Inkjet printhead with micro-electromechanical fluid ejection devices having integrated movement sensors

• US 20050225600A1
• Filed: 05/09/2005
• Published: 10/13/2005
• Est. Priority Date: 06/30/1999
• Status: Active Grant

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Granted Patent: US 7,328,977 B2
• Time in Patent Office: Days
• US Class Current: 347/54
• 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

An inkjet printhead comprises a plurality of micro-electromechanical fluid ejection devices, each having a substrate and semiconductor layer positioned on the substrate. The substrate and the semiconductor layer define a fluid inlet chamber. A nozzle chamber defining structure is positioned on the substrate to define a nozzle chamber in fluid communication with the fluid inlet chamber and a fluid ejection port in fluid communication with the nozzle chamber. An actuator is fixed, at one end, to the substrate. The actuator incorporates a heating circuit electrically connected to the semiconductor layer. The heating circuit is configured to generate thermal differential expansion and contraction upon excitation and de-excitation by the semiconductor layer so that the actuator is cyclically displaced relative to the substrate. A fluid ejection member is fixed to an opposite end of the actuator and positioned with respect to the nozzle chamber so that resultant displacement of the fluid ejection member causes fluid to be ejected from the fluid ejection port. A movement sensor is positioned on the actuator to determine an extent of movement of the actuator.

Claims

1. An inkjet printhead comprising a plurality of micro-electromechanical ejection devices for ejecting ink onto print media, at least some of the devices comprising:

a substrate;

a semiconductor layer positioned on the substrate, the substrate and the semiconductor layer defining a fluid inlet chamber;

a nozzle chamber defining structure positioned on the substrate to define a nozzle chamber in fluid communication with the fluid inlet chamber and a fluid ejection port in fluid communication with the nozzle chamber;

an actuator that is fixed, at one end, to the substrate, the actuator incorporating a heating circuit electrically connected to the semiconductor layer, the heating circuit being configured to generate thermal differential expansion and contraction upon excitation and de-excitation by the semiconductor layer so as to effect displacement of the actuator relative to the substrate;

a fluid ejection member fixed to an opposite end of the actuator and positioned with respect to the nozzle chamber so that resultant displacement of the fluid ejection member causes fluid to be ejected from the fluid ejection port; and

a movement sensor that is positioned on the actuator to determine an extent of movement of the actuator.

2. An inkjet printhead as claimed in claim 1, wherein the actuator includes an outer arm portion that is electrically isolated from the semiconductor layer and an inner arm portion that is electrically connected to the semiconductor layer to define the heating circuit, the inner and outer portions being mechanically coupled together such that expansion and contraction of the inner portion causes the actuator arm to be displaced, respectively, away from and towards the substrate.

3. An inkjet printhead as claimed in claim 2, wherein the movement sensor includes a contact element fixed to the inner portion to be live when a current flows through the inner portion and a fixed contact element that is connected to the semiconductor layer, the contact elements being positioned to be spaced from one another under normal operation of the actuator, and to make contact with each other under excessive displacement of the actuator.

4. An inkjet printhead as claimed in claim 3, wherein the movement sensor includes amplifier circuitry connected to the fixed contact element to amplify a signal generated when the contact elements are in contact with each other and processing circuitry connected to the amplifier circuitry to process signals received from the amplifier circuitry according to predetermined algorithms.

5. An inkjet printhead as claimed in claim 2, wherein the fluid ejection member is a paddle that is interposed between the fluid inlet chamber and the nozzle chamber such that displacement of the actuator towards and away from the substrate results in displacement of the paddle towards and away from the fluid ejection port to eject fluid from the port.