Lighting fixtures represent one of the broadest classes of appliances in use today, covering a wide range of applications and industries. Within the last decade, one of the most significant changes in this class of appliances has been the lighting source itself. In the past, most fixtures were designed to handle either incandescent or fluorescent bulbs.
The increased use of LED-based lighting technologies, along with efforts to integrate lighting into exterior and interior design schemes, is leading to the creation of new fixture designs. This offers a major opportunity for design engineers to utilize a broad range of fastening and positioning technologies to enhance the functional performance and visual and ergonomic appeal of these devices.
Two key elements of functional design
Whether they are designed for outdoor, industrial/warehouse, office and residential interiors, or architectural applications, most lighting fixtures feature two functional elements: access control and position control. Most lights, whether situated 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 feature diffusers; what they have in common is a basic functional requirement: to be easily opened and securely closed on a routine basis, to change an expired light source and perform routine cleaning and maintenance.
In addition, many desktop and workstation lights use positioning hinges to routinely re-position a light fixture to beam light onto the area where individuals are working. These appliances are often designed for high visual and user appeal, calling on designers to search for ways to integrate the positioning hinge technology into the fixture without disrupting the overall flow of design.
Access control and positioning devices are typically the only “moving” parts of a light fixture. As such, they are more than purely functional: They feature design and performance characteristics that contribute to a person’s “touch point” experience when used. These characteristics can include:
- Easy and intuitive user efforts and feel
- Providing tactile feedback during operation
- Enhancing end user perception of value
- Increasing product reliability and long-term usability
By considering and evaluating these functional “touch point” characteristics for elements such as latches and hinges, lighting fixture designers help ensure that the products they design offer an enhanced level of value for the end user.
Access control requirements
Enclosed lighting fixtures, whether designed with clear or diffuser panels, need to incorporate access control elements. A wide range of clips and latches is available for this function from many suppliers due to the simplicity of the application: easy opening and secure closing.
Simple access is an important ergonomic characteristic, especially to maintenance departments for large facilities like warehouses, airplane hangars, large parking lots and garages, and retail interiors. If the access hardware is too complicated to operate, it can slow down maintenance time.
In addition, because many of the latest generation of incandescent and LED-based lighting sources now offer multi-year operation, accessing light panels may occur at much longer intervals. Latches – particularly those used in outdoor environments – need to stay reliably closed and keep panels fully compressed against outside moisture for greater lengths of time.
Finally, most lighting appliance designers seek to balance form and function, so access control latches and hinges that fit cleanly into fixture designs, with surfaces and materials that are easy to integrate, are also desirable.
Access control products take many forms; several of the most useful for lighting applications 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 appliance ensures there’s no risk of lost components, meaning that whenever the panel is accessed, it can always be fully sealed when closed.
For lighting panels made of plastic or lexan, quarter-turn fasteners offer another advantage: They can’t be over tightened like a screw, potentially cracking the panel surface. Quarter-turn fasteners that have a set torque amount help to ensure consistent operation over long periods of time.
In addition, these fasteners can be designed to require a special device or “key” to interface and operate them, rather than a standard tool. This helps ensure that only authorized maintenance personnel can access the panels.
Because they’re quick and simple to operate, quarter-turn fasteners are ideal options for large, flat lighting panels, as well as other interior fixtures that must be secured.
Captive fasteners, like the 82 DZUS® Lion Quarter-Turn are an ideal solution for overhead lighting fixtures, with a low profile design and simple quarter-turn operation that prevents the risk of damaging the diffuser due to over-tightening.
Compression and draw latches
These types of latches are also very effective devices for providing lighting access control. Draw latches are typically two-piece components with a lever-like mechanism to securely latch a light cover panel to the main body of the fixture. One advantage of draw latches is that that are very compliant to variability between the cover panel and the rest of the fixture; for industrial lighting appliances that are less precise in the fabrication of separate elements, a draw latch can literally “draw” the covering panel to a closed, tight seal.
Compression latches perform a similar function with a different mechanism of action. A compression latch holds a door, panel or cover shut by using a cam, and at the same time compresses 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 light fixtures.
Both compression and draw latches can be easily modified to incorporate locking features using keys or special access tools, another advantage for outdoor lights.
Draw latches, like Southco’s 97 Series can accommodate misalignment of lighting panels and draws the panels tight to compress the gasketing around the lighting bezel and seal the light bulb against exposure to environmental conditions.
Hinges: the advantages of constant torque
The other major “moving” part of a light fixture is the lighting panel hinge. While also considered a relatively simple component, the technical capabilities of the latest hinge technology provide industrial design engineers with new options to enhance the performance and “touch point” interaction with lighting appliances – both those that are fully stationary such as overhead lights, as well as workstation, floor lamp and desktop lights that are routinely positioned and adjusted.
One hinge technology with growing appeal for lighting designers is hinges with integrated constant torque. Constant torque hinges provide both smooth operation and infinite positioning of lighting equipment. A constant torque hinge that has been embedded into the joint of a pivoting desk lamp for instance, provides for intuitive movement of the beam of light by allowing the end user to position it at any point throughout the full range of motion, and remain in place once they have let go of the lamp. The amount of effort required to move the light is just enough to respond to deliberate action by the user, while still holding the light fixture in place during a more casual touch.
On many types of lights designed to be positioned, this capability is accomplished with clamping or latching mechanisms. These often do not provide the infinite positioning ability that a constant torque hinge supplies, or the smooth, flowing tactile feedback. In addition, a constant torque hinge allows one-handed operation of a lamp, rather than needing to push a button or flip a lever to move it around.
In addition, many constant torque hinges have been designed to be very compact, allowing them to be cleanly integrated into lamp designs. They are also engineered to deliver an extended service life, which is valuable when designing lighting fixtures for industrial workstations and other locations where constant movement and adjustment is common. Constant torque hinges provide repeatable and consistent motion that lasts much longer than hinges designed with plastic bearings or wave washers to provide tension.
Constant torque hinges, like Southco’s ST series, create a defined resistance throughout the entire range of motion, allowing the head of a desktop lamp to be held in any position without additional mechanical assistance. The compact design of these hinges allows them to be bolted or molded directly into a thin-profile product housing to complement industrial design.
Selecting access components and position control solutions
Lighting appliances are designed to accommodate a wide range of sizes, configurations and usage cases. For those fixtures that include closed panels, requiring access devices and positioning hinges, the application environment is a key factor in selecting the right device:
- Industrial: Using quarter-turn fasteners for large area overhead fixtures supports reliable and simple access. For large panels located overhead, using constant torque hinges means the panel won’t drop down on onto the individual accessing it when the access device is released, and also eliminates the need for lanyards that may get in the way during maintenance. If the industrial environment includes equipment that generates high levels of vibration, designers should choose latches designed to compress panels together or seek solutions that compensate for misalignment.
- Outdoor: The principal concern for outdoor applications is access devices that fully secure fixture covers against environmental challenges like moisture and exterior corrosion. For preventing water inclusion, compression latches that meet the IP65 rating are usually required for exterior applications, either directly or indirectly exposed to rain, snow and ice. Designers may also want to select hinges and latches with high-corrosion-resistant stainless steel construction or powder-coated surfaces.
Architectural: Whether used in larger fixtures used to create lighting effects on building exteriors, or smaller fixtures used for special interior lighting applications in homes, retail settings, galleries or other applications, selecting the right hinge to precisely control where the light points and the beam lands is very important. Constant torque hinges, with their smooth operation and infinite positioning control, provide a very elegant and precise device that helps the designer balance functionality with aesthetic appeal.
Residential/Office: As noted earlier, fixtures mounted overhead or directly to walls are typically covered or enclosed, making simple quarter-turn fasteners an ideal solution – particularly because they are attached to the fixture and are nearly impossible to lose. For desktop office lights, positioning hinges with touch point features and one-handed, intuitive operation can help add to the visual quality and user appeal of high-end lamps.
Lighting appliances are much more than mere light sources; they are an integral part of the environment that we live and work in every day. As lighting technology continues to evolve, every appliance designer has specific functional and aesthetic requirements for the devices they are creating. Working with the leading suppliers of fastening and positioning technology that have experience with the latest design solutions can enhance the functional performance and visual and ergonomic appeal of lighting appliances.