In the past, only coupés or convertibles had frameless windows, Nowadays they can be found in other vehicles as well. One thing however is certain, the complexity and the effort required for the constructing of the winder-mechanism is much higher. They always have to be adapted to the respective requirements. Thereby, not only is the amount of available space decisive, but also the window guidance. One of the factors is the possible slanting in all directions. There have already been windows, that could only be fitted into the respective door-frames by tilting them in.
Basically, as far as the power transfer fom the electric motor to the window guidance is concerned, one distinguishes between a cable- and a lever mechanism. The cable system (see above picture) is less expensive, more frequently found and more flexible as far as the installation goes. The incoming power from the electric motor is conducted, via a gearbox, to a drum around which the cable is wound. Assuming a minimal bend-radius, the cable can now be led to the actual working area - to either one or to both of the guide rails - which are a certain distance apart.
Regardless of whether they are lever- or cable driven windows, the force, which should not be underestimated, is always supplied by an electric motor. The switching of the open or close movement occurs through polarity reversal. Decisive is the automatic-reversal feature. This allows the free movement of the window only then, when no obstacle is in the way. The motor control device registers an obstacle when either more force is required or when the movement becomes slower. Normal windows will then simply stop, those which have a more complex regulation, will reverse the direction so as to allow the assumed obstacle to be removed. So, the latter require an exact knowledge about the final positions, the former may possibly consider these points to a pinching signal.
Something new, is a fibre-optical sensor, which is built into the window frame or into the sealing rubbers, basically it's an optical-fibre, whose light-flow is reduced should pinching take place. In this case, it depends only on the deformation and not on the force. The sensor can in fact, even distinguish whether the entire length of the window or only one particular point is affected.
Like a number of suppliers, the manufacturers of power windows have also become versatile 'all-rounders'. They may possibly manufacture complete door-units including locking- and sound equipment. The advantage for the car manufacturer is that the supplier does all the testing and is responsible for the punctual delivery and the quality of the other components to be installed.