Slot machine

The present invention relates to a slot machine, especially to a slot machine wherein information about the foregoing games or simulation of following games can be displayed.

Slot machines are well known as game machines in which players can play a game by Inserting coins or tokens (hereinafter referred to as coins) prior to starting the game. When a hit, that is, the winning of a prize, occurs, a number of coins are paid out depending on the rank of the hit

Each slot machine has a predetermined pay-out rate, that is, the total coin pay-out number-to-the total coin insertion number ratio. In a slot machine where a random number is sampled at the beginning of a game to decide the rank of winning based on the random number, and the stop of reels is controlled electrically corresponding to the decided rank, it is possible to predetermine the pay-out rate by assigning each random number to any of the predetermined hit ranks as well as by determining the number of coins to be paid out for the respective ranks such that she obtained pay-out rate will corresponds to a desirable value according to the probability theory. Also in a slot machine wherein reels stop at random timings, it is possible to select the hit symbol combinations-to-the total available symbol combinations ratio and the number of coins to be paid out for the respective hit ranks such that a desirable pay-out rate may be obtained according to probability theory. In either case, the total coin pay-out number-to-the total coin insertion number ratio approaches to the predetermined pay-out rate as a greater number of games are played.

Although a pay-out rate is predetermined for a slot machine in the above manner, most of the players play games for a limited time that is very short relative to the total operating time of the slot machine, so that the transient pay-out rate in the limited time does not always coincide with the predetermined pay-out rate. As the result, the probability of prize-winning changes depending on the number of coins paid out for the foregoing games.

Considering this characteristic, it will be understood that a slot machine from which a great number of coins have already been paid out has a tendency to pay out a less number of coins thereafter. Such a characteristics or tendency is also known to the skilled players by experience.

As described so far, whether a good many number of coins can be won or not depends to a certain degree on the result of the past games. However, even when a player knows the above characteristics of the slot machine, because no information about the past games is given in conventional slot machines, the player can not take advantage of the knowledge on selecting a slot machine to play a game. It is, of course, possible to observe others' play for a certain time as to see the progress of the preceding games before selecting a slot machine to play. But this is time-wasting and ineffective.

US-A-3 112 979 and US-A-4 624 459 disclose slot machines in accordance with the precharacterising portions of claims 1 and 2 in which winning scores or the number of previously won games is stored and can be displayed, for instance so that a multiple pay-out can be made if the number of wins reaches a predetermined number. It is also well-known, for instance from GB-A-2 185 612 for the machine to monitor the pay-out ratio so that the current pay-out can be adjusted to achieve a desired pay-out ratio.

US 4 679 143 describes an amusement device device and method of operation wherein a plurality of payout schedules which govern the conduct of the game are retained in a memory. The actual payout rate of the apparatus is constantly determined and the actual payout is compared with predetermined limits. If the actual payout exceeds the limit, the apparatus automatically selects another payout schedule which alters the probability of a layer's winning. The game is fair because the payout schedule governing conduct of the game is displayed to the player.

The present invention provides a slot machine in which a player pays to play each game, and a predetermined value prize is paid-out as a prize for a hit game, said slot machine comprising: <ul id="ul0001" list-style="none" compact="compact"><li>controlling means for controlling the pay-out ratio of the slot machine;</li><li>means for storing data about the past games; and</li><li>means for displaying to the player said data about the past games characterised in that said data is pay-out data on the past games representing the relationship between the cost of the games and the value of prizes for the games.</li></ul>

Because data about the past games are displayed, the player can see and consider the data for selecting a slot machine before starting a game, so the invention will improve amusement of the game.

A random number may be sampled to decide the rank of winning as well as the number of coins to be paid out, the decided rank depending on the sampled random number.

Means may also be provided for simulating games, said storing means and displaying means storing and displaying data about simulated games.

By making possible to execute simulation games and display hypothetical pay-out data, the player can start an actual game at an appropriate time while considering the tendency of coin payment or the transient probability of winning predicted based on the hypothetical pay-out data.

In either case, because the player can predict the probability of winning based on the past or hypothetical pay-out data, amusement increases compared with the conventional slot machines wherein the players can merely play games successively.

The two aspects of the invention may be combined and the display means be operable to display data about either past played or past simulated games in response to actuation of a selection means.

The invention will be further described by way of non-limitative example with reference to the accompanying drawings, in which:- <ul id="ul0002" list-style="none" compact="compact"><li>Figure 1 is a perspective view showing an appearance of the slot machine;</li><li>Figure 2 is an example of display showing pay-out data of the past games;</li><li>Figure 3 is an example of display showing hypothetical pay-out data calculated for simulative games;</li><li>Figure 4 is a block diagram schematically showing circuity of a slot machine embodying the present invention; and</li><li>Figure 5 is a flowchart for explaining the operation of the slot machine.</li></ul>

In figure 1, a slot machine embodying the present invention has a housing 2 with a door panel 3 on the front thereof. The door panel 3 has three windows 4 though which three reels 5, 6 and 7 rotatable in the housing 2 can be viewed, respectively. The door panel 3 is hinged onto the front wall of the housing 2 so as to be opened for maintenance or examination of the slot machine.

Designated by 8 is a coin slot 8 though which a player should insert one to three coins before starting a game, wherein the number ofwinning lines effective for that game depends on the number of inserted coins. That is, there are three horizontal lines and two diagonal lines across the windows 4, and when a single coin is inserted, only the middle horizontal line becomes effective, whereas when two or three coins are inserted, the three horizontal lines or all the five lines including the two diagonal lines become effective, respectively.

Upon actuating a start lever 12 after the insertion of at least a coin, the reels 5 to 7 simultaneously start rotating and thereafter stop at random automatically. When all the reels have stopped, if a combination of symbols on the effective winning line corresponds to one of predetermined hit combinations, a predetermined number of coins are paid out into a coin saucer 11 according to the rank of the obtained hit combination.

The door panel 3 is further provided with a pay-out data reference button 14 and a simulation button 15. When the pay-out data reference button 14 is depressed, data on the paid coins in the past games is displayed as a graphic data on a display 16 disposed at the upper front of the housing 2. The display 16 is a liquid crystal display panel, but may be a small CRT screen.

Figure 2 shows an example of pay-out data displayed upon depression of the pay-out data reference button 14, wherein the horizontal axis represents the accumulated number of inserted coins. The pay-out data X in figure 2 is of the case where more than 2000 coins have been inserted prior to the depression of the pay-out data reference button 14. In this embodiment, the pay-out data X is calculated each time the accumulated number of inserted coins increases by 100, but it is possible to calculate the pay-out data X for each increase of 50 or 25 or another number of inserted coins. Change of the pay-out data X is represented by a curve with using an interpolation, but it is possible to display the data X in another fashion.

Assuming that a number NT1 of coins have been inserted and a number ST1 of coins have been paid out when the pay-out data X is to be calculated, and that a predetermined pay-out rate of the slot machine is K, the pay-out data D can be defined as follows:<maths id="math0001" num=""><math display="block"><mrow><mtext>X = (ST1 / K) - NT1</mtext></mrow></math><img file="EP0443738B2_D0001.tif" /></maths>

In this way, it becomes possible to know about how many coins had been paid out with reference to the number of inserted coins. It may be possible to define the pay-out data X as the difference obtained by the subtraction of the number ST1 from the number NT1. However, when the predetermined pay-out rate of the slot machine is more or less than 100 %, the data curve tends toward upper or lower half of the vertical axis, so that the data value can go over or under the limit values of the scale of the vertical axis. Therefore, it is preferable to take the pay-out rate into account of the pay-out data so as to off-set such a tendency. On the other hand, when the accumulated number of inserted coins NT1 exceeds the maximum of the scale of the horizontal axis, 2000 for instance, it is possible to effect a horizontal scrolling of the display.

The steep curve portion of the pay-out data X in a period J, that is shown by a dashed line, indicates that a large number of coins were paid out for a big hit, e.g. jack pot, in this period J. It is desirable to display the curve of the period J in a specific manner, e.g. in a twinkling fashion, so that the player may gain useful information about the progress of the past coin payments from that slot machine.

The simulation button 15 is depressed to start simulative games and to display hypothetical pay-out data representing the progress of hypothetical coin payments during the simulative games on the display 16 in a manner as shown in figure 3. As described in more detail below, the simulative games are repeated at a high speed independently of the actuation of the start lever 10, and each simulative game is processed on the assumption that three coins were inserted though no coin is actually inserted. The reels 5 to 7 are not rotated during the simulative game and, of course, no coin is paid out even when a simulative game results in a hit game.

The accumulated number of coins assumed to be inserted increases by three as a simulative game is played, while the accumulated number of coins assumed to be paid out increases according to the occurrence of hit games. Assuming that the accumulated number of coins assumed to be inserted is NT2, and that the accumulated number of coins assumed to be paid out is ST2, the hypothetical pay-out data Y is calculated each time 100 hypothetical coins have been inserted, according to the following formulas:<maths id="math0002" num=""><math display="block"><mrow><mtext>Y = (ST2/K) - NT2</mtext></mrow></math><img file="EP0443738B2_D0002.tif" /></maths>    wherein K is the pay-out rate.

The hypothetical pay-out data Y are sequentially displayed after the data Y is calculated as above for each increases of 100 in the number NT2. Because the simulative games are repeated at a high speed, e.g. 100 cycles per second, the player can see what a tendency the slot machine has with respect to coin pay-out probability by observing the display 16 for an appropriate time. Thereafter, by again depressing the simulation button 15, he can terminate the simulative games and start an actual game after the insertion of a number of coins.

Referring now to figure 4 showing circuitry of the slot machine, a microprocessor unit (hereinafter called MPU) 18 controls the start and stop of the rotation of the reels 5 to 7 according to a game program stored in a program ROM 17. Upon actuation of the start lever 10, a start signal generator 19 outputs a start pulse to the MPU 18, which then supplies clock pulses to drivers 20 to 22 provided for the respective reels. The drivers 20 to 22 supply an individual number of drive pulses to the associated stepping motors 24 to 26 thereby to rotate the reels 5 to 7, wherein the number of supplied drive pulses depends on the number of clock pulses supplied to the corresponding drivers.

A RAM 27 includes clock pulse counters counting the respective numbers of clock pulses supplied to the drivers 20 to 22, and the counts of the clock pulse counters are monitored by the MPU 18. Each reel 5, 6, 7 has at its reference position a light-shielding lug 5a, 6a, 7a formed integrally with the reel. Each time the light-shielding lugs 5a, 6a, 7a are detected by photo-interrupters 28 to 30 disposed in association with the respective reels 5 to 7, the corresponding clock pulse counters are reset to zero. Therefore, the count of the clock pulse counter corresponds to a rotational angle during one revolution of the associated reel. Because the symbols disposed on the reels are arranged at a regular intervals in a predetermined sequence with reference to the reference position, it is possible to identify the symbols positioned on the winning line by the counts of the clock pulse counters.

After the start of a game, a random number generated from a random number generator 33 is sampled by the MPU 18 and is stored in a designated address of the RAM 27. The sampled random number is used to decide what rank of hit is to be awarded to the game. The RAM 27 further comprises memory locations for temporary storage of various data or flags provided during the game program execution.

A probability table 31 is referred to for judging the rank of hit assigned to the sampled random number. Assuming that the range of all the random numbers to be generated is from "0" to "9999", the probability table 31 is constructed as a ROM in which all the random numbers are classified into four ranks, namely; the range from "0" to "49" is assigned to a big hit, the range from "50 to 249" to a small hit, the range from "250" to "1499" to a middle hit and the range from "1500" to "9999" to a lost game. Depending on which range the sampled random number belongs to, it is decided whether and what a hit is to be displayed. A pay-out number table 32 is constructed as a ROM storing the number of coins to be paid out for each rank of hit.

A first coin sensor 34 is disposed in a passage way from the coin slot 8 and outputs a detection signal to the MPU 18 when detecting a coin inserted prior to the start of a game. The MPU 18 decides the number of effective winning lines depending on the number of coins inserted for a game. A first coin counter 35 accumulates the number of coins actually inserted for the games throughout operation of the slot machine.

A coin hopper 38 pays out, when a hit is obtained, an appropriate number of coins according to the rank of the hit. The coins paid out from the coin hopper 38 are detected by a second coin sensor 39, so that a second coin counter 40 accumulates the number of coins actually paid out through out the operation of the slot machine. Each time the count of the first coin counter 35 increases by 100, that is, every 100 coins have been inserted, the MPU 18 refers to the count of the second coin counter 40 as to calculate the pay-out data X, and stores the data X in an assigned address of the RAM 27.

When the pay-out data reference button 14 is depressed, a display signal generator 41 outputs a display signal to the MPU 18, which then reads out the pay-out data X from the RAM 27 to display them on the display 16 by driving a LCD driver 37.

When the simulation button 15 is depressed, a simulation signal generator 45 outputs a simulation start signal to the MPU 18, which then activates a first hypothetical coin counter 42 and a second hypothetical coin counter 43. The first hypothetical coin counter 42 counts the number of hypothetical coins that are assumed to be inserted during simulative games, while the second hypothetical coin counter 43 counts the number of hypothetical coins that are assumed to be paid out during simulative games. Each time the count of the first hypothetical coin counter 42 increases by 100, the MPU 18 refers to the count of the second hypothetical coin counter 43 and calculates the hypothetical coin pay-out data Y. The hypothetical coin pay-out data Y calculated in this way are sequentially stored in an individual address of the RAM 27, and are displayed on the display 16 in synchronism with the storage.

Now the operation of the above described slot machine will be described with reference to the flowchart shown in figure 5.

When playing an actual game, the player actuates the start lever 10 after inserting one, two or three coins. The first coin counter 35 counts the number N of coins inserted for this game. Depending on the number N, the number of effective winning lines is decided. The first coin counter 35 also adds the number N to the number ofcoins having been inserted before, thereby to post the accumulated number NT1 of inserted coins. The number N is accumulated in the RAM 27 as another accumulated number NO1.

After sampling a random number from the random number generator 30, the MPU 18 refers to the probability table 31 as to decide whether and which rank of winning is to occur depending on the random number. Then the drivers 20 to 22 are supplied with a series of clock pulses whose frequency gradually increases, whereby the stepping motors 24 to 26 start to rotate the reels 5 to 7. Thereafter, the MPU 18 generates a stop signal at an appropriate timing so that the frequency of the clock pulse gradually decreases and the stepping motors 24 to 26 are controlled to stop. On controlling the stop of the stepping motors 24 to 26, the number of clock pulses supplied to each driver 20, 21, 22, which is counted in the RAM 27, is monitored so that the reels 5 to 7 may stop in a position corresponding to, the decided rank of winning.

When the reels 5 to 7 stop, it is determined what a combination of symbols is positioned on each of the effective winning lines based on the stop positions of the stepping motors 24 to 26. If a combination of symbols comprises a hit combination, then a predetermined number of coins are paid out by referring to the pay-out number table 32.

During the payment of the coins, the second coin sensor 39 outputs a detection signal for each detection of a coin. The detection signals are counted by the second coin counter 40. The second coin counter 40 accumulates the number of coins having been paid out for all the preceding hit games, so that the accumulated number ST1 is posted each time a hit game occur.

Each time the accumulated number NO1 reaches 100, the pay-out data X is calculated and is sequentially stored in the RAM 27, and the number NO1 is cleared to "0". Therefore, the RAM 27 stores pay-out data X calculated for each increase of 100 of inserted coins.

The pay-out data X stored the RAM 27 are sequentially read out by the MPU 18 to be displayed on the display 16 in a manner as shown in figure 2 when the pay-out data reference button 14 is depressed. In this way, the player can see the progress of the past coin payments from the slot machine by depressing the pay-out data reference button 14 before he actually starts a game, so that it becomes possible for the player to select a slot machine among of available slot machines after considering the pay-out data thereof.

On the other hand, when the simulation button 15 is actuated to cause the simulation signal generator 45 to output a simulation start signal to the MPU 18, then a simulation flag "F" is set, and a simulative game is started on the assumption that three coins were inserted. In the simulative game, sampling of a random number, decision of winning rank, and the number S2 of coins to be paid out for the decided rank are performed in the same way as the actual game. The simulative game is performed one after another so far as the simulation button 15 is again depressed.

During the simulative games, the hypothetical number of inserted coins increases by three for each game, and the hypothetical number is accumulated in the first hypothetical coin counter 42 as well as in the RAM. If a hit occurs during the simulative games, the hypothetical number S2 decided with reference to the pay-out number table 32 is accumulated in the second hypothetical coin counter 43. Each time the RAM 27 accumulates the hypothetical number of inserted coins up to 100, the hypothetical pay-out data Y is calculated. The hypothetical pay-out data Y is stored in the RAM 27 and, at the same time, is displayed on the display 16 in a manner as shown in figure 4, wherein the LCD driver 37 is already activated upon depression of the simulation button 15.

The player can see the hypothetical progress of coin payments during the simulative games by observing the display 16. As shown in the flowchart of figure 5, because the random number sampling for the simulative games is performed in a common sequence to the sampling for the actual games, the player can terminate to start an actual game when he predicts based on the hypothetical pay-out data progress that the probability of winning becomes higher. For terminating the simulative games, the player has only to depress again the simulation button 15, then the simulation flag "F" is reset. If, for example, a tendency as shown in figure 3 is observed till the accumulated number of coins assumed to be inserted NT2 reaches 1500, and if the player expects that the following curve will raise as shown by a dashed line, then he may again depress the simulation button 15 to start an actual game.

Although the above description substantially relates to the embodiments shown in the drawings, the present invention should not be limited to these embodiments. It is therefore to be understood that with in the scope of the appended claims the invention may be practiced or embodied in still other way. For example, the pay-out data display 16 may be removably attached to a slot machine. The horizontal axis of the graphic display may represent the number of played games. Furthermore, it is possible to calculate pay-out data according to another formulas, that is, it is possible to display the accumulated number of paid coins itself as the pay-out data for each predetermined number of increase of inserted coins, or to display the transient pay-out rate calculated at regular intervals.

The present invention may be adopted to a video-type slot machine where the symbols are displayed on a CRT screen, wherein it is possible to display pay-out data in a segment of the CRT screen. The present invention may also be adopted to a slot machine with stop buttons wherein the stop control of the reels is executed based on the timing of depression of the stop buttons, or to a credit type or memory card type slot machine wherein coins are not actually inserted in nor paid out from the machine and, instead, the number of coins assigned to be inserted is counted down by a credit counter while the number of coins to be paid out is counted up by the credit counter, whereby the player can cash a check or memory card having recorded with the total of the count.

It is also possible to calculate pay-out data at once prior to the display while the transient accumulated number of paid coins is stored in a RAM each time the accumulated number of inserted coins increases by a predetermined number, instead of calculating pay-out data for each predetermined number of increase of the accumulated number of inserted coins.