Methods and apparatus for aligning print heads

• US 20060092199A1
• Filed: 12/22/2004
• Published: 05/04/2006
• Est. Priority Date: 11/04/2004
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kurita, Shinichi, Shang, Quanyuan, White, John M., Ji, Hongbin, Jozwiak, Janusz, Sze, Fan Cheung, Beer, Emanual, Huang, Inchen
• Granted Patent: US 7,556,334 B2
• Time in Patent Office: Days
• US Class Current: 347/9
• CPC Class Codes: B41J 2/04505 aiming at correcting alignment
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04581 controlling heads based on piezoelectric elements
• CPC Class Codes: B41J 2/04588 using a specific waveform
• CPC Class Codes: B41J 2/0459 Height of the driving signal being adjusted
• CPC Class Codes: B41J 2/04593 Dot-size modulation by changing the size of the drop
• CPC Class Codes: B41J 2/125 Sensors, e.g. deflection sensors nozzle clogging detection for cleaning reasons B41J2/16579; detection for compensation for failed nozzles B41J2/2139
• CPC Class Codes: B41J 25/001 Mechanisms for bodily moving print heads or carriages parallel to the paper surface
• CPC Class Codes: B41J 25/003 for changing the angle between a print element array axis and the printing line, e.g. for dot density changes
• CPC Class Codes: B41J 25/005 for serial printing movements superimposed to character- or line-spacing movements
• CPC Class Codes: B41J 29/15 Script supports connected to the typewriter or printer
• CPC Class Codes: B41J 29/393 Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns
• CPC Class Codes: B41J 3/28 for printing downwardly on flat surfaces, e.g. of books, drawings, boxes , envelopes, e.g. flat-bed ink-jet printers
• CPC Class Codes: B41J 3/407 for marking on special material
• CPC Class Codes: B41J 3/543 with multiple inkjet print heads B41J2/17503, B41J2/2103 take precedence

Abstract

In a first aspect, a system is provided. The system includes (1) a stage adapted to move a substrate relative to print heads during printing; (2) at least one print head suspended from a support above the stage and adapted to be moveable in a plane above the stage; (3) a controller operable to rotate the print head about a center of the print head; and (4) an imaging system adapted to capture an image of the print head and to determine a center point of the print head based upon images of the print head captured as the print head is rotated. Numerous other aspects are provided.

Claims

1. A system comprising:

a stage adapted to move a substrate relative to print heads during printing;

at least one print head suspended from a support above the stage and adapted to be moveable in a plane above the stage;

a controller operable to rotate the print head about a center of the print head; and

an imaging system adapted to capture an image of the print head and to determine a center point of the print head based upon images of the print head captured as the print head is rotated.

2. The system of claim 1 wherein the at least one print head is adapted to rotate in a horizontal plane.

3. The system of claim 1 wherein the imaging system includes a camera aimed upward.

4. The system of claim 3 wherein the camera is positioned below a level of a surface of the stage.

5. The system of claim 1 wherein the imaging system is further adapted to identify at least two nozzles on the print head that trace substantially similar circular paths phase shifted by 180°

on the horizontal plane as the head is rotated and to determine a center point of the print head based upon the two nozzles.

6. An apparatus comprising:

a camera adapted to capture images of a print head;

a processor coupled to the camera and operable to store images of the print head from the camera; and

a memory coupled to the processor and adapted to store processor instructions to capture an image of the print head and to determine a center point of the print head based upon images of the print head captured as the print head is rotated.

7. The apparatus of claim 6 wherein the print head is adapted to rotate in a horizontal plane.

8. The apparatus of claim 6 wherein the camera is aimed upward.

9. The apparatus of claim 6 wherein the camera is positioned adjacent to and below a stage adapted to move a substrate.

10. The apparatus of claim 6 wherein the camera is positioned below a stage adapted to move a substrate.

11. The apparatus of claim 6 wherein the processor is adapted to identify at least two nozzles on the print head that trace substantially similar circular paths as the head is rotated and to determine a center point of the print head based upon the two nozzles.

12. The apparatus of claim 6 wherein the memory is further adapted to store processor instructions to:

transmit a print head rotation request to a print head drive mechanism;

identify at least two nozzles on the print head that trace substantially similar circular paths phase shifted by 180°

on a horizontal plane above the camera as the print head is rotated; and

determine a center point of the print head based upon the two nozzles.

13. An apparatus comprising:

a camera adapted to capture images of a print head;

a processor coupled to the camera and operable to store images of the print head from the camera; and

a memory coupled to the processor and adapted to store processor instructions to;

transmit a print head rotation request to a print head drive mechanism;

identify at least two nozzles on the print head that trace substantially similar circular paths phase shifted by 180°

on a horizontal plane above the camera as the print head is rotated;

determine a center point of the print head based upon the two nozzles; and

calibrate the print head drive mechanism based on the determined center point.

14. A method comprising:

transmitting a print head rotation request to a print head dive mechanism;

capturing images of the print head as the print head is rotated; and

determining a center point of the print head based upon the images.

15. The method of claim 14 further comprising:

calibrating the print head drive mechanism based upon the determined center point.

16. The method of claim 14 further comprising:

moving a print head above a camera coupled to an imaging system.

17. The method of claim 14 wherein determining a center point of the print head includes identifying at least two nozzles on the print head that trace substantially similar circular paths phase shifted by 180°

on a horizontal plane as the print head is rotated.

18. The method of claim 17 wherein determining a center point of the print head includes determining a point on the print head that is substantially equidistant from the two identified nozzles.

19. An apparatus comprising:

a stage adapted to move a substrate relative to print heads during printing;

a plurality of print head carriages suspended from a support above the stage and adapted to be moveable in a plane above the stage;

a print head drive mechanism operable to move the print head carriages relative to the support; and

a camera mounted in one of the print head carriages in place of a print head and adapted to couple to an imaging system.

20. A method comprising:

moving a plurality of print head carriages suspended from a support in a plane above a substrate support via a print head drive mechanism; and

determining a position of the print heads using information from a camera mounted in one of the print head carriages in place of a print head.

21. The method of claim 20, wherein determining a position of the print heads includes transmitting a signal representative of an image captured by the camera to a controller.

22. The method of claim 21, wherein determining a position of the print heads further includes computing a position of the print heads based upon a known offset from the position of the camera, and

wherein the image is of a position reference mark.

23. The method of claim 21, wherein determining a position of the print heads further includes computing a position of the print heads based upon a location of an ink drop deposited by one of the print heads, and

wherein the image is of a position reference mark and the ink drop.