A Combined Pulse Driving Waveform With Rising Gradient for Improving the Aperture Ratio of Electrowetting Displays

As a reflective display technology, electrowetting displays (EWDs) have the advantages of paper-like display, low power consumption, fast response, and full color, but the aperture ratio of EWDs is seriously affected by oil dispersion and charge trapping. In order to improve the aperture ratio and optimize the display performance of EWDs, a combined pulse driving waveform with rising gradient design was proposed. First, an initial driving voltage was established by the threshold voltage of oil film rupture (Vth). And then, a rising gradient was designed to prevent oil from dispersing. At last, the oil splitting and movement were controlled to achieve the target aperture combined with the pulse waveform. Experimental results showed that the oil dispersion of EWDs can be effectively improved by using the proposed driving waveform, the aperture ratio of EWDs was increased by 3.16%, and the stability was increased by 71.43%.

Driving Waveform Design of Electrowetting Displays Based on a Reset Signal for Suppressing Charge Trapping Effect

Electrowetting display (EWD) device is a new type of reflective optoelectronic equipment with paper-like display performance. Due to the oil backflow phenomenon, it is difficult for pixels to be maintained a stable aperture ratio, so the grayscale of EWDs cannot be stabilized. To reduce the oil backflow in EWDs, a driving waveform composed of a driving signal and a periodic reset signal was proposed in this paper. A direct current (DC) signal was designed as the driving signal for driving pixels. The aperture ratio of pixels was determined by the amplitude of the DC signal. The periodic reset signal was divided into a charge release phase and a driving recovery phase. During the charge release phase, the driving voltage was abruptly dropped to 0 V for a period to release trapped charges. In the driving recovery phase, the driving voltage was rapidly increased from 0 V to a maximum value. To reach the same grayscale of EWDs, the driving waveform was returned to the driving signal at the end of the driving recovery phase. Experimental results showed that the aperture ratio of EWDs was unchanged when the driving waveform was applied. However, the aperture ratio of pixels was gradually decreased with the conventional driving waveform. It was indicated that the charge trapping effect and the oil backflow phenomenon can be effectively inhibited by the proposed driving waveform. Compared with the conventional driving waveform, the speed of oil backflow was reduced by 90.4%. The results demonstrated that the proposed driving waveform is beneficial for the achievement of stable grayscale in EWDs.

Research on the Teaching Mode of Oral Courses for Kindergarten Teachers based on OBE

The kindergarten teacher’s spoken language course is the core course of the preschool education major. Its main purpose is to cultivate and improve the students’ ability to comprehensively use the kindergarten teacher’s oral language. This article is guided by the OBE concept, with the teaching goal of cultivating students’ thinking ability as the main goal, and adopts the 5P mode in classroom teaching, namely preparation, proposition, panel discussion, and debate display (Performance) and perfection (Perfection), thereby improving the teaching quality of kindergarten teachers’ oral courses.

Driving Scheme Optimization for Electrowetting Displays Based on Contact Angle Hysteresis to Achieve Precise Gray-Scales

As a new display technology, electrowetting display (EWD) has many excellent display characteristics, such as paper-like, low power consumption, quick response and full color. These characteristics make EWD devices very suitable for portable devices. However, the gray-scale distortion caused by the contact angle hysteresis of EWDs seriously affects the accuracy of gray-scale display. To improve this phenomenon, the hysteresis curve of an EWD panel was studied according to the motion characteristics of advancing contact angle and receding contact angle of oil in a pixel. Then, a driving scheme for EWDs using alternating current (AC) voltage instead of direct current (DC) voltage was proposed in this paper. And the advantages and disadvantages of the driving scheme at different AC frequencies from 90 to 2,700 Hz were analyzed through experiments. According to the stability of aperture ratio in EWDs, a 470 Hz AC driving scheme was determined. Experimental results showed that the aperture ratio distortion of EWDs could be reduced from 35.82 to 5.97%, which significantly improved the display performance of pixel units.

Selectively UV-Blocking and Visibly Transparent Adhesive Films Embedded with TiO2/PMMA Hybrid Nanoparticles for Displays

To simultaneously achieve the high visible transparency and enhance the ultraviolet (UV)-blocking performance of displays, inorganic–organic hybrid nanoparticles, comprising TiO2 as a core and poly(methyl methacrylate) (PMMA) as a shell, were uniformly incorporated into the optically clear adhesive (OCA) used in the front of a display device. The highly refractive TiO2 nanocore could selectively scatter UV rays, which degrade the display performance, owing to the differences in the refractive indices between the inorganic particles and PMMA matrix, thereby offering an improved UV protection property to the adhesive film. Moreover, the organic PMMA nanoshell maintained the high visible light transmittance of the pristine OCA film via the prevention of particle agglomeration. To examine the effect of the PMMA nanoshell and nanoparticle size on the optical properties of the adhesive films, the OCA films embedded with only TiO2 nanoparticles or hybrid nanoparticles with different particle sizes were prepared using a roll-to-roll process, and characterized in the range of UV and visible lights using UV-visible spectroscopy. It is experimentally revealed that the adhesive film including small TiO2/PMMA hybrid nanoparticles at an extremely low content exhibited enhanced UV-blocking properties and increased visible light transmittance compared to that with only TiO2 nanoparticles.

GPU ACCELERATED COMPUTING IN RADAR INFORMATION PROCESSING

Position synchronization on maps is a critical problem in displaying radar information. Previously, this process was done in a sequential manner in the central processing (CPU). This often causes some bottlenecks leading to a long processing time because of the limited CPU architecture. To mitigate this problem, we proposed an algorithm of parallel processing to take advantage of the multi-core architecture of GPU to quickly reproject coordinates in radar information processing, improving the information display performance. Practical tests were done on different data sets to demonstrate the performance of this method, and the result showed that the improvement speeds are between 10 to 100 times better in each test.

Foveated near-eye display for mixed reality using liquid crystal photonics

Foveated near-eye display is one of the most promising approaches to deliver immersive experience of mixed reality. However, it is challenged to conceive a compact optical system. Here, we introduce a method to use polarization optics via liquid crystal photonics to improve the foveated display performance. We demonstrate a benchtop prototype of this idea. We implement and combine two display modules for peripheral and foveal visions. A peripheral display consists of a polarization selective lens (PSL) module, a polarization selective diffuser (PSD), and a slanted projection system. An 80$$^\circ$$ ∘ diagonal field of view is achieved by on-axis optical configuration of the PSL module and the PSD. A foveal holographic display is composed of a spatial light modulator (SLM), a volume grating lens, and a microelectromechanical system mirror possibly in combination with a switchable polarization selective grating module. The holographic reconstruction using the SLM enables accurate focus cue generation and high resolution above 30 cycles per degree within 15$$^\circ$$ ∘ by 15$$^\circ$$ ∘ field of view. We explore and discuss the liquid crystal photonics in the prototype that has a novel optical design using volume gratings with polarization selectivity.

Compact Current Reference Circuits with Low Temperature Drift and High Compliance Voltage

Highly accurate and stable current references are especially required for resistive-sensor conditioning. The solutions typically adopted in using resistors and op-amps/transistors display performance mainly limited by resistors accuracy and active components non-linearities. In this work, excellent characteristics of LT199x selectable gain amplifiers are exploited to precisely divide an input current. Supplied with a 100 µA reference IC, the divider is able to exactly source either a ~1 µA or a ~0.1 µA current. Moreover, the proposed solution allows to generate a different value for the output current by modifying only some connections without requiring the use of additional components. Experimental results show that the compliance voltage of the generator is close to the power supply limits, with an equivalent output resistance of about 100 GΩ, while the thermal coefficient is less than 10 ppm/°C between 10 and 40 °C. Circuit architecture also guarantees physical separation of current carrying electrodes from voltage sensing ones, thus simplifying front-end sensor-interface circuitry. Emulating a resistive-sensor in the 10 kΩ–100 MΩ range, an excellent linearity is found with a relative error within ±0.1% after a preliminary calibration procedure. Further advantage is that compliance voltage can be opposite in sign of that obtained with a passive component; therefore, the system is also suitable for conditioning active sensors.