Abstract: An automatic sliding door system suited for use in walk-in freezer or refrigerator units includes exterior and interior sensor units for opening one or more sliding doors. Each sensor unit comprises both a motion sensor and a presence detector. The motion sensor detects motion towards the sliding door(s), and opens the door(s) as they are approached. The motion sensor keeps the door(s) open so long as the motion is present. The presence detector of each sensor unit detects a change in the ambient conditions directly underneath the doorway, and keeps the door(s) open when the ambient conditions change. A brushless DC servo motor is preferably employed to move a pulley and thereby synchronously open and close the door(s). Optical sensors are deployed above the door(s) at selected deceleration and stopping points for the doors. Other features include a push plate or pushbutton, a key lock, and a multi-tier alarm system.

Abstract: An automatic sliding door system especially well suited for use in walk-in freezer or refrigerator units includes an exterior sensor unit for detecting opening conditions on the exterior of a freezer or refrigerator unit, and an interior sensor unit for detecting opening conditions in the interior of the freezer or refrigerator unit. Each sensor unit comprises both a motion sensor and a presence detector. The motion sensor detects motion towards the sliding doors, and opens the doors as they are approached. Once motion is detected, the motion sensor tracks the motion no matter whether towards or away from the door, and keep the doors open so long as the motion is present. The presence detector of each sensor unit detects a change in the ambient conditions directly underneath the doorway, and keeps the door open when the ambient conditions change. The right and left side doors that are opened and closed simultaneously and in synchronism using a pulley mechanism connected to both the right and left side doors.

Abstract: An automatic sliding door system especially well suited for use in walk-in freezer or refrigerator units includes an exterior sensor unit for detecting opening conditions on the exterior of a freezer or refrigerator unit, and an interior sensor unit for detecting opening conditions in the interior of the freezer or refrigerator unit. Each sensor unit comprises both a motion sensor and a presence detector. The motion sensor detects motion towards the sliding doors, and opens the doors as they are approached. Once motion is detected, the motion sensor tracks the motion no matter whether towards or away from the door, and keep the doors open so long as the motion is present. The presence detector of each sensor unit detects a change in the ambient conditions directly underneath the doorway, and keeps the door open when the ambient conditions change. The right and left side doors that are opened and closed simultaneously and in synchronism using a pulley mechanism connected to both the right and left side doors.