Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-01-15
2001-07-17
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06260963
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
This invention relates generally to an ink jet print head and, more specifically, to an ink jet print head that reduces deleterious print head vibration.
BACKGROUND OF THE INVENTION
A typical color ink jet print head includes an array of ink jets that are closely spaced from one another for use in ejecting drops of ink toward a receiving surface. The typical print head also has at least four ink manifolds for receiving the black, cyan, magenta and yellow ink used in monochrome plus subtractive color printing. The number of such manifolds may be varied where a printer is designed to print solely in black ink, gray scale or with less than a full range of color.
In a conventional ink jet print head, each ink jet is paired with an electromechanical transducer, such as a piezoelectric transducer (PZT). The transducer is bonded to the flexible diaphragm and typically has metal film layers to which an electronic transducer driver is electrically connected. When a voltage is applied across the metal film layers of the transducer, the transducer attempts to change its dimensions. Because it is rigidly attached to a flexible diaphragm, the transducer bends and deforms the diaphragm, thereby causing the outward flow of ink through the ink jet.
It has been discovered that firing multiple transducers simultaneously at particular frequencies can create a global mechanical vibration mode in the print head. For example, where the ink jet nozzles are arrayed horizontally in an extended rectangular formation across the print head (see FIG.
5
), firing multiple transducers at a particular frequency cam create a vertical vibration mode and bending about a horizontal axis A of the print head. A given print head may also have one or more resonance modes that correspond to a particular frequency or firing rate of the transducers/ink jets. As more transducers are actuated simultaneously at a resonant frequency, the magnitude of the mechanical vibration within the print head increases. This vibration may cause jets to become less efficient and slower in operating, especially in certain regions of the print head that are more sensitive to vibration. This reduction in jet efficiency can lead to ink drop position errors on the receiving surface and visible image artifacts, such as banding.
U.S. Pat. No. 5,781,212 to Burr et al. discloses a print head structure that controls acoustic or fluidic pressure waves in the ink flow passageways by utilizing a baffle structure to dampen the pressure waves within the passageways. U.S. Pat. No. 4,730,197 to Raman et al. teaches the use of compliance relief slots adjacent to a portion of a compliance plate that forms the bottoms of ink manifolds. The slots allow the compliance plate to flex in response to ink pressure changes and fluidic pressure waves in the manifolds. Neither of these print head structures addresses the problem of global mechanical vibrations created by simultaneously firing multiple ink jets.
Accordingly, a need exists for an improved ink jet print head that dampens global mechanical vibrations created by simultaneously firing multiple ink jets.
BRIEF SUMMARY OF THE INVENTION
It is an aspect of the present invention to provide a print head structure that dampens mechanical vibrations created by firing multiple ink jets within the print head.
It is a feature of the present invention to provide a print head structure that includes at least one vibration disruption chamber vertically spaced from an ink manifold.
It is another feature of the present invention that the vibration disruption chamber is positioned near regions in the print head that are susceptible to vibration.
It is yet another feature of the present invention that multiple, separate vibration disruption chambers may be utilized in the print head.
It is still another feature of the present invention that the dimensions and positioning of the vibration disruption chambers may be varied to control a particular resonance mode in a given print head.
It is an advantage of the present invention that the vibration disruption chambers dissipate energy within the print head.
It is another advantage of the present invention that the vibration disruption chambers allow the print head structure to operate at resonant frequencies.
Still other aspects of the present invention will become apparent to those skilled in this art from the following description, wherein there is shown and described a preferred embodiment of this invention by way of illustration of one of the modes best suited to carry out the invention. The invention is capable of other different embodiments and its details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. And now for a brief description of the drawings.
REFERENCES:
patent: 4730197 (1988-03-01), Raman et al.
patent: 5170177 (1992-12-01), Stanley et al.
patent: 5625393 (1997-04-01), Asai
patent: 5736993 (1998-04-01), Regimbal et al.
patent: 5781212 (1998-07-01), Burr et al.
patent: 5963234 (1999-10-01), Miyazawa et al.
Burr Ronald F.
Reistad Brett W.
Stephens Terrance L.
Le N.
Moore Charles F.
Ngiem Michael
Xerox Corporation
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