Kabushiki Kaisha Toshiba

Toshiba Tec Kabushiki Kaisha

Fumito Ide

Yasuo Abuyama

Takeshi Sanbayashi

Osamu Hamanaka

Shinichi Hashimoto

Reiji Murakami

Toshiyuki Sogo

Noriyuki Nomura

Hiroshi Matsumoto

Akiro Iimori

Mamoru Shimono

Kouzou Matsuyama

Yoshimi Miura

Shoji Takano

Hidenori Mochizuki

Mamoru Shimino

Tetsushu Kuwahara

A developing device incorporated into a copying machine of the present invention has a developer/toner supplying section in which a developing tank and a toner cartridge are independently and detachably formed. A toner density sensor for controlling toner density of developer is provided in the developing device. The toner density sensor is used to detect a developer drawing defect and maintain a predetermined value of toner density during the copying operation when developer is supplied from the developer/toner supply section.

Image forming apparatus

An image forming apparatus of the present invention has an image forming device including an image scanning device and an automatic document feeder. A document on a platen located on the image forming device is positioned in a predetermined position. The scanning device starts the scanning operation from a starting position opposite to the predetermined position. The scanning position of the scanning device is individually determined to be a position corresponding to the document size detected by the detecting device. Therefore, the image forming operation is performed without failing to form the image on the copying paper. Furthermore, the speed of the image forming operation is increased.

Image forming apparatus with an image scanning apparatus and an

An image forming apparatus is provided with a developing device for developing a latent image formed on the surface of the photosensitive drum. The developing device includes a first developing unit for developing the latent image by use of a first color developing agent and a second developing unit for developing the latent image by use of a second color developing agent. The first and second developing units are selectively driven and devices for inserting/removing the first and second development units are also provided. The image forming apparatus has a selecting device for interrupting an image forming process which is in progress to automatically select an image forming process which uses the second developing unit.

Image forming apparatus with removable developing means

A light amount control apparatus contains an exposure lamp, a photo sensor for receiving light from the lamp, an AC power source for applying an AC voltage to the lamp, a CPU for computing an electric power to be supplied to the exposure lamp in accordance with magnifications and optical densities of originals by using the data signal outputted from the photo sensor, a lamp regulator for control an electric power supplied to the exposure lamp by using a value computed by the CPU, and a zero-cross generator for causing the CPU to periodically perform the computation in synchronism with the AC voltage of AC power source applied to the lamp.

Light amount control apparatus

An image forming apparatus is provided with a developing device for developing a latent image formed on the surface of a photosensitive drum. The developing device includes a first developing unit for developing the latent image by use of a first colon developing agent and a second developing unit for developing the latent image by use of a second colon developing agent. The first and second developing units are selectively driven and devices for inserting/removing the first and second development units are also provided. The inserting/removing device includes a handle on the developing unit having first and second hooks which are rotated by the handle to engage pins on the housing of the image-forming apparatus to lock the developing unit in operative relationship with the photosensitive drum.

Image forming apparatus with easily removable developing units

An image-forming apparatus is provided with a photosensitive drum rotatably located in a housing, and a developing device for developing the latent image formed on the surface of the photosensitive drum. A first developing unit of the developing device develops the latent image by a color developing agent. A second developing unit develops the latent image by a second black developing agent. The first and second developing units are alternatively driven by a switch provided on a control panel which is located on the housing. The first developing unit is in the form of a cartridge which can be removably set in the housing. A pair of positioning members are attached to the front and rear walls of the developing agent supply section of the first developing unit. Both end support portions of the handle are swingably mounted on the positioning members by supporting shafts, individually. Each support portion of the handle is fitted with a hook which can rock around its corresponding supporting shaft. The hook engages its corresponding retaining pin on the housing, thereby restraining the handle from moving upward. An engaging recess (a first positioning portion) and an end face (a second positioning portion), both formed on the bottom side of each positioning member, are adapted to engage and abut against positioning pins on the housing, respectively. Thus, the first developing unit is held in a prescribed position.

Removable developing unit for an electrostatic copier and locking device

An image-forming apparatus is provided with a photosensitive drum rotatably located in a housing, and a developing device for developing the latent image formed on the surface of the photosensitive drum. A first developing unit of the developing device develops the latent image by a first red developing agent. A second developing unit develops the latent image by a second black developing agent. The first and second developing units, each of which includes a developing roller and a magnet roll, are alternatively driven by a switch provided on a control panel which is located on the housing. The respective magnet rolls of the first and second developing units are allowed to rock through about 25 degrees each. As the magnet rolls rock within this range, magnetic brushes of the developing agents can be formed on the surfaces of the developing rollers, respectively, or removed therefrom. When the magnet rolls of the first and second developing units are shifted to the prescribed positions by a magnet roll drive mechanism, the magnetic brushes are formed on the surface of only one of the developing rollers of the first and second developing units.

An image forming apparatus is provided which includes a document set section, a document size detecting device, a medium set section, a device for picking up the size of the medium, a medium feed device, and an image forming device for forming an image of a document in the document set section on the medium of an image forming location. The apparatus further includes an auto magnification designating device for generating data to designate an image forming magnification according to data representative of the size of the medium picked up by the pick up device by using the document size as detected by the document size detecting device. Further, a manual magnification designating device is providing for manually designating a desired magnification for image forming. A first priority means for operating the auto magnification designating device to define a first default mode of operation of the apparatus and a second priority means for operating the manual magnification designating means for defining a second default mode of operation of the image forming device are also provided. Finally, a priority select device is provided for reversibly selecting between the first and second priority means so as to select a default mode of operation of the apparatus.

Image forming apparatus enabling reversible selection of a default mode

An image-forming apparatus is provided with a photosensitive drum rotatably located in a housing, and a developing device for developing the latent image formed on the surface of the photosensitive drum. A first developing unit of the developing device develops the latent image by a first red developing agent. A second developing unit develops the latent image by a second black developing agent. The first and second developing units are alernatively driven by a switch provided on a control panel which is located on the housing. A copy mode for black is automatically established when the power is turned on or if no operation is performed for a prescribed time after a foregoing copying operation, in a mode for any other color than black, is ended.

A sheet supplying apparatus supplies sheets one by one from a paper cassette to a transfer portion defined between a photosensitive body and a transfer charger in a housing. The sheet is picked up by rotation of a pair of feed rollers. The picked-up sheet is aligned by register rollers. The feed rollers are driven in synchronism with the operation of the register rollers.

Sheet supplying apparatus

A document feeder for use with an image forming device such as a copy machine. An original document is first transported from an original document feed port toward an original exit port until a trailing end of the original passes a predetermined stop position whereat an imaging operation is to be carried out. By transporting until the trailing end passes the stop position, there is time for a previous original to exit from the original exit port. Then the original document is fed back toward the original feed port until the trailing end of the original is properly positioned so that the document can be imaged.

Document feeders used with image forming apparatus

A sheet supplying apparatus supplies sheets one by one from a paper cassette to a sheet feed portion defined between a photosensitive body and a transfer charger in a housing. The sheet is picked up by rotation of a pair of feed rollers. The picked-up sheet is aligned by register rollers. The feed rollers are then driven in synchronism with the operation of the register rollers.

An image forming apparatus for a photocopy machine. A document table holds the document to be copied. An image area designating panel on the document table designates the area of the document to be copied and generates electrical signals corresponding to the copy area when the panel is pressed. A memory stores the electrical signals generated by the panel and a plurality of light-emitting elements prevents the formation of the electrostatic latent image on the photosensitive body except for the indicated copy area, according to the electrical signals which are read from the memory.

An image forming apparatus reciprocally operates one of the image forming body units and the document feeding units. A first control circuit produces signals necessary for image formation operation, while keeping an automatic document feeder in a wait state. A second control circuit operates the automatic document feeder only when the image formation operation is not in progress. Therefore, the power source which is provided can be shared between the image forming body unit and the automatic document feeder without the necessity for excess capacity.

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Zama, Japan

Fumito Ide