Methods and apparatus for precision control of print head assemblies

• US 20060092207A1
• Filed: 02/18/2005
• Published: 05/04/2006
• Est. Priority Date: 11/04/2004
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Shang, Quanyuan, Shamoun, Bassam, Ji, Hongbin, Jozwiak, Janusz
• Granted Patent: US 7,413,272 B2
• Time in Patent Office: Days
• US Class Current: 347/14
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/0456 detecting drop size, volume or weight
• CPC Class Codes: B41J 2/04581 controlling heads based on piezoelectric elements
• CPC Class Codes: B41J 2/04591 Width 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 2/2128 by means of energy modulation control methods or devices therefor, e.g. driver circuits or control circuits B41J2/04501
• CPC Class Codes: B41J 2202/09 Ink jet technology used for manufacturing optical filters
• CPC Class Codes: G02F 1/133516 Methods for their manufacture, e.g. printing, electro-deposition or photolithography
• CPC Class Codes: H04N 1/4015 of the reproducing head

Abstract

The present invention provides methods and apparatus for controlling the quantity of fluid output (e.g., drop size) by individual nozzles of a print head to a very high precision at a frequency equal to the frequency at which fluid is normally dispensed. This is achieved by mapping fluid quantity control information into the data that represents the image to be printed. Data representative of an image is received and converted into pixel data. In at least one embodiment, the pixel data includes pixels represented by N bits, and the N bits may represent a drop size for the pixel and a union of the N bits may represent a nozzle status. A print head may be controlled based on the pixel data, and the print head may include nozzles that are each adapted to deposit at least one drop size quantity of a fluid on a substrate.

Claims

1. A method comprising:

receiving data representative of an image;

converting the data into pixel data including drop size information; and

controlling a print head based on the pixel data,

wherein the drop size information specifies a quantity of fluid per drop.

2. The method of claim 1 wherein the image is of a color filter for a display and the print head includes a plurality of nozzles each adapted to deposit at least one drop of the fluid based on the drop size information on a substrate.

3. The method of claim 1 wherein the pixel data includes pixels, each pixel is represented by N bits, and a union of the N bits represents a nozzle status.

4. The method of claim 1 wherein the pixel data includes pixels, each pixel is represented by N bits, and the N bits represent a drop size.

5. The method of claim 4 wherein the drop size is related to a pulse voltage and the N bits specify a pulse voltage.

6. The method of claim 5 wherein the pulse voltage may be a voltage within a range of voltages from V_min to V_max, and wherein a set of possible voltage values between V_min to V_max includes pulse voltage values that are stored in a database for each value of i from 1 to (2^N−

1).

7. The method of claim 6 further including creating the database based upon a pulse voltage calibration of each nozzle of the print head for each desired drop size.

8. The method of claim 7 wherein calibration of each nozzle includes determining 2^N−

1 voltage values within the range of voltages from V_min to V_max that correspond to 2^N−

1 drop sizes wherein the 2^N−

1 drop sizes are evenly distributed among a range of drop sizes D_min to D_max wherein D_min corresponds to V_min and D_max corresponds to V_max.

9. The method of claim 5 wherein the pulse voltage may be a voltage within a range of voltages from V_min to V_max, and wherein a set of possible voltage values between V_min to V_max includes pulse voltage values that equal V_min+[i*(V_max−

V_min)/(2^N−

2)] for each value of i from 0 to (2^N−

2).

10. The method of claim 9 further comprising adjusting for variations in a volume of ink deposited for a given pulse voltage between different nozzles of the print head by multiplying each of the pulse voltage values by a correction factor determined for each drop size of each nozzle during an initial calibration.

11. The method of claim 10 further comprising determining a correction factor for each of a plurality of nozzles by which to adjust the pulse voltage values in order to compensate for variations in a volume of ink deposited for a given pulse voltage between different nozzles of the print head.

12. A method comprising:

determining a desired volume of ink per unit area to be deposited within a first sub-pixel well, the first sub-pixel well having a predefined area; and

based on data representative of an image of a filter including at least a second sub-pixel well having an area different than the predefined area, depositing ink within at least the second sub-pixel well using a drop size and a number of drops that most closely match the determined desired volume of ink per unit area.

13. The method of claim 12 wherein the image of the filter is an image representative of a color filter for a display.

14. The method of claim 12 wherein depositing ink includes controlling a print head based on the data representative of the image of the filter.

15. The method of claim 12, further comprising converting the data representative of the image of the filter into drop information data wherein:

each drop is represented by N bits,

the N bits represent a drop size, and

a union of the N bits represents a nozzle status.

16. The method of claim 15, wherein depositing ink includes controlling a print head based on the drop information data.

17. A method comprising:

generating a digital image representative of a display filter, the digital image including a representation of a plurality of filter pixels;

determining image pixel data including a drop size and nozzle status for each of the plurality of filter pixels; and

controlling a print head based on the image pixel data.

18. The method of claim 17 wherein the drop size and nozzle status for each image pixel are encoded into an N-bit number for each image pixel, wherein N bits represent the drop size and a union of the N bits represents the nozzle status.

19. An apparatus comprising:

a controller including at least one driver;

a print head coupled to the controller and adapted to be controlled by the driver based on pixel data; and

a memory coupled to the controller and adapted to store data representative of an image converted into pixel data wherein;

the pixel data includes a plurality pixels,

each pixel is represented by N bits,

the N bits represent a drop size, and

a union of the N bits represents a nozzle status.

20. The apparatus of claim 19 wherein the controller is adapted to receive the data representative of an image and convert the data into pixel data.

21. The apparatus of claim 19 wherein the driver includes logic adapted to convert the drop size into a pulse voltage operable to cause a nozzle of a plurality of nozzles of the print head to dispense a volume of fluid related to the drop size.

22. The apparatus of claim 21 wherein the logic is adapted to relate each possible value of the drop size to a pulse voltage within a range of voltages from V_min to V_max, and wherein a set of possible pulse voltage values between V_min to V_max includes pulse voltage values that are stored for each value of i from 0 to (2^N−

2).

23. The apparatus of claim 22 further including:

a database for storing each possible voltage value determined based upon a calibration of each nozzle of the print head, and

wherein the database includes 2^N−

1 voltage values within the range of voltages from V_min to V_max that correspond to 2^N−

1 drop sizes wherein the 2^N−

1 drop sizes are evenly distributed among a range of drop sizes D_min to D_max wherein D_min corresponds to V_min and D_max corresponds to V_max.

24. The apparatus of claim 21 wherein the logic is adapted to relate each possible value of the drop size to a pulse voltage within a range of voltages from V_min to V_max, and wherein a set of possible pulse voltage values between V_min to V_max includes pulse voltage values that equal V_min+[i*(V_max−

V_min)/(2^N−

2)] for each value of i from 0 to (2^N−

2),

wherein the memory includes a table of correction factors determined to compensate for variations in a volume of ink deposited for a given pulse voltage between different nozzles of the print head, the correction factors having been determined for each drop size of each nozzle during an initial print head calibration, and

wherein the logic is further adapted to adjust the pulse voltage for the nozzle by multiplying the pulse voltage value by a corresponding correction factor from the table of correction factors.