A hinge unit for hopperawning window units, the window unit comprising a fixed frame and a sash capable of rototranslation between open and closed positions. According to an embodiment of the present invention, it is determined whether or not a virtual keyboard is displayed on a display. The first light receiving region has a distinctly different structure in comparison to the second light receiving region. The destination address is associated with a client device of the client devices. The fraction of the branched off light is fixed, that is to say a measured value determined by the photocounter is proportional to the image dose. The wind turbine system includes a vibration damper, which provides a variable signal to control torque produced by a generator of the wind turbine system.