Anti-entrapment system
An anti-entrapment system for preventing an object from being entrapped by a translating device such as a vehicle window includes a capacitance sensor and a controller. The sensor has a jacket with a cavity, a dielectric element within the cavity, and first and second electrical conductors. The conductors are within the cavity on opposite sides of the dielectric element such that the conductors are separated from one another by a separation distance. The capacitance of the sensor changes in response to an electrically conductive object moving in proximity to at least one of the conductors. The controller is configured to control a translating device as a function of the capacitance of the sensor. The jacket is attachable to a seal configured to receive the translating device.
1. A sensor device comprising:
a capacitance sensor, wherein a capacitance of the capacitance sensor changes in response to a conductive object coming into proximity of the capacitance sensor; and
a plurality of charge storing capacitors;
a controller including a micro-controller configured to:
closing a first switch to develop an electrical charge in the sensor by placing a known voltage from a voltage source across conductors of the capacitance sensor;
opening the first switch to isolate the capacitance sensor from the voltage source;
closing a second switch to instigate a charge transfer between the capacitance sensor and at least one charge storing capacitor of the charge storing capacitors, wherein the transferred charge from the capacitance sensor is indicative of the capacitance of the capacitance sensor;
opening the second switch to isolate the at least one charge storing capacitor from the sensor;
determine the capacitance of the capacitance sensor based on the transferred charge;
wherein the controller is operable to select a number of the plurality of charge storing capacitors for the charge transfer with the capacitance sensor to reach a target capacitance value of the plurality of charge storing capacitors; and
wherein the selected number of the plurality of charge storing capacitors corresponds to a sensitivity of the device.
2. The device of claim 1 , wherein the controller is configured to:
perform a sequential charge transfer by instigating a plurality of charge transfers to cause a collective charge on the at least one charge storing capacitor, and
determine the capacitance of the capacitance sensor based on the collective charge.
3. The device of claim 2 , wherein the controller is operable to adjust a number of charge transfers made in the sequential charge transfer.
4. The device of claim 2 , wherein the controller is operable to select a number of charge transfers in the sequential charge transfer to select a sensitivity of the controller when determining the capacitance of the capacitance sensor.
5. The device of claim 2 , wherein the controller controls at least one aspect of the sequential charge transfer for controlling a sensitivity of the capacitance sensor.
6. The device of claim 1 , wherein
the transferred charge corresponds to a signal indicative of the capacitance of the capacitance sensor,
the controller is configured to interpret the signal, and
the controller is operable to perform a level shift on the signal to reduce a DC component of the signal.
7. The device of claim 6 , wherein
the controller amplifies the signal having the reduced DC component to provide a conditioned signal, and
the controller is configured to determine the capacitance of the capacitance sensor based on the conditioned signal.
8. The device of claim 1 , wherein the controller is operable to select at least one of the plurality of charge storing capacitors for the charge transfer with the capacitance sensor.
9. The device of claim 1 , wherein the controller is operable to control at least one of a translating device or a motor based on the determined capacitance of the capacitance sensor.
10. A sensor device comprising:
a capacitance sensor, wherein a capacitance of the capacitance sensor changes in response to a conductive object coming into proximity of the capacitance sensor;
a plurality of charge storing capacitors; and
a controller including a micro-controller configured to:
select a number of the charge storing capacitors,
closing a first switch to develop an electrical charge in the capacitance sensor by applying a known voltage from a voltage source across conductors of the capacitance sensor;
opening the first switch to isolate the capacitance sensor from the voltage source;
closing a second switch to instigate a charge transfer between the capacitance sensor and the selected number of charge storing capacitors, wherein the transferred charge from the capacitance sensor is indicative of the capacitance of the capacitance sensor;
opening the second switch to isolate the selected number of charge storing capacitors from the sensor; and
determine the capacitance of the capacitance sensor based on the transferred charge.
11. The sensor device of claim 10 , wherein the selected number of charge storing capacitors for the charge transfer corresponds to a target capacitance value of the plurality of charge storing capacitors.
12. The sensor device of claim 10 , wherein the selected number of charge storing capacitors for the charge transfer corresponds to a sensitivity of the controller.
13. A method of sensing an object using a capacitance sensor having a capacitance that changes in response to a conductive object coming into proximity of the capacitance sensor, comprising the steps of:
charging the capacitance sensor by closing a first switch with a micro-controller to develop an electrical charge in the capacitance sensor by applying a known voltage from a voltage source across conductors of the capacitance sensor;
opening the first switch with the micro-controller to isolate the capacitance sensor from the voltage source;
performing a plurality of charge transfers from the capacitance sensor to at least one charge storing capacitor by sequentially opening and closing a second switch with the micro-controller;
opening the second switch with the micro-controller to isolate the at least one charge storing capacitor from the capacitance sensor; and
determining a capacitance of the capacitance sensor based on a collective charge stored on the at least one charge storing capacitor from the plurality of charge transfers.
14. The method of claim 13 , comprising selecting a number of the charge transfers for adjusting a sensitivity of the sensor.
15. The method of claim 13 , comprising using the plurality of charge transfers for filtering noise from the determined capacitance.
16. The method of claim 13 , comprising
generating a signal based on the transferred charge from the plurality of charge transfers;
level shifting the generated signal to remove a DC component of the signal; and
amplifying the level shifted signal to produce a conditioned signal that corresponds to a magnified indication of the capacitance of the capacitance sensor.
17. The method of claim 13 , comprising controlling at least one of a translating device or a motor based on the determined capacitance.
18. The method of claim 17 , comprising stopping the at least one of the translating device or the motor based on the determined capacitance indicating the presence of an object in proximity to the capacitance sensor.