Voltage drive amplifier with voltage feedback
First Claim
1. A voltage drive circuit for a stepper motor in a laser scanning device, comprising:
- a. said stepper motor having a rotor, a stator, a center-tapped AC winding to which an AC drive signal is applied and a DC winding to which a DC drive signal is applied;
b. a triangular waveform generating means for generating a periodic triangular voltage signal;
c. means for driving said AC winding with said periodic triangular voltage signal, including a voltage feedback circuit in which a voltage across the AC winding is compared with the input periodic triangular voltage signal driving the AC winding and the voltage across the AC winding is caused to follow the input periodic triangular voltage signal driving the AC winding; and
d. means for driving said DC winding with a DC winding voltage signal.
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Accused Products
Abstract
A voltage drive circuit for driving a stepping motor for a laser scanning mirror in a laser bar code reader assembly. The voltage drive circuit provides a highly damped, low q drive in which resonance is virtually eliminated and wherein damping of the rotor is proportional to its angular velocity, and also the position of the rotor precisely follows an input voltage signal driving the motor. The stepping motor includes a rotor, a stator, a center-tapped AC winding and a DC winding. The motor drive circuit comprises a triangular waveform generator for generating a periodic triangular voltage signal. A driving circuit for an AC winding receives the periodic triangular voltage signal as an input, and includes a voltage feedback circuit in which the voltage across the AC winding is compared with and caused to follow the input voltage signal driving the AC winding. The drive circuit for the AC winding includes a first noninverting operational amplifier and a second inverting operational amplifier for driving respectively first and second phase sides of the AC winding. Each of the first and second operational amplifiers receive the triangular voltage signal as a first input signal and also receives as a second input a feedback signal representing respectively the voltage across the first and second phase sides of the AC winding. A drive circuit for the DC winding utilizes a voltage feedback signal obtained from the AC winding for compensating for an angular offset between the AC and DC windings.
14 Citations
13 Claims
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1. A voltage drive circuit for a stepper motor in a laser scanning device, comprising:
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a. said stepper motor having a rotor, a stator, a center-tapped AC winding to which an AC drive signal is applied and a DC winding to which a DC drive signal is applied; b. a triangular waveform generating means for generating a periodic triangular voltage signal; c. means for driving said AC winding with said periodic triangular voltage signal, including a voltage feedback circuit in which a voltage across the AC winding is compared with the input periodic triangular voltage signal driving the AC winding and the voltage across the AC winding is caused to follow the input periodic triangular voltage signal driving the AC winding; and d. means for driving said DC winding with a DC winding voltage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification