Apparatus and method for coating polyimide layer

1. An apparatus for coating a polyimide layer comprising:

a printing table in which a substrate is provided;

an inkjet head having an injection surface with nozzles for injecting a polyimide liquid onto the substrate;

a polyimide liquid supply tank filled with the polyimide liquid;

an inkjet head cleaner spraying a solvent onto the inkjet head using a high pressure gas;

an ultrasonic cleaner in which a cleaning liquid for cleaning the inkjet head is stored for cleaning the inkjet head with vibrations in the cleaning liquid generated by applying an ultrasonic signal; and

a wiper for wiping an injection surface of the inkjet head.

2. The apparatus of claim 1 , wherein the ultrasonic cleaner includes:

a storage unit that stores the cleaning liquid;

a ultrasonic oscillator that is mounted in the storage unit for applying ultrasonic vibrations to the cleaning liquid; and

a controller that controls an operation of the ultrasonic oscillator with electrical ultrasonic signals.

3. The apparatus of claim 2 , wherein the storage unit is mounted so that the inkjet head can be dipped into the cleaning liquid.

4. The apparatus of claim 2 , wherein the ultrasonic oscillator is in contact with the cleaning liquid and converts the electrical ultrasonic signal from the controller to a mechanical signal to vibrate the converted mechanical signal through the cleaning liquid.

5. The apparatus of claim 2 , wherein the ultrasonic oscillator is in a position opposite to the injection surface of the inkjet head.

6. The apparatus of claim 1 , wherein the cleaning liquid includes isopropyl alcohol.

7. The apparatus of claim 1 , wherein the ultrasonic signal has a frequency in a range of about 20 kHz to about 400 kHz.