Image reading apparatus
First Claim
1. An image reading apparatus for reading an image on a sheet, comprising:
- image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image;
a white reference image part provided within said predetermined area so as to be scanned by the image reading means;
a black reference image part provided within said predetermined area so as to be scanned by the image reading means;
white reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the white reference image part, for storing the output image signal supplied thereto;
black reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the black reference image part, for storing the output image signal supplied thereto;
image correction means supplied with the output image signal from the image reading means line sequentially in response to the image reading means scanning the sheet, said image correction means being supplied further with a first reference signal indicative of the image signal stored in the white reference memory means and with a second reference signal indicative of the image signal stored in the black reference memory, for producing a corrected image signal so that the corrected image signal has a maximum level corrected with reference to the first reference signal and a minimum level corrected with reference to the second reference signal; and
control means for controlling the white reference memory means and the black reference memory means so that the white reference memory means stores the output image signal of the image reading means only when the image reading means scans the white reference image part and so that the black reference memory means stores the output image signal of the image reading means only when the image reading means scans the black reference image part;
wherein said image correction means comprises an analog-to-digital converter supplied with the output image signal from the image reading means for producing a digital image data, said analog-to-digital converter being supplied with the first reference signal and the second reference signal from respectively the white and black reference memory means for setting the range of the incoming image signal from the image reading means, and said digital image data being supplied selectively to the white reference memory means and to the black reference memory means under the control of the control means; and
wherein said white reference memory means and said black reference memory means comprise first and second line buffers for storing the digital image data corresponding to one line and first and second analog-to-digital converters respectively connected to the first and second line buffers for producing said first and second reference signals.
1 Assignment
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Accused Products
Abstract
An image reading apparatus for reading an image on a sheet. The apparatus comprises an image reading part for scanning a predetermined area, including the sheet, one scanning line by one scanning line for producing an output image signal. A white reference image part is provided within the predetermined area so as to be scanned by the image reading part. A black reference image part is provided within the predetermined area so as to be scanned by the image reading part. A white reference memory is supplied with the output image signal from the image reading part for storing the output image signal supplied thereto, and a black reference memory is supplied with the output image signal from the image reading part for storing the output image signal supplied thereto. An image correction part is supplied with the output image signal from the image reading part and further with a first reference signal and a second reference signal from the white and black reference memories for producing a corrected image signal. A controller controls the reading operation of the white reference memory and the black reference memory. In the image forming apparatus, the effect of shading is eliminated, the quality of image recording is improved, and the size of the sheet on which the image to be read can be detected.
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Citations
13 Claims
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1. An image reading apparatus for reading an image on a sheet, comprising:
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image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image; a white reference image part provided within said predetermined area so as to be scanned by the image reading means; a black reference image part provided within said predetermined area so as to be scanned by the image reading means; white reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the white reference image part, for storing the output image signal supplied thereto; black reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the black reference image part, for storing the output image signal supplied thereto; image correction means supplied with the output image signal from the image reading means line sequentially in response to the image reading means scanning the sheet, said image correction means being supplied further with a first reference signal indicative of the image signal stored in the white reference memory means and with a second reference signal indicative of the image signal stored in the black reference memory, for producing a corrected image signal so that the corrected image signal has a maximum level corrected with reference to the first reference signal and a minimum level corrected with reference to the second reference signal; and control means for controlling the white reference memory means and the black reference memory means so that the white reference memory means stores the output image signal of the image reading means only when the image reading means scans the white reference image part and so that the black reference memory means stores the output image signal of the image reading means only when the image reading means scans the black reference image part; wherein said image correction means comprises an analog-to-digital converter supplied with the output image signal from the image reading means for producing a digital image data, said analog-to-digital converter being supplied with the first reference signal and the second reference signal from respectively the white and black reference memory means for setting the range of the incoming image signal from the image reading means, and said digital image data being supplied selectively to the white reference memory means and to the black reference memory means under the control of the control means; and wherein said white reference memory means and said black reference memory means comprise first and second line buffers for storing the digital image data corresponding to one line and first and second analog-to-digital converters respectively connected to the first and second line buffers for producing said first and second reference signals. - View Dependent Claims (2, 3)
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4. An image reading apparatus for reading an image on a sheet, comprising:
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image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image; a white reference image part provided within said predetermined area so as to be scanned by the image reading means; a black reference image part provided within said predetermined area so as to be scanned by the image reading means; white reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the white reference image part, for storing the output image signal supplied thereto; black reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the black reference image part, for storing the output image signal supplied thereto; image correction means supplied with the output image signal from the image reading means line sequentially in response to the image reading means scanning the sheet, said image correction means being supplied further with a first reference signal indicative of the image signal stored in the white reference memory means and with a second reference signal indicative of the image signal stored in the black reference memory, for producing a corrected image signal so that the corrected image signal has a maximum level corrected with reference to the first reference signal and a minimum level corrected with reference to the second reference signal; and control means for controlling the white reference memory means and the black reference memory means so that the white reference memory means stores the output image signal of the image reading means only when the image reading means scans the white reference image part and so that the black reference memory means stores the output image signal of the image reading means only when the image reading means scans the black reference image part; wherein said image reading means comprises a movable optical system provided so as to be moved by the controller at least to such an extent that the optical system scans the white reference image part and the black reference image part; and wherein said movable optical system comprises a movable mirror supported rotatably about an axis extending in a direction parallel to the scan of the image reading means, said movable mirror being controlled by the controller between a first state and a second state so that the image reading means produces the output image data corresponding to the white reference image part when the mirror is in the first state and the output image data corresponding to the black reference image part when the mirror is in the second state.
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5. An image reading apparatus for reading an image on a sheet, comprising:
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image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image; a white reference image part provided within said predetermined area so as to be scanned by the image reading means; a black reference image part provided within said predetermined area so as to be scanned by the image reading means; white reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the white reference image part, for storing the output image signal supplied thereto; black reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the black reference image part, for storing the output image signal supplied thereto; image correction means supplied with the output image signal from the image reading means line sequentially in response to the image reading means scanning the sheet, said image correction means being supplied further with a first reference signal indicative of the image signal stored in the white reference memory means and with a second reference signal indicative of the image signal stored in the black reference memory, for producing a corrected image signal so that the corrected image signal has a maximum level corrected with reference to the first reference signal and a minimum level corrected with reference to the second reference signal; control means for controlling the white reference memory means and the black reference memory means so that the white reference memory means stores the output image signal of the image reading means only when the image reading means scans the white reference image part and so that the black reference memory means stores the output image signal of the image reading means only when the image reading means scans the black reference image part; and sheet feeding means for so feeding the sheet that the image on the sheet is scanned by the image reading means in response to the feeding of the sheet; wherein said image reading means comprises a movable optical system provided so as to be moved by the controller at least to such an extent that the optical system scans the white reference image part and the black reference image part. - View Dependent Claims (6)
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7. An image reading apparatus for reading an image on a sheet, comprising:
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image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image; a white reference image part provided within said predetermined area so as to be scanned by the image reading means; a black reference image part provided within said predetermined area so as to be scanned by the image reading means; white reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the white reference image part, for storing the output image signal supplied thereto; black reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the black reference image part, for storing the output image signal supplied thereto; image correction means supplied with the output image signal from the image reading means line sequentially in response to the image reading means scanning the sheet, said image correction means being supplied further with a first reference signal indicative of the image signal stored in the white reference memory means and with a second reference signal indicative of the image signal stored in the black reference memory, for producing a corrected image signal so that the corrected image signal has a maximum level corrected with reference to the first reference signal and a minimum level corrected with reference to the second reference signal; and control means for controlling the white reference memory means and the black reference memory means so that the white reference memory means stores the output image signal of the image reading means only when the image reading means scans the white reference image part and so that the black reference memory means stores the output image signal of the image reading means only when the image reading means scans the black reference image part; wherein said white reference image part and said black reference image part are carried on a movable part which is moved by the controller between a first state and a second state so that the image reading means scans the white reference image part when the movable part is in the first state and the black reference image part when the movable part is in the second state. - View Dependent Claims (8, 9)
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10. An image reading apparatus for reading an image on a sheet, comprising:
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image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image; a white reference image part provided within said predetermined area so as to be scanned by the image reading means; a black reference image part provided within said predetermined area so as to be scanned by the image reading means; white reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the white reference image part, for storing the output image signal supplied thereto; black reference memory means supplied with the output image signal from the image reading means in response to the image reading means scanning the black reference image part, for storing the output image signal supplied thereto; image correction means supplied with the output image signal from the image reading means line sequentially in response to the image reading means scanning the sheet, said image correction means being supplied further with a first reference signal indicative of the image signal stored in the white reference memory means and with a second reference signal indicative of the image signal stored in the black reference memory, for producing a corrected image signal so that the corrected image signal has a maximum level corrected with reference to the first reference signal and a minimum level corrected with reference to the second reference signal; and control means for controlling the white reference memory means and the black reference memory means so that the white reference memory means stores the output image signal of the image reading means only when the image reading means scans the white reference image part and so that the black reference memory means stores the output image signal of the image reading means only when the image reading means scans the black reference image part; wherein said white reference image part and said black reference image part are provided in parallel to the scanning line so as to alternately repeat the white reference image part and the black reference image part, and the control means controls the white reference memory means and the black reference memory means such that the output image data corresponding to the white reference image part is stored in the white reference memory means and the output image data corresponding to the black reference image part is stored in the black reference memory means.
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11. An image reading apparatus for reading an image on a sheet and detecting the size of the sheet, comprising:
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image reading means for scanning a predetermined area including the sheet scanning line by scanning line, said image reading means reading an image pattern on the predetermined area including the image on the sheet and producing an output image signal indicative of the image; a white reference image part provided within said predetermined area so as to be scanned by the image reading means, said white reference image part being adapted such that the sheet is passed above the white reference image part when the image reading means scans the predetermined area; a black reference image part provided within said predetermined area so as to be scanned by the image reading means, said black reference image part being adapted so that the sheet is passed above the black reference image part when the image reading means scans the predetermined area; sheet feeding means for feeding the sheet passing above the white reference image part and the black reference image part so that the sheet is scanned by the image reading means; control means for controlling the image reading means so that the image reading means scans the sheet in correspondence to where the sheet passes above the white reference image part and in correspondence to where the sheet passes above the black reference image part; and sheet width detection means supplied with the output image signals of the image reading means obtained in correspondence to the image reading means reading a first image pattern wherein the sheet is passed above the white reference image part and in correspondence to the image reading means reading a second image pattern wherein the sheet is passed above the black reference image part, for detecting the width of the sheet measured along the scanning line. - View Dependent Claims (12, 13)
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Specification