Abstract: An optical scanner includes a light source unit configured to emit light; an optical system configured to cause the light emitted from the light source unit to scan an object so as to form an image on the object; and a control unit configured to control the light source unit. The light source unit includes a plurality of light emitting units arranged in a sub scanning direction, and the control unit controls the light source unit to emit light at different positions on the object by using either n (n: positive integer) light emitting units or n+1 light emitting units selected from among the plurality of light emitting units, according to a positional shift amount of the image in the sub scanning direction.

Abstract: An oscillation frequency control part includes a voltage-to-current converting circuit converting an input voltage to a current having a value corresponding to the input voltage, and outputting a current in proportion to the current obtained from the voltage-to-current converting circuit. An oscillating circuit part includes a ring oscillator, wherein a current in proportion to the output current of the oscillation frequency control part flows through the ring oscillator so that the oscillation frequency in the ring oscillator is controlled by the output current of the oscillation frequency control part. The voltage-to-current converting circuit has linear voltage-to-current conversion characteristics in a predetermined range of the input voltage including a ground potential.

Abstract: An oscillation frequency control part includes a voltage-to-current converting circuit converting an input voltage to a current having a value corresponding to the input voltage, and outputting a current in proportion to the current obtained from the voltage-to-current converting circuit. An oscillating circuit part includes a ring oscillator, wherein a current in proportion to the output current of the oscillation frequency control part flows through the ring oscillator so that the oscillation frequency in the ring oscillator is controlled by the output current of the oscillation frequency control part. The voltage-to-current converting circuit has linear voltage-to-current conversion characteristics in a predetermined range of the input voltage including a ground potential.

Abstract: An optical scanning apparatus is disclosed that includes a light source unit having plural main light sources that are two-dimensionally arranged in the main scanning direction and the sub scanning direction, and plural sub light sources that are arranged between rows of the main light sources aligned in the main scanning direction. The optical scanning apparatus also includes an optical system configured to scan light emitted from the light source unit on a scanning object to form an image on the scanning object, and a control apparatus configured to adjust a main scanning direction image position by controlling two of the main light sources that are juxtaposed to each other with respect to the main scanning direction and adjust a sub scanning direction image position by controlling a main light source and a sub light source that are adjacent to each other.

Abstract: An output device is disclosed that includes an impedance matching section including an impedance adjustment section, and a dummy circuit section having the same configuration as the impedance adjustment section and adapted to calculate an adjustment value for matching an output impedance to a characteristic impedance of the transmission line. The impedance matching section sets the adjustment value to an impedance adjustment section, thereby matching the output impedance to the characteristic impedance. The output device further includes a switching transistor configured to be turned on/off so as to switch the output between an H level and an L level, and a constant current driver configured to add a constant current to the output.

Abstract: A circuit for generating a pixel clock for use in scanning a laser beam includes a high-frequency-clock generating circuit which generates a high-frequency clock having a higher frequency than the pixel clock, and a control circuit which generates the pixel clock while shifting a phase of the pixel clock by a shift step proportional to a clock cycle of the high-frequency clock in response to phase data indicative of timing and amounts of phase shifts.

Abstract: A pixel clock generation circuit is disclosed, including a high frequency clock generation unit configured to generate high frequency clock, a clock modulation data generation unit configured to generate clock modulation data based on pixel clock phase data indicating timing of a transition in pixel clock. The pixel clock generation circuit further includes a modulation clock generation unit configured to modulate the frequency and phase of the high frequency clock based on the modulation data thereby to generate modulated pixel clock.

Abstract: A pixel clock generator that generates a pixel clock to regulate a drive timing of a scanning light source includes a data generating circuit that generates phase data based on a phase data pattern to correct an uneven scanning speed and fluctuation of scanning widths, and a pixel clock generating circuit generates a pixel clock having a long cycle based on a high-frequency clock and that performs a phase shift for the pixel clock based on the high-frequency clock. The phase pattern is set-such that difference in an amount of the phase shift between the pixel clocks adjacent to each other does not exceed a basic amount of the phase shift of the pixel clock generating circuit.

Abstract: A semiconductor laser modulation signal is generated for modulating a semiconductor laser. The semiconductor laser is driven based on the semiconductor laser modulation signal. An output impedance of a semiconductor laser modulation signal generating unit and an input impedance of a semiconductor laser driving unit are corrected. The semiconductor laser modulation signal is transmitted as a low amplitude differential signal, from the semiconductor laser modulation signal generating unit to the semiconductor laser driving unit.

Abstract: A pixel clock generation apparatus includes a detector detecting a time interval between two horizontal synchronization signals. A comparing part compares the time interval detected by the detector and a target value, and outputs the difference. A phase shift data generation part stores one or more lookup tables each storing a pattern of phase shift data for controlling a phase shift amount of a pixel clock, and reads and outputs the phase shift data from the lookup table based on the difference that is output from the comparing part. A high frequency clock generation part generates a high frequency clock. A pixel clock generation part generates the pixel clock whose phase is controlled in accordance with the phase shift data based on the high frequency clock.

Abstract: A pixel clock generating device includes a measurement unit that measures a scanning time required for scanning a length and outputs a measured value, a pixel clock generating unit that generates a pixel clock, and a reference clock generating unit that generates a reference clock having a frequency higher than the pixel clock. A phase of the pixel clock is controlled based on (i) the reference clock and (ii) a comparison result between the measured scanning time and a preset scanning time.

Abstract: A pixel clock and pulse-modulation-signal generating device includes a high-frequency-clock generating unit that generates a high-frequency clock; a modulation-data generating unit that generates, based on pixel control data that specifies a pixel length and image data, phase data that indicates a transition timing of a pixel clock and modulation data that indicates a desired bit pattern that corresponds to the image data; a pixel-clock generating unit that generates a pixel clock based on the high-frequency clock, the phase data, and a horizontal synchronization signal; and a serial-modulation-signal generating unit that inputs the modulation data, and outputs a pulse modulation signal in a serial pulse string based on the high-frequency clock.

Abstract: In a pixel clock creation method and device, a high frequency clock is created. A scanning time needed to scan a predetermined scanning length is detected in accuracy of half a period of the high frequency clock to output a detection value indicating the detected scanning time. The detection value and a predetermined target value are compared to output a comparison result. A phase data is created based on the comparison result. A pixel clock whose phase is controlled based on both the high frequency clock and the phase data is created.

Abstract: A color image forming apparatus produces a latent image on a photosensitive body based on a signal output from a scanning light detecting part in response to detection of scanning light; a semiconductor laser modulation signal generating part includes a clock generating part and a clock modulation part; a semiconductor laser and a semiconductor laser driving part are provided for each color of yellow, magenta, cyan and black; and further, a plurality of the semiconductor lasers are provided for at least one color of yellow, magenta, cyan and black.

Abstract: An oscillation frequency control part includes a voltage-to-current converting circuit converting an input voltage to a current having a value corresponding to the input voltage, and outputting a current in proportion to the current obtained from the voltage-to-current converting circuit. An oscillating circuit part includes a ring oscillator, wherein a current in proportion to the output current of the oscillation frequency control part flows through the ring oscillator so that the oscillation frequency in the ring oscillator is controlled by the output current of the oscillation frequency control part. The voltage-to-current converting circuit has linear voltage-to-current conversion characteristics in a predetermined range of the input voltage including a ground potential.

Abstract: A laser modulating and driving device comprises a modulation signal generating unit configured to generate a laser modulation signal consisting of a pair of small swing differential signals based on pixel data, and a driving unit configured to drive a laser according to the laser modulation signal supplied from the modulation signal generating unit.

Abstract: A circuit for generating a pixel clock for use in scanning a laser beam includes a high-frequency-clock generating circuit which generates a high-frequency clock having a higher frequency than the pixel clock, and a control circuit which generates the pixel clock while shifting a phase of the pixel clock by a shift step proportional to a clock cycle of the high-frequency clock in response to phase data indicative of timing and amounts of phase shifts.

Abstract: A pixel clock generation apparatus includes a detector detecting a time interval between two horizontal synchronization signals. A comparing part compares the time interval detected by the detector and a target value, and outputs the difference. A phase shift data generation part stores one or more lookup tables each storing a pattern of phase shift data for controlling a phase shift amount of a pixel clock, and reads and outputs the phase shift data from the lookup table based on the difference that is output from the comparing part. A high frequency clock generation part generates a high frequency clock. A pixel clock generation part generates the pixel clock whose phase is controlled in accordance with the phase shift data based on the high frequency clock.

Abstract: There is provided a pixel clock generating device, a laser scanning device and an image forming device able to control the width of a pixel clock with high precision but a simple configuration, and to correct fluctuation of the scanning length with high precision. The number of clocks in a period of scanning a distance between two photo detectors is counted, and comparison is made between the count and an object value. Based on this comparison, a determination is made of the timing of changing the level of the pixel clock that determines the scanning length (timing of transition). Furthermore, there is provided a configuration for generating a high frequency clock. Being synchronized with the high frequency clock, the pixel clock is generated based on the timing of transition. The laser driving device drives the semiconductor laser based on the generated pixel clock and the input image data.