CA2226989A1

CA2226989A1 - Game piece detector

Info

Publication number: CA2226989A1
Application number: CA 2226989
Authority: CA
Inventors: Ian Michael Wiles; Andrew David White
Original assignee: Individual
Current assignee: Hasbro International Inc
Priority date: 1995-07-14
Filing date: 1996-07-11
Publication date: 1997-02-06
Also published as: AU6464996A; DE69604405T2; ES2137012T3; AU695447B2; EP0839066B1; DE69604405D1; NZ312747A; GB9514422D0; EP0839066A1; WO1997003739A1; JPH11509124A

Abstract

Game apparatus comprises a playing surface defining an array of playing positions (2); and a playing piece detector (3) positioned behind at least one of the playing positions (2), the or each detector including a pair of capacitor plates (4, 6) electrically insulated from each other. A monitoring system (20) is connected to the or each detector (3) for monitoring the value of a resistance in proximity to the capacitor plates (4, 6) and for providing a corresponding output. A set of one or more playing pieces (12) each have an electrically resistive surface (13) which is placed on or adjacent to the playing surface in use. When a playing piece (12) is placed on a playing position (2) associated with the detector (3), the resistive surface (13) is insulated from the detector but capacitively coupled with it so that the monitoring system (20) can monitor the playing piece resistance.

Description

GAME APPARATUS

The invention relates to game apparatus and in particular to apparatus which provides a detector for detecting the position of a playing piece on the apparatus.
Many proposals have been made in the past for detecting the position of playing pieces on a board of a game but these have been relatively complex, requiring the use of specially constructed playing pieces and boards, and thus are expensive which is particularly undesirable in the field of games.
US 5082286 discloses electronic game apparatus in which transmit and receive coils are provided beneath the playing positions and a high frequency current is supplied to each transmit coil in turn and a voltage induced in the receive coils is detected. The presence of a playing piece on the playing area being tested will affect the voltage induced in the receive coils and hence the presence, absence or type of playing piece can be determined. This approach has very limited applications since it relies on measuring changes in mutual inductance and in practice the system will only be able to measure an increase or decrease in mutual inductance enabling no more than two different types of playing piece to be distinguished.
2S US-A-5013047 discloses game playing apparatus in which each playing position is divided into two halves formed as metal contacts connected to an electrical circuit. When a playing piece having a conductive base is placed on the playing position it will establish a conductive connection between the two halves thus completing the electrical circuit and allowing the presence of the piece to be detected. The main drawback of this approach is the fact that the contacts are exposed which makes it particularly undesirable for use as game playing apparatus where it will be subject to the risk of shorting due to spillages and the like and may also present a hazard to the players, W O 97/03739 PC~/GB96/01672 particularly children, who risk receiving an electrical shock if they touch the game board.
In accordance with the present invention, game apparatus comprises a playing surface defining an array of playing positions; a playing piece detector positioned behind at least one of the playing positions, the or each detector including a pair of capacitor plates electrically insulated from each other; a monitoring system connected to the or each detector for monitoring the value of a resistance in proximity to the capacitor plates and for providing a corresponding output; and a set of one or more playing pieces each having an electrically resistive surface which is placed on or adjacent to the playing surface in use, the arrangement being such that when a playing piece is placed on a playing position associated with the detector, the resistive surface is insulated from the detector but capacitively coupled with it so that the monitoring system can monitor the playing piece resistance.
We have devised a new game apparatus which is particularly advantageous since the playing pieces can have a substantially conventional construction and simply need to be provided with an electrically resistive surface.
There is no need to incorporate special electronics into the playing pieces and thus the overall cost and complexity of the apparatus is significantly reduced. Furthermore, the invention avoids the problems mentioned above in connection with exposed contacts by placing the detectors behind the playing positions. Effectively, a series arrangement of a capacitor defined between one of the capacitor plates and the electrically resistive surface of the playing piece, a resistance defined by the electrically resistive surface, and a second capacitor defined between the electrically resistive surface and the other capacitor plate is formed and providing the impedance presented by the two capacitances is relatively small compared with the resistance of the electrically resistive surface, a measurement of the total resistance in this series arrangement can be equated effectively with the resistance of the electrically resistive surface. In this way, it is possible relatively easily to monitor the resistance of the ~ electrically resistive surface of a playing piece at the 5 playing position while at the same time avoiding electrical t contact between the playing piece and the detector. In addition, as will be explained below, it is much simpler with this approach to distinguish between several different playing pieces by virtue of the fact that the present 10 invention monitors resistance rather than other features such as mutual inductance.
In some cases, the electrically resistive surface of a playing piece is insulated from the detector by providing the surface at a position spaced from the base o~ the lS playing piece so as to ensure there is no contact therebetween. Preferably, however, the electrically resistive surface is positioned on the base of the or each playing piece which contacts the playing surface, the playing surface being electrically insulated from the 20 detector. For example, the detector could be covered with an insulating coating or be physically spaced apart from the playing surface.
In some cases, where the game apparatus includes a plurality of playing pieces, only one of these pieces may 25 be provided with an electrically resistive surface. This would be suitable in the case where the game only requires the position of one special playing piece to be monitored.
However, preferably all the playing pieces are provided with electrically resistive surfaces. In this case, the 30 surfaces may have the same resistance but in the preferred arrangement, the electrically resistive surfaces of at least some of the playing pieces have different resistances so that they can be distinguished.
In general, it is intended that only a single playing 35 piece ~ill be placed on a playing position associated with a detector at any one time. In some applications, however, it is possible that two (or more) playing pieces could be positioned on the same playing position. In some cases, this would mean that the types of playing pieces on that playing position could not be distinguished if they each have an electrically resistive surface. However, by sui~ably choosing the resistances of the surfaces of all the playing pieces, it would be possible to ensure that any combination of playing pieces will generate a total monitored response which is different from any one of the pieces (or any combination of those pieces) so that the identity of the pieces can be distinguished.
In a similar way, in some cases a detector may be positioned only in association with a single playing position. However, in the preferred arrangement, a detector is associated with a plurality, preferably all, of the playing positions. In these cases, the monitoring system is preferably adapted to poll each detector in turn in order to determine the identity of the playing pieces situated at each playing position.
Typically, the monitoring system carries out a resistance measurement between the two plates of the or each detector at a frequency of about lOOkHz. An infinite resistance indicates the absence of a playing piece while a finite resistance of a particular value will identify the piece (or pieces) on the playing position. The resistance measurement can be carried out in several ways as will be described below.
The playing surface itself will generally be flat but could have any other form such as curved providing the playing pieces can be positioned on the surface.
An example of game apparatus according to the invention will now be described with reference to the accompanying drawinys, in which:-Figure 1 is a plan of part of a board of the game apparatus with a detector being shown in phantom;
Figure 2 is a cross-section taken on the line 2-2 in Fi~ure l with a playing piece positioned on the board;

CA 02226989 l998-0l-l4 W O 97/0373g PCT/GB96/01672 Figure 3 is a block diagram of the processing electronics;
Figure 4 illustrates part of the scan controller circuit of Figure 3 in more detail; and, Figure 5 illustrates a dummy column of detectors.
J Figure 1 illustrates part of a game board 1 which is divided into a number of playing positions 2 formed as an orthogonal array of rows and columns. Only nine playing positions have been shown in Figure 1 and typically, for example in the case of a chess board, there would be 64 playing positions.
Beneath each playing position 2 is positioned a detector 3. One of the detectors 3 is shown in phantom under one of the playing positions 2 in Figure 1. The detector 3 is formed as an interdigitated capacitor comprising a ~irst capacitor plate 4 having a number of laterally extending fingers 5 and a second capacitor plate 6 having a number of laterally extending fingers 7 interdigitated between the fingers 5. Only two of each of the fingers 5,7 have been shown in Figure 1 for clarity.
In practice, there would be several more, for example six, of each. The capacitor plates are connected to processing electronics 8 via suitable tracks (not shown) arranged in conventional "rows and columns" fashion.
The construction of the board can be seen in more detail in Figure 2. The board comprises a base 10 on which the capacitor plates 4,6 are formed, typically as printed tracks using printed circuit board technology. An insulated coating 11 is provided over the tracks defining the capacitors 4,6, the coating being provided with graphics. These graphics typically will outline the playing positions and provide other information in a conventional manner.
Figure 2 also illustrates a playing piece l~ which has a resistive coating 13 on its base. It will be seen that the resistive coating 13 contacts the insulating coating 11 when the playing piece 12 is positioned at a particular playing position. However, the resistive coating 13 is spaced from the capacitor plates 4,6 by the coating 11.
The resistive coating 13 is formed by an appropriate combination of conductive and resistive inks. In practice, since the physical dimensions of the coatings 13 on each playing piece will be substantially the same, a difference in resistance is achieved by using appropriately varied combinations of inks to obtain coatings with different resistivities. In a typical game, there will be between 12 and 20 playing pieces, each having a resistive coating with a different resistivity.
The construction of the processing electronics is shown in more detail in Figure 3. The electronics includes a scan-controller circuit 20 connected to the detectors 3 on the game board l and constitutes a slave control circuit for the system. It is supplied with a lOOkHz (27MHz is a suitable alternative) unmodulated signal from an oscillator 21 and supplies this signal in turn to all the detectors in respective columns of the array of playing positions Z.
While the signal is being supplied to a column of detectors, the scan controller circuit 20 routes signals returning from the rows of the game board, in turn, to a demodulator 22.
The analogue output from the scan controller circuit ~5 20 for each row is fed to a demodulator 22 which includes a diode 23 in series with a parallel arrangement of a capacitor 24 and resistor 25. This demodulates the incoming signal to generate a DC output level which varies in accordance with the resistance of the coating 13 of the playing piece associated with the detector whose output is being currently monitored. In accordance with Ohm's law a low resistance will cause a high DC level and vice versa.
This DC analogue level is fed to an A/D convertor 26 which generates a digital output which is fed to the system controller and speech circuit 27. This is the master control circuit for the system. The system controller 27 has a suitably programmed microprocessor which can access a look-up table from which it can determine the playing piece resistances being monitored. At the same time, the system controller 27 is controlling the scan controller circuit 20 so that it also knows the playing position which is currently being monitored and so can determine the location and type of piece. In this example, all the pieces have resistive coatings 13 of different resistances so that following a complete scan of the game board 1, the system controller 27 can build up a complete picture of the type and location of each playing piece on the board.
The system controller 27 can then use this information in a variety of ways depending upon the game being played.
In particular, the system controller includes a speech circuit for generating commands and other information which is routed via the scan controller circuit 20 to one or both of a pair of headphones 30,31 worn by the players.
In this example, the monitoring of a single piece on a playing position has been described. In other examples, the playing positions 2 may be large enough to accommodate more than one playing piece. Providing the resistances of the coatings 13 of the playing pieces are suitably selected, it is possible to be able to identify each individual playing piece on the playing position. For example, if the resistances of the coatings of the two pieces are R1, R2 then their combined resistance will be the parallel combination of these two resistances (R) given by:
l/R = 1/R1 + l/R2 Providing there is no other playing piece or combination of playing pieces with resistance R then the detection of such a resistance R will indicate the presence of the two pieces with resistances R1, R2.
In order to explain how the resistance of a playing piece is monitored, reference is made to Figures 4 and 5 which show part of the scan controller circuit 20 in more detail. In this example, it is assumed that there are six rows of detectors (labelled Row 0 - Row 5) and five columns of detectors (labelled Column 0 - Column 4). The first capacitor plates 4 of each detector 3 in Row 0 are connected to a first port of an analogue switch 40. In a similar manner, the first capacitor plates 4 of successive rows are connected to successive ports of the analogue switch 40. Each row is also connected to a respective lKn resistor 41-46.
The second capacitor plates 6 of the first column (column 0) of detectors is connected to a first port of an analogue switch 47 and in a similar manner the second capacitor plates 6 of successive columns of detectors (Columns 1-4) are connected to successive ports of the analogue switch 47. In addition, each column of detectors is connected to a respective lKn resistor 48-53.
Each analogue switch 40,47 is controlled from the microprocessor within the system controller and speech circuit 27 via 3 bit row and column control lines 54,55.
An unmodulated lOOkHz signal is generated by the RC
oscillator 21 and fed to the analogue switch 40. The analogue switch 40 is controlled by the microprocessor via control lines 54 to feed the oscillating signal in turn to each of the rows Row 0 - Row 5. Each of the other rows is grounded via the respective resistors 41-46.
All the columns Column 0 - Column 4 are grounded by the resistors 48-53 and the analogue switch 47 is controlled via control lines 55 to connect the columns in turn via a unity gain buffer 5i to one side of a difference amplifier 58 while the oscillating signal is fed to one row. The next row is then selected and the response from each column is monitored. This sequence is then repeated for all rows.
A signal received from a dummy column (Figure 5) and shown as Column 5 in Figure 4 is permanently fed via a unity gain buffer 59 to the other input of the difference amplifier 58. The difference signal from the difference amplifier 58 is fed to the diode 23 where it is converted to DC form as shown in Figure 3.

, The effect of the presence of a playing piece in a playing position is to create a series connection between a capacitor defined by the playing piece and the first capacitor plate 4, a resistance defined by the resistance of the resistive coating 13, and a capacitor defined between the playing piece and the second capacitor plate 6.
At a frequency of lOOkHz, the impedance presented by the two capacitors can be made relatively small compared with the resistance of the coating by using coating resistances in the order of lM~. Alternatively, if oscillator frequencies in the order of 27M~z are used then this will result in each capacitance presenting an impedance of about lOOQ with the result that lower coating resistances of the order of 1 ool~n c~n be used.
In any cvent, the resistance of the electrical coating is chosen to be significantly higher than the impedances presented by the capacitances so that these impedances can effectively be ignored. The resistance is then monitored by monitoring the current flowing through the resistance which in turn is monitored by monitoring the voltage drop across the resistors 48-53. This voltage drop, represented by the current from the difference amplifier 58 is then used to represent the monitored resistance.
The dummy column, Column 5, is provided to eliminate effects caused by stray capacitances. The dummy column is not affected by the playing piece and so the signal monitored from the dummy column represents the effect of stray capacitances and can simply be subtracted from the signal rec~ived from the appropriate one of the columns Col 0-Col 4 by the difLerence amplifier 58.
In some cases, the dummy column can be defined by a set of detectors arranged parallel with the other columns but this is not essential and indeed there is a risk that a player could affect the signal from the dummy column in this situation r n the preferred arrangement, therefore, as shown in Fiyure 5, the dummy column comprises a set of six capacitor/resistor components each connected in series , to a respective row line ~ow O - Row 5 and in parallel to the Col 5 line. These are shown at 61-66 in Figure 5.
In this description, it has been assumed that the playing pieces will rest on the playing positions under gravity. Ilowever, it is also possible to use other means, such as magnetism, to hold the pieces in position.

Claims

1. Game apparatus comprising a playing surface defining an array of playing positions; a playing piece detector positioned behind at least one of the playing positions, the or each detector including a pair of capacitor plates electrically insulated from each other; a monitoring system connected to the or each detector for monitoring the value of a resistance in proximity to the capacitor plates and for providing a corresponding output; and a set of one or more playing pieces each having an electrically resistive surface which is placed on or adjacent to the playing surface in use, the arrangement being such that when a playing piece is placed on a playing position associated with the detector, the resistive surface is insulated from the detector but capacitively coupled with it so that the monitoring system can monitor the playing piece resistance.

2. Apparatus according to claim 1, wherein the electrically resistive surface is positioned on the base of the or each playing piece which contacts the playing surface, the playing surface being electrically insulated from the detector.

3. Apparatus according to claim 2, wherein the playing surface includes an insulating coating on which the playing pieces are positioned.

4. Apparatus according to claim 3, wherein the insulating coating comprises graphics.

5. Apparatus according to any of the preceding claims, the apparatus including a plurality of playing pieces each of which has a resistive surface whose resistance is different from all the other playing pieces.

6. Apparatus according to claim 5, wherein the resistances of the resistive surfaces of the playing pieces are chosen so that if any combination of two or more playing pieces are provided on the same playing position then the monitored resistance is different from that of any other playing piece alone or combination of playing pieces.

7. Apparatus according to any of the preceding claims, wherein the resistive surfaces of the playing pieces have substantially the same physical dimensions but with different resistances.

8. Apparatus according to any of the preceding claims, wherein the resistive surface of the or each playing piece is formed by a combination of conductive and resistive inks.

9. Apparatus according to any of the preceding claims, wherein the playing surface is generally flat.

10. Apparatus according to any of the preceding claims, wherein the monitoring system includes an oscillator; means for coupling the oscillator to the or each detector; and a monitor for monitoring current flow through the detector.

11. Apparatus according to claim 10, wherein the playing positions are arranged in an orthogonal array of rows and columns, each playing position having a respective detector, the coupling means being capable of coupling the oscillator to each row in turn.

12. Apparatus according to claim 11, wherein the monitor is adapted to monitor current flowing through each column of detectors in turn.

13. Apparatus according to any of claims 10 to 12, further comprising an additional set of detectors defining a dummy column not associated with playing positions, and means for correcting column currents monitored by the monitor by subtracting a current flowing through detectors of the dummy column.