Patent Publication Number: US-6902050-B2

Title: Coin mechanism of simplified construction and method of coin validity testing and vending machine operation

Description:
The present invention relates to a coin mechanism of the type typically used with a vending machine, and to testing the validity of a coin and operating a vending machine in response to detecting a valid coin. More particularly the present invention relates to a new and improved coin mechanism having a simplified construction involving fewer parts made of advantageous plastic materials which facilitate assembly of the coin mechanism, and a new and improved method of testing the validity of the coin and operating a vending machine. 
   BACKGROUND OF THE INVENTION 
   A coin mechanism is a device which accepts one or more coins, tests the validity of the coins, and permits the proper and intended operation of a vending machine to dispense a product from the machine in response to valid payment. In addition, the coin mechanism must retain the money accepted. In a sense, the coin mechanism acts as a lock or mechanism to prevent products from being dispensed from the vending machine until valid payment is made. 
   Coin mechanisms have, in the past, employed a relatively large number of parts and have been of relatively complex construction. The large number parts were required to perform the various distinct and important functions of coin acceptance, coin validity testing, and product dispensing. Moreover, the large number parts have usually been cast from metal. Many of the parts used in a conventional coin mechanism are also spring-biased. Metal parts interact on a reliable basis with metal spring elements which create the bias force necessary to make certain parts function effectively. 
   One of the disadvantages of previous coin mechanisms employing a relatively large number of metal parts, including springs, is that the assembly of the overall mechanism is complex and time-consuming. Orienting all the parts and connecting them together and inserting the springs between the parts involves a significant amount of human labor. The labor costs, as well as the increased costs associated with the fabricating a relatively large number of individual parts, has increased the cost of prior coin mechanisms. Furthermore, the costs of servicing such coin mechanisms is also relatively high, for the same reasons involving complexity in assembly and disassembly of the relatively large number of parts involved. 
   These and many other considerations applicable to previous coin mechanisms have given rise to the present invention. 
   SUMMARY OF THE INVENTION 
   The coin mechanism of the present invention offers a significant improvement in regard to reducing the number of individual parts which must be fabricated to construct a fully functional coin mechanism. Another improvement of the present invention is the capability of integrating multiple individual and separate parts into single parts which perform all the functions of the previous separate parts, thereby reducing the overall parts count of the coin mechanism. Reducing the parts count facilitates the assembly of the coin mechanism because a lesser number of parts must be assembled. The amount of time is required for assembly of the coin mechanism is reduced because of the integrated functionality provided by the lesser number of parts. Moreover, the fewer number of parts with the integrated multiple functionality are susceptible to fabrication from plastic by injection molding, which further reduces the manufacturing costs. The plastic parts have wear resistance and strength which are typically better than metal parts. Injection molded plastic parts are also generally less expensive to fabricate on a large-scale basis, compared to metal parts. The reduced number of parts, reduced fabrication cost and simplicity of assembly also facilitate service and repair of the coin mechanism, because any malfunctioning parts can be replaced on a convenient, economic and rapid basis. The present invention obtains all of these advantages and improvements, as well as others, without compromising the essential functionality of the coin mechanism of accepting only valid coins and permitting only the intended vending operation in response to valid payment. 
   In accordance with these and other improvements, a coin mechanism comprises a back plate and a coin wheel positioned to rotate adjacent and relative to the back plate. The coin wheel includes a receptacle within which to receive the coin. At least one test arm is integrally connected to the back plate and extends to a position over the coin wheel to contact the coin within the receptacle. The test arm moves in response to a characteristic of the coin contacted, and the degree of movement of the test arm indicates validity with respect to the tested characteristic. 
   A method of testing validity of a coin is also one of the improvements of the present invention. The method comprises positioning a coin in a receptacle of a coin wheel, positioning a back plate stationarily relative to the coin wheel, extending a test arm which is integrally connected to the back plate into contact the coin within the receptacle of the coin wheel, rotating the coin wheel in a first rotational direction with the coin in the receptacle, moving the test arm in response to contact with the coin in the receptacle in the coin wheel as or after the coin wheel rotates, and determining validity of the tested characteristic of the coin by the degree of movement of the test arm. One or more test arms may be employed to test multiple characteristics of the coin to determine its validity, including thickness, diameter and presence and absence of holes in the coin. 
   Preferred aspects of both the coin mechanism and the method of the present invention relate to preventing rotation of the coin wheel in at least one rotational direction until the test arm has moved to the degree necessary to indicate validity, while permitting rotation of the coin wheel in the other direction even if the coin is tested as invalid. Preferably, one or more test arms extend from the back plate in a cantilever manner. The degree of movement of each test arm which indicates validity preferably occurs in opposition to bias force resulting from deflecting the test arm, but the test arm is substantially free of bias force when in a non-deflected position. The coin mechanism is preferably connected to rotate a dispenser to dispense the vended product upon determining the validity of the coin, and an anti-rotational arm is preferably integrally connected to the back plate in a similar manner to prevent rotation of the coin wheel and the connected dispenser in a rotational direction opposite of the rotational direction which resulted in determining the validity of the coin. Each of the relatively few components used in the coin mechanism and involved in the validity testing method is preferably formed by injection molding from acetal plastic. Acetal plastic provides good strength, possesses resilience for spring memory characteristics, exhibits very good resistance to wear, and is capable of injection molding. 
   A more complete appreciation of the scope of the present invention and the manner in which it achieves the above-noted and other improvements can be obtained by reference to the following detailed description of a presently preferred embodiment taken in connection with the accompanying drawings, which are briefly summarized below, and by reference to the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front perspective view of a coin mechanism embodying the present invention, including a portion of an exterior housing, and a dispenser drum of the vending machine which is shown in an exploded relationship from the coin mechanism. 
       FIG. 2  is a rear perspective and exploded view of the coin mechanism, exterior housing portion and dispenser drum shown in FIG.  1 . 
       FIG. 3  is an exploded perspective view of the components of the coin mechanism shown in  FIGS. 1 and 2 . 
       FIG. 4  is an enlarged vertical cross-sectional view of the coin mechanism taken substantially in the plane of line  4 — 4  of FIG.  1 . 
       FIG. 5  is an enlarged elevation view of a coin wheel of the coin mechanism taken substantially in the plane of line  5 — 5  of FIG.  4 . 
       FIG. 6  is an enlarged rear elevation view of the coin mechanism shown in  FIG. 2 , with a portion of a back plate of the coin mechanism broken away to illustrate a home or stop position where the coin wheel shown in  FIG. 5  begins and ends rotational movement. 
       FIG. 7  is an enlarged rear elevation view of the coin mechanism, similar to  FIG. 6 , with a portion of the back plate of the coin mechanism broken away to illustrate a rotational position of the coin wheel where a diameter of an inserted coin is tested. 
       FIG. 8  is an enlarged rear elevation view of the coin mechanism, similar to  FIG. 7 , with a portion of the back plate of the coin mechanism broken away to illustrate a rotational position of the coin wheel where the inserted coin is tested to determine whether it has a hole. 
       FIG. 9  is an enlarged rear elevation view of the coin mechanism, similar to  FIG. 8 , with a portion of the back plate of the coin mechanism broken away to illustrate a rotational position of the coin wheel where product from a vending machine is dispensed. 
       FIG. 10  is an enlarged rear elevation view of the coin mechanism, similar to  FIG. 9 , with a portion of the back plate of the coin mechanism broken away to illustrate a rotational position of the coin wheel where the inserted coin is extracted. 
       FIG. 11  is a sectional view taken substantially in the plane of line  11 — 11  of  FIG. 6 , but with the coin shown in  FIG. 6  removed from the coin wheel. 
       FIG. 12  is a sectional view similar to  FIG. 11 , but showing the coin inserted in the coin wheel. 
       FIG. 13  is an enlarged view of a portion of  FIG. 7  showing a test arm in a position when no coin has been inserted in the coin wheel. 
       FIG. 14  is a view similar to  FIG. 13 , showing the test arm in a position to measure the diameter of an undersized coin inserted in the coin wheel. 
       FIG. 15  is a sectional view taken substantially in the plane of line  15 — 15  of  FIG. 8 , but with a washer replacing the coin shown in FIG.  8 . 
       FIG. 16  is a sectional view similar to  FIG. 15 , showing further rotation of the coin wheel in a forward direction relative to the position shown in FIG.  15 . 
       FIG. 17  is a sectional view taken substantially in the plane of line  17 — 17  of FIG.  9 . 
       FIG. 18  is a sectional view similar to  FIG. 17 , showing further rotation of the coin wheel in a forward direction relative to the position shown in FIG.  17 . 
       FIG. 19  is an enlarged partial perspective view of a portion of FIG.  10 . 
       FIG. 20  is an enlarged section view taken substantially in the plane of line  20 — 20  of FIG.  10 . 
       FIG. 21  is an enlarged partial sectional view taken substantially in the plane of line  21 — 21  of  FIG. 4 , illustrating features also shown in  FIGS. 10 and 19 . 
       FIG. 22  is an enlarged perspective view of an alternative embodiment of a coin wheel similar to that shown in FIG.  5 . 
       FIG. 23  is enlarged perspective view of another alternative embodiment of a coin wheel similar to that shown in  FIG. 5 , shown in exploded relationship. 
       FIG. 24  is a view of the coin wheel shown in  FIG. 23 , shown partially and from a different perspective. 
       FIG. 25  is a perspective view of the coin wheel shown in  FIGS. 23 and 24  shown in an assembled relationship. 
   

   DETAILED DESCRIPTION 
   An embodiment of a coin mechanism  30  which operates in regard to a single coin and which incorporates the present invention is generally shown in  FIGS. 1-21 . As shown primarily in  FIGS. 1-4 , the coin mechanism  30  includes a front plate  32 , a handle  34  with a connected shaft  36  which is inserted through the front plate  32 , a coin wheel  38  which is connected to the shaft  36 , and a back plate  40  which is positioned relative to the front plate  32  by the shaft  36  and by screws  42 . In the assembled coin mechanism  30 , the coin wheel  38  is located and positioned for rotation between the front plate  32  and the back plate  40 . The coin mechanism  30  is attached to an outside housing  44  of a vending machine (not otherwise shown). The front plate  32  is located on the front or outside surface of the housing  44  and the back plate  40  is located on the back or inside surface of the housing  44 . The screws  42  hold the front and back plates of the coin mechanism  30  in assembled relationship with respect to one another, and also retain the coin mechanism to the vending machine by capturing the housing  44  between the front plate  32  and the back plate  40 . 
   The front plate  32  includes a cylindrical hole  46 , and the back plate  40  includes a cylindrical hole  48 , through which the shaft  36  extends. A cylindrical surface  50  ( FIG. 3 ) is formed on the shaft  36  adjacent to the handle  34 . The cylindrical surface  50  is received within the cylindrical hole  46 . The shaft  36  is square or rectangular in cross-section at locations other than the cylindrical surface  50 . A correspondingly-shaped square or rectangular hole  52  is formed in the coin wheel  38 , and the square cross-sectional portion of the shaft  36  fits within the square hole  52 . A cylindrical sleeve  54  surrounds the square hole  52  in the coin wheel  38 . The cylindrical sleeve  54  extends within the cylindrical hole  48  of the back plate  40 . An end piece  56  is connected to the end of the shaft  36  by a screw  58 . The end piece  56  contacts the backside of the back plate  40  and prevents the shaft  36  from moving axially forward out of the coin mechanism  30 . The end piece  56  includes a square or rectangle or terminal end shape which fits within a correspondingly shaped square or rectangular opening in an end wall of a dispenser drum  64  (FIG.  1 ). 
   Twisting the handle  34  rotates the shaft  36  and the connected coin wheel  38  between the stationary front and rear plates  32  and  40 . A coin  60  ( FIG. 1 ) is inserted in a receptacle  62  of the coin wheel  38  when the coin wheel  38  occupies a home or stop position shown in  FIGS. 1 ,  3 ,  4  and  6 . Inserting a coin  60  of valid thickness releases the coin wheel  38  for rotational movement from the home position (FIG.  6 ). Forward rotational movement is in the clockwise direction shown in FIG.  1  and rotational movement in the rearward direction is in the counterclockwise direction shown in  FIGS. 2 ,  3  and  6 - 10 . 
   Forward rotational movement of the coin wheel  38  from the home position shown in  FIG. 6  positions the inserted coin  60  at the position shown in  FIG. 7 , where the diameter of the inserted coin  60  is tested. Provided that the inserted coin  60  has the diameter of a valid coin, further rotation of the coin wheel of  38  in a forward direction is possible and the inserted coin  60  is moved forward to the position shown in FIG.  8 . At the position shown in  FIG. 8 , the inserted coin  60  is tested to determine whether it has a hole in its center and the thickness of the coin is checked again. Valid coins do not have center holes. The thickness, diameter and hole tests performed at the rotational positions shown in  FIGS. 6 ,  7  and  8 , respectively, determine whether the inserted coin  60  is valid payment for the product to be dispensed from the vending machine. 
   Upon confirming the validity of the coin  60 , further rotation of the handle  34  and shaft  36  rotates a connected dispenser drum  64  ( FIGS. 1 and 2 ) to a position or orientation where product (not shown) within the dispenser drum  64  dumps or spills out of the rotated dispenser drum  64  through an opening  66  formed in the dispenser drum  64 . In this position, the handle  34  and the connected dispenser drum  64  are prevented from being rotated back and forth in oscillating manner to attempt illegitimately to reload the dispenser drum  64  through the opening  66  with additional product and dispense the additional product with only the single payment represented by the single coin  60 . Reloading the dispenser drum  64  with product occurs when the opening  66  in the dispenser drum  64  faces upward. Preventing the dispenser drum  64  from rotating in the reverse direction prevents reloading the dispenser drum after the product has been dumped from the opening  66 . The dispenser drum  64  is connected to the coin mechanism by inserting the square or rectangular shaped portion of the terminal end piece  56  ( FIG. 2 ) into a correspondingly shaped opening formed in an end wall of the dispenser drum  64 , as understood from FIG.  1 . In this manner, rotation of the shaft  36  and the connected end piece  56  also rotates the dispenser drum  64 . 
   After the product has been dispensed, further forward rotation positions the coin wheel  38  at the position shown in FIG.  10 . In this position, the coin  60  is extracted from the receptacle  62  in the coin wheel  38 . The extracted coin is directed by gravity from the coin mechanism  30  into a secure collecting container of the vending machine (not shown). Further rotational movement from the position shown in  FIG. 10  returns the coin wheel  38  back to the home or stop position shown in  FIG. 6 , where the coin validity determining and product dispensing sequence may begin again upon the insertion of another coin and again twisting the handle  34 . More product is also reloaded through the opening  66  of the dispenser drum  64  while in the home or stop position. 
   The manner in which the relatively few parts of the coin mechanism  30  interact with each other to accept the coin, to test its validity, to vend only a single quantity of the dispensed product, to extract the coin and to return to begin another such sequence is described in greater detail below. 
   At the home stop position shown in  FIG. 6 , an arm  68  of the back plate  40  normally positions a pin  70  ( FIG. 11 ) and its lower end  75  within a hole  72  ( FIGS. 5 and 11 ) formed in the coin wheel  38 . The arm  68  is formed as an integral part of a generally planar structure of the back plate  40 . A U-shaped slot  74  ( FIGS. 2 and 3 ) separates the arm  68  from the other portion of the back plate  40 , but leaves the arm  68  attached to the back plate  40  to extend in a cantilevered manner. The pin  70  is located at the terminal end of the arm  68  opposite of the integral connection of the arm  68  to the back plate  40 . As shown in  FIG. 11 , the pin  70  extends from the arm  68  toward the coin wheel  38  to a greater distance than the back plate  40  is separated from the coin wheel  38 . When the coin mechanism  30  is not used and no coin  60  is inserted in the receptacle  62  of the coin wheel  38 , the arm  68  extends essentially in a planar relationship with the remaining portion of the back plate  40  and occupies a normal, relaxed, non-biased state. 
   In the normal, non-biased position of the arm  68 , the pin  70  extends into the hole  72  of the coin wheel  38 , as shown in FIG.  11 . The pin  70  is generally cylindrical in cross-section, and is slightly smaller in diameter than the diameter of the hole  72 , thereby permitting the pin  70  to move into the hole  72 . With the pin  70  in the hole  72 , the coin wheel  38  can not be rotated in the reverse direction. 
   The handle  34  and the coin wheel  38  can only be rotated in the forward direction as a result of inserting a proper-thickness coin  60  into the receptacle  62  of the coin wheel  38 . When the coin  60  is inserted in the receptacle  62 , an edge of the coin  60  initially contacts a beveled surface (not shown) on the side of the pin  70  leading to a lower end  75  of the pin  70 . The edge of the coin  60  slides along this beveled surface and forces the arm  68  upward, away from the coin wheel  38 , as shown in  FIGS. 6 and 12 . Because the thickness of the receptacle  62  is the same as the thickness of the coin  60 , the lower end  75  of the pin  70  is approximately at the level of an upper surface  76  of the coin wheel  38 , as shown in FIG.  12 . In this position, the pin  70  is withdrawn from the hole  72  and will no longer serve as an impediment to rotating the coin wheel  38 . If the coin  60  is invalid because it has less than the desired thickness, the lower end  75  of the pin  70  will not be elevated to the upper surface  76  of the coin wheel  38 . Instead the lower end  75  will remain partially in the hole  72 , to prevent rotation of the coin wheel  38 . 
   As shown in  FIGS. 11 and 12 , the pin  70  has a cylindrical sidewall  80  which extends from the arm  68 . The cylindrical sidewall  80  directly confronts a cylindrical sidewall  82  of the of the hole  72 . Consequently, rotational movement of the coin wheel  38  is stopped and prevented because of the contact of the sidewalls  80  and  82  when the coin wheel  38  is rotated to the stop position. However, a beveled surface (not shown) located on a side of the pin  70  permits a coin  60  inserted in the receptacle  62  to lift or move the arm  68  to a position which releases the coin wheel for rotation from the home position in the forward direction as shown in FIG.  6 . 
   If an invalid coin which is too thick is attempted to be inserted into the receptacle  62 , the shallower depth of the receptacle  62  will prevent that invalid coin from being inserted into the receptacle  62 . If an invalid coin which is too thin is inserted into the receptacle  62 , its thickness will be insufficient to lift the lower end  75  of the pin  70  completely out of the hole  72 , and a small portion of the cylindrical surfaces  80  and  82  will remain in contact with one another to prevent rotation of the coin wheel  38  in the forward direction. 
   When the coin wheel  38  rotates from the home position shown in  FIG. 6 , the lower end  75  of the pin  70  of the arm  68  rides on top of a ridge which is located beyond the outside circumference of a groove  84  ( FIG. 5 ) in the coin wheel  38  between grooves  84  and  136 . A slanted surface  86  ( FIG. 5 ) is located at the opposite end of the groove  84 . The arm  68  thus moves out of its normal, non-biased position only when a coin  60  is inserted into the receptacle  62  and the coin mechanism  30  is operated. Even then, the bias force induced on the arm  68  is only momentary, because insertion of the coin  60  is followed immediately by rotation of the coin wheel  38  to start the coin testing and product vending sequence. Consequently, the stop and release arm  68  does not experience bias force or tension for a significant amount of time. By minimizing the time during which the bias force is applied, the arm  68  is not permanently deformed, but instead the resiliency of the arm  68  is maintained at an effective level to function in the manner described. Minimizing the time of application of the bias force allows the arm  68  to be formed from the same type of material, preferably acetal plastic, as the back plate  40 , so that its spring memory characteristics are maintained. 
   With the arm  68  biased by the inserted coin  60  to a position which allows rotation of the coin wheel  38 , twisting the handle  34  rotates the coin wheel  38  in the forward direction to the position shown in  FIG. 7 , where a lever  90  tests the diameter of the inserted coin  60 . As shown in  FIGS. 7 ,  13  and  14 , the lever  90  includes a circular ball-like end  92  which is pivotally received in a cylindrical socket  94 . The cylindrical socket  94  is formed in the front plate  32 . An end  96  of the lever  90 , which is opposite of the ball end  92 , has a surface which extends slightly less than perpendicular with respect to the longitudinal dimension of the lever  90 . A bias lever portion  98  extends from the lever  90  in the opposite direction from the coin wheel  38  and contacts a boss  100  formed in the front plate  32 . One of the screws  42  ( FIG. 3 ) extends into the boss  100  when the back plate  40  is attached to the front plate  32 . 
   The bias lever portion  98  of the lever  90  normally biases the arm  90  toward a clockwise direction as shown in  FIGS. 7 ,  13  and  14 , as a result of its contact with the boss  100 . In this normal position, shown in  FIG. 13 , the end  96  will normally extend into the receptacle  62  to a position which is slightly radially inward from the outer circumferential surface  102  of the coin wheel  38 . Consequently, if the coin wheel  38  is rotated with the insertion of a coin of less than the proper proper diameter, the end  96  will contact an inward-extending corner surface  104  of the receptacle  62  to prevent further forward rotation of the coin wheel. In this manner, the lever  90  prevents rotation of the coin wheel  38  past the position shown in  FIG. 13  if the coin inserted in the receptacle  62  is less than the proper diameter. Coins of greater than the proper diameter can not be inserted because the receptacle  62  is sized to prevent the insertion of coins of larger than the desired diameter. 
   The lever  90  includes a contact surface  106  located approximately midway between the ends  92  and  96  on the side of the lever  90  which faces the coin wheel  38 . With a coin  60  inserted in the receptacle  62  (FIGS.  7  and  14 ), the contact surface  106  will contact and ride up on the outside circular surface  108  of the coin  60  as the rotating coin wheel  38  moves the coin in the forward rotational direction, as shown in FIG.  14 . Contact with the outside circumferential surface  108  of the proper diameter coin  60  pivots the lever  90  in a clockwise direction around the end  92 , as shown in  FIG. 14 , as a result of the contact surface  106  contacting the outside surface  108  of the coin  60 . If the diameter of the inserted coin  60  is correct, the end  96  of the lever  90  will move radially outward slightly beyond the outside circumferential surface  102  of the coin wheel  38 , as shown in FIG.  7 . In this radially outward position, the end  96  will not contact the corner surface  104 . The coin wheel  38  can therefore continue further forward rotational movement. However, if the diameter of the inserted coin  60  is too small, the end  96  will not pivot outward a sufficient distance for the end  96  to clear the corner surface  104  of the receptacle  62 , and instead the end  96  will contact the corner surface  104  to prevent further forward rotation of the coin wheel  38 , as shown in  FIG. 14. A  coin  60  having a diameter which is too small will still permit the reverse or rearward rotation (clockwise as shown in  FIGS. 7 ,  13  and  14 ) of the coin wheel  38 , because the pivot position of the arm  90  at the ball end  92  and length of the arm  90  are incapable of contacting any portion of the coin wheel  38  to interfere with rearward rotation. Permitting rotation in the reverse direction back to the home position allows extraction of an improper coin from the coin receptacle  62 . 
   The bias lever portion  98  of the arm  90  undergo bias only when the contact surface  106  contacts the outside circumferential surface  108  of the inserted coin  60  and/or the outside circumferential surface  102  of the coin wheel  38 . When the coin wheel  38  is in the home position (FIG.  6 ), the end  96  of the lever  90  is located in a recess  109 , shown in  FIG. 5 , formed the outside circumferential surface  102  of the coin wheel  38 . The recess  109  ( FIG. 5 ) extends radially inward to the extent necessary to prevent any deflection on the bias lever portion  98  of the arm  90 , thereby eliminating any bias force on the arm  90  when it is in the normal, home position. The bias lever portion  98  contacts the boss  100  and deflects slightly to create a bias force in a direction toward the coin wheel  38  only when the end  96  of the lever  90  contacts the outside circumferential surface  102  of the coin wheel  38  or the outside circumferential surface  108  of the inserted coin. The deflection is resisted by the strength of the material, preferably acetal plastic, from which the arm  90  is made. The deflection forces the contact surface  106  firmly against the outside circumferential surface  108  of the coin  60 . In this manner, the bias force assures that an accurate measurement of the diameter of the coin  60  will be made, and further assures that undersized coins will not permit the coin wheel  38  to be rotated beyond the position shown in  FIG. 7 , as a result of the bias force from the bias lever portion  98  forcing the end  96  into contact with the corner surface  104 . 
   With a proper diameter coin  60 , the coin wheel may be rotated in the forward direction to the next position shown in FIG.  8 . At the position shown in  FIG. 8 , an arm  110  tests for the presence or absence of a hole  112  ( FIGS. 15 and 16 ) in the inserted object and again tests for the proper thickness. The presence of a hole  112  in the center of the inserted object indicates an invalid coin, such as a washer  114 , for example. The arm  110  is connected to the back plate  40 , preferably as an integrated, cantilevered structure created by a slot  116  in essentially the same manner as the arm  68  is connected to the back plate  40  (FIG.  6 ). 
   A contact extension  118  extends toward the coin wheel  38  from a forward end  120  of the arm  110 , as shown in FIG.  15 . Normally, the contact extension  118  extends into the groove  84  (FIG.  5 ). Clearance exists between the lowermost point of the contact extension  118  and the bottom of the groove  84 . However, When the coin wheel  38  is rotated toward the position shown in  FIG. 8 , the slanted surface  86  contacts the contact extension  118  and pushes the contact extension  118  of the arm  110  upward. In this position, the contact extension  118  rests on a surface  122  ( FIGS. 5 and 15 ) slightly rotationally in advance of the receptacle  62 . Thus, the arm  110  is biased away from the coin wheel  38  before the coin  60  or washer  114  is moved into contact with the contact extension  118 . 
   As the coin wheel  38  rotates in the forward direction, the valid coin  60  or invalid washer  114  moves into position beneath the contact extension  118 . The contact extension  118  first moves over the upper surface of the coin  60  or washer  114 , as shown in FIG.  15 . If a valid coin  60  (not shown in  FIGS. 8 ,  15  or  16 ) is present in the receptacle  62 , the contact extension  118  will continue to ride over the upper surface of the valid coin  60  as the coin wheel  38  continues to rotate in the forward direction. However, if a washer  114  is present in the receptacle  62  (as shown in  FIGS. 8 ,  15  and  16 ), the bias from the upward-deflected arm  110  pushes the contact extension  118  into the hole  112  of the washer  114 , when the hole  112  rotates beneath the contact extension  118 , as shown in FIG.  16 . Once the contact extension  118  is located in the hole  112 , a surface  124  of the contact extension  118  contacts a surface of the washer  114  created by the hole  112 . The contact of the surface  124 , which faces in the reverse rotational direction, with the surface of the washer  114  formed by the hole  112  prevents any further forward rotational movement of the coin wheel  38 . Because the surface  124  of the contact extension  118  and the surface caused by the hole  112  are generally parallel to one another and perpendicular to the direction in which the washer  114  is moved in the forward direction while within the coin receptacle  62 , the contact extension  118  will not ride up out of the hole  112 , even when considerable force is applied to attempt to rotate the coin wheel  38  in the forward direction. In this manner, further forward rotational movement of the coin wheel is prevented upon detecting an invalid coin having a hole in its center, such as the washer  114 . 
   The arm  110  also performs a second and more precise test of the thickness of the coin  60 . As the contact extension  118  rests on the upper surface of the coin  60  when the coin wheel  38  carries the coin  60  in the forward rotational direction, an invalid coin  60  of less than the desired diameter will not elevate the lower surface of the contact extension  118  to the full thickness of the coin wheel  38 . Instead, the contact extension  118  to remain slightly within the coin receptacle  62  due to the lesser thickness of the invalid coin, as can be understood from FIG.  15 . Further forward rotation of the coin wheel  38  under these circumstances results in the surface  124  of the contact extension  118  contacting the corner surface  104  of the receptacle  62 , because the invalid coin  60  has insufficient thickness to lift the lower surface of the contact extension  118  up to the level of the corner surface  104 . The forward-facing surface  124  contacts the corner surface  104 , and prevents further forward rotation of the coin wheel  38  in a manner similar to the circumstance illustrated in FIG.  16 . 
   Thus, the arm  110  detects invalid coins in the form of a washer  114  and which have less than the desired thickness. Upon detecting a washer  114 , the contact extension  118  falls into the hole  112  and prevents the coin wheel  38  from continuing forward rotational movement. Upon detecting a coin  60  of invalid thickness, the contact extension contacts and abuts the corner surface  104  of the coin receptacle  62  and prevents the coin wheel  38  from continuing further forward rotational movement. However, a beveled surface  128  of the contact extension  118  will permit rotation of the coin wheel  38  in the reverse direction (left to right movement of the coin wheel  38  as shown in  FIG. 15 ) so that the coin wheel  38  can be returned to the home position for removal of the invalid washer  114  or the invalid coin of insufficient thickness. 
   In a similar manner to the arm  68  (FIG.  6 ), the normal position of the arm  110  results in no bias force being applied to it. The contact extension  118  normally extends into the groove  84  (FIG.  5 ), and no bias force is applied on the arm  110  until the coin mechanism  38  is operated with a valid coin  60  or invalid washer  114 . Since the deflection of the arm  110  occurs intermittently, the natural resilience and strength of the material, preferably acetal plastic, from which the arm  110  is formed is sufficient to apply the bias force necessary to test for the hole  112 , without fatiguing the plastic material to the point where inadequate bias force is available to perform the hole and thickness tests. 
   The testing arms  68 ,  90  and  110  therefore operate in the manner described to detect the thickness, diameter and the presence or absence of the hole in the coin. These three tests determine whether or not the coin is valid. If a coin is determined to be invalid in any of these three tests, it is not possible to rotate the coin wheel  38  further in the forward direction to dispense the product out of the opening  66  of the dispenser drum  64  (FIGS.  1  and  2 ). However, detecting an invalid coin permits the coin wheel  38  to be rotated in the reverse direction to the home position ( FIG. 6 ) to permit the invalid coin to be withdrawn from the receptacle. Permitting the coin wheel  38  to be returned to the home position offers the opportunity to remove the invalid coin so that legitimate authorized vending operations can proceed without the necessity for service and repair of the coin mechanism. 
   Detecting a valid coin  62  constitutes authorization to vend the product. Vending the product is accomplished by further forward rotation of the coin wheel  38 , from the position shown in  FIG. 8  to the position shown in FIG.  9 . In the position shown in  FIG. 9 , the dispenser drum  64  ( FIGS. 1 and 2 ) has been rotated sufficiently so that the contents will spill or dump from the opening  66  into a dispensing chute or conduit (not shown) within the vending machine (also not shown). The product moves through the chute or conduit to location where it is collected by the purchaser. 
   To permit only a single quantity of product to be dispensed through the opening  66  of the dispenser drum  64 , the coin mechanism  38  employs and anti-return arm  130 . The anti-return arm  130  is also integrally formed by a slot  132  in the backplate  40  to extend in the cantilevered manner. The anti-return arm  130  has the same previously-described characteristics as the arm  110  and the arm  68 . The anti-return arm  130  includes a ratchet extension  134  ( FIGS. 17 and 18 ) which extends into a groove  136  (FIG.  5 ). As shown in  FIG. 5 , a number of divider walls  138  extend across the groove  136  at a plurality of circumferentially spaced locations. 
   A relatively lengthy portion  140  of the groove  136  (approximately one-fourth of the circumference of the groove  136  in the coin wheel  38 ) does not include divider walls  138  within it, as shown in FIG.  5 . When the coin wheel  38  is in the home position (FIG.  6 ), the ratchet extension  134  is located within the portion  140  of the groove  136 . Moreover, the portion  140  of the groove  136  extends a sufficient circumferential distance to locate the ratchet extension  134  within it while the coin wheel  38  is rotated through the coin validity testing positions ( FIGS. 6-8 ) where the thickness, diameter and presence and absence of a center hole are tested. The ratchet extension  134  extends into the groove  136  only that amount of distance which provides a clearance space between the ratchet extension  134  and the groove  136 . Thus, while the ratchet extension  134  is located within the groove portion  140 , it does not influence the forward or return rotation of the coin wheel  38 . 
   Upon completing the tests for a valid coin, a beveled surface  142  of the ratchet extension  134 , shown in  FIGS. 17 and 18 , contacts a first divider wall  138   a  which rotationally follows the groove portion  140  (FIG.  5 ). The beveled surface  142  of the ratchet extension  134  rides up on the divider wall and biases the anti-return arm  130  upward. Further forward rotation of the coin wheel  38  causes a perpendicular surface  144  of the ratchet extension  134  to move past a back vertical surface  146  of the divider wall  138 . At this point, the bias from the anti-return arm  130  moves the ratchet extension  134  back into the groove  136 . From the rotational position shown in  FIG. 17 , an attempt to rotate the coin wheel  38  in the reverse direction will result in the perpendicular surface  144  of the ratchet extension  134  contacting the vertical surface  146  of the divider wall  138 , as shown in FIG.  18 . The contact of the surfaces  144  and  146  prevents further reverse rotation of the coin wheel. Under these conditions, it is only possible to continue rotating the coin wheel  38  in the forward direction to deposit the coin and dispense the product from the vending machine. 
   The divider walls  138  are relatively closely spaced throughout the remaining portion of the groove  136  not occupied by the portion  140 . The relatively close spacing of the divider walls  138  permits only a relatively small amount of reverse movement, and that relatively small amount of reverse movement is insufficient to reverse the rotational position of the dispenser drum  64  enough reload it with product through the opening  66  ( FIGS. 1 and 2 ) after the initial full amount of product has been dispensed. The contact of the ratchet extension  134  with the divider walls  138  thus prevents an attempt to oscillate the dispenser drum  64  back and forth to reload and to dump on the repeated basis multiple quantities of the product with only a single payment. The effect of the ratchet extension  134  with the divider walls  138 , and the bias from the anti-return arm  130  and the movement available from the beveled surface  142  permits only further forward rotation of the coin wheel, after a single quantity of the product has been dispensed, until the home position ( FIG. 6 ) is reached. 
   As shown in  FIG. 5 , the divider walls  138  have a concave curvature. This concave curvature forces the surface  144  of the ratchet extension  134  into the center of the divider wall  138  and therefore establishes firm restraint against reverse rotational movement. Moreover, the anti-rotation arm  130  is not retained in a deflected position when the coin mechanism  30  is not in use. Accordingly the material, preferably acetal plastic, from which the anti-rotation arm  130  is formed will not lose its structural spring memory characteristic and resilience because of continual deflection. Instead, the relatively short intermittent deflections experienced by the anti-rotation arm  130  are not sufficient to reduce its ability to create sufficient bias to prevent reverse rotation. 
   Upon rotating the coin wheel  38  further in the forward direction, as permitted by the anti-return arm  130 , the coin  60  in the receptacle  62  is extracted at the rotational position shown in FIG.  10 . The extraction occurs as a result of a protrusion  150  contacting the outside circular surface  108  of the coin  60  and dislodging the coin  60  out of the receptacle  62 . An opening or cut out portion  151  of the back plate  40  permits the coin  60  to be moved out of the receptacle  62 , because the cut out portion  151  of the back plate  40  does not confine the coin  60  within the receptacle  62 . The protrusion  150  extends from the back plate  40  into a groove  152  ( FIG. 5 ) of the coin wheel  38 , as shown in  FIG. 10 and 19 . A clearance exists between the protrusion  150  and the groove  152  to prevent the protrusion  150  from interfering with normal rotation of the coin wheel  38 . The groove  152  opens into the receptacle  62  (FIG.  5 ). 
   As the coin  60  in the receptacle  62  moves into contact with the protrusion  150  (FIG.  20 ), continued rotation of the coin wheel  38  in the forward direction pushes the outside circular surface  108  against the protrusion  150  (FIG.  10 ), forcing the coin  60  radially outward from the receptacle  62 . A series of inclines  154  extend rearwardly from the front plate  32  beneath the protrusion  150 , as shown in FIGS.  10  and  19 - 21 . As the coin  60  moves radially outward from the receptacle  62 , the coin  60  contacts the inclines  154  to help separate the coin from the coin mechanism  30 . The extracted coin falls by gravity into a chute or conduit which leads to a secure container within the vending machine (not shown). Thereafter, continued forward rotation, permitted by the anti-return arm  130 , returns to the coin wheel  38  to the home position (FIG.  6 ), to allow another coin validity testing and product vending sequence to commence upon the insertion of another coin  60  and rotation of the handle  34  (FIG.  1 ). While in the home position, the opening  66  of the dispenser drum  64  ( FIGS. 1 and 2 ) is facing upward to allow the dispenser drum to be reloaded with product. 
   An alternative form of the coin mechanism  30  which may be used to accept and test multiple coins inserted as a single payment for dispensed product, makes use of a coin wheel  160  shown in FIG.  22 . All other components of this multiple coin form of the coin mechanism itself are the same as have been described previously. The orientation of the square or rectangular hole in the end wall of the dispenser drum  64  ( FIG. 1 ) is retarded in rotational orientation when the coin wheel  160  is employed, as described below. 
   The coin wheel  160  includes the first coin receptacle  62  and a second coin receptacle  162 . The second coin receptacle  162  is located at a circumferential position on the coin wheel  60  which rotationally follows the first coin receptacle  62 . Both coin receptacles  62  and  162  have essentially the same characteristics as previously described. Using the coin wheel  160  permits a first coin to be inserted in the first coin receptacle  62 , and after the coin wheel  160  is rotated slightly in the forward direction, and permits a second coin to be inserted into the coin receptacle  162 . Dispensing the product requires both coins to be inserted for payment. If the first coin inserted into the first coin receptacle  62  does not test validly by the functionality of the arm  68 , in the same manner as previously described, it is not possible to rotate the coin wheel  160  into the second position where the second coin can be inserted into the second coin receptacle  162 . 
   If both coins inserted into the receptacles  62  and  162  test favorably by the functions performed by the arm  68 , further forward rotation of the coin wheel tests each of the coins for the proper diameter as a result of the functionality performed by the arm  90 , in the same manner as previously described in conjunction with  FIGS. 13 and 14 . If either the first coin in the first coin receptacle  62  or the second coin in the second coin receptacle  160  is found to be of insufficient diameter, the arm  90  prevents further forward rotation movement of the coin wheel  160  in the same manner as previously described. However, reverse rotational movement of the coin wheel  160  is permitted to remove both of the coins of insufficient diameter, in the manner previously described, even if the first coin in the first coin receptacle  62  is valid but the second coin in the second coin receptacle  162  is invalid. 
   In a similar manner, if either of the coins in the receptacles  62  or  162  is a washer  114 , or if either of the coins are of insufficient thickness, as tested by the arm  110 , further forward rotation of the coin wheel  160  will be prevented in the same manner as previously described. A washer(s) or an invalid coin(s) of insufficient thickness can still be removed from the coin mechanism  30  as a result of reverse rotational movement of the coin wheel  160 , in the manner and for the reasons previously described. 
   Once the coins in the receptacles  62  and  162  have been tested as valid, the anti-return arm  130  prevents the reverse rotation of the coin wheel  160  in the same manner as has previously been described. However, because it is necessary to test two coins in the two receptacles  62  and  162 , the location of the divider wall  138   a  in the groove  136  is positioned at a position which is rotationally delayed or retarded in the coin wheel  160 , as compared to the position of the divider wall  138   a  in the groove  136  of coin wheel  38  shown in FIG.  5 . Moreover, the number of divider walls when  38  in the groove  136  is reduced in the coin wheel  160 , and shown in FIG.  22 . 
   The rotational orientation of the dispenser drum  64  relative to the end piece  56  of the coin mechanism is retarded by approximately forty-five rotational degrees when the two-coin form of the coin wheel  160  is employed in the coin mechanism  30 . The retarded orientation is achieved by changing the orientation of the square or rectangular hole formed in the end wall of the dispenser drum  64  ( FIG. 1 ) or changing the orientation of the square or rectangular shaped portion on the end piece  56  (FIG.  1 ). The retarded position of the dispenser drum  64  orients the opening  66  of the dispenser drum  64  to prevent any product within the dispenser drum  64  from spilling from the container  66  ( FIGS. 1 and 2 ) as the second of the two coins is tested for validity. If the opening  66  in the dispenser drum  64  was not rotationally retarded in position, it might be possible to “bleed” product from the vending machine by rotating the coin wheel to the position where a second coin was tested and found to be invalid and then back to the home position on a repeated basis. Such rotational oscillation is possible because reverse rotation back to the home position is possible when second coin tests invalid. By rotationally retarding the position of the opening  66  in the dispenser drum  64  ( FIG. 1 ) when the two-coin form of the coin wheel  160  is used, the orientation of the opening  66  prevents the contents of the dispenser drum  64  from spilling out until after the second coin has been tested and determined to be valid. Furthermore, rotationally retarding the position of the opening  66  in the dispenser drum  64  also prevents the dispenser drum from being loaded with product until the second coin has been tested as valid. The first divider wall  138   a  is located within the groove  136  of the coin wheel  160  to prevent reverse rotation of the coin wheel  160  after the second coin has been tested as valid. 
   Use of the coin wheel  160  in the coin mechanism permits larger payments to be obtained for vending more expensive products than would otherwise be obtained by payment from a single coin. Larger payments for more expensive dispensed products may also be obtained by stacking two coins, one on top of the other, in one or two coin receptacles  62  in another form of a coin wheel (not shown), provided that the coin receptacle(s) and the coin wheel are sufficiently thick to permits stacking the coins. The arms  68 ,  90  and  110  will perform most of their essential functions under this stacked-coin situation, except that locating a washer  114  below a valid coin  60  will prevent the arm  110  from detecting the washer. If a single arm  90  is employed, it will respond to the diameter of the one of the coins with which it is aligned. However, two diameter-detecting arms  90  may be located or stacked in a vertically positioned relationship with respect to one another, so that each of the arms is aligned with and capable of detecting the diameter of each individual stacked coin. Under these circumstances, operation of the coin mechanism will be prevented if either one of the two stacked coins is of invalid diameter. 
   Typically, a different coin wheel must be fabricated for each coin which is to be accepted as payment. Consequently, different coin wheels require different molds because each of the coin receptacles is of a different size. Alternatively, each coin receptacle can be milled from the plastic, but milling the coin receptacles adds to the manufacturing cost. Since a considerable amount of the cost associated with forming plastic parts is the direct result of fabricating the mold for those plastic parts, the costs may be reduced by creating a coin wheel  170  which is formed by a common portion  172  and by an insert portion  174 , as shown in  FIGS. 23-25 . The common portion  172  is similar to and contains the previously-described features of the coin wheel  38 , other than those features which are contained an insert portion  174 . The insert portion  174  contains the coin receptacle  62  which is uniquely sized to accept each unique size of coin. The insert portion  174  is connected to the common portion  172  to form the complete coin wheel  170  as shown in FIG.  25 . 
   The insert portion  174  fits within a cut out area  176  formed by the common portion  172 . The insert portion  174  includes the square or rectangular hole  52  and the cylindrical sleeve  54 . The grooves  84 ,  136  and  152  continue into the insert portion  174 , and the inclined surface  86  is also formed on the insert portion  174 . To hold the insert portion  174  firmly with respect to the common portion  172 , a hook  178  and two wings  180  and  182  are formed on the insert portion  174 . The wings  180  and  182  fit on the front and rear sides, respectively, of the common portion  172 , as shown in  FIGS. 23-25 . The hook  178  fits into a receptacle (not shown) on the back side of the common portion  172 . The hook  178 , in its position within the receptacle (not shown), prevents the insert portion  174  from being withdrawn out of the cut out area  176  in a radial direction relative to the common portion  172 . The wings  180  and  182  prevent the insert portion from moving axially forward or rearward out of the cut out area  176 . In addition, once the coin wheel  170  is retained between the front plate  32  and the back plate  40  ( FIGS. 1-3 ) in the coin mechanism, there is additional support for preventing the insert portion  172  from separating in axial and radial directions out of the cut out area  176  of the common portion  172 . 
   A coin wheel  170  of the type having the insert portion  174  with a coin receptacle  62  specifically sized to accept a particular coin, and a common portion  172  which incorporates the remaining common features in the coin wheel, permits the same coin mechanism to be used economically for a wide variety of different coins, without incurring the additional and considerable expenses of creating a separate mold for each different coin wheel. The use of the insert portion  174  is a particular advantage when it is necessary to accommodate a variety of different denominations and sizes of coins, particularly coins which are larger in diameter than is typical. Different molds for only the insert portions  174  are required, and those different molds differ only by the size of the coin receptacle  62 . Moreover, dividing the coin wheel  170  into the common portion  172  and the insert portion  174  allows the size of the coin receptacle  62  to be milled or machined to into the insert portion  174 . In this circumstance, only two molds are required, one for the common portion  172  and one for the insert portion  174 . Differences in coin size are accommodated by milling the desired shape and size of the coin receptacle  62  into only the insert portion  174 , or by separately forming only the insert portion  74  for each different size of coin. 
   As shown in  FIG. 3 , the entire coin mechanism  30  is formed by only six components, not including the screws to hold those components together. Of those six components, the major functions of coin validity testing and vending are achieved by the interaction of the coin wheel  38  and the arms  68 ,  90 ,  110  and  130 . The arms  68 ,  110  and  130  are integrally formed with the back plate  140 . Preferably all the components (other than the screws) are formed by injection molding from durable and resilient plastic material or engineering resin, such as acetal. Forming the coin mechanism components from molded plastic permits those components to be manufactured efficiently and economically with a high degree of precision. Moreover, the configurations of the various elements which perform the thickness testing, diameter testing and hole presence testing on the coin and which perform the anti-rotation and coin extraction functions, are readily established by the characteristics of the molds from which those components are molded and the characteristics of the plastic material from which those components are formed. The resilience and spring memory characteristics which are inherently built into the test arms eliminate the need for separate springs and complicated assembly. The organization and arrangement of the various elements perform the coin validity testing, anti-rotation and extraction functions with a high degree of accuracy, and result in a high level of precision in the functionality of the coin mechanism. Because of the relatively small number of parts employed in the coin mechanism, and their integral functionality, organization and arrangement, it is a relatively simple and straightforward task to assemble the coin mechanism from its component parts. Many other advantages and improvements will be apparent upon gaining a complete understanding of the present invention. 
   A presently preferred embodiment of the invention and many of its improvements and advantages have been described with a degree of particularity. This description is of a preferred example of the invention, and is not necessarily intended to limit the scope of the invention. The scope of the invention is defined by the following claims.