Ki-deok Bae

T-jet: a novel thermal inkjet printhead with monolithically fabricated nozzle plate on SOI wafer

A novel thermal inkjet printhead with monolithically fabricated nickel nozzle plate on SOI wafer has been proposed for the first time. A chamber and a restrictor are implemented on the 40 /spl mu/m thick top-silicon layer, and a nozzle plate covering heater layers are monolithically fabricated on them. Unlike the general back-shooters, the inkjet printhead reported here is a kind of back-shooter, which has a chamber and a restrictor with arbitrary shape by utilizing the silicon dioxide etch-stop layers in the bottom and sidewalls of chamber. Moreover, nozzle plating mold process, followed by placing the chamber underneath the heater layer, is performed on a planar surface, resulting in more uniform and reliable control of nozzle size. The new design was applied for monochrome inkjet printhead, which has 56 nozzles in 2 columns with real 600NPI(nozzle per inch), and showed good performances such as a drop velocity of 12 m/s, a drop volume of 30 pl, and a maximum firing frequency of 12 kHz for single nozzle ejection. From nozzle by nozzle inspection, we observed the uniformity variation of less than 4% in drop speed as well as drop volume. The monolithic fabrication process resulted in a good uniformity and is expected to have superior manufacturing yield to the nozzle assembly process.

An optical switch with newly designed electrostatic actuators for optical cross connects

We have developed an optical switch having low voltage driven electrostatic actuators and measured its optical performance. The simple structure of the actuator makes the fabrication process easy, helping to yield a low-cost device. In addition, a low-voltage actuating mechanism also provides good compatibility with IC and a simple driving circuit.

Characteristics of 16/spl times/16 micro optical switch

We measured the characteristics of free space type 16/spl times/16 micro optical switches. Two types of micro mirrors to switch the laser beam were used. One is electrostatic actuation type and the other is mixing (electromagnetic+electrostatic) type. We could lessen the insertion loss by arranging the lenses in zigzag style which shorten the optical path. We compared the insertion losses of the optical switches with that of in-line type bench which has loss from the optical bench part only. The loss from the bench part was about 2 dB while the total insertion loss was about 5 dB and 12 dB for each mirror type. From this result, the main reason of the insertion loss was known to be from the mirror part. The switching time was about 15 msec. and the crosstalk was less than 50 dB for both types of switches.