenomena such as oscillation are more likely to occur.

The present invention solves these conventional problems, and aims to provide an excellent positioning device that can perform stable speed control regardless of the number of moving tracks.

(Means for Solving Problem 8) In order to achieve the above object, the present invention is designed so that the velocity profile always becomes trapezoidal depending on the stroke, as shown in FIG. Equipped with a speed profile table that allows constant speed (maximum speed) between the acceleration and deceleration regions of the motor.
It is designed to provide an area.

(Function) Therefore, according to the present invention, by always providing a constant speed range regardless of the length of the stroke in speed control, current interference during acceleration and deceleration can be prevented, and residual vibration at the end of seek can be prevented. This has the effect of making stable and high-speed access possible.

(Example) FIG. 1 shows a speed profile of an example of the present invention. In addition, as for the circuit configuration.

FIG. 2 can be applied as is. Therefore, the microcomputer 4 uses a table of the difference between the number of tracks to be sought and the number of tracks that have actually moved (the remaining number of tracks to be sought) as a command value for speed control during seek as shown in FIG. It is memorized in the form of a speed profile. 5 is microcomputer 4
D/ which converts the speed control command value from
A converter.

6 is a motor drive/control circuit that converts this analog signal into a drive current, 7 is a positioning motor (DC servo motor) that moves the magnetic head to a desired track, and 8 is an encoder ( (optical 1-phase encoder).

In this way, in this embodiment, the speed profile table stored in the microcomputer 4 is as shown in FIG.
Since it always has a trapezoidal shape regardless of the stroke size, the speed command value is given to the motor drive/control circuit 6 via the D/A converter 5, and as a result, the current flowing to the motor 7 is The current waveform becomes as shown in the figure, and the motor 7 receives stable speed control.

(Effects of the Invention) As is clear from the above examples, the present invention has the following effects.

(1) Since acceleration and deceleration are prevented from switching suddenly, stable speed control is possible without interference from the motor current.

(2) Since motor current interference is less likely to occur, unstable phenomena such as residual vibrations remaining at the end of seek or oscillation do not occur.

(3) As for the average access time, since the seek is originally a long stroke (1/3 of the total stroke), it often results in a trapezoidal drive, and therefore, due to item (1) above, the movement takes longer. According to the above-mentioned item (2), the settling time is shortened, the access time is also shortened overall, and stable speed control is possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the speed profile of an embodiment of the present invention, FIG. 2 is a block diagram showing the circuit configuration of the positioning device, FIG. 3 is a diagram showing the speed profile of a conventional example, and FIG. 5 is a motor drive current waveform diagram when the motor has a constant speed region, and FIG. 5 is a motor drive current waveform diagram when the motor does not have a constant speed region. 1...Media, 2...Servo signal detection means (
(including head), 3... A/D converter, 4
...Microcomputer, 5 ...D/A converter, 6...
・Motor drive/control circuit, 7...Positioning motor, 8...Encoder. Patent applicant: Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Scope of Claims] Servo signal detection means including a magnetic head that detects a servo signal recorded on a medium, an A/D converter that converts the detected servo signal into a digital signal, and an off-track amount from the digital signal. a microcomputer and a D/A converter that calculate the off-track amount, output a correction value for the off-track amount, and output a command value for speed control during seek, and a D/A converter that moves the magnetic head to a desired track. It is equipped with a positioning motor such as a DC servo motor or a voice coil motor, and a means for driving and controlling the motor, and a speed profile table built into the microcomputer always maintains the acceleration range and constant of the motor regardless of the size of the stroke. A positioning device characterized by having a trapezoidal profile consisting of a speed region and a deceleration region.