Patent ID: 8091476

Claim:
A web conveyance method of tandem printing system wherein first and second printers to form images on a web are tandemly arranged, and there are provided a web feeding mechanism for feeding a web into said second printer and an air loop mechanism disposed subsequently after the web feeding mechanism to create slack in the web and convey the web; said web conveyance method of tandem printing system, comprising: at the time of the start of standby for printing, a step of detecting a tensile force of the web at least one position from a downstream of a web discharge part of the first printer to an upstream of the web feeding mechanism of the second printer, a step of reporting the resulted tensile force to a control apparatus of said second printer, a step of starting low-speed web conveyance by the web feeding mechanism when the control apparatus of said second printer receives information indicating that said resulted tensile force is less than a prescribed value, and starting a measurement of an amount of web accumulated in the air loop mechanism, the web being accumulated by the low-speed web conveyance, and a step of halting the low-speed web conveyance when information indicating that the resulted tensile force has exceeded the prescribed value is received, and saving in a memory the amount of web accumulated in the air loop mechanism, the web being accumulated by the low-speed web conveyance, at a time of start of a printing, a step of starting high-speed conveyance of the web by web conveyance mechanisms other than the web feeding mechanism, and starting the measurement of an amount of conveyances of the web, the web being conveyed by the high-speed conveyance, and a step of starting a high-speed conveyance by the web feeding mechanism when the difference between the amount of the web accumulation in the air loop mechanism and the amount of the high-speed conveyance of the web becomes below a predetermined value.