Method and apparatus for controlling the temperature of an electrically-heated discharge nozzle

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.

Description

[0001]The instant application claims priority to Provisional Application No. 61 / 142,575, which was filed on Jan. 5, 2009, and to U.S. patent application Ser. No. 12 / 139,391, filed Jun. 13, 2008. The disclosures of both applications are incorporated herein in their entirety.BACKGROUND [0002]1. Field of the Invention[0003]The disclosure relates to a method and apparatus for sensing and controlling the temperature of an electrically resistive heater which may be integrated with a discharge nozzle of a print-head. More specifically, the disclosure relates to a novel controller for controlling temperature of a discharge nozzle. The discharge nozzle can be used for depositing substantially dry ink on a surface to be used for electronic applications.[0004]2. Description of Related Art[0005]The manufacture of organic light emitting devices (OLEDs) requires depositing one or more organic films on a substrate and coupling the top and bottom of the film stack to electrodes. The film thickness ...

AI Technical Summary

Benefits of technology

[0011]In another embodiment, each discharge nozzle in an array of discharge nozzles is provided with a separate detection circuit for detecting failure mode at the discharge nozzle. Each discharge nozzle communicates with a controller for controlling the temperature of the discharge nozzle. The controller can be interposed between a power supply and the discharge nozzle. By controlling the power supplied to the discharge nozzle, the controller can increase or decrease the temperature of the discharge nozzle. The controller may optionally include a sensor for detecting the temperature of the nozzle either directly or indirectly. The sensor can also detect failure mode at the discharge nozzle. With each nozzle in the array having a sensor, the operator can readily identify a failing sensor in a large array of sensors.

Problems solved by technology

This process is inefficient, as the entire substrate must be coated, even though only the regions exposed through the shadow mask require a film.

Furthermore, the shadow mask becomes increasingly coated with each use, and must eventually be discarded or cleaned.

Finally, the use of shadow masks over large areas is made difficult by the need to use very thin masks (to achieve small feature sizes) that make said masks structurally unstable.

Furthermore, ink jet printing is conventionally limited to the use of single layer OLED film stacks, which typically have lower performance as compared to multilayer stacks.

The single-layer limitation arises because printing typically causes destructive dissolution of any underlying organic layers.

If one or more discharge nozzles should fail in a array of, for example, 120 discharge nozzles, this may not be immediately detected and the printed substrate will prove faulty after much time and labor has been expended.

When a fixed voltage is applied to the heater, 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.

Images