Patent ID: 6966147

Claim:
An automatic pet door system comprising: (a) a rectangular frame comprising: two substantially parallel columns mounted vertically between studs of a wall, each of the columns comprising a channel disposed along the length of the column, such that openings of the channels are facing each other; a top plate disposed between top portions of the columns; a bottom plate disposed between bottom portions of the columns; wherein a lower portion of the frame defines a passage between opposite sides of the columns; (b) a door slidably movable within the channels between a lower closed position for closing the passage and an upper open position for opening the passage; (c) a drive means lifting the door between the closed and open positions, comprising: a motor disposed on one of the columns; a primary pulley mounted on the motor; a secondary pulley mounted on the top plate; a pivot pin means disposed on the door; a locking means disposed on the door, the locking means preventing movement of the door upwardly from the closed position unless the door is moved by way of the drive means; a cable having a first end fixedly attached to the primary pulley and a second end fixedly attached to the locking means, such that the cable is rising at a substantially 30 degree angle from horizontal from the primary pulley to the secondary pulley, feeding over the secondary pulley, descending at a substantially 90 degree angle from horizontal to the pivot pin means, feeding through the pivot pin means and leading, substantially horizontally, from the pivot pin means to the locking means; wherein the motor, when energized, spinning the primary pulley thereby causing the cable to pull the door up to the open position, and wherein the motor, when not energized, allowing the door to move down to the closed position by way of the force of gravity; (d) a magnetic transmitter worn by a pet, the magnetic transmitter producing a predetermined transmitter signal; (e) a detector means located proximate the frame, the detector means generating a detector signal in response to the transmitter signal when the pet approaches the frame from one side of the wall at a predetermined distance from the frame; (f) a control means electrically connected to the detector means and to the motor energizing the motor in response to the detector signal.