| 1. |
Aam Muharam, Suziana Ahmad, Reiji Hattori, Daiki Obara, Mitsuru Masuda, Kristian Ismail, Abdul Hapid, An Improved Ground Stability in Shielded Capacitive Wireless Power Transfer, 2019 International Conference on Sustainable Energy Engineering and Application, ICSEEA 2019, 2019.10, A shielded capacitive power transfer (S-CPT), a method of wireless power transmission (WPT) in which using electric field resonant (EFR) with an improved ground stability is proposed in this paper. The feature of ground stability can be succeeded simultaneously by using 1:1 Ruthroff transmission line transformer (TLT) balun. The unbalanced condition from the power source is converted to the balanced condition by the transformer. The analytical study of the shield plate voltage stability is also described both the simulation and hardware experiment. By using Spice software, with the proposed system, the simulation results show the constant zero voltage value from the shield plate to the ground. An experiment was conducted for validations of the proposed S-CPT with balun at 6.78 MHz resonant frequency. A measured shield voltage was compared under the unbalanced and balanced condition with the value of 20 V (peak to peak) and steadily of 5 V (peak to peak). An enhancement of the shield voltage ground stability is developed successfully with 75% of swing voltage reduced by the implementation of the TLT balun.. |
| 2. |
Aam Muharam, Mitsuru Masuda, Reiji Hattori, Abdul Hapid, Compactly Assembled Transmitting and Receiving Modules with Shield for Capacitive Coupling Power Transfer System, 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer, WoW 2019, 2019.06, This paper proposes a compact module of transmitting and receiving unit which has a shield part for capacitive coupling power transfer (CPT) system, and describes the analytical study of the shielded CPT structure with the simplest design approach. The Spice simulation results show the stability of shield voltage expressed by a constant zero voltage and the resonant inductance does not be affected by the change of coupling capacitance or the coupler distance. Power ratio of output over input, -0.8 dB or 83% at 10 cm couplers distance in the range of working frequency from 13.00 MHz to 13.57 MHz can be obtained with an experimental setup. The system can maintain the efficiency to the level 66% for tolerance 3 cm misalignment in Y-axis. With a 1 cm gap between the shield-plate and the coupler, it shows a thin and compact transmitting and receiving module.. |
| 3. |
Tarek M. Mostafa, Dai Bui, Aam Muharam, Reiji Hattori, Aiguo Patrick Hu, A Capacitive Power Transfer System with a CL Network for Improved System Performance, 2018 IEEE Wireless Power Transfer Conference, WPTC 2018, 2019.02, This paper introduces the analysis and optimization of capacitive power transfer system with a CL compensation circuit on the secondary for reduced voltage stress across the electric field coupling interface and less system sensitivity. The system has been mathematically analyzed to understand the effect of the CL circuit. And simulation and experimental studies are also carried out for verifications. It is found by increasing Cp (and reducing Lp accordingly to be tuned to the nominal frequency), the quality factor (Q) can be reduced to make the system less sensitive to circuit parameter and load variations, thus easier to tune. However, the CL network should be carefully designed to reduce the voltage stress and electric field leakage around the interface. A practical circuit is built which has demonstrated 5 W of power transfer across a combined interface capacitance of ∼ 1 nF at an operating frequency of 1 MHz, and the system power efficiency is above 65%. The voltage stress and sensitivity reduction have been confirmed practically.. |
| 4. |
Aam Muharam, Tarek M. Mostafa, Asep Nugroho, Reiji Hattori, Power Loss Analysis of Inverter with and without Transformer for Capacitive Power Transfer, 2018 IEEE Wireless Power Transfer Conference, WPTC 2018, 2019.02, This paper investigates the power loss characteristics in the circuit for the capacitive power transfer (CPT) system using analog circuit simulation focusing on the high voltage pulse generator with and without step-up transformer. The CPT usually has low capacitance value in their coupled capacitance due to the physical dimension and low dielectric constant of the interface, hence the high voltage with high-frequency switching needed to transfer the power through it. Using a simple LC resonant circuit and 1 MHz frequency operation, the power losses in inverter MOSFETs and transformer are analyzed under the condition with output power of 200W at 200Ω load resistance. The simulation results indicate that the inverter with step-up transformer with lower series resistance in both of wire strands can decrease the losses at MOSFETs with better efficiency compared to the high DC voltage supplied inverter without step-up transformer.. |
| 5. |
Aam Muharam, Tarek M. Mostafa, Asep Nugroho, Abdul Hapid, Reiji Hattori, A single-wire method of coupling interface in capacitive power transfer for electric vehicle wireless charging system, 6th International Conference on Sustainable Energy Engineering and Application, ICSEEA 2018, 2019.01, This paper proposes a new approach of coupling interface configuration on capacitive power transfer (CPT) for electric vehicle wireless charging system. CPT has several advantages in use of wireless charging system for short range application such as electric vehicle. One of the advantages is flexibility of coupling interface. Two-pairs of plate usually used to acquire electric field work in order to deliver some amount of designated power. This paper studies a single-wire coupling interface for EV charging system. Simulation has been done in SPICE software with the consideration of parasitic components appearing in the system. As the result, at 3.3 kW output power delivered, the coupling voltage and chassis voltage were measured at 24,720 V and 114V, respectively. This level is obtained when the coupling and chassis capacitances are 1.1 pF and 442 pF, correspondingly. The values are extracted by the electric field simulation on a normal size car.. |
| 6. |
Dai Bui, Tarek M. Mostafa, Aiguo Patrick Hu, Reiji Hattori, DC-DC Converter Based Impedance Matching for Maximum Power Transfer of CPT System with High Efficiency, 2018 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer, Wow 2018, 2018.08, It is well known that a DC or fully tuned inductive power transfer (IPT) system operating at its maximum power output point results in a low power efficiency being equal or below 50%. Based on the analyses of the maximum power transfer condition against the detuning factor of an LC resonant circuit, this paper proposes a Capacitive Power Transfer (CPT) system which can track the maximum power output using a DC-DC converter, at the same time achieve a high-power efficiency when the circuit is not fully tuned. The method is applied to a voltage-fed inverter at series tuned off-resonance operation for reduced power losses. A prototype system is built with a half-bridge inverter to drive the capacitively coupling circuit, and a buck-boost converter is designed for impedance matching. A perturb and observe algorithm is developed for controlling the duty cycle of the DC-DC converter to track the maximum power against load variations. It is found that under a fixed electric field coupling condition, the system can maintain the maximum power transfer operation at 10W and achieve a power efficiency of about 70% over a wide range of load variation from 5mathbf{Omega} to 500mathbf{Omega}.. |
| 7. |
Fahed Elsamnah, Reiji Hattori, Muhamad Affiq, Chang Hoon Shim, Anubha Bilgaiyan, Ryutaro Sugawara, Reflectance-based monolithic organic pulsemeter device for measuring photoplethysmogram signal, 2018 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2018, 2018.07, Photoplethysmogram (PPG) signal is an essential bio-signal that can be used for detecting several heart diseases. It has become fundamental to wearable health monitoring devices. The human vital signs, such as heart rate (HR), Oxygen saturation (SpO2) and respiration rate, can be clearly extracted from the PPG signal. In this paper, we applied reflectance pulse measurement method on an organic optoelectronic device to measure the PPG signal. We fabricated a monolithic device, a red (625nm) organic light-emitting diode (OLED) and an organic photodiode (OPD) sensitive at the aforementioned wavelength. The external quantum efficiency (EQE) of the OLED and the OPD were 7% and 47%, respectively. In this work, we utilized a Bluetooth Low Energy (BLE) for sending the measured PPG signal to the central side, desktop computer. The data traffic of the BLE module was 2 kbps at the minimum connection interval 7.5 ms. The reflectance method showed very good results of (1.5) percent error of the heart rate compared to the commercially reference we obtained.. |
| 8. |
A. Bilgaiyan, R. Sugawara, F. Elsamnah, C. Shim, Md Affiq, Reiji Hattori, Optimizing performance of reflectance-based organic Photoplethysmogram (PPG) sensor, Organic and Hybrid Sensors and Bioelectronics XI 2018, 2018.01, Wearable sensors enable the continuous monitoring of various physiological conditions of individuals without constraints on time and place. Primary vital signs of human body such as; heart rate (HR), Oxygen saturation (SpO2) and respiration rate, can be extracted from the PPG signal. In comparison to conventional inorganic based sensors, the use of organic semiconductor-based devices opens the possibility of devising inexpensive, lightweight, flexible sensors. Reflection-mode PPG sensors overcome the limitations posed by transmission-mode PPG sensor as it can be positioned anywhere on the body. The state of art has not exploited the reflection-mode of PPG sensors extensively, as opposed to transmission-mode. In this work, we have fabricated reflection mode PPG sensor, which comprises of a red (631 nm) organic light emitting diode (OLED) (EQE = 8%) and organic photodetector (OPD) (EQE =47 %) on the same substrate. With motivation to improve the existing PPG sensing technologies, OLED and OPD performances were optimized on a single substrate. Further, we have estimated the best pattern and optimal distance between OLED and OPD in order to maximize signalnoise ratio and lower the power consumption of the device. An analog circuit is designed to read out PPG signals. For realtime pulse monitoring, the signals were sent via a Bluetooth interface to the computer. In summary, a low cost, organic based sensor is developed to detect the heart rate with wireless enabled data monitoring. Our device displayed promising results with 1.5 % error in the heart rate measurement compared to the commercial reference.. |
| 9. |
Yutaro Ono, Yuhei Morimoto, Reiji Hattori, Masayuki Watanabe, Nanae Michida, Kazuo Nishikawa, Smart steering wheel with swept frequency capacitive sensing, 23rd International Display Workshops in conjunction with Asia Display, IDW/AD 2016, 2018.01, We present a smart steering wheel that detects the gripping position and area, as well as the distance to the approaching driver's hands by measuring the resonant frequency and its resistance value in an LCR circuit composed of the floating capacitance between the gripping hand and the electrode of the steering, and the body resistance. The resonant frequency measurement provides a high sensitivity that enables the estimation of the distance to the approaching hand, the gripping area, of a gloved hand, and for covering the steering surface with any type of insulating material. This system can be applied for drowsiness detection, driving technique improvements, and for customization of the driving settings.. |
| 10. |
Aam Muharam, Tarek M. Mostafa, Reiji Hattori, Design of power receiving side in wireless charging system for UAV application, 2017 International Conference on Sustainable Energy Engineering and Application, ICSEEA 2017, 2017.07, This paper proposes a design of power receiving side on capacitive coupling wireless power transfer for an unmanned aerial vehicle (UAV). In order to minimize a component used in the system and fitted the circuit to the drone, the realized system must be very compact and efficient. The power receiving circuit in CPT system for simple application consists of rectifier and capacitor. In an advanced method, several components added into a circuit that makes the size and weight of the system increased. In this paper, all resonant matching system is placed and controlled in the primary side, thus the secondary side circuit could have a light module with minimum components. This paper focuses on the design a secondary side of CPT consisted of a rectifier, a DC-DC buck converter, and a charging circuit. The system is designed to operate with wide range input voltage. Simulation and experimental results have demonstrated that the proposed system could obtain charging process for Li-Ion cells battery by the output power of 8 W, with the power efficiency exceeding of 77%.. |
| 11. |
Tarek M. Mostafa, Aam Muharam, Reiji Hattori, Wireless battery charging system for drones via capacitive power transfer, 2017 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer, WoW 2017, 2017.06, We developed the wireless battery charging system for an unmanned aerial vehicle (UAV) or a drone using the capacitive power transfer (CPT) technology which provides a wide charging area for the drone to land especially required at autonomous flying. As the circuit on the power receiving side or drone side must be small and light in this application, we employ the circuit where a matching circuit, a transformer and all inductors are placed in the emitting side and the circuit in the receiving side is composed of the small devices using semiconductor elements for DC-DC converter and charge controlling IC. The system validity has been verified with prototype that delivered ∼12W through a combined interface capacitance of 500 pf at an operating frequency 6.78MHz and efficiency exceeding 50%.. |
| 12. |
Yutaro Ono, Yuhei Morimoto, Reiji Hattori, Masayuki Watanabe, Nanae Michida, Kazuo Nishikawa, Smart steering wheel with swept frequency capacitive sensing, 23rd International Display Workshops in conjunction with Asia Display, IDW/AD 2016, 2016.01, We present a smart steering wheel that detects the gripping position and area, as well as the distance to the approaching driver's hands by measuring the resonant frequency and its resistance value in an LCR circuit composed of the floating capacitance between the gripping hand and the electrode of the steering, and the body resistance. The resonant frequency measurement provides a high sensitivity that enables the estimation of the distance to the approaching hand, the gripping area of a gloved hand, and for covering the steering surface with any type of insulating material. This system can be applied for drowsiness detection, driving technique improvements, and for customization of the driving settings.. |
| 13. |
Yuhei Morimoto, Ryota Yoneda, Reiji Hattori, Skin resistance measurement using static capacitive touch panel, 2015 SID International Symposium, 2015.06, We present a novel touch-sensing system that detects the skin resistance of a touched finger using a static capacitive touch panel The employed frequency-scan method enables us to measure skin resistance regardless of touching conditions. The proposed system can create new touch-sensor applications such as multiuser system and bioelectrical sensing.. |
| 14. |
Yoshimitsu Murozono, Reiji Hattori, Tsukasa Yagi, Kazuyoshi Omata, Flexible OLED lighting panel with capacitive coupling wireless power supply, 22nd International Display Workshops, IDW 2015, 2015.01, An organic light-emitting diode (OLED) lighting panel is powered by a capacitive-coupling wireless-power transmission system with a wide power-receiving position. The panel consists of only OLEDs with flexible plastic substrate and rectifying diodes, which result in a very simple and ultrathin lighting device.. |
| 15. |
Chang Hoon Shim, Chihiro Tsukii, Seung Kyum Kim, Reiji Hattori, Tsuneo Munakata, Precise simulation of brightness variation on whole AMOLED panel caused by power line voltage drop, 22nd International Display Workshops, IDW 2015, 2015.01, A precise simulation method to evaluate the brightness variation across an entire AMOLED panel with actual pixel numbers caused by power line voltage drop is presented. The voltage drop is evaluated for four types of simplified compensated pixel circuits which cover all of the AMOLED pixel circuits.. |
| 16. |
Shoichiro Tsukamoto, Naoto Iizasa, Kuniaki Yoshitomi, Ramesh Pokharel, Keiji Yoshida, Reiji Hattori, Haruichi Kanaya, Daisuke Kanemoto, Development of a rectenna for batteryless electronic paper, 2013 IEEE International Conference of IEEE Region 10, IEEE TENCON 2013, 2013.12, This paper describes the design of a rectenna for batteryless electronic paper. The rectenna is composed of a one-sided directional flexible antenna and a booster rectifying circuit that is composed of a series resonant circuit and a Cockcroft-walton circuit. The proposed one-sided directional flexible antenna has a bottom floating metal layer that enables one-sided radiation. The booster rectifying circuit has an output of 3.5V DC for an input of 200mV and a 50-ω power source at 920MHz.. |
| 17. |
Seunq Kvum Kim, Chang Hoon Shim, Tomohiko Edura, Kohei Tsugita, Satoshi Yukiwaki, Chihaya Adachi, Reiji Hattori, Elevated-electrode structure in organic thin-film transistors, 20th International Display Workshops 2013, IDW 2013, 2013.01, A new structure of organic thin-film transistor named the "Elevated-Electrode Structure" shows mobility, on/off ratio as high as those of the structure with bottom-gate and top-contact and higher than those of structure with bottom-gate and bottom-contact in actual devices fabricated using DNTT.. |
| 18. |
Reiji Hattori, Kohei Miyamoto, Haruichi Kanaya, Shoichiro Tsukamoto, Hiroshi Ishinishi, Wireless power transmission system for mobile devices, 20th International Display Workshops 2013, IDW 2013, 2013.01, We present three types of Wireless power transmission systems for mobile devices using inductive and capacitive coupling and a radio wave. Capacitive coupling provides a wider reception area than inductive coupling. A radio wave receiving type system has a longer transmission distance than the others; however, it has lower efficiency. We demonstrate these systems by embedding them into an electronic paper device.. |
| 19. |
Tatsuya Takahashi, Reiji Hattori, Akihiko Watanabe, Hiroshi Ishinishi, Batteryless electronic paper using wireless power transfer with resonant capacitive coupling, 19th International Display Workshops in Conjunction with Asia Display 2012, IDW/AD 2012, 2012.12, The capacitively-coupled wireless power transfer system embedded in the e-Paper device was demonstrated. This system realizes a batteryless e-Paper with a wide power-supply position. 13.56 MHz power transfer frequency was employed and the frequency was modulated to keep the resonant conditions.. |
| 20. |
Kyuwon Kyoung, Reiji Hattori, Improvement of detection linearity on the capacitive touch panel using transient electrical response, 19th International Display Workshops in Conjunction with Asia Display 2012, IDW/AD 2012, 2012.12, A new capacitive sensing method using the difference of transient response by touch positions was proposed. In this method, the linearity of touch detection on an electrode was improved by using two reference voltages in relaxation oscillator circuits. We verified the touch panel operation with the improved circuits by not only SPICE simulation but also an evaluation circuit board. The suggested method is able to provide a tremendous cost advantage because of a single layer structure and simple wiring.. |
| 21. |
Chang Hoon Shim, Shuzo Hirata, Juro Oshima, Tomohiko Edura, Reiji Hattori, Chihaya Adachi, Self-refreshable lighting device using liquid oled material, 49th SID International Symposium, Seminar and Exhibition, dubbed Display Week, 2012, 2012.01, We made a self-refreshable lighting device using liquid OLED which can emit light in the liquid state. This device has a mesh-structure cathode made by means of MEMS processes and a liquid reservoir in the backside of the cathode. Although luminance decreased as the light emitting, the degraded emitting material was refreshed by natural replacement from the reservoir in the backside.. |
| 22. |
Kyuwon Kyoung, Katsunori Yuge, Reiji Hattori, Single layered and one-side wired capacitive touch panel using transient electrical response, 18th International Display Workshops 2011, IDW 2011, 2011.12, We proposed in this paper the capacitive sensing method based on measuring transient response. Proposed capacitive sensing method with single layered one-dimensional electrode arrays can achieve multi-touch function and narrow bezel by one-side wiring. The capacitive sensing method was verified by SPICE simulations and evaluation kits.. |
| 23. |
Masayuki Nishii, Yoshinori Iwabuchi, Hidefumi Kotsubo, Ryo Sakurai, Yoshitomo Masuda, Reiji Hattori, Development of flexible electronic paper with transparent polymer electrodes prepared through directly printing approach, 17th International Display Workshops, IDW'10, 2010.12, A 4.0 in. diagonal and 88 dpi flexible electronic paper with line-shaped electrodes composed of transparent conductive polymer of poly(3,4-ethylene dioxythiophene) and poly(styrenesulfonate) (PEDOT/PSS) was prepared and passive matrix images were successfully displayed. The line-shaped electrodes of the conductive polymer were directly formed onto the flexible polyethylene terephthalate (PET) substrate by using screen printing method. Increase of the viscosity of PEDOT/PSS aqueous suspension and improvement of a screen mask enabled to pattern the line-shaped electrodes in higher resolution.. |
| 24. |
Reiji Hattori, Ryo Sakurai, Norio Nihei, Yoshitomo Masuda, Thin and light weight flexible electronic paper display using QR-LPD™ technology, 10th International Meeting on Information Display and International Display Manufacturing Conference and Asia Display 2010, IMID/IDMC/ASIA Display 2010, 2010.12, We have developed thin and light weight flexible electronic paper display using QR-LPD technology. Novel types of thin and light weight flexible electronic paper display are discussed. This technology can realize the "real paper like" flexible electronic paper in combination with a plastic substrate QR-LPD fabricated by roll-to-roll process.. |
| 25. |
Reiji Hattori, Sang Gun Lee, Theoretical equations for current-voltage characteristics in OLED, Organic Light Emitting Materials and Devices XIII, 2009.12, Theoretical equations for current-voltage characteristics in mono-layer unipolar devices and multilayer bipolar device (that is, OLED) are investigated on the basis of the model consisting of diffusion theory of internal carrier emission through Schottky barrier at cathode and anode electrodes and electronic field dependence of carrier mobility, so called Pool-Frenkel mobility. Space charge effects are also included in this model, which is not presented as a simple Mott-Gurney law. The current-voltage characteristics of OLED are presented using a behavioral language for analog systems (Verilog-A), and the accuracy of this model was verified by comparing with the device simulation results.. |
| 26. |
Masayuki Nishii, Ryo Sakurai, Kaoru Sugie, Yoshitomo Masuda, Reiji Hattori, The use of transparent conductive polymer for electrode materials in flexible electronic paper, 2009 Vehicles and Photons Symposium, 2009.01, Transparent conductive polymer of PEDOT/PSS has been applied to top electrodes of flexible electronic-paper display. High resolution electrode patterning of the polymer materials in a line shape has been performed by laser ablation method. An 8.4-in. diagonal and 82 dpi flexible electronic paper using quick response liquid-powder technology has been prepared by applying the patterned flexible substrates. The flexible electronic paper with PEDOT/PSS electrodes has exhibited comparable display properties to that consisting of ITO electrodes.. |
| 27. |
Reiji Hattori, Chang Hoon Shim, Full HD AMOLED current-programmed driving with negative capacitance circuit technology, 8th International Meeting on Information Display - International Display Manufacturing Conference 2008 and Asia Display 2008, IMID/IDMC/ASIA DISPLAY 2008, 2008.12, The circuit simulation has been done on the current-programmed AMOLED and shows that the circuit which behaves as a negative capacitance can reduce the effect of parasitic capacitance fixed on the data-line and can accelerate the current programming speed as high as that required in Full HD AMOLED.. |
| 28. |
Sang Gun Lee, Reiji Hattori, OLED analog behavioral modeling based on physics, 8th International Meeting on Information Display - International Display Manufacturing Conference 2008 and Asia Display 2008, IMID/IDMC/ASIA DISPLAY 2008, 2008.12, The physical OLED analog behavioral model for SPICE simulation has been described using Verilog-A language. The model is based on the carrier-balance between the hole and electron injected through Schottky barrier at anode and cathode. The accuracy of this model was examined by com-paring with the results from device simulation.. |
| 29. |
Chang Hoon Shim, Reiji Hattori, Late-news paper Fast current-programming method to OLED, 2008 SID International Symposium, 2008.01, The concept of 'negative capacitance', which consists of a differentiation circuit, an inverting voltage amplifier and a voltage-to-current converter, was introduced to the driving of PMOLED to shorten the current setting time even at a small current level. This new driving circuit enabled to show an accurate gray scale with both PWM and PAM methods, and is also applicable to a current-programmed AMOLED.. |
| 30. |
Akihiro Ikeda, Yashuhiro Kimiya, Yoshiaki Fukunaga, Hiroshi Ogi, Reiji Hattori, Hisao Kuriyaki, Yashuhide Ohno, Yukinori Kuroki, Effects of electroless Ni/Sn bump formation using hydrogen-plasma reflow on the electrical characteristics of MOSFETs, 9th Electronics Packaging Technology Conference, EPTC 2007, 2007.12, Fine size Ni/Sn bumps were formed by electroless Ni/Sn plating and hydrogen plasma reflow, and then electrical characteristics of nMOSFETs and pMOSFETs were evaluated on the bumped chips. After the hydrogen plasma reflow, threshold voltages and carrier mobilities were not changed from those of the nMOSFETs and pMOSFETs as fabricated, before Ni/Sn plating. Also, gate leak currents were not increased by the plasma reflow for both the nMOSFETs and pMOSFETs. Off leak currents of the nMOSFETs were slightly decreased after the plasma reflow. In contrast, off leak currents of the pMOSFETs were slightly increased up to several tens of pA after the plasma reflow. However, the changes of the off leak currents by the plasma reflow were very small for both the nMOSFETs and pMOSFETs. Electrical damages induced by the plasma reflow were negligible for both the nMOSFETs and pMOSFETs.. |
| 31. |
M. Asakawa, T. Nakashima, T. Saeki, R. Hattori, A. Yokoo, R. Sakurai, N. Nihei, Y. Masuda, Electrical characteristics of driver LSI with 35μm thickness for flexible display, 14th International Display Workshops, IDW '07, 2007.12, The electrical characteristics of the mechanically flexible driver LSI as thin as 35pm to mount directly on a flexible display were precisely analyzed. The high-voltage transistors on this LSI show the current decrease less than 13% in high voltage region, which can be associated with a self-heating effect comparing with that of an ordinary thickness LSI. As the result of analysis under the convex and concave bending conditions, the drain current change by piezoresistive effect was observed.. |
| 32. |
M. Asakawa, T. Nakashima, T. Saeki, R. Hattori, A. Yokoo, R. Sakurai, N. Nihei, Y. Masuda, Electrical characteristics of driver LSI with 35μm thickness for flexible display, 14th International Display Workshops, IDW '07, 2007.12, The electrical characteristics of the mechanically flexible driver LSI as thin as 35μm to mount directly on a flexible display were precisely analyzed. The high-voltage transistors on this LSI show the current decrease less than 13% in high voltage region, which can be associated with a self-heating effect comparing with that of an ordinary thickness LSI. As the result of analysis under the convex and concave bending conditions, the drain current change by piezoresistive effect was observed.. |
| 33. |
Reiji Hattori, Michihiro Asakawa, Yoshitomo Masuda, Norio Nihei, Akihiko Yokoo, Shuhei Yamada, Itsuo Tanuma, Passive-matrix flexible electronic paper using quick-response liquid powder display (QR-LPD) technology and custom driver circuits, 54th IEEE International Solid-State Circuits Conference, ISSCC 2007, 2007.09, A low-power high-voltage physically-flexible driver is fabricated for passive-matrix plastic-substrate quick-response liquid powder displays (QR-LPD). A level-shifter circuit effectively reduces the power consumption and the chip area. The 2.3×21.4mm2 IC is thinned down to 35μm to obtain physical flexibility.. |
| 34. |
Reiji Hattori, Organic thin-film transistor from solution-processed precursor film, Conference on Lasers and Electro-Optics/Pacific Rim, CLEOPR 2007, 2007.01, Small molecule, Tetrabenzoporphyrin (BP), organic thin-film-transistor (OTFT) were fabricated by annealing its spin-coated precursor film at 205oC. The OTFT has a bottom contacted structure with Polystyrene passivation layer. The transfer characteristics of the TFT provide a mobility of 0.11 cm2/(V•s) and an on/off ratio of more than 104.. |
| 35. |
Reiji Hattori, Chang Hoon Shim, Sang Gun Lee, Masayasu Tazoe, Takuro Nakashima, Shinji Aramaki, Akira Ohno, Yoshimasa Sakai, Full fabrication process for AM-OLED using solution-processed tetrabenzoporphyrin thin-film transistor, 13th International Display Workshops, IDW '06, 2006.12, Full fabrication process of An AM-OLED pixel with solution processed organic TFTs composed of metal-complex tetrabenzoporphyrin as an active layer and polystyrene as a passivation layer was presented. The TFTs were isolated using an RIE process and miniaturized for implementation into a pixel size of 100 μm × 300 μm.. |
| 36. |
Reiji Hattori, Satoshi Wakuda, Michihiro Asakawa, Yoshitomo Masuda, Norio Nihei, Akihiko Yokoo, Shuhei Yamada, Three-voltage-level driver driven Quick-Response Liquid Powder Display, 44th International Symposium, Seminar, and Exhibition, SID 2006, 2006.12, We developed a new custom-made high voltage driver with three voltage levels and with low power consumption for Quick-Response Liquid Powder Display (QR-LPD), which allows a variety of driving method. The difference between the driving methods was investigated in terms of image quality and power consumption.. |
| 37. |
Akihiro Ikeda, Yosuke Sugimoto, Tomonori Kuwada, Satoru Kajiwara, Tsuyoshi Fujimura, Kazuya Iwasaki, Hiroshi Ogi, Kiyoshi Hamaguchi, Hisao Kuriyaki, Reiji Hattori, Yukinori Kuroki, A study of the reliability of mosfets in two stacked thin chips for 3D system in package, 2005 IEEE International Reliability Physics Symposium Proceedings, 43rd Annual, 2005.12. |
| 38. |
Yoshitomo Masuda, Ryo Sakurai, Norio Nihel, Reiji Hattori, Invited paper Novel reflective display QR-LPD®, Second Americas Display Engineering and Applications Conference, ADEAC 2005, 2005.12, A novel reflective display; Quick-Response Liquid Powder Display (QR-LPD®), has been developed. This paper-like display has the advantages of outstanding image stability, easy viewing, low-power consumption and a high-response time. QR-LPD®will be promoted, initially, for use as electronic price tag displays for merchandise. In addition, QR-LPD® is suitable for flexible display applications since it does not require TFT arrays or a high temperature process while maintaining an excellent paper-like image as well as glass type display compatibility.. |
| 39. |
Yoshitomo Masuda, Ryo Sakurai, Norio Nihei, Reiji Hattori, Novel reflective display QR-LPD®, 25th Internatioanl Display Research Conference, EURODISPLAY 2005, 2005.12, A novel reflective display; Quick-Response Liquid Powder Display (QR-LPD®), has been developed. This paper-like display has the advantages of outstanding image stability, easy viewing, low-power consumption and a high-response time. QR-LPD® will be promoted, initially, for use as electronic price tag displays for merchandise. In addition, QR-LPD® is suitable for flexible display applications since it does not require TFT arrays or a high temperature process while maintaining an excellent paper-like image as well as glass type display compatibility.. |
| 40. |
Y. Masuda, R. Sakurai, N. Nihei, R. Hattori, Novel type of multi-stable reflective display using electric powder, IDW/AD'05 - 12th International Display Workshops in Conjunction with Asia Display 2005, 2005.12, We have developed a novel reflective and multi-stable display using electric powder. It has a paper-like appearance and good image stability. In addition, QR-LPD® is suited for flexible display applications since it does not require either a high temperature or complicated manufacturing process. QR-LPD® can maintain an excellent paper-like image and also offers glass type display compatibility. In this paper, an IC card display is proposed as one of the possible applications for flexible QR-LPD®, as a so-called electronic paper application.. |
| 41. |
Gordon Yip, Reiji Hattori, Shintarou Sugimoto, Single DAC current delivery system for driving AMOLED panel with increased pixel uniformity, SID Symposium Digest of Technical Papers, 2005.01, A Current sink data-driver with 54 outputs for AM-OLED, driven by a current-programmed method, has been demonstrated. This driver can sink constant current as low as I μA with 6-bit analog levels.. |
| 42. |
Akihiro Ikeda, Tomonori Kuwata, Satoru Kajiwara, Tsuyoshi Fujimura, Hisao Kuriyaki, Reiji Hattori, Hiroshi Ogi, Kiyoshi Hamaguchi, Yukinori Kuroki, Design and measurements of test element group wafer thinned to 10 μm for 3D system in package, Proceedings of the 2004 International Conference on Microelectronic Test Structures (ICMTS 2004), 2004.07, We designed and measured test element group wafers thinned to 10μm for 3D system in package. The n-well - p-Si diodes in 10 μm thick wafer showed increasing of the reverse saturation current in comparison to the currents in 20μm, 30 μm or 640 μm thick wafer. While the pMOSFETs and nMOSFETs in 10μm thick wafer showed no degradation of mobility, sub-threshold swing and threshold voltage. Defects might be induced by mechanical stress during wafer back grinding process near wafer back side, within a few micron-meters from the wafer back surface.. |
| 43. |
Rohana Perera, Akihiro Ikeda, Reiji Hattori, Yukinori Kuroki, Anomalous leakage current in silicon oxynitride thin films grown by microwave excited nitrogen plasma nitridation, Proceedings of the 7th International Conference on Properties and Applications of Dielectric Materials, 2003.10, Silicon oxynitride (SiON) has emerged as a better gate dielectric material to replace ultra-thin gate SiO2 in scaled down metal-oxide-semiconductor (MOS) devices. The present study investigates the leakage current in SiON grown by a plasma-based process. Thin films of SiON (6nm) were grown on Si substrates by nitriding rapid thermally grown SiO2 layers in a low-energy, microwave excited nitrogen plasma and by subsequent re-oxidation; and the resulting films were characterized in Al/SiON/p-Si MOS structures under atmospheric, vacuum and low temperature conditions. The analysis of the current-voltage (I-V) characteristics obtained under atmospheric conditions shows an enhanced leakage current in the pre-Fowler-Nordheim region of 4∼8MV/cm oxide field range. However, I-V characterization in vacuum showed the complete removal of this additional current component. This current was found to be not due to a charging/capacitive effect. It is speculated that this additional mid-oxide-field leakage current could possibly be due to a conducting pathway given rise to by interaction of atmospheric gases/water molecules with the plasma induced defects on the oxynitride film.. |
| 44. |
T. Fujimura, Akihiro Ikeda, S. Etoh, Reiji Hattori, Y. Kuroki, Suk Sang Chang, Fabrication of open-top microchannel plate using deep x-ray exposure mask made with SOI substrate, International Microprocesses and Nanotechnology Conference, MNC 2002, 2002.01, Human genome project has now been completed. At the next stage, the analysis of the DNA diversity originated from each individual is a very important aspect. It requires a method that can determine the base-pair sequence quickly and easily for fast and effective analysis. Separating the biochemical samples by electrophoresis is one of the analysis processes. Recently, electrophoresis has been performed in the fine channel formed on various substrates. By utilizing a microchannel chip for electrophoresis, the dead volume of the reagent and detection apparatus, and energy are reduced. To improve the separation performance of microchannel chip, the width of the channel should be narrower. On the other hand, the volume of the sample that can be introduced is restricted. Then, the channel is filled with ionic solution, and the top of the substrate is covered with a plate for shallow channel, so as not to cause current leakage induced by applying high voltage during electrophoresis. But, it requires a high quality substrate-cover adhesion. technique. We propose a high-aspect-ratio open-top microchannel plate. The high-aspect-ratio structure increases the sample and reagent volume inside the channel without increasing the channel width, which results in an enhancement of the detection sensitivity. And the buffer solution is introduced only before the measurement and sequential supply from an external source is not needed. The chip is standalone. The deep channel leads to another advantage. Its deep depth prevents overflow of the solution to the uncovered channel. By avoiding the difficult sealing process, the fabrication process become easy and high-throughput is realized.. |
| 45. |
S. Etoh, T. Fujimura, R. Hattori, Y. Kuroki, Observation of on-chip electrophoresis microcapillary using confocal laser scanning microscopy, International Microprocesses and Nanotechnology Conference, MNC 2002, 2002.01, In a capillary electrophoresis separation performance is affected by various factors, for example, an electroosmotic flow, dispersion of sample plug and sample adsorption to capillary wall. In order to miniaturize the microcapillary onto a chip we have to understand them in detail and investigate their influence. Confocal Laser Scanning Microscopy (CLSM) in fluorescence mode (FV300 Fluoview OLYMPUS JAPAN CO., LTD, Japan) was used to observe the motion of the samples in microcapillary fabricated on a chip. The CLSM is a powerful tool to understand their influence since it can capture the fluorescence images sliced in the plane perpendicular to the optical axis and can scan the plane position along the optical axis. Therefore it makes possible to observe the sample behavior inside the channel. This study also contributes the investigation of the microfluidic manipulation which includes a micropump, a microvalve and other microfluidic actuator devices under electrokinetic driven conditions.. |
| 46. |
J. Kanicki, J. H. Kim, J. Y. Nahm, Y. He, Reiji Hattori, Amorphous silicon thin-film transistors base active-matrix organic light-emitting displays, Asia Display/IDW 2001, 2001.12, In our laboratory we have simulated, designed, and fabricated hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) based pixel electrode circuits for active-matrix organic light-emitting displays (AM-OLEDs). These pixel circuits, having very small feed-through voltages, can supply a continuous output current at an adequate level for AM-OLEDs up to 500 dpi of resolution. Each pixel electrode has also compensation circuits that will allow to adjust the output current level for the OLED and a-Si:H TFTs threshold voltage variations. Therefore, we can control display brightness uniformity at an acceptable level.. |
| 47. |
J. Kanicki, Y. He, R. Hattori, A-Si:H pixel electrode circuits for AM-OLEDs, Flat Panel Display Tecnology and Display Metrology II, 2001.01, A new pixel electrode circuit based on hydrogenated amorphous silicon (a-Si:H) technology has been designed, fabricated and characterized for the active-matrix organic light-emitting displays. This circuit has four thin-film-transistors (TFTs) and only two external terminals. In addition, a current driver is used to provide the signals to the data line and automatically adjust the current level to compensate for the threshold voltage shifts of both the organic light-emitting devices and the drive TFT. Consequently, this pixel electrode circuit has an excellent electrical reliability even when a large threshold voltage shift is present. Experimental results indicate that an continuous pixel electrode excitation can be achieved with these circuits. Even after a long time circuit aging stress, this circuit only shows an output current level variation less than 1% at the high current level (≥0.5μA) and less than 5% at the low (≤0.1 μA) current levels. Two additional pixel electrode circuits have also been proposed. These new circuits can achieve a higher output current level and a better output-input current linearity without sacrificing the circuit's electrical reliability. All these circuits can potentially be used for the active-matrix organic light-emitting displays (AM-OLEDs).. |
| 48. |
Yi He, Reiji Hattori, Jerzy Kanicki, Electrical reliability of two- and four- a-Si H TFT pixel electrode circuits for active-matrix OLEDs, 20th International Display Research Conference, 2000.12, A two-thin film transistor (TFT) pixel electrode circuit, based on hydrogenated amorphous silicon (a-Si:H) TFT technology, for active-matrix organic light-emitting displays has been initially designed, fabricated, and characterized. Experimental results indicate that a continuous pixel electrode excitation can be achieved with this type of pixel circuit and the voltage applied on the data line can control the pixel circuit output current. However, this type of pixel circuit exhibits a poor electrical reliability due to the drive TFT threshold voltage (Vth) shift. The pixel circuit shows an output current variation of about 40 to 85% after 104 seconds bias temperature stress of the drive TFT at the room temperature. To overcome this Vth shift, a new four-TFT pixel circuit has been designed and fabricated. Experimental results indicate that a new pixel circuit has an excellent electrical reliability even when a large threshold voltage shift is present.. |
| 49. |
M. Abd Elnaby, A. Ikeda, Reiji Hattori, Y. Kuroki, Effect of nitrogen plasma conditions on the electrical properties of silicon oxynitrided thin films for flash memory applications, 12th International Conference on Microelectronics, ICM 2000, 2000.10, Si[100] substrates were oxynitrided with nitrogen plasma, at different exposure times, followed by thermal oxidation in dry O2 without using any harmful or global warming gas. Secondary ion mass spectroscopy (SIMS) measurements confirm that nitrogen is confined to the immediate vicinity of the surface. The damage induced in the thin SiO2-Si system after an exposure to nitrogen plasma at different exposure times ranged from 10 to 60 s was estimated from the analysis of C-V and I-V measurements. A generation of different densities of positive oxide charge has been observed. Correlation between the local bonding structures in the oxynitride films and the electrically active defective states at the Si-SiO2 interface are also discussed. It is proposed that improved electrical characteristics for positive charge trapping, interface state density, leakage current, and stress immunity of the oxynitride films could be obtained by using an optimal plasma exposure time of about 30 s. The preliminary results obtained indicate that these oxynitride films can be considered as potential candidates for ultra thin gate oxide and flash memory applications.. |
| 50. |
Tsuyoshi Fujimura, Shin Ichi Etoh, Satoshi Ishikawa, Akihiro Ikeda, Reiji Hattori, Yukinori Kuroki, High aspect-ratio microchip-based capillary electrophoresis device using chemically machinable photosensitive glass substrate, International Microprocesses and Nanotechnology Conference, MNC 2000, 2000.01, To analyze DNA fragments rapidly and easily will be a most important process in a future DNA industry. This paper reports a new fabrication process and a new device structure for microchip-based capillary electrophoresis (CE) using chemically machinable photosensitive glass substrate. The fabrication process of our device has an advantage in mass production as an inexpensive device. In addition we can easily obtain the high aspect-ratio structure of the channel, which presents high performance in separation characteristics.. |
| 51. |
Reiji Hattori, Yukinobu Tanida, Junji Shirafuji, New type TFT with unique operation and simple fabrication process, Proceedings of the 1994 MRS Spring Meeting, 1994.12, A thin film transistor (TFT) with a new structure and a unique operation principle has been proposed. This TFT has Schottky barrier contacts at source and drain, and employs electron tunneling through the Schottky barrier. The first feature of this TFT is simplification of the production process because a self-aligned technique is applicable and an ion-implantation process is not necessary. These advantages are promising for low-cost production of active-matrix liquid crystal displays (AM-LCDs). In this letter, we propose of new type TFT and carry out 2-D device simulation on a simplified structure to show the fundamental characteristics of this transistor and to optimize impurity density, channel thickness, and barrier height.. |
| 52. |
Reiji Hattori, Kyuwon Kyoung, Ryota Yoneda, Single-ITO-layer multi-touch sensor panel, 20th International Display Workshops 2013, IDW 2013, We present a multi-touch sensor technology with a single ITO layer, which is available even for large panels. This technology has a one-dimensional array of elements in a patterned ITO layer and it senses the touch position two-dimensionally through a combination of the surface and projected capacitive touch sensing principles.. |
| 53. |
Reiji Hattori, High-voltage driver LSI for passive matrix driven electronic paper with 160 tri-level voltage outputs, 2012 Japan-Egypt Conference on Electronics, Communications and Computers, JEC-ECC 2012, We have succeeded in developing a custom LSI with 160-outputs which supply tri-level voltages as high as 110 V using LDMOS technology for driving a passive-matrix driven electronic paper. The level shifter was designed to suppress the power consumption by employing the new level shifter which needed no DC bias voltage. The LSI chip was thinned to 35 m for direct-mounting onto a flexible display.. |
| 54. |
Masayuki Nishii, Ryo Sakurai, Shingo Ohno, Yoshitomo Masuda, Reiji Hattori, Full color and flexible electronic paper display, 18th International Display Workshops 2011, IDW 2011, A full color and flexible electronic paper of quick response liquid powder display (QR-LPD™) technologies have been achieved. The overview and recent results about the development of electronic paper of QR-LPD will be described. In particular, colorization of the monochromic panels and the development of flexible displays are focused. The originally developed panel materials and roll-to-roll manufacturing processes have enabled us to fabricate the full color and flexible displays.. |
| 55. |
Akihiko Yokoo, Tadashi Kubota, Yasunobu Saida, Ryo Sakurai, Shingo Ohno, Yoshitomo Masuda, Reiji Hattori, Wireless smart card with electronic paper dot matrix display using QR-LPD technology, 49th Annual SID Symposium, Seminar, and Exhibition 2011, Display Week 2011, We have developed a thin and flexible smart card with EPD (Electronic Paper Display) using QR-LPD™ (Quick-Response Liquid Powder Display) technology. The extremely low energy consumption display applications can be realized by utilizing the image holding property with no energy consumption. In this study, we combined flexible EPD with wireless energy and data transfer system in order to realize extremely thin, light weight and flexible smart card that has dot matrix EPD. The possibility of wireless smart card with flexible EPD using QR-LPD technology is discussed.. |
| 56. |
Masayuki Nishii, Yoshinori Iwabuchi, Hidefumi Kotsubo, Ryo Sakurai, Yoshitomo Masuda, Reiji Hattori, 54.2 Direct printed electrodes of transparent conductive polymers for flexible electronic papers, 48th Annual SID Symposium, Seminar, and Exhibition 2010, Display Week 2010, Direct formation of line-shaped electrodes consisting of transparent conductive polymer of poly(3,4-ethylene dioxythiophene) and poly(styrenesulfonale) (PEDOT/PSS) was successfully achieved onto a flexible polyethylene terephthalate (PET) substrate by using screen printing method. Improvement of the components and the viscosity of the conductive materials enabled to pattern the line electrodes in high resolution. A 4.0 in. diagonal and 88 dpi flexible electronic paper display using quick response liquid-powder technology has been prepared by applying the flexible substrate with the direct printed transparent polymer electrodes.. |
| 57. |
S. Kaneko, M. Asakawa, Reiji Hattori, Y. Masuda, N. Nihei, Akihiro Yokoo, Shuhei Yamada, Additional speeding-up method of updating time for bistable passive-matrix driven display by shrinking multiline addressing data, 16th International Display Workshops, IDW '09, We discussed the speeding-up method in the updating time of Quick Response-Liquid Powder Display (QR-LPD™). We generated the shrunk multiline addressing "lossless" data using the linearly dependence of an image data matrix. The generated data can reduce the update time by quarter compared with that of a conventional driving method.. |
| 58. |
Masayuki Nishii, Ryo Sakurai, Kaoru Sugie, Yoshitomo Masuda, Reiji Hattori, Development of electrode materials for flexible electronic paper Application of conductive organic polymers by higher resolution patterning, 16th International Display Workshops, IDW '09, Transparent conductive polymer of PEDOT/PSS has been used to the top electrodes of a flexible electronic paper. High resolution pattering of PEDOT/PSS has been performed by a laser ablation method in the resolution of 88 dpi. The electronic paper with the patterned PEDOT/PSS has exhibited comparable display properties to those of ITO panels.. |
| 59. |
S. Kaneko, M. Asakawa, Reiji Hattori, Y. Masuda, N. Nihei, A. Yokoo, S. Yamada, Multiline driving of Quick-Response Liquid Powder Display (QR-LPD) with non-negative matrix factorization, 15th International Display Workshops, IDW '08, The availability and possibility of multiline addressing (MLA) for Quick Response Liquid Powder Display (QR-LPD™) using Non-negative Matrix Factorization (NMF) were discussed. The NMF adopted to generate the multiline data was processed by MATLAB®. The multiline data were sent to QR-LPD ™ panel and displayed the image on the panel successfully.. |
| 60. |
Chang Hoon Shim, Reiji Hattori, Acceleration of current programming speed for AMOLED using active negative-capacitance circuit, 14th International Display Workshops, IDW '07, Settling time of current programming for AMOLED was shortened to the range of micro-second even in 10 nA of the programming current level by differentiator feedback using an active negative-capacitance circuit. The circuit can be easily implemented in a conventional CMOS current driver since neither a huge capacitance nor an additional panel circuit is required.. |
| 61. |
Reiji Hattori, Organic thin-film transistor from solution-processed precursor film, 2007 Conference on Lasers and Electro-Optics - Pacific Rim, CLEO/PACIFIC RIM, Small molecule, Tetrabenzoporphyrin (BP), organic thin-film-transistor (OTFT) were fabricated by annealing its spin-coated precursor film at 205°C. The OTFT has a bottom contacted structure with Polystyrene passivation layer. The transfer characteristics of the TFT provide a mobility of 0.11 cm 2/(V·s) and an on/off ratio of more than 104.. |
| 62. |
Tsuyoshi Fujimura, Akihiro Ikeda, Shin Ichi Etoh, Reiji Hattori, Yukinori Kuroki, Masanori Hidaka, Suk Sang Chang, Fabrication of absorber-embedded in membrane type deep X-ray exposure mask with wide exposure area made with Si substrate, International Microprocesses and Nanotechnology Conference, MNC 2003, In this paper we study about the fabrication of absorber-embedded in membrane type deep X-ray exposure mask with wide exposure area made with Si substrate.. |
