CROSS-REFERENCE TO RELATED APPLICATIONS 
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   FEDERALLY SPONSORED RESEARCH 
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   SEQUENCE LISTING OR COMPUTER PROGRAM 
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   BACKGROUND OF THE INVENTION 
   (a) Field of Invention 
   The present invention relates to gravity-based sorting mechanisms which separate and route coins, and other disk-shaped objects, using diameter-dependent deflection. 
   (b) Discussion of Prior Art 
   Coin sorting mechanisms which operate by gravity and utilize diameter-dependent deflection are well-documented in U.S. patent literature—many descriptions date back to the late nineteenth century. Today, such gravity-based sorting mechanisms are commonly used in low-speed, cost-sensitive applications: coin validation systems represent one such application. Vending machines, and other coin-operated equipment, employ validation systems to verify the physical characteristics of deposited coins, and gravity-based sorting mechanisms generally provide the diameter-dependent separation and routing needed for this verification process. 
   U.S. Pat. No. 4,263,924 (R. A. Johnson, 1981) describes a gravity-based sorting mechanism designed for validation systems which separate and route multiple coin denominations. This sorting mechanism employs a hollow deflection element that pivots underneath a stationary block. The bottom portion of this stationary block contains a plurality of deflection-edges which are angled in different directions, and each deflection-edge is elevated at a different predetermined height above the floor of the hollow deflection element. Deposited coins of mixed denomination roll edgewise through the hollow deflection element, and coins of the smallest diameter roll underneath the stationary block into a particular routing channel. The deflection-edges of the stationary block selectively engage coins of each larger diameter and force the deflection element to pivot in different directions which guide these coins into their proper routing channel. 
   The sorting mechanism in U.S. Pat. No. 4,263,924 separates and routes a plurality of coin denominations in a very small amount of space, and this space-efficiency helps reduce the overall size of the validation system. Compact validation hardware is very important because the amount of space available inside coin-operated equipment tends to be rather limited. However, this space-efficiency is achieved through the use of a movable deflection element. Coin sorting mechanisms which utilize moving parts are expensive to manufacture and maintain; moving parts tend to wear quickly and must be cleaned and/or replaced on a regular basis to minimize the risk of mechanical failure. In these applications, such maintenance is critically important because mechanical failure can translate into lost revenue. 
   U.S. Pat. No. 5,988,349 (Bruner et al., 1999) describes a coin validation system which separates and routes multiple coin denominations using static deflection elements, and the elimination of moving parts reduces the manufacturing and maintenance costs of the hardware. But, each static deflection element separates and routes coins with respect to only one predetermined diameter at a time; so, multiple deflection elements must be networked together in order to process a plurality of coin denominations, and this tends to increase the overall size and complexity of the validation system. 
   SUMMARY OF THE INVENTION 
   The present invention represents a gravity-based coin sorting mechanism which separates and routes a plurality of coin denominations using a controlled form of diameter-dependent angular deflection. This approach produces a compact sorting device that can be manufactured using cost-efficient methods. Other advantages will become apparent from the information presented in the ensuing description and drawings. 


   
     DESCRIPTION OF DRAWINGS 
       FIG. 1  is a perspective view of the preferred embodiment of the present coin sorting mechanism in which coin separation occurs across a planar deflection-area. 
       FIGS. 2 and 3  are respectively a top plan view and perspective view of the deflection-wall and collimation-wall; these figures show the variation in the width and height of the input channel. 
       FIG. 4  is a perspective view of the lower surfaces of the coin deflector. 
       FIG. 5  is a top plan view of the deflector and mounting-block that illustrates the proper alignment of the deflector with respect to the bottom end of the input channel. 
       FIG. 6  is a side elevation view of the deflector and mounting-block that illustrates the proper alignment of the deflector with respect to the planar deflection-area. 
       FIG. 7  is a top plan view of the deflector and mounting-block that illustrates the proper alignment of the deflector with respect to the various exit channels. 
       FIG. 8  is a top plan view of the coin sorting mechanism that illustrates the movement of coins through the mechanism during normal operation. 
       FIG. 9  is a top plan view of a coin emerging from the deflector in a tilted orientation and rolling edgewise into its respective exit channel. 
       FIGS. 10 ,  11 ,  12  are perspective views of alternative embodiments of the deflector and mounting-block; these figures illustrate three different installation methods for the deflector. 
       FIG. 13  is a perspective view of an alternative embodiment of the present coin sorting mechanism in which coin separation occurs across a cylindrical deflection-area. 
       FIG. 14  is a perspective view of the lower surfaces of the coin deflector shown in  FIG. 13 . 
       FIG. 15  is a side elevation view of the deflector and mounting-block shown in  FIG. 13 ; this figure illustrates the proper alignment of the deflector with respect to the cylindrical deflection-area. 
   


   DETAILED DESCRIPTION OF THE INVENTION 
   (a) Preferred Embodiment 
   FIGS.  1 – 9   
     FIG. 1  shows a perspective view of the preferred embodiment of the present sorting mechanism. Base  40  has an upper surface  42  that is horizontally level in the lateral direction (side-to-side) and inclined longitudinally (top-to-bottom) at a predetermined angle  30  relative to the horizontal plane  20 . The spatial orientation of surface  42  is maintained by a means of support (not shown) attached to base  40 ; this means of support is not part of the present invention. 
   Structural components that extend upward from surface  42  include: coin-chute  50 , deflection-wall  60 , collimation-wall  80 , mounting-block  90 , and routing structures  100 ,  120 ,  140 ,  160 ,  180 . Deflection-area  44  represents a portion of surface  42  which extends away from mounting-block  90  in the lateral direction. Deflector  200  is a removable element, and mounting-block  90  is designed to hold deflector  200  in proper operational alignment with respect to deflection-area  44  and various structural components distributed across surface  42 . In the present embodiment, deflector  200  is installed inside a depression in the upper portion of mounting-block  90  by means of thumbscrew  96  which threads into hole  98 . In general, the specific number of routing structures, and some of the physical features of deflector  200 , depend on the number of coin denominations being sorted. In the form described here, the present sorting mechanism is capable of separating and routing four coin denominations. 
     FIGS. 2 and 3  provide a top plan view and perspective view of coin-chute  50 , deflection-wall  60 , and collimation-wall  80 . In  FIG. 2 , the space between deflection-wall  60  and collimation-wall  80  defines input channel  70 . The width of input channel  70  is nonuniform. The minimum lateral separation between the sidewalls of coin-chute  50  equals the maximum width  74  of input channel  70 . Starting at a small distance downstream from coin-chute  50 , the width of input channel  70  gradually decreases and reaches a minimum value  72  at a small distance upstream from the bottom ends of deflection-wall  60  and collimation-wall  80 . Minimum width  72  has a predetermined value which is slightly greater than the largest coin-thickness in the set of denominations being sorted. Maximum width  74  is approximately twice the predetermined value of minimum width  72 . 
   As shown in  FIG. 3 , the height of input channel  70  is also nonuniform. Starting at the bottom end of coin-chute  50 , input channel  70  has a predetermined minimum height  76  which is less than the smallest coin-diameter in the set of denominations being sorted. The height of input channel  70  increases to a predetermined maximum value  78  at a small distance upstream from the bottom ends of deflection-wall  60  and collimation-wall  80 . Maximum height  78  is slightly greater than the largest coin-diameter in the set of denominations being sorted. The constriction in the width of input channel  70  occurs within the interval where input channel  70  has its minimum height  76 . 
     FIG. 4  shows a perspective view of the lower surfaces of deflector  200 . These lower surfaces include: mounting-surface  210 , undersurfaces  220 ,  230 ,  240 , front mounting-edge  250 , and deflection-edges  260 ,  270 ,  280 . Open-slot  212  facilitates the installation and removal of deflector  200  from mounting-block  90 . Mounting-surface  210  and undersurfaces  220 ,  230 ,  240  are mutually parallel, and these surfaces are perpendicular to mounting-edge  250  and deflection-edges  260 ,  270 ,  280 . Each deflection-edge consists of a circular-section located near the top of deflector  200  and a straight-section located toward the bottom. At the top of deflector  200 , each circular-section curves tangentially away from the plane of front mounting-edge  250  and subtends a different predetermined angle with respect to this plane. 
     FIG. 5  provides a top plan view of deflector  200  installed in mounting-block  90  and includes the bottom portion of input channel  70 ; a side elevation view of deflector  200  installed in mounting-block  90  is shown in  FIG. 6 . In  FIG. 5 , front-surface  92  of mounting-block  90  is laterally aligned with the inner-surface of deflection-wall  60  at the bottom of input channel  70 . Deflector  200  is offset downstream from the bottom end of input channel  70  by a small distance  94 . Distance  94  provides a “turning-clearance” for coins to roll edgewise down and laterally away from the bottom end of input channel  70  without becoming lodged against the inner-surface of collimation-wall  80 . In the proper alignment of deflector  200 , front mounting-edge  250  is laterally aligned with front-surface  92  of mounting-block  90 , and, as shown in  FIG. 6 , deflection-edges  260 ,  270 ,  280  are parallel to deflection-area  44  at predetermined heights  264 ,  274 ,  284 , respectively. 
   The predetermined values of heights  264 ,  274 ,  284  depend on the diameters of the coin denominations being sorted. Height  264  is greater than the smallest diameter, but less than the second-smallest diameter; height  274  is greater than the second-smallest diameter, but less than the second-largest diameter, and height  284  is greater than the second-largest diameter, but less than the largest diameter. As viewed in  FIG. 5 , the straight-sections of deflection-edges  260 ,  270 ,  280  diverge away from the common plane of front-surface  92  and front mounting-edge  250  at predetermined angles  262 ,  272 ,  282 , respectively. The magnitudes of angles  262 ,  272 ,  282  are ordered with respect to the magnitudes of heights  264 ,  274 ,  284 . That is, deflection-edge  260  has the smallest height  264  and the smallest angle  262 ; deflection-edge  270  has intermediate height  274  and intermediate angle  272 , and deflection-edge  280  has the largest height  284  and the largest angle  282 . 
     FIG. 7  shows a top plan view of routing structures  100 ,  120 ,  140 ,  160 ,  180  with deflector  200  installed in mounting-block  90 . The space between each adjacent pair of routing structures  100 ,  120 ,  140 ,  160 ,  180  defines exit channels  110 ,  130 ,  150 ,  170 , respectively. The heights of exit channels  110 ,  130 ,  150 ,  170  are equal to a common predetermined value which is less than the smallest coin-diameter in the set of denominations being sorted. In the proper alignment of deflector  200 , as viewed in  FIG. 7 , vertex  122  of routing structure  120  is displaced slightly down and to the left of the bottom end of deflection-edge  260 . Similarly, vertex  142  of routing structure  140 , and vertex  162  of routing structure  160  are displaced slightly down and to the left of the bottom ends of deflection-edges  270  and  280 , respectively. Surface  124  of routing structure  120  is angled clockwise relative to the longitudinal direction, and surface  126  is angled slightly counterclockwise relative to the straight-section of deflection-edge  260 . Surface  146  of routing structure  140  is angled slightly counterclockwise relative to the straight-section of deflection-edge  270 , and surface  166  of routing structure  160  is angled slightly counterclockwise relative to the straight-section of deflection-edge  280 . 
   In normal operation, as illustrated in the top plan view of  FIG. 8 , coins of mixed denomination enter coin-chute  50  one at a time and roll edgewise down input channel  70  toward deflector  200 . As the coins approach deflector  200 , the increased height and reduced width at the bottom of input channel  70  forces the coins to roll in a vertical orientation, and the reduced width also insures that the coins emerge from input channel  70  in single file. 
   The smallest-sized coins have diameters which are less than height  264 , so these coins roll underneath deflector  200  and are collected into exit channel  110  by surface  124  of routing structure  120 . The diameters of the second smallest-sized coins are greater than height  264 , but less than height  274 . Deflection-edge  260  engages the top portions of these coins and directs their rolling motion toward surface  126  of routing structure  120 ; surface  126  collects these coins into exit channel  130 . The diameters of the second largest-sized coins are greater than height  274 , but less than height  284 . Deflection-edge  270  engages the top portions of these coins and directs their rolling motion toward surface  146  of routing structure  140 ; surface  146  collects these coins into exit channel  150 . The diameters of largest-sized coins are greater than height  284 , so deflection-edge  280  engages the top portion of these coins and directs their rolling motion toward surface  166  of routing structure  160 ; surface  166  collects these coins into exit channel  170 . 
   In some operational environments, coins may not always enter coin-chute  50  one at a time. For example, if the present mechanism is operated manually, coins can be inadvertently dropped into coin-chute  50  too quickly. Coin-chute  50  and the maximum width at the top of input channel  70  are designed to allow two coins in a side-by-side configuration to roll downward, away from coin-chute  50 ; this prevents such coins from becoming lodged within coin-chute  50 —a location which is rather difficult to access. The constriction in the width of input channel  70  arrests such coins at a location where they can be accessed more easily—namely, where input channel  70  has its minimum height. 
   In general, small variations in the spatial orientation of surface  42  do not affect the normal operation of the present mechanism. For instance, a small change in inclination angle  30  of surface  42  just increases or decreases the overall rate at which coins move through the mechanism. If surface  42  is tilted slightly to the left—that is, if the left side of surface  42  is slightly lower than the right side—the vertical orientations of the coins will be biased to the left as they emerge from the bottom of input channel  70 . Since the motions of the three larger-sized coins are controlled by deflection-edges  260 ,  270 ,  280 , the trajectories of these coins toward exit channels  130 ,  150 ,  170  will not change significantly. The motion of the smallest-sized coins will be biased to the left, so these coins will be guided into exit channel  110  by front-surface  92  of mounting-block  90 . If surface  42  is tilted slightly to the right, the motion of the three larger-sized coins will again remain largely unaffected, but the trajectories of the smallest-sized coins will drift to the right. By positioning vertex  122  as far right as possible—namely, just down and to the left of the bottom end of deflection-edge  260 —surface  124  of routing structure  120  can still collect the smallest-sized coins into exit channel  110 . 
   As viewed in  FIGS. 7 and 8 , vertices  122 ,  142 ,  162  are respectively positioned down and to the left of the bottom ends of deflection-edges  260 ,  270 ,  280  in order to accommodate the bottom portions of the three larger-sized coins as they emerge from deflector  200 . During the deflection process, deflection-edges  260 ,  270 ,  280  exert contact forces on the top portions of the three larger-sized coins, so these coins tend to roll toward exit channels  130 ,  150 ,  170  in tilted orientations. For example,  FIG. 9  shows a top plan view of one of the largest-sized coins as it emerges from deflection-edge  280  and rolls toward exit channel  170  in such a tilted orientation. Dashed-line  46  represents the trajectory of the bottom portion of the coin across deflection-area  44 . Toward the end of the deflection process, as viewed in  FIG. 9 , the trajectory of the bottom portion of the coin becomes approximately parallel to deflection-edge  280 , but it is offset slightly down and to the left. Vertex  162  of routing structure  160  is displaced slightly down and to the left of the bottom end of deflection-edge  280  to provide proper clearance for such trajectories. Vertices  122 ,  142  provide the same type of clearance for the other two larger-sized coins. 
   Friction plays an important role during the deflection process because deflection-area  44  must provide sufficient traction to keep the three larger-sized coins from slipping underneath deflector  200 . The maximum amount of friction available from deflection-area  44  can be increased by reducing inclination angle  30  of surface  42 , but this slows down the overall movement of the coins through the mechanism. In order to insure adequate traction for the deflection process without compromising throughput performance, surface  42  can be textured or coated to increase the friction within deflection-area  44 , or base  40  can be fabricated from a material that has a high coefficient of friction. 
   Friction is also an important factor with regard to the design changes needed to sort a different number of coin denominations. The maximum amount of friction available from the deflection-area establishes a maximum angle for reliable coin deflection. So, in general, increasing the number of coin denominations involves using a larger number of deflection-edges with straight-sections that diverge with smaller angular increments. But, in order to accommodate the width of each exit channel, the lateral separation between each deflection-edge at the bottom of the deflector must remain unchanged; so, reducing the angular separation between the straight-sections of adjacent deflection-edges increases the length of the deflector in the longitudinal direction. The width along the bottom edge of the deflector must also be increased to accommodate a larger number of exit channels. Therefore, sorting a larger number of coin denominations generally increases the overall size of the deflector in both the longitudinal and lateral directions. Conversely, sorting a smaller number of coin denominations generally decreases the overall size of the deflector in both the longitudinal and lateral directions. 
   The present mechanism offers considerable flexibility with regard to general construction, and this flexibility can be used to control the amount of friction that exists at different locations. That is, increasing the friction between the coins and the deflection-area improves the reliability of the deflection process, but decreasing the friction between the coins and various surfaces of the structural components improves durability and throughput performance. These design goals can be resolved by fabricating the base and structural components separately out of different materials. The optimization of the reliability and durability of the present mechanism can be particularly important in certain applications. However, in other cases, it may be more cost-effective to fabricate the base and structural components as one integral part—injection-molded, for instance—using a common material. This type of construction would significantly reduce the manufacturing and assembly costs in applications that require large-volume production. The removable deflector can be fabricated out of a durable, low-friction material. 
   (b) Alternative Embodiments 
   FIGS.  10 – 15   
   Different operational environments may require different methods for installing the deflector into the mounting-block. In some applications—due to space limitations, for instance—the deflector may have to be installed in the lateral direction; in other cases, the installation may have to be carried out in the vertical direction. Different methods can be employed to hold the deflector in proper operational alignment without the use of separate fasteners. Some alternative installation methods are illustrated in  FIGS. 10 ,  11 , and  12 . However, in general, many other installation methods are possible. 
     FIG. 10  shows an example of a lateral installation method which utilizes a dovetail-joint formed by horizontal-flanges  312  in mounting-block  310  and beveled-edges  302  in the rear portion of deflector  300 . The proper alignment of deflector  300  is maintained by a flexible clamp  314  which latches into the tapered surface of indentation  304 .  FIG. 11  illustrates a vertical installation method in which deflector  320  is inserted down into a depression in mounting-block  330 ; this depression contains vertical-flanges  332  that form a dovetail-joint with beveled-slots  322  in deflector  320 . Deflector  320  is held against the bottom of the depression by two flexible clamps  334  which independently latch into the tapered surfaces of indentations  324 .  FIG. 12  shows another vertical installation method. In this case, when deflector  340  is inserted down into the depression of mounting-block  350 , pivot-pins  342  in the rear portion of deflector  340  slide into open-slots  352  in mounting-block  350  and create a hinged-joint which enables deflector  340  to be rotated downward against the bottom of the depression. In the same manner as before, the proper alignment of deflector  340  is maintained by two flexible clamps  354  which independently latch into the tapered surfaces of indentations  344 . 
   In the preferred embodiment of the present sorting mechanism, coin separation occurs across a planar surface; however, coin separation can also occur across a curved surface. For example,  FIG. 13  shows a perspective view of an alternative embodiment of the present sorting mechanism which uses a cylindrical deflection-area. 
   In  FIG. 13 , surface  442  of base  440  is planar above and below deflection-area  444 . The planar portion of surface  442  below deflection-area  444  is horizontally level in the lateral and longitudinal directions. The planar portion of surface  442  above deflection-area  444  is horizontally level in the lateral direction, but longitudinally inclined at a predetermined angle  430  relative to the horizontal plane  20 . The middle portion of surface  442  is curved so that deflection-area  444  conforms to the surface of a circular cylinder. Coin-chute  50 , deflection-wall  60 , collimation-wall  80 , and routing structures  100 ,  120 ,  140 ,  160 ,  180  are the same structural components utilized in the preferred embodiment of the present mechanism. In this embodiment, deflector  500  is installed in mounting-block  600  using the method illustrated in FIG.  10 —that is, using a horizontal dovetail-joint, secured by flexible clamp  604 . 
     FIG. 14  shows a perspective view of the lower surfaces of deflector  500 . Mounting-surface  510  and undersurfaces  520 ,  530 ,  540  are curved to accommodate the cylindrical shape of deflection-area  444 ; that is, these surfaces are curved to form surface elements of circular cylinders. Mounting-surface  510  and undersurfaces  520 ,  530 ,  540  are concentrically aligned along a common central axis and have different predetermined radii with respect to this common axis; these surfaces are perpendicular to front mounting-edge  550  and deflection-edges  560 ,  570 ,  580 . Each deflection-edge curves tangentially away from the plane of mounting-edge  550 , then extends away from this plane in the form of a helix. As described earlier, vertices  122 ,  142 ,  162  of routing structures  120 ,  140 ,  160  must be properly positioned with respect to the bottom ends of the deflection-edges; in the present embodiment, this positioning is established by the helical pitch of each deflection-edge. 
     FIG. 15  shows a side elevation view of deflector  500  installed in mounting-block  600 . In the proper alignment of deflector  500 , front mounting-edge  550  and front-surface  602  of mounting-block  600  are laterally aligned with the inner-surface of deflection-wall  60  at the bottom of input channel  70  ( FIG. 5 ), and the common central axis of mounting-surface  510  and undersurfaces  520 ,  530 ,  540  coincides with the central axis of deflection-area  444 . The radii of undersurfaces  520 ,  530 ,  540  are designed so that deflection-edges  560 ,  570 ,  580  are radially equidistant from deflection-area  444  at predetermined distances  564 ,  574 ,  584 , respectively. The predetermined values of distances  564 ,  574 ,  584 , are respectively equivalent to the predetermined values of heights  264 ,  274 ,  284 , shown in  FIG. 6 . 
   In this embodiment, the sorting mechanism operates in the same manner described previously ( FIG. 8 ). Coins of mixed denomination enter coin-chute  50  one at a time and roll edgewise toward deflector  500  in single file. The coins of the smallest diameter roll underneath deflector  500  into exit channel  110 . Coins of each larger diameter are selectively engaged by one of the deflection-edges  560 ,  570 ,  580  and directed across deflection-area  444  into exit channels  130 ,  150 ,  170 , respectively.
In the present sorting mechanism, coins of mixed denomination roll edgewise down an inclined channel toward a static coin deflector that contains a plurality of deflection-edges. These deflection-edges are distinctly curved and elevated at different predetermined distances above an extended surface. Coins of the smallest diameter roll underneath the deflector into a particular routing channel; coins of each larger diameter are selectively engaged by one of the deflection-edges and directed across this extended surface into their proper routing channel. The present mechanism implements a controlled form of diameter-dependent angular deflection which separates and routes a plurality of coin denominations in a space-efficient manner.