US 6,982,516 B2
Compensation of batch variation in the travel due to variations in the layer thickness or number of layers in multi-layer piezoelectric elements
Johannes-Jörg Rueger, Vaihingen/enz (Germany); Wolfgang Stoecklein, Stuttgart (Germany); and Bertram Sugg, Gerlingen (Germany)
Assigned to Robert Bosch GmbH, Stuttgart (Germany)
Filed on Apr. 02, 2001, as Appl. No. 9/824,193.
Claims priority of application No. 00106990 (EP), filed on Apr. 01, 2000.
Prior Publication US 2001/0050512 A1, Dec. 13, 2001
Int. Cl. H01L 41/08 (2006.01)
U.S. Cl. 310—316.01 33 Claims
OG exemplary drawing
 
1. An apparatus for charging a piezoelectric element (10, 20, 30, 40, 50 or 60), characterized in that an activation voltage and an activation charge value for driving the piezoelectric element (10, 20, 30, 40, 50 or 60) is controlled online by a control unit (D) which: (a) adjusts the activation voltage (U) and activation charge values in order to compensate for deviations caused by variations in the piezoelectric element's (10, 20, 30, 40, 50 or 60) layer thickness or the number of layers; and (b) determines the activation voltage and the activation charge value as a function of a correction factor, the correction factor measured in accordance with a manufacturing process.