Modern computers are being increasingly manufactured in the form of so-called tablet computers—also known in a simplified manner in technical circles as “tablets”. Such a tablet comprises a portable computer with flat geometry which has a touch-sensitive display configured in the form of a touchscreen. The display of the tablet is used at the same time as an input unit, which makes the provision of a keypad or a mouse superfluous. The latest generation of tablets resembles the modern smartphone in terms of their specification.
As a result of their simple handling, tablet computers are also being increasingly used in explosion-prone areas such as, for example, oil drilling platforms or similar as a working device. For any electronic device which are used in such explosion-prone areas, inter alia requirements defined in the DIN standard EN 60079-0 apply with regard to the absolutely necessary mechanical strength of the device. However, the displays of conventional commercially available tablet PCs specifically do not meet the minimum requirements specified in this standard. Furthermore, the temperatures on the surface of the display which are achieved by the display due to faults and which can reach values up to 200° C. prove to be problematical during operation of tablet displays in explosion-prone areas. At such high temperatures however, there is the risk that a gas-air mixture present in the explosion-prone area will be ignited and explode.
One possibility for increasing the mechanical strength of the display of a tablet now consists in applying an additional transparent glass pane having high glass hardness to the surface thereof, whereby an improvement in the mechanical strength of the display can be achieved. However, the detection of a touching of the display by the user, which is absolutely essential in a touchscreen, proves problematical in connection with such an additional glass pane. In conventional tablets this is typically accomplished by means of surface-capacitive signal detection. If an additional glass pane is not applied to the actual display, there is the risk that the required signal coupling between the user when he touches the display or the glass pane applied thereon, and the electronic device is no longer ensured with sufficient accuracy. Another critical aspect when using an additional glass pane is the removal of the waste heat generated by the display.