Numerical evaluation of moiré pattern in touch sensor module with electrode mesh structure in oblique view

Pournoury, Marzieh; Zamiri, Ali; Kim, T. Y.; Yurlov, Victor; Oh, Kyunghwan

doi:10.1117/12.2207826

Cited by 7 publications

(8 citation statements)

References 4 publications

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“…Therefore, the Moiré pattern should be made imperceptible through a proper combination of sensor geometrical parameters. A spectral analysis of overlapped display-sensor pattern pairs in the frequency domain can be carried out by Fourier transform to predict the Moiré pattern periods, directions, and strengths, i.e., perceptual contrast [16][17][18]25,26 . Therefore, in this study, grayscale N × N pixel images of various overlapped patterns were prepared, and the discrete Fourier transform (DFT) was applied to the image matrices to perform spectral analysis.…”

Section: Sensor Pattern Selection For Moiré Pattern Minimizationmentioning

confidence: 99%

“…The viewing distance was assumed to be~40 cm, as the mean eye-screen distance is~33-40 cm for mobile devices 27 . The radius of the visibility circle corresponds to the threshold spatial frequency, 60 cycles/degree, suggested by the human contrast sensitivity function (CSF) 17,18 . The CSF describes the threshold sensitivity of the visual system to sinusoidal luminance contrast, with a range of spatial frequencies.…”

Section: Sensor Pattern Selection For Moiré Pattern Minimizationmentioning

confidence: 99%

“…Specifically, the appearance of Moiré patterns can be very problematic. The Moiré pattern refers to a phenomenon in which a new pattern, which did not originally exist, becomes apparent when repeated patterns or structures, such as grids, meshes, and a pixel matrix, overlap [16][17][18] . In the case of the on-screen fingerprint sensor, a repetitive pattern of the display overlaps with another repetitive pattern of the sensor.…”

Section: Introductionmentioning

confidence: 99%

“…The Moiré pattern issue has been extensively studied for the substitution of indium tin oxide (ITO) with metal mesh electrodes in touch screen panels, as they also have sensor electrodes on the display panel [17][18][19] . In the touch sensor, the pitch of the electrodes is considerably larger than that in the fingerprint sensor (~4 mm vs.…”

Section: Introductionmentioning

confidence: 99%

“…50-100 μm) 20,21 , so it can only locate the finger as a whole. The pitch is considerably larger than the pitch of smartphone display pixel arrays (~40-120 μm); thus, it is less challenging to avoid or reduce the Moiré pattern by altering the pattern geometry without significantly affecting the sensing capability 17,19,22 . However, the pitches of the fingerprint sensor electrodes are in the same range as the smartphone display pixel pitch, and thus, the Moiré effect can be significant.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Sensor Pattern Selection For Moiré Pattern Minimizationmentioning

confidence: 99%

Section: Sensor Pattern Selection For Moiré Pattern Minimizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Simulation of moire pattern based on transmittance calculation of LCD metal mesh touch panel

Wang

2021

J Soc Info Display

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In this paper, a precise and effective computational method for moire patterns' simulation and prediction of liquid crystal display (LCD) metal mesh touch panel based on the transmittance calculation of LCD's sub‐pixel is proposed. Firstly, we analyze the actual physical model and build our simulation model. Secondly, we explain the form reason of moire phenomenon and establish the transmittance calculation formula. Finally, we demonstrate the accuracy and validation of our simulation approach by practical experiment. The experimental results show that the simulation matching rate is about 88.2%, and the simulated graphs are extremely similar to the actual moire pattern. We can evaluate the moire degree with our new method; this research is significant to touch panel's production.

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P‐142: Moire Analysis and Quantification in Oblique View

Jia

You

Wang

et al. 2020

Symp Digest of Tech Papers

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The aim of this work is to analyze and quantify moire issue of stacked structures in oblique view. In oblique view, the pixel values of the stacked layers can't be added directly. Thus, we made a simple one-dimensional model to calculate the coordinates of the down layer and used interpolation method to calculate the pixel values in olique view. Then we used CSF method to process the superposition graph and made quantification. Experiment results showed that our method is a simple and effective way to analyze moire in oblique view.

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Numerical evaluation of moiré pattern in touch sensor module with electrode mesh structure in oblique view

Cited by 7 publications

References 4 publications

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

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

Simulation of moire pattern based on transmittance calculation of LCD metal mesh touch panel

P‐142: Moire Analysis and Quantification in Oblique View

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