An image reading device includes an image reading unit that reads an image while moving in a sub-scanning direction, a casing that houses the image reading unit, a guiding member that is movable relative to the casing in the sub-scanning direction and guides the casing in the sub-scanning direction, and an endless member to which the casing is fixed and that endlessly travels between a starting position and a terminal position in the sub-scanning direction.

A driving device is used in an image reading apparatus, and reciprocates a scanning unit for reading an image on an original. The driving device comprises a pull member, a driving pulley which transmits driving force to the pull member, a following pulley which applies tension to the pull member and a pulley holder having a pulley axis which holds the following pulley rotatably. Then, the pulley axis has a lock pawl capable of locking an upper end portion of the following pulley and canceling engagement with the following pulley by being tilted toward a side of an axial center by elastic deformation. Furthermore, the lock pawl is arranged at a side of a tension acting direction from the pull member to the following pulley except the farthest position from the driving pulley among positions in a circumferential direction of the pulley axis. It is possible to attach and detach the following pulley easily at a time of maintenance or the like.

An image sensor unit includes a light condenser that collects light from a reading target object; an image sensor that receives light and converts the light into an electric signal; an elongated housing that houses the light condenser and the image sensor; and an elongated rigid member attached to a side surface extending in the elongated direction of the housing. The side surface of the housing is provided with an attachment protrusion. The rigid member is provided with an attachment hole that penetrates from a surface facing the side surface of the housing to a non-facing surface on the opposite side, and the non-facing surface of the rigid member is provided with a concave. The attachment protrusion is inserted into the attachment hole, and a part of the attachment protrusion is fit into the concave.

There is provided an image reading apparatus including: a reading device; a carriage which the reading device is loaded; a support shaft which is formed of a conductive material, which is grounded to a ground potential, and which supports the carriage; and a conduction member which allows a conductive part of the carriage and the support shaft to be electrically conducted to each other, in which the carriage includes a bearing section which is formed of a material having electric insulation properties, in which the bearing section is supported by the support shaft in a state of abutting against the support shaft from one side of the support shaft in a direction intersecting with a shaft line of the support shaft, and in which the conduction member is fixed to the carriage, and abuts against the support shaft from a side opposite to the support shaft.

An image reading device includes a contact plate, a frame, a carriage, and a flexible flat cable. The carriage includes a reading mechanism and a resin-made slider projectedly provided at both end portions of the reading mechanism in its extending direction, and reciprocally moves in a sub-scanning direction at a bottom surface side of the contact plate while the slider slides the bottom surface of the contact plate in the frame. The flexible flat cable is connected to an one side surface of the carriage so that a width direction thereof matches the main-scanning direction, is arranged so that a part continued from a portion where the flexible flat cable connects with the one side surface is curved in a U-shape to go around toward an underside of the carriage, and transmits an electric signal of the reading mechanism. The contact plate is applied with a fluorine coating.

There is provided a flat head type image reading device configured to scan a standard size document including an A4 size, the image reading device including: a document pressing section pressing the standard size document and made of an elastic member, in which the document pressing section has fixing members, and the fixing members are arranged at positions corresponding to end portions of the standard size document.

An image forming apparatus includes a housing. From an upper surface of the housing, a plate-like rail part, which extends along the screw shaft to guide movement of the holding member, protrudes, and the holding member is provided with a guide part having a guide groove engaged with the rail part. The optical scanning device further includes a scraper member fixed to the holding member and scraping off foreign matters attached to the rail part, wherein the scraper member includes a pair of scraper pieces provided at both sides of the rail part while interposing the rail part therebetween and having distal end edges abutting a side surface of the rail part.

A driving device is used in an image reading apparatus, and reciprocates a scanning unit for reading an image on an original. The driving device comprises a pull member, a driving pulley which transmits driving force to the pull member, a following pulley which applies tension to the pull member and a pulley holder having a pulley axis which holds the following pulley rotatably. Then, the pulley axis has a lock pawl capable of locking an upper end portion of the following pulley and canceling engagement with the following pulley by being tilted toward a side of an axial center by elastic deformation. Furthermore, the lock pawl is arranged at a side of a tension acting direction from the pull member to the following pulley except the farthest position from the driving pulley among positions in a circumferential direction of the pulley axis. It is possible to attach and detach the following pulley easily at a time of maintenance or the like.

A driving device is used in an image reading apparatus, and reciprocates a scanning unit for reading an image on an original. The driving device comprises a pull member, a driving pulley which transmits driving force to the pull member, a following pulley which applies tension to the pull member and a pulley holder having a pulley axis which holds the following pulley rotatably. Then, the pulley axis has a lock pawl capable of locking an upper end portion of the following pulley and canceling engagement with the following pulley by being tilted toward a side of an axial center by elastic deformation. Furthermore, the lock pawl is arranged at a side of a tension acting direction from the pull member to the following pulley except the farthest position from the driving pulley among positions in a circumferential direction of the pulley axis. It is possible to attach and detach the following pulley easily at a time of maintenance or the like.

An image reading apparatus includes: a contact glass provided at an upper surface of a main body of the apparatus to set a manuscript thereon, an image sensor being positioned below the contact glass and having a reading surface on contact glass side for reading an image from the manuscript on the contact glass, a carriage supporting the image sensor accommodated in a sensor container formed to have a recess open to the contact glass side, a rail member slidably supporting the carriage, and a biasing member biasing the image sensor to the contact glass side via a biased portion adjacent to the reading surface of the image sensor. An upper end of the biasing member is positioned below the contact glass and above the lower surface of the image sensor.