Michihisa Suga

Improved Drop Ejection Characteristics through Use of Micro-Valves in Ink Jet Head

A new pressure-pulsed ink jet head with two micro-valves has been developed. This ink head gives a wide frequency response and produces little fluctuation in the velocity of the ink droplets. Drop ejection has been analyzed theoretically using a physical model, including meniscus motion in a nozzle, pressure generation by a piezoelectric transducer, and micro-valve operation. It is found that damped oscillation in the ink flow is produced by both the elastic energy of the piezoelectric transducer and the surface tension of the nozzle meniscus. This oscillation causes a deterioration in the characteristics of drop velocity versus operational frequency. However, the microvalves described here make it possible to prevent this damped oscillation, as well as to eliminate the capillarity dependency of the ink supply.

Effects of doping profile upon electrical characteristics of Gunn diodes

A one-dimensional computer simulation of Gunn diodes with zero-impedance external load has been made for various nonuniform doping profiles including asymmetrical step-like ones, linearly graded ones, and a periodic square-wave one. The distances between the electrodes and the doping level are taken as 10 µ and an order of 1015cm-3, respectively. Current-voltage characteristics, oscillation current waveforms, oscillation frequency versus applied voltage characteristics, and electric field distributions as well as their dynamic changes were computed for the profiles with various parameters. The results show that with asymmetrical doping profiles, Gunn oscillation takes place when the cathode is on the higher resistance side, while for the opposite polarity it is difficult for the oscillation to occur. In the latter case, a static high-field domain is built up in the vicinity of the anode. The results also show that the voltage dependence of oscillation frequency is enhanced by an asymmetrical nonuniformity in the doping profiles. A considerable rise of the threshold voltage of the oscillations is found for the periodic square-wave profile. An experimental result is analyzed on the basis of the computed results.

Investigations on an Ultrasonic Piezoelectric Printer

An ultrasonic piezoelectric printing technology was proposed and investigated. The printing head is composed of a multilayer piezoelectric actuator, operating in stiffened longitudinal mode, two-stage step horns and printing wire. The resonant frequency for the ultrasonic printing head is 146 kHz. The thermoplastic ink, melted by ultrasonic energy, is transferred onto the surface layer of plain rough paper by ultrasonic vibration. This technology realizes more rapid, lower noise and higher quality printing on a wide range of papers than conventional thermal transfer printing technologies. This unique non-impact printing method is useful for a personal desktop printer.

Application of Designed-Space Forming Technology

A completely new designed-space forming technology using ceramic green sheet technology and photolithographic technology has been developed for ceramics. With this technology, it is possible to make any fine space accurately and at will in ceramics. A monolithic ceramic ink jet head and a piezoelectric multilayer ceramic sound transducer were developed using this new technology. A piezoelectric ceramic material was used for these devices. Spaces for nozzles, pressure chambers and an ink chamber in the ink jet head and cabities in the ceramic sound transducer were formed in the piezoelectric ceramic body with photosensitive polymer by photolithographic technology. The ink jet head showed stable ink ejection action with low drive voltage. The ceramic sound transducer showed wide-band sound responce characteristics with low drive voltage. The new designed-space forming technology can be applied to many kinds of electronic ceramic components and devices. Using this technology, miniaturization and cost reduction can be achieved.