GB2088561A - Ratio encoder for slot machine reels - Google Patents

Abstract

A ratio encoder encodes the instantaneous angular position of one or more spinning reels in a microprocessor controlled amusement game such as a fruit machine. The ratio encoder provides substantially instantaneous angular position data to the microprocessor by measuring the ratio of two voltages generated by electrical resistance track 11 on the reel's periphery. One of the voltages may be a reference voltage applied to the ends of resistance track 11 via slip rings 14, 16 and the other may be substantially proportional to the angular displacement of the reel from a reference position as detected by slider 18. The ratio, which is thereby rendered independent of supply current fluctuations, may be obtained as an analogue voltage from meter 22, converted to digital form at 23 and then supplied to the microprocessor. <IMAGE>

Description

SPECIFICATION Ratio encoder for slot machine reels This invention relates to rotary potentiometers for encoding the instantaneous angular positions of spinning reels in amusement games including fruit machines, sometimes known as slot machines. More particularly, the invention relates to devices for providing instantaneous position information in the form of digital data input to a microprocessor controlling an amusement game by measurement of a voltage ratio rather than an absolute voltage.

In a microprocessor controlled fruit machine, for example, the microprocessor may be required to stop each of a plurality of spinning reels at a preselected position. The positions could be determined by microprocessor calculations conforming with particular rules governing the course of play.

When the reels are stopped at the preselected positions there will be a preselected array of fruit symbols displayed on a win line. The present invention, therefore, provides such a microprocessor with the current position of each spinning reel.

The microprocessor utilises the position information to issue "stop" instructions in order to stop each reel at its predesignated position.

An example of a fruit machine feature for which the present invention can sense position information for a microprocessor is found in Bally Mfg. Co.'s co-pending application entitled "Swap Feature for Fruit Machines", Application No. 8026094. The invention may also be used to solve other sensing and control problems in gaming machines or amusement games.

Fruit machines are presently known in which electrical means are utilized to sense the angular position of a reel after the reel has stopped spinning.

British Patent No, 1,423,415, for example, issued to New Century Novelty Company, Pty. Ltd. discloses a fruit machine reel having a resistor with two contact points adjacent to each symbol on a fruit machine reel. The resistance value of the resistor encodes the particular symbol displayed. A pair of wipers connected to a voltage source then identifies the particular symbol displayed by measuring the resistance adjacent to that symbol. The identification is used to determine whether the combination of stopped reels is entitled to a play-off.

The art exemplified by the New Century Novelty Company patent is not used for real time microprocessor control.

Rotary potentiometers have been used to indicate continuously the angular position of a rotatable shaft. British Patent No. 1,297,111 issued to Jones, for example, discusses the use of a rotary potentiometer for indicating the wind direction. The output of the rotary potentiometer can be fed to a simple galvanometer which, in turn, can drive a pen on a moving strip chart. Rotary potentiometers have not, however, been previously used in amusement games as sensing elements for microprocessors.

Bally Mfg. Co.'s co-pending application entitled "Analogue Encoder for Slot Machine Reels", Appli --r:^^ + rAtorv! for sensing the substantially instantaneous position of a rotating reel in an amusement game. The output voltage of the potentiometer is converted to a digital signal by an analogue/digital converter and then used as input data for the controlling microprocessor.

The principles described in the co-pending application were embodied in systems that measured absolute electrical quantities. For example, in a reel having uniform resistance around the periphery, a constant current could be input at a fixed point on the reel's periphery and output at a point fixed in space. The voltage drop between the two points is then proportional to the resistance along the periphery between the two points and, hence, to the reel's angular position.

The present invention, in contrast, envisions the measurement of ratios of electrical quantities as indicators of reel angular position, rather than the values of the quantities themselves. Ratio measurements have inherent advantages which are realizable within the scope of this invention. For example, the value of resistance per unit length around the reel's periphery is unimportant if voltage ratios are measured. All that is needed is that the resistance be uniform on each reel. As a consequence, substantial manufacturing economies may be realized by utilizing ratio measurements.

Also, by utilizing ratio measurements one makes the measurement substantially independent of supply voltage or supply current fluctuations. Such independence will become evident in the following description of a preferred embodiment utilising the principles of the present invention.

In one embodiment of the invention the periphery of the spinning reel will comprise a conductor containing resistance such that the resistance between any two points on the reel is proportional to the angular displacement separating the two points as measured from the centre of the reel. In this embodiment a first reference point on the reel is connected to a potential source fixed at a voltage with respect to earth through a first slip-ring. A fixed terminal which is earthed contacts the periphery of the reel at a point fixed in space so that the angular displacement between the fixed terminal and the reference point on the reel increases in time at a rate proportional to the angular velocity of the reel. An opening may be made in the conductor containing resistance to provide an open circuit in the conducting path on the reel's periphery.The open circuit may be provided on one side of, and adjacent to the first reference point; the angle from the other side of the first reference point to a second reference point then becomes a fixed reference angle. The second reference point connects to a second slip-ring. The ratio of the fixed voltage to the voltage difference between slip rings will then equal the ratio of the angular displacement to the angular separation between reference points. The voltage difference between slip-rings and the fixed voltage may then be fed to an analogue/digital converter whose output becomes the input to the controlling microprocessor. The reference voltage to the analogue/digital converter mav be iust the voltage from the potential source. The input to the microprocessor will then be the aforementioned ratio.

The implementation of the embodiment is not limited to detection of positions of a single wheel.

Positions of several wheels may be determined by use of multiple techniques. In a complete machine, for example, the microcomputer could monitorthe angular positions of several wheels simultaneously and then issue stop instructions to means controlling the rotation of each of the several wheels according to a programme contained in the microprocessor.

Examples of the invention will now be described with reference to the accompanying drawings in which Figure 1 illustrates an embodiment of the invention.

In Figure 1 a reel of a gaming machine is illustrated generally at 10. The reel 10 may comprise one of the indicating reels of a fruit machine, for example. The reel 10 has a resistive track 11 extending about the axis 12 of rotation of the reel. The track 11 is circular centred on the axis 12 and is continuous apart from a breack 13. Immediately adjacent one side of the break 13, the track 11 is electrically connected to a first continuous circular conductive slip ring 14 having a low resistance by a contact 15 slideably connected to the slip ring 14. On the other side of the break 13 the track 11 is electrically connected to a second slip ring 16 buy a contact 17 slideably connected to the slip ring 16.The angular displacement between the contact 15 and 17 is thereby substantially 360O as measured along the electrically connected portion of track 11. Typically the rings 14 and 16 may be of copper. Electrical contacts are made to the track 11 and the slip rings 14 and 16 by means of brushes 18, 19, and 20, respectively. The three brushes are fixed in space. As a result the point of contact between the brush 18 and the track 11 is dependent on the angular position of the reel 10.

However, because of the low resistance of the rings 14 and 16 direct electrical contact is effectively made between the brush 19 and the contact 15 near one end of the track 11.

Effectively direct electrical contact is made through slip-ring 16 between the brush 20 and the contact 17 on the other side of the break from contact 15.

The track 11 has a constant resistance per unit angular displacement about the axis 12 so that the resistance between any two points along the track 11 is dependent on their angular separation. Accordingly, it can be seen that the resistance between the brushes 18 and 19 is dependent on the angular position of the reel 10, whereas the resistance between the brushes 19 and 20 is essentially fixed. A voltage source 21 establishes a fixed voltage between the brush 19 and brush 20, the latter being connected to earth. The fixed voltage thereby establishes a reference voltage between the two edges of the break 13.

The angular distance between the contact point of the brush 19 on the track 11 and the break 13 may now be determined by voltage ratio measurements.

The ratio of the voltage (with respect to earth) on brush 18to the voltage source voltage on brush 19 is substantially equal to the angular distance in question. The ratio of voltages may be conveniently measured with a voltage ratio meter 22 and the output fed to an analog-to-digital converter 23. The digital output may then be utilised by the controlling microprocessor.

Claims (5)

1. A gaming device utilising one or more reels that spin and then stop under control of a microprocessor and its associated memory, and having apparatus for transmitting to the microprocessor the instantaneous position of each reel with respect to a spatially fixed point by generating a pair of voltages having a ratio uniquely dependent upon the instantaneous angular position of the reel, and apparatus responsive to the ratio of the voltages which outputs a digital signal substantially indicative of said ratio, said digital signal capable of being read and acted upon by the microprocessor and stored in the microprocessor memory.

2. A gaming machine having at least one reel rotatable about an axis and measurement means to measure the angular position of the reel, said measurement means comprising electrical resitance means on the reel providing angularly distributed electrical resistance extending substantially completely around the periphery of the reel; at least a triad of contact means to make electrical contact with said resistance means, at least one of said contact means contacting said electrical resistance at a contact point fixed in space, thereby causing the location of said contact point on said resistance means and the resistance between at least one pair of contact means to depend upon the angular position of the reel; and means to generate a digital signal substantially proportional to the ratio of the resistance between said pair of contact points to a substantially fixed reference resistance between a second pair of contact points.

3. A gaming machine as claimed in Claim 2 wherein a first contact means makes contact at a point fixed in space and a second and a third contact means make contact at different fixed reference points on said resistance means, the ratio of the voltage between the first and second contact means to the voltage between the second and third contact means being proportional to the angular displacement between the first and second contact means.

4. A gaming machine as claimed in Claims 2 or 3 wherein the resistance means is a continuous resistive track.

5. A gaming machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.