Ink droplet analysis apparatus

• US 6,347,857 B1
• Filed: 09/23/1999
• Issued: 02/19/2002
• Est. Priority Date: 09/23/1999
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: ENCAD, Inc. (Eastman Kodak Company)
• Inventors: Free, Warren, Neese, David A., Purcell, David A.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Mouttet, Blaise L
• Application Number:
  US09/404,558
• Time in Patent Office: 880 Days
• Field of Search: 347/19, 347/22, 347/104, 347/105, 250/222.1, 250/559.01, 250/559.04, 250/559.05, 250/559.06, 250/559.08, 250/559.2
• US Class Current: 347/19
• CPC Class Codes: B41J 2/16579 Detection means therefor, e.g. for nozzle clogging
• CPC Class Codes: B41J 2/2135 Alignment of dots

Abstract

A droplet deposition analysis system for an ink jet printer including a flexible transparent substrate. The printer may include a light source on one side of the substrate, and an optical detector on the other side of the substrate.

Claims

1. An ink jet printer with fast and inexpensive droplet deposition analysis capability, said ink jet printer comprising:

a platen having a slot therein;

a supply reel mounted in said platen;

a strip of substantially flexible transparent film extending from said supply reel, across said platen, and into said slot;

a film drive capstan and pinch roller mounted beneath said slot and accepting said film therebetween;

a light source and an optical detector mounted adjacent to said drive capstan and said pinch roller such that said film may be advanced past said optical detector by said drive capstan while being illuminated by said light source; and

a processor coupled to receive an output of said optical detector as said film is advanced past said optical detector, wherein said processor is configured to create one or more images of an array of ink droplets on said film by said ink jet printer, wherein said processor is configured to map said one or more images onto a coordinate plane, and wherein said processor is configured to detect missing and inaccurately positioned droplets relative to said coordinate plane.

2. A droplet analysis system for an ink jet printer comprising:

a strip of flexible and substantially transparent film;

a light source on a first side of said film;

an optical detector on a second side of said film opposite said first side; and

a processor coupled to receive an output of said optical detector representative of an image of an array of ink droplets on said film, and wherein said processor compares positions of the ink droplets in the array on said film with expected positions to detect missing or inaccurately positioned droplets.

3. The droplet analysis system of claim 2 wherein said light source is mounted on a moveable print carriage.

4. The droplet analysis system of claim 2 wherein said light source is mounted to a stationary portion of said ink jet printer.

5. The droplet analysis system of claim 2, wherein said light source comprises a plurality of light sources of different colors.

6. The droplet analysis system of claim 5, wherein said plurality of light sources comprise a red light-emitting-diode, a green light emitting diode, and a blue light emitting diode.

7. The droplet deposition apparatus of claim 2, additionally comprising at least one color filter positioned between said light source and said optical detector.

8. The droplet analysis system of claim 7, wherein said color filter is positioned between said film and said optical detector.

9. The droplet analysis system of claim 7, wherein said color filter is integral to said film.

10. The droplet analysis system of claim 2, wherein said optical detector comprises a color CCD array.

11. The droplet analysis system of claim 2 wherein said optical detector comprises a linear array of photodiodes.

12. The droplet analysis system of claim 11, wherein said linear photodiode array resolution is at least approximately equal to the ink jet printer resolution.

13. The droplet analysis system of claim 11, wherein said linear photodiode array comprises approximately 400 pixels per inch or more.

14. The droplet deposition apparatus of claim 2, wherein said optical detector comprises a linear CCD array.

15. The droplet analysis system of claim 2, wherein a portion of said film is wound onto a supply reel.

16. The droplet analysis system of claim 15, additionally comprising a receptacle configured to collect film previously advanced over said optical detector.

17. The droplet deposition apparatus of claim 16, wherein said supply reel is mounted in a platen of the ink jet printer.

18. A method of analyzing ink droplet deposition in an ink jet printer comprising:

depositing a set of ink droplets onto a strip of flexible and substantially transparent film;

illuminating said film with light;

detecting intensity of light passing through said film at a plurality of locations on said film;

using detected light intensity at said plurality of locations to detect missing or inaccurately positioned droplets.

19. The method of claim 18, wherein said light comprises light in one or more selected frequency bands.

20. The method of claim 19, wherein said light comprises red, green, and blue light.

21. The method of claim 18, additionally comprising filtering the light as it passes through said film prior to detecting the intensity.

22. A method of servicing an ink jet print head comprising:

positioning said ink jet print head over a portion of a print surface which comprises a first segment of substantially transparent flexible film;

depositing a first set of ink droplets onto said first segment of substantially transparent film;

analyzing said first set of ink droplets;

performing a service routine on said ink jet print head;

advancing said substantially transparent film such that a second segment of said substantially transparent film is positioned at said portion of said print surface;

positioning said inkjet print head over said portion of said print surface;

depositing a second set of ink droplets onto said second segment of substantially transparent film without removing said first set of ink droplets;

analyzing said second set of ink droplets.

23. The method of claim 22, additionally comprising forcing ink through said ink jet print head after depositing said first set of ink droplets and before depositing said second set of ink droplets.

24. In an ink jet printer, a method of detecting malfunctioning ink ejection nozzles of a print head, said method comprising:

depositing a pattern of ink droplets onto a flexible and substantially transparent film with said print head;

acquiring a digital image of said pattern;

analyzing pixel values of said digital image so as to identify features of said pattern which are indicative of malfunctioning ink ejection nozzles.

25. The method of claim 24 wherein said depositing comprises ejecting ink droplets onto a substantially transparent substrate.

26. The method of claim 24, wherein said acquiring comprises advancing said deposited ink droplets past an optical detector.

27. An ink jet printer comprising:

a platen having an opening therein;

an optical detector mounted-beneath said opening; and

a light source mounted beneath said opening,

a flexable film threaded through said opening and between said optical detector and said light source, and

a processor coupled to receive an output of said optical detector representative of an image of an array of ink droplets on said film, and wherein said processor compares positions of the ink droplets in the array on said film with expected positions to detect missing or inaccurately positioned droplets.

28. The ink jet printer of claim 27, wherein the film is a substantially transparent strip of flexible film.

29. The ink jet printer of claim 28, additionally comprising a drive capstan in contact with said film to advance said film past said optical detector.

30. The ink jet printer of claim 29, wherein said optical detector comprises a linear array of photodiodes oriented transverse to the direction of advance of said substantially transparent film.

31. A method of servicing a droplet deposition system in an ink jet printer comprising:

removing a substantially empty transparent film supply reel from a mounting bay in a print surface of said ink jet printer, wherein said print surface is adjacent to a path of substrate material during normal printing operations;

installing a second supply of substantially transparent film into said mounting bay; and

threading an end of the second supply of substantially transparent film through a slot in said print surface such that said film passes between a light source and an optical detector.

32. A method of ink jet printing comprising:

depositing an array of ink droplets onto a flexable transparent substrate;

passing light through said transparent substrate and into an optical detector so as to detect said array of ink droplets;

mapping said array of ink droplets onto a coordinate field; and

detecting at least one ink droplet which is incorrectly placed relative to said coordinate field.

33. The method of claim 32, additionally comprising servicing an ink jet print head in response to said detecting.