Motorized surgical instrument

[0001] The present application is a continuation-in-part patent application claiming priority under 35 U.S.C. §120 from commonly-owned, U.S. patent application Ser. No. 13/021,876, filed Feb. 7, 2011, entitled “Motorized Surgical Instrument” to David C. Yates, Thomas W. Huitema, Frederick E. Shelton, IV, and Brett E. Swensgard, U.S. Patent Publication No. US-2011/0125177-A1, which is a continuation patent application claiming priority under 35 U.S.C. §120 from commonly-owned U.S. patent application Ser. No. 12/235,972, filed Sep. 23, 2008, entitled “Motorized Surgical Instrument” to David C. Yates, Thomas W. Huitema, Frederick E. Shelton, IV, and Brett E. Swensgard, U.S. Patent Publication No. US-2010/0076475-A1, the entire disclosures of which are herein incorporated by reference.

[0002] Surgical staplers have been used in the prior art to simultaneously make a longitudinal incision in tissue and apply lines of staples on opposing sides of the incision. Such instruments commonly include a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. Such instruments typically include a plurality of reciprocating wedges that, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.

[0003] An example of a surgical stapler suitable for endoscopic applications is described in published U.S. patent application Pub. No. 2004/0232196 A1, entitled, “Surgical stapling instrument having separate distinct closing and firing systems,” the disclosure of which is herein incorporated by reference. In use, a clinician is able to close the jaw members of the stapler upon tissue to position the tissue prior to firing. Once the clinician has determined that the jaw members are properly gripping tissue, the clinician can fire the surgical stapler, thereby severing and stapling the tissue. The simultaneous severing and stapling steps avoid complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple.

[0004] Motor-powered surgical cutting and fastening instruments, where a motor powers the cutting instrument, are also known in the prior art, such as described in published U.S. application Pub. No. 2007/0175962 A1, entitled “Motor-driven surgical cutting and fastening instrument with tactile position feedback,” which is incorporated herein by reference. In this reference, a battery in the handle is used to electrically power the motor.

[0005] In one general aspect, embodiments of the present invention are directed to motorized surgical instruments. The instruments may be endoscopic instruments, such as linear endocutters or circular cutters, or laparoscopic instruments. The instruments may be comprised of staples and/or RF electrodes for fastening tissue clamped in the end effector.

[0006] Several embodiments disclosed herein are pertinent to cordless motor-powered instruments. In one embodiment, the instrument comprises a charge accumulator device, separate from the battery, that provides additional power to the electric motor when needed. The charge accumulator device may be initially charged by the battery. Then, it may be taken off-line until such time that the extra power from the charge accumulator device is needed. At that time, the charge accumulator device is connected in series with the battery to provide additional power to the motor.

[0007] In another embodiment, the motor may comprise at least two windings. In one mode of operation, the windings are connected in series and in another mode of the operation the windings are connected in parallel. When the windings are connected in series, the motor may have a high-speed low-torque output. When the windings are connected in parallel, the motor may have a low-speed high-torque output. That way, for example, the motor could exhibit both modes of operation, without the instrument having to have multiple motors.

[0008] In yet another embodiment, the instrument utilizes a replaceable (possibly rechargeable) battery pack to electrically power the motor. The battery pack may comprise a plurality of battery cells. A first set of the battery cells may be connected in series in the battery pack, and a second set of battery cells may be connected in series in the battery pack, but, within the battery pack, the first set is not connected in series to the second set. Rather, the instrument may comprise a battery cell connected in the handle, for example, that connects the first set in series with the second set when the battery pack is installed or placed in the instrument.

[0009] These and other benefits of the present invention will be apparent from the description below.

[0025] FIGS. 1 and 2 depict a surgical cutting and fastening instrument 10 according to various embodiments of the present invention. The illustrated embodiment is an endoscopic instrument and, in general, the embodiments of the instrument 10 described herein are endoscopic surgical cutting and fastening instruments. It should be noted, however, that according to other embodiments of the present invention, the instrument may be a non-endoscopic surgical cutting and fastening instrument, such as a laparoscopic instrument.

[0026] The surgical instrument 10 depicted in FIGS. 1 and 2 comprises a handle 6, a shaft 8, and an articulating end effector 12 pivotally connected to the shaft 8 at an articulation pivot 14. An articulation control 16 may be provided adjacent to the handle 6 to effect rotation of the end effector 12 about the articulation pivot 14. In the illustrated embodiment, the end effector 12 is configured to act as an endocutter for clamping, severing and stapling tissue, although, in other embodiments, different types of end effectors may be used, such as end effectors for other types of surgical devices, such as graspers, cutters, staplers, clip appliers, access devices, drug/gene therapy devices, ultrasound, RF or laser devices, etc. More details regarding RF devices may be found in the '312 patent.

[0027] The handle 6 of the instrument 10 may include a closure trigger 18 and a firing trigger 20 for actuating the end effector 12. It will be appreciated that instruments having end effectors directed to different surgical tasks may have different numbers or types of triggers or other suitable controls for operating the end effector 12. The end effector 12 is shown separated from the handle 6 by a preferably elongate shaft 8. In one embodiment, a clinician or operator of the instrument 10 may articulate the end effector 12 relative to the shaft 8 by utilizing the articulation control 16, as described in more detail in published U.S. patent application Pub. No. 2007/0158385 A1, entitled “Surgical Instrument Having An Articulating End Effector,” by Geoffrey C. Hueil et al., which is incorporated herein by reference.

[0028] The end effector 12 includes in this example, among other things, a staple channel 22 and a pivotally translatable clamping member, such as an anvil 24, which are maintained at a spacing that assures effective stapling and severing of tissue clamped in the end effector 12. The handle 6 includes a pistol grip 26 towards which a closure trigger 18 is pivotally drawn by the clinician to cause clamping or closing of the anvil 24 toward the staple channel 22 of the end effector 12 to thereby clamp tissue positioned between the anvil 24 and channel 22. The firing trigger 20 is farther outboard of the closure trigger 18. Once the closure trigger 18 is locked in the closure position as further described below, the firing trigger 20 may rotate slightly toward the pistol grip 26 so that it can be reached by the operator using one hand. Then the operator may pivotally draw the firing trigger 20 toward the pistol grip 12 to cause the stapling and severing of clamped tissue in the end effector 12. In other embodiments, different types of clamping members besides the anvil 24 could be used, such as, for example, an opposing jaw, etc.

[0029] It will be appreciated that the terms “proximal” and “distal” are used herein with reference to a clinician gripping the handle 6 of an instrument 10. Thus, the end effector 12 is distal with respect to the more proximal handle 6. It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical” and “horizontal” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute.

[0030] The closure trigger 18 may be actuated first. Once the clinician is satisfied with the positioning of the end effector 12, the clinician may draw back the closure trigger 18 to its fully closed, locked position proximate to the pistol grip 26. The firing trigger 20 may then be actuated. The firing trigger 20 returns to the open position (shown in FIGS. 1 and 2) when the clinician removes pressure, as described more fully below. A release button on the handle 6, when depressed may release the locked closure trigger 18. The release button may be implemented in various forms such as, for example, as a slide release button 160 shown in FIG. 7 or any of the mechanisms described in published U.S. Patent Application Publication. No. 2007/0175955 A1, which is incorporated herein by reference.

[0031] FIG. 3 is an exploded view of the end effector 12 according to various embodiments. As shown in the illustrated embodiment, the end effector 12 may include, in addition to the previously mentioned channel 22 and anvil 24, a cutting instrument 32, a sled 33, a staple cartridge 34 that is removably seated in the channel 22, and a helical screw shaft 36. The cutting instrument 32 may be, for example, a knife. The anvil 24 may be pivotably opened and closed at a pivot point 25 connected to the proximate end of the channel 22. The anvil 24 may also include a tab 27 at its proximate end that is inserted into a component of the mechanical closure system (described further below) to open and close the anvil 24. When the closure trigger 18 is actuated, that is, drawn in by a user of the instrument 10, the anvil 24 may pivot about the pivot point 25 into the clamped or closed position. If clamping of the end effector 12 is satisfactory, the operator may actuate the firing trigger 20, which, as explained in more detail below, causes the knife 32 and sled 33 to travel longitudinally along the channel 22, thereby cutting tissue clamped within the end effector 12. The movement of the sled 33 along the channel 22 causes the staples of the staple cartridge 34 to be driven through the severed tissue and against the closed anvil 24, which turns the staples to fasten the severed tissue. In various embodiments, the sled 33 may be an integral component of the cartridge 34. U.S. Pat. No. 6,978,921, entitled “Surgical stapling instrument incorporating an E-beam firing mechanism,” which is incorporated herein by reference, provides more details about such two-stroke cutting and fastening instruments. The sled 33 may be part of the cartridge 34, such that when the knife 32 refracts following the cutting operation, the sled 33 does not retract.

[0032] It should be noted that although the embodiments of the instrument 10 described herein employ an end effector 12 that staples the severed tissue, in other embodiments different techniques for fastening or sealing the severed tissue may be used. For example, end effectors that use RF energy or adhesives to fasten the severed tissue may also be used. U.S. Pat. No. 5,709,680 entitled “Electrosurgical Hemostatic Device” to Yates et al., and U.S. Pat. No. 5,688,270 entitled “Electrosurgical Hemostatic Device with Recessed and/or Offset Electrodes” to Yates et al., which are incorporated herein by reference, disclose an endoscopic cutting instrument that uses RF energy to seal the severed tissue. Published U.S. patent application Pub. No. 2007/0102453 A1 to Jerome R. Morgan, et al. and published U.S. patent application Pub. No. 2007/0102452 A1 to Frederick E. Shelton, IV, et al., which are also incorporated herein by reference, disclose endoscopic cutting instruments that use adhesives to fasten the severed tissue. Accordingly, although the description herein refers to cutting/stapling operations and the like below, it should be recognized that this is an exemplary embodiment and is not meant to be limiting. Other tissue-fastening techniques may also be used.

[0033] FIGS. 4 and 5 are exploded views and FIG. 6 is a side view of the end effector 12 and shaft 8 according to various embodiments. As shown in the illustrated embodiment, the shaft 8 may include a proximate closure tube 40 and a distal closure tube 42 pivotably linked by a pivot links 44. The distal closure tube 42 includes an opening 45 into which the tab 27 on the anvil 24 is inserted in order to open and close the anvil 24, as further described below. Disposed inside the closure tubes 40, 42 may be a proximate spine tube 46. Disposed inside the proximate spine tube 46 may be a main rotational (or proximate) drive shaft 48 that communicates with a secondary (or distal) drive shaft 50 via a bevel gear assembly 52. The secondary drive shaft 50 is connected to a drive gear 54 that engages a proximate drive gear 56 of the helical screw shaft 36. The vertical bevel gear 52b may sit and pivot in an opening 57 in the distal end of the proximate spine tube 46. A distal spine tube 58 may be used to enclose the secondary drive shaft 50 and the drive gears 54, 56. Collectively, the main drive shaft 48, the secondary drive shaft 50, and the articulation assembly (e.g., the bevel gear assembly 52a-c) are sometimes referred to herein as the “main drive shaft assembly.”

[0034] A bearing 38, positioned at a distal end of the staple channel 22, receives the helical drive screw 36, allowing the helical drive screw 36 to freely rotate with respect to the channel 22. The helical screw shaft 36 may interface a threaded opening (not shown) of the knife 32 such that rotation of the shaft 36 causes the knife 32 to translate distally or proximately (depending on the direction of the rotation) through the staple channel 22. Accordingly, when the main drive shaft 48 is caused to rotate by actuation of the firing trigger 20 (as explained in more detail below), the bevel gear assembly 52a-c causes the secondary drive shaft 50 to rotate, which in turn, because of the engagement of the drive gears 54, 56, causes the helical screw shaft 36 to rotate, which causes the knife driving member 32 to travel longitudinally along the channel 22 to cut any tissue clamped within the end effector. The sled 33 may be made of, for example, plastic, and may have a sloped distal surface. As the sled 33 traverses the channel 22, the sloped forward surface may push up or drive the staples in the staple cartridge through the clamped tissue and against the anvil 24. The anvil 24 turns the staples, thereby stapling the severed tissue. When the knife 32 is retracted, the knife 32 and sled 33 may become disengaged, thereby leaving the sled 33 at the distal end of the channel 22.

[0035] FIGS. 7-10 illustrate an exemplary embodiment of a motor-driven endocutter. The illustrated embodiment provides user-feedback regarding the deployment and loading force of the cutting instrument in the end effector. In addition, the embodiment may use power provided by the user in retracting the firing trigger 20 to power the device (a so-called “power assist” mode). As shown in the illustrated embodiment, the handle 6 includes exterior lower sidepieces 59, 60 and exterior upper side pieces 61, 62 that fit together to form, in general, the exterior of the handle 6. A battery 64, such as a Li ion battery, may be provided in the pistol grip portion 26 of the handle 6. The battery 64 powers an electric motor 65 disposed in an upper portion of the pistol grip portion 26 of the handle 6. According to various embodiments, a number of battery cells connected in series may be used to power the motor 65.

[0036] The motor 65 may be a brushed driving motor having a maximum rotation of approximately 25,000 RPM with no load. In other embodiments, the motor 65 may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The motor 64 may drive a 90° bevel gear assembly 66 comprising a first bevel gear 68 and a second bevel gear 70. The bevel gear assembly 66 may drive a planetary gear assembly 72. The planetary gear assembly 72 may include a pinion gear 74 connected to a drive shaft 76. The pinion gear 74 may drive a mating ring gear 78 that drives a helical gear drum 80 via a drive shaft 82. A ring 84 may be threaded on the helical gear drum 80. Thus, when the motor 65 rotates, the ring 84 is caused to travel along the helical gear drum 80 by means of the interposed bevel gear assembly 66, planetary gear assembly 72, and ring gear 78.

[0037] The handle 6 may also include a run motor sensor 110 in communication with the firing trigger 20 to detect when the firing trigger 20 has been drawn in (or “closed”) toward the pistol grip portion 26 of the handle 6 by the operator to thereby actuate the cutting/stapling operation by the end effector 12. The sensor 110 may be a proportional sensor such as, for example, a rheostat, or variable resistor. When the firing trigger 20 is drawn in, the sensor 110 detects the movement, and sends an electrical signal indicative of the voltage (or power) to be supplied to the motor 65. When the sensor 110 is a variable resistor or the like, the rotation of the motor 65 may be generally proportional to the amount of movement of the firing trigger 20. That is, if the operator only draws or closes the firing trigger 20 in a little bit, the rotation of the motor 65 is relatively low. When the firing trigger 20 is fully drawn in (or in the fully closed position), the rotation of the motor 65 is at its maximum. In other words, the harder the user pulls on the firing trigger 20, the more voltage is applied to the motor 65, causing greater rates of rotation.

[0038] The handle 6 may include a middle handle piece 104 adjacent to the upper portion of the firing trigger 20. The handle 6 also may comprise a bias spring 112 connected between posts on the middle handle piece 104 and the firing trigger 20. The bias spring 112 may bias the firing trigger 20 to its fully open position. In that way, when the operator releases the firing trigger 20, the bias spring 112 will pull the firing trigger 20 to its open position, thereby removing actuation of the sensor 110, thereby stopping rotation of the motor 65. Moreover, by virtue of the bias spring 112, any time a user closes the firing trigger 20, the user will experience resistance to the closing operation, thereby providing the user with feedback as to the amount of rotation exerted by the motor 65. Further, the operator could stop retracting the firing trigger 20 to remove thereby force from the sensor 100, to thereby stop the motor 65. As such, the user may stop the deployment of the end effector 12, thereby providing a measure of control of the cutting/fastening operation to the operator.

[0039] The distal end of the helical gear drum 80 includes a distal drive shaft 120 that drives a ring gear 122, which mates with a pinion gear 124. The pinion gear 124 is connected to the main drive shaft 48 of the main drive shaft assembly. In that way, rotation of the motor 65 causes the main drive shaft assembly to rotate, which causes actuation of the end effector 12, as described above.

[0040] The ring 84 threaded on the helical gear drum 80 may include a post 86 that is disposed within a slot 88 of a slotted arm 90. The slotted arm 90 has an opening 92 its opposite end 94 that receives a pivot pin 96 that is connected between the handle exterior side pieces 59, 60. The pivot pin 96 is also disposed through an opening 100 in the firing trigger 20 and an opening 102 in the middle handle piece 104.

[0041] In addition, the handle 6 may include a reverse motor (or end-of-stroke sensor) 130 and a stop motor (or beginning-of-stroke) sensor 142. In various embodiments, the reverse motor sensor 130 may be a limit switch located at the distal end of the helical gear drum 80 such that the ring 84 threaded on the helical gear drum 80 contacts and trips the reverse motor sensor 130 when the ring 84 reaches the distal end of the helical gear drum 80. The reverse motor sensor 130, when activated, sends a signal to the motor 65 to reverse its rotation direction, thereby withdrawing the knife 32 of the end effector 12 following the cutting operation. The stop motor sensor 142 may be, for example, a normally closed limit switch. In various embodiments, it may be located at the proximate end of the helical gear drum 80 so that the ring 84 trips the switch 142 when the ring 84 reaches the proximate end of the helical gear drum 80.

[0042] In operation, when an operator of the instrument 10 pulls back the firing trigger 20, the sensor 110 detects the deployment of the firing trigger 20 and sends a signal to the motor 65 to cause forward rotation of the motor 65 at, for example, a rate proportional to how hard the operator pulls back the firing trigger 20. The forward rotation of the motor 65 in turn causes the ring gear 78 at the distal end of the planetary gear assembly 72 to rotate, thereby causing the helical gear drum 80 to rotate, causing the ring 84 threaded on the helical gear drum 80 to travel distally along the helical gear drum 80. The rotation of the helical gear drum 80 also drives the main drive shaft assembly as described above, which in turn causes deployment of the knife 32 in the end effector 12. That is, the knife 32 and sled 33 are caused to traverse the channel 22 longitudinally, thereby cutting tissue clamped in the end effector 12. Also, the stapling operation of the end effector 12 is caused to happen in embodiments where a stapling-type end effector is used.

[0043] By the time the cutting/stapling operation of the end effector 12 is complete, the ring 84 on the helical gear drum 80 will have reached the distal end of the helical gear drum 80, thereby causing the reverse motor sensor 130 to be tripped, which sends a signal to the motor 65 to cause the motor 65 to reverse its rotation. This in turn causes the knife 32 to retract, and also causes the ring 84 on the helical gear drum 80 to move back to the proximate end of the helical gear drum 80.

[0044] The middle handle piece 104 includes a backside shoulder 106 that engages the slotted arm 90 as best shown in FIGS. 8 and 9. The middle handle piece 104 also has a forward motion stop 107 that engages the firing trigger 20. The movement of the slotted arm 90 is controlled, as explained above, by rotation of the motor 65. When the slotted arm 90 rotates CCW as the ring 84 travels from the proximate end of the helical gear drum 80 to the distal end, the middle handle piece 104 will be free to rotate CCW. Thus, as the user draws in the firing trigger 20, the firing trigger 20 will engage the forward motion stop 107 of the middle handle piece 104, causing the middle handle piece 104 to rotate CCW. Due to the backside shoulder 106 engaging the slotted arm 90, however, the middle handle piece 104 will only be able to rotate CCW as far as the slotted arm 90 permits. In that way, if the motor 65 should stop rotating for some reason, the slotted arm 90 will stop rotating, and the user will not be able to further draw in the firing trigger 20 because the middle handle piece 104 will not be free to rotate CCW due to the slotted arm 90.

[0045] Components of an exemplary closure system for closing (or clamping) the anvil 24 of the end effector 12 by retracting the closure trigger 18 are also shown in FIGS. 7-10. In the illustrated embodiment, the closure system includes a yoke 250 connected to the closure trigger 18 by a pin 251 that is inserted through aligned openings in both the closure trigger 18 and the yoke 250. A pivot pin 252, about which the closure trigger 18 pivots, is inserted through another opening in the closure trigger 18 which is offset from where the pin 251 is inserted through the closure trigger 18. Thus, retraction of the closure trigger 18 causes the upper part of the closure trigger 18, to which the yoke 250 is attached via the pin 251, to rotate CCW. The distal end of the yoke 250 is connected, via a pin 254, to a first closure bracket 256. The first closure bracket 256 connects to a second closure bracket 258. Collectively, the closure brackets 256, 258 define an opening in which the proximate end of the proximate closure tube 40 (see FIG. 4) is seated and held such that longitudinal movement of the closure brackets 256, 258 causes longitudinal motion by the proximate closure tube 40. The instrument 10 also includes a closure rod 260 disposed inside the proximate closure tube 40. The closure rod 260 may include a window 261 into which a post 263 on one of the handle exterior pieces, such as exterior lower sidepiece 59 in the illustrated embodiment, is disposed to fixedly connect the closure rod 260 to the handle 6. In that way, the proximate closure tube 40 is capable of moving longitudinally relative to the closure rod 260. The closure rod 260 may also include a distal collar 267 that fits into a cavity 269 in proximate spine tube 46 and is retained therein by a cap 271 (see FIG. 4).

[0046] In operation, when the yoke 250 rotates due to retraction of the closure trigger 18, the closure brackets 256, 258 cause the proximate closure tube 40 to move distally (i.e., away from the handle end of the instrument 10), which causes the distal closure tube 42 to move distally, which causes the anvil 24 to rotate about the pivot point 25 into the clamped or closed position. When the closure trigger 18 is unlocked from the locked position, the proximate closure tube 40 is caused to slide proximately, which causes the distal closure tube 42 to slide proximately, which, by virtue of the tab 27 being inserted in the window 45 of the distal closure tube 42, causes the anvil 24 to pivot about the pivot point 25 into the open or unclamped position. In that way, by retracting and locking the closure trigger 18, an operator may clamp tissue between the anvil 24 and channel 22, and may unclamp the tissue following the cutting/stapling operation by unlocking the closure trigger 20 from the locked position.

[0047] Additional configurations for motorized surgical instruments are disclosed in published U.S. application Pub. No. 2007/0175962 A1, entitled “Motor-driven surgical cutting and fastening instrument with tactile position feedback,” which is incorporated herein by reference in its entirety.

[0048] FIG. 11 is a schematic diagram of the motor control circuit according to various embodiments of the present invention. In various embodiments, the motor control circuit may include one of more integrated circuits (ICs), such as, for example, a processor, memory, microcontroller, time circuits, etc. In other embodiments, the motor control circuit may not comprise any ICs. Such a non-IC motor control circuit may be advantageous because it is often difficult, complicated, and expensive to sterilize a surgical instrument including ICs.

[0049] When an operator initially pulls in the firing trigger 20 after locking the closure trigger 18, the sensor 110 is activated (or closed, where the sensor 110 is a switch), allowing current to flow therethrough. If the normally open reverse motor sensor switch 130 is open (meaning the end of the end effector stroke has not been reached), current will flow to a single pole, double throw relay 132. When the reverse motor sensor switch 130 is not closed, a coil 134 of the relay 132 will not be energized, so the relay 132 will be in its de-energized state.

[0050] As shown in FIG. 11, the circuit may also include a resistive element 144 and a switch 146 connected in parallel, with the paralleled elements connected in series with the relay 132. The resistive element 144 and the switch 146 are also connected to the power source 64. The switch 146 may be controlled by a control circuit 148 that is responsive to the cutting instrument position sensor 150. According to various embodiments, the control circuit 148 may open the switch 146 when the cutting instrument 32 is (i) very near to the beginning of its stroke and (ii) very near to the end of its stroke. For example, the control circuit may open the switch when the cutting instrument 32 is (i) 0.001 inches from the beginning point of its stroke and (ii) 0.001 inches from the end of its stroke, as determined by the cutting instrument position sensor 150. With the switch 146 open, current flows through the resistive element 144, and then through the relay 132, the relay 138, the run motor sensor switch 110, to the motor 65. Current flowing through the resistive element 144 reduces the magnitude of the current delivered to the motor 65, thereby reducing the power delivered by the motor 65. Thus, when the cutting instrument 32 is (i) very near to the beginning of its stroke or (ii) very near to the end of its stroke, the power delivered by the motor 65 is reduced. Conversely, once the cutting instrument 32 moves sufficiently far from its beginning point or end of stroke point, the control circuit 148 may close the switch 146, thereby shorting the resistive element 144, thereby increasing the current to the motor 65, thereby increasing the power delivered by the motor.

[0051] According to various embodiments, the electrical circuit further includes lockout sensor switches 136a-d collectively defining an interlock circuit 137 through which current from the relay 132, when de-energized, passes in order for electrical operation of the motor 65 to be initiated. Each lockout sensor switch 136a-d may be configured to maintain an open (i.e., non-conductive) switch state or a closed (i.e., conductive) switch state responsive to the presence or absence, respectively, of a corresponding condition. Any of the corresponding conditions, if present when the instrument 10 is fired, may result in an unsatisfactory cutting and stapling operation and/or damage to the instrument 10. Conditions to which the lockout sensor switches 136a-d may respond include, for example, (a) the absence of the staple cartridge 34 in the channel 22, (b) the presence of a spent (e.g., previously fired) staple cartridge 34 in the channel 22, and (c) an open (or otherwise insufficiently closed) position of the anvil 24 with respect to the channel 22. Other conditions to which the lockout sensor switches 136a-d may respond, such as component wear, may be inferred based upon an accumulated number of firing operations produced by the instrument 10. Accordingly, in various embodiments, if any of these conditions exists, the corresponding lockout sensor switches 136a-d maintain an open switch state, thus preventing passage of the current necessary to initiate operation of the motor 65. Passage of current by the lockout sensors 136a-d is allowed, in various embodiments, only after all of the conditions have been remedied. It will be appreciated that the above-described conditions are provided by way of example only, and that additional lockout sensor switches for responding to other conditions detrimental to operation of the instrument 10 may be provided. It will similarly be appreciated that for embodiments in which one or more of the above-described conditions may not exist or are of no concern, the number of lockout sensor switches may be fewer than that depicted.

[0052] As shown in FIG. 11, the lockout sensor switch 136a may be implemented using a normally open switch configuration such that a closed switch state is maintained when the staple cartridge 34 is in a position corresponding to its proper receipt by the channel 22. When the staple cartridge 34 is not installed in the channel 22, or is installed improperly (e.g., misaligned), the lockout sensor switch 136a maintains an open switch state. Lockout sensor switch 136b may be implemented using a normally open switch configuration such that a closed switch state is maintained only when an unspent staple cartridge 34 (i.e., a staple cartridge 34 having a sled 33 in the unfired position) is present in the channel 22. The presence of a spent staple cartridge 34 in the channel 22 causes the lockout sensor switch 136b to maintain an open switch state. Lockout sensor switch 136c may be implemented using a normally open switch configuration such that a closed switch state is maintained when the anvil 24 is in a closed position with respect to the channel 22. The lockout sensor switch 136c may be controlled in accordance with a time delay feature wherein a closed switch state is maintained only after the anvil 24 is in the closed position for a pre-determined period of time.

[0053] Lockout sensor switch 136d may be implemented using a normally closed switch configuration such that a closed switch state is maintained only when an accumulated number of firings produced by the instrument 10 is less than a pre-determined number. The lockout sensor switch 136d may be in communication with a counter 139 configured for maintaining a count representative of the accumulated number of firing operations performed by the instrument 10, comparing the count to the pre-determined number, and controlling the switch state of the lockout sensor switch 136d based upon the comparison. Although shown separately in FIG. 11, it will be appreciated that counter 139 may be integral with the lockout sensor switch 136d so as to form a common device. Preferably, the counter 139 is implemented as an electronic device having an input for incrementing the maintained count based upon the transition of a discrete electrical signal provided thereto. It will be appreciated that a mechanical counter configured for maintaining the count based upon a mechanical input (e.g., retraction of the firing trigger 20) may be used instead. When implemented as an electronic device, any discrete signal present in the electrical circuit that transitions once for each firing operation may be utilized for the counter 139 input. As shown in FIG. 11, for example, the discrete electrical signal resulting from actuation of the end-of-stroke sensor 130 may be utilized. The counter 139 may control the switch state of lockout sensor switch 136d such that a closed switch state is maintained when the maintained count is less than a pre-determined number stored within the counter 139. When the maintained count is equal to the pre-determined number, the counter 139 causes the lockout sensor switch 136d to maintain an open switch state, thus preventing the passage of current therethrough. It will be appreciated that the pre-determined number stored by the counter 139 may be selectively adjusted as required. According to various embodiments, the counter 304 may be in communication with an external display (not shown), such as an LCD display, integral to the instrument 10 for indicating to a user either the maintained count or the difference between the pre-determined number and the maintained count.

[0054] According to various embodiments, the interlock circuit 137 may comprise one or more indicators visible to the user of the instrument 10 for displaying a status of at least one of the lockout sensor switches 136a-d. More details regarding such indicators may be found in published U.S. patent application Pub. No. 2007/0175956, entitled “Electronic lockouts and surgical instrument including same,” which is incorporated herein by reference in its entirety. This application also includes example mounting arrangements and configurations for the lockout sensor switches 136a-d.

[0055] In the illustrated embodiment, when the lockout sensor switches 136a-d collectively maintain a closed switch state, a single pole, single throw relay 138 is energized. When the relay 138 is energized, current flows through the relay 138, through the run motor switch sensor 110, and to the motor 65 via a double pole, double throw relay 140, thereby powering the motor 65, allowing it to rotate in the forward direction. According to various embodiments, because the output of the relay 138, once energized, maintains the relay 138 in an energized state until relay 132 is energized, the interlock circuit 137 will not function to prevent operation of the motor 165 once initiated, even if one or more of the interlock sensor switches 136a-d subsequently maintains an open switch state. In other embodiments, however, it may be necessary or otherwise desirable to connect the interlock circuit 137 and the relay 138 such that one or more the lockout sensor switches 136a-d must maintain a closed switch state in order to sustain operation of the motor 165 once initiated.

[0056] Rotation of the motor in the forward direction causes the ring 84 to move distally and thereby de-actuate the stop motor sensor switch 142 in various embodiments. Because the switch 142 is normally closed, a solenoid 141 connected to the switch 142 may be energized. The solenoid 141 may be a conventional push-type solenoid that, when energized, causes a plunger (not shown) to be axially extended. Extension of the plunger may operate to retain the closure trigger 18 in the retracted position, thus preventing the anvil 24 from opening while a firing operation is in progress (i.e., while the switch 142 is not actuated). Upon deenergization of the solenoid 141, the plunger is retracted such that manual release of the closure trigger 18 is possible.

[0057] When the end effector 12 reaches the end of its stroke, the reverse motor sensor 130 will be activated, thereby closing the switch 130 and energizing the relay 132. This causes the relay 132 to assume its energized state (not shown in FIG. 11), which causes current to bypass the interlock circuit 137 and run motor sensor switch 110, and instead causes current to flow to both the normally-closed double pole, double throw relay 140 and back to the motor 65, but in a manner, via the relay 140, that causes the motor 65 to reverse its rotational direction. Because the stop motor sensor switch 142 is normally closed, current will flow back to the relay 132 to keep it energized until the switch 142 opens. When the knife 32 is fully retracted, the stop motor sensor switch 142 is activated, causing the switch 142 to open, thereby removing power from the motor 65, and de-energizing the solenoid 141.

[0058] In other embodiments, other alternatives may be used to limit the current supplied to the motor 65 during certain time periods during the cutting stroke cycle. Other embodiments are described in U.S. patent application Ser. No. 12/235,782, which is incorporated herein by reference in its entirety.

[0059] In some instances, it may be advantageous to provide a momentary increase in current to the motor 65 to increase the output torque. FIG. 19A shows an embodiment of a circuit for providing a momentary increase to the motor 65 according to various embodiments. The circuit is similar to that shown in FIG. 11, except that the circuit of FIG. 19A additionally includes a charge accumulator device 1000 connected to the power source 64. The charge accumulator device 1000 may be any device that can store charge, such as a capacitor. For example, the charge accumulator device 1000 may comprise an ultracapacitor (sometimes called a supercapacitor). When the motor 65 is first turned on, such as when the switch 110 is closed due to retraction of the firing trigger 20, the switch S1 may be closed so that the battery 64 can power the motor 65 as described above. In addition, the switch S3 may also be closed for only a brief period of time (“the charging period”) to charge the charge accumulator device 1000 via the resistor R. For example, according to various embodiments, the switch S3 may be closed for one to ten RC time constants, where R is the resistance of the resistor R and C is the capacitance of the charge accumulator device 1000.

[0060] The charge in the charge accumulator device 1000 may remain unused during normal operating conditions, but if there comes a time in the procedure where the clinician needs additional output torque from the motor 65, the charge accumulator device 1000 could be put in series with the battery 64. This could be done, for example, by opening switch S1 and closing switch S2 (with S3 remaining open following the charging period). With switch S2 closed, the charge accumulator device 1000 would be connected in series with the battery 64, thereby supplying additional current to the motor 65.

[0061] The condition requiring the charge accumulator device 1000 may be detected in numerous ways. For example, there may be a variable resistor or spring connected to the firing trigger 20. When the firing trigger is retracted beyond a certain point or with a force above a threshold level, the charge accumulator device 1000 may be connected in series to the battery 64. Additionally or alternatively, the handle 6 may comprise an external switch (not shown) that the clinician could activate to connect the charge accumulator device 1000 in series with battery 64.

[0062] The charge accumulator device 1000 could be used with or without the current limiting devices described above in connection with FIG. 11.

[0063] FIG. 19B shows an embodiment of an alternative circuit to that shown in FIG. 19A for providing a momentary increase in current to the motor 65 according to various embodiments. In some arrangements of the circuit, the battery 64 alone may power the motor 65. For example, switch Sb can be closed, in combination with switch 110 being closed, to provide power from only the battery 64 to the motor 65. The remaining switches Sa, Sc, Sd, and Se can remain open. As another example, switches Sd and Se can be closed, in combination with switch 110 being closed, to provide power from only the battery 64 to the motor 65. The remaining switches Sa, Sc, and Sb can remain open. As yet another example, switches Sb, Sd, and Se can be closed, in combination with switch 110 being closed, to provide power from only the battery 64 to the motor 65. The remaining switches Sa and Sc can remain open. In some arrangements of the circuit, the battery 64 may charge the charge accumulator device 1000 without powering the motor 65. For example, switches Sc and Sd can be closed to charge the charge accumulator device 1000 without powering the motor 65. The remaining switches Sa, Sb, and Se can remain open. In some arrangements of the circuit, the battery 64 can simultaneously power the motor 65 and charge the charge accumulator device 1000. For example, switches Sc, Sd, and Se can be closed, in combination with switch 110 being closed, to simultaneously charge the charge accumulator device 1000 and power the motor 65. The remaining switches Sa and Sb can remain open. As another example, switches Sb, Sc, and Se can be closed, in combination with switch 110 being closed, to simultaneously charge the charge accumulator device 1000 and power the motor 65. The remaining switches Sa and Sd can remain open. As another example, switches Sb, Sc, Sd, and Se can be closed, in combination with switch 110 being closed, to simultaneously charge the charge accumulator device 1000 and power the motor 65. The remaining switch Sa can remain open. In some arrangements of the circuit, the battery 64 and the charged charge accumulator device 1000 can be coupled in series to power the motor 65. For example, switches Sa and Se can be closed, in combination with switch 110 being closed, to couple the battery 64 and charge accumulator device 1000 in series with the motor 65. The remaining switches Sb, Sc, and Sd can remain open.

[0064] FIG. 19C shows an embodiment of an alternative circuit to the circuits shown in FIGS. 19A and 19B for providing a momentary increase in current to the motor 65 according to various embodiments. In some arrangements of the circuit, the battery 64 alone may power the motor 65. For example, switches Sd and Se can be closed, in combination with switch 110 being closed, to provide power from only the battery 64 to the motor 65. The remaining switches Sa and Sc can remain open. In some arrangements of the circuit, the battery 64 may charge the charge accumulator device 1000 without powering the motor 65. For example, switches Sc and Sd can be closed to charge the charge accumulator device 1000 without powering the motor 65. The remaining switches Sa and Se can remain open. In some arrangements of the circuit, the battery 64 can simultaneously power the motor 65 and charge the charge accumulator device 1000. For example, switches Sc, Sd, and Se can be closed, in combination with switch 110 being closed, to simultaneously charge the charge accumulator device 1000 and power the motor 65. The remaining switch Sa can remain open. In some arrangements of the circuit, the battery 64 and the charged charge accumulator device 1000 can be coupled in series to power the motor 65. For example, switches Sa and Se can be closed, in combination with switch 110 being closed, to couple the battery 64 and charge accumulator device 1000 in series with the motor 65. The remaining switches Sc and Sd can remain open.

[0065] At some times during use of the instrument 10, it may be advantageous to have the motor 65 run at high speed but relatively low torque output. At other times, it may be desirable to have the motor 65 have a high torque output but at low speeds. According to various embodiments, this functionality may be accomplished with a motor 65 having multiple (e.g., two or more) windings, as shown in FIG. 20. In the illustrated embodiment, the motor has two windings. A first winding 1200 may have winding halves (or portions) 1201 and 1202. A second winding 1204 may have winding halves (or portions) 1206 and 1208. The motor 65 in this example may be a 6 or 8 lead motor with a bipolar driving circuit 1210 (see FIGS. 11 and 12, for example). When the high-speed low-torque mode is desired, the two sets of winding may be connected in series. In this mode, as shown in FIG. 20, switches S1 and S4 are closed, and switches S2, S3, S5, and S6 are open. When the low-speed high-torque mode is desired, the two sets of windings may be connected in parallel. In this mode, switches S1 and S4 are open, and switches S2, S3, S5, and S6 are closed. The ability to transition between the two modes effectively creates a two-speed transmission with no additional moving parts. It also allows the same motor to generate both high speeds and high torque outputs, albeit not at the same time. An advantage of this configuration is that it avoids using multiple motors. In addition, it may be possible to eliminate some gearing because the motor 65 can generate extra torque when in the parallel mode and extra speed when in the series mode. In addition, additional windings could be employed such that a greater number of operating modes may be realized. For example, there could be windings for multiple combinations of series and parallel winding connections. Also, some windings may be used for sensing motor conditions, etc.

[0066] According to various embodiments, the handle 6 may comprise an external motor mode selection switch 1220, as shown in FIG. 21. By using the switch 1220, the operator of the instrument 10 could select with the motor 65 is in the high-speed low-torque mode or in the low-speed high-torque mode. Other switching circuits could also be used to toggle the motor 65 between the operating modes, such as switching circuits that automatically switch the motor mode based on sensor inputs.

[0067] In a motorized surgical instrument, such as one of the motorized endoscopic instruments described above or in a motorized circular cutter instrument, the motor may be powered by a number of battery cells connected in series. Further, it may be desirable in certain circumstances to power the motor with some fraction of the total number of battery cells. For example, as shown in FIG. 12, the motor 65 may be powered by a power pack 299 comprising six (6) battery cells 310 connected in series. The battery cells 310 may be, for example, 3-volt lithium battery cells, such as CR 123A battery cells, although in other embodiments, different types of battery cells could be used (including battery cells with different voltage levels and/or different chemistries). If six 3-volt battery cells 310 were connected in series to power the motor 65, the total voltage available to power the motor 65 would be 18 volts. The battery cells 310 may comprise rechargeable or non-rechargeable battery cells.

[0068] In such an embodiment, under the heaviest loads, the input voltage to the motor 65 may sag to about nine to ten volts. At this operating condition, the power pack 299 is delivering maximum power to the motor 65. Accordingly, as shown in FIG. 12, the circuit may include a switch 312 that selectively allows the motor 65 to be powered by either (1) all of the battery cells 310 or (2) a fraction of the battery cells 310. As shown in FIG. 12, by proper selection, the switch 312 may allow the motor 65 to be powered by all six battery cells or four of the battery cells. That way, the switch 312 could be used to power the motor 65 with either 18 volts (when using all six battery cells 310) or 12 volts (such using four of the second battery cells). In various embodiments, the design choice for the number of battery cells in the fraction that is used to power the motor 65 may be based on the voltage required by the motor 65 when operating at maximum output for the heaviest loads.

[0069] The switch 312 may be, for example, an electromechanical switch, such as a micro switch. In other embodiments, the switch 312 may be implemented with a solid-state switch, such as transistor. A second switch 314, such as a push button switch, may be used to control whether power is applied to the motor 65 at all. Also, a forward/reverse switch 316 may be used to control whether the motor 65 rotates in the forward direction or the reverse direction. The forward/reverse switch 316 may be implemented with a double pole-double throw switch, such as the relay 140 shown in FIG. 11.

[0070] In operation, the user of the instrument 10 could select the desired power level by using some sort of switch control, such as a position-dependent switch (not shown), such as a toggle switch, a mechanical lever switch, or a cam, which controls the position of the switch 312. Then the user may activate the second switch 314 to connect the selected battery cells 310 to the motor 65. In addition, the circuit shown in FIG. 12 could be used to power the motor of other types of motorized surgical instruments, such as circular cutters and/or laparoscopic instruments. More details regarding circular cutters may be found in published U.S. patent applications Pub. No. 2006/0047307 A1 and Pub. No. 2007/0262116 A1, which are incorporated herein by reference.

[0071] In other embodiments, as shown in FIG. 13, a primary power source 340, such as a battery cell, such as a CR2 or CR123A battery cell, may be used to charge a number of secondary accumulator devices 342. The primary power source 340 may comprise one or a number of series-connected battery cells, which are preferably replaceable in the illustrated embodiment. The secondary accumulator devices 342 may comprise, for example, rechargeable battery cells and/or supercapacitors (also known as “ultracapacitors” or “electrochemical double layer capacitors” (EDLC)). Supercapacitors are electrochemical capacitors that have an unusually high energy density when compared to common electrolytic capacitors, typically on the order of thousands of times greater than a high-capacity electrolytic capacitor.

[0072] The primary power source 340 may charge the secondary accumulator devices 342. Once sufficiently charged, the primary power source 340 may be removed and the secondary accumulator devices 342 may be used to power the motor 65 during a procedure or operation. The accumulating devices 342 may take about fifteen to thirty minutes to charge in various circumstances. Supercapacitors have the characteristic they can charge and discharge extremely rapidly in comparison to conventional batteries. In addition, whereas batteries are good for only a limited number of charge/discharge cycles, supercapacitors can often be charged/discharged repeatedly, sometimes for tens of millions of cycles. For embodiments using supercapacitors as the secondary accumulator devices 342, the supercapacitors may comprise carbon nanotubes, conductive polymers (e.g., polyacenes), or carbon aerogels.

[0073] As shown in FIG. 14, a charge management circuit 344 could be employed to determine when the secondary accumulator devices 342 are sufficiently charged. The charge management circuit 344 may include an indicator, such as one or more LEDs, an LCD display, etc., that is activated to alert a user of the instrument 10 when the secondary accumulator devices 342 are sufficiently charged.

[0074] The primary power source 340, the secondary accumulator devices 342, and the charge management circuit 344 may be part of a power pack in the pistol grip portion 26 of the handle 6 of the instrument 10, or in another part of the instrument 10. The power pack may be removable from the pistol grip portion 26, in which case, when the instrument 10 is to be used for surgery, the power pack may be inserted aseptically into the pistol grip portion 26 (or other position in the instrument according to other embodiments) by, for example, a circulating nurse assisting in the surgery. After insertion of the power pack, the nurse could put the replaceable primary power source 340 in the power pack to charge up the secondary accumulator devices 342 a certain time period prior to use of the instrument 10, such as thirty minutes. When the secondary accumulator devices 342 are charged, the charge management circuit 344 may indicate that the power pack is ready for use. At this point, the replaceable primary power source 340 may be removed. During the operation, the user of the instrument 10 may then activate the motor 65, such as by activating the switch 314, whereby the secondary accumulator devices 342 power the motor 65. Thus, instead of having a number of disposable batteries to power the motor 65, one disposable battery (as the primary power source 340) could be used in such an embodiment, and the secondary accumulator devices 342 could be reusable. In alternative embodiments, however, it should be noted that the secondary accumulator devices 342 could be non-rechargeable and/or non-reusable. The secondary accumulators 342 may be used with the cell selection switch 312 described above in connection with FIG. 12.

[0075] The charge management circuit 344 may also include indicators (e.g., LEDs or LCD display) that indicate how much charge remains in the secondary accumulator devices 342. That way, the surgeon (or other user of the instrument 10) can see how much charge remains through the course of the procedure involving the instrument 10.

[0076] The charge management circuit 344, as shown in FIG. 15, may comprise a charge meter 345 for measuring the charge across the secondary accumulators 342. The charge management circuit 344 also may comprise a non-volatile memory 346, such as flash or ROM memory, and one or more processors 348. The processor(s) 348 may be connected to the memory 346 to control the memory. In addition, the processor(s) 348 may be connected to the charge meter 345 to read the readings of and otherwise control the charge meter 345. Additionally, the processor(s) 348 may control the LEDs or other output devices of the charge management circuit 344. The processor(s) 348 can store parameters of the instrument 10 in the memory 346. The parameters may include operating parameters of the instrument that are sensed by various sensors that may be installed or employed in the instrument 10, such as, for example, the number of firings, the levels of forces involved, the distance of the compression gap between the opposing jaws of the end effector 12, the amount of articulation, etc. Additionally, the parameters stored in the memory 346 may comprise ID values for various components of the instrument 10 that the charge management circuit 344 may read and store. The components having such IDs may be replaceable components, such as the staple cartridge 34. The IDs may be for example, RFIDs that the charge management circuit 344 reads via a RFID transponder 350. The RFID transponder 350 may read RFIDs from components of the instrument, such as the staple cartridge 34, that include RFID tags. The ID values may be read, stored in the memory 346, and compared by the processor 348 to a list of acceptable ID values stored in the memory 346 or another store associated with the charge management circuit, to determine, for example, if the removable/replaceable component associated with the read ID value is authentic and/or proper. According to various embodiments, if the processor 348 determines that the removable/replaceable component associated with the read ID value is not authentic, the charge management circuit 344 may prevent use of the power pack by the instrument 10, such as by opening a switch (not shown) that would prevent power from the power pack being delivered to the motor 65. According to various embodiments, various parameters that the processor 348 may evaluate to determine whether the component is authentic and/or proper include: date code; component model/type; manufacturer; regional information; and previous error codes.

[0077] The charge management circuit 344 may also comprise an i/o interface 352 for communicating with another device, such as described below. That way, the parameters stored in the memory 346 may be downloaded to another device. The i/o interface 352 may be, for example, a wired or wireless interface.

[0078] As mentioned before, the power pack may comprise the secondary accumulators 342, the charge management circuit 344, and/or the f/r switch 316. According to various embodiments, as shown in FIG. 16, the power pack 299 could be connected to a charger base 362, which may, among other things, charge the secondary accumulators 342 in the power pack. The charger base 362 could be connected to the power pack 299 by connecting aseptically the charger base 362 to the power pack 299 while the power pack is installed in the instrument 10. In other embodiments where the power pack is removable, the charger base 362 could be connected to the power pack 299 by removing the power pack 299 from the instrument 10 and connecting it to the charger base 362. For such embodiments, after the charger base 362 sufficiently charges the secondary accumulators 342, the power pack 299 may be aseptically installed in the instrument 10.

[0079] As shown in FIG. 16, the charger base 362 may comprise a power source 364 for charging the secondary accumulators 342. The power source 364 of the charger base 362 may be, for example, a battery (or a number of series-connected batteries), or an AC/DC converter that converters AC power, such as from electrical power mains, to DC, or any other suitable power source for charging the secondary accumulators 342. The charger base 362 may also comprise indicator devices, such as LEDs, a LCD display, etc., to show the charge status of the secondary accumulators 342.

[0080] In addition, as shown in FIG. 16, the charger base 362 may comprise one or more processors 366, one or more memory units 368, and i/o interfaces 370, 372. Through the first i/o interface 370, the charger base 362 may communicate with the power pack 299 (via the power pack's i/o interface 352). That way, for example, data stored in the memory 346 of the power pack 299 may be downloaded to the memory 368 of the charger base 362. In that way, the processor 366 can evaluate the ID values for the removable/replaceable components, downloaded from the charge management circuit 344, to determine the authenticity and suitability of the components. The operating parameters downloaded from the charge management circuit 344 may also stored in the memory 368, and then may then be downloaded to another computer device via the second i/o interface 372 for evaluation and analysis, such as by the hospital system in which the operation involving the instrument 10 is performed, by the office of the surgeon, by the distributor of the instrument, by the manufacturer of the instrument, etc.

[0081] The charger base 362 may also comprise a charge meter 374 for measuring the charge across the secondary accumulators 342. The charge meter 374 may be in communication with the processor(s) 366, so that the processor(s) 366 can determine in real-time the suitability of the power pack 299 for use to ensure high performance.

[0082] In another embodiment, as shown in FIG. 17, the battery circuit may comprise a power regulator 320 to control the power supplied by the power savers 310 to the motor 65. The power regulator 320 may also be part of the power pack 299, or it may be a separate component. As mentioned above, the motor 65 may be a brushed motor. The speed of brushed motors generally is proportional to the applied input voltage. The power regulator 320 may provide a highly regulated output voltage to the motor 65 so that the motor 65 will operate at a constant (or substantially constant) speed. According to various embodiments, the power regulator 320 may comprise a switch-mode power converter, such as a buck-boost converter, as shown in the example of FIG. 17. Such a buck-boost converter 320 may comprise a power switch 322, such as a FET, a rectifier 32, an inductor 326, and a capacitor 328. When the power switch 322 is on, the input voltage source (e.g., the power sources 310) is directly connected to the inductor 326, which stores energy in this state. In this state, the capacitor 328 supplies energy to the output load (e.g., the motor 65). When the power switch 320 is in the off state, the inductor 326 is connected to the output load (e.g., the motor 65) and the capacitor 328, so energy is transferred from the inductor 326 to the capacitor 328 and the load 65. A control circuit 330 may control the power switch 322. The control circuit 330 may employ digital and/or analog control loops. In addition, in other embodiments, the control circuit 330 may receive control information from a master controller (not shown) via a communication link, such as a serial or parallel digital data bus. The voltage set point for the output of the power regulator 320 may be set, for example, to one-half of the open circuit voltage, at which point the maximum power available from the source is available.

[0083] In other embodiments, different power converter topologies may be employed, including linear or switch-mode power converters. Other switch-mode topologies that may be employed include a flyback, forward, buck, boost, and SEPIC. The set point voltage for the power regulator 320 could be changed depending on how many of the battery cells are being used to power the motor 65. Additionally, the power regulator 320 could be used with the secondary accumulator devices 342 shown in FIG. 13. Further, the forward-reverse switch 316 could be incorporated into the power regulator 320, although it is shown separately in FIG. 17.

[0084] Batteries can typically be modeled as an ideal voltage source and a source resistance. For an ideal model, when the source and load resistance are matched, maximum power is transferred to the load. FIG. 18 shows a typical power curve for a battery. When the battery circuit is open, the voltage across the battery is high (at its open circuit value) and the current drawn from the battery is zero. The power delivered from the battery is zero also. As more current is drawn from the battery, the voltage across the battery decreases. The power delivered by the battery is the product of the current and the voltage. The power reaches its peak around at a voltage level that is less than the open circuit voltage. As shown in FIG. 18, with most battery chemistries there is a sharp drop in the voltage/power at higher current because of the chemistry or positive temperature coefficient (PTC), or because of a battery protection device.

[0085] Particularly for embodiments using a battery (or batteries) to power the motor 65 during a procedure, the control circuit 330 can monitor the output voltage and control the set point of the regulator 320 so that the battery operates on the “left” or power-increasing side of the power curve. If the battery reaches the peak power level, the control circuit 330 can change (e.g., lower) the set point of the regulator so that less total power is being demanded from the battery. The motor 65 would then slow down. In this way, the demand from the power pack would rarely if ever exceed the peak available power so that a power-starving situation during a procedure could be avoided.

[0086] In addition, according to other embodiments, the power drawn from the battery may be optimized in such a way that the chemical reactions within the battery cells would have time to recover, to thereby optimize the current and power available from the battery. In pulsed loads, batteries typically provide more power at the beginning of the pulse that toward the end of the pulse. This is due to several factors, including: (1) the PTC may be changing its resistance during the pulse; (2) the temperature of the battery may be changing; and (3) the electrochemical reaction rate is changing due to electrolyte at the cathode being depleted and the rate of diffusion of the fresh electrolyte limits the reaction rate. According to various embodiments, the control circuit 330 may control the converter 320 so that it draws a lower current from the battery to allow the battery to recover before it is pulsed again.

[0087] As mentioned above, according to various embodiments the battery pack 299 may comprise multiple battery cells 310. FIG. 22 shows an embodiment with six (6) battery cells 310. The battery cells 310 may be, for example, lithium primary batteries. According to various embodiments, the battery pack 299 may have only a fraction of the battery cells internally connected. For example, as shown in FIG. 22, cell 310a is connected to cell 310b, cell 310c is connected to cell 310d, and cell 310e is connected to cell 310f. However, cell 310b is not connected internally in the battery pack to cell 310c, and cell 310d is not connected internally in the battery pack to cell 310e. The handle 6 of the instrument 10 in such embodiments may comprise a battery cell connector 1300 that connects the cells 310 in series only when the battery pack 299 is physically inserted in the instrument 10. For example, the connector 1300 may comprise a positive output terminal 1302, a connector 1304 that series connects cell 310b to cell 310c, a connector 1306 that connects cell 310d to cell 310e, and a negative output terminal 1308.

[0088] FIG. 23 shows an embodiment of the instrument 10 where a replaceable, removable battery pack 299 is installed in the handle 6 of the instrument 10. As shown in FIG. 23, the battery cell connector 1300 may be integrated into the handle 6 such that, when the battery pack 299 is inserted into the handle 6, the battery cell connector 1300 makes the necessary battery cell connections.

[0089] Of course, in other embodiments, battery packs with a different number of internal cells and different numbers of internally connected cells may be used. For example, FIG. 24 shows an embodiment with six cells 310a-f, where two sets of three cells (cells 310a-c and cells 310d-f) are connected together.

[0090] The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application.

[0091] Preferably, the various embodiments of the invention described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a thermoformed plastic shell covered with a sheet of TYVEK. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility.

[0092] It is preferred that the device is sterilized. This can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, steam and other methods.

[0093] While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art. The various embodiments of the present invention represent vast improvements over prior staple methods that require the use of different sizes of staples in a single cartridge to achieve staples that have differing formed (final) heights.

[0094] Accordingly, the present invention has been discussed in terms of endoscopic procedures and apparatus. However, use herein of terms such as “endoscopic” should not be construed to limit the present invention to a surgical stapling and severing instrument for use only in conjunction with an endoscopic tube (i.e., trocar). On the contrary, it is believed that the present invention may find use in any procedure where access is limited, including but not limited to laparoscopic procedures, as well as open procedures. Moreover, the unique and novel aspects of the various staple cartridge embodiments of the present invention may find utility when used in connection with other forms of stapling apparatuses without departing from the spirit and scope of the present invention.