JPS63262099A - Positioning mechanism and positioning method - Google Patents

Abstract

PURPOSE:To maintain the stopping position of an element to be driven irrespective of the rotating direction of a stepping motor by bringing the value of 1/2 of the hysteresis of the motor into coincidence with a positioning error. CONSTITUTION:When a magnetic head is converged toward a stopping position in a vibrating state by a final positioning pulse to a stepping motor, a speed for the head to move to its stopping position is maintained the same irrespective of the normal or reverse rotation of the motor. Thus, 1/2 of the hysteresis deltaof the motor is brought into coincidence with the positioning error f0/k. Thus, the stopping position after the motor is vibrated can coincide with an ideal position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning mechanism and a positioning method using a step motor, and more particularly to a positioning mechanism and method suitable for magnetic disk drives and the like.

[Conventional technology]

Conventional magnetic disk devices and floppy disk devices that use a step motor as the driving source for their positioning mechanism are equipped with a method such as that described in Japanese Patent Application Laid-Open No. 58-29597 in order to eliminate hysteresis of the step motor as the track density increases. A unidirectional excitation method was used. In addition, since this alone is insufficient in terms of positioning accuracy,
! A method of temporarily stopping before the target position as described in Publication No. 1 is also disclosed. However, in both cases, the configuration logic was complicated and insufficient consideration was given to increasing access time.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account shortening of the access time of the positioning mechanism, and there is a problem in that there is a difference in access time depending on the direction of movement.

It is an object of the present invention to shorten access time and solve the difference in access time depending on the direction of movement, while maintaining and improving positioning accuracy.

[Means for solving problems]

The above purpose is to control the speed at which the magnetic head enters the stop position, regardless of whether the step motor rotates forward or backward, when the magnetic head converges in a vibrating state towards the stop position due to the final positioning pulse to the step motor. The energy applied to the step motor (applied voltage or time) or the mechanical frictional force associated with the positioning mechanism is controlled.

This allows the center of the hysteresis of the step motor to be the stopping position of the magnetic head.

[Effect]

The movement trajectory of the step motor (or magnetic head) that follows the pulse corresponding to the final movement command during positioning of the positioning system by the step motor is modeled as shown in Figure 4, and is expressed as m"i + px + kx f, 111100 formula. The equation of motion holds true (however, ±fo changes depending on the sign of X).

(2) Solve the equation with x = mO at t-0, and μm of O groups at x-~0 (and when the total becomes 10, when X≦±τ, it stops.

At this time, if the moving directions are different (jc -?O or all"' - -o), the stopping position t will be near 1., , , - f-a/C, and approximately However, controlling the vibration convergence conditions of the positioning system, L
.

Even if the direction of movement is different, it is possible to stop at X or X-+, and positioning accuracy can be maintained even if the direction of movement is different. This control of vibration convergence conditions is achieved by matching the center of hysteresis caused by different moving directions of the step motor with the positional error that occurs when positioning the magnetic head.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 7 is a diagram showing the configuration of a flexible disk device. This mechanism consists of a recording medium 2 enclosing a rotating disk 1, a magnetic head 4 for recording and reproducing information on a concentric recording track 3 provided on one surface of the disk, and a magnetic head 4 for positioning the magnetic head 4 on the recording track 3. step motor 5
, a band 6 that converts the rotational motion of the step motor 5 into linear motion of the magnetic head 4, a pulley 7, and the magnetic head 4.
It consists of a carriage 8 on which is mounted, and two guide rails 9 that guide the carriage 8.

Further, in order to determine the above-mentioned dynamic frictional force f, the carriage 8 has a structure in which a friction piece 11 is pressed against the guide rail 9 via a fixed spring 10. As described above, the rotational interlocking and positioning of the step motor 5 correspond to the linear movement and positioning of the magnetic head 4.

FIG. 1 is a diagram showing a step motor movement command in which the step motor 5 rotates and the magnetic heald 4 moves by a pulse input to the drive circuit of the step motor 5, and the step motor movement locus that follows the command over time. . FIG. 3 shows a detailed view of portions A and BC in FIG. 1, and shows the positioning state of the magnetic head 4 over time after vibration.

Figures 3 (A) and (C) show that the movement locus shows damped oscillation in response to the step motor movement command, and the movement trajectory is approximately 6 cycles long.
In contrast, it is shown that the positioning is performed with an error of (÷-4:'). Further, when positioning is performed from the opposite direction (B), a positioning error of (δ-word) occurs as a result of the ideal position, contrary to the above, due to the difference in the moving direction.

In contrast, in this embodiment, for example, FIG.

As shown in FIG. 6 (detailed view of the fifth drawing section), the above formula (1)
By varying f, the stopping position of the magnetic head 4 after vibration is made to coincide with the ideal position. Specifically, as shown in FIG. 2, it is shown that if the step motor and the magnetic head are set to match, the stop position of the magnetic head can be made to match the ideal position.

The above embodiment deals with the dynamic friction force of the magnetic head support system, but this embodiment describes the positioning of the magnetic head by the step motor by varying the restoring torque constant of the step motor, that is, the voltage applied to the step motor. However, the same method as described above can also be used to improve the positioning of other driven objects, such as robots, machine tools, etc., where positioning errors due to movement directions are a problem.

〔Effect of the invention〕

According to the present invention, the stop position of the driven body by the step motor can be made constant regardless of the rotational direction of the step motor, resulting in the effect of improving positioning accuracy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the movement command and movement locus of a step motor according to an embodiment of the present invention, FIG. 2 is a diagram showing the stopped state of the step motor, which is the details of the ABC part in FIG. 1, and FIG. , FIG. 4 is an explanatory diagram for explaining the present invention in detail, FIG. 5 is a diagram showing stop position variation with respect to frictional load, and FIG.
The figure is a detailed view of the D section in FIG. 5, and FIG. 7 is a perspective view showing the configuration of the magnetic disk device. 1°...Disk, 4...Magnetic head, 5...Step motor, 7...Pulley, 8...Carriage, 9
... Guide rail, 10 ... Spring, 11 ... Friction piece, m ... Magnetic head mass, μ ... Viscous damping coefficient,
Hmm...restoring torque constant of the step motor, f...
Dynamic friction force of the magnetic head support system, X...Displacement. Representative Patent Attorney Masaru Ogawa 2nd time, 5th time'? IIIJ Imaushi 4th flash 'm: To magnetism, do I71 true 1 μm a□ To Ki... Do support and zubushibu Y-Sekau! 31
1:、No viscous strength and torque: Step (-。 。 。 。 。 。 。

Claims (2)

[Claims] (1) In a positioning method of a positioning mechanism consisting of a step motor and a driven body driven and positioned by the step motor, the direction of movement of the driven body just before it stops is caused by damped vibration of the driven body in response to the final positioning pulse. A positioning method characterized in that the direction of movement of a driven object is the same as the direction of movement of a driven body corresponding to one or more movement commands given to a step motor. (2) In a positioning mechanism consisting of a step motor, a driven object that is driven and positioned by the step motor, and a support structure that supports the driven object, immediately before it stops due to damped vibration of the driven object in response to the final positioning pulse. means for making the moving direction of the driven body the same in response to one or more movement commands given to the step motor; A positioning mechanism characterized by having means for setting a value obtained by dividing a holding force of a driven body due to a holding torque to 1/2 of a hysteresis amount of a step motor.