Detuning multiple radio frequency identification antenna arrangement for gaming

Abstract

A gaming table contains several antennas that are detuned from the resonant frequency of a single RFID tag. This increases the power required to read the single tag but matches the resonant frequency for reading the stack of RFID tags. The game table may further include a network analyzer and a set of capacitors that dynamically switch among the antennas in accordance with measuring reflection coefficients of the antennas.

Description

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 17 / 587,293, filed on January 28, 2022, for "De-Tuned Multiple RFID Antenna Arrangement for Gaming," which claims the benefit of U.S. Provisional Application No. 63 / 283,086, filed on November 24, 2021, for "De-Tuned Multiple RFID Antenna Arrangement for Gaming." The entire contents of these applications are incorporated herein by reference in their entirety for all purposes. Background Art

[0003] The present invention relates to gaming, and in particular to a radio frequency identification (RFID) system having an antenna arrangement for detecting the location of an RFID tag on a gaming table.

[0004] Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

[0005] Instantly tracking the location of gaming tokens at the gaming table has the potential to revolutionize the gaming industry by providing improved security. Tying this data to specific players allows casinos to create accurate player profiles while relieving table managers of mundane tasks that take years of training to hone.

[0006] Traditional RFID systems have attempted to solve the problem of the gaming market, but with little success. In a typical RFID system, the excitation antenna defines a "working volume" in which the energy projected by the antenna is sufficient to power the RFID tag. This "working volume" is usually ill-defined, with only the option of increasing / decreasing power to adjust the read range. But doing so will extend the read range in all directions, thereby introducing crosstalk errors when multiple antennas are in close proximity. There are multiple disadvantages in existing products on the market. First, the product is limited to discrete betting sites. Secondly, the product is limited in terms of the stacking height of game tokens that can be read. Third, the product has poor discrimination between adjacent betting sites. Fourth, the product has a read error higher than an acceptable read error. Fifth, the product has a slow read rate, which makes it miss important events (e.g., the placement and removal of game tokens, etc.).

[0007] These shortcomings limit the available technology to games where the betting sites are far apart (e.g., a single "pot"), to detecting only the initial bet, and to identifying counterfeit tokens only when they are used at the table (not during the game process).

[0008] U.S. Application Publication No. 2013 / 0233923 discusses a ferrite core technology. Ferrite core technology overcomes many of the above disadvantages, but does not address the need to track multiple individual bets placed by different bettors on a single larger betting site (e.g., when a "back bettor" shares a betting site with a seated bettor in a traditional gaming layout). There is also a need for the ability to identify the locations of very closely spaced bets.

[0009] U.S. Application Publication No. 2017 / 0228630 discusses a solution involving two crossed antenna arrays. One horizontal antenna array provides one coordinate, and a second vertical antenna array provides a second coordinate. Then, a set of higher fidelity coordinates can be interpolated using signal strength information comparing adjacent antennas.

[0010] While the method of U.S. Application Publication No. 2017 / 0228630 works, it suffers from the simple fact that reading RFID tags takes time, and reading the tags multiple times for interpolation purposes multiplies the time required, making it impractical to capture an accurate “snapshot” of a transient event with a large number of tags in certain gaming environments.

[0011] Typical RFID systems solve the question "Who's there?" The response is a series of unique item identifiers (e.g., serial numbers). As discussed above, the ferrite core technology discussed in U.S. Application Publication No. 2013 / 0233923 is directed to solving the additional question "Where are you?" as a way to track individual bets.

[0012] U.S. Application Publication No. 2016 / 0217645 discusses the use of a network analyzer device prior to RFID reading, whereby the RFID reader can be directed only to those antennas where tags are present. This describes a sequential approach that eliminates the "overhead" of using an RFID reader to find tags when no tags are present, because using a network analyzer device takes less time than using an RFID reader.

[0013] U.S. Application Publication No. 2013 / 0233923 and U.S. Application Publication No. 2016 / 0217645 both relate to placing bets in a specific area (betting site). An RFID tag not placed in one of the defined areas will not be correctly read. None of these disclosures address the need to detect bets placed anywhere on a larger defined area. The additional disclosures of U.S. Application Publication No. 2017 / 0228630 address placing multiple bets in a larger defined area. However, the system disclosed therein relates to multiple RFID reads to define the coordinates of each bet, which is a time-consuming process.

[0014] U.S. Application Publication Nos. 2013 / 0233923, 2016 / 0217645, and 2017 / 0228630 all describe systems for identifying and locating RFID tags by using signal strength information as measured by an RFID reader to determine proximity to a particular antenna. U.S. Application Publication No. 2013 / 0233923 describes a system that increases the signal strength at the appropriate antenna, which further improves accuracy.

[0015] U.S. Application Publication No. 2021 / 0011107 discusses various antenna arrangements for gaming. Summary of the invention

[0016] One problem with existing systems is that specific gaming tables have specific betting areas of varying sizes, which makes reading the RFID tags in each area a challenge.An antenna arrangement that works well for a specific gaming table is needed.

[0017] In view of the above, embodiments are directed to improving detection of RFID tags on a gaming table.

[0018] According to an embodiment, a system determines the location of an object in a gaming environment. The system includes: a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; and an RFID reader coupled to the RFID antennas. The antennas are impedance matched to a stack of RFID tags at a first impedance matching value, wherein the first impedance matching value is different from a second impedance matching value used to impedance match the antenna to a single RFID tag. The first impedance matching value produces a less efficient impedance match than the second impedance matching value between the single RFID tag and the antenna.

[0019] The system may further include one or more reactance tuning components coupling the antenna to the RFID reader, wherein the one or more reactance tuning components are selected from capacitors and inductors. The antenna is impedance matched to the RFID tag stack by adjusting the reactance of the one or more reactance tuning components.

[0020] Each of the antennas may be impedance matched to the RFID tag stack according to a corresponding type of each of the plurality of antennas, wherein the type includes size, shape, and configuration. The type of antenna may include a point antenna type, a line antenna type, and a cross antenna type.

[0021] According to an embodiment, a method determines a location of an object in a gaming environment. The method includes providing a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table. The method further includes providing an RFID reader coupled to the plurality of RFID antennas. The antenna is impedance matched to a stack of RFID tags at a first impedance matching value, wherein the first impedance matching value is different from a second impedance matching value for impedance matching the antenna to a single RFID tag. The first impedance matching value produces an impedance match that is less efficient than the second impedance matching value between the single RFID tag and the antenna.

[0022] The following detailed description and accompanying drawings provide a further understanding of the nature and advantages of embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a block diagram of an RFID system 200 .

[0024] Figure 2 is a graph 300 of a Smith chart of an antenna tuned for a single RFID tag.

[0025] Figure 3 is a graph 400 of a Smith chart of an antenna tuned for a stack of 20 RFID tags.

[0026] Figure 4 is a flow chart of a method 500 of determining a position of an object in a gaming environment.

[0027] Figure 5 is a block diagram of an RFID system 600 .

[0028] Figure 6 is a block diagram of an RFID system 700 implementing a dynamic tuning system.

[0029] Figure 7 is a top view of antenna arrangement 800 covering the area above the gaming table.

[0030] Figure 8 is a top view of antenna arrangement 900 covering the area above the gaming table.

[0031] Fig. 9 is a top view of antenna arrangement 1000 covering the area above the gaming table.

[0032] Fig.10 is a block diagram of an RFID system 1100 .

[0033] Fig.11 is a flow chart of a method 1200 of determining a position of an object in a game environment.

[0034] Fig.12 is a block diagram of an RFID system 1300 . DETAILED DESCRIPTION

[0035] Techniques for position determination of RFID tags are described herein. In the following description, for the purpose of explanation, numerous examples and specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention as defined by the claims may include some or all of the features in these examples alone or in combination with other features described below, and may further include modifications and equivalents of the features and concepts described herein.

[0036] In the following description, various methods, processes, and procedures are described in detail. Although certain steps may be described in a particular order, this order is primarily for convenience and clarity. Certain steps may be repeated more than once, may occur before or after other steps (even if those steps are otherwise described in another order), and may occur in parallel with other steps. It is only necessary for a first step to follow a second step if the second step must be completed before the first step can be started. When this is not clear from the context, this will be specifically noted.

[0037] In this document, the terms "and", "or", and "and / or" are used. Such terms should not be interpreted as having an inclusive meaning. For example, "A and B" may mean at least the following: "both A and B", "at least both A and B". As another example, "A or B" may mean at least the following: "at least A", "at least B", "both A and B", "at least both A and B". As another example, "A and / or B" may mean at least the following: "A and B", "A or B". When an exclusive or is intended, this will be specifically indicated (e.g., "A or B", "at most one of A and B").

[0038] In this document, the terms "RFID tag", "RFID game tag", "RFID token", "RFID game token", "token" and "game token" are used. Such terms should be interpreted as broadly synonymous. (More precisely, "RFID token" can be used to refer to an integrated circuit component of an "RFID tag", which also includes additional components such as an antenna, a rigid housing, etc. However, this document is primarily concerned with the broad use of these terms.) RFID tags typically respond to radio frequency signals from an RFID reader with their serial number or other identifiers, thereby enabling the RFID reader to obtain an inventory of nearby RFID tags. In a gaming environment, RFID game tags can be placed on a gaming table as a bet, removed from a gaming table, or moved around a gaming table according to various game rules. RFID game tags can be tagged with identifiers.

[0039] RFID Tags

[0040] Generally, RFID tags are tuned to a specific resonant frequency, such as 13.56 MHz. The conventional solution is to configure the RFID tag with a high, narrow Q at the resonant frequency in order to reduce the amount of power that must be output by the RFID reader in order to generate a response by the RFID tag. In contrast to this conventional solution, U.S. Application Publication No. 2013 / 0233923 describes the use of a ferrite core and components that tune an RFID tag to a frequency higher than 13.56 MHz. Any coupling by a neighboring RFID tag shifts its resonant frequency lower and therefore closer to 13.56 MHz, thereby increasing the power received from the RFID reader. In summary, U.S. Application Publication No. 2013 / 0233923 describes tuning the Q of an RFID tag.

[0041] The following sections describe several features that improve the detection of RFID tags on a gaming table. First, the Antenna Tuning section and the Dynamic Antenna Tuning section (Sections 1 and 2 below) describe tuning the excitation tag of an RFID reader to further increase the read range as defined by the height of the stack of RFID tags placed on the antenna. Note that these sections differ from the tuning described in U.S. Application Publication No. 2013 / 0233923 in that the sections are directed to tuning antennas in RFID readers, not antennas in RFID tags.

[0042] Second, the Rapid Scanning of Antennas section (Section 3 below) describes the use of antenna reflection coefficient S11 for antennas having a larger area than described in previous disclosures such as U.S. Application Publication No. 2016 / 0217645.

[0043] Third, the Instrumented Winning section (Section 4 below) describes features for improving transitions between game states in a game.

[0044] 1. Antenna tuning

[0045] Figure 1 2 is a block diagram of an RFID system 200. The RFID system 200 may be implemented in a gaming table. The RFID system 200 includes a controller 202, an RFID reader 204, a multiplexer 206, and a plurality of antennas 208.

[0046] The controller 202 generally controls the operation of the RFID system 200. The controller 202 controls the RFID reader 204 to generate a read command and receives an RFID tag identifier from the RFID reader 204 in response to the read command. The controller 202 controls the multiplexer 206 to connect to a selected one of the antennas 208. The controller 202 includes a tag database that associates RFID tag identifiers with token values. The controller 202 may also implement other functions, such as calculating and displaying token values ​​corresponding to detected RFID tag identifiers, tracking game status, generating alerts, etc., as described throughout this document. The controller 202 may be implemented by a computer or other device including a processor, such as a personal computer.

[0047] RFID reader 204 generates a read command by outputting a carrier wave at a given frequency; any RFID tag receiving power responds with its tag identifier by modulating the carrier wave. RFID tags may respond according to an anti-collision process. RFID tags may also respond to an acknowledgement command from RFID reader 204, causing a given tag to stop responding until the next read cycle.

[0048] Multiplexer 206 connects RFID reader 204 to a selected one of antennas 208. Multiplexer 206 may be implemented using a radio frequency switch. In response to a command from controller 202, multiplexer 206 connects the selected antenna 208 to RFID reader 204. This enables multiple antennas to be associated with one RFID reader. RFID reader 204 is then selectively connected to antenna 208 in a time-sharing manner.

[0049] Antenna 208 is typically associated with an area on the gaming table. Additionally, gaming bets may be placed on lines and intersections between multiple numbered sites, and antennas may be associated with these lines and intersections. Since these betting sites, lines, and intersections have different sizes and shapes, the size and shape of antenna 208 may also vary, as discussed in subsequent paragraphs.

[0050] As a specific example of a gaming table, the RFID system 200 includes 200 or more antennas 208 feeding a single RFID reader 204 on multiple printed circuit boards. An embodiment with multiple readers and multiplexers (e.g., one reader and one multiplexer per circuit board) may also be implemented, where the controller 202 coordinates the multiple RFID readers and multiplexers. With an average of 5 milliseconds for an RFID reader 204 to perform a read, if no tags are present, this arrangement causes the RFID reader 204 to take 1 second to read all 200 antennas in its associated group antenna 208; reading a tag takes approximately 7 milliseconds, so if there are 50 tags, the total read time is 1.35 seconds (5 milliseconds*200+7 milliseconds*50). The number of RFID readers 204, the number of multiplexers 206, and the number of antennas 208 may be adjusted as desired.

[0051] Using RFID tags with ferrite cores (eg, as described in U.S. Application Publication No. 2013 / 0233923), the RFID tags are very tightly coupled and multiple tags can be detuned from proper antenna matching.

[0052] Contrary to what would be expected in a conventional RFID system (e.g., where the antenna is tuned to the resonant frequency of the RFID tag), the RFID system 200 is somewhat counter-intuitive because the antenna 208 is not tuned to the typical resonant frequency of the RFID tag. Instead, the antenna 208 is detuned in a manner that is customized so that the resulting frequency shift that occurs when multiple tags are present is moved in the direction of optimal tuning, while still maintaining the necessary sensitivity when only a small number of RFID tags are present in the RF excitation field. In this way, any reduction in signal strength from tokens added to the top of the stack at the betting site (due to distance from the excitation antenna) is offset by increased sensitivity as the resonance shift approaches ideal.

[0053] Careful measurement of coupling as a function of the number of tokens in the stack allows each of the antennas 208 to be configured with tuning to maximize the sensitivity of the antenna (and thereby maximize the height of the token stack that can be read for a given power level).

[0054] To get the highest field strength, it is desirable to have a high Q. The trade-off is that high-Q circuits are prone to detuning - and placing multiple tokens in the excitation field will cause this detuning. Therefore, in the case of a high-Q antenna, tuning for a high stack height is optimal. Tuning for a high stack height (rather than for a single token) can produce a 7dB signal improvement at the top of the stack (where the excitation field is weakest). Therefore, the system performance limit is set by the token on the top of the stack.

[0055] Figure 2300 is a Smith chart of an antenna tuned for a single RFID tag. Scaling is omitted, and the antenna is tuned to 50 ohms. Chart 300 includes 4 data points corresponding to the reflection coefficient S11 measured for various numbers of RFID tags arranged as a stack on the antenna. Point 302 corresponds to 1 tag, point 304 corresponds to 5 tags, point 306 corresponds to 10 tags, and point 308 corresponds to 20 tags. Since the antenna is tuned for 1 tag, point 302 is located near the center of the figure, indicating a close impedance match to 50 ohms. Points 304, 306, and 308 are always at the right edge, indicating a large impedance mismatch that occurs when only a few more tags are added to the stack. Due to the impedance mismatch, a higher power level is required to perform the read. Therefore, tuning the antenna for a single tag severely limits the sensitivity (e.g., the ability to read a larger number of tags) at a given power level.

[0056] Figure 3 4 is a graph 400 of a Smith chart of an antenna tuned for a stack of 20 RFID tags. Scaling is omitted, and the antenna is tuned to 50 ohms. Graph 400 includes 4 data points corresponding to the reflection coefficient S11 measured for various numbers of RFID tags arranged in a stack on the antenna. Point 402 corresponds to 1 tag, point 404 corresponds to 5 tags, point 406 corresponds to 10 tags, and point 408 corresponds to 20 tags. Since the antenna is tuned for 20 tags, point 408 is located in the center of the graph, indicating a close impedance match. Points 402, 404, and 406 are offset a little from the center, but not as much as the center. Figure 2 is as far offset as in Figure 2 It is important to note that although the impedance matching degrades when fewer tokens are present, it needs to be smaller than Figure 2 The mismatch has less power and can therefore still be read despite the mismatch.

[0057] Table 1 shows the comparison of tuning between 1 tag and 30 tags with a 4-turn loop antenna of 30 mm diameter.

[0058]

[0059] Table 1

[0060] In Table 1, the "Tuning" column indicates the two options being compared, i.e., 1 tag versus 30 tags. The "Reactance" column indicates the corresponding reactance of the reactive components that are coupled to the antenna in order to perform impedance matching for the indicated number of tags. Here, the reactive components are series capacitors (e.g., capacitors in a series connection between the RFID reader and the antenna) and shunt capacitors (e.g., capacitors in a shunt connection between the RFID reader and the antenna). The specific reactance of the reactive components coupled to the antenna can be determined by measurement during system configuration, as discussed further below. Based on whether the antenna is tuned for 1 tag or 30 tags, the "When Reading 1 Tag" column indicates the impedance and power required to read 1 tag. Based on whether the antenna is tuned for 1 tag or 30 tags, the "When Reading 30 Tags" column indicates the impedance and power required to read 30 tags.

[0061] As can be seen, when the antenna is tuned for 1 tag, the selected capacitance value produces an impedance of 52+j3 ohms, which is a good impedance match to the 50 ohm impedance of the RFID reader. Therefore, only 0.5 mW is required to perform a read. However, when a stack of 30 tags is placed on this antenna, the impedance changes significantly to 5-j9 ohms, and due to the impedance mismatch with the RFID reader, 603 mW of power is required to read all 30 tokens.

[0062] By comparison, when the antenna is tuned for 30 tags, the selected capacitance values ​​produce an impedance of 48+j2 ohms, which is a good impedance match to the 50 ohm impedance of the RFID reader. Therefore, only 115 mW of power is required to perform a read, which is a 7.2 dB improvement in efficiency (compared to 603 mW for the other tunings). Admittedly, tuning the antenna in this way does require 3 times more power to read a single token, but at only 1.55 mW this inefficiency is very acceptable.

[0063] In other words, by tuning the antenna to match the impedance of the RFID tag stack, the minimum power required is increased (e.g., 0.5 mW to 1.55 mW) and the maximum power required is reduced (e.g., 603 mW to 115 mW). Although the power efficiency is reduced by a small amount (e.g., about 1 mW) when reading a single tag, the power efficiency is improved by a larger amount (e.g., about 490 mW) when reading a larger number of tags. Thus, the overall power efficiency of the system is improved.

[0064] Table 2 shows the various antenna types that can be used on a gaming table.

[0065] Betting Area Size(mm) shape Configuration Turn Main number location 47×70 rectangle Loop 3 Horizontal Line 29×70 rectangle Loop 3 Cross 28×28 rectangle Loop 5 Vertical Lines 28x 47 rectangle Loop 4 List 70×90 rectangle Double figure 8 2

[0066] Table 2

[0067] In Table 2, each antenna type is associated with a betting area and has a size, shape, configuration, and number of turns.

[0068] The "Betting Area" column indicates the type of betting area on the gaming table. The "Size" column indicates the size of the antenna. The "Shape" column indicates the shape of the antenna. The "Configuration" indicates whether the antenna is configured as a loop or a figure 8. A figure 8 antenna has two loops with the antenna wire crossing in the middle between the loops; thus, the field in one loop has a 180 degree phase shift from the field in the other loop. A double figure 8 antenna has two figure 8 antennas offset so that the second figure 8 covers the null zone between the two loops of the first figure 8 antenna. The "Turns" column indicates the number of turns the antenna has. A single turn of a circular antenna can be seen as the antenna wire turns 360 degrees, two turns correspond to 720 degrees, three turns correspond to 1080 degrees, four turns correspond to 1440 degrees, and so on. All of these parameters affect the value of the reactive components coupled to each antenna for impedance matching.

[0069] More generally, the antenna types of Table 2 can be classified into three general types: point, line and cross type. Point type covers an area usually, for example, corresponding to a given bet site. Line type covers the border between two bet areas usually, for example, corresponding to bets on both of those numbers. Cross type covers the intersection between four bet areas usually, for example, corresponding to bets on all four numbers in those numbers. The quantity, its arrangement and size of the bet site can be adjusted as needed, wherein the size, shape, configuration and number of turns of the associated antenna are adjusted accordingly.

[0070] Once the antenna type has been selected, the reactance circuit of each antenna can be configured to match the impedance of the tag stack. For example, as discussed above with reference to Table 1, when tuned to an impedance match for 30 tags, the corresponding reactance circuit includes a series capacitor at 194 pF and a shunt capacitor at 226 pF. Other antennas on the gaming table can be tuned in a similar manner. For example, the impedance of a stack of 30 tags can be measured, and the reactance of the reactance circuit (e.g., one or more of a capacitor and an inductor in one or more of a series and shunt configuration) can be adjusted until a reasonable match is achieved. A network analyzer device can be used to perform impedance matching, for example, by measuring the reflection coefficient and adjusting the reactance in response to the measurement.

[0071] Table 3 provides an example of tuning for three of the antenna types shown in Table 2 to match a stack of 30 RFID tags.

[0072]

[0073] Table 3

[0074] In Table 3, it can be seen how the reactance value of the reactive component varies based on the type of antenna.

[0075] Figure 4 is a flow chart of a method 500 for determining the location of an object in a gaming environment. The RFID system 200 (see Figure 1 )Execute method 500 on the gaming table.

[0076] At 502, a number of radio frequency identification (RFID) antennas are provided that are arranged at a plurality of locations on a gaming table. For example, the antennas may be of the various types listed in Table 2 and may be arranged in the betting area of ​​the gaming table as discussed above.

[0077] At 504, an RFID reader coupled to the RFID antenna is provided. For example, the RFID system 200 may be integrated into a gaming table, and the RFID system 200 may include one or more RFID readers 204 coupled to the RFID antenna on the gaming table.

[0078] As discussed above, each of the antennas is impedance matched to a stack of RFID tags at a first impedance match value, wherein the first impedance match value is different from a second impedance match value used to impedance match the antenna to a single RFID tag. For example, Table 1 shows that due to the configuration of the reactive element, the first impedance match value is 48+j2 ohms and the second impedance match value is 52+j3 ohms. Thus, the first impedance match value produces an impedance match that is less efficient than the second impedance match value between the single RFID tag and the antenna. For example, Table 1 shows that when the reactive component is configured to match for tuning 30 tags, the required power is 1.55 mW, which is greater than the 0.5 mW required when the reactive tuning component is configured to match for tuning 1 tag.

[0079] At 506, a given antenna of the plurality of antennas is selectively connected to an RFID reader. For example, the controller 202 may control one of the multiplexers 206 to selectively connect one of the RFID readers 204 to one of the antennas 208.

[0080] At 508, the given antenna is powered on with the RFID reader, wherein powering on the given antenna includes reading a subset of the plurality of RFID tags. For example, the controller 202 may instruct the given RFID reader 204 to perform a read of the given antenna 208 (see 506); the controller 202 then associates the tag identifier resulting from the read with the betting site corresponding to the given antenna.

[0081] The RFID system 200 can then perform the method 500 on other of the antennas on the gaming table. In this way, the RFID system 200 can determine the amount of bets placed at various locations on the gaming table.

[0082] 2. Dynamic Antenna Tuning

[0083] The antenna tuning system described above in Section 1 works well, but is limited in sensitivity by inherent conflicts caused by fixed tuning circuits. Specifically, the antenna tuning described in Section 1 shifts the antenna match to bias for higher tag stacking, which results in increased power and inefficiencies when reading smaller numbers of tags. The RFID system described in Section 2 addresses these issues.

[0084] Figure 5 600. The RFID system 600 may be used in conjunction with the RFID system 200 described above (see Figure 1 ) is integrated into the gaming table in a manner similar to that described in . The RFID system 600 includes a controller 602, a network analyzer 604, an RFID reader 606, a reactance network 608, a multiplexer 610, and an antenna 612.

[0085] Controller 602 generally controls the operation of RFID system 600. Controller 602 sends commands to other components of RFID system 600 and receives data from other components in response to commands. Controller 602 may store an RFID tag database containing RFID tag identifiers of RFID tags in use on the gaming table. Controller 602 may manage the game state and various events of the game. Controller 602 may be implemented by a personal computer or other device including a processor. Controller 602 may be similar to controller 202 (see Figure 1 ).

[0086] The network analyzer 604 typically measures the reflection coefficient S11 of the selected one of the antennas 612. The reflection coefficient (also called reflectivity) is a parameter that describes how much of a wave is reflected due to an impedance discontinuity in the transmission medium (in this case, the selected one of the antennas 612). The reflection coefficient is the ratio of the complex amplitude of the reflected wave to the complex amplitude of the incident wave. The network analyzer 604 can measure the reflection coefficient in a manner similar to that described in U.S. Application Publication No. 2016 / 0217645.

[0087] The RFID reader 606 typically outputs a read command that includes energizing a selected one of the antennas 612 and receiving a response from the RFID tag energized by the field. The RFID reader 606 may be otherwise similar to the RFID reader 204 (see Figure 1 ).

[0088] The reactance network 608 typically includes a number of reactance elements, including capacitors, inductors, etc., that can be connected in various configurations (including in a series configuration, in a shunt configuration, etc.). The reactance network 608 responds to a command from the controller 602 to select a specific set of reactance elements and their configuration to produce a specific reactance. The reactance network 608 may include a specific element configuration, where a specific configuration is selected. For example, when there are 10 types of antennas that can be tuned to 5 different stack heights (e.g., 30, 20, 10, 5, 1), the reactance network may include 50 reactance element configurations. Alternatively, the reactance network 608 may include a first group of configurable reactance elements that can be connected in a series configuration and a second group of configurable reactance elements that can be connected in a shunt configuration. For example, the first group may include four series capacitors with sizes of 200pF, 100pF, 50pF, and 25pF; selecting one or more (or none) produces a series capacitance that can be selected from 0pF to 375pF in 25pF increments.

[0089] Multiplexer 610 selectively connects reactance network 608 to one of antennas 612 in response to commands from controller 602. Selected antenna 612 is then connected to network analyzer 604 via reactance network 608 (having a selected configuration) to measure the reflection coefficient of the selected antenna, or to RFID reader 606 to read an RFID tag near the selected antenna.

[0090] Similar to the above with respect to antenna 208 (see Figure 1 ) as described above, antennas 612 are located at various locations on the gaming table. Antennas 612 are of various types, such as those detailed in Table 2 above.

[0091] The RFID system 600 may include multiple RFID readers, multiple reactance networks, and multiple multiplexers, wherein each RFID reader is associated with one of the reactance networks, one of the multiplexers, and a set of antennas. This allows the controller 602 to control multiple RFID readers to perform read operations at overlapping times.

[0092] RFID system 600 may be used to implement a dynamic tuning system, as discussed below.

[0093] 2.1 Dynamic tuning system

[0094] When configured to implement a dynamic tuning system, the RFID system 600 generally operates as follows. The controller 602 first measures the reflection coefficient S11 of a given antenna 612 using the network analyzer 604 and then adjusts the tuning of the reactive network 608 to properly match the given antenna 612. Since the RFID system 600 dynamically tunes the given antenna 612, the RFID system can use antennas with high Q and adjust the resonant tuning to best match the operating frequency (e.g., 13.56 MHz), regardless of whether there is only one tag or multiple tags in the excitation field. The controller 602 then instructs the RFID reader 204 (selectively connected to the given antenna 612 by means of the multiplexer 610) to excite the given antenna 612 using the selected tuning to achieve optimal performance.

[0095] Alternatively, a dynamic tuning system may be implemented without a network analyzer, as described with respect to Figure 6 Described in detail.

[0096] Figure 6 RFID system 700 includes an RFID reader 702, a dual directional coupler 704, a controller 706, a series reactance network 708a, a shunt reactance network 708b, a multiplexer 710, and an antenna 712.

[0097] RFID reader 702 performs a read operation that includes energizing a selected one of antennas 712 and receiving a response from an RFID tag in the vicinity of the selected antenna. RFID reader 702 may be otherwise similar to RFID reader 204 (see Figure 1 ), RFID reader 606 (see Figure 5 )wait.

[0098] The dual directional coupler 704 taps the energy of the excitation signal and the energy of the return signal during a read operation. The dual directional coupler 704 receives the excitation energy from the RFID reader 702, provides the excitation energy to the reactance networks 708a and 708b, and provides the forward signal 705a to the controller 706. The dual directional coupler 704 receives the response from the RFID tag, provides the response to the RFID reader 702, and provides the reflected signal 705b to the controller 706.

[0099] Controller 706 receives forward signal 705a and reflected signal 705b from dual directional coupler 704 and measures the reflection coefficient based on forward signal 705a and reflected signal 705b. Based on the reflection coefficient, controller 706 controls reactance networks 708a and 708b to adjust the series reactance and shunt reactance. Controller 706 can then instruct RFID reader 702 to perform another read operation using the adjusted reactance value.

[0100] The series reactance network 708a couples the RFID reader 702 to a selected one of the antennas in a series reactance element configuration, and the shunt reactance network 708b couples the RFID reader to the selected antenna in a shunt reactance element configuration. Reactance networks 708a and 708b each include a number of reactance elements, including capacitors, inductors, etc. Reactance networks 708a and 708b may include elements with different reactance values, and controller 706 may select one or more in order to obtain the desired reactance value. For example, the series reactance network 708a may include four capacitors with values ​​of 200pF, 100pF, 50pF, and 25pF; this allows any capacitance value to be selected from 0pF to 375pF in 25pF increments. Shunt reactance network 708b may include 5 capacitors with values ​​of 400pF, 200pF, 100pF, 50pF, and 25pF; this allows any capacitance value to be selected from 0pF to 775pF in 25pF increments. Thus, reactance networks 708a and 708b may selectively provide the appropriate reactance for any of the antennas on the gaming table (e.g., see the antenna types listed in Table 2).

[0101] Multiplexer 710 couples reactance networks 708a and 708b to a selected one of antennas 712 as selected by controller 706. In this manner, selected antenna 712 is coupled to RFID reader 702 via reactance networks 708a and 708b. Multiplexer 710 may be implemented by a radio frequency switch.

[0102] Antenna 712 is associated with various locations on the gaming table. Antenna 712 can be of various types (such as those listed in Table 2) and quantities. Antenna 712 can be similar to antenna 208 (see Figure 1 )、612(See Figure 5 )wait.

[0103] Note that, with the RFID system 600 (see Figure 5 ) compared to the RFID system 700, the network analyzer is omitted. Alternatively, if the current read produces a suboptimal return signal (as determined by the controller 706 by analyzing the forward and reflected signals), the RFID system 700 may perform one or more additional reads.

[0104] 2.2 Selective Tuning Network

[0105] Alternatively, the RFID system 700 may implement a selective tuning network by replacing the reactance networks 708a and 708b with a selection of specific configurations of series and shunt reactance elements. For example, the antenna 712 may include 10 different types of antennas (e.g., the types listed in Table 2). A given antenna type has a number of matching reactance configurations corresponding to various RFID tag stacking heights. For example, a given antenna may have 5 matching reactance configurations corresponding to 5 stacking heights (e.g., 30, 20, 10, 5, 1). As a specific example of a circular 30 mm loop antenna with 4 turns (see Table 3), the tuning for a stack of 30 RFID tags is a series capacitance of 194 pF and a shunt capacitance of 226 pF. This antenna then has four other pre-configured reactance configurations corresponding to 20, 10, 5, and 1 RFID tags. Thus, for 10 antenna types and 5 stacking heights, the selective tuning network includes 50 selectable reactance element configurations. When a first RFID read operation to an antenna produces a mismatch, the controller 706 selects another one of the pre-configured reactance configurations for the antenna.

[0106] In summary, the dynamic antenna tuning of Section 2 achieves several differences from the antenna tuning of Section 1. First, dynamic antenna tuning enables the use of antennas with higher Q, which produces increased field strength (for a given power level) and enables reading of higher RFID tag stacks. Second, dynamic antenna tuning enables the use of a reactance network shared among multiple antennas, rather than each antenna having its own separate reactance configuration.

[0107] These features enable several improvements over existing systems. First, the features allow the tuning of a given antenna's resonance to be dynamically changed to match the sensitivity of the given antenna, which improves the efficiency of the system (e.g., power savings in the excitation field produced by the RFID reader). Second, the features allow the tuning of an RFID reader's resonance to be dynamically changed based on different resonances of antennas of different types (e.g., different sizes, different shapes, different numbers of turns, etc.). Third, the features allow the tuning of a given antenna to be dynamically changed as different numbers of RFID tags are placed within the magnetic field (also referred to as the H-field) produced by the given antenna when powered on.

[0108] 3. Rapid scanning of the antenna

[0109] U.S. Application Publication No. 2016 / 0217645 discusses the change of the reflection coefficient S11 of the antenna measured by a network analyzer device in the presence of different numbers of RFID tags. However, the system described in U.S. Application Publication No. 2016 / 0217645 has several problems. One problem is that the system described in U.S. Application Publication No. 2016 / 0217645 does not work well for larger antennas. This problem is problematic for games where some betting sites have larger areas. Increasing the size of the antenna does not work well because larger antennas produce reduced flux density, which reduces the change of S11, making it difficult to detect the presence of RFID tags. Table 4 gives an example of attempting to measure S11 with a larger antenna.

[0110]

[0111]

[0112] Table 4

[0113] In Table 4, the reflection coefficient S11 was measured for four tag populations using a 13x30 cm loop antenna matched to 50 ohms at an excitation frequency of 13.56 MHz. As can be seen, the measurements are very close together, making it difficult to distinguish between 0 and 3 tags.

[0114] To address these issues, Section 3 describes the use of multiple antennas to detect RFID tags distributed over a larger area. Multiple antennas are used to keep the flux density high enough to ensure measurable changes in S11. Multiple antennas can be configured as loops, overlapping loops, figure-8 antennas, overlapping figure-8 antennas, etc. Table 5 gives an example of measuring S11 with a figure-8 antenna.

[0115] Number of tags Reflection coefficient S11 0 (36.1+j6.5)Ω 1 (37.7+j4.4)Ω 2 (39.8+j0.7)Ω 3 (41.1–j6.7)Ω

[0116] Table 5

[0117] In Table 5, the reflection coefficient S11 was measured for four tag populations using a 7x24 cm figure-8 antenna matched to 50 ohms at an excitation frequency of 13.56 MHz. As can be seen, the differences among the measurements are greater than in Table 4, making it easier to distinguish between 0 and 3 tags.

[0118] The 13×30 cm area of ​​the 13×30 cm loop antenna can then be covered by multiple 7×24 cm figure-8 antennas (e.g., using 4 figure-8 antennas). This allows a network analyzer, which returns results faster than an RFID reader, to perform a quick scan to determine which antenna has a tag on it, thereby reducing the time it takes to read all of the antennas on the gaming table.

[0119] However, using multiple antennas to cover an area presents new technical challenges. Multiple antennas couple magnetically and thereby distort the resulting magnetic field from the intended magnetic field, creating unwanted constructive interference (called hot spots) and destructive interference (called nulls). If the flux density is too low, the change in reflection coefficient is undetectable when a tag is placed in a low flux area, and the fast scan feature is unusable. Section 3 discusses ways to increase flux density in large areas.

[0120] Figure 7 800 is a top view of an antenna arrangement 800 covering an area on a gaming table. The antenna arrangement 800 includes two antennas 802 and 804, which are coupled to other components (not shown) such as a network analyzer, an RFID reader, etc. via a radio frequency switch 806. The antennas 802 and 804 overlap slightly so that the field radiates over the entire area and avoids gaps in coverage. The antenna arrangement 800 also has reactive elements that may include capacitors and inductors. Here, the antenna arrangement 800 includes a capacitor 810 coupled in series to the antenna 802, a capacitor 812 coupled in series to the antenna 804, and a capacitor 814 in a shunt configuration between the network analyzer and the switch 806. The reactive elements may match the antennas 802 and 804 to 50 ohms at 13.56 MHz, which is a common radio frequency design impedance.

[0121] For antennas 802 and 804 considered by themselves in the absence of other components, there may be magnetic coupling between the antennas when the network analyzer measures the reflection coefficient. However, placing shunt capacitor 814 on the side of switch 806 opposite antennas 802 and 804 prevents a conductive loop from being formed from one antenna (e.g., 802) through the other antenna (e.g., 804) to ground. (If the shunt element is placed on the same side of the switch as the antenna, the shunt element of one antenna completes the connection to ground when the other antenna is powered, thereby creating magnetic coupling.) This placement of the reactive element on the side of the switch opposite the antenna (or alternatively, on the same side of the switch as the network analyzer) may also be referred to as inside placement.

[0122] Antenna arrangement 800 generally operates as follows. Antennas 802 and 804 cover betting sites on a gaming table, where the betting sites are sized such that using a single larger antenna will result in reduced flux density, as discussed above. First, a network analyzer selectively measures the reflection coefficients of antennas 802 and 804; when measuring antenna 802, switch 806 connects antenna 802, and antenna 804 is an open loop; when measuring antenna 804, switch 806 connects antenna 804, and antenna 802 is an open loop. When the number of tokens energized by a given antenna changes, the measured reflection coefficient changes from the previous reflection coefficient measurement of the given antenna.

[0123] Next, based on comparing the measured reflection coefficient with the previous measurement, the RFID reader selectively energizes the antennas in the antenna arrangement 800 to perform a read operation. When the reflection coefficient of neither of the antennas 802 and 804 changes, no RFID reading is required because the current tag is the same tag that was present in the previous measurement. When the reflection coefficient of one of the antennas 802 and 804 changes, the particular antenna (e.g., 802) is connected to the RFID reader via switch 806, and the other antenna (e.g., 804) is an open loop; the RFID tags near the particular antenna then respond to the read energy with their tag identifiers. When the reflection coefficients of both antennas 802 and 804 change, the switch 806 selectively connects the first antenna (e.g., 802) for the RFID reader to energize, and forms an open loop for the second antenna (e.g., 804), and then the switch 806 selectively connects the second antenna (e.g., 804) for the RFID reader to energize, and forms an open loop for the first antenna (e.g., 802).

[0124] In summary, placing one or more reactive tuning elements inside switch 806 enables coverage of a defined area using any number of antennas to be used while maintaining a desired flux density. For example, antennas may be selected from the antenna types listed in Table 2 and used to provide coverage of various sized areas on a gaming table.

[0125] Figure 8900 is a top view of an antenna arrangement 900 covering an area on a gaming table. The antenna arrangement 900 includes four antennas 902, 904, 906, and 908, which are coupled to other components (not shown) such as a network analyzer, an RFID reader, etc. via four radio frequency switches 912, 914, 916, and 918. The antennas 902, 904, 906, and 908 overlap slightly in order to radiate the field over the entire area and avoid gaps in the coverage area. The antenna arrangement 900 also has reactive elements that may include capacitors and inductors. Here, antenna arrangement 900 includes capacitor 922 coupled in series between switch 912 and antenna 902, capacitor 924 coupled in series between switch 914 and antenna 904, capacitor 926 coupled in series between switch 916 and antenna 906, and capacitor 928 coupled in series between switch 918 and antenna 908, and capacitor 930 in a shunt configuration between the network analyzer and switches 912, 914, 916, and 918. The reactive elements may match antennas 902, 904, 906, and 908 to 50 ohms at 13.56 MHz. As with antenna arrangement 800, using capacitor 930 as a shared (or common) shunt capacitor among antennas 902, 904, 906, and 908 and placing capacitor 930 between the network analyzer and switches 912, 914, 916, and 918 avoids magnetic coupling between closely placed antennas.

[0126] The antenna arrangement 900 may be similar to the antenna arrangement 800 discussed above (see Figure 7 ) method.

[0127] Fig. 9 1 is a top view of an antenna arrangement 1000 covering an area on a gaming table. Antenna arrangement 1000 includes two figure-8 antennas 1002 and 1004. Each of antennas 1002 and 1004 is in the shape of a figure-8 with two loops (1002a and 1002b and 1004a and 1004b). The loops of antennas 1002 and 1004 overlap slightly (e.g., loop 1004b overlaps loops 1002a and 1002b) so as to radiate the field over the entire area and avoid gaps in the coverage area. The figure-8 antenna exhibits a null between the two loops. This null area can be mitigated by spacing the loops so that the loop of one antenna covers the null area of ​​the other antenna. For example, loop 1004b covers the null of antenna 1002, and loop 1002b covers the null of antenna 1004. Antennas 1002 and 1004 are coupled to other components (not shown) such as a network analyzer, an RFID reader, etc. via two radio frequency switches 1012 and 1014 .

[0128] The antenna arrangement 1000 also has reactive elements that may include capacitors and inductors. Here, the antenna arrangement 1000 includes a capacitor 1022 coupled in series between the switch 1012 and the antenna 1002; a capacitor 1024 coupled in series between the switch 1014 and the antenna 1004; and a capacitor 1030 in a shunt configuration between the network analyzer and the switches 1012 and 1014. The reactive elements may match the antennas 1002 and 1004 to 50 ohms at 13.56 MHz. As with the antenna arrangements 800 and 900, using capacitor 1030 as a shared (or common) shunt capacitor among the antennas 1002 and 1004 and placing capacitor 1030 between the network analyzer and the switches 1012 and 1014 avoids magnetic coupling between the closely placed antennas.

[0129] The antenna arrangement 1000 may be similar to the antenna arrangement 800 discussed above (see Figure 7 ) or antenna arrangement 900 (see Figure 8 ) method.

[0130] Fig.10 1 is a block diagram of an RFID system 1100. The RFID system 1100 may be used in conjunction with the RFID system 200 described above (see Figure 1 ), RFID system 600 (see Figure 5 ), RFID system 700 (see Figure 6 ) etc. RFID system 1100 generally implements the fast scan feature described above, and may include other features among those described herein (e.g., Sections 1-2). RFID system 1100 includes controller 1102, network analyzer 1104, RFID reader 1106, switchable reactance network 1108, and antenna 1110.

[0131] The controller 1102 typically controls the operation of the RFID system 1100, for example, by sending control signals to the network analyzer 1104, the RFID reader 1106, and the switchable reactance network 1108, as described in detail below. The controller 1102 can be similar to the controller 202 (see Figure 1 ), controller 602 (see Figure 5 ), controller 706 (see Figure 6 ) etc. The controller 1102 may be implemented by a device including a processor (eg, a personal computer).

[0132] The network analyzer 1104 measures the reflection coefficient of a selected one of the antennas 1110. Based on the reflection coefficient, the controller 1102 determines the approximate number of RFID tags present in the excitation field of the selected antenna and performs other operations. One such operation is to configure the switchable reactance network 1108 to an appropriate reactance value that matches the impedance of the selected antenna (because the RFID tag couples with the selected antenna and changes its impedance), as described in Section 1 or Section 2. Another such operation is to control the RFID reader 1106 to perform a read operation on the selected antenna and provide a detected RFID tag identifier so that the controller 1102 can determine that a specific RFID tag is present at a specific location on the gaming table corresponding to the selected antenna. Since the network analyzer produces results faster than the RFID reader 1106, the controller 1102 can control the RFID reader 1106 to read only those antennas in the antennas 1110 where there are tags (or changes in the number of tags), which results in time savings compared to always reading all antennas in the antennas 1110.

[0133] RFID reader 1106 performs a read operation on a selected one of antennas 1110. The read operation generally includes exciting the selected antenna, reading a response of an RFID tag that responds to the excitation energy, and providing the RFID tag identifier of the responding tag to controller 1102. Because controller 1102 has configured switchable reactance network 1108 to an appropriate reactance value based on the reflection coefficient measured by network analyzer 1104, the excitation energy is impedance matched to the selected antenna, and the read operation is performed more efficiently than would otherwise occur. RFID reader 1106 may be otherwise similar to the RFID reader 204 described herein (see Figure 1 ), RFID reader 606 (see Figure 5 ), RFID reader 702 (see Figure 6 ) and other RFID readers.

[0134] The switchable reactance network 1108 typically selectively connects one of the network analyzer 1104 and the RFID reader 1106 to a selected one of the antennas 1110 having a selectable, configurable, or adjustable reactance value. The controller 1102 configures the appropriate reactance value based on the reflection coefficient measured by the network analyzer 1104. The switchable reactance network 1108 includes reactance elements such as capacitors, inductors, etc. in various series and shunt configurations. These various configurations of the reactance elements correspond to the impedance ranges desired for various types of antennas on the gaming table (e.g., see Table 2). For example, the switchable reactance network 1108 may implement antenna tuning described in Section 1, dynamic antenna tuning described in Section 2, Figures 7 to 9The specific capacitor arrangement of the antenna 1104 and the like includes a number of radio frequency switches to connect the selected antenna to the network analyzer 1104 (or the RFID reader 1106) and to connect the selected reactive element to the selected antenna.

[0135] Antenna 1110 is placed at various locations on the gaming table (e.g., the betting locations described above). Antenna 1110 has various types, for example, the types listed in Table 2. Antenna 1110 can be similar to antenna 208 (see Figure 1 ), antenna 612 (see Figure 5 ), antenna 712 (see Figure 6 ), antennas 802 and 804 (see Figure 7 ), antennas 902, 904, 906 and 908 (see Figure 8 ), antennas 1002 and 1004 (see Fig. 9 ), etc. A given area on the gaming table may be associated with a single antenna (e.g., one of the antenna types listed in Table 2) or with multiple antennas (e.g., as described above with respect to Figures 7 to 9 described).

[0136] As for the antenna arrangement 1000 (see Fig. 9 ), the controller 1102 controls the switchable reactance network 1108 (at Fig. 9 1002 and 1004. The controller 1102 controls the RFID reader 1106 via one switch configuration to power on the selected antenna to perform a read operation. The other antenna is selectively disconnected via another switch configuration to form an open loop.

[0137] The RFID system 1110 may implement other features in addition to those described above. For example, the RFID reader 1106 may implement a persistence feature with the RFID tags. For persistence, when the RFID reader 1106 receives an identifier from a particular RFID tag, the RFID reader 1106 indicates that the particular RFID tag is no longer responding during the current read operation. This allows the read cycle to no longer repeat the read even if the tag is in the overlap region of the antenna 1110. For example, the antenna loops 1002a and 1004b (see Fig. 9 ) are overlapping; RFID tags located in the overlapping area will be powered by both antennas 1002 and 1004.

[0138] As mentioned above, measuring the reflection coefficient of antenna 1110 (using network analyzer 1104) before reading an RFID tag (using RFID reader 1106) results in a time savings compared to simply reading all of the antennas in antenna 1110 using RFID reader 1106. For example, the average time for operation of network analyzer 1104 is 0.3 milliseconds and the average time for operation of RFID reader 1106 is 5 milliseconds; for a gaming table with 200 antennas, it takes 1000 milliseconds to read all of the antennas in antenna 1110 using RFID reader 1106. In contrast, measuring the reflection coefficient of all of the antennas using network analyzer 1104 takes 60 milliseconds; if controller 1102 determines that only 50 of antenna 1110 need to be read (because the other 150 antennas do not have a changed reflection coefficient), then reading the subset of antennas using RFID reader 1106 takes only 250 milliseconds. The net time is then 310 milliseconds (60+250), which is less than the 1000 milliseconds used to read all antennas in antenna 1110.

[0139] Fig.11 1 is a flow chart of a method 1200 for determining the location of an object in a gaming environment. Fig.10 )Execute method 1200 on the gaming table.

[0140] At 1202, the reflection coefficient of a selected antenna of a number of antennas is measured. The antennas are arranged at a number of locations on the gaming table. For example, the gaming table may have a number of antennas (e.g., of the type listed in Table 2) arranged to detect RFID tags at various locations on the gaming table. At least some of the antennas are closely spaced, with multiple antennas covering a single betting site, so as to fully cover the area while providing a desired flux density. The controller 1102 (see Fig.10 ) can control the network analyzer 1104 to measure the reflection coefficient of the selected antenna by configuring the connection with the selected antenna via the switchable reactance network 1108.

[0141] At 1204, the reactance associated with the selected antenna is selectively adjusted based on the measured reflection coefficient (see 1202). For example, the controller 1102 (see Fig.10) can adjust the reactance of the switchable reactance network 1108 based on the reflection coefficient of the selected antenna measured by the network analyzer 1104. If the reflection coefficient of the selected antenna has not changed from its previously measured value, then the reactance does not need to be changed (e.g., selectively adjusted to remain unchanged). Because the antennas are closely spaced, the reactance adjustment uses an inner shunt element in the switchable reactance network. For example, the switchable reactance network 1108 may include an inner shunt capacitor (e.g., on the same side of the switch as the network analyzer or on the side of the switch opposite the selected antenna), such as capacitor 814 (see Figure 7 ), capacitor 930 (see Figure 8 ), capacitor 1030 (see Fig. 9 )wait.

[0142] As another option, steps 1202-1204 may be performed more than once. For example, if the second measurement of the reflection coefficient indicates an impedance mismatch, the reactance may be further adjusted.

[0143] At 1206, when the reflection coefficient of the selected antenna has changed from a previously measured value of the selected antenna, the selected antenna is powered on, wherein powering on the selected antenna includes powering on one or more RFID tags near the selected antenna and receiving one or more RFID tag identifiers from the one or more RFID tags. For example, the RFID reader 1106 (see Fig.10 ) can energize the selected antenna via the switchable reactance network 1108 using the reactance adjusted in 1204 to read RFID tags in the vicinity of the selected antenna (e.g., RFID tags located in a particular betting location on the gaming table associated with the selected antenna). When the reflection coefficient has changed, this indicates that the RFID tags in the vicinity of the selected antenna have changed, so the RFID reader needs to perform a new read. However, when the reflection coefficient has not changed, this indicates that the RFID tags in the vicinity of the selected antenna have not changed, so the RFID reader does not need to perform a read using the selected antenna.

[0144] At 1208, the first antenna is deselected, the second antenna is selected, and steps 1202, 1204, and 1206 are performed using the second antenna.

[0145] Step 1208 may then be repeated for multiple antennas on the gaming table (eg, less than all antennas on the gaming table, as determined based on the changed reflection coefficients). For example, controller 1102 (see Fig.10) can control the RFID system 1100 to selectively read a subset of antennas 1110 having a reflection coefficient that has changed from the reflection coefficient measured in the previous read cycle. In this way, the RFID system 200 can determine the amount of bets placed at various locations on the gaming table without having to perform RFID reads on all antennas 1110.

[0146] In summary, the fast scanning feature of Section 3 achieves several improvements over existing systems. First, multiple antennas are used to provide coverage of a larger area while avoiding coupling by selectively connecting one of the antennas and selectively disconnecting the other antennas. This decoupling is performed by placing the tuning components outside the switch used for selection. Second, the use of multiple antennas over a larger area maintains a defined flux density so that the change in reflection coefficient when an RFID tag is present in the excitation field is measurable (e.g., compared to using a single larger antenna). Third, it creates time savings by using the reflection coefficient to control which antennas the RFID reader reads (e.g., less than all antennas).

[0147] 4. Instrumentation wins the bid

[0148] Chapter 4 describes the instrumented winning mark of the game state in the help management game.For each game state, the game logic is different.For example, it is allowed to place or remove bets in the public betting state rather than in the competitive state.The game also includes various events, such as bet locking events, winning number events and game over events.The event marks the transition from one game state to another game state.The instrumented winning mark described herein helps to accurately define these transitions.

[0149] In either case (automated or non-automated), a winning bet is placed on the winning number on the gaming table and is not removed until all winning bets are awarded.

[0150] The instrumented winning ticket described herein adds instrumentation to the winning ticket. Specifically, the instrumented winning ticket includes an RFID tag with a unique identifier. This RFID-enabled winning ticket can then be used to automatically detect these events and trigger the use of new game logic in subsequent game states. Specifically, the instrumented winning ticket rests in one of two locations on the gaming table: on a dedicated resting location (called "parking") or on a winning number.

[0151] Fig.12 1 is a block diagram of an RFID system 1300. The RFID system 1300 may be used in conjunction with the RFID system 200 described above (see Figure 1 ), RFID system 600 (see Figure 5 ), RFID system 700 (see Figure 6 ), RFID system 1100 (see Fig.10 ) etc. RFID system 1300 generally implements the instrumented winning features described herein, and may include other features among those described herein (e.g., Sections 1-3). RFID system 1300 includes controller 1302, RFID reader 1304, switching network 1306, antenna 1308, and instrumented winning 1310.

[0152] Controller 1302 generally controls the operation of RFID system 1300, for example, by sending control signals to RFID reader 1304 and switching network 1306, as described in detail below. Controller 1302 also manages the game state described above based on the results of detecting the position of instrumented winning bid 1310. Controller 1302 can be similar to the controller 202 described herein (see Figure 1 ), controller 602 (see Figure 5 ), controller 706 (see Figure 6 ), controller 1102 (see Fig.10 ) or other controllers. The controller 1302 may be implemented by a device including a processor, such as a personal computer.

[0153] The RFID reader 1304 performs a read operation on a selected one of the antennas 1308. The read operation generally includes energizing the selected antenna, reading a response from an RFID tag that responds to the energizing energy, and providing the RFID tag identifier of the responding tag to the controller 1302. Specifically, with respect to the instrumented winning bid 1310, the read operation reads the tag identifier of the instrumented winning bid 1310 at the selected antenna corresponding to the betting site with the winning number. The RFID reader 1304 can be otherwise similar to the RFID reader 204 (see FIG. 1 ) described herein. Figure 1 ), RFID reader 606 (see Figure 5 ), RFID reader 702 (see Figure 6 ), RFID reader 1106 (see Fig.10 ) and other RFID readers.

[0154] The switching network 1306 typically uses a plurality of switches to connect the RFID reader 1304 to a selected one of the antennas 1308. Similar to the switchable reactance network 1108 (see Fig.10 ), the switching network 1306 may also include a reactance network having a selectable, configurable, or adjustable reactance value. The switching network 1306 may otherwise be similar to the multiplexer 206 described herein (see Figure 1 ), multiplexer 610 (see Figure 5 ), multiplexer 710 (see Figure 6 ), switchable reactance network 1108 and other switching networks.

[0155] Antennas 1308 are placed at various locations on the gaming table. One of the antennas 1308 may also be associated with a parking location for an instrumented winning bid 1310. Antennas 1308 are of various types, for example, the types listed in Table 2 for use in a 3×12 grid area of ​​the gaming table. Antennas 1308 may be otherwise similar to antennas 208 (see Figure 1 ), antenna 612 (see Figure 5 ), antenna 712 (see Figure 6 ), antennas 802 and 804 (see Figure 7 ), antennas 902, 904, 906 and 908 (see Figure 8 ), antennas 1002 and 1004 (see Fig. 9 ), antenna 1110 (see Fig.10 )wait.

[0156] The instrumented winning bet 1310 contains an RFID tag with a unique tag identifier. When a read operation performed by the RFID reader 1304 returns the tag identifier of the instrumented winning bet 1310 at a selected one of the antennas 1308 (e.g., as routed via the switching network 1306 as configured by the controller 1302), the controller 1302 recognizes this as a winning number event and transitions the game state from the competition state to the settlement state. Optionally, the controller 1302 may also recognize a bet lock event when the RFID reader 1304 detects that the instrumented winning bet has been removed from the parking area.

[0157] Controller 1302 and instrumented winning mark 1310 usually interact as follows. When instrumented winning mark 1310 is parked, controller maintains game in open betting state. Removing instrumented winning mark 1310 (when there is no other automation input) from parking position represents betting locking event. Instrumented winning mark 1310 is placed on the numbered site on the game table to define winning number event and represents transition to settlement state. Removing instrumented winning mark 1310 from winning number defines new game event, which represents the end of settlement state and transitions to the open betting state in the next game from the current game.

[0158] In some embodiments, the bet lock event is automatically determined (e.g., via a speed sensor in the reels). In other embodiments, the manual action of the dealer can define this event (e.g., removing the instrumented winning mark 1310 from the parking position). In some embodiments, the system knows the winning number (e.g., via a sensor in the reels). In other embodiments, the instrumented winning mark 1310 is placed in one of the 36 numbered areas in the 3×12 grid to define the winning number. In other embodiments, both the detection of the instrumented winning mark 1310 on the sensor in the reels and the winning number are included, and if the results are inconsistent, the controller 1302 generates a warning. The knowledge of the winning number determines which bets are winners and which bets are losers. Then, the controller 1302 can use information about the placed bets (e.g., according to the RFID tags detected at various betting sites) and the winning number (e.g., by detecting the RFID tags in the instrumented winning mark 1310) to determine the appropriate reward.

[0159] Instrumentation win mark 1310 allows seamless integration with existing use cases, while providing the exact timestamp of key events, triggering the change of game state and determining reward. These features enable the novel index of the wide range including win / loss calculation, player betting mode (e.g., by associating a specific RFID tag with a specific player), game index (e.g., the number and type of competitive speed, errors, etc.) and recording results to determine whether the wheel is "true". These features also enable controller 1302 to track various alarms, such as belated betting alarms or winning bet change alarms. When the system is in a betting lock state and any bet (e.g., the change of the RFID tag detected at a specific antenna) occurs, belated betting alarms occur. When once instrumentation win mark 1310 has been placed and winners and losers are distinguished, winning bet change alarms occur, and the system enters a settlement state; the system detects any attempt to change the bet placed on the winning site and generates a warning.

[0160] In summary, the RFID system 1300 uses the RFID tag identifier of the instrumented winning token 1310 (which is read when the instrumented winning token 1310 is placed at various locations on the gaming table) to change the gaming state of the game. This operation of the RFID system 1300 is different from other uses of the RFID tag identifier (e.g., for determining the face value of the bet at the betting site, for determining warnings, etc.) because these other uses are not used to change the gaming state. This operation of the RFID system 1300 is also different from other systems that change the gaming state because those systems use something other than a specific RFID tag identifier to change their gaming state.

[0161] Exemplary embodiments listed

[0162] Various aspects of the invention can be seen from the exemplary embodiments (EEE) listed below.

[0163] EEE B1. A system for determining the location of an object in a gaming environment, the system comprising: a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; an RFID reader coupled to the plurality of RFID antennas; a plurality of reactance tuning components coupling the plurality of RFID antennas to the RFID reader; and a controller, wherein the controller adjusts the reactance between the RFID reader and a selected one of the plurality of RFID antennas, wherein adjusting the reactance includes selectively connecting one or more of the plurality of reactance components, and wherein adjusting the reactance includes performing impedance matching between the RFID reader and the selected antenna.

[0164] EEE B2. The system according to EEE B1, further comprising: a network analyzer system, wherein the network analyzer system measures a reflection coefficient of the selected antenna, and wherein the controller adjusts the reactance based on a result of measuring the reflection coefficient. EEE B2.

[0165] EEE B3. The system of EEE B2, wherein prior to each read operation performed by the RFID reader, the network analyzer system measures the reflection coefficient and the controller adjusts the reactance of the plurality of reactance tuning components. ...

[0166] EEE B4. A system according to EEE B2, wherein the plurality of RFID antennas have a plurality of configurations, wherein each configuration includes one of a plurality of turns and one of a plurality of loop sizes, wherein the controller adjusts the reactance of each of the plurality of RFID antennas by switching a subset of the plurality of tuning components, wherein the subset is selected based on the reflection coefficient measured for each of the plurality of RFID antennas.

[0167] EEE B5. The system according to EEE B1, wherein the RFID reader performs a first read operation on the selected antenna, wherein the controller adjusts the reactance based on a result of the first read operation, and wherein the RFID reader performs a second read operation on the selected antenna using the adjusted reactance. EEE B5. The system according to EEE B1, wherein the RFID reader performs a first read operation on the selected antenna.

[0168] EEE B6. A system according to EEE B1, wherein the multiple reactance tuning components include a first group of components configured in series and a second group of components configured in shunt, wherein each component in a given group has a reactance value different from each other component in the given group, and wherein the controller adjusts the reactance by selecting one or more of the first group of components and one or more of the second group of components.

[0169] EEE B7. A system according to EEE B1, wherein the plurality of reactance tuning components include a plurality of preconfigured reactance configurations, wherein the selected antenna is associated with a subset of the plurality of preconfigured reactance configurations, and wherein the controller adjusts the reactance by selecting one of the subsets of the plurality of preconfigured reactance configurations.

[0170] EEE B8. The system according to EEE B1, wherein the RFID reader performs a plurality of RFID read operations in succession, wherein the controller dynamically adjusts the reactance when the RFID reader performs the plurality of RFID read operations in succession. EEE B8. The system according to EEE B1, wherein the RFID reader performs a plurality of RFID read operations in succession.

[0171] EEE B9. A method for determining the position of an object in a gaming environment, the method comprising: providing a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; providing an RFID reader coupled to the plurality of RFID antennas; providing a plurality of reactance tuning components coupling the plurality of RFID antennas to the RFID reader; and adjusting the reactance between the RFID reader and a selected antenna among the plurality of RFID antennas, wherein adjusting the reactance includes selectively connecting one or more of the plurality of reactance components, and wherein adjusting the reactance includes performing impedance matching between the RFID reader and the selected antenna.

[0172] EEE C1. A system for determining the location of an object in a gaming environment, the system comprising: a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; a network analyzer system; an RFID reader; a switchable reactance network that selectively connects the plurality of RFID antennas to one of the network analyzer system and the RFID reader using selectable reactance, wherein the switchable reactance network includes a plurality of switches and a shunt element, wherein the shunt element is located inside at least two of the plurality of switches; and a controller, wherein the controller controls the network analyzer system to measure a reflection coefficient of a selected antenna among the plurality of RFID antennas, and wherein based on the reflection coefficient that has been measured, the controller controls the RFID reader to energize the selected antenna, wherein in response to energizing the selected antenna, the RFID reader receives at least one RFID tag identifier from at least one RFID tag near the selected antenna.

[0173] EEE C2. A system according to EEE C1, wherein the plurality of RFID antennas include two or more antennas arranged to cover a given area of ​​the gaming table, wherein the controller selectively couples the network analyzer system to each of the two or more antennas to measure a reflection coefficient of each of the two or more antennas, wherein the selective coupling includes selectively connecting each of the two or more antennas and selectively disconnecting all of the two or more antennas except one that has been selectively connected via an open loop, and wherein the controller controls the RFID reader to selectively energize the two or more antennas based on a result of measuring the reflection coefficient of each of the two or more antennas.

[0174] EEE C3. The system of EEE C1, wherein the controller controls the switchable reactance network to connect one of the network analyzer system and the RFID reader to the selected antenna using the plurality of switches. ...

[0175] EEE C4. A system according to EEE C1, wherein the controller controls the switchable reactance network to adjust the selectable reactance based on the reflection coefficient that has been measured. EEE C4.

[0176] EEE C5. A method for determining the position of an object in a gaming environment, the method comprising: providing a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; providing a network analyzer system; providing an RFID reader; providing a switchable reactance network, the switchable reactance network selectively connecting the plurality of RFID antennas to one of the network analyzer system and the RFID reader using a selectable reactance, wherein the switchable reactance network comprises a plurality of switches and a shunt element, wherein the shunt element is located inside at least two of the plurality of switches; controlling the network analyzer system to measure a reflection coefficient of a selected antenna among the plurality of RFID antennas; and based on the measured reflection coefficient, controlling the RFID reader to energize the selected antenna, wherein in response to energizing the selected antenna, the RFID reader receives at least one RFID tag identifier from at least one RFID tag near the selected antenna.

[0177] EEE D1. A system for determining the location of an object in a gaming environment, the system comprising: a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; an RFID reader coupled to the plurality of RFID antennas; an instrumented winning tag having an RFID tag; and a controller, wherein the controller manages a plurality of gaming states associated with the gaming table, wherein the RFID reader reads the instrumented winning tag based on proximity of the instrumented winning tag to a subset of the plurality of RFID antennas on the gaming table, wherein the subset is less than all of the plurality of RFID antennas, and wherein the controller changes from one of the plurality of gaming states to another of the plurality of gaming states based on a result of the RFID reader reading the instrumented winning tag.

[0178] EEE D2. A system according to EEE D1, wherein the multiple game states include an open betting state, a competition state, and a settlement state. EEE D2.

[0179] EEE D3. A system according to EEE D1, wherein the result of the RFID reader reading the instrumented winning bid corresponds to one of a plurality of events, wherein the plurality of events include a bet lock event, a winning number event, and a new game event. EEE D3.

[0180] EEE D4. A system according to EEE D1, wherein the RFID reader reads multiple RFID tags near the multiple RFID antennas, and wherein the controller generates a warning based on a current game state among the multiple game states and changes in the multiple RFID tags. EEE D4.

[0181] EEE D5. A system according to EEE D1, wherein the gaming table includes an instrumented wheel that determines a winning number, wherein the controller determines the winning number by detecting the instrumented winning number by a particular antenna among the plurality of RFID antennas, and wherein the controller generates a warning when the winning number determined by detecting the instrumented winning number is different from the winning number determined by the instrumented wheel.

[0182] EEE D6. A method for determining the position of an object in a gaming environment, the method comprising: providing a plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on a gaming table; providing an RFID reader coupled to the plurality of RFID antennas; providing an instrumented winning tag having an RFID tag; managing a plurality of gaming states associated with the gaming table by a controller; reading the instrumented winning tag by the RFID reader based on proximity of the instrumented winning tag to a subset of the plurality of RFID antennas on the gaming table, wherein the subset is less than all of the plurality of RFID antennas; and changing from one of the plurality of gaming states to another of the plurality of gaming states by the controller based on a result of the RFID reader reading the instrumented winning tag.

[0183] The above description illustrates various embodiments of the present invention along with examples of how aspects of the present invention may be implemented. The above examples and embodiments should not be considered the only embodiments, but are presented to illustrate the flexibility and advantages of the present invention as defined by the appended claims. Based on the above disclosure and the appended claims, it will be apparent to those skilled in the art that other arrangements, embodiments, implementations and equivalent forms may be employed without departing from the spirit and scope of the present invention as defined by the claims.

Claims

1. A system for determining a position of an object in a game environment, the system comprising: A plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on the gaming table; and an RFID reader coupled to the plurality of RFID antennas, wherein an antenna of the plurality of RFID antennas is impedance matched to a stack of RFID tags at a first impedance matching value, wherein the first impedance matching value is different from a second impedance matching value used to impedance match the antenna to a single RFID tag, wherein the first impedance matching value produces a less efficient impedance match than the second impedance matching value between the single RFID tag and the antenna.

2. The system according to claim 1, further comprising: one or more reactive tuning components that couple the antenna to the RFID reader, wherein the one or more reactive tuning components are selected from capacitors and inductors, The antenna is impedance matched to the RFID tag stack by adjusting the reactance of the one or more reactance tuning components.

3. The system of claim 2, wherein the one or more reactance tuning components include a series capacitor and a shunt capacitor, Wherein the antenna is impedance matched to the RFID tag stack by increasing the capacitance of the series capacitor and by reducing the capacitance of the shunt capacitor.

4. The system of claim 1, wherein the plurality of RFID antennas comprises a first plurality of antennas and a second plurality of antennas, wherein the first plurality of antennas are each of a first type, wherein the second plurality of antennas are each of a second type.

5. The system of claim 1, wherein the plurality of RFID antennas comprise a plurality of types.

6. The system of claim 1, wherein each of the plurality of RFID antennas is of a type, wherein the type includes size, shape, and configuration.

7. The system of claim 1, wherein each of the plurality of antennas is impedance matched to the RFID tag stack according to a corresponding type of each of the plurality of antennas.

8. The system of claim 1, further comprising: a plurality of reactive tuning components that couple the plurality of antennas to the RFID reader, Wherein each of the plurality of RFID antennas is of a type, wherein each type is associated with a corresponding reactance of the plurality of reactance tuning components.

9. The system of claim 1, wherein the plurality of RFID antennas are of a plurality of types, wherein the plurality of types include two or more of a point antenna type, a line antenna type, and a cross antenna type.

10. The system of claim 1, further comprising: A multiplexer selectively connects one of the plurality of antennas to the RFID reader.

11. The system of claim 1 , wherein the RFID reader is one of a plurality of RFID readers associated with the gaming table.

12. The system of claim 1, further comprising: a controller coupled to the RFID reader, the controller configured to store an RFID tag database and send a read command to the RFID reader, wherein the RFID reader is configured to energize a given one of the plurality of RFID antennas and receive one or more RFID tag identifiers from one or more RFID tags in response to the read command, and wherein the controller is configured to determine a value associated with a given one of the plurality of locations on the gaming table based on the given antenna, the RFID tag database, and the one or more RFID tag identifiers.

13. The system of claim 1, wherein the first impedance matching value is determined by: measuring the reflection coefficients of the plurality of RFID tags; and The reactance of one or more reactance tuning components coupling the antenna to the RFID reader is adjusted based on the reflection coefficient that has been measured.

14. The system of claim 1, wherein the RFID tag stack and the single RFID tag each comprise a ferrite core.

15. The system of claim 1, wherein the RFID tag stack and the single RFID tag each include a ferrite core, wherein the ferrite core changes an excitation field of a given antenna of the plurality of RFID antennas.

16. A device for determining a position of an object in a gaming environment, the device comprising: Game table; A plurality of radio frequency identification (RFID) antennas arranged at a plurality of locations on the game table; and an RFID reader coupled to the plurality of RFID antennas, wherein an antenna of the plurality of RFID antennas is impedance matched to a stack of RFID tags at a first impedance matching value, wherein the first impedance matching value is different from a second impedance matching value used to impedance match the antenna to a single RFID tag, wherein the first impedance matching value produces a less efficient impedance match than the second impedance matching value between the single RFID tag and the antenna.

17. The apparatus of claim 16, wherein each of the plurality of antennas is impedance matched to the RFID tag stack according to a corresponding type of each of the plurality of antennas.

18. The apparatus of claim 16, wherein the plurality of RFID antennas are of a plurality of types, wherein the plurality of types include two or more of a point antenna type, a horizontal line antenna type, a vertical line antenna type, a cross antenna type, and a pole antenna type.

19. A method for determining a position of an object in a gaming environment, the method comprising: providing a plurality of radio frequency identification (RFID) antennas disposed at a plurality of locations on the gaming table; and providing an RFID reader coupled to the plurality of RFID antennas, wherein an antenna of the plurality of RFID antennas is impedance matched to a stack of RFID tags at a first impedance matching value, wherein the first impedance matching value is different from a second impedance matching value used to impedance match the antenna to a single RFID tag, wherein the first impedance matching value produces a less efficient impedance match than the second impedance matching value between the single RFID tag and the antenna.

20. The method of claim 19, further comprising: selectively connecting a given antenna of the plurality of antennas to the RFID reader; and The given antenna is powered on with the RFID reader, wherein powering the given antenna includes reading a subset of the plurality of RFID tags.

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