Hitachi, Ltd.

Hitachi Koki Co., Ltd.

Syoji Sagae

Yasumasa Matsuda

Masatoshi Kasahara

Hiroyuki Tadokoro

Satoshi Shimada

Takahiro Yamada

Kazuhiro Wakamatsu

Kanji Kawakami

Isamu Terashima

Motohisa Nishihara

Hiroyasu Uchida

Akira Shimada

Masayoshi Suzuki

Tetsuo Doi

Kyoji Mukumoto

Taisaku Kohzuma

Each of color toner images is formed on a photo-sensitive drum using a plural development units. An exposure process and a development process for a color image information are carried out repeatedly corresponding to a respective hue of the image information. The toner images of n colors are transferred to the drum by contacting a recording paper to the drum. A record mode is selected in accordance with a length in a peripheral direction of the drum of the image information against a peripheral length of the drum. When the length of the image information is longer than the peripheral length of the drum, N times transfer processes are selected as the record mode. Then the length of the image information is divided into N areas. The image information of n colors existing in every divided area is formed dividedly on the drum. The color image is recorded on a full length of the paper. Besides, when the length of the image information is shorter than the peripheral length of the drum, one time transfer process is selected as the record mode.

Color image electrophotographic apparatus for printing long-size copy

A roller forms a curve in a sheet of recording paper to which a toner image, formed on the curved surface of a photosensitive drum, is transferred such that a transfer curve extends along the curved surface of a transfer drum. The roller is provided in a path for carrying the recording paper so as to be in contact with the transfer drum.

Image transfer apparatus

An ink jet printing apparatus comprises a nozzle head including, orifices for ejecting ink particles, pressure chambers each having a piezoelectric element for applying a pressure wave to ink in the chamber and each communicating with corresponding one of the orifices and an ink chamber communicating with the pressure chambers, and electrical signal applying device for applying an electrical signal to selected one or ones of the piezoelectric elements to produce the pressure waves. The electrical signal applying device applies a main electrical signal pulse to the selected one or ones of the piezoelectric elements for inducing rises of the pressure waves and applies a sub-electrical signal pulse for suppressing the pulsations of the pressure waves a predetermined time interval after the main electrical signal.

Ink jet printing apparatus

A liquid droplet projection apparatus is disclosed which comprises a nozzle arranged at a liquid droplet ejection head, a liquid droplet supply tank, and an electro-mechanical transducer section interposed on the head between the nozzle and the tank. The volume of the electro-mechanical converter means changes in volume in response to an electrical signal pulse applied thereto to cause the nozzle to eject liquid droplets in accordance with the electrical signal. When the pattern of the electrical signal applied to the electromechanical transducer section has an interruption period longer than a predetermined width and three or more successive electrical signals following the interruption period, the amplitude and/or width of the second one of the successive electrical signals is enlarged as compared with the amplitude and/or width of the other electrical signals, thus preventing the diameter of the second liquid droplet ejected following the interruption from being reduced.

Liquid droplet projection apparatus

An ink jet printing apparatus in which, among two types of ink droplets of small and large sizes ejected from a nozzle, only the ink droplets of small size are electrically charged in accordance with an information signal, deflected and directed toward a recording medium to produce thereon a desired image. The state in which the ink droplets are produced is detected by detecting means disposed in the vicinity of a flight path of the ink droplets. On the basis of the output signal produced from the detecting means, intensity of excitation imparted to the nozzle is set at a level at which the ink droplets of small size are stably produced. Further, the intensity of excitation imparted to the nozzle is corrected on the basis of the output signal available from the detecting means through phase matching means for causing generation of the small size ink droplet to coincide with phase of the information signal.

A drop jet apparatus has a nozzle head which defines a pressure chamber, a nozzle, and passages. Part of the pressure chamber is defined by a thin diaphragm which is made thick at the central and at a surrounding portion spaced from the central portion. A piezoelectric plate is adhered to the thick portions so as to bridge the thin portion between the projections.

Drop jet apparatus

An ink-jet printing apparatus having a plurality of nozzles for projecting ink droplets which are selectively deposited on a printing medium in accordance with an information signal so as to form a printed pattern, such ink-jet printing apparatus comprising means for causing ink droplets used for printing to project from each nozzle in accordance with an information signal, a common power source for supplying a desired voltage to the ink-drop forming means provided at each nozzle thereby operating them, and switching means connected between the ink-drop forming means and the common power source and controlled by the information signal, the output of the power source being selectively supplied through the switching means to the ink-drop forming means, so that the driving system for driving the ink-drop forming means and the control system therefor can be separately provided, thus enabling a number of nozzles to be effectively controlled by a lowest control voltage.

Ink-jet printing apparatus

A multi-nozzle ink jet recording apparatus having a plurality of nozzle apertures arranged in parallel for generating ink droplets. Information signals as applied to respective electrical energy-mechanical energy converting elements associated with independent ink chambers in communication with the respective nozzle apertures to selectively generate from the nozzle apertures ink droplets necessary for recording in response to the information signals. The electrical signals applied to the converting elements associated with adjoining independent ink chambers are rendered mutually out of phase to thereby prevent generation of surplus ink due to interference between the adjoining independent ink chambers.

Ink jet recording apparatus

A nozzle head of an ink-jet printing apparatus according to the present invention comprises an ink reservoir for storing the ink supplied from an ink tank, a pump chamber provided between said ink reservoir and a nozzle for injecting ink particles, and a fluid diode provided between said ink reservoir and said pump chamber, which are all formed in a same substrate, wherein said pump chamber is caused to change its volume responsive to electric signals so that the ink stored therein is injected from said nozzle, and the ink is prevented from reversely flowing from said pump chamber to said ink reservoir when the volume of the pump chamber is changed, thereby to improve the frequency response of ink particles injected from the nozzle.

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Hitachiota, Japan

Syoji Sagae