Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-02-23
2001-06-05
Fuller, Benjamin R. (Department: 2855)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C310S328000, C347S094000
Reexamination Certificate
active
06241346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head for recording images and characters on recording paper by emitting ink droplets from nozzle apertures by the expansion and contraction of piezoelectric vibrators operating in a longitudinal vibration mode.
2. Background
It is known to use a recording head having piezoelectric vibrators which operates in a longitudinal vibration mode and which can be driven at a high speed. Such a recording head includes a passage unit formed by laminating a nozzle plate having nozzle apertures, a passage forming plate having pressure generating chambers and reservoirs, and an elastic plate. The recording head is driven by a vibrator unit including piezoelectric vibrators which expands and contracts in its longitudinal direction with one end of the vibrator being fixed to a fixing base.
With such a vibrator unit, since the rigidity of the vibrator itself is high, the area of the contact surface with the pressure generating chamber can be reduced and the vibrator unit will still be suitable for a recording head designed for high density printing. However, when high density printing is desired, there are the following concerns: (1) the array pitch is extremely small; (2) the reaction force which operates on a fixing base is extremely large; (3) the amount of deflection of the fixing base is varied depending upon the number of simultaneously driven piezoelectric vibrators; and (4) the capacity of the emission of ink droplets depends upon the number of simultaneously driven piezoelectric vibrators.
To address these concerns, measures have been taken, such as providing a fixing base made of a very rigid material and a reinforcement member, such as metal, inserted between a frame for integrally fixing the passage unit and the vibrator unit. However, there is a problem associated with this solution in that the fixing base is too large and the assembly is complicated.
SUMMARY OF THE INVENTION
The present invention is made to solve such problems and the object is to provide an ink jet recording head in which the displacement characteristic of each piezoelectric vibrator can be equalized without increasing the overall size of the recording head. Further, the displacement characteristics are consistent independent of the number of piezoelectric vibrators that are driven.
To solve such problems, according to the present invention, the ink jet recording head includes: a passage unit including at least one nozzle aperture, a chamber associating with said nozzle aperture, and an elastic plate serving as a part of a wall of said chamber; and a plurality of piezoelectric vibrators fixed at one end portion thereof to said fixing plate at a predetermined pitch and contacting said elastic plate at another end portion thereof, said piezoelectric vibrators being actuated in a longitudinal vibration mode for emitting an ink droplet by deflecting said elastic plate to expand or contract said pressure generating chamber; and an elastically deformable connecting member extending across said piezoelectric vibrators in a transverse direction and secured thereto. The displacement of the piezoelectric vibrators is controlled by the connecting member. Accordingly, in case multiple piezoelectric vibrators are simultaneously displaced, the mutual displacement and the displacement speed are equalized by the connecting member and the variation of the displacement characteristic depending upon the number of driven piezoelectric vibrators is controlled.
Further, dummy piezoelectric vibrators are disposed at opposite sides of the array of piezoelectric vibrators and an end of said connecting member is fixed to said dummy vibrator. Finally, according to one embodiment, the connecting member includes an elastically deformable ribbon cable for supplying a driving signal to said piezoelectric vibrators.
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Dickens C.
Fuller Benjamin R.
Seiko Epson Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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