Nec Corporation

Toru Yakushiji

Kazuo Shima

Junichi Suetsugu

Yoshihiro Hagiwara

Hitoshi Minemoto

Hitoshi Takemoto

Tadashi Mizoguchi

Tomoya Saeki

Ryosuke Uematsu

Tadashi Mizocuchi

Ryousuke Uematsu

Junichi Suetsucu

An ink jet printer has a plurality of ink ejection electrodes for receiving an ejecting voltage to eject an ink droplet, a pulse width generator for specifying the pulse width of each ejecting electrode to obtain a dot diameter of the ink droplet for gray-scale printing. The ejecting voltage Vej for each ejection electrode is divided into a plurality of unit pulses. Each unit pulse is supplied to a corresponding ejection electrode concurrently with unit pulses for other ejection electrodes. A combination of unit pulses for a single ejection electrode forms a single ink droplet having a dot diameter corresponding to the number of unit pulses, thereby achieving accurate gray-scale printing with a reduced circuit scale.

Electrostatic ink jet printer

A toner density sensor, including a light emitting element and a light receiving element, detects toner density even for a liquid developer having a low transmission factor. The toner density sensor includes a liquid developer tank for retaining liquid developer, a diluting liquid tank for retaining diluting liquid which is a base material of the liquid developer, and a mixing chamber connected to the tanks through two separate valve/pump assemblies which are opened and closed by a controller. A circulation passage is formed in the mixing chamber and has disposed therein a third pump and a transparent cell element. A quantity of light transmitted by the light emitting element and passing through liquid developer in the transparent cell element is measured by the light receiving element on an opposite side of the transparent cell element.

Toner density sensor, and ink jet head, developing unit and image forming apparatus in which toner density sensor is used

An inkjet device ensuring reliable and stable ink ejection is disclosed. A plurality of ejection electrodes are arranged in a housing having an ink chamber containing ink including toner particles and a gate electrode plate is placed at a predetermined distance from the ejection electrodes. The gate electrode plate has a slit formed such that the ejection electrodes are directed to the slit and an ink drain coupled to the slit for draining ink from the slit.

Electrostatic inkjet head having an ink drain for draining ink from a slit

An inkjet device having a plurality of ejection electrodes includes a gate electrode plate having a plurality of gate electrodes therein corresponding to the ejection electrodes, respectively. A voltage difference between the ejection electrode and the gate electrode is generated and is changed between a first value and a second value depending on an input signal. The first value is equal to or greater than a threshold value and the second value is smaller than the threshold value. The threshold value is a minimum value which can cause ejection of particulate matter from each ejection electrode.

Inkjet recording apparatus having gate electrodes and print head thereof

An electrostatic ink jet printing head comprises printing electrodes formed on the base film of a substrate. The printing electrodes have insulating coating films which coat the printing electrodes, respectively. Each of the printing electrodes has a main electrode portion formed on the base film and a protruding electrode portion which protrudes from the base film. A covering member covers the main electrode portion. The covering member has an internal surface defining, in cooperation with the main electrode portions and the base film, a ink receiving space which receives ink containing toner particles.

Simple electrostatic ink jet printing head having low cost

An inkjet recording apparatus includes an insulating support member having a major surface on which a plurality of ejection electrodes are formed with each of the ejection electrodes protruding from an ejection end of the insulating support member. Each of the ejection electrodes is coated with an insulating material. Further, a cover member is provided to cover the insulating support member to form ink chambers between them and an opening at an ejection end of the cover member. The ejection portion of each ejection electrode protrudes from the ejection end of the cover member through the opening. The ink is supplied from one ink chamber to the ejection electrodes and flows into the other ink chamber through the ejection electrodes.

Injet recording apparatus

An electrostatic ink jet recorder of the type controlling charged toner particles contained in ink by using electrophoresis is disclosed. The recorder achieves a miniature and cost-effective configuration by reducing the number of drivers for driving ejection electrodes and auxiliary electrodes. The same amount of toner particles is ejected from all of ejection electrodes despite a scatter in the ejection electrode and a scatter in the position of the ejection electrode relative to auxiliary electrodes and a counter electrode.

Electrostatic ink jet recorder having ejection electrodes and auxiliary electrodes divided into groups

An inkjet recording apparatus includes a plurality of ejection electrodes and a counter electrode which are controlled at predetermined intervals such that a first voltage pulse is applied to a selected ejection electrode depending on input data and a second voltage pulse is applied to the counter electrode in synchronization with the first voltage pulse. The first and second voltage pulses produce a voltage difference between the selected ejection electrode and the second electrode, wherein the voltage difference is not smaller than a predetermined threshold voltage which is a minimum value which causes ejection of particulate matter from the selected ejection electrode.

Inkjet recording apparatus

An electrostatic ink jet recording device includes a recording head having an ink chamber receiving therein liquid ink containing electrified toner particles and a plurality of recording electrodes for ejecting the toner particles from the liquid ink. Each of the recording electrodes is applied with a bias pulse train when the recording head resides in a printing area and a non-printing area, and a selected group of the recording electrodes are applied with a constant recording signal for ejection of toner particles. Undesirable ejection of the toner particles in the non-printing area is avoided by the application of the bias pulse train.

Control system for applying biasing and recording signals to recording electrodes of an electrostatic ink jet recording device

Light of a light emitting portion is received by a total of two light receiving portions disposed opposite to each other through a record medium. The surface condition of the record medium is detected corresponding to the amount of light reflected and the amount of light transmitted so as to determine whether the record medium placed is plain paper, coated paper, OHP film, or the like. By controlling the number of heating elements of a heater or turning on/off the heater, an optimum fixing condition is accomplished.

Electrostatic ink jet recording apparatus that adjusts the amount of heat based on the type of recording material

An ink jet recording head comprises a plurality of electrophoretic electrodes corresponding to a plurality of ejecting electrodes, and a pair of stirring electrodes disposed at both ends of the row of the ejecting electrodes. The stirring of the colored particles by the stirring electrodes prevents block of an ink jet slit by the concentrated colored particles, whereas individual control of the electrophoretic electrodes prevents undesirable ink ejection from non-specified ejecting electrode.

Ink jet recording head having ink stirring electrodes for dispersing ink

In an image forming apparatus operable with a developing liquid consisting of a solvent and toner particles dispersed therein, a device for stirring the liquid includes a reservoir formed with an inlet and an outlet for causing the liquid to be circulated therethrough. A pump delivers the developing liquid from the reservoir to the developing unit. A conduit causes the developing liquid fed from the reservoir to return to the reservoir via the pump and developing unit. The conduit forms a circulation path for preventing the toner particles of the developing liquid from depositing in the reservoir.

Method and device for stirring a developing liquid stored in an image forming apparatus

The quantity of toner particles in an ink is detected by a toner quantity detector. The quantity of toner particles is integrated for a predetermined time period by a controlling portion. The integrated value is compared with a reference value. When the integrated value is smaller than the reference value, a value is opened for a predetermined time period so as to supply a toner in a toner replenisher to an ink tank. Thus, a predetermined quantity of the toner is replenished to the ink tank. After the toner has been replenished, when the integrated value does not become larger than the reference value, a valve is opened for a predetermined time period under the control of the controlling portion so as to replenish a charge control agent from a charge control agent replenisher to the ink tank.

Toner quantity detection and replenishment system for an electrostatic

The electrostatic ink-jet recording head has a head member having a chamber for supplying and discharging ink, a head chip in which a plurality of continuous meniscus shapes are respectively formed on groove portions, a cover plate formed so as to expose a part of the corners of the groove and flange portions, and a protruded member on which pectinate protrusions are formed at the same intervals as those of the meniscus shapes formed on the head chip. A recording electrode is formed on each groove portion. Each protrusion of the protruded member is set on each groove portion of the head chip and moreover, formed so as to be protruded beyond the corner of the flange portion.

Electrostatic ink-jet recording head having a head chip provided with

An ink jet recording device comprises a recording head for ejecting pigmented ink in an ink chamber, an ink reservoir for circulating the pigmented ink between the ink chamber and the ink reservoir, and a replenishment tank for replenishing concentrated pigmented ink to the ink reservoir. The replenishment of the concentrated pigmented ink is effected by a piezoelectric element for reducing the volume of the replenishment tank upon receiving a driving signal. The concentration of colored particles in the concentrated pigmented ink is equal to the concentration of the colored particles in the ink droplet ejected from the ink chamber.

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Niigata, Japan

Toru Yakushiji