Mid-power LEDs achieve high M/P ratios

19th June 2020
Mick Elliott

Now available at distributor Digi-Key are Luminus Devices’ Salud 3030 mid-power LEDs.

They are engineered and specified to achieve specific melanopic/photopic (M/P) ratios in addition to providing light that is comfortable and renders true colours.

Scientists studying human circadian rhythm and the physiological reaction to light have determined that low M/P ratios are a signal to the body to prepare for sleep and higher M/P ratios tell the body to be more alert.

Sunlight is a perfect example of illumination with a high M/P ratio. Typical daylight is approximately 6500 K with an M/P ratio of ~1.1.

Most light at cooler temperatures has a high M/P ratio; however, it is generally not desirable to illuminate spaces with high correlated colour temperature (CCT) LED light as it tends to be bluish and feel uncomfortable.

The M/P ratio is a metric designed to quantify lighting’s circadian effect. The higher the MP ratio, the stronger the circadian effect of the light source.

Increasing blue and cyan content suppresses the production of melatonin in the body and raises the M/P ratio.

As the demand for human-centric lighting grows, lighting designers will need to plan for adequate levels of melanopic lux (lux multiplied by M/P ratio of the light source).

Cool CCTs tend to have higher levels of blue and cyan content and higher M/P ratios. Under this type of light, people tend to be more alert and productive making it perfect for schools, factories, offices, and more.

Warm CCTs often have higher red content and tend to have less blue and cyan so their MP ratios are lower and are ideal for night time relaxation and preparation for sleep.

It is not typical to illuminate architectural spaces with very cool CCTs (>4000 K), so the challenge is to create warmer LEDs, 4000 K and below, with higher MP ratios.

With Salud LEDs, high M/P ratios and high melanopic lux can be achieved without having to use high CCTs and without having to over light the space.

The result is lighting that is more comfortable, saves energy, reduces glare, and keeps occupants healthy, alert, and productive.

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