<title>High-speed chip-matrix 1200-dpi LED printhead</title>

Abstract

ABSTRACT We have developed a novel 1200 dot per inch (dpi) light emitting diode (LED) printhead for a high quality digital colorprinter in the next generation. Performance tests showed that the LED printhead was really suitable for a color printerprinthead: an excellent light output uniformity 1%, a high contrast light spot of 80%, a high accuracy light spotposition within 20 # m, and a very high light output efficiency to realize a high-speed printing of 45 pages per minute(PPM). In order to achieve the high performance of the LED printhead, we have developed an original 1200 dpi LED arraychip with 8x8 matrix-structured wiring (dubbed as “chip-matrix LED array chip”). The chip-matrix LED (CM LED) arraychip was fabricated on a double hetero structured Al x Ga 1-x As epitaxial wafer using our original fabrication techniques anddevice designs. This is the key for fabricating a super-high resolution array chip with a super-high light output efficiency.Moreover, the CM LED array chip made it possible to reduce an overall super-high-density printhead cost: the number ofbonding wires and driver integrated circuit (IC) chips on the LED printhead decreases to one-fourth, and one-half,respectively, compared to the conventional 1200 dpi printhead.Keywords: 1200 dpi LED printhead, color printer, matrix-structured wiring, double hetero structured, light outputefficiency, high-speed, light spot position error.