A downlight, also known as a recessed light, canister light, or can light, is a kind of ceiling fixture in which the light source is set back from the plane of the ceiling. The use of downlighting has increased recently in part because of the flexibility of the many downlighting luminaires that are currently on the market, as well as the ability to apply downlighting in a variety of environments that require either general lighting, task lighting, accent lighting, or similar lighting, including combinations thereof. Due to the possibility to use a variety of fixtures created specifically for downlighting applications, downlighting offers a degree of versatility that is unattainable with many other types of lighting, including wall-washing, accent, and ambient lighting. Since downlighting luminaires are often recessed in a ceiling, the sheer nature of downlighting permits the applied luminaires to be relatively inconspicuous.
The great majority of collimated downlighting illumination systems are recessed in fake or lowered ceilings; alternatively, they may be supported by a structure that is joined to a solid ceiling or embedded in a wall. Such downlighting systems are very attractive since they complement the ceiling flush and are often used in commercial lighting applications. In "downlighting" situations, lighting fixture assemblies are nested above a room's ceiling or sub-ceiling with the majority of the fixtures being hidden by the ceiling. The fixtures are thus unobtrusive while providing efficient illumination within the surrounding space beneath an aperture in the ceiling whereby light is directed from lamping carried by the fixtures. Downlighting luminaires must be functional and effective, and as a result, they must be able to perform the typical functions of downlighting luminaires, such as being effective, able to dim, producing useable light, having advantageous spacing, etc.
Today's houses and businesses are increasingly using recessed lighting fixtures, often known as downlights. Recessed lighting fixtures and downlights are increasingly used for interior lighting purposes since they may meet a variety of needs and are not only functional but also visually beautiful. Due to a variety of options involving design elements of the luminaires themselves as well as characteristics of the illumination generated by downlighting luminaires of specific configurations, downlighting luminaires can serve a decorative function in addition to specific lighting functions. Therefore, a downlight can be used with almost any design scheme to complete a variety of lighting tasks, such as emphasizing specific decorative or practical elements within the environment space or combining with other downlights and/or another lighting to provide general illumination within the space. It is advantageous to apply decorative downlighting luminaires that produce distinctive illumination, such as colored lighting effects, to tie or complement a colour palette used by an architect or interior designer and to create unique environments, such as in posh offices, gathering areas, and corporate lobbies.
Systems for downlighting illumination are specifically designed to work with a certain kinds of light sources, such as high-intensity discharge (HID) lamps, compact fluorescent lamps (CFLs), incandescent lamps, halogen lamps, or more recently, light-emitting diodes (LEDs). Due to increased brightness per watt qualities over incandescent bulbs, a significant majority of downlighting systems now employ CFL lamp technology. CFL lamps, however, produce light in all directions by nature (with the exception of the area where the electrical connection joins to the body of the gas-filled tube), which results in a large loss of light when used in a downlight system. Consumers in both the business and residential sectors are interested in LED lighting due to its benefits. LED lighting has many benefits, such as lower power consumption, longer lifespans, and much less environmental waste. Furthermore, it is thought that LED lighting offers improved aesthetics. In addition to replacing conventional light fixtures with LED fixture retrofits in existing building infrastructure, this has led to an increase in the choice and installation of LED lighting in new construction. In comparison to CFL-based systems, downlights based on LEDs, which are intrinsically directed light-generating sources, have a large LOR (Light Output Ratio) advantage. This is because the light released by LEDs often has a beam angle ranging between 10 degrees and 140 degrees.
An LED module is fitted into the housing, or "can," of the light fixture. The LED module may have one or more LEDs that are mounted on a single substrate. A cylindrical thermally conductive body, such as die-cast aluminum, is often used as the housing. A heat sink designed to transfer heat from the LEDs and the LED module may be thermally linked. The housing also functions as a heat sink, removing heat produced by the light source. The housing may feature a number of latitudinal spirally extending heat radiating fins positioned centrally towards the base of the housing to maximize heat radiation from the downlight and thus boost the cooling of the light source. There are several configuration options for the heat sink. Each fin may have an elongating radial section that extends from the core component and an additional straight portion that extends directly from the radial portion. The housing's outside surface may be treated to enhance its emissivity, for as by being painted black or anodized, to further increase the emission of heat energy. The LED module may be attached to an MCPCB (metal Core Printed Circuit Board) with a circular shape. This type of printed circuit board has layers, with the metal core base typically being made of aluminum, the dielectric layer serving as a thermal and electrical insulator, and the copper circuit layer serving as the electrical connection layer for the circuit. The thermally conductive PCB may also be built using an MCPCB, direct-bonded copper (DBC) substrates, insulated metal substrates (IMS), or ceramic substrates. Since electricity is delivered to the device as AC voltage, control circuitry that incorporates an AC-to-DC converter may often be used to operate LED downlights. The conversion circuitry (which may include a transformer and one or more solid-state electrical components, such as diodes and one or more transistors), may be integrated inside the downlight or linked externally.
To further direct the light output from the LEDs, an LED downlight often includes a reflector and a diffuser. For the purpose of reflecting, refracting, transmitting, or dispersing light, a reflector housing may be fitted mostly around the LED light source. A reflective substance, such as silvered plastic or aluminum, is used to create the reflector. To serve as the LED module's secondary heat sink, the reflector housing may be connected to the heat sink and/or the can. The size and form of the light source, the size and shape of the aperture opening, and the required photometric distribution are some of the variables that might affect the actual shape of the reflector. The size, arrangement, and proximity of the LED array to other optical components, together with the reflector's shape, diffuser, and size, determine the beam spread. When a number of these units are used to uniformly illuminate a surface, the beam spread determines the coverage of each lighting unit as well as the amount and spacing that are needed.
The trim ring provides a beautiful framing for the lighting fixture. A wide range of hues, forms, textures, and arrangements are possible for the trim ring. Typically having intrinsic color and placed in the luminaire aperture or hung below the aperture, such trim commonly takes the shape of glass or acrylic rings or plates of various sizes and designs.
Recessed lighting fixtures for ceilings often come with a frame that may be fastened to the ceiling's structural supports. The retrofit light fixture is designed to be installed without the need for tools or hardware into an existing aperture in the ceiling or in a mounting frame. When the retrofit downlight is inserted into the aperture, the spring bands are designed to deflect inward. The spring bands may revert to their preloaded condition after installation, aiding in the ceiling fixture's security.
