Interconnection
Well protected
Hanspeter Külb reviews the changing requirements for waterproof switches, membrane keypads and steel keypads
E
ver more products are being developed for outdoor use, or having to offer a certain degree of
waterproofing for other environmental reasons. This may be because they have to be washed - as in the case of medical devices or domestic appliances for example, or because the finished appliances are exposed to extremely heavy- duty use, e.g. in production halls or in the food processing sector. This naturally affects the operating controls as well as casing components, connecting cables, plug-fit connectors and displays, etc. In the case of switches, it is becoming a matter of protecting “normal” non-sealed models with additional protective covers or a similar arrangement to prevent any penetration of moisture. This often gives rise to ergonomic and aesthetic design "breaks", as a grey rubber cap functioning as a key cover does not sit well with every refined front-panel design. This is an area in which design engineers
are increasingly turning to membrane or steel keypads to fulfil their own specific requirements. Accordingly, we are seeing an increase in the demand for sealed components for front-panel assemblies. These also provide the advantage of reducing appliance manufacturing costs as they do not require any extra outlay on additional covers or assembly time. In response knitter-switch has developed
a comprehensive standard range of toggle and pushbutton switches and pushbuttons, along with customer-specific membrane keypads, rubber switch mats and stainless-steel keypads with protection levels up to IP69K. With numerous options in terms of the colour of the operating controls and the colour, material and surface finish of switch casings, etc., integration into a specific appliance design is not a problem, with even individually-tailored solutions now possible.
For example, the DPWL-D is available in any of 5 fine metal surface finishes. Single or two-colour LEDs are also possible, likewise in a wide selection of colours. This means that it can be individually selected to fit in with the sophisticated design of its environment. The series offers protection against
30 October 2013
compatible with the often low price of the finished product, for reasons of economy. Membrane keypads are found today in
environmental influences to the standard of IP67 making it suitable for any use, from industrial and automatic machines to a simple doorbell – indeed everywhere that there is a call for a waterproof, illuminated pushbutton offering an attractive look and feel at the same time.
Medical technology
As is the case with all components used, medical technology imposes particularly high demands on the switches and keypads used in appliances. Apart from a long service life, extended temperature ranges and small construction dimensions, the requirement here is also for hygiene and therefore a high degree of waterproofing. To fulfil these requirements a range of sub-miniature, miniature or even micro- miniature switches, toggle switches, pushbutton or rotary coded switches which provide sensitive and responsive
Components in Electronics
operation and permanent protection against electrostatic discharges (ESD) up to 10 KV are available. The MTE series is waterproof to IP67 standard, and is suited for appliances which need frequent cleaning as required by hygiene regulations. The switches are mainly used in operator consoles, measuring technology and manually operated consoles for medical appliances and auxiliary medical devices.
In portable appliances such as fever thermometers, blood-pressure meters or insulin injectors, use is often made of extremely small control units. When operated by pressing, this frequently involves a tact switch for setting or changing operating modes and often a rotary switch or rotary coding switch. These applications impose specific requirements on the switch, since on the one hand they call for a very high degree of reliability, while on the other hand they have to be
many areas of application calling for protection against dirt and humidity, as well as in all fields of medical technology, and especially where the patient is actively involved in operating the equipment, such as the operating controls of a dentist's chair. They are easy to clean, can be individually designed for an attractive appearance and are even resistant to chemicals - membrane keypads represent the ideal control unit for all kinds of medical appliances. Users such as doctors and hospital personnel can easily keep their appliances clean and disinfected. Users employ switches in X-ray appliances, ultra-sound appliances, various other measuring devices, dentist's chairs, as controls for items of hospital furniture and even – in miniaturised form – for controlling portable measuring devices for blood pressure and temperature, for example. A further area of application is in domestic appliances, where design requirements are of great importance, and for professional appliances in the food processing sector, where the official regulations in terms of cleanliness and therefore washability are stringent in the extreme. There is often a requirement for hygiene in the rapidly-growing health care and fitness sector as well. Here, too, use is made of membrane keypads. Applications in extreme production
environments or automatic machines in the public sector often impose requirements beyond the level accepted as normal in the past. Here, aspects such as security for cash dispensers for example, or resistance to vandalism, also have a role to play. To remain competitive manufacturers are having to develop tailor-made solutions that can be developed in a relatively short space of time and that are able to meet the more demanding needs of their customers.
knitter-switch |
www.knitterswitch.com Hanspeter Külb is CEO of knitter-switch
www.cieonline.co.uk
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