An image reading device includes an angle restriction part 212a that restricts an inclination angle with respect to a document table glass (203) when viewed from a sub-scanning direction of a flat cable (214) such that a contact portion is biased to one side of the flat cable (214) in a main scanning direction when an upper surface part of the flat cable (214) contacts with the document table glass (203) with movement of an image reading unit (210).

An image processing apparatus includes a support member to support a sheet, a light source that extends in a main-scanning direction and is configured to move in a sub-scanning direction and irradiate light on the sheet as the light source moves in the sub-scanning direction, a conversion unit configured to generate multiple line image data based on light reflected by the sheet and incident thereon, as the light source moves in the sub-scanning direction, and a processing unit configured to carry out a correction process with respect to each of the line image data using a different correction formula for each of the line image data.

A read sensor generates front side image information indicating an image on a front side of an object to be read, and front side measurement information indicating a line of an image in a main scanning direction on the front side of a correction chart. A read sensor generates back side image information indicating an image on a back side of the object to be read, and back side measurement information indicating a line of an image in the main scanning direction on the back side of the correction chart. The image correction device calculates an amount of misalignment of read positions based on the front side measurement information and the back side measurement information, and corrects misalignment of images on the front side and the back side of the object to be read, indicated by the front side image information and the back side image information.

An image processing device includes a modulation clock generator, a line synchronization signal generator, a line image sensor, and an image processor. The modulation clock generator is configured to generate the modulation clock by modulating a frequency of a reference clock at a predetermined modulation cycle. The line synchronization signal generator is configured to generate, on the basis of the modulation clock, a line synchronization signal whose line cycle varies from line to line. The line image sensor is configured to sequentially read an image of one line of a document at a timing corresponding to the line synchronization signal and to output image data. The image processor is configured to process the image data on the basis of the modulation clock.

An image forming system includes an image reading device which reads an image of a sheet conveyed along a conveyance path. The image reading device includes a reading sensor and a moving mechanism. The reading sensor optically reads the image. The moving mechanism moves the reading sensor to a reading position closer to the conveyance path and readable the image and a non-reading position separated from the conveyance path farther than the reading position.

In accordance with an embodiment, an image reading apparatus comprises a carriage, a stepping motor and a processor. The carriage acquires an image. The stepping motor moves the carriage. The processor outputs a first clock signal for driving the stepping motor if a present position of the carriage is unknown and outputs a second clock signal, of which a frequency is higher than that of the first clock signal, for driving the stepping motor if the present position of the carriage can be recognized.

An image reader including a document table having a reference point, a first region of a sheet having a predetermined size when a vertex of the sheet is positioned on the reference point, and a second region, a changing mechanism changing a reading position in a sub scanning direction, and a controller configured to control the changing mechanism to change the reading position to a first position such that a distance in the sub scanning direction between the reference point and the first position corresponds to a length of the predetermined sheet size in the sub scanning direction, acquire specific digital data of the second region through image reading in the first position with a light source turned off, compare a particular value of the specific digital data with a criterion value within the second region, and determine a state of a document cover based on the comparison.

When heights from the reading lines (Lr, Lg, Lb) on the transmission part (13B) corresponding to the line sensors (33r, 33g, 33b) to the predetermined conveyance path T are employed as reading heights of the line sensors (33r, 33g, 33b), a position shift correction unit (100) performs first correction control for correcting position shifts between image signals outputted from the line sensors (33r, 33g, 33b) on the basis of a difference of the reading heights between the line sensors (33r, 33g, 33b).

An image reader including a document table having a reference point, a first region of a sheet having a predetermined size when a vertex of the sheet is positioned on the reference point, and a second region, a changing mechanism changing a reading position in a sub scanning direction, and a controller configured to control the changing mechanism to change the reading position to a first position such that a distance in the sub scanning direction between the reference point and the first position corresponds to a length of the predetermined sheet size in the sub scanning direction, acquire specific digital data of the second region through image reading in the first position with a light source turned off, compare a particular value of the specific digital data with a criterion value within the second region, and determine a state of a document cover based on the comparison.

Regarding an image forming apparatus for printing an input image and including a print head having a head sensor configured to sense information from the input image printed on a print medium, there is a method of determining a head sensor position parameter in the image forming apparatus. The method includes printing a first swath of the input image on the print medium and determining the head sensor position parameter by performing a sub-method. The sub-method includes capturing, via the head sensor, a target image from the printed first swath, comparing the target image to a reference image for the first swath based upon the input image, and determining the head sensor position parameter based on a relative shift between the target image and the reference image.