| 摘要 |
PURPOSE:To facilitate the cassette designing for a transfer material by determining the winding diameter thereof checking the rotational speed of a winding core to detect the winding diameter of the transfer material in a non-contact manner. CONSTITUTION:A disc plate 57 having slits 56... is mounted at an equal space on the driving shaft 51a of one ribbon motor 51. Optical detectors 58 for detecting rotational speed are provided at the position corresponding to the slits. The circumferential speed VP of the platen 10 is equal to the transfer speed V1 of a heat transfer ribbon 15. When the winding diameter of the heat transfer ribbon 15 at an intermediate position is represented by D, the rotational speed N of the winding core 32 is inversely proportional to D when the value V1 is constant. On the other hand, DELTAtproportional 1/N is given, when the time interval of the output signals from the detectors 58 is represented by DELTAt. Therefore, as DELTAtproportional D is derived, the relationship of DELTAt=A.D+B (A and B are constants) is obtained. The winding diameter of the heat transfer ribbon 15 can be converted by learning A, B and DELTAt. With such an arrangement, the winding diameter of the heat transfer ribbon 15 can be detected free from contact with the heat transfer ribbon 15 along with an easier cassette designing of the heat transfer ribbon 15. |
