Drapery actuator

Claim 2

In an actuator for opening and closing closure members: motive means for moving a said closure member between predetermined limits of travel; means for detecting a predetermined limit of travel condition of said closure member; and circuit means responsive to said detection for reversing said motive means for a short period of time compared with the time of closure operating movement between limits of travel, for relieving the force applied to said closure member by said motive means.

Claim 3

The actuator according to claim 1 wherein a limit of travel condition is detected by detection of force exerted relative to said closure member.

Claim 4

The actuator according to claim 1 including a pull cord through which said motive means drives said closure member, and wherein said means for detecting said limit of travel condition comprises means for detecting a predetermined tension in said pull cord.

Claim 5

In an actuator for opening and closing closure members: a pull cord for moving such closure members; a reversible electric means for driving said cord; first switch means movable in response to tension in said cord between a first condition for actuating the reversible electric means in one direction and a second condition for actuating said reversible electric means in a second direction; control switch means for energizing said first switch means for actuating said electric means only in a selected one of said directions for bringing about unilateral movement of said closure member; and further means for additionally energizing said first switch means for a limited period of time immediately following movement of said first switch means, for causing said electric means to reverse direction temporarily and relieve tension on said pull cord.

Claim 6

In an actuator for opening and closing closure members: a pull cord for moving such closure members; a reversible electric means for driving said cord; first switch means movable in response to tension in said cord between a first condition for actuating the reversible electric means in one direction and a second condition for actuating said reversible electric means in a second direction; control switch means for energizing said first switch means for actuating said electric means only in a selected one of said directions for bringing about unilateral movement of said closure member; and further means for additionally energizing said first switch means for a limited period of time immediately following movement of said first switch means, for causing said electric means to reverse direction temporarily and relieve tension on said pull cord.

Claim 7

The actuator according to claim 4 wherein said further means comprises an electric time constant circuit for bringing about energization of said reversible electric means substantially for a time proportional to the duration of discharge of such time constant circuit, and contacts on said first switch means through which said electric means is actuated in said reverse direction for said limited period of time.

Claim 8

The actuator according to claim 5 wherein said further means additionally includes a relay operated by said time constant circuit and through which said reversible electric means is energized for said limited period of time.

Claim 9

The actuator according to claim 5 wherein said further means additionally includes a semiconductor device activated by said time constant means and through which said reversible electric means is energized for said limited period of time.

Claim 10

The actuator according to claim 5 including circuit means for charging said time constant circuit during energization of said reversible electric means by said first switch means in a selected direction.

Claim 11

The actuator according to claim 4 wherein said control switch means is provided with first and second contacts for selecting first and second directions for said reversible electric means and wherein said further means is disposed in shunt relation with nonselected contacts of said control switch means for energizing said reversible electric means in said reverse direction for said limited period of time through additional contacts provided on said first switch means.

Claim 12

In an actuator for opening and closing closure members: reversible motor means including a gear reduction drive for moving a said closure member; a control switch for said motor means, said control switch having forward and reverse contacts; limit switch for detecting limit conditions of said closure member and having contacts operable in combination with contacts of said control switch for reversing said motor from a given direction to a reverse direction when a limit condition is reached and when said control switch is also operated to direct reverse movement of said closure member; and a circuit responsive to actuation of said limit switch for limited energization of said motor means in said reverse direction through further contacts of said limit switch before said control switch is also operated, said circuit including time constant means setting such limited energization of said motor means to a predetermined period of time.

Claim 13

In an actuator for opening and closing closure members: reversible motor means including a gear reduction drive for moving a said closure member; a control switch for said motor means, said control switch having forward and reverse contacts; limit switch for detecting limit conditions of said closure member and having contacts operable in combination with contacts of said control switch for reversing said motor from a given direction to a reverse direction when a limit condition is reached and when said control switch is also operated to direct reverse movement of said closure member; and a circuit responsive to actuation of said limit switch for limited energization of said motor means in said reverse direction through further contacts of said limit switch before said control switch is also operated, said circuit including time constant means setting such limited energization of said motor means to a predetermined period of time.

Claim 14

The actuator according to claim 10 wherein said time constant means comprises a capacitor-resistor discharge circuit, and means for charging said capacitor during operation of said motor means in said given direction.

Claim 15

The actuator according to claim 10 wherein said circuit includes a relay operated by said time constant means for completing a connection through a said further contact of said limit switch for energizing said motor means.

Claim 16

The actuator according to claim 10 wherein said circuit includes a silicon-controlled rectifier having its gate coupled to said time constant means for causing said silicon-controlled rectifier to complete a connection through a said further contact of said limit switch for energizing said motor means.

Claim 17

The actuator according to claim 10 wherein said circuit includes a transistor having a control terminal thereof coupled to said time constant means for causing said transistor to complete a connection through a said further contact of said limit switch for energizing said motor means.