referring to fig1 there is shown a pinball game 20 having the usual playfield 22 onto which a pinball is projected . also shown are a number of ramps , targets and other features typical of modern day pinball machines . at the lower end of the playfield 22 are a pair of flippers 24 and 26 which are player controlled in the usual case by switch buttons located on the side of the pinball machine . a player use these switches to operate the flippers to return the pinball to the upper portion of the playfield , thereby to prevent it from going into the outhole or drain which is located at the lower end of the playfield . as shown in fig1 there is a space between the flippers 24 and 26 through which the pinball can pass regardless of whether the flippers are operated by the player . the spacing between the flippers is an important design consideration . if this space is too great , the game will be difficult for beginners , thereby discouraging play . on the other hand , if the space between the flippers is too small , skilled players will soon tire of the game as it will present little challenge and revenue will decrease because games will last for an excessive period of time . according to the present invention , a variable position mechanism is provided whereby the space between the flippers can be adjusted as the play of the game progresses . the adjustment can be controlled by the microprocessor control system associated with modern day pinball games . referring to fig2 and 3 , there is illustrated flippers 24 and 26 in their two extreme positions . thus , in fig2 the flippers are as close together as permitted so that it is almost , but not quite , impossible for a ball to travel between the flippers to the outhole . in fig3 the flippers are separated by a substantially greater distance so that it is easier for a ball to pass therebetween . it is important to note , however , that in both cases ( and in all intermediate positions between the two extremes ) the angle of the flippers relative to the playfield does not change . this is important because the playfield design is based , in part , upon the angle at which the flippers are set . thus , the various targets and ramps are positioned by the game designer so that the shots can be made by the player employing flippers at a known angle . if the angle of the flippers were to change as they moved toward and away from each other , this could adversely affect the player &# 39 ; s ability to accurately hit the various ramps and targets . this , of course , would be counterproductive to the objective of improving the enjoyment of the game and maintaining competitiveness over a range of skill levels . according to the present invention , regardless of the distance between the flippers , the correct angle of the flippers relative to the playfield is maintained . referring now to fig4 the variable positioning mechanism , according to the present invention , is illustrated . the flippers are player controlled . each flipper is provided with a solenoid 30 which causes the flipper to strike the pinball when operated by the player . the manner in which the flipper mechanism operates is well - known in this art and will not be described in detail . in brief , the solenoids 30 are connected by a linkage 32 to a shaft 34 on which the flippers 24 and 26 are mounted . operation of the solenoids causes the linkage to rotate the shaft , thereby to cause the flippers to rotate and strike a pinball on the playfield . in the usual case , the flipper mechanism just described is mounted directly to the underside of the playfield , thereby fixing the distance between the flippers . in the present invention , each flipper mechanism is mounted instead on a plate 36 having extensions tabs 38 which are received in channels indicated as 40 in the drawings . the plates 36 and the flipper mechanisms mounted thereon are thus positioned for linear movement within the channel 40 as indicated by the arrow 42 . the shaft 34 to which the flipper is mounted , extends upwardly to the playfield through an elongated slot best shown in fig6 . movement of the plates 36 on which the flipper mechanisms are mounted is controlled by an indexing mechanism now to be described . a cam plate 50 is rotatably mounted to the underside of the playfield and includes a number of ratchet teeth 52 along a portion of the periphery thereof . arcuate slots 54 and 56 are cut into the central portion of the cam plate 50 . each slot is intended to receive a follower pin 58 which secures a tab extension 60 formed on the plate 36 . as will be understood , and as explained in detail hereafter , rotation of the cam plate 50 causes movement of the plates 36 as indicated by the arrow 42 . as the cam plate rotates from the position shown in fig4 ( the closed position ), to the position shown in fig1 ( the open position ), the slots 54 and 56 cause the plates 36 to move outwardly from the cam plate 50 , thereby moving the flippers away from each other and increasing the distance therebetween . so that the same microprocessor can know the precise position of the cam plate , it is desirable to provide a signaling means . one such acceptable mechanism for signaling the processor includes the use of optical detectors 70 positioned on a circuit board 71 mounting beneath the indexing mechanism ( fig6 ). these horseshoe - shaped solid state devices are dimensioned to receive an interrupting element 72 , carried by the cam plate 50 . as shown in fig6 when the interrupting element passes between the upwardly extending arms of the detector 70 , a digital signal is generated which can be detected and interpreted by the microprocessor , thereby to determine the position of the cam plate and , in turn , the spacing of the flippers . with this information , in a manner well - known to those skilled in the art , the indexing mechanism of the present invention can be controlled to permit precise positioning of the flipper elements as desired . for example , minimum spacing can be employed , thereby making the game easier , at the beginning . as the game progresses , the flippers can be moved further apart as a function of a number of variables , such as time , score , number of targets hit , etc . alternatively , movement of the flippers can be controlled as a bonus feature so that the flippers move together whenever a player makes a predetermined sequence of targets or achieves a predetermined score . thereafter , the flippers can be separated to again render the game more difficult . the possibilities are virtually limitless and will be set by the game designer as deemed appropriate for a particular game theme . the point is that the electromechanical indexing mechanism of this invention permits variable positioning of the flippers . this permits a game designer to vary the skill level as a function of any desired game parameter . the signals from the optical detector portion of the system permit the processor to determine the present position of the flippers and ensure that appropriate modifications have taken place when it is desired to change the flipper positions . in the fully closed position of fig4 only one of the detectors 70 generates a signal . in progressive positions shown in fig7 - 10 , different combinations of the detectors will generate signals , each consisting a unique digital code relating to the position of the flippers . in order to move the flippers apart , the cam plate is indexed by a mechanism which includes an advance solenoid 80 , a reset solenoid 82 and associated linkages , and springs . the advance solenoid 80 is associated with an index follower 88 , the distal end of which is adapted to engage the teeth 52 on the cam plate 50 . an advance spring 84 provides the return stroke after operation of the solenoid 80 . a reset solenoid 82 includes a reset follower 90 and a release arm 91 linked to the solenoid . the distal end of the follower 90 is adapted to selectively engage the teeth 52 of the cam plate 50 when permitted by the release arm 91 . a spring 92 biases the reset follower into engagement with the teeth . as indicated , fig4 shows the mechanism in the fully closed position in which the flippers are as close together as permitted by the dimensions of the slots 54 and 56 in the cam plate 50 . fig7 - 10 illustrate the mechanism in other positions and are useful in explaining the manner in which the indexing device operates . in particular , fig7 shows the solenoid 80 in its retracted position , such that the follower 88 is drawn to the right , in preparation for an indexing operation , whereby the cam plate 50 will be rotated clockwise the dimension of one tooth . when the solenoid 80 retracts its plunger to move the follower 88 to the position shown in fig7 a stop arm 89 engages the cam plate to prevent it from turning in a counter - clockwise direction . after the advance solenoid 80 retracts the follower 88 , spring 84 extends it ( fig8 ) which results in one - tooth rotation of the cam plate 50 . restated , the reciprocal movement of the index follower causes it to engage the next tooth on the periphery of the cam plate and then force that tooth forward by the amount of the stroke of the solenoid . the stop arm 89 is automatically released during the clockwise movement of the cam plate . as shown in fig4 the reset follower 90 normally is disengaged from the cam plate . in this manner , the index follower can move the cam plate clockwise , until the desired position of the flippers is achieved . when it is desired to move the cam from the fully open position shown in fig1 to an intermediate position , or to the fully closed position of fig4 the reset solenoid 82 is operated . this retracts its plunger , engaging the reset follower 90 with the cam plate teeth ( fig8 and 9 ). to free the cam plate for counter - clockwise return rotation , it is necessary to disengage the index follower 88 and the stop arm 89 from the cam plate . the stop arm release 91 , linked to the solenoid 82 , accomplishes this function . thus , as shown in fig8 when the reset solenoid 82 retracts its piston , the release arm 91 engages stop arm 89 to move the latter away from the cam plate 50 . this also disengages the index follower 88 , freeing the cam plate to rotate . the return spring 86 , attached to the cam plate at 100 and to a fixed location on the underside of the playfield 102 , then rotates the cam plate in the counter - clockwise direction . tooth - at - a - time return movement is accomplished due to the reset follower engaging the cam plate . this is due to the action of the piston of solenoid 82 which moves the release arm away from the stop 103 carried on the follower 90 . spring 92 brings the follower 90 into engagement with the next tooth on the cam plate . as shown in fig8 and 9 , this results in tooth - at - a - time return movement so that the game processor can accurately position the flippers . after each actuation of solenoid 82 , the spring 84 returns the release arm to its original position ( fig4 ). the follower 88 and stop arm 89 reengage the plate 50 and reset follower 90 is disengaged completing the cycle . as will be understood by those skilled in the art , the indexinq mechanism operates by utilizing the advance solenoid to step or index the cam plate 50 clockwise from the position shown in fig4 to any intermediate position , as represented in fig7 or 9 , or to the fully open position shown in fig1 . the return movement is accomplished by freeing the cam plate from the index follower and stop arm so that the return spring 86 can rotate the cam plate in the counter - clockwise direction . this return movement is also indexed a step at a time by the action of the reset follower which alternately engages and disengage the teeth of the cam plate . in this manner , the processor can accurately position the flippers at any desired location between the extremes of fig4 and 10 in an increment of the width of one cam tooth 52 . it will be understood that the only control signals required to operate the mechanism are the signals supplied to the solenoids 80 and 82 . solenoids , of course , are commonly used in pinball games and the appropriate circuitry for driving them from a microprocessor control system are well - known in this art . it will also be understood that the positioning means of the present invention can be used with playfield mechanisms other than flippers . for example , it can be used to variably position targets and ramps . such use is limited only by the creativity of the game layout designer . the mechanism is simply mounted to the plate 36 in a manner similar to the mounting of the flipper mechanism . while the principles of this invention have been described in connection with a specific embodiment thereof , it is to be understood that various changes in form and detail can be made without departing from the true spirit and scope of the claimed invention .
a variable position flipper mechanism is disclosed for use with pinball or rolling ball games . the flippers , actuated by solenoid mechanisms , are spaced a selectable distance apart thereby to permit adjustment in the skill level of the game . spacing of the flipper mechanisms is accomplished by rotating a cam plate which is ratcheted into various positions by a pair of solenoid operators and appropriate linkages . rotation of the cam plate in a first direction spaces the flippers at their maximum distance , while rotation in the opposite direction moves the flippers to successively closer positions . optical detection means can be associated with the cam plate to provide position information to a controller associated with the pinall machine .