Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-12-14
2001-06-19
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S015000
Reexamination Certificate
active
06247776
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a recording apparatus with employment of an ink jet recording head in which a piezoelectric vibrating element is used in an actuator capable of applying pressure to a pressure producing chamber, and more specifically, to a drive technique for the ink jet type recording head.
BACKGROUND TECHNIQUE
In an ink jet type recording head, while piezoelectric materials and conductive layers are alternately stacked as a piezoelectric vibrating element, either such a piezoelectric vibrating element of a longitudinal vibration mode expanding along an axial direction thereof, or a displacement type piezoelectric vibrating element which is provided on a surface of an elastic plate and is displaced by deflection is employed. In this ink jet type recording head, a pressure producing chamber, a portion of which is constituted by an elastic plate and is communicated to a nozzle opening, is expanded/compressed by a piezoelectric vibrating element, so that ink is refilled into the pressure producing chamber and the ink of the pressure producing chamber is pressurized. As a result, ink droplets are jetted from the nozzle opening.
The piezoelectric vibrating element having the longitudinal vibration mode has high rigidity, and can be driven at high speeds. On the other hand, this piezoelectric vibrating element owns such a problem that since this piezoelectric vibrating element is required to be assembled to the elastic plate in a three-dimensional manner, complex manufacturing steps are required.
To the contrary, in the latter-mentioned ink jet type recording head with employment of the deflection displacement type piezoelectric vibrating element, either the green sheet made of the piezoelectric material can be attached, or can be directly formed on the surface of the elastic plate by way of the film forming method. As a result, the manufacturing steps thereof can be simplified. However, this recording head with using the deflection displacement type piezoelectric vibrating element would require a larger displacement area than that of the recording head with using the piezoelectric vibrating element operable in the longitudinal vibration mode. Accordingly, the volume of the pressure producing chamber is increased, and thus the ink amount of the ink droplets jetted from this recording head is also increased. This recording head owns such a difficulty. That is, it is practically difficult to form dots having very small sizes such as graphic printing operation.
To solve such a problem, it is conceivable to reduce the displacement of the deflection displacement type piezoelectric vibrating element, so that the ink amount of the jetted ink droplets maybe decreased. However, the jetting pressure is also reduced, so that the speed of the ink droplets is lowered. As a result, there are errors at the ink impinge positions on the recording medium. In particular, there is such a problem that the printing quality is apparently deteriorated in a printing operation such as graphic printing operation that precise dots are required to be formed.
The present invention has been made to solve these problems, and has an object to provide an ink jet type recording apparatus capable of forming dots suitable for a graphic printing operation by that an ink amount for constituting ink droplets is reduced as small as possible without lowering jetting speeds of the ink droplets by way of a recording head in which a piezoelectric vibrating element is employed as a drive source.
DISCLOSURE OF THE INVENTION
An ink jet type recording apparatus, according to the present invention, is featured by comprising; an ink jet type recording head including a pressure producing chamber communicated with a nozzle opening and a reservoir, for expanding/compressing the pressure producing chamber by using a piezoelectric vibrating element so as to jet an ink droplet from the nozzle opening; and drive means for outputting a drive signal to the piezoelectric vibrating element, the drive signal executing a first expansion stage for expanding the pressure producing chamber, a first compression stage for compressing the pressure producing chamber in order to jet the ink droplet from the nozzle opening, a second expansion stage for expanding the pressure producing chamber, the volume change of which is smaller than that achieved in the first expansion stage, and further a second compression stage for compressing the pressure producing chamber. The pressure producing chamber is compressed in the second compression step stage, and the pressure producing chamber is expanded in the first expansion stage, so that the meniscus produced just before the ink droplet is jetted is moved back to the pressure producing chamber side. Thereafter, the pressure producing chamber is expanded in the first expansion stage, so that a small ink amount of ink droplets can be jetted without lowering the jetting speeds of the ink droplets.
REFERENCES:
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patent: 6024438 (2000-02-01), Koike et al.
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International Search Report (foreign language).
Katakura Takahiro
Usui Toshiki
Barlow John
Hallacher Craig A.
Seiko Epson Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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