An image processing apparatus includes a document table, an image reading portion, a cover portion, a presser sheet, and a sheet winding portion. The presser sheet is provided on the cover portion, and contacts the document on the document table when the cover portion is positioned at the closing position. The sheet winding portion allows a first portion of the presser sheet to extend along the document table while holding a second portion of the presser sheet in a wound state. The sheet winding portion can feed the second portion when an external force is applied to the first portion. In the cover portion, a retreat space is formed so that the first portion of the presser sheet and a portion of the second portion fed from the sheet winding portion can retreat into the retreat space.

An image processing apparatus includes a document table, an image reading portion, a cover portion, a presser sheet, and a sheet winding portion. The presser sheet is provided on the cover portion, and contacts the document on the document table when the cover portion is positioned at the closing position. The sheet winding portion allows a first portion of the presser sheet to extend along the document table while holding a second portion of the presser sheet in a wound state. The sheet winding portion can feed the second portion when an external force is applied to the first portion. In the cover portion, a retreat space is formed so that the first portion of the presser sheet and a portion of the second portion fed from the sheet winding portion can retreat into the retreat space.

An image reading device includes: a scanner glass; photo-sensors arranged at intervals in a main scanning direction to read a document conveyed in a sub-scanning direction; an adjuster that adjusts the size of an overlapping area between a first and second image obtained by neighboring photo-sensors, the overlapping area constituting a first area of the first image and a second area of the second image; a superimposing portion that shifts either one of images of the first and second area to the other one; a judgment portion that judges whether the images having different focal depths exist based on the degree of matching between the first and second area; and a detector that detects a foreign body on the scanner glass platen by detecting a continuous image stretching in a document conveying direction in both of the images having different focal depths, if the images having different focal depths exist.

An image reading device includes: a scanner glass; photo-sensors arranged at intervals in a main scanning direction to read a document conveyed in a sub-scanning direction; an adjuster that adjusts the size of an overlapping area between a first and second image obtained by neighboring photo-sensors, the overlapping area constituting a first area of the first image and a second area of the second image; a superimposing portion that shifts either one of images of the first and second area to the other one; a judgment portion that judges whether the images having different focal depths exist based on the degree of matching between the first and second area; and a detector that detects a foreign body on the scanner glass platen by detecting a continuous image stretching in a document conveying direction in both of the images having different focal depths, if the images having different focal depths exist.

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 estimated image data calculator is configured to calculate, as estimated image data, for each of image data of respective colors outputted from an imaging element, on the basis of a pixel value of a first pixel on one of two lines adjacent to each other in the image data, and a pixel value of a second pixel on the other of the two lines and adjacent to the first pixel, image data of a non-reading region between a reading region in a document corresponding to the one of the two lines and a reading region in the document corresponding to the other of the two lines. A pixel value correcting unit is configured to correct at least one of the pixel value of the first pixel and the pixel value of the second pixel on the basis of the estimated image data.

An estimated image data calculator is configured to calculate, as estimated image data, for each of image data of respective colors outputted from an imaging element, on the basis of a pixel value of a first pixel on one of two lines adjacent to each other in the image data, and a pixel value of a second pixel on the other of the two lines and adjacent to the first pixel, image data of a non-reading region between a reading region in a document corresponding to the one of the two lines and a reading region in the document corresponding to the other of the two lines. A pixel value correcting unit is configured to correct at least one of the pixel value of the first pixel and the pixel value of the second pixel on the basis of the estimated image data.

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 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 an LED light source, a CCD sensor receiving light reflected from a document irradiated with light from the LED light source, a fan, and a frame housing the LED light source, the CCD sensor and the fan. The fan circulates air in a substantially sealed space formed by the frame. Thus, temperature difference in the image reading apparatus can be reduced while not degrading dust-proof property of the apparatus, and efficient heat radiation to the outside becomes possible. Thus, variation of sensitivity of CCD sensor, deviation of point of focus of image forming system and deviation of reading position caused by temperature increase can be prevented.