• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2005.11a
• /
• pp.245-248
• /
• 2005

This paper presents a novel user interface system which aims at easy controlling of mobile devices. The fundamental concept of the proposed interface is to launch an appropriate function of the device by sensing and recognizing the grip-pattern when the user tries to use the mobile device. To this end, we develop a prototype system which employs capacitive touch sensors covering the housing of the system and a recognition algorithm for offering the appropriate function which suitable for the sensed grip-pattern. The effectiveness and feasibility of the proposed method is evaluated through the test of recognition rate with the collected grip-pattern database.

• Journal of Sensor Science and Technology
• /
• v.26 no.2
• /
• pp.101-106
• /
• 2017

A novel intravenous (IV) infusion monitoring sensor is presented to measure the drop rate in the drip chamber of an IV infusion set. It is based on a capacitive proximity sensor and detects the variation of the longitudinal electric field induced by the drop falling into the drip chamber. Unlike the conventional capacitor sensor with two semi-cylindrical conductor plates, the proximity sensor for IV monitoring is composed of a pair of conductor rings which are mounted on the outer surface of the drip chamber with a specific gap between them. The characteristics of the proximity sensor for IV monitoring were investigated through three dimensional electrostatic simulations. It showed quite superior performances in comparison with the conventional capacitor sensor. Especially, the proposed proximity sensor exhibits consistent sensitivity regardless of its mounting position on the drip chamber, operates normally though the drip chamber is tilted and shows robustness to the changes of the drop size and the drip factor of the IV infusion set. Thus, the proximity sensor for IV monitoring is more suitable for use in actual environment of IV therapy compared with the conventional capacitor sensor.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.2
• /
• pp.17-23
• /
• 2002

A cylindrical capacitance-type spindle displacement sensor was developed and its effectiveness as a system to monitor cutting forces during hard turning was tested in this research. The sensor was installed between the face of spindle cover and the chucking element and measured pure radial motion of the spindle under the condition with presence of roundness error at measured surface. To prove the effectiveness of the developed system hard aiming tests using ceramic inserts and tool steel as workpiece were conducted. The workpiece was hardened up to 65 Rc. The variations of pure radial motion of the spindle ware measured during the cutting tests. The signals from the sensor showed the same pattern of cutting force variations from the tool dynamometer due to the progress of tool wear. As the flank wear of the ceramic tool increased both static component of cutting forces and the amount of center shift of spindle orbit increased, Results from the research showed that the developed sensor could be utilized as an effective and cheap on-line sensing device to monitor cutting conditions and tool performance in the un-manned machining center.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.3 s.357
• /
• pp.65-71
• /
• 2007

We propose a pixel-level automatic calibration circuit scheme that initializes a capacitive fingerprint sensor LSI to eliminate the influence of the surface condition and environment, which is degraded by dirt during long-time use, process variation and ambient temperature. The sample chip is fabricated on $0.35{\mu}m$ standard CMOS process. The calibration is executed by optimizing the reference voltage in each pixel to make the sensor signals of all pixels the same. The calibration control circuit is composed of the sensing circuit and charge pumping circuit, and calibrates all pixels in a short time. 16-level gray scale fingerprint images can be captured to increase the accuracy of identification. This confirms that the scheme is effective for capturing consistent clear images during long-time use.

• Journal of Power Electronics
• /
• v.17 no.1
• /
• pp.305-313
• /
• 2017

A novel interference isolation method is proposed by using several designed coils in capacitive power transfer systems as isolation impedances. For each designed coil, its stray parameters such as the inter-turn capacitance, coil resistance and capacitance between the coil and the core, etc. are taken into account. An equivalent circuit model of the designed coil is established. According to this equivalent circuit, the impedance characteristic of the coil is calculated. In addition, the maximum impedance point and the corresponding excitation frequency of the coil are obtained. Based on this analysis, six designed coils are adopted to isolate the interference from power delivery. The proposed method is verified through experiments with a power carrier frequency of 1MHz and a data carrier frequency of 8.7MHz. The power and data are transferred parrallelly with a data carrier attenuation lower than -5dB and a power attenuation on the sensing resistor higher than -45dB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.875-877
• /
• 2011

This paper introduces a touch screen panel driver using modified charge pump circuit. The touch screen panel driver is composed of an analog circuit part which senses a touch and a digital circuit which analyse the sensed signal. To verify the functions the touch screen panel driver, a mixed-mode circuit was built and simulated using Cadence Spectre. The digital circuits were modeled with Verilog-A in order to interface with the analog circuits and verify the functionalities of the driver with less simulation time. From the simulation results, we can verify the reliable operations of the simple structured touch screen panel driver which does not include an ADC.

• Nuclear Engineering and Technology
• /
• v.54 no.8
• /
• pp.2871-2876
• /
• 2022

The sensitivity of polymer-based capacitive relative humidity (RH) sensors after irradiation with neutrons, electrons and protons was measured. Degradation consists of the decreasing of the upper RH limit that can be measured. At the same time, low RH-level sensitivity is almost stable. After 30 krad of absorption dose, RH cut off is equal to 85% of max value, after 60 krad-40%. Degradation reduces after annealing which indicates high radiation sensitivity of the internal circuit in comparison to RH-sensing polymer film.

• Journal of Sensor Science and Technology
• /
• v.27 no.2
• /
• pp.93-98
• /
• 2018

In this paper, an energy-efficient 11.49-bit successive approximation register (SAR) capacitance-to-digital converter (CDC) for capacitive sensors with a figure of merit (FoM) of 31.6 pJ/conversion-step is presented. The CDC employs a SAR algorithm to obtain low power consumption and a simplified structure. The proposed circuit uses a capacitive sensing amplifier (CSA) and a dynamic latch comparator to achieve parasitic capacitance-insensitive operation. The CSA adopts a correlated double sampling (CDS) technique to reduce flicker (1/f) noise to achieve low-noise characteristics. The SAR algorithm is implemented in dual operating mode, using an 8-bit coarse programmable capacitor array in the capacitance-domain and an 8-bit R-2R digital-to-analog converter (DAC) in the charge-domain. The proposed CDC achieves a wide input capacitance range of 29.4 pF and a high resolution of 0.449 fF. The CDC is fabricated in a $0.18-{\mu}m$ 1P6M complementary metal-oxide-semiconductor (CMOS) process with an active area of 0.55 mm2. The total power consumption of the CDC is $86.4{\mu}W$ with a 1.8-V supply. The SAR CDC achieves a measured 11.49-bit resolution within a conversion time of 1.025 ms and an energy-efficiency FoM of 31.6 pJ/step.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.1
• /
• pp.83-91
• /
• 2014

This paper presents a capacitive readout circuit for tri-axes microaccelerometer with sub-fF offset calibration capability. A charge sensitive amplifier (CSA) with correlated double sampling (CDS) and digital to equivalent capacitance converter (DECC) is proposed. The DECC is implemented using 10-bit DAC, charge transfer switches, and a charge-storing capacitor. The DECC circuit can realize the equivalent capacitance of sub-fF range with a smaller area and higher accuracy than previous offset cancelling circuit using series-connected capacitor arrays. The readout circuit and MEMS sensing element are integrated in a single package. The supply voltage and the current consumption of analog blocks are 3.3 V and $230{\mu}A$, respectively. The sensitivities of tri-axes are measured to be 3.87 mg/LSB, 3.87 mg/LSB and 3.90 mg/LSB, respectively. The offset calibration which is controlled by 10-bit DECC has a resolution of 12.4 LSB per step with high linearity. The noise levels of tri-axes are $349{\mu}g$/${\sqrt}$Hz, $341{\mu}g$/${\sqrt}$Hz and $411{\mu}g$/${\sqrt}$Hz, respectively.

• Journal of Biosystems Engineering
• /
• v.41 no.4
• /
• pp.408-417
• /
• 2016

Purpose: Yield monitoring systems are an essential component of precision agriculture. They indicate the spatial variability of crop yield in fields, and have become an important factor in modern harvesters. The objective of this paper was to review research trends related to yield monitoring sensors for grain crops. Methods: The literature was reviewed for research on the major sensing components of grain yield monitoring systems. These major components included grain flow sensors, moisture content sensors, and cutting width sensors. Sensors were classified by sensing principle and type, and their performance was also reviewed. Results: The main targeted harvesting grain crops were rice, wheat, corn, barley, and grain sorghum. Grain flow sensors were classified into mass flow and volume flow methods. Mass flow sensors were mounted primarily at the clean grain elevator head or under the grain tank, and volume flow sensors were mounted at the head or in the middle of the elevator. Mass flow methods used weighing, force impact, and radiometric approaches, some of which resulted in measurement error levels lower than 5% ($R^2=0.99$). Volume flow methods included paddle wheel type and optical type, and in the best cases produced error levels lower than 3%. Grain moisture content sensing was in many cases achieved using capacitive modules. In some cases, errors were lower than 1%. Cutting width was measured by ultrasonic distance sensors mounted at both sides of the header dividers, and the errors were in some cases lower than 5%. Conclusions: The design and fabrication of an integrated yield monitoring system for a target crop would be affected by the selection of a sensing approach, as well as the layout and mounting of the sensors. For accurate estimation of yield, signal processing and correction measures should be also implemented.