LED Technology
and concentration, while warm light colours promote relaxation during breaks. Elsewhere in hospitals, a bright, friendly atmosphere in waiting areas is the perfect tonic to counter fear and anxiety, while sufficient luminance with uniform and glare-free illumination of paths facilitates orientation and safe movement.
tunable ipRGC solution is a logical market requirement.
Existing solutions deploy melanopic- enhanced LEDs and conventional LEDs in unison to create a tunable source. The problem here is that melanopic- enhanced LEDs still emit light outside the melanopic-sensitive wavelength range and conventional LEDs emit light inside the melanopic-sensitive wavelength range. It is therefore not possible to control the melanopic light output part of the solution independently using only the melanopic- enhanced LED.
An ipRGC CTT (colour temperature tunability) light source must have two functions with regard to circadian lighting: high melanopic light output in the morning and lower melanopic output through the afternoon and evening. By providing a clear separation of this dual functionality, it becomes possible to design a circadian tunable light source offering a combination of energizing blue and peaceful, calming, warm white, as provided by the Dynasolis. And yet, not just any blue will suffice. Phosphor-converted white LEDs typically rely on a blue pump in the range of 450 nm because producing LEDs at that wavelength maximizes wall plug efficiency. However, research into the non-visual receptors of humans reveals that the peak sensitivity for ipRGCs is closer to the cyan region, around 480-490 nm. To deliver system-level efficacy at 480-490 nm, phosphor-converted cyan represents the way ahead, especially if it provides the same forward voltage and Z-height dimension of the warm white LED for focal length matching and uniform mixing.
www.cieonline.co.uk.
CHCL in retirement and care homes Old age and age-related illnesses place high demands on lighting in retirement, care, and nursing homes. Many residents have poor eyesight and often need illuminance levels of 1,500 lux for reading and handicrafts, which is a good four times more than a 20-year-old. Unfortunately, a high percentage of residents also suffer from various forms of dementia, with those affected often restless and prone to wandering around the facility. Their movements are typically unsteady, with a high risk of falling. Shadows on the floor are easily perceived by dementia patients as unsettling obstacles. Other common issues include disorientation and a shifted sleep- wake rhythm. This situation is also stressful for staff and sometimes requires increased personnel deployment, with the additional cost this brings.
In the morning and at midday, wide-area lighting with vertical illuminance of 250 lux at the eye and a light colour of at least 5,000K contributes to daytime activation, while evening recommendations include direct-beam luminaires offering lower illuminance and a maximum CCT of 3,000K. During night hours, the facility should reduce lighting to the level necessary for orientation and in compliance with standards.
Dynasolis delivers a solution to a long-standing problem by combining two separate LED spectra: a cyan LED with an ipRGC sensitivity-optimized spectrum for high melanopic output (without emission in the rest of the spectrum); and an LED with very little to no light in the melanopic- sensitive wavelength range. At last, the healthcare market has a solution that provides independent control of this critical functionality.
CHCL in hospitals
Increasing numbers of hospitals are deploying HCL lighting systems that are simultaneously ergonomic, emotionally appealing and health- promoting. The result: patients and staff feel better, while treatments are more efficient. A stay in hospital usually means bed rest, where biologically effective lighting adapted to the course of the day can become
an important timer for the internal body clock. A wide-area brightening of the ceiling with high blue spectral components (over 5,300K) and illuminance levels of up to 1,600 lux (at least 250 lux vertically at the eye) is perfect during the day. For the evening and night, dimmable warm white light sources absent of any activating effect are ideal. Since light is also perceived subconsciously, circadian lighting is suitable for normal patient rooms as well as intensive care units and recovery rooms.
If the circadian rhythm of the patients is stable, the time required for therapy and care is shorter, bringing relief to hospital staff. Furthermore, dynamic lighting systems with preset lighting scenes ensure visual comfort in consultation rooms used by doctors or nurses. Light with high illuminance levels and high cyan components supports motivation
In addition to appropriate light levels, lighting with non-visual effects contributes to significantly more activity and the wellbeing of residents. Moreover, because residents are more active during the day, they also sleep better at night, leading to less need for medication and relief for nursing staff.
Time to see the light
In summary, most commercially available HCL systems work primarily by adjusting CCT. While a solution such as Dynasolis addresses colour tuning, it also delivers efficacy, colour quality and, most importantly, spectral light tuning that explicitly targets melanopsin- containing neurons in the retina of the eye. Due to the principal benefits provided by innovative solutions such as Dynasolis, hospitals and healthcare facilities are beginning to see the light, literally.
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Components in Electronics May 2023 53
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