Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-04-03
2001-03-27
Barlow, John (Department: 2853)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
Reexamination Certificate
active
06208321
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic ink jet recorder and, more particularly, to an electrostatic ink jet recorder of the type controlling charged toner particles contained in ink by using electrophoresis.
An electrostatic ink jet recorder of the type subjecting ink containing charged toner particles to an electric field and ejecting the ink toward a recording medium on the basis of a Coulomb force acting on the particles is conventional. An ink jet recorder of this type includes an electrophoresis electrode for causing the toner particles to gather at ejection ports due to electrophoresis. A plurality of ejection electrodes each ejects the particles gathering at the associated ejection port. A counter electrode is located at the rear of the recording medium while facing the ejection ports. Auxiliary electrodes are so arranged as to intensify electric fields around the ejection electrodes.
The conventional recorder of the type described has the following problems (1) and (2) left unsolved.
(1) Circuitry for driving the ejection electrodes and auxiliary electrodes is scaled up. Specifically, a single driver must be assigned to each ejection electrode, and a single driver must be assigned to each two auxiliary electrodes. It follows that a multielement head having e.g., electrodes arranged in several ten arrays or a line head having electrodes arranged in several hundred to several thousand arrays needs a prohibitive number of drivers, scaling up drive circuitry. Moreover, an increase in the number of drivers increases the overall size and production cost of the recorder.
(2) Even when the same voltage is applied the ejection electrodes, the amount of toner particles ejected differs from one ejection electrode to another ejection electrode, resulting in dots each having a different shape on a recording medium. This is ascribable to scatters ascribable to the head production process, e.g., scatters in the configuration of the ejection electrodes and ejection ports, the position of the auxiliary electrodes relative to the ejection electrodes, and the distance between the ejection electrodes and the counter electrode. The ejection electrodes, for example, promote the concentration of electric fields more positively when provided with sharper tips, increasing the amount of particles to be ejected and the size of a dot on the recording medium. As the distance between a given ejection electrode and the associated auxiliary electrode or the counter electrode decreases, compared to the distance between another ejection electrode and the associated auxiliary electrode or the counter electrode, the size of a dot on the recording medium increases, and vice versa. Such a scatter in dot size is aggravated when the number of ejection electrodes is increased.
Technologies relating to the present invention are also taught in, e.g., Japanese Patent Laid-Open Publication Nos. 57-11058, 2-217253, 6-286130, and 8-1942.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to solved the above problem (1), i.e., to provide a miniature cost-effective electrostatic ink jet recorder by reducing the number of drivers for driving ejection electrodes and auxiliary electrodes.
It is a second object of the present invention to solve the problem (2), i.e., to provide an electrostatic ink jet recorder capable of ejecting substantially the same amount of toner particles from all of its ejection electrodes despite a scatter in the ejection electrode and a scatter in the position of the ejection electrodes relative to auxiliary electrodes and a counter electrode.
In accordance with the present invention, an electrostatic ink jet recorder for recording an image on a recording medium by applying an electric field to ink containing charged toner particles and ejecting an ink drop based on a Coulomb force acting on the toner particles includes an electrophoresis electrode for causing the toner particles to concentrate at ejection ports. A plurality of ejection electrodes each ejects the toner particles concentrating at particular one of the ejection ports. A counter electrode faces the ejection ports with the intermediary of the recording medium. A plurality of auxiliary electrodes adjoin the plurality of ejection electrodes for intensifying electric fields. The ejection electrodes are divided into a plurality of groups and applied with a voltage group by group. The auxiliary electrodes are also divided into a plurality of groups and applied with a voltage group by group.
REFERENCES:
patent: 4553150 (1985-11-01), Katahira
patent: 4794463 (1988-12-01), Tamura et al.
patent: 0 761 443 (1997-03-01), None
patent: 0 778 138 (1997-06-01), None
patent: 2 031 344 (1980-04-01), None
patent: 57-11058 (1982-01-01), None
patent: 2-217253 (1990-08-01), None
patent: 6-286130 (1994-10-01), None
patent: 8-1942 (1996-01-01), None
Patent Abstracts of Japan, vol. 009, No. 272, Jun. 22, 1985 (corresponds to JPA 60-116458).
Hagiwara Yoshihiro
Minemoto Hitoshi
Mizoguchi Tadashi
Saeki Tomoya
Shima Kazuo
Barlow John
Gordon Raquel Yvette
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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