What is a Graphic Overlay?
A graphic overlay, or membrane switch overlay, is the outermost layer of the membrane switch assembly. It is the intuitive part of an electronic interface that connects the user to the machine, device, or equipment; and the part of the membrane switch which is visible to the user, graphically defining the locations of the keypads, and explaining the operation of the equipment. For these reasons, the graphic overlay plays a significant role in defining the user experience.
A well-designed graphic overlay makes a powerful first impression of your company and your equipment. The design of the membrane switch overlay will set your equipment apart from the competition by providing an unsurpassed user experience.
Not only must the graphic (membrane switch) overlay explain the operation of the equipment, it must satisfy aesthetic requirements, and more importantly, environmental and physical end-use application requirements.
Environmental Considerations Affecting Graphic Overlay Design & Material Choice
Indoor Use vs. Outdoor Use
UV, extreme temperatures, humidity, and moisture all threaten to degrade and shorten the useful life of the membrane switch. Ask Pannam to recommend an overlay material that will best withstand these conditions.
Chemicals and Abrasion
Industrial chemicals and/or cleaning agents can damage the graphic overlay material. Care must be exercised to choose a material that withstands these chemicals.
Sterile environments may require an overlay material with anti-microbial properties that inhibit bacterial growth, as well as endure harsh cleaning agents.
Some artificial and natural lighting can cause glare that makes the overlay difficult to interpret and is strenuous on the eyes. Pannam offers overlay material in a range of gloss and antiglare levels to maximize the readability of your membrane switch overlay.
Heavy Use and Abuse
In environments that are subject to heavy operator use or even abuse, it may be necessary to specify a graphic overlay material that can withstand such misuse. Instead of a typical .007” thick polyester keypad overlay, it may be more suitable to utilize a more robust membrane switch overlay material such as:
- .020″ Metalphoto anodized aluminum
- .060″ acrylic
- .018″ stainless steel
- .040″ glass
Pannam utilizes special switch technologies that allow these more rigid overlays to properly actuate the membrane switch keypads. Talk to one of our application engineers for more information on these technologies.
Aesthetic Considerations Affecting Graphic Overlay Design & Material Choice
The surface finish of any graphic overlay is a direct function of material type and screen printing. Finishes may include:
- Metals (e.g. brushed aluminum, stainless steel)
Special Printing Effects
In addition to screen printing, membrane switch overlays may be printed using digital processes. This allows the graphic overlay to utilize creative effects such as:
- Photographic-quality images
- Custom spot colors
Unlimited Color Choices
Graphic overlays can be printed with a virtually unlimited range of colors, including:
- Metallic silver
- Metallic gold
Combining metallic colors with a brushed surface finish is an excellent way to simulate the look of brushed metal.
Back Lighting and Displays
Because most graphic overlay materials are transparent, the ability incorporate back lighting and display components is possible. Lighting options include:
- LED lamps
- EL lighting
- fiber optic lamps
It is important to specify a membrane switch overlay material that maximizes the desired back lighting effect. Pannam’s engineering team can assist you with material recommendation.
You may elect to emboss your membrane switch overlays, a secondary operation that raises the overlay in selected areas, typically the keypads. Styles include:
Lettering and other symbols can also be embossed for a more decorative look, or to accentuate brands and logos. Keep in mind that embossing does stress the overlay material, and will shorten the flex life of those keypads that are embossed.