LED News

Researchers developing device to predict proper light exposure for human health

$1.8 million NIH grant supports research to study links between lighting, sleep, psychosocial stress

Scientists have long known that the human body runs like clockwork, guided by a circadian system that responds to daily patterns of light and darkness. Now a team of researchers is developing a personal device to measure daily light intake and activity, which could allow them to predict optimal timing for light therapy to synchronize the circadian clock to the 24-hour solar day and relieve psychosocial stress.

In short, scientists are creating a tool to help people literally “lighten up.”

By wearing this small, wireless device being developed by scientists in Rensselaer's Lighting Research Center, users can monitor their daily rest and activity pattern as well as exposure to circadian light. The tool will have the capacity to communicate with the user in real time to give immediate feedback regarding proper light exposure to promote a synchronized circadian rhythm. [Photo Credit: Rensselaer/Dennis Guyon]

Inadequate or irregular light exposure — something many individuals face on a regular basis — can cause circadian rhythm disruptions that can manifest into sleep and stress-related ailments. Supported by a $1.8 million grant from the National Institutes of Health (NIH), researchers in Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) are creating a small, head-mounted device to measure an individual’s daily rest and activity patterns, as well as exposure to circadian light — short-wavelength light, particularly natural light from the blue sky, that stimulates the circadian system.

The wireless tool will have the capacity to communicate with the user in real time to give immediate feedback regarding proper light exposure to promote a synchronized circadian rhythm, according to Mark Rea, director of the LRC and principal investigator on the project.

Like a clock that needs to be set daily for accurate time-telling, the circadian clock — an internal regulating mechanism that controls the repetition of biological activities such as core body temperature variations, hormone production and secretion, and sleeping and waking patterns, among other functions in the human body — requires similar “setting” from the light each day. A cycle of very bright days and very dark nights is the perfect regulator for the human circadian system, but patterns of light and dark in today’s modern world are often inconsistent with this cycle.

The advent of electricity has dramatically changed our light and dark exposure patterns, and indoor lighting can be insufficient to stimulate the circadian clock, Rea says. Exposure to indoor light sources during the night, including computer screens, may be too bright or seen for too long, to properly set the timing of the circadian clock. These disruptions can desynchronize the circadian rhythm from the solar daytime/nighttime cycle, leading to sleep problems and psychosocial stress such as mood and eating disorders, depression, and possibly immune deficiencies.

“Outdoor light levels during the day — even under cloud cover or during the winter — are of much higher levels than those found in windowless, electrically illuminated buildings, and this absence of suitable light may induce ‘circadian darkness,’” Rea says. “If an individual’s circadian light intake is deficient during waking hours, our device will be able to reliably predict the light therapy necessary to resynchronize the circadian phase with the solar day.”

Such treatments could range from standing outside for 15 minutes to sitting in front of a light box fitted with blue LEDs for a certain amount of time, says Rea.

Rea and his colleague Mariana Figueiro, assistant professor in the LRC and co-PI on the project, will collaborate with scientists from Brown and Yale universities on a study to uncover participants’ baseline circadian rhythms by collecting information regarding each person’s sleeping and waking cycles, light intake, and fluctuations in sleep quality, stress markers, and gene expression, which are all controlled by the circadian rhythm. Then, using light therapy treatment, the team will attempt to shift each participant’s circadian phase.

The results of the study will provide scientists in the LRC with the information they need to determine the level of accuracy required for the new device to accurately predict light-induced shifting of the circadian phase, according to Figueiro.

Additionally, monitoring each participant’s genes before, during, and after the light therapy may help the researchers determine whether or not light exposure can express or silence genes influenced by the circadian system, an emerging area of interest to the circadian and cancer research communities who have begun to focus on the possibility that our circadian clock controls the expression of a wide variety of genes, including many cancer-related genes.

Once developed, the new light monitoring and therapy prediction device has the potential to positively affect the lives of millions who suffer from circadian rhythm sleep disorders. Among others, potential populations that could benefit from the tool include college students, who experience a delayed sleep phase and go to bed and arise later than most people; international business travelers who suffer from jet lag; and shift workers who are often active at times opposite the solar day, according to the researchers.

This project was funded by the National Institutes of Health’s Exposure Biology Program — a component of its new Genes, Environment, and Health Initiative — which focuses on the development of innovative technologies to measure environmental exposures, diet, physical activity, psychosocial stress, and addictive substances that contribute to the development of disease.

Source: Rensselaer Polytechnic Institute

LED Products

The bright green gift that keeps on giving

Consumers around the world now have superior options for reducing their carbon footprint through the revolutionary technology of LED lighting. Lemnis Lighting offers the Pharox bulb, newly available in the United States at Upscale Lighting. The Lemnis Pharox bulb is the first LED-based light to offer the warm, soft white-light quality comparable to that of a traditional 40-W light bulb while using no mercury. The bulbs are recyclable, unlike their CFL counterparts.

On an annual basis, the Pharox bulb emits 90% fewer emissions than a traditional incandescent bulb, and is compatible with standard fittings. The Pharox bulb is as energy efficient as a fluorescent bulb, and over its significantly longer lifetime (up to 50,000 hours or approximately 35 years) it creates significantly lower carbon emissions.

Want more information? Click below.
Lemnis Lighting

Bi-color LED design illuminates portable electronic equipment

DDP, a leader in engineered LED solutions, has developed an LED assembly that provides task lighting in portable electronic equipment enclosures. The bi-color design features alternating white and green LEDs that allow operators to use night-vision technology while working with the equipment. DDP has already delivered the low-profile, bi-color LED lighting strip assembly for a portable communication system designated the SPEAR (Self-Propelled Electronic Armored Rack).

Utilizing surface-mount technology to reduce the profile of the LED assembly, DDP’s LED light strip systems can be designed for any enclosure, rack, or shelving unit. DDP’s LED light strip solutions are available in a wide variety of standard and custom configurations.

Want more information? Click below.
DDP

World’s brightest single-chip SMT LED

OSRAM Opto Semiconductors announces the arrival of Diamond DRAGON, launching in January 2008. Diamond DRAGON achieves brightness up to 250 lumens and will be available in whites ranging from 2,700 K through 6,500 K and all monochromatic colors. With this latest advance in technology, OSRAM will offer an LED that is ideal for indoor and outdoor general lighting, automotive forward and signal lighting, and other high-performance applications.

The exceptionally low thermal resistance of Rth = 2.5 K/W provided by the Diamond DRAGON's SMT package allows heat produced in the chip to be efficiently removed from the LED package. The maximum junction temperature of 175°C makes these LEDs extremely robust and enables applications where the LED cannot be cooled easily. The combination of low thermal resistance and high junction temperature capability allows simple integration of Diamond DRAGON LEDs in small spotlights such as MR-16 bulb retrofits and recessed downlights.

Want more information? Click below.
OSRAM OPTO

New green LEDs are 70% brighter

Cree, Inc. announces the commercial availability of green XLamp XR-E LEDs that are 70% brighter than the company’s previous green power LEDs. The new green XR-E produces maximum luminous flux of 87.5 lumens at 350 mA. The green XR-E LEDs complement the previously released blue XR-E LEDs for industry-leading performance in RGB LED applications.

Cree’s green and blue XR-E LEDs are the newest lighting-class members of the award-winning XLamp XR-E family, which includes industry-leading performance in warm- and cool-white LEDs. All are available in production quantities.

Want more information? Click below.
Cree

DC-to-DC dimmer for LED lighting products

LEDtronics announces the release of its new DC-to-DC Dimmer for LED Lighting Products, supporting 5-VDC to 40-VDC applications — up to 2 A or 24 W. The LED Dimmer makes it possible to dim all 5-VDC to 40-VDC LED products such as LED strip lights, LED bulbs, and LED floodlights. Since LEDs draw much less current than traditional incandescent bulbs, users had to buy a special high-end electronic dimmer to control the desired light levels for their LED lighting application. The DC-to-DC LED Dimmer is ideal to use for 12-VDC LED products, mix-and-match LED light strips, and LED bulbs. Maximum load per DC-to-DC Dimmer is 24 W.

LED dimming range is 0% to 100% of input. Dimmer output voltage is continuously adjustable between 0 and full-on. LED Dimmers operate on minimal no-load current (10 mA to 15mA). Power dissipation of the LED dimmer’s drive circuitry is less than 0.7 W. No extra load is added to the lighting circuit. Not for use with inductive devices such as motors, etc.

Want more information? Click below.
LEDtronics

Bling, bling: LED headlamp brightens up luxury ride

Lighting and electronics specialist Hella has developed a full-LED headlamp for the Cadillac Escalade Platinum. It will be the first sports utility vehicle (SUV) in the world to be equipped with this forward-looking lighting technology. With a color temperature of around 5,500 K, the light color of the white LEDs is considerably closer to daylight (approx. 6,000 K) than that of Xenon light (approx. 4,000 K).

Hella's full-LED headlamp for the Cadillac Escalade Platinum has been realized using various transmissive optical elements. Free-form glass projection lenses are being used for the first time anywhere in the world; thanks to their individual optical design, each area of the lens is responsible for a certain part of the light distribution on the road. Of the seven glass lenses used in a headlamp overall, only two are completely identical, all the others are of different shapes.

Want more information? Click below.
Hella

Drivers with integrated dot correction provide dynamic brightness control

Texas Instruments Incorporated (TI) introduces two 16-channel, constant-current sink, LED drivers with dot correction and grayscale on one integrated circuit (IC) for high-quality video. The drivers give designers increased system reliability and dynamic brightness control to enhance the resolution for large-panel mono-, multi-, or full-color LED displays, LED signboards, and display backlighting.

An extension of TI’s popular TLC5940 family, the new TLC5942 and TLC5945 provide high-performance capabilities, such as analog and digital dimming, in an integrated IC for large LED displays. A single external resistor can set the maximum current value of all 16 channels. Paralleling channels can provide higher currents. Both the TLC5942 and TLC5945 have two error-detection circuits for LED open detection (LOD) and a thermal error flag (TEF).

Want more information? Click below.
TI

Cool and confident cycling with wireless LED turn-signals

Bicygnals is a major step forward in bicycle lighting and bicycle communication intended as an aid for cyclists to communicate safely and effectively with other road users. Bicygnals combines front and rear bicycle lights with left and right direction indicators, giving a significant boost to confidence when cycling. The indicators are wirelessly connected between the front and rear light units so that the rear indicator always follows the front indicator as selected by the cyclist.

Bicygnals uses the latest hi-tech coded radio-frequency technology to provide wireless communication between front and rear units while providing simultaneous left and right indication at the simple push of a front-positioned button. State of the art, super-bright LEDs increase light output, optimize battery consumption, and have been specifically positioned within the units to maximize visibility to other road users, even during turning.

Want more information? Click below.
Gavin Thompson Design

Simplified design of edge-lit LEDs provides efficiency

ACI’s new edge-lit LED systems are turnkey-engineered LED backlighting solutions for LCD panels that utilize the latest in High Bright LED (HBLED) technology. Together with ACI’s patent-pending I-DRIVE LED drivers, ACI LED backlighting solutions provide significant advantages over alternative LED solutions that are generally more invasive, require complicated modifications, and are less efficient.

Features of the LED backlighting solutions include:

Electrical-to-light efficiency nearly twice that of the traditional CCFL approaches
Applicable on any size edge-lit display from 6.4 in. to 20.1 in., from any manufacturer
Suitable for new or retrofit installations
Long life (> 35,000 hr)
Superior brightness uniformity over CCFL backlights
Rail design allows for open/short of one or more LEDs without affecting the rest of the LED’s in the rail

Want more information? Click below.
Applied Concepts

World’s smallest flash LED driver

The AS3685 is an ultra-small, safe, simple, and fully integrated 700-mA charge-pump-based flash LED driver targeted at camera flash applications in mobile phones.

Designing LED-based flash functions with currents in the 700-mA range can have a significant impact on power consumption, especially in modern mobile phones (features like video streaming, MP3, or WiFi). Moreover, the large number of functions in a mobile phone already consumes a significant amount of PCB space, which makes adding a large flash LED and driver a challenge. The addition of these components conflicts with the ongoing trend towards ever-smaller phone designs, making actual component size a critical factor.

The wafer-thin AS3685 in a scale package resolves these issues. Measuring only 2 mm x 1.5 mm and less than 600 µm in height, it takes up just 14 mm2 of PCB space, including four external components. Following 0.25 mm PCB design rules, the AS3685 uses less than 50% of the space required by its closest competitor. The only external components that the AS3685 needs are low-cost capacitors and resistors.

Want more information? Click below.
austriamicrosystems