Microelectromechanical ink jet printhead with printhead temperature feedback

• US 7,918,540 B2
• Filed: 12/17/2004
• Issued: 04/05/2011
• Est. Priority Date: 10/16/1998
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Meier; Stephen D
• Assistant Examiner(s): Martin; Laura E
• Application Number:
  US11/013,881
• Publication Number:
  US 20050099465A1
• Time in Patent Office: 2,300 Days
• Field of Search: 347/14, 347/17, 347/60
• US Class Current: 347/60
• 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 2/04573 Timing; Delays
• 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 2/04596 Non-ejecting pulses
• CPC Class Codes: B41J 2/04598 Pre-pulse
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1626 etching
• 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 2/175 : Ink supply systems ; Circuit parts therefor
• CPC Class Codes: B41J 2/17513 : Inner structure
• CPC Class Codes: B41J 2/17553 : Outer structure
• CPC Class Codes: B41J 2002/14491 : Electrical connection
• CPC Class Codes: B41J 2202/21 : Line printing

Abstract

A microelectromechanical ink jet printhead includes a number of groups of ink ejection nozzles. Each group has a temperature sensor that is monitored by a processor incorporating the printhead. In order to maintain printing ink at a constant viscosity the processor compares temperature signals from the sensors to a predetermined threshold. In the event that the temperature signals indicate that the printhead is below a predetermined temperature then the processor applies heating pulses to the printhead. The heating pulses are of sufficient energy to cause warming of the printhead ink but insufficient to cause actual ink ejection. In this way ink ejection droplet size, and hence print quality, is maintained in spite of operating temperature fluctuations.

Claims

1. An integrated ink jet printhead chip comprising:

a plurality of ink ejection nozzles each including a thermo-mechanical ink ejection actuator formed in a substrate common with the nozzles, each actuator having first and second arms cantilevered at the substrate, each first arm being heated upon application of heating pulses so as to thermally expand relative to the respective second arm causing cantilevered bending of the respective actuator and thereby ejection of ink from the respective nozzle;

at least one integrated temperature sensor formed in a substrate common with the nozzles for monitoring the nozzle temperature and outputting a temperature signal representing the monitored nozzle temperature; and

,

a heating arrangement for applying the heating pulses to the first arms of the actuators, the heating arrangement being arranged to apply heating pulses insufficient to cause ink ejection but sufficient to cause ink warming when the temperature signal represents that the monitored nozzle temperature is below a predetermined threshold until the temperature signal represents that the monitored nozzle temperature is at or above an operational temperature of the printhead at which ink ejection for printing on print media is performed.

2. A printhead chip according to claim 1, the chip including a plurality of temperature sensors formed in the substrate.

3. A printhead chip according to claim 1, wherein the predetermined threshold is set on the basis of an ambient temperature about said printhead.

4. A printhead chip according to claim 2, wherein the at least one sensor is arranged to monitor the temperature signal whilst applying the heating pulses.

5. A printhead chip according to claim 2, wherein the plurality of temperature sensors is formed at intervals in the substrate common with the nozzles.

6. A printhead chip according to claim 5, wherein the nozzles are grouped and wherein a temperature sensor is located in each nozzle group.