Abstract: Provided is an image reading apparatus configured to recognize edge portions of an image of an original precisely without being influenced by the varying state of the four sides of the original. The image reading apparatus includes an image reading unit configured to read the original image by scanning the original, an edge determining unit configured to determine first edge locations at the left end and right end of the original image in a main scanning direction, an edge detector configured to detect a second edge location of the original image in a sub-scanning direction, a tilt expression calculator configured to calculate a linear expression that represents the amount of inclination of the original image with respect to the main scanning direction.

Abstract: An image forming apparatus includes: a photosensitive member; a process member configured to act on the photosensitive member; and a light scanning apparatus configured to emit a light beam to the photosensitive member. The light scanning apparatus includes: a light source; a rotary polygon mirror; a first signal generating unit configured to receive the light beam deflected by the rotary polygon mirror to generate a first signal indicating a scan starting position; and a second signal generating unit configured to generate a second signal based on a rotation angle of the rotary polygon mirror. A lighting-up timing of the light source for generating the first signal is determined based on a number of the second signals after a voltage for image formation is applied and a relationship between the first signal and the second signal is obtained before the voltage is applied and after the rotary polygon mirror is rotated.

Abstract: An image reading apparatus which is capable of successfully reading an image off an original by correctly detecting a size of the original without degrading productivity even if mixed-size originals are placed on an original tray with edges not aligned. An image reading unit reads an image off an original passing through a reading position. An original size detection sensor detects an original. A first original size is determined using a result of detection by the original size detection sensor, and a second original size is determined using the image read off the original. The first original size or the second original size is adopted as an original size.

Abstract: An image reading apparatus capable of recognizing edge portions of an original image with precision is provided. The image reading apparatus uses an image reading unit to scan an original being conveyed and read an image of the original. The image reading apparatus includes an edge information obtaining unit and an edge determining unit. The edge information obtaining unit detects an image of an edge portion of the original image and obtains, for each point in a main scanning direction, edge information, which indicates whether or not an edge portion image is detected at the point in a sub-scanning direction. The edge determining unit conducts detection from at least one of two directions of the main scanning direction to detect a point where a given number of successive edge portion images are detected, and obtains an edge portion based on the detected point.

Abstract: An image forming apparatus includes multiple light emitting elements (LDs) as a light source, controls the light source such that laser beams emitted from LD1 and LDN are sequentially incident on a BD sensor in a non-image-forming period, and measures a time interval between two BD signals output sequentially from the BD sensor. When image formation is performed subsequent to the non-image-forming period, the image forming apparatus controls the light source such that a laser beam from the LD1 is incident on the BD sensor. Furthermore, using a single BD signal output from the BD sensor as a reference, the image forming apparatus controls timings at which the LDs emit laser beams based on the image data, according to the measurement value of the time intervals between the BD signals.

Abstract: A bus arbiter (101) is provided to a bus (107). The bus (107) is connected to a plurality of bus masters, such as a CPU (410) and a serial I/F (413), to each of which a priority is given. The bus arbiter (101) changes the priorities of the plurality of bus masters at cycles determined in advance. The bus arbiter (101) receives a request signal for making a request for use of the bus (107) from at least one bus master. Based on the priorities of the respective bus masters at a time when the request signal is received, the bus arbiter (101) identifies one bus master given the highest priority among the at least one bus master that has transmitted the request signal. The bus arbiter (101) transmits a grant signal for permitting the use of the bus (107) to the identified one bus master.

Abstract: Provided is an image reading apparatus configured to recognize edge portions of an image of an original precisely without being influenced by the varying state of the four sides of the original. The image reading apparatus includes an image reading unit configured to read the original image by scanning the original, an edge determining unit configured to determine first edge locations at the left end and right end of the original image in a main scanning direction, an edge detector configured to detect a second edge location of the original image in a sub-scanning direction, a tilt expression calculator configured to calculate a linear expression that represents the amount of inclination of the original image with respect to the main scanning direction.

Abstract: An image reading apparatus capable of recognizing edge portions of an original image with precision is provided. The image reading apparatus uses an image reading unit to scan an original being conveyed and read an image of the original. The image reading apparatus includes an edge information obtaining unit and an edge determining unit. The edge information obtaining unit detects an image of an edge portion of the original image and obtains, for each point in a main scanning direction, edge information, which indicates whether or not an edge portion image is detected at the point in a sub-scanning direction. The edge determining unit conducts detection from at least one of two directions of the main scanning direction to detect a point where a given number of successive edge portion images are detected, and obtains an edge portion based on the detected point.

Abstract: An image forming apparatus including: a photosensitive member; a process member configured to act on the photosensitive member; and a light scanning apparatus configured to emit a light beam to the photosensitive member. The light scanning apparatus includes: a light source; a rotary polygon mirror; a first signal generating unit configured to receive the light beam deflected by the rotary polygon mirror to generate a first signal indicating a scan starting position; and a second signal generating unit configured to generate a second signal based on a rotation angle of the rotary polygon mirror. A lighting-up timing of the light source for generating the first signal is determined based on a number of the second signals after a voltage for image formation is applied and a relationship between the first signal and the second signal is obtained before the voltage is applied and after the rotary polygon mirror is rotated.

Abstract: An image reading apparatus which is capable of successfully reading an image off an original by correctly detecting a size of the original without degrading productivity even if mixed-size originals are placed on an original tray with edges not aligned. An image reading unit reads an image off an original passing through a reading position. An original size detection sensor detects an original. A first original size is determined using a result of detection by the original size detection sensor, and a second original size is determined using the image read off the original. The first original size or the second original size is adopted as an original size.

Abstract: An image forming apparatus including: a photosensitive member; a charging unit; a light scanning apparatus configured to emit a light beam to scan the photosensitive member to form a latent image; and a developing unit configure to develop the latent image. The light scanning apparatus includes a light source, a rotary polygon mirror, a light receiving unit, and a signal generating unit. An incident timing when the light beam deflected by the polygon mirror enters the light receiving unit after the photosensitive member is charged by the charging unit and after a voltage is applied to a toner carrying member by the developing unit is identified based on the number of second signals generated by the signal generating unit between the first signal and the first signal generated by the light receiving unit before the photosensitive member is charged and before the voltage is applied to the toner carrying member.

Abstract: An image forming apparatus that executes processes necessary for image formation in a distributed manner. An image forming module (304) executes a process assigned by a sub master control unit (330) and a slave control unit (331) which are connected to each other by a pair of serial communication buses (380tx, 380rx). The sub master control unit (330) transmits first data for executing a process assigned to the slave control unit (331) via the serial communication bus (380tx). The slave control unit (331) transmits second data to the sub master control unit (330) via the serial communication bus (380rx) in a period during which the slave control unit (331) does not receive the first data.

Abstract: An image forming apparatus including: a photosensitive member; a charging unit; a light scanning apparatus configured to emit a light beam to scan the photosensitive member to form a latent image; and a developing unit configure to develop the latent image. The light scanning apparatus includes a light source, a rotary polygon mirror, a light receiving unit, and a signal generating unit. An incident timing when the light beam deflected by the polygon mirror enters the light receiving unit after the photosensitive member is charged by the charging unit and after a voltage is applied to a toner carrying member by the developing unit is identified based on the number of second signals generated by the signal generating unit between the first signal and the first signal generated by the light receiving unit before the photosensitive member is charged and before the voltage is applied to the toner carrying member.

Abstract: An image forming apparatus includes multiple light emitting elements (LDs) as a light source, controls the light source such that laser beams emitted from LD1 and LDN are sequentially incident on a BD sensor in a non-image-forming period, and measures a time interval between two BD signals output sequentially from the BD sensor. When image formation is performed subsequent to the non-image-forming period, the image forming apparatus controls the light source such that a laser beam from the LD1 is incident on the BD sensor. Furthermore, using a single BD signal output from the BD sensor as a reference, the image forming apparatus controls timings at which the LDs emit laser beams based on the image data, according to the measurement value of the time intervals between the BD signals.

Abstract: The present image forming apparatus includes a first control unit and a second control unit driven by built-in clock oscillators to realize the distributed control. The first control unit generates, using a first timer driven by the built-in clock oscillator of the first control unit, a pulse signal corresponding to a predetermined clock rate and outputs the pulse signal to the second control unit. The second control unit measures, using a second timer driven by the built-in clock oscillator of the second control unit, a pulse width of the pulse signal outputted from the first control unit, and calculates a correction coefficient using reference pulse width corresponding to the predetermined clock rate and the measured pulse width. The processing unit processes using the calculated correction coefficient.

Abstract: The information processing system includes an arithmetic processing unit, a master control unit including a master memory, and slave control units each including a slave memory. The master control unit stores in a master memory transmission data including address information that can designate the address of any one of the master memory and the slave memory, which is sent from the arithmetic processing unit, or transmits the transmission data to the corresponding slave memory via a communication data memory. Such the information processing system can reduce the number of times of directions from the master control unit to the slave control unit.

Abstract: This invention provides an image forming apparatus to which a distributed control system is applied and which improves error detection accuracy in each control unit. To accomplish this, the image forming apparatus includes a master control unit which controls the overall image forming apparatus, a plurality of sub-master control units which control a plurality of functions required to implement image formation, and a plurality of slave control units which control loads required to implement the plurality of functions. Each slave control unit includes a monitoring unit which monitors the operation of the other active slave control unit and performs an error diagnosis when the slave control unit is inactive.

Abstract: The information processing system includes an arithmetic processing unit, a master control unit including a master memory, and slave control units each including a slave memory. The master control unit stores in a master memory transmission data including address information that can designate the address of any one of the master memory and the slave memory, which is sent from the arithmetic processing unit, or transmits the transmission data to the corresponding slave memory via a communication data memory. Such the information processing system can reduce the number of times of directions from the master control unit to the slave control unit.

Abstract: A bus arbiter (101) is provided to a bus (107). The bus (107) is connected to a plurality of bus masters, such as a CPU (410) and a serial I/F (413), to each of which a priority is given. The bus arbiter (101) changes the priorities of the plurality of bus masters at cycles determined in advance. The bus arbiter (101) receives a request signal for making a request for use of the bus (107) from at least one bus master. Based on the priorities of the respective bus masters at a time when the request signal is received, the bus arbiter (101) identifies one bus master given the highest priority among the at least one bus master that has transmitted the request signal. The bus arbiter (101) transmits a grant signal for permitting the use of the bus (107) to the identified one bus master.

Abstract: An image forming apparatus that executes processes necessary for image formation in a distributed manner. An image forming module (304) executes a process assigned by a sub master control unit (330) and a slave control unit (331) which are connected to each other by a pair of serial communication buses (380tx, 380rx). The sub master control unit (330) transmits first data for executing a process assigned to the slave control unit (331) via the serial communication bus (380tx). The slave control unit (331) transmits second data to the sub master control unit (330) via the serial communication bus (380rx) in a period during which the slave control unit (331) does not receive the first data.