• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.249-252
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• 2003

This paper propose an advanced circuit for fingerprint sensor signal processing. We increased the voltage between ridge and valley by modifying the parasitic capacitance eliminating circuit of sensor plate. The analog to comparator was designed for comparing the sensor signal voltage with the reference signal voltage. We also propose an exective isolation strategy for removing noise and signal coupling of each sensor pixel. The 128$\times$144 pixel fingerprint sensor circuit was designed and simulated, and the layout was performed.

• Proceedings of the IEEK Conference
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• summer
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• pp.82-85
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• 2004

This paper proposes an advanced circuit for the capacitive type fingerprint sensor signal processing and an effective isolation structure for minimizing an electrostatic discharge(ESD) influence and for removing a signal coupling noise of each sensor pixel. The proposed detection circuit increases the voltage difference between a ridge and valley about $80\%$ more than old circuit. The test chip is composed of $160\;\times\;192$ array sensing cells $(9,913\times11,666\;um^2).$ The sensor plate area is $58\;\times\;58\;um^2$ and the pitch is 60um. The image resolution is 423 dpi. The chip was fabricated on a 0.35um standard CMOS process. It successfully captured a high-quality fingerprint image and performed the registration and identification processing. The sensing and authentication time is 1 sec(.) with the average power consumption of 10 mW at 3.0V. The reveal ESD tolerance is obtained at the value of 4.5 kV.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.910-912
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• 2015

In this paper, we designed the novel capacitive sensor and system for measuring the position of the piston in hydraulic cylinder. The magnetic or LVDT sensors have been widely used to measure the position of the piston because of its high accuracy, but these types of sensor are very expensive and have difficulty in use because of its complexity. To overcome these disadvantages, we studied the optimized non-contact capacitive sensor and designed detecting system for accurate measuring the location of piston in hydraulic cylinder. The proposed capacitive sensor and detecting system have the possibility of practical use for hydraulic cylinder through experiments.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.107-114
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• 2012

We have developed a textile capacitive pressure sensor for smart gait analysis. The proposed system can convert sensor signal into step counts and pressure levels by different posture. To evaluate the performance of insole type textile capacitive sensor, we measured capacitance change by increment of weights from 10 kg to 100 kg with 10 kg increment using M1 class rectangular weights (four 20 kg weights and two 10 kg weights) which have ${\pm}10%$ tolerance. The result showed non-linearity characteristic of a general capacitive pressure sensor. The test was performed according to a test protocol for four different postures (sitting, standing, standing on a left leg and standing on a right leg) and different walking speeds (1 km/h and 4 km/h). Five healthy male subjects were participated in each test. As we expected, the pressure level was changed by pressure distribution according to posture. Also, developed textile pressure sensor showed higher recognition rate (average 98.06 %) than commercial pedometer at all walking speed. Therefore, the proposed step counts and posture monitoring system using conductive textile capacitive pressure sensor proved to be a reliable and useful tool for monitoring gait parameters.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.110-117
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• 1997

This paper discusses numerically and experimenally several design parameters for the plate- type capacitive displacement sensor. The influenences of shape of this sensor on the sensitivity are numerically analyzed with the charge density method. Using many test sensor plates of different shape for verifing the validity of this method can not guarantee the repetibility of experiments. Therefore we made specially the test sensor plate so that experiments of effects of shape of this sensor on sensitivity can be done with only that plate. Results from these experiments agree well with those from numerical analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1297-1303
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• 2003

This paper propose an advanced circuit for fingerprint sensor signal processing. We increased the voltage between ridge and valley by modifying the parasitic capacitance eliminating circuit of sensor plate. The analog comparator was designed for comparing the sensor signal voltage with the reference signal voltage. We also propose an effective isolation strategy for removing noise and signal coupling, ESD of each sensor pixel. The 128${\times}$l44 pixel fingerprint sensor circuit was designed and simulated, and the layout was performed.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.33-38
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• 2002

To establish the national standard of capacitance, four main electrodes of the cross capacitor which were evaluated to linearity and roundness less the $\pm 1 \mu m$ respectively have to be adjusted symmetrically in an inner cylinder. Four LM shafts with diameter of 5 mm were installed between main electrodes of the cross capacitor, and the electrodes were adjusted, as the first step, by means of the measured capacitance. In the second step, the symmetrical adjustment up to $\pm 1.2\mu m$ was performed by using a ball sensor, ball-type movable sensor, non-contacting capacitive sensor and upper guard sensor which were developed in this project.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.208-213
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• 2015

The purpose of this study is to optimize the design of a capacitive pressure sensor element using the simulation of electrical characteristics. The simulation of the ceramic sensor diaphragm ($Al_2O_3$) was performed by permitting pressure to change the curvature of the diaphragm. The pressure capacitance ($C_P$) was increased from 19.63 pF to 15.26 pF by applying pressure because the distance between the electrodes has been changed from $30{\mu}m$ to $15{\mu}m$. When the thickness of the diaphragm was changed to 0.46~0.52 mm, a larger capacitance change showed in accordance with the reduced thickness, which means an increase of sensitivity. However, considering the viewpoint of the signal linearity, it was selected for the optimum thickness of the diaphragm to 0.50 mm. The designed sensor element based on simulated results was tested to measure the output characteristics. Comparing of simulated and measured results, there was a margin of error of approximately 2%.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.230-236
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• 2001

We developed a built-in sensor bearing to measure the rotor motion of a rolling piston type compressor for the air conditioner. Because of needs for the high efficiency and long life span of compressor, and the usage of alternative refrigerants, the operating condition of the compressor becomes more severe. The accurate measurement of the rotor motion of the compressor can contribute greatly to the design and analysis of the hydrodynamic bearing. However, it is difficult to measure accurately the shaft behavior of small compressor because of the small space for the sensor mount, high temperature and pressure of compressor, oil mixed with refrigerant, and electromagnetic noise of the motor. To overcome these difficulties, we develop the cylindrical capacitive sensor that is built in the hydrodynamic bearing and calibrate the built-in sensor bearing indirectly through measuring the oil relative permittivity. We measured the rotor motion as well as suction and discharge pressures in various conditions. The several experimental results show that the developed built-in sensor bearing can measure the rotor motion not only in steady state but also in transient state.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.964-967
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• 2009

A new hybrid-type touch screen panel (TSP) has been developed based on a-Si:H TFT which can detect the change of both $C_{LC}$ and photo-current. This TSP can detect the difference of $C_{LC}$ between touch and no-touch states in unfavorable conditions such as dark ambient light and shadows. The hybrid TSP sensor consists of a detection area which includes one TFT for photo sensing and two TFTs for amplification. Compared to a single internal capacitive TSP or an optical sensing TSP, this new proposed hybrid-type TSP enables larger sensing margin due to embedding of both optical and capacitive sensors.