Printing apparatus

#The present invention relates to a printing apparatus that performs printing on a sheet pulled out of a roll sheet in which a continuous sheet is wound.

#A printing apparatus that automatically detects a sheet leading end of an installed roll sheet (hereinafter also referred to simply as a “roll”) is disclosed in Japanese Patent Laid-Open No. 2011-37557. In this apparatus, the roll is rotated in a winding direction opposite to a supply direction, and separation of the sheet leading end from the roll due to its own weight (hereinafter also referred to as “peeling”) is detected by an optical sensor placed near the roll.

#The optical sensor disclosed in Japanese Patent Laid-Open No. 2011-37557 detects the peeling of the sheet on the basis of an on-output obtained by reflected light at a moment at which the leading end of the sheet peeled from the roll passes through a sensor optical axis parallel to a tangent line of the roll. A signal strength of the sensor output at this time is substantially zero until the peeled sheet leading end reaches the sensor optical axis, and a pulse-like signal is generated by reflected light at an edge of the sheet leading end at a moment at which the sheet leading end passes through the sensor optical axis. After passing through the sensor optical axis, sensor light strikes an inner surface of the peeled sheet, but since the sensor optical axis and the inner surface of the sheet are substantially parallel, and a distance between the inner surface of the sheet and the optical sensor is increased abruptly, a reflection strength is weak and a signal level after passing falls abruptly. In other words, basically, the optical sensor disclosed in Japanese Patent Laid-Open No. 2011-37557 is only able to determine a moment at which the sheet leading end passes through the sensor optical axis in the middle of peeling.

#FIG. 1 is a perspective view of a printing apparatus according to the present invention;

#FIG. 2 is an explanatory diagram of a sheet conveyance path in the printing apparatus;

#FIG. 3A is an explanatory diagram of a sheet supplying apparatus, and FIG. 3B is an enlarged view of a swing member in FIG. 3A;

#Hereinafter, exemplary embodiments of the present invention will be described with reference to the appended drawings. First, a basic composition of the present invention will be described.

#<Basic Configuration>

#FIGS. 1 to 5 are explanatory diagrams of a basic configuration of a printing apparatus according to an embodiment of the present invention. A printing apparatus of the present example is an inkjet printing apparatus including a sheet supplying apparatus that supplies a sheet serving as a print medium and a printing unit that prints an image on the sheet. For the sake of description, coordinate axes are set as illustrated in the drawings. In other words, a sheet width direction of a roll R is set as an X-axis direction, a direction in which the sheet is conveyed in a printing unit 400 to be described later is set as a Y-axis direction, and a gravity direction is set as a Z-axis direction.