Barrier operator having system for detecting attempted forced entry

Abstract

A movable barrier or garage door operator has a barrier drive for moving the movable barrier or garage door between open and closed positions. Motion of the barrier is detected by a tachometer connected to the barrier drive or by upper and lower barrier travel limit switches. A test is made to determine if the barrier has been commanded to be in a closed state and to determine if a preselected time interval has elapsed following closure of the barrier. When both of those conditions are present and the door is moved upward without authorization an alarm signal is generated and can signal the barrier drive to apply a closing force. The timer prevents the barrier from being closed on a person or obstacle during normal operation and prevents injury. An obstacle detector also prevents unwanted closure on an obstacle.

Description

BACKGROUND OF THE INVENTIONThe invention relates, in general, to barrier operators and, in particular to a garage door operator including a system for detecting when an attempt is made to force open a closed garage door.Several garage door operator systems are available on the market for maintaining a garage door either in a closed or open position. It is clear that the systems should be relatively easy to use and should be able to open the door relatively rapidly to allow quick and easy access to the garage. In addition, many systems are provided which include detectors, pressure detectors and the like that sense when the garage door is being brought down and the bottom edge of the door comes in contact with an obstacle prior to the door reaching the fully closed position. These systems are important because they prevent the garage door from closing on people, pets or small objects and, therefore, prevent personal injury and property damage. One of the drawbacks of such systems, ho...

AI Technical Summary

Benefits of technology

It is a principal object of the present invention to provide a barrier operator for opening and closing a movable barrier which includes an electronic system for detecting when forced entry is being attempted on the carrier and for preventing the barrier from being opened.

Problems solved by technology

One of the drawbacks of such systems, however, is that for some such systems, when the door has been closed, if a lifting force is applied to the door, or instance by an unwanted intruder grabbing the handle of the door and attempting to raise it by jacking the door or the like, some systems through a force measurement routine, automatically cause the door to be opened, in order to prevent what the garage door operator senses might be potential harm.

Mechanical systems may be available that in effect, jam the door closed; however, once these systems are placed in effect, if a person not knowing that the door is down and effectively mechanically locked attempts to open the door the garage door operator then attempts to lift the door against the locking mechanism and the garage door operator may be inadvertently damaged thereby or, at the very least, not open the door because it is locked.

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