Abstract:
For each bet on a slot machine game, such as a conventional reel-type game, a fraction of a free game is stored in the machine&#39;s memory, where the stored free game fraction is associated with the amount bet. Thus, each possible bet amount option is associated with a particular free game pot in memory. Each paid-for play may accumulate any free game fraction, such as 1/10, ⅕, ¼, ⅓, etc. The player is notified of the accumulated free games on a video screen so the player wants to keep playing so as to not waste any stored free game fractions. The player may play stored whole free games at any time by actuating a button. The free game pots may be easily added to existing games without significant regulatory involvement and does not affect the casino&#39;s profit.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to gaming machines and, in particular, to providing players fractions of free games for each game played. 
       BACKGROUND 
       [0002]    Common slot machines randomly select and display an array of symbols on actual or virtual reels, then grant an award to a player based on the occurrence of winning symbol combinations across activated paylines. Common symbol displays include a 5 column by 4 row (5×4) matrix, a 5×3 matrix, a 3×3 matrix, and a 3×1 matrix. 
         [0003]    There are typically a plurality of bet amount options, including a minimum bet (e.g., 1 credit), a maximum bet (e.g., credits needed to play all paylines at a maximum amount per payline), and bets in-between. Casinos like higher bets per play since more profit is made. 
         [0004]    The present invention may apply to other types of gaming machines such as video poker or any other game. 
         [0005]    Slot machine manufacturers and casinos have created many different ways to encourage players to bet more, play longer, and play certain machines. Such ways frequently involve designing the game to contain special features such as a bonus game, or the casino may provide an incentive to the players to play more such as awarding complimentary services for play in excess of a certain amount. New or revised game programs typically require a long time to develop and test and require approval by the appropriate regulatory agency. And, casino incentives cost the casino money. 
         [0006]    What is needed is a technique that encourages players to play slot machines for a longer time and to bet higher amounts per game, where the technique does not require changes to the game itself and does not cost the casino money. 
       SUMMARY 
       [0007]    For each bet on a slot machine game, such as a conventional reel-type game, a fraction of a free game is stored in the machine&#39;s memory, where the stored free game fraction is associated with the amount bet. Thus, each possible bet amount option is associated with a particular free game pot in memory. Each paid-for play may accumulate ¼ of a free game or any other fraction, such as 1/10, ⅕, ⅓, etc. 
         [0008]    For example, if the player bet one credit for a game, ¼ of a free game credit will be stored in the “1 credit free game pot.” After the player plays three more 1-credit games (i.e., accumulates a whole free game), the player will receive a free 1-credit game (i.e., the paylines and awards will be that for a paid 1-credit game). Similarly, if the player bets 10 credits for a game, ¼ of a free game credit will be stored in the “10-credit free game pot.” After the player plays three more 10-credit games, the player will receive one free 10-credit game. 
         [0009]    The player is notified of the accumulated free games on a video screen, a meter, or other type of display, so the player has a desire to keep playing so as to not waste any stored free game fractions. 
         [0010]    The player may play stored whole free games at any time by pressing an actual button or a virtual button on a touch screen. In another embodiment, as soon as a whole free game is accumulated, it is automatically played as the next game after informing the player of the free game. In another embodiment, the stored free games may be transferred to other gaming machines via a network or encoded on a paper ticket when the player cashes out. 
         [0011]    In order for the free games to not reduce the profitability of the machine, the payout percentage (i.e., average payout/pay-in ×100% for each game) for the paid games is slightly reduced so that the overall target payout percentage for the machine is maintained when including the free games. 
         [0012]    As an incentive to bet the maximum bet for each game, the fraction of a free game achieved for each paid game may be greater than the fraction for a smaller bet game. In another embodiment, the free game fraction is only applicable to a maximum bet, thereby encouraging the players to bet the maximum. Other incentives for playing increased bets are described herein. 
         [0013]    Further, there may be special free game multiplier symbols introduced into the reel strips such that the occurrence of a multiplier symbol multiplies the stored free games associated with the game&#39;s bet amount. Other symbols may be introduced that increment a free game pot. 
         [0014]    The free games may also be stored for a video poker game or other gambling game. 
         [0015]    As seen, various techniques involving awarding fractions of free games associated with the amount bet are described that entail no changes to the underlying game itself, and the target payout percentage is not affected. Therefore, the free game pot invention may be easily added to existing games without significant regulatory involvement and does not affect the casino&#39;s profit. The addition of the free game feature causes potential players to be attracted to the machines and rewards the player for long term play. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of one type of gaming machine that is programmed to carry out the inventive technique. 
           [0017]      FIG. 2  is a block diagram showing the basic functional units in the gaming machine of  FIG. 1 . 
           [0018]      FIG. 3  illustrates an example of a screen showing a 5×3 matrix of symbols and a display of the stored free games in the free game pots. 
           [0019]      FIG. 4  is a flow chart of the basic method carried out using the new technique. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Although the invention can typically be implemented by installing a software program in most types of modern video gaming machines, one particular gaming machine platform will be described in detail. 
         [0021]      FIG. 1  is a perspective view of a gaming machine  10  that incorporates the present invention. Machine  10  includes a display  12  that may be a thin film transistor (TFT) display, a liquid crystal display (LCD), a cathode ray tube (CRT), or any other type of display. A second display  14  provides game data or other information in addition to display  12 . Display  14  may provide information such as an advertisement for the game, the rules of the game, pay tables for each bet amount, the different blocks of symbol positions associated with their associated bet amount to determine winning symbol combinations, or other information, or may even display the main game or the bonus games along with display  12 . Alternatively, the area for display  14  may be a display glass for conveying relevant information. 
         [0022]    Display  12  or  14  may have a touch screen lamination that includes a transparent grid of conductors. Touching the screen changes the capacitance between the conductors, and thereby the X-Y location of the touch may be determined. The processor associates this X-Y location with a function to be performed. Such touch screens are very well known in the field of slot machines, and a detailed description of them is not required. 
         [0023]    A coin slot  22  accepts coins or tokens in one or more denominations to generate credits within machine  10  for playing games. An input slot  24  for an optical reader and printer receives machine readable printed tickets and outputs printed tickets for use in cashless gaming. A bill acceptor  26  accepts various denominations of banknotes. 
         [0024]    A coin tray  32  receives coins or tokens from a hopper upon a win or upon the player cashing out. 
         [0025]    A card reader slot  34  accepts any of various types of cards, such as smart cards, magnetic strip cards, or other types of cards conveying machine readable information. The card reader reads the inserted card for player and credit information for cashless gaming. The card reader may also include an optical reader and printer for reading and printing coded barcodes and other information on a paper ticket. 
         [0026]    A keypad  36  accepts player input, such as a personal identification number (PIN) or any other player information. A display  38  above keypad  36  displays a menu for instructions and other information and provides visual feedback of the keys pressed. 
         [0027]    Player control buttons  39  include any buttons needed for the play of the particular game or games offered by machine  10  including, for example, one or more bet buttons, a repeat bet button, a spin reels button, a maximum bet button, a cash-out button, a display payout tables button, select icon buttons, free game play buttons, and any other suitable button. Buttons  39  may be replaced by a touch screen with virtual buttons. In one embodiment, to simplify betting, there are only a limited number of betting options, such as five, and each betting option has a separate button  39 . 
         [0028]      FIG. 2  illustrates basic circuit blocks in a suitable gaming device. A control unit (CPU  40 ) runs a gaming program stored in a program ROM  43  (e.g., a CD). A coin/credit detector  41  enables the CPU  40  to initiate a next game. A paytable ROM  44  detects the outcome of the game and identifies awards to be paid to the player. A payout device  42  pays out an award to the player in the form of coins upon termination of the game or upon the player cashing out. A payout may also be in the form of a coded paper ticket, credits on a smart card or magnetic strip card, or in any other form. A display controller  45  receives commands from the CPU  40  and generates signals for the various displays  46 . If a display  46  is a touch screen, player commands may be input through the display screen into the CPU  40 . All components may be connected to a single bus. 
         [0029]    A RAM  47  stores all or portions of the game program (downloaded from program ROM  43 ) while the machine is being used and stores a plurality of free game pots  48 - 51 , one pot per bet amount option. Each pot is actually a dedicated memory location that stores the accumulated number of free games associated with that bet amount. The CPU  40  interacts with the RAM  47  when the RAM  47  is loaded with the pertinent game software. The CPU  40  calculates the free game pot amounts and stores the accumulated amounts in the free game pots. 
       Operation of Gaming Machine Incorporating Invention 
       [0030]    The operation of the gaming machine of  FIG. 1  will be described with respect to the sample screen display of  FIG. 3  and the flowchart of  FIG. 4 . 
         [0031]    As an initial matter, the game program or a separate program controlling CPU  40 , or a hardware circuit, causes the RAM  47  to dedicate certain memory locations to accumulating free games associated with each bet option (step  60  in  FIG. 4 ). Each such memory location is referred to as a free game pot. For simplicity, it is assumed that there are only three betting options for playing a single game: 1 credit, 5 credits, and a maximum bet. A game may be the rotation and random stoppage of five virtual reels  54  displaying a 5×3 matrix of symbols. Sample symbols are shown. Awards are based upon whether the symbol combinations across paylines are winning combinations. Only three horizontal paylines, PL 1 , PL 2 , PL 3 , are shown in  FIG. 3  for simplicity. Normally, there would be many more paylines. Increasing a bet typically adds paylines or multiplies an award for a winning combination of symbols, or both. 
         [0032]    The player initially deposits money into the gaming machine, either by cash, ticket, or download, to accumulate credits for later betting. In step  61 , the player then makes a wager for a single game, such as 1 credit, 5 credits, or a max bet. It will be assumed that a bet of 1 credit is wagered for the game. 
         [0033]    In step  62 , a free game pot associated with the bet amount made is incremented by a fraction of a free game, and the free game pots are displayed. The fraction may be 1/10, ⅕, ¼, ⅓, or any other fraction. It will be assumed that the fraction is ¼.  FIG. 3  illustrates that the display screen  12  of  FIG. 1  has incremented the Bet  1  Free Game Pot by ¼ so that the player has accumulated 1½ free games, after previously playing five games betting one credit per game. The display of the stored quantity of free games in each pot may be a continuous display or may be displayed between games or upon the player pressing a button to display the free game pots. 
         [0034]    In step  63 , the game is initiated by pressing a “spin reels” button or pulling a handle, and the reels randomly stop to display an A×B matrix of symbols (step  64 ).  FIG. 3  shows a sample 5×3 matrix of displayed symbols. 
         [0035]    In step  65 , any award is granted based on winning symbol combinations across activated paylines and based on the amount bet. In some types of games, an increased bet increases the award proportionally. In other types of games, an increased bet increases the number of activated paylines and may not affect the award amount. In any event, an increased bet is beneficial to the player due to increased awards or increased odds of winning. 
         [0036]      FIG. 3  also illustrates that certain symbols in the A×B matrix may be related to the free game pots. One symbol, shown as +4FG, adds four free games to the pot associated with the amount bet. Symbols may award any fractions of free games or whole free games. Another symbol shown in  FIG. 3  is a FGX3 symbol, which multiplies the stored free games for the associated bet by three times. Any multiple may be used. 
         [0037]    In step  66 , it is determined whether the player has any full free games stored in any of the free game pots  48 - 51  in  FIG. 2 . If not, the process reverts back to step  61 , where the player must bet again to play again. 
         [0038]    In step  67 , if there are one or more full free games stored in the pots, then the player may elect to play any of the games by pressing a “play free games” button  56 .  FIG. 3  shows a virtual button for each free game pot that the player touches to play a free game from that pot. Touch screens are well known in the field of slot machines. The free game is then played using the bet amount associated with the pot, and the full free game is deducted from the pot. The player may play any number of the stored full free games. In  FIG. 3 , since only the Bet  1  Free Game Pot contains a full free game, the player may only play a Bet  1  free game. 
         [0039]    After the player cashes out of the machine by pressing a cash-out button, the free game pots are preferably reset to zero or another starting point to discourage non-players from waiting to play machines with stored fractions of free games. 
         [0040]    The invention encourages extended play by the player since the player does not want to leave any partial free games in the pots. Also, the invention encourages betting a maximum amount since the free games are played using the bet amount associated with the pot. A free game played from the Bet Max Free Game Pot is the most valuable free game since the awards or odds of winning are generally higher than those of free games from other pots. 
         [0041]    In one embodiment, there is only a free game pot for the maximum bet, or for certain bets greater than the minimum bet, to encourage the player to bet more than the minimum bet. To further encourage players to bet more than the minimum bet, higher bet amounts increment their associated free game pots by higher fractions of free game. For example, a minimum bet may add ⅕ free game for each paid game, and a maximum bet may add ¼ free game for each paid game. Additionally, certain symbols on the virtual reel strips may increment a free game pot only when the player makes a maximum bet or other increased bet. Such symbols may only be included in a reel strip if the player makes the maximum bet or other increased bet. 
         [0042]    Further, even though the awards for the paid games are reduced to take into account awards granted during the free games, to maintain an overall target average payout percentage, the player perceives the free games as an additional award, so the slot machines are more popular than conventional machines. The award amounts are easily controlled by programming the paytable ROM  44  in  FIG. 2 . 
         [0043]    An additional benefit of the invention is that the game played need not be affected by the free game feature. In other words, the reel strips, reel stop selection software, winning combinations, and odds of winning an award may be unaffected by the addition of the free game feature. This allows the feature to be a simple software add-on that does not change the game itself. Hence, there may be minimum regulatory approval for the add-on. Only the paytable needs to be changed to maintain a target payout percentage, and the steps  62 ,  66 , and  67  need to be added to the process flow. 
         [0044]    The various techniques described are easily implemented by a software programmer storing a program in the program ROM  43  in  FIG. 2 . The CPU  40  carries out the program, as would be understood by those skilled in the art. 
         [0045]    The technique may be carried out on a stand-alone machine or on a machine connected to a server. 
         [0046]    While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention.