Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-02-18
2001-11-27
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S068000, C347S071000
Reexamination Certificate
active
06322203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ink jet recording head for elastically deforming an elastic plate forming a pressure generation chamber by a piezoelectric vibrator and jetting ink in the pressure generation chamber as an ink drop through a nozzle opening and more particularly to a structure of a flow passage formation substrate.
2. Description of the Related Art
An ink jet recording head is designed for pressurizing a pressure generation chamber communicating with a common ink chamber and a nozzle opening by pressure generation means, such as a heating element provided in the pressure generation chamber or a piezoelectric vibrator provided so as to be able to deform a part of the pressure generation chamber, for jetting ink drops.
For example, JP-A-9-123448 proposes an ink jet recording head wherein a substrate is formed on both faces with first and second pressure generation chambers as concaves, wherein each pressure generation chamber is provided with first and second ink supply ports as slightly narrowed concaves communicating with a reservoir, and wherein a nozzle communication hole in the form of a through hole is made in an area opposed to the nozzle opening.
In this type of recording head, the pressure generation chamber volume can be made small and minute ink drops fitted to graphics print can be jetted. In addition, the through hole occupying the substrate is small and rigidity can be provided, thus the substrate can be made thin and it is possible to shorten the etching time and reduce material costs.
However, as shown in
FIG. 18
, since substrate
100
is formed on both faces with first and second flat pressure generation chambers
41
(not shown) and
103
, when a nozzle opening
103
is sealed with a cap and negative pressure is made to act on the nozzle opening
103
from the outside for forcibly discharging ink for recovering ink drop jet performance, the flow velocity of ink flowing into the pressure generation chamber
41
,
102
from reservoir
104
easily decreases. Thus, bubbles easily accumulate particularly in the pressure generation chamber
41
on the piezoelectric vibrator
105
side. Since the bubbles absorb pressure applied by the piezoelectric vibrator, as is known, the ink drop jet capability lowers, degrading print quality. In
FIG. 18
, numerals
106
and
107
denote first and second ink supply ports.
Since the pressure generation chambers become shallow as compared with the case where the pressure generation chamber is formed as a single chamber, flow passage resistance of the pressure generation chamber is large and ink supply from the reservoir to the pressure generation chamber is delayed, slowing down drive speed.
SUMMARY OF THE INVENTION
According to the invention, there is provided an ink jet recording head comprising a flow passage formation substrate comprising a reservoir, a first ink supply port formed on a face opposed to an elastic plate, a second ink supply port formed on a face opposed to a nozzle plate, first and second pressure generation chambers communicating with the reservoir through the first and second ink supply ports, and a nozzle communication hole made so as to be spread and opened to the nozzle opening side so as to allow the first and second pressure generation chambers to communicate with each other, a nozzle plate having a nozzle opening for sealing one face of the flow passage formation substrate, the elastic plate for sealing an opposite face of the flow passage formation substrate, and pressure generation means for pressurizing the pressure generation chambers.
Thus, when the nozzle plate is sealed with a cap and negative pressure is made to act on the nozzle plate, the nozzle communication hole spread and opened to the nozzle opening side causes the flow velocity of ink to increase in the proximity of the nozzle communication hole and bubbles accumulating in the first pressure generation chamber can be promptly moved to the second pressure generation chamber on the nozzle opening side and can be reliably discharged.
Since flow passage resistance and inertance of the nozzle communication hole can be held at low values, a pressure wave occurring after an ink drop is jetted can be allowed to rapidly pass through the nozzle communication hole for improving the response speed and ink drop jet stability.
It is therefore a first object of the invention to provide an ink jet recording head capable of preventing bubbles from accumulating in a pressure generation chamber while improving ink supply to the pressure generation chamber.
It is a second object of the invention to provide an ink jet recorder comprising the ink jet recording head.
REFERENCES:
patent: 5455615 (1995-10-01), Burr et al.
patent: 5754205 (1998-05-01), Miyata et al.
patent: 6010209 (2000-01-01), Kitahara
patent: 6137511 (2000-10-01), Furuhata et al.
patent: 6139132 (2000-10-01), Yasukawa et al.
patent: 707961 (1996-04-01), None
patent: 761447 (1997-03-01), None
patent: 778140 (1997-06-01), None
patent: 0761447 A2 (1997-03-01), None
patent: 9-123448 (1997-05-01), None
Barlow John
Do An H.
Seiko Epson Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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