Membrane keypads and membrane switches offer designers of electronic equipment a flexible, customizable user interface which is compact, versatile, reliable and assembly friendly.
Permark offer membrane keypads/switches that can incorporate the following:
Constructed of layers of polyester (PET) film combined with spacers and adhesive, electrically conductive inks are printed onto the film to form a circuit. Total thickness is typically 1-2mm. Depending on the application and environment, graphic overlay materials can be specified to resist harsh environments such as high moisture, high UV and chemicals. Tactile Feedback of switches can be built into the keypads by insertion of stainless steel tactile discs or embossing of the overlays. Permark can supply either Female Clinch or ZIF connectors (see specifications here)
Electroluminescent Lighting (EL)
EL lighting can be incorporated into membrane keypads, and is achieved through a printing process, thus giving great flexibility in customizing the design to your specific application.
A layer of phosphorescent material is printed between two conductive electrodes. When an AC current is applied to the electrodes the phosphor emits light.
This technology has a definite life cycle – in a typical application, this would be a half life of about 3000 hours. EL panels are driven by an AC source, commonly 120AV at 400Hz. An inverter derives this from DC supply of 5-24VDC. The higher the frequency, the higher the light output. The lifetime is also inversely correlated to the frequency – increased light intensity reduces lifetime. Often the Integration of a light sensor or timer within the circuit to switch the panel on and off extends the effective life of the EL panel.
Electroluminescent Lighting Panels are sensitive to humidity, moisture, and UV light, all of which are taken into account at the design stage.
Lumitex Woven Fibre Backlighting
Lumitex is a patented woven fibre optic sheet commonly used for applications such as LCD backlighting, Membrane switches, machine vision applications.
A computer controlled loom produces a sheet of precisely laid optical fibres, which is then laminated into layers to form the backlighting panel.
The thin panel is heat and EMI free and provides superior brightness, longer life, and significant design flexibility when compared with other backlighting methods. Power requirements can be as low as 10-20mA at 2 VDC and no inverter.
The light source is LED, or gas filled bulb, or halogen, and can be simply changed.
The above image shows the fibre optics bundled into a round ferrule where a light source is then attached.
Electronic Equipment requiring a user interface such as:
Above: Fibre optics bundled into a round ferrule where a light source is then attached.
In addition to standard quality checks through the production process, Permark performs testing for:
We can assist with advice at the design stage of a product development. Contact us here.
Information that is helpful in providing an accurate quote will include the following:
Estimate of daily key actuation