Abstract: Movement of a movable barrier (10) such as, for example, a vertically-dropping fire door, can be controlled in an informed manner and with greater flexibility regarding the manner of movement via, in one embodiment, use of a motor (20) as a generator to resist the downward movement of the barrier. One or more dummy electrical loads (22) can be used in combination with the generator mode of operation to influence the degree of braking proffered by the motor. In various embodiments, one or more sensors (25, 26, 27) can be used to detect local and remote conditions of interest to thereby at least partially inform the barrier movement decision process. A display (90) (or displays) can serve to provide various kinds of information to authorized personnel and an operator control (120) can serve, at least under some operating circumstances, to permit a person to locally cause a closed barrier to move to at least a partially opened position.

Abstract: Methods and apparatus for sensing barrier position in a barrier movement system are disclosed. Electrical apparatus is connected to the barrier and generates a barrier position signal representative of barrier positions which may be used by a controller to detect barrier position. The electrical apparatus can be manually adjusted to reflect a first barrier position such as a closed position. Other barrier positions can be sensed by comparing the barrier position signal to other manually adjustable position signals.

Abstract: A cable tension sensing apparatus is mounted on a wall having a door opening. The jack shaft garage door operator includes a drive unit having an electric motor for driving a jack shaft mounted above a door opening. A pull-up cable drum is connected to the jack shaft and has a multi-strand steel pull-up cable that may be payed out to lower a door or wound up to raise the door. The cable tension sensing apparatus includes a cable guide to retain the cable a substantially fixed distance from the wall and a spring driven cable follower which urges against the cable extending between the drum periphery and the cable guide. An alerting switch is connected to the cable follower and sends a signal indicating loss of cable tension when the cable follower moves beyond a predetermined distance. Additionally, the movement of the cable follower moves a door blocking arrangement to a position to block movement of the door when being raised without use of the motor.

Abstract: Methods and apparatus for sensing barrier position in a barrier movement system are disclosed. Electrical apparatus is connected to the barrier and generates a barrier position signal representative of barrier positions which may be used by a controller to detect barrier position. The electrical apparatus can be manually adjusted to reflect a first barrier position such as a closed position. Other barrier positions can be sensed by comparing the barrier position signal to other manually adjustable position signals.

Abstract: A cable tension sensing apparatus is mounted on a wall having a door opening. The jack shaft garage door operator includes a drive unit having an electric motor for driving a jack shaft mounted above a door opening. A pull-up cable drum is connected to the jack shaft and has a multi-strand steel pull-up cable that may be payed out to lower a door or wound up to raise the door. The cable tension sensing apparatus includes a cable guide to retain the cable a substantially fixed distance from the wall and a spring driven cable follower which urges against the cable extending between the drum periphery and the cable guide. An alerting switch is connected to the cable follower and sends a signal indicating loss of cable tension when the cable follower moves beyond a predetermined distance. Additionally, the movement of the cable follower moves a door blocking arrangement to a position to block movement of the door when being raised without use of the motor.