Nec Corporation

Kazuo Shima

Junichi Suetsugu

Yoshihiro Hagiwara

Hitoshi Minemoto

Toru Yakushiji

Hitoshi Takemoto

Tadashi Mizoguchi

Ryosuke Uematsu

Tomoya Saeki

Minoru Yamada

Junichi Fujisawa

Yoshihiro Hagihara

Ryousuke Uematsu

Tadashi Mizocuchi

Junichi Suetsucu

Ryosuki Utmatsu

An ink jet print head comprises a substrate formed with a heating resistor, an ink path defining member for defining an ink supply path, and a orifice plate, and in the orifice plate, there is formed an ink outlet at the position opposing the heating resistor. Further, a heating zone surrounding the heating resistor is formed at the position corresponding to the heating resistor of the ink supply path. The channel resistance of the ink supply path is set so that a relationship is established between a quantity q of the discharged ink drop, a sectional area A of the ink outlet, and a maximal projection h that a meniscus of the ink has when it projects from the ink outlet after it has restored the exit level from a retreat position it had after the drop of the ink had been discharged, such that 0<h<0.3 q/A. Consequently, there is obtained a high-speed printing of high quality without dispersion.

Ink jet print head

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 electrostatic ink jet recording head of a drop-on-demand type has a head body defining an ink chamber for receiving liquid ink containing charged toner particles, a set of electrodes for migrating the liquid ink by electrophoresis and ejecting the liquid ink from an ejecting slit of the ink chamber, and an ink reservoir, disposed above the ink chamber, for circulating the liquid ink by gravity between the ink reservoir and the ink chamber. A flow resistance against the liquid ink in the flow path from the outlet port of the ink chamber to the ink reservoir is smaller than a meniscus force generated by meniscuses formed at the ejecting slit to effectively eject the liquid ink without a pump and without an ink leakage.

Electrostatic ink jet recording head having electrophoretic electrode and gravity ink reservoir

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 recording device which provides stable printing by preventing too much charged toner from gathering around an ink discharge aperture even if the charged toner has not been discharged for a long time. If the charged toner is not to be discharged, the potential difference between the electrophoretic electrode and the discharge electrode is so controlled as to suppress electrophoretic movement of the charged toner toward the ink discharging aperture, or the potential difference is made zero. If the charged toner is to be discharged, the voltage applied to the discharge electrode is kept lower than the voltage applied to the electrophoretic electrode for a predetermined period of time before discharging a jet of the charged toner.

Ink-jet recording device for suppressing excess electrophoretic accumulation of charged particles

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.

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Niigata, Japan

Kazuo Shima