Nec Corporation

Canon Kabushiki Kaisha

Sadao Fujita

Emmanuel Le Taillandier De Gabory

Kiyoshi Fukuchi

Shuntaro Yamazaki

Koji Asahi

Minoru Shikada

An optical transmitter includes optical modulation means for modulating a laser beam with a driving signal and outputting an optical signal; monitor means for detecting a part of the optical signal and outputting a monitor signal; bias voltage applying means for applying, to the optical modulation means, a bias voltage on which a dither signal is superimposed; average optical intensity detection means for detecting an average optical intensity of the optical signal from the monitor signal; top dither signal detection means for detecting, from the monitor signal, a top dither signal that is superimposed on a waveform with maximum optical intensity included in the optical signal; and bias voltage control means for controlling the bias voltage based on the average optical intensity and the top dither signal.

Optical transmitter and method of controlling the same

To provide a modulation control method and an optical transmission device that realize high reliability by more stably performing bias control of an optical modulator using an optical QAM scheme, an optical transmitter according to the present invention comprises a first waveguide and a second waveguide, wherein each of the first waveguide and the second waveguide are provided with an optical modulator that modulates a carrier light with a modulation driving signal that has multiple strength level values, a phase shift unit that provides a predetermined phase difference between a first optical signal outputted from the first waveguide and a second optical signal outputted from the second waveguide, a light detector that detects and photoelectrically converts a portion of a multiple value optical signal obtained by multiplexing the first optical signal and the second optical signal which have been provided with the phase difference and a control circuit that, on the basis of signal amplitude information obtained by a signal amplitude detector from wideband signal components from the light detector, corrects a first voltage provided to the first waveguide and corrects a second voltage provided to the second waveguide.

Optical transmission device and control method therefor

Since it is difficult to emit a stable and reliable modulated lightwave signal by means of IQ modulators used for QAM format, a method for controlling an optical transmitter according to an exemplary aspect of the invention includes the steps of (a) keeping an optical amplitude of a continuous wave light output from the optical transmitter constant, (b) making operating point values in optical modulation converge to predetermined values during step (a), and (c) modulating the continuous wave light with multiple amplitudes and phase levels around the operating point values converged in step (b).

Optical transmitter and method for controlling the same

An image forming apparatus that can reduce the time period for rotation of an intermediate transfer unit required before toner patches are formed, and measurement of toner patch densities while continuing the rotation. A toner image formed on a photosensitive drum is transferred to a surface of the intermediate transfer unit. A toner image for detection is formed on the intermediate transfer unit, and image forming conditions are corrected based on the amount of toner obtained by reading the toner image for detection. Two density sensors read the surface of the intermediate transfer unit. Outputs from the two density sensors are stored as a first profile and a second profile, respectively. A toner density of the toner image for detection is calculated based on the first and second profiles, and image forming conditions are corrected based on the toner density.

Image forming apparatus that adopts image density control with density sensors

An image processor capable of detecting whether an image formed on a recording medium by the image forming apparatus is defective or non-defective with as high accuracy as possible and at high speed. A sheet-surface portion-determining section determines sheet-surface portions of a non-defective formed image on a pixel basis, and stores data of the sheet-surface portion/non-sheet-surface portion distribution, and extracts smallest RGB pixel values from image data of a group of pixels determined to correspond to a sheet-surface portion, to form RGB offset signals based on the smallest values. A sheet-surface portion determination-based offset section subtracts the values of the offset signals from the image data (RGB) of an inspection object. An image quality-determining section determines whether a formed image on the object is defective or non-defective on a pixel basis, using the most significant 1-bit RGB values subjected to the subtraction and the distribution data.

Image processor, control method therefor, image forming apparatus, and program

An image forming apparatus capable of identifying the amount of reflected light from any portion of an image carrier in a short time. A sensor detects reflected light from an intermediate transfer belt. A CPU performs pattern matching between the amount of reflected light from the belt corresponding to one rotation thereof and the amount of reflected light from a specific portion of the belt to thereby identify a first circumferential location of the specific portion and a second circumferential location of a toner patch formed on the belt. The CPU calculates toner patch density based on the amount of reflected light from the toner patch and the amount of reflected light from the belt in the second circumferential location. The density of a toner image to be formed on the belt is controlled according to the calculated toner patch density.

Image forming apparatus that transfers toner image carried by image carrier onto sheet, density control method therefor, and storage medium

An image forming apparatus which is capable of eliminating influence of in-plane variation contained in secondary-color patches, which is caused by devices, in performing gradation correction. A first toner pattern having a uniform density (of gray) and a second toner pattern having gradation (of gray and black) are formed in a direction orthogonal to a direction of driving an image bearing member. Gradation correction data for converting an input image signal associated with the toner of black is formed, based on density information on the second toner pattern formed by the two toners, and density information on the second toner pattern formed by the toner of gray.

Image forming apparatus

Each node of an optical ring system having m nodes connected multiplexes wavelengths of &lgr;1 to &lgr;n in optical wavelength division and transmits signals. This optical ring system is composed of working optical fibers ( - and - ) and protection optical fibers ( - and - ). Each node is composed of 4&times;4 optical switches ( and ), a first optical preamplifier ( ), a first wavelength demultiplexer ( ), a first wavelength multiplexer ( ), a first optical booster amplifier ( ), a second optical preamplifier ( ), a second wavelength demultiplexer ( ), a second wavelength multiplexer ( ), a second optical booster amplifier ( ), a third optical preamplifier ( ), a third wavelength demultiplexer ( ), a third wavelength multiplexer ( ), a third optical booster amplifier ( ), a fourth optical preamplifier ( ), a fourth wavelength demultiplexer ( ), a fourth wavelength multiplexer ( ), a fourth optical booster amplifier ( ), and line terminals ( - to - ). In each node, 2&times;2 optical switches ( - to -n and - to -n) are connected in the working optical paths, and 2&times;2 optical switches ( - to -n and - to -n) are connected in the protection optical paths.

Node for optical communication and wavelength-division multiplexing transmission apparatus having a ring structure composed of the same nodes

In an FSK laser transmitting apparatus, a light source can change the output light frequency. A driver performs FSK of the light source with a plurality of values. A beam splitter splits the output light from the light source into two split beams. A delay circuit delays one of the two split beams with respect to the other. A beam coupler combines delayed and nondelayed beams as the two split beams from the beam splitter. A controller detects the beat frequency of combined light from the beam coupler and supplies a control signal to the driver so as to set the beat frequency to be a predetermined value.

Growing community of inventors

Tokyo, Japan

Sadao Fujita