Hitachi Koki Co., Ltd.

Other

Hitachi, Ltd.

Shigenobu Katagiri

Hiroshige Nakano

Hiroomi Kozawa

Shinichi Nishino

Toshitaka Ogawa

Yasuo Kikuchi

Tsuneki Kobayashi

Minoru Seino

Kazuyuki Kubo

Hisayoshi Monma

Kazuo Matsuzaki

Susumu Saito

Akira Arimoto

Takeshi Mochizuki

Isao Nakajima

Takashi Suzuki

Hiroshi Ueno

Masayuki Ainoya

Tsukasa Onose

Koji Doi

Tomio Sugaya

Osamu Namikawa

Mitsugu Asano

Minoru Ohshima

Toshiaki Fujieda

Masami Ishikawa

Hirochika Okano

Mineo Ohyama

Motoya Toyoda

Koutaro Yamada

An optical scanner and method in which light beams from a plurality of sources are directed onto a medium to form a composite spot. The relative positions of the beams are detected and changed to change the diameter of the composite spot so that lines formed by such spots appear unbroken. The modulating times, intensities and number of sources of the beams can also be varied to provide a linear relation between the dither matrix and the picture element density.

Optical scanner and method for generating and detecting a composite dot

A laser printer with a thermal fixing unit comprises: a pair of heat and pressure rolls for pressing a sheet with a developed toner image therebetween to fix the toner image on the sheet; a web immersable with an oil; an oil coater for supplying the oil to the web and pressing the web against the heat roll at at least one point to make the web contact with the heat roll so that the oil is applied from the oil coater onto the surface of the heat roll through the web to thereby prevent occurrence of offset of the toner image; and at least one pressing member provided separately from the oil coater for locally urging the web against the heat roll, the pressing member being located on at least one of before and behind the oil coater.

Laser printer with thermal fixing of toner

In an electrophotographic printer, a photoconductive drum is scanned with a light spot provided by scanning light sources to electrostatically form a latent image with dot on it. The light sources comprise at least two LED print heads different in linear density are provided to print out data different in linear density on one and the same page.

Electrophotographic printer

An electrophotographic device has a photosensitive element, an electrifier that forms a uniform electrostatic potential on the photosensitive element, and a light source for irradiating the photosensitive element to obtain an electrostatic latent image that has a reduced potential. A bias potential is applied to the photosensitive element after the latent image is formed, but before it is developed, so that the reduced potential of the latent image can be maintained at a constant level. With constant potentials existing on the photosensitive element, a printed image of high quality is obtained.

Electrophotographic device with controlled exposed potential

Systems for discriminating among a plurality of type carriers differing in number of characters and pitch of characters are disclosed. In one circuit, the type carrier is provided with synchronizing marks and discrimination marks in addition to the usual type character marks. The synchronizing mark is located at the beginning of a set of characters, and the discrimination mark is located a predetermined distance from the synchronizing mark according to the number of characters and pitch of the particular type carrier. This distance is determined by counting type character marks. In another circuit, one or more discrimination marks are provided between type character marks at the beginning of a set of characters. The number of discrimination marks indicates the number of characters of the particular type carrier. In either circuit, a counter of only a few stages and a simple decoding circuit are all that are required to carry out the discrimination operation.

System of discriminating the kinds of type carriers

A cleaning apparatus for a copier includes a photoconductor-cleaning rotating fur brush disposed within a housing. In order to prevent toner buildup and resultant flaking within the housing, the brush and housing are relatively movable so that the brush can periodically clean the housing.

Cleaning apparatus for xerographic printing apparatus

System for discriminating among different kinds of type carriers

A driving motor of the type employing pneumatic bearings is improved by reducing a weight moment of an upper pad by cutting away a portion thereof, to make the gaps of the bearing pads of the motor more nearly uniform.

Rotary multi-mirror driving motor

In an impact printer or the like having a plurality of print-hammer drive electromagnets which are respectively connected in series with switching transistors between the terminals of a voltage source, the switching transistors are normally gated into conduction by gating signals with a duration sufficient to energize the electromagnets for operating the associated print hammers. In a test mode which occurs prior to the operation of the printer, the gating signals are successively applied to the switching transistors and the duration of each gating signal is reduced so that the gated transistor remains conductive for a short interval which is insufficient to operate the hammer. The potential at a circuit junction between the respective transistor and the associated electromagnet is coupled through a voltage divider to an input of a coincidence gate which receives its another signal from the gate electrode of the associated transistor to generate a failure indication signal when the input logic states have a predetermined relation therebetween.

Failure detection circuit for impact printers or the like

A microcomputer which controls a device or apparatus in accordance with a control program prestored in a Read Only Memory included in the microcomputer, further comprises a Random Access Memory for storing parity bits of the control program. The data indicative of the control program prestored in the Read Only Memory are read out in sequence and are fed to a central processing unit of the microcomputer so that parity bits of the prestored data are produced and then stored in the Random Access Memory. The parity bits stored in the Random Access Memory are used to check whether the prestored data are correct or not.

Microcomputer having a ram for storing parity bits

A failure detection circuit for stepping motors having a rotor and a motor control circuit including first and second transistors respectively connected in series with first and second stator coils. The rotor is set in motion in response to energization of the second stator coil when the second transistor is activated and brought to a halt in response to energization of the first stator coil when the first transistor is activated. During the interval when the first transistor is activated, the potential at a circuit junction between the respective transistor and the associated coil is detected and compared with the logic level of the input to the associated transistor to check for a set of operational states of the circuit elements to give a warning indication if the compared levels have a predetermined relationship to each other. During the interval when the rotor is at standstill, the second transistor is activated in a brief interval so that the amount of current generated in the second stator coil is insufficient to generate a torque to the rotor and in this brief interval the above comparison is made to check for another set of operational states of the circuit elements to give a warning indication if the compared levels have a predetermined relationship therebetween.

Failure detection method and circuit for stepping motors

A magnetic interference prevention system in a printer comprising a plurality of print hammers whose hammering surfaces are disposed in a straight line and a plurality of printing magnets arranged adjacent one another to drive each of the print hammers respectively. In this system when a signal to drive a first printing magnet for a column is provided the driving of at least one of two printing magnets adjacent to the first printing magnet is inhibited for a predetermined period of time. This will prevent three adjacent printing magnets from being driven substantially at the same time.

Printer magnetic interference prevention system

A printing device having a plurality of print hammers having striking surfaces arranged along a print line and print magnets provided adjacent to one another for driving the printing hammers. A magnetic interference preventing device comprises a memory for storing for each column the excitation lapse time information of the print magnets. A reader which, when exciting each print magnet is started, reads the excitation lapse time information of both print magnets adjacent to each print magnet out of the memory. The reader outputs a signal only when the excitation lapse times of both print magnets are in a predetermined range of time. An inhibitor is used for inhibiting the excitation of each print magnet when the excitation lapse times of both print magnets are within the predetermined range of time.

Magnetic interference prevention system

An improved printing magnet drive device for use in a printing apparatus, such as line printer, is disclosed. The improvement comprises a constant voltage control means in which an output terminal voltage of a transistor is compared with a reference voltage and the comparison result is fed back to the transistor so as to control the output terminal voltage of the transistor to a predetermined value, whereby the voltage applied to the printing magnets is substantially maintained unchanged.

Printing magnet drive device

A device for limiting the number of printing columns in a printer in which a group of printing data codes transferred from a data source are successively compared with a group of type codes which are determined in correspondence to the instantaneous positions of type on a type carrier, so that a type in a place where a printing data code coincides with a type code is printed. The device comprises a reversible counter adapted to subject a coincidence signal relating to said printing data code and type code and a printing completion signal for each place to addition and subtraction, respectively, so that when the count value of the reversible counter reaches a predetermined value, printing for further places is inhibited.

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Katsuta, Japan

Shigenobu Katagiri