DISTANCE SENSOR, ALIGNMENT SYSTEM AND METHOD
FIG3A shows a part of an embodiment of a distance sensor in more detail
FIG3A shows a first embodiment of the processing device 40. In this embodiment the processing device 40 includes a lookup table 44 that includes for each of a plurality of values hi a respective value pvi that was observed for the property indicative for the distance. The value pairs hi, pvi were obtained in an initialization mode wherein the distances hi were varied and measured with a reference distance meter. The embodiment further includes a subtraction element 41 to determine the difference pv-pvi, an absolute value determining element 42 to determine the absolute value of this difference, and an optimizer 43 to select the index i that minimizes this absolute value. Hence, in this embodiment the estimated value h for the average height h is determined as: ĥ = hj, wherein j=miniAbspv−pvi
embodiment
48
calculated in processing module
45
optimizer
40
processing device
42
absolute value determining element 3A in that elements
43
optimizer 3A in that elements
41
subtraction element
49
processing module
44
lookup table
46
interpolator
['1. A distance sensor (1) for estimating a distance to a surface (Os) of an object (O), the distance sensor including a micro electric mechanical system , MEMS, (5) comprising a MEMS device (10) having a surface (12), denoted as MEMS sensor surface, to be arranged opposite the surface (Os) of said object (O) and a MEMS driver (20) for generating an ac driving signal to cause the MEMS sensor surface to vibrate,  characterized in that  it comprises a detection means (30) to determine a value of a property of a dynamic behavior of the MEMS (5) and a processing device (40) to estimate an average distance (h) from a measurement of the dampening of the MEMS sensor surface, as a measured distance (D 2 ) between the MEMS sensor surface (12) and the surface (O s ) of the object (O) based on the determined value for said property.']