US2561383A

US2561383A - Cosmetic prosthetic hand

Info

Publication number: US2561383A
Application number: US781110A
Authority: US
Inventors: Edward T Larkins; Bernard S Thomas; David R Fetters
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-10-21
Filing date: 1947-10-21
Publication date: 1951-07-24
Anticipated expiration: 1968-07-24

Description

July 24s 31951 T. www@ HAL @95629333 COSMETIC PROSTHETIC HAND Filed OCT.. 2l, 1947 3 Sheets-Shet l Juy 24%? E951 E. T. LARKANS ET AL 255515383 cosMETIc PROSTHETIC HAND Filed oct. 21, 1947 s sheets-sheet :s

Patented July 24, 1951 COSMETIC PROSTHETIC HAND Edward T. Larkins, Daytona Beach, Fla., Bernard S. Thomas, Washington, D. C., and David R.

Fetters, Hyattsville, Md.

Application October 21, 1947, Serial No. 781,111)

12 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 G. 757) The present invention relates generally to prosthetic devices and more particularly to a self-I closing prosthetic hand mechanism which 'simulates the gripping action of the human hand,

and is adapted to be covered by a cosmetic plastic glove which closely simulates the color, texture, conguration, and appearance of the "human hand.

A difficulty encounted in prosthetic hands of this character heretofore devised has been in combining high utility value with natural appearance. A further difficulty has been in providing a mechanism which is easy to operate and which has a grip of suicient strength for normal use.

In the device of the present invention these difficulties have been substantially obviated in that the mechanism is constructed and arranged to follow closely the skeletal formation and finger movement of the human hand, and, therefore, is particularly adapted for use with the aforementioned cosmetic plastic glove. The mechanism is also especially adapted for use with a shoulder-operated cable mechanism in that the hand mechanism is normally spring-urged toV the closed position, thereby obviating a tedious and continuous pull on the cable while holding objects with the hand. The finger structure of the mechanism is mechanically arranged to provide anti-friction devices at certain of the joints thereof whereby the fingers are moved to an open position by a small pull on the cable, a quality particularly desirable Where it is necessary to grasp and release objects frequently.

An object of the present invention is tol provide a new and improved prosthetic hand mechanism for use with a cosmetic plastic glove.

Another object is to provide a prosthetic hand mechanism which closely simulates the skeletal formation and movement of the human hand.

Still another object is to provide a prosthetic hand mechanism which is operated by a small pulling force.

A further object is to provide a prosthetic hand mechanism in which the finger structure is normally spring-closed.

A still further object is to provide a springclosed prosthetic hand mechanism in which the finger structure is operated throughout the movement thereof by a more nearly uniform pulling; force.

A still further object is to provide a prosthetic hand mechanism which is light in weight, simple in design, and durable in operation.

vStill further objects, advantages, and improve- 2 ments will become apparent from the followin detailed description taken in connection with theaccompanying drawings in which: Fig. 1 is a plan view of the device of the present invention according to a preferred em`I the mechanism taken along line 2-2 Fig. 6 is a sectional View taken along line 6-6 of Fig. 5;

ig. 7 is a sectional view taken along line 1 1 of Fig. 4; and

Fig. 8 is a sectional view takenalong line 8'-8 of Fig. 5.

Referring now to the drawings in which like numerals of reference are employed to indicate like parts throughout the several views,l there is provided a mechanism generally indicated l5 and including a supporting disk Il), Yperforated las at ll to decrease the weight thereof and having a threaded hollow attaching-shank l2 adapted to receive a nut I3. The shank l2 and nut I3 serve to secure the disk lil to a conventional arm boot Ill which may be fastened to thearm stump of' the wearer in any well known manner.

The `mechanism I5 also includes a frame mem-` ber I6 attached to the disk IG by means of a screw Il. A locking pin I8 extends through disk l and into frame member I6, thereby to prevent rotation of the frame member withx respect to the;

disk.

The frame member I6 is for'medwith areduced portion I9 to receive a cam pulley 2|.l A pivot pin 22 is press-fitted into a boref23 I'of portion I9. Pin 22 receives anti-friction bearing 24 of cam pulley 2| which is held against displacement by a screw 25 positioned in one end ofthe pin 22. Cam pulley 2i has secured theretov` an eccentrically mounted pin 26, the purpose which will be hereinafter more fully des'zribec'i.-y The body member I6 is formedl at c me e z 11lwith an angular extension 2l havingacutportion 28 adapted to receive'-a--bearingjcap secured thereto by screws 3| and 32: Exten Sion 21 has a' birfurcated end adapted ft'v'otatably receive a transversely disposed `rodl3 3.-'

Fixedly mounted on rodv 33 andia 'similar-'rod' "34 are four

arched finger bars

35, 35, 31, -'and which- 3 are Shaped to follow the skeletal formation of the human lingers. This construction insures unitary action of the four finger bars about the axis of rod 33. Finger bar 36 has an opening 39 formed therein to accommodate a pin 4l. A bifurcated' linl:I 42. is pivoted o n pin 4l and has one end of a connecting bar 43 pivotally attached thereto as at 44. lihe other end of connecting( bar 43 is pivotally joined to cam pulley 2| by theA aforementioned pin 26.

Fastened as at 40 to the pulley 2l is a cable 45 which passes around a portion ofthe peripheryl of the pulley, through an opening 5l)v inthe disk i0' and continues up the arm of the wearer to the usual shoulder operating mechanism (not shown). It will be apparent that when cable 45 is pulled, pulley 2l is rotated, thereby causing movement of the finger bars to an open or non-gripping, position as the pull on the cable is. transmittedv through pin 26, connecting bar 43, and link 42.

It, further will be@ apparent that any desired opening of thefinger bars may be made. by governing the amountof pull. on the cable 45.

'Ihecampulley is so shaped as to provide. an eiective torque arm which. increases, Fig. 4, as the, pulley isJ rotated and the, tension. of the nger actuating springs is increasedwhereby the nger.. structure is adapted to be operated throughout the movement thereof by a more near-12S(y uniform pull. on the cable.

It, beseen inFig. 4. of the drawings that when the nger structure in the closed position, the pivotal axes. ofthe. pulley, bar, and linkv arein. substantial alignment; thereby providing a substantially7 irreversible lock, that is, the nger structure can. be moved by a pull on cable 45 and cannot readily be moved by a pull on the fingers themselves, thus there is little likelihood of the linger structure inadvertently releasing smal-1 articles heldv thereby.

In order to bring the finger bars to the closed ov. gripping positionand also to provide a strong gripforthe 'finger bars there are provided a pair of springs. 46 mounted4 0n a, Shaft 4l which is. rotatably mounted in complementary halves of a.. bore.- 48.v in; angular extension 21. and bearing cap: 2li. The. shaft llll has formed therein a pair of: transverse slots 49,Y adapted to receive one end of. each ofthe springs 46 respectively. The.

springs, are secured toshaft. 41 by transverse pins 66. An important feature of the device is the reduction of.A friction by providing anti-friction..

thumb bar. over and above thatwhich would. be f applied thereto i-f. the springs. were mounted on shaft 33 with the, same tension in the closed position.y for the:l reason that, by interposing pivotal shaft. 33 between shafts. 34 and, 41, the lever arm of each of springs. 4.6 decreases as the finger structure is opened, whereby the force applied to. the finger structure byv the, springs further. increases asY the linger structure is. progressively opened; The foregoing arrangement has the advantage that the gripping force, between. the thumb bar andthe ringer structure increases asy larger and heavier objects are grasped therebetween.`

Mounted; at one end of the shaft. 4.1 isa toothed ratchetwheel 5.2 which, is engaged by a. paw-l lli 4 53 mounted on shaft 54 rotatably held in complementary halves of the bore 55 in extension 21 and cap 29. The end of shaft 41 is formed as at 56 to receive a key (not shown) for the purpose of adjusting the tension on springs 46.

Secured to the, body member I6v and;v at one side thereof by screws 5-1fand 58 isa thumb bar 594 Which is bent to follow generally the skeletal formation of the human thumb the tip thereof comingtoa point substantially midway of the tips of finger bars 35 and 36 and extending slightly therebeyond. As Will be seen in Fig. 8, theV screw 5,3*v may be used to adjust the thumb bar 59 to the position desired. A purpose of the above arrangementl is to provide a convenient means of preadjusting the position of thumb bar 53 so as to facilitate the gripping of small objects such as pencils, pens, etc. The thumb bar may. be rigidly attached to the frame, in which case angular adjustment of the bar may be effected` by heating. and. bending.

Aeuard platenV is. secured t0 the angular.: ex tension 21. by screw 3l. to: prevent the ratchet mechanism.. and.- Sprihgs: from becoming entangled... in aA glove-or cover 6i.- to be hereinafter` more, fully described..

In order. to provide aprosthetic. handhaving a,

natural appearance the cover or glove 6i isused; with the device of the presen-t invention. rEhe glove, lV is composed, of ailexibleplastic. mate-fV rial` wlfiicl'i` closely simulates; the. color;- textura and. appearance of the human skin. It is.I formed. by a molding process,l the molds being produced by` aprocess in which, a; human. hand is used' toprovide the form and detail thereof.. A glove is, therefore provided. which, has substantially au. the intricate details, of. the. human hand as well,V as.A the ,estheticl character thereof.

The glove 6 I. has a pal- 1n portion 62 which covers;

, the major part of the mechanism t5, a, thumb.

portion 63. which covers the thumbl b ar 5 3, and;

finger portions

6,4, 65,.4 66, and 61 which cover theI finger bars 3,

5L

36, 31 and 38. respectively'. Wrist portion 6.8, is formed witha slit 6 9.- to. fa;- cilitate the application or removal of the glove. slide fastenerv 'Hf is. Provided. t0. close the. slit,-

The glove 6 l.. is formed ofaiiexible semi-elastic plastic material,A in order to. provide; a Covering.; for the mechanism which. appeals tothe esthetic. senses, and, also, accommodates the movement; of the.. mechanism Without undue distortioni of the glove. Inv order to. prevent excessivev wear of the glove 6.|- in service and to QQOperate with the glove in providing an improved griplng medium,A resilient llers 15 formed ofa suitabler material such, for example, as. foam plastic are mounted on the. finger.- bars and; the thumb bar and are disposed respectively within the. lingers.

l and thumb of the. glove.

It. also a. feature ci theihvehtioh that the cam pulley 2i has formed; on the ne-,liphery thereof a radial shoulder 'i3 for contact with thel slrroullder-y 'llion framel i6 in order tol proyide a Stan to prevent excessive opening. 0fV the mecha,-

nism. It is, of course, understood.- thatwhile the. device of the present invention has. beenk shown beibe-y arraneed for attachment, to the right arm, the mechanism and: glove may be made-in f reverseorder for usel with, the left arm.

From the foregoing, it should now be appre- @lated that a. prosthet, hand. mechanism has been provided. whichV the thumb and. finger structure may be formed of a light and strong material. such. for example, as. magnesium whereby v,these partsv may be vprovided with4 sufficient strength to retain their initial hand simulating characteristics notwithstanding a Wide diversity A of use and to avoid permanent strains and distortion resulting from accidental bending of the parts in service, while at the same time providing a skeletal hand structure of light Weight and precise mechanical movement.

Whereas a preferred embodiment of the invention has been disclosed in particularity herein which gives satisfactory results, it will be apparent that additional embodiments and modifications thereof may Voccur to those skilled in the art without departing from the spirit and scope as defined by the appended claims.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor.

What isl claimed as new and desired to be secured by Letters Patent of the United States is: l l. A mechanism for a prosthetic hand, comprising the combination of a frame member, a thumb bar attached to said frame member, a finger structure mounted for pivotal movement on said frame member, yieldable means for urgin'g said finger structure toward said thumb bar, said yieldable means increasing in tension as the finger structure is moved away from the thumb bar, link members attached together and to said finger structure, a cam pulley mounted for rotation on said frame, and a cable passed around the pulley and secured thereto for coaction therewith, said pulley having an eccentric pin for operative connection with the terminal one of said link members and being cam shaped in such a manner as to increase the leverage of the cable thereon as the tension of said yieldable means increases during the movement ofthe linger structure away from the thumb bar thereby to provide a more nearly uniform tension on the cable throughout said movement of the finger structure.

2. A prosthetic hand mechanism, comprising i the combination of a frame, a thumb bar flxedly attached tosaid frame, a linger structure mounted for pivotal movement on said frame, spring means for yieldably urging said finger structure v toward said thumb bar, said spring means increasing in tension as the finger structure is moved away from the thumb bar, a cable operated cam-shaped pulley rotatably supported on said frame and link means interconnecting the pulley and the finger structure for moving the finger structure away from the thumb bar as the pulley is rotated by a pull on the cable whereby the leverage of the cable thereon is increased during movement ofthe finger structure away from said thumb bar and a simulation of themovement of the human fingers is provided by a more'nearly uniform tension in the cable.

tensimV respectively for maintaining said shaft@` in la set position thereby to vary the initial tension on said pair of springs, and means. including a. cable operated pulley having a peripheral cam surface thereon in engagement with the cable for moving the finger structure away from the thumb bar and concurrently therewith increasing the leverage of the cable with respect to the pulley in response to tension applied to thel cable. l

, 4. A prosthetic hand mechanism adapted to be covered by a cosmetic plastic glove, comprising, in combination, a frame member having an angular extension, a thumb bar attached to said frame member and disposed within the thumb of the glove, a unitary finger structure pivotally mounted on said angular extension and adapted to be moved from a closed position to an open position with relation to said thumb bar, the

lingers of said nger structure being disposed,

within. the fingers of the glove, spring means for normally maintaining the finger structure in the closed position, said spring means increasing in tension as the finger structure is moved to said open position, means supported on said frame member and including a cable operatedcamshaped pulley and a link connection between the pulley and the linger structure for moving the finger structure to the open position as the pulley is rotated by a pull on the cable, said pulley having a cam-shaped periphery for increasing the effective leverage of the cable thereon as the tension in said spring means increases thereby to provide a more nearly uniform pull on the cable and simulation of movement of the human hand.

5. In a prosthetic hand mechanism adapted to be covered by a cosmetic plastic glove, the combination of a frame member having an angular extension thereon, a thumb bar attached to` said frame member, a linger structure mounted for pivotal movement on said angular extension and adapted to be moved with relation to said thumb bar, spring means for normally maintaining said 'linger structure adjacent the thumb bar, ratchet means operatively connected to said spring means for varying the tension of said spring means, a cable, and means including apulley for coaction with said cable and a link connection between the pulley and the finger structure for providing an irreversible lock for the linger structure when in adjacency with the thumb bar and for movingthe finger structure away from the thumb bar against the opposing force of said spring means` when aI sufficient pulling force is exerted onthe Cable. 5

6. A mechanism for a cosmetic prosthetic,l

ture away from the thumb bar, means including a cam-shaped pulley rotatably supported on the frame, a cable secured to the pulley and passed over a peripheral portion thereof for coactionV therewith and a link connection between the pulley and the'iinger structure for moving the finger structure with relation to the thumb bar and in opposition to the tension ofl said springs when the cable is pulled, said peripheral por- ,tion ofthe pulley being cam shaped to increase aten-fees the ei-ective leverage yof the 'cable on 'the :pulley as the tension in `said springs ,increases in :ree sponse to said movement of the .nger structure, and means including a ratchet and pawl mechanism operatively connected to said plurality of springs and adjustable at will for Ivarying the tension of the springs in accordance with the degree lof :gripping force desired between the finger structure and the thumb bar.

'7. A .prosthetic Ihand mechanism Vfor use with a glove :simulating lthe color, texture, fand contour of .the Ihuman hand, .comprising the combination of aiframe member, a thumb barmounted on said frame member' and disposed within the thumb of the glove, :a ringer Ymechanism mounted for pivotal .movement `on said frame 'member and having fingers respectively disposed within the fingers 'of the glove, means .including an adjust-- ing screw for moving 'the thumb bar laterally withv relation .to a pair of said .lingers of the finger mechanism, spring Ameansfor yieldably and normally maintaining said -linger mechanism adjacent said thumb bar, said spring 'means in' creasing in tension during movement of the :fin` ger mechanism away from the thumb bar., and means including a fcable .and a cam-shaped coacting .pulley having said Icable wrapped thereon for .moving the vfing-er mechanism away .from the thumb bar, said pulley being cam shaped to provide an increasing lever action of the cable on the 'pulley as the ltension of the spring means increases thereby to operate the linger mechanism throughout said movement thereof in response to a more nearly uniform tension applied to the cable.

8. In a cosmetic prosthetic hand, the combination with a vresilient plastic glove 'of a mechanized :skeletal thumb and nger structure disposed therewi'thinand comprising a frame membei' having an angular extension, ringer bars simulating the skeletal formation of human fingers, a'pair of transverse parallel rods for rigidly securing said iinger bars 'in spaced relation simu lating the .fingers oi Ta partially closed human hand, one of said pair of rods being journalled in said angular extension transversely thereof thereby 'to .pivotally support the nger bars as a unit thereon, .a thumb bar simulating the human Ithumb and adjustably secured to said frame member for lateral bending movement with respect 'to said finger bars, the other of said pair of rods having a plurality o'f anti-friction rollers carried thereon, a yshaft journalled in fthe Vang-ulai1 extension transversely thereof and parallel to said pair of rods, a plurality of coil springs secured .to `said shaft and having .arms extending into engagement respectively with said plurality of rollers so as to yieldably urge the finger bars into gripping relation with respect to said thumb bar and to .progressively increase the tension in the 'springs as the finger bars are progressively moved to open position with respect tothe thumb bar, a ratchet wheel carried by the shaft -and a cooperating` pawl carried bythe rangular exe tension for adjusting the tension in said 'springs upon rotation of the shaft, Va cable, a cam-shaped pulley .rotatably supported on the angular eX- sion and secured to said `cable and having `the cable `wrapped thereon for coaction therewith, said pulley being cam shaped in la manner to increase the leverage .of the cable on 'the pulley as the pulley is rotated upon pulling the cable, a crank pin secured to the pulley, za rst link pivotally secured to one of said Stinger bars, and a second link pivotally interconnecting v'said cran-k nin and Asaid first link, .said pulley andfsaid fijst andrsecond links being constructed and arranged' to lresist opening yof the linger' :bars 'from the closed position thereof by a for-ce applied thereto 9. A prosthetic hand mechanism compri-sing, a support, -coact'ing thumb and finger `structures respectively secured to and pivotally mounted Aon said support, a shaft journalled in the support parallel to the pivotal lairis oi' the nger struc ture., :a plurality of anti-friction rollers carried by the finger structure, said pivotal axis' ybeing disposed intermediatesaid shaft and said rollers, a 'plurality of coil springs carried by the-shaft-and having arms respectively extending into engagementwith said .rollers so as to yieldably urge the linger structure into `gripping relation with vre spect to the thumb bar and to progressively increase the tension 4in the springs as the finger structure is 4opened progressively with respect Lto the thumb bar, a cable, a cam-shaped pulleyrotatably mounted on said support and` secured to the cable and having the cable Wrapped thereon for cooperation therewith, said `pulley being ca-m shaped rin a manner to increase the leverage Iof the lcable on the pulley upon rotation thereof as the `cable, is pulled, and a linkage interconnecting the pulley and the iinger structure for pivotally' moving `the finger structure as the pulley is rotated.

l0. In a cosmetic prosthetic hand, the combi# nation of a resilient plastic glove and a mechanized skeletal thumb and linger structure disposed therewithn and comprising a frame having an angular extension, nger bars simulating the skeletal formation of human vlingers mounted for pivotal movement on said angular extension and respectively ldisposed within the fingers of the" i the finger bars away lfrom the thumb bar, andmeans including a cable and a coacting /c'ainf shaped pulley secured to said cable and havin'g' the cable wrapped thereon for moving the finger bars away from the thumb bar in response to 'a pull 'on the cable, said pulley being cam shaped to increase the leverage of the cable on the pulley thereby to compensate -iorsaid increase in ten-` sion of the spring means during said movement of the ringer bars. j

11. A mechanism for a prosthetic hand comprising, in combination, a frame member adapted to "be secured to the stump of a human arin, said movement with respect to `said thumb bar, a'bar extending through said plurality of lingers adjacent said pivotal 'mounting and having apairjof anti-'friction rollers thereon, a shaft rotatably mounted in and extending beyond 'the sides said vframe member in spaced adjacency to said pivotal mounting, a pair-of'helical springs fixedly mounted 4on said s'haft respectively adjacent "the sides of said frame member and having extended ends thereof engaging said rollers, a ratchet 'wheel secured to said shaft, a pawl mounted on said frame 'and engagingl the ratchet lwheel whereby the initial tension `on'said springs is adjustably maintained, said springs yieldably urging said linger structure toward a gripping position with respect to the thumb bar and increasing in tension as the nger structure moves to open position, a peripherally grooved -cam-shaped pulley, anti-friction means for pivotally mounting the pulley on said frame, a pin eccentrically mounted on the pulley, a link interconnecting said pin and said linger structure at a point slightly beyond said bar and for moving the ngers to said open position as the pulley is rotated, means including a cable for rotating said pulley, said cable having one end fastened to the pulley and normally riding in said peripheral groove, said camshaped pulley being shaped to increase the lever arm thereof as the tension of said springs increases during movement of the lingers to said open position thereby to provide a more nearly uniform pulling force on the cable during movement of the finger structure to said open position.

12. A prosthetic hand mechanism comprising, in combination, a frame, a thumb bar attached to the frame, a unitary finger structure pivotally supported on said frame for pivotal movement 25 toward and away from said thumb bar,r spring cured to the pulley and passed around a peripheral portion thereof, and link means interconnecting said nger structure and said cam pulley for moving the finger structure away from the thumb bar as the pulley is `rotated by a pull on the cable, said peripheral portion being shaped to increase the leverage of the cable on the pulley to compensate for said increase in tension of said spring means as the pulley is rotated by the cable whereby the pull on the cable is rendered more nearly uniform during said movement of the linger structure away from the thumb bar.

EDWARD T. LARKINS. BERNARD S. THOMAS. DAVID R. FETTERS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,225,415 Cronemiller May 8, 191'7 1,507,680 Pecorella Sept. 9, 1924 2,409,884 Mollenhour Oct. 22, 1946 FOREIGN PATENTS Number Country Date 163,514 Great Britain May 26, 1921 319,058 Germany Feb. 23, 1920