Lighting in Design Q1 2023
LED technology Linear architectural LED light fixtures come in a diversified range of output colour options, including solid white, solid colour, intelligent white, and colour-changing light. LEDs are p-n junction devices fabricated from indium gallium nitride ( InGaN) or aluminium indium gallium phosphide (AlInGaP) material systems. The InGaN and AlInGaP semiconductor dies emit in narrow spectral bands. The optical radiation is perceived by the eye as coloured monochromatic light such as red, green, or blue. Whi te l ight can be created by ut i l ising a semiconductor emitter to pump a phosphor down converter within the device package or through additive colour synthesis using a minimum of three primary colours. Phosphor converted LEDs are the dominantly used white light emitters. They are available in a whole spectrum of colour temperatures, which offers the freedom in selecting the most appropriate light colour for a particular application. Tunable white systems use white light LEDs of varying colour temperatures to modulate the colour temperature of white light in a continuously adjustable range. The use of RGB LED systems enab les implementation of dynamic lighting solutions that can produce white light and colours of various hues and saturation levels. Channels of amber or white LEDs seamlessly blend with channels of red, green, and blue LEDs to create RGBW, RGBA and RGBWA LED systems which come with a significantly expanded colour-mixing gamut. Dimming control Linear LED wall washers or grazers can be controlled via an analogue interface (i.e., 0-10 V dc) or a digital interface such as DMX or Ethernet. The interface allows the dimming circuits that adjust the light output of an individual, group, or entire array of LEDs to be operated by a light controller. The LEDs incorporated in these fixtures can be dimmed through pulse-width modulation (PWM) and constant current reduction (CCR). Analog dimming (CCR) may be inappropriate for applications that require a full dimming range and a constant colour temperature. To produce predictable colours from an RGB, RGBW, RGBA or RGBWA LED, each of its component LEDs requires individual, accurate PWM digital dimming control. These component LEDs are addressed individually to identify the specific DMX or Ethernet control signals. Uniquely addressing and controlling each lighting node – a multi-colour LED array – allow individual lighting fixtures within the installation to act in unison and enable an infinite variety and combination of dynamic effects.
typical IP66 ingress protection rating. The LEDs can also be protected from water, dust and other atmospheric influences with silicone-potting. The aluminium housing provides structural strength as well as conductive and convective thermal transfer for the LED module. The LED module consists of a linear array of LEDs assembled on a metal-core printed circuit board (MCPCB). The light distribution of the LEDs is individually controlled by secondary optics which can be reflectors, TIR lenses or freeform lenses. These optics typically produce asymmetric beam patterns with horizontal and vertical beam angle options ranging from narrow to wide. The LEDs operate on dc power which is regulated by an LED driver running directly from a commercial alternating current (ac) power source or a low voltage dc power supply. The ac-dc LED driver must transform the ac power into an appropriate direct current, while protecting the LEDs from power surges as well as overcurrent, short-circuit, overvoltage and over-temperature conditions. Multiple fixtures can be wired in series or in parallel, and installed in an end-to-end configuration or using jumper cables to add space between fixtures in a series. The maximum number of fixtures each circuit can support is determined by specific configuration details which include fixture power rating, fixture length, fixture spacing, circuit size, supply voltage, and leader cable length.
LiD Q1 - 2023
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