Wheel mounting assembly and wheelchair therewith

Information

  • Patent Grant
  • 6273445
  • Patent Number
    6,273,445
  • Date Filed
    Monday, June 14, 1999
    25 years ago
  • Date Issued
    Tuesday, August 14, 2001
    23 years ago
Abstract
An apparatus for joining an axle tube to a wheelchair frame includes a body coupled to the wheelchair frame by a coupling. An opening in the outer surface of the body is shaped and dimensioned to receive a projection on the axle tube to form a joint between the axle tube and the body. Alternatively, a joint may be formed by an opening in the outer surface of the axle that is shaped and dimensioned to receive a projection on the body. A wheelchair having a pair of spaced side frames has a body coupled to each of the side frames. An opening in the outer surface of each body is shaped and dimensioned to receive a projection on an axle tube to form a joint between the axle tube and each body. A pair of wheels each has an axle received by the axle tube.
Description




BACKGROUND




Wheelchairs are typically relatively small, single-person conveyances that generally comprise a seat supported by side frames. The side frames are usually supported on a supporting surface by opposing front and rear wheels. The rear wheels may be supported by an axle that is engageable with a laterally extending axle tube. The axle tube may span between and traverse the opposing side frames. The ends of the axle tube may be attached to the side frames by a double clamp configuration. A suitable double clamp configuration typically includes a frame clamp and an axle tube clamp vertically spaced from the frame clamp. The frame clamp usually extends in a direction substantially perpendicular relative to a direction in which the axle tube clamp extends. The frame clamp generally comprises two components, which are attachable to one another. The axle tube clamp generally comprises a third component, which is attachable to one of the frame clamp components.




What is needed is a wheel mounting assembly which requires fewer components, and thus, is lighter and consumes less material, and hence, is more cost effective.




SUMMARY




The invention is directed to a wheel mounting assembly that satisfies the foregoing needs as well as other needs. The wheel mounting assembly includes a body coupled to the wheelchair frame by a coupling. An opening in the outer surface of the body is shaped and dimensioned to receive a projection on the axle tube to form a joint between the axle tube and the body. Alternatively, a joint may be formed by an opening in the outer surface of the axle tube that is shaped and dimensioned to receive a projection on the body. The invention is also directed to a wheelchair having a pair of spaced side frames and a body coupled to each of the side frames. An opening in the outer surface of each body is shaped and dimensioned to receive a projection on an axle tube to form a joint between the axle tube and each body. Each wheel of a pair of wheels has an axle received by the axle tube.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a front and right side perspective view of a wheel mounting assembly according to one embodiment of the invention and a wheelchair with front wheels shown in hidden line and rear wheels shown in phantom line.





FIG. 2

is an enlarged front and right side perspective view of the wheel mounting assembly shown in FIG.


1


and wheelchair side frames partially shown in phantom line.





FIG. 3

is a side elevational view of the wheel mounting assembly shown in

FIG. 1 and a

portion of a wheelchair side frame shown in full and holes and fasteners shown in hidden line.





FIG. 4

is an exploded partial front and right side perspective view of the wheel mounting assembly shown in FIG.


1


and an axle tube.





FIG. 5

is a partially exploded partial front and right side perspective view of another embodiment of the wheel mounting assembly.





FIG. 6

is a partially exploded partial front and right side perspective view of another embodiment of the wheel mounting assembly.





FIG. 7

is a partially exploded partial front and right side perspective view of another embodiment of the wheel mounting assembly.





FIG. 8

is a partially exploded partial front and right side perspective view of another embodiment of the wheel mounting assembly.











DESCRIPTION




Referring now to the drawings, there is illustrated in

FIG. 1

a wheelchair


110


comprising wheelchair frame


111


including a pair of laterally spaced, longitudinally extending side frames


112


A and


112


B. “Longitudinally extending” in this context means that the side frames


112


A and


112


B are placed or running substantially lengthwise. The term “substantially” in this context and elsewhere throughout this description, and the claims that follow, may be broadly interpreted to mean exactly or something less than exactly. The term “lengthwise” is in reference to the length of the wheelchair


110


or the measurement of the extent of the wheelchair


110


along its greatest dimension, that is, from the front of the wheelchair


110


to the rear of the wheelchair


110


. The side frames


112


A and


112


B are supported on a supporting surface S by front wheels


114


A and


114


B (shown in hidden line) and rear wheels


116


A and


116


B (shown in phantom line). A laterally extending, substantially horizontally disposed seat panel


118


and a laterally extending, substantially vertically disposed seat back


120


are supported or held in position by the side frames


112


A and


112


B. “Laterally extending” in this context means that the seat panel


118


and the seat back


120


are placed or running in a direction substantially transverse to the longitudinal direction, or from one side of the wheelchair


110


to the other side of the wheelchair


110


. The seat panel


118


and seat back


120


are provided for bearing the weight of the wheelchair occupant (not shown). A footrest


122


may be disposed at the forward end of the wheelchair


110


for bearing the weight of the wheelchair occupant's feet.




Continuing with reference to

FIG. 1

, there is illustrated a mounting assembly for joining wheels to a wheelchair. In particular, there is illustrated a pair of mounting assemblies, generally indicated at


124


, for joining the rear wheels


116


A and


116


B to the laterally spaced side frames


112


A and


112


B of a wheelchair


110


. The rear wheels


116


A and


116


B may include a hub (not shown) at the focal point of the wheels


116


A and


116


B. An axle


126


(shown in hidden line in

FIG. 2

) may extend inward substantially perpendicularly from the focal point of the hub of each wheel


116


A and


116


B. The term “focal point” is in reference to a central point or a point substantially at the center of the wheels


116


A and


116


B and the hub of each wheel


116


A and


116


B.




The axle


126


is coupled to an axle tube


128


. The axle tube


128


may be in the form of a cross tube, such as the axle tube


128


shown, or a camber tube (not shown). Cross tubes generally have a linear axis. The term “linear” in this context is understood to mean substantially straight or along a substantially straight line. The axis of the cross tube is understood to be in reference to an imaginary line indicated along the line “A” through the center the cross tube (shown in FIG.


2


). Unlike cross tubes, camber tubes are generally bent so as to support the wheels in a cambered position. The term “camber” is understood to mean a setting of the wheels


116


A and


116


B in which the top of the wheels


116


A and


116


B is closer together than the bottom of the wheels


116


A and


116


B, or vice versa. Cross tubes, unlike camber tubes, may support wheels


116


A and


116


B in a cambered or non-cambered position.




Now referring back to the drawings, there is illustrated an axle tube


128


that is preferably in the form of a generally rigid, elongate, laterally extending substantially cylindrical tube. The term “rigid” in this context means substantially non-flexible or stiff. The term “generally” may be construed liberally to allow for some flexibility in the axle tube


128


. The term “elongate” is understood to mean having a length greater than its width. The axle tube


128


has a substantially cylindrical outer surface


136


. The outer surface


136


is substantially cylindrical because the axle tube


128


shown is a substantially cylindrical tube. However, it should be understood that the geometry or surface shape or the physical arrangement of the axle tube


128


need not be cylindrical and that axle tubes having other shapes and forms may fall within the scope of the invention. The axle tube


128


may be a single tube having opposing ends, generally indicated at


132


and


134


, as shown. A single axle tube may extend between and traverse the side frames


112


A and


112


B with the opposing ends


132


and


134


coupled or joined to the side frames


112


A and


112


B. Alternatively, each axle


126


(shown in hidden line in

FIG. 2

) may be supported by a separate axle tube (not shown) coupled to each side frame


112


A and


112


B. Although the axle tube


128


is coupled to the side frames


112


A and


112


B, it should be clearly understood that the term “side frame” may be broadly interpreted to generally mean the wheelchair frame


111


. Hence, the axle tube


128


may be coupled to any portion of the wheelchair frame


111


.




One manner in which the axle tube


128


may be joined to the side frames


112


A and


112


B is best understood with reference to

FIGS. 2 through 4

. Each end


132


and


134


of axle tube


128


, or in the case where separate axle tubes (not shown) are employed, each axle tube, may be joined to a respective side frame


112


A and


112


B in a similar manner. Hence, to simplify the description, the remaining portion of the description that follows will be directed toward a mounting assembly for joining one end


132


of the axle tube


128


to a corresponding or respective one of the side frames


112


A. It should be clearly understood that the opposing end


134


of the axle tube


128


may be joined to the other side frame


112


B with a similar mounting assembly.




Continuing with reference to the drawings, there is illustrated a projection


138


on the axle tube


128


. “Projection” may be broadly interpreted to mean a thing or part that extends outward beyond a prevailing surface of the axle tube


128


. A projection according to the invention preferably extends about a portion of the axle tube


128


and not entirely about the axle tube


128


. The projection


138


may be in the form of a tongue or a protruding strip, such as the projection


138


C shown in

FIG. 8

, along the outer surface


136


C of the axle tube


128


C. The projection


138


is most preferably in the form of a tenon, such as the rigid, laterally extending tenon shown. It is also preferable that the projection


138


be in the shape of a dovetail. The shape of the projection


138


shown characterizes a dovetail shape. However, projections of other shapes may fall within the scope of the invention. The projection


138


preferably extends from one end


132


of the axle tube


128


to the other end


134


of the axle tube


128


. However, a separate projection on each of the opposing ends


132


and


134


of the axle tube


128


may be sufficient for carrying out the invention. An example of one such projection is shown


138


B is shown in FIG.


7


. In other words, the projection


138


need not extend entirely between the opposing ends


132


and


134


but rather may be discontinued between the opposing ends


132


and


134


so that the projection


138


is not on the axle tube


128


between the side frames


112


A and


112


B. In the event that separate axle tubes (not shown) are employed, a projection


138


may be on each axle tube. This should become more apparent in the description that follows, as it will become clear that a projection


138


need only be provided adjacent the side frames


112


A and


112


B. The term “adjacent” may be broadly interpreted to mean close or next to the side frames


112


A and


112


B. An advantage of having a projection


138


on the axle tube


128


that extends substantially without interruption between the opposing ends


132


and


134


of the axle tube


128


is that the mounting assembly


124


may readily join the axle tube


128


to the side frames


112


A and


112


B spaced various distances.




The projection


138


is preferably engageable with an opening


140


. The opening


140


is preferably shaped and dimensioned to receive the projection


138


to form a joint, generally indicated at


142


in

FIGS. 2 and 3

whereby the axle tube cannot rotate relative to said body. For example, the projection


138


may be in the form of a tongue and the opening


140


may be in the form of a matching groove. The term “matching” in this context may be broadly interpreted to mean that the projection


138


and the opening


140


fit together or may be caused to fit together. An example of an opening


140


C in the form of a matching groove is shown in FIG.


8


. It is most preferable that the opening


140


be in the form of a mortise that is shaped and dimensioned to receive a tenon. The term “mortise” is intended to broadly define a captive opening or an opening that is shaped and dimensioned to trap or capture the projection


138


. For example, the opening


140


may be in the shape of a dovetail to receive a dovetail shaped projection


138


. A dovetail shaped opening


140


is characterized by the opening


140


shown in the drawings. The dovetail shaped projection


138


may be received in the dovetail shaped opening


140


by sliding the projection


138


into the opening


140


, such as in a direction along the direction of the arrow B. Once in the opening


140


, the projection


138


is captured or prevented from escaping from the opening


140


in a direction transverse to the direction of the arrow B.




Although a dovetail shaped projection


138


and opening


140


are preferred, it should be understood that other shaped projections and openings may fall within the scope of the invention. An example of an alternatively shaped projection


138


A is shown in

FIG. 6

along the outer surface


136


A of the axle tube


128


A. This projection


138


A is a T-shaped projection. Another alternatively shaped projection


138


B is shown in

FIG. 7

along the outer surface


136


B of the axle tube


128


B. This projection


138


B is an L-shaped projection. Alternatively shaped openings


140


A and


140


B, such as the T-shaped and L-shaped openings shown, may be provided for receiving these projections


138


A and


138


B.




Each side frame


112


A and


112


B supports an opening, generally indicated at


140


, as is more clearly shown in FIG.


4


. The manner in which each side frame


112


A and


112


B supports an opening


140


may be substantially the same. Hence, as stated above, the following description will be directed toward one of the side frames


112


A and a manner in which an opening


140


may be supported by that side frame


112


A. The side frame


112


A may support the opening


140


in a number of ways. For example, a main or central part (hereinafter referred to as a body, generally indicated at


144


) may define the opening


140


and the body


144


may be coupled to the side frame


112


A. The body


144


preferably has an outer surface


146


and the opening


140


is preferably in the outer surface


146


. The body


144


may be defined by a support having a seat


148


, as is clearly shown in

FIG. 4

, upon which the axle tube


128


may rest. The term “support” in this context is in reference to substantially any structure capable of bearing the weight of the axle tube


128


or holding the axle tube


128


in position so as to keep the axle tube


128


from falling. It should be clearly understood that the axle tube


128


may be positioned above or below the side frame


112


A. The body


144


is most preferably in the form of a rigid, rectangular shaped base. The term “base” in this context is in reference to the body


144


being substantially the lowest or bottom part or the basic underlying element of the mounting assembly


124


. The body


144


preferably has an upper end, generally indicated at


150


, and a lower end, generally indicated at


152


. A carriage, generally indicated at


130


, as is clearly shown in

FIG. 4

, may be formed by the upper end


150


of the body


144


. The term “carriage” may be broadly interpreted to mean a movable part for holding or shifting the location of the axle tube


128


.




The mounting assembly may include a retainer, generally indicated at


170


, as shown in FIG.


4


. The term “retainer” may be broadly interpreted as a device that restrains or holds the axle tube


128


in a particular place or position. The retainer


170


most preferably holds the axle tube


128


in a position relative to the body


144


so that the axle tube


128


is prevented from moving laterally relative to the body


144


. The retainer


170


may be in many forms in the direction of the arrow B or in a direction opposite to the direction of the arrow B. The retainer


170


may include a setscrew


172


that may be threadably engageable with a hole


174


in the body


144


. The hole


174


in the body


144


may coalign with a portion of the axle tube


128


or a portion of the projection


138


. The setscrew


172


may be threaded into the hole


174


to contact the axle tube


128


or the projection


138


to hold the axle tube


128


or projection


138


in place. It should be understood that the retainer


170


shown is provided for illustrative purposes and that other retainers may fall within the scope of the invention.




It should be clearly understood that the body


144


may be joined to the side frame


112


A so as to permit the side frame


112


A to support the opening


140


. This may be accomplished in a number of ways. One manner in which the body


144


may be joined to the side frame


112


A is set forth as follows. The lower end


152


of the body


144


may define an upper clamp part


154


having a saddle, generally indicated at


156


, shaped and dimensioned to receive a portion of the wheelchair side frame


112


A. A lower clamp part


158


may be removably attachable to the upper clamp part


154


to form a clamp, indicated generally at


160


, as shown in

FIGS. 2 and 3

. The term “removably” in this context is intended to be broadly interpreted to mean that the lower clamp part


158


can be readily removed from the upper clamp part


154


, with or without the aid of tools (not shown). The term “readily” may be interpreted liberally to mean promptly or in a prompt, timely manner or in manner indicating or connoting ease. The lower clamp part


158


may similarly have a saddle, generally indicated at


162


, shaped and dimensioned to receive a portion of the wheelchair side frame


112


A. The term “saddle” may be understood to mean a support shaped to fit the wheelchair side frame


112


A. For example, the upper and lower clamp parts


154


and


158


may have semi-cylindrical saddles, as shown in the drawings, that, when attached together, form a cylindrical support shaped to fit a cylindrical portion of the side frame


112


A. The clamp


160


is adjustable for bracing the body


144


to the wheelchair side frame


112


A. This may be accomplished by inserting threaded fasteners


164


(shown in hidden line in FIG.


3


), such as a hex cap screw, into holes


166


(shown in hidden line in

FIG. 3

) in the lower clamp part


158


and threading the fasteners


164


into coaligning, internally threaded holes


168


(also shown in hidden line in

FIG. 3

) in the body


144


. Although only one clamp


160


is described above, it should be clearly understood that a pair of clamps


160


may be used to couple a pair of bodies


144


to the opposing wheelchair side frames


112


A and


112


B.




It should also be understood that the invention is not intended to be limited to include a coupling, such as the clamp


160


shown. Any of various devices with opposing, adjustable sides or parts may be used for bracing the body


144


to the side frame


112


A and holding the body


144


and the side frame


112


A together. It should further be understood that the invention is not limited to the clamp


160


described above and that other couplings may be suitable for coupling the body


144


to the wheelchair side frame


112


A.




It should further be understood that the mounting assembly may comprise an opening, generally indicated at


176


, defined by an axle tube


178


and a projection


180


on the side frame


112


A, as is shown in FIG.


5


. The opening


176


on the axle tube


178


may likewise be shaped and dimensioned to receive the projection


180


on the side frame


112


A. The projection


180


may be in the form of a tongue or a dovetail shaped tenon and the opening


176


may respectively be in the form of a matching groove or a mortise having a mating dovetail shape.




It should be understood that the projection


180


may be directly on the side frame


112


A or may be on a body


182


that may be joined to the side frame


112


A. For example, the projection


180


may be on the outer surface


184


of the body


182


. The body


182


may in turn be joined to the side frame


112


A. The term “body” in this context is not limited to the body


182


shown in the drawings but rather may include any part suitable for supporting the projection


180


. Moreover, the projection


180


may be affixed directly to the side frame


112


A, such as by welding, or may be formed, shaped or molded on the side frame


112


A or as a part of the structure forming the side frame


112


A.




There is an advantage in having a projection


180


on a body separate and apart from the side frame


122


A. The position of the body


182


may be adjusted relative to the side frame


112


A. This may be accomplished by coupling the body


182


to the side frame


112


A by a coupling, such as the coupling


186


shown. The coupling


186


may be similar to the clamp


160


described above, having first and second clamp parts


188


and


190


. The first clamp part


188


may be defined by the lower end (shown but not referenced) of the body


182


. The second clamp part


190


may be removably attachable to the first clamp part


188


in a manner similar to the manner in which the above-described upper and lower clamp parts


154


and


158


are attached. The first and second clamp parts may be adjustable relative to one another for bracing the body


182


to the side frame


112


A. The first and second clamp parts may each further have a saddle


192


and


194


shaped and dimensioned to receive a portion of the side frame


112


A. The saddles


192


and


194


may be similar to the saddles


156


and


162


described above.




In accordance with the provisions of the patent statutes, the principle and mode of operation of the inventions have been explained and illustrated in their preferred embodiments. However, it must be understood that the inventions may be practiced otherwise than as specifically explained and illustrated without departing from their spirit or scope.



Claims
  • 1. A mounting assembly for joining a wheel to a wheelchair frame, comprising:an axle tube having a projection thereon; a body having an opening therein, said opening being shaped and dimensioned to receive said projection to form a joint whereby said axle tube cannot rotate relative to said body; and a coupling for coupling said body to the wheelchair frame.
  • 2. The mounting assembly according to claim 1, wherein said body defines a first clamp part, said first clamp part being removably attachable to a second clamp part to form said coupling, said first and second clamp parts being adjustable relative to one another for adjustably bracing said body to the wheelchair frame.
  • 3. The mounting assembly according to claim 2, wherein said first and second clamp parts each have a saddle shaped and dimensioned to receive a portion of the wheelchair frame.
  • 4. The mounting assembly according to claim 1, wherein said projection is a tongue and said opening is a matching groove.
  • 5. The mounting assembly according to claim 1, wherein said body is defined by a support having a seat upon which said axle tube may rest.
  • 6. The mounting assembly according to claim 5, wherein said support defines a first clamp part, said first clamp part being removably attachable to a second clamp part, said first and second clamp parts being adjustable relative to one another for bracing said support to the wheelchair frame.
  • 7. The mounting assembly according to claim 6, wherein said first and second clamp parts each have a saddle shaped and dimensioned to receive a portion of the wheelchair frame.
  • 8. The mounting assembly according to claim 1, wherein said projection is a T-shaped projection and said opening is a matching T-shaped opening.
  • 9. The mounting assembly according to claim 1, wherein said projection is a L-shaped projection and said opening is a matching L-shaped opening.
  • 10. The mounting assembly according to claim 4, wherein said tongue is a rectangular-shaped tongue and said groove is a matching rectangular-shaped groove.
  • 11. An apparatus for joining an axle tube to a wheelchair frame, comprising:a tube having a projection thereon, said projection being a rigid, laterally extending tenon; a body having an outer surface and an opening in said outer surface, said opening being shaped and dimensioned to receive said projection to form a joint, said opening further being a mortise, said tenon and said mortise being in the shape of a dovetail; and a coupling for coupling said body to a wheelchair frame.
  • 12. The apparatus according to claim 11, wherein said body is defined by a base having an upper end and a lower end, said upper end forming a carriage having a seat upon which the axle tube may rest, said mortise being in said upper end of said base.
  • 13. The apparatus according to claim 12, wherein said base defines a first clamp part, said first clamp part being removably attachable to a second clamp part, said first and second clamp parts being adjustable relative to one another for bracing said base to the wheelchair side frame.
  • 14. The apparatus according to claim 12, wherein said first and second clamp parts each have a saddle shaped and dimensioned to receive a portion of the wheelchair frame.
  • 15. The apparatus according to claim 13, wherein said base is rigid and rectangular in shape.
  • 16. A mounting assembly for joining an axle tube to a wheelchair frame, comprising:a body having an outer surface and a projection on said outer surface; an axle tube defining an opening, said opening being shaped and dimensioned to receive said projection to form a joint whereby said axle tube cannot rotate relative to said body; and a coupling for coupling said body to the wheelchair frame.
  • 17. The mounting assembly according to claim 16, wherein said body defines a first clamp part, said first clamp part being removably attachable to a second clamp part, said first and second clamp parts being adjustable relative to one another for bracing said body to the wheelchair frame.
  • 18. The apparatus according to claim 17, wherein said first and second clamp parts each have a saddle shaped and dimensioned to receive a portion of the wheelchair frame.
  • 19. The mounting assembly according to claim 16, wherein said projection is a tongue and said opening is a matching groove.
  • 20. The mounting assembly according to claim 19, wherein said tongue is a rectangular-shaped tongue and said groove is a matching rectangular-shaped groove.
  • 21. An apparatus for joining an axle tube to a wheelchair frame, comprising:a body having an outer surface and a projection on said outer surface, said projection being a rigid, laterally extending tenon; a tube defining an opening, said opening being shaped and dimensioned to receive said projection to form a joint, said opening further being a mortise, said tenon and said mortise having mating dovetail shapes; and a coupling for coupling said body to a wheelchair frame.
  • 22. A mounting assembly for joining a wheel to a wheelchair frame, comprising:an axle tube having an outer surface and a tongue on said outer surface of said axle tube; a support having a seat upon which said axle tube may rest and a groove shaped and dimensioned to receive said tongue to form a joint between said axle tube and said support, said support defining a first clamp part; and a second clamp part being removably attachable to said first clamp part so as to form a clamp, said first and second clamp parts each having a saddle shaped and dimensioned to receive a portion of the wheelchair frame, said clamp being adjustable relative to the wheelchair frame.
  • 23. An apparatus for joining wheels to a wheelchair having laterally spaced side frames, said apparatus comprising:a rigid, elongate, laterally extending, cylindrical axle tube having opposite ends and an outer cylindrical surface; a rigid, laterally extending tenon on said outer cylindrical surface of said axle tube, said tenon extending from one said end of said axle tube to the other said end of said axle tube, said tenon having a dovetail shape; a pair of rigid, rectangular shaped bases, each said base having an upper end and a lower end, said upper end of each said base forming a carriage having a seat upon which said axle tube may rest and a mortise shaped and dimensioned to receive said tenon to form a joint between said axle tube and each said base, said lower end of each said base defining an upper clamp part having a saddle shaped and dimensioned to receive a portion of a respective one of the wheelchair side frames; and a pair of lower clamp parts, each said lower clamp part having a saddle shaped and dimensioned to receive a portion of a respective one of the wheelchair side frames, each said lower clamp part being removably attachable to said upper clamp part of a respective one of said bases so as to form a pair of clamps, each said clamp being adjustable for bracing each said base to a respective one of the wheelchair side frames.
  • 24. A wheelchair comprising:a frame; an axle tube; a projection on said axle tube, said projection extending about a portion of said axle tube and not entirely about said axle tube; a body coupled to said frame, said body having an outer surface and an opening in said outer surface supported by said frame, said opening being shaped and dimensioned to receive said projection to form a joint between said axle tube and said body.
  • 25. A mounting assembly for joining wheels to a wheelchair frame, comprising:an axle tube having opposite ends; a body adapted to be supported by the wheelchair frame; a projection on said axle tube, said projection extending from one said end of said axle tube to the other said end of said axle tube; and an opening in said body, said opening being shaped and dimensioned to receive said projection to form a joint.
US Referenced Citations (4)
Number Name Date Kind
5409247 Robertson et al. Apr 1995
5593173 Williamson Jan 1997
5851018 Curran et al. Dec 1998
6027132 Robinson et al. Feb 2000