Force-sensitive occupancy sensing technology
First Claim
1. A force-sensitive capacitive sensor comprising:
- a first conductive plate;
a second conductive plate that is spaced apart from the first conductive plate;
a compressible dielectric insulator positioned between the first conductive plate and the second conductive plate;
a first protective insulator;
a second protective insulator sealed to the first protective insulator to encase the first conductive plate, the second conductive plate, and the compressible dielectric insulator; and
a circuit attached via wires to the first conductive plate and the second conductive plate, the circuit being configured to;
when the force-sensitive capacitive sensor is positioned below a support surface, sense a change in capacitance between the first conductive plate and the second conductive plate caused by compression of the compressible dielectric insulator resulting from a person occupying the support surface, andtransmit output based on the sensed change in capacitance between the first conductive plate and the second conductive plate,wherein the circuit is configured to detect a binary occupancy state of the support surface based on the sensed change in capacitance between the first conductive plate and the second conductive plate and transmit the detected binary occupancy state, andwherein the circuit is configured to detect the binary occupancy state of the support surface by;
determining an average acquired signal in an unoccupied state by averaging, over a first number of samples, values of measured capacitance between the first conductive plate and the second conductive plate;
setting an activation threshold based on the average acquired signal in the unoccupied state and a value that defines an amount of signal change required for activation;
after setting the activation threshold, determining that a signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold for a pre-defined number of samples;
based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold, detecting occupancy of the support surface;
determining an average acquired signal in an occupied state by averaging, over a second number of samples, values of measured capacitance between the first conductive plate and the second conductive plate;
setting a deactivation threshold based on the average acquired signal in the occupied state and a difference between the average acquired signal in the unoccupied state and the average acquired signal in the occupied state;
after setting the deactivation threshold, determining that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold for a pre-defined number of samples; and
based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold, detecting a lack of occupancy of the support surface.
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Accused Products
Abstract
A force-sensitive capacitive sensor that includes a first conductive plate, a second conductive plate that is spaced apart from the first conductive plate, and a compressible dielectric insulator positioned between the first conductive plate and the second conductive plate. The sensor also includes a first protective insulator, a second protective insulator sealed to the first protective insulator to encase the first conductive plate, the second conductive plate, and the compressible dielectric insulator, and a circuit attached via wires to the first conductive plate and the second conductive plate. The sensor may also include electromagnetic shielding. The circuit is configured to sense a change in capacitance between the first conductive plate and the second conductive plate caused by compression of the compressible dielectric insulator resulting from a person occupying the sensor or a support surface positioned above the sensor, and transmit output based on the sensed change in capacitance.
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Citations
19 Claims
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1. A force-sensitive capacitive sensor comprising:
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a first conductive plate; a second conductive plate that is spaced apart from the first conductive plate; a compressible dielectric insulator positioned between the first conductive plate and the second conductive plate; a first protective insulator; a second protective insulator sealed to the first protective insulator to encase the first conductive plate, the second conductive plate, and the compressible dielectric insulator; and a circuit attached via wires to the first conductive plate and the second conductive plate, the circuit being configured to; when the force-sensitive capacitive sensor is positioned below a support surface, sense a change in capacitance between the first conductive plate and the second conductive plate caused by compression of the compressible dielectric insulator resulting from a person occupying the support surface, and transmit output based on the sensed change in capacitance between the first conductive plate and the second conductive plate, wherein the circuit is configured to detect a binary occupancy state of the support surface based on the sensed change in capacitance between the first conductive plate and the second conductive plate and transmit the detected binary occupancy state, and wherein the circuit is configured to detect the binary occupancy state of the support surface by; determining an average acquired signal in an unoccupied state by averaging, over a first number of samples, values of measured capacitance between the first conductive plate and the second conductive plate; setting an activation threshold based on the average acquired signal in the unoccupied state and a value that defines an amount of signal change required for activation; after setting the activation threshold, determining that a signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold for a pre-defined number of samples; based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold, detecting occupancy of the support surface; determining an average acquired signal in an occupied state by averaging, over a second number of samples, values of measured capacitance between the first conductive plate and the second conductive plate; setting a deactivation threshold based on the average acquired signal in the occupied state and a difference between the average acquired signal in the unoccupied state and the average acquired signal in the occupied state; after setting the deactivation threshold, determining that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold for a pre-defined number of samples; and based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold, detecting a lack of occupancy of the support surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method comprising:
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sensing, by a circuit of a force-sensitive capacitive sensor and based on the force-sensitive capacitive sensor being positioned below a support surface, a change in capacitance between a first conductive plate of the force-sensitive capacitive sensor and a second conductive plate force-sensitive capacitive sensor caused by compression of a compressible dielectric insulator resulting from a person occupying the support surface, the compressible dielectric insulator being positioned between the first conductive plate and the second conductive plate; detecting, by the circuit, a binary occupancy state of the support surface based on the sensed change in capacitance between the first conductive plate and the second conductive plate; and transmitting, by the circuit, the detected binary occupancy state, wherein detecting the binary occupancy state of the support surface comprises; determining an average acquired signal in an unoccupied state by averaging, over a first number of samples, values of measured capacitance between the first conductive plate and the second conductive plate; setting an activation threshold based on the average acquired signal in the unoccupied state and a value that defines an amount of signal change required for activation; after setting the activation threshold, determining that a signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold for a pre-defined number of samples; based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold, detecting occupancy of the support surface; determining an average acquired signal in an occupied state by averaging, over a second number of samples, values of measured capacitance between the first conductive plate and the second conductive plate; setting a deactivation threshold based on the average acquired signal in the occupied state and a difference between the average acquired signal in the unoccupied state and the average acquired signal in the occupied state; after setting the deactivation threshold, determining that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold for a pre-defined number of samples; and based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold, detecting a lack of occupancy of the support surface.
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19. A circuit for a force-sensitive capacitive sensor, the circuit being configured to perform operations comprising:
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sensing, based on the force-sensitive capacitive sensor being positioned below a support surface, a change in capacitance between a first conductive plate of the force-sensitive capacitive sensor and a second conductive plate force-sensitive capacitive sensor caused by compression of a compressible dielectric insulator resulting from a person occupying the support surface, the compressible dielectric insulator being positioned between the first conductive plate and the second conductive plate; detecting a binary occupancy state of the support surface based on the sensed change in capacitance between the first conductive plate and the second conductive plate; and transmitting the detected binary occupancy state, wherein detecting the binary occupancy state of the support surface comprises; determining an average acquired signal in an unoccupied state by averaging, over a first number of samples, values of measured capacitance between the first conductive plate and the second conductive plate; setting an activation threshold based on the average acquired signal in the unoccupied state and a value that defines an amount of signal change required for activation; after setting the activation threshold, determining that a signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold for a pre-defined number of samples; based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the activation threshold, detecting occupancy of the support surface; determining an average acquired signal in an occupied state by averaging, over a second number of samples, values of measured capacitance between the first conductive plate and the second conductive plate; setting a deactivation threshold based on the average acquired signal in the occupied state and a difference between the average acquired signal in the unoccupied state and the average acquired signal in the occupied state; after setting the deactivation threshold, determining that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold for a pre-defined number of samples; and based on the determination that the signal representative of measured capacitance between the first conductive plate and the second conductive plate has crossed the deactivation threshold, detecting a lack of occupancy of the support surface.
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Specification