A printing apparatus, including a sheet conveyer unit with a first roller unit, a printer unit, and a controller, is provided. The controller executes a first-face printing process, wherein an image is printed on a first face of a sheet; a switchback process, wherein the sheet after the first-face printing process is conveyed in a reverse direction by the first roller unit; a second-face printing process, wherein the image is printed on a second face of the sheet; a first ink amount determining process to determine whether an ink amount discharged in the first-face printing process at an end area of the sheet is one of greater than and equal to a first threshold amount; and a switchback setting process, wherein, if the ink amount is smaller than the first threshold amount, a rotation speed of the first roller unit is set at a higher rotation speed.

A decoloring device according to an embodiment includes a decoloring unit that erases a first image formed with erasable colorant on a first side of a sheet and a second image formed with erasable colorant on a second side of the sheet. A reading unit reads the first and second sides of the sheet and determines whether the first side and the second side are reusable. A single-side reusable paper tray stacks the sheet if the reading unit determines that only one of the first and second sides is reusable. A marking unit adds a mark to the one of the first and second sides that is determined to be not reusable when only one of the first and second sides is determined to be reusable.

A laser machining apparatus includes, a processing chamber, a window disposed in a surface of the processing chamber, a substrate carrier disposed inside the processing chamber and facing the window, a laser irradiator which irradiates a laser onto the substrate carrier through the window, a protector supplier disposed on a side of the processing chamber, a protector retriever disposed on an opposite side of the processing chamber opposite to the side of the processing chamber, and a protector which connects the protector supplier with the protector retriever, where at least a portion of the protector is disposed between the substrate carrier and the window in the processing chamber.