Abstract: An image reading apparatus for reading an image on an original document by irradiating it with light and photoelectrically converting reflected light from it by an image pickup unit, including: an original document guide member positionable opposite to the image pickup unit, with a conveyance position of the original document therebetween; a white reference member that is positionable, the same as the original document guide member, and has a reference white color; an achromatic constant-density reference member that is positionable, the same as the original document guide member, and has a reference achromatic constant-density; a drive unit that moves one of the three members so as to be positioned opposite to the image pickup unit; and a control unit that controls execution of detection processings for dust detection from data obtained by moving, as described above, the achromatic constant-density reference member and the white reference member by reading them.

Abstract: In the event of a failure of one of the image storing devices provided to process colors separately, the image data allocated for the failed image storing device is sent to the image storing devices being allocated other colors and is stored therein. In the event of a partial failure of the a magnetic disk apparatus, the number of scanning lines per unit time during the document reading operation by the image reading section is reduced from the normal level or the page spacing during the reading operation by the image reading section is increased over the normal level. This arrangement ensures apparatus functions and provides a color image forming apparatus capable of continuous operations.

Abstract: Disclosed in an image reading apparatus including a reading unit to obtain an image data by irradiating a document with a light and reading an image of the document, a paper thickness detection unit to detect a thickness of the document to be read by the reading unit, a process unit to process the image data which is obtained by the reading unit based on a parameter and a control unit to carry out a control of changing the parameter of the process unit according to the thickness of the document which is detected by the paper thickness detection unit.

Abstract: An image reading device includes: a solid-state image sensor for converting image information into an electric signal; an analog processing section for generating an analog processing signal by sampling and amplifying the electric signal at a sampling position; an A/D converting section for converting the analog processing signal into a digital signal; a pulse generating section for generating a control pulse to the solid-state image sensor, the analog processing section and the A/D converting section; and a control section for controlling a pulse generating timing of the pulse generating section, wherein the analog processing section comprises an amplification processing section for amplifying the electric signal so as to set an output voltage to a set voltage, the pulse generating section includes a varying section for varying the sampling position, and the control section includes an optimizing section for optimizing the sampling position based on variance of amplification gain values.

Abstract: An image reading apparatus for reading an image on an original document by irradiating it with light and photoelectrically converting reflected light from it by an image pickup unit, including: an original document guide member positionable opposite to the image pickup unit, with a conveyance position of the original document therebetween; a white reference member that is positionable, the same as the original document guide member, and has a reference white color; an achromatic constant-density reference member that is positionable, the same as the original document guide member, and has a reference achromatic constant-density; a drive unit that moves one of the three members so as to be positioned opposite to the image pickup unit; and a control unit that controls execution of detection processings for dust detection from data obtained by moving, as described above, the achromatic constant-density reference member and the white reference member by reading them.

Abstract: Disclosed is an image reading method for reading an image on a document, including: reading cyclically the image in a main scanning direction with using an image pickup section, while relatively moving at least one of a light emitting section and the document irradiated by the light emitting section with a sub-scanning velocity in a sub-scanning direction perpendicular to the main scanning direction, against the image pickup section which comprises a plurality of light receiving elements in the main scanning direction; controlling, while the cyclic reading, a reading cycle in the main scanning direction to be inversely proportional to a magnification ratio; controlling, while the cyclic reading, light emitting intensity and light emitting period in the reading cycle to be constant irrespective of the magnification ratio; and controlling, while the cyclic reading, the sub-scanning velocity to be constant irrespective of the magnification ratio.

Abstract: In the event of a failure of one of the image storing devices provided to process colors separately, the image data allocated for the failed image storing device is sent to the image storing devices being allocated other colors and is stored therein. In the event of a partial failure of the a magnetic disk apparatus, the number of scanning lines per unit time during the document reading operation by the image reading section is reduced from the normal level or the page spacing during the reading operation by the image reading section is increased over the normal level. This arrangement ensures apparatus functions and provides a color image forming apparatus capable of continuous operations.

Abstract: In a document reading apparatus having a scanning exposure reading system by which a document placed on a platen is scanning exposed by an optical system and a document image is read out, or a document reading system by which a moving document is read out by an optical system, at the first collection position and the second collection position which are different in the sub-scanning direction of the scanning expose on a reference density plate, the first shading correction data and the second shading correction data are respectively read in the main scanning direction, and the shading position is corrected on the basis of the read first and second shading correction data.

Abstract: An image reading device includes: a solid-state image sensor for converting image information into an electric signal; an analog processing section for generating an analog processing signal by sampling and amplifying the electric signal at a sampling position; an A/D converting section for converting the analog processing signal into a digital signal; a pulse generating section for generating a control pulse to the solid-state image sensor, the analog processing section and the A/D converting section; and a control section for controlling a pulse generating timing of the pulse generating section, wherein the analog processing section comprises an amplification processing section for amplifying the electric signal so as to set an output voltage to a set voltage, the pulse generating section includes a varying section for varying the sampling position, and the control section includes an optimizing section for optimizing the sampling position based on variance of amplification gain values.

Abstract: In a document reading apparatus having a scanning exposure reading system by which a document placed on a platen is scanning exposed by an optical system and a document image is read out, or a document reading system by which a moving document is read out by an optical system, at the first collection position and the second collection position which are different in the sub-scanning direction of the scanning expose on a reference density plate, the first shading correction data and the second shading correction data are respectively read in the main scanning direction, and the shading position is corrected on the basis of the read first and second shading correction data.

Abstract: An image memory apparatus for storing image data which includes: plural memory cells, arranged in a one-chip memory, for inputting image data and for outputting the image data therefrom; a writing line, connected with all of the plural memory cells, for inputting the image data into the plural memory cells; a readout line, provided independent from the writing line and connected to all of the plural memory cells, for outputting the image data from the plural memory cells; a first address designating line, connected with the plural memory cells, for identifying one of the plural memory cells which is subjected to an input of the image data through the writing line; a second address designating line, provided independent from the first address designating line and connected with the plural memory cells, for identifying one of the plural memory cells which is subjected to an output of the image data through the readout line.

Abstract: A document size detector for detecting a size of a document in use with a document scanner. The document size detector has an irradiator to irradiate the document with a light beam; a cover of the document; a receiver of the reflection light from the document and the cover; a converter to convert the reflection light to image signals; a detector to detect the shadow of the document on the cover in the image signals; and the determiner to determine the size of the document according to the detected shadow of the document.