Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-12-27
2002-10-15
Nguyen, Thinh (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S094000
Reexamination Certificate
active
06464344
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microstructured element. The present invention also relates to a method for producing a microstructured element.
2. Description of the Related Art
Various types of structural minute elements have been used in miniature or precision equipment for various physical purposes. For example, in the technical field of printing machines, a print or ink-jet head incorporated in an ink jet printer or plotter is known as one example of miniature or precision equipment including minute elements. A thermal-type print head of a conventional ink jet printer or plotter generally includes a body with a plurality of channels or grooves, a base secured to the body so as to cover the length of the grooves, a plurality of heating elements arranged on a surface of the base facing toward the body, and a nozzle plate fixed to the body adjacent to the longitudinal ends of the grooves. The body, the base and the nozzle plate are structural minute elements for affecting the flow of ink by the shape or dimension of an ink passage defined in these components, as described below.
A plurality of pressurizing chambers are defined between the grooves of the body, the base and the nozzle plate. The pressurizing chambers are connected to a flow-dividing chamber provided in the body, and ink supplied from an external ink-source flows through the flow-dividing chamber into the respective pressurizing chambers. The nozzle plate is provided with a plurality of nozzles, each of which opens to the respective one of the pressurizing chambers. Each of the heating elements is located at a position corresponding to the respective one pressurizing chamber. The heating element is energized to instantaneously heat the ink held in the corresponding pressurizing chamber, so that the ink is pressurized due to the thermal expansion thereof and thereby discharged through the nozzle aligned to the pressurizing chamber.
In this structure, when the ink held in each pressurizing chamber is pressurized by the energization of the corresponding heating element, some of the ink may flow back to the flow-dividing chamber. Accordingly, in the conventional, thermal-type ink jet printer or plotter, it is required to reduce the back flow of the ink from the pressurizing chambers, by optimizing the dimensions of the pressurized chambers and the nozzles as well as the positions of the heating elements, in order to obtain a sufficient pressure or discharging energy of the ink. The lack of ink discharging energy can make the discharged ink susceptible to an external force, and thereby the ink-discharging performance as well as the printing quality of the ink jet printer may be deteriorated. Further, the back flow of the ink from the pressurizing chambers may deteriorate the response of the ink discharging operation of the print head.
On the other hand, a piezoelectric-type print head of a conventional ink jet printer or plotter generally includes a body with a plurality of channels or grooves, a diaphragm secured to the body so as to cover the length of the grooves, a plurality of piezoelectric elements arranged on the reverse side of the diaphragm away from the grooves, and a nozzle plate fixed to the body adjacent to the longitudinal ends of the grooves. The body, the diaphragm and the nozzle plate are structural minute elements for affecting the flow of ink by the shape or dimension of an ink passage defined in these components, as described below.
The diaphragm is made of a flexible material, and a plurality of pressurizing chambers are defined between the diaphragm, the grooves of the body and the nozzle plate. The pressurizing chambers are connected to a flow-dividing chamber provided in the body, and ink supplied from an external ink-source flows through the flow-dividing chamber into the respective pressurizing chambers. The nozzle plate is provided with a plurality of nozzles, each of which opens to the respective one of the pressurizing chambers. Each of the piezoelectric elements is located at a position corresponding to the respective one pressurizing chamber along the reverse side of the diaphragm.
The piezoelectric element is excited to generate an electrostrictive effect, and thereby actuates or deforms a part of the diaphragm defining the corresponding one of the pressurizing chambers. As the part of the diaphragm is deformed to instantaneously reduce the volume of the corresponding pressurizing chamber, the ink held therein is pressurized and thereby discharged through the nozzle aligned to the pressurizing chamber. The piezoelectric elements are separated from each other and are fixedly supported on a base that, in turn, is securely assembled with the body, so as to eliminate any influence on the other parts of the diaphragm defining the other pressurizing chambers during an ink pressurizing operation.
The pressurizing chambers are normally connected to the flow-dividing chamber through restrictions or orifices provided also in the body. When the ink held in each pressurizing chamber is pressurized by the excitation of the corresponding piezoelectric element, the ink is substantially prevented from flowing back to the flow-dividing chamber due to large fluid resistance at the orifice, and thereby is discharged with a sufficient pressure through the nozzle.
The restrictions or orifices are designed and dimensioned to suitably control the ink flow inside the print head, so as to optimize the ink-discharging performance of the ink jet printer. In this respect, when the cross-sectional area of the restriction or orifice is further reduced and the fluid resistance thereof is further increased, the larger discharging energy of the ink from the pressurizing chamber through the nozzle is obtained. The increased discharging energy of the ink can make it hard for the discharged ink to be affected by an external force and, therefore, the ink-discharging performance as well as the printing quality of the ink jet printer can be improved.
However, the reduction of the cross-sectional area of the restriction or orifice also makes it difficult for the ink to flow from the flow-dividing chamber to the respective pressurizing chamber. As a result, ink may be insufficiently supplied into the respective pressurizing chambers or, otherwise, the time required for sufficiently supplying ink into each pressurizing chamber after the ink is discharged therefrom through the nozzle may be increased, which may deteriorate the response of the ink discharging operation of the print head. Accordingly, it is difficult for the conventional, piezoelectric-type ink jet printer or plotter to ensure both a high printing quality and a quick discharge response.
As another example of miniature or precision equipment including minute elements, in the field of hydro-pneumatic arts, a miniaturized pump unit for ensuring a high precision control of a fluid flow rate, used for, e.g., chemical-analysis or medical purposes, is known. A valveless-type, conventional miniaturized pump unit generally includes a body with a fluid-passage or channel, a diaphragm secured to the body so as to cover the length of the channel, and a plurality of piezoelectric elements arranged on the reverse side of the diaphragm away from the channel in a longitudinal array along the length of the channel. The body is a structural minute element for affecting the flow of fluid by the shape or dimension of a fluid passage defined in the body, as described below.
The channel of the body includes a plurality of expanded areas located in mutually spaced arrangement along the length of the channel. The diaphragm is made of a flexible material, and a plurality of pressure chambers are defined between the diaphragm and the expanded areas of the channel of the body. The channel opens the opposite sides of the body and is connected at respective open ends with an external fluid circuit. Each of the piezoelectric elements is located at a position corresponding to the respective one pressure chamber along the reverse side o
Citizen Watch Co. Ltd.
Nguyen Thinh
Stephens Juanita
LandOfFree
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