An image-based acceptance learning device (2) learns a result of determination as to whether a planar object (1) is acceptable or defective based on at least one of a three-dimensional shape or a color on a surface of the planar object (1). The device (2) includes a surface image receiver (3) to receive an inputted two-dimensional data being image data of the surface of the planar object (1), a determination information receiver (4) to receive an inputted determination information indicating the result of determination as to whether the planar object (1) corresponding to the two-dimensional data is acceptable or defective, and a learner (5) to learn, based on the two-dimensional data and the determination information, a relevant area (1R) including the three-dimensional shape or the color on the surface in the two-dimensional data. The relevant area is a basis for the determination information.

There is provided a method of manufacturing an image sensor unit, the image sensor unit including: a linear light source that illuminates a document along a main scanning direction; a rod lens array that includes a plurality of rod lenses arranged in the main scanning direction and condenses a light reflected from the document; and a linear image sensor that receives a light condensed by the rod lens array. When a rod lens having an optically discontinuous portion on a surface and/or interior of the rod lens is included, the rod lens array is arranged such that the optically discontinuous portion is not located toward the document.

There is provided a method of manufacturing an image sensor unit, the image sensor unit including: a linear light source that illuminates a document along a main scanning direction; a rod lens array that includes a plurality of rod lenses arranged in the main scanning direction and condenses a light reflected from the document; and a linear image sensor that receives a light condensed by the rod lens array. When a rod lens having an optically discontinuous portion on a surface and/or interior of the rod lens is included, the rod lens array is arranged such that the optically discontinuous portion is not located toward the document.

According to an embodiment, a reading device that reads an object to be read in an image forming apparatus includes a lens array and a light guide. The lens array is provided in a posture in which an optical axis follows a height direction intersecting a reading surface. The light guide is adjacent to the lens array in a sub-scanning direction intersecting both the height direction and a main scanning direction, and locates maximum illuminance of illumination light illuminating the object to be read on a side opposite to the lens array with respect to a deepest position of a depth of field of the lens array in the height direction.

An optical device includes a lens body including plural lenses of which optical axes are arranged alongside each other, and having an intermediate image forming surface for forming an erect real image of equal magnification formed in an optical path, a light shielding body that is provided to face a light incident surface of the lens body, and includes a transmitting portion that is positioned on the optical axes of the plural lenses and transmits light and a light shielding unit that is positioned on a portion other than the optical axes of the plural lenses and shields the passage of light, and a regulating body that is provided to face a light incident surface of the light shielding body, includes an opening narrower than the transmitting portion, and regulates a part of light toward the transmitting portion.

An image reading device includes a plurality of light-receiving pixels configured to receive reflected light; a first light-shielding member including a plurality of first openings and disposed between the plurality of light-receiving pixels and a reference surface; a second light-shielding member including a plurality of second openings and disposed between the plurality of first openings and the reference surface; and a plurality of condenser lenses disposed at a distance from the plurality of second openings. The plurality of condenser lenses, the second light-shielding member, the first light-shielding member, and the plurality of light-receiving pixels are disposed at positions at which reflected light sequentially passes through one of the condenser lenses corresponding to each light-receiving pixel, one of the second openings corresponding to the each light-receiving pixel, and one of the first openings corresponding to the each light-receiving pixel and enters the each light-receiving pixel.

An image reading device includes a lens array including lenses arranged in a main scanning direction and forming an erect unmagnified optical system to converge light from a reading target, a holder holding the lens array, a light receiver to receive the light converged by the lenses, and slit units. Each slit unit includes three or more light shielding plates each separating an optical path of one lens from an optical path of another lens between the lens array and the light receiver, and side plates disposed on two sides of the light shielding plates in a direction intersecting the main scanning direction and connecting two adjacent light shielding plates. The slit units are arranged in the main scanning direction, and each two adjacent slit units are arranged with a space therebetween for one optical path of one lens.

The image forming apparatus includes a sheet conveyance part, an image forming part, and a sheet reading unit. The sheet reading unit includes a line sensor. The line sensor includes split line sensors. The line sensor reads a conveyed sheet. The line sensor includes a plurality of split line sensors. The split line sensors are placed at non-stretching positions, respectively. Each non-stretching position is such a position that as in the main scanning direction, a main-scanning-direction distance from a gap between one split line sensor and another split line sensor to an ideal edge position of every usable regular size exceeds a permissible value.

Methods and systems for blending line image data streams from a film scanner are disclosed. In one embodiment, a method is provided including receiving multiple data streams from line scan sensors. An overlap position may then be initially selected, which forms an overlap position between two of the data streams. A difference measure may then be calculated between the two data streams within the overlap area. The overlap positions may then be iteratively altered between a plurality of overlap positions, and additional difference measures may be computed for each overlap position. A blending position may then be selected from the plurality of overlap positions, which may correspond to the overlap position with the smallest difference measure. The data streams may then be blended at the selected blending position.

A lens array includes a flat plate-shaped base part, a plurality of lenses, a plurality of columnar light guiding parts and a plurality of light shielding parts. The lenses are formed on one surface of the base part. The columnar light guiding parts are formed on another surface of the base part at points corresponding to the lenses. The light shielding parts are formed at least on lateral surfaces of the light guiding parts.