Screen printing apparatus

In screen printing apparatus for printing on web material, a printing station including:

• a screen printing mesh attached under tension to a screen frame;
• reciprocating means for rectilinearly reciprocating said screen frame with a particular speed;
• a squeegee mounted above said screen printing mesh for movement into contact with said screen printing mesh along a line of contact, and out of contact with said screen printing mesh;
• means for feeding ink to one side of the squeegee above the mesh;
• a profiled support surface positioned opposite said squeegee and below said screen printing mesh for supporting a portion of the web material in a planar configuration which forms a snap-off angle between itself and the screen printing mesh at the line of contact, said screen printing mesh being biased toward said support surface when said squeegee is in contact with it;
• conveyor means for moving the web of material to be printed on between said support surface and said screen printing mesh at the location of said squeegee, said conveyor means moving said web of material at the particular speed of said reciprocating means during a printing stroke when said screen printing mesh is biased towards said support surface by said squeegee, the improvement comprising;
• means for moving said support surface during said printing stroke to change the position of the planar configured portion of the web such that the snap-off angle between the support surface, and hence the portion of the web of material which lies against the support surface, and the portions of the screen printing mesh after the squeegee, is maintained at a substantially constant value, a snap-on angle between the support surface and the portion of the web of material before the squeegee also is maintained at a substantially constant value.