Optical storage device rotation speed control apparatus and method

• US 7,116,622 B2
• Filed: 06/18/2003
• Issued: 10/03/2006
• Est. Priority Date: 06/26/2002
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Shen, Po-Jen
• Primary Examiner(s): CHOW, VAN NGUYEN
• Assistant Examiner(s): Pham, Van T.
• Application Number:
  US10/250,251
• Publication Number:
  US 20040022153A1
• Time in Patent Office: 1,203 Days
• Field of Search: 369/53.3, 369/53.37, 369/47.4, 369/47.55, 388/811, 388/907.5, 318/599, 318/606, 318/432
• US Class Current: 369/53.3
• CPC Class Codes: G11B 19/28 Speed controlling, regulating, or indicating G11B19/24 takes precedence

Abstract

A method for controlling the rotation speed of an optical storage device. In the first mode, a first signal is produced, and in the second mode, a second signal is produced. In one mode, a first pulse of a first voltage and a second pulse of a second voltage are sent to the motor, which causes the motor to produce a first armature current and a second armature current. In another mode, a DC signal of a third voltage is produced, which causes the motor to produce a third armature current. The armature currents are detected, and test voltages are outputted. The first and second voltages, and the first and second test voltages are used to find a motor coefficient. The third voltage, the motor coefficient, and the third test voltage are used to calculate a motor rotation speed. The calculated speed is used to control the real motor speed.

Claims

1. A method for controlling angular velocity of a spindle motor to rotate an optical disc in an optical disc reproduction apparatus, the optical disc reproduction apparatus having an optical pick-up to read information stored on the optical disc, the method comprising:

generating a first control signal while in a first control mode, and generating a second control signal while in a second control mode;

when receiving the first control signal in the first control mode, sending a first pulse with a first control voltage and a second pulse with a second control voltage to the spindle motor, causing the spindle motor to produce a first armature current upon reception of the first pulse and produce a second armature current upon reception of the second pulse;

when receiving the second control signal in the second control mode, sending a third DC signal with a third control voltage to the spindle motor, causing the spindle motor to produce a third armature current upon reception of the DC signal;

sensing the first, the second, and the third armature currents, and outputting a first, a second, and a third test voltage corresponding to the first, the second, and the third armature currents;

using the first and the second control voltages and the first and second test voltages to obtain a motor coefficient of the spindle motor;

using the third control voltage, the motor coefficient, and the third test voltage to obtain a relative angular velocity of the spindle motor for controlling the angular velocity of the spindle motor.

2. The method of claim 1 wherein the motor coefficient is found by taking a ratio of a sum of the control voltages to a difference of the test voltages.

3. The method of claim 1 wherein the relative angular velocity of the spindle motor is found by taking a difference of the third control voltage and the product of the motor coefficient and the third test voltage.

4. The method of claim 1 wherein a armature current sensor circuit is used to find the first, the second, and the third test voltages relative to the first, the second, and the third armature currents, respectively, the armature current sensor circuit comprising:

a first resistor, connected in series with the motor;

an operational amplifier;

a second and a third resistor, the second resistor connected at a first end to a first end of the first resistor, and connected at a second end to the non-inverting input of the operational amplifier, and the third resistor connected at a first end to a second end of the first resistor, and connected at a second end to the inverting input of the operational amplifier; and

a fourth and fifth resistor, the fourth resistor connected at a first end to the non-inverting input of the operational amplifier and at a second end to a reference voltage, and the fifth resistor connected at a first end to the inverting input of the operational amplifier and at a second end to an output terminal of the operational amplifier.

5. The method of claim 4 wherein the value of the second resistor is equal to the value of the third resistor;

the value of the fourth resistor is equal to the value of the fifth resistor; and

the value of the first resistor is much lower than the value of the second resistor.

6. An apparatus for reproducing information on a disk-shaped information storing medium, comprising:

a pick-up for reproducing information on the medium;

a spindle motor for rotating the medium;

a motor driving circuit for generating a first pulse with a first control voltage to the spindle motor and causing the spindle motor to produce a first armature current, generating a second pulse with a second control voltage to the spindle motor and causing the spindle motor to produce a second armature current, and generating a DC signal with a third voltage to the spindle motor and causing the spindle motor to produce a third armature current;

a sensor circuit for sensing the first, the second, and the third armature currents,

and generating a first, a second, and a third test voltage corresponding to the first, the second, and the third armature currents, respectively;

wherein the first and the second test voltages are calculated to obtain a motor coefficient of the spindle motor; and

wherein the third control voltage, the motor coefficient, and the third test voltage are calculated to obtain a relative angular velocity of the spindle motor for controlling the angular velocity of the spindle motor.

7. The apparatus of claim 6 further comprising an angular velocity control circuit, the angular velocity control circuit generating a first control signal while in a first control mode, generating a second control signal while in a second control mode, the motor driving circuit generating the first pulse and the second pulse when receiving the first control signal, and generating the DC signal when receiving the second control signal.

8. The apparatus of claim 7 wherein the angular velocity control circuit obtains the motor coefficient by taking a ratio of a sum of the first and the second control voltages to a difference of the first and the second test voltages.

9. The apparatus of claim 7 wherein the angular velocity control circuit obtains the relative angular velocity of the motor by taking a difference of the third control voltage and the product of the motor coefficient and the third test voltage.

10. The apparatus of claim 6 wherein the sensor circuit comprises:

a first resistor connected in series with the motor;

an operational amplifier;

a second and a third resistor, the second resistor connected at a first end to a first end of the first resistor, and connected at a second end to the non-inverting input of the operational amplifier, and the third resistor connected at a first end to a second end of the first resistor, and connected at a second end to the inverting input of the operational amplifier; and

a fourth and fifth resistor, the fourth resistor connected at a first end to the non-inverting input of the operational amplifier and at a second end to a reference voltage, and the fifth resistor connected at a first end to the inverting input of the operational amplifier and at a second end to an output terminal of the operational amplifier.

11. The apparatus of claim 10 wherein resistance of the second resistor is equal to resistance of the third resistor;

resistance of the fourth resistor is equal to resistance of the fifth resistor; and

resistance of the first resistor is much lower than the resistance of the second resistor.

12. A method for controlling angular velocity of a spindle motor to rotate an optical disc in an optical disc reproduction apparatus, the optical disc reproduction apparatus having an optical pick-up to read information stored on the optical disc, the method comprising:

generating a first pulse with a first control voltage and a second pulse with a second control voltage to the spindle motor, causing the spindle motor to produce a first armature current upon reception of the first pulse and produce a second armature current upon reception of the second pulse;

generating a third DC signal with a third control voltage to the spindle motor, causing the spindle motor to produce a third armature current upon reception of the DC signal;

sensing the first, the second, and the third armature currents, and outputting a first, a second, and a third test voltage corresponding to the first, the second, and the third armature currents;

using the first and the second control voltages and the first and second test voltages to obtain a motor coefficient of the spindle motor;

using the third control voltage, the motor coefficient, and the third test voltage to obtain a relative angular velocity of the spindle motor for controlling the angular velocity of the spindle motor.