Provided is an image reading apparatus including a line sensor including three line sensors arranged at a predetermined interval in a sub-scanning direction, and being configured to read an image of an original by the respective line sensors, which includes light receiving elements arranged in a first direction, to generate read data representing the read image, the three line sensors each including a first light receiving element configured to receive red light, a second light receiving element configured to receive blue light, and a third light receiving element configured to receive green light, which are arranged in a main scanning direction; and a reading control board. The reading control board is configured to generate a first combined flag obtained by combining results of detecting abnormal images of respective colors and a second combined flag obtained by combining results of detecting abnormal images of the respective colors.

In an image-reading device, a counting unit counts a number of clock cycles of a spread-spectrum clock as a counter value. A correcting unit corrects one of the counter value and a reference clock cycle number based on a phase detected by the phase detecting unit when the counting unit counts. A comparing unit compares the counter value and the reference clock cycle number and determines whether the counter value and the reference clock cycle number satisfy a prescribed relationship. A time length setting unit sets a length of at least one of a reading time and an irradiation time based on: a timing when the counting unit starts counting to set the time length; and a timing when the comparing unit determines that the compared values satisfy the prescribed relationship, such that the time length set by the time length setting unit remains constant.

In an image-reading device, a counting unit counts a number of clock cycles of a spread-spectrum clock as a counter value. A correcting unit corrects one of the counter value and a reference clock cycle number based on a phase detected by the phase detecting unit when the counting unit counts. A comparing unit compares the counter value and the reference clock cycle number and determines whether the counter value and the reference clock cycle number satisfy a prescribed relationship. A time length setting unit sets a length of at least one of a reading time and an irradiation time based on: a timing when the counting unit starts counting to set the time length; and a timing when the comparing unit determines that the compared values satisfy the prescribed relationship, such that the time length set by the time length setting unit remains constant.

Then image reading device includes a transparent document table, a frame, a reading unit, a moving mechanism, a white reference member, and a controller. The frame is provided around a peripheral of the document table. The white reference member is provided on the frame adjacent to the document table in the sub scanning direction and has a length in the main scanning direction longer than the document table. The reading unit includes a first reading part which reads an area corresponding to the document table and a second reading part which reads an area corresponding to the frame. The controller detects a boundary between the frame and the reference member based on a read value of the second reading part while moving the reading unit by the moving mechanism, and positions the reading unit at a home position apart from the boundary by a predetermined distance.

Then image reading device includes a transparent document table, a frame, a reading unit, a moving mechanism, a white reference member, and a controller. The frame is provided around a peripheral of the document table. The white reference member is provided on the frame adjacent to the document table in the sub scanning direction and has a length in the main scanning direction longer than the document table. The reading unit includes a first reading part which reads an area corresponding to the document table and a second reading part which reads an area corresponding to the frame. The controller detects a boundary between the frame and the reference member based on a read value of the second reading part while moving the reading unit by the moving mechanism, and positions the reading unit at a home position apart from the boundary by a predetermined distance.

An original image is read as an aggregate of a plurality of pixels in which adjacent pixels have different colors (R, G, and B) in a main scanning direction and in a sub-scanning direction, and the read pixels of the respective colors are stored in a line memory in association with information on relative positions of the pixels with respect to another pixel. Then, the stored pixels are sorted so that pixels having the same color are adjacent to each other, and an abnormal pixel (dust) not present in the original image is detected based on the state of the sorted pixels. With this, the dust not present in the original image is detected without increasing the cost, and the dust is corrected without forming a conspicuous trace of correction.

An image sensor unit (1A) includes: a light condenser (40) that condenses light including image information of an illuminated object; an image sensor (48) that receives the light passed through the light condenser (40) and that converts the light to an electrical signal; and a frame (10A) that houses the light condenser (40) and the image sensor (48), wherein the image sensor unit (1A) includes an urging member (50A) that urges and fixes the light condenser (40) to the frame (45), and the urging member (50A) urges and fixes the light condenser (40) to the frame (10A) from a light entering side or a light emission side of the light.

An image sensor unit (1A) includes: a light condenser (40) that condenses light including image information of an illuminated object; an image sensor (48) that receives the light passed through the light condenser (40) and that converts the light to an electrical signal; and a frame (10A) that houses the light condenser (40) and the image sensor (48), wherein the image sensor unit (1A) includes an urging member (50A) that urges and fixes the light condenser (40) to the frame (45), and the urging member (50A) urges and fixes the light condenser (40) to the frame (10A) from a light entering side or a light emission side of the light.

An image reading apparatus according to the present disclosure includes a platen glass, an image reader, and an output interface. An original is placed on the platen glass. The image reader is configured to read an image of the original on the platen glass. The image reader includes at least one sensor configured to detect a quantity of light for each of a plurality of regions on the platen glass. The output interface is configured to output information which identifies one or more regions of the plurality of regions in which the quantity of light detected therefrom exceeds a given value.

An image reading apparatus according to the present disclosure includes a platen glass, an image reader, and an output interface. An original is placed on the platen glass. The image reader is configured to read an image of the original on the platen glass. The image reader includes at least one sensor configured to detect a quantity of light for each of a plurality of regions on the platen glass. The output interface is configured to output information which identifies one or more regions of the plurality of regions in which the quantity of light detected therefrom exceeds a given value.