Systems and methods for capacitive sensing of objects

Abstract

Systems and methods for capacitive sensing of objects in a summation mode and a non-summation mode. A dual mode capacitive sensing system comprises a capacitive sensor and a processor. The capacitive sensor has a pair of adjacent conducting pads including a first conducting pad and a second conducting pad. The processor has a pair of input/output channels respectively coupled to the first and second conducting pads. The processor is configured to measure capacitance of the capacitive sensor in a summation mode and in a differential mode. A capacitive object sensing system comprises a capacitive sensor, a processor, and a plurality of objects each configured to have a unique capacitance. The processor is configured to identify one of the playing pieces based on the sensor capacitance measured when the one of the playing pieces is set on the capacitive sensor.

What is claimed is: 
     
         1 . An interactive game board system, comprising:
 a game board including a playing area surface;   a capacitive sensor with a pair of adjacent conducting pads embedded in said game board;   a processor with a pair of input/output channels, each electrically coupled to one of the pair of conducting pads, the processor with a system ground; and   wherein the processor is configured to measure capacitance of the capacitive sensor in one of a summation mode and a non-summation mode, wherein the processor configured to measure capacitance in the summation mode is configured with both of the pair of input/output channels configured for input float and wherein the processor configured to measure capacitance in the non-summation mode is configured with at least one of the pair of input/output channels set to system ground.   
     
     
         2 . The interactive game board system of  claim 1  further comprising:
 a ground plane embedded in the game board and electrically coupled to the system ground. 
 
     
     
         3 . The interactive game board system of  claim 1 , the capacitive sensor further comprising an interdigitated capacitive sensor. 
     
     
         7 . The interactive game board system of  claim 1 , wherein the conducting pads have symmetrical semi-circular shapes in a side-by-side arrangement. 
     
     
         8 . The interactive game board system of  claim 1 , wherein include the conducting pads have symmetrical rectangular shapes in a side-by-side arrangement. 
     
     
         9 . The interactive game board system of  claim 1 , wherein the conducting pads include a round pad and a circular pad surrounding the round pad and concentric therewith. 
     
     
         10 . The interactive game board system of  claim 1 ,
 further comprising a plurality of playing pieces, each of the plurality of playing pieces including an electrically conductive portion; and   wherein the processor is configured to identify one of a plurality of playing pieces based on measured capacitance when the one of the plurality of playing pieces is set on the capacitive sensor.   
     
     
         11 . The interactive game board system of  claim 10 ,
 wherein each of the plurality of playing pieces has one of a plurality of spacers coupled to a bottom of the electrically conductive portion of the playing piece; and   wherein each of the plurality of spacers is of a different thickness.   
     
     
         12 . The interactive game board system of  claim 10 , wherein the electrically conductive portion of each of the plurality of playing pieces has a different area. 
     
     
         13 . The interactive game board system of  claim 10 ,
 wherein each of the plurality of playing pieces has one of a plurality of spacers coupled to a bottom of the electrically conductive portion the playing piece; and   wherein each of the plurality of spacers has a substantially similar thickness and a different dielectric constant.   
     
     
         21 . The interactive game board system of  claim 1 , wherein the processor is configured to measure capacitance of the capacitive sensor in the summation mode by performing the steps of:
 configuring the pair of input/output channels for output and setting to system ground;   waiting until charge has dissipated from the input/output channels;   configuring the pair of input/output channels for input;   timing charging times of each of the pair of input/output channels;   computing the capacitance of each of the pair of conducing pads based on the charging time of the respective one of the pair of input/output channels; and   computing the capacitance of the capacitive sensor by summing the capacitance of each of the pair of conducting pads.   
     
     
         22 . The interactive game board system of  claim 21 , wherein the processor is configured to measure capacitance of the capacitive sensor in the non-summation mode by performing the steps of:
 configuring the pair of input/output channels for output and setting to system ground;   waiting until charge has dissipated from the input/output channels;   configuring one of the pair of input/output channels for input;   timing a charging time for the one of the pair of input/output channels configured for input; and   computing the capacitance of the capacitive sensor based on the charging time for the one of the pair of input/output channels configured for input.