Patent Publication Number: US-2009227327-A1

Title: Slot Machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of U.S. Provisional Application No. 61/034,638 filed on Mar. 7, 2008. The contents of this application are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a slot machine. 
     2. Description of the Related Art 
     Slot machines known as a type of gaming machines are constituted so as to: start games by players inserting coins or the like into the gaming machine; rearrange columns of symbols in predetermined region of the gaming machine; and award a prize based on a combination of rearranged symbols. 
     In addition, the above slot machines are generally constituted to judge whether or not a winning combination allowed to award a prize is established, based on whether or not a predetermined number of symbols of the same type (for example, “CHERRY” or “7”) are arranged along a preset payline. In the conventional slot machine, in a case where a predetermined number or more of symbols of the same type are arranged, it has been a common routine to award a prize based on the number of the aforementioned arranged symbols, regardless of the payout line. 
     Further, many of the conventional slot machines have been known which alternately conduct two types of games, i.e., a basic game and a free game. The basic game is executed upon consumption of inserted gaming values, namely, a credit. On the other hand, the free game is executed without consuming a credit. 
     It is a common routine to perform control to switch the basic game to the free game when the predetermined condition is met. The condition includes a case in which, for example, a combination of predetermined symbols is rearranged during the basic game. The free game is switched to the basic game when the predetermined condition is met. The condition includes a case in which, for example, the free games are executed by a predetermined number of times or which a combination of predetermined symbols is rearranged and a prize is awarded. 
     In the conventional slot machines, it has been a common routine to change arrangement of symbols at the time of switching to the free game so as to raise players&#39; feeling of expectation that a combination of predetermined symbols would be rearranged. For example, U.S. Pat. No. 6,394,902-B1 describes a video-reel slot machine in which a total of fifteen symbols are displayed on a matrix display in three rows and five columns. This slot machine decreases types of symbols arranged on reels from eight to five types at the time of switching to the free game. In this manner, a control is performed to raise the possibility of establishing a combination allowed to award a prize during the free game. 
     Further, a bonus prize is set that is awarded in a case where a combination of special symbols is rearranged, in which a big prize, namely, so-called jackpot is awarded, thereby enhancing entertainability of the slot machine. 
     The possibility of winning this jackpot, however, is kept low. Therefore, there is an aspect that players consider the jackpot as no more than an accidentally-winnable prize. 
     The present invention has been made in view of the above-described circumstance. It is an object of the present invention to provide a novel slot machine and a controlling method thereof for providing higher entertainability by performing game control that enables players to raise expectations for establishment of the jackpot. 
     SUMMARY OF THE INVENTION 
     A first aspect of the present invention is a slot machine including: a display device having a symbol display region for displaying plural types of symbols in a matrix form; an input device for accepting BET; a first memory for cumulatively storing a bonus point which is awarded, in a case where a predetermined number or more of first symbols contained in the plural types of symbols are rearranged in the symbol display region; a second memory for cumulatively storing at least one part of a credit which is bet through the input device; and a controller for controlling the display device, the input device, the first memory, and the second memory. The controller is programmed to (a) execute a basic game; (b) rearrange the plural types of symbols in the symbol display region during the basic game; (c) add the bonus point to a cumulative value of the first memory during the basic game; (d) add the credit to a cumulative value of the second memory during the basic game; (e) execute a free game, in a case where a predetermined condition is met during the basic game; (f) execute a bonus game by a number of times equal to the cumulative value of the bonus points stored in the first memory, during a predetermined period from before start to after termination of the free game; and (g) award a prize determined based on the cumulative value of the second memory, in a case where a second symbol displayed in the symbol display region met a predetermined condition during the bonus game. 
     According to the first aspect of the present invention, when a predetermined number or more of the first symbols are rearranged during the basic game, the bonus point as a right to execute the bonus game is awarded, and the bonus game is executed by the equal number of times to a cumulative value of bonus points. In a case where the second symbol is rearranged on a symbol display screen under a predetermined condition, a so-called jackpot is awarded. If the bonus point is won in the basic game, players are conscious that the bonus game, which possibly awards the jackpot, may be executed later, thereby being allowed to play the game with expectations. Entertainability of the slot machine is enhanced by adding the above bonus game. 
     A second aspect of the present invention is a slot machine constituted as set fourth below. In the first aspect, the controller, in the itemized (g), determines plural types of prizes based on the cumulative value of the second memory and, awards the prize according to an outcome of the bonus game. 
     A third aspect of the present invention is a slot machine constituted as set forth below. In the first aspect, the controller, in the itemized (f), executes the bonus game that the plural types of symbols containing the second symbol are rearranged. 
     According to the above aspects, when the second symbol indicative of a so-called jackpot is rearranged in the symbol display region under a predetermined condition, the jackpot is awarded. The second symbol may change depending on a grade of the awarded prize. In a case where the payout increases in the order of MIN, MEJOR, and MEGA, for example, the symbols may be prepared correspondingly to those prizes, respectively. 
     A fourth aspect of the present invention is a slot machine constituted as set forth below. In the first aspect, the controller, in the itemized (f), terminates the bonus game without execution of remaining bonus games during the plural bonus games, in a case where the second symbol is rearranged before a last bonus game. 
     Even where the bonus game is continued after the second symbol is rearranged under a predetermined condition and the jackpot is awarded, the jackpot is not awarded again, so that it is rational for even the player to complete the bonus game. 
     A fifth aspect of the present invention is a slot machine constituted as set forth below. In the first aspect, the controller, in the itemized (f), rearranges a plurality of cards on which the symbols containing the second symbol are drawn, in the symbol display region in a state where the symbols are invisible, and executes the bonus game that the equal number of cards to the cumulative value of the second memory are switched in a state where the symbols are visible. 
     During the bonus game, the slot machine with the above structures switches a screen from a symbol display screen to a card display screen in which the plurality of cards are displayed. It is preferable that the displayed cards have common patterns such as those on back surfaces of trump or tarot cards so that the respective cards are not visually distinguishable by the players. The player selects and designates the card while the processor changes the pattern of the designated card in a manner to display the symbol. In a case where the pattern after changed corresponds to the pattern indicative of a so-called jackpot, which meets a predetermined condition, the jackpot is awarded. The pattern of the second symbol may be distinguished depending on a grade of the prize to be awarded. In a case where the payout increases in the order of MIN, MEJOR, and MEGA, for example, the patterns may be prepared correspondingly to those prizes, respectively. 
     A sixth aspect of the present invention is a slot machine constituted as set forth below. In the first aspect, the slot machine further includes an input device for accepting entry of side BET. The controller, in the itemized (b), rearranges the first symbol in the symbol display region upon accepting the entry of the side BET from the input device. 
     According to the above aspect, the first symbol is rearranged only where a credit is entered upon the side BET. Therefore, the player who does not place the side BET cannot win the bonus point because the first symbol is not rearranged during the basic game, thereby not being able to execute the bonus game. Under a control as described above, fairness between the player who places the side BET and the player who does not can be maintained in a case of setting the game that the jackpot is financed by the credit from the side BET. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing an exemplary symbol matrix during a basic game according to a first embodiment; 
         FIG. 2  is a perspective view schematically showing an appearance of a slot machine according to the first embodiment; 
         FIG. 3  is a block diagram depicting an internal construction of the slot machine shown in  FIG. 2 . 
         FIG. 4A  is a view showing an exemplary symbol matrix displayed during the basic game according to the first embodiment; 
         FIG. 4B  is a view showing an exemplary symbol matrix displayed during the basic game according to the first embodiment; 
         FIG. 5A  is a view showing an exemplary image displayed during the free game in the slot machine shown in  FIG. 2 ; 
         FIG. 5B  is a view showing an exemplary symbol matrix during the free game according to the first embodiment; 
         FIG. 6A  is a view showing an exemplary image displayed during the free game in the slot machine shown in  FIG. 2 ; 
         FIG. 6B  is a view showing an exemplary symbol matrix during the free game according to the first embodiment; 
         FIG. 7  is a flowchart showing a subroutine of a main process according to the first embodiment; 
         FIG. 8  is a flowchart showing a subroutine of a game execution process according to the first embodiment; 
         FIG. 9  is a flowchart showing a subroutine of a basic game symbol rearrangement process according to the first embodiment; 
         FIG. 10  is a flowchart showing a subroutine of a bonus game symbol rearrangement process according to the first embodiment; 
         FIG. 11A  is a view showing an exemplary card display screen during a bonus game according to the first embodiment; 
         FIG. 11B  is a view showing an exemplary card display screen during the bonus game according to the first embodiment; 
         FIG. 12  is a flowchart showing a subroutine of the bonus game execution process according to the first embodiment; 
         FIG. 13  is a perspective view schematically showing an appearance of a slot machine according to a second embodiment; 
         FIG. 14A  is a view showing an exemplary symbol matrix during a basic game according to the second embodiment; and 
         FIG. 14B  is a view showing an exemplary symbol matrix during the basic game according to the second embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First, a slot machine  10  (see  FIG. 2 ) according to a first embodiment will be described with referring to the drawings. The slot machine according to the first embodiment is a so-called video slot machine, which has an image display panel such as a liquid crystal display and executes a game by displaying images of various symbols on the image display panel. The slot machine  10  according to the present invention executes two gaming modes alternately. The two gaming modes include a basic game and a free game. The basic game is executed upon consumption of inserted gaming values bet by players, namely, a credit. The free game is executed without consuming the credit. When a right to execute a bonus game is stored at the time of shifting a game from the basic game to the free game when the predetermined condition is met, a chance for winning the jackpot is given upon execution of the bonus game. The slot machine  10  is of a stand-alone type, which is not connected to a network, the present invention is also applicable to a networked slot machine. 
       FIG. 1  is a view showing an exemplary display of a symbol matrix during a basic game according to the first embodiment. The symbol matrix  28  is displayed on a lower image display panel  16  described later, included in the slot machine  10 . The symbol matrix  28  is made up of cells in three rows and five columns, in which the symbols can be rearranged. In the cells in  FIG. 1 , symbols “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, and “CHANCE  70   a ” are rearranged. 
     As shown in  FIG. 1 , in a case where three symbols “CHANCE  70   a ” are rearranged in the symbol matrix during the basic game, an icon “BONUS  70   e ” is displayed in a blinking state in an effect image display region  94  (see  FIGS. 4A and 4B ) right above the symbol matrix. Next to the icon “BONUS  70   e ”, an icon “BONUS  70   d ” is displayed, which indicates that more than three symbols “CHANCE  70   a ” had been rearranged prior to a previous game. Specifically, every time when three or more symbols “CHANCE  70   a ” are rearranged, the icon “BONUS  70   e ” is displayed cumulatively in the display region  94 . The number of icons “BONUS  70   e ” displayed in the display region  94  is a bonus point, which indicates acquisition of a right to execute the bonus game by the equal number of times to the number of icons  70   e.    
       FIG. 2  is a view schematically depicting an appearance of an appearance of the slot machine according to the first embodiment. The gaming media used in the slot machine  10  include coins, bills, or electronic value information equivalent thereto. In the present invention, however, the gaming media are not limitative thereto in particular, and can include medals, tokens, electric money, and tickets, for example. The above tickets are not limitative in particular, and can include barcode-attached tickets or the like, as described later, for example. 
     The slot machine  10  is provided with a cabinet  11 , a top box  12  installed on an upper side of the cabinet  11 , and a main door  13  provided on a front surface of the cabinet  11 . 
     The lower image display panel  16  serving as a display device is provided in front of the main door  13 . The lower image display panel  16  is provided with a liquid crystal panel, which displays the cells of the symbol matrix  28  in three rows and five columns. A single symbol is arranged in each of the cells of the symbol matrix  28 , and the maximum of fifteen symbols can be displayed. 
     A credit amount display section  31  of the lower image display panel  16  displays a credit corresponding to the number of inserted coins by way of an image. A payout amount display unit  32  displays by way of an image, a combination of rearranged symbols or the number of coins to be paid if the predetermined number of symbols are rearranged. 
     Provided on the lower side of the lower image display panel  16  at a center of the main door  13  is a control panel  20  on which a plurality of buttons  23  to  27  and  85  through which command regarding the process of the game is entered, a coin receiving slot  21  for receiving coins into the cabinet  11 , and bill validator  22  are disposed. 
     On the control panel  20 , a start button  23 , a change button  24 , a cashout button  25 , a 1-BET button  26 , a MAX-BET button  27 , and a side-BET button  85  are provided. The start button  23  is intended for entering a command for starting the game. The change button  24  is intended for use in asking an attendant of the gaming facility for change. The cashout button  25  is intended for entering a command for paying out the credited coins to a coin tray  18  through a coin payout exit  19 . 
     The 1-BET button  26  is intended for entering a command for betting a credit corresponding to one coin. The MAX-BET button  27  is intended for entering a command for betting the maximum number (fifteen in this embodiment) of coins that can be bet per game. The side-BET button  85  is used to place a bet on a sub game other than a game in which symbols are rearranged in the symbol matrix  28 . In this embodiment, for example, control can be performed to rearrange the symbol “CHANCE  70   a ” in the symbol matrix  28  when the predetermined credit is bet. A part of credit that has been bet through those input units are cumulatively stored in a memory region provided in a RAM  43  and are used as the reference to determine the amount of payout in a case where the jackpot is won during the bonus game. 
     The bill validator  22  validates whether or not a bill is legitimate and accepts a legitimate bill into the cabinet  11 . The bill validator  22  may be configured so that a barcode-attached ticket  39  described later is readable thereby. Provided on a lower front surface of the main door  13 , that is, at a lower part of the control panel  20 , is a berry glass  34  on which characters of the slot machine  10  and the like are depicted. 
     On a front surface of the top box  12 , an upper image display panel  33  is provided. The upper image display panel  33  has a liquid crystal panel, which displays images for introducing the game contents or explaining game rules, for example. 
     Also, on the top box  12 , a speaker  29  and a lamp  30  are provided. On a lower side of the upper image display panel  33 , a ticket printer  35 , a card reader  36 , a data display unit  37 , and a key pad  38  are provided. The ticket printer  35  prints on the ticket, a barcode having encoded thereon data such as the credit amount, the date and time, and the identification number of the slot machine  10 , and outputs the printed ticket as the barcode-attached ticket  39 . The player can play the game on another slot machine with the barcode attached ticket  39  by causing this slot machine to read the barcode attached ticket  39 . Alternatively, the player can exchange the barcode-attached ticket  39  with the bills or the like at a predetermined place (at a cashier inside a casino, for example) of the gaming facility. 
     The card reader  36  reads data from and writes data into a smart card. The smart card is to be owned by the player, which stores data for identifying the player or data regarding the log of games executed by the player, for example. The smart chard may store data corresponding to coins, bills, or a credit. As an alternative of a smart card, a magnetic stripe card may be employed. The data display  37  is made up of a fluorescent display and the like, and displays the data read by the card reader or the data input by the player through the key pad  38 , for example. The key pad  38  inputs data and commands regarding the ticket issuance or the like. 
       FIG. 3  is a block diagram depicting the internal construction of the slot machine shown in  FIG. 2 . A gaming board  50  includes: a CPU (Central Processing Unit)  51 , a ROM (Read Only Memory)  55  and a boot ROM  52  interconnected by an internal bus; a card slot  53 S corresponding to a memory card  53 ; and an IC socket  54 S corresponding to a GAL (Generic Array Logic)  54 . 
     The memory card  53  contains therein a nonvolatile memory and stores game programs. The game programs include a symbol selection program. The aforementioned symbol selection program is intended for determining the symbols to be rearranged in the symbol matrix  28 . The aforementioned symbol selection program includes symbol weighing data respectively corresponding to plural types of payout ratios (80%, 84%, and 88%, for example). The symbol weighting data is indicative of the correspondence relationship between the respective symbols and one or more random numeric values which come under a predetermined numerical range (0 to 255). The payout ratio is determined according to the payout-ratio setting data output from the GAL  54 . The symbols to be rearranged in the symbol matrix  28  are determined depending upon the symbol weighing data corresponding to this payout ratio. Further, the game programs include table data indicating the correspondence relationship between each of the symbols and a payout. 
     Also, the card slot  53 S is configured to allow the memory card  53  to be inserted thereinto or ejected therefrom, and is connected to a mother board  40  through IDE pass. Accordingly, the memory card  53  can be ejected from the card slot  53 S, other game programs and other game system programs can then be written into the memory card  53 , and further, the memory card  53  can be inserted into the card slot  53 S, thereby allowing the player to change the types and contents of games executed in the slot machine  10 . The game program includes data concerning a game progress. Furthermore, the game program includes image data or sound data to be output during the game. The image data include, for example, image data indicative of the symbol matrix  28 . 
     The GAL  54  is a type of a PLD having a fixed OR array structure. The GAL  54  includes plural input ports and plural output ports. Where predetermined data is input to the input port, the GAL  54  outputs data corresponding to the aforementioned data from the output port. The data output from this output port is equivalent to the aforementioned payout-ratio setting data. Further, the IC socket  54 S is configured to allow the GAL  54  to be attached thereto and detached therefrom, and is connected to the mother board  40  by a PCI bus. Accordingly, the GAL can be replaced with the replacement GAL  54  to change the payout-ratio setting data. 
     The CPU  51 , the ROM  55 , and the boot ROM  52  interconnected by the internal bus are connected to the mother board  40  by the PCI bus. The PCI bus serves to transmit signals between the mother board  40  and the gaming board  50  and supply power from the mother board  40  to the gaming board  50 . 
     The mother board  40  is constructed using a general-purpose mother board commercially available (a printed circuit board on which essential parts of a personal computer are mounted) and includes: a main CPU (Central Processing Unit)  41 , a ROM (Read Only Memory)  42 ; a RAM (Random Access Memory)  43 ; and a communication interface  44 . 
     The ROM  42  stores thereon a program such as BIOS (Basic Input/Output System) executed by the main CPU  41 , and permanent data. When the BIOS is executed by the main CPU  41 , processing of initializing predetermined peripheral devices is carried out and processing of capturing game programs and game system programs stored in the memory card  53  through the gaming board  50  is started. In the present invention, the contents of the ROM  42  may be rewritable or not. 
     The RAM  43  stores data and a program used when the main CPU  41  is activated. The RAM  43  can also store game programs. The RAM  43  further stores data concerning the credit amount, the number of coin-in or coin-out for one game, and the like. In embodiments of the present invention, the RAM  43  stores bonus points cumulatively. 
     Both a main body PCB (Printed Circuit Board)  60  and a door PCB  80  are connected to the mother board  40  by USB. A power supply unit  45  is also connected to the mother board  40 . 
     Connected to the main body PCB  60  and the door PCB  80  are: equipment and devices which generate input signals to be input to the main CPU  41 ; and equipment and devices of which operations are controlled by a control signal output from the main CPU  41 . The main CPU  41  executes a game program stored in the RAM  43  based on an input signal having been input to the main CPU  41  and performs a predetermined computational process, thereby storing results thereof in the RAM  43  or transmitting a control signal to each of equipment and devices as a control process therefor. 
     A lamp  30 , a hopper  66 , a coin detecting section  67 , a graphic board  68 , a speaker  29 , a touch panel  69 , the bill validator  22 , the ticket printer  35 , the card reader  36 , a key switch  38 S, and the data display unit  37  are connected to the main body PCB  60 . The lamp  30  is lit up in a predetermined pattern based on a control signal output from the main CPU  41 . 
     The hopper  66  is installed in the cabinet  11  and pays out a predetermined number of coins from the coin payout exit  19  to the coin tray  18  based on a control signal output from the main CPU  41 . The coin detecting section  67  is installed inside the coin payout exit  19  and outputs an input signal to the main CPU  41  upon detecting that a predetermined number of coins have been paid out from the coin payout exit  19 . 
     The graphic board  68  controls, based on a control signal output from the main CPU  41 , images to be displayed on the upper image display panel  33  and the lower image display panel  16 . The credit amount stored in the RAM  43  is displayed on a credit amount display section  31  (see  FIG. 2 ) of the lower image display panel  16 . The number of coins to be paid out is displayed at a payout amount display section  31  (see  FIG. 2 ) of the lower image display panel  16 . The graphic board  68  is equipped with a VDP (Video Display Processor) which generates image data based on a control signal output from the main CPU  41  and a video RAM which temporarily stores image data generated by the VDP, and the like. The image data used in generating image data with VDP is contained in the game program read from the memory card  53  and stored in the RAM  43 . 
     The bill validator  22  validates whether or not a bill is legitimate and accepts a legitimate bill into the cabinet  11 . Upon accepting a legitimate bill, the bill validator  22  outputs an input signal to the main CPU  41  based on the amount of the bill. The main CPU  41  stores in the RAM  43  the credit amount corresponding to the amount of bills transmitted by the input signal. 
     Based on a control signal output from the main CPU  41 , the ticket printer  35  prints on a ticket a barcode having encoded thereon data such as the credit amount, data and time, and the identification number of the slot machine  10  stored in the RAM  43 . Further, this printer outputs the printed ticket as a barcode-attached ticket  39 . The card reader  36  transmits to the main CPU  41  the data read from the smart card and writes the read data onto the smart card, based on a control signal from the main CPU  41 . The key switch  38 S is provided on the keypad  38 , and outputs a predetermined input signal to the main CPU  41  when the player operates the key pad  38 . The data display  37 , based on a control signal output from the main CPU  41 , displays the data read by the card reader  36  and the data input by the player through the key pad  38 . 
     The control panel  20 , a reverter  21 S, a coin counter  21 C, and a cold cathode tube  81  are connected to the door PCB  80 . The control panel  20  is provided with: a start switch  23 S corresponding to the start button  23 ; a change switch  24 S corresponding to the change button  24 ; a cashout switch  25 S corresponding to a cashout button  25 ; a 1-BET switch  26 S corresponding to a 1-BET button  26 ; a MAX-BET switch  27 S corresponding to the MAX-BET button  27 ; and a side-BET switch  90 S corresponding to the side-BET switch  85 . When the player operates the buttons  23  to  27  and  85 , the corresponding switches  23 S to  27 S and  90 S output input-signals to the main CPU  41 , respectively. 
     The coin counter  21 C is provided inside the coin receiving slot  21 , and validates whether or not a legitimate coin is inserted into the coin receiving slot  21 . Those other than the legitimate coins are discharged from the coin payout exit  19 . The coin counter  21 C outputs an input signal to the main CPU  41  when a legitimate coin is detected. 
     The reverter  21 S operates based on a control signal output from the main CPU  41  and distributes coins recognized as being legitimate by the coin counter  21 C into a cash box (not shown in the drawings) or the hopper  66  which is arranged in the slot machine  10 . In other words, when the hopper  66  is filled with coins, legitimate coins are distributed by the reverter  21  S into the cash box. On the other hand, when the hopper  66  is not filled with coins, legitimate coins are distributed into the hopper  66 . The cold cathode tube  81  functions as a backlight installed on rear face side of each of the lower image display panel  16  and the upper image display panel  33 , and is lit up based on a control signal output from the main CPU  41 . 
       FIGS. 4A to 6B  are views each showing an exemplary image displayed on an image display panel of the slot machine  10  shown in  FIG. 2  according to the first embodiment.  FIGS. 4A and 4B  are views each showing an exemplary image displayed during a basic game in the slot machine shown in  FIG. 2 . 
     As shown in  FIG. 4A , the lower image display panel  16  is made up of a display region  92 , an information display section  93 , the effect image display section  94 , and the like. The symbol matrix  28  is displayed in the display region  92 . On both sides of the symbol matrix  28 , the icons indicative of the number of coins that have been bet are arranged, and control is performed to blink the icon corresponding to the bet amount. The information display section  93  is arranged upwardly of the display region  92  and is made up of a credit amount display section  93   a,  a BET amount display section  93   b,  a character information display section  93   c,  a PAID amount display section  93   d,  and a charge display section  93   e.    
     The number of coins currently credited is displayed at the credit amount display section  93   a  while the number of coins bet on one game is displayed at the BET amount display section  93   b.  The character information indicative of a current status of the game is displayed at the character information display section  93   c.  The characters of “PLAYNOW” are displayed during the play of the game, whereas the characters of “GAMEOVER” are displayed during the intervals between the plays of the game. The number of coins that have been paid out in one game is displayed at the PAID amount display section  93   d,  whereas a conversion value of the credit amount based on a predetermined amount of money is displayed at the charge display section  93   e.    
     The effect image display section  94  displays effect images according to a type of the slot game. In other words, the effect image display section  94  displays different effect images between the basic and free games. 
     Any of symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, and “CHANCE  70   a ” are rearranged in the elements of the symbol matrix displayed on the lower image display panel  16 . A payout is determined based on the number of these symbols rearranged in the symbol matrix. 
       FIG. 4A  is a view showing a case where the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, and “CHANCE  70   a ” are rearranged in the symbol matrix  28  during the basic game. The single symbol “CHANCE  70   a ” is rearranged, which does not meet the condition to win the bonus point, so that the icon “BONUS  70   d ” is not displayed in the effect image display section  94 . On the other hands, the two symbols “main character  121 ” are displayed, each of which serves a trigger to switch the basic game to the free game. The condition to start the free game is met when three or more symbols “main character  121 ” are rearranged. This condition is not met in this case, thereby not starting the free game. 
       FIG. 4B  is a view for showing an exemplary image displayed during the basic game in the symbol matrix  28 , relating to determination of start of the free game. In the drawing, the three symbols “main character  121 ” are displayed in the symbol matrix  28 . The condition to start the free game is met in this case, so that a switch to the free game is determined. At this time, timing for executing the bonus game is also determined independently from the free game. Specifically, in a case where the three or more symbols “CHANCE  70   a ” are rearranged during the basic game, thereby winning the bonus point, control is performed to execute the bonus game at any time before, during, or after the free game. In the first embodiment of the present invention, the bonus game is executed after the free game (see a flowchart of the game execution process in  FIG. 8 ). In the case shown in  FIG. 4B , the five icons “BONUS  70   d ” are displayed in the effect image display section  94 , which indicates that the five bonus points are won. Therefore, the bonus game is executed five times. 
       FIGS. 5A ,  5 B are views each showing an exemplary image displayed on the upper image display panel  33  and the lower image display panel  16  during the free game. In a case where start of the free game is determined, a display image  90   b  in  FIG. 5A  is displayed on the upper image display panel  33 . On the other hand, the display region  92  of the lower image display panel  16  displays the symbol matrix  28  in  FIG. 7B . The five icons “BONUS  70   d ” are displayed in the effect image display section  94 , which indicates acquisition of a right to execute the bonus game five times. 
       FIGS. 6A ,  6 B are views each showing an exemplary image displayed on the upper image display panel  33  and the lower image display panel  16  during the bonus game. When the bonus game is started, the display image  90   b  in  FIG. 6A  is displayed on the upper image display panel  33 , which indicates that the bonus game is in execution. On the other hand, the display region  92  of the lower image display panel  16  displays the symbol matrix  28 .  FIG. 6B  shows an exemplary display of the lower image display panel  16 , in which the two icons “BONUS  70   d ” are displayed in the effect image display section  94 , which indicates acquisition of a right to execute the two remaining bonus games. On the other hand, the seven bonus symbols “sub character  122 ” are displayed in the symbol matrix  28 . The symbols more than three, which is the condition for establishment of the bonus, are rearranged, thereby awarding the jackpot. In this case, the remaining two bonus games are not executed and the bonus points are canceled, thereby terminating the bonus game. 
     Next, a process executed in the slot machine  10  according to the first embodiment, will be described in detail with reference to the drawings. The main CPU  41  controls the progress of a game by reading out of the RAM  43  and executing the game program. 
       FIG. 7  is a flowchart showing a subroutine of a main process. In the main process, first, when a power switch is turned on (that is, when power is supplied), a mother board  40  and a gaming board  50  are activated respectively, so that the CPU  51  executes an initial setting process (step S 101 ). In this initial setting process, the main CPU  41  executes the BIOS stored in the ROM  42 , decompresses, in the RAM  43 , compressed data included in the BIOS, executes the BIOS decompressed in the RAM  43 , and performs diagnosis and initialization of each of the peripheral devices. The main CPU  41  writes game programs or the like from memory card  53  into the RAM  43 , and retrieves data for setting a payout ratio and country-identification information. The main CPU  41  also performs an authentication process for each program during execution of the initial setting process. 
     Next, the main CPU  41  performs a game execution process described later with reference to  FIG. 8  (step S  102 ). In this game execution process, the main CPU  41  sequentially reads and executes the game programs or the like from the RAM  43 . By performing this game execution process, the slot machine  10  according to the first embodiment executes the game. The game execution process is repeatedly performed while power is supplied to the slot machine  10 . 
       FIG. 8  is a flowchart showing a subroutine of the game execution process invoked and performed at step S 102  of the subroutine shown in  FIG. 7 . First, the main CPU  41  judges whether a coin has been bet or not (step S 201 ). Specifically, the main CPU  41  judges whether or not an input signal has been received. The input signal is output from the 1-BET switch  26 S at the time of operation of the 1-BET button  26  or output from the MAX-BET switch  27 S at the time of operation of the MAX-BET button  27 . The main CPU  41  controls the current step to return to the process at step S 201  upon judging that no coin has been bet (step S 201 : NO). 
     Next, the main CPU  41  subtracts the number of bet coins from the credit amount stored in the RAM  43  (step S 202 ) upon judging that a coin has been bet (step S 201 : YES). Where the number of bet coins is larger than the credit amount stored in the RAM  43 , the main CPU  41  controls the current step to return to step S 201  without performing the process for subtracting the number of bet coins from the credit number stored in the RAM  43 . Where the number of bet coins exceeds the upper limit ( 50  coins in this embodiment) of coins that can be bet in one game, the main CPU  41  controls the step to return to step  203  without performing the process for subtracting the number of bet coins from the credit number stored in the RAM  43 . 
     The main CPU  41  judges whether or not the start button  23  has been set to ON (step S 203 ). Specifically, the main CPU  41  judges whether or not an input signal output from the start switch  23 S at the time of pushing of the start button  23  has been received. The main CPU  41  controls the step to return to step  201  upon judging that the start button  23  has not been set to ON (step S 203 : NO). Where the start button  23  has not been set to ON (for example, where an instruction has been input to terminate the game without setting the start button  23  to ON), the main CPU  41  cancels acceptance of a subtraction result at step S 202 . 
     On the other hand, the main CPU  41  performs a symbol rearrangement process (step S 204 ) upon judging that the start button  23  has been set to ON (step S 203 : YES). Specifically, the CPU  41  executes the program stored in the RAM  43  and determines the symbols to be rearranged in the symbol matrix. The symbols are selected from among the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, “CHANCE  70   a ”, and “blank”. This determination is based on the symbol weighting data and random numeric values sampled by sampling the random numeric values in a numerical range which comes under a predetermined range of random numeric values. The CPU  41  then rearranges the symbols in the symbol matrix. 
     Next, the main CPU  41  judges whether a prize has been established or not (step S 205 ). Specifically, the main CPU  41  judges whether or not a combination of symbols rearranged in the symbol matrix  28  results in a winning combination allowed to award any of payouts. Herein, the prize is established on condition that the three or more symbols of the same type are rearranged in the symbol matrix  28 . 
     Next, upon judging that the prize is established (step S 205 : YES), the main CPU  41  performs a predetermined coin-payout process (step S 206 ). In the coin-payout process, the main CPU  41  transmits the control signal to the hopper  66  to pay out the predetermined amount of coins. The CPU  41  may control the process to add the credit corresponding to the coins to be paid out to the credit amount stored in the RAM  43 . 
     Next, the CPU  41  judges whether a free game trigger condition has been met or not (step S 207 ) when judging that the prize is not established (step S 205 : NO) or after executing the payout process at step S 206 . Specifically, the main CPU  41  executes the program stored in the RAM  43  to sample the random numeric values in a numerical range which comes under a predetermined range of random numeric values, thereby judging whether or not the symbol “main character  121 ” is rearranged based on the sampled random numeric values. The main CPU  41  then counts the number of the rearranged symbols “main character  121 ” and judges that the free game trigger condition is met when the three or more symbols “main character  121 ” are rearranged. The main CPU  41  performs the free game execution process (step S 208 ) when judging that the free game trigger condition is met (step S 207 : YES). In this free game execution process, the main CPU  41  reads and executes game programs or the like out of the RAM  43  in sequence, thereby executing the free game execution process. The main CPU  41  then executes the bonus game execution process, which will be explained later with reference to  FIG. 10  (step S 209 ). On the other hand, the main CPU  41  terminates the game execution process when judging that the free game trigger condition is not met at step S 207  (step S 207 : NO) or when executing the process at step S 209 . 
       FIG. 9  is a flowchart showing a subroutine of a symbol rearrangement process which is invoked and executed at step S 204  of the subroutine shown in  FIG. 8 . First, the main CPU  41  displays the symbols in a scrolling manner (step S 301 ). Specifically, the main CPU  41  executes the program stored in the RAM  43  to perform a virtual display of an effect image that is virtually recognized as if the symbols are scrolled at high speed in a downward direction of a column of the symbol matrix. 
     The main CPU  41  then judges whether or not the side-BET button  85  has been set to ON (step S 302 ). Specifically, the main CPU  41  judges whether or not the input signal has been received, the signal being output from the side-BET switch  90 S when the side-BET button  85  is pressed. Upon judging that the side-BET button  85  has been set to ON (step S 302 : YES), the main CPU 41  executes a process at step S 303 . Upon judging that the side-BET button  85  has not been set to ON (step S 302 : NO), the main CPU  41  executes a process at step S 304 . 
     The main CPU  41  selects a group of symbols containing the symbol “CHANCE  70   a ” from among a plurality of groups of symbols stored in the RAM  43 . On the other hand, the CPU  41  selects the group of symbols not containing the symbol “CHANCE  70   a ” from among the plurality of groups of symbols stored in the RAM  43 . In this manner, control is performed to rearrange the symbol “CHANCE  70   a ” in the symbol matrix  28  only when the side-BET has been placed. 
     The main CPU  41  then rearranges the symbols selected at step S 304  or S 305 , in the symbol matrix (step S 305 ). Specifically, the main CPU  41  executes the program stored in the RAM  43  to compare a numeric value determined based on each symbol weighting data to a random numeric value generated correspondingly to each cell of the symbol matrix  28 , thereby determining the symbol to be arranged in each cell of the symbol matrix, from among the group of symbols selected at step S 303  or S 304 . The main CPU  41  then rearranges the determined symbols. 
     Next, the main CPU  41  makes a judgment as to whether or not the symbol “CHANCE  70   a ” is contained in the symbols rearranged in the symbol matrix at step S 305 . In a case where the symbol “CHANCE  70   a ” is not included, the main CPU  41  terminates the symbol rearrangement process (step S 306 : NO). Where the symbol “CHANCE  70   a ” is included in the symbols rearranged in the symbol matrix  28 , the main CPU  41  counts the number of symbols “CHANCE  70   a ”. Upon judging that three or more symbols “CHANCE” are contained (step S 306 : YES), the main CPU  41  causes the effect image display section  94  to display an effect image that one more icon “BONUS” is added (step S 307 ). 
     The main CPU  41  then invokes a cumulative value of bonus points stored in the RAM  43 , the value being equal to the number of icons “BONUS  70   d ” having been displayed by the time of the previous symbol rearrangement process. The main CPU  41  adds one to the value and then stores it again in the RAM  43  (step S 308 ). The main CPU  41  terminates the symbol rearrangement process throughout the above described process. 
       FIG. 10  is a flowchart showing a subroutine of the bonus game execution process invoked and executed at step S 209  of the subroutine shown in  FIG. 8 . First, the main CPU  41  invokes the cumulative number of bonus points stored in the RAM  43  and judges whether or not a right to execute the bonus game exists (step S 401 ). Specifically, in the case of the cumulative number being equal to zero, the subroutine is terminated (step S 401 : YES). On the other hand, when the cumulative value is not equal to zero (step S 401 : NO), the number of bonus games is set (step S 402 ). Specifically, the main CPU  41  sets a value of the bonus game number B to the bonus points, thereby storing the value in the RAM  43 . 
     The main CPU  41  then judges whether or not the start button  23  has been set to ON (step S 403 ). As described above, specifically, the main CPU  41  judges whether or not the input signal has been received, the signal being output from the start switch  23 S when the start button  23  is pressed. Upon judging that the start button  23  has not been set to ON (step S 403 : NO), the main CPU  41  controls the step to return to steps subsequent to step S 402 . In a case where the start button  23  has not been set to ON (for example, where an instruction has been entered to terminate the game without setting the start button  23  to ON), the main CPU  41  displays alarm on the upper image display panel  33  and then sets the cumulative value of the bonus points to zero, thereby terminating the subroutine. 
     On the other hand, upon judging that the start button  23  has been set to ON (step S 403 : YES), the main CPU  41  performs the symbol rearrangement process (step S 404 ). Specifically, the CPU  41  executes a program stored in the RAM  43  and samples a plurality of random numeric values corresponding to the symbol matrix  28  from among predetermined random numbers. The CPU  41  then compares the sampled random numeric values to symbol weighting data which comes under a predetermined numerical range. The CPU  41  determines the symbol to be rearranged in the symbol matrix from among the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, “CHANCE  70   a ”, and “blank”. 
     Next, the main CPU  41  judges whether the bonus has been established (step S 405 ). Specifically, the main CPU  41  judges whether three or more symbols “sub character  122 ” serving as a bonus symbol, are rearranged in the symbol matrix  28  (see  FIG. 7B ). 
     Upon judging that the bonus has been established (step S 405 : YES), the main CPU  41  performs the payout process of coins (step S 406 ), the number of which is determined based on the cumulative number of credits having been cumulatively stored in the memory region set in the RAM  43 . In a case where the coins are deposited, the main CPU  41  performs a process of adding the number of paid-out coins to the credit amount stored in the RAM  43 . In a case where the coins are paid out, the main CPU  41  pays out the predetermined number of coins by transmitting the control signal to the hopper  66 . 
     On the other hand, upon judging that the bonus has not been established (step S 405 : NO), the main CPU  41  sets the remaining bonus game number to B=B−1 (step S 407 ). Specifically, the main CPU  41  sets B=B−1 at a value of the remaining bonus game number B stored in the RAM  43 . 
     Next, the main CPU  41  judges whether or not a value of the remaining free game number B is equal to zero (step S 408 ). Specifically, the main CPU  41  judges whether or not the remaining game number B stored in the RAM  43  is equal to zero. Upon judging that a value of B is not equal to zero (step S 408 : NO), the main CPU  41  controls the step to shift to step S 403 . Upon judging that a value of B is equal to zero (step S 408 : YES), on the other hands, the main CPU  41  clears a cumulative value of bonus points stored in the RAM  43  and terminates the subroutine. 
       FIGS. 11A ,  11 B, and  12  are views each showing a case in this embodiment where the bonus game is executed not as the above-described symbol rearrangement game but as a card game.  FIGS. 11A and 11B  are views each showing an exemplary image displayed on the lower image display panel  16 .  FIG. 12  is an execution flowchart of the card game as a bonus game. 
       FIGS. 11A and 11B  are views each showing an exemplary image displayed on the lower image display panel  16  during the bonus game. Upon start of the bonus game, the display region  92  of the lower image display panel  16  switches a screen to a card display screen in which ten cards are displayed in a face-down manner. In this case, the display region  92  functions as a touch panel, and the CPU  41  judges the card touched by the player as the selected one. The player can designate cards as many as the number of icons “BONUS” displayed on the display region  94 , that is, the number of bonus points. In the case shown in  FIG. 11A , the player designates one card and the CPU  41  changes a pattern to the symbol “car  125 ”. On the other hand, the icon “BONUS  70   e ” displayed on the display region  94  disappears after blinking. The player can designate the cards as many as the remaining number, four in this case, of icons “BONUS”. 
       FIG. 11B  shows an exemplary display of the lower image display panel  16  when the player designates cards in succession.  FIG. 11B  shows a state that the player designates the fifth card after designating four cards, and the CPU  41  changes a pattern of the fifth card to the bonus symbol “sub character  122 ”. In  FIG. 11B , the three symbols “sub character  122 ” are displayed, which meets the condition for establishment of the bonus, so that the jackpot is awarded. 
       FIG. 12  is a flowchart of the bonus game execution process invoked and executed at step S 209  of the subroutine shown in  FIG. 8 . In this case, the bonus game is a card game having been explained with reference to  FIG. 11 . First, the main CPU  41  invokes a cumulative value of bonus points stored in the RAM  43  and judges whether or not a right to execute the bonus game exists (step S 501 ). Specifically, in a case of two or less bonus points, the subroutine is terminated (step S 501 : NO). On the other hand, in a case of three or more bonus points (step S 501 : YES), the main CPU  41  switches display of the display region  92  from the symbol matrix  28  to the card display (step S 502 ). At this time, the symbol matrix  28  disappears but the card is not yet displayed. Next, the CPU  41  sets the number of cards which can be selected (step S 503 ). Specifically, the main CPU  41  sets B=bonus points at a value of the selectable card number B and stores the value in the RAM  43 . Thereafter, the more cards than the number of bonus points are displayed on the display region  92  (step S 404 ). 
     Next, the main CPU  41  judges whether or not the player selects the card by touching the display region  92  functioning as a touch panel (step S 505 ). Upon judging that the selection has not been made (step S 505 : NO), the main CPU  41  displays a selection command on the upper image display panel  33  and stands by until when the card is selected. In a case where the card has not been selected (for example, where an instruction has been input to terminate the game), the main CPU  41  displays an alarm on the upper image display panel  33 , sets a cumulative value of bonus points to zero, and terminates the subroutine. 
     On the other hand, upon judging that the card has been selected (step S 505 : YES), the main CPU  41  changes a pattern of the selected card to display the symbol (step S 506 ). Specifically, the CPU  41  executes the program stored in the RAM  43  and samples a plurality of random numeric values corresponding to the card from among predetermined random numbers. The CPU  41  then compares the sampled random numeric values to symbol weighting data which comes under a predetermined numerical range. The CPU  41  determines the symbol to be rearranged in the symbol matrix from among the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, and “villa  128 ”. 
     Next, the main CPU  41  judges whether or not the bonus has been established (step S 507 ). Specifically, the main CPU  41  judges whether or not three or more cards are displayed, the cards displaying thereon the bonus symbol “sub character  122 ” (see  FIG. 11B ). 
     Upon judging that the bonus has been established (step S 507 : YES), the main CPU  41  then performs the payout process of coins (step S 508 ), the number of which is determined based on the cumulative number of credits having been cumulatively stored in the memory region set in the RAM  43  (step S 508 ). In a case where the coins are deposited, the main CPU  41  performs a process for adding the number of paid-out coins to the credit amount stored in the RAM  43 . In a case where the coins are paid out, the main CPU  41  pays out the predetermined number of coins by transmitting the control signal to the hopper  66 . 
     On the other hand, upon judging that the bonus has not been established (step S 507 : NO), the main CPU  41  sets the remaining number of selectable cards B=B−1 (step S 509 ). Next, the main CPU  41  judges whether or not a value of B is equal to zero (step S 510 ). In a case of judging that a value of B is not equal to zero (step S 510 : NO), the main CPU  41  controls the step to return to step S 505  and stands by for the next selection of the card. On the other hand, upon judging that a value of B is equal to zero (step S 410 : YES), the main CPU  41  clears a cumulative value of bonus points stored in the RAM  43  and terminates the subroutine. 
     Next, a slot machine  100  according to a second embodiment will be described with reference to the drawings. The slot machine according to the second embodiment below is a so-called hybrid slot machine in which a plurality of rotatably-supported mechanical reels have a transparent liquid crystal panel on front surfaces to display images of various symbols drawn on peripheral surfaces of the mechanism reels through the transparent liquid crystal panel through which the pictures are allowed to pass. The slot machine according to the second embodiment has an appearance, circuitry, and the like that are substantially the same as those of the slot machine  10  according to the first embodiment. Thus, a duplicated explanation is omitted here. Constituent elements corresponding to those of the slot machine  10  are designated by the same reference numerals and are explained. 
       FIG. 13  is a view schematically showing an appearance of the slot machine according to the second embodiment. As shown in  FIG. 13 , the slot machine  100  is rotatably provided with five reels  101   a  to  101   e.  A symbol column made up of the symbols “blank”, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, and “villa  128 ” is drawn on the respective one of the outer circumferential surfaces of the reels  101   a  to  101   e ,. 
     A main liquid crystal panel  202  formed of a transparent liquid crystal panel, which is disposed at the main door, is provided in front of the respective reels  101   a  to  101   e.  The main liquid crystal panel  202  displays the symbol display region  28  with visually recognizable rear surface so as to surround symbols displayed in the reels  101   a  to  101   e  in a stopped state, respectively. The symbols drawn on the reels  101   a  to  101   e  are visualized by rendering the symbol display region transparent. 
       FIGS. 14A and 14B  are views each showing an exemplary display of the lower image display panel  16  during the basic game executed in the slot machine  100 . In  FIG. 14A , the five reels  101   a  to  101   e  are displayed in a stopped state, and respective frames  103   a  to  103   o  of the symbol display region in the main liquid crystal panel  202  are transparently displayed so as to render these five reels  101   a  to  101   e  visually recognizable. In this case, the symbols “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, and “villa  128 ” are displayed in a stopped state. 
     During the process with the slot machine  100  corresponding to the rearrangement process of the basic game (see  FIG. 9 ) according to the first embodiment, the symbol “CHANCE  70   a ” to be rearranged is rearranged on the frame of the symbol matrix  28  of the liquid panel  202 . The symbol drawn on the reel is fixed, so that control whether to rearrange the symbol “CHANCE  70   a ”, which is decided based on existence of the side BET, cannot be performed. On the liquid crystal panel, on the other hand, this control can be easily performed by selecting display or non-display.  FIG. 14B  shows a state where the symbol “CHANCE  70   a ” is rearranged on the symbol matrix  28  of the liquid crystal panel  202  as compared with display in a stopped state of the five reels  101   a  to  101   e  shown in  FIG. 14A . In a frame  103   k  of the symbol matrix  28 , the symbol “CHANCE  70   a ” is displayed in superposition with the symbol “main character  121 ” so that both of the symbols “CHANCE  70   a ” and “main character  121 ” can be visually recognizable. 
     As described above, the slot machine  100  according to the second embodiment exercises control over the game so as to award the bonus point during the basic game according to the first embodiment. On the other hand, the card game executed in the bonus game (see  FIGS. 11 and 12 ) is carried out on the display region  92  of the liquid crystal panel  202 . 
     In the foregoing, while the embodiments of the present invention have been described, these embodiments merely present specific examples. An appropriate design change can be made for the specific configuration of each means or the like. Also, the effects described in the embodiments of the present invention are only listing the most preferable effects arising from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention.