The invention relates to an oil scraper ring for pistons of internal combustion engines, said oil scraper ring comprising a disc provided with a bearing surface having an asymmetrical crowned form with a vertex line extending over the periphery of the disc. Various embodiments are contemplated, such as, without limitation, methods that print darkened modules having four light corners, three light corners, two light corners, one light corner, andor one light edge. The active area defined by the switchable cells includes at least a first switchable region having a first transconductance and a second switchable region having a second transconductance which is different from the first transconductance. The method comprises receiving a request for a power ramp, making preparations for the power ramp, determining that the power ramp has been completed, and resuming normal operation in response to the determination. The first horizontal airflow path induces a second horizontal airflow, which moves around the housing along a line substantially parallel to the diagonal.