METHOD AND APPARATUS FOR CONTROLLING THE TEMPERATURE OF AN ELECTRICALLY-HEATED DISCHARGE NOZZLE

• US 20100188457A1
• Filed: 10/16/2009
• Published: 07/29/2010
• Est. Priority Date: 01/05/2009
• Status: Abandoned Application

• Current Assignee: Connor F. Madigan, Martin A. Schmidt, Valerie Gassend
• Original Assignee: Connor F. Madigan, Martin A. Schmidt, Valerie Gassend
• Inventors: Gassend, Valerie, Schmidt, Martin A., Madigan, Connor F.
• Application Number:
  US12/580,831
• Publication Number:
  US 20100188457A1
• Time in Patent Office: Days
• US Class Current: 347/17
• CPC Class Codes: B41J 2/14 Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2/175 Ink supply systems ; Circuit parts therefor
• CPC Class Codes: H10K 71/135 using ink-jet printing

Abstract

In an embodiment, the disclosure relates to a method and apparatus for fault monitoring and controlling operation of a discharge nozzle in a large array of discharge nozzles. An exemplary apparatus includes a thin, thermally conductive membrane, with an integrated thin-film electrical heater. When a fixed voltage is applied to the heater, and as the heater heats, the resistance of the heater will increase which will cause a concomitant decrease in the electrical current flowing through the heater. By measuring the resistance of the heater it can readily be determined whether the device is functioning properly.

Claims

1. A method for controlling the temperature of a discharge nozzle, the method comprising:

providing a discharge nozzle for dispensing ink, the discharge nozzle having a thermally-conductive membrane with an integrated thin film electric heater and the thin film electric heater defining a resistance;

receiving a quantity of ink in liquid-form at the discharge nozzle;

energizing the thin-film heater by applying a substantially constant current to the thin-film heater;

measuring a voltage across the heater and a current through the heater; and

determining temperature of the heater as a function of the voltage and the current; and

determining the temperature of the ink droplet as a function of the heater temperature.

2. The method of claim 1, further comprising energizing the thin-film heater by supplying electric current and measuring the ink quantity by measuring a change in the heater temperature.

3. The method of claim 1, further comprising energizing the thin-film heater by applying a plurality of voltage pulses to the thin-film heater, each voltage pulse providing substantially identical voltage and having varying pulse width.

4. The method of claim 1, wherein the step of determining temperature of the heater further comprises determining the temperature as a function of the resistance from data specific to said resistor.

5. The method of claim 1, further comprising varying the voltage to increase the temperature of the heater.

13. The system of claim 1, wherein the controller further comprises a processor circuit programmed with instructions to:

(a) determine one of the amount or the duration of activation required to discharge the quantity of ink particles to the substrate;

(b) energize the discharge nozzle consistent with the amount or duration determined in step (a); and

(c) repeat steps (a) and (b) to discharge additional quantities of ink particles onto the substrate.

14. The system of claim 1, wherein the controller further comprises at least one processor circuit in communication with a memory for storing instructions.

15. The system of claim 1, wherein the controller tasks the dispenser to provide the metered quantity of ink by providing pulsating energy to the dispenser, the pulsating energy adapted to exact a metered quantity of ink to the discharge nozzle.

6. A control system for controlling temperature of a discharge nozzle, the control system comprising:

a discharge nozzle having a plurality of conduits for receiving a quantity of liquid ink, the discharge nozzle thermally communicating with a heater;

a first metering device for measuring a voltage across the heater;

a second metering device for measuring a current through the heater;

a processor circuit for determining resistance of the heater as a function of the voltage and the current, the processor circuit controlling at least one of voltage or current input to the heater; and

a memory circuit in communication with the processor circuit, the memory containing data associating resistance with the temperature of the conduits of the discharge nozzle;

wherein the processor increases the voltage supplied to the heater to increase the temperature at the conduits of the discharge nozzle.

7. The control system of claim 6, wherein the discharge nozzle has a thermally-conductive membrane.

8. The control system of claim 6, further comprising a power supply in communication with the processor, the processor controlling at least one of voltage or current supplied to the heater.

9. The control system of claim 6, further comprising a power supply in communication with the processor, the power supply supplying voltage pulses to the heater, wherein the voltage pulses have substantially identical pulse height and varying pulse width.

10. The control system of claim 6, wherein the resistive heater is integrated with the discharge nozzle.

11. A discharge system for depositing ink on a substrate, the system comprising:

a chamber having a quantity of ink, the ink defined by a plurality of suspended ink particles in a carrier liquid;

a discharge nozzle for receiving a quantity of liquid ink from the chamber;

a heater in thermal communication with the discharge nozzle, the heater evaporating the carrier liquid at the discharge nozzle to deposit a substantially solid quantity of ink particles from the discharge nozzle; and

a controller in communication with the discharge nozzle, the controller maintaining the heater temperature by varying the voltage while maintaining substantially constant current supplied to the heater.

12. The system of claim 11, wherein the controller supplies a plurality of energy pulses to a heater, each of the plurality of pulses having a substantially constant pulse height and varying pulse width.