Method of detecting MEM device faults with single current pulse

• US 8,038,252 B2
• Filed: 04/03/2011
• Issued: 10/18/2011
• Est. Priority Date: 06/30/1999
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Nguyen; Lam S
• Application Number:
  US13/078,998
• Publication Number:
  US 20110187386A1
• Time in Patent Office: 198 Days
• Field of Search: 347/5, 347/9, 347/19, 347/55, 347/65
• US Class Current: 347/19
• CPC Class Codes: B41J 2/04508 aiming at correcting other parameters
• CPC Class Codes: B41J 2/0451 for detecting failure, e.g. clogging, malfunctioning actuator
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• 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 2/0459 Height of the driving signal being adjusted
• 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 2/125 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 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2002/14346 Ejection by pressure produced by thermal deformation of ink chamber, e.g. buckling
• CPC Class Codes: B41J 2002/14354 Sensor in each pressure chamber
• CPC Class Codes: B41J 2002/14435 Moving nozzle made of thermal bend detached actuator
• CPC Class Codes: B41J 29/38 Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
• 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: Y10T 137/8225 Position or extent of motion indicator
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

A method of detecting a fault within a micro electro-mechanical device is provided. The micro electro-mechanical device has a support structure and an actuating arm that is movable relative to the support structure because of thermal expansion of at least part of the actuating arm caused by heat inducing current flow through at least that part. The method comprises the steps of passing a first current pulse having a predetermined duration t_p through at least the part of the actuating arm and determining movement of the actuating arm in response thereto.

Claims

1. A method of detecting a fault within a micro electro-mechanical device of a type having a support structure and an actuating arm that is movable relative to the support structure because of thermal expansion of at least part of the actuating arm caused by heat inducing current flow through at least said part, the method comprising the steps of:

providing a movement sensor comprising a moving contact element formed integrally with the actuating arm, a fixed contact element formed integrally with the support structure and electric circuit elements formed within the support structure;

passing a first current pulse having a predetermined duration tp through at least said part of the actuating arm;

determining movement of the actuating arm in response thereto to determine if the arm has moved a predetermined amount by detecting the contact made between the fixed and moving contact elements;

passing a second current pulse through said at least said part of the actuating arm, wherein the second current pulse having an energy level significantly greater than that of the first current pulse, if the movement of the actuating arm is determined not reach to the predetermined amount; and

repassing a further current pulse having an increased energy level from that of the last current pulse through said at least said part of the actuating arm, until the movement of the actuating arm is determined to reach to the predetermined amount.

2. The method of claim 1 including determining one of the amount of movement, the rate of movement, and a predetermined amount of movement of the arm.

3. The method of claim 1 including determining if the state of an electrical circuit has been changed due to movement of the arm.

4. The method of claim 3 including determining the closure of an electrical circuit.

5. The method as claimed in claim 1 when employed in relation to a liquid ejection nozzle having a liquid receiving chamber from which the liquid is ejected with movement of the actuating arm.

6. The method as claimed in claim 1 when employed in relation to an ink ejection nozzle having an ink receiving chamber from which the ink is ejected with movement of the actuating arm.