Belt transfer type multi-function device and control method thereof

A control device for a belt transfer type multi-function device printing an image transferred on a belt to paper moving between a transfer roller and a belt roller, the control device further comprising:

• a security paper detection sensor installed on a transfer path of paper starting from a paper tray,
• wherein the control device determines whether corresponding paper is security paper according to a detection value from the security paper detection sensor, and performs control such that security paper is normally printed and plain paper is ejected as blank paper,
• wherein the control device performs controlling such that an image to be printed on paper already caught between the transfer roller and the belt roller is printed as it is, and if the control device determines that next paper along a movement direction of paper is plain paper, the control device performs controlling the belt transfer type multi-function device by switching such that movement of the next paper is stopped on the transfer path of paper before the next paper is positioned between the transfer roller and the belt roller, the image already transferred on the transfer belt is deleted in a state in which the next paper is maintained to be stopped on the transfer path of paper, and the next paper in a stopped state is ejected as a blank paper through a ejection port of printed paper along the transfer path of paper, with the image already transferred to the transfer belt, which is to be printed on the next paper along the movement direction of paper, being not printed on the next paper.