Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-12-14
2001-08-28
Yockey, David F. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S033000, C347S090000
Reexamination Certificate
active
06280014
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to a self-cleaning ink jet printer and methods for cleaning same and more particularly to a wiper blade assembly for an ink jet printer having a fixed canopy-type gutter.
BACKGROUND OF THE INVENTION
An ink jet printer produces images by ejecting ink droplets onto a receiver medium 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 mediums are largely responsible for the wide acceptance of ink jet printers in the marketplace.
“On demand” ink jet printers utilize a pressurization actuator to produce the ink jet droplet at orifices of a print head. In this regard, either one of two types of actuators may be used including heat actuators and piezoelectric actuators. With 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 possessing 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.
In the case of “continuous” ink jet printers, electrostatic charging tunnels are placed close to the point where ink droplets are being ejected in the form of a stream. Selected 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.
Recently a new type of continuous ink jet printer has been disclosed. U.S. patent applications bearing Ser. No. 08/954317, now U.S. Pat. No. 6,079,821, and Ser. No. 09/342,371 to Chwalek et al., which describe a continuous ink jet printer in which on demand asymmetric heating of an ink jet causes selected drops to deflect. In one mode of operation, selected drops are deflected toward an image-recording medium while the other drops are intercepted in a canopy-type gutter that is placed in close proximity (for example, 3 mm) to the ink jet nozzle plate.
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 nozzles 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 nozzles are exposed to many kinds of air born particulates. Particulate debris may accumulate on surfaces formed around the nozzles and may accumulate in the nozzles and chambers themselves. That is, the ink may combine with such particulate debris to form an interference burr that blocks the nozzle or that alters surface wetting to inhibit proper formation of the ink droplet. The particulate debris should be cleaned from the surface and nozzle 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 nozzle.
Thus, ink jet printers can be said to have the following problems: the inks tend to dry-out in and around the nozzles resulting in clogging of the nozzles; and the wiping of the nozzle plate causes wear on plate and wiper, the wiper itself producing particles that clog the nozzle. In addition, cleaning an ink jet nozzle plate that has limited accessibility due to the placement of a fixed gutter poses extra demands on the design of cleaning members and on methods used.
Ink jet print head cleaners are known. A wiping system for ink jet print heads is disclosed in U.S. Pat. No. 5,614,930 titled “Orthogonal Rotary Wiping System For Ink jet Printheads” issued Mar. 25, 1997 in the name of William S. Osborne et al. This patent discloses a rotary service station that has a wiper supporting tumbler. The tumbler rotates to wipe the print head along a length of linearly aligned nozzle. In addition, a wiper scraping system scrapes the wipers to clean the wipers. However, Osborne et al. do not disclose use of an external solvent to assist cleaning and also does not disclose complete removal of the external solvent. Also a wiper scraping system is limited by the size constraints imposed by the print head itself. This is particularly true for fixed gutter ink jet print head systems which partially encloses the print head surfaces. Fixed gutter systems require a mechanism that can work within small tolerances imposed by the integrated gutter in order to clean the print head.
Therefore, there is a need to provide a suitable ink jet printer with cleaning mechanism, and method of assembling same, which cleaning mechanism is capable of cleaning the print head surface. There is also a need to supply cleaning liquid to lubricate and aid cleaning in a manner that does not cause wear of the print head nozzle plate. Furthermore there is a need for a mechanism that can operate within the small tolerances imposed by an fixed canopy-type gutter.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a self-cleaning ink jet printer with a cleaning mechanism and method of assembling same, which cleans a surface of a print head belonging to the printer.
It is another object of the present invention to provide an ink jet print head assembly that includes a cleaning mechanism and method of assembling same that can be used in fixed gutter continuous ink jet printers.
With the above objects in view, disclosed is a wiper blade assembly for use in a self-cleaning printer, the printer comprising a print head having a print head surface and an ink channel therein; a structural member that functions as a gutter for collecting ink is disposed opposite to the print head surface; the cleaning mechanism adapted to simultaneously clean contaminant from the print head surface.
According to an exemplary embodiment of the present invention, disclosed is a self-cleaning printer comprising a print head defining a plurality of ink channels therein, each ink channel terminating in a nozzle. The print head also has a surface thereon surrounding all the nozzles. The print head is capable of jetting ink through the nozzles, which ink jets are subsequently heated to cause drops to form and to selectively deviate drops for printing. Ink drops are either intercepted by a receiver or a gutter. In one method of operation, ink is selectively deflected onto a receiver (e.g., paper or transparency) supported by a platen disposed adjacent the print head, while the non-deflected ink drops are intercepted by the gutter. Ink intercepted by the gutter may be recycled. Contaminant such as an oily film-like deposit or particulate matter may reside on the surface and may completely or partially obstruct the nozzle. 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 nozzles and therefore may give rise to undesirable image artifacts, such as banding. It is therefore desirable to clean the contaminant from the surface and the nozzles.
Therefore, a cleaning mechanism is disposed relative to
Faisst, Jr. Charles F.
Griffin Todd R.
Sharma Ravi
Eastman Kodak Company
Stevens Walter S.
Yockey David F.
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