Sheet thickness detecting device for detecting thickness from the change in distance between rollers

An image forming apparatus for forming an image on a sheet, said image forming apparatus comprising:

• image forming means and;
• a thickness detecting device for detecting the thickness of the sheet to be fed to said image forming means by detecting a change in distance between respective axes of a pair of rollers for pinching and feeding the sheet, said sheet thickness detecting device including:
• a pair of rollers for pinching and feeding the sheet;
• distance detecting means for detecting the distance between said pair of rollers;
• angle detecting means for detecting a state that one of said rollers is positioned only at a single predetermined angle of rotation;
• and
• judging means for judging the thickness of the sheet in accordance with a signal supplied from said distance detecting means when the sheet is not pinched by said pair of rollers in a position of the predetermined angle of rotation detected by said angle detecting means and a signal supplied from said distance detecting means when the sheet is pinched by said pair of rollers in the position of the predetermined angle of rotation.

A sheet thickness detecting device for detecting the thickness of a sheet, said sheet thickness detecting device comprising:

• a roller supported so as to be movable in the sheet thickness direction;
• first detecting means for detecting an amount of movement of said roller as it is abutted by the sheet conveyed from an upstream side in a sheet convey direction;
• second detecting means for detecting a state that said roller is positioned at a single predetermined angle of rotation;
• and
• judging means for judging the thickness of the sheet in accordance with a signal supplied from said first detecting means when the sheet doesn't abut said roller in a position of the predetermined angle of rotation detected by said second detecting means and a signal supplied from said first detecting means when the sheet abuts said roller in the position of the predetermined angle of rotation.

An image forming apparatus for forming an image on a sheet, said image forming apparatus comprising:

• image forming means;
• a roller supported so as to be movable in the sheet thickness direction;
• first detecting means for detecting an amount of movement of said roller as it is abutted by the sheet conveyed from and upstream side in a sheet convey direction;
• second detecting means for detecting a state that said roller is positioned at a single predetermined angle of rotation;
• judging means for judging the thickness of the sheet in accordance with a signal supplied from said first detecting means when the sheet doesn't abut said roller in a position of the predetermined angle of rotation detected by said second detecting means and a signal supplied from said first detecting means when the sheet abuts said roller in the position of the predetermined angle of rotation;
• and
• control means for controlling said image forming means in accordance with the judgement of said judging means.