Scanning-type image reading device
First Claim
Patent Images
1. A scanning-type image reading device, comprising:
- an imaging lens that forms an image of an object;
a linear image sensor that captures said image formed by said imaging lens, said linear image sensor including a plurality of aligned light receiving elements that output image signals;
a rotating-type scanning system that scans said image on said linear image sensor, such that said linear image sensor outputs a plurality of scanning lines to form two-dimensional image data;
a distance changing system that changes a distance between said imaging lens and said linear image sensor; and
a controller that controls said distance changing system, said controller determining a reference in-focus distance between said imaging lens and said linear image sensor at a reference position of said scanning system, controlling said distance changing system to set said reference in-focus distance, and controlling said distance changing system in accordance with said reference in-focus distance and a rotational position of said scanning system such that said imaging lens forms an in-focus image on a predetermined target area of said image sensor for each scanning line.
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Abstract
A scanning-type image reading device is provided which includes an image sensor, a rotating-type scanning system, a focusing mechanism, and a controller. The controller may control the focusing mechanism for each rotational position of the rotating-type scanning system. In a particular case, the controller may control the focusing mechanism according to the rotational position of the rotating-type scanning system and according to an initial position of the focusing mechanism determined at a predetermined position of the rotating-type scanning system.
37 Citations
17 Claims
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1. A scanning-type image reading device, comprising:
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an imaging lens that forms an image of an object; a linear image sensor that captures said image formed by said imaging lens, said linear image sensor including a plurality of aligned light receiving elements that output image signals; a rotating-type scanning system that scans said image on said linear image sensor, such that said linear image sensor outputs a plurality of scanning lines to form two-dimensional image data; a distance changing system that changes a distance between said imaging lens and said linear image sensor; and a controller that controls said distance changing system, said controller determining a reference in-focus distance between said imaging lens and said linear image sensor at a reference position of said scanning system, controlling said distance changing system to set said reference in-focus distance, and controlling said distance changing system in accordance with said reference in-focus distance and a rotational position of said scanning system such that said imaging lens forms an in-focus image on a predetermined target area of said image sensor for each scanning line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A scanning-type image reading device comprising:
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an imaging lens; an image sensor comprising a plurality of linearly aligned light receiving elements, said image sensor being arranged perpendicular to an optical axis of said imaging lens; a scanning mirror arranged between said imaging lens and an object, said scanning mirror being rotatable about an axis parallel to said image sensor and positioned on said optical axis; a scanning system that rotates said scanning mirror such that said imaging lens sequentially forms a plurality of images corresponding to different portions of said object on said image sensor, said image sensor outputting a corresponding plurality of scanning lines representing said plurality of images, said scanning system rotating said scanning mirror through a predetermined scanning range including at least one predetermined reference position, a focusing mechanism that drives said imaging lens along said optical axis; and a controller that controls said focusing mechanism in accordance with operation of said scanning system and a reference in-focus position of said imaging lens, said reference in-focus position being calculated when said scanning system is located at said predetermined reference position. - View Dependent Claims (14, 15)
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16. A scanning-type image reading device comprising:
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an imaging lens; an image sensor comprising a plurality of linearly aligned light receiving elements, said image sensor arranged to intersect an optical axis of said imaging lens at right angles; a rotating-type scanning system arranged in relation to said imaging lens, said imaging sensor, and an object, such that, during rotation of said scanning system, said imaging lens forms a plurality of images on said image sensor, said image sensor outputting a corresponding plurality of scanning lines representing said plurality of images; a focusing mechanism for driving said imaging lens along said optical axis; a controller which, based on a predetermined focusing condition obtained at a predetermined scanning position of said scanning system, controls said focusing mechanism to substantially maintain said predetermined focusing condition throughout said rotation of said scanning system when said object is a two dimensional surface arranged having a predetermined arrangement with respect to said scanning system; wherein said predetermined focusing condition is obtained by setting said predetermined scanning position and operating said focusing mechanism until an in-focus image is formed on said image scanner.
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17. A scanning-type image reading device comprising:
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an imaging lens; a rotating-type scanning system; a linear image sensor, wherein an image of an object is scanned by driving said scanning system and said image sensor in a step-wise manner, and wherein said imaging lens is positioned between said object and said image sensor and a position of said imaging lens when said image of said object is scanned is determined in accordance with a position of said scanning system and an initial position of said lens, said initial position determined when said scanning system is at a predetermined position; wherein said initial position is an in-focus position.
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Specification