Electroluminescent Backlit Membrane Switch

Why Electronic Touch Systems? Read more about us. Click on the image and request a sample. MEMBRANE KEYPAD DESCRIPTION In its simplest form a membrane keypad consists of one or several keys within a flat panel (less than 1mm thick). Each key consists of an open contact between two tracks or wires that exit at the back of the panel in the form of a tail that can then be connected directly to a PCB (Printed Circuit Board). Each key is graphically represented on the top panel and to operate all that is required is a simple press of a finger on the designated key to momentarily short the contact.

THE GRAPHIC

The graphic or top layer has many possibilities. Because the raw material is clear and all the colours are printed individually it is possible to leave clear areas in the graphic that can create any shape of window for displays or LED ports. Colour combinations are endless but remember colours are individually printed resulting in a cost implication.

Typically a basic unit starts with two colours, one colour for the detail and the second colour for the background. Colours normally vary from two colours to five colours but there is no limit. Solid colours are preferred as half-tone printing is limited and can lead to extra expense.

The printing process is currently restricted in this way but digitally printed graphics with full colour resolution may soon be possible. For colour references we use the universal Pantone colour chart as a guide to the finished product.

CIRCUIT DESIGN OPTIONS

The circuit assembly consists of two layers, an upper circuit and a lower circuit, separated by a spacer material. The keys only make contact when the upper circuit is pressed down onto the lower circuit. Both circuits are joined at a single connector on the end of the tail.

Unlike PCB boards the tracks are printed with conductive ink onto a clear polyester film. This allows many options but also limitations on spacing of keys and circuit layout e.g. a membrane switch with up to 7 keys can have a single common track on one layer and then 7 more tracks, one to each key on the other layer resulting in a tail with 8 tracks leading off the membrane keypad. Where more keys are required for example a 12 key membrane it is preferable to use a X Y matrix configuration. In other words one layer will have 3 tracks for the columns and the other layer will have 4 tracks for the rows resulting in a 3 x 4 matrix and 7-track tail. In this situation your microprocessor will interpret which key has been activated and the resulting response processed.

TAIL AND CONNECTIONS

The tail is what connects the keypad to your interface or processor. The tail can be manufactured to any length, normally 50mm to 200mm and have various connection options. Most popular is the female type with housing at at 2.54mm pitch and is suited to plug into a standard header on a PCB. Male solder tabs are also available to directly solder into a predrilled board. There are several PCB mount type connectors where the tail end can push fit into a connector already mounted on the PCB. Some of these PCB connectors offer a 1mm pitch for tight spaces and this would result in a narrower width of the keypad tail.

TACTILE OR NON TACTILE

Standard construction of the membrane keypad offers no tactile feedback but an audio or visual display can staisfy most users. Where a physical fedback is required tactile keys are an extra feature. These consist of metal clickers incorporated inside the membrane assembly that offer a positive click when pressed.

EMBOSSING THE GRAPHICS

It is possible to raise certain areas of the graphic to create either ridges around the keys or the whole key itself. The process is mostly cosmetic but is very popular and the results pleasing to the eye.

EMI / RFI SHIELDING

An extra layer, either solid or in a grid pattern, can be incorporated between the graphic and the upper circuit. This layer facilitates the cancellation or dissipation of electrostatic build up on a person's finger. Electrostatic discharge can interfere with or damage sesitive electronic components. RFI shielding used on non conducting composite casing materials to shield sesitive electronic devices from radio frequency electromagnetic interference.

INTEGRATED LED's

Surface mounted LED's can be located inside the membrane keypad either with their own circuit and tail or incorporated with the key circuit layer and become part of the single circuit layout. Normally the graphic is embossed over the LED with the option of printed transparent colours to enhance the look of the LED on the graphic.

ELECTROLUMINESENT LAMPS

Backlighting is often desirable but past technology has been expensive and the results disappointing. Electronic Touch Systems (ETS) is currently testing new products and would welcome your requirements and participation.

OTHER SERVICES:

Our experience with printing and materials allows us to offer many other products.

PANEL AND OVERLAYS

All manufactured to the same specifications and dedication as our membrane switchs, offering the same benefits and design flexibility.

LABELS AND DIALS

Volume consistency and service are the requirements and here you will find no better supplier.

DOMED LABELS

You have admired them; so why not let us show you how easy it is to acquire. Simple process but amazing results. Put a lens over your image.

QUALITY AND TESTING

All products and individually tested and inspected. We are an award winning team, both locally and internationally. All products are monitored and documented during every stage of production. We strive to meet your requirements.

GRAPHIC OVERLAY

We process the same materials as used for the membrane keypads but without any built in keys.

In other words we use the top graphic layer with a single adhesive backing. All the same advantages of this material are applicable, namely professional look, hard wearing, cleanable and functional.

A choice of graphic material allows for different finishes, from gloss to matt, the material being clear allows for the possibility of display components to shine through designated areas within the material itself such as LCDs or LEDs. It is also possible to print transparent colours in these areas. The material is flexible enough to cover mechanical keys and allow one to push these keys through the material without loss of feel. Cutouts for components or raised silicone keys can be accurately die or laser cut.

LABELs

Everyone knows what a label is but deciding which type of label is suitable for each application requires some understanding of the different materials. In its simplest form a label consists of printed ink on top of a base material which is backed by an adhesive plus a throw away liner.

Vinyl Labels

This type of label is cheap to produce. The material is readily available as a complete product only requiring printing on the top surface and minimum processing. The vinyl is normally white (other colours are available) or clear and comes with an adhesive backing. Different grades are available depending on product life. The disadvantage of a basic vinyl label is that the ink is exposed to fading and scratching and the vinyl itself is a “soft” material. To improve on this label it is possible as an extra process to overlaminate with a clear protective layer but this adds to the processing and material cost.

Polycarbonate Labels

Polycarbonate offers a greater variation and superior performance to that of a vinyl label. The base material is clear without adhesive. The ink is printed on the reverse side of the material, the final print being viewed through the material itself. The material being clear does not have a background colour so the background colour is printed last which offers an infinite choice of colour including matching the colour to the object that label is finally adhered to. Polycarbonate is available in different grades and finishes, the matt velvet look being the most popular, resulting in a very scratch resistant, hard wearing product. Because the printing ink has been applied behind the material it is protected by the material itself. To complete the product an adhesive layer is added before the label is cut to size. Different adhesives are available depending on the final requirement.

DOMED BADGES

Enhance your marketing impact by turning an ordinary label into something extraordinary.

The process can be compared to the affect a drop of water has on a polished surface.

We add a “drop” of clear resin to the printed material, which acts like a lens, to magnify, brighten and give depth and perspective to the flat image.

The final product, looks great, is weather resistant, cleanable and will continue to promote for many years.

We are able to manufacture in almost any shape, size or number of colours.

We are glad to dome your label for evaluation. Please feel free to send us samples.