A charge-pump led driver with PFC and low-frequency-flicker reduction

Santos, Rodrigo L. dos; Rufino, Diogo Moreira; Morais, Maxwell B. M. de; Edilson, M.

doi:10.1109/cobep.2017.8257256

Cited by 4 publications

(2 citation statements)

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“…The luminance was tested at 120 cd/m 2 , which was within the recommendation for the luminance of standardised charts to be between 85 cd/m 2 and 300cd/m 2 [29]. A fourorientation Landolt C chart design was introduced to the subjects [30] with an internally illuminated by standardised light-emitting diodes (LED) lamp that known for its lesser flicker [31], [32] and provides better colour properties [33].…”

Section: Visual Stimulimentioning

confidence: 99%

Contrast Ratios, Colour Elements, and Polarities in Visual Acuity Measurements

Chen

Muhamad

2018

IJET

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This study was aimed to investigate the effects of contrast ratios, colour elements, and polarities on visual acuity measurements. The visual acuities of 18 subjects were measured using 6 different modifications of the Landolt C chart in a 4-metre LogMAR design: ( Comparative analysis was performed to examine the effects of the three aforementioned parameters on visual acuity measurements. The visual acuities were found to be significantly different between the contrast ratios of 0.5 and 0.8, regardless of whether colour elements were present (blackon-white) or otherwise (yellow-on-green) [Friedman test:  2 (3) = 24.24, p < 0.05]. Interestingly, the LogMAR score was found to be significantly different between the yellow-on-green and black-on-yellow chart designs when the contrast ratio remained constant at 0.8 [Wilcoxon signed-rank test: z = 2.950, p < 0.05]. However, the effect of contrast polarity (positive/ negative) on visual acuity was not significant when the contrast ratio was fixed at 0.8 [Wilcoxon signed-rank test: z = 0.318, p > 0.05]. A lower contrast ratio and midrange wavelength colour reduced visual acuity. The effect of contrast polarity without colour elements on visual acuity was negligible.

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Section: Visual Stimulimentioning

confidence: 99%

Contrast Ratios, Colour Elements, and Polarities in Visual Acuity Measurements

Chen

Muhamad

2018

IJET

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“…Charge-pump (CP) converters are considered single stage and have a reduced number of components because of this, they were widely used to drive fluorescent lamps. CP converters to drive power LEDs are shown in the works [1][2][3]. However, only fluorescent lamps using the bridgeless concept together with CP are presented in the literature [4].…”

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confidence: 99%

Single‐stage PFC bridgeless converter

Fonseca

Nascimento²,

Badin³

2020

Electron. lett.

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A power factor correction (PFC) charge-pump (CP) bridgeless converter for LEDs is presented. In the input stage, coupled inductors, together with CP capacitors, are integrated into a half-bridge inverter, thus characterising the single stage. This topology even being bridgeless due to the positioning of the load operates with a bus voltage below the bending voltage. The CP configuration is used to reduce the LED's current ripple. The prototype achieves an output power of 60 W with high power factor, achieving the efficiency of up to 94%, 127 V ac input, total harmonic distortion of input current, with harmonic magnitudes within the IEC 61000-3-2 standard class C the device limits and flicker in conformed with the recommendation of IEEE 1789.

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