Vehicle door proximity detector system

Claim 2

In a system providing a load transporting vehicle having a door, door-operating means connected for opening and closing said door, and a proximity detector connected to said door and to said door-operating means for selectively modifying the operation of said door, said detector comprising: a capacitance means including a sensing means secured to said door and responsive to the presence of load adjacent to the edge of said door; a transformer means having an input winding means including circuit means connected with said capacitance means to form a pair of parallel connected electrical paths for supplying first and second signals, each of said paths including a different portion of said capacitance means and a different portion of said transformer means; a source of periodic voltage electrically connected to said circuit means for energizing said parallel paths; said transformer means having an output winding means coupled to the different portions of said input winding means for establishing an output including a pair of oppositely polarized signals and varying according to the variance between said first and second signals in said pair of parallel paths, and a control circuit connected to said output winding means and to said dooroperating means for selectively modifying the operation of said door in response to the sensed presence of load adjacent to the edge of said door.

Claim 3

The system of claim 1, wherein said detector includes a variable impedance means connected to said capacitance means and to said source and including a common adjustable output means to provide a pair of adjustable, inversely proportional Impedance in said parallel paths and in parallel with the different portions of said capacitance means.

Claim 4

In an elevator system, a structure having a hoistway provided with a landing and an elevator car disposed for movement in the hoistway from a position displaced from the landing to a predetermined position adjacent the landing to serve the landing for transporting load, said car having a door, door-operating means for opening and closing said door, a proximity detector connected to said door and to said door-operating means for selectively modifying the operation of said door in response to the sensed presence of load within the closing path of said door, said detector comprising: first and second antennae mounted along the edge of said door to be responsive to the presence of load in proximity thereto, a first input winding of a first transformer electrically connected in series to said first antenna and to an electrical ground by the capacitive coupling between said first antenna and said structure to form a first branch circuit, a second input winding of a second transformer electrically connected in series to said second antenna and to an electrical ground by the capacitive coupling between said second antenna and said structure to form a second branch circuit, said first and second branch circuits electrically connected in parallel, a source of periodic voltage connected to said first and second branch circuits, said first and second output transformers including first and second output windings, respectively, said output windings connected in series electrical opposition and providing an output in response to a change in impedance to ground of one antenna with respect to the other due to the proximity of load to such antenna, and a control circuit connected to said output and to said door-operating means for selectively modifying the operation of said door.

Claim 5

In an elevator system, a structure having a hoistway provided with a landing and an elevator car disposed for movement in the hoistway from a position displaced from the landing to a predetermined position adjacent the landing to serve the landing for transporting load, said car having a door, door-operating means for opening and closing said door, a proximity detector connected to said door and to said door-operating means for selectively modifying the operation of said door in response to the sensed presence of load within the closing path of said door, said detector comprising: first and second antennae mounted along the edge of said door to be responsive to the presence of load in proximity thereto, a first input winding of a first transformer electrically connected in series to said first antenna and to an electrical ground by the capacitive coupling between said first antenna and said structure to form a first branch circuit, a second input winding of a second transformer electrically connected in series to said second antenna and to an electrical ground by the capacitive coupling between said second antenna and said structure to form a second branch circuit, said first and second branch circuits electrically connected in parallel, a source of periodic voltage connected to said first and second branch circuits, said first and second output transformers including first and second output windings, respectively, said output windings connected in series electrical opposition and providing an output in response to a change in impedance to ground of one antenna with respect to the other due to the proximity of load to such antenna, and a control circuit connected to said output and to said door-operating means for selectively modifying the operation of said door.

Claim 6

The system of claim 3, and including a shunting circuit having a variable impedance connected to said electrical ground and to the junctures between said antennae and said input windings for providing a shunting impedance between each of said antennae and said electrical ground.

Claim 7

The system of claim 4, wherein said shunting circuit includes a resistive element electrically connected between said junctures and providing a selectively variable output tap electrically connected to said electrical ground.

Claim 8

The system of claim 4, wherein said shunting circuit includes a selectively variable capacitive element electrically connected between said junctures and said electrical ground.

Claim 9

The system of claim 3, and including a selectively variable capacitive element electrically connected in parallel to said first input winding.

Claim 10

The system of claim 3, wherein said control circuit includes an operational amplifier electrically connected to said output of said output transformers for providing an alternating output signal, a conversion circuit connected to said operational amplifier for providing a constant output voltage having a magnitude varying in accordance with the varying magnitude of said alternating output signal, an electrical comparator circuit having a first input electrically connected to said conversion circuit and a second input connected to a voltage source supplying a preset voltage, said comparator circuit providing an output signal when said output voltage from said conversion circuit supplied to said first input attains the preset voltage level supplied to said second input, and a switching circuit connected to receive said output signal from said comparator circuit for supplying a control signal to said door-operating means for modifying the opening and closing of said door.

Claim 11

The system of claim 8, wherein said control circuit further includes a de-activating circuit selectively electrically connected to said first input of said comparator in response to said door attaining a preselected position to prevent said switching circuit from modifyIng the operation of said door.

Claim 12

The system of claim 9, wherein said de-activating circuit includes means for preventing said output voltage supplied by said conversion circuit from attaining the preset voltage level supplied to said second input of said comparator circuit.

Claim 13

The system of claim 9, wherein said de-activating circuit further includes a pair of contacts controlled by the positioning of said door for selectively electrically connecting said first input of said comparator to a preselected voltage constituting the system electrical ground.

Claim 14

The system of claim 8, wherein said switching circuit includes a controlled rectifier having an input gate electrically connected to receive the output of said comparator, and a control relay electrically connected to the output of said controlled rectifier.