US2351452A

US2351452A - Pantograph

Info

Publication number: US2351452A
Application number: US475586A
Authority: US
Inventors: Pash Robert
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1943-02-11
Filing date: 1943-02-11
Publication date: 1944-06-13
Anticipated expiration: 1961-06-13

Description

`lune 13, 1944.A R. PASH PANTOGRAPHl Filed Feb. 11. 1943 2 Sheets-Shan. 1

FIG. 2

R. PASH PANTOGRAPH June 13, 1944.

Filed Feb. 11 1945 Z'Sheets-Sheet 2` y FIG. 4

/NVEN TOR l?. PA SH A TTORNEY Patented June 13, 1944 UNITED STATES PATENT OFFICE;

* APAN'roGRAPH Robert Pash, Roselle, N. J., assignor to Western Electric Company, Incorporated, New York, N. yY., a corporation of New York vApplicationFebruary 11, 1943, serial No. 475,586

's claims. (cia3- 24) This invention relates to a.. pantograph "and more particularly to a pantograph controlled by linkages dependent only upon pivotal connections and not upon rectilinear or rectiplanar guide members for accuracy of operation or for support or both.

The most familiar linkage employed in pantograph construction as the controlling factor in its operation, is probably one form or another of the lazy tongs, too familiar to need descrip-,tionhere One characteristic ofthe lazy tongs `linkage is that it has practically no rigidity transversely of the common plane of its links. Its accuracy of operation requires it to be supported on a single plane surface of operation, upon which both its guide point and tracing point must; rest in such fashion that the members -of the linkage are always parallel to this plane. Another feature of this arrangement is that both the tracing pointl and .the drawing point operate on the same plane, so that the linkage extends over and more or less obscures and obstructs the area of operation. y

An object of the present invention is to provide a pantograph device in which controlling linkage is removed from the working surfaces entirely, is substantially self-supporting, and permits of having the tracing plane and drawing; plane spaced apart and parallel to-each other.

Another object of the invention is to provide a pantograph device capable of reproducing and simultaneously proportionally enlarging vor diminishing in three dimensions, so that, for example, a contoured model map may be copied on another scale.

'With the above and other objects in view, the invention may be embodied in a pantographhaving a two dimensionally extended. primary link age member mounted -to berotatable about yan axis in the plane thereof and about an axis perpendicular to and intersecting the first namedaxis, anda pair of two dimensionallyextended secondary members each .pivotably attached to the primary members on an axis parallel to the first named axis of the primary member andeach provided with a tracing point,` in combination.

with two mutually parallel drawing boards perpendicular to the second named axis of theprimary linkage member to respectively receive 'and support the two tracing points, the `two secondary members being mutually so proportioned that the4 two tracing points lie in a planepassing through the first named axis of the primary ber.

linkage memv Other objects and `features, of the inventionV tion of embodiments thereof, taken in connection with the accompanying drawings in which the same reference numerals are applied to identical parts in the several figures and in which Fig. 1 is a view in side elevation of a pantograph embodying the invention;

Fig. 2 is a left end elevation of the showing of Fig. 1;

Fig. 3 is a broken plan View thereof, and

Fig. 4 is a diagrammatic view in side elevation of the pantograph in use three dimensionally.

The arrangement shown in Figs.. 1, 2 and 3 is a pantogiraphic device primarily for reproducing, on an altered scale, a map, drawing or other two dimensional figure. A pair of horizontally disposed drawing boards 2|J and 2| are supported in fixed columns 22 and23, the upper board 20 immovably and the lower board 2| being adjustable as to height. At one side of this generalstructure, `a support member 24 is mounted to be freely pivotable aboutI a vertical axis, i. e. about an axis perpendicular to 'both drawing boards. Accurate Vmaintenance of position of this'axis/,of rotation is important. Hence, for example, the member 24 should have an integral stub shaft 25 as long as is reasonably practicable, and this.:

in turn, should be mounted in two

separate bearings

26 and 21 spaced as far apart as circumstances will permit. A horizontal shaft 28 is rigidly mounted in or secured to the support 24 to be rotatable therewith. At; each end of the shaft 28 is pivoted one of a pair of

parallel twin bars

29 and 30, which are rigidly connected together at their other ends by a crossbar 3|. The

bars

29 and 30 are further connected together and braced by transverse

anti-torsion members V

32 and 33, here shown as tubular and welded to the

members

32 and 33 and their top crossbar 3| form a single, two dimension-ally extended, torsionally 'rigid member `which will be hereinaftertermed the primary linkage member or primary link of the pantograph linkage. As mounted, this primary link is freely rotatable about the `rigidly fixed vertical axis of the support 24 and also about the horizontal axis of the shaft -28 carried by the member 24. For accuracy of expression, the horizontal axis of the shaft 28 will, in the appended claims, be called the body axis of the shaft.

Near the top of the primary link, now generally indicated by the numeral 34, a secondary link, generally indicated by the numeral 35, Ais mounted on the primary link 34 to be freely pivotable Will appear from `the foillOWirlg detailed descrip-,55 with respect thereto about an axis parallel to the axis of the shaft 28; and a second secondary Y link, generally indicated at 36, is mounted on ythe shaft 28.

Details of structure and arrangement are not minutely described since these are, in general, not novel or relevant to the invention. Important features are that the vertical axis of rotation of the support 24 be invariable, that the

links

34, 35 and 36 each be torsionally rigid with respect to any of the stresses of ordinary use, and that the axis on which the link 34 pivots on the member 24 and the axes on which the

links

35 and 36 pivot on'the link 34 be all three mutually parallel and in one plane, no matter how the link 36 be adjusted in position on the link 34. To ensure these latter conditions, the three links Vare made as broad from side to side as is reasonably practicable so that each maybe pivoted upon two separate .bearings means asfar apart as reasonably practicable. n As thus far described, the arrangement .is an operable pantographic device. If the point i31 mounted on the free extremity of the link .35 be caused to follow any gure on the drawing .board 20, the point 38 mounted on the free extremity of the link 36 `will tracea similar figure of smaller dimensions on the board 2|. The .dimension ratio .of the two figures will vbe the ratio of the distances from the axes of the

links

35 and 36 to the axis of .the link 34, provided that the position of the point '38 on the link 36 be vsoadjusted that the `line lthrough the two points `31 and .38 intersects the axis of the link 34. A handle 39 may be provided on the link 35 for easier manipulation of the point 31. The pivotable support 24 must be located well outside the area of operation of the point 31, since the lever arm by which the whole linkage `is rotated on the vertical axis of the support 24 isthe distance from this axis to the handle 39.

As described and demonstrated, the arrangement is a practicable and useful pantographic device. However, if the `point 31 be lifted from one point ofthe figure on the board 2U and -set down on -another point, the point 38 will not lift correspondingly but will trace from the corresponding first point to the corresponding second point. To provide means t make the drawing peint 38 follow the tracing point 31 in vertical motion also, the links 35 and 3G are extended backward past Vtheir axes of pivotability `in the link 34, and are connected togetherv by a tertiary link 40, pivotably connected to each of the

links

35 and 36 at points equidistant from the link34, so that the link 40 is always parallel to the link 34. The connection between the link v40 and the link 36 is made to be adjustable along the link 440, so Athat the

links

35 and 36 may also always be parallel. With the link 40 added, the motion of the point 38 will -always be a reduced facsimile of the motion of the point 31 in any spatial direction in `all three dimensions. Thus, as diagrammatically illustrated in Fig. 4, the arrangement is also capable `of use as a three dimensional pantograph, to copy a solid body, e. g. a modelledcontour map, on an altered scale.

While the point 38 has been described and thought of as the reproducing point whose motion is controlled by the motion of the tracing point .31, to reproduce on a smaller scale a fig.-

ure traced by the point 31, it will be obvious that this relation may be reversed and the point 31 caused to reproduce on an enlarged scale a figure traced by the point 38.

A device having particular details of construetion to ensure torsional and other rigidity of parts and to provide for adjustability as described is disclosed `in the drawing to illustrate the invention. Such details may be varied in various ways without departing from the spirit and scope of the invention as pointed out and described in the appended claims.

LWhat is claimed is:

1. In a pantograph, a linkage to effect control ofthe-motion of a reproducing point by the motion of a tracing point, the said linkage comprising a support pivotable about an axis, a

primary linkon the support and pivotable thereon about an axis perpendicular to the axis thereof, and two secondary links pivotable on the primary flink about spaced and mutually parallel axesparallel tothe axis of the primary link on thesupport, the .tracing point being mounted on one ofthe seconda-ry links andthe reproducing point being mounted on the other secondarylink in combination with two mutually parallel work supporting-tables to coact respectively with the tracing point and the reproducing .point and having their Working Vsurfaces transverse to the direction of fthe axis ofthe pivotable support.

2. In a .pantograph, a linkage to effect control of the-motionof a reproducing point by the motion .of a ftracing point, the said linkage comprising a :support pivotable about .an axis, a primary linkonthe support and pivotable thereon about `an axis perpendicular to the axis thereofftwosecondar-y links pivotable on the pri.- mary link about spaced and mutually parallel axes `.paralle1 to the axis of the primary link on the support, 'and a tertiary link pivotably attachedto both secondary links and spaced from and 4paralle1 Yto the primary `link, the tracing point being mounted on one of the secondary links andthe reproducing point bei-ng mounted on vthe v'other secondary link in combination with two mutually parallel `work supporting tables to coact respectively with the Vtracing point and the reproducing point and having their Working surfaces transverse to the Vdirection of the axis ofthe pivotable support.

3. In a pantOgraph, a linkage to effect control of the motion of a reproducing point by the motion of a tracing point, the said linkage comprising a shaft pivotable about an axis perpendicular to the body axis ofthe shaft, a primary link pivotable on the shaft about the body axis thereof, and two secondary links pivotable on the primary link about spaced and mutually parallel axes paralle1 to the body axis of the shaft, the tracing point being mounted on one of the secondary links and the reproducing point being mounted on the other secondary link in combination with two mutually parallel work supporting tables to coact respectively with the tracing point and the reproducing point and having their Working'surfaces transverse to the direction of the axis about which the shaft is pivotable.

4. In a pantograph, a linkage to effect control of the motion of a reproducing point by the motion of a tracing point, the said linkage comprising a shaft pivotable about an axis perpendicular to the body axis of the shaft, a primary link pivotable on the shaft about the body axis thereof, two secondary links pivotable'on the primary link about spaced and mutually parallel axes parallel to the body axis of the shaft, and a tertiary link pivotably attached to both secondary links and spaced from and parallel to the primary link, the tracing point being mounted on one of the secondary links and the reproducing point being mounted on the other secondary link in combination with two mutually parallel work supporting tables to coact respectively with the tracing point and the reproducing point and having their working surfaces transverse to the direction of the axis about which the shaft is pivotable.

5. In a pantograph, a linkage to effect control of the motion of a reproducing point by the motion of a tracing point, the said linkage comprising a shaft pivotable about an axis perpendicular to the body axis of the shaft, a two dimensionally extended and torsionally rigid primary link journalled on the shaft at two spaced points thereon to be freely pivotable thereon about the body axis of the shaft, and two two dimensionally extended and torsionally rigid secondary links each journalled on the primary link at two spaced points thereon to be freely pivotable thereon about spaced mutually parallel axes parallel to the body axis of the shaft, the tracing point being mounted on one of the secondary links and the reproducing point being mounted on the other secondary link in combination with two mutually parallel work supporting tables to coact respectively with the trae ing point and the reproducing point and having their working surfaces transverse to the direction of the axis about which the shaft is pivotable.

6. In a pantograph, a linkage to effect control of the motion of a reproducing point by the motion of a tracing point, the said linkage comprising a shaft pivotable about an axis perpendicular to the body axis of the shaft, a two dimensionally extended and torsionally rigid primary link journalled on the shaft at two spaced points thereon to be freely pivotable thereon about the body axis of the shaft, two two dimensionally extended and torsionally rigid secondary links each journalled on the primary link at two spaced points thereon to be freely pivotable thereon about spaced mutually parallel axes parallel to the body axis of the shaft, and a tertiary link pivotably attached to both secondary links and spaced from and parallel to the primary link, the tracing point being mounted on one of the secondary links and the reproducing point being mounted on the other secondary link in combination with two mutually parallel work supporting tables to coact respectively with the tracing point and the reproducing point and having their working surfaces transverse to the direction of the axis about which the shaft is pvotable.

ROBERT PASH.