MECHANISM FOR ADJUSTING PRINT GAP AND THICKNESS DETECTOR

摘要

PROBLEM TO BE SOLVED: To obtain a print gap adjusting mechanism for sustaining an appropriate print gap constantly while minimizing the time required for adjustment. SOLUTION: A noncontact print gap detector 3 irradiates a print sheet 5 on a platen 8 with laser light and detects the print gap between the print sheet 5 and a print head 1. A shaft 4 for guiding a carrier frame 2 provided with the noncontact print gap detector 3 and the print head 1 rotates eccentrically to adjust the print gap. Noncontact sheet thickness detectors 6 and 7 detect the thickness of the print sheet 5 in the upstream of the print section and adjust the print gap to fit in with the thickness of sheet before the print sheet 5 is sucked into the print section. The noncontact print gap detector detects the print gap periodically immediately after the print sheet 5 is sucked into the print section and during print operation and corrects the print gap to an appropriate value if it deviates from an allowable range.