Ricoh Company, Ltd.

Susumu Tatsumi

Seiichi Miyakawa

Chikara Imai

Koji Sakamoto

Tadahiro Eda

Akira Midorikawa

Sakae Ota

Takashi Yano

Masumi Ikesue

Akira Suzuki

Nobuo Kasahara

Mitsuru Hashimoto

Tsuneo Kurotori

Kenji Kojima

Tatsuo Tani

Manabu Mochizuki

Hideo Watanabe

Keishi Kubo

Kenzo Ariyama

Yasushi Koichi

Toshiyuki Kawanishi

Masao Hosaka

Mitsuo Tanaka

Toyoo Okamoto

Isao Nakamura

Hiroyuki Idenawa

Nobuo Mochizuki

Yoshihiro Ogata

Ichiro Fukushima

Shoji Kuroishi

Toshio Hayashi

Tatsuo Tani Formerly Nishikawa

Tatsuo Tani, Formerly Nishikawa

Youtarou Kakitani

A thermosensitive image transfer recording medium comprising a support material and a thermofusible ink layer formed thereon, which thermofusible ink layer comprises a dye component, a binder agent and a pigment having a needle-like crystal form, which is dispersed in a network form throughout the thermofusible ink layer.

Thermosensitive image transfer recording medium

A developing unit for use with an electrophotographic copying apparatus of the type comprising a developing electrode and at least one corona discharger includes a conductive member arranged within a shield casing of the discharger for obtaining a voltage to be applied to the developing electrode as a bias voltage thereto. In the case where an a.c. discharger for charge elimination is being used in addition to the primary discharger, conductive members are incorporated with respective dischargers and the outputs from the conductive members are superimposed on each other and applied to the developing electrode. In this instance, the output of the conductive member associated with the a.c. discharger is continuously applied to the developing electrode after the de-energization of the primary discharger, i.e., the completion of developing an electrostatic latent image to thereby prevent the deposition of toner on the developing electrode.

Developing unit for electrophotography

A process for treating exhaust gas from an electrophotographic machine which comprises oxidizing, in the presence of a heated oxidation catalyst, an odorous exhaust gas generated in course of the steps of developing an element being developed by means of a developer, transferring the thus developed image onto a transfer sheet and/or heating a copy material consisting of said element being developed or said transfer sheet thereby to make said exhaust gas odorless, and an apparatus therefor.

Process for treating exhaust gas from electrophotographic machine and

An electrode (12) for sensing a surface potential is connected to a non-inverting input of an operational amplifier (14). The output of the operational amplifier (14) is connected to the inverting input thereof in a voltage follower configuration. The output of the operational amplifier (14) is also connected to one or more shield electrodes (19) which are operatively disposed adjacent to the sensing electrode (12). An offset bias voltage of the operational amplifier (14) is adjusted to cancel an input bias current thereof. An operational amplifier (33) may be mounted on a flat substrate (112), with sensing and shield electrodes (113), (114), (116) formed on the substrate (112) by printing. The shield electrodes (114), (116) surround the sensing electrode (113) and also the operational amplifier (33).

Electrometer apparatus

A detecting electrode (22) is formed on a substrate (28), an amount of potential from a charged surface (23) induced in the detecting electrode (22) corresponding to a potential on the surface (23). A guard electrode (26) formed on the same surface of the substrate (28) as the detecting electrode (22) surrounds the detecting electrode (22). Part of the guard electrode (26b) is formed on the back surface of the substrate (28). The detecting electrode (22) is connected to a non-inverting input of an operational amplifier (24). The output of the operational amplifier (24) is connected to the inverting input thereof and also to the guard electrode (26) to produce unity gain and place the guard electrode (26) at the same potential as the detecting electrode (22). The substrate (28) is formed of a material such that the electrical resistance between the detecting electrode (22) and the guard electrode (26) is at least 10.sup.9 ohms to reduce zero drift to a negligible value.

Electrometer probe

An exposure unit radiates a light image of an original document onto a charged photoconductive member to form an electrostatic image through localized photoconduction. A developing unit applies a powdered developing substance comprising carrier particles and toner particles to the photoconductive member to develop the electrostatic image and produce a toner image which is transferred and fixed to a copy sheet to produce a permanent reproduction of the original document. Prior to exposure with the light image a reference electrostatic image is formed on the photoconductive member and the electrostatic potential thereof is measured. The intensity of the light image of the original document and/or a developing bias voltage are regulated in accordance with the sensed electrostatic potential. The reference image may be of a reference surface having a predetermined optical density or a portion of the original document produced by reverse optical scanning.

Exposure control and other component control for electrostatic copying

A photoconductive drum (32) is charged, radiated with a light image of an original document (34) and developed to produce a toner image. The density of the toner image is sensed and additional toner fed to a developing unit (37) if the sensed density is below a predetermined value. The sensed toner density is compensated for variations in charge potential, light image intensity, electrostatic image potential, developing bias voltage, power supply voltage and/or sensor output so as to be independent of these variables.

Electrostatographic copying apparatus with automatic toner density

In an electrophotographic copying machine, the copy image adjustment method for correcting copy image characteristics comprises the steps of measuring copying characteristics by use of a reference original and resetting development characteristics in accordance with the measurement results.

Copy image adjustment method

The vertical and horizontal lengths of an original document (28) are automatically sensed and compared with the vertical and horizontal lengths of a copy sheet (38) and the reduction ratio of a variable magnification optical system (33) is automatically adjusted in accordance therewith so that the maximum length of the image of the document (28) is equal to the corresponding vertical or horizontal length of the copy sheet (38). The image may be selectively parallel to the vertical length or the horizontal length of the copy sheet (38) regardless of whether the image is parallel to the vertical or horizontal length of the document (28). In one form (21) of the invention the document (28) is placed on a platen (27) so that the image is parallel to the vertical length of the platen (27) regardless of whether the image is parallel to the vertical or horizontal length of the document (28). In another form (71) of the invention, the document (28) is placed on the platen (74) so that the vertical length of the document (28) is parallel to the vertical length of the platen (74) regardless of whether the image is parallel to the vertical or horizontal length of the document (28). In the latter form (71) a lever (76) or the like is manually changed over to indicate whether the image is parallel to the vertical or horizontal length of the document (28) and the optical axis of the light image is rotated to one of two positions angularly spaced 90.degree. from each other in accordance with the position of the lever (76).

Variable magnification electrostatic copying machine

An electrode (17) is provided adjacent to a photoconductive drum (12) to sense the background area potential at a leading edge of an electrostatic image on the drum (12). An electrically conductive shield (26) surrounds all surfaces of the electrode (17) except a surface which faces the drum (12). A voltage follower (18) has an input connected to the electrode (17) and an output connected to the shield (26). This makes the capacitance between the electrode (17) and the drum (12) much greater than the capacitance between the electrode (17) and ground. The surface of the electrode (17) facing the drum (12) is formed with a pattern of projections and depressions to increase the surface area thereof and thereby the capacitance between the electrode (17) and the drum (12). The output of the voltage follower (18) is connected through a sample and hold circuit (53), (54), (56), (57), (62) to a developing bias voltage generator (58), (69), (71) which applies a bias voltage to a developing unit (23) in accordance with the output of the voltage follower (18) and thereby the potential of the electrostatic image on the drum (12).

Electrostatographic apparatus comprising developing bias means

An image of an original document (16) is sensed to determine if the document (16) is a printed document (the image consists of characters and symbols) or a photographic document. The exposure illumination intensity, developing bias voltage and/or other variable operating parameters are controlled in accordance with the determination.

Electrostatographic apparatus comprising automatic document type

An exposure unit radiates a light image of an original document onto a charged photoconductive member to form an electrostatic image through localized photoconduction. A developing unit applies a powdered developing substance comprising carrier particles and toner particles to the photoconductive member to develop the electrostatic image and produce a toner image which is transferred and fixed to a copy sheet to produce a permanent reproduction of the original document. The tone density, or the ratio of toner particles to carrier particles in the developing substance is electromagnetically measured, and the developing ability of the developing substance is opticaly measured. The developing substance is replaced when the difference between the toner density and developing ability exceeds a predetermined value. Prior to exposure with the light image a reference electrostatic image is formed on the photoconductive member and the electrostatic potential thereof is measured. The intensity of the light image of the original document and/or a developing bias voltage are regulated in accordance with the sensed electrostatic potential. The reference image may be of a reference surface having a predetermined optical density or a portion of the original document produced by reverse optical scanning.

Electrostatic copying machine

A method of maintaining the correct conditions of an electrophotographically duplicated image, which uses a reference plate having at least a dark-tone area and a light-tone area and in which signals associated with the reference plate are detected and synthesized to control the duplicating process conditions such as developing bias potential, charge, exposure and of the optical system so that an optimum image may be produced.

Method of maintaining the correct conditions of an

A photoconductive drum (12) is electrostatically charged and radiated with a light image of an original document (16) to form an electrostatic image. The average value of the electrostatic potential of the electrostatic image is sensed and a developing bias voltage controlled in accordance therewith. The bias voltage is progressively increased when the sensed electrostatic potential is below a predetermined value and is reduced to a lower value when the electrostatic potential exceeds the predetermined value. The electrostatic potential is below the predetermined value for original documents constituted by printed pages and above the predetermined value for original documents constituted by photographs and other continuous tone documents.

Electrostatographic apparatus comprising improved developing bias control

A powdered toner mixture comprising a non-magnetic toner component and a ferromagnetic carrier component is caused to flow downwardly through a vertical conduit by gravity. An electromagnetic coil is wound around the conduit and energized with an alternating electric signal. An electrically conductive and magnetic mass is disposed inside the conduit. The permeability of the toner mixture decreases as the toner density, or the ratio of the toner component to the carrier component, increases. The lower the permeability of the toner mixture, the greater the proportion of magnetic flux passing through the mass. The flux passing through the mass induces eddy currents therein which, in combination with hysterisis and skin effect losses, dissipate a portion of the electric signal. The amount of power dissipation is a function of the relative proportion of flux through the mass and thereby the toner density and, when measured, provides a measure of the toner density.

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Tokyo, Japan

Susumu Tatsumi