DRAWING METHOD FOR ELECTRONIC BLACKBOARD

In an electronic blackboard, a print head for drawing an image on the screen sheet is disposed on the upstream side of a read head for reading an image from the screen sheet, with respect to the forward travel direction of the screen sheet. When an image is printed on the screen sheet, the screen sheet is moved in the reverse travel direction. When the read head reads an image on the screen sheet, print stop processing is performed in order to stop printing operation of the print head. If an unerased image is present on the stored face of the screen sheet when printing on the screen sheet is performed, the unerased image on the stored face passes by the read head, because the screen sheet is moved in the reverse travel direction during such a printing operation. If the read head reads an unerased image, the print stop processing is performed in order to stop printing operation of the print head, and warning display processing is performed in order to display a message indicating that an unerased image is present on the screen sheet.