Lexicraft Ltd. is a supplier and manufacturer of high quality membrane switches offering an extensive range of standard and special purpose membrane switches, keyboards and keypads. Each is manufactured to the highest standards of quality, performance and reliability at competitive cost, meeting the needs of specific applications. This page lists some of the types of membrane switches, membrane switch panels and membrane keypads that we manufacture.

Tactile feedback within a membrane keyboard is achieved using either metal dome inserts or by embossing domes into a plastic layer. In both cases, the domes can either be passive, sitting over a normal flat switch to give an enhanced tactile feel, or active, where the dome forms part of the circuit when actuated.

A three layer tactile switch is perhaps the simplest and cheapest structure. It has the shorting pad within a dome on the top (graphic) layer. Polyester domes are capable of more than five million cycles within a 20ms contact bounce time.

A five layer structure is normally specified where other requirements make three layer structures impractical, or where design features on the overlay would conflict with domes in the centre of the keys.

Keyboards based on Printed Circuit Boards have the lower circuit etched onto the PCB, which can also hold rear-mounted components. The upper layers, which are the same for a flexible circuit, are then laminated to the PCB to form a single unit.

Either type of keyboard may be mounted onto a rigid panel or moulding, which can be carried out either by Lexicraft or by the customer.

Keyboard switches can be either flat or tactile and can be combined within the same keyboard.

Tactile switches

Tactile switches allow the operator to feel a significant movement as the switch closes. With flat switches, there is still some movement as the membrane switch is pressed, but it is generally too small for it to be felt by the operator.

Flat Switch Construction

Standard three-layer switch construction can either be a keyboard with no graphic overlay, or the shorting pad can be printed on the overlay behind the graphics.

Five and Seven layer switches are also available, providing the facility to incorporate separate overlays; these types of flat switch may be specified under a number of circumstances:

• where the overlay requires embossing;

• where the operating environment will be particularly harsh

• where customised keyboards are to be used on a standard switch array

Sales for Membrane Switches:

Copyright 2002. Lexicraft Ltd. 50 Cleveland Street, Birkenhead, Wirral. CH41 6LG. Registered in England No. 536750. VAT No. 163 54 37 62.