Chiaki Tanuma

Competition between Electrostatic and Capillary Forces Acting on a Single Particle

Using an AFM, interactions between a conducting particle and SiO2/Si substrates with different hydrophilicities have been investigated with voltage applied in air. Attractive forces observed on hydrophobic substrates showed simple V2 dependence at any distance, and was purely of electrostatic interaction. Forces measured for hydrophilic substrates, on the other hand, exhibited the complicated dependence on V and distance. V dependence of the force for hydrophilic substrates showed that the interaction changed continuously from electrostatic at long distances to capillary condensation at short distances including the contact region. This interaction change could be explained by electrification and deformation of the water layer adsorbing onto hydrophilic surfaces, the sudden formation of the water bridge, and the enlargement of the cross section area of the water bridge.

A dynamic model of an a-Si:H photoconductive sensor

A dynamic model of an a-Si:H photoconductive sensor under a pulse driven condition is proposed. In this model, it is assumed that a high rate of recombination at the interface between a-Si:H and the substrate occurs due to hole drift along the interface when a driving voltage is applied between the electrodes. Calculated results agree with experimental results to an accuracy of 10%. It is shown that the localized state density of the bulk a-Si:H is one of the dominant factors determining the photoresponse of the a-Si:H photoconductive sensor under a pulse driven condition, and that the minimum photoresponse time of this sensor is about 5 ms. >

CCD micro-miniature color camera

A microminiature color camera system with an extremely small camera head utilizing a CCD (computer-controlled display) image sensor is described. The camera system consists of a camera head unit with a camera holder, a camera control unit, and an AC power supply unit. The camera head is connected to the camera control unit by a 4 mm diameter, 2 m long cable. The design used separates the camera head from the control unit, so that it can meet a variety of customer needs or special purposes. Since the output signal from the camera control unit is a standard NTSC signal, it can be easily connected to a standard TV monitor or to an independent video cassette recorder. The camera head (17.5 mm in diameter and 53 mm in length) incorporates a small, wide-angle 7.5 mm focus lens, a 200000 picture element CCD image sensor with color filter array and compact electronic circuits. The design, specifications and applications of the system are discussed.

A PARALLEL-BIMORPH-TYPE PIEZOELECTRIC ACTUATOR FOR HIGH-RESOLUTION IMAGER

As minute positioning actuators for high-resolution imagers using CCD(charge coupled device)-chip-shift operation, piezoelectric bimorph actuators having low voltage drive and high-speed response are required. In this study, a highly sensitive parallel-bimorph-type piezoelectric actuator using both-ends support with a U-shaped metal plate is proposed and developed. Firstly, the effectiveness of the proposed actuator is confirmed from the frequency and displacement characteristics in relation to the added mass. Secondly, a parallel-bimorph-type piezoelectric actuator where two bimorphs are arranged parallel to each other is fabricated for use in a high-resolution imager that employs CCD-chip-shift operation for practical applications. Through those experiments, the optimal bimorph length and the U-shaped metal plate length are experimentally obtained for stable and high performance of the imager. A box-shaped package of imager, with a 22-pin, dual-in-line format, and dimensions of 30(L)×20(W)×11(H) mm is obtained. A demand displacement of 8.5×10-3 mm is obtained at a driving voltage of 13 Vp-p (30 Hz pulses).

An a-Si:H photoconductive sensor with a gate electrode

A hydrogenated amorphous silicon photoconductive sensor with a gate electrode is developed for a matrix-driven linear image sensor array. The photoresponse time for this new sensor is about 1/3 of that for a conventional photoconductive sensor. A new dynamic model is proposed to analyze the photoresponse characteristics for this sensor. The minimum photoresponse time predicted by the calculation is about 2 ms. This value is markedly short compared with that for a conventional photoconductive sensor (about 5 ms). >

A Highly Sensitive Displacing Device Using Piezoelectric Bimorph with Double-Support Structure

In order to improve displacing devices, new methods for supporting a bimorph element with a double-support structure were investigated. Consideration of bending properties revealed that, when the bimorph element was bent, the cross-sections at both of the bimorph elements ends rotated. A double-support bimorph element with U-shaped metal plates at each end was designed, the result being used. It was found that the displacement for the double-support bimorph with U-shaped metal plates was approximately 4 times larger than the displacement for a conventional double-support bimorph.

Shear-Mode Industrial Inkjet Head Using Lead-Free Piezoelectric Ceramics

A shear-mode inkjet head utilizing alkaline niobate-based lead-free piezoelectric ceramics has been developed. A prototype inkjet head with a nozzle density 150 dots per inch (dpi) was achieved on a grayscale of eight levels with a minimum ink droplet ejection of 6 pl. Furthermore, the inkjet head with a nozzle density of 300 dpi was achieved on a grayscale of four levels with a minimum ink droplet ejection of 3 pl. Although the prototype inkjet head required a high voltage of approximately twice the driving voltage of the inkjet head using lead zirconate titanate (PZT) piezoelectric ceramics, the grayscale can be realized by a multidrop method. Thus, the alkaline niobate-based lead-free piezoelectric ceramics can be used to replace PZT ceramics as shear-mode actuators for inkjet heads.

A ½-Inch 792(H) × 492(V) Pixel Colour Synchro Vision CCD Image Sensor

Publisher Summary This chapter discusses a ½-inch 792(H) × 492(V) pixel color synchro vision charge-coupled devices (CCDs) image sensor. A black and white synchro vision (SV)-CCD with CCD swing operation realizes a doubling in resolution. CCD swing operation was also applied to a one-chip color CCD with a checkerboard pixel layout. A new high-resolution SV-CCD image sensor using a ½-inch 792(H) × 492(V) pixel CCD chip has been fabricated. This device has achieved simultaneous resolution enhancement for both luminance and color signals. In addition, aliasing and Moire effects have been significantly reduced without using an optical low-pass filter. The pixel unit is composed of a photodiode and a vertical CCD register, which is optically shielded. The area of the photodiode is the aperture for incident light. A full-frame element comprises the signal stored at the first site during one field and that stored at the second, adjacent, site during the next field interval.

A High Resolution CCD Imager Module with Swing Operation

A new, high resolution CCD imager has been developed. An interline transfer CCD chip is swung synchronously at frame frequency in a horizontal direction with the aid of newly-designed piezoelectric bimorph actuators. Though the swing operation using these actuators, 560 TV line horizontal limiting resolution, is twice higher than the conventional operation, it has been realized without increasing CCD pixels on the Si-chip. The newly-designed signal processing circuit, its band being less than 7 MHz, fits the NTSC system and has achieved high-resolution images for the new device.

Simulation of a liquid droplet ejection device using multi-actuator

An equivalent circuit model for a liquid droplet ejection device using a multiactuator has been developed. The equivalent circuit was simplified using a gyrator in the synthesis of the outputs of many elements. The simulation was performed for an inkjet head having three piezoelectric elements using MATLAB/Simulink. In this model, the pressure chamber is filled with a Newtonian fluid. For this reason, the model assumed only the resistance component of the pressure chamber and the nozzle as a load. Furthermore, since the resistance component of the inlet is much larger than that of the nozzle, it is not considered in this model. As a result, by providing a time difference between the driving signals of the piezoelectric elements, we found that the pressure of the ink chamber could be arbitrarily controlled. By this model, it becomes possible to control the pressure in the ink chamber of the inkjet head required for the ejection of various inks.