Hitachi Printing Solutions, Ltd.

Hitachi Koki Co., Ltd.

Ricoh Printing Systems, Ltd.

Hitachi, Ltd.

Ricoh Company, Ltd.

Kunio Satou

Hitoshi Kida

Shinya Kobayashi

Takahiro Yamada

Kazuo Shimizu

Katsunori Kawasumi

Lee Chahn

Yoshikane Matsumoto

Toshitaka Ogawa

Akemi Ouchi

Hidetoshi Fujii

Susumu Saito

Masaya Adachi

Nobuyoshi Hoshi

Mamoru Okano

Shunichi Oohara

Tsutomu Maekawa

Kazuhito Masuda

Osamu Machida

Kunihiro Tamahashi

Yoshinari Suzuki

Takashi Sekino

Eiichi Toyama

Masuo Furutono

Naoto Ueda

The invention provides a double feed sensing device capable of sensing double feed of paper sent out for the first time. The double feed sensing device includes a thickness sensing unit for sensing thickness of cut paper conveyed, a rigidity sensing unit for sensing bending rigidity of the conveyed paper, and a double feed determining unit for comparing a value of the thickness of the paper sensed by the thickness sensing unit and a value of the bending rigidity of the paper sensed by the rigidity sensing unit with threshold values of thickness and rigidity of the paper set based on values of thickness and bending rigidity of one sheet of the paper and values of thickness and bending rigidity of stacked sheets of the paper, so as to determine whether the paper is double-fed or not.

Double feed sensing device, double feed determining method and image forming apparatus

When an refresh ink droplet ejected from a nozzle and deflected by an inclined electric field impinges on a orifice electrode/ink receiving member, electric charge is discharged from the refresh ink droplet, thereby an electric current is generated. A current-voltage converter/amplifier detects the electric current and outputs a detection signal. A defective-condition determining circuit determines an ejection condition of a nozzle element based on voltage value of the detection signal.

Detection device for detecting ejection condition of nozzles

An ink jet head includes: a chamber plate having a plurality of pressuring chambers formed therein for storing an ink; a vibrating plate bonded to the chamber plate; a housing having an ink flow path through which an ink is supplied into the pressuring chambers; an orifice through which an ink is ejected from the pressuring chambers; and a longitudinal vibration mode piezoelectric element for generating pressure under which an ink droplet is ejected through the orifice. A thickness of the vibration plate is from 5 &#x3bc;m to 10 &#x3bc;m.

Ink jet head and droplet ejection device having same mounted thereon

A computer portionof a printer includes a memory storing a printer driver softwareand nozzle profile data. The printer driver softwareincludes a raster image processor (RIP). When the RIPreceives document data, the RIPconverts the document datainto bitmap datawhich is one dot/one bit data for 300 data/inch. Then, the nozzle data converting portionconverts the bitmap datainto driving databased on the nozzle profile data. At this time, each bit of the bitmap datais replaced by 16 bits. That is, the data amount is increased to 16 times of the bitmap data. Accordingly, fine control of ink ejection can be achieved.

Line scanning type ink jet recording device capable of finely and individually controlling ink ejection from each nozzle

During a printing operation, a recording device is switched from a normal mode to a refresh ejection mode so as to temporarily increase an ejection frequency. A refresh ink droplet ejected in the refresh ejection mode is deflected to impinge on an ink collector. Recording ink droplets ejected in the refresh ejection mode are deflected and impinge on a recording sheet at positions that are shifted by gradually smaller distances.

Inkjet recording device with ink refresh function

A recording headhas a plurality of nozzle orifices aligned in a row extending in a first direction. The recording headis arranged with the nozzle orifices in confrontation with a recording medium P. The recording medium P is moved in a second direction B with respect to the recording head. Also, ink droplets ejected from the nozzle orifices are charged to a charged amount that corresponds to deflection amount of the ink droplets. The charged ink droplets are deflected in a direction perpendicular to a main scanning line. The plurality of ink droplets ejected from the plurality of nozzle orifices impinge on the same pixel position or at a nearby position so that it is possible to impinge multiple droplets at the same pixel position or a nearby position. As a result, it is possible to back up broken nozzles and to reduce recording distortion.

Line scan type ink jet recording device

An inkjet recording device includes an ink reservoir that stores ink, a recording head having a plurality of nozzle holes for forming recording dots on a recording medium by ejecting ink particles from the plurality of nozzle holes onto the recording medium positioned opposite the plurality of nozzle holes, an ink channel for supplying ink from the ink reservoir to the recording head, ink discharging means for discharging ink from the recording head and the ink channel, evacuating means for creating a vacuum state in the recording head and the ink channel, and ink filling means for filling the evacuated recording head and ink channel with deaerated ink. The ink discharging means divides the recording head and the ink channel into a plurality of sections and independently discharges ink from each section of the recording head and the ink channel.

Inkjet recording device and ink supplying device employed thereby

An orifice electrode/ink receiving member is attached to an orifice plate that is attached to a recording head module . An ink absorbing member is embedded in a lower surface of the orifice electrode/ink receiving member . A recording ink droplet ejected through an orifice is deflected as needed by an angled electric field and then impinges on a recording sheet to form a recording dot . On the other hand, a refresh ink droplet is deflected by the angled electric field and impinges on the ink absorbing member of the orifice electrode/ink receiving member after flying in a U-turn path. In this configuration, the ink absorbing member provided to the orifice electrode/ink receiving member collects ink, so that there is no need to increase a gap between the recording head module and the recording sheet so much in order to dispose the ink absorbing member , preventing decrease in recording precision and paper jam. Also, it is possible to perform the ink refresh operation using a minimum amount of ink anytime needed without stopping recording operations.

Refresh ink ejection device and inkjet recording device including the refresh ink ejection device

A plurality of nozzle rows are formed in a nozzle plate, and nozzle electrodes for generating a deflecting field are provided for every two nozzle rows. Each electrode is attached to the nozzle plate so as to locate between the corresponding adjacent two nozzles. Ink reception absorption bodies are embedded in the bottom surface of the electrodes. Refresh ink droplets deflected by the deflecting field travels along U-turn paths and impinge on the ink reception absorption bodies.

Inkjet head provided with deflecting electrodes for deflecting ejected ink droplets

When a pixel-dividing number is increased to a predetermined number or more, then nozzles in each nozzle group become in one-to-one correspondence with the sub-pixel number, so that only one of the nozzles performs ink ejection at one time. Accordingly an analog driving signal drives only a single nozzle in the corresponding group at one time. Therefore, by trimming the analog driving signal in accordance with a subject nozzle each time, the all-amount trimming is possible without providing a large number of analog-driving-signal generating devices for all of the nozzles.

Inkjet recording device capable of controlling ejection timing of each nozzle individually

An inkjet head selectively ejects recording ink droplets and refresh ink droplets. The recording ink droplets are deflected so as to impinge on target locations on a recording medium, thereby forming recording dots thereon. On the other hand, the refresh ink droplets are deflected so as to impinge on an ink absorbing member. The ink clinging on the ink absorbing member is collected into an ink tank and reused. The ink absorbing member functions as a filter for preventing impurities being collected into the ink tank along with the ink.

Inkjet recording device that reuses refresh ink

When ink droplets are ejected, angled or splashed where a plurality of minute ink droplets are generated, angled or splashed ink clings on an electrode 401, 402 and increases the amount of electric current conducted therethrough. Hence, the defectiveness of ink ejection can be detected by monitoring the amount of the electric current. When the defectiveness of ink ejection is detected, ejection data D is retrieved and updates the ejection data D based on a condition register S, and set to a defect register E. When the defect register E has only one element that takes a condition value of 1 indicating defectiveness, the corresponding nozzle is identified as defective. The restoring means reallocates dots, which have been originally allocated to the defective nozzle, to neighboring nozzle.

Multinozzle ink jet recording device capable of identifying defective nozzle

When positively charged ink droplets from a defective nozzle impact a negatively charged deflector electrode , the positive charge on condenser flows to the ground via a FET of a photo-coupler . As a result, the electric discharge occurs by an amount equivalent to the charging amount of the ink droplets clinging on the electrode . Because a switching signal is &ldquo;1&rdquo;, the ON resistance of the photo-coupler is large, and the ON resistance of the FET of the photo-coupler is small. Accordingly, the discharge due to the charged ink droplets is detected as a large detection voltage and amplified by an operational amplifier . Because the charger voltage of the condenser is static and has no noise, even when the detection output is highly amplified, noise during the detection is suppressed.

Ink jet recording device capable of detecting defective nozzle with high signal-to-noise ratio

A sheet-position synchronizing signal is generated once each time a recording sheet is transported by a single-line worth of distance in a sheet feed direction. A print-driving signal and a refresh-driving signal are generated within a time interval of two successive sheet-position synchronizing signal. When the print-driving signal is applied to a piezoelectric element of a nozzle, then a print ink droplet is ejected, thereby a dot is formed on a recording sheet. On the other hand, when the refresh-driving signal is applied to the piezoelectric element, then a negatively-charged refreshing ink droplet is ejected. The refresh ink droplet refreshing ink droplet is deflected by an electric field and collected by a metal mesh without reaching the recording sheet.

Inkjet recording device capable of performing ink refresh operation without stopping printing operation

As shown in FIG. ( ), an electric field is generated at timing T at which an ink droplet is divided, end moves the negative ions toward a main ink portion As shown in FIG. ( &prime;), a resultant main ink droplet M has an increased charging amount of &minus;3 q, and a satellite ink droplet S has a decreased charging amount of &minus;6 q. When the main ink droplet M and the satellite ink droplet S have the mass of 1 m and Qs, respectively, then the relative charging amounts of the main ink droplet M and the satellite ink droplet S are both &minus;3. Hence, the deflection amount of the satellite ink droplet S is approximately equal to the deflection amount of the main ink droplet M. Accordingly, the satellite ink droplet S and the rain ink droplet M impact the recording sheet on the same spot or on the extremely close spots, thereby forming a single dot.

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Hitachinaka, Japan

Kunio Satou