PAPER THICKNESS DETECTION DEVICE AND IMAGE FORMING APPARATUS WITH PAPER THICKNESS DETECTION DEVICE

PROBLEM TO BE SOLVED: To provide a high-accuracy paper thickness detection device featuring little variation in detection results by minimizing the effects of eccentricity of a roller.SOLUTION: The paper thickness detection device according to the present invention comprises: a rotationally driven driving roller 6; a driven roller 12 driven to rotate by rotation of the driving roller 6; a sensor HS for detecting the displacement of the driven roller 12; a central processing unit CPU which determines an average calculation section width T1 corresponding to a rotational period of the driven roller 12 and an average calculation time difference T2 corresponding to a rotational period of the driving roller 6 from a paper-feeding-state observation waveform PW meaning the output variation of the sensor HS, and which determines an average output difference V between an average output of the sensor HS within the average calculation section width T1 in a paper-absent state of the paper-feeding-state observation waveform PW and an average output of the sensor HS within the average calculation section with T1 in a paper-present state after elapse of the average calculation time difference T2; and a memory unit MEMO for beforehand storing the relation between the average output difference V and the paper thickness x as data. The central processing unit CPU calculates the paper thickness x from the average output difference V and the data stored in the memory unit MEMO. 【課題】ローラの偏心による影響を極力除去して、ばらつきの少ない高精度な紙厚検出装置を提供する。【解決手段】本発明は、回転駆動される駆動ローラ６と、駆動ローラ６により従動回転される従動ローラ１２と、従動ローラ１２の変位を検出するセンサHSと、従動ローラ１２の回転周期に相当する平均算出区間幅T1と駆動ローラ６の回転周期に相当する平均算出時間差T2とをセンサHSの出力の変動を意味する通紙状態観測波形PWから求めると共に、通紙状態観測波形PWの紙なし状態における平均算出区間幅T1内のセンサの平均出力と平均算出時間差T2経過後の紙あり状態における平均算出区間幅T1内のセンサHSの平均出力との差である平均出力差 Vを求める演算処理装置CPUと、平均出力差 Vと紙厚ｘとの関係をデータとして予め記憶する記憶部MEMOとを備え、演算処理装置CPUは、平均出力差 Vと記憶部に記憶されたデータとから通紙状態における紙厚ｘを算出する。【選択図】 図４７