Manually operated stretching apparatus

Information

  • Patent Grant
  • 6634995
  • Patent Number
    6,634,995
  • Date Filed
    Thursday, June 28, 2001
    23 years ago
  • Date Issued
    Tuesday, October 21, 2003
    21 years ago
Abstract
An exercise device for stretching the lower back and leg muscles of a user includes a flexible footrest and a handle device. The handle device is designed to be grasped by the hands of a user and the cable is attached, at one end, to a footrest or fixed location. The other end of the cable is engaged by a rotatable member in the handle device; and a pawl and ratchet mechanism in the handle device rotates the rotatable member to draw the cable member into the device. A reciprocating lever member is operated by the user, grasping the handle member to effect incremental stepwise rotation of the rotatable member through the pawl and ratchet mechanism.
Description




BACKGROUND




Exercise equipment has been designed for developing and maintaining physical fitness through a variety of exercises. Such equipment includes weight lifting machines, rowing machines, stair climbing machines, treadmills, and the like. Such machines, and most exercise regimens, are designed to improve the cardiovascular condition of the persons undertaking the exercise, and to provide muscle building and muscle toning. Fitness centers and home exercise equipment for accomplishing these purposes are in widespread use.




Although muscle building and muscle conditioning are important in developing and maintaining physical fitness, another part of the physical fitness story is developing body flexibility. Simply stated, a flexible body works better. Good posture, decreased stress, relief of muscular and joint pain, substantially improved physical and athletic ability and an enhanced sense of well being all come with improved flexibility. On the other hand, inflexibility, particularly in the lower back and hamstrings, causes low back and hamstring pain and injury.




A large percentage of the adult population in the United States suffers from lower back pain; and improving back flexibility can reduce or eliminate this type of pain. Although the benefits of such flexibility are important and obvious, achieving such flexibility has not been a simple task.




Inactivity and certain exercises, such as bicycle riding and running, cause the hamstring muscles to contract or shorten. Contracting the hamstring muscles then causes the pelvis to become unstable. This in turn tends to throw the spine out of alignment, constricting and pinching nerves, including the sciatica, which can cause moderate to severe pain from the lower back through the upper leg. It has been found that stretching before and after exercise reduces or eliminates the risk of injury from fitness workouts or athletic performance.




To properly stretch, the targeted muscles must be in a relaxed or passive state. Solo stretching the hamstring and other muscle groups creates an inherent conflict of self-generated stretching force interfering with the passive state muscles. While dynamic or ballistic stretching is an option, it is less effective, and it invites injury. Partner or training-assisted stretching also presents problems. Most obviously, another person is required each time the stretching exercise sequence is undertaken. Beyond this, however, it is difficult, even with a trainer, to produce consistent stretching tension.




A device for stretching the back and hamstring muscles of a user without requiring a partner or trainer is disclosed in the U.S. Pat. to Reed No. 5,108,090. This patent is directed to a power stretching device where the user is seated with legs extended. A leg immobilizing unit is provided; and an adjustable extension portion is attached pivotally to a reciprocating telescoping unit. The telescoping unit has hand grips at its upper end for engagement with the hands of the person using the device. A motor controls the reciprocating movement of the telescoping unit to cause it to move toward and away from the person using the device. Consequently, as the handgrips move away from the user toward the pivot, the user is pulled forward into a bending position to effect the desired stretching of the back and leg muscles. Although the device of the Reed Pat. No. 5,108,090 is effective for providing back stretching exercise, the mechanical parts are somewhat complex; and the overall device is relatively large.




Another approach for effecting the stretching of back and hamstring muscles is disclosed in the U.S. Pat. to Reed No. 6,210,348. The device of this patent is directed to an exercise device having a handle member designed to be grasped by the hands of a user. One end of a flexible cable is attached to a fixed position device; and the other end is attached to a rotatable reel in the handle member, which also carries apparatus coupled with the reel for rotating the reel to wind the cable while the handle member is grasped by the hands of a user. In some specific implementations of the device disclosed in the Reed Pat. No. 6,210,348, the rotatable reel is driven by an electric motor mounted within the handle member; and a switch is provided for turning on the motor to rotate the reel at a uniform speed to wind the cable.




It is desirable to provide an improved, hand-held mechanically operated stretching device.




SUMMARY OF THE INVENTION:




It is an object of this invention to provide an improved exercise device.




It is another object of this invention to provide an improved hand-held exercise device.




It is an additional object of this invention to provide an improved compact, easy to use, manually operated stretching apparatus.




It is a further object of this invention to provide an improved manually operated mechanical device for stretching the lower back and hamstring muscle groups.




In accordance with a preferred embodiment of the invention, an exercise device designed to stretch the back and leg muscles of a user includes a handle body having a handle member grasped by the hands of a user. A fixed position member is provided adjacent the location where the device is to be used. A flexible cable is secured at a first end to the fixed position member; and it is engaged by a rotatable member in the handle body. A manually operated pawl and ratchet mechanism in the handle body is used to rotate the rotatable member to draw the cable into the handle device through the operation of a reciprocating lever member coupled with the pawl and ratchet mechanism. Operation by a user reciprocating the handle member effects incremental stepwise rotation of the rotatable member through the pawl and ratchet mechanism to pull the flexible cable into the handle body.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a front perspective view of a portion of the operating mechanism of a preferred embodiment of the invention;





FIG. 2

is a rear perspective view of the operating mechanism shown in

FIG. 1

from the opposite side;





FIG. 3

is an exploded view of a portion of the operating mechanism of a preferred embodiment of the invention;





FIG. 4

is an exploded view of another portion of the operating mechanism of a preferred embodiment of the invention;





FIG. 5

is an exploded perspective view of another portion of the operating mechanism of the preferred embodiment of the invention;





FIGS. 6 and 7

are exploded perspective views of other portions of the operating mechanism of a preferred embodiment of the invention;





FIGS. 8 and 9

are side views of a portion of the mechanism of a preferred embodiment of the invention illustrating features of its operation;





FIG. 10

is an exploded view of a portion of the mechanism of a preferred embodiment of the invention;





FIG. 11

is a cut-away side view of a portion of the operating mechanism of a preferred embodiment of the invention;





FIGS. 12 and 13

are cut-away side views of the opposite sides of the mechanism shown in

FIG. 11

illustrating two different positions of operation of a preferred embodiment of the invention;





FIG. 14

is a diagrammatic illustration of a preferred embodiment of the invention in its storage position;





FIGS. 15

,


16


and


17


illustrate different positions of a user operating the embodiment of the invention disclosed in

FIGS. 1 through 14

; and





FIG. 18

is a diagrammatic illustration of a variation of a feature of the invention as an alternative to the one shown in FIG.


14


.











DETAILED DESCRIPTION




Reference now should be made to the drawings, in which the same or similar reference numbers are used throughout the different figures to designate the same components. Initially, reference should be made to

FIGS. 1

,


2


and


3


; although portions of the mechanism shown in these figures are also illustrated in various ones of the other figures in greater detail. The stretching apparatus of a preferred embodiment of the invention is housed within a handle body including a housing or housing device


20


, which has a hollow interior.




The housing device


20


may be made of a plurality of mating parts to form the internal cavities; or it may be constructed of a pair of clamshell members which are closed around the operating mechanism for the stretching apparatus. Since the housing device


20


may be of any suitable configuration, it is shown only in dotted lines in

FIGS. 1 and 2

; although subsequent figures illustrate the housing device


20


, or various portions of it, in solid lines. It is believed that the perspective views of

FIGS. 1 and 2

, however, are more clearly understood with the housing device


20


merely being indicated in dotted lines showing it in phantom. In

FIGS. 1 and 2

other portions of the exercising device also are shown, at least in part, in dotted lines. These include a pair of right and left handgrips or handlebars


21


and


22


, each secured at one end to the central housing device


20


, each and secured at the other end in a circular aperture in a pair of guide members


23


and


25


, respectively.




The guide member


23


is shown in solid lines in FIG.


1


. As is apparent from an examination of

FIG. 1

, the guide member


23


includes a hollowed out elongated channel


24


between the enlarged end where the handle


21


is secured and its opposite end. A similar channel (not numbered) is present in the guide member


25


.




The basic user activated operating element of the exercise device comprises an elongated handle member in the form of a rod which extends from the channel


24


in the guide member


23


to the corresponding channel in the guide member


25


, as shown clearly in

FIGS. 1

,


2


and


3


. The rod


26


is designed to be engaged by the right and left thumbs of the user, with the fingers of the right and left hands engaging the handgrips


21


and


22


, respectively. The operating rod


26


is spring biased away from the handgrips


21


and


22


by springs (not shown); so that in the rest position of the device, the rod


26


is located near or at the right-hand end (as shown in

FIG. 1

) of the channel


24


and the corresponding channel in the member


25


.




The distance between the rod


26


and the handgrips


21


and


22


is relatively short, on the order of 2½″ to 4″. This permits reciprocal movement of the


26


rod back-and-forth, in the direction of the arrows shown in

FIG. 1

, in the channels in the members


23


and


25


, and in a corresponding elongated channel or slot


30


through the main housing


20


. The slot


30


in the main housing


20


is illustrated most clearly in

FIGS. 8 through 13

; although various others of the figures also show the slot


30


in its location relative to other portions of the exercise device.




In operating the exercise device, reciprocal movement of the rod


26


back-and-forth in the channels, such at the channel


24


, is used to push and pull an elongated rack gear


36


mounted in a bracket


32


, which is attached to the housing


20


. The rack gear


36


moves back-and-forth with its power or operating stroke occurring when it is driven from the end of the channel


24


toward the handgrips


21


and


22


, as illustrated in FIG.


1


.

FIG. 1

shows the position of the operating rod


26


in its farthermost position of travel for an operating stroke of the device.




As shown in FIG.


1


and in the exploded view of

FIG. 10

, the rack gear


36


is attached at one end to the center of the operating rod


26


, through a bracket


38


, by means of a pin or rivet which extends through a hole in the end of the rack gear


36


and corresponding upper and lower holes in the bracket


38


. The rack ear


36


then rides on the top of an idler pinion gear


44


, which is carried on a shaft


42


reciprocally mounted in a slot


34


in the ides of the bracket


32


. The slot


34


is slightly longer than the diameter of the shaft


42


to permit the idler pinion gear


44


to move back-and-forth in the slot


34


as the rack gear


36


moves back-and forth under the control of the movement of the operating rod


26


. The location of various ones of these parts are shown in

FIGS. 1

,


8


,


9


and


10


.





FIG. 8

shows the driving or operating position when the thumbs are used to squeeze the operating rod


26


forward toward the handgrips


21


and


22


. When this occurs, the shaft


42


carrying the idler pinion gear


44


rolls toward the left-hand end of the slot


34


(as viewed in

FIGS. 8 and 9

) to cause the gear


44


to engage the outer teeth of a driver pinion gear


50


, as seen most clearly in FIG.


8


. Thus, as the rack


36


moves toward the left, as shown in

FIG. 8

, the idler pinion gear


44


rotates and engages the driver pinion gear


50


to rotate the driver pinion gear counterclockwise as viewed in FIG.


8


. This occurs for each squeezing or driving stroke of the operating rod


26


in the direction of the arrow shown in FIG.


8


.




When the squeezing force between the handgrips


21


and


22


and the rod


26


is released, the spring action from the return springs (not shown) pushes the operating rod


26


toward the right, as viewed in FIG.


9


and as indicated by the arrow pointing toward the right in FIG.


9


. When this occurs, immediately upon the commencement of the rightward motion of the rack gear


36


, the shaft


42


carrying the idler pinion gear


44


is moved toward the right in the slot


34


. This moves the gear


44


out of engagement with the drive pinion


50


; so that rotation of the drive pinion


50


ceases. It is apparent that continued reciprocal or back-and-forth motion of the operating rod


26


between the positions shown in

FIGS. 8 and 9

causes intermittent incremental rotation of the driver pinion


50


for each full cycle of operation of the rod


26


between the position shown in

FIG. 8

to the position shown in

FIG. 9

, and back again to the position shown in FIG.


8


.




The driver pinion gear


50


includes a smaller gear portion


52


located on its right-hand end (as viewed in FIG.


6


). Gears


50


and


52


are part of a gear reduction chain, the remainder of which is effected by means of a ring gear and pinion assembly in which the gear


52


acts as the driving gear for three planetary pinions


64


mounted on the right-hand side of a pulley half


58


(as shown in FIG.


1


), and shown as mounted on the left-hand side of the pulley


58


in the view of FIG.


6


. The planetary pinion gears


62


are mounted on respective shafts


57


, which are secured to the pulley half


58


at equi-angular positions, as shown most clearly in

FIGS. 6 and 11

.




The ring gear portion of the gear reduction assembly comprises a ring gear


59


, which is secured by any suitable means in the housing


20


against rotation. The relative position of the ring gear


59


and the planetary gears


54


, along with the driver


52


, is shown most clearly in

FIG. 11

; although

FIG. 6

illustrates in exploded view the manner in which these various parts fit together. Consequently, each time a reciprocating cycle of the operating bar


26


is effected through the operating strokes described above in conjunction with

FIGS. 8 and 9

, the gear


52


rotates the pulley half


58


through the attached shafts


57


on the planetary gears


64


to effect stepped incremental rotation of the pulley clockwise, in the direction of the center arrows and top arrow shown in FIG.


11


. This causes an incremental stepwise rotation of the right-hand pulley


58


, as viewed in

FIGS. 1 and 2

, for each of these operating cycles.




The left-hand half


60


of the pulley assembly is secured at its center by any suitable means to the right-hand half


58


, as viewed in

FIGS. 1 and 2

; so that the two halves rotate together. The pulleys are mounted for rotation on the common shaft


54


, which is used as part of the gear assembly, as is apparent from an examination of various ones of the figures of the drawing.




On the other side of the assembly, on the reverse side of the pulley half


60


, there is a circular ring ratchet gear


86


mounted for rotation with the pulley half


60


. The pulley half


60


, as well as the pulley half


58


and various ones of the gears which have been described previously, all rotate about a common shaft


54


, as is clearly shown in

FIGS. 1

,


2


,


3


and


8


through


13


. As shown most clearly in

FIG. 12

, four equally spaced pawls


88


(only three of which have been shown in

FIGS. 12 and 13

in order to avoid unnecessary cluttering of the drawing) normally engage the ratchet ring


86


to allow it to rotate in the direction of the arrows shown in

FIG. 12

in the incremental rotations described previously in the operation of the device. Bias springs


92


cause the ends of the pawls to engage the teeth


86


to prevent rotation of the pulley


58


/


60


in the reverse direction (clockwise, as shown in

FIG. 12

) so long as the pawls


88


are allowed to ride on the ratchet teeth


86


in the configuration shown in FIG.


12


.




It should be noted that the pawls are mounted on shafts


90


located substantially near their centers, as is apparent from an examination of the drawings of

FIGS. 12 and 13

. These shafts


90


are secured to the housing


20


in the fixed position shown. The pawls


88


remain in the same position illustrated in

FIGS. 12 and 13

throughout the operation of the device.




A release lever


82


, which extends through an opening in the top of the housing


20


, is provided to allow reverse rotation of the pulley halves


58


and


60


once a particular exercising session has been completed by a user. The release lever


82


is attached to a plate


80


designed to rotate a limited distance about the shaft


54


.




The plate


80


carries four pins


94


which extend under the spring loaded ends of the pawls


88


, as shown in FIG.


12


. When the release lever


82


is moved rightward to the position shown in

FIG. 13

, the pins


94


are rotated clockwise a short distance to cam the pawls


88


out of engagement with the circular ratchet gear


86


, as shown in FIG.


13


. When this occurs, the pulley


58


/


60


no longer is held against reverse rotation. Furthermore, when this occurs with the operating rod


26


in the rightmost position as shown in

FIG. 9

, the reduction gear train is allowed to rotate in the opposite direction to permit withdrawal of the cable


61


, rotating the pulley assembly


58


/


60


in the counterclockwise direction (as viewed in

FIGS. 1 and 11

) for purposes of release and resetting the mechanism.




As illustrated in the various exploded views of the different parts of the apparatus, the different parts of the housing


20


may be secured together by means of threaded fasteners or any other suitable type of fasteners operating in conjunction with spacers


66


and elongated bolts


68


, which thread into mating internally threaded heads


70


, as shown in various ones of the figures, particularly

FIGS. 2

,


3


and


5


.

FIGS. 1 and 2

show a completed assembly of one of these fastener units, several of which are used to hold the different parts of the hollow housing


20


together.




In operation of the device, the flexible cable or rope


61


is passed over the top of the pulley assembly


58


/


60


, which have curved ribs on the facing surfaces, as most clearly shown in

FIGS. 1

,


2


and


6


, to pull the cable or rope


61


toward the right as viewed in

FIG. 3

upon each incremental operation of the device in the manner described above. The cable


61


passes through an upper opening formed by the mating faces


101


A and


100


B of the parts of the housing


20


, as shown in

FIGS. 4 and 5

, to pass over the top of the pulley


58


/


60


and then outwardly through the lower openings


102


A and


102


B formed when the two halves of the unit shown in

FIGS. 4 and 5

are assembled together to form the compact housing


20


illustrated in others of the drawings. A pulley device of the type formed by the pulley halves


58


/


60


is commonly used in marine applications, and is known as a“come-a-long”. Because of the wedging action of the cable or rope


61


in the narrow portion of the pulley


58


/


60


near the axis at the shaft


54


, the cable


61


is securely gripped and pulled toward the right, as viewed in

FIGS. 3 and 6

, to pull it through the pulley


58


/


60


and deposit the free end outwardly from the housing


20


through the slot


102


A/


102


B.





FIGS. 14 and 18

illustrate different configurations of use for the exercise device described above in conjunction with the other FIGS. In

FIG. 14

, the free end of the cable or rope


61


is secured to a ring


101


, which in turn is secured to a base


100


carrying a footrest portion


104


at its right-hand end, as viewed in FIG.


14


. The housing


20


may be placed, in its rest or ready position, in a depression


102


for storing the device. When use of the device is to be made, the release lever


82


is operated to push it to the position shown in

FIG. 13

; and a desired length of cable or rope


61


is extended from the device, as illustrated in FIG.


15


. When a user begins use of the device, the user


120


is in the position shown in FIG.


15


. The lever


82


is released to its return position, as shown in

FIG. 12

, and the handgrips


21


and


22


are engaged by opposite hands of the user on either side of the central housing


20


. The user


120


relaxes in the position shown in

FIG. 15

, with his or her feet resting against the footrest


104


. Successive squeezing action to form the reciprocal movement of the operating rod


26


then is effected by the user squeezing his or thumbs toward the handgrips


21


and


22


in the sequence described above in conjunction with

FIGS. 8 and 9

to incrementally draw the cable


61


through the housing


20


to pull the user


120


progressively into the positions shown in

FIGS. 16 and 17

.






17


illustrates a finishing position for a user who has a very flexible back and leg muscles. At any time, however, the user


120


can stop the operation of the device by ceasing to perform the sequential squeezing and releasing action of the operating rod


26


whenever the maximum stretch for that particular user


120


is reached. It should be noted that the user has absolute control over the speed at which the housing


120


is moved toward the left along the cable


61


by controlling the speed of the successive cycles of operation of the operating rod


26


. Any time the user releases the operating rod


26


or holds it in the position shown in

FIG. 1

, rotation of the pulleys


58


/


60


ceases; and the position may be held.




It should be noted that the exercise device shown in the drawings, and which is described above, provides its most effective muscle stretching conditioning with users who are as relaxed as possible, and who allow the pull on the cable or rope


61


to move the housing


20


toward the left (as viewed in

FIGS. 15 through 17

) to accomplish all of the“work”. It has been found that a very few 30 second or 60 second stretches on the same day can improve the stretching reach of most persons by


8


″ or more, the average shortfall for most persons to touching their toes.





FIG. 18

illustrates an alternative anchor or attachment of the fixed end or left-hand end of the cable


61


. In the arrangement shown in

FIG. 18

, the device is attached to a bracket


112


, which in turn is attached to a wall


110


. An attaching ring


114


, which is similar to the ring


101


, is secured to the bracket


112


for holding the fixed end of the rope or cable


61


in the same manner described above for the attachment to the ring


101


in the embodiment of




FIG.


14


. In all other respects, the operation and use of the device is identical to that which has been described above for the embodiment shown in FIG.


14


.




The foregoing description of the preferred embodiment of the invention is to be considered as illustrative and not as limiting. Various changes and modifications will occur to those skilled in the art for performing substantially the same function, in substantially the same way, to achieve substantially the same result, without departing from the true scope of the invention as defined in the appended claims.



Claims
  • 1. An exercise device for stretching the back, neck and leg muscles of a user including in combination:a handle body, having a handle member designed to be grasped by the hands of a user; a fixed position member; a flexible cable with first and second ends, secured at the first end to the fixed position member and engaged by a rotatable member in the handle body; a pawl and ratchet mechanism in the handle body for rotating the rotatable member to draw the flexible cable member into the handle body; and a reciprocating lever member coupled with the pawl and ratchet mechanism and operated by a user reciprocating the handle member relative to the handle body to effect incremental stepwise rotation of the rotatable member through the pawl and ratchet mechanism.
  • 2. The exercise device according to claim 1 wherein the flexible cable is engaged intermediate the first and second ends thereof by the rotatable member in the handle body.
  • 3. The exercise device according to claim 2 wherein the handle member comprises an elongated bar mounted for linear reciprocating motion in the handle body and is coupled with the reciprocating lever member to move the reciprocating lever member back-and-forth as the elongated bar is moved back-and-forth in the handle device.
  • 4. The exercise device according to claim 3 wherein the reciprocating lever member translates linear motion to rotational motion for effecting the incremental stepwise rotation of the rotatable member.
  • 5. The exercise device according to claim 4 wherein the reciprocating lever member is a rack-and-pinion drive mechanism.
  • 6. The exercise device according to claim 5 where the rack-and-pinion reciprocating lever member includes a driver pinion, an idler pinion and a rack, with the idler pinion mounted for movement into and out of engagement with the driver pinion and the rack mounted for continuous engagement with the idler pinion, such that the idler pinion is moved by the rack into engagement with the driver pinion when the rack is moved in a first direction and is moved out of engagement with the driver pinion when the rack is moved in a second opposite direction by a user reciprocating the handle member.
  • 7. The exercise device according to claim 6 further including a manually operated release mechanism for releasing the pawl and ratchet mechanism to permit the cable to be withdrawn from the handle body.
  • 8. The exercise device according to claim 7 wherein the fixed position member includes a footrest portion for abutting the feet of a user of the exercise device.
  • 9. The exercise device according to claim 1 wherein the reciprocating lever member translates linear motion to rotational motion for effecting the incremental stepwise rotation of the rotatable member.
  • 10. The exercise device according to claim 9 wherein the reciprocating lever member is a rack-and-pinion drive mechanism.
  • 11. The exercise device according to claim 10 where the rack-and-pinion reciprocating lever member includes a driver pinion, an idler pinion and a rack, with the idler pinion mounted for movement into and out of engagement with the driver pinion and the rack mounted for continuous engagement with the idler pinion, such that the idler pinion is moved by the rack into engagement with the driver pinion when the rack is moved in a first direction and is moved out of engagement with the driver pinion when the rack is moved in a second opposite direction by a user reciprocating the handle member.
  • 12. The exercise device according to claim 11 further including a manually operated release mechanism for releasing the pawl and ratchet mechanism to permit the cable to be withdrawn from the handle body.
  • 13. The exercise device according to claim 1 wherein the handle member comprises an elongated bar mounted for linear reciprocating motion in the handle body and is coupled with the reciprocating lever member to move the reciprocating lever member back-and-forth as the elongated bar is moved back-and-forth in the handle device.
  • 14. The exercise device according to claim 1 wherein the fixed position member includes a footrest portion for abutting the feet of a user of the exercise device.
  • 15. The exercise device according to claim 1 further including a manually operated release mechanism for releasing the pawl and ratchet mechanism to permit the cable to be withdrawn from the handle body.
  • 16. The exercise device according to claim 1 wherein the reciprocating lever member is a rack-and-pinion drive mechanism.
  • 17. The exercise device according to claim 16 where the rack-and-pinion reciprocating lever member includes a driver pinion, an idler pinion and a rack, with the idler pinion mounted for movement into and out of engagement with the driver pinion and the rack mounted for continuous engagement with the idler pinion, such that the idler pinion is moved by the rack into engagement with the driver pinion when the rack is moved in a first direction and is moved out of engagement with the driver pinion when the rack is moved in a second opposite direction by a user reciprocating the handle member.
US Referenced Citations (10)
Number Name Date Kind
5067709 Christianson Nov 1991 A
5108090 Reed Apr 1992 A
5421801 Davies Jun 1995 A
5674163 Sennett Oct 1997 A
5863280 Wang Jan 1999 A
5876310 Mackey Mar 1999 A
5938573 Davies Aug 1999 A
6210348 Reed Apr 2001 B1
6368259 Liao Apr 2002 B1
6544152 Rosati Apr 2003 B2