Patent ID: 7823815

Claim:
A shredder comprising: a shredder housing having a throat for receiving at least one article to be shredded therethrough; a shredder mechanism received in the housing, the shredder mechanism including a motor and cutter elements, the shredder mechanism enabling the at least one article to be shredded to be fed into the cutter elements and the motor being operable to drive the cutter elements in a shredding direction so that the cutter elements shred the at least one article fed therein into particles; a sensor for emitting and detecting radiation, the sensor being selected from one of the group consisting of (a) a throat sensor operable to detect insertion of the at least one article into the throat based on interruption of the radiation by the at least one article, and (b) a waste level sensor operable to detect an accumulation of shredded particles discharged by the shredder mechanism based on an interruption of the radiation on the accumulated shredded particles; a controller coupled to the sensor and the shredder mechanism, the controller being operable to control an operation of the shredder mechanism upon detection by the sensor, and the controller being configured to perform an automatic calibration wherein an intensity of the radiation emitted by the sensor is adjusted to or within a predetermined amount above a minimum threshold detection level when no article or shredded particles is/are present to interrupt the radiation of the sensor.