Indicia sensor system for optical reader

• US 6,585,159 B1
• Filed: 11/02/1999
• Issued: 07/01/2003
• Est. Priority Date: 11/02/1999
• Status: Expired due to Term

• Current Assignee: Welch Allyn Incorporated
• Original Assignee: Welch Allyn Incorporated
• Inventors: Meier, Timothy P., Barber, Charles P., Hussey, Robert M.
• Primary Examiner(s): Frech, Karl D.
• Assistant Examiner(s): WALSH, DANIEL I
• Application Number:
  US09/432,282
• Time in Patent Office: 1,337 Days
• Field of Search: 235/462.31, 235/462.25, 235/462.14, 235/462.05, 235/462.08, 235/462.16, 235/462.2
• US Class Current: 235/462.31
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners
• CPC Class Codes: G06K 7/109 adaptations to make the hand-held scanner useable as a fixed scanner

Abstract

In the present invention, the control unit of an optical reader analyzes image data being generated by the imaging element of the reader and changes the mode of operation of the reader if the image data indicates that machine readable indicia, such as a bar code symbol or a text character, is likely in the field of view of the reader. Normally, analysis of image data includes the step of detecting for edge transitions in the image information. If the control unit determines that the image data includes more than a predetermined number of edge transitions, then the control unit imparts appropriate control over various reader elements to change the mode of operation of the reader. Normally, the control unit changes the mode of operation of the reader from a first mode, wherein the reader does not operate to decode or recognize image data to a second mode, wherein the reader operates to decode and/or recognize image data.

Claims

1. A method for operating an optical reading device having an imaging assembly, said method comprising the steps of:

generating image information from said imaging assembly;

detecting edge transitions of said image information; and

changing a mode of operation of said optical reading device if a number of said edge transitions is equal to or exceeds a number of edge transitions previously determined to indicate there being a decodable indicia represented in said image information, wherein said number of edge transitions is at least two edge transitions.

2. The method of claim 1, wherein said detecting step includes the step of analyzing a single line of image information.

3. The method of claim 1, wherein said detecting step includes the steps of:

capturing a frame of image information;

sequentially analyzing a plurality of lines of image information from said captured frame; and

ceasing said detecting step if one of said lines indicates the presence of edge transitions in said image information in excess of said predetermined amount.

4. The method of claim 3, wherein said analyzing step includes the step of sequentially analyzing vertical, horizontal, and diagonal lines of image information.

5. The method of claim 1, wherein said detecting step includes the steps of:

analyzing a line of image information;

establishing at least one threshold for said line of image information; and

recording said edge transitions based on crossings of said image information of said at least one threshold.

6. The method of claim 1, further comprising the step of determining a pixel variance measurement to determine if said image information corresponds to a uniform gray scale image.

7. The method of claim 1, wherein said establishing step includes the step of setting a maximum threshold and a minimum threshold, and wherein said recording step includes the step of counting an edge transition if said image information rises above said maximum threshold or falls below said minimum threshold.

8. The method of claim 1, wherein said establishing step includes the step of setting said thresholds according to a rule which precludes said thresholds from being established within a predetermined range of one another so that edge transitions are not recorded from image information that corresponds to a substantially uniform gray scale scene.

32. The method of claim 1, wherein said method further includes the step of implementing said method using a stationary position optical reading device.

33. The method of claim 1, wherein a mode of operation of said device after said mode change is characterized by at least one of an increase in illumination and activation of a decoding algorithm.

34. The method of claim 1, wherein a mode of operation of said device prior to said mode change is characterized by an illumination array being off, and a mode of operation of said device subsequent to said mode change is characterized by said illumination array being on.

35. The method of claim 2, wherein said line is a straight line of contiguous pixels.

36. The method of claim 3, wherein said plurality of lines are spaced apart.

9. A method for detecting for the presence of a machine readable indicia which may be represented in image information, said method comprising the steps of:

detecting edge transitions represented in said image information;

counting said edge transitions, and

determining that a machine readable indicia is represented in said image information if the number said edge transitions is equal to or exceeds a predetermined number, wherein said predetermined number of edge transitions is at least two.

10. The method of claim 9, further including the step of increasing illumination of said indicia if said indicia is determined to be present.

11. The method of claim 9, wherein said detecting step includes the step of analyzing a line of image information.

12. The method of claim 9, wherein said detecting step includes the steps of:

capturing a frame of image information;

sequentially analyzing a plurality of lines of image information from said captured frame; and

ceasing said detecting step if one of said lines of image information indicates the presence of edge transitions in said image information is equal to or in excess of said predetermined number.

13. The method of claim 12, wherein said analyzing step includes the step of sequentially analyzing vertical, horizontal, and diagonal lines of image information.

14. The method of claim 12, when said analyzing step includes the step of sequentially analyzing parallel spaced apart lines of image information.

15. The method of claim 9, wherein said detecting step includes the steps of:

analyzing a line image information;

establishing at least one threshold for said line; and

recording said edge transitions based on crossings of said image information of said at least one threshold.

16. The method of claim 15, further comprising the step of finding a pixel variance measurement to determine if said image information corresponds to a uniform gray scale image.

17. The method of claim 15, wherein said establishing step includes the step of setting a maximum threshold and a minimum threshold, and wherein said recording step includes the step of counting an edge transition if said image information rises above said maximum threshold or falls below said minimum threshold.

18. The method of claim 17, wherein said establishing step includes the step of setting said thresholds according to a rule which precludes said thresholds from being established within a predetermined range of one another so that edge transitions are not recorded from image information that corresponds to a substantially uniform gray scale scene.

37. The method of claim 9, wherein said method further includes the step of implementing said method using a stationary position optical reading device.

38. The method of claim 9, wherein said method further includes the step on activity a mode change if said machine readable indicia is determined to be represented in said image information, said mode change characterized by at least one increased illumination, and activation of a decoding algorithm.

39. The method of claim 38, wherein a mode of operation of said device prior to said mode change is characterized by an illumination array being off, and a mode of operation of said device subsequent to said mode change is characterized by said illumination array being on.

40. The method of claim 11, wherein said line is a straight line of contiguous pixels.

41. The method of claim 12, wherein said plurality of lines are spaced apart.

19. An optical reading device having an imaging assembly, said optical reading device being adapted to:

generate image information from said imaging assembly;

detect edge transitions of said image information; and

change a mode of operation of said optical reading device if a number of said edge transitions is equal to or exceeds a predetermined number of edge transitions, wherein said predetermined number of transitions is at least two.

20. The optical reading device of claim 19, wherein said optical reading device is further adapted to:

capture a frame of image information;

sequentially analyze a plurality of lines of image information from said captured frame; and

cease said detection of said edge transitions if one of said lines indicates the presence of edge transitions in said image information is equal to or in excess of said predetermined number of transitions.

21. The optical reading device of claim 20, wherein said reading device in analyzing said image information, sequentially analyzes vertical, horizontal, and diagonal lines of image information.

22. The optical reading device of claim 19, wherein said reading device in detecting said edges:

analyzes a line of image information;

establishes at least one threshold for said line of image information; and

records said edge transitions based on crossings of said image information of said at least one threshold.

23. The optical reading device of claim 22, wherein said reading device further determines if said image information corresponds to a uniform gray scale image.

24. The optical reading device of claim 22, wherein said reading device in establishing at least one said threshold sets a maximum threshold and a minimum threshold, and wherein said reading device, in recording said edge transitions, counts an edge transition if said image information rises above said maximum threshold or falls below said minimum threshold.

25. The optical reading device of claim 22, wherein said reading device, in establishing said at least one threshold, sets thresholds according to a rule which precludes threshold from being established within a predetermined range of one another so that edge transitions are not recorded from image information that corresponds to a substantially uniform gray scale scene.

42. The device of claim 19, wherein said device is a stationary position optical reading device.

43. The device of claim 19, wherein said device after said mode change is characterized by at least one of the activation of an illumination array, and activation of a decoding algorithm.

44. The device of claim 19, wherein said device includes an illumination array and wherein a mode of operation of said device prior to said mode change is characterized by an illumination array being off, and a mode of operation of said device subsequent to said mode change is characterized by said illumination array being on.

45. The device of claim 20, wherein said line is a straight line of contiguous pixels.

46. The device of claim 20, wherein said plurality of lines are spaced apart.

26. An optical reading device having an imaging assembly, said optical reading device being adapted to:

generate image information from said imaging assembly;

detect edge transitions of said image information; and

change a mode of operation of said optical reading device if a number of said edge transitions of said image information is at least two, and indicates change in said number of transitions by a predetermined number of transitions.

27. The optical reading device of claim 26, wherein said optical reading device is further adapted to:

capture at least a first frame for determining a equilibrium number of edge transitions;

capture a subsequent frame of image information;

analyze at least one line of image information from said subsequent captured frame; and

activate said mode change if said at least one lines indicates that a number of edge transitions in said image information exceeds said equilibrium level by said predetermined amount.

28. The optical reading device of claim 27, wherein said reading device in analyzing said image information, sequentially analyzes vertical, horizontal, and diagonal lines of image information.

29. The optical reading device of claim 26, wherein said reading device in detecting said edges:

analyzes a line of image information;

establishes at least one threshold for said line of image information; and

records said edge transitions based on crossings of said image information of said at least one threshold.

30. The optical reading device of claim 29, wherein said reading device in establishing at least one said threshold sets a maximum threshold and a minimum threshold, and wherein said reading device, in recording said edge transitions, counts an edge transition if said image information rises above said maximum threshold or falls below said minimum threshold.

31. The optical reading device of claim 29, wherein said reading device, in establishing said at least one threshold, sets thresholds according to a rule which precludes thresholds from being established within a predetermined range of one another so that edge transitions are not recorded from image information that corresponds to a substantially uniform gray scale scene.

47. The device of claim 26, wherein said device is a stationary position optical reading device.

48. The device of claim 26, wherein said mode of operation of said device after said mode change is characterized by at least one of the activation of an illumination array, and activation of a decoding algorithm.

49. The device of claim 26, wherein a mode of operation of said device prior to said mode change is characterized by an illumination array being off, and a mode of operation of said device subsequent to said mode change is characterized by said illumination array being on.

50. The device of claim 29, wherein said line is a straight line of contiguous pixels.

51. The device of claim 26, wherein said device is adapted to plurality of spaced apart lines when detecting said edge transitions.

52. A stationary position, presentation style optical reader, comprising:

a 2D imaging assembly disposed for generating image data corresponding to a target;

an illumination assembly;

a control unit in communication with said imaging assembly and said illumination assembly, adapting said reader to;

capture a frame of image data;

analyze at least one line of image data of said frame;

detect edge transitions in said at least one lie; and

change a mode of operation of said reader if a number of edge transitions in said line is at least two and if said number of transitions is equal to or exceeds an amount previously determined to indicate there being a decodable indicia intersected by said line, said mode of operation after said mode change characterized by at least one of an increase in an illumination level of said reader and an actuation of a decoding algorithm.

53. The reader of claim 52, wherein said control unit analyzes a plurality of spaced apart lines in said image data.

54. The reader of claim 52, wherein said control unit sequentially analyzes a plurality of spaced apart lines in said images data and ceases said analysis of said lines if one of said lines includes a number of edge transitions indicative of there being decodable indicia intersected by said line.

55. The reader of claim 52, wherein said mode of operation said reader after said mode change is characterized by an increase in an illumination level of said illumination assembly.

56. The reader of claim 52, wherein a mode of operation of said reader said mode change is characterized by an actuation of a decoding algorithm.

57. The reader of claim 52, wherein said control unit in detecting said edge transitions, establishes at least one threshold for said line and records said edge transitions based on crossings of said image information of said at least one threshold.

58. The reader of claim 52, wherein said control unit is further adapted to determine a pixel variance method measurement to determine if said image data corresponds to a uniform gray scale image.

59. The reader of claim 52, wherein said reading device in establishing at least one said threshold sets a maximum threshold and a minimum threshold, and wherein said reading device, in recording said edge transitions, counts an edge transition if said image information rises above said maximum threshold or falls below said minimum threshold.

60. The reader of claim 52, wherein said reading device, in establishing said at least one threshold, sets thresholds according to a rule which precludes threshold from being established within a predetermined range of one another so that edge transitions are not recorded from image information that corresponds to a substantially uniform gray scale scene.

61. The reader of claim 52, wherein said at least one line comprises a straight line of contiguous pixels.

62. A stationary position, presentation style optical reader, comprising:

an imaging assembly disposed for generating image data corresponding to a scene including a background having a plurality of edges;

an illumination assembly;

a control unit in communication with said imaging assembly and said illumination assembly, adapting said reader to;

capture at least one frame of image data;

analyze at least one line of image data of said frame to determine an equilibrium level of edge transitions, said equilibrium level of edge transitions indicating a number of edge transitions of said background intersection by said line;

capture a subsequent frame of image data;

detect edge transitions in said at least one line from said subsequent frame; and

change a mode of operation of said reader if a number of edge transitions in said line exceeds said equilibrium level of transitions by an amount previously determined to indicate there being a decodable indicia intersected by said line, said mode of operation after said mode change characterized by at least one of an increase in a illumination level of said reader and an actuation of a decoding algorithm.

63. The reader of claim 62, wherein said control unit analyzes a plurality of spaced apart line in said image data.

64. The reader of claim 62, wherein said control unit sequentially analyzes a plurality of spaced apart lines in said image data and ceases said analysis of said lines if one of said lines includes a number of edge transitions indicative of there being decodable indicia intersected by said line.

65. The reader of claim 62, wherein said mode of said reader after said mode change is characterized by an increase in said illumination level.

66. The reader of claim 62, further characterized by an actuation of a decoding algorithm.

67. The reader of claim 62, wherein said control unit in detecting said edge transitions, establishes at least one threshold for said line and records said edge transitions based on crossings of said image information of said at least one threshold.

68. The reader of claim 62, wherein said control unit is further adapted to determine a pixel variance method measurement to determine if said image data corresponds to a uniform gray scale image.

69. The reader of claim 62, wherein said reading device in establishing at least one said threshold sets a maximum threshold and a minimum threshold, and wherein said reading device, in recording said edge transitions, counts an edge transition if said image information rises above said maximum threshold or falls below said minimum threshold.

70. The reader of claim 62, wherein said reading device, in establishing said at least one threshold, sets thresholds according to a rule which precludes threshold from being established within a predetermined range of one another so that edge transitions are not recorded from image information that corresponds to a substantially uniform gray scale scene.

71. The reader of claim 70, wherein said line comprises a straight line of contiguous pixels.