Patent ID: 7641185

Claim:
A vacuum pick mechanism for picking sheet media items, the vacuum pick mechanism comprising: a pump; a suction cup arranged to contact a sheet media item to pick the sheet media item; a pick line connecting the pump to the suction cup; a pressure sensor arranged to measure the pressure relative to local atmospheric pressure within the pick line; a motor arranged to drive the pump; and control circuitry arranged to (i) receive pressure information indicating the pressure measured by the pressure sensor, (ii) monitor the pressure during transport of a first sheet media item, (iii) control the motor to drive the pump until a first predetermined target pressure is measured by the pressure sensor, (iv) control the pump so as to increase pressure if a pressure drop below the first predetermined target pressure is detected during transport of the first sheet media item, (v) record a leakage pattern for the first sheet media item based on pressure changes noted during handling of the first sheet media item, (vi) compute a second predetermined target pressure which is different from the first predetermined target pressure based upon the recorded leakage pattern associated with the first sheet media item, (vii) monitor the pressure during transport of a second sheet media item, (viii) control the motor to drive the pump until the second predetermined target pressure is measured by the pressure sensor, and (ix) control the pump so as to increase pressure if a pressure drop below the second predetermined target pressure is detected during transport of the second sheet media item.