Method of detecting a fault condition in a micro-electromechanical device

• US 20050046659A1
• Filed: 09/27/2004
• Published: 03/03/2005
• Est. Priority Date: 06/30/1999
• Status: Active Grant

• Current Assignee: Zamtec Limited (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Granted Patent: US 6,969,142 B2
• Time in Patent Office: Days
• 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 condition in a micro-electromechanical device includes the step of applying at least one current pulse to an actuator of the device such that the actuator is cyclically displaced at least once. The extent of displacement of the actuator is determined. The device is calibrated by determining a relationship between an operational parameter and said displacement. The device is tested by applying said parameter to the device, such that an error is detectable where said relationship is not achieved.

Claims

1. A method of detecting a fault condition in a micro-electromechanical device, the method comprising the steps of:

applying at least one current pulse to an actuator of the device such that the actuator is cyclically displaced at least once;

determining an extent of displacement of the actuator;

calibrating the device by determining a relationship between an operational parameter and said displacement; and

testing the device by applying said parameter to the device, such that an error is detectable where said relationship is not achieved.

2. A method as claimed in claim 1, in which the step of applying at least one current pulse to the actuator comprises the step of applying a series of current pulses to the actuator.

3. A method as claimed in claim 2, in which the step of determining the extent of displacement of the actuator includes the step of generating an electrical signal when the actuator is displaced to said extent.

4. A method as claimed in claim 3, in which the step of generating the electrical signal includes the step of establishing a switch that is operable upon displacement of the actuator to direct the current from the actuator to processing circuitry upon displacement of the actuator to said extent, such that a switch contact is positioned to correspond with said extent of displacement.

5. A method as claimed in claim 4, in which the step of calibrating the device includes the step of applying the series of current pulses to be of increasing duration until such time as the switch closes and a series of the electrical signals are generated such that a current pulse of a particular duration corresponds with said extent of displacement.

6. A method as claimed in claim 5, in which the step of testing the device includes the step of applying a series of current pulses of said particular duration and determining whether or not said series of electrical signals are generated.