JPH0888997A - Step motor driving device and head moving device - Google Patents

Abstract

PURPOSE: To reduce hysteresis in characteristics, which are not critical, by performing the switching of the exciting strength of a step-motor driving means when the step motor is stopped at a different pattern for every step motor coil, and performing settling. CONSTITUTION: When signals DIR and STEP are inputted into an exciting control circuit 3, transistors 10 and 11 are both turned ON, exciting-phase signal outputs ϕA-ϕD of the exciting control circuit 3 are sequentially switched and a step motor is rotated. When the step motor is stopped, the STEP signal is not inputted and fixed to the total of two phase signals of any of the exciting- phase signal outputs ϕA and ϕC and any of the exciting-phase signal outputs ϕB and ϕD. Then, the strong and weak signal outputs PA and PB are alternately switched and step motor coils 1 and 2 perform the small oscillation. Finally both strong and weak signal outputs PA and PB are strongly excited and settled. Thus, the hysteresis of the step motor can e reduced, and the head moving device having the excellent position accuracy can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head moving device used in a magnetic recording device such as a floppy disk.

[0002]

2. Description of the Related Art Generally, a step motor is often used in a head moving device of a magnetic recording device, and particularly in a recording device having a small track density such as a floppy disk, almost only a step motor can be said. However, there is a position error with hysteresis in the step motor,
Due to a subtle difference in load, forward / reverse of the moving direction up to the stop, and a difference in moving speed, a track position error is generated at the time of stop and reliability is lowered. In order to reduce this hysteresis, it is also possible to use an expensive stepping motor or a method of flowing a large driving current excessively, or a method of reducing it by a special control mode when the stepping motor is stopped. As an example, in the conventional example of Japanese Utility Model Laid-Open No. 60-160096, a mode of vibrating to the front and rear phases when stopped is proposed.

[0003]

However, the method of oscillating the excitation phase of the step motor back and forth when stopped as in the above-mentioned conventional example is very critical, and is the most effective in selecting the kind of the step motor. The effect cannot be obtained unless it is vibrated at regular time intervals. Further, in the case of an improper time pattern, there is a risk of adverse effects and increasing hysteresis. Therefore, due to the above problems, it is difficult to generalize the excitation phase switching means of the step motor into an IC. Furthermore, as another problem, it is necessary to prepare a vibration pattern at the time of stop for each final combination of stop phases, and the storage unit (ROM) for forming the vibration pattern becomes complicated.
The above invention solves the above problems, and an object thereof is to realize a control circuit for moving a head, which has a non-critical characteristic to reduce hysteresis and which can be configured relatively easily.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention does not take a large rotation angle such as oscillating to a phase before and after a stop phase but a number of steps corresponding to one step around a stop position of a final purpose. It vibrates between one-half. In general, a step motor of 4-phase 2-excitation is used as a step motor, and one cycle is formed by four steps, and two coils are excited and stopped. The present invention finally stops 2
The feature is that the two coils are independently controlled for strong and weak excitation.

[0005]

In the above-described structure of the present invention, the step motor feeds the head to the target track and then balances the exciting forces of the two coils while being fixed to the exciting phase that finally stops. It can be changed from strong to weak. As a result, the restepping motor reciprocates about the target stop position within a range that is not too large, and finally the excitation of the two coils is balanced to end the settling operation, and the hysteresis is removed to stop.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A detailed description of the present invention will be given below based on Examples.

FIG. 1 is a circuit diagram of a head moving device according to an embodiment of the present invention. Reference numerals 1 and 2 are two windings of the step motor, each having two phase coils, and the middle point is a power supply terminal. Reference numeral 3 denotes an excitation control circuit that receives a movement instruction STEP from the host device and a movement direction instruction DIR at that time to form an excitation phase signal and an excitation strength signal of the step motor. Reference numerals 4 to 7 are drivers for switching the phase of the step motor coil by receiving the excitation phase signal outputs φ _{A to} φ _D of 3, and 8 and 9 are step motor driving transistors 10 receiving the strong and weak signal outputs P _A and P _B of 3. And 11 for driving. When the excitation is strong, the transistors 10 and 11 are turned on, and when the excitation is weak, they are excited through the limiting resistors 13 and 16. Reference numerals 12 and 15 are base resistors, and 14 and 17 are noise absorbing capacitors when switching the transistor.

When the signals DIR and STEP are input, both the transistors 10 and 11 are turned on, φ _A to φ _D are sequentially switched, and the step motor is rotated. When the STEP signal is no longer input, it is fixed to a total of two phase signals of either φ _A or φ _C or φ _B and φ _D. And P _A
And P _B are alternately switched, and the step motor coils 1 and 2 make a small vibration, and finally P _A and P _B are both strongly excited and settling is completed, and then both P _A and P _B are turned off and weak. Excited and enters hold mode. Compared to the conventional general step motor driving means, transistors 10 and 1
The re-stepping motor coils 1 and 2 of which 1 is a separate series can be separately switched between strong and weak excitation.

FIG. 2 is a phase switching explanatory view showing how the stepping motor phases φ _{A to} φ _D are switched. Double circles indicate strong excitation by P _A or P _B , and single circles indicate weak excitation. The movement of one track is made by one step of the step motor, and the left side of the dotted line is track 0.
The movement from 0 to the track 01, the right side shows the movement from the track 02 to the track 01. T ₁ represents the timing of the final movement, and T _{2 to} T ₆ represent the timing of each strength change during settling. In FIG. 2, after moving to the track 01, strong excitation of φ _C → strong excitation of φ _B is repeated twice, and T
_{At 6} , both φ _C and φ _B are strongly excited, and then the holding mode is entered.

FIG. 3 is a rotation change diagram showing a state in which the rotation of the step motor is changed by the operation shown in the phase switching explanatory diagram of FIG. Eventually track 0
Whether the track 0 or the track 02 is moved to the track 01, the setting is accurately performed 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 and 22 and exclusive OR gates 23 and 24 form excitation phase signals φ _{A to} φ _D. On the other hand, a timer 20 which starts with a STEP signal and sequentially forms timings T _{1 to} T ₆ with a clock signal CK and gates 25 to 3
5, the strong and weak signals P _A and P _{B of} excitation are formed. R
There is no need to use an OM, and the configuration can be made simply with a small number of gates.

FIG. 5 shows outputs T _{1 to} T ₆ of the timer 20 shown in FIG.
It is a timing chart figure which shows. Timer 20 is ST
Since it is initialized every time the EP signal is input, T ₁ is held if the STEP signal is continuously input at a constant interval,
Therefore, P _A and P _B are also continued with strong excitation.

[0013]

As described above, according to the present invention, it is possible to realize a head moving apparatus having a relatively simple circuit structure and capable of reducing the hysteresis of the step motor and having a high positional accuracy. Further, in the present invention, the timing of the vibration mode of the hysteresis reduction can be set without being largely influenced by the characteristics of the step motor, so that the versatility is high and the IC can be easily formed. Further, as another advantage of the present invention, when the rotation of the step motor is slow, that is, when the step input interval is long, the step motor does not move smoothly and the noise problem that occurs can be reduced. This is because the excitation enters a mode in which the excitation becomes weak after a certain period of time after the input of STEP, so that the power of the step motor also weakens and the amplitude of free vibration that is a source of noise also decreases. As described above, according to the present invention, a head moving device having good characteristics can be obtained without using an expensive step motor, and a great effect can be produced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a head moving device that is an embodiment of the present invention.

2 is a phase switching explanatory diagram for explaining the operation of FIG. 1. FIG.

FIG. 3 is a rotation change diagram of a step motor showing effects of the present invention.

FIG. 4 is a detailed circuit diagram of the excitation control circuit 3 shown in FIG.

5 is a timing chart of the timer 20 in FIG.

[Explanation of symbols]

 1, 2 ... Step motor coil 4-9 ... Driver 10, 11 ... Excitation strength / weakness drive transistor

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 11, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Step motor driving device and head moving device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor driving device used in a magnetic recording device such as a floppy disk and a magnetic head moving device using the same.

[0002]

2. Description of the Related Art Generally, a step motor is often used in a head moving device of a magnetic recording device, and particularly in a recording device having a small track density such as a floppy disk, almost only a step motor can be said. However, there is a position error with hysteresis in the step motor,
Due to a subtle difference in load, forward / reverse of the moving direction up to the stop, and a difference in moving speed, a track position error is generated at the time of stop and reliability is lowered. In order to reduce this hysteresis, it is also possible to use an expensive stepping motor or a method of flowing a large driving current excessively, or a method of reducing it by a special control mode when the stepping motor is stopped. As an example, in the conventional example of Japanese Utility Model Laid-Open No. 60-160096, a mode of vibrating to the front and rear phases when stopped is proposed.

[0003]

However, the method of oscillating the excitation phase of the step motor back and forth when stopped as in the above-mentioned conventional example is very critical, and is the most effective in selecting the kind of the step motor. The effect cannot be obtained unless it is vibrated at regular time intervals. Further, in the case of an improper time pattern, there is a risk of adverse effects and increasing hysteresis. Therefore, due to the above problems, it is difficult to generalize the excitation phase switching means of the step motor into an IC. Furthermore, as another problem, it is necessary to prepare a vibration pattern at the time of stop for each final combination of stop phases, and the storage unit (ROM) for forming the vibration pattern becomes complicated.
The above invention solves the above problems, and an object thereof is to realize a control circuit for moving a head, which has a non-critical characteristic to reduce hysteresis and which can be configured relatively easily.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention does not take a large rotation angle such as oscillating to a phase before and after a stop phase but a number of steps corresponding to one step around a stop position of a final purpose. It vibrates between one-half. In general, a step motor of 4-phase 2-excitation is used as a step motor, and one cycle is formed by four steps, and two coils are excited and stopped. The present invention finally stops 2
The feature is that the two coils are independently controlled for strong and weak excitation.

[0005]

In the above-described structure of the present invention, the step motor feeds the head to the target track and then balances the exciting forces of the two coils while being fixed to the exciting phase that finally stops. It can be changed from strong to weak. As a result, the restepping motor reciprocates about the target stop position within a range that is not too large, and finally the excitation of the two coils is balanced to end the settling operation, and the hysteresis is removed to stop.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a circuit diagram of a head moving device according to an embodiment of the present invention. Reference numerals 1 and 2 are two windings of the step motor, each having two phase coils, and the middle point is the power supply terminal. An excitation control circuit 3 receives the movement command signal STEP from the host device and the movement direction command signal DIR at that time, and forms an excitation phase signal and an excitation strength signal of the step motor. 4 to 7 are drivers for receiving the excitation phase signal outputs φ _{A to} φ _D of 3 and switching the phase of the step motor coil.
Reference numerals 8 and 9 denote drivers for receiving the strong and weak signal outputs P _A and P _B of 3 and driving the step motor drive transistors 10 and 11. Transistors 10 and 11 are ON when the excitation is strong
However, when it is weak, it is excited through the limiting resistors 13 and 16.
Reference numerals 12 and 15 are base resistors, and 14 and 17 are noise absorbing capacitors when switching the transistors.

When the signals DIR and STEP are input, both the transistors 10 and 11 are turned on, φ _A to φ _D are sequentially switched, and the step motor is rotated. When the signal STEP is no longer input, it is fixed to a total of two phase signals of either φ _A or φ _C and φ _B or φ _D. And P _A
And P _B are alternately switched, and the step motor coils 1 and 2 make a small vibration, and finally P _A and P _B are both strongly excited and settling is completed, and then both P _A and P _B are turned off and weak. It becomes excited and enters the holding mode. Compared with the conventional general step motor driving means, transistors 10 and 11
Is a separate series, and the excitation of the step motor coils 1 and 2 can be switched between strong and weak separately.

FIG. 2 is a phase switching explanatory view showing how the stepping motor phases φ _{A to} φ _D are switched. Double circle indicates the state of strong excitation by P _A or P _B ,
Single circle indicates weak excitation. The movement of one track is performed by one step of the step motor, and the left side of the dotted line shows the movement from the track 00 to the track 01, and the right side shows the movement from the track 02 to the track 01. T ₁ represents the timing of the final movement, and T _{2 to} T ₆ represent the timing of each strength change during settling. In FIG. 2, after the magnetic head is moved to the track 01, the strong excitation of φ _C → the strong excitation of φ _B is repeated twice, and after both φ _C and φ _B are strongly excited at T ₆ , the magnetic head is held. The transition to the mode is shown. In the holding mode, since weak excitation currents are supplied to both φC and φB, when the rotation of the step motor is slow, that is, the signal S
When the TEP input interval is long, it is possible to reduce the noise problem caused by the smooth movement of the step motor. This is because the excitation enters a mode in which the excitation becomes weak after a certain time elapses after the signal STEP is input, so that the power of the step motor is weakened and the amplitude of free vibration that is a source of noise is reduced.

FIG. 3 is an explanatory view showing a state in which the rotation of the step motor is changed by the phase switching drive shown in FIG. Eventually, no matter whether the track 00 or the track 02 is moved to the track 01, the settling is accurately performed without hysteresis.

FIG. 4 is a circuit diagram showing in detail the excitation control circuit 3 of FIG. D-type flip-flop 2
1, 22 and exclusive OR gates 23, 24 are excitation phase signal φ _A
~ ~ _D is formed. On the other hand, it is started by the input of the signal STEP, and sequentially timing T ₁ by the clock signal CK.
The timer 20 and the gate 25 to 35 for forming a through T _6, intensity signals P _A and P _B of the excitation are formed. There is no need to use a ROM, and it can be configured simply with a few gates.

FIG. 5 shows outputs T _{1 to} T of the timer 20 shown in FIG.
FIG. ₆ is a timing chart showing ₆ ; Timer 20 is S
Since the TEP signal is initialized every time it is input, if the signal STEP is continuously input at a constant interval, T ₁ is held, and thus P _A and P _B are also continuously excited.

[0013]

As described above, according to the step motor driving device of the present invention, the hysteresis of the step motor can be reduced with a simple circuit configuration, and a head moving device with good position accuracy can be realized. . Further, according to the step motor drive device of the present invention, the timing of the vibration mode of hysteresis reduction can be set without being largely influenced by the characteristics of the step motor, so that it is versatile and can be easily integrated into an IC. Therefore, it is possible to obtain a head moving device having good characteristics without using an expensive step motor.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a step motor drive device of the present invention.

FIG. 2 is an explanatory diagram of phase switching when driving a step motor using the circuit of FIG.

FIG. 3 is an explanatory view showing a state in which the rotation of the step motor is changed by the step motor driving device of the present invention.

FIG. 4 is a detailed circuit diagram of the excitation control circuit 3 shown in FIG.

5 is a timing chart of the timer 20 in FIG.

[Explanation of reference signs] 1, 2 ... Step motor coil 4-9 ...- Driver 10, 11-.

Claims (1)

[Claims] 1. A step motor for head movement, excitation phase switching means for reversibly rotating the step motor by switching the phase of the step motor coil, and excitation of the step motor coil is switched between strong and weak to drive the step motor. In a head moving device composed of step motor driving means, when the step motor is stopped, the excitation intensity of the step motor driving means is switched in a different pattern for each step motor coil for settling. Moving device.