GB512061A - Improvements in the photographic production of designs for use in jacquard mechanism - Google Patents

Abstract

512,061. Jacquards; cards punching; producing weaving designs. JONES, N. Sept. 10, 1938, No. 24796/37. [Classes 142 (i) and 142 (iv)] [Also in Group XX] In a method for the photographic production of jacquard weaving designs a design A', Fig. 6, of each portion of the pattern which has a separate weave is produced, preferably photographically, and exposed in contact with a weave screen E beneath a light source B' with a square stop b and above a sheet of bromide paper D. The weave screen has a series of minute circular holes, one for every dot of the required weave. The relative distances of stop b, bromide paper, and weave screen and design are so chosen that the square images of the b on the bromide paper join together to reproduce the design with edges of stepped formation. The separate designs are exposed in this way, each through its own weave screen, until the whole design is built up. The separate designs are preferably obtained photographically by producing a number of negatives of the original design and blacking out on each all but the portions corresponding to one particular weave. The finished design is "read on'" to a Jacquard mechanism by the machine shown in Fig. 14. The design is first photographically reproduced on to a thin metal sheet coated with sensitive material which is hardened to an adherent non-conducting layer where affected by light and washed off where unaffected. This metal sheet is then placed round. one of the rollers H. A row of insulated needles h is reciprocated vertically by an eccentric h<2> so as to make contact with the bare parts of the surface and thus operate electromagnets controlling the needles of the Jacquard mechanism. The rollers H are fed forward by a crank h' operating a pawl h<6> engaging a wheel h<5> geared to the rollers. When dealing with fabrics with different relationships between the number of picks and the number of warps per unit size, the same weave screens can be used for any if the original design is appropriately distorted, to alter the ratio of length to width, in the production of the section negatives. A machine as in Fig. 8 may be used. A transparent copy of the original design is attached to the band F<3> with one end attached to a drum F<2> and kept taut by a weight W. Sensitised material surrounds the drum F<1>. As the drums are rotated, due to the different diameters of the drums, the design and sensitized material pass at different speeds beneath a lamp g with slit g<1> to give a distorted contact print. The illumination of the lamp is intermittent. The machine shown in Fig. 12 is used for producing the weave screens. ' A 'copy of each weave is made in the ordinary way, Jacquard cards are cut by hand and used in a Jacquard machine the harness of which is connected to a row of fine punches m, each with a projection m', slidable in a frame M. As the frame M is lifted, a swinging frame M<2> is lifted outwards by a roller M<3>. When the frame M is lowered, the projections m<1> of those punches which have not been lifted by the Jacquard are engaged by the bar M<2> and the material E is punched accordingly. Specification 469,654 is referred to.