Ricoh Company, Ltd.

Kenichirou Asada

Yoshiki Yoshida

Kiyoto Nagasawa

Takanobu Fujioka

Yoshio Kaneko

Takashi Mama

Takahiro Asai

Mitsuo Hasebe

Setsuo Soga

Kazuo Murai

Akio Katsumata

Isamu Shibata

Yasumori Nagahara

Yoshiaki Kanmoto

Masaaki Kogure

An image forming apparatus that forms an image by scanning a recording medium with a plurality of light beams that are modulated by individual image forming signals respectively corresponding to the light beams. A beam detecting device detects the plurality of light beams at preset positions and outputs corresponding detection signals. At least one delay device delays each of the detection signals from the beam detecting device by an arbitrary time period which is predetermined individually for each of the detection signals. A reference clock signal generating device generates a plurality of reference clock signals on the basis of delayed detection signals output from the at least one delay device. The image forming apparatus performs an image forming operation according to the plurality of reference clock signals.

Image forming apparatus capable of controlling timing for a plurality of laser beams to write an image

An image forming apparatus comprises an image signal converting means. The image converting means converts a first image signal into a second image signal. The first image signal includes an n-bit digital signal indicating a tone level of an image. The second image signal includes an m-bit digital signal indicating the tone level of the image. Here, m and n are integers and m is greater than n. A predetermined relationship between 2.sup.n values expressible by the n-bit digital signal and 2.sup.n related values among 2.sup.m values expressible by the m-bit digital signal is according to a first image forming characteristic in the image forming apparatus. The image forming apparatus further comprises an image forming means having a second image forming characteristic. The image forming means is coupled to the image signal converting means and forms the image based on the second image signal related to a combination of the first and second image forming characteristics.

Image forming apparatus and method

A device applicable to a laser beam printer, color printer, digital copier, facsimile machine or similar image recorder for controlling the output level of a scanning beam to a predetermined level. The device sets the output level of the scanning beam in response to data fed thereto from the outside, thereby coping with changes in image forming conditions and changes in various characteristics due to aging. The device incorporated in a color printer, for example, sets the output levels of individual laser beams in matching relation to the characteristics to individual colors.

Scanning beam output control device for an image recorder

A laser beam scanning position detecting device having a beam detecting element for detecting the passage of a laser beam, and determining a print start timing in response to an output signal of the beam detecting element. The print start timing is changed in response to a reference signal or externally derived data.

Laser beam scanning position detecting device having means for

An image data storing device for an image forming apparatus having a plurality of line buffers to which image data are written from external equipment and from which the written image data are read to form an image. Selectors selectively cause the individual buffers into a read state, write state, and inoperative state. An image forming signal generator generates an image forming signal during one frame of image forming period. During an image forming period, the selectors condition each of the line buffers for any one of the above-mentioned three different states while, during a non-image forming period, they hold the line buffers in the individual states. This allows the line buffers to start operating under the same conditions whenever an image forming period is reached.

Image data storing device for an image forming apparatus

An image forming apparatus has a control device for controlling an optical output of a semiconductor laser. An operation of controlling the optical output is started with a timing before an incoming signal which indicates an effective image region in a sub scanning direction of a photosensitive body and responsive to a timing signal (or power check start signal) having a predetermined period.

Image forming apparatus and method of controlling output of

An image forming apparatus includes a fixing speed setting unit for selectively setting the fixing speed in accordance with a desired mode of operation, a fixing unit for fixing a reproduced image of an original formed on a image forming medium at a variable fixing speed in accordance with the fixing speed setting unit, and a scanning unit provided with opto-electrical elements arranged in one line extended laterally to a predetermined scanning direction for optically receving an image of the original through the opto-electrical elements. The opto-electrical elements are carrying out a scanning operation in the predetermined scanning direction with varied scanning speed by changing a sweep spacing of an image data with averaging every N line of the image data in accordance with the operation mode with using every N-1 lines of the image data to reproduce the image of the original on the image forming medium.

Image reproducing apparatus

A multi-beam detecting apparatus adapted to an optical system in which a recording medium is scanned by a plurality of light beams emitted from respective light sources, includes a photodetector, a light interrupting member, and a control circuit. The photodetector produces detection signals when the corresponding light beams come to a predetermined position. The light interrupting member is interposed between the light sources and the light detecting member, and has transparent portions related to the respective light beams. A controlling circuit controls ON/OFF states of the light source in accordance with the respective detection signals related to the corresponding light beams passing through the respective transparent portions in the light interrupting member.

Light beam scanning apparatus

A printer structure relies on a laser modulator operating in response to image data cooperates with a rotary deflector for deflecting the modulated laser onto a recording medium with the rotation of the rotary deflector being controlled by a predetermined signal. A synchronizer receives the deflected laser irradiated from the rotary deflector in the vicinity of the recording medium and the synchronizer outputs a signal which defines a timing which the laser modulator uses to begin modulation. At least three memories are used which are each capable of storing the image data corresponding to one line defined by one deflection of the rotary deflector and a memory control device controls the writing of the image data inputted from an exterior of the printer in one memory means after switching the one memory to a write operation in synchronization with the rotary signal defining the one line. Subsequently, the image data which is written in the particular one memory is read after switching the one memory to a read operation and transferring the read image data to the laser modulator.

Printer

An electrophotographic copier, facsimile machine, laser printer or similar image forming apparatus for reproducing an image on a paper sheet by transforming an image signal representative of the image into an image forming signal by pulse width modulation, causing a spot beam in the form of a laser beam which is modulated by the image forming signal to scan a photoconductive element to form an electrostatic latent image thereon, developing the latent image to render it visible, and transferring the visible image to a paper sheet. The laser beam output, the set pulse widths of the image forming signal (beam turn-on times) and the bias voltage for development are changed in association with the deterioration of the laser beam power and the sensitivity of the photoconductive element.

Image forming apparatus

A semiconductor laser control apparatus for controlling an optical output of a semiconductor laser to a predetermined value comprises a switching part coupled in series with the semiconductor laser and controlled by an N-bit image signal, N constant current supply circuits coupled in parallel to each other and in series with the switching part for supplying currents to the switching part so that a driving current is supplied to the semiconductor laser from the switching part, a detector for detecting the optical output of the semiconductor laser and for outputting a detection signal indicative of the detected optical output, and a control part responsive to the detection signal from the detector for controlling the driving current by controlling the N constant current supply circuits so that the optical output of the semiconductor laser becomes the predetermined value.

Semiconductor laser control apparatus

An image forming apparatus which produces image data by reading an original document, modulates a light beam to be radiated from a light emitting element by the image data, and exposes an electrophotographic conductive element imagewise by the light beam modulated. The power of the modulated beam is varied dot by dot in association with tones. The apparatus renders multiple tones without lowering resolution.

A synchronizing device is used in a laser printer which comprises a polygonal mirror for periodically deflecting a laser beam which scans a scanning plane and a photodetector provided on the scanning plane outside a region in which a printing is made by the laser beam for outputting an output signal when the laser beam is detected. The output signal of the photodetector is used for producing an image scan clock signal which synchronizes each scan of the laser beam. The synchronizing device comprises a pulse generating circuit for generating a plurality of pulse signals having a frequency identical to that of the image scan clock signal and having phases which are successively shifted by a constant phase with respect to each other, a clock selecting circuit for selectively outputting one of the plurality of pulse signals generated by the pulse generating circuit as the image scan clock signal, and a setting circuit for arbitrarily setting the pulse signal to be selectively outputted from the clock selecting circuit responsive to the output signal of the photodetector.

Growing community of inventors

Tokyo, Japan

Kenichirou Asada