Step motor drive circuit and analog electronic timepiece

• US 20070188124A1
• Filed: 02/06/2007
• Published: 08/16/2007
• Est. Priority Date: 02/15/2006
• Status: Active Grant

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Ogasawara, Kenji, Shibuya, Yoshihiro
• Granted Patent: US 7,538,513 B2
• Time in Patent Office: Days
• US Class Current: 318/696
• CPC Class Codes: H02P 8/16 Reducing energy dissipated or supplied

Abstract

To be able to supply a large drive current to a motor and to be able to downside the motor. In driving to rotate a motor, a first drive cycle of driving transistors to an ON state and driving transistors to an OFF state, and a second drive cycle of driving the transistors to the ON state and driving the transistors to the OFF state are carried out alternately, and in braking the motor provided at an interval between times of driving to rotate the motor, the transistors are driven to the ON state, the transistors are driven to the OFF state. A large drive current is made to be able to supply to the motor and the motor is made to be able to be downsized by using the transistors for driving the motor and for electrostatic resistance.

Claims

1. A step motor drive circuit characterized in a step motor drive circuit comprising:

a first transistor pair comprising a first and a second transistor;

a second transistor pair comprising a third and a fourth transistor; and

driving means for rotating a step motor in a predetermined direction by supplying an alternating signal to the step motor by alternately driving the first transistor pair and the second transistor pair to an ON state in driving to rotate the motor and driving both drive terminals of the step motor to a same level by driving the first and the third transistors to an ON state and driving the second and the fourth transistors to an OFF state in braking the motor;

a fifth transistor connected in parallel with the first transistor and a sixth transistor connected in parallel with the third transistor;

wherein the driving means drives the fifth transistor to an ON state when the first transistor is driven to the ON state in driving to rotate the motor, drives the fifth transistor to an OFF state when the first transistor is driven to the ON state in braking the motor, drives the sixth transistor to an ON state when the third transistor is driven to the ON state in driving to rotate the motor and drives the sixth transistor to an OFF state when the third transistor is driven to an ON state in braking the motor.

2. The step motor drive circuit according to claim 1;

wherein the first and the fifth transistors are constituted by transistors of a same channel and the third and the sixth transistors are constituted by transistors of a same channel.

3. The step motor drive circuit according to claim 1;

wherein the first and the fifth transistors are constituted by transistors of different channels and the third and the sixth transistors are constituted by transistors of different channels.

4. The step motor drive circuit according to claim 1;

wherein the first through the sixth transistors are constituted by a semiconductor integrated circuit, the first and the fifth transistors are constituted by physically dividing a single one of a transistor and the third and the sixth transistors are constituted by physically dividing a single one of a transistor.

5. The step motor drive circuit according to claim 4, wherein an area of the fifth transistor is larger than an area of the first transistor and an area of the sixth transistor is larger than an area of the third transistor.

6. An analog electronic timepiece comprising:

a step motor for driving to rotate a time hand; and

a step motor drive circuit operated to count time based on a time signal constituting a reference of time for driving to rotate the step motor and indicating time by the time hand by driving to rotate the motor by the step motor drive circuit;

wherein the step motor drive circuit is constituted by using the step motor drive circuit according to claim 1.

7. An analog electronic timepiece comprising:

a step motor for driving to rotate a time hand; and

a step motor drive circuit operated to count time based on a time signal constituting a reference of time for driving to rotate the step motor and indicating time by the time hand by driving to rotate the motor by the step motor drive circuit;

wherein the step motor drive circuit is constituted by using the step motor drive circuit according to claim 2.

8. An analog electronic timepiece comprising:

a step motor for driving to rotate a time hand; and

a step motor drive circuit operated to count time based on a time signal constituting a reference of time for driving to rotate the step motor and indicating time by the time hand by driving to rotate the motor by the step motor drive circuit;

wherein the step motor drive circuit is constituted by using the step motor drive circuit according to claim 3.

9. An analog electronic timepiece comprising:

a step motor for driving to rotate a time hand; and

a step motor drive circuit operated to count time based on a time signal constituting a reference of time for driving to rotate the step motor and indicating time by the time hand by driving to rotate the motor by the step motor drive circuit;

wherein the step motor drive circuit is constituted by using the step motor drive circuit according to claim 4.

10. An analog electronic timepiece comprising:

a step motor for driving to rotate a time hand; and

a step motor drive circuit operated to count time based on a time signal constituting a reference of time for driving to rotate the step motor and indicating time by the time hand by driving to rotate the motor by the step motor drive circuit;

wherein the step motor drive circuit is constituted by using the step motor drive circuit according to claim 5.