Self-cleaning ink printing printer with gutter cleaning structure and method of assembling the printer

Abstract: Self-cleaning ink printing printer with gutter cleaning structure and method of assembling the printer. The printer includes a print head (10) having a surface (14) thereon, the surface (14) including an orifice region (18) having at least one ink-ejection orifice (16), a first gutter (22) disposed proximate one side of the orifice region (18) adapted for connection to a source of a cleaning fluid (26), and a second gutter (24) disposed proximate an opposite side of the orifice region (18) adapted for connection to a receiver for the cleaning fluid. A cover member (40) is positionable opposite the orifice region (18) and the gutters (22,24) for forming a sealed enclosure (42) thereof defining a cavity (44) sized to allow fluid flow therethrough from the first gutter (22) over the orifice region (18) to the second gutter (24). A pump (36) is provided, preferably integrally formed in the print head (10), and connected to the gutters (22, 24) through channels (28, 30, 32, 34) in the print head (10) substrate for the circulation of the cleaning fluid. A filter (38) can also be provided between one of the gutters (22, 24) and the pump (36) for removing contaminants from the cleaning fluid. A source of acoustic energy (54) can also be provided for exciting the cleaning fluid as the cleaning fluid flows through the cavity (44) for facilitating the cleaning action.

Description: This invention generally relates to ink jet printer apparatus and methods and more particularly relates to a self-cleaning ink printing printer including a gutter cleaning structure for directing cleaning fluid over a surface of a print head and ink-ejecting orifices thereon and collecting the fluid and contaminants contained therein, and also relates to a 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 possesses 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. Patent 4,970,535 titled "Ink Jet Print Head Face Cleaner" issued November 13, 1990, in the name of James C. Oswald. This patent discloses an ink 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 clean the print head face in a manner that leaves printing speed unaffected by the cleaning operation. European patent application number EP 1016532 discloses an ink jet cartridge for an inkjet printer. The cartridge includes an orifice plate having a plurality of orifices for ink ejection and a reservoir having ink which is adapted to be ejected through the orifices. The cartridge also includes a cleaning manifold having a plurality of inlet and outlet passages through which cleaning fluid can be applied so that such fluid is directed across the surface of the orifice plate and a plurality of actuable ultrasonic transducers disposed in operative relationship with respect to the orifice plate. When actuated, the ultrasonic transducers produce ultrasonic sound waves which impinge upon the orifice plate to loosen debris that is carried away by the cleaning fluid directed across the surface of the orifice plate. However, European patent application number EP 1016532 is not relevant when assessing inventive step. European patent application number EP 0749836 discloses a microclimate enriched by solvent vapors produced in an antechamber. The antechamber is formed by the ink print head being set back in relation to the front wall of the housing. In the front wall opposite the nozzles, openings are made whose width is larger than the diameter of a nozzle opening. The antechamber has a trough-shaped area for the inlet and outlet of solvent by capillary action, and a non-capillary area for the solvent vapors. A seal bonnet is provided for sealing during longer print pauses and cleaning processes. Japanese publication number 58096563 discloses a printhead including a nozzle plate having a plurality of nozzles. When one of the nozzles is clogged, an ultrasonic wave vibrator is operated to develop ultrasonic wave vibration in a nozzle plate 24 for freeing the nozzles 4 and 5 of dirt and debris. At the same time, a clogging removal solution is made to flow into the vicinity of the nozzles to flush dirt and debris into an ink discharge tank. Therefore, an object of the present invention is to provide a self-cleaning printer which provides effective cleaning without limitations relating to print head surface wear, ink contact, or complex cleaning station apparatus, and a method of assembling the printer. With this object in view, the present invention is defined by the several claims appended hereto. According to an exemplary embodiment of the present invention, a self-cleaning ink printing printer comprises a print head defining a plurality of ink channels therein, each ink channel terminating in an ink-ejection orifice. The print head also has a surface thereon including an orifice region surrounding all of the orifices. The print head is capable of ejecting ink droplets through the orifices, which ink droplets are intercepted by a receiver (e.g., paper or transparency) supported by a platen roller disposed adjacent the print head. Contaminants 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, according to the exemplary embodiment of the invention, a first gutter is disposed proximate one side of the orifice and is adapted for connection to a source of cleaning fluid. A second gutter is disposed proximate on opposite side of the orifice and is adapted for connection to a receiver for the cleaning fluid. A cover member is positionable opposite the orifice region and cutters for forming a sealed enclosure thereover. The enclosure defines a cavity sized to allow fluid flow therethrough from the first gutter over the orifice region to the second gutter, so as to remove the contaminant from the surface and/or orifice. A feature of the present invention is the provision of a first gutter disposed proximate one side of the orifice region adapted for connection to a source of cleaning fluid, and a second gutter disposed proximate an opposite side of the orifice region adapted for connection to a receiver for the cleaning fluid. Another feature of the present invention is the provision of a cover member disposed opposite the orifice region and the gutters for forming a sealed enclosure thereover defining a cavity for the flow of cleaning fluid from the first gutter over the orifice region to the second gutter for removing contaminants from the surface and/or orifices. Another feature of the present invention is the provision of a pump integrally formed in the print head connected to the gutters through fluid flow channels in the print head substrate for the circulation of the cleaning fluid. A filter can also be provided between one of the gutters and the pump for removing contaminants. Another feature of the present invention is the provision of a source of acoustic energy disposed on the cover member for exciting the cleaning fluid as the cleaning fluid flows through the cavity for facilitating the cleaning action. As an advantage of the present invention, the gutters and channels for the cleaning fluid are incorporated into the print head, and close alignment of the cover member with the print head is not required, thus avoiding the need for complex cleaning station apparatus. As another advantage, the cleaning is accomplished without contacting the surface within the orifice region, thus avoiding potential damage to delicate aspects of the print head, such as exposed heaters and the like. According to the invention, any liquid that does not significantly damage the print head can be used as a cleaning fluid. For example, water, isopropanol, diethylene glycol, diethylene glycol monobutyl ether, octane, acids and bases, surfactant solutions and any combination thereof may be used as cleaning fluids. Complex fluids such as microemulsions, micellar surfactant solutions, vesicles and solid particles dispersed in liquids may also be used as cleaning fluids. These and other objects, features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there are shown and described illustrative embodiments of the invention. While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of the present invention, it is believed the invention will be better understood from the following detailed description when taken in conjunction with the accompanying drawings wherein: Figure 1 is a schematic front view of a self-cleaning print head according to the present invention; and Figure 2 is a sectional view of the print head taken along line 2-2 of Figure 1, showing a cover member of the present invention operatively positioned thereover. The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. Therefore, referring to Fig. 1, an ink jet print head 10 includes a body 12 of a semiconductor material, such as, but not limited to, CMOS material. Body 12 has a front surface 14 including a plurality of ink-ejection orifices 16 therein arranged in a linear array generally defining the peripheral boundaries of an elongate orifice region 18. Referring also to Fig. 2, each ink-ejection orifice 16 extends from surface 14 through the substrate thereof to a respective ink channel 20 connected in fluid communication to a supply of ink, not shown. Print head 10 is conventionally operable to selectively eject ink contained in respective ink channels 20 through the ink-ejection orifices 16 onto a receiver such as a paper or transparency disposed opposite the orifice 16, for instance, using heating elements (not shown) located in front surface 14 which are energized to heat the ink to generate a vapor bubble. Front surface 14 of print head 10 additionally includes a first elongate gutter 22 disposed proximate one side of orifice region 18, and an elongate second gutter 24 disposed proximate a second side of orifice region 18 opposite the first side thereof. First gutter 22 is connected in fluid communication with a source of cleaning fluid 26 via a plurality of connecting channels 28 communicating with a supply channel 30 extending through the substrate of body 12 from source 26. Second gutter 24 communicates with source 26 through a plurality of connecting channels 32 in communication with a return channel 34 extending through the substrate of body 12 to source 26. Source 26 preferably includes a microfluidic pump 36 micro machined in body 12 of print head 10, a filter 38 disposed in return channel 34 for filtering fluid flow therethrough and an optional fluid reservoir (not shown) in connection with channel 34 for supplying cleaning fluid to pump 36. Pump 36 is operable to suction or scavenge cleaning fluid from return channel 34 and pump the fluid through supply channel 30 and connecting channels 38 into first gutter 22. Fig. 2 represents a section through body 12 of print head 10 along section line 2-2 in Fig. 1. Fig. 2 shows a cover member 40 positioned opposite orifice region 18 and first and second gutters 22 and 24 of surface 14 of print head 10, forming an enclosure 42 defining a cavity 44 over orifice region 18 and first and second gutters 22 and 24. Cover member 40 includes a peripheral edge 46 sealably engageable with an elastomeric seal member 48 mounted in a groove 50 extending circumferentially around orifice region 18 and first and second gutters 22 and 24 thereby sealing cavity 44. When so sealed, cavity 44 forms an enclosed path for the flow of the cleaning fluid from first gutter 22 over orifice region 18 and ink-ejection orifices 16 to second gutter 24, as denoted by arrow 52, for dislodging and/or dissolving dried ink, particulate matter, and other contaminants from orifice region 18 and orifices 16. The cleaning fluid and ink and other contaminants then flows from second gutter 24 through connecting channels 32 and return channel 34 to filter 38, which removes the contaminants. The cleaning fluid can then pass through the remainder of return channel 34 to pump 36 for recirculation to first gutter 22. To facilitate the cleaning action, a source of acoustic energy 54 can be provided adjacent cavity 44 for exciting the cleaning fluid as it flows therethrough. Preferably, source of acoustic energy 54 includes an ultrasonic transducer 56 mounted atop or on cover member 40 as shown, and is energizable and operable in a suitable conventional manner. The cleaning fluid may be any suitable liquid solvent composition, such as water, isopropanol, diethylene glycol, diethylene glycol monobutyl ether, octane, acids and bases, surfactant solutions and any combination thereof. Complex fluids such as microemulsions, micellar surfactant solutions, vesicles and solid particles dispersed in liquid may also be used. It may be appreciated from the description hereinabove, that cover member 40 may be separated from print head 10 while print head 10 is in a printing mode, wherein ink is selectively ejected through orifices 16 onto a recording medium, such as paper, transparencies, or the like in the usual manner. When print head 10 is not in a printing mode, cover member 40 can be brought into sealed engagement with elastomeric seal member 48 to sealably enclose orifice region 18 and gutters 22 and 24, to provide a moist environment to delay or retard drying of ink thereon, and to prevent the collection of air born particulates such as dust, fibrous material from paper and the like from collecting within orifice region 18 and contaminating same. Pump 36 can then be energized using a suitable power source for pumping the cleaning fluid into first gutter 22 and over orifice region 18 and ink-ejection orifices 16 to second gutter 24, for cleaning any ink and other contaminants therefrom. It may be appreciated from the description hereinabove, that another advantage of the present invention is that effective cleaning of orifice region 18 and orifices 16 can be accomplished using the present apparatus without the requirement of a complex cleaning station apparatus, or the requirement of close alignment thereof with print head 10 to effect the cleaning operation. This enables greatly simplifying the cleaning apparatus and increasing the cleaning efficiency. While the invention has been described with particular reference to its preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements of the preferred embodiment without departing from the invention. In addition, many modifications may be made to adapt a particular situation and material to a teaching of the present invention without departing from the essential teachings of the invention. For example, print head 10 may be of a piezoelectric or other well known conventional construction as explained herein as background and elsewhere. As another example, elastomeric seal member 48 may be alternatively located on peripheral edge 46 of cover member 40, and cover member 40 may be alternatively constructed to accommodate same. Therefore, what is provided is a self-cleaning ink printing printer with gutter cleaning structure and method of assembling the printer.

Claims: A self-cleaning ink printing printer comprising: (a) a print head (10) having a surface (14) thereon, the surface including an orifice region (18) having at least one ink-ejection orifice (16), a first gutter (22) disposed proximate one side of the orifice region adapted for connection to a source of a cleaning fluid (26), and a second gutter (24) disposed proximate an opposite side of the orifice region adapted for connection to a receiver for the cleaning fluid; and (b) a cover member (40) positionable opposite the orifice region and the gutters for forming a sealed enclosure (42) thereover defining a cavity (44) sized to allow fluid flow therethrough from the first gutter over the orifice region to the second gutter; characterized by a source of acoustic energy (54) being disposed on the cover member for exciting the cleaning fluid in the sealed enclosure. The self-cleaning ink printing printer of claim 1, wherein said gutters are attached to the print head. The self-cleaning ink printing printer of claim 1, wherein the print head includes a pump (36) having an outlet connected in fluid communication with the first gutter for delivering the cleaning fluid thereto. The self-cleaning ink printing printer of claim 3, wherein the pump has an inlet connected in fluid communication with the second gutter for receiving the cleaning fluid therefrom. The self-cleaning ink printing printer of claim 4, further comprising a filter (38) disposed between the pump and one of the gutters for removing contaminants from the cleaning fluid. The self-cleaning ink printing printer of claim 4, wherein the print head includes integral channels (28, 30, 32, 34) connecting the pump with the first and second gutters. The self-cleaning ink printing printer of claim 1, wherein the print head includes a seal member (48) extending around the gutters and the orifice region adapted for engaging the cover member for forming the sealed enclosure. The self-cleaning ink printing printer of claim 1, wherein the source of acoustic energy comprises an ultrasonic transducer (56). A method of assembling a self-cleaning ink printing printer, comprising the steps of: (a) providing a print head, the print head having a surface defining at least one ink ejection orifice therethrough, the at least one ink ejection orifice being susceptible to obstruction by contaminants, a first gutter disposed in the surface proximate a first side of the at least one ink ejection orifice, and a second gutter disposed in the surface proximate a second side of the at least one ink ejection orifice opposite the first side, the first gutter being connected to a source of a cleaning fluid and the second gutter being connected to a receiver for the cleaning fluid; (b) providing a removeable cover member corresponding in size and shape to a region of the surface including the at least one orifice, the first gutter and the second gutter, the cover member including a source of acoustic energy on the cover member for exciting the cleaning fluid when flowing from the first gutter to the second gutter; and (c) positioning the cover member opposite the region in sealed relation to the surface around the region defining a cavity therebetween for flow of the cleaning fluid from the first gutter over the at least one orifice to the second gutter. The method of claim 9, wherein the source of the cleaning fluid includes a pump. The method of claim 10, wherein the source of the cleaning fluid further includes a filter. The method of claim 9, wherein the surface of the print head further includes a seal member extending around the at least one orifice, the first gutter and the second gutter for forming the sealed condition with the cover member.

Inventors: CHWALEK JAMES M, DEBESIS JOHN R, HAWKINS GILBERT A, CHWALEK, JAMES M., DEBESIS, JOHN R., HAWKINS, GILBERT A.
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 2000
Main classification: B41J2
IPC codes: B41J2, B41J29