Retro-reflective scan module for electro-optical readers

• US 6,360,949 B1
• Filed: 03/24/1999
• Issued: 03/26/2002
• Est. Priority Date: 10/10/1995
• Status: Expired due to Fees

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Luciano, Vincent, Barkan, Edward D., Bridgelall, Raj, Gurevich, Vladimir, Katz, Joseph, Dvorkis, Paul, Shepard, Howard, Li, Yajun, Krichever, Mark, Metlitsky, Boris
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): FUREMAN, JARED
• Application Number:
  US09/275,858
• Time in Patent Office: 1,098 Days
• Field of Search: 235/454, 235/462.01, 235/462.32, 235/462.33, 235/462.36, 235/462.37, 235/462.43, 235/462.45, 235/462.46, 235/462.47, 235/472.01, 235/472.02
• US Class Current: 235/462.43
• CPC Class Codes: G06K 7/10653 using flexible or piezoelectric means
• CPC Class Codes: G06K 7/10683 Arrangement of fixed elements

Abstract

A miniaturized electro-optical, retro-reflective scanning module. The module has a base, a first circuit board, and a second circuit board mounted substantially orthogonal to the first circuit board. The base supports a light emitter for producing a scanning beam and optical elements for directing and collecting light energy. The emitted beam reflects off a fold mirror onto a reflector mounted on a drive for oscillation. The oscillating reflector, in turn, redirects the beam onto an indicia being read. The reflected light is reflected off the oscillating reflector and directed to the collection mirror before reaching a detector. The detector included in the module senses light reflected from an indicia scanned by the beam. The reflector is driven by an electro-magnetiz driven system, including a flexure and an actuation arm.

Claims

1. A scanning element for scanning a beam of light over an indicium having parts of different light reflectivity, comprising:

a) a support;

b) a generally planar, elongated flexure having one end region connected to the support, and an opposite end region;

c) an elongated actuation arm connected to the opposite end region of the flexure and having opposite end portions, the actuation arm being attached to the flexure at a region between the opposite end portions of the actuation arm;

d) a reflector for reflecting the light beam and being connected to one end portion of the actuation arm;

e) a magnet attached to the other end portion of the actuation arm; and

f) a drive for exerting a force upon the magnet and for moving the magnet, the actuation arm and the reflector to scan the light beam across the indicium.

2. The scanning element of claim 1, wherein the drive comprises an electromagnetic coil having a passage.

3. The scanning element of claim 2, wherein the magnet at least partially enters the passage during movement of the magnet.

4. The scanning element of claim 1, wherein the magnet and the reflector have respective weights that balance each other.

5. The scanning element of claim 1, wherein the reflector is a generally planar mirror.

6. The scanning element of claim 5, wherein the mirror is constituted of a plastic material.

7. The scanning element of claim 1, wherein the actuation arm is constituted of a plastic material.

8. The scanning element of claim 1, wherein the actuation arm and the reflector constitute a single molded plastic piece.

9. The scanning element of claim 1, wherein the flexure is constituted of a plastic film.

10. The scanning element of claim 1, wherein the flexure includes at least two leaf springs.

11. The scanning element of claim 1, and further comprising a laser diode on the support for emitting the light beam as a laser beam.

12. A scanning module for electro-optically reading bar code symbols by scanning each symbol with a beam of light, and by collecting light returning from the respective symbol, the scanning module comprising:

a) a base;

b) a light source on the base for generating the beam of light;

c) a scanning element on the base for scanning the respective symbol with the beam of light in an oscillatory movement, the scanning element including

i) a support attached to the base;

ii) a generally planar, elongated flexure having one end region connected to the support, and an opposite end region;

iii) an elongated actuation arm connected to the opposite end region of the flexure and having opposite end portions, the actuation arm being attached to the flexure at a region between the opposite end portions of the actuation arm;

iv) a scan mirror for reflecting the light beam and being connected to one end portion of the actuation arm;

v) a magnet attached to the other end portion of the actuation arm; and

vi) a drive for exerting an oscillatory force upon the magnet and for oscillating the magnet, the actuation arm and the scan mirror to scan the light beam across the respective symbol;

d) a collection optics for collecting the light returning from the respective symbol;

e) a detector for detecting and converting the collected light into an electrical signal; and

f) a processing circuit for processing the electrical signal into data corresponding to the respective symbol.

13. The scanning module of claim 12, and further comprising a folding mirror located along a beam path from the light source to the scanning element, for folding the beam of light generated by the light source and redirecting the beam of light onto the scan mirror.

14. The scanning module of claim 13, wherein the folding mirror has a curvature for modifying a cross-sectional characteristic of the light beam.

15. The scanning module of claim 13, wherein the collection optics includes a collection mirror having a hole therethrough, and wherein the folding mirror folds the beam of light generated by the light source and redirects the beam of light through the hole in the collection mirror onto the scan mirror.

16. The scanning module of claim 15, wherein a width of the collection mirror is substantially equal to a least projected width of the scan mirror.

17. The scanning module of claim 12, wherein the drive comprises an electromagnetic coil having a passage.

18. The scanning module of claim 13, wherein the magnet at least partially enters the passage during movement of the magnet.

19. The scanning module of claim 17, and further comprising a first circuit board for providing electrical connections to the light source, the detector and the coil.

20. The scanning module of claim 12, wherein the magnet and the scan mirror have respective weights that balance each other.

21. The scanning module of claim 12, wherein the scan mirror is constituted of a plastic material.

22. The scanning module of claim 12, wherein the actuation arm is constituted of a plastic material.

23. The scanning module of claim 12, wherein the actuation arm and the scan mirror constitute a single molded plastic piece.

24. The scanning module of claim 12, wherein the flexure is constituted of a plastic film.

25. The scanning module of claim 12, wherein the flexure includes at least two leaf springs.

26. The scanning module of claim 12, wherein the light source is a laser diode for emitting the light beam as a laser beam.

27. The scanning module of claim 12, wherein the processing circuit includes an application specific integrated circuit.

28. The scanning module of claim 12, wherein the processing circuit includes chip-on-board circuitry.

29. The scanning module of claim 12, wherein the processing circuit includes programmable means for selectively modifying at least one operating parameter of the scanning module.

30. The scanning module of claim 29, wherein said at least one operating parameter is stored inside the processing circuit.

31. The scanning module of claim 12, and further comprising a centering means for adjusting a position of the scanning element with respect to the base.

32. The scanning module of claim 12, wherein the base includes at least two alignment elements for proper positioning of the scanning element within a housing of a data acquisition device.

33. The scanning module of claim 32, wherein said at least two alignment elements comprise alignment tabs.

34. The scanning module of claim 32, wherein said at least two alignment elements comprise alignment holes.

35. The scanning module of claim 12, wherein the scanning of the light beam and the collection of the returning light are personnel in different planes.

36. A scanning module for electro-optically reading bar code symbols by scanning each symbol with a laser beam, and by collecting light returning from the respective symbol, the scanning module comprising:

a) a metal base;

b) a collection mirror for collecting the light returning from the respective symbol, the collection mirror having a hole therethrough;

c) a laser light source for generating the laser beam;

d) a fold mirror for folding the laser beam generated by the laser light source and for projecting a folded laser beam through the hole in the collection mirror;

e) a scanning element for receiving the folded laser beam projected through the hole in the collection mirror, and for scanning the respective symbol with the laser beam in an oscillatory movement, the scanning element including

i) a support structure attached to the metal base;

ii) a generally planar, elongated flexure having one end region connected to the support structure, and an opposite end region;

iii) an elongated actuation arm connected to the opposite end region of the flexure and having opposite end portions, the actuation arm being attached to the flexure at a region between the opposite end portions of the actuation arm;

iv) a scan mirror having a width and connected to one end portion of the actuation arm, for accepting the folded laser beam projected through the hole in the collection mirror, and for directing the accepted laser beam onto the respective symbol;

v) a magnet attached to the other end portion of the actuation arm; and

vi) an electromagnetic coil for exerting an oscillatory force upon the magnet, and for moving the magnet, the actuation arm and the scan mirror in opposite circumferential directions about an axis to scan the laser beam across the respective symbol;

f) a detector for detecting and converting the collected reflected light into an electrical signal;

g) a first circuit board for making electrical connections with the laser source, the detector and the coil; and

h) a second circuit board including a processing circuit for processing the electrical signal into data corresponding to the respective symbol.

37. The scanning module of claim 36, wherein the fold mirror has a curvature for modifying a cross-sectional characteristic of the laser beam.

38. The scanning module of claim 37, wherein the fold mirror has a cylindrical curvature.

39. The scanning module of claim 36, wherein the coil has a passage through which the magnet at least partially enters during movement of the magnet.

40. The scanning module of claim 36, wherein the actuation arm and the scan mirror constitute a single molded plastic piece.

41. The scanning module of claim 36, wherein the magnet and the scan mirror have respective weights that balance each other.

42. The scanning module of claim 36, wherein the scan mirror is constituted of a plastic material.

43. The scanning module of claims 36, wherein the flexure includes at least two leaf springs.

44. The scanning module of claim 36, wherein the processing circuit includes an application specific integrated circuit.

45. The scanning module of claim 36, wherein the processing circuit includes chip-on-board circuitry.

46. The scanning module of claim 36, wherein the processing circuit includes programmable means for selectively modifying at least one operating parameter of the scanning module.

47. The scanning module of claim 46, wherein said at least one operating parameter is stored inside the processing circuit.

48. The scanning module of claim 46, wherein the processing circuit further includes a decoder for decoding information encoded in the respective symbol.

49. The scanning module of claim 36, and further comprising a centering means for adjusting a position of the scanning element with respect to the base.

50. The scanning module of claim 36, wherein a width of the collection mirror is substantially equal to the width of the scan mirror.

51. The scanning module of claim 36, wherein a volume of the module is less than 0.15 cubic inches.

52. The scanning module of claim 51, wherein the volume includes a length of about 0.8 inches, a width of about 0.5 inches and a height of about 0.3 inches.

53. The scanning module of claim 36, wherein the base includes at least two alignment elements for proper positioning of the scanning module into a housing of a data acquisition device.

54. The scanning module of claim 53, wherein said at least two alignment elements comprise alignment tabs.

55. The scanning module of claim 53, wherein said at least two alignment elements comprise alignment holes.

56. The scanning module of claim 36, wherein the coil includes a first winding being a drive winding, and a second winding being a feedback winding.

57. The scanning module of claim 36, wherein the scanning of the light beam and the collection of the returning light are performed in different planes.