Miniature optical scanner for a two axis scanning system

• US 6,288,816 B1
• Filed: 01/23/1998
• Issued: 09/11/2001
• Est. Priority Date: 10/26/1994
• Status: Expired due to Fees

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Johnston, Richard S., Tidwell, Michael R., Furness, Thomas A. III, Kollin, Joel S., Melville, Charles D.
• Primary Examiner(s): Phan, James
• Application Number:
  US09/103,772
• Time in Patent Office: 1,327 Days
• Field of Search: 359/198, 359/199, 359/223, 359/224, 359/212-214, 310/36, 310/40.R, 310/208, 310/75.R, 310/181, 310/103-105, 310/318, 310/333, 310/40.MM
• US Class Current: 359/199.1
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 7/1821 for rotating or oscillating mirrors

Abstract

A miniature optical scanner includes an electromagnetic drive having stationary magnets and stationary drive coils to minimize the rotational inertia of the scanner and increase the scanner'"'"'s resonant frequency. The scanner is such that the resonant frequency is manually tunable as well as automatically adjustable to compensate for variables causing frequency drift. The optical scan angle is increased by employing a multiplying mirror with the optical scanner. For a two axis scanning system, the multiplying mirror may be formed of a second optical scanner to increase the optical scan angle relative to both of the axes.

Claims

1. A miniature optical scanner comprising:

a support;

an oscillating body carried by the support, the oscilating body having at least one arm, a reflective surface and a resonant frequency;

a driver to move the oscillating body; and

an electrically controlled actuator coupled to the support and responsive to an electrical signal to apply a force acting on the arm of the oscillating body to automatically adjust the resonant frequency of the oscillating body.

2. A miniature optical scanner as recited in claim 1 wherein the actuator includes a piezoelectric material responsive to an electrical signal to expand the actuator to create a force on the support.

3. A miniature optical scanner as recited in claim 1 wherein the actuator includes at least one actuator arm coupled to the support, the actuator arm being responsive to an electrical signal to expand, creating a pushing force on the support to adjust the tension in the arm.

4. A miniature optical scanner as recited in claim 1 wherein said reflective surface is disposed between a first arm and a second arm carried by respective first and second portions of the support and said electrically controlled actuator includes at least one auxiliary arm extending generally parallel to the first and second arms between the first and second support portions, the actuator arm being responsive to an electrical signal to apply a force to the first and second support portions to create tension in the arms of the oscillating body to vary the resonant frequency thereof.

5. A method of automatically adjusting the resonant frequency of a miniature optical scanner having an oscillating body with a mirror surface and a torsional member comprising:

coupling a piezoelectric material to the torsional member;

generating a control signal; and

applying the control signal to the piezoelectrical material to generate a force acting on the torsional member of the optical scanner to automatically adjust the resonant frequency of the optical scanner.