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US 7,253,890 B2Granted
Door obstacle sensor
OwnerReza Miremadiinventor
Life of this patent
Estimating the term…
Abstract
A door obstacle sensor in which an optical transmitter and a receiver are located on the same side of an entranceway, and a retroreflector is placed on the opposite side. A controller measures the time of flight of a light beam that is reflected from the retroreflective target. All future target distances are compared to the initial distance, and a decision is made as to an object being present in or absent from the entranceway.
Claims11
An arrangement for detecting an object in a door entranceway bounded by upright walls, comprising:
- a) a transmitter supported by one of the walls for transmitting a light beam across the entranceway toward the other of the walls;
- b) a reflector supported by the other of the walls for reflecting the light beam across the entranceway toward the one of the walls;
- c) a receiver supported by the one of the walls for receiving the light beam reflected by the reflector when the object is absent from the entranceway, and for receiving light reflected by the object when the object is present in the entranceway;
- and
- d) a controller having a memory which stores a reference arrival time of the light beam at the receiver when the object is absent from the entranceway, and for measuring an obstacle arrival time of the light at the receiver when the object is present in the entranceway, and for generating a control signal indicative of object presence in the entranceway when the measured obstacle arrival time is less than the reference arrival time by a given margin,
- wherein the reference arrival time corresponds to the time for the light beam to be transmitted by the transmitter across the entranceway and received by the receiver when the object is absent from the entranceway, and
- wherein the obstacle arrival time corresponds to the time for the light beam to be transmitted by the transmitter and received by the receiver when the object is present in the entranceway.
4 more elements
A method of detecting an object in a door entranceway bounded by upright walls, comprising the steps of:
- a) supporting a transmitter by one of the walls for transmitting a light beam across the entranceway toward the other of the walls;
- b) supporting a reflector by the other of the walls for reflecting the light beam across the entranceway toward the one of the walls;
- c) supporting a receiver by the one of the walls for receiving the light beam reflected by the reflector when the object is absent from the entranceway, and receiving light reflected by the object when the object is present in the entranceway;
- and
- d) establishing a reference arrival time of the light beam at the receiver when the object is absent from the entranceway, and measuring an obstacle arrival time of the light at the receiver when the object is present in the entranceway, and generating a control signal indicative of object presence in the entranceway when the measured obstacle arrival time is less than the reference arrival time by a given margin,
- wherein the reference arrival time corresponds to the time for the light beam to be transmitted by the transmitter and received by the receiver when the object is absent from the entranceway, and
- wherein the obstacle arrival time corresponds to the time for the light beam to be transmitted by the transmitter and received by the receiver when the object is present in the entranceway.
4 more elements
Dependencies are inferred from the claim text.