Printhead integrated circuit with low drive transistor to nozzle area ratio

• US 7,815,291 B2
• Filed: 06/05/2009
• Issued: 10/19/2010
• Est. Priority Date: 10/16/1998
• Status: Expired due to Fees

• Current Assignee: Zamtec Limited (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Do; An H
• Application Number:
  US12/478,769
• Publication Number:
  US 20090237433A1
• Time in Patent Office: 501 Days
• Field of Search: 347/40, 347/42, 347/54, 347/57, 347/63, 347/45
• US Class Current: 347/54
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04553 detecting ambient temperature
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/04585 controlling heads based on thermal bent actuators
• CPC Class Codes: B41J 2/04588 using a specific waveform
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/155 for line printing
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1631 photolithography
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1635 dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1639 sacrificial molding
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1646 thin film formation by sputtering
• CPC Class Codes: B41J 2/1648 Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2002/14419 Manifold
• CPC Class Codes: B41J 2002/14491 Electrical connection

Abstract

A inkjet printhead integrated circuit that has a wafer substrate with a fluid ejection surface, and an array of drop ejectors for ejecting drops of printing fluid onto a media substrate, the array being formed on the fluid ejection surface of the wafer substrate. Each drop ejector has a nozzle through which the drops are ejected, an actuator for ejecting drops through the nozzle and, a drive transistor for energizing the actuator with a drive pulse. The area of the drive transistor projected onto the fluid ejection surface is less than 37 times the area of the nozzle.

Claims

1. A printhead integrated circuit comprising:

a wafer substrate with a fluid ejection surface;

an array of drop ejectors formed on the fluid ejection surface of the wafer substrate, each drop ejector having;

a nozzle through which the drops are ejected;

an actuator for ejecting drops through the nozzle; and

,

a drive transistor for energizing the actuator with a drive pulse;

wherein,

the area of the drive transistor projected onto the fluid ejection surface is less than 37 times the area of the nozzle.

2. A printhead according to claim 1 wherein the area of the drive transistor projected onto the fluid ejection surface is less than 22 times the area of the nozzle.

3. A printhead according to claim 1 wherein the drop of ejected printing fluid is less than 2 pico liters.

4. A printhead according to claim 1 wherein the drive pulse is less than 500 nano Joules.

5. A printhead according to claim 1 wherein the drop ejectors are formed such that the area of the drive transistor projected onto the fluid ejection surface at least partially overlaps with the area of the actuator projected onto the fluid ejection surface.

6. A printhead according to claim 1 wherein the aperture of the nozzle defines an area of less than 200 μ

m².

7. A printhead according to claim 1 wherein the aperture of the nozzle defines an area of less than 100 μ

m².

8. A printhead according to claim 1 where the drive transistor has a width to length ratio between 500 and 800.

9. A printhead according to claim 1 where the drive transistor has a width to length ratio between 600 and 700.

10. A printhead according to claim 1 where the drive transistor has an on-resistance between 3 Ohms and 5 Ohms.

11. A printhead according to claim 1 where the drive transistor power consumption is less than 10% of the actuator power consumption.

12. A printhead according to claim 1 wherein the drive pulse has a voltage less than 5V.

13. A printhead according to claim 1 wherein the drive pulse has a pulse width less than 2 μ

s.

14. A printhead according to claim 1 wherein the total area of the nozzle, the actuator and the drive transistor is less than 2000 μ

m².

15. A printhead according to claim 1 wherein there are more than 3000 drop ejectors per square cm of the fluid ejection surface.

16. A printhead according to claim 1 wherein the array has more than 2000 drop ejectors.

17. A printhead according to claim 1 wherein the fluid ejection surface has an area less than 1 cm².