An implanter comprising a housing, a hollow needle connected to the housing, a drive pin positioned within the housing and aligned with the hollow needle, and a trigger assembly operably connected to both the housing and the drive pin. The drive pin has a distal end, and further has a retracted position wherein the distal end of the drive pin is in the housing and an extended position wherein the distal end of the drive pin portion extends out of the housing. A pellet is positioned between the needle and the distal end of the drive pin when the drive pin is in the retracted position. The drive pin expels the pellet through the hollow needle when moving from the retracted position to the extended position. The trigger assembly includes a trigger that has a relaxed position and an actuated position. The drive pin moves from the retracted position to the extended position when the trigger moves from the relaxed position to the actuated position. The invention further relates to a method for implanting an object beneath a membrane, comprising the steps of: positioning an object to be implanted between a drive pin and a hollow needle; positioning a plug between the object and the drive pin; inserting the needle through the membrane; and moving the drive pin from a retracted position to an extended position to expel the object through the hollow needle and stop the needle with the plug.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates, generally, to apparatus and methods for
 implanting objects beneath membranes. More particularly, the invention
 relates to implanters for depositing electronic tracing devices, hormone
 pellets or other objects or pellets beneath a membrane.
 2. Background Information
 The state of the art in general includes various devices and methods for
 implanting objects beneath a membrane using a device that has a rod which
 travels through a hollow needle to deposit the object through the needle
 and beneath the punctured membrane. For example, the objects or pellets
 may comprise electronic tracing devices or transponders which are used to
 tag an animal, or the pellets may comprise hormone pellets which are used
 in the domestic livestock fattening industry to promote growth of the
 animal. The pellets are often injected into the ears of the animals to
 prevent the pellets from entering food products for human or animal
 consumption as the ears are commonly discarded in slaughtering. Typically,
 the ear is grabbed with one hand while the other hand operates the
 implanter. The pellets should be carefully, properly and accurately
 implanted to reduce the probability for infection and increase the
 effectiveness of the deposited pellets. Further, because of the movements
 of the animals, it is desirable for the pellets to be quickly implanted
 into the animal.
 These devices and methods are believed to have significant limitations and
 shortcomings. One of the shortcomings is that implanter devices may spread
 blood-borne diseases among the animals if the needle is not replaced for
 each animal. In recognition of this problem, Turley (U.S. Pat. No.
 5,279,554) disclosed a device that uses a shroud or covering that moves
 and locks in an extended position to partially cover the needle, and thus
 encourages a user to replace the needle after each use. Another
 shortcoming of the known art is the inability to automatically, quickly,
 consistently and powerfully implant multiple pellets. Turley (U.S. Pat.
 No. 4,154,239) disclosed that the link between the drive pin and the
 trigger actuator in the known art devices tended to buckle, and further
 disclosed that the speed or velocity of the drive pin was limited because
 the known art devices employed a 1:1 ratio between the drive pin and the
 trigger/actuator. In recognition of these problems, Turley ('231)
 disclosed a device that uses a flexible belt or link to achieve a velocity
 ratio other than 1:1. Other devices have achieved a velocity ratio other
 than 1:1 by attaching spur gears to the trigger and a rack gear to the
 drive pin.
 Applicants' invention provide an implanter apparatus which is believed to
 constitute an improvement over existing technology.
 BRIEF SUMMARY OF THE INVENTION
 The present invention provides an implanter which generally comprises a
 housing or housing assembly, a hollow needle connected to the housing
 assembly through a quick attachment mechanism, a drive pin positioned
 within the housing assembly and aligned with the hollow needle, and a
 trigger assembly operably connected to both the housing assembly and the
 drive pin. The drive pin has a distal end, and further has a retracted
 position in which the distal end of the drive pin is in the housing
 assembly and an extended position in which the distal end of the drive pin
 extends out of the housing assembly. A pellet is positioned between the
 needle and the distal end of the drive pin when the drive pin is in the
 retracted position. The drive pin expels the pellet through the hollow
 needle as it moves from the retracted position to the extended position.
 The trigger assembly includes a trigger that has a relaxed position and an
 actuated position. The drive pin moves from the retracted position to the
 extended position to expel the pellet when the trigger moves from the
 relaxed position to the actuated position. The trigger assembly is adapted
 to provide a mechanical advantage for increasing the velocity of the drive
 pin with respect to the velocity of the trigger. The trigger assembly
 includes a trigger lever having a fulcrum point, a trigger end operably
 contacting the trigger, and a shuttle end operably connected to a drive
 pin shuttle that slides along at least one shuttle guide groove to move
 the drive pin between the retracted position and the extended position.
 The fulcrum point is preferably closer to the trigger end than to the
 shuttle end to provide the mechanical advantage for increasing the
 velocity ratio between the drive pin and the trigger assembly.
 The housing assembly includes a magazine housing attached to a body
 housing. The magazine housing has a magazine passage sized to receive a
 pellet magazine and contains a magazine advancement mechanism. The
 magazine advancement mechanism indexes the pellet magazine through a
 number of predetermined index positions within the magazine passage. The
 drive pin is adapted to extend through the pellet magazine, i.e. one of
 the plurality of tubes, and into the hollow needle at each one of the
 predetermined index positions. The magazine advancement mechanism
 preferably has an opening or window for viewing the index positions of the
 pellet magazine. The magazine advancement mechanism has at least one fixed
 clip for engaging one side of the pellet magazine, at least one movable
 clip for engaging the other side of the pellet magazine, and an index
 actuator for indexing the at least one movable clip within the magazine
 passage. The clips are adapted to prevent the pellet magazine from moving
 in a first direction within the magazine passage and to allow the pellet
 magazine to move in a second direction upon the application of an index
 force, which moves the movable clip in an index motion. The movable clip
 has a bias spring to move the movable clip from one groove, over a ridge,
 and to an adjacent groove upon release of an index force.
 In a manual index actuator embodiment, the index force is manually applied
 to the index actuator to index the movable clip within the magazine
 passage. A bias spring provides the return motion. In an automatic index
 actuator embodiment, the index force is generated by an actuation force
 applied to the trigger. The automatic index actuator includes a cam lever
 pivotally attached at a fulcrum point to the housing assembly. The cam
 lever has a cam end in operable contact with a cam follower mounted on the
 drive pin shuttle. The cam lever further has a magazine advancement
 mechanism end in operable contact with the at least one movable clip. The
 magazine advancement end has an index motion and a return motion. The cam
 lever pivots and moves the magazine advancement end in an index motion to
 index the pellet magazine when the cam follower moves with the drive pin
 into the retracted position, and the cam lever pivots and moves the
 magazine advancement end in a return motion as the cam follower moves with
 the drive pin from the retracted position toward the extended position. A
 latch mechanism prevents the magazine advancement end from undergoing an
 index motion until the drive pin is fully retracted out of the magazine.
 Each one of the tubes in the pellet magazine may include both a pellet and
 a plug. The pellet is positioned in front of the plug. When the drive pin
 extends, the pellet is expelled from the needle and the plug remains in
 the needle to discourage the use of the needle in another animal. The
 quick attachment mechanism allows the needle to be quickly replaced.
 Preferably, the quick attachment mechanism includes a threaded collect.
 The hollow needle extends through the threaded collect, and a threaded nut
 screws around the collect to quickly attach and detach the hollow needle
 from the housing assembly. The collect preferably has two or more
 circumferencially spaced slots that enable the collet to securely tighten
 around a range of needle diameters.

DETAILED DESCRIPTION
 FIGS. 1-16 illustrate preferred embodiments of the present invention, which
 is generally indicated by the reference numeral 10. The implanter 10 is
 described below first in terms of its major structural elements and then
 in terms of its secondary structural and/or functional elements which
 cooperate to implant an object beneath a membrane, i.e. to inject a
 transponder or hormone into an animal or to deposit a reactant through a
 stretched covering into a reaction vessel, among others.
 Referring to FIGS. 1, 3, 5, 7 and 8, the implanter 10 generally comprises a
 housing assembly 12, a hollow needle 14 connected to the housing assembly
 12, a drive pin assembly 16 including a drive pin 18 positioned within the
 housing assembly 12 and aligned with the hollow needle 14, and a trigger
 assembly 20 operably connected to both the housing assembly 12 and the
 drive pin 18. The drive pin 18 has a distal end 22, and further has a
 retracted position in which the distal end 22 of the drive pin 18 is in
 the housing assembly 12 and an extended position in which the distal end
 22 of the drive pin 18 extends out of the housing assembly 12 and through
 the hollow needle 14.
 Referring to FIGS. 3 and 5 in particular, a pellet 24 is positioned,
 preferably using a pellet magazine 26, between the needle 14 and the
 distal end 22 of the drive pin 18 when the drive pin 18 is in the
 retracted position. The drive pin 18 expels the pellet 24 through the
 hollow needle 14 as it moves from the retracted position to the extended
 position. The trigger assembly 20 includes a trigger 28 that has a relaxed
 position shown in FIG. 7, and an actuated position shown in FIG. 8. The
 drive pin 18 moves from the retracted position to the extended position as
 the trigger 28 moves from the relaxed position to the actuated position.
 The trigger assembly 20 is adapted to provide a mechanical advantage for
 increasing a drive pin velocity with respect to a trigger velocity, which
 provides the implanter 10 with the capability of quickly depositing an
 object or pellet 24. The embodiments illustrated in the figures
 incorporate a first class lever as a trigger lever 30 to provide the
 mechanical advantage that increases the drive pin velocity.
 The pellet magazine 26 has a plurality of tubes 32 for holding and
 retaining pellets 24. The housing assembly 12 includes a magazine passage
 34 sized to receive the pellet magazine 26 and contains a magazine
 advancement mechanism 36 for indexing the pellet magazine 26 through a
 number of predetermined index positions within the magazine passage 34.
 The drive pin 18 is adapted to extend through the pellet magazine 26 and
 into the hollow needle 14 when the pellet magazine 26 is at each one of
 the predetermined index positions. A pellet 24 may be loaded in front of a
 plug 38 in each one of the tubes 32 in the pellet magazine 26. The pellet
 24 is positioned and adapted to be expelled from the needle 14, and the
 plug 38 has a shape and size to remain in the needle 14 when the drive pin
 18 is extended. By remaining in the needle 14, the plug 38 discourages,
 and effectively prevents, the hollow needle 14 from being used again in
 another animal. The plug 38 may be formed from a variety of materials. In
 the embodiment shown in the figures, the plug 38 is a plastic object
 having a generally cylindrical shape. The plug 38 has a circumferencial
 rib 39 that causes the plug 38 to be stuck in the needle 14.
 The elements of the implanter 10 are hereafter described in more detail.
 Many of these elements or components are constructed from molded plastic
 in order to provide an economical implanter 10 that is light and durable.
 Referring again to FIG. 1, the housing assembly 12 generally includes a
 body housing 40 attached to a magazine housing 42. In the embodiments
 shown, the body housing 40 is formed by fastening a first side 40a to a
 second side 40b, and the magazine housing 42 is formed by fastening
 together a first side 42a to a second side 42b. The body housing 40 is
 shaped generally like a pistol, which provides a user the ability to
 operate the device and accurately deposit the pellet with one hand. The
 body housing 40 comprises a hand grip portion 44 and a drive pin portion
 46. The trigger assembly 20, and in particular the trigger 28, is
 positioned adjacent to the hand grip portion 44. Referring to FIGS. 7 and
 8, the drive pin portion 46 is formed to include a drive pin passage 48
 and a shuttle guide, which is formed by shuttle guide grooves 50 in the
 first and second sides 40a and 40b of the body portion 40. A drive pin
 shuttle 90 is connected to the proximal end of the drive pin 18, and
 slides along the shuttle guide. The shuttle guide and the drive pin
 passage 48 cooperate to accurately extend the drive pin 18 through the
 pellet magazine 26 and the hollow needle 14.
 The first and second sides 42a and 42b of the magazine housing 42 form the
 magazine passage 34, which is sized and configured to receive the pellet
 magazine 26 shown in FIG. 4. The pellet magazine 26 comprises a plurality
 of adjacent tubes 32 formed together as a unitary body. The longitudinal
 axes of these tubes are parallel to each other and are generally aligned
 in the same plane. The pellet magazine 26 has two exterior sides 52a and
 52b, each of which have a set of parallel ridges 54 and corresponding
 grooves. The pellet magazine 26 further has a proximal end 56 and a distal
 end 58. An alignment flange 60, having a generally rectangular plate-like
 shape, is formed at the proximal end 56 and serves as a means for properly
 aligning and orientating the pellet magazine 26 in the magazine passage
 34. A lip having circumferencial cuts is formed around the circumference
 of each tube 32 at the distal end 58. The lip prevents the pellets 24 from
 falling out of the pellet magazine 26, but allows the drive pin 18 to
 easily force a pellet 24 through the lip. As illustrated in FIG. 13, the
 alignment flange 60 of the pellet magazine 26 corresponds to alignment
 grooves 62 formed in each side of the magazine housing 42 and causes the
 pellet magazine 26 to fit within the magazine passage 34 only in the
 predetermined manner.
 A quick attachment mechanism 64 for a needle 14 is mounted on the distal
 side of the magazine housing 42. As illustrated in FIGS. 1 and 6, the
 quick attachment mechanism 64 preferably includes a threaded collet 66 or
 slotted sleeve. The hollow needle 14 extends through the threaded collet
 66, and a threaded nut 68 screws around the collet 66 to quickly attach
 and detach the hollow needle 14 from the housing assembly 12. The collet
 66 preferably has two or more circumferencially spaced slots 70 that
 enable the collet 66 to securely tighten around a large range of needle
 diameters. The collet 66 shown in the figures, for example, has six
 circumferencially spaced slots 70. The collet 66 is mounted to the
 magazine housing 42 by sandwiching the housing wall between two nuts.
 The magazine housing 42 contains the magazine advancement mechanism 36 for
 indexing the pellet magazine 26. The magazine advancement mechanism 36
 includes: at least one and preferably two fixed clips 72 for engaging one
 side of the pellet magazine; at least one and preferably one movable clip
 74 for engaging the other side of the pellet magazine; and an index
 actuator 76 for indexing the movable clip 74 within the magazine passage
 34. The clips 72 and 74 are attached to the magazine housing 42 within the
 magazine passage 34. As illustrated in FIG. 10, the clips 72 and 74 are
 adapted to prevent the pellet magazine 26 from moving in a first direction
 and to allow the pellet magazine 26 to move in a second direction upon the
 application of an index force by securely engaging the ridges 54 in the
 side walls of the pellet magazine 26. The movable clip 74 has a bias
 spring 78 and a latch spring 80 to move the movable clip 74 from one
 groove over a ridge 54 to another adjacent groove upon release of the
 index force.
 In manual index actuator embodiment 76a illustrated in FIGS. 1, 2, 6, and
 9, the index force is manually applied to the index actuator 76 to index
 the movable clip 74 within the magazine passage 34. The bias spring 78
 provides the return motion. In an automatic index actuator embodiment 76b
 illustrated in FIGS. 11-15, the index force is generated by an actuation
 force applied to the trigger 28. The automatic index actuator 76b includes
 a cam lever 82 pivotally attached at a fulcrum point 84 to the body
 housing 40b. The cam lever 82 has a cam end 86 in operable contact with a
 cam follower 88 mounted on a drive pin shuttle 90, which is attached to
 the drive pin 18. The cam lever 82 further has a magazine index end 92 in
 operable contact with the movable clip 74. The magazine index end 92 has
 an index motion and a return motion. As illustrated in FIGS. 12 and 15,
 the cam lever 82 pivots and moves the magazine index end 92 in a return
 motion as the cam follower 88 moves with the drive pin 18 from the
 retracted position toward the extended position. As illustrated in FIGS.
 14 and 16, the cam lever 82 pivots and moves the magazine index end 92 in
 an index motion when the cam follower 88 moves with the drive pin shuttle
 90 and drive pin 18 into the retracted position. A latch mechanism 94,
 comprising a latch member 96 pivotally mounted to the body housing 40 and
 a latch spring 98 for biasing the latch member 96 in a latch position,
 prevents the magazine index end 92 from undergoing an index motion until
 the drive pin shuttle 90 contacts the latch member 96, presses against the
 latch spring 98, and pushes the latch member 96 to a release position. The
 drive pin 18 is fully retracted out of the magazine 26 when the drive pin
 shuttle 90 contacts the latch member 96. The latch member 96 releases a
 pair of bias springs 78, shown in FIG. 16, which provide an index force to
 index the pellet magazine 26. The drive pin 18 is securely attached to the
 drive pin shuttle 90, and together form the drive pin assembly 16 that
 cooperates with the drive pin passage 48 and shuttle guide in the body
 housing 40 to consistently and accurately extend and retract the drive pin
 18 along a line extending through the pellet magazine tubes 32, the collet
 66, and the hollow needle 14. The index position of the pellet magazine 26
 is seen through an opening or window 100 in the magazine housing 42.
 The trigger assembly 20 is adapted to provide a mechanical advantage for
 increasing a drive pin velocity with respect to a trigger velocity, and
 thus allow the implanter 10 to quickly deposit the pellet. The embodiments
 illustrated in FIGS. 7, 8, 12 and 14 incorporate a first class lever 30,
 wherein the effort or actuation force is applied at the trigger 28 and the
 load is applied at the drive pin shuttle 90, to provide the mechanical
 advantage to increase the drive pin velocity. The trigger assembly 20
 includes the trigger lever 30 which has a fulcrum point 102, a trigger end
 104 operably contacting or connected to the trigger 28, and a shuttle end
 106 operably connected, through a trigger linkage 118, to the drive pin
 shuttle 90 that slides along the shuttle guide grooves 50 to move the
 drive pin 18 between the retracted position and the extended position. The
 fulcrum point 102 is preferably closer to the trigger end 104 than to the
 shuttle end 106 to provide the mechanical advantage to increase the
 velocity ratio between the drive pin 18 and the trigger 28. A cam follower
 108 is connected at the trigger end 104 of the trigger lever 30 and a cam
 surface 110 is formed in the interior of the trigger 28. The trigger 28 is
 attached to the body housing 40 at a pivot point 112. The trigger 28
 pivots about this point 112 upon the application of an actuation force.
 The cam surface 110 within the trigger 28 is formed to cause the cam
 follower 108 and the trigger end 104 to pivot back toward the hand grip
 portion 44, which causes the shuttle end 106 to pivot forward to extend
 the drive pin 18. A trigger bias spring 114 is attached between the
 trigger lever 30 and a spigot 116 in the hand grip portion 44 of the body
 housing 40 to bias the shuttle end 106 and the drive pin shuttle 90 in the
 retracted position. The force of the trigger bias spring 114 is sufficient
 to overcome the force of the latch spring 98.
 The implanter 10 described above is used to implant an object 24 beneath a
 membrane. The method for implanting an object 24 beneath a membrane
 generally comprises the steps of positioning an object 24 to be implanted
 between a drive pin 18 and a hollow needle 14, positioning a plug 38
 between the object 24 and the drive pin 18, inserting the needle 14
 through the membrane, and moving the drive pin 18 from a retracted
 position to an extended position to expel the object 24 through the hollow
 needle 14 and to stop the needle 14 with the plug 38. This method has
 advantages related to preventing blood borne diseases when the object is
 implanted in an animal. The stopped needle is replaced with an unstopped
 needle before implanting another object in another animal. Replacing the
 needles is quick and easy using the quick attachment mechanism 64, and
 generally requires the steps of unscrewing the nut 68 off of the threaded
 collet 66, removing the stopped needle from the collet 66, placing an
 unstopped needle in the collet 66, and screwing the nut 68 onto the collet
 66. Furthermore, the steps of positioning an object 24 to be implanted
 between a drive pin 18 and a hollow needle 14 and positioning the plug 38
 between the object 24 and the drive pin 18 is quickly and easily
 accomplished by pre-loading a plurality of objects 24 and plugs 38 in a
 magazine 26 of tubes and indexing the magazine 26 to position each object
 24 and plug 38 between the drive pin 18 and the needle 14. Additionally,
 the step of moving the drive pin 18 from a retracted position to an
 extended position to expel the object 24 through the hollow needle 14 and
 to stop the needle 14 with the plug 38 is quickly and easily accomplished
 by actuating a trigger 28, and the step of indexing the magazine 26 to
 position each object 24 and plug 38 between the drive pin 18 and the
 needle 14 is quickly and easily accomplished by releasing the trigger 28.
 The descriptions above and the accompanying drawings should be interpreted
 in the illustrative and not the limited sense. While the invention has
 been disclosed in connection with the preferred embodiment or embodiments
 thereof, it should be understood that there may be other embodiments which
 fall within the scope of the invention as defined by the following claims.
 Where a claim, if any, is expressed as a means or step for performing a
 specified function it is intended that such claim be construed to cover
 the corresponding structure, material, or acts described in the
 specification and equivalents thereof, including both structural
 equivalents and equivalent structures, material-based equivalents and
 equivalent materials, and act-based equivalents and equivalent acts.