Incremental printing of symbolic information – Ink jet – Ejector mechanism
Utility Patent
1998-12-29
2001-01-02
Le, N. (Department: 2863)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S027000, C347S025000
Utility Patent
active
06168256
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to ink jet printer apparatus and methods and more particularly relates to a self-cleaning ink jet printer with oscillating septum and method of assembling the printer.
An ink jet printer produces images on a receiver by ejecting ink droplets onto the receiver in an imagewise fashion. The advantages of non-impact, low-noise, low energy use, and low cost operation in addition to the capability of the printer to print on plain paper are largely responsible for the wide acceptance of ink jet printers in the marketplace.
In this regard, “continuous” ink jet printers utilize electrostatic charging tunnels that are placed close to the point where ink droplets are being ejected in the form of a stream. Selected ones of the droplets are electrically charged by the charging tunnels. The charged droplets are deflected downstream by the presence of deflector plates that have a predetermined electric potential difference between them. A gutter may be used to intercept the charged droplets, while the uncharged droplets are free to strike the recording medium.
In the case of “on demand” ink jet printers, at every orifice a pressurization actuator is used to produce the ink jet droplet. In this regard, either one of two types of actuators may be used. These two types of actuators are heat actuators and piezoelectric actuators. With respect to heat actuators, a heater placed at a convenient location heats the ink and a quantity of the ink will phase change into a gaseous steam bubble and raise the internal ink pressure sufficiently for an ink droplet to be expelled to the recording medium. With respect to piezoelectric actuators. A piezoelectric material is used, which piezoelectric material possess piezoelectric properties such that an electric field is produced when a mechanical stress is applied. The converse also holds true; that is, an applied electric field will produce a mechanical stress in the material. Some naturally occurring materials possessing these characteristics are quartz and tourmaline. The most commonly produced piezoelectric ceramics are lead zirconate titanate, barium titanate, lead titanate, and lead metaniobate.
Inks for high speed ink jet printers, whether of the “continuous” or “piezoelectric” type, must have a number of special characteristics. For example, the ink should incorporate a nondrying characteristic, so that drying of ink in the ink ejection chamber is hindered or slowed to such a state that by occasional spitting of ink droplets, the cavities and corresponding orifices are kept open. The addition of glycol facilitates free flow of ink through the ink jet chamber. Of course, the ink jet print head is exposed to the environment where the ink jet printing occurs. Thus, the previously mentioned orifices are exposed to many kinds of air born particulates. Particulate debris may accumulate on surfaces formed around the orifices and may accumulate in the orifices and chambers themselves. That is, the ink may combine with such particulate debris to form an interference burr that blocks the orifice or that alters surface wetting to inhibit proper formation of the ink droplet. The particulate debris should be cleaned from the surface and orifice to restore proper droplet formation. In the prior art, this cleaning is commonly accomplished by brushing, wiping, spraying, vacuum suction, and/or spitting of ink through the orifice.
Thus, inks used in ink jet printers can be said to have the following problems: the inks tend to dry-out in and around the orifices resulting in clogging of the orifices; and the wiping of the orifice plate causes wear on plate and wiper, the wiper itself producing particles that clog the orifice.
Ink jet print head cleaners are known. An ink jet print head cleaner is disclosed in U.S. Pat. No. 4,970,535 titled “Ink Jet Print Head Face Cleaner” issued Nov. 13, 1990, in the name of James C. Oswald. This patent discloses an in jet print head face cleaner that provides a controlled air passageway through an enclosure formed against the print head face. Air is directed through an inlet into a cavity in the enclosure. The air that enters the cavity is directed past ink jet apertures on the head face and then out an outlet. A vacuum source is attached to the outlet to create a subatmospheric pressure in the cavity. A collection chamber and removable drawer are positioned below the outlet to facilitate disposal of removed ink. Although the Oswald patent does not disclose use of brushes or wipers, the Oswald patent also does not reference use of a liquid solvent to remove the ink; rather, the Oswald technique uses heated air to remove the ink. However, use of heated air is less effective for cleaning than use of a liquid solvent. Also, use of heated air may damage fragile electronic circuitry that may be present on the print head face. Moreover, the Oswald patent does not appear to disclose “to-and-fro” movement of air streams or liquid solvent across the head face, which to-and-fro movement might otherwise enhance cleaning effectiveness.
Therefore, there is a need to provide a self-cleaning printer with oscillating septum and method of assembling the printer.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a self-cleaning printer with oscillating septum and method of assembling the printer, which oscillating septum enhances cleaning effectiveness.
With the above object in view, the present invention resides in a self-cleaning printer, comprising a print head having a surface thereon; and an ocsillatable structural member disposed opposite the surface for defining a gap therebetween sized to allow a flow of fluid in a first direction through the gap, said member accelerating the flow of fluid to induce a shearing force in the flow of fluid while the member oscillates, whereby the shearing force acts against the surface while the shearing force is induced in the flow of fluid and whereby the surface is cleaned while the shearing force acts against the surface.
According to an exemplary embodiment of the present invention, the self-cleaning printer comprises a print head defining a plurality of ink channels therein, each ink channel terminating in an orifice. The print head also has a surface thereon surrounding all the orifices. The print head is capable of ejecting ink droplets through the orifice, which ink droplets are intercepted by a receiver (e.g., paper or transparency) supported by a platen roller disposed adjacent the print head. Contaminant such as an oily film-like deposit or particulate matter may reside on the surface and may completely or partially obstruct the orifice. The oily film may, for example, be grease and the particulate matter may be particles of dirt, dust, metal and/or encrustations of dried ink. Presence of the contaminant interferes with proper ejection of the ink droplets from their respective orifices and therefore may give rise to undesirable image artifacts, such as banding. It is therefore desirable to clean the contaminant from the surface.
Therefore, a cleaning assembly is disposed relative to the surface and/or orifice for directing a flow of fluid along the surface and/or across the orifice to clean the contaminant from the surface and/or orifice. The cleaning assembly includes an oscillating septum disposed opposite the surface and/or orifice for defining a gap therebetween. The gap is sized to allow the flow of fluid through the gap. Presence of the oscillating septum accelerates the flow of fluid in the gap to induce a hydrodynamic shearing force in the fluid. This shearing force acts against the particulate matter and cleans the particulate matter from the surface and/or orifice. A pump in fluid communication with the gap is also provided for pumping the fluid through the gap. In addition, a filter is provided to filter the particulate mater from the fluid for later disposal.
A feature of the present invention is the provision of an oscillating septum disposed opposite the surface and/or orifice for defining a gap therebetw
Bier Klaus-Dieter
Delametter Christopher N.
Meichle Michael E.
Quenin John A.
Sharma Ravi
Eastman Kodak Company
Hsieh Shih-Wen
Le N.
Stevens Walter S.
LandOfFree
Self-cleaning ink jet printer with oscillating septum and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-cleaning ink jet printer with oscillating septum and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-cleaning ink jet printer with oscillating septum and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2456814