Canon Kabushiki Kaisha

Oki Electric Industry Co., Ltd.

Konica-minolta Holdings, Inc.

Yukihiro Ozeki

Katsuhiro Sakaizawa

Kazumi Furuta

Manami Sekiguchi

Makoto Nonomura

Kazuo Tanaka

Osamu Iwasaki

Takeshi Yamamoto

Hideyuki Yano

Koujirou Sekine

Junji Araya

Mitsuru Yokoyama

Tadashi Furuya

Hiroaki Ueda

Manami Kuiseko

Kenya Ogawa

Mikiya Suzuki

Kozo Fujii

Hideaki Satoh

Kiyoshi Nagai

Shigeru Shikii

Makiko Imae

Koji Horii

Shusei Aoki

Harumi Kugo

Naoki Mitsugi

A diffractive optical element has a diffraction grating which multiplexes light beams of different wavelengths, and the diffraction grating has a binary structure in which the diffraction surface top part and the diffraction surface bottom part repeat a concave and convex shape through a rising surface part along an optical axis direction P. The diffraction surface top part and the diffraction surface bottom part are inclined to the rising surface part. By this diffractive optical element, the diffraction angle of the light beam is maintained, and the diffraction efficiency of the light beam can be improved. By using this diffractive optical element in an optical communication module, while the separation angle of the light beam of the different wavelength is maintained, the signal receiving performance is increased.

Diffractive optical element and bidirectional optical communication module using the same

The present invention is provided to obtain an inexpensive bidirectional optical module wherein a diffraction efficiency can be maximized at different diffraction order for light beam with different wavelength, and light usage efficiency is enhanced. The bidirectional optical module includes a light-emitting element for transmitting an optical signal toward an end of an optical fiber; a light-receiving element for receiving an optical signal from the end of the optical fiber; and a grating in which stair shapes are repeated with a predefined pitch. In the bidirectional optical module, a phase function is defined as phase-difference contour lines which is formed by making two light fluxes from predetermined positions interfere with each other on a surface arranged at a position of the grating. A planar pitch of the grating is formed such that values of the phase function form phase contour lines each representing an integer multiple of 360 degrees.

Bi-directional optical module

An echelon type diffraction structureis formed on the flat optical surface of a lens, thereby ensuring easy designing and easy production of a diffraction structure as a microstructure. Further, the light of wavelength &#x3bb;is applied to the diffraction structurein a tilted position with respect to the optical axis of the lensso that the first order diffracted light produced by the diffraction structuretravels along or parallel to the optical axis of the lens, with the result that improved light transmittance can be maintained. Further, a lensis arranged between a light emitting deviceand lens. Thus, the flat optical surface of the lensis arranged on the side of the end faceof an optical fiber, thereby reducing the deterioration in aberration more effectively.

Optical communication module

An optical bidirectional modulehaving therein light emitting elementwhich transmits optical signal to the end facet of the optical fiber, light receiving elementwhich receives optical signal from the end facet of the optical fiber and stair-shaped multi-level grating, wherein the stair-shaped multi-level grating separates the first light path between the end facet of optical fiber and the light emitting element and the second light path between the end facet of optical fiber and the light receiving element by a different wavelength of each optical signal, when the module mixes and separates optical signal with different wavelengths traveling in opposite directions related to the end facet of the optical fiberused for bidirectional optical fiber communication by means of a wavelength multiplex system.

Optical bidirectional module

An optical multiplex communication system includes a multiplexer and a demultiplexer. In the multiplexer, one of two modulated optical pulse train signals is attenuated by an optical attenuator so that amplitudes of the two signals differ from each other. Then, the two signals are time-division multiplexed to produce a multiplexed optical pulse train signal. In the demultiplexer, a VD detector indirectly derives the amplitude of the extracted optical pulse train signal and outputs it to a comparator. A VR detector derives the mean amplitude of the multiplexed optical pulse train signal and outputs it to the comparator. Based on the inputted amplitudes, the comparator identifies the extracted optical pulse train signal. A controller and a mixer control the signal extraction timing such that the extracted optical pulse train signal as identified by the comparator agrees with selection designated by an externally inputted select signal.

Multiplexer, demultiplexer and multiplex communication system

A semiconductor optical modulator having an electroabsorptive layer and a pair of modulating voltage electrodes also has a direct-current voltage electrode, from which an unmodulated electric field can be applied to the electroabsorptive layer to adjust the output optical power level. The output optical power level can thus be adjusted without the need for an external attenuator, and without shifting the modulating voltage away from the part of the extinction ratio characteristic having the best linearity. An optical multiplexing module using semiconductor optical modulators of this type can generate a multiplexed output signal with a uniform optical power level simply by controlling the direct-current voltages applied to the semiconductor optical modulators.

Semiconductor optical modulator, optical multiplexing module, and control method thereof

A developing roller for electrophotography is disclosed which is composed of a conductive mandrel, a charge-providing layer having a charge-providing performance to a non-magnetic one-component toner, formed at the surface of the roller, a base layer having an elasticity, formed at a position nearer to the mandrel of the roller than the charge-providing layer and an elastic intermediate layer formed at a position between the base layer and the charge-providing layer. The elastic intermediate layer is formed of a composition having a contact angle to water which is smaller than that of a composition for forming the base layer. Also, disclosed are a developing apparatus, an apparatus unit and an image forming apparatus using the developing roller.

Developing roller for electrophotography, developing apparatus, apparatus unit and image forming apparatus

The WDM light source comprises a light source which generates an optical signal for an optical channel. The optical signal is intensity modulated with modulating signals. The modulated optical signal is applied to a dispersion generating circuit, at which dispersion occurs on the optical signal, according to the wavelength of the signal. A phase difference detector detects phase difference between the optical signal input to the dispersion generating circuit and the optical signal output from the dispersion generating circuit. According to the detected phase difference, the control signal which corresponds to delay time is generated. The control signal is fed back to the light source thus the wavelength of the light source is controlled.

Apparatus for stabilizing light source frequency

Image forming apparatus featuring a conductive developing roller including a mandrel, an elastic layer, an intermediate layer, and a charge-providing layer formed thereon

An EDFA is comprised of a pre-amp and a post-amp which are connected in series, a photocoupler a long wave pass filter (LWPF) and an LWPF controller The photocoupler is connected to an input-stage of the EDFA and enters the light signal in the LWPF controller The LWPF is located between the pre-amp and the post-amp and its cutoff wavelength is adjustable. A short-wavelength-part of the light signal which is amplified by the pre-amp is cut off by the LWPF The LWPF controller detects an input signal power of the input light signal and adjusts the cutoff wavelength of the LWPF based on the detected input signal power. Gain of light signals which are output from the post-amp are equalized ranging the extensive input signal power and covering wide signal-wavelength bands.

Optical fiber amplifier

An image forming apparatus includes an image bearing member for bearing an electrostatic latent image, and a developing device for developing the electrostatic latent image with a developer and collecting the developer remaining on the image bearing member including a developer carrying member for carrying the developer. The developer carried by the developer carrying member comes into contact with the image bearing member as the developer carrying member moves and a regulating member for regulating a layer thickness of the developer carried by the developer carrying member. The regulating member regulates the layer thickness of the developer carried by the developer carrying member so that there will be three to eight layers, wherein V2/V1>1.54 holds where V1 is a peripheral velocity of said image bearing member and V2 is a peripheral velocity of said developer carrying member.

Image forming apparatus featuring a regulating member for regulating a number of layers of a developer carried by a developer carrying member

It is proposed to provide a developing agent carrier, developing unit, and image forming apparatus which can stably obtain a high-quality image. There is provided a developing agent carrier comprising an elastic portion which comes into contact with an image carrier, wherein an Asker C hardness of the elastic portion is not less than 20 and not more than 40, and a dynamic friction coefficient of a surface of the elastic portion is not less than 0.01 and not more than 0.2.

Developing agent carrier, developing unit, and image forming apparatus

A developing apparatus has a developer carrying member for carrying a developer thereon and conveying it to a developing area opposed to an image bearing member, an agitating member for agitating the developer to be supplied to the developer carrying member and a stripping device for stripping off the developer having passed the developing area from the developer carrying member wherein the developer stripped off from the developer carrying member by the stripping device is guided to a position farther from the developer carrying member than a position at which the agitating member is disposed.

Developing apparatus featuring first and second developer chambers and guide member for directing stripped-off developer

An optical delay time adjuster and an optical time-division multiplexer. The delay time adjuster includes a support, an optical fiber attached to the support, and a device attached to the support which adjustably changes the length of the optical fiber. In various embodiments the device is an electric heater or cooling device or provides current to a piezoelectric element serving as the support. The optical time-division multiplexer includes an optical coupler which multiplexes optical signals received at its input ports, and the optical delay time adjuster connected to one of the input ports of the coupler.

Optical delay time adjuster and optical time-division multiplexer

An LN (Lithium Niobate) modulator outputs light Po modulated using a modulation voltage Vm. An inputted light signal average level monitor is arranged at the input of the LN modulator. Further, an outputted light signal average level monitor is arranged at the output of the LN modulator. A negative feedback circuit controls the feeding back of a bias voltage applied to the modulator from the average level of the input signal and the average level of the output signal. Further, a bias voltage limiter performs control in such a manner that the center of the voltage limiting range for the bias voltage becomes the optimum operating point. This bias voltage limiter has: a voltage limiter for limiting the operating output range of an op-amp to be a prescribed voltage range; an integrator for applying an offset voltage to and shifting the limiting voltage of the voltage limiter; and a difference monitor for monitoring the difference between a modulation voltage Vm and an offset voltage .increment.V. The integrator generates an offset voltage based on shift information monitored by the difference monitor, with this offset voltage being provided to the voltage limiter. The voltage limiter then shifts the voltage control range in response to the provided offset voltage.

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Fujisawa, Japan

Yukihiro Ozeki