An illuminating device according to an embodiment included in an image reading apparatus and an image forming apparatus includes light source portions, light-guiding members for illuminating an illumination target from an elongated light emitting face that extends in a longitudinal direction, by guiding light from the light source portions, and holding members for holding the light-guiding members. The holding members include holding portions for removably holding the light-guiding members, and tilted portions that reflect light emitted from the light emitting face, the tilted portions extending from a front end on the light emitting face side of the holding portions, obliquely widening with increasing distance from the light-guiding members.

In a first image formation mode, an image is formed with a first development contrast C1 and a specific dot pattern is formed with a second development contrast C2, which is lower than the first development contrast C1; in a second image formation mode, an image is formed with a third development contrast C3 and a specific dot pattern is formed with a fourth development contrast C4, which is lower than the third development contrast C3; and when C1 (=C2/C1) denotes a ratio between the second development contrast C2 and the first development contrast C1, and C2 (=C4/C3) denotes a ratio between the fourth development contrast C4 and the third development contrast C3, C2<C1 is satisfied.

An illuminating device (210) according to an embodiment of the invention included in an image reading apparatus (100) and an image forming apparatus (D) includes light source portions (211a1), (211b1), (211a2) and (211b2), light-guiding members (213a) and (213b) for illuminating an illumination target (G) from an elongated light emitting face (M) that extends in a longitudinal direction (Y), by guiding light from the light source portions, and holding members (216a) and (216b) for holding the light-guiding members. The holding members include holding portions (2161a) and (2161b) for removably holding the light-guiding members, and tilted portions (2162a) and (2162b) that reflect light emitted from the light emitting face (M), the tilted portions extending from a front end on the light emitting face (M) side of the holding portions, obliquely widening with increasing distance from the light-guiding members.

An ion writing unit includes a housing, an electrode assembly, and a heating mechanism. The housing includes a chamber at least partially containing an ion generator. The electrode assembly includes an array of electrode nozzles on one exposed exterior surface of the housing and aligned to receive and guide generated ions. The heating mechanism applies heat to at least one of the chamber and at least a portion of the array of electrode nozzles.

In a first image formation mode, an image is formed with a first development contrast C1 and a specific dot pattern is formed with a second development contrast C2, which is lower than the first development contrast C1; in a second image formation mode, an image is formed with a third development contrast C3 and a specific dot pattern is formed with a fourth development contrast C4, which is lower than the third development contrast C3; and when C1 (=C2/C1) denotes a ratio between the second development contrast C2 and the first development contrast C1, and C2 (=C4/C3) denotes a ratio between the fourth development contrast C4 and the third development contrast C3, C2<C1 is satisfied.

In the image forming method, a halftone image is generated by performing halftone processing for an input image, a scanned image of a printed material on which on which the halftone image is printed is obtained, and a failure component of an image forming apparatus is identified based on a difference between the scanned image and the input image. In the generation, the halftone image is generated by representing a dot pattern of a halftone portion in a case where the input image is a test image for the failure diagnosis by a dot pattern whose frequency is relatively higher than that of a dot pattern that is applied to the halftone portion in a case where the input image is an image other than the test image.

In the image forming method, a halftone image is generated by performing halftone processing for an input image, a scanned image of a printed material on which on which the halftone image is printed is obtained, and a failure component of an image forming apparatus is identified based on a difference between the scanned image and the input image. In the generation, the halftone image is generated by representing a dot pattern of a halftone portion in a case where the input image is a test image for the failure diagnosis by a dot pattern whose frequency is relatively higher than that of a dot pattern that is applied to the halftone portion in a case where the input image is an image other than the test image.

A method is described for adjusting the focus position of a linear printhead in a digital printing system. A line image is printed including a plurality of variable linewidth lines at different cross-track positions. A digital image capture system is used to capture an image of the printed line image, and a data processing system is used to automatically analyze the captured image to determine linewidth parameters representing linewidths of the plurality of lines. Linewidth progression functions are determined for the lines responsive to the determined linewidths, wherein the linewidth progression functions represent the linewidth parameters as a function of position. The linewidth progression functions are analyzed to determine defocus characteristics of the linear printhead, which are used to adjust the focus position of the linear printhead.

An optical scanning apparatus includes a polygonal mirror configured to deflect a light beam emitted from a light source such that the laser beam scans a member to be scanned, a drive motor configured to rotate the polygonal mirror, aboard on which the polygonal mirror and the drive motor are mounted, an installation portion where the board is installed, a rubber member provided between the board and the installation portion, and an adjustment unit configured to position on the board with respect to the installation portion and to adjust inclination of the board with respect to the installation portion by deforming the rubber member.

In an optical sensor, a light emission system emits an irradiated light of a linear polarization in a first polarization direction toward a surface of a target object having a sheet shape from an incident direction which is inclined with respect to a normal direction of the surface. A first light detection system includes a first light detector arranged on a first light path of a specular reflected light, which is emitted from the light emission system and is specularly reflected from the target object. A second light detection system includes a second light detector arranged on a second light path of a diffuse reflected light which is diffusely reflected from an incident plane on the target object. The second light detector receives second light passed by an optical element which passes a linear polarization component of a second polarization direction perpendicular to the first polarization direction.