An image reading apparatus includes a light source to emit at least light in a first wavelength range and light in a second wavelength range, a background member having different light reflectances in the first and second wavelength ranges, an imaging device, and circuitry. The imaging device receives reflected light from the background member irradiated with the light in the first wavelength range, and generates first read information. The imaging device further receives reflected light from the background member irradiated with the light in the second wavelength range, and generates second read information. The circuitry detects presence or absence of a first foreign substance based on a difference in reading level of the first read information generated by the imaging device; and detect presence or absence of a second foreign substance based on a difference in reading level of the second read information generated by the imaging device.

An image reading apparatus includes an image reading chip configured to read an image. The image reading chip includes a first pixel unit which generates a first pixel signal, a second pixel unit which generates a second pixel signal, a first amplification unit which amplifies the first pixel signal, and outputs a first amplification signal, a second amplification unit which amplifies the second pixel signal, and outputs a second amplification signal, and a third amplification unit that amplifies each of the first amplification signal and the second amplification signal, and outputs an amplified signal. The image reading chip has a shape which includes a first side and a second side shorter than the first side. The third amplification unit is disposed between the first amplification unit and the second amplification unit in a direction along the first side.

An image reading apparatus includes a light source to emit at least light in a first wavelength range and light in a second wavelength range, a background member having different light reflectances in the first and second wavelength ranges, an imaging device, and circuitry. The imaging device receives reflected light from the background member irradiated with the light in the first wavelength range, and generates first read information. The imaging device further receives reflected light from the background member irradiated with the light in the second wavelength range, and generates second read information. The circuitry detects presence or absence of a first foreign substance based on a difference in reading level of the first read information generated by the imaging device; and detect presence or absence of a second foreign substance based on a difference in reading level of the second read information generated by the imaging device.

An image sensor module comprises: a substrate having a first side and second side, the first side being an opposite of the second side, an image sensor attached to the first side of the substrate, bonding wires to bond the image sensor to pads on the first side of the substrate, a protective structure disposed on the first side of the substrate surrounding the image sensor, the bonding wires, and the pads, the protective structure having a dam and a lid, a cover glass disposed on the protective structure, and a set of solder balls attached to the second side of the substrate.

A photoelectric conversion element includes a plurality of pixels to receive light; and a signal processor to process a signal of the pixels. The signal processor includes: a first element, being a transistor, having a first effective channel width through which a current can effectively pass through in the first element; and a second element, being a transistor, having a second effective channel width through which a current can effectively pass through in the second element. The first effective channel width of the first element is larger than the second effective channel width of the second element.

A light receiving unit including: a sensor board assembly on which plural sensor tips are arrayed in a line in a longitudinal direction of the sensor board and mounted on the sensor board; and a sensor plate on which plural of the sensor board assemblies are arrayed and mounted in a line in the longitudinal direction. The sensor chips include plural pixels formed in a line in the longitudinal direction. At longitudinal ends of the sensor board assembly, the sensor chips protrude outward in the longitudinal direction from the longitudinal ends. Between the facing sensor chips of the adjacent sensor board assemblies, the facing sensor chips mounted at the longitudinal ends, the ends of the facing sensor chips are spaced at a predetermined interval. The sensor board includes convex portions, at the longitudinal ends, protruding in the longitudinal direction. The sensor chips are mounted at the convex portion.

An image sensor module comprises: a substrate having a first side and second side, the first side being an opposite of the second side, an image sensor attached to the first side of the substrate, bonding wires to bond the image sensor to pads on the first side of the substrate, a protective structure disposed on the first side of the substrate surrounding the image sensor, the bonding wires, and the pads, the protective structure having a dam and a lid, a cover glass disposed on the protective structure, and a set of solder balls attached to the second side of the substrate.

A light receiving unit including: a sensor board assembly on which plural sensor tips are arrayed in a line in a longitudinal direction of the sensor board and mounted on the sensor board; and a sensor plate on which plural of the sensor board assemblies are arrayed and mounted in a line in the longitudinal direction. The sensor chips include plural pixels formed in a line in the longitudinal direction. At longitudinal ends of the sensor board assembly, the sensor chips protrude outward in the longitudinal direction from the longitudinal ends. Between the facing sensor chips of the adjacent sensor board assemblies, the facing sensor chips mounted at the longitudinal ends, the ends of the facing sensor chips are spaced at a predetermined interval. The sensor board includes convex portions, at the longitudinal ends, protruding in the longitudinal direction. The sensor chips are mounted at the convex portion.

An image reading apparatus includes an image reading chip configured to read an image. The image reading chip includes a first pixel unit which generates a first pixel signal, a second pixel unit which generates a second pixel signal, a first amplification unit which amplifies the first pixel signal, and outputs a first amplification signal, a second amplification unit which amplifies the second pixel signal, and outputs a second amplification signal, and a third amplification unit that amplifies each of the first amplification signal and the second amplification signal, and outputs an amplified signal. The image reading chip has a shape which includes a first side and a second side shorter than the first side. The third amplification unit is disposed between the first amplification unit and the second amplification unit in a direction along the first side.