Some hard disk drives (HDDs) have fewer magnetic heads than the maximum number of mountable magnetic heads. Such HDDs need to be re-designed. We created a dummy head that is installed in these HDDs, enabling them to keep the gain of their vibration feature around the sampling frequency as low as an HDD having the maximum number of mountable magnetic heads.

View full abstract

The dynamic strain response of the suspension of a small form factor hard disk drive (HDD) to shock pulses was obtained experimentally for the first time. A head arm assembly (HAA) was subjected to half-sine shock pulses of varying pulse widths and amplitudes in physical linear drop tests. Dynamic strains caused by the shock pulses were measured using a strain gauge mounted on the suspension of the HAA. It was found that the dynamic strain response was sensitive to pulse width and amplitude. The damping of the HAA was also investigated from the dynamic strain results. It was found that the damping factor of the HAA depended strongly on the pulse width and amplitude.

View full abstract

Due to the requirement for higher areal densities and transfer speeds, an efficient model was constructed for the servo vibration suppression with its lumped parameters obtained from FEM structural analyses and modal analyses. State equations are presented.

View full abstract

There are power/size and price/cost constraints in realizing embedded mechatronic systems. Thus, this paper considers finite word length (FWL) effects when implementing discrete-time transfer functions in the delta form, The new implementation method named Variable Modulation Method (VMM) is previously proposed and the effectiveness is verified at MIPE2003. In this paper, this method is extended to improve the numerical accuracy by using bang-bang control law. The simulated results show that the proposed method is effective.

View full abstract

An optical matrix switch with low- insertion-loss, a flat package and flexible configuration of 18 input/output ports was developed. An array of two-axis electrostatic movable mirrors fabricated by MEMS technology was used to switch optical paths. The mean of measured insertion losses of all 64 paths in an 8×8 switch configuration was 1.1 dB; thus low insertion loss of the switch was confirmed. Loss increase caused by tilt angle drift of the mirrors was reduced to 1.1 dB by applying bias voltage.

View full abstract

In this study, we fabricated high the micro-structures of aspect ratio made of silicon or thick photoresist SU-8 using the supercritical drying technology. Form the result of silicon micro-structure fabrication, it was confirmed that the micro-structures having the high aspect ratio of 1000 can be fabricated without sticking. Further, from hand the result of SU-8 micro-structure fabrication, it was confirmed that the residual of SU-8 in the channel was flowed to the openings due to the effect of supercritical drying.

View full abstract

We propose a three dimensional micro-fluidic device for the analysis of intracellular response to localized chemical stimulation. The device has microchannels and an aperture in their side wall, where single cell is immobilized and subjected to chemical stimuli. The device was fabricated using PDMS molding of SU-8 structure and self-forming polymer bridge. Delivery of fluorescent dye, calcein, was demonstrated here.

View full abstract

In this paper, we propose innovative valveless pumping devices for microfluidic systems. The liquid in the microchannel was transported by generating a traveling wave on the channel wall, which was composed of a piezoelectric Pb(Zr,Ti)O_3 (PZT) thin film actuator array. The PZT thin films were deposited on the silicon-on-insulator (SOI) substrates where microchannels, 200 and 500μm wide, were fabricated. The maximum displacements of the 200 and 500μm wide filled channels at 10 V_<PP> were about 61 and 219 nm, respectively. By generating a traveling wave on the channel wall, clear liquid flow could be induced with a mean flow velocity of about 118 and 172μm/s for the 200 and 500μm wide channels, respectively.

View full abstract

Currently, MRI is used not only for diagnosis but also for intraoperative surgical treatment. In order to provide intuitive visualization of MR image for surgery navigation, we developed LCD slice image overlay display that augments MR image onto patient's body. We evaluated the MRI compatibility of the overlay device based on MR images and electromagnetic wave measurements. As the result, electromagnetic wave leakage at a resonance frequency band of 0.2 T MRI was not detected, MR images were not distorted, and that the signal-to-noise ratio (SNR) decreased by 1.7%. Therefore, we conclude that the overlay device has high MRI compatibility and it is possible to use while acquiring MR images.

View full abstract

The shortage of nurses in large hospitals of developed countries has become a major problem. Especially, the shortage of scrub nurses, who assist operating surgeons exchange surgical instruments, has been chronically severe. To compensate for this shortage, we have been proposing the Scrub Nurse Robot (SNR) system that is capable of functioning as a skilled human scrub nurse in endoscopic and laparoscopic surgery. We developed the SNR, and achieved smooth and cleverly movement of its arm with 6 D.O.F.. The SNR is able to insert the tip of instrument into a small-caliber trocar cannula penetrating a patient's abdominal wall. This function is named Automatic Instrument Inserting Function (AIIF) and it helps a surgeon to exchange instruments much faster than that in the real clinical operating room between a human scrub nurse and a surgeon. The AIIF is basically composed of a commercially-available 3D position measurement system and the algorithm that we developed to enable the arm to insert the instrument into the cannula instead of a surgeon. In this paper, we constructed two types of algorithm for AIIF, and verified which one is faster than the other one. The one algorithm controls 3 D.O.F. independently (IFC). And the other one is based on the kinematic analysis and control (KAFC). In the evaluation, we compared "targeting time" that was spent for inserting into trocar cannula. As the result, KAFC finished with an average of 0.46 sec faster than IFC (IFC: 3.13±0.63 sec (N=20)), (KAFC: 2.67±0.16 sec (N=20)). We figured out that latter algorithm is able to target faster and more stable. Therefore, what we can expect is, if this arm installed in the real clinical operating room, surgeons would concentrate on the operating procedures.

View full abstract

This paper proposes a human body posture estimation method using a 3D articulated human body CG model. The estimation method is based on 2D matching between the human silhouettes extracted from camera images and the model silhouettes projected onto corresponded camera planes. The candidates of the human model silhouette is generated by using Monte Carlo filter and the XOR distance is introduced to calculate the likelihood rate between silhouettes. Experimental results confirmed the feasibility of the estimation method.

View full abstract

This paper investigates a human body posture estimation method based on back projection of human silhouette images extracted from multi-camera images. To achieve real-time 3D human body posture estimation, some improvements of the estimation algorithm are proposed in the fitting process of cylindrical human model. To evaluate the proposed method, estimation experiments of 3D human body postures are carried out. Experimental results confirm the effectiveness of the estimation method.

View full abstract

We describe optimizations of geometry as well as readout mechanism of a highly effective biomolecular detection method known as suspended microchannel resonator. Efficiency improvements lead to increase in mass resolution up to 3.6 times; furthermore new integration of piezoresistive readout method eliminates previous approach drawbacks.

View full abstract

We developed and demonstrated a laser beam alignment system for micro laser projectors. This system measured the angle and position of each laser beam axis, and aligned them with the alignment stage. We could reduce the laser beam gap of each laser beam axis to 0.55′10-3° and 1.3 mm at a projection distance of 440 mm with this system. Also we showed that the size can be reduced to several cubic centimeters.

View full abstract

Process of toner layer formation in non-magnetic single component development system of electrophotography is investigated. Experiments clarified the behavior of formed the toner volume and the toner charge with respect to rotation speed and voltage between the development roller and the supply roller. Numerical calculation of toner motion clarified the characteristics of the formed toner volume and the degradation of toner particles.

View full abstract

"Bead-carry-out" phenomenon in the two-component magnetic brush development system of electrophotography is analyzed. We have investigated characteristics of the BCO on the effect of the development voltage to find the optimum condition for decreasing the BCO. Additionally, the behavior of carrier particles in the development area has been observed with a high-speed CCD camera in order to recognize dynamics of the BCO.

View full abstract

This paper describes electrical discharge machining (EDM) at a high speed, with a high precision five degrees of freedom (5-DOF) controlled maglev actuator. To machine deep, small holes with a depth more than the stroke of the maglev actuator, a conventional EDM machine having long stroke and the maglev actuator were combined and cooperatively controlled. To avoid abnormal electrical discharge, we proposed two types of driving method for an electrode; jump and circular motions using the maglev actuator. Experimental results show that high speed and high precision adjustment of the distance between a work-piece and the electrode (EDM gap) by the maglev actuator is effective for high speed EDM. Moreover, the jump and circular motions increase the machining speed due to improvement in the ejection of debris and bubbles and decrease in the probability of abnormal electrical discharge.

View full abstract

Micro-motion stages are used for ultra-precise positioning. Accordingly, a high resonance frequency is required. That also requires a longer stroke. There are two ways to raise the resonance frequency. One is to lighten the moving part. The other is to increase the rigidity of the spring. On the other hand, to lengthen the stroke requires suppression of stress. This development does not allow the moving part to be made smaller. Therefore, it is difficult to lighten the moving part. Thus, maintaining the rigidity of the spring can achieve a high resonance frequency.

View full abstract

This paper describes the principle and basic characteristics of a new optical MEMS switch using a belt-shaped thin film mirror. The thin film mirror between the two substrates is deformed and driven by electrostatic force. The effect of the design parameters of the switch on the minimum driving voltage is examined.

View full abstract

There is a great demand to measure the surface profiles of microstructures with high accuracy. However, conventional measurement techniques, including scanning electron microscopy (SEM) imaging, atomic force microscopy (AFM) scanning, mechanical surface profiler, require often destructive process or may be difficult to measure with a wafer scale. In this paper, we implement a novel measurement technique for the surface profiles of microstructures fabricated by standard MEMS techniques using an optical scanner based on a DVD pick-up module, which is widely used in optical storages installed within PC or laptops. 2D images for the fabricated microstructures are successfully generated using the intensity signal of reflection light from the surface topologies and the depths of the microstructures are measured simultaneously using focus error signal from four-quadrant photodiodes (PD). The advantages of the proposed methods are non-destructive, non-contact, do not require any sample preparation and can be carried out with a wafer scale. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and cost-effectively, compared to conventional MEMS measurement techniques.

View full abstract

Currently, more and more surgical operations are conducted in micro areas, such as anastomosis. Microsurgery is difficult to conduct unless a hospital is adequately staffed with personnel with techniques and experiences. For this reason, this study aims to make a high precision manipulator device for anastomosis surgery to support microsurgery. Especially, the aim is to develop an unconventional, compact and lightweight manipulator for supporting microsurgery by adopting shape memory alloy which is possible for flexible movements and easy for force control so that an actuator can contract and relax. Figure 1 shows schematic illustration of this micromanipulation system.

View full abstract

Nanometer scale mechanical properties of extremely thin DLC films deposited by filtered cathodic vacuum arc (FCVA) and electron cyclotron resonance chemical vapor deposition (ECR-CVD) methods were evaluated. DLC films, whose target thicknesses are 100nm, 5nm, and 2nm were, deposited on Si (100) substrates by FCVA and ECR-CVD method. Nanoindentation hardness and nanowear resistance of these DLC films are investigated by AFM (Atomic force microscopy). Nanoindentation hardness of 100-nm-thick DLC films deposited by FCVA and ECR-CVD is 57GPa and 25GPa, respectively. The nanowear resistance of 5nm- or 2nm-thick DLC films can be evaluated by AFM at proper load conditions. Then nanowear test reveal the excellent wear resistance of the FCVA-DLC films.

View full abstract

Carbon and boron nitride nanoperiod multilayer films were deposited by bias radio frequency (RF) sputtering. Nanovibration processing was performed on the nanoperiod multilayered films with electroconductive diamond tips. In the case of processing without vibration, since the strength of the nm-period multilayer film was large, the processing volume of this film was small. Applying vibration during processing, processing depths significantly increased. Accordingly, the processed groove with nearly 2nm depth corresponding to the thickness of the multilayer film can be easily performed. In lateral vibration processing test, not only nanoprocessing but also nanometer scale evaluation can be performed due to their difference of friction force and current properties. As a result, the composition orientation of the nanoperiod multilayer film and the interface formed between C layer and BN layer were experimentally confirmed.

View full abstract

Friction and wear surfaces were observed during tribological tests using laser strobe technique to the several steel materials. As results of monitoring, the surface was wore slowly and finally fracture. The stored friction surface images were analyzed to found their features. The results indicated the surface fracture patterns were distinguished several groups by the wear size.

View full abstract

The dependences of surface energy on ultra-thin film thickness are investigated experimentally and theoretically. Langmuir-Blodgett (LB) film and Perfluoropolyether (PFPE) lubricant on solid substrates are used as ultra-thin film samples. Surface energies as a function of film thickness are experimentally obtained from contact angle measurements. The theoretical equation of the dispersive component of the surface energy of ultra-thin film is derived from a corrected van der Waals pressure equation for a multilayered system proposed by the authors. The theoretical values are found to agree with the experimental values. The theoretical equation presented in this study is considered to be useful in predicting the surface energy of an ultra-thin film on a solid substrate.

View full abstract

Friction force was measured between single-crystal silicon plates and a single-crystal-tipped gold pin under a high vacuum of 1.5×10^<-5> Pa. A reciprocating micro-tribotester was used to rub a gold pin that had a (111) and (100) surface on its spherical tip against the (111) and (100) surfaces of silicon plates, respectively. The external applied normal load was 10μN. By rotating the silicon plate, difference between each crystal orientation was changed and the relationship between the friction force and mutual angle was examined. A maximum anisotropy factor of about ten was found between the combinations of the (111) surfaces.

View full abstract

We have fabricated nano-groove surfaces using a novel nano-patterning method. One of biggest features of the proposed method is capability of fabricating nano-grooves for a wide area more than 100×100 mm^2. First, we fabricated micro-scale patterns to a silicon substrate by photolithography. Second, multilayer films were deposited by physical vapour deposition (PVD) process. For multilayer films, combinations of iron and gold (Fe-Au), and other materials were applied. Third, the substrate was polished and different material appeared on the surface as parallel stripes. Finally, additional etchings that are physical or chemical treatments applied to get nano-grooves. In this paper, we introduce some of nano-patterned surfaces.

View full abstract

High dielectric capacitor, that has around 1000 in dielectric constant, can be successfully formed by nanotransfer on non-heat-resisting substrates. PZT film could be released from the Si substrate and bonded onto the polymer one. The releasing characteristics have the relationships with the thickness of Pt layer. The formed PZT has perovskite structure and clear columnar texture.

View full abstract

Utilizing a triangular aperture for high-density "near-field recording" is thought to be one of the most promising breakthroughs to realize both higher spatial resolution and higher signal output simultaneously. We have already reported 300 nm to 100 nm line-and-space patterns readout performances of the triangular aperture, clarifying the influence of the polarization direction on the readout signals. This paper reports signal output performance in radial direction (tracking characteristics) using linearly arranged line-and-space patterns.

View full abstract

The variation of the temperature of a laser diode (LD) in a hard disk drive (HDD) was investigated. Three locations for the LD in a head-stack assembly of an HDD were assumed: on the arm, on the flexure of the head suspension, and on the slider. They were determined according to the relationship between LD size and available space. The finite element method (FEM) was used to calculate the temperature increase of the LD in the case of these three locations. The FEM result suggests that in regards to maintaining a stable light source, the temperature increase of the LD is acceptable in the case that it is located on the arm or on the slider.

View full abstract

In the Near Field Recording system, there are always possibilities of collision between the SIL and the media, because of narrow gap distance. Especially, it is weak about an external shock. To make a robust NFR system against an external shock, we propose an anti-shock air gap control method of SIL-based Near Field Recording System using an accelerometer and inverse impulse. Through repetitive experiments using an accelerometer, we estimated magnitude of external shock in a very short time that is compared with a duration time of an external shock. And because a gap error signals (GES) are almost same in experiments that are applied same external shock, we have approximated GES profiles about each external shock and we made inverse impulse for the GES profiles. So, when an external shock is applied to NFR system, a magnitude of shock is decided and inverse impulse is applied to the NFR system as magnitude of shock. Through simulations, we confirm the feasibility of anti-shock air gap control method using an accelerometer and inverse impulse.

View full abstract

This research explores the design of a dynamic vibration absorber (DVA) using an L-Shaped beam with tip mass. To design the proposed DVA, the dynamic characteristics of the optical disk drive were represented with finite element models. The dimensions of the beam were optimized to reduce the vibration effectively. The vibration-reduction performance was also measured experimentally.

View full abstract

Servo control system developed for holographic data storage system(HDSS) can be said as two types. The first type uses servo layer on the media and red laser for tracking and focusing servo control similar to conventional ODD, and the other type uses analyzed data of captured image. CISD(Center for Information Storage Device) in Yonsei University studied about servo control system of HDSS and developed another type of servo method using servo beam servo track writing method. In this paper, optical and mechanical characteristics of servo system developed by CISD are analyzed, and feasibility of the servo system is evaluated.

View full abstract

This paper investigates the method for both analyzing and optimizing moving-magnet-type actuators for optical pickups. Because of special characteristic of suggested electromagnet circuit, we consider not just electromagnetic force, but also solenoid effects that make coils to electromagnet when analyzing dynamic behavior of actuators. The moving-magnet-type actuator is fabricated and its dynamic behaviors are measured experimentally to validate the analysis method. To improve the dynamic behaviors of moving-magnet-type actuators based on analysis method, the structural simulation and electromagnetic simulation are connected to perform a coupled field analysis.

View full abstract