Patent ID: 8444072

Claim:
A thickness detecting system for a paper shredder, comprising: the paper shredder comprises a feed opening protection system comprising: an upper cover having an obverse side and a reverse side, the upper cover having a paper feed opening there through; a plate having a topside and a bottomside, wherein the bottomside of the plate is disposed proximate to the obverse side of the upper cover, and wherein the plate is selectively positioned to one of fully cover and fully uncover the paper feed opening; a touch structure configured to mechanically respond to contact therewith; and a preferential power supply switch configured to preferentially control a power supply for performing a shredder protection in response to the touch structure mechanically responding; wherein the upper cover is configured with one of the touch structure or the preferential power supply switch, and the plate is configured with the other of the touch structure or the preferential power supply switch, and wherein the touch structure and the preferential power supply switch are configured to engagingly interact to control the paper power supply; a first sensor positioned in a throat of the paper shredder and configured to output a signal when shredding material is inserted into the throat; a lever arm extending into the throat, the lever arm configured to rotate about an axis responsive to contact with shredding media; a spring coupled to the lever arm and configured to provide resistance to the lever arm's rotation; a removable counterweight coupled to the lever arm and configured to dampen the lever arm's rotation; a second sensor configured to output a signal when the lever arm rotates to a first position, a third sensor configured to output a signal when the lever arm rotates to a second position; and circuitry coupled to the first sensor, second sensor, and third sensor and configured to control operation of a motor coupled to cutting blades in the shredder; wherein the circuitry is configured to prevent activation of the motor and then reverse the motor responsive to receiving a signal from the second sensor prior to operation of the motor; and wherein the circuitry is configured to stop and then reverse the motor responsive to receiving a signal from the third sensor during operation of the motor.