An image signal processing device includes a reference signal generating portion, a determination portion, and an extraction portion. The reference signal generating portion generates and outputs a reference signal that sequentially transmits reference pulses shifted from horizontal synchronization pulses on a horizontal synchronization signal by a predetermined shift time. The determination portion determines whether the horizontal synchronization pulses are normal by comparing time differences between input of the horizontal synchronization pulses and input of the reference pulses with the shift time. The extraction portion extracts line image data points from an image signal in synchronization with the input of the horizontal synchronization pulses that have been determined as normal.

A reading device includes a carriage configured to move in a sub-scanning direction with reference to an object placed on a contact glass, an optical sensor attached to the carriage, the optical sensor being configured to scan the object placed on the contact glass to obtain an image of the object, and a reference scale used as a reference when a dimension of the object is computed based on the image obtained by the optical sensor. In the reading device, the reference scale extends in a main scanning direction and a sub-scanning direction with reference to the object, and is disposed outside a range of image acquisition in which the optical sensor scans the object to obtain the image of the object as the carriage moves and inside a maximum movement range in which the carriage is movable and the optical sensor obtains the image of the object.

An image reading apparatus according to the present invention is an image reading apparatus including a reading unit that illuminates an original and reads an image of the original, wherein the apparatus can execute a first mode of reading the image of the moving original while the reading unit is kept stationary, and a second mode of reading the image of the stationary original while moving the reading unit, the apparatus further includes a light condensing unit that refracts a light flux from the reading unit and condenses the light flux on the original in the first mode, and the light flux from the reading unit incidents on the original without passing through the light condensing unit in the second mode.

An image signal processing device includes a reference signal generating portion, a determination portion, and an extraction portion. The reference signal generating portion generates and outputs a reference signal that sequentially transmits reference pulses shifted from horizontal synchronization pulses on a horizontal synchronization signal by a predetermined shift time. The determination portion determines whether the horizontal synchronization pulses are normal by comparing time differences between input of the horizontal synchronization pulses and input of the reference pulses with the shift time. The extraction portion extracts line image data points from an image signal in synchronization with the input of the horizontal synchronization pulses that have been determined as normal.

An image forming apparatus including: a drive motor configured to rotate a rotary polygon mirror to deflect light beam; a signal generation unit configured to generate a rotation synchronous signal; and a rotation control unit configured to control a rotation speed of the rotary polygon mirror, wherein the rotation control unit executes a disabling processing of disabling control of the drive motor based on the rotation synchronous signal, wherein a term of a first disabling processing for a first rotation speed is shorter than a term of a second disabling processing for the second rotation speed, and wherein when the rotation speed of the rotary polygon mirror is changed from the first rotation speed to the second rotation speed, the rotation control unit switches the disabling processing from the first disabling processing to the second disabling processing after reduction of the rotation speed of the rotary polygon mirror is started.

An optical scanning apparatus, an image projecting apparatus, and a mobile object. The optical scanning apparatus includes a light source to emit light, a light deflector to deflect the light emitted from the light source at least in a sub-scanning direction to perform optical scanning on a scan region, a light receiver to receive, within a predetermined range in the sub-scanning direction, the light used for optical scanning performed by the light deflector, and a controller to control the light deflector based on a number of times of light reception of the light receiver at a plurality of positions in the sub-scanning direction within the predetermined range. The image projecting apparatus includes the optical scanning apparatus, and a projection optical system configured to project light emitted from the optical scanning apparatus to the scan region.

An image forming apparatus which is capable of reducing a load on a data bus therein when controlling an image reading apparatus depending on its image processing capability. When acquired identification information about the image forming apparatus is included in a clock control table 600, a clock frequency for controlling hardware of the image reading apparatus in accordance with the clock control table 600, while setting the clock frequency therefor to a default setting of the clock control table 600 when the acquired identification information is not included in the clock control table 600, wherein a minimum value of clock frequencies in the clock control table 600 is set as the default setting of the clock control table 600.

An image forming apparatus includes a photosensitive member, a light source, a deflecting unit, a storing unit, a correcting unit, and a light source driving portion. Magnification correction data is determined using a quadratic function of a variable representing a scanning position with respect to a scanning direction. Coefficients of two quadratic functions corresponding to adjacent two regions included in a plurality of scanning regions are set so that a differential value calculated at the variable corresponding to a boundary of the two regions by a differential of the quadratic function for one region and a differential value calculated at the variable corresponding to the boundary of the two regions by a differential of the quadratic function for the other region are equal to each other.

In accordance with an embodiment, an image reading apparatus comprises a conveyance system, a reading section, a movement sensor and a processor. The conveyance system conveys a document in a conveyance route including a reading position. The reading section reads an image on a surface of the document passing through the reading position. The movement sensor detects a conveyance speed of the document conveyed by the conveyance system. In a case in which the conveyance speed of the document detected by the movement sensor differs from a reference speed, if the conveyance speed of the document is within an adjustable range, the processor performs control to adjust a reading processing in response to the conveyance speed of the document.

An image acquisition apparatus, an image forming apparatus, and a control method of the same are provided. An image acquisition apparatus includes an image sensor in which a red element outputting a signal corresponding to a red light, a green element outputting a signal corresponding to a green light, and a blue element outputting a signal corresponding to a blue light are arranged in a predetermined pattern, a driving unit configured to move the image sensor to a plurality of positions; and an image processor configured to receive a signal output from the red element, the green element and the blue element in the plurality of positions, respectively, and configured to acquire an image of an object by combining the received signal.