High-Speed Chip-Matrix 1200 dpi LED Printhead

摘要

We have developed a novel 1200 dot per inch (dpi) 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 mu 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 array chip with 8X8 matrix-structured wiring (dubbed as "chip-matrix LED array chip"). The chip-matrix LED (CM LED) array chip was fabricated on a double hetero structured Al_xGa_(1-x)As 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 (IC) chips on the LED printhead decreases to one-fourth, and one-half, respectively, compared to the conventional 1200 dpi printhead.