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A Pixel Circuit With Wide Data Voltage Range for OLEDoS Microdisplays With High Uniformity
摘要： A new pixel circuit is proposed for the realization of high resolution and high uniformity organic light-emitting diode on silicon (OLEDoS) microdisplays in this article. A compensation scheme is adopted to mitigate the influence of threshold voltage variation of the driving transistor on display uniformity. Furthermore, two coupling capacitors are used to reduce the voltage at the gate terminal of the driving transistor in order to extend the data voltage range. The performance of the proposed pixel circuit is verified in an industrial 0.18-μm CMOS process. Simulation results show that the data voltage of the proposed pixel circuit ranges from 0.5 to 3.12 V, which is up to 4.37× wider than the previously published pixel circuits. The emission current error of the proposed pixel circuit varies from ?2.1% to 2.08%, under the condition of ±5 mV threshold voltage variation for the driving transistor. The maximum emission current error changes from ?10.36% to ?2.62% when the OLED turn-on voltage is increased by 5 to 20 mV due to device aging. Furthermore, the proposed pixel circuit only occupies a layout area of 8.1 μm × 4 μm.
关键词： Aging,high uniformity,compensation,organic light-emitting diode on silicon (OLEDoS),threshold voltage variation
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Energy Efficiency Analysis of GaN-based Superluminescent Diodes
摘要： Gallium-nitride-based superluminescent light-emitting diodes (SLEDs) are attractive light sources for augmented or virtual reality devices and other applications. However, the energy efficiency of SLEDs is still far below the peak values reported for LEDs and laser diodes. Utilizing advanced numerical device simulation, this paper investigates the internal physical processes that cause the low SLED efficiency.
关键词： superluminescent light-emitting diode,Gallium Nitride,SLED,efficiency
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE Industry Applications Society Annual Meeting - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Industry Applications Society Annual Meeting - LED Power Factor and Quality Factor
摘要： This paper presents the LED power factor and quality factor simply characterized from the available terminal average current, average voltage, and RMS current to evaluate the electric power quality of LEDs. The LED average power is composed of the bandgap power and the resistive power due to the forward voltage and equivalent series resistor in the LED approximate linear circuit, respectively. The forward voltage and equivalent series resistor are characterized from the available terminal average current, average voltage, and RMS current to calculate the bandgap power and the resistive power. The LED power factor and quality factor are calculated from the bandgap power, resistive power and average power to evaluate the electric power quality of LEDs. Using a single-branch LED approximate linear circuit and a high-order LED piece-wise linear circuit, two verification examples, respectively, are demonstrated to calculate their LED power factor and quality factor.
关键词： light-emitting-diode,average power,root-mean-square,average current,forward voltage,resistive power,bandgap power,power factor,rms,LED,quality factor
更新于2025-09-16 10:30:52
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Pixel Circuit With Leakage Prevention Scheme for Low-Frame-Rate AMOLED Displays
摘要： This work proposes a new pixel circuit for active-matrix organic light-emitting (AMOLED) smartwatch displays with a low frame rate. Within the long emission period, the leakage current of a low-temperature polycrystalline silicon thin-film transistor (LTPS TFT) is reduced to suppress the distortion of the driving voltage at the gate node of the driving TFT. Based on the measured electrical characteristics of a fabricated p-type LTPS TFT, the HSPICE model is established to verify the feasibility of the proposed circuit. The analytical results indicate that the relative OLED current error rates are all below 4.73%, as the threshold voltage of TFT varies by ±0.5 V. Notably, the OLED current varies by only 2.94% during the emission period of 66.7 ms at a medium gray level, demonstrating the effectiveness of the leakage prevention scheme.
关键词： low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs),Active-matrix organic light-emitting diode (AMOLED),leakage current prevention
更新于2025-09-16 10:30:52
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Efficiency improvement of power LED modules using a hybrid aluminum nitride substrate
摘要： This study combined experimental and theoretical analysis to investigate the hybrid aluminum nitride (AlN) substrate that can effectively improve efficiency and heat dissipation of multi-chip LED modules. The experimental results showed that hybrid AlN substrate can effectively reduce the thermal resistance from junction to substrate ΔRjs by 46% compared with metal core printed circuit board (MCPCB) as driving current increased from 0.6 A to 1.6 A. Under the rated current of 1.2 A, the Rjs and chip temperature of the AlN module was approximately 0.73 K/W and 10 °C lower than that in the MCPCB module. Compared to MCPCB, the hybrid AlN substrate also had 25% higher luminous flux at 1.2 A. Simulating results provided insight understanding of temperature distribution inside the LED modules and showed good consistency with experiments. Additionally, the decreasing rate of substrate temperature (Ts) outside the chips in AlN LED module is higher than in MCPCB LED module. This study demonstrated that the hybrid AlN substrate is a reliable and a cost effective design that can effectively improve both efficiency and heat dissipation of high power LED modules.
关键词： Thermal,Efficiency,Light emitting diode,Aluminum nitride
更新于2025-09-16 10:30:52
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Light-Emitting Diode Spectral Sensitivity Relationship with Growth, Feed Intake, Meat, and Manure Characteristics in Broilers
摘要： Light-emitting diode (LED) light sources have high potential for replacing traditional incandescent lamps in broiler production. LEDs with short wavelengths (480 and 560 nm) have been reported to stimulate broiler growth. However, short-wavelength stimuli might also have potential negative effects on husbandry workers, which has restricted the application of LED technology to broiler production. In this study, we investigated the effect of human-friendly yellow LED light (580 nm), which is close to the wavelength of 560 nm and acceptable for humans, on broiler growth response. We further evaluated the effects of various LED lights on the feed intake and manure characteristics of broilers. The following seven light treatments were tested: red LED light (R group), yellow LED light (Y group), green LED light (G group), blue LED light (B group), purple LED light (P group), white LED light (W group), and incandescent bulb light (I group). We used a 12:12 light:dark cycle, as described in our previous study. The feed and water usage of each group were recorded daily, while body weight and manure weight were determined weekly. Manure from each group was sampled for subsequent analysis. We found that the effects of the LEDs on broiler growth were age-related. Broilers in the Y, G, and B groups had similar body weights. However, the relative body weight gain ratio of broilers in the Y group was always greater than those of broilers in the other groups, particularly those in the I group (p = 0.003). The mass ratio of water usage to feed consumption was highest in the R group, whereas the Y group had the lowest mass ratio. Analysis of manure characteristics showed that manure production was positively correlated with feed intake, and broilers in the Y group produced the lowest amount of manure. The water intake of the broilers and the moisture content of the manure were also positively correlated, suggesting that the lower moisture content of the Y group manure might be caused by decreased water intake. These findings suggest that human-friendly yellow LED light might be a good alternative to green LED, blue LED, and incandescent lamps and can successfully be applied to broiler production.
关键词： Intake characteristics,Broiler,Body weight,Manure characteristics,Yellow light-emitting diode (LED)
更新于2025-09-16 10:30:52
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[IEEE 2019 28th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN) - New Delhi, India (2019.10.14-2019.10.18)] 2019 28th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN) - Teaching Method for Robota??s Gripper Posture with a Laser Sensor on a Pan-tilt Actuator: A Method for Specifying Posture Feature Curves and Posture Feature Point <sup>*</sup>
摘要： We present a novel design and fabrication process using the hydrophilic con?nement effect and a 3-D printer for producing convex and concave microlenses on top of light-emitting diodes. We use energy conservation and a lawnmower algorithm to design a freeform lens, and transform it into heterogeneous microlenses. The diameters of the microlenses on top of the light-emitting diode are 500 and 200 μm for the concave and convex shapes, respectively. Heterogeneous microlenses are printed on a glass substrate using the hydrophilic con?nement effect of SU-8 photoresist and an inkjet printer. Then, the array is copied with a mold made by a 3-D printer for the replication process. In the replication process, the mold is ?lled with polydimethylsiloxane to reproduce heterogeneous microlenses. Experimental results show that this heterogeneous microlens array improves the light distribution uniformity of a light-emitting diode from 17% to 63%.
关键词： Freeform lens,light-emitting diode (LED),micro-structure on LED,microlenses
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 25th International Symposium for Design and Technology in Electronic Packaging (SIITME) - Cluj-Napoca, Romania (2019.10.23-2019.10.26)] 2019 IEEE 25th International Symposium for Design and Technology in Electronic Packaging (SIITME) - Thermal Model for LED Luminaire
摘要： Various electrical and thermal models can be found in literature but the thermal models developed for this paper, both the Spice equivalent circuit as well as the SolidWorks thermal simulation were built based on the assumption that there will be two ambient temperatures: one at the heat sink level and a different one above the primary lens of the LED. This difference is due to the fact that the LED is part of a lighting assembly that features a lens/light diffuser that prevents the exchange of fluids between the primary lens of the LED and the exterior of the assembly. In this paper the influence of the two different ambient temperatures on the LED temperature is studied.
关键词： thermal model,direct voltage,light emitting diode
更新于2025-09-16 10:30:52
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Facile synthesis of durable perovskite quantum dots film with near unity photoluminescence quantum yield for efficient perovskite light emitting diode
摘要： In this work, a bright uniform PSK QDs film is synthesized in-situ using an amorphous polymer and optimizing the stoichiometry. The in-situ formed QDs film grown in the presence of poly(vinylpyrrolidone) chains shows a photoluminescence quantum yield (PLQY) as high as 98% even under low light intensities (0.01mW/cm2) with a long shelf lifetime of up to 2 years under ambient light (nanocrystals retain 100% of the initial PLQY). The near unity PLQY is due to the passivation of the surface defects of the PSK QDs by the Lewis base pyrrolidone groups of the polymer chain. Further, the QDs film shows higher thermal stability that increases by a factor of more than 5 compared to the bulk film. High efficient green perovskite light-emitting diodes (PLEDs) are fabricated without electron transporting layer using the high luminescent in situ synthesized low roughness QDs film with a current efficiency of 48.18 cd/A and power efficiency of 6.88 lm/W. Such devices start emitting green light at 2.5V and reach a maximum luminance of 124727 cd m?2 at 7V with external quantum efficiency of 10.5%. Further, the flexible PLED based on PSK QDs yields a maximum luminance of 43990 cd m-2 at 7V.
关键词： Perovskite quantum dots,perovskite light emitting diode,in situ synthesis
更新于2025-09-16 10:30:52
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White and red LEDs as two-phase batch for cyanobacterial pigments production
摘要： Carotenoids and phycobiliproteins have a high economic value, due to their wide range of biological and industrial applications. The implementation of strategies to increase their production, such as the application of two-phase light cultivation systems, can stimulate pigments production, increasing economic turnover. In this sense, Cyanobium sp. was grown in seven different two-phase white/red cultivation arrangements, varying the time of each light from 0 to 21 days. Biomass, photosynthetic activity, pigments profile and antioxidant capacity were measured along time. Red light increased photosynthetic activity and pigments content (ca. 1.8-fold), and the use of a two-phase cultivation system generally raised bioactivity and production of phytochemicals. Among the studied, the optimal cultivation condition was found with 10 days of white followed by 4 days of red light. The optimized growth led to a productivity of 137.4 ± 0.8 mg.L-1.d-1 of biomass, 17.0 ± 0.2 mg.L-1.d-1 of total phycobiliproteins and 4.5 ± 0.2 mg.L-1.d-1 of carotenoids
关键词： cyanobacteria,carotenoids,phycobiliproteins,antioxidant capacity,light-emitting diode
更新于2025-09-16 10:30:52