| 摘要 |
PURPOSE: To enhance positional control of a printing pattern on a completed bag by measuring an actual distance between adjacent eyemarks and calculating an average actual spacing between the eyemarks to set a predetermined draw length so as to allow the same to substantially coincide with the spacing. CONSTITUTION: A plurality of eyemarks 32 are printed on a web 12 at an equal interval along the outer edge of the web 12 in order to accurately arrange a seal to the printing pattern 17 on the web 12 and the passage of the eyemarks 32 is detected photoelectrically by an optical scanner 34. The actual spacing between the continuous eyemarks 32 is detected and a predeterined nominal take-up length is set so as to substantially coincide with the actual spacing. Herein, a distance DL is set so as to almost coincide with a value obtained by adding one half the width of a 'detection window' to a value which is obtained by adding an error actually measured as a time of previous drawing to the nominal spacing of the eyemarks 32 capable of being set on a control panel 22 by a worker. By this constitution, the positional control of the printing pattern 17 on a completed bag can be enhanced. |
