Compact bar code scanning module with shock protection

• US 5,581,067 A
• Filed: 10/20/1994
• Issued: 12/03/1996
• Est. Priority Date: 05/08/1990
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Grosfeld, Henry, Doran, Robert, Dvorkis, Paul, Charych, Hal
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): FRECH, KARL D
• Application Number:
  US08/326,328
• Time in Patent Office: 775 Days
• Field of Search: 235/462, 235/472, 359/198, 359/199
• US Class Current: 235/462.36
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 2207/1016 Motor control or optical moving unit control
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10584 Source control
• CPC Class Codes: G06K 7/10633 by oscillation
• CPC Class Codes: G06K 7/10643 Activating means
• CPC Class Codes: G06K 7/10653 using flexible or piezoelectric means
• CPC Class Codes: G06K 7/10673 Parallel lines
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10871 randomly oriented data-fields, code-marks therefore, e.g. concentric circles-code
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners
• CPC Class Codes: G06K 7/10891 the scanner to be worn on a finger or on a wrist
• CPC Class Codes: G06K 7/109 adaptations to make the hand-held scanner useable as a fixed scanner
• CPC Class Codes: G06K 7/1098 the scanning arrangement having a modular construction

Abstract

A scanner module for use in a bar code reader has a scanning mirror which is mounted to a bracket by way of leaf-spring, allowing the mirror to oscillate in one direction. The bracket is hung from a stationary chassis by means of two strips of mylar film, allowing the entire bracket to oscillate in the perpendicular direction, thereby providing two dimensional oscillation of the mirror and raster scanning of a light beam reflected from the mirror. The mylar sheets are protected against mechanical shock by pins which pass through holes in the bracket. The pins are slightly smaller than the holes, allowing sufficient clearance for movement of the bracket during normal operation, but preventing too much stress being placed upon the mylar films if the module is dropped. The pins also provide accurate alignment of the bracket with respect to the chassis.

Claims

1. A scan module for use in a scanner for reading indicia having parts of differing light reflectivity, the scan module comprising:

a) a frame;

b) a scanning component mounted to the frame for oscillatory motion, the scanning component including an optical element for directing light in a scanning pattern across an indicia to be read, the scanning component having an aperture therein; and

c) an anti-shock member, passing through the aperture in the scanning component, the anti-shock member having a waist portion smaller in cross section than the size of the aperture, thereby providing clearance of the scanning component to oscillate relative to the waist portion in use, but preventing excessive movement of the scanning component with respect to the frame in the event that the module is subjected to a mechanical shock.

2. A scan module as claimed in claim 1 wherein the anti-shock member is a pin having a first head portion, a second head portion, and the waist portion having a smaller cross section than the first and second head portions, the waist portion being located within the aperture during normal operation of the scan module.

3. A scan module as claimed in claim 2 wherein the first head portion carries an external screw thread which is arranged to be screwed into a bore in the frame.

4. A scan module as claimed in claim 3 wherein the first head portion is substantially flush with the frame when the pin is in a position for normal operation of the scan module.

5. A scan module as claimed in claim 2 wherein the second head portion is arranged to be received within a correspondingly-sized bore within the frame.

6. A scan module as claimed in claim 5 wherein the frame comprises a first side portion, a second side portion, and a rear portion connecting the first and second side portions, the electromagnetic coil being mounted between the side portions.

7. A scan module as claimed in claim 6 including an optical collector element mounted to the first side.

8. A scan module as claimed in claim 6 including a photodetector unit mounted to the second side.

9. A scan module as claimed in claim 6 wherein the first and second sides have respective cut out portions, within which are received respective hanging brackets portions of the bracket.

10. A scan module as claimed in claim 9 wherein the hanging bracket portions are mounted to the frame by respective flexure members.

11. A scan module as claimed in claim 10 wherein the flexure members are polyester material films.

12. A scan module as claimed in claim 2 wherein the cross sectional size and shape of the second head portion corresponds with the size and shape of the aperture.

13. A scan module as claimed in claim 12 wherein the second head portion is of such a length that the pin may be positioned with the second head portion contained within the aperture and extending from the aperture into a correspondingly-sized bore within the frame, thereby locating the scanning component with respect to the frame.

14. A scan module as claimed in claim 2 wherein the pin extends across a cut out portion of the frame, the aperture being in a portion of the scanning component which extends into the said cut out portion.

15. A scan module as claimed in claim 14 wherein said cut out portion of the scanning component contains a hanging bracket.

16. A scan module as claimed in claim 15 wherein the hanging bracket is supported from the frame by a flexure member.

17. A scan module as claimed in claim 10 wherein the flexure member comprises a polyester material film.

18. A scan module as claimed in claim 1 wherein the aperture is in a portion of the scanning component comprising a hanging bracket.

19. A scan module as claimed in claim 18 wherein the hanging bracket is supported from the frame by a flexure member.

20. A scan module as claimed in claim 19 wherein the flexure member comprises a polyester material film.

21. A scan module as claimed in claim 1 wherein the scanning component is supported from the frame by a flexure member, the scanning component further including counterweight means balancing the mass of the optical element at the flexure member.

22. A scan module as claimed in claim 21 further including an electromagnetic coil mounted to the frame, the counterweight means at least partially overlying the coil.

23. A scan module as claimed in claim 1 wherein the scanning component is supported from the frame by a flexure member, and the optical element is supported from the scanning component by a further flexure member, the flexure member and the further flexure member being arranged to flex in mutually perpendicular directions.

24. A scan module as claimed in claim 1 including first and second anti-shock members, the first anti-shock member being adjacent a first side of the frame, and the second anti-shock member being adjacent a second side of the frame.

25. A scan module as claimed in claim 1 wherein the anti-shock member has a longitudinal axis, the movement of the scanning component at the aperture, during oscillation, being substantially perpendicular to the said axis.

26. A scan module as claimed in claim 1 wherein the anti-shock member comprises a pin.

27. A method of assembling a scan module for use in a scanner for reading indicia having parts of differing reflectivity, the scan module comprising:

a frame;

a scanning component to be mounted to the frame for oscillatory motion, the scanning component including an optical element for directing light in a scanning pattern across an indicia to be read, the scanning component having an aperture therein; and

an anti-shock pin having a first head portion, a second portion, and a waist portion having a smaller cross section than the first and second head portions;

the method comprising;

a) positioning the scanning component adjacent to

the frame;

b) partially inserting the pin in to the frame so that the second head portion passes through the aperture and extends from the aperture in to a correspondingly-shaped bore in the frame, thereby aligning the scanning component with respect to the frame;

c) securing the scanning component to the frame;

d) continuing insertion of the pin in to the frame so that the waist portion of the pin becomes located within the aperture, thereby providing clearance for the scanning component to oscillate in use, but preventing excessive movement of the scanning component with respect to the frame in the event that the module is subjected to a mechanical shock.

28. A method of assembling a scan module for use in a scanner for reading indicia having parts of differing reflectivity, the scan module comprising:

a frame;

a scanning component to be mounted to the frame for oscillatory motion, the scanning component including an optical element for directing light in a scanning pattern across an indicia to be read, the scanning component having an aperture therein; and

an anti-shock pin having a head portion, a second head portion, and a waist portion having a smaller cross section than the first and second head portions;

the method comprising the steps of;

a) positioning the scanning component adjacent to the frame;

b) partially inserting the pin into the frame so that the second head portion passes through the aperture and extends from the aperture into a correspondingly-shaped bore in the frame, thereby aligning the scanning component with respect to the frame;

c) securing the scanning component to the frame; and

d) continuing insertion of the pin into the frame so that the waist portion of the pin becomes located within the aperture, thereby providing clearance for the scanning component to oscillate in use, but preventing excessive movement of the scanning component with respect to the frame in the event that the module is subjected to a mechanical shock.

29. A method as claimed in claim 28 wherein the final location of the pin, for normal operation of the scan module, is defined by a position in which the first head portion of the pin lies flush with the frame.

30. A scan module for use in a scanner for reading indicia having parts of differing light reflectivity, the scan module comprising:

a) a frame;

b) a scanning component including a bracket mounted to the frame by flexible support means for oscillatory motion, the bracket carrying an optical element for directing light in a scanning pattern across an indicia to be read;

c) an electromagnetic coil mounted to the frame;

d) magnet means secured to the bracket adjacent the coil; and

e) the bracket further including a counterweight portion balancing the mass of the optical element at the flexible support means, the counterweight portion at least partially overlying the coil.

31. A scan module as claimed in claim 30 including an anti-shock member passing through an aperture in the bracket, the anti-shock member having a waist portion smaller in cross section than the size of the aperture, thereby providing clearance for the scanning component to oscillate relative to the waist portion in use, but preventing excessive movement of the scanning component with respect to the frame in the event that the module is subjected to a mechanical shock.

32. A scan module as claimed in claim 31 wherein the anti-shock member comprises a pin.

33. A scan module as claimed in claim 32 wherein the pin has a first head portion, a second held portion, and the waist portion having a smaller cross section than the first and second head portions, the waist portion being located within the aperture during normal operation of the scan module.

34. A scan module as claimed in claim 33 wherein the first head portion carries an external screw thread which is arranged to be screwed into a bore in the frame.

35. A scan module as claimed in claim 34 wherein the first head portion is substantially flush with the frame when the pin is in a position for normal operation of the scan module.

36. A scan module as claimed in claim 33 wherein the head portion is arranged to be received within a correspondingly-sized bore within the frame.

37. A scan module as claimed in claim 33 wherein the cross sectional size and shape of the second head portion corresponds with the size and shape of the aperture.

38. A scan module as claimed in claim 37 wherein the second head portion is of such a length that the pin may be positioned with the second head portion contained within the aperture and extending from the aperture into a correspondingly-sized bore within the frame, thereby locating the scanning component with respect to the frame.

39. A scan module as claimed in claim 33 wherein the pin extends across a cut out portion of the frame, the aperture being in a portion of the scanning component which extends into the said cut out portion.

40. A scan module as claimed in claim 30 wherein the optical element is supported from the bracket by a further flexible support means, the flexible support means and the further flexible support means being arranged to flex in mutually perpendicular directions.

41. A scan module for use in a scanner for reading indicia having parts of differing light reflectivity, the scan module comprising:

a) a frame;

b) a scanning component including a main bracket mounted to the frame by flexible support means for oscillatory motion, the main bracket carrying an optical element for directing light in a scanning pattern across an indicia to be read, the main bracket having an aperture therein;

c) an electromagnetic coil mounted to the frame;

d) magnet means, secured to the bracket adjacent to the coil;

e) the bracket further including a counterweight portion balancing the mass of the optical element at the flexible support means, the counterweight portion at least partially overlying the coil; and

f) an anti-shock member passing through the aperture in the main bracket, the member having a waist portion smaller in cross section than the size of the aperture, thereby providing clearance for the scanning component to oscillate relative to the waist portion in use, but preventing excessive movement of the scanning component with respect to the frame in the event that the module is subjected to a mechanical shock.

42. A scan module for use in a system for electro-optically reading coded indicia, comprising:

a) a frame;

b) a scanner component mounted for oscillating movement on the frame to direct light therefrom toward the coded indicia during said oscillating movement;

c) an anti-shock member mounted on the frame and having an anti-shock portion that extends with clearance through the scanner component; and

d) means for oscillating the scanner component relative to the anti-shock portion within a predetermined range of motion.