An image sensor unit includes: a linear light source that illuminates a document with a light; a first erecting equal-magnification lens array and a second erecting equal-magnification lens array arranged in the stated order away from the document so as to receive a light reflected from the document and form an erecting equal-magnification image; a slit provided on an intermediate imaging plane between the first erecting equal-magnification lens array and the second erecting equal-magnification lens array; a diffraction grating that disperses a light output from the second erecting equal-magnification lens array; and a linear image sensor that receives a light dispersed by the diffraction grating.

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 (100) includes a first glass member (52), a plurality of condensing lenses (14) provided on a first surface (52a) of the first glass member (52), a first light blocking member (12) having a plurality of first openings (32) respectively corresponding to the plurality of condensing lenses (14), a second glass member (51) having a third surface (51a) in superimposition with the first light blocking member (12), a second light blocking member (11) having a plurality of second openings (31) respectively corresponding to the plurality of first openings (32), a third glass member (53) having a fifth surface (53a) in superimposition with the second light blocking member (11), a third light blocking member (15) having a plurality of third openings (34) respectively corresponding to the plurality of second openings (31), and a sensor unit (3) having a sensor substrate (9) and a plurality of light receiving pixels (10) arrayed in a predetermined array direction on the sensor substrate (9) and respectively corresponding to the plurality of third openings (34).

An optical device includes: a lens body including plural lenses arranged such that optical axes of the plural lenses extend along each other; and a light-blocking body disposed on a light incident side of the lens body and including light-transmitting portions that transmit light and light-blocking portions that block light, the light-transmitting portions and the light-blocking portions being continuously arranged in an alternating manner such that the light-transmitting portions are positioned at the plural lenses and that the light-blocking portions are positioned between the plural lenses.

An optical element of a lens mirror array according to an embodiment includes an incident-side lens surface, a first reflection surface, a second reflection surface, an emission-side lens surface, a first positioning surface, and a second positioning surface. The incident-side lens surface refracts and converges incident light. The first reflection surface reflects light made incident via the incident-side lens surface. The second reflection surface reflects the light reflected by the first reflection surface. The emission-side lens surface emits the light reflected by the second reflection surface. The lens mirror array is a lens mirror array in which a plurality of optical elements are arrayed in a direction orthogonal to optical axes of the incident light and the reflected light and parallel to the first positioning surface.

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.

An exposure device includes a plate member, a plurality of light-emitting elements, and an optical system. The plate member extends in both a first direction and a second direction intersecting with the first direction. The light-emitting elements are disposed on the plate member side by side in the first direction. The light-emitting elements emit respective light beams in the second direction. The optical system is disposed on the plate member and faces the light-emitting elements in the second direction. The optical system performs imaging of the light beams emitted by the respective light-emitting elements.

A first lens body and a second lens body are fixed to, using an adhesive layer, a surface of a lens fixing plate determined by intersection of a straight line in an optical axis direction and a straight line in a longitudinal direction, such that the lens fixing plate in which a lens fixing plate opening is formed in a lateral direction overlaps, when viewed in the lateral direction, at least a portion of a junction at which the first lens body and the second lens body are bonded to each other. A first adjustment member is brought into contact with the first lens body via at least one hole into which the first adjustment member is inserted A second adjustment member is brought into contact with the second lens body via at least one hole and into which the second adjustment member is inserted.

An image reading device includes a plurality of light receiving parts arrayed regularly, a first light blocking member including a plurality of first openings arrayed corresponding respectively to the plurality of light receiving parts, and a plurality of microlenses arrayed corresponding respectively to the plurality of first openings. Each light receiving part included in the plurality of light receiving parts includes a plurality of light receiving pixels arrayed in a first direction as a main scanning direction. Each microlens included in the plurality of microlenses is object side telecentric. The plurality of microlenses, the first light blocking member and the plurality of light receiving parts are arranged so that light reflected by an object and passing through the microlens and the first opening corresponding to the microlens enters the plurality of light receiving pixels included in the light receiving part corresponding to the first opening.

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.