Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-10-07
2002-04-16
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06371602
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ink-jet recording head and a process for its formation; the ink-jet recording head being an ink-jet recording head comprising a plate member in which a plurality of pressure chambers partitioned with sidewalls are formed in the form of grooves and one side surface of which is caused to vibrate by a piezoelectric device to thereby control the pressure of an ink held in the pressure chambers and eject the ink from nozzles communicating with the pressure chambers.
2. Description of the Related Art
In conventional ink-jet recording heads, as shown in
FIG. 10A
, to a cavity plate
103
on one side surface of which pressure chambers (cavities)
101
are formed in the form of grooves, a plate material
105
is joined with an adhesive or the like on the one side surface where the pressure chambers open, to close the pressure chambers
101
, and vibrating plates
107
and piezoelectric devices
109
are arranged on the plate material
105
. Then, a drive voltage is applied to electrodes
111
and
113
provided to the piezoelectric devices
109
, to thereby cause the piezoelectric devices
109
to deform and, concurrently therewith, the plate material
105
closing the pressure chambers
101
to deform, so that the pressure of ink in the pressure chambers
101
can be controlled to eject the ink outward from nozzles communicating with the pressure chambers
101
.
In such a ink-jet recording head, usually a plurality of pressure chambers
101
are provided and the ink is ejected from the nozzles communicating with the pressure chambers
101
, where it is important from the viewpoint of print quality that their ejection performance is uniform.
Now, the pressure chambers
101
are closed by joining the plate material
105
to the cavity plate
103
at the top edge faces
117
of the sidewalls that partition the pressure chambers
101
. Thus, originally independent materials are joined to each other in respect of the cavity plate
103
forming the pressure chambers
101
and the plate material
105
deformed by the piezoelectric devices
109
. Hence, the state of joining between them is greatly concerned with the deformation properties of the plate material
105
, and the uniformity of accuracy at the joints affects the uniformity of ejection performance of the nozzles.
In order to uniform the accuracy at the joints, the top edge faces
117
of the sidewalls
115
and the plate material
105
side are required to have a high flatness. They are also required to be uniformly joined at the joints when joined with an adhesive or the like.
However, it is difficult to achieve a high flatness and uniform joining at the all joints, and any slightly non-uniform flatness or joining may cause a delicate change in the deformation properties of the plate material
105
, vibrating plates
107
and piezoelectric devices
109
which are supported at the top edge faces
117
of the sidewalls
115
, making it difficult to impart uniform ejection performance to all nozzles.
As also shown in
FIG. 10B
, in order to double resolution, one may have an idea that pressure chambers
201
are formed on both sides of a cavity plate
203
in a alternately half-pitch shifted state, and laminates of piezoelectric devices
209
and vibrating plates
207
, respectively formed on plate materials
205
, are joined in such a way that their positions are in agreement with the positions of the open areas of the pressure chambers
201
, and thus the nozzles can be provided in a higher density. Since, however, the above problem also arises on the both sides, the problem of the non-uniformity in flatness and joining becomes more serious, bringing about the problem that it is difficult to make the nozzle density higher.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink-jet recording head that can prevent the deformation properties of plate materials, cavity plates and piezoelectric devices from being affected by the non-uniform flatness and joining for each sidewall and can impart uniform ejection performance to all nozzles, and a process for forming such an ink-jet recording head.
To achieve the above object, the present invention provides an ink-jet recording head comprising a plate member in which a plurality of pressure chambers partitioned with sidewalls are formed in the form of grooves and one side of which is caused to vibrate by a piezoelectric device to thereby control the pressure of an ink held in the pressure chambers and eject the ink from nozzles communicating with the pressure chambers; wherein a sheet type piezoelectric device provided with electrodes and having been polarized is laminated to the plate member on the side opposite to the pressure chambers-formed side.
The present invention also provides a process for forming the ink-jet recording head as above; the process comprising the steps of;
forming an electrode on the surface of an unbaked sheet type piezoelectric device;
joining the sheet type piezoelectric device to the plate member on its one side, made of a material having a nature similar or identical to the sheet type piezoelectric device, to form a laminate;
baking the laminate, and after the baking;
forming pressure chambers in the form of grooves on the surface of the laminate on the plate member side;
covering the pressure chambers with a sheet-like cover member; and
before or after the covering with the sheet-like cover member, subjecting the sheet type piezoelectric device to polarization.
This and other objects, features and advantages of the present invention are described in or will become apparent from the following description.
In the ink-jet recording head of the present invention, a sheet type piezoelectric device provided with electrodes and having been polarized is laminated to the plate member on the side opposite to the pressure chambers-formed side. More specifically, the sheet type piezoelectric device is laminated to the plate member not on the open side of the pressure chambers but on its external surface on the side opposite thereto. This lamination can be achieved by, e.g., a method in which the sheet type piezoelectric device is joined with an adhesive to a plate member in which grooves for the pressure chambers have been made, or a method in which an unbaked sheet type piezoelectric device and an unbaked plate member with the grooves are brought into close contact by vacuum pressing or the like followed by baking to form the pressure chambers.
Accordingly, since the sheet type piezoelectric device is not joined on the open side of the pressure chambers of the plate member, it follows that the device is not joined to the top edge faces of the sidewalls partitioning the pressure chambers and is laminated to the external surface on the opposite-side continuous single surface of the plate member. Thus, for both the sheet type piezoelectric device side and the plate member side, the uniformity concerning flatness and joining may be achieved on the single surface, so that a lamination that is uniform over the all pressure chambers can be achieved with ease and hence an ejection performance that is uniform over the all nozzles can be attained.
The other side of the plate member, the open side of the pressure chambers, may be covered with a sheet-like cover member. Even if this sheet-like cover member is joined a little non-uniformly, there can not be any effect that may come into question on the ejection performance, because any deformation does not take place on the side of the sheet-like cover member.
As the direction of polarization, the sheet type piezoelectric device may be polarized, e.g., in its thickness direction. In this instance, the electrodes may be so disposed that the direction of electric fields is identical with or reverse to the direction of polarization, i.e., in what is called the unimorph type formation. For example, the electrodes may be so disposed that they are formed on both sides of the sheet type piezoelectric device, where,,of the electrodes,
Brooke Michael S
Brother Kogyo Kabushiki Kaisha
LandOfFree
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