Lighting fixtures are one of the broadest classes of appliances—one that includes a wide range of applications and industries. Within the last decade, one of the most significant changes in these appliances has been the light source itself. In the past, most fixtures could handle either incandescent or fluorescent bulbs, and that was it.
The increased use of LED-based lighting, along with efforts to combine lighting with exterior and interior design schemes, is leading to new fixture designs. This gives engineers an opportunity to use a broad range of fastening and positioning mechanisms to improve the performance—not to mention, the visual and ergonomic appeal—of these devices.
Captive fasters, such as this 82 Dzus Lion Quarter, are great solutions for overhead light fixtures. They have a low profile and open simply with a quarter-turn, plus they cannot be over-tightened, so there’s little risk of damaging the diffuser when installing them. In addition, the hardware is all connected so it cannot get lost or dropped.
Two Key Elements of Functional Design
Whether they are designed for outdoors; factories and warehouses; offices and residential interiors; or even architectural applications, most light fixtures have features that address access and position control. Access control secures lighting fixtures, such as latches or locks. Position control lets users to move, adjust, and point the light beam on a specific point or area of work or display. Some lights, once positioned, are fixed in place; many others need to be moved and pointed according to changing needs.
Most lights, whether on desks and workstations, or mounted flush to walls and ceilings, have enclosures that seal the light source from the outside environment. Some enclosures are clear-paned, while others have diffusers; what they have in common is the need to be routinely and easily opened and securely closed to change burnt-out lights or perform routine cleaning.
In addition, many desktop and workstation lights have positioning hinges so they can be aimed to light areas that need it. These lamps are supposed to be attractive, so designers search for ways to add positioning hinges without disrupting the design.
Access control and positioning components are typically the only “moving” parts of a lamp. As such, they are more than purely functional: They include design and performance characteristics that contribute to users’ “touch point” experience. These characteristics can include:
- Being easy and intuitive to use.
- Providing tactile feedback when turned on or off or repositioned.
- Enhancing its perceived value.
- Increasing product reliability and durability.
By considering and evaluating these characteristics, designers can choose latches, hinges, and other components that help ensure the lamp offers users more value.
Constant-torque hinges, such as Southco’s ST Series, provide a constant and defined resistance through its range of motion. This lets a desktop lamp remain in any position without mechanical assistance. They are also compact, so they can be molded or bolted directly onto thin-profile housings to complement the design.
Enclosed lighting fixtures, whether equipped with clear or diffuser panels, need access controls. There are wide range of clips and latches available for this from many suppliers due to the simplicity of easy opening and secure closing.
Simple access is important, especially to maintenance staff in large facilities such as warehouses, airplane hangars, and parking lots. If access hardware is too complicated, it can slow maintenance.
In addition, because many of the latest light sources operate for several years, it might be some time between when the light panels or fixture are opened. Therefore, latches, particularly those used outdoors, need to keep panels tightly closed against moisture for longer periods of time.
Finally, most designers want to combine form and function, so they want latches and hinges that fit cleanly into fixtures, with surfaces and materials that work well together.
Access controls take many forms; several of the most useful for lighting include:
Quarter-turn fasteners. The simplest option, these fasteners are secured to the frame and open and reseal with a quick quarter-turn. Being fastened to the lamp ensures there’s no risk of lost components, so whenever the panel is opened, it can always be fully resealed when closed.
For lighting panels made of plastic or Lexan, quarter-turn fasteners can’t be over tightened like a screw, potentially cracking the panel. Quarter-turn fasteners that have a set torque help ensure consistent operation over long periods of time.
In addition, these fasteners can require a special “key” rather than a standard tool to operate them. This helps ensure that only authorized personnel can access the panels.
Because they’re quick and simple to operate, quarter-turn fasteners are good options for large, flat lighting panels, as well as other interior fixtures that must be secured.
Compression and draw latches. These latches are also effective devices at providing access to lighting controls. They are typically two-piece devices with a lever-like mechanism that securely latches a cover panel to the fixture’s main body. One of their advantages is that they can adapt to cover any manufacturing variations between the cover panel and fixture. On industrial lights that are not as precisely fabricated as high-end interior lamps, the draw latch pulls the covering panel to a closed, tight seal.
Compression latches perform a similar function with a different mechanism. They hold a door, panel, or cover shut by using a cam, while also compressing a gasket around the inside of the door to seal out moisture, dirt, and dust. This makes them particularly well-suited for basic outdoor applications (parking lot lights, for example), as well as exterior architectural fixtures.
Both compression and draw latches can be easily modified to incorporate locks that need keys or special access tools to open—another advantage for outdoor lights.
Hinges and constant torque. The other major “moving” part of a light fixture is the panel hinge. Although relatively simple components, the latest hinges give engineers new options for stationary overhead lights, as well as floor and desktop lamps that are routinely repositioned and adjusted.
Constant torque hinges, for example, provide smooth operation and a wide range of possible light positions. One can be embedded in a desk lamp’s pivoting joint, for example, where it lets users move and reposition the light, but it will then remain in place once they let go of it. The effort required to move the light lets it respond to a user’s deliberate actions, but it will remain in place if just casually brushed.
On many lights designed to be repositioned, this capability is done with clamps or latches. These often do not provide the range of possible positions or the smooth, flowing motion that constant-torque hinges supply. Also, constant-torque hinges can be moved with one hand; there’s no need to push a button or flip a lever to move it around.
In addition, constant torque hinges can be compact, letting them be cleanly and easily installed on lamps. They also deliver an extended service life, which is valuable for lamps on industrial workstations and anywhere constant movements and adjustments are common. Constant torque hinges provide repeatable and consistent motion and last much longer than hinges that use plastic bearings or wave washers to provide tension.
Draw klatches, such as Southco’s Series 97, accomodate misaligned lighting panels and draw them tight when closing to compress gasketing around the edge, sealing the light source against the outside environment.
Getting the right hardware for a light fixture depends to a large extend on where that fixture will be used. Here are some key factors in selecting the right device based on the environment:
Industrial. Quarter-turn fasteners for large, overhead fixtures keeps access reliable and simple. For overhead panels, constant-torque hinges prevent panels from dropping onto anyone accessing them when they are opened. The hinges also eliminate the need for lanyards that can get in the way during maintenance. If the factory or setting includes equipment that creates strong vibrations, engineers should opt for latches that compress panels together or look for hardware that compensates for misalignments.
Outdoor. For outdoor applications, the main concern is that any access devices fully secure covers against threats like moisture and exterior corrosion. For keeping out water (rain, snow, ice, or fog), compression latches with IP65 ratings are usually required. Engineers may also want to specify hinges and latches made of corrosion-resistant stainless steel and/or includes powder-coated surfaces.
Architectural. Selecting the right hinge to precisely control where a lamp points and the beam lands is critical in larger fixtures that create lighting effects on buildings, as well as in smaller fixtures for interior lighting.
Residential/Office. As noted earlier, fixtures mounted overhead or on walls are typically covered or enclosed, making simple quarter-turn fasteners a good solution. They attach to the fixture and are nearly impossible to lose. For desktop lights, positioning hinges with one-handed, intuitive operation, built-in feedback, and smooth motion can add to the aesthetics and user appeal both of the lamps and the entire work area.