Contact recording systems have been studied for future magnetic recording disks with a high recording density. Tribological key technologies for ultra-low spacing and high wear performance are required for the contact systems. Particularly, a liquid lubrication system plays an important roll for reducing a mechanical spacing and improving wear performances. However, a lubrication design concept for contact recording systems is not established. In this study, molecular design of lubricants for contact systems will be discussed from a viewpoint of bouncing and wear behaviors. As a result, a minimum bouncing height of 3 nm and a high wear performance were obtained for ion-etched contact sliders by the optimization of design parameters, i. e. pad design and lubricant material.

In a DC 50 V/5 A circuit, the relationship between the number of breaking arcs and the spatial distribution of the spectral intensity of breaking arcs of long duration near the cathode in palladium contact were examined through substitution of the contact surfaces of three different shapes: flat and spherical (1 mm radius and 2 mm radius). Findings show the distribution of spectral intensity in Pd arcs to be influenced remarkably by the shape of contact surface and the number of breaking arcs. However, the temperature of Pd arcs was affected neither by the shape of contact surface nor by the number of breaking arcs. The metal-vapor quantity present differed for flat and spherical surface contacts; however, it was not affected by the radius of the curved contact surfaces or by the number of breaking arcs. Additionally, the longer the duration of the breaking arc, the more metal-vapor was presented in the beginning of the arc. Furthermore, arc tracks on contact surfaces were observed with microscopes, clarifying that the relationship between the area of the clouded white metal on the cathode and the shape of contact surface is the same as the relationship between the existent area of measured spectra and the shape of the contact surface.

Surface damage of the electrical contact is a primary cause of failure in many electronic devices which use sliding contacts. Therefore, the quantitative observation of the contact surface is one of the most important subjects for improvement of contact reliability. In this study, in order to clarify the relationship between the contact resistance and the damage on the contact surface, a digital image measuring system (DIMS) was developed. A shadow image processing technique (SIPT) was applied to the damage analysis on the sliding contact surface. The damage width on the contact surface and the damaged image could be obtained with a 3-D graphic image by applying both DIMS and SIPT. Part of the relationship between the damage on the contact surface and the contact resistance could be obtained in the case when Cu is used for the moving contact and Cu and Ni are used for the static contact.

Effects of organic gases (1, 4-butanediol, n-hexane, phenol, and benzene) on the contact resistance (the electrical life and the mechanical life) and the sticking were evaluated. These effects were evaluated by using telecommunication relays from which the cases were removed. Contact materials were Au90Ag10(clad)/Ag40Pd60 (base). Test conditions were as follows: In the cases of the electrical life test and the mechanical life test: Load conditions: DC28 V, 100 mA and 0 V, 0 mA. Temperature: 85. Frequency: 5 Hz. Number of operations: 2,500,000 times. In the case of the sticking test: Load condition: DC96 V, 140 mA. Temperature: 50. Frequency: 5 Hz. Number of operations: 2,000,000 times. It was found that the electrical life was more than 2,500,000 times, the mechanical life was more than 2,500,000 times, and the sticking didnt occur in the case of 1, 4-butanediol. The electrical life was improved by adding 1, 4-butanediol to phenol and benzene, respectively.

Gold on connector contacts is superior in environmental resistance. However, pores existing gold film are source to trigger the corrosion reaction between gold and base metal. For examination of the contacts, it has been popular to apply "Salt Spray Test" and "Sulfur Dioxide Test. " There are some differences of the corrosion products between two tests. Main metal forming the product in Salt Spray is Copper, and main metal in Sulfur Dioxide is Nickel. To investigate the reason, we tried to employ an electro-chemical method. As a result, it was found that there was the difference between the respective galvanic cell combinations generated through pores.

We discussed on relationship between the width of slit ray and the accuracy of the measurement system for surface profile of electric contact. To obtain resolution of 10 [µm], we designed the mechanism which keeps constant the focal length between the object and the lens. As a result, the width of slit ray was clear in the whole surface. A section image could measured exactly and enhanced the resolution.

Fiber physical contact (FPC) is proposed and demonstrated as a new method designed to enable fibers to be connected easily with a small structure while maintaining high optical performance. FPC is performed by mating two bare optical fibers in a micro sleeve and fixing them to a holder while they are buckled. Buckling is a phenomenon whereby a long column is bent by compression along its length. PC connection is realized by the buckling force of the fibers themselves and does not require any springs. Optical fiber buckling is studied both theoretically and experimentally. The buckling force, which is determined by an initial span between the optical fiber holding points, remains constant when the span is changed and is useful as the PC force. The buckling amplitude which is determined by the span reduction must be so small that it does not cause excess radiation loss. A suitable span is about 7 mm. This generates a 0.7 N. The allowed span reduction is 0.1 mm. This results in a buckling amplitude of 0.64 mm which prevents radiation losses of above 0.1 dB for 1.31 µm light. Based on a study of fiber buckling, we demonstrate the optical performance for FPC connection with a 0.126 mm diameter micro sleeve in which optical fibers are mated and with polished fiber end faces. The insertion loss is under 0.3 dB and the average return loss is 50 dB for 1.31 µm light. These values are stable in the 20 to 70 temperature range. We confirm that FPC connection realizes high optical performance with a small simple structure.

Force curves obtained from an elastic contact theory are shown and compared with experimental results. In the elastic contact theory, a pin-on-disk contact is assumed and the following interaction are taken into consideration; (i) elastic deformation, (ii) the specific energy of adhesion in the area of the contact, which is expressed as the difference between the surface energies and the interface energy, (iii) the long-range interaction outside the area of contact, assuming the additivity of the Lennard-Jones type potential, and (iv) another elastic term for the measurement system such as the cantilever stiffness of an atomic force microscope (AFM). In the limit when the stiffness is infinite, the theory conforms to Muller-Yushchenko-Derjaguin (MYD) theory. In the limit when the surface-surface interaction is negligible, the theory conforms to the analytical theory by Takahashi-Mizuno-Onzawa. In the limit when the stiffness is infinite and the long-range interaction outside the area of contact is negligible, the theory conforms to Johnson-Kendall-Roberts (JKR) theory. All parameters and all equations are normalized and the normalized force curve is obtained as the functional of only two parameters; (1) the normalized stiffness of the measurement system, and (2) the normalized distance which is used in the expression of the Lennard-Jones potential. The force-displacement plots are converted into force-penetration plots.

The effect of silicone vapour concentration on the contact failure was examined by using micro relays and motor brush-slip ring(commutator) contacts, [(CH3) 2SiO]4: D4 was used as a vapour source of silicone contamination. Because the influence of the vapour of the silicone on the contact surface can not be avoided at all times due to its gradual evaporation in the atmosphere. The contact failure caused by the silicone vapour was confirmed as formation of SiO2 on the contact surfaceby analysis of EPMA and XPS. A minimum limiting concentration level which does not affect contact reliability was found. This limiting level was 10 ppm(O.13mg/l). Validity of the limiting level was confirmed by the relationships among concentration, temperature, SiO2 film thickness and contact resistance. Furthermore, the effect of the degree of silicone polymerization on the limiting concentration was derived by an empirical formula. This silicone is found to have polymerization degree larger than D7: n=7. These results were confirmed by the contact failure data due to the silicone contamination.

Arc discharge at switching contacts is one of the key phenomena, because it strongly affects material wear/transfer, contact resistance and electromagnetic interference (EMI). The arc discharge is classified into various types from the viewpoint of its sustaining mechanism and voltage waveform. They are mainly steady arc, showering arc and initial arc. Furthermore, a steady arc consists of two stages named metallic phase arc and gaseous phase arc. In the metallic, phase arc, metal ious from the electrodes mainly sustain the arc. On the other hand, gas ions from the surrounding atmosphere play an important role in the gaseous phase. Each phase arc has different influence on contact performance and EMI. The purpose of this paper is to review the arc discharges at light duty electrical contacts, and to survey the effects of arc discharges on material transfer and EMI.

When circuits which include inductive loads are turned off by contact, showering noise generates across contact gap. Showering noise waveforms seem not to be stable in the case that wire-spring relay contact is used to turn on/off inductive load. It seems that various factors are concerned in the irregularity of showering noise waveforms. This paper clarifies the relation between showering noise waveform and the cathodic contact surface variation with the number of contact operation, and moving velocity of contact.

This paper describes the characteristics of the radiated magnetic field caused by breaking arcs between a pair of Ag, AgDdO, AgSnO2 or Pd contacts in a DC 50V/1.9-5.0A circuit. For Ag contacts, in an interrupting current less than 3.3A, the radiated magnetic field appears strongly during the metallic phase arc where the smaller the interrupting current is, the more the number of frequency spectra of the radiated magnetic field becomes. In an interrupting current more than 3.3A, the radiated magnetic field appears weakly during the metallic-gaseous transition period. For AgSnO2 and AgCdO contacts, there is a weak radiated magnetic field in the metallic-gaseous transition period and the smaller the interrupting current is, the stronger the maximum intensities of frequency spectra of the radiated magnetic field in the transition period are. For Pd contacts, the maximum intensities of frequency spectra of the radiated magnetic field do not change very much from the beginning to the end of the breaking arc, which do not depend on the interrupting current. From the experimental results, the maximum intensities of frequency spectra of the radiated magnetic fields are found to depend on the contact material. And their distribution depends on the impedance of the circuit containing the contacts that generates the breaking arc.

A vertical magnetoresistive (MR)/inductive head using the current bias technique has been developed for high-density magnetic recording. In this head, the sense current is orthogonal to the air-bearing surface (ABS). The area exposed at the ABS of the MR element is beneath the front lead, and the active area of the sensor is positioned behind that area. The MR element is composed of two permalloy films separated by a thin nonmagnetic material. The easy axis of the films is oriented parallel to the ABS and the films are magnetostatically coupled. The magnetic field created by the sense current is applied in the direction of the easy axis and the MR element is stabilized. In this head structure, no MR-element-stabilizing layer, such as an antiferromagnetic film or a hard magnetic film, is needed. Since the permalloy film beneath the front lead acts as a front flux guide, the signal flux propagates in the sensing area of the MR element behind the ABS. The new vertical MR head has the same electrical performance characteristics as the conventional horizontal MR head. The offtrack signal profile is symmetric against the track center because the magnetization of the two permalloy films rotates symmetrically in the signal-flux direction. The output signal level of this head is independent of the read trackwidth, which favors a narrow trackwidth. The exposed portion at the ABS is only connected to the common lead and is at ground potential. In this design, electrostatic breakdown does not occur and no corrosion is observed. Tests have shown that as the flying height is reduced, the error rate is reduced and noise does not increase. This head structure appears suitable for the near-contact recording of the near future.

Silver is a fundamental material for electrical contact application. In spite of high electrical conductivity and economical advantage, silver surface is corroded easily by environment contained sulfide. A corrosion product as Ag2S deteriorates the property of contact reliability. In order to examine contact reliability, the acceleration tests have been accepted widely in industries. In the present study, the acceleration factor of the contact reliability for the sulfide film on the surface of silver contact which was subject to the tarnish acceleration test was clarified in comparison with the film grown in a normal office environment. The accelerated environment based on the Japan Electric Industry Development Association (JEIDA) standard No.25 was adopted. This environment is consisted of air contained 3 ppm H2S gas under 40, 85-95% RH. The growth rate of the sulfide film (Ag2S) was evaluated by applying the ellipsometry analysis. In the results, it was found that growth of Ag2S film of 500 in thickness in the normal office environment required corrosion time of 3103 h. This thickness of 500 caused increase in contact resistance of 0.1-1.0 (Ω). However, in the accelerated environment, corrosion time decreased to 1.7 h for same thickness. Therefore, the acceleration factor was obtained by comparison of these time as 1.8103 for the standard test of JEIDA.

We are developing multimodal man-machine interfaces through which users can communicate by integrating speech, gaze, facial expressions, and gestures such as nodding and finger pointing. Such multimodal interfaces are expected to provide more flexible, natural and productive communications between humans and computers. To achieve this goal, we have taken the approach of modeling human behavior in the context of ordinary face-to-face conversations. As the first step, we have implemented a system which utilizes video and audio recording equipment to capture verbal and nonverbal information in interpersonal communications. Using this system, we have collected data from a task-oriented conversation between a guest (subject) and a receptionist at company reception desk, and quantitatively analyzed this data with respect to multi-modalities which would be functional in fluid interactions. This paper presents detailed analyses of the data collected: (1) head nodding and eye-contact are related to the beginning and end of speaking turns, acting to supplement speech information; (2) listener responses occur after an average of 0.35 sec. from the receptionist's utterance of a keyword, and turn-taking for tag-questions occurs after an average of 0.44 sec.; and (3) there is a rhythmical coordination between speakers and listeners.

We developed an eye-contact technique using a blazed half-transparent mirror (BHM), which is a micro-HM array arranged on the display surface, to make a compact eye-contact videophone. This paper describes a new BHM structure that eliminates ghosts and improves image quality. In the new BHM, the reflection and transmission areas are separated to exclude ghosts from appearing in the captured image. We evaluated the characteristics of the captured and displayed images. The results show that the contrast ratio of the captured image and the brightness of both captured and displayed images are much better than with the previous BHM.

This is an attempt to examine the contact resistance of a composite material which is used for sliding contacts. The composite material used here is sintered by dispersing the solid lubricant WS2 into the metallic base alloy Cu-Sn. A method based on Greenwood's formula is applied to determine how the calculated values are related to the contact resistance values obtained in our experiments. As a result, the composite material mated with the carbon specimen is found nearly to corresponds to the values of those calculated by the extended Greenwood's formula, whereas its value mated with the tungsten specimen does not. In short, it is concluded that the composite material mated with the carbon specimen consists of multispots.

The networked reality is defined to be the virtual reality used in networks and using networks. The paper describes several levels of the networked reality and their applications.

Reliability of an electric contact can be defined by two parameters, contact resistance and wear, and the parameters of contacts operated in arcing condition are governed by the arc discharge. Thus the measurement on the relationship between the parameters and arc phenomena is necessary to improve the contact performance. The parameters for arcing electric contacts and problems were reviewed, and new concept for electric contact testing systems was proposed. Measurement with such an advanced system should be concurrent parallel measurement, quantitative measurement of degradation, systematic measurement, and analysis of arc discharge phenomena. Some examples of advanced measurement systems and new data obtained with such systems were described. Systematic results on relationships between condition and performance parameters were obtained by systematic measurement with systematically settled conditions, such as opening speed or material condition. A measurement method for the metallic phase arc duration was developed by the authors, and role of the metallic phase arc on contact performance parameters was found from interpretation of obtained data. The real-time surface profile measurement of an operating contact and the optical transient spectrum analyser for arc light radiated from breaking contact were also described.

Plating is applied to protect contact surfaces of contact devices such as switch, relay and connector from contaminations of oxidization and sulfuration etc. Furthermore it is known that the contact resistance can be reduced when there exist plated layers on the contact surfaces which have enough thickness and low resistivity compared with substratum materials. In this paper, contact resistance between plated conductors are calculated using three dimensional finite element method. Similariry, current density distribution in a contact spot with various resistivity of plated layers are shown and relative conductance depends on the contact area fraction with thickness of plated layers are presented.