Sirona XIOS Plus, Руководство по эксплуатации

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61 97 102 D3495
10 D3495
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201.03.07
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02 08.2011
2 Warning and safety information Sirona Dental Systems GmbH
2.2 About the physics of electrostatic charges Operating Instructions XIOS
Plus
Sensors
The content of this training is explained in the Chapter "About the physics
of electrostatic charges" [ → 10].
2.2
About the physics of electrostatic charges
About the physics of electrostatic charges
What is an electrostatic charge? An electrostatic charge is a voltage field on and in an object (e.g. a human
body) which is protected against conductance to ground potential by a
nonconductive layer (e.g. a shoe sole).
Formation of an electrostatic charge
Electrostatic charges generally build up whenever two bodies are rubbed
against each other, e.g. when walking (shoe soles against the floor) or
driving a vehicle (tires against the street pavement).
Amount of charge The amount of charge depends on several factors:
Thus the charge is higher in an environment with low air humidity than in
one with high air humidity; it is also higher with synthetic materials than
with natural materials (clothing, floor coverings).
The following rule of thumb can be applied to assess the transient
voltages resulting from an electrostatic discharge.
An electrostatic discharge is:
● perceptible at 3,000 V or higher
● audible at 5,000 V or higher (cracking, crackling)
● visible at 10,000 V or higher (arc-over)
The transient currents resulting from these discharges have a magnitude
of 10 amperes. They are not hazardous for humans because they last for
only several nanoseconds.
Background Integrated circuits (logical circuits and microprocessors) are used to
implement a wide variety of functions in dental/X-ray/CAD/CAM systems.
The circuits must be miniaturized to a very high degree in order to include
as many functions as possible on these chips. This leads to structure
thicknesses as low as a few ten thousandths of a millimeter.
It is obvious that integrated circuits which are connected to plugs leading
outside of the unit via cables are sensitive to electrostatic discharge.
Even voltages which are imperceptible to the user can cause breakdown
of the structures, thus leading to a discharge current which melts the chip
in the affected areas. Damage to individual integrated circuits may cause
malfunction or failure of the system.
NOTICE
Electrostatic discharge must be preceded by electrostatic charging.