Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-06-11
2001-04-17
Fuller, Benjamin R. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S065000
Reexamination Certificate
active
06217161
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet printer head.
2. Description of the Related Art
There is an actuator of a head equipped in an ink jet printer, which expands and restores the capacity of many ink storing chambers formed inside the actuator using a piezoelectric element installed corresponding to each of the ink storing chambers, and which applies pressure to the ink inside the ink storing chamber. In this way, the actuator discharges the ink from an ink discharge hole formed in each of the ink storing chambers to the external i.e., onto the recording sheet.
As one example of such an actuator, this is an actuator provided with: a cavity plate in which the ink storing chambers and ink flow paths to supply the ink to the ink storing chambers are formed; and a nozzle plate in which fine ink discharge holes are formed.
The ink discharge holes may be arranged tandem in two rows along a longitudinal direction of the cavity plate at a central surface portion of the cavity plate. Along this tandem direction of the ink discharge holes, two ink flow paths are formed on both peripheral surface portion of the cavity plate. The ink storing chambers store the ink supplied from these ink flow paths, and introduce the ink to the ink discharge holes, such that a plurality of grooves connecting the ink flow paths with the ink discharge holes are arranged along the tandem direction of the ink discharge holes.
These ink storing chambers are separated from each other by respective one of separating walls, each of which is called as a beam. By accurately keeping the width, the height and the arrangement interval (the pitch) of the beam to be predetermined values respectively, the variations of the capacities of the ink storing chambers can be reduced, and that the ink discharge ability can be improved.
However, since the above mentioned cavity plate is formed by injection-molding ceramic such as alumina and then sintering the ceramic, it is necessary to apply a polishing process after the molding and sintering processes, so that it is difficult to keep the width, the height and the arrangement interval of the beam to be predetermined values respectively.
Namely, in a case of forming the beam in a perpendicular wall shape, since the physical or mechanical strength at a root portion of the beam is weak enough to be easily broken, the beam is formed with a certain taper angle. In such a case, there is raised a problem that the width of the beam is changed by the polishing amount.
Further, in a case of fixing the cavity plate onto the piezoelectric element member, it is necessary to adhere a partition plate called as a diaphragm on the cavity plate. In such a case, there is raised a problem that the adhesive agent coated on the beam tends to flow into the grooves from the beam in the taper shape, and the capacity of the ink storing chamber is reduced.
SUMMARY OF THE INVENTION
Given these circumstances, it is an object of the present invention to provide an ink jet printer head, in which the physical strength of the beam can be improved, in which the beam can be accurately formed and in which the adhesive agent can be prevented from flowing into the grooves between the adjacent beams.
The above object of the present invention can be achieved by an ink jet printer head for discharging ink provided with: a cavity plate prescribing (i) an ink flow path through which the ink is supplied, (ii) a plurality of ink storing chambers, each of which is connected to the ink flow path in which the supplied ink is temporarily stored, and (iii) a plurality of ink discharge holes which are connected to respective one of the ink storing chambers though which the temporarily stored ink is discharged; a piezoelectric element member, which is shaped in a plate opposed to the cavity plate and has a plurality of piezoelectric elements for selectively changing capacities of the ink storing chambers; and a partition plate interposed between the cavity plate and the piezoelectric element member such that each of the ink storing chambers be a closed space for temporarily storing the ink. The cavity plate is provided with a main plate portion and a plurality of partition wall portions, which stand from the main plate portion and are arranged at substantially equidistant intervals, for partitioning the ink storing chambers adjacent to each other. Each of the partition wall portions includes (i) a straight wall portion, which is disposed at a tip side thereof and is constant in width from the tip side toward a root side thereof to prescribe a straight wall substantially perpendicular to the main plate portion, and (ii) an inclined wall portion, which is disposed at the root side, increases in width from the tip side toward the root side to prescribe an inclined wall oblique to the main plate portion.
According to the ink jet printer head of the present invention, at the time of forming the cavity plate, a polishing process is applied after a molding process such as an injection molding process is applied. On one hand, since the partition wall portion includes the straight wall portion at the tip side thereof and since the polishing process is applied to the straight wall portion (but not to the inclined wall portion), even if there is a certain variation in the polishing amount, the capacities of the ink storing chambers can be kept constant to each other because of the uniform width of the straight wall portion. On the other hand, since the partition wall portion includes the inclined wall portion at the root side thereof, the physical strength of the partition wall portion can be improved and it is possible to prevent the partition wall portion from being broken at the time of performing the polishing process etc. Further, since the surface of the partition wall portion opposed to the piezoelectric element member through the partition plate is the tip surface of the straight wall portion, it is possible to prevent or restrain the adhesive agent coated on this tip surface from flowing into the ink storing chambers.
In one aspect of the ink jet printer head of the present invention, the inclined wall portion has a taper with a predetermined taper angle.
According to this aspect, since the inclined wall portion has the taper, the physical strength of the partition wall portion at the root side can be certainly improved and it is possible to prevent the partition wall portion from being broken at the root side, at the time of performing the polishing process etc.
In another aspect of the ink jet printer bead of the present invention, the inclined wall portion has a curved surface with a predetermined radius of curvature.
According to this aspect, since the inclined wall portion has the curved surface, the physical strength of the partition wall portion at the root side can be certainly improved and it is possible to prevent the partition wall portion from being broken at the root side, at the time of performing the polishing process etc.
In another aspect of the ink jet printer head of the present invention, the cavity plate and the partition plate are adhered to each other by adhesive agent.
According to this aspect, although the cavity plate and the partition plate are adhered by means of the adhesive agent, since the surface of the partition wall portion adhered to the partition plate is the tip surface of the straight wall portion, it is possible to prevent or restrain the adhesive agent coated on this tip surface from flowing into the ink storing chambers.
In this aspect of the ink jet printer head of the present invention, the adhesive agent may be coated on a tip surface of the straight wall portion. In this case, it is certainly possible to prevent or restrain the adhesive agent coated on the tip surface of the straight wall portion from flowing into the ink storing chambers.
In another aspect of the ink jet printer head of the present invention, a tip surface of the straight wall portion is polished.
According to this aspect, since the straight wall portion is
Deguchi Masaaki
Inose Toshio
Brother Kogyo Kabushiki Kaisha
Dickens C
Fuller Benjamin R.
Oliff & Berridg,e PLC
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