Mobile Display Research Articles

A 10 Gbps D-PHY Transmitter Bridge Chip for FPGA-Based Frame Generator Supporting MIPI DSI of Mobile Display

A 10 Gbps D-PHY Transmitter Bridge Chip for FPGA-Based Frame Generator Supporting MIPI DSI of Mobile Display

A 70 MHz Temperature-Compensated On-Chip CMOS Relaxation Oscillator for Mobile Display Driver ICs

A 70 MHz temperature-compensated onchip CMOS relaxation oscillator for mobile display driver ICs is proposed to reduce frequency variations. The proposed oscillator compensates for frequency variation with respect to temperature by adjusting the bias currents to control the change in delay of comparators with temperature. A bandgap reference (BGR) is used to stabilize the bias currents with respect to temperature and supply voltages. Additional temperature compensation for the generated frequency is achieved by optimizing the resistance in the BGR after measuring the output frequency. In addition, a trimming circuit is implemented to reduce frequency variation with respect to process. The proposed relaxation oscillator is fabricated using 45 nm CMOS technology and occupies an active area of 0.15 mm 2 . The measured frequency variations with respect to temperature and supply voltages are as follows: (i) ±0.23% for changes in temperature from -30 to 75°C, (ii) ±0.14% for changes in V DD1 from 2.2 to 2.8 V, and (iii) ±1.88% for changes in V DD2 from 1.05 to 1.15 V.

Improving color reproduction accuracy of a mobile liquid crystal display.

The default method for color representation on displays involves sRGB as device-independent encoding color space. For improving color reproduction accuracy, we develop a device-specific display characterization model for the Apple iPad Air 2. In separate articles, we will evaluate the same method for other devices and for other display technologies. This model is combined with an easy-to-implement new method to account for the influence of illuminance from ambient light. The combination is called the mobile display characterization and illumination model (MDCIM) for the iPad Air 2, representing modern liquid crystal displays. Seven observers performed psychophysical tests at ambient illuminance levels from 600 to 3000 lx. They visually compared colors of calculated images with those of physical samples. The MDCIM model achieves similar color reproduction accuracy as when using the default method involving sRGB encoding at 1000 lx, while considerably improving color accuracy at other illuminance levels. At 600 lx, 98% of the observers prefer images directly generated with the MDCIM model over those created using the default method. The average color reproduction accuracy improves by two categories on a five-point scale. At 3000 lx, the percentage of colors that is represented at least reasonably well, according to the subjective assessment of visual observers, increased from 0% to 60%.

Assessment of white for displays under dark- and chromatic-adapted conditions.

This study aims to investigate the white perception of mobile display devices under dark-adapted and chromatic-adapted conditions. The white perception was modeled with error ellipses and bivariate Gaussian distributions. The dark-adapted white encompassed a rather large area centered around 7300 K, slightly above the Planckian locus. The chromatic-adapted whites were highly dependent on the ambient illuminant, and were not parallel to the Planckian locus. Combined, the white region encompassing 6179 to 7479 K in correlated color temperature and -0.0038 to 0.0144 in Duv was suggested. The results of this study are expected to be the basis for enhanced white appearance on mobile display devices.

Resource-Efficient Mobile Multimedia Streaming With Adaptive Network Selection

From the advancements of mobile display and network infrastructure, mobile users can enjoy high quality mobile video streaming anywhere, anytime. However, most mobile users are still reluctant to use high quality video streaming when they are mobile due to costly cellular data and high energy consumption. In this work, we develop scheduling algorithms for resource-efficient mobile video streaming, which minimize the weighted sum objective of cellular cost and energy consumption. We first model the scheduling problem as a Markov decision process and propose an optimal scheduling algorithm based on dynamic programming. Then, we derive a heuristic algorithm that approximates the optimal algorithm. To evaluate the performance of proposed algorithms, we run simulation over YouTube video traces with audience retention graphs and mobility/connectivity traces in public transportation (e.g., commuting). Through extensive simulations, we show that our proposed scheduling algorithm has negligible performance loss compared to the optimal scheduling algorithm, where it saves 59% of cellular cost and 41% of energy compared to the YouTube default scheduler. We also implement our scheduling algorithm on an Android platform, and experimentally evaluate the performance compared to existing streaming policies.

Real time control device for reading distance and head tilt

The people’s daily routine is characterized by an exposure to short reading distances during a long time period. This is due because of excessive reading and writing work and also because the use of mobile display screens. The human visual activity has changed a lot during last decades, demanding to the visual system (both accommodative and vergencial level) an extra effort. To correct the associated effects of working with short distances, we present a Real Time Control device “RTC device” which consists of an optical measurement system and algorithmically correction for improving working distance. The RTC device contains a head tilt measurement system that monitorizes in real time. Our main goal is to design an optical device that could improve the visual performance of people by controlling the reading distance, and thus avoiding visual-functional and postural complications since the childhood.

An Approach to Design Highly Durable Piezoelectric Nanogenerator Based on Self‐Poled PVDF/AlO‐rGO Flexible Nanocomposite with High Power Density and Energy Conversion Efficiency

Till date, fabrication of piezoelectric nanogenerator (PNG) with highly durable, high power density, and high energy conversion efficiency is of great concern. Here a flexible, sensitive, cost effective hybrid piezoelectric nanogenerator (HPNG) developed by integrating flexible steel woven fabric electrodes into poly(vinylidene fluoride) (PVDF)/aluminum oxides decorated reduced graphene oxide (AlO‐rGO) nanocomposite film is reported where AlO‐rGO acts as nucleating agent for electroactive β‐phase formation. The HPNG exhibits reliable energy harvesting performance with high output, fast charging capability, and high durability compared with previously reported PVDF based PNGs. This HPNG is capable for harvesting energy from a variety and easy accessible biomechanical and mechanical energy sources such as, body movements (e.g., hand folding, jogging, heel pressing, and foot striking, etc.) and machine vibration. The HPNG exhibits high output power density and energy conversion efficiency, facilitating direct light on different color of several commercial light‐emitting diodes instantly and powers up many portable electronic devices like wrist watch, calculator, speaker, and mobile liquid crystal display (LCD) screen through capacitor charging. More importantly, HPNG retains its performance after long compression cycles (≈158 400), demonstrating great promise as a piezoelectric energy harvester toward practical applications in harvesting biomechanical and mechanical energy for self‐powered systems.

P-24: Novel Pixel Structure for Improving Transmittance of High Resolution LCD

We introduce the new pixel structure named ‘Gate Space Share (GSS)’. The new structure consists of the two transistors together in order to reduce the area of the transistors. Reducing the space of the transistor is efficient to the transmittance of the LCDs especially for the high resolutions LCDs. We achieved 40% higher transmittance than the conventional structure of the 5.0 inch Full HD mobile display.

P-184: Improvement of Color Mixing in High PPI Mobile Displays

In this paper, we introduce color washout-free liquid crystal display (LCD) with thin layered color filter (CF) technique. The thickness of 1.5 µm thin layered CF was achieved by optimizing the performance of color resist. Thin layered CF can reduce color differences (Δu′v′) for RGB displays in oblique viewing angles, which means reduced color mixing.

Head lights

A team from Arizona State University have developed a novel way to treat neurological diseases. Their method exploits devices normally associated with display technology and neuro-stimulation. Electronics Letters takes a look at their findings. The team believe that their manuscript is the first reported and successful use of flexible OLED display technology to optically stimulate neural tissue OLEDs, Organic Light Emitting Diodes, are thin-film electroluminescent devices that emit light when a forward voltage bias is applied across a transparent anode and reflective cathode. Flexible OLED displays are manufactured on thin and flexible plastic substrates, instead of glass, and are rapidly becoming the mobile display technology of choice for the latest generation of smartphones. Somewhat surprisingly, the main advantage for flexible OLED display technology is not mechanical flexibility or bendability. Instead, by replacing the traditional rigid and thick glass substrates with over 35 times thinner flexible plastic substrates, the overall case thickness of a smartphone can be reduced by as much as 10 percent. Using thin and flexible substrates also makes it much easier to add functional and visually appealing curved edges to the display, while improving durability and reducing weight. Given these advantages, flex OLEDs appear poised to replace conventional glass substrate-based displays in mobile applications. OLEDs have also found a use in wearable electronics. Until now, wearable electronics have been manufactured using microelectronic components bonded to printed circuit boards. However, these conventional wearables are typically quite rigid and planar, while biological surfaces are usually curved, soft and pliable. As an alternative approach, wearable biomedical devices have been manufactured using an inherently biocompatible, thin and flexible plastic display substrate. To date, the team from Arizona has also adapted flexible OLED display technology to manufacture a prototype photoplethysmograph (PPG) sensor array for precision cardiac monitoring and a programmable fluorescent microarray for point-of-care medical diagnostics in smart bandages. In the Letter featured, the group used the emitted light from flexible OLEDs, instead of electrical neuro-stimulation, to optically excite genetically modified neural tissue in vitro. Optogenetics is a relatively new and experimental neuro-stimulation technique that genetically modifies neurons to respond to light. In their conceptual therapeutic configuration, individual OLED pixels in a conformable flexible display would be turned on to illuminate and optically stimulate selected and localised peripheral nerves. The team explored the viability of this technology as a non-invasive alternative to both prescription drugs and surgery to treat chronic inflammatory disease and mental health disorders. The team hope that this new therapy could be used to treat patients by optically stimulating selected branches of the auricular vagus transcutaneously via the outer ear using a high-resolution array of red OLEDs manufactured on a flexible plastic substrate, similar to a peel-and-stick adhesive bandage, as opposed to a surgically implanted device. Preliminary analysis combined with in-vitro experimental measurements indicated that the flexible red OLEDs are bright enough to induce therapeutic optical stimulation in optogenetically modified neural tissue. As an alternative to conventional prescription-drug-based treatments, direct neuromodulation of peripheral nerves promises drug-free treatment of chronic inflammatory disease and mental health disorders, including arthritis, systemic inflammatory response syndrome, inflammatory bowel disease, post-traumatic stress disorder (PTSD), anxiety, and depression. Essentially, this technology uses peripheral neuro-stimulation to treat a number of diseases by helping the body heal itself, as opposed to having to take a pill to treat the same condition. Their preliminary data and analysis indicates that an experimental optogenetics-based optical stimulation using OLED technology may be a viable alternative to electrical neuro-stimulation. A potential benefit of peripheral neuro-stimulation is the promise of far fewer side effects during patient treatment. From its start at Stanford about a decade ago, optogenetics is now being widely investigated in a large number of research labs across the world. Much of this early work has focused on advancing the understanding of a number of neurological and psychiatric diseases and disorders. The team believe that the future of optogenetics work will increasingly put an emphasis on diagnosis and patient treatment. Hopefully, this future work will eventually allow doctors to treat patients using new peripheral neuromodulation methods as a safe alternative to prescription drugs and with far fewer side effects. A new biophotonic alternative to conventional prescription-drug-based treatments for inflammatory disease and mental health disorders is presented

Expanding Mobile User Experience Through the Use of Transparent Display

Background : A transparent display has important traits that distinguish it from legacy displays and thus holds potential new applications; on the other hand, it has the potential to cause cognitive problems, requiring a study of user experience that can improve a transparent display’s inherent special characteristics. Methods : This work focuses on mobile display experience to apply special characteristics of a transparent display. Two prototypes for two experiments were developed after predicting transparent display UX from existing researches. In the first experiment, with a low-fidelity prototype, various possibilities were found and the concept direction was established. In the second experiment, based on a high-fidelity and interactive prototype, agile development and inspection were repeated to verify the findings. For the second prototype, a transparent display layer was added on to the mobile display to suppose the superimposed or juxtaposed TMD(Transparent Mobile Display) concept. Nine interaction sets were also developed for the detailed investigation. Result : In the TMD concept, the transparent display layer (1) creates a sense of spatiality between information and caused new cognitive and emotional experiences; (2) naturally expands legacy display experiences; (3) operates as a tangible UI element and provides direct and quick experience; (4) provides practical experience of the concept of the layer, which is based on single display experience; and (5) enables users to set a virtual information area in the air. Conclusions : A transparent display has special traits to expand display experience in both cognitive and emotional ways.

Exploration of Location-Aware You-Are-Here Maps on a Pin-Matrix Display

Supporting blind and visually impaired people with digital maps that can enhance spatial awareness and learning about the surrounding environment is a challenge. This study introduces an audio-tactile you-are-here map system that presents map elements and users’ updated location on a mobile pin-matrix display for blind and visually impaired people. In addition to panning and zooming a map, in the system, a set of tactile map symbols consisting of raised and lowered pins have been proposed to present varying map elements. A field test with eight visually impaired subjects and eight blindfolded subjects who did not have experience with tactile maps and Braille was conducted. Subjects would locate surrounding streets easily after a short-time training, as well as nearby point-of-interests (POIs). The results of the evaluation indicated that the mean relative distance error was significantly lower with nearby POIs, which do not require panning while exploring, than far away POIs. Furthermore, it is important to improve the portability of the proposed prototype and develop a one-hand map exploration method.

A Semantic Learning Object (SLO)Web-Editor based on Web Ontology Language (OWL) using a New OWL2XSLO Approach

Today, we see a strong demand for real-time information, with a rapid growth of m-learning. We also see that there are many educational resources on the Internet. Learning objects (LOs) are designed as a means of reusing these resources. Most of these LOs are built for e-learning systems based on desktop computers, which prevents their use on mobile devices. A LO is an area that is open to research and has a lot of potential in the creation, adaptation and production of learning content. There are standards that describe LOs in general as IEEE LOM, SCORM. Semantic web and its associated technologies are increasingly used in electronic document editing while separating the content from the presentation. Creating a LO with the semantic web is complex and raises difficulties because of the editing tools that require general knowledge of XML syntax and related technologies. In this paper, the authors propose a new OWL2XSLO approach based on ontologies (OWL) allowing the generation of XML-Schemas LOs. They then derive a semantic LO web editor based on OWL2XSLO approach for the generation of a content type enabling the editing of interactive LOs with XML technology and which can then be integrated into LMS and adapted to the mobile display.

An optimized Radial Basis Function model for color characterization of a mobile device display

This paper presents an optimized color characterization model based on Radial Basis Functions (RBFs). The performance of the proposed model was tested on a number of different mobile devices and compared with the performance of other state of the art color characterization models. We compared the accuracy of models using the CIELAB color difference. Four different models were discussed in detail: Piecewise Linear Model Assuming Variation in Chromaticity, Polynomial regression, Artificial Neural Network, and proposed Radial Basis Function model. For training and evaluation of the models we measured a large number of color samples on various mobile device displays. Results have shown that our optimized RBF model has superior accuracy over other models with median color difference of 0.39. In addition, it has particularly good accuracy for colors on the boundary of device’s gamut with maximum color difference of 0.87, where other models shown unacceptably high (>10) color difference.

Distinct Contrast in CIECAM02 for Mobile Display

The absolute contrast ratio of a display is a distinctive measure of the display contrast. However, this contrast ratio does not match the perceived contrast as it only uses the physical characteristic of the display. Therefore, this paper proposes a contrast measure that considers the perceptually discriminable brightness within the display brightness ranges. First, the Weber-Fechner ratio is applied to determine the brightness ranges of the display gamut in CIECAM02. Thereafter, the number of brightness values for each brightness range is computed and the perceptually discriminable brightness is then estimated based on the sum of the ratio between the number of brightness values in each brightness range and the brightness length in the display gamut. A preference test was conducted on various displays using random brightness patches to evaluate the perceived contrast. Experimental results showed that the proposed measure is more consistent with human perception than previous contrast measures.

Paper No S12.1: Architectures of Oxide TFT for High Resolution Display (Invited Paper)

AbstractIn this paper, we present the architecture of oxide TFT selected from diverse TFT structures for the application to the high resolution mobile display. Due to the selection of proper materials and process, we can achieve highly stable BCE TFT and show the promise of vertical oxide TFT with the smallest TFT footprint.

Paper No S13.1: Visual Performance Characterization of Flexible Mobile Displays (Invited Paper)

AbstractThe measurement of flexible displays is possible only with special measurement arrangements using common display characterization devices. A conoscope with a working distance of 15 mm was used to demonstrate the dependency of viewing properties of a flexible active‐matrix organic light‐emitting display.

유기 전기 발광소자의 원리와 연구동향

Organic Light Emitting Diodes (OLEDs) have been receiving great attention in academic and industrial fields, and it is being actively applied to mobile display, as well as large area TV and next-generation flexible display due to their excellent advantages. In addition, the scope of research on OLED materials and device fabrication technology is getting expanded. This review discusses the principle and basic composition of OLED and also classifies OLED materials with different chemical structures according to their usages. Systematic classification of OLEDs by technical concept and material characteristics can help developing new emitting materials.

The High Photo-Sensitivity of Low-Temperature Poly-Silicon Lateral p-I-n Diode Utilizing Reflective Layers

In past research, most of Semiconductor photo-detectors were fabricated in thick single-crystal silicon wafer in order to obtain high photo sensitivity. They are widely used in the electronics industry in a variety of areas from ambient light sensors, image scanner to artificial retina systems. However, most of them suffered from high-temperature and complexity to the fabrication process. Therefore, in this work a polycrystalline silicon lateral PIN diode utilizing reflective layers (RL) by LTPS technology was proposed to achieve high photo sensitivity for the first time. When combined with photo-detectors, LTPS technology will become a promising one-panel solution in wearable chips or systems application [1]. The lateral thin-film diodes were fabricated on a glass substrate using the conventional LTPS process [2]. In which, the intrinsic region was definition by overlapping boron and phosphorous implant regions. In the past research, the space charge region of devices was confined to intrinsic region mostly [3], so that RL was designed upon the intrinsic region by using photolithography that was formed of tri-layer film stacks consisted of silicon nitride, silicon dioxide and molybdenum. This device was demoted as RL-PIN described in Fig1. In order to examine our RL-PIN device, a very low intensity planar light source (~10mw/m2 at peak) with 0o incident angle was supplied as backside illumination through the substrate BK-7 glass. In general, the multiple dielectric layers named buffer layer were used to isolate the device RL-PIN and substrate BK-7 glass. The buffer layer included oxide and nitride in this work. After that, it was found that the incident light from backside illumination obtained the high transmittance over 85% to polycrystalline silicon region based on Fabry-Perot theory calculation.For further investigation, photo-sensitivity was defined per watt incident light illumination generated the photo current to estimate the photo-sensitivity performance. In our research, the RL-PIN achieved a very high photo-sensitivity above 106mA/W with reverse bias which was higher three orders than without RL ones. In our implementation of RL-PIN, silicon nitride, silicon dioxide and molybdenum were used as a RL having high reflectivity above 98% to reflect the incident light through the intrinsic region. Furthermore, a bi-layer of silicon nitride and silicon dioxide as the buffer layer also provided the reflectivity above 27% to the other interface of the intrinsic region. The reflectivity could be calculated according to (1). Both of interfaces of the intrinsic region were associated RL and buffer layer with reflectivity above 98% and 27%, respectively. Furthermore, the polycrystalline silicon was not only placed in between RL and buffer layer but also had higher reflectivity around 5.0 higher than the others. Therefore, it was found that the optical-cavity phenomenon in the intrinsic region was occurred to improve light absorption and enhance photo-sensitivity. In conclusion, backside illumination had been first adopted in RL-PIN was fabricated by LTPS technologies to block incident light for high-performance photo sensors which can achieve very high photo-sensitivity due to the optical-cavity phenomenon for scientific applications. The RL-PIN was of increasing interest due to their application to mobile display with embedded sensors. Reference [1] Yoshitaka Nishizaki, Takehiko Yamashita,Takehiro and Satoshi Inoue IDW ’07 107. [2] Se Hwan Kim, Seung Hoon Lee, and Jin Jang IEEE electric device letters, vol. 31, no.5, MAY 2010 [3] IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 56, NO. 1, JANUARY 2009 Figure 1

An Automated Mobile Phone Photo Relay and Display Concept Applicable to Operational Severe Weather Monitoring

AbstractThe increasing use of mobile phones (MPs) equipped with digital cameras and the ability to post images and information to the Internet in real time has significantly improved the ability to report events almost instantaneously. From the perspective of weather forecasters responsible for issuing severe weather warnings, the old adage holds that a picture is indeed worth a thousand words; a single digital image conveys significantly more information than a simple web-submitted text or phone-relayed report. Timely, quality-controlled, and value-added photography allows the forecaster to ascertain the validity and quality of storm reports. The posting of geolocated, time-stamped storm report photographs utilizing an MP application to U.S. National Weather Service (NWS) Weather Forecast Office (WFO) social media pages has generated recent positive feedback from forecasters. This study establishes the conceptual framework, architectural design, and pathway toward implementation of a formalized photo report (PR) system composed of 1) an MP application, 2) a processing and distribution system, and 3) the Advanced Weather Interactive Processing System II (AWIPS II) data plug-in software. The requirements and anticipated appearance of such a PR system are presented, along with considerations for possible additional features and applications that extend the utility of the system beyond the realm of severe weather applications.