Asymmetric Optical Sensor for Automatic Door Obstacle Detection
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Solution Overview
Problem
Automatic door installations using optical sensors are prone to false obstacle detection due to cross-talk and low light intensity issues, particularly when light is received along direct or indirect pathways not involving reflections from obstacles in the detection zone.
Innovation Solution
The automatic door installation employs a configuration of transmitter-receiver pairs with inclined axes and staggered mounting on doors, ensuring that the beam and field of view overlap to define detection zones, minimizing non-reflecting pathways and optimizing light intensity and sensitivity, thereby reducing false obstacle detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proximity sensors use low light intensity thresholds to detect obstacles in remote zones, then detection sensitivity is improved, but false obstacle detection increases due to cross-talk between transmitters and receivers
Solution Approach 1:
The transmitter and receiver are positioned asymmetrically relative to each other, with the receiver offset from the direct line of sight of the transmitter. This asymmetric arrangement ensures that the receiver cannot directly receive transmitted light, eliminating cross-talk while maintaining the ability to detect reflected light from obstacles in the detection zone
Solution Approach 2:
The detection system transitions from direct optical transmission to reflected optical transmission by introducing an intermediate obstacle surface. The light path is extended into a third dimension through reflection, allowing the receiver to detect obstacles indirectly while avoiding direct receiver-transmitter communication that causes false detections
2Use of energy by moving object
If transmitters and receivers are positioned directly opposite each other to maximize beam reception, then signal strength is improved, but direct light pathways cause false obstacle detection
Solution Approach 1:
The receiver is positioned at an angle relative to the transmitter rather than directly opposite, creating an asymmetric configuration. This ensures that while the receiver can detect reflected light from obstacles, it cannot directly receive the transmitted beam, thereby eliminating false detections caused by direct light pathways
Solution Approach 2:
The system converts the potentially harmful direct light pathway into a beneficial reflected light pathway. By positioning the receiver to reject direct light, the system ensures that only light reflected from actual obstacles reaches the receiver, turning the challenge of direct light interference into a feature that enhances detection accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the accuracy of obstacle detection by maintaining consistent light intensity and reducing cross-talk, leading to fewer false detections and improved reliability in door operation.
Implementation Method 1
a transmitter for transmitting an optical beam and a receiver for receiving the optical beam along a reflected pathway
Data Source
AI summary
There is disclosed an automatic door installation 100 configured to determine the presence of an obstacle 150 in one or more detection zones remote from a door opening, comprising: at least a first door 104 slidable in a door opening along a horizontal door axis from an open configuration to a closed configuration during a door closing operation; a plurality of transmitter-receiver pairs, each transmitter-receiver pair comprising: a transmitter 116 for transmitting a beam 140 and a receiver 118 for receiving a reflection of the beam, wherein one of the transmitter 116 and the receiver 118 is coupled to the first door so that, in use, the transmitter and receiver move closer together during the door closing operation; wherein the transmitter 116 defines a transmitter axis 120 corresponding to the optical axis of the beam; wherein the receiver 118 has a field of view 142 for receiving the beam, which is oriented around a receiver axis; and wherein the transmitter axis 120 and the receiver axis 122 are configured so that the beam and the field of view overlap to define a detection zone for the transmitter-receiver pair in at least one operational configuration of the door installation. At least one of the transmitter axis 120 and the receiver axis 122 is inclined with respect to the horizontal plane and the transmitter 116 is vertically spaced apart from the receiver 118.