US1815196A - Ladder web for venetian blinds - Google Patents

Description

July 2l, 1931-. G' F FRENCH ET AL I 1,815,196

LADDER WEB FOR VENETIAN BLINDS Filed Aug. 25, 1950 A? I I I fh??? W 04 e AeA/'w21' hit/Z I I I j' @w 22%. z @Mw-Manly.;

Patented July 21, 1931 TES PATENr OFFICE.

LAIDDER WEB SFOR VENETIAN BLINDS Application led August 25, 1930, Serial No. 477,764, and in Great Britain September 14, 1929.

5 of intermittent straps prevent end'wise movement-of the laths.

An objection to Venetian blinds is that if subject to a draught, say when hung at an open window, or outside a window, or if in positions other than the vertical, say over a sloping skylight, the laths are apt to be displaced, and allow lightto pass between them, and are also liable to rattle.

To -overcome such drawback, it has already been proposed to provide ladder webs with double or two-ply woven straps, the

laths passing between the plies, but such tapes have been expensive and slow to manufacture, and have presented diiiiculties in weaving owing to an increased number of shuttles being needed, necessitating special looins with complicated dobby or jacquard motions.

The object of this invention is to provide a ladder web with double straps which can be woven with the same number of shuttles as' the ordinary single strap webs, and at.

practically the same rate of production, which can be manufactured at a'cost very 9 little, if anything at all, above the cost' of the ordinary single straps tape, using virtually standard looms, and with little complication in the warp-shedding devices.

According to the invention the improved ladder web is characterized by double straps wherein the second or extra strap is Jformed from an eXtra warp or warps left unwoven for a portion or portions of its length. In the preferred example there are a number of warps left entirely free from weft during the weaving of the straps. Ladder Webs according to this invention may be woven on the same looms used for single strap webs, i. e. having four tiers of shuttles.

In a modification the extra strap of one part-width web may, for a portion of its length, be supplied with weft from the shuttle used to weave the ordinary strap of the other part-width web and vice versa.

In a further modification, the two straps of each pair are supplied alternately with a number o' picks of weft, and the crossings over from one strap to the other subsequently severed or removed.

The eXtra or dummy straps thus formed, not having to bear the weight of a lath, but merely to lie on the top of the' lath, are quite sulicient to prevent displacement of the lath.

The dummy straps may be direct-ly above the usual straps or to one side thereof, or even on the other half or side of the body wbs, but clear of the woven straps on that si e.

The invention will be further described with reference to the accompanying drawings, wherein z- Figs. 1 and 2 are edge and side views respectively of a ladder web constructed according to one form of the invention.

Fig. 3 is a part sectional perspective view of the web shown in Figs. l and 2, illustratingY the use of the improved double straps.

Figs. .Lto 7 arediagrammatic views illusltrating methods of weaving the improved web, hereinafter described.

Fig. 8 is a view corresponding to Fig. 2, but to a smaller scale, and illustrating a further form of the invention.

As shown in Figs. l to 6, the ladder web comprises two full-width woven webs A, B, and two part-width woven webs C, D, the latter being woven into the former at regular intervals. The extra or dummy straps in this form of the invention consist of warp threads only, without weft, see Figs. l to 3, and may be obtained by introducing a number of extra warp threads a, or by selecting some of the warps of the part-width webs where they are not woven into the body webs. During the time that the ordinary straps C and D are being woven, these selected Warp threads do not shed or-divide with the ordinary warps b and c but are held fixed so that no weft is inserted between them, see Flgs. 4, 5 and 6. This can conveniently be ac complished by adding additional hooks o1 ]a cks on the acquard or dobby (or by lntroducing a second jacquard or dobby) and addltional heald shafts, for the extra warps. A tape thus produced has a length of unwoven or floating warpthreads a against each woven strap, thus .producing the .desired double strap. The laths of the blind lie between the double straps as 4may be seen from Fig. 3.

In another form of the invention, the extra strap is obtained as in the previously described example, i. e. by means of extra warps a, or selected warps, but during the time that the usual strap C or D is being woven into the two body webs (a distance of about 1% to 13/8 for a strap of the average length of 21/2, and represented by the reference d in Fig. 8), the shuttle for such strap, which A throughout that period is not putting weft into the strap, although crossing the web at each pick, is employed to insert weft in the warps -a forming the opposite extra strap, as represented by the reference e in Fig.`8, the extra warps being separated b'y' th'e healds to receive the weft. The shuttle for the strap C inserts weft threads in the dummy opposite the strap D, and vice versa. This is accomplished by shedding the selected warps by means of extra heald shafts fitted for the purpose. The weft threads will be inserted in the dummy straps for a length equal to the length taken up by the binding of the straps in the body webs. The weft in the dummy straps will only connect in the middle of the strap warps a but will spread out to a certain extent over the length of such straps.

. In a further form of the invention and as illustrated in Fig. 7, the lath straps are woven two-fold or V shape, that is to say, the straps C and a or D and a are supplied alternately with weft from the same shuttle and the shedding is such that say 6/ 8 picks of weft are first inserted in the top half, then a similar number in the bottom half, and soon. The two halves are thus oined by a number of crossings of weft 7 to each strap, which on beingcut will -produce two tapes. These may be slightly imperfect owino to their each having ing double' straps one of which isformed by selecting and holdin out a number of warps from the other whilst the latter is being woven, as set forth. l

2. A ladder web for Venetian blinds, having double straps one of which comprises unwoven warp threads which have not been' shedded during the weaving of the other, as set forth.

3. A ladder web for Venetian blinds having two full-width webs and two part-Width webs and having double straps according to claim 2, characterized in that the otherwise unwoven warp threads of one part-width web are supplied with weft from the vshuttle which normally weaves the straps of the other partwidth web, whilst the latter is being woven into the full-width webs, as set forth.

4. A ladder web for Venetian blinds, having double straps, each of which is formed in portions of its length by unwoven warp threads which have not been shedded during the weaving .of the opposite parts of the other, as set forth.

In testimony whereof we have signed our names to this specification.

GEORGE FREDERICK FRENCH. ROGER FRENCH.

only half the usual number of picks and those distributed in periodic patches, but the tendency will be for the weft to distribute itself over the whole length of strapwarp (especiallyif a coarse weft is used) producing light tapes.

Whilst preferring the arrangement of extra warps only or part extra warps and part weft to form dummy straps, .a length or lengths of narrow braid or tape or cords may be used as part of the warp.

'What we claim is 1. A ladder web for Venetian blinds, hav-

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