An illuminating device capable of stably illuminating an irradiated object such as a document while suppressing light loss with a simply structure is provided. An LED array and a reflective plate are disposed sandwiching a slit (St) through which light reflected by a document MS passes and a light-guiding member is disposed on the side of the LED array. The light-guiding member includes a direct emission unit disposed between an illumination range y centered on a document reading position and the LED array and an indirect emission unit disposed between the reflective plate and the LED array, a light incidence face of the direct emission unit and a light incidence face of the indirect emission unit are disposed at mutually different position around the LED array, and the LED array is disposed on a side of an interior angle formed by the light incidence faces.

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.

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.

An illuminating device capable of stably illuminating an irradiated object such as a document while suppressing light loss with a simply structure is provided. An LED array and a reflective plate are disposed sandwiching a slit (St) through which light reflected by a document MS passes and a light-guiding member is disposed on the side of the LED array. The light-guiding member includes a direct emission unit disposed between an illumination range y centered on a document reading position and the LED array and an indirect emission unit disposed between the reflective plate and the LED array, a light incidence face of the direct emission unit and a light incidence face of the indirect emission unit are disposed at mutually different position around the LED array, and the LED array is disposed on a side of an interior angle formed by the light incidence faces.

An image reading apparatus includes an illumination unit that illuminates light on an image surface of a sheet, and a photoelectric conversion element that converts reflected light from the sheet illuminated by the illumination unit into an electric signal. The illumination unit includes a circuit board including a light emitting element, and a light guide that guides light, emitted from the light emitting element, to a sheet read surface. In the image reading apparatus, the light guide includes a positioning surface that abuts against a first surface of the circuit board and that performs positioning of the light guide and the circuit board, and a pressing portion that abuts against a second surface of the circuit board on an opposite side of the first surface and that presses the circuit board against the positioning surface.

An image reading apparatus includes an illumination unit that illuminates light on an image surface of a sheet, and a photoelectric conversion element that converts reflected light from the sheet illuminated by the illumination unit into an electric signal. The illumination unit includes a circuit board including a light emitting element, and a light guide that guides light, emitted from the light emitting element, to a sheet read surface. In the image reading apparatus, the light guide includes a positioning surface that abuts against a first surface of the circuit board and that performs positioning of the light guide and the circuit board, and a pressing portion that abuts against a second surface of the circuit board on an opposite side of the first surface and that presses the circuit board against the positioning surface.

An illuminating device capable of stably illuminating an irradiated object such as a document while suppressing light loss with a simply structure is provided. An LED array and a reflective plate are disposed sandwiching a slit (St) through which light reflected by a document MS passes and a light-guiding member is disposed on the side of the LED array. The light-guiding member includes a direct emission unit disposed between an illumination range y centered on a document reading position and the LED array and an indirect emission unit disposed between the reflective plate and the LED array, a light incidence face of the direct emission unit and a light incidence face of the indirect emission unit are disposed at mutually different position around the LED array, and the LED array is disposed on a side of an interior angle formed by the light incidence faces.

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.

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.

An image sensor includes: a lens configured to focus light irradiated toward an object to be read and reflected by the object to be read; a sensor configured to receive light focused by the lens; a sensor board configured to mount thereon the sensor; a board retaining plate, having a casing attachment surface extending in the X direction and a sensor board attachment reference surface that is in contact with the +Y side of the sensor board and is formed in a side surface of the casing attachment surface, and configured to retain the sensor board; and a first casing configured to fix or retain the board retaining plate by fastening of a surface of the casing attachment surface.