Stepper motor apparatus and method for controlling stepper motor

• US 20080007195A1
• Filed: 06/11/2007
• Published: 01/10/2008
• Est. Priority Date: 06/23/2006
• Status: Active Grant

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Yamada, Yoshihisa
• Granted Patent: US 7,859,216 B2
• Time in Patent Office: Days
• US Class Current: 318/696
• CPC Class Codes: G01D 2213/10 Drivers for gauges
• CPC Class Codes: G01R 7/06 moving-iron type
• CPC Class Codes: H02P 8/34 Monitoring operation H02P8/36 takes precedence

Abstract

The object of the invention is to provide a stepper motor apparatus and a method for controlling a stepper motor, and particularly relates to a stepper motor apparatus for driving a pointer and a method for controlling the stepper motor.

When an ignition switch is turned on, CPU 12 starts to feed a driving signal into the stepper motor in order to cause the stepper motor to rotate in a backward direction. Upon detecting that a protrusion 9 is in abutment with a stopper 10 on the basis of induced voltage generated on excitation coils 5 and 6, CPU stop rotation of the stepper motor 3 by maintaining the driving signal'"'"'s phase at which the abutment is detected. Subsequently, CPU 12 feeds the driving signal into the stepper motor 3 in order to drive the stepper motor 3 to rotate in a direction where the protrusion 9 is driven against the stopper 10, and then stops rotation of the stepper motor 3 in a forward direction by maintaining a predetermined phase at which the driving signal arrives. Thereafter, CPU 12 drives the stepper motor to rotate such that a pointer 1 homes in on its commanded position θi.

Claims

1. A stepper motor apparatus, including:

a stepper motor rotating in response to a driving signal, a duty cycle of which is modulated, supplied thereto in order to drive a pointer;

a stopper configured to stop rotation of the stepper motor mechanically in cases where a driven member associated with the stepper motor is in abutment therewith;

an initialization driving device configured to feed the driving signal into the stepper motor in order to drive the stepper motor to rotate in a backward direction where the driven member is driven toward the stopper;

a detection coil producing an induced voltage by means of rotation of the stepper motor;

a position detection device configured to determine whether the driven member is in abutment with the stopper or not by examining the induced voltage on the detection coil;

a first stopping device configured to stop rotation of the stepper motor in the backward direction by maintaining driving signal'"'"'s phase at which the abutment is detected by the position detection device; and

a normal driving device configured to feed the driving signal into the stepper motor in order to drive the stepper motor to rotate in a direction where the pointer homes in on its commanded position, after first stop by the first stopping device, characterized by further including;

a memory configured to store a predetermined phase;

a forward driving device configured to feed the driving signal into the stepper motor in order to drive the stepper motor to rotate in a forward direction where the driven member is driven against the stopper, after first stop by the first stopping device; and

a second stopping device configured to stop rotation of the stepper motor in the forward direction by maintaining the predetermined phase when the driving signal transmitted by the forward driving device arrives at the predetermined phase, wherein the normal driving device drives the stepper motor to rotate again after second stop by the second stopping device.

2. The stepper motor apparatus according to claim 1, further including:

a drive initiating device configured to initiate operations of both the initialization driving device and the position detection device, pursuant to a storage instruction, and

a storing device configured to store a phase, which is a predetermined phase difference out of phase with the driving signal'"'"'s phase at which the abutment is detected by the position detection device, as the predetermined phase in the memory.

3. The stepper motor apparatus according to claim 2, wherein the predetermined phase difference is 270 degrees.

4. A method for controlling a stepper motor, comprising the steps of:

(A) feeding a driving signal, a duty cycle of which is modulated, into the stepper motor in order to drive the stepper motor to rotate in a backward direction where a driven member associated with the stepper motor is driven toward a stopper;

(B) determining whether the driven member is in abutment with the driven member or not by examining an induced voltage on a detection coil resulting from the step (A);

(C) stopping rotation of the stepper motor in the backward direction by maintaining the driving signal'"'"'s phase at which the abutment is detected in step (B); and

(D) feeding the driving signal into the stepper motor in order to drive the stepper motor to rotate in a direction where a pointer, which is driven by the stepper motor, homes in on its commanded position after the step (C), in stepwise fashion, characterized by further including following steps between the step (C) and the step (D);

feeding the driving signal into the stepper motor in order to drive the stepper motor to rotate in a direction where the driven member is driven against the stopper, and subsequently

stopping rotation of the stepper motor in the forward direction by maintaining a predetermined phase when the driving signal arrives at the predetermined phase stored in a memory.

5. A method for controlling a stepper motor, comprising the steps of:

(A) feeding a driving signal, a duty cycle of which is modulated, into the stepper motor in order to drive the stepper motor to rotate in a backward direction where a driven member associated with the stepper motor is driven toward a stopper;

(B) determining whether the driven member is in abutment with the driven member or not by examining an induced voltage on a detection coil resulting from the step (A);

(C) stopping rotation of the stepper motor in the backward direction by maintaining the driving signal'"'"'s phase at which the abutment is detected in step (B); and

(D) feeding the driving signal into the stepper motor in order to drive the stepper motor to rotate in a forward direction where a pointer, which is driven by the stepper motor, homes in on its commanded position after the step (C), in stepwise fashion, characterized by further including following steps between the step (C) and the step (D);

feeding the driving signal into the stepper motor in order to drive the stepper motor to rotate an amount of phase difference between the phase as maintained in the step (C) and a predetermined phase stored in a memory, in a forward direction where the driven member is driven against the stopper, and subsequently

stopping rotation of the stepper motor in the forward direction by maintaining the predetermined phase, after completion of the afore-mentioned driving signal supply.