JPH027898A - Head moving device - Google Patents

Abstract

PURPOSE:To reduce the hysteresis of a step motor and to improve the positional precision by stopping the motor after it is reciprocatingly driven with the target stop position as the center and within the limits not too large. CONSTITUTION:When no STEP signals are inputted, two phase signals in total, i.e., either phiA or phiC and either phiB or phiD, are fixed as the signals to be driven finally. After that, PA and PB output LOW levels for a specified period one after another until the speed of the step motor is completely stabilized. When the PA is on the LOW level, a pulse signal CHOP is introduced into a driver 4 or 5 and controls in chopping a coil 1. The step motor is thereby reciprocatingly be driven with the target stop position as the center and within the limits not too large. Finally, the excitation of two coils (1 and 2) are balanced and the stabilizing action is completed, so that the hysteresis of the motor is removed and the step motor stops.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a magnetic head moving device used in a magnetic recording device such as a floppy disk.

[Prior Art] In general, step motors are often used in head moving devices of magnetic recording devices, and in particular, in recording devices with a small track density such as floppy disks, only step motors are used. However, step motors have position errors with hysteresis, and track position errors occur when stopping due to subtle differences in load, forward and reverse directions of movement, and differences in movement speed until stopping, reducing reliability. In order to reduce this hysteresis, it is possible to reduce it by using a special control mode when the step motor is stopped, instead of using an expensive step motor or passing a large drive current.

- For example, in the conventional example of Utility Model Application Laid-Open No. 60-160096, a mode is proposed in which the vibration is made into the front and rear phases when stopped.

[Problems to be Solved by the Invention] However, the method of vibrating the excitation phase of the step motor back and forth when stopped, as in the conventional example above, is extremely critical and is most effective when the type of step motor is selected. The effect cannot be obtained unless the vibration is made at regular time intervals, and if the time pattern is inappropriate, there is a risk that it will have the opposite effect and increase hysteresis. Therefore, due to the above-mentioned problem, it becomes difficult to generalize the excitation phase switching means of the step motor when it is integrated into an IC. Furthermore, considering another problem, it is necessary to prepare a vibration pattern for each final stop phase combination (it is necessary to prepare a storage section for forming vibration patterns).
ROM) becomes complicated. The above invention is intended to solve the above problems, and aims to realize a head movement control circuit that reduces hysteresis with non-critical characteristics and can be constructed relatively easily.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention does not take a large rotation angle that would cause vibration to the phases before and after the stop phase, but instead rotates a part of one step around the final target stop position. It vibrates between 1 and 2. - In the previous section, a 4-phase, 2-excitation step motor is used, and one cycle is made up of 4 steps, and two coils are excited and then stopped.The present invention allows these two coils, which are finally stopped, to be independent of each other. It is characterized in that it performs chopping control to effectively control strong and weak excitation.

[Function] In the above configuration of the present invention, after the step motor sends the head to the target track, the step motor changes the balance between the excitation forces of the two coils while being fixed at the excitation phase where it finally stops. →Can be changed to weak and strong.

As a result, the step motor reciprocates within a range that is not too large around the desired stop position, and finally balances the excitation of the two coils to complete the settling operation, eliminates hysteresis, and stops.

[Example] The present invention will be described in detail below based on examples.

FIG. 1 is a circuit diagram of a head moving device according to an embodiment of the present invention. 1 and 2 are the two windings of the step motor, each with 2 windings.
It has two phase coils, and the midpoint is the power terminal. 3 receives the movement command 5TEP from the host device and the movement direction command DIR at that time, and drives the step motor by pulsing the excitation phase signal of the step motor, the strength of the power supply terminal voltage, and each pair of phase signals one by one. This is an excitation control circuit that performs chopping control to reduce the effective value of force. 4 to 7 are the excitation phase signal outputs φ6 to φ of 3. 8 is an AND-type driver that switches the phase of the step motor coil based on the received signal, and 8 is the output PA and P from 3 that instructs the strength of the coils 1 and 2, respectively.
This is an OR type driver that switches the strength of the step motor in response to . The step motor is strong when moving and stopping.
When stationary, it becomes weaker, reducing power consumption and heat generation. This strong/weak switching is made up of a transistor 10, a base resistor 9, a limiting resistor 11, and a noise absorbing capacitor 12 when the transistor switches. Signal 5TEP and DIR
When is input, the transistor 10 is turned on, and φ, to φ.

are switched sequentially and the step motor rotates. 5TEP
When the signal is no longer input, φ and φ. Either of these and φ
6 and φ. Any two phase signals among them are fixed as the final driven signals. After that, until the step motor is completely settled, PA and pH are kept at L for a certain period of time.
Outputs OW level. When PA is at the LOW level, a pulse signal CHOP is introduced into the driver 4 or 5 by the gate 13 to chop the coil 1. When P is at the LOW level, the gate 14 similarly controls the coil 2 by chopping. PA that is a combination other than the above
=pa =HIGH level is seeking, PA
=P B=LOW level is a mode in which excitation is weak during rest. In the present invention, the reduction in driving force can be arbitrarily determined by the duty of CHOP.

In particular, since it can be determined independently of the driving force generated by the resistor 11 when it is stationary, it is very effective in eliminating hysteresis by changing the balance of the effective driving force due to chopping in eleven directions.

Figure 2 shows step motor phases φ1 to φ. FIG. 3 is a phase switching explanatory diagram showing how the switching is performed.

Double circles indicate strong excitation by PA or P, -1 circle indicates weak excitation by chopping, one track movement is achieved by one step of the step motor, and the left side of the dotted line is from track 00 to track Movement to φ1,
The right side shows movement from track 02 to track 01. T represents the timing of the final movement, and T2 to T6 represent the timing of each strength change during settling. In FIG. 2, after moving to track φl, φ. Strong excitation of φ8 is repeated twice, and φ at T6. and φ are both strongly excited and then shift to the holding mode.

FIG. 3 is a rotation change diagram showing how the rotation of the step motor is changed by the operation shown in the phase switching λ explanatory diagram of FIG. 2. FIG. Ultimately, whether moving from track 00 or track 02 to track 01, it is accurately settled without hysteresis.

FIG. 4 is a circuit showing the excitation control circuit 3 of FIG. 1 in detail. D-type flip-flops (hereinafter referred to as FF) 21.22 and exclusive OR gates 23.24 receive excitation phase signals φ6 to φ. form.

On the other hand, it starts with the 5TEP signal, and the 6TEP signal C
Timer 2 that sequentially forms timings T, ~T6 based on K
0 and gates 25 to 35 to generate excitation strength signals PA and P.
5 is formed. There is no need to use a ROM and it can be configured simply with a few gates.

FIG. 5 is a timing chart showing outputs T1 to T6 of the timer 20 in FIG. 4. The timer 20 is initialized every time 5TEP signal is input, so 5TEP signal is input at regular intervals.
If the signal is continuously input, T1 will be maintained and therefore P
A and Pg will also continue to be strongly excited.

[Effects of the Invention] As described above, the present invention can reduce the hysteresis of the step motor with a relatively simple circuit configuration, and can realize a head moving device with high positional accuracy. By using the present invention, a special mode timing for reducing hysteresis can be set without being greatly affected by the characteristics of the step motor, so it is highly versatile and can be easily integrated into an IC.

Further, in the present invention, all the control circuits for reducing hysteresis can be integrated into a logic circuit, and the hardware of the power control circuit can be the same as the conventional one. Therefore, it has the great advantage that it can be handled by changing the control IC.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a head moving device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of phase switching λ for explaining the operation of FIG. 1. FIG. 3 is a diagram showing changes in rotation of a step motor showing the effects of the present invention. Figure 4 is a detailed circuit diagram of the excitation control circuit 3 in Figure 1;
The figure is a timing chart diagram of the timer 20 in FIG. 4. l, 2...Step motor coils 4 to 8...Driver and above

Claims (1)

[Claims] In a head moving device consisting of a step motor for moving the head and excitation phase switching means for reversibly rotating the step motor by switching the phase of the step motor coil, a pair of step motors are finally driven when the step motor is stopped. A head moving device characterized by pulsing the phase signals of the coils one by one to reduce the effective value of the driving force and then stopping the head moving device.