Pixel Layout Research Articles

Color Tunable Three Terminal (3-T) Vertically Stacked Tandem Organic Electroluminescent Devices.

Traditional full-color displays typically use a pixel layout with three side-by-side subpixels emitting red (R), green (G), and blue (B) colors. However, this configuration limits the resolution especially in augmented reality (AR) and virtual reality (VR) applications. To address the issue of low pixel density in display technology, this study demonstrated vertically stacked three-terminal (3-T) bottom-emitting tandem OLEDs (sOLED). These OLEDs offer color tunability, facilitated by individually controlled colour units. This study demonstrates two combinations: G+B and R+G. Incorporating three generations of OLED's materials phosphorescent (R), thermally activated delayed fluorescence (TADF) (G), and hyperfluorescent (B). The OLEDs achieve maximum current efficiencies of approximately 11 cd/A, 52.4 cd/A, and 40.7 cd/A for R, G, and B, respectively, in their respective tandem configurations. A wide range of colors can be achieved by blending G+B and R+G color spectrum by adjusting the voltage of independent color unit. The optimal mix results in a fine cyan color with CIE coordinates (0.273,0.5) in G+B sOLED and a warm white with CIE coordinates (0.416,0.518)in R+G sOLED. This work demonstrate a better performing 3-T sOLED utilizing three different generations OLED materials, offering an individual control within a single pixel providing enhanced pixel density for display technology.

P‐104: Corrugated Silicon Nitride Masks with Enhanced Mechanical Strength for Patterning RGB‐Stripe OLED Microdisplays

Corrugated silicon nitride masks (SiNMs) with improved mechanical strength are developed for patterning OLED microdisplays. The corrugations in the nitride membrane significantly increase the rigidity of the mask and reduce sagging, enabling 3000‐ppi slot apertures for patterning RGB‐stripe pixel layouts that are normally not achievable by fine metal masks.

Design and simulation of modified 3D-trench electrode sensors

Future experiments at high-luminosity hadron colliders will involve unprecedent levels of pile up, calling for ultrafast detectors in order to add time information to distinguish between particle tracks. The unique geometry of 3D sensors enables to achieve very good timing performance, with the additional benefit of high radiation hardness. Remarkable results in terms of temporal resolution have been reported for 3D sensors with columnar electrodes (∼30 ps) and even better with trenched electrodes (∼10 ps), because of a more uniform distribution of the electric field and weighting field. However, 3D-trench technology is more complex, and has still to be optimized in terms of both fabrication process and pixel layout. To this purpose, as an alternative to the existing design which features continuous (p+) ohmic trenches, we propose a new variant by introducing a gap (∼10 μm) in the p+ trenches and placed offset with respect to the readout (n+) trenches, so as to reduce the risk of lithographical defects that were observed in mm's long ohmic trenches, thus improving the fabrication yield.TCAD simulations confirmed that the impact of the gap on the uniformity of the electric and weighting field is minimum, and good charge collection efficiency performance is preserved up to large fluences. Further Monte Carlo time-resolved simulations are performed on both the standard and modified geometries showing comparable temporal resolutions.

Magneto-optical spatial light modulator driven by current-induced domain wall motion for holographic display applications.

We have developed a magneto-optical spatial light modulator (MO-SLM) with a 10 k × 5 k pixel layout and with a pixel pitch horizontally of 1 µm and vertically of 4 µm. An MO-SLM device pixel has a magnetic nanowire made of Gd-Fe magneto-optical material whose magnetization was reversed by current-induced magnetic domain wall motion. We successfully demonstrated the reconstruction of holographic images, showing large viewing zone angles as wide as 30 degrees and visualizing different depths of the objects. These characteristics are unique to holographic images, providing physiological depth cues which may play a vital role in three-dimensional (3D) perception.

P‐9: LTPO TFTs Based PWM Pixel Circuit for AM‐Micro‐LED Display with Falling‐time <10μs

A pulse‐width‐modulation (PWM) pixel circuit for Micro‐LED display based on low‐temperature poly‐silicon and oxide (LTPO) thin‐film transistor (TFT) is proposed. The PWM falling‐time is reduced to 10 μs, which is only 1/10 of conventional PWM pixel schematics, thanks to the high gain dynamic CMOS inverter for converting data voltage to PWM waveforms and an independent diode‐connected compensation structure for generating constant driving current. The maximum error of PWM conversion and driving current of Micro‐LED is less than 1%, despite VTH shift of oxide TFT ±2 V or VTH variation of LTPS TFT ±1 V. Furthermore, high display resolution above 270 PPI is obtained as the pixel layout reduced to 94 μm×94 μm due to the simplified pixel structure.

42.1: Invited Paper: Naked‐Eye 3D Display System Based on Microlens Array

3D display technology can bring users 3D stereoscopic and realistic visual experience. At present, many types of 3D display technologies have been developed in this field. Among them, naked eye 3D is a more advanced 3D display technology. Compared with traditional polarized 3D display technology, it allows people to directly observe the stereo vision effect without polarized glasses. The naked-eye 3D technology discussed in this paper is based on micro-lens array, which is an important branch in the field of naked-eye 3D display. In this paper, the real-time human eye tracking technology is used to capture the user's human eye coordinates, and the pixel layout on the display module is adjusted in real time according to the human eye coordinate position, so as to ensure that the images taken into the human eye within any visual angle range have a three- dimensional effect. BOE has accumulated many advanced technologies in the field of display and artificial intelligence, especially in the fields of high-resolution display, new display and human eye tracking. This paper focuses on the naked eye 3D display system independently developed by BOE.

Computational Super-Resolution Imaging With a Sparse Rotational Camera Array

A sparse camera array utilizes several identical cameras for multi-frame super-resolution. However, the influence of camera layout on super-resolution performance remains unclear. In conventional camera arrays, all cameras share a similar observation model, resulting in redundancy during information collection. This study presents a novel super-resolution framework that actively controls cameras in a sparse camera array to rotate to certain degrees. Through a detailed analysis of the forward imaging model, it is shown that the rotation of cameras uses the rotational asymmetry property of pixel layouts and shape. The proposed camera layout method provides more diverse and informative spatial sampling than a conventional camera array with only translations between cameras. A physics-enabled deep neural network was introduced for multi-frame super-resolution. With the explicitly defined gradients and affine models as guidance, it can effectively decode additional information collected by the rotational camera array and overcome the large-scale spatial feature alignment problem. The experimental results on synthetic and real prototype datasets validated the proposed theory and solution. We believe our study can inspire innovations for future task-specific camera array system design.

Balanced pixel interpolation algorithm when identifying the object’s contours on the borders of the image

The operation of algorithms for identifying object’s contours using two-dimensional convolution operation on the boundaries of raster images depends entirely on the location of the transformed pixel in the pixel matrix. The problem is related to the need for the convolution algorithm itself to use an additional set of pixels located outside the pixel matrix of the processed image [1, 2, 3]. In this paper, an algorithm for balanced interpolation of pixels at image boundaries in addition to algorithms based on statistical averages [4, 5] is proposed. Various sets of coefficients which are located at a certain pixel layout and participate in the interpolation algorithm is considered. A comparative analysis of the results of the balanced interpolation algorithm with the results using the arithmetic mean methods is carried out. Also, an example of using a new algorithm to solve the problem of the object’s contours identification on the borders of a raster halftone image is presented. The described algorithm is easy to understand, use and integrate with other algorithms and it does not require significant computing power.

Charge Collection Dynamics of the ARCADIA Passive Pixel Arrays: Laser Characterization and TCAD Modeling

Monolithic Active Pixel Sensors (MAPS) represent one of the most promising technologies for the next generation of radiation detectors. The ARCADIA project aims at the development of Fully Depleted (FD) MAPS employing a production process compatible with a 110 nm commercial CMOS technology. The first engineering run of the project included matrices of active pixels with embedded analog and digital frontend electronics and passive test structures such as passive pixel arrays, MOS capacitors and backside diodes. Although the produced samples were already characterized from the electrical point of view, a thorough study of the charge collection dynamics of the passive pixel arrays was still missing. In this paper we show the results of the dynamic characterization of a group of passive pixel arrays with different pixel pitches (50, 25 and 10 μm) and different pixel layouts. The tested samples have been illuminated from the backside with an infrared and a red laser with wavelengths equal to 1,060 nm and 660 nm, respectively. The pixel arrays have been mounted on a custom readout PCB connected to an external amplifier with 1 GHz bandwidth and the signals have been acquired through a fast digital oscilloscope. We employed both focused and unfocused laser spots to evaluate the change in the measured signal as a function of the laser spot position and the average response of the pixel arrays. An excellent agreement has been demonstrated by comparing the measured signals with the results of transient TCAD simulations and a time for 50% charge collection of 7.8, 4.2 and 2.6 ns has been predicted and experimentally validated in pixels with 50, 25 and 10 μm pitch, respectively.

59‐1: Invited Paper: Scaling Down of OLED Pixels Enabled by Photolithography

This paper discusses the advantages of OLEDs in pixel scaling and the novel device structures enabled by photolithography. We show the pixel layouts that can be realized by photolithographic patterning, i.e., delta and color strip pixel layout with high pixel density. Further integration of OPD next to an OLED pixel is discussed. Finally, we show the OLED performance after three times OLED patterning steps, which is crucial for the full‐color OLED display realized by photolithography patterning processes. The results suggest that the photolithography patterning process could be a powerful method to further enhance the AMOLED display performance.

65‐5: AI Based Simulation and Design Space Exploration for Pixel Layout

Typical properties of the display backplane and CF are image quality such as brightness, uniformity, crosstalk, response time, and gamut. A global optimal design that satisfies these properties must search all design spaces. This paper proposes a simulation and design space exploration through an AI‐based solution. Numerous layouts are generated through AI based layout generator, and the properties are checked through Fast Simulator, which has been accelerated by replacing physics simulation with AI. Humans can check 10 designs per week, and AI can check over 1000 designs per hour. AI overpowers humans in search range, optimal path, predictive power and speed. In all design spaces, optimal results are being applied to the new QD display product development process.

P‐85: Improvement of the Transmittance of ADS Mode in 8K Display

One of the main factors for popularization of 8K TV is the drastically deteriorated transmittance. We proposed several ways to improve the transmittance of ADS mode in 8K display, such as modifying the traditional pixel layout and adopting new materials. The transmittance gap between 4K and 8K has narrowed.

Designing Display Pixel Layouts for Under-Panel Cameras

Under-panel cameras provide an intriguing way to maximize the display area for a mobile device. An under-panel camera images a scene via the openings in the display panel; hence, a captured photograph is noisy as well as endowed with a large diffractive blur as the display acts as an aperture on the lens. Unfortunately, the pattern of openings commonly found in current LED displays are not conducive to high-quality deblurring. This paper redesigns the layout of openings in the display to engineer a blur kernel that is robustly invertible in the presence of noise. We first provide a basic analysis using Fourier optics that indicates that the nature of the blur is critically affected by the periodicity of the display openings as well as the shape of the opening at each individual display pixel. Armed with this insight, we provide a suite of modifications to the pixel layout that promote the invertibility of the blur kernels. We evaluate the proposed layouts with photomasks placed in front of a cellphone camera, thereby emulating an under-panel camera. A key takeaway is that optimizing the display layout does indeed produce significant improvements.

Staggered Pixel Layout to Reduce Area and Increase Full Well Capacity in CMOS Image Sensors

CMOS image sensor’s ability to collect light depends, amongst others, on its full well capacity (FWC) which is the capability of a pixel of storing electrons. The FWC can be improved either by expensive and time-consuming process modifications or by increasing the pixel photodiode area. Optimizing the pixel layout is crucial to increase the photodiode area at a given pixel pitch. In this article, we present a novel layout technique that reduces the area occupied by the in-pixel transistors by reorganizing the shared diffusions. Such optimization is demonstrated to increase the area of the photodiode for a given pixel pitch and, hence, the fill factor (FF). Both a mathematical model of the methodology and experimental results of pixels manufactured in a commercially available technology are presented. We prove that the technique is particularly effective for small pixel pitches and can lead to an increase in FF and FWC of at least 20% in a 4-transistor CMOS pixel with 2.4- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> pitch.

Wideband Double-Polarized Array of Cold-Electron Bolometers for OLIMPO Balloon Telescope

In this article, we propose a novel type of a wideband 2-D array of cold-electron bolometers (CEBs) sensitive to both polarizations of the incoming optical signal. This array was developed for osservatorio per il lontano infrarosso e le microonde su pallone orientabile (OLIMPO) balloon telescope with a requirement on bandwidth more than 10%. Sensitivity to both polarization components was achieved by a special meander-type arrangement of orthogonal L/2 dipoles. We present theoretical estimations for the optimal arrangement of 2-D arrays of CEBs, which allows achieving maximum efficiency in a wide band with the lowest noise equivalent power (NEP). A pixel layout with an optimal density of CEBs, sensitive to dual polarizations, and having more than 10% FWHM bandwidth at around 350 GHz was proposed and numerically analyzed. The layout consists of a periodic sparse array of orthogonal dipoles sensitive to both polarization components of the incoming signal. The numerical analysis confirmed that the sparse array is the most promising for a combination of high absorbing efficiency and low noise of the system and satisfying the 10% bandwidth requirements for the OLIMPO instrument. Different combinations of series and parallel connections of bolometers were considered for better noise properties to achieve the photon noise-limited level.

Şifrelenmiş Verileri Rast Gele Piksel Yaklaşımı ile Bir Görüntüye Gömme

With the recent developments in information and communication technologies, data is transferred to digital environments. However, it has become very important to protect the information in digital environments. This situation raises the need for information security. Cryptography and steganography are among the most effective areas in ensuring information security. This study was carried out in order to contribute to information security by using cryptography at the point of making data meaningless by encrypting, and steganography at the point of hiding meaningless data. In this study, random pixel layout approach is used to hide the encrypted data into a 24-bit image. The proposed technique was examined on images with different file types and resolutions. The Structural Similarity Index Measure (SSIM), Mean Square Error (MSE) and Peak Signal to Noise Ratio (PSNR) parameters were revealed to measure the effectiveness of the proposed approach. It has been observed from the application that this method increases the security level of embedding data process.

Improving the spatial resolution of silicon pixel detectors through sub-pixel cross-coupling

We present a concept to improve the spatial resolution of silicon pixel-detectors via the implementation of a sub-pixel cross-coupling, which introduces directional charge sharing between pixels. The charge-collection electrode is segmented into sub-pixels and each sub-pixel is coupled to the closest sub-pixel of the neighboring pixel.Such coupling schema is evaluated for a model sensor design with 50µm×50µm pixels and AC-coupled sub-pixels. A first-order SPICE simulation is used, to determine feasible coupling strengths and assess the influence on the charge-collection efficiency. The impact of the coupling strength on spatial resolution is studied with a dedicated simulation, taking into account charge-cloud evolution, energy-loss straggling, electronic noise, and the charge detection-threshold. Using simplifying assumptions, such as perpendicular tracks and no gaps between charge-collection electrodes, an improvement of the spatial resolution by up to approximately 30% is obtained in comparison to the standard planar pixel layout.

Real RGB printing AMOLED with high pixel per inch value

AbstractA 403‐ppi (pixel per inch) real RGB active‐matrix organic light‐emitting diode (AMOLED) was fabricated without using fine metal mask (FMM). Organic light‐emitting materials were printed on array panel, with a novel process that has the advantages of low cost and high pixel density. The uniformity of the organic light‐emitting diodes (OLEDs) was improved with carefully tuning printing parameters, and good panel performance was achieved. The key to such a process was the design of the hexagonal patterning of the pixels. The image quality of the panel with this hexagonal pixel arrangement was evaluated with a bmp format Pixel Layout Simulation picture.

Pixel Design Driven Performance Improvement in 4T CMOS Image Sensors: Dark Current Reduction and Full-Well Enhancement

Dark current (DC) limits the optical performance of CMOS image sensors. The main sources of the DC in a modern submicrometer process are the defects induced by the shallow trench isolation fabrication process steps. In this brief, we present a pixel layout technique to reduce the impact of these defects by removing the trench-oxide between the two adjacent edges of neighboring photodiodes (PDs). This isolation scheme relies only on the p-well layer and provides the further advantage of requiring less area. Hence, a larger PD can be designed, leading to an increased pixel fill factor. Experimental results show that this approach reduces the DC by 21% and increases the linear full well capacity by approximately 9%.

Development of an Area Image Sensor Pixel for an X-Ray Detector

Area photodetector devices (image sensors) are the main imaging element of digital X-ray systems used in medicine today. Since the cost of a medical diagnostics error is very high, the requirements imposed on the image sensor are very strict. We consider a sequence of procedures for the development of an area image sensor for biomedical X-ray investigations, which must reliably distinguish low-contrast details down to 80–100 µm. The development is aimed, in particular, at combining different parameters for different tasks, which require either a high frame rate at a low digit capacity or a wide dynamic range in the slow image sensing mode. The most important parameters of an image sensor are the fill factor of an optical pixel (photosensitive cell) and the quantum efficiency. The pixel layout and topology are proposed and a solution of merging the four neighboring photocells in a separate functional group (superpixel) with a large sensitive area and a potential well is found. The calculation and simulation allow us to develop specific recommendations and requirements on the photodetector for the developed X-ray sensitive panel, and determine the frame and bit rate ranges in the transmission lines.