Abstract: Disclosed is an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is sensed by the document feeding unit to thereby read an image on the document.

Abstract: In an image reading apparatus which can operate in a plurality of image processing modes, and includes a photoelectric converter for reading an object image and outputting an electrical signal, a reference white plate used to correct image read nonuniformity by the photoelectric converter, and a lamp for illuminating an object and the reference white plate with light, and its control, the currently set image processing mode is determined, a wait time is set in correspondence with the currently set image processing mode and the lamp is turned on, then the photoelectric converter begins to read the reference white plate after a lapse of the wait time.

Abstract: An original size sensing method for an apparatus which includes a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, determines the presence/absence of incidence of ambient light on the basis of an output from the photoelectric converter while the light source is kept off. When ambient light is found to be incident, the method determines the size of an original placed on the platen on the basis of that output from the photoelectric converter, which falls outside the range in which the ambient light is incident, while the light source is kept on.

Abstract: An original size sensing method for an apparatus which includes a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, determines the presence/absence of incidence of ambient light on the basis of an output from the photoelectric converter while the light source is kept off. When ambient light is found to be incident, the method determines the size of an original placed on the platen on the basis of that output from the photoelectric converter, which falls outside the range in which the ambient light is incident, while the light source is kept on.

Abstract: Shading correction data used in an image reading apparatus for shading-correcting image data obtained by reading an original image by a line sensor is acquired. A defect position on a white reference plate and a defect correction coefficient for correcting shading correction data at this defect position are obtained, and the shading correction data at the defect position is corrected by using the defect correction coefficient. Shading correction is performed by using the corrected shading correction data.

Abstract: Disclosed is an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is sensed by the document feeding unit to thereby read an image on the document.

Abstract: In an image reading apparatus which can operate in a plurality of image processing modes, and includes a photoelectric converter for reading an object image and outputting an electrical signal, a reference white plate used to correct image read nonuniformity by the photoelectric converter, and a lamp for illuminating an object and the reference white plate with light, and its control, the currently set image processing mode is determined, a wait time is set in correspondence with the currently set image processing mode and the lamp is turned on, then the photoelectric converter begins to read the reference white plate after a lapse of the wait time.

Abstract: Shading correction data used in an image reading apparatus for shading-correcting image data obtained by reading an original image by a line sensor is acquired. A defect position on a white reference plate and a defect correction coefficient for correcting shading correction data at this defect position are obtained, and the shading correction data at the defect position is corrected by using the defect correction coefficient. Shading correction is performed by using the corrected shading correction data.

Abstract: An original size sensing method for an apparatus which includes a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, determines the presence/absence of incidence of ambient light on the basis of an output from the photoelectric converter while the light source is kept off. When ambient light is found to be incident, the method determines the size of an original placed on the platen on the basis of that output from the photoelectric converter, which falls outside the range in which the ambient light is incident, while the light source is kept on.

Abstract: The objective of this invention is to provide an apparatus which can form a high-quality image by reliably adjusting the superposing positions of frame images when a single image is formed by superposing a plurality of frame images, and especially, the objective of this invention is to reliably adjust the superposing positions of frame images and form a high-quality image by controlling a rotary polygon and image carrier to operate in association with each other. To achieve such objectives, the apparatus of this invention generates a first signal indicating that the light beam coming from the rotary polygon has scanned a predetermined position, also generates a second signal independently of that detection, and moves the image carrier by selectively using the first and second signals as needed. In this apparatus, by rotating a driving means N times on the basis of a reference signal obtained by frequency-dividing the first signal, the image carrier completes one rotation.

Abstract: An image processing apparatus and method which inputs multivalued image data capable of m-level representation, performs image processing on the input data, and converts the processed data into multivalued image data capable of n-level (m<n) tonality. Upon forming an image on a print medium based on input image data, the image is formed such that the difference between an image density D(x) of the image formed on a print medium at a tonality level x and an image density D(x+1) of an image formed on the print medium at the next tonality level x+1 satisfies D(x+1) -D(x).ltoreq.A.times.D(x) (A.ltoreq.0.08) (A.ltoreq.0.08). Further, a pattern signal having a rectified sine wave having a predetermined period is generated, and a pulse-width modulated signal for generating a beam is generated by performing pulse-width modulation on the input image data based on the pattern signal.

Abstract: It is an object to identify a failed portion in a circuit for image processing and notify a service center of the failed portion, thereby enabling the failed circuit to be promptly replaced. Circuit portions of image processing units are constructed on separate substrates. As processing routes of an image signal which is inputted from an A/D converting unit, a route in which the image signal passes through a given circuit portion and a route in which the image signal doesn't pass therethrough are set. Data of a predetermined pattern is processed by those processing routes. The presence or absence of a failure of each circuit portion is discriminated from the processing results. The discrimination result is transmitted to an external apparatus installed in a service center.

Abstract: An image forming apparatus in which two delay time generators input data for two delay times, and a reference signal, and outputs two pulse signals having predetermined pulse-widths. A pulse generator generates a pulse signal based on the phase difference between the two output pulse signals. The pulse-width and pulse position of the generated pulse signal is arbitrarily controlled by the two output pulse signals.

Abstract: An image forming apparatus for forming images by allowing a light beam to be scanned and exposed on a photosensitive body includes a single detecting device for detecting the light beam scanned and exposed onto the photosensitive body, a plurality of signal generating devices for generating a predetermined control signal on the basis of an output from the detecting device, and an output control device for controlling the routing of an optical signal output which is output from the detecting device to the objective signal generating device.