Dual Capacitor Load Cell
AssigneeNCR Corporation
InventorAlbertus Maria Geradus Claessen
Life of this patent
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Abstract
A dual capacitor load cell is presented that includes two coupled capacitors with a common plate between them where the common plate is responsive to a force applied to the load cell. The capacitance of the two capacitors varies inversely and changes in response to the applied force. The combined capacitance of each capacitor is used to determine the magnitude of the force being applied to the load cell.
Claims20
A capacitive based sensor for measuring a received force comprising:
- a first support beam and a second support beam where the first and the second support beams are horizontally spaced apart and generally parallel;
- a top capacitive plate disposed horizontally across and attached to the first support beam and the second support beam;
- a force responsive deflectable plate including a vertically deflectable main portion attached to a first side portion and a second side portion, the first side portion attached to the first support beam, the second side portion attached to the second support beam, the main portion being resiliently connected to the first and the second support beams such that the main portion is configured to move vertically in response to the received force and where the force responsive deflectable plate is located below the top capacitive plate;
- a bottom capacitive plate disposed horizontally between and attached to the first support beam and the second support beam and located below the force responsive deflectable plate;
- and
- where the top capacitive plate and the force responsive deflectable plate form a first capacitor, and the bottom capacitive plate and the force responsive deflectable plate form a second capacitor, and the capacitance of the first capacitor and the second capacitor change inversely as the result of movement of the force responsive deflectable plate.
A method for operating a capacitive based sensor for measuring a received force, the method comprising:
- receiving the force to be measured wherein the force deflects a force responsive deflectable plate that moves in response to the received force between two fixed plates and wherein the force responsive deflectable plate forms a first capacitor and a second capacitor between the two fixed plates;
- measuring the capacitance of the first capacitor and the capacitance of the second capacitor while the received force is applied to the force responsive deflectable plate;
- and
- transmitting capacitance information related to the first and second capacitors.
A weigh scale for weighing an item placed on the weigh scale, the weigh scale comprising:
- a weigh plate;
- one or more dual capacitor based load cell sensors configured so that the weigh plate is supported by and attached to the one or more sensors;
- a memory including computer instructions stored therein;
- and
- a processor in communication with each of the one or more sensors and the memory and where the processor is adapted to execute the computer instructions which when the processor executes the computer instructions cause the processor to:
- receive capacitive information from each of the one or more sensors;
- and
- determine the weight of the item using the received capacitive information.
Dependencies are inferred from the claim text.