On-Display Transparent Half-Diamond Pattern Capacitive Fingerprint Sensor Compatible With AMOLED Display

Ma, Hyunggun; Liu, Zhenyi; Heo, Su-Jeong; Lee, Jeeyoon; Na, Kyungmin; Jin, Han Byul; Jung, Sungchul; Park, Kibog; Kim, Jae Joon; Bien, Franklin

doi:10.1109/jsen.2016.2605125

Cited by 35 publications

(33 citation statements)

References 5 publications

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“…On the other hand, the AgNF–AgNW hybrid structure exhibited a negligible dependence of R s on the pattern widths, and it had a significantly low R s even for narrow patterns with widths <100 μm. This enabled the fine patterns of transparent electrodes required in fingerprint sensors that need to detect the period between the ridges and valleys of human fingers (~100 μm) 9 , 21 , 22 . Figure 2f shows the relative change in resistance of the AgNF–AgNW hybrid electrode that was formed on a c-PI film (thickness: 25 μm) as a function of the radius of curvature and the corresponding bending-induced strain ( ε ).…”

Section: Resultsmentioning

confidence: 99%

“…The capacitance is changed due to the distance of each ridge (closer) or valley (further) from the fingerprint sensor. Thus, a fingerprint image can be determined by the measurement of this voltage output signals over time at each capacitor of the sensor array 9 . Currently, capacitive fingerprint sensors that are used in mobile devices, especially in smartphones, are still opaque, and implemented either within an activation button or in areas on the back of these devices.…”

Section: Introductionmentioning

confidence: 99%

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Transparent and flexible fingerprint sensor array with multiplexed detection of tactile pressure and skin temperature

et al. 2018

Self Cite

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We developed a transparent and flexible, capacitive fingerprint sensor array with multiplexed, simultaneous detection of tactile pressure and finger skin temperature for mobile smart devices. In our approach, networks of hybrid nanostructures using ultra-long metal nanofibers and finer nanowires were formed as transparent, flexible electrodes of a multifunctional sensor array. These sensors exhibited excellent optoelectronic properties and outstanding reliability against mechanical bending. This fingerprint sensor array has a high resolution with good transparency. This sensor offers a capacitance variation ~17 times better than the variation for the same sensor pattern using conventional ITO electrodes. This sensor with the hybrid electrode also operates at high frequencies with negligible degradation in its performance against various noise signals from mobile devices. Furthermore, this fingerprint sensor array can be integrated with all transparent forms of tactile pressure sensors and skin temperature sensors, to enable the detection of a finger pressing on the display.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transparent and flexible fingerprint sensor array with multiplexed detection of tactile pressure and skin temperature

et al. 2018

Self Cite

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“…Qualcomm’s ultrasonic fingerprint sensor can also be placed at the bottom of the screen, with a penetration capability of 700–800 μm, but at a higher cost, it is currently only available on the latest flagship phones [5]. Capacitive fingerprint sensors obtain fingerprint images by measuring the difference in capacitance between the fingerprint ridges and valleys and the sensor [7,8,9,10,11,12]. At present, the most widely used fingerprint identification tool is a capacitive sensor because it is low in cost and small in size, and it is convenient to be deployed in the system.…”

Section: Introductionmentioning

confidence: 99%

A Novel Fingerprint Sensing Technology Based on Electrostatic Imaging

Tang

Liu

Wang

et al. 2018

Sensors

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In this paper, we propose a new fingerprint sensing technology based on electrostatic imaging, which can greatly improve fingerprint sensing distance. This can solve the problem of the existing capacitive fingerprint identification device being easy to damage due to limited detection distance and a protective coating that is too thin. The fingerprint recognition sensor can also be placed under a glass screen to meet the needs of the full screen design of the mobile phone. In this paper, the electric field distribution around the fingerprint is analyzed. The electrostatic imaging sensor design is carried out based on the electrostatic detection principle and MEMS (micro-electro-mechanical system) technology. The MEMS electrostatic imaging array, analog, and digital signal processing circuit structure are designed. Simulation and testing are carried out as well. According to the simulation and prototype test device test results, it is confirmed that our proposed electrostatic imaging-based fingerprint sensing technology can increase fingerprint recognition distance by 46% compared to the existing capacitive fingerprint sensing technology. A distance of more than 439 μm is reached.

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“…However, the most convenient and intuitive location of the fingerprint sensor is on the front face. Various types of sensors that can recognize fingerprints on display screens have been developed [1][2][3][4][5][6][7][8][9][10][11] . Typical examples include capacitive, optical, and ultrasonic fingerprint sensors.…”

Section: Introductionmentioning

confidence: 99%

On-screen fingerprint sensor with optically and electrically tailored transparent electrode patterns for use on high-resolution mobile displays

et al. 2020

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In this study, a mutual capacitive-type on-screen fingerprint sensor, which can recognize fingerprints on a display screen to provide smartphones with full-screen displays with a minimal bezel area, is fabricated. On-screen fingerprint sensors are fabricated using an indium tin oxide transparent conductor with a sheet resistance of ~10 Ω/sq. and a transmittance of ~94% (~86% with the substrate effect) in the visible wavelength range, and assembled onto a display panel. Even at this high transmittance, the electrodes can degrade the display quality when they are placed on the display. The interference between periodic display pixel arrays and sensor patterns can lead to the Moiré phenomenon. It is necessary to find an appropriate sensor pattern that minimizes the Moiré pattern, while maintaining the signal sensitivity. To search for appropriate patterns, a numerical calculation is carried out over wide ranges of pitches and rotation angles. The range is narrowed for an experimental evaluation, which is used to finally determine the sensor design. As the selected sensor pitches are too small to detect capacitance variations, three unit patterns are electrically connected to obtain a unit block generating a larger signal. By applying the selected sensor pattern and circuit driving by block, fingerprint sensing on a display is demonstrated with a prototype built on a commercial smartphone.

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On-Display Transparent Half-Diamond Pattern Capacitive Fingerprint Sensor Compatible With AMOLED Display

Cited by 35 publications

References 5 publications

Transparent and flexible fingerprint sensor array with multiplexed detection of tactile pressure and skin temperature

Transparent and flexible fingerprint sensor array with multiplexed detection of tactile pressure and skin temperature

A Novel Fingerprint Sensing Technology Based on Electrostatic Imaging

On-screen fingerprint sensor with optically and electrically tailored transparent electrode patterns for use on high-resolution mobile displays

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