MOVEMENT AMOUNT DETECTION DEVICE, IMAGE FORMATION DEVICE AND MOVEMENT AMOUNT DETECTION METHOD

摘要

PROBLEM TO BE SOLVED: To reduce error in a case where a movement amount is detected by discrete Fourier transform.SOLUTION: A movement amount detection device includes a light source for lighting a surface of a sheet-like body, an imaging sensor for imaging a pattern of the surface with a reflection light from the sheet-like body, a discrete Fourier transform part 61 which performs a discrete Fourier transform with two patterns Di, Dj obtained by imaging using the imaging sensor with a time interval, a high frequency component removing part 62 which removes a high frequency component HG for the two patterns Di, Dj having been subjected to the discrete Fourier transform by using a threshold value determined based on a cycle of rough on the surface of the sheet-like body, and a movement amount calculation part 66 which acquires a movement amount of the sheet-like body based on a phase relation of the two patterns Di, Dj in which a high frequency component has been removed by the high frequency component removing part 62.SELECTED DRAWING: Figure 5