Patent ID: 8734037

Claim:
An apparatus comprising: a sheet feeding unit configured to feed a sheet that is a continuous sheet; a reverse unit configured to reverse the sheet for duplex printing, wherein, in the duplex printing, a printing unit performs printing a plurality of images on a first surface of the sheet fed from the sheet feeding unit, the printed sheet is reversed by the reverse unit to feed the reversed sheet to the printing unit again, and the printing unit performs printing a plurality of images on a second surface, which is a back of the first surface, of the sheet fed from the reverse unit; the printing unit, wherein the printing unit is configured to print on the sheet and convey the sheet as a conveyed sheet, wherein the printing unit includes: a print head, a first roller pair configured to nip the sheet at an upstream side of the print head to convey the sheet, a second roller pair configured to nip the sheet at a downstream side of the print head to convey the sheet, a third roller pair configured to nip the sheet at an upstream side of the first roller pair to convey the sheet, a direct sensor configured to measure a surface of the conveyed sheet at a measurement position between a nip position of the first roller pair and a nip position of the third roller pair to obtain information relating to a movement speed of the conveyed sheet, and a mark reader configured to read marks, formed on a first surface of the sheet fed from the sheet feeding unit by the print head with a plurality of images, at a reading position between the nip position of the first roller pair and the nip position of the third roller pair when printing on a second surface of the sheet fed from the reverse unit; a humidifying unit having a duct leading to a discharge opening located at an upstream side of the nip position of the third roller pair to introduce a humidifying gas from the humidifying unit in a way that causes the introduced humidifying gas to flow through around the measuring position of the direct sensor, then flow through a gap between the print head and the sheet; and a control unit configured to control to correct at least one of driving control of the print head and conveying control of the sheet based on the information obtained by the direct sensor, and to adjust print positions of each image on the second surface of the continuous sheet to each image on the first surface of the continuous sheet based on read timings by the mark reader.