A relative position detection method detecting a position of a light-emitting member relative to a lens array or a position of the lens array relative to the light-emitting member, in which the light-emitting member includes light-emitting elements arranged in a first direction and the lens array includes lenses arranged in the first direction and condenses light from the light-emitting elements to image positions of the light-emitting elements, optical axes of the lenses being orthogonal to the first direction. The method includes: causing the light-emitting elements to emit light; detecting, at a position displaced from the image positions along an optical axis direction, optical intensity distribution of light emitted from the light-emitting elements and transmitted through the lens array; and detecting a position of the light-emitting member relative to the lens array or a position of the lens array relative to the light-emitting member with use of the optical intensity distribution.

An exposure unit includes first and second exposure heads. The first exposure head includes: first light emitting devices each emitting a first light beam; a first optical system performing imaging of each of the first light beams; a first coupler; and a first base member. The first coupler is provided at a first position, in the first base member, based on a position at which the imaging performed by the first optical system is performed. The second exposure head includes: second light emitting devices each emitting a second light beam; a second optical system performing imaging of each of the second light beams; a second coupler; and a second base member. The second coupler is provided at a second position, in the second base member, based on a position at which the imaging performed by the second optical system is performed and is fit into the first coupler.

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.

An optical print head including a light emitting member, an optical member, a detection unit, and a correction unit. The light emitting member is elongated in a longitudinal direction with light emitting elements arranged along the longitudinal direction. The optical member is elongated in the longitudinal direction with optical elements arranged along the longitudinal direction, the optical elements collecting light emitted by the light emitting elements. The detection unit detects an index value of linear expansion difference in the longitudinal direction of the light emitting member and the optical member. The correction unit uses the index value to correct an emitted light amount for each of the light emitting elements in order to offset differences in light collection efficiency caused by the linear expansion difference.

A static eliminator of the present disclosure includes a light source and a rod-shaped light guide member. The light guide member includes one end surface which light from the light source enters, and emits the light which has entered the one end surface toward an image carrying member. The light guide member includes a reflection portion which reflects light and a light emission surface which emits the light toward the image carrying member. In the one end surface, a concave portion is formed that includes a concave curved surface which is formed in the shape of an arc in a first direction along a direction of light emission extending from the reflection portion toward the image carrying member.

An LED head includes a base material having one or more wiring pattern formation surfaces and one or more metal wiring patterns formed on the one or more wiring pattern formation surfaces. When the occupancy ratio of the one or more metal wiring patterns in a first region of a substrate is A, and the occupancy ratio of the one or more metal wiring patterns in a second region of the substrate is B, the LED head satisfies 0.75A/B1 or 0.75B/A1.

A lens unit according to an embodiment includes: lens members in each of which lenses are linearly arrayed in a longitudinal direction; at least one light block member between the lens members; engagement sections arranged in the longitudinal direction, each of the engagement sections configured to mutually engage members including the lens members and the light block member and stacked with each other; and clamp members disposed in positions corresponding to at least one of the engagement sections in the longitudinal direction and configured to clamp the stacked members. All the stacked members are fixed with each other at only one portion in the longitudinal direction.

The invention describes a laser printing system (100) for illuminating an object moving relative to a laser module of the laser printing system (100) in a working plane (180), the laser module comprising at least two laser arrays of semiconductor lasers and at least one optical element, wherein the optical element is adapted to image laser light emitted by the laser arrays, such that laser light of semiconductor lasers of one laser array is imaged to one pixel in the working plane of the laser printing system, and wherein the laser printing system is a 3D printing system for additive manufacturing and wherein two, three, four or a multitude of laser modules (201, 202) are provided, which are arranged in columns (c1, c2) perpendicular to a direction of movement (250) of the object in the working plane (180), and wherein the columns are staggered with respect to each other such that a first laser module (201) of a first column of laser modules (c1) is adapted to illuminate a first area (y1) of the object and a second laser module (202) of a second column (c2) of laser modules is adapted to illuminate a second area (y2) of the object, wherein the first area (y1) is adjacent to the second area (y2) such that continuous illumination of the object is enabled.

An exposure head configured to expose a photoreceptor includes a substrate having a plurality of light emitting portions, a lens array having a plurality of lenses that condense light emitted from the light emitting portions onto the photoreceptor, and a holder that holds the substrate and the lens array. The holder has an opposing surface including an opening into which the lens array is inserted and facing the photoreceptor in an optical axis direction of the lens. The opposing surface has a contacting surface on which a cleaning rod cleaning a light exit surface of the lens array abuts. The holder includes a sealing agent that seals a gap between a side wall of the lens array and an edge of the opening along a longitudinal direction of the holder, and a groove formed in the opposing surface between the opening and the contacting surface. The sealing agent is applied between the groove and the side wall.

Provided is a rod lens array that includes: a plurality of lenses; and a pair of side plate sections interposing side surfaces of the respective lenses in between to hold the lenses, and each including a first side plate provided adjacent to the lenses, and a second side plate provided on outer side of the first side plate, and having machinability lower than machinability of the first side plate, and a linear expansion coefficient smaller than linear expansion coefficient of the first side plate.