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High-efficiency LED Printhead Technology

For the exposure unit of our color printers and multifunction devices, Fuji Xerox has been using an original all-in-one driving IC chip featuring high-precision, multifunctional light intensity control technology. This LED printhead has allowed us to build more compact devices while providing high image quality. Now, we have further improved this LED printhead technology and developed an even more efficient LED printhead, which makes it possible to achieve smaller, more energy-efficient devices as well as enhanced light intensity.

This new energy-saving LED printhead technology incorporates the newly developed current confinement self-scanning light-emitting device (current confinement SLED), which was developed based on our original vertical-cavity surface-emitting laser (VCSEL) technology. By controlling and limiting the path that the current takes, we have effectively increased the light intensity, thereby allowing high-resolution output of 1,200 dpi x 2,400 dpi while at the same time reducing power consumption. Also, because the driver circuit has now been incorporated into the light-emitting chip, the number of wires required has been reduced and multiple boards have been consolidated into one, resulting in a smaller LED printhead. This makes it possible to build more compact multifunction devices without sacrificing high-resolution printing performance.

The structure of the new current confinement SLED can be explained as follows. Because we have created a layer (oxidized area) within the current confinement SLED that blocks the flow of current (using a similar manufacturing technology used for the current-confining mechanism of VCSEL technology), the light-emitting region is now focused near the center of the SLED. This significantly reduces the current that was previously flowing on its sides, which did not contribute to light emission. Because of this improvement, the light intensity of the new SLED has increased threefold compared to that of the conventional SLED, even with the same amount of current applied. This highly efficient light emission has made it possible to conserve more energy.

Fig. 1: Cross section diagram of the current confinement SLED