Patent ID: 7705281

Claim:
An image forming apparatus, comprising: an information detecting device for detecting information on a sheet material; an image forming means for forming an image on the sheet material and which functions as a sheet material treating unit; and a sheet transport means for transporting the sheet material from the information detecting device to the image forming unit, wherein the information detecting device comprises: means for applying an external force to the sheet material; a detecting unit for detecting information corresponding to a force existing after attenuation of the external force applied to the sheet material, the detecting unit including a piezoelectric member; and a sheet material displacing means for displacing the transported sheet material to a proper position; wherein, when the external force is to be applied, the sheet material displacing means performs positioning of the sheet material such that a distance between the sheet material and the detecting unit opposed to the sheet material is a predetermined value not less than 0, and the image forming means treats the sheet material based on a result of the detection by the information detecting device.