In order to make an appropriate choice
when it comes to operating systems, all important ambient factors associated
with the particular device must be taken into account. Important factors
include location, climatic requirements as well as the function to be
triggered.
"Vandal-proof input systems"
have now spread to the most diverse areas of application. These operating
elements are chosen for their robust nature and, increasingly, for design
reasons, too. The range of products for such input systems is just as diverse as
the application areas they are deployed in. There are piezo switches, metal
switches with stroke, metal switches with tactility and switches based on
sensor technology such as capacitive technology. Within this classification, a
combination of the various technologies is also possible.
When it comes to considering
logistics, a differentiation must be made between devices that are used
exclusively inside buildings, those that are located outside but with a
covering and those that are outside with total exposure to the elements.
Devices which are located outside with total exposure need, in most cases, to
be able to withstand snow and ice and thus minus temperatures. Piezo switches
with a completely sealed surface lend themselves particularly well to meeting
the demands of devices located outside with no protective covering.
When it comes to protecting the device
against dust and liquids, the components are specified according to IP
protection classes. Piezo switches fulfill a protection class of at least IP67.
Metal switches with stroke or tactility on the other hand are designed with
varying protection classes of between IP40 and IP67. In the case of metal
switches, a differentiation is made between the IP protection at the mechanical
level and that at the electrical contact level.
When mounting on horizontal or slightly
inclined surfaces, a hazard is posed, for example, by unintentionally spilled
liquids entering the inside of the switch. If the liquid is a sugar-containing
substance such as lemonade or sweetened coffee, the function will become
increasingly impaired. The liquid evaporates and the sugar which remains leads
to the switch becoming stiff, possibly leading to jamming of the actuator. In order
to avoid such impairment, a vertical mounting position should be chosen insofar
as the device design permits this. Alternatively, the use of a piezo switch is
recommended here, too.
The function which the switch should
activate is also decisive when it comes to selecting the type of switch
required. Frequently, the switches are arranged next to a display and the menu
navigation is controlled via the display. An additional possibility for
operator guidance is to provide the switch surface with an inscription, either
using text or appropriate symbols. Each time the switch is activated, the
device operator should receive feedback that the activation of the switch has
been acknowledged by the machine.
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