US 6,377,009 B1Granted

Capacitive closure obstruction sensor

OwnerHarald Philippinventor

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Abstract

A system for preventing the pinching or trapping of a human body part or foreign object by a closing panel, which may be a window, door, sunroof, hood or trunk lid, or other closure part of a transport vehicle operates by capacitively sensing the human body part, either before contact with a sensing electrode or plate, or at the time of contact with the plate. The sensing electrode may be a metal strip or wire, which can be embedded in a plastic or rubber molding strip, placed behind a piece of fascia or other trim part, or may simply be a metal element on top of the trim parts. Sensing electrodes of this sort can be prepared from conductive ink, made of adhesive backed metal foil, formed from a metal mesh strip, or simply be a wire or serpentine-laid wire. The capacitive sensing technology that follows the “charge transfer” approach and provides immunity from environmental effects, such as moisture and humidity.

Claims15

Dependent claims

A control system responsive to an obstruction to a panel closure, the panel adapted to be moved by a motor from an open state to a closed sate in which a leading edge of the panel is adjacent a predetermined portion of a frame, the system comprising;

a controller adapted to control the motor;
end-of-travel sensing means adapted to provide an output to the controller when the panel is in one of the open state or the closed state;
capacitive obstruction sensing means comprising a plate disposed adjacent the predetermined portion of the frame, the plate electrically coupled to an electrical ground by a shunting conductor substantially conducting electrical current pulses having durations greater than a first predetermined value, the shunting conductor substantially not conducting current pulses having durations less than a second predetermined value, the capacitive obstruction sensing means having an output to the controller, the capacitive obstruction sensing means comprising:
a source of DC current for charging the plate;
a voltage pulse source adapted to output a discharging voltage pulse having a duration less than the second predetermined value;
and
a discharging switch having an open state and a closed state, the discharging switch moving from its open to its closed state responsive to the discharging voltage pulse, the discharging switch connecting the plate to a charge measuring means when in the closed state, the discharging switch otherwise not connecting the plate to the charge measuring means;
wherein the controller is adapted to stop the motor if the output from the obstruction sensor exceeds a predetermined threshold value.

5 more elements

A control system for controlling a panel closure responsive to an object adjacent at least one of a plurality of capacitive sensing plates, the panel disposed on a vehicle having a chassis ground, the plurality of sensing plates comprising at least three plates, the system comprising:

a motor adapted to move the panel between a closed state, in which a leading edge of the panel abuts a predetermined portion of the vehicle and an open state in which the leading edge of the panel is distal therefrom;
a controller adapted to supply a plurality of control outputs to the motor;
a capacitance measurement circuit adapted to separately measure an electrical capacitance between each of the plurality of sensing plates and the chassis ground and to provide a separate output associated with each of the respective plates to the controller, the capacitance measurement circuit comprising:
a source of dc voltage;
pulse generating means for generating a plurality of charging pulses, each of the charging pulses having a subsequent discharging pulse associated therewith,
a charging switch having an open state and a closed state, the charging switch moving from its open to its closed state responsive to the charging pulse, the charging switch connecting the voltage source to the respective plate when in its closed state, the charging switch otherwise disconnecting the voltage source from the respective plate;
a discharging switch having an open state and a closed state, the discharging switch moving from its open state to its closed state responsive to the discharging pulse, the discharging switch connecting the respective plate to a charge measuring means when in its closed state, the discharging switch otherwise not connecting the respective plate to the charge measuring means;
whereby a quantity of charge representative of the capacitance of the respective plate is transferred to the charge measurement means, and whereby a change in the capacitance of the respective plate is indicative of the proximate presence of a body adjacent the respective plate;
an operator's keypad comprising two or more of the plurality of capacitive plates;
and
at least one capacitive obstruction sensing plate adjacent the predetermined portion of the vehicle.

8 more elements

A method of controlling a panel closure, in which the panel is moved by a motor and a drive mechanism from an open state in which a leading edge of the panel is distal from a frame member having a capacitive sensing plate adjacent thereto to a closed state in which the leading edge is adjacent the frame member, the method responsive to the presence of an obstruction that changes a value of capacitance measured at the sensing plate by more than a predetermined threshold amount, and wherein the obstruction does not contact the panel, the method comprising the steps of:

a) controlling the motor to move the panel from the open to the closed state when no obstruction is present and storing a plurality of records, each of the records comprising an instantaneous position value measured from the drive mechanism;
and the capacitance value measured from the capacitive sensing plate at the same time at which the associated position value is measured;
b) subsequently controlling the motor to move the panel from the open toward the closed state and comparing, at each of the plurality of position values, the respective stored capacitance value with a currently measured capacitance value;
c) stopping the motion of the panel if the currently measured capacitance value and the respective stored capacitance value differ by more than the threshold amount;
but otherwise moving the panel to the closed state.

2 more elements

Dependencies are inferred from the claim text.