Abstract: Light grid for protecting the door edge of a motor-driven door against collision with an object, having a transmitter strip and a receiver strip with transmitter elements and receiver elements, for detecting an object in the plane of the door panels by interruption of the reception of individual receiver elements. An evaluation device distinguishes between normal and safety cases based on the detection of a status for the door, identifies the safety case if the number of uninterrupted receiving elements between door edge and object falls below a critical number, and identifies the normal case if the safety case is not identified. A communication device outputs a signal for the status. The evaluation device determines a distance value corresponding to the number of uninterrupted receiver elements below the door edge up to the first interrupted element, and the communication device varies the frequency as a function of the distance value.

Abstract: Light grid for protecting the door edge of a motor-driven door against collision with an object, having a transmitter strip and a receiver strip with transmitter elements and receiver elements, for detecting an object in the plane of the door panels by interruption of the reception of individual receiver elements. An evaluation device distinguishes between normal and safety cases based on the detection of a status for the door, identifies the safety case if the number of uninterrupted receiving elements between door edge and object falls below a critical number, and identifies the normal case if the safety case is not identified. A communication device outputs a signal for the status. The evaluation device determines a distance value corresponding to the number of uninterrupted receiver elements below the door edge up to the first interrupted element, and the communication device varies the frequency as a function of the distance value.