Light beam shaping arrangement and method in electro-optical readers

• US 20040245338A1
• Filed: 06/09/2003
• Published: 12/09/2004
• Est. Priority Date: 06/09/2003
• Status: Active Grant

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Poloniewicz, Paul R.
• Granted Patent: US 7,007,843 B2
• Time in Patent Office: Days
• US Class Current: 235/454
• CPC Class Codes: G06K 7/10653 using flexible or piezoelectric means

Abstract

A micro-electro-mechanical system component is deformed to control a shape and size and orientation of a laser beam spot that is scanned across a symbol to be read by an electro-optical reader.

Claims

1. A beam shaping arrangement in a reader for electro-optically reading indicia, comprising:

a) a light source for emitting a light beam along an optical axis, the light beam having a cross-section in a plane perpendicular to the optical axis;

b) a deformable, micro-electro-mechanical system (MEMS) mirror for reflecting the light beam along an optical path toward the indicia as a reflected beam having a cross-section in a plane perpendicular to the optical path; and

c) means for deforming the MEMS mirror to change the cross-section of the reflected beam to be different from the cross-section of the light beam emitted by the source.

2. The arrangement of claim 1, wherein the light source is a solid-state laser.

3. The arrangement of claim 1, and further comprising a substrate and an upright support for supporting the MEMS mirror above the substrate.

4. The arrangement of claim 3, wherein the deforming means includes a plurality of electrodes on the substrate at opposite sides of the support and below the MEMS mirror, and a drive circuit for charging the electrodes to generate between the electrodes and the MEMS mirror an electrostatic field of sufficient strength to deform the MEMS mirror.

5. The arrangement of claim 4, wherein the support lies in an upright plane bisecting the MEMS mirror, and wherein the electrodes include a first electrode positioned at one side of the upright plane, and a second electrode positioned at an opposite side of the upright plane, and wherein the drive circuit charges both the first and the second electrodes simultaneously.

6. The arrangement of claim 5, wherein the MEMS mirror has an initial configuration in which the MEMS mirror lies in a plane, and wherein the MEMS mirror has a curved configuration during operation of the deforming means.

7. The arrangement of claim 4, wherein the support is an upright post centrally located with respect to the MEMS mirror, and wherein the electrodes are arranged circumferentially about the post, and wherein the drive circuit charges at least one of the electrodes.

8. The arrangement of claim 3, wherein the substrate, the support and the MEMS mirror are of one-piece construction.

9. The arrangement of claim 1, wherein the cross-section of the light beam emitted by the source is generally circular, and wherein the deforming means changes the cross-section of the reflected beam to be elliptical.

10. A beam shaping method used in electro-optical reading of indicia, comprising the steps of:

a) emitting a light beam along an optical axis, the light beam having a cross-section in a plane perpendicular to the optical axis;

b) positioning a deformable, micro-electro-mechanical system (MEMS) mirror relative to the light beam for reflecting the light beam along an optical path toward the indicia as a reflected beam having a cross-section in a plane perpendicular to the optical path; and

c) deforming the MEMS mirror to change the cross-section of the reflected beam to be different from the cross-section of the light beam.

11. The method of claim 10, and the step of supporting the MEMS mirror above a substrate.

12. The method of claim 11, wherein the deforming step is performed by positioning a plurality of electrodes on the substrate below the MEMS mirror, and by charging the electrodes to generate between the electrodes and the MEMS mirror an electrostatic field of sufficient strength to deform the MEMS mirror.

13. The method of claim 12, wherein the charging step is performed by simultaneously charging a plurality of the electrodes.

14. The method of claim 13, wherein the deforming step distorts the MEMS mirror between a generally planar configuration and a curved configuration.

15. The method of claim 10, wherein the cross-section of the light beam is generally circular, and wherein the deforming step is operative to change the cross-section of the reflected beam to be elliptical.