The present invention relates to barrier movement systems and particularly to methods and apparatus for detecting barrier position in such systems.
Automatic barrier movement systems are known and used today which responds to various input stimuli to open and close a barrier. Modern automatic garage door openers or gate controllers are examples of automatic barrier movement systems. Known barrier movement systems generally include an electric motor controlled by a control circuit to move the barrier in response to user interaction. In order to safely and efficiently move the barrier, sensing apparatus is desirable to identify the position of the barrier during movement and when responding to user commands to begin such movement. As a part of barrier position detection, it is also desirable to know when the barrier is closed and when it is opened as opposed to being in an intermediate position.
Open and closed limit switches may be physically placed to be contacted in the event that the barrier has reached these two positions. Alternatively, a device may be used which is connected to the motor which moves the barrier and which moves proportionally to barrier movement between open and closed positions. The actual movement of such a device may be sufficiently reduced so that it can be mounted inside a housing of the barrier movement system, somewhat removed from the barrier itself.
In accordance with the embodiments described herein a barrier position sensor includes a first potentiometer which changes an electrical resistance as the barrier moves. The first potentiometer is capable of manual adjustment when the barrier is in a first position. A voltage taken from the potentiometer can then be compared to a fixed reference to detect the presence of the door at the first position. The position sensing arrangement may also include a second potentiometer which is manually adjusted when the barrier is in a second position. By surveying voltages from the first and second potentiometers the second position of the door can be identified.
In accordance with an embodiment the barrier is first moved to a closed position and the first potentiometer is manually adjusted so that a voltage from the first potentiometer has a first predetermined relationship to a first reference voltage. The barrier may then be moved to an open position and a second potentiometer adjusted until a voltage from the second potentiometer bears a second predetermined relationship to the voltage from the first potentiometer. Thereafter a controller can identify when the barrier is in the open and closed positions by responding to the potentiometer voltage.
A potentiometer for use in the position sensing apparatus and method may include a portion frictionally coupled to a rotating member representing a position of the door. The frictional coupling is sufficient to control the potentiometer until a limit of travel of the potentiometer is reached at which event the coupling between the rotating member and the potentiometer slips. Further, the potentiometer includes a manually adjustable part so that the frictional coupling to the barrier movement can be overcome during set up and adjustments.
Controller 84 is connected to receive user generated command signals from a wall control 39 or from a user remote control (not shown) via an antenna 32 and RF receiver 80. The user generated command signals generally to initiate an action on the part of the barrier movement system. When such action is taken, the controller 84 should do so with safety, efficiency and accuracy. Several sensing arrangements are employed to assist the controller in properly responding to user commands. Block 90 of
The embodiment of
The frictional forces on sprocket 47 allow it to rotate the potentiometer shaft 49 until one of the two clockwise or counter-clockwise limits of the potentiometer is contacted. Then the sprocket will then slip in its frictional contact. In addition, shaft 49 has a slot 74 across one end so that a tool such as a screwdriver can be used to adjust the potentiometer resistance by rotating the shaft. When shaft 49 is rotated by a screwdriver, the clutch assembly slips with regard to the sprocket 47.
As the barrier is moved, shaft 49 (
During a set up procedure, during door assembly, the motor 14 is activated to move the door to the closed position. This will cause wiper to move to one of the two rotation limits of potentiometer 51, if such is within the range of door motion. In order to make certain that a limit position has been reached after the door is in the closed position, a screwdriver is inserted into slot 74 and is used to apply rotational force to shaft 49 to move the wiper to its least resistance limit position. If it is already there, no movement will occur. If it is not at the lowest limit, the operator with the screwdriver will manually rotate the shaft until the lowest limit position is achieved. Such will be signaled by the controller 84 which lights a LED on a panel such as 81 (FIG. 2) when the second signal is generated by comparator 55. After the manual adjustment of potentiometer 51 comparator 55 will generate the second signal indicating that the closed limit has been reached when the door is closed and generates the first signal when the door is in other positions.
The voltage signal from the wiper 48 of potentiometer 51 is also applied to the positive (+) input of a comparator 57. The negative (−) input of comparator 57 is connected to the wiper 76 of a second potentiometer 53. The resistance 78 of the potentiometer 53 is connected between the predetermined voltage and ground via a resistor 56. Thus, the negative input of comparator 57 receives a reference voltage from potentiometer 53. As with comparator 55, comparator 57 generates a first output signal when the negative input exceeds the positive input and it generates a second signal when the two inputs are equal. During system set up, after the potentiometer 53 is manually adjusted to represent the closed limit, the door is moved to the open position, increasing the voltage on wiper 48. When in the open position, potentiometer 53 is adjusted so that the voltage applied to comparator from potentiometers 51 and 53 are equal. Thus, causing comparator 57 to generate the second signal when the door reaches the open position.
Controller 84, which receives the output of comparator 57, responds to a transition from the first signal to the second signal by stopping the motor, when running, and lights an open LED81. After potentiometers 51 and 53 are adjusted as described above, the controller can easily identify open and closed limit positions by responding to changes in state of the comparators 55 and 57 outputs.
In the preceding embodiments two comparators are used to establish an open limit and a closed limit signal. Additional comparators may be employed in the same manner as comparator to allow the identification of one or more positions intermediate to the open limit and closed limit. Thus, each of the “intermediate” comparators would receive the voltage from wiper 48 as one input and the voltage of an adjustable reference similar to that provided by potentiometer 53 as the other input. During set up, the barrier would be stopped at an intermediate position and the equivalent of potentiometer 53 in the “intermediate” reference would be adjusted until equal to the voltage of wiper 58. Thereafter, the controller will recognize the intermediate position because of the signal state change by the “intermediate” comparator.
The preceding embodiments use physical comparators mounted on a circuit board 75 to generate state change signals. Any arrangement for detecting the equality of voltage may be employed to identify learned positions. For example, a controller 84′ (FIG. 10), which functions much the same as controller 84 of
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Number | Date | Country | |
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20040124992 A1 | Jul 2004 | US |