Video test strip reader and method for evaluating test strips

• US 5,408,535 A
• Filed: 09/07/1993
• Issued: 04/18/1995
• Est. Priority Date: 09/07/1993
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Miles, Inc. (Bayer AG)
• Inventors: Yoder, Mark A., Rogers, Robert W., Huang, Dijia, Howard, Willis E. III, Shaffer, Gerald H.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): PRIKOCKIS, LARRY J
• Application Number:
  US08/117,782
• Time in Patent Office: 588 Days
• Field of Search: 382/1, 382/8, 382/17, 382/61, 382/6, 364/526, 364/413.11, 422/58, 422/65, 422/66, 422/67, 422/87, 422/85, 422/82.05, 422/91, 436/44, 436/46, 436/47, 436/48, 436/43, 356/402, 356/408, 356/421, 250/226, 250/561
• US Class Current: 382/128
• CPC Class Codes: G01N 2021/177 Detector of the video camera type
• CPC Class Codes: G01N 2035/00108 Test strips, e.g. paper
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
• CPC Class Codes: Y10T 436/11 Automated chemical analysis

Abstract

A video test strip reader uses a video imager or camera for viewing a viewing field containing reagent test strips each having test pads reacted with a specimen containing constituents of interest. The video imager produces an analog signal representing an image of the viewing field. An image handler coupled to the video imager converts or digitizes the analog signal into a digital signal representing the image and stores the image in the form of an array of pixels representing the image. Each pixel contains color information broken down into red, green or blue (RGB). A processor coupled to the image handler analyzes the array of pixels, determines the location and orientation of a test strip, identifies the test areas on the test strip, measures the corresponding test areas on the strip at the proper times and calculates the test results, such as the concentration of the constituents of interest in the specimen or other measurable properties of the specimen such as color or specific gravity, etc. Accordingly, the video test strip reader can simultaneously locate, color analyze and time track multiple test strips on the viewing field.

Claims

1. A video test strip reader for reading reagent test strips, said test strips each having test pads, each of said test pads reacting with a sample when contacting said sample and changing color according to one or more read times for each of said test pads and an amount of a constituent or property in said sample, comprising:

a video imager adjacent to a viewing area for converting an image of said viewing area to an analog signal representing said image;

a signal converter responsive to said analog signal, said signal converter converting said analog signal into a digital signal representing said image;

an image handler responsive to said digital signal, said image handler storing said image represented by said digital signal; and

a processor coupled to said image handler for analyzing said image to determine a placement of a test strip at any location on said viewing area, said processor determining the location and orientation of a test strip on said viewing area and identifying a test pad for said test strip, said processor including a timing mechanism for tracking an elapsed time from said placement of each of said test strips, said processor analyzing a portion of said image representing an identified test pad of said test strip after said read times for said test pad, said processor calculating said amount of said constituent or property in said sample from said analysis of said portion of said image.

2. The video reader of claim 1 further comprising a transport mechanism with at least a portion of said transport mechanism being in said viewing field, said transport mechanism transporting said test strips across said viewing field.

3. The video test strip reader of claim 1 wherein said video imager is a color camera.

4. The video test strip reader of claim 1 wherein said video imager is a monochrome camera having a plurality of color filters.

5. The video test strip reader of claim 3 or 4 wherein said image handler is a frame-grabber board.

6. The video test strip reader of claim 5 wherein said processor includes a conventional personal computer, said frame-grabber board coupled to an I/O port of said personal computer.

7. The video test strip reader of claim 1 wherein said video imager includes said signal converter.

8. The video test strip reader of claim 1 wherein said image handler includes said signal converter.

9. The video test strip reader of claim 1 wherein said processor is a DSP processor on a dedicated board.

10. The video test strip reader of claim 1 further comprising an illumination source illuminating said viewing area.

11. The video test strip reader of claim 1 further comprising a storage memory coupled to said processor, said processor storing reference values in said storage memory, said processor using said reference values to calibrate said video test strip reader and compensate for any illumination variations on the viewing area.

12. The video test strip reader of claim 1 further comprising a displayer coupled to said processor.

13. A video test strip reader for reading reagent test strips, said test strips each having test pads, each of said test pads reacting with a sample when contacting said sample and changing color in proportion with one or more read times for each of said test pads and an amount of a constituent or property in said sample, comprising:

a video imager adjacent to a viewing area for converting an image of said viewing area to an analog signal representing said image;

a signal converter responsive to said analog signal, said signal converter converting said analog signal into a digital signal representing said image;

an image handler responsive to said digital signal, said image handler storing said image represented by said digital signal;

a transport mechanism with at least a portion of said transport mechanism being in said viewing area, said transport mechanism receiving said test strips and transporting said test strips across said viewing area; and

a processor coupled to said image handler for analyzing said image to determine a location and orientation for a test strip placed at any location on said viewing area, said processor identifying a test pad relative to said location and orientation for said test strip, said processor including a timing mechanism for tracking an elapsed time from the placement of said test strip, said processor analyzing a portion of said image representing a test pad of said test strip after said read time for said test pad, said processor calculating said amount of said constituent in said sample from said analysis of said portion of said image.

14. The video test strip reader of claim 13 wherein said transport mechanism has a loading end and a waste end, said viewing area is between said loading end and said waste end, said transport mechanism receives said test strips at said loading end, said transport mechanism transports said test strips across said viewing area for analysis and deposits said test strips in a waste receptacle at said waste end.

15. The video test strip reader of claim 14 further comprising a loading sensor at said loading end of said transport mechanism, said loading sensor signalling said processor that said transport mechanism has received said test strip, said processor triggering said timing mechanism for said test strip upon receiving said signal.

16. The video test strip reader of claim 15 wherein said loading sensor includes an optical interrupter utilizing a modulated light source and a synchronous photodetector such that said light source shines a light beam across said loading end of said transport mechanism directly at said photodetector, said light beam is broken upon said transport mechanism receiving said test strip, said loading sensor signals said processor upon receiving said test strip.

17. The video test strip reader of claim 13 wherein said video imager is a color camera.

18. The video test strip reader of claim 13 wherein said video imager is a monochrome camera having a plurality of color filters.

19. The video test strip reader of claim 17 or 18 wherein said image handler is a frame-grabber board.

20. The video test strip reader of claim 19 wherein said processor includes a conventional personal computer, said frame-grabber board is coupled to an I/O port of said personal computer.

21. The video test strip reader of claim 13 wherein said video imager includes said signal converter.

22. The video test strip reader of claim 13 wherein said image handler includes said signal converter.

23. The video test strip reader of claim 13 wherein said processor is a DSP processor on a dedicated board.

24. The video test strip reader of claim 13 further comprising an illumination source illuminating said viewing area.

25. The video test strip reader of claim 13 further comprising a storage memory coupled to said processor, said processor storing reference values in said storage memory, said processor using said reference values to calibrate said video test strip reader and compensate for any illumination variations on the viewing area.

26. The video test strip reader of claim 13 further comprising a displayer coupled to said processor.

27. A video test strip analyzer for analyzing an image represented by a digital signal, said image being of a viewing field with reagent test strips, said test strips each having test pads, each of said test pads reacting with a sample when contacting said sample and changing color according to one or more read times for each of said test pads and an amount of a constituent or property in said sample, comprising a processor analyzing said image to determine a location and orientation for a test strip placed at any location on said viewing area, said processor identifying a test pad for said test strip, said processor including a timing mechanism for tracking an elapsed time from said placement of said test strip, said processor analyzing a portion of said image representing a test pad of said test strip after said read times for said test pad, said processor calculating said amount of said constituent or property in said sample from said analysis of said portion of said image.

28. The video test strip analyzer of claim 27 wherein said processor includes a conventional personal computer.

29. The video test strip analyzer of claim 27 wherein said processor is a DSP processor on a dedicated board.

30. The video test strip analyzer of claim 27 further comprising a storage memory coupled to said processor, said processor storing reference values in said storage memory, said processor using said reference values to calibrate said video test strip reader and compensate for any illumination variations on the viewing area.

31. The video test strip analyzer of claim 27 further comprising a displayer coupled to said processor.

32. A method for reading reagent test strips each having test pads, each of said test pads reacting with a sample when contacting said sample and changing color in proportion to one or more read times for each of said test pads and an amount of a constituent or property in said sample, comprising the steps of:

converting an image of a viewing area into a digital signal representing said image;

storing said digital signal representing said image;

detecting a test strip placed at any location on said viewing area by analyzing said digital signal representing said image;

determining the location and orientation of said test strip on said image;

identifying portions of said image representing a test pad on said test strip;

timing said test strip starting at said detection of said test strip to obtain a current time for said test strip;

determining whether said read time for said test pad has expired by comparing said read time with the current time for said test strip;

analyzing said portion of said image representing said expired test pad to obtain a raw reflectance value for a portion of said image representing said expired test pad; and

calculating said mount of said constituent or property in said sample from said raw reflectance value for said portion of said image representing said expired test pad.

33. The method of claim 32 further comprising the initial steps of:

converting a reflectance reference image into a digital signal;

storing said digital signal in reflectance reference matrices; and

obtaining a threshold signal level from said reflectance reference matrices.

34. The method of claim 33 wherein said step of calculating further comprises compensating said raw reflectance value with said reflectance reference matrices to correct illumination variations on said viewing area and to obtain a reflectance value for said expired test pad.

35. The method of claim 32 further comprising the step of transporting said test strip across said viewing field.

36. The method of claim 32 further comprising the step of displaying results from said calculation.

37. The method of claim 32 wherein said steps following said step of converting further comprise employing a conventional personal computer.

38. The method of claim 32 wherein said steps following said step of converting further comprise employing a DSP processor on a dedicated board.

39. The method of claim 32 further comprising the step of illuminating said viewing area.

40. A method for reading reagent test strips each having test pads, each of said test pads reacting with a sample when contacting said sample and changing color according to one or more read times for each of said test pads and an amount of a constituent or property in said sample, comprising the steps of:

receiving a test strip;

transporting said test strip across a viewing area;

converting an image of said viewing area into a digital signal representing said image;

storing said digital signal representing said image;

determining a location and orientation for said test strip at any location on said viewing area by analyzing said image represented by said digital signal;

identifying portions of said image relative to said location and orientation representing a test pad on said test strip;

timing said test strip starting at said receiving of said test strip to obtain a current time for said test strip;

determining whether said read time for said test pads of said test strip has expired by comparing said read time with said current time for said test strip;

analyzing a portion of said image representing said expired test pad to obtain a raw reflectance value for said portion of said image representing said expired test pad; and

calculating said amount of said constituent or property in said sample from said raw reflectance value for said portion of said image representing said expired test pad.

41. The method of claim 40 further comprising the initial steps of:

converting a reflectance reference image into a digital signal;

storing said digital signal in reflectance reference matrices; and

obtaining a threshold signal level from said reflectance reference matrices.

42. The method of claim 41 wherein said step of calculating further comprises compensating said raw reflectance value with said reflectance reference matrices to correct illumination variations on said viewing area and to obtain a reflectance value for said expired test pad.

43. The method of claim 40 wherein said step of receiving further comprises receiving said test strip at a loading end of a transport mechanism.

44. The method of claim 40 further comprising the step of depositing said test strips in a waste receptacle at said waste end of said transport mechanism.

45. The method of claim 43 wherein said step of receiving further comprises the steps of:

employing a loading sensor at said loading end of said transport mechanism for detecting said receiving said test strip;

providing a signal that said transport mechanism has received said test strip; and

triggering a timing mechanism with said signal for said test strip.

46. The method of claim 45 further comprising the steps of:

employing an optical interrupter utilizing a modulated light source and a synchronous photodetector such that said light source shines a light beam across said loading end of said transport mechanism directly at said photodetector as said loading sensor; and

providing said signal upon said light beam being broken.

47. The method of claim 40 wherein said step of converting further comprises the step of employing a color camera.

48. The method of claim 40 wherein said step of converting further comprises the step of employing a monochrome camera having a plurality of color filters.

49. The method of claim 40 wherein said steps following said step of converting further comprise the step of employing a conventional personal computer.

50. The method of claim 40 further comprising the step of displaying results from said calculation.

51. The method of claim 40 wherein said steps following said step of converting further comprise employing a conventional personal computer.

52. The method of claim 40 wherein said steps following said step of converting further comprise employing a DSP processor on a dedicated board.

53. The method of claim 40 further comprising the step of illuminating said viewing area.

54. A method for analyzing an image represented by a digital signal, said image being of a viewing field with reagent test strips each having test pads, each of said test pads reacting with a sample when contacting said sample and changing color according to one or more read times for each of said test pads and an amount of a constituent or property in said sample, comprising the steps of:

determining a location and orientation of a test strip placed at any location on said viewing field;

identifying portions of said image representing a test pad on said test strip;

timing said test strip to obtain a current time for said test strip;

determining whether said read time for said test pad on said test strip has expired by comparing said read time with the current time for said test strip;

analyzing said portion of said image representing said expired test pad to obtain a raw reflectance value for a portion of said image representing said expired test pad; and

calculating said amount of said constituent or property in said sample from said raw reflectance value for said portion of said imaging representing said expired test pad.

55. The method of claim 54 further comprising the initial steps of:

constructing reflectance reference matrices from a digital signal representing a reflectance reference image; and

obtaining a threshold signal level from said reflectance reference matrices.

56. The method of claim 55 wherein said step of calculating further comprises compensating said raw reflectance value with said reflectance reference matrices to correct illumination variations on said viewing area and to obtain a reflectance value for said expired test pad.

57. The method of claim 54 further comprising the step of outputting said results from said calculation.

58. The method of claim 54 further comprising employing a conventional personal computer.

59. The method of claim 54 further comprising employing a DSP processor on a dedicated board.