Abstract:
An assembly technique has been developed which reliably inserts the outer disk of an exposed film indicator into the crimp diameter of the cartridge end cap. This process gimbals the fixture containing the film cartridge, and rocks it in a manner that creates a circular wobble motion.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to the field of manufacturing, and in particular to parts manufacturing and assembly. 
     BACKGROUND OF THE INVENTION 
     What is needed in the art is a film cartridge which will indicate whether the film in the cartridge has been exposed. 
     Recently there has been a desire by snap-shooters, photo enthusiasts, and professionals to be able to determine if a roll of film has been advanced through a camera or has never been used. This can be accomplished by attaching an exposed film indicator to the long end of the spool on a 35 mm cartridge. This is primarily needed when shooting multiple rolls of film, or for the purpose of some consumer and professional cameras, when a roll is only partially exposed to be used again later. 
     One problem involving assembling the exposed film indicator to the cartridge, is developing a method to reliably attach two thin disks to the long hub end of the spool. The inner (or exposed) disk is attached to the spool hub by three barbs and therefore rotates with the spool. The word EXPOSED may be printed on it, or to differentiate from the outer disk, it may be a different color. The outer (or unexposed) disk is attached to the crimp diameter of the end cap. It remains stationary relative to the cartridge. The word UNEXPOSED may be printed on it, or, again to differentiate from the inner disk, it may be a different color. When a customer purchases a fresh roll of film, the outer disk on the exposed film indicator will be visible. As film is wound back into the cartridge after the pictures are taken, a tab that sticks up on the inner disk engages a tab that sticks down on the outer disk. The inner disk then exits through a slot in the outer disk and is visible to the customer. 
     U.S. Pat. No. 5,708,879 shows a film cartridge with a visual exposure status indicator. 
     U.S. Pat. No. 5,715,494 is another example of a film cartridge with a visual exposure status indicator. 
     To implement adding exposure indication to a 35 mm film cartridge in a timely and cost effective manner, it is necessary to minimize the impact on the existing manufacturing infrastructure. Given the complexity of this infrastructure and the space constraints around the equipment, it is highly desirable to add the feature after the film cartridge is completely assembled. Since the completed film cartridge is loaded into the canister at the end of the film winding operation, the feature must be assembled to the cartridge either by removing the cartridge from the canister or while the cartridge is in the canister. It is advantageous to assemble the feature to the film cartridge while it is in the canister since: 
     1) The canister provides a convenient method of conveying and singulating the film cartridges for the assembly operations. 
     2) It is difficult to reinsert the film cartridge back into the canister without using a special motion to wrap the film leader around the cartridge. 
     3) Reduced handling of the cartridges and thus the potential for cosmetic damage to either the cartridge or the film leader is reduced. 
     4) Equipment space limitations does not permit cartridge removal. 
     SUMMARY OF THE INVENTION 
     The above problem of applying an exposed film indicator to the cartridge after assembly of the cartridge is solved by applying the gimbaled roller process described herein. 
     The invention provides a means of reliably inserting the outer disk of the exposed film indicator into the crimp diameter of the cartridge end cap on the long hub end of the spool. 
     The assembly process will accept the canned cartridges opened end up, either from a tray unloader or from a centrifugal feeder. Individual canisters will be singulated on the infeed conveyor, using a separator screw. They will then be loaded onto either a continuous motion rotary assembly turret, a dial indexer or some type of assembly chassis. Using this motion generated by the chassis and the gimbaled roller tooling, this process can be used to find the center of the spool and assemble the outer disk of the exposed film indicator to the cartridge by pressing the outer disk into the crimp diameter of the cartridge end cap. 
     Significant interference is required between the outside diameter on the outer disk and the end cap crimp diameter to provide sufficient torsional retention. Because of this diametrical interference, straightline insertion may not be sufficiently reliable. A process has been developed to rock the fixture containing the film canister and cartridge. This motion can take the form of either a pivot about a shaft or a circular “wobble”. The net result of the motion is to present the crimp diameter of the end cap to the outside diameter of the outer disk in a manner that only a few of the engagement tabs on the outer disk are inserted into the crimp diameter at any point in time. 
     It is noted that if desired, the functionality of the exposed film indicator can be reversed by having the inner disk designated as unexposed and the outer disk designated as exposed and assembled to the cartridge in reverse order. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objectives, features, and advantages of the invention will be apparent from the following more particular description, including the presently preferred embodiments of the invention, as illustrated in the accompanying drawings in which: 
     FIG. 1 shows the general assembly of the gimbaled assembly mechanism. 
     FIG. 2 is an exploded view of the product, typically a 35 mm film cartridge and a canister. 
     FIG. 3 is an enlarged view of the tooling head. 
     FIG. 4 is an enlarged view of the nest and cam subassemblies. 
     FIGS. 5 through 14 show the sequential positions of the tooling required to assemble the disk to the end of the cartridge. 
     FIG. 15 shows the gimbaled assembly mechanism returned to the home position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows the general assembly of a mechanism designed to assemble a thin flexible disk to the end of a cartridge such as a 35 mm film cartridge that is already in a plastic canister. The major components of the assembly consists of a tooling head sub-assembly  1 , a nest sub-assembly  2  and a cam actuator sub-assembly  4 . The tooling head  1  is driven up and down vertically by a lead screw assembly  3 . 
     FIG. 2 is an enlarged view of the product  10 , which consists of a plastic canister  11  and a 35 mm cartridge  12 . The cartridge  12  is made up of a spool  13 , preferably made of plastic, a steel shell or magazine  15 , and two steel end caps  14 , which are staked onto the ends of the magazine . Protruding out of the cartridge (preferably approximately 58 mm) is the film leader  16 . The film leader  16  tends to act as a leaf spring and pushes the cartridge  12  up against the inside wall of the canister  11  on the side opposite from where the film exits the cartridge  12 . This phenomenon helps hold the cartridge  12  in one place relative to the inside of the canister  11 . Note that the cartridge  12  is free to move anywhere within the confines of the canister  11 . 
     FIG. 3 is an enlarged view of the tooling head which provides a means to hold the outer disk in place during the assembly operations, and provides a means to properly locate the outer disk on center until it is assembled to the cartridge  12 . The tooling head consists of a centering shaft  21 , and a vacuum or tooling head  22 , that holds the outer exposed film indicator disk in place at the tip. The tooling head  22  is attached through a coupling or piston  23  to an air spring  24 . The air spring is supplied with an adjustable air pressure through the inlet port  25 . The centering shaft  21  moves vertically, and independently relative to the tooling head  22 . The movement of the centering shaft  21  is controlled by an air cylinder  26  and is supported by two bearings  27 , which are pressed into the piston  23  and the tooling head  22 . 
     FIG. 4 is an enlarged view of the nest sub-assembly  2  whose function is to support the product assembly  10 , consisting of the canister  11  with the cartridge  12  inside during the assembly operation. The nest sub-assembly  2  which contains a nest  28 , and a cam  29 , is captured in a spherical bearing seat  30  that will allow it to rock back and forth in an orbital motion. The nest sub-assembly  2  is driven up and down vertically by an air cylinder  31  attached to a slide  32  and the nest support bracket  38 . When the nest sub-assembly  2  is lowered, the cam plate  29  presses against the cam followers  33 , causing the nest assembly to tip. The cam followers  33  are mounted on a spindle  34  which rotates by energizing a motor  35  that is attached to the spindle  34  through a belt and pulley assembly  36 . The spindle  34  is mounted in a bearing block  37 . 
     FIGS. 5 through 15 are enlarged views of the sequential steps required to assemble the outer exposed film indicator disk to the end of the cartridge. FIG. 5 shows the tooling head  22  in the load position. In all the following figures, the tooling head is raised or lowered as required, by the lead screw  3  shown in FIG.  1 . The nest  28 , with the cam plate  29 , is also raised up off the cam followers  33 , and is therefore in a vertical position. The outer disk  17  is placed on the tooling head  22  over the centering shaft  21  and held by vacuum. Vacuum is supplied at port  39 , and then internally ported through the tooling head in order to hold the outer disk  17  onto the bottom of the head. The canister  11 , with a cartridge  12  inside, is placed in the nest  28 . 
     FIG. 6 shows the tooling head  22  after it has been lowered to a position where the centering shaft  21  has just entered the end of the spool  13 , and has captured it within the confines of the inside diameter of the spool. 
     The tooling head  22 , along with the centering shaft  21 , will continue to lower slowly until it reaches the position shown in FIG.  7 . Because the tip of the centering shaft  21  is a cone, it acts as a wedge and pushes the edge of the spool  13  away from the wedge or centering shaft  21 . Since the spool  13  is captured inside the cartridge assembly  12 , the cartridge will move with the spool  13 . The cartridge  12  in turn, is inside the canister  11  and coupled to the canister through the leader  16 . Therefore, the canister  11 , will also attempt to move with the spool  13 . In other words, the entire product assembly  10  moves as the wedge or centering shaft  21  pushes it. Since the wedge is a conical surface, as it pushes itself away from one side, it gets closer to the other side of the inside of the spool  13 . As the tooling head  22  and centering shaft  21  continue to lower, the clearance between the inside diameter of the spool  13  and the conical tip of the centering shaft  21  decreases, until eventually the tip is seated firmly into the spool  13 . At this point, the cartridge  12  is centered relative to centering shaft  21 . It is preferred that the bottom of the nest  28  is smooth, so that as the wedge or centering shaft  21  attempts to move the product, the frictional force developed between the bottom of the canister  11  and the nest  28 , is less than the force developed by the wedge. If the frictional force is too large, the product  10  will not move, hence, the product  10  will not center itself and/or the tip of the spool  13  will be damaged. If however, the canister  11 , were prevented from moving further, (as a result for example, of pressing against the edge of the nest or excessive friction between the canister  11  and the nest  28 ) the cartridge would still continue to move towards center because the film leader  16 , which couples the cartridge  12  to the canister  11  is a compliant member and therefore would collapse as needed. 
     In FIG. 8, the tooling head  22  has lowered slightly so that the tip of the vacuum or tooling head  22  has now also captured the spool  13 , thus preventing it from losing its center orientation relative to the tooling head  22 . The centering shaft  21  remains in the same vertical position as it was in FIG. 7, still holding the spool  13 , and the product assembly on center with the tooling head  22 . Therefore the tooling head must have the ability to move independently relative to the centering shaft. 
     In FIG. 9 the centering shaft  21  has retracted approximately ½ inch. The spool  13  however, is still constrained by the tooling head  22 , but does have the freedom to translate by an amount equal to the clearance between the inside diameter of the tooling head  22  and the outside diameter of the spool  13 . 
     FIG. 10 shows the nest assembly which contains the nest  28 , spherical bearing seat  30 , nest support bracket  38 , roller slide  32 , and an air cylinder  31 . The nest  28  is lowered, preferably ¼ inch, by the air cylinder  31 . When it is lowered, the cam  29  attached to the bottom of the nest  28 , is forced up against the cam followers  33 . Because the cam followers  33  are at a different height (as shown) the nest assembly  2  will tilt to the side. At the same time that the air cylinder  31  begins to lower the nest assembly  2 , the tooling head  22  also lowers the same distance and at the same rate, maintaining the same relationship between the product assembly  10  and the tooling head  22 , thus keeping the spool  13  constrained. As the air cylinder  31  begins to lower the nest assembly, as shown in FIG. 4, the motor  35  begins to turn. Coupled to the motor through a pulley assembly  36  is a spindle  34 , which is attached to the cam follower assembly  33 . Referring back again to FIG. 10, the spindle  34  with the cam follower  33  attached begins to rotate. The cam  29 , which simultaneously was lowered, approaches the cam follower  33 . Since the two cam followers  33  are each at different heights, the cam  29  will first touch one of the followers, and since the cam follower is offset from the centerline of the cam  29  and nest  28 , the nest will attempt to tilt. Because the nest is contained by a spherical bearing seat  30 , there is nothing to prevent the nest  28  from tilting. As the air cylinder  31  continues to press the nest  28  lower, the nest will tilt until it touches both followers  33 , as shown. At that point the nest  28  is tilted to its maximum angle allowed based on the difference in height of the cam followers  33 . This angle can be varied by adjusting the difference in height. FIG. 11 is an enlarged view of FIG.  10 . 
     In FIG. 12, the tooling head  22 , has been lowered further so that the outer exposed film indicator disk  17  is now inside of the end cap  14 , but only on one side. The vacuum, supplied from port  39  to hold the outer disk  17  onto the tooling head is released, so the outer exposed film indicator disk  17  is now free to move. However, it is trapped by the spool and can not fall off. By only inserting one side or point at a time, there is room for the outer disk  17  to move away from the interference towards the opposite side of the cartridge. This phenomenon allows this assembly technique to work. By allowing the outer disk  17  on the exposed film indicator to float away from the point of interference, the amount of force required to insert the outer disk decreases at this point, since the assembly process is not attempting to force all of the teeth on the outer disk  17  to pass through the smaller diameter of the end cap  14  simultaneously. Instead only a couple teeth are assembled together at the same instant. As the cam follower  33  driven by the motor  35 , and the pulley assembly  36  rotates, the point of assembly interference moves around the perimeter of the end cap  14 . FIG. 13 is the same as FIG. 12 except the cam follower  33 , and in turn the nest sub-assembly  2 , are shown rotated 180° from the initial position, hence the nest sub-assembly is shown tipped in the opposite direction. The cam follower  33  will continue to rotate a minimum of one full revolution. The point of assembly interference will coincide with the point of the higher of the two cam followers  33 . As the cam follower  33  rotates, the nest  22  will also continue its gimbal or wobble motion. As each point of the tooling head presses into the end cap  14 , the outer exposed film indicator disk  17  is forced or squeezed into the crimp diameter of the end cap. 
     As shown in FIG. 14, after the cam follower  33  has made a minimum one complete revolution, and hence the nest sub-assembly  2  has completed its wobble motion, the tooling head  22  is raised back up by actuating the lead screw, and the centering shaft  21  is also extended back to its original position. The outer exposed film indicator disk  17  is now securely assembled to the end cap  14  of the cartridge  12 . 
     FIG. 15 shows all of the tooling subassemblies back at their original positions. The air cylinder  31  has been raised back up to its original position, disengaging the cam follower  33  from the cam plate  29 , and allowing the entire nest sub-assembly  2  to straighten itself, by again pivoting in the spherical bearing seat  30 . The motor (not shown) turning the cam follower  33  will also stop rotating. Once all of the subassemblies stop moving, the product assembly  10  (with the outer disk  17  attached) can be removed from the nest  28 . The entire assembly sequence can now be repeated. 
     The many features and advantages of the invention are apparent from the detailed specification and thus it is intended by the appended claims to cover all such features and advantages which fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 
     PARTS LIST 
       1 . Tooling Head Sub-Assembly 
       2 . Nest Sub-Assembly 
       3 . Lead Screw Sub-Assembly 
       4 . Cam Actuator Sub-Assembly 
       10 . 35 mm Cartridge Product Assembly 
       11 . Canister 
       12 . Cartridge 
       13 . Spool 
       14 . End Caps (2) 
       15 . Magazine 
       16 . Leader 
       17 . Outer Exposed Film Indicator Disk 
       21 . Centering Shaft 
       22 . Vacuum or Tooling Head 
       23 . Piston 
       24 . Air Spring 
       25 . Air Spring Pressure Inlet Port 
       26 . Centering Shaft Air Cylinder 
       27 . Bearings (2) 
       28 . Nest 
       29 . Cam 
       30 . Spherical Bearing Seat 
       31 . Nest Air Cylinder 
       32 . Slide 
       33 . Cam Followers 
       34 . Spindle 
       35 . Motor 
       36 . Pulley Assembly 
       37 . Bearing Block 
       38 . Nest Support Bracket 
       39 . Vacuum Head Inlet Port