Web carrier, web carrying method, and web carriage control program

A web transport apparatus transporting a sheet web by using multiple rollers, comprising:

• a driving roller transporting the web;
• an angle adjustable roller disposed adjacent upstream of the driving roller in a transportation direction, provided with a shaft adjustable in a shaft direction;
• imaging means for picking up an image of the web transported on the angle adjustable roller;
• alignment adjusting means for adjusting the angle of the shaft of the angle adjustable roller;
• and
• a controller,
• wherein the controller comprising:
• image analyzing means for detecting a linear pattern of a waveform generated on the web to find a sign of wrinkling in the web from the image picked up by the imaging means, and for analyzing an entering direction of the linear pattern into the angle adjustable roller;
• and
• shaft angle control means for adjusting the shaft of the angle adjustable roller such that the shaft direction is perpendicular to the entering direction of the linear pattern analyzed by means of the image analyzing means, and for controlling the alignment adjusting means, whereby the web is not wrinkled.

A web transporting method for a web transport apparatus provided with multiple rollers transporting a sheet web, the method comprising:

• a critical tension calculation step of calculating a critical minimum tension on the web in which the web slips and a critical maximum tension on the web in which the web is wrinkled, on the basis of a driving information as to a predetermined driving condition of the web transport apparatus and of a physical property of the web;
• a tension control step of controlling the tension on the web such that the tension is within the critical minimum tension and the critical maximum tension;
• an image analysis step of detecting a linear pattern of a waveform generated on the web from an image picked up in the web being transported on an angle adjustable roller that is adjustable in a shaft direction and analyzing an entering direction of the linear pattern into the shaft of the angle adjustable roller;
• a shaft angle control step of moving the shaft of the angle adjustable roller such that the shaft direction is perpendicular to the entering direction of the linear pattern analyzed in the image analysis step.

A web transport control program for a web transport apparatus provided with multiple rollers transporting a sheet web, the program ordering a computer to perform functions of:

• calculating a critical minimum tension on the web in which the web slips and a critical maximum tension on the web in which the web is wrinkled, on the basis of a driving information as to a predetermined driving condition of the web transport apparatus and of a physical property of the web;
• controlling the tension on the web such that the tension is within the critical minimum tension and the critical maximum tension;
• detecting a linear pattern of a waveform generated on the web from an image picked up in the web being transported on an angle adjustable roller that is adjustable in a shaft direction and analyzing an entering direction of the linear pattern into the shaft of the angle adjustable roller;
• and
• moving the shaft of the angle adjustable roller such that the shaft direction is perpendicular to the entering direction of the analyzed linear pattern.