Brief Description of the Drawings
The features and advantages of the present invention will become more apparent from the detailed description of the invention that follows, with reference to the accompanying drawings, wherein:
FIG. 1 is a front perspective view of a slot machine embodying the present invention;
FIG. 2 is a schematic view showing an electrical circuit incorporated in the slot machine of FIG. 1;
FIG. 3 is a flow chart showing the events of a game played with the slot machine of this invention; and
FIG. 4 is an explanatory view showing the relation between the number of games played and the prearranged numerical value.
Detailed Description of the Invention
In FIG. 1, which shows a slot machine of the present invention, the slot machine 2 is provided with a front door 2a which can be opened and closed with respect to a main body of the slot machine 2. This front door 2a is provided with stop buttons 3 to 5, a start lever 6, and a coin insertion slot 7. A front panel 8 is mounted on an upper part of the door 2a, above stop buttons 3 to 5, and a first reel 9, a second reel 10 and a third reel 11 are rotatably disposed on a rear side of the front pane 18. Each reel 9 to 11 bears on its outer periphery various symbols such as, for example, "lemon", "7" and "watermelon". These symbols can be observed through three windows 12 to 14 formed in the front panel 8. A plurality of prize-winning lines 16 traverse the respective windows 12 to 14, and the number of the effective lines is increased when a greater number of coins is inserted.
When the start lever 6 is actuated after a coin or coins have been inserted into the coin insertion slot 7, the respective reels 9 to 11 are simultaneously made to start rotating, and the stop buttons 3 to 5 can be actuated after the reels have reached a steady speed of rotation. When the stop buttons 3 to 5 are actuated at a desired time interval, stop control is initiated and the respective reels 9 to 11 are stopped, whereupon a predetermined symbol combination is displayed on the effective prize-winning line 16. But if the symbol combination that stops on the effective prize-winning line 16 is a prize-winning symbol combination, the number of coins corresponding to the prize-winning rank of that combination are paid out into a coin saucer 17. In case no buttons have been actuated within a predetermined period of time, the respective reels 9 are sequentially stopped by an automatic stop mechanism known per se.
In FIG. 2, it will be seen that the electrical circuit of the slot machine 2 comprises blocks representing elements of an operating portion 20, a central processing unit (hereinafter simply referred to as the CPU) 21, a symbol judgment portion 22, a stop control portion 23, and a coin pay-out portion 24.
The operating portion 20 comprises stop switches 3a to 5a which are turned on by the corresponding stop buttons 3 to 5, a start switch 6a which is turned on by the start lever 6, and a coin sensor 7a which is turned on by a coin or coins that are inserted, all of 3a-7a being separately connected to the CPU 21.
The symbol judgment portion 22 has a random number generation circuit 25, a sampling circuit 26, a read/write circuit 27, a symbol decision circuit 28, a win judgment table 29, a memory 30 and a symbol combination table 31 which are all connected in the CPU 21. These tables 29 and 31 comprise a ROM. Upon receipt of a coin detection signal from the coin sensor 7a, the CPU 21 sends a random number generation signal to the random number generation circuit 25 to generate at random numerical values included in a series of integers ranging from 1" to "4096". Thereafter, when a start signal from the start switch 6a is input into the CPU 21, the CPU 21 sends a sampling signal to the sampling circuit 26 for the first game within one cycle in order to cause the sampling circuit 26 to sample one numerical value among the random numbers periodically generated by the random number generation circuit 25. When this sampling is finished, or when the CPU 21 judges that there is in progress a second game or subsequent game, this CPU 21 stops the random number generating circuit 25.
The read/write circuit 27 reads win judgment data (data indicating whether there is a win or not as well as data indicating the rank thereof) stored in the win judgment table 29 based on a numerical value N stored in the memory 30. This numerical value N is a random number or a prearranged numerical value determined on the basis of the random number. The win judgment table 29 shows the relation between the win judgment data and each numerical value constituting a series of numerical values ranging from the minimum numerical value "1" to the maximum numerical value "4096", and the respective numerical values are used as addresses. In this embodiment, although the big win is assigned to the numerical value "4096", the big win may be assigned to "1" as a numerical value at the other end of the series of numerical values. Furthermore, the big win may be assigned to a numerical value in the vicinity either of "4096" or of "1", for example, "4095" or " 2". When win judgment data are sent from the CPU 21 to the symbol decision circuit 28, the symbol decision circuit 28 reads a combination of symbols corresponding to the win judgment data from the symbol table 31 and sends them to the CPU 21 after splitting the same into three symbol signals corresponding to the respective reels 9 to 11.
The stop control portion 23 comprises a stop position decision circuit 35, a motor control circuit 36, drivers 37 to 39, pulse motors 40 to 42 for driving the respective reels 9 to 11, photosensors 46 to 48, and a search circuit 49. The photosensors 46 to 48 are adapted to detect the passage of light shielding element 43 to 45 formed on the respective reels 9 to 11 so as to determine reference positions for the respective reels 9 to 11.
The motor control circuit 36 is adapted to control the driving of the respective pulse motors 40 to 42, and to send driving pulses, which have been fed to the respective pulse motors 40 to 42, to the search circuit 49. The search circuit 49 is adapted to start counting the driving pulses when detection signals are generated from the photosensors 46 to 48 so as to determine the number of driving pulses corresponding to the rotated positions of the respective reels 9 to 11. The search circuit 49, as is known, has a symbol combination table representing the relation between the driving pulses and symbol combinations which are borne by the reels and is adapted to determine the positions of the respective symbols on the rotating reels 9 to 11 from the number of the counted driving pulses. When a stop signal is input from the CPU 21, the stop position decision circuit 35 receives information on the predetermined positions of the respective symbols on the reels 9 to 11 from the search circuit 49, and outputs stop position signals for the respective reels to the motor control circuit 36, so that these symbols will be stopped on the effective prize-winning line 16.
If the time when the stop buttons 3 to 5 are operated is markedly different from the time when the respective reels 9 to 11 are actually stopped, the player might be given an undesirable impression. Therefore, the stopping times are set in a range which will not give such an impression to the player. For example, they are set such that the respective pulse motors 40 to 42 are stopped before the symbols on the respective reels 9 to 11 are moved by more than a few symbols from the time the stop signal is output. Therefore, the combination of symbols decided by the symbol decision circuit 28 is not necessarily accomplished. In case the combination of symbols is, in particular, a big win of a combination of 7-7-7, the request for this big win is carried over to the next game.
A coin pay-out section 24 comprises a pay-out control circuit 55 connected to the CPU 21, and a coin hopper 57 connected to the coin pay-out control circuit 55 through a driver 56. If the combination of symbols is a winning symbol combination after the pulse motors 40 to 42 are all stopped, the pay-out control circuit 55 causes the coin hopper 57 to pay out coins corresponding to the rank of the winning symbol combination.
The operation of the above embodiment will now be described with reference to FIGS. 3 and 4. When a coin or coins have been inserted into the coin insertion slot 7, the CPU 21 actuates the random number generation circuit 25. Then, upon actuation of the start lever 6, the CPU 21 instructs the motor control circuit 36 to start the pulse motors 40 to 42. At the same time, the CPU 21 judges whether the game is a first game with reference to the numerical value "N" stored in the memory 30. In case the numerical value "4096" is stored in the memory 30, the CPU 21 judges it as a first game, and instructs the sampling circuit 26 to sample one number from among random numbers which belong to the series of numerical values ranging from "1" to "4096".
This sampled random number is then stored in the memory 30 as a numerical value "N". If the numerical value N happens to be, say, "251", as shown by way of example in FIG. 4, the CPU 21 accesses the win judgment table 29 through the read/write circuit 27 and reads win judgment data of a small win corresponding to the numerical value "251". Thereafter, the CPU 21 selects three symbols "cherry", "cherry" and "cherry" corresponding to a prize-winning combination comprising a small win, from the symbol table 31 through the symbol decision circuit 28, and sends these symbol signals to the stop position decision circuit 35.
When the respective pulse motors 40 to 42 have reached a steady speed of rotation, it becomes possible to actuate the stop buttons 3 to 5. Thereafter, the respective stop buttons 3 to 5 are actuated, and a stop signal is sent from the CPU 21 to the stop position decision circuit 35. The stop position decision circuit 35 determines a stop position signal for each pulse motor for stopping the symbol "cherry" on the prize-winning line with reference to its current position as detected by the search circuit 49. The motor control circuit 36 stops the pulse motors in accordance with the stop position signals and aligns the symbols "cherry" on the respective reels on the effective prize-winning line 16. When the reels 9 to 11 are all stopped, a combination of symbols "cherry", "cherry" and "cherry" is displayed on the effective prize-winning line 16. In case the stop buttons 3 to 5 are not actuated, the motor control circuit 36 starts the stop control after a predetermined period and stops the pulse motors 40 to 42 so that the predetermined symbol combination will nevertheless be displayed. When all the reels 9 to 11 are stopped, the pay-out control circuit 55 outputs a pay-out signal to the coin hopper 57 to pay out the number of coins corresponding to the winning symbol combination "cherry", "cherry" and "cherry".
When a coin or coins are again inserted into the coin insertion slot 7 and the start lever 6 actuated in order to play a second game, the game is started in the manner previously described. In this second game, the CPU 21 reads the numerical value "251" stored in the memory 30 and then adds "1" to it. If such a sampled numerical value is used as an initial value, an obtained numerical value "252" is the prearranged numerical value which is specifically selected according to the number of times the game has been played and according to the initial value. This numerical value "252" is stored in the memory 30.
The CPU 21 reads win judgment data corresponding to the numerical value "252" from the win judgment table 29 and selects three symbols with reference to the symbol table 31. Then, when the respective stop buttons 3 to 5 are actuated, the stop control of the pulse motors 40 to 42 is effected to display the predetermined symbol combination. As this symbol combination is not a win, no coins are paid out.
The game is continued in this way. When the number of games played reaches a total of (4096-250), the numerical value N of this game becomes the maximum value "4096". Since this numerical value "4096" is a big win, the stop control of the reels 9 to 11 is executed such that a symbol combination 7-7-7 is displayed on the effective prize-winning line, provided that the timing of the operation of the stop buttons 3 to 5 is within a proper range. In this case, a large number of coins are paid out from the con hopper 57. When this big win is awarded, one cycle of games is finished. When a coin or coins are next inserted, the first game in the next cycle is started and selection of the initial numerical value is performed with random numbers as previously mentioned.
If a big win is not awarded, due to the timing of the operation of the stop buttons 3 to 5, then the numerical value "4096" is carried over to the next game. This process is continued until the big win is awarded, so that a big win will necessarily be awarded by the end of one cycle of games.
Although the prearranged numerical value in the above-described embodiment is found by successively adding "1", it may proceed toward "4096" by alternately performing addition and subtraction. For example, the prearranged numerical value may be found by adding "3" in one game and by subtracting "1" in the next game. If the big win is assigned to the minimum value "1", it may proceed to the minimum value "1" only by subtraction or by alternate subtraction and addition. Also, in the above-described embodiment, the present invention is applied to a manually stopped slot machine. However, the present invention may be likewise applied to an automatically stopped slot machine with no stop buttons, or, as mentioned, to a video type slot machine. Furthermore, instead of paying out coins each time the win occurs, there may be provided a credit counter so that obtained coins are added up and that the sum is displayed on a display device. In this case, when the start lever is actuated without inserting a coin or coins, the next game is started and, at the same time, the credit counter is subjected to subtraction processing.
It is to be understood that the present invention can be changed, altered and modified to various forms without departing from the scope of the invention.