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Automotive 3.0 ?μm Pixel High Dynamic Range Sensor with LED Flicker Mitigation
摘要： We present and discuss parameters of a high dynamic range (HDR) image sensor with LED flicker mitigation (LFM) operating in automotive temperature range. The total SNR (SNR including dark fixed pattern noise), of the sensor is degraded by floating diffusion (FD) dark current (DC) and dark signal non-uniformity (DSNU). We present results of FD DC and DSNU reduction, to provide required SNR versus signal level at temperatures up to 120°C. Additionally we discuss temperature dependencies of quantum efficiency (QE), sensitivity, color effects, and other pixel parameters for backside illuminated image sensors. Comparing +120°C junction vs. room temperature, in visual range we measured a few relative percent increase, while in 940 nm band range we measured 1.46x increase in sensitivity. Measured change of sensitivity for visual bands—such as blue, green, and red colors—reflected some impact to captured image color accuracy that created slight image color tint at high temperature. The tint is, however, hard to detect visually and may be removed by auto white balancing and temperature adjusted color correction matrixes.
关键词： temperature dependence,sensitivity,LED flicker mitigation,quantum efficiency,automotive,CMOS,high dynamic range,image sensor
更新于2025-09-19 17:13:59
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Comparison of Neurovascular Coupling between Normal Tension Glaucoma Patients and Healthy Individuals with Laser Speckle Flowgraphy
摘要： Background The purpose of this pilot study was to investigate the differences in neurovascular coupling between Caucasian patients with normal tension glaucoma (NTG) and healthy subjects (HS) with Laser Speckle Flowgraphy (LSFG). Methods Measurement of optic nerve head blood flow was performed with LSFG. Mean blur rate of the whole optic nerve head (MA), of the big retinal vessels (MV) and of the microvasculature (MT) was analysed during continuous flicker light stimulation for four minutes. Results We included 12 eyes from 12 Caucasian patients with diagnosis of normal tension glaucoma and 12 eyes from 12 age- and sex-matched healthy individuals. MA, MV and MT all increased significantly in both groups during the observation period with no difference between the groups. Conclusion Neurovascular coupling is detectable in NTG patients. Flicker light stimulation leads to a comparable increase in ocular blood flow in glaucoma patients and healthy individuals.
关键词： flicker,laser speckle flowgraphy,ocular perfusion,normal tension glaucoma,neurovascular coupling
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) - Riga, Latvia (2019.10.7-2019.10.9)] 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) - Effects of PWM Dimming LED Illumination on Camera Images and Countermeasures
摘要： This paper presents the analysis of brightness fluctuation for camera images under the PWM dimming LED Illumination environment and countermeasures against it. The exposure dose of a camera, which depends on PWM frequency and duty, exposure time and shooting instant of a camera, and video frame rate, was analyzed using a computer simulation program. As a result, it was found that the brightness fluctuation did not occur in most cases when the PWM frequency of LED lighting was at a frequency of 24 kHz or its multiple. The experimental results confirmed the effectiveness of proposed brightness fluctuation prevention measures.
关键词： flicker,LED Illumination,PWM frequency,GaN HEMT,exposure time,camera
更新于2025-09-19 17:13:59
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Multipoint and energy-equal fiber-optic laser-ultrasonic actuator based on peanut-shaped structures
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： frequency stability,flicker,atomic frequency standard,Allan variance,phase noise,frequency noise,oscillator,measurement uncertainty
更新于2025-09-16 10:30:52
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[IEEE 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - K?rdla, Estonia (2019.6.12-2019.6.15)] 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - Power Quality Assessment of Indoor LED Luminaires
摘要： Due to the fact that it is a semiconductor based lighting equipment, the LEDs have important effects on the power quality. In the ever-expanding lighting industry, the use of LED equipment is increasing day by day. Therefore, it is very important to analyze and interpret the effects of LEDs on the grid. In this study, power quality measurements of 4 different commercial LED luminaires have been realized and the results obtained have been interpreted. According to the measurements, it is found that the power factor values are acceptable for the luminaries when they are completely on. However, when the luminaries are dimmed, it has been observed that the power factor decreased and the current harmonics exceeded the limit values determined by the related standards. On the other hand, it is seen that all the luminaires provide flicker boundaries. As a result of the study, it has been concluded that the effects of dimmable equipment on power quality should be analyzed in more detail.
关键词： LED lamps,harmonics,flicker,power quality,power factor
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Electrical and Computing Technologies and Applications (ICECTA) - Ras Al Khaimah, United Arab Emirates (2019.11.19-2019.11.21)] 2019 International Conference on Electrical and Computing Technologies and Applications (ICECTA) - Miniature Dual-Band Band-Pass Filter Using Slotted Ring Resonators and Coupled lines for L and S Bands Communication
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： atomic frequency standard,frequency noise,measurement uncertainty,oscillator,frequency stability,Allan variance,flicker,phase noise
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - A Multiplexing Off-Line LED Driver Achieves High Power Factor and Flicker-Free Operation
摘要： Although a single-stage off-line LED driver can achieve low cost and high efficiency, the notorious double-line-frequency flicker issue with a single-stage LED driver limits its usage in high-quality lighting applications. To solve lighting flicker, multiplexing operation is proposed in this paper. One switching cycle is further divided into two portions, namely phase one and phase two, which produces a main output voltage and an opposite ripple voltage. The main and the opposite ripple voltage are connected in series to form the LED voltage, which is a DC because of ripple cancellation. Therefore, a DC LED current can be produced and achieves flicker-free LED driving performance. A 7.5W experimental prototype had been built and tested to verify the design concept.
关键词： power factor correction,ripple cancellation,multiplexing operation,flicker-free,LED driver
更新于2025-09-12 10:27:22
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Recent Developments in Photovoltaic Materials and Devices || A Quick Maximum Power Point Tracking Method Using an Embedded Learning Algorithm for Photovoltaics on Roads
摘要： This chapter presents a new approach to realize quick maximum power point tracking (MPPT) for photovoltaics (PVs) bedded on roads. The MPPT device for the road photovoltaics needs to support quick response to the shadow flickers caused by moving objects. Our proposed MPPT device is a microconverter connected to a short PV string. For real-world usage, several sets of PV string connected to the proposed microconverter will be connected in parallel. Each converter uses an embedded learning algorithm inspired by the insect brain to learn the MPPs of a single PV string. Therefore, the MPPT device tracks MPP via the perturbation and observation method in normal circumstances and the learning machine learns the relationships between the acquired MPP and the temperature and magnitude of the Sun irradiation. Consequently, if the magnitude of the Sun beam incident on the PV panel changes quickly, the learning machine yields the predicted MPP to control a chopper circuit. The simulation results suggested that the proposed MPPT method can realize quick MPPT.
关键词： microconverter,maximum power point tracking (MPPT),incremental learning,modal regression on a fixed memory budget,photovoltaics bedded on road,insect brain,shadow flicker,embedded learning algorithm,partial shading
更新于2025-09-12 10:27:22
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Heterochromatic Flicker Photometry for Objective Lens Density Quantification
摘要： PURPOSE. Although several methods have been proposed to evaluate lens transmittance, to date there is no consensual in vivo approach in clinical practice. The aim of this study was to compare ocular lens density and transmittance measurements obtained by an improved psychophysical scotopic heterochromatic flicker photometry (sHFP) technique to the results obtained by three other measures: a psychophysical threshold technique, a Scheimpflug imaging technique, and a clinical assessment using a validated subjective scale. METHODS. Forty-three subjects (18 young, 9 middle aged, and 16 older) were included in the study. Individual lens densities were measured and transmittance curves were derived from sHFP indexes. Ocular lens densities were compared across methods by using linear regression analysis. RESULTS. The four approaches showed a quadratic increase in lens opacification with age. The sHFP technique revealed that transmittance decreased with age over the entire visual spectrum. This decrease was particularly pronounced between young and older participants in the short (53.03% decrease in the 400–500 nm range) wavelength regions of the light spectrum. Lens density derived from sHFP highly correlated with the values obtained with the other approaches. Compared to other objective measures, sHFP also showed the lowest variability and the best fit with a quadratic trend (r2 ? 0.71) of lens density increase as a function of age. CONCLUSIONS. The sHFP technique offers a practical, reliable, and accurate method to measure lens density in vivo and predict lens transmittance over the visible spectrum. An accurate quantification of lens transmittance should be obtained in clinical practice, but also in research in visual and nonvisual photoreception.
关键词： non-image forming,circadian light,ocular media,psychophysics,heterochromatic flicker photometry,cataract,clinical,lens density,photoreception
更新于2025-09-04 15:30:14
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Color and brightness encoded in a common L- and M-cone pathway with expansive and compressive nonlinearities
摘要： Lights near 560 nm appear brighter when flickered, whereas lights near 520 or 650 nm appear yellower. Both effects are consistent with signal distortion within the visual pathway—brightness changes at an expansive nonlinearity, and hue shifts at a compressive one. We previously manipulated the distortion products generated by each nonlinearity to extract the temporal properties of stages of the L- and M-cone pathways that signal brightness and color before (early stages) and after (late stages) each nonlinearity. We find that the attenuation characteristics of the early and late stages are virtually identical in both pathways: The early temporal stage acts like a band-pass filter peaking at 10–15 Hz, while the late stage acts like low-pass filter with a cut-off frequency near 3 Hz. We propose a physiologically relevant model that accounts for the filter shapes and incorporates both nonlinearities within a common parvocellular pathway. The shape of the early band-pass filter is consistent with antagonism between center signals and more sluggish and delayed surround signals, while the late filter is consistent with a simple two-stage low-pass filter. Modeling suggests that the brightness change and hue shift are both initially caused by the half-wave rectification and partition of signals into ON and OFF components. However, the hue shift is probably caused by the additional effects of a later nonlinearity that compresses chromatic red and green signals. Plausible sites for the expansive half-wave rectifying nonlinearity are after surround antagonism, possibly from horizontal cells, but the compressive nonlinearity is likely to be after the late filter.
关键词： lightness/brightness,color,nonlinearity,temporal vision,flicker sensitivity,vision models
更新于2025-09-04 15:30:14