Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02226989 1998-01-14
PCT/GB96/01672
W O 97/03739
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,
CA 02226989 1998-01-14
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
CA 02226989 1998-01-14
PCT/GB96/01672
W O 97JO3739
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
CA 02226989 1998-01-14
PCT/GB96/01672
W O 97/03739
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
CA 02226989 1998-01-14
W O 97/03739 PCT/GB96/01672
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
CA 02226989 1998-01-14
PCT/GB96/01672
W O 97103739
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
CA 02226989 1998-01-14
W O 97/03739 PCT/GB96/01672
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.
,
CA 02226989 1998-01-14
WO 97/03739 PCT/GB96/01672
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
,
CA 02226989 1998-01-14
W O 97/03739 PCT/GB96/01672
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.
