jacquard guide bar!jacquard fabric!jacquard The invention of the Jacquard machine in weaving allowed effective individual control of each warp yarn in weaving. The idea was transferred to warp knitting, where single guides are individually controlled in one guide bar (Figure 9.1). In case of mechanical or electric command, each guide on the jacquard guide bar can be bent so that it places the yarn at one position higher then the original one in relaxed, or not activated position. Currently the most advanced are the piezo-jacquard bars [15],[16], where at each guide one piezoelectric transducer is fixed. The transducer deflects the guide by application of a control potential. Information about the older mechanical or electromechanical systems can be found in a several books. This chapter concentrates on the fabric construction of these fabrics. The possibility to move each guide individually opens enormous patterning possibilities in warp knitting, because it increases the variations of the loops without the need of a large number of single bars. From another point of view, the jacquard bar is more costly and requires special software and good educated people for the design of the fabrics. For these reasons warp knitted machines with jacquard guide bars are used mainly for products where individual local changes of the pattern are required.