Image reading apparatus with correction of image signals
First Claim
Patent Images
1. An image reading apparatus for reading an open book document placed face up on a document table by optical scanning comprising:
- a mirror arranged along a lateral side of the document table in a subscanning direction and which reflects a lateral side view of the book document placed on the document table;
a projection lens disposed above the document table and which projects an image of the book document placed on the document table and the lateral side view of the book document reflected on the mirror;
a scanner disposed above the projection lens which includes a line sensor arranged along a main scanning direction and sequentially moves a reading position of the line sensor in the subscanning direction, wherein the line sensor captures an image of the book document projected by the projection lens and the lateral side view of the book document reflected on the mirror to generate image signals at every reading position;
detection means for detecting a height of the book document placed on the document table at every reading position based on the image signal of the lateral side view of the book document; and
correction means for correcting the detected height of the book document at every reading position based on a deviation between a position of the image of the book document projected on the line sensor and a position of the lateral side view of the book document projected on the line sensor with respect to the subscanning direction.
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Abstract
An image reading apparatus for reading a document such as book, constructed to detect a height of the document. A line sensor captures an image of the document and a lateral side view of the document reflected on a mirror. Then the height of the document detected by the line sensor is corrected based on a deviation between a positions of the document image projected on the line sensor and the lateral side view of the document projected on the line sensor.
36 Citations
16 Claims
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1. An image reading apparatus for reading an open book document placed face up on a document table by optical scanning comprising:
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a mirror arranged along a lateral side of the document table in a subscanning direction and which reflects a lateral side view of the book document placed on the document table; a projection lens disposed above the document table and which projects an image of the book document placed on the document table and the lateral side view of the book document reflected on the mirror; a scanner disposed above the projection lens which includes a line sensor arranged along a main scanning direction and sequentially moves a reading position of the line sensor in the subscanning direction, wherein the line sensor captures an image of the book document projected by the projection lens and the lateral side view of the book document reflected on the mirror to generate image signals at every reading position; detection means for detecting a height of the book document placed on the document table at every reading position based on the image signal of the lateral side view of the book document; and correction means for correcting the detected height of the book document at every reading position based on a deviation between a position of the image of the book document projected on the line sensor and a position of the lateral side view of the book document projected on the line sensor with respect to the subscanning direction. - View Dependent Claims (2, 3, 4, 5)
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6. An image reading apparatus for reading an open book document placed face up on a document table by optical scanning comprising:
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a mirror arranged along a lateral side of the document table in a subscanning direction and which reflects a lateral side view of the book document placed on the document table; a projection lens disposed above the document table and which projects an image of the book document placed on the document table and the lateral side view of the book document reflected on the mirror, wherein said projection lens is movable only along the direction of an optical axis thereof; a scanner disposed above the projection lens which includes a line sensor arranged along a main scanning direction and sequentially moves a reading position of the line sensor in the subscanning direction, wherein the line sensor captures an image of the book document projected by the projection lens and the lateral side view of the book document reflected on the mirror to generate image signal at every reading position; detection means for detecting a height of the book document placed on the document table at every reading position based on the image signal of the lateral side view of the book document; and correction means for correcting the detected height of the book document at every reading position based on a deviation between a position of the image of the book document projected on the line sensor and a position of the lateral side view of the book document projected on the line sensor with respect to the subscanning direction, wherein said deviation is generated from the movement of the projection lens in the direction of the optical axis thereof. - View Dependent Claims (7, 8, 9, 10)
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11. An image reading apparatus for reading a book document placed face up on a document table by optical scanning comprising:
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a mirror arranged along a lateral side of the document table in a subscanning direction and which reflects a lateral side view of the book document placed on the document table; a projection lens disposed above the document table and which projects an image of the book document placed on the document table and the lateral side view of the book document reflected on the mirror; a line sensor arranged above the projection lens and along a main scanning direction and sequentially moves in the subscanning direction, wherein the line sensor captures an image of the book document projected by the projection lens and the lateral side view of the book document reflected on the mirror to generate an image signal; detection means for detecting a height of the book document placed on the document table based on the image signal of the lateral side view of an book document; and correction means for correcting the detected height of the book document at a reading position based on a deviation between a position of the image of the book document projected on the line sensor and the lateral side view of the book document projected on the line sensor with respect to the subscanning direction, wherein said reading position is the position at which the prolongation line of the optical path connecting the line sensor and a principal point of the lens intersects the document table. - View Dependent Claims (12, 13)
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14. An image reading apparatus for reading an open book document placed face up on a document table by scanning comprising:
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means for providing an image of a lateral side view of the book document; a projection lens disposed above the document table and which projects an image of the book document placed on the document table and a lateral side view of the book document; a scanner disposed above the projection lens which includes an image sensor, wherein the image sensor captures an image of the book document and the lateral side view of the book document projected by the projection lens to generate an image signal at every reading position; means for moving the scanner to enable the generation of the image signal; detection means for detecting a height of the book document placed on the document table at every reading position based on the image signal of the lateral side view of the book document; and correction means for correcting the detected height of the book document at every reading position based on a deviation between a position of the image of the book document and a position of the lateral side view of the book document. - View Dependent Claims (15, 16)
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Specification