METHOD OF PRINTING LETTER ON KEY NOB OF KEY BOARD

摘要

(A) contacting the thermal film on a knob; and (B) pressing a ultrasonic tip on the film. The thermal film has colours to print the knob with different colors. The ultrasonic tip has a character on a contct surface. The ultrasonic is applied to a tip to weld the knob and the thermal film and then the thermal film is implanted into the knob.