Sheet detecting device
AssigneeCanon Kabushiki Kaisha
InventorShunzo Inoue
Life of this patent
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Abstract
A device in which a light source and a light receiving element are disposed at one side of a sheet transportation path and a reflecting member is disposed at the other side of the sheet transportation path so that a light ray emitted from the light source is reflected by the reflecting surface of the reflecting member and is caused to enter the light receiving element and any variation in the quantity of light entering the light receiving element is detected to thereby detect the presence of a sheet. The reflecting member is disposed such that the angle formed by the normal to the reflecting member with the surface of the sheet placed at the detection position is equal to or smaller than the critical angle at which total reflection is created on the surface of the sheet.
Claims14
A sheet detecting device for detecting a sheet advancing along a predetermined path comprising:
- a light source for emitting a light ray in a predetermined direction of said path;
- a light reflecting member disposed at a position opposite to said light source in respect of said path, said light reflecting member being disposed such that the angle formed by a bisecting line between the light incident on said light reflecting member and the light reflected by said light reflecting member with a line normal to the surface of the sheet is larger than the critical angle causing the total reflection of the ray on the surface of the sheet;
- and
- a light receiving element disposed at a position opposite to said light reflecting member in respect of said path for receiving the light ray of the light source reflected by said light reflecting member.
Dependencies are inferred from the claim text.