JPH01144398A - Drive method for stepping motor - Google Patents

Abstract

PURPOSE:To prevent an overshoot by temporarily stopping the driving voltage of a stepping motor when the preset time passes according a seek rate. CONSTITUTION:When final step pulses S2 are input, a seek rate is decided. A stepping motor is driven for a1msec after the input of the step pulses S2, the drive of the stepping motor is interrupted for b1msec, and the stepping motor is driven for 19.7msec after the input of the step pulses S2 again. Driving voltage is brought to an 'L' level when 19.7msec passes, and drive is stopped. Accordingly, no overshoot is generated, and settling is conducted completely for 19.7msec after the input of the final step pulses S2.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for driving a stepping motor.

[Conventional technology]

With the recent spread of personal computers, many disk drives are being used as external storage devices. A stepping motor is often used as a means for transporting the head device of this disk drive device.

FIG. 6 shows a magnetic head transfer device for a floppy disk drive (hereinafter referred to as FDD) using a stepping motor. In FIG. 12
The tip thereof is supported by the motor mounting plate 13. The magnetic head 14 is mounted on the tip of the carriage 15 and can move linearly along the guide shaft 16 together with the carriage 15. Also, carriage 1
5 and the lead screw 12 of the stepping motor 10 are coupled by engaging the needle pin 17 attached to the carriage 15 with the groove 1) formed in the lead screw 12, so that the rotational movement of the lead screw 12 is This is converted into a linear motion of the carriage 15. That is, in FIG. 7, the needle pin 17 is engaged with 'a1) of the lead screw 12, and by applying a constant force by the leaf spring 18 from the opposite side of this engagement part, the needle pin 17 is The mechanism is such that it does not come off from the groove 1). As the lead screw 12 rotates in the direction of arrow E, the carriage 15 equipped with the needle pin 17 moves linearly in the direction of arrow F.

FIG. 8 shows one step signal (indicated by pulse a) in the stepping motor 10 of the head transfer device shown in FIG.
This figure shows the relationship between the displacement and speed of the needle pin 17 over time when . Since the slope of the tangent to the displacement curve 19 in FIG. 8 represents the velocity, the displacement curve 19
The velocity at points P and Q above becomes zero. And point P
In the section from to point Q, the speed of the needle pin 17 is negative as can be seen from the speed curve 20 (the hatched area surrounded by the speed curve and the time axis).

If a step signal (indicated by pulse b) is further input in this section, the moving direction of the needle pin 17 and the moving direction of the lead screw 12 will be exactly opposite, and the groove 1) and the needle pin 17 will collide. As a result, a loud operating sound will be emitted. When overshoot O8 occurs in the displacement curve 19 as described above, a phenomenon occurs in which the operating noise becomes louder in a specific period of the step signal.

In an actual FDD, the period of the step signal (called the seek rate) differs depending on the usage conditions. For example, at 5.25 inches, the track density is 487 PI.
4ms to 20m5 (usually 6
m s ). Therefore, in order to minimize the operating noise during 10 rotations of the stepping motor over the entire range of these seek rates, it is necessary to obtain a displacement curve without overshoot.

Further, an example of a drive control circuit for the stepping motor 10 is shown in FIG. The figure shows a control circuit for a four-phase stepping motor. In the figure, a control circuit 1 receives a step signal 3 inputted from the outside to instruct the amount of rotation of the stepping motor 10, and instructs the direction of rotation. In response to the direxilan 4 for the purpose of the present invention, it generates the timing of the A-phase excitation signal 5 and the B-phase excitation signal 6 and outputs these excitation signals, and also generates a power save signal 7 for controlling the power supply voltage of the stepping motor 10. This is a circuit for generating and outputting. The motor driver 8 is a circuit for driving the stepping motor 2 based on the A-phase excitation signal 5, the B-phase excitation signal 6, and the power save signal 7 sent from the control circuit 1. Further, typical examples of the timing of the excitation signal include one-phase excitation, two-phase excitation, and 1-2 phase excitation.

Here, FIG. 10 shows a general waveform of the power save signal (hereinafter referred to as "100 signal") 7 in the conventional stepping motor driving method. When the PS signal is H1 in FIGS. 9 and 10, the starting voltage (for example, 12V or 5V) is applied to the stepping motor 10 at 'L'.
'', a holding voltage (for example, 5V or OV) is applied.

The ps multiplied signal is set to "H" during the period from when the step signal is input until the vibration at the time of starting the stepping motor 10 subsides, and thereafter the ps multiplied signal is set to "L" to save power.

[Problem that the invention seeks to solve]

By the way, as can be seen from FIG. 8, in the above conventional example, an overshoot O8 appears on the curve indicating the angular displacement before the rotating shaft of the stepping motor rotates and stops, so that the rotating shaft does not move as desired. It took a considerable amount of time to stabilize and stop at this angle. and,
Because of this overshoe (O3), there is a region in which the speed becomes negative, resulting in a problem that the positioning accuracy of the stop position of the rotating shaft of the stepping motor deteriorates.

This invention was made in view of the above technical background, and its purpose is to propose a method for driving a stepping motor that can exhibit excellent positioning accuracy.

[Means for solving problems]

In order to achieve the above object, the present invention provides a method for driving a stepping motor that takes one step using at least two step pulses, which detects a seek rate input to the stepping motor, and detects a step rate after inputting at least the final step pulse. The stepping motor is configured to temporarily stop when a preset time has elapsed according to the detected seek rate while the motor is being driven.

[Effect]

The above means takes into consideration the correlation between the seek rate and the torque, in that when the frequency of the seek rate is low, the time to drive the stepping motor becomes longer and the torque becomes larger.According to the above means, at least the final While the stepping motor is being driven after inputting the step pulse, the driving torque can be controlled by controlling the time from inputting the step pulse to stopping the stepping motor in accordance with the detected seek rate. In other words, when the seek rate is at a low frequency (when the seek rate value is large), the time required to turn off the stepper motor drive voltage is shortened to suppress the increase in speed, and when the seek rate is at a high frequency, (When the seek rate value is small) It is possible to make the torque the same as that of the lower seek rate.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 5 are for explaining the invention in detail. FIG. 3 is a diagram of actual sound measurement, FIG. 4 is an explanatory diagram showing the planar shape of the anechoic box used for sound measurement, and FIG. 5 is an explanatory diagram showing the side profile of the same. In the following description, components that can be considered equivalent to those of the conventional example are given the same reference numerals.

The stepping motor 10 according to the embodiment receives at least two step pulses and moves one step. The step pulse is outputted when there is a command from the personal computer and inputted to the control circuit 1 of the stepping motor 10. Control circuit 1
First, when the first step pulse SI is input, the drive voltage of the stepping motor 10 is set to the "H" level to drive the stepping motor 2 21m38c. After that, the driving voltage is set to "L" level (lower to L-OV in this case) for b, msec, and again for the same time, m
When sec has elapsed, the driving voltage is set to the 6H'' level, the stepping motor 10 is driven, and the next second step pulse S! is input.

Next, when the next second step pulse S2 is input, the time from the previous first step pulse S1 to the input of this second step pulse S2 on the control circuit 1 side is 1. Detect. This time t1 is the seek rate, and the seek rate t+ is a preset value, t+-4 in this example.
, 75 msec or less, or larger than that.

Based on this judgment, the seek rate t+ is 4.75 msec.
In the following case, for example, in the case of t, x4 msec, the stepping motor 10 is driven by a, msec from the input of the second step pulse St as shown in FIG. After interrupting the driving of the stepping motor 1, the stepping motor 1 is operated again until 19.7 msec has elapsed since the input of the second step pulse S2.
0, and when 19.7 msec has elapsed, the drive voltage is set to the "L" level and the drive is stopped. As a result, the second step pulse S! without overshooting O3 occurs. The settling is completed completely after 19.7 m sec has elapsed since the input of .

Further, the time 1° from the input of the first step pulse SI to the input of the second step pulse S2 is 4.75.
For example, when t, m5 msec is larger than m s e c, the second step pulse S
After driving the stepping motor 10 continuously for azmsec shorter than the above a1msec from the input of step 2, b, ms
ec drive is stopped, and the second step pulse S
After driving for 19.7 msec from the input of 2, the driving is stopped. As a result, when the seek rate is large, in other words, when the frequency of the seek rate is low, it takes a long time to reach the second step pulse S (although the speed of the screw shaft 12 is increased, By stopping the driving of the stepping motor 10 early after the input of the second step pulse S2, it is possible to suppress an increase in speed.In this way, by stopping the stepping motor early, It is possible to achieve a small torque equivalent to that obtained when the seek rate is low, and also prevent overshoot.

Above, driving time al+am and driving stop time,
Sb should be set appropriately according to the characteristics and drive system of the stepping motor 10, the setting time of Giclee 1+, etc. In the above embodiment, the
An example of D, specifically, for example, a,=3.2
When ms e c, b, = 0.8 ms ec, ■at = 2.5 ms e c, b, -0,9 m
s e c ■ a, w'1.7 msec, b2 = Q, 7
msec■ax -2,8ms e c, bz=Q
, 5ms e c, etc. are selected. As above, a
Fig. 3 shows actual measured values when l+b+, az, and Ig are selected and when driving is not stopped. In FIG. 3, when × is ■, O is ■, Δ is ■, and * is the conventional case. These actual measurements are based on i, -75cm in a cube of l+-120cm, which is indicated by the model number of AR-4H made by RION, as shown in Figures 4 and 5.
Place a square platform with a height l and m4.6 cm, and install an FDD in the center, horizontally 14 = 25 cm and vertically j! Measurements were taken using a microphone installed at an angle of -30° at a distance of s = 45 cm. As is clear from this figure, the seek rate is 4.75 msec.
At the above low frequencies, it was possible to reduce the sound pressure level by approximately 10 dBA.

This significant reduction in sound pressure level means that
This shows that the occurrence of overshoot has been suppressed, and it can be seen that settling occurs earlier and the torque is naturally reduced.

Therefore, according to the above embodiment, the positioning of the magnetic head 14 is performed quickly and accurately, and collision with the inner surface of the groove 1) of the lead bin 17 is suppressed, so that when the seek rate is 4.75 msec or more, The sound pressure level, which was above 50 dBA, can be reduced by approximately 10 dBA, and a quiet FDD can be provided.

〔Effect of the invention〕

As is clear from the previous explanation, the seek rate input to the stepping motor is detected, and at least while the stepping motor is being driven after inputting the final step pulse, a preset time is set according to the detected seek rate. According to this invention, the driving of the stepping motor is temporarily stopped when the time period has elapsed.Since the driving torque of the stepping motor can be controlled, overshoot can be prevented and the positioning accuracy of the rotational position of the stepping motor can be improved. be able to.

[Brief explanation of the drawing]

Figures 1 to 5 are for explaining the embodiment.
1 and 2 are explanatory diagrams showing the relationship between step pulses, drive voltages, and rotation angles of the stepping motor, respectively; FIG. 3 is an actual sound measurement diagram; and FIG. 4 is a plan view showing the sound measurement conditions. Fig. 5 is a side view of the same, Figs. 6 to 10 are for explaining the conventional example, Fig. 6 is a perspective view schematically showing the head transfer device of the FDD, and Fig. 7 is a diagram showing the needle pin and groove. 8 is an explanatory diagram showing the relationship between displacement and speed of the needle pin over time, FIG. 9 is a driving circuit diagram of the stepping motor, and FIG. 10 is a step signal and a ps multiplication signal. It is an explanatory diagram showing a relationship. 10...Stepping motor, tl...
・・・・・・Secret. Fig. 1 L7-1%+'l [m sec] Fig. 2 Clear interval [ITl 5ecl Fig. 3 4.75 10.0 20.
0 di-crate ro m secl Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 1Q

Claims (3)

[Claims] (1) In a method of driving a stepping motor that takes one step using at least two step pulses,
detecting the seek rate input to the stepping motor, and at least during driving of the stepping motor after inputting the final step pulse, according to the detected seek rate,
A method for driving a stepping motor, comprising temporarily stopping the stepping motor when a preset time has elapsed. (2) In the statement of claim (1), when the preset time elapses according to the detected seek rate is larger than the preset reference value of the seek rate, it is shorter than when it is smaller. A method for driving a stepping motor, characterized in that the stepping motor is set at a time. (3) The method for driving a stepping motor as set forth in claim (2), wherein the reference value is 4.75 msec.