Abstract:
A method and system for determining the presence and identity of a game piece placed at a sensing location by attaching one or more conductive rings at fixed concentric locations on the bottom of the game piece and sensing the presence or absence of the conductive rings by means of sensors that are insensitive to the rotational orientation of the game piece.

Description:
This application is a continuation of and claims priority to co-pending Nonprovisional application Ser. No. 12/485,010, filed 15 Jun. 2009, which in turn claims priority to U.S. Provisional Patent Application Ser. No. 61/132620, “Interactive Game System Incorporating Capacitive Sensing and Identification” filed Jun. 20, 2008, U.S. Provisional Patent Application Ser. No. 61/132330, “Method and System for Capacitive Sensing Using a Dual-Mode Interdigitated Sensor” filed Jun. 16, 2008, U.S. Provisional Patent Application Ser. No. 61/132235, “Game System Incorporating Capacitive Sensing” filed Jun. 16, 2008, U.S. Provisional Patent Application Ser. No. 61/132237, “Method and System for Encoding Data, and for Reading Encoded Data” filed Jun. 16, 2009, and U.S. Provisional Patent Application Ser. No. 61/132238, “Method and System for Identifying a Game Piece” filed Jun. 16, 2008, each of which is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the use of multiple sensing structures to sense coded indicia on an object. 
     BACKGROUND 
     Games involving electrical and electronic components are becoming commonplace. Many traditional board games can be realized in electronic form, with some of the features of the game implemented by electronic circuitry rather than by human action. A useful feature for such games is the detection of the position and identity of a game piece upon the game board. For example, U.S. Pat. No. 5,129,654 by Bogner describes an electronic game apparatus where the presence and identity of game pieces is detected by two intersecting series of transmission lines, which transmit different frequencies that excite resonant circuits held within each game piece, the circuit for each piece having a distinct resonant frequency which uniquely identifies the game piece. Similarly, U.S. Pat. No. 5,853,327 by Gilboa describes a system in which each game piece contains a transponder which is responsive to an electromagnetic query signal, and a plurality of sensors that respond to answer signals generated by a game piece and thereby determine the location and identity of a game piece. In still another example from the prior art, U.S. Pat. No. 6,168,158 by Bulsink describes a system that incorporates resonance coils within each game piece such that the electrical and magnetic properties of each resonance coil is indicative of the type of game piece, and a game board equipped with a series of transmit and receive coils such that each playing square has a unique pair of transmit and receive coils under it. In each of these systems, the presence of a game piece of a particular identity at a particular position can be used to control the behavior of the game. 
     In the above systems described in the prior art, each game piece in a game must be equipped with complex circuitry that responds to outside stimuli, and the game board must be equipped with a plurality of sensors and a complex driving and sensing control circuit to accomplish the task of identifying the location and identity of a piece. These factors make such systems too expensive for simple board games, and therefore limit their practicality. 
     Simpler systems have been described for determining the identity of an article by sensing indicia on the article. For example, U.S. Pat. No. 4,355,300 by Weber describes a system in which a series of sensing elements reads conductive indicia in fixed positions upon a substrate, each sensing position signaling the presence or absence of an indicium and the resulting binary bits forming a complete code value. The system of Weber has the advantage of being simple and inexpensive, but requires that the object to be identified be placed at a particular location and in a particular orientation to facilitate the identification. These latter requirements are impractical in a children&#39;s game, where object placement is often haphazard, and object orientation may not be readily apparent. 
     The teachings of each of the above-listed citations (which do not incorporate essential material by reference) are herein incorporated by reference. None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention. 
     What is required is a system that utilizes simple indicia on a game piece in conjunction with a simple sensing circuit to determine the location and identity of the game piece within the playing area of a game. 
     SUMMARY AND ADVANTAGES 
     A method and system for encoding identifying indicia on a game piece and unambiguously determining the identity of a game piece placed upon a sensing location, regardless of the rotational orientation of the game piece on the sensing location. 
     In one embodiment of the invention, the indicia are rings of conductive material of fixed width and of a plurality of diameters emplaced concentrically on the bottom of a game piece, the number and diameter of the rings being representative of a code identifying the type of the game piece, said indicia being sensed by capacitive sensors arranged in corresponding concentric regions within a circular sensing area, whereby the response of the sensors to the presence of the conductive rings is independent of the rotational orientation of the game piece. 
     In an alternative embodiment of the invention, the indicia are rings of conductive material of a plurality of widths and of a plurality of diameters emplaced concentrically on the bottom of a game piece, the number, width, and diameter of the rings being representative of a code identifying the type of the game piece, said indicia being sensed by capacitive sensors arranged in corresponding concentric regions within a circular sensing area, whereby the response of the sensors to the conductive rings is dependent on the presence and width of a ring but is independent of the rotational orientation of the game piece. 
     Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. Further benefits and advantages of the embodiments of the invention will become apparent from consideration of the following detailed description given with reference to the accompanying drawings, which specify and show preferred embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the detailed description, serve to explain the principles and implementations of the invention. 
         FIG. 1  depicts a system embodying the features of this invention. 
         FIG. 2  shows an exemplary method of constructing a sensor for use with this invention. 
         FIG. 3  shows a game piece configured for use with this invention. 
         FIG. 4  depicts the relationship between a game piece and a sensor in the inventive system. 
         FIG. 5  shows a plan view of the relationship between a sensor and indicia in the inventive system. 
         FIG. 6  shows a flowchart describing an exemplary procedure for reading a set of sensors and deriving a decoded numerical value. 
         FIG. 7  shows an alternative embodiment using multiple indicia widths. 
     
    
    
     DETAILED DESCRIPTION 
     Before beginning a detailed description of the subject invention, mention of the following is in order. When appropriate, like reference materials and characters are used to designate identical, corresponding, or similar components in differing figure drawings. The figure drawings associated with this disclosure typically are not drawn with dimensional accuracy to scale, i.e., such drawings have been drafted with a focus on clarity of viewing and understanding rather than dimensional accuracy. 
     In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer&#39;s specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure. 
       FIG. 1 . depicts the component parts of an exemplary system  100  for reading an encoded value using the method of the current invention. A sensor assembly  110  is connected to a processor  150 , which also connects to a program memory  160  and a data memory  170 . The sensor assembly  110  comprises a multiplicity of sensor elements including a conductive reference element  120  which is preferentially a half disk, and a plurality of conductive sensor elements  130 ,  140  which are preferentially arcuate segments disposed so that the axis of half-disk sensor element  120  is coincident with the axis of arcuate segments  130 ,  140 . Each of the elements  120 ,  130 ,  140  of sensor assembly  110  is electrically connected to processor  150 . Under control of program instructions stored in program memory  160 , processor  150  reads sensors elements  130 ,  140  in sequence, in each case reading the capacitance between the sensor element and the reference element  120 . Processor  150  converts the sensor readings, using calibration data stored in data memory  140 , into an identity value that is reported to an external device through communication channel  150 . One skilled in the art will recognize that program memory  160  and data memory  170  can be any type of memory including solid state, optical, magnetic, or other memory means; furthermore, program memory  160  and data memory  170  could be logical divisions of physical memory locating within a single memory system. In the exemplary system two sensor elements are depicted, however, three or more sensor elements may be included in sensor assembly  110  to allow decoding of a greater number of combinations of indicia. 
       FIG. 2  shows in perspective view the assembly of the components of a sensor assembly onto a non-conductive substrate  200 . Within a circular raised ring  210  on the substrate  200 , the conductive reference element  120  and conductive sensor elements  130 ,  140  are disposed so that the axes of reference element  120  and sensor elements  130 ,  140  are coincident with the axis of circular raised ring  210 . A non-conductive shield  220  is placed over the elements  120 ,  130 ,  140 , within the raised ring  210 . For clarity, the electrical connections of elements  120 ,  130 ,  140  are not shown. 
       FIG. 3  depicts an exemplary game piece for use with system  100 . The game piece  300 , depicted in an inverted position, comprises a non-conductive body  310  with a flat bottom surface  320  upon which are arranged conductive indicia in a multiplicity of fixed positions  330 ,  340 . Indicia may be emplaced at some or all of the multiplicity of fixed positions  330 ,  340 , whereby the number and placement of the indicia uniquely encodes the identity of the game piece. 
       FIG. 4  shows in greater detail the relationship between game piece  300  and sensor assembly  110  when determining the presence and identify of game piece  300  by the inventive method. Game piece  300  is placed by a player within ring  210 , which confines it position over the location of sensor assembly  110 . Indicia at locations  330 ,  340  are thereby brought into proximity with reference element  120  and sensor elements  130 ,  140 , with a fixed spacing between indicia  330 ,  340  and elements  120 ,  130 ,  140  maintained by non-conductive shield  220 . The relationship between indicia locations  330 ,  340  and sensor elements  120 ,  130 ,  140  is shown schematically in  FIG. 5 , which shows a schematic plan view of these elements to depict their spatial relationship. A conductive indicium at position  330  spans the gap between conductive reference element  120  and conductive sensor element  130 , thereby modifying the capacitance measured between reference element  120  and sensor element  130 ; similarly, a conductive indicium at location  140  spans the gap between reference element  120  and sensor element  140 , thereby modifying the capacitance measured between reference element  120  and sensor element  140 . The presence or absence of indicia at locations  330 ,  340  will determine the capacitance measured by processor  150  when determining the identity of game piece  300 . Because of the circular symmetry of indicia at locations  330 ,  340  and the positional relationship between indicia locations  330 ,  340  and sensor elements  120 ,  130 ,  140 , the measured capacitance for each sensor element is independent of the rotation orientation of game piece  300 . 
     While the embodiment portrayed in  FIG. 4  uses a raised ring to confine the position of the game piece, alternative methods of positioning the game piece relative to the sensor may be employed. For example, the sensor assembly  110  may be emplaced in a circular depression in substrate  200 , or a series of pins or posts might be substituted for raised ring  210 , or magnets might be incorporated into substrate  200  underlying sensor  210  and into game piece  300 . Any of these or other alternative methods could be employed to ensure that game piece  300  is disposed coaxially with sensor assembly  110  when determining the presence and identity of the game piece, without departing from the spirit and intention of the invention. 
     Processor  150  can measure the capacitance of the various sensor elements  130 ,  140 , without requiring additional external switching circuitry, thereby reducing the complexity of system  100 . 
       FIG. 6  depicts an exemplary procedure  400  by which the identity of a game piece is determined. At a first step  410  the identity value is set to 0, and measurement starts at the first sensor. At a further step  420 , the sensor is read. At a further step  430 , the sensor reading is converted to a number, either 0 indicating the absence of an indicium at this sensor position, or 1 indicating the presence of an indicium at this position. The conversion at step  430  is made using calibration tables stored in data memory  170 . At a further step  440  the number derived at step  430  is added to the identity value. At a further step  450  a test is made to determine if more sensors remain to be read. If more sensors remain to be read, at a further step  460  the identity value is multiplied by two. At a further step  470 , the next sensor is selected, and processing continues at step  420 . When all sensors have been read, at a further step  480  the identity value is output, signaling the identity of the game piece. Preferentially a game piece will have at least one indicium emplaced on the bottom surface, so that executing step  430 , processor  150  will measure a 1 value for at least one sensor, thereby minimizing the chance of a false determination of the presence of a game piece. Thus, for a sensor assembly  110  with N sensor elements, the number of unique codes that can be differentiated is (2 raised to the N-th power) minus 1. 
       FIG. 7  depicts an alternative embodiment of the inventive system in which indicia of multiple sizes are used at fixed locations  330 ,  340  to encode the identity of a game piece. In the left panel, indicia of a first width  500 ,  501  are emplaced over the sensor elements  120 ,  130 ,  140 . In the right panel, an indicium of a different width  502  is emplaced over sensor element  130 . In this alternative embodiment, the identity of the game piece is determined by detecting both the presence and character of indicia. The use of indicia of multiple sizes allows for the differentiation of a greater number of unique codes, thereby reducing the number of sensor elements to differentiate among a fixed number of unique game pieces. 
     It will be apparent to one skilled in the art that the foregoing description of exemplary implementations is intended only to provide examples of the use of the invention, and is not a limitation upon the possible uses of the invention. Other similar embodiments could be designed or modified to utilize the features of this description without departing from the spirit and intention of this invention. 
     Those skilled in the art will recognize that numerous modifications and changes may be made to the preferred embodiment without departing from the scope of the claimed invention. It will, of course, be understood that modifications of the invention, in its various aspects, will be apparent to those skilled in the art, some being apparent only after study, others being matters of routine mechanical, chemical and electronic design. No single feature, function or property of the preferred embodiment is essential. Other embodiments are possible, their specific designs depending upon the particular application. As such, the scope of the invention should not be limited by the particular embodiments herein described but should be defined only by the appended claims and equivalents thereof.