Masumi Koizumi

High-speed chip-matrix 1200-dpi LED printhead

We have developed a novel 1200 dot per inch light emitting diode (LED) printhead for a high quality digital color printer in the next generation. Performance tests showed that the LED printhead was really suitable for a color printer printhead: an excellent light output uniformity within +/- 1 percent, a high contrast light spot of 80 percent, a high accuracy light spot position within +/- 20 micrometers , and a very high light output efficiency to realize a high-speed printing of 45 pages per minute. In order to achieve the high performance of the LED printhead, we have developed an original 1200 dpi LED array chip with 8 by 8 matrix-structured wiring. The chip-matrix LED array chip was fabricated on a double hetero structured AlxGa1-xAs epitaxial wafer using our original fabrication techniques and device 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 of bonding wires and driver integrated circuit chips on the LED printhead decreases to one-fourth, and one-half, respectively, compared to the conventional 1200 dpi printhead.