Electricity: motive power systems – Positional servo systems – Unwanted harmonic or voltage component elimination...
Reexamination Certificate
2002-06-14
2004-11-02
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Positional servo systems
Unwanted harmonic or voltage component elimination...
C318S599000, C318S603000
Reexamination Certificate
active
06812669
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to micro-electro-mechanical system (MEMS) mirrors, and more particularly, to a MEMS resonant scanning mirror driver circuit.
2. Description of the Prior Art
Movement of a resonant MEMS mirror is accomplished using a control loop that includes a sinusoidal driver circuit. This driver circuit must have low harmonic distortion characteristics in order to precisely and accurately control movement of the MEMS mirror. Such driver circuits generally require use of either a precision analog oscillator or a fast and therefore expensive digital-to-analog converter (DAC) devices and accompanied sine wave logic to control the amplitude of the drive signal to a MEMS resonant scanning mirror.
In view of the foregoing, it would be desirable and advantageous in the MEMS mirror art to provide a resonant scanning mirror driver circuit that allows use of an inexpensive means of generating the sine wave and an inexpensive DAC with a relatively slow sample rate commensurate with a microprocessor based control algorithm.
SUMMARY OF THE INVENTION
The present invention is directed to a MEMS resonant scanning mirror driver circuit. The driver circuit has separate amplitude and waveshape inputs which allows a relatively slow and therefore inexpensive DAC to be used to control the amplitude of the drive signal for the MEMS device.
According to one embodiment, a resonant scanning mirror driver circuit is provided that has an analog input to set the amplitude of a sinusoidal drive voltage and further has a PWM digital input that generates the sinusoidal waveform.
REFERENCES:
patent: 3649902 (1972-03-01), Dunbar
patent: 3654450 (1972-04-01), Webb
patent: 3657657 (1972-04-01), Jefferson
patent: 3659226 (1972-04-01), Angeleri et al.
patent: 3713137 (1973-01-01), Stone
patent: 3742326 (1973-06-01), Okuda et al.
patent: 4426149 (1984-01-01), Kuemmel et al.
patent: 4584658 (1986-04-01), Ottobre et al.
patent: 5453833 (1995-09-01), Kawashima et al.
Brady III W. James
Kempler William B.
Ro Bentsu
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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