Patent ID: 7490786

Claim:
A shredder for shredding substrates, comprising: a housing; a shredder mechanism received in the housing and including a motor and cutter elements, the shredder mechanism enabling substrates 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 substrates fed therein; the housing having a feed opening enabling the substrates to be shredded to be fed into the cutter elements; and a stack thickness gauge defining a substrate receiving opening configured to receive an edge portion of a stack of substrates therein, the substrate receiving opening having a width less than or equal to a maximum thickness of a stack of substrates that the shredder mechanism is capable of shredding, a sensor associated with the stack thickness gauge and a controller, the sensor being communicated to the controller, the sensor being operable to detect receipt of the edge portion of the stack of substrates in the substrate receiving opening, the controller enabling activation of the motor to drive the cutter elements in the shredding direction only upon the sensor detecting receipt of the edge portion of the stack of substrates in the substrate receiving opening.