Nonuniform probability reel stop mechanism for gaming machines

• US 4,858,932 A
• Filed: 04/21/1988
• Issued: 08/22/1989
• Est. Priority Date: 04/21/1988
• Status: Expired due to Term

• Current Assignee: Bally Gaming Incorporated (Scientific Games Corporation)
• Original Assignee: Bally Manufacturing Corp. (Park Hotels & Resorts Inc.)
• Inventors: Keane, Martin A.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Harrison, Jessica
• Application Number:
  US07/184,240
• Time in Patent Office: 488 Days
• Field of Search: 273/138 A, 273/143 R, 273/138 R
• US Class Current: 463/21
• CPC Class Codes: G07F 17/3244 Payment aspects of a gaming system, e.g. payment schemes, setting payout ratio, bonus or consolation prizes

Abstract

In order to provide a reel type gaming apparatus with the capability to pay out winnings having a higher value than an apparatus where the reels have an equal probability of stopping at each reel stop, a table is created in memory having pairs of lower and upper numerical limits which define groups of subintervals that in turn correspond to reel stops. A random number is generated and the subinterval which includes the number is identified and the reel is stopped at the corresponding reel stop. The interval between the upper and lower limits for each subinterval defines the relative stopping probability for the corresponding reel stop. In another approach probability factors are assigned to each reel stop and a microprocessor subtracts the value of each probability factor from a randomly generated probability value and increments a reel stop index until the probability value is less than the probability factor for the current stop index. Upon a player activated event the current stop index is used to stop the reel in a predetermined position. The relative values of the probability factors correspond to the relative stopping probability of each reel stop.

Claims

1. A gaming apparatus having a symbol bearing reel mounted for rotation about an axis with the reel having a predetermined number of reel stops comprising:

initiation means responsive to a player input for generating an initiate signal;

a digital memory storing a stop index for each of the reel stops and a probability factor for each reel stop that corresponds to each one of said stop indexes;

means responsive to said initiate signal for initiating rotation of the reel; and

microprocessor means operatively connected to said digital memory including selection means for randomly selecting one of said stop index values including generating means for generating a probability value, comparison means for comparing said probability value to a selected one of said probability factors associated with one of said stop indexes and if said probability value is greater than said selected probability factor incrementing the selected stop index associated with said selected probability factor, subtracting said selected probability factor from said probability value, and repeating said comparison or alternatively terminating said comparison if said probability value is less than said selected probability factor, means for periodically performing said probability value and comparison operation; and

stop means responsive to said selected stop index for stopping the reel at a predetermined location.

2. A gaming apparatus having a symbol bearing reel mounted for rotation about an axis with the reel having a predetermined number of reel stops comprising

initiation means responsive to a player input for generating an initiate signal;

a digital memory containing a table of upper and lower subinterval limits wherein each of pairs of said upper and lower subinterval limits defines a subinterval and wherein each subinterval corresponds to a stop index and wherein the range between the lower limit and the upper limit of each subinterval represents a predetermined probability factor;

processor means responsive to said initiation signal for initiating rotation of the reel;

generator means for generating a value;

means utilizing said table for determining which of said subintervals contains said value and identifying the corresponding stop index;

stop means responsive to said identified stop index for stopping said reel at a predetermined location corresponding to said identified stop index.

3. The apparatus of claim 2 wherein said value is randomly generated with a substantially uniform distribution.

4. The apparatus of claim 2 wherein the range of said values is at least five significant figures.

5. An apparatus for generating a table of subintervals for use in a memory of a gaming apparatus having X number of reel stops each corresponding to one of the subinterval comprising;

means for initializing the value of X to 1;

first means for setting the lower limit of the first subinterval corresponding to X=1 equal to zero;

second means for setting the upper limit of said first subinterval to a first predetermined stopping probability;

incrementing means for incrementing the value of X by 1;

third means for setting the lower limit for the subinterval corresponding to said incremented X to the value of said upper limit of the subinterval corresponding to X-1;

Fourth means for setting the upper limit of the subinterval corresponding to X to the lower limit of the subinterval corresponding to X plus a predetermined stopping probability for X;

means for comparing the value of X to the maximum value of X for the apparatus and for causing said incrementing means and said third and fourth means to repeat their operations if X is less than said maximum value of X.

6. A gaming apparatus having a symbol bearing reel mounted for rotation about an axis with the reel having a predetermined number of reel stops comprising:

initiation means responsive to a player input for generating an initiate signal;

a memory for storing a probability factor for each reel stop wherein each reel stop has a stop index associated therewith;

processor means responsive to said initiation means and said memory means for initiating rotation of the reel in response to said initiate signal and for stopping the reel wherein said processor means includes;

generating means for generating a probability value;

means for selecting a current one of said stop indexes;

comparison means for implementing a comparison logic step including comparing said probability value to the current reel stop probability factor associated with said current stop index and if said probability value is greater than said selected reel stop probability factor subtracting said current reel stop probability factor from said probability value incrementing said current stop index, and causing said comparison means to repeat said comparison logic step or alternatively causing said comparison means to terminate said comparison logic step if said probability value is less than said current reel stop probability factor;

interrupt means for causing said generating means to generate said probability value and said comparison logic step to be periodically actuated; and

stop means responsive to a stop signal for stopping the reel such that the reel stop corresponding to said current stop index stops as a predetermined position.

7. The gaming apparatus of claim 6 wherein said generating means generates said probability values having a random distribution.

8. The gaming apparatus of claim 7 wherein said random probability values have a uniform probability distribution.

9. The gaming apparatus of claim 7 wherein said probability value has a maximum value Δ

W according to the relation;

##EQU2## where W_i represents the probability factor for the stop index i and p represents the maximum number of stop indexes.

10. The apparatus of claim 9 wherein said processor means additionally includes residual means for generating a residual probability value and wherein said comparison means additionally subtracts said residual probability factor from said selected reel stop probability factor before subtracting said selected reel stop probability factor from said probability value.

11. The apparatus of claim 10 wherein said comparison means additionally sets said residual probability factor to zero after said incrementing of said current stop index.