Abstract: A system and method is disclosed for providing a robust ultra low power serial interface with a digital clock and data recovery circuit for power management systems. In one advantageous embodiment a digital clock and data recovery circuit of the invention comprises a quadruple phase clock generator circuit that generates four shifted clock signals, a decision logic circuit, a state detector circuit, and an edge detector circuit. The detected edges of data signals are used to latch the state of the four shifted clock signals. The state detector circuit selects a stable clock signal among the four shifted clock signals for use as a recovered clock signal and synchronizes the recovered clock signal at a center of the data signal. The selected recovered clock signal remains available until another data signal transition is detected.

Abstract: An image reading apparatus accurately determines the positions of image forming mirrors formed with an off-axis reflecting surface, while enabling any thermal expansion caused by a rise in temperature due to a rise in the surrounding temperature to be absorbed. Each image forming mirror formed with an off-axis reflecting surface comprises respective and independent units for determining the positions in the longitudinal direction, in the lateral position, and in the direction orthogonal to the reflecting surface. Holes with which the longitudinal position determining units and the lateral position determining units engage have gaps in the directions orthogonal to the position determining directions to absorb the thermal expansion caused by a rise in the temperature of the image forming mirror when the position determining units engage with the holes.

Abstract: A module for synthesizing image-sensing signals comprises a first image-sensing element, a second image-sensing element, and an analog adder. The first and the second image-sensing elements are connected in parallel to an input port of the analog adder. The module provides an AD converter whose input port connects an output port of the analog adder. An output port of the AD converter connects a scanner controller. The scanner controller provides a first driving signal and a second driving signal to the first and the second image-sensing elements respectively. The first driving signals and the second driving signals respectively command the first and the second image-sensing elements to alternately output image signals during clock cycle. The image signals outputted from the first and the second image-sensing elements are composed by the analog adder.

Abstract: A signal delay structure and method of reducing skew between clock and data signals in a high-speed serial communications interface includes making a global adjustment to the clock signal in the time domain to compensate for a component of the skew that is common between the clock and all data signals. This can include skew caused by the variation in frequency of the input clock from a nominal value, misalignment between the phase of the clock and data generated at the source of the two signals. The global adjustment is made through a delay component that is common to all of the clock signal lines for which skew with data signals is to be compensated. A second level adjustment is made that compensates for the component of the skew that is common to the clock and a subset of the data signals.

Abstract: A data communication apparatus is provided with an image reader which reads a document image, a storage which stores image data of the document image read by the image reader and registers one or a plurality of transmitting destinations, a data communication unit having a plurality of communication lines, and a communication control unit which controls a transmission start timing of the image data to the transmitting destinations. The communication control unit controls the data communication unit to start transmitting the image data to a first transmitting destination at a timing when reading of the document image by the image reader starts, when a plurality of transmitting destinations are registered.

Abstract: The tracking of the phase of a received signal having a known preamble is accomplished by the steps of: initializing a phase-locked loop in accordance with estimated phase parameters, which are generated during an estimation interval by processing samples of the known preamble; delaying the preamble; generating phase error parameters by processing samples of the delayed preamble; and training the phase locked loop by tracking the phase-tracked signal in accordance with the tracking error parameters during a training interval after the estimation interval. The timing of the sampling is likewise trained in a closed timing loop in accordance with timing error parameters generated during the training interval after the timing loop has been initialized by estimated timing parameters generated during the estimation interval. The duration of the delay of the preamble is one-half the duration of the estimation interval.

Abstract: There is provided a printer control apparatus which can be applied to an image forming apparatus in which a plurality of types of readers and a plurality of types of printers can be connected to a single controller, and which enable efficient transfer of image data from the reader to the printer via an image memory of the controller. The controller receives image data from a reader and temporarily stores the same in an image memory, and transmits the stored image data to a printer. The controller acquires a reader processing speed from the reader and a printer processing speed from the printer, and determines, while the image data is being written to the image memory, timing for transmitting the image data written in the memory to the printer according to a difference between the reader processing speed and the printer processing speed and a sub-scan size of the image data.

Abstract: An image forming apparatus using a synchronization signal generator can easily generate a pixel clock that enables both a magnification correction in a main scanning direction and a correction of expansion and contraction of pixel width in the main scanning direction. Each of pixel clock generation units generates a clock signal by dividing a frequency of a high-frequency clock so as to generate pulses of a reference period, a long period longer than the reference period and a short period shorter than the reference period, and outputs, as the pixel clock, one of the pulses that is designated by an output selection signal. A pixel clock correction data synthesizing unit synthesizes a first selection signal, which is generated base on a time-series distribution of the pulses of each period defined by a first set of data, and a second selection signal, which is based on a time-series distribution of the pulses of each period defined by a second set of data, so as to generate the output selection signal.

Abstract: A method of faxing a multi-page job via a facsimile device. Accordingly, the method includes scanning a page of the multi-page job with the facsimile device, encoding the scanned page as a fax signal, and loading the fax signal into a buffer memory. Each page of the multi-page job is scanned, encoded, and loaded. The method further includes transmitting the fax signals encoded from each page of the multi-page job from the buffer memory to a recipient fax device in a single transmission.

Abstract: There is described an apparatus, which includes an image-forming section to form a multicolor image on a recording medium by recording the unicolor images in such a manner that the unicolor images overlap each other, based on printing image data sets of them, and a controlling section that determines at least a sub-scanning velocity in a sub-scanning direction relative to the recording medium, corresponding to a printing magnification factor, so as to adjust an output-start timing in the sub-scanning direction for every printing image data set, in response to the sub-scanning velocity determined in advance. Further, the controlling section also determines a main-scanning velocity in a main-scanning direction, corresponding to the printing magnification factor, so as to adjust output-start timings in both the main-scanning direction and the sub-scanning direction for every printing image data set, in response to the main-scanning velocity and the sub-scanning velocity, both determined in advance.

Abstract: A sampling-error phase compensating device and a method thereof for sequentially sampling data signals and outputting sampled data signals.

Abstract: To provide a technology which facilitates positioning of a document to a document table even in a condition of a vertically placed image reading apparatus and by which operability was improved. It is configured in such a manner that, in case that a document cover 6 was opened to an apparatus main body 1 in the vertically placed condition, (a distance c between a document table glass 2 of an apparatus main body 1 and an end portion 57 of a lowermost portion of a press-contact sheet 8)<(a step (a height from the document table glass 2) d of a step 58a) is realized.

Abstract: In a symbol timing detector, a correlator calculates a correlation value for a received radio packet signal. A peak detector compares the correlation value with a threshold value to be used, and sends, upon a correlation value detected larger than the threshold value, a detection signal to a symbol synchronous processor. A threshold value to be used for the peak detector is set different, after the first peak detected, between a predetermined estimation period and a period other than the former. A first peak is detected with a threshold value under a severer condition in the period other than the estimation period, and the next peak detection timing is estimated upon the first peak detected. A synchronization detecting position is determined, when no correlation peak is detected at the estimated timing, to output a sync detection signal.

Abstract: An image transmission apparatus and method for use with at least two transmission paths having different transmission rates from one another. The image transmission apparatus comprises an image input for receiving an image signal, a coding processing unit for encoding the image signal, a protocol control unit for packetizing the data encoded by the coding processing unit to generate data packets for transmission, and a transmission unit for transmitting the data packets. The protocol control unit has at least one timer processing unit which controls a data packet transmission interval individually corresponding to the transmission rates of the respective transmission paths based on data packet discard ratio information from the transmission paths.

Abstract: The video signal processing circuit has a clamp circuit for clamping a composite video signal including a copy guard signal with amplitude of from white to black as well as a pseudo horizontal synchronization signal, a brilliant signal, and a synchronization signal. The circuit also has a synchronization signal separation circuit, which separates the synchronization signal from the composite video signal and a synchronization signal discrimination circuit, which identifies if the synchronization signal coming from the synchronization signal separation circuit has the same cycle as that of a horizontal synchronization signal, and which blocks the signal with the cycle shorter than the cycle of the horizontal synchronization signal, letting only the signal with the cycle of the horizontal synchronization signal pass.

Abstract: An image reading device includes a reading unit and a controller connected to the reading unit through a transmission path. The controller includes: a first clock generator which generates a first reference clock; a second clock generator which generates a second reference clock; a line synchronizer which generates a line synchronization signal based on the first reference clock; a clock transmitter which transmits the line synchronization signal and a unit clock based on the first reference clock to the reading unit; and a processor which execute a process based on the second reference clock and which is synchronized with the line synchronization signal. The reading unit includes a reading sensor which reads a document line by line based on the unit clock and the line synchronization signal.

Abstract: A multimedia processing system and method thereof are provided. The system and method provide for synchronizing a first clock of a multimedia decoder of a first multimedia processing device to a second clock of a multimedia encoder of a second multimedia processing device, synchronizing a first timing reference of the multimedia decoder to a second timing reference of the multimedia encoder, receiving, at a network interface of the first multimedia processing device, an encoded multimedia data stream from a network interface of the second multimedia processing device, wherein the encoded multimedia data stream is encoded by the multimedia encoder based on the second clock and the second timing reference, and decoding the encoded multimedia data stream at the multimedia decoder based on the first clock and the first timing reference.

Abstract: Provided are a method and apparatus for generating a synchronization signal. The method includes generating a square wave signal based on a sensing signal, which shows a motion of a scanner, and a specified threshold signal, generating a reference signal having a phase locked reference frequency, based on the generated square wave signal, and generating a synchronization signal synchronized with the motion of the scanner, based on the generated reference signal. By outputting an image signal according to the generated synchronization signal, the motion of the scanner and the image signal can be synchronized.

Abstract: A memory read control unit (606) reads out image data of one pixel from a memory (603) in synchronism with a clock signal. On the basis of the image data of one pixel, a converting unit (604) converts the density of a corresponding pixel into digital data of a plurality of bits and stores the digital data in a shift register (606). A pixel-piece insertion and deletion control unit (607) inserts data of one bit into the shift register or deletes data of one bit from the shift register. The pixel-piece insertion and deletion control unit (607) estimates a data storing state in the shift register and controls image data read-out from the memory (603) in accordance with the estimated data storing state.

Abstract: A method of self-synchronizing clocks in a multiple chip system, by assigning one chip as the master chip and the other chips as slave chips. A training signal is sent from master chip to the slave chips to determine the latency from the master chip to a slave chip, and then a synchronization signal is sent out to synchronize the “time zero” of the chips.

Abstract: Image data having a total number of pixels being H×V is written in SDRAM having an enough number of recording domains capable of storing all the pixel data of the image data and the number of Column addresses set therein at 2n (4?n) in the order of lines after the implementation of a first image rotation processing at a rotation angle of 90°×m (0?m?3) to the image data and read from the SDRAM in the order of the lines after the implementation of a second image rotation processing at a rotation angle of 90°×p (0?p?3). In doing so, the recording domains of the SDRAM are divided into a plurality of recording blocks 21-s having the number of the Column addresses set therein at 2q (2?q?(n?2) and capable of storing groups of the pixels for one line in the image data after the implementation of the first image rotation processing. The groups of the pixels for one line in the image data in an image direction after the implementation of the first image rotation processing are written in the recording blocks 21-s.

Abstract: In an image forming apparatus, screen information for displaying a plurality of function options available for a predetermined process is generated. A screen generating program and option information showing the plurality of function options is transmitted in response to an request from an apparatus that is connected through a network and the user uses. The predetermined process is conducted by using a hardware resource when receiving the setting parameter indicating the function option set by the user from the plurality of the function options that the apparatus displays by executing said screen generating program, from the apparatus.

Abstract: Provided are a method and apparatus for compensating display distortion generated when the image is formed using the operational characteristic of a scanner. The method for compensating a display distortion in a display system includes: dividing a sync section where image data is output into a plurality of sections; setting a clock speed of the image data for each of the sections based on an operational characteristic of a scanner; and outputting the image data at a different clock speed for each divided section, the different clock speed reflecting a set clock speed for each divided section.

Abstract: An object of this invention is to provide an image processing apparatus capable of preventing any color misregistration in printing even when the image processing apparatus is divided into a plurality of semiconductor integrated circuits. An image processing apparatus is used for an image forming apparatus for sequentially printing image processing results of color components by a plurality of photosensitive drums separated by predetermined distances in correspondence with the colors. In the image processing apparatus, a plurality of image processing sections for the respective color components are divided into a plurality of semiconductor integrated circuits. At least two of the plurality of image processing sections have storage sections which adjust the printing timings of the color components corresponding to the distances between the photosensitive drums.

Abstract: When executing e-document scan, an image scanning device scans a document and stores scanned data. After resetting a timer, the image scanning device calculates a hash value of the scanned data, and transmits the calculated hash value to a TSA to request the TSA to issue a timestamp. When receiving a timestamp from the TSA, the image scanning device stores the scanned data and the timestamp in an e-document folder. When failing to receive a timestamp within a prescribed period of time after requesting the timestamp, the image scanning device adds a comment to the scanned data indicating that the timestamp failed to be received, and prints out the scanned data with the comment.

Abstract: An image reading apparatus which includes a timing adjusting circuit for adjusting a generation timing of a drive signal for driving at least an image pickup element which reads an object image and outputs an image signal of the object image, a memory circuit for storing an adjustment value of the generation timing of the drive signal adjusted by the timing adjusting circuit, and a drive signal generating circuit for generating the drive signal in accordance with the adjustment value stored in the memory circuit.

Abstract: There is provided a printer control apparatus which can be applied to an image forming apparatus in which a plurality of types of readers and a plurality of types of printers can be connected to a single controller, and which enable efficient transfer of image data from the reader to the printer via an image memory of the controller. The controller receives image data from a reader and temporarily stores the same in an image memory, and transmits the stored image data to a printer. The controller acquires a reader processing speed from the reader and a printer processing speed from the printer, and determines, while the image data is being written to the image memory, timing for transmitting the image data written in the memory to the printer according to a difference between the reader processing speed and the printer processing speed and a sub-scan size of the image data.

Abstract: A method and a system for increasing scanning speed are provided. The method may include determining a transmission rate of a transit interface, scanning an original to generate an image data, and adjusting a cycle time of the image data to change a data generating rate responsive to the transmission rate of the transit interface. One aspect of the present disclosure may be by adjusting the cycle time of a state machine to change the data generating rate corresponding to the transmission rate of the transit interface. Therefore, in response to the transmission rate of the transit interface, the cycle time of the state machine may be adjusted to produce the data at a rate that prevents the smearing process. Thus, the possibility of memory buffer full may be reduced, which may lead to the reduction in start-stop processes and therefore the overall scanning speed may be increased without necessarily requiring the increase in size of a memory buffer.

Abstract: An image forming device includes a printer engine, a display unit, and a sound reproducing unit. The image forming device receives a list of contents from a content distributing device, and has the display unit display the content list. From the content list displayed by the display unit, a user of the image forming device selects a print content, a display content, and a sound content that he desires, associates the selected contents with one another to produce a group of the selected contents, and requests the content distributing device to distribute the group of the selected contents. The content distributing device produces the group of contents associated with one another, and distributes the group of contents to the image forming device. The image forming device expands the print content in the distributed content group into print data, and has the printer engine print the print data.

Abstract: This invention is to obtain a multi-beam scanning apparatus which always executes synchronization detection at the same timing to prevent any jitter, and an image forming apparatus using the apparatus. In a multi-beam scanning apparatus which guides a plurality of light beams emitted from a light source to an optical deflector, guides the plurality of light beams deflected by the optical deflector onto a target scanning surface through a scanning lens system, and guides some of the plurality of light beams deflected by the optical deflector to a synchronization detecting unit to execute synchronization using a sync signal obtained by the synchronization detecting unit, the synchronization detecting unit includes a BD slit which determines the synchronization detecting timing, and the BD slit has a smooth member.

Abstract: The present invention relates to a facsimile gateway device capable of easily avoiding interruption of facsimile communication due to a delay in data transmission via the Internet, without changing a communication procedure. A main control unit of the gateway device receives facsimile image data from one facsimile machine via the Internet, and stores the image data into an image data memory area of a hard disk drive. When transmitting the image data to a destination facsimile machine via a public switched telephone network, the gateway device transmits a TCF signal, to which error data is appended, if image data of one page worth is not stored in the image data memory area. The TCF signal is a procedure signal for facsimile communication, and is a test data for training. The error data is, for example, all “1” data.

Abstract: Print control program, by its constituent portions in cooperation with a scanner apparatus, spools image data sent from the scanner apparatus and controls the print engine etc. of the printer apparatus to print out the spooled image data. The print control program prepares job attribute information used for obtaining the output rate of the printer apparatus, calculates an anticipatory spool amount based on the job attribute information of the printer apparatus thus prepared and job attribute information received from the scanner apparatus, and adjusts timing for printing out the spooled image data.

Abstract: A facsimile machine is provided that can shorten a time period required for a pre-transmission procedure through simple manipulation, thus improving the transmission efficiency. Moreover, a facsimile communications method using the facsimile machine is provided. When initial facsimile transmission is performed to an opposite party of which a number is registered corresponding to at least one of abbreviated dialing and one-touch dialing, a partial step of a pre-communication procedure is stored in correspondence with the registered number. In the second or later communications to the registered number, a stored content is read out. Then, by allocating the stored content to said partial step, a required communication time period is shortened. The facsimile machine has a memory that stores number information on abbreviated dialing and/or one-touch dialing and required information corresponding to the number information.

Abstract: When correction data is set, a CPU 3 reads out the correction data from an EEPROM 8 through strobe signal lines STB1-N to STB4-N and supplies it as print data signals DATA3 to DATA0 to an LED driver IC 6. When the driving of an LED array 7 according to print data is instructed, the CPU 3 supplies a group selection signal to the LED array 7 through the strobe signal lines STB1-N to STB4-N. An electrophotographic printer which can realize a high speed of the operation and contribute to the improvement of the reliability is provided.

Abstract: An image forming apparatus which forms an image on a recording material, which has: a writing section to write according to the image data; an oscillator to generate a synchronized synchronizing clock signal; a spreading clock generator to spread the band of a synchronized reference clock and generate spreading clock signals; and a plurality of control circuits to control the image forming apparatus and each section of the image forming apparatus including a writing control circuit to control the writing section. More than one control circuits in the control circuits other than the writing control circuit are driven by the spreading clock signals, and the writing control circuit is driven by the synchronizing clock signal.

Abstract: A scanner with an output port connected to a printer or a storage device. The scanner includes a casing, a scanning module installed inside the casing for scanning a document and generating corresponding image data, a control unit installed in the casing for controlling the operations of the scanner, and an output port electrically connected to the control unit for connecting to an external printer or a portable storage device. When the scanning module finishes scanning a document, the control unit transmits the image data of the document to the storage device or to the printer for printing according to the type of device connected to the output port.

Abstract: A printer comprises, from upstream to downstream, a loader for articles to be printed, a printing device and transfer elements to direct sequentially the articles from the outlet of the loader to the printing device and from the printing device toward collection elements for the printed articles. The outlet drive element for the articles from the loader, has a cylinder in contact with the articles to be printed by an opening provided in a wall of the loader, and is moved by a motor common to the transfer elements. The contact between the cylinder and the articles is sequentially interrupted by an isolating device moved by a mechanical connection with the motor of the printing device.

Abstract: The invention provides an image reading apparatus that produces a precise image of an original document to prevent the read image from having distortion or irregular density, by driving a DC motor, which drives an image reading unit in a scanning direction, at a constant speed suitable for a document to be read. In addition, the image reading apparatus prevents position errors or misalignment at the start of the image reading, or at a restart of the image reading after the image reading is paused. A speed control circuit provides feedback to a DC motor to synchronize a time interval detected by a pulse interval detecting circuit with a time interval set by an interval setting register, so that the DC motor is operated at a constant speed. A counter counts the number of signals output from an encoder. After the speed of the DC motor is stabilized, a timing of signals output from a CCD drive unit to the image reading unit is synchronized with a timing of the signals generated by the encoder.

Abstract: To enable processing both the image data of RGB and the image data of CMYK and enhance printing speed, the following measures are taken. An image processor for printing according to the present invention is provided with an expander for expanding both the image data in the first color space of RGB and others and the image data in the second color space of CMYK and others and image data supply means for converting expanded image data to the image data in the second color space and supplying it to a print engine if the expanded image data is the image data in the first color space or supplying expanded image data to the print engine without converting it if the expanded image data is the image data in the second color space.

Abstract: A clock signal is frequency-modulated and an image processing operation is executed synchronously with the frequency-modulated clock signal to generate image data which is stored in a memory. Image data written in the memory is read synchronously with a clock signal having a fixed frequency. The image data written in the memory synchronously with the frequency-modulated clock signal is therefore converted into the image data synchronizing with the clock signal having a fixed frequency. Data subjected to image processing synchronously with the frequency-modulated clock signal can be output on the recording apparatus side without any practical problem.

Abstract: Auxiliary information (150) representing binary or multi-level (M?2) logical values is embedded into successive segments (110) of an audio, video or other data signal in response to a user request to download the data signal via an on-line distributor (350) on a computer network such as the Internet. To avoid unnecessary delays in providing the data signal to the user, the data signal is pre-processed to provide two sets or copies of data (230, 235). One set (230) of the data contains segments with an embedded binary “0”, while the other set (235) contains corresponding segments with an embedded binary “1”. Successive segments are selected from one of the two sets to provide a time-multiplexed composite data signal (230) that has the desired content, but with an embedded binary data sequence that identifies the user.

Abstract: A system and method for handling facsimile transmissions in a digital communications network, such as a GSM network. In general, the process includes first synchronizing incoming binary-coded facsimile information and then recording the degree of bit-rotation exhibited by the facsimile information. Segregated portions of the incoming facsimile information are identified as either a synchronization sequence, facsimile status information, or neither type. If a portion of the incoming transmission is identified as facsimile status information, any bit-rotated condition present in the portion is compensated for prior to further processing. In addition, once the incoming information has been synchronized, every time thereafter that a synchronization sequence or facsimile status information is identified in a portion of the incoming information, this event is used as an indication that the facsimile transmission is still in synchronization.

Abstract: An image input apparatus includes a reading unit for reading a manuscript image, and a communication unit for transferring the image data, which is read by the reading unit, and control data to another apparatus. The communication unit has a first mode in which a periodic data transfer can be assured, and a second mode in which the periodic data transfer cannot be assured. The communication unit transfers the image data in the first mode, and the control data in the second mode.

Abstract: An image forming method applied to an image forming apparatus including an image inputting unit for inputting image data, a memory for storing the image data inputted from the image inputting unit, and a printer for forming the image data on an image forming medium. At a start of image forming processing on the image data inputted from the image inputting unit, if the printer is performing any other processing, all the image data inputted by the image inputting unit is stored in the memory. The printer performs image forming processing on the image data stored in the memory after completing performing the other processing.

Abstract: A synchronous detector detects timing of scanning by an optical scanner in an image forming apparatus. The optical scanner has a light source that emits a light beam, a deflecting unit that deflects the light beam, a scanning optical element that focuses the light beam deflected by the deflecting unit onto a surface to be scanned. The synchronous detector includes a photoreceiver, and a synchronous optical element that focus the light beam deflected by the deflecting unit onto the photoreceiver. The synchronous optical element satisfies a relationship fm<fd, where fm is a composite focal length of the scanning optical element in a main scanning direction, and fd is a composite focal length of the synchronous optical element in the main scanning direction.

Abstract: A continuous-tone facsimile mechanism supports a transmission rate control mode to control the transmission rate of a continuous-tone image (e.g., a color image) based on the data rate between the transmitter and receiver. The transmission rate is controlled by scaling the original quantization values based on the data rate producing scaled quantization values which are then used to compress the image. The scaled quantization values are transmitted along with the compressed continuous-tone image. Via a rate control mode, a continuous-tone facsimile device with this transmission rate control technique can allow a user to specify whether the transmission rate control is activated or deactivated.

Abstract: The object of the invention is to automatically select an optimum printing device according to the characteristics of a page in units of pages to print the page, thereby reducing the load on the operator in print processing. For this purpose, it is determined in units of pages whether data to be printed contains color information. If color information is present, a color flag is set to ON. When the color flag is ON, print data prepared and developed in a page buffer is sent to a color printer. When the color flag is OFF, the print data prepared and developed in the page buffer is sent to a monochromatic printer.

Abstract: A test image has a black bias on a white background. The black bias is a line set at about 45 degrees to the scan lines of a scanner. Boundary points of the scanned bias are found. A regression line is calculated from the positions of the boundary points. Differences in the positions of adjacent boundary points, together with the slope reciprocal of the regression line, are used to determine error values. The error values are compared with a gate value to determine if there are any occurrences of scan line misalignment.

Abstract: The multicolor image forming apparatus according to the present invention comprises openings near the edge of the laser beam scanning start side, near the center, and near the edge of the laser beam scanning end side, on the photoconductor belt. The multicolor image forming apparatus measures time intervals from the horizontal synchronizing signal to the detection of the scanning start-side opening, the center opening, and the scanning end-side opening, respectively. The multicolor image forming apparatus calculates the function indicating the scanning speed at time t along the surface of the photoconductor, to correct the function indicating an image clock frequency at time t.

Abstract: A test image has a black bias on a white background. The black bias is a line set at about 45 degrees to the scan lines of a scanner. Boundary points of the scanned bias are found. A regression line is calculated from the positions of the boundary points. Differences in the positions of adjacent boundary points, together with the slope reciprocal of the regression line, are used to determine error values. The error values are compared with a gate value to determine if there are any occurrences of scan line misalignment.