The pulse width modulation (PWM) dimming mode features good linearity and has been widely used for driving high-brightness light-emitting diodes (HBLEDs), in which the brightness change is reached by modulating duty cycle of signal to regulate average current flowing through LEDs. However, current-illuminance characteristic curve most LEDs nonlinear nature. Namely, under same lighting power fed...

PURPOSE To reevaluate the validity of the light scatter factor (LSF) formula of Paulsson and Sjöstrand, LSF = L/E (M2/M1-1), where L is the target luminance, E is the illuminance of the glare source at the eye, and M2 and M1 are modulation contrast thresholds measured with and without the glare source, respectively. This equation has recently been deemed invalid by Yager, Yuan, and Mathews. M...

The objective of this paper is to assess the capability of existing lighting simulation methods to predict the performance of complex fenestration systems, which are becoming a commonly used component in buildings construction domain. A specific experimental protocol was conducted to collect reliable reference data based on illuminance measurements inside a black box with (and without) one comp...

A photosensor is an electronic control device that adjusts the light output of a lighting system based on detected illuminance. While some photosensors simply switch lights on and off, Specifier Reports: Photosensors focuses on photosensors that are used with dimming electronic ballasts to adjust the light output of fluorescent lighting systems over a continuous range. These photosensors are mo...

Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but at lower illuminance with potential reductions in energy consumption. Consideration of experimental d...

This paper describes the implementation of a CMOS image sensor that performs a two-way rectified temporal high-pass filtering operation on the incoming visual signal. The sensor adapts to background illuminance and responds to local positive and negative illuminance transients at separately coded terminals. The transients are converted into a stream of asynchronous binary pulses, which are mult...

Changes of annulus luminance in traditional disk-and-annulus patterns are perceptually ambiguous; they could be either reflectance or illuminance changes. In more complicated patterns, apparent reflectances are less ambiguous, letting us place test and standard patches on surrounds perceived to be different grays. Our subjects matched the apparent amounts of light coming from the patches (brigh...

An all-printed photosensor based on polyfluorene derivatives has been developed for high illuminance range detection (>100 klux). The active layer is a blend of hole-accepting poly(9,9’-dioctylfluorene-cobis-N,N’-(4-butylphenyl)-bis-N,N’-phenyl-1,4-phenylenediamine) (PFB) and electron-accepting poly(9,9’-dioctylfluorene-co-benzothiadiazole) (F8BT). A top-absorbing architecture was used with pol...

Aspects of classroom lighting and décor that can promote discomfort and impair task performance through glare, and imperceptible 100 Hz flicker from fluorescent lighting, were examined in a sample of UK schools. In 90 classrooms, across eleven secondary schools and six local education authorities variables measured included flicker, illuminance at desks, and luminance of whiteboards. Results sh...

General illumination using LEDs has enabled designers to have precise control of the intensity and color of an illuminated area. In this work, I investigate how these systems can dynamically adjust to create optimal lighting conditions in the built environment. By incorporating environmental feedback into a system control loop, i.e., illuminance or luminance measurements, the precise intensity ...