Natural climatic conditions
Humidity as a stress factor
High humidity can be caused by natural climatic conditions as well as by artificial, civilization-related situations.
High humidity caused by civilization-related situations occurs, among other things, in numerous industrial applications, in swimming pools or in canteen kitchens. The temperature determines the amount of water bound in the air. The moisture content in the air is therefore given as relative humidity. The relative humidity indicates the percentage to which the absolute humidity exhausts the maximum value.
At a certain temperature, only a limited amount can be maximally absorbed by the air in vaporous form. If the maximum amount of water for the temperature in question is reached, this corresponds to 100% relative humidity.
High humidity can cause a variety of moisture-related failure mechanisms in touch systems:
- Contact corrosion
- material-related corrosion
- Clamping corrosion cracking
- electric flashovers
- Leakage currents
- Diffusion of moisture
- Swelling / warping of materials
- Loss of strength of materials
- Loss of adhesive strength in seals
As shown, high humidity has a significant impact on the functionality of a touch system. In the course of an analysis of the possible environmental influences at the location of a touch system, the necessary attention should therefore be paid to the humidity.
Furthermore, the temperature at the place of use must be taken into account. On the one hand, because the air temperature influences the amount of water that can be bound and released in the air (condensation). On the other hand, very high or very low temperatures as well as extreme temperature fluctuations can have further effects to be taken into account on the materials and the functionality of the touch system.
Critical components in the design of a touch panel are the outer materials as well as the seals. Special environmental simulation tests to measure the effects of high humidity on a touch system are carried out specifically under the aspect of a long-term consideration over the duration of the life cycle.
In the case of touch systems that are used in the out-door area, cyclical effects caused by day and night, as well as by the different seasons, are taken into account in the tests on a site-specific basis.
