Patent ID: 7883123

Claim:
An electronic push retraction exit device for latching and unlatching a door, the exit device comprising: a support rail mountable to the door; a pair of rocker levers mounted on the support rail; a push rail mounted on the pair of rocker levers and movable between an outward position and an inward position, the push rail being biased towards the outward position and movable to the inward position by manually pushing on an exterior surface of the push rail to manually unlatch and open the door; a latch bolt operably connected to the push rail and movable between a latched position and an unlatched position, the push rail being connected to move the latch bolt to the unlatched position when the push rail is moved to the inward position; a linear actuator operable in a driving state and a holding state, and an off state; the linear actuator including: a linearly movable shaft connected via a lost motion connection to the pair of rocker levers, the lost motion connection allowing the push rail to be manually moved to the inward position without moving the shaft of the linear actuator, and a stepping motor connected to linearly move the shaft when the stepping motor rotates and thereby move the push rail to the inward position to electronically unlatch the door; and a control circuit electrically connected to the stepping motor and operable to control the stepping motor in the driving state, the holding state, and the off state wherein: in the driving state, the control circuit produces and sends a series of pulses to the stepping motor to rotate the stepping motor and move the push rail towards the inward position to electronically unlatch the door; in the holding state the control circuit supplies power to the stepping motor to actively prevent rotation of the stepping motor and hold the linear actuator at a constant linear position, the control circuit preventing the push rail from returning to the biased outward position when the push rail is in the inward position; and in the off state the control circuit removes power from the stepping motor to allow rotation of the stepping motor and thereby allow the push rail to return to the biased outward position and latch the door.