Patent Grant
7669960
This invention relates to techniques for servicing ink-jet printing systems.
The subject invention generally relates to ink jet printing, and more particularly to thin film ink jet printheads for ink jet cartridges and methods for manufacturing such printheads.
The art of ink jet printing is relatively well developed. Commercial products such as computer printers, graphics plotters, and facsimile machines have been implemented with ink jet technology for producing printed media. The contributions of Hewlett-Packard Company to ink jet technology are described, for example, in various articles in the Hewlett-Packard Journal, Vol. 36, No. 5 (May 1985); Vol. 39, No. 5 (October 1988); Vol. 43, No. 4 (August 1992); Vol. 43, No. 6 (December 1992); and Vol. 45, No. 1 (February 1994); all incorporated herein by reference.
Generally, an ink jet image is formed pursuant to precise placement on a print medium of ink drops emitted by an ink drop generating device known as an ink jet printhead. Typically, an ink jet printhead is supported on a movable carriage that traverses over the surface of the print medium and is controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to a pattern of pixels of the image being printed.
A typical type of ink jet printhead includes an array of precisely formed nozzles in an orifice plate that is attached to an ink barrier layer, which in turn is attached to a thin film substructure that implements ink firing heater resistors and apparatus for enabling the resistors. The ink barrier layer defines ink channels including ink chambers disposed over associated ink firing resistors, and the nozzles in the orifice plate are aligned with associated ink chambers. Ink drop generator regions are formed by the ink chambers and portions of the thin film substructure and the orifice plate that are adjacent to the ink chambers.
One weakness of inkjet technology is that nozzles or ink injectors can sometimes fail, leaving some areas of the image unpainted, thus eliminating information on the image, which can result in aesthetical problems or uncompleted information on the image.
Ink-jet printheads are typically serviced to minimize these problems. Often, however, reliability problems of new ink injectors appear or become known when the product is already on the market. This can be a problem, as the servicing and printer design has been fine tuned only for known problems.
In the past when a printhead reliability problem appeared, a typical methodology for addressing a problem on the printhead included understanding and fixing the problem on the printhead, and implementing the printhead fix in subsequently manufactured printheads. Users would replace the existing printheads with the reliability problem with the new printheads after failure or replacement in the normal course of usage.
Sometimes, a code change on the machine can help solve reliability problems. In this case, the code change is implemented in the code of newly manufactured machines, and the revised code can be posted on the manufacturer's internet web site for downloading by affected users.
For a problem on a printer mechanism or printer firmware, several techniques have been employed. If the problem solution involves changes in mechanical parts, the solution is implemented on new production machines. For some large problems, the parts on existing machines can be replaced with new parts.
If the problem can be fixed with a printer's code change, the code change is implemented on newly fabricated machines and users can be advised to change the code on the existing printers.
Sometimes a process can help fix the problem. In this case, the fixing procedure can be communicated to the users and some tools sent to the users. For example, a printing system may have a paper pick problem, and a tool kit having an emery board for roughing up a pick roller and an instruction sheet can be furnished to the user.
In accordance with one aspect of the invention, a method is described for servicing an inkjet printhead on an inkjet printer including a first service module. One embodiment of the method includes:
The method can further include the steps of removing the first service module from the printer, installing the second service module in the printer, and, using the set of instructions, conducting a special printhead-related servicing operation. After completion of the special printhead-related servicing operation, the second service module can be removed from the printer, and the first service module re-installed in the printer in place of the second module.
Having a special service module that the user can fit in the machine could help solve many of the problems unseen during the development phase of a printing system.
These and other features and advantages of the present invention will become more apparent from the following detailed description of an exemplary embodiment thereof, as illustrated in the accompanying drawings, in which:
An exemplary embodiment of this invention will be described with respect to a large format inkjet printer, which includes a printhead cleaner. An exemplary swath plotter/printer is described in U.S. Pat. No. 6,076,920, the entire contents of which are incorporated herein by this reference. The following description of
The printer 50 has four ink-jet print cartridges 70, 72, 74, and 76 that store ink of different colors, e.g., black, yellow, magenta and cyan ink, respectively, in internal spring-bag reservoirs. As the carriage assembly 60 translates relative to the medium along the y axis, selected nozzles in the ink-jet cartridges are activated and ink is applied to the medium.
The carriage assembly 60 positions the print cartridges 70-76, and holds the circuitry required for interface to the heater circuits in the cartridges. The carriage assembly includes a carriage 62 adapted for the reciprocal motion on the front and rear sliders 92A, 92B. The cartridges are secured in a closely packed arrangement, and may each be selectively removed from the carriage for replacement with a fresh pen. The carriage includes a pair of opposed side walls, and spaced short interior walls, which define cartridge compartments. The carriage walls are fabricated of a rigid engineering plastic. The print heads of the cartridges are exposed through openings in the cartridge compartments facing the print medium.
As mentioned above, full color printing and plotting requires that the colors from the individual cartridges be applied to the media. This causes depletion of ink from the internal cartridge reservoirs. The printer 50 includes four take-a-gulp ink delivery systems (IDSs) to meet the ink delivery demands of the printing system. Each IDS includes three components, an off-carriage ink reservoir, an on-carriage print cartridge, and a print head cleaner. The ink reservoir includes a bag, holding 370 ml of ink for this exemplary embodiment, with a short tube and refill valve attached. Details of a ink reservoir bag structure suitable for the purpose are given in application Ser. No. 08/805,860, SPACE-EFFICIENT ENCLOSURE SHAPE FOR NESTING TOGETHER A PLURALITY OF REPLACEABLE INK SUPPLY BAGS, now U.S. Pat. No. 6,030,073, by Erich Coiner et al. These reservoirs are fitted on the left-hand side of the printer (behind the door of the left housing 58) and the valves attach to a valve holder arm 170, also behind the left door, as will be described below. The print cartridge in this exemplary embodiment includes a 300-nozzle, 600 dpi printhead, with an orifice through which it is refilled. The head cleaner (not shown) includes a spittoon for catching ink used when servicing and calibrating the printheads, a wiper used to wipe the face of the printhead, and a cap (used to protect the printhead when it is not in use). These three components together comprise the IDS for a given color and are replaced as a set by the user.
The proper location of each component is preferably identified by color. Matching the color on the replaced component with that on the frame that accepts that component will ensure the proper location of that component. All three components will be in the same order, with, in an exemplary embodiment, the yellow component to the far left, the cyan component in the center-left position, the magenta component in the center-right position and the black component in the far-right position.
The ink delivery systems are take-a-gulp ink refill systems. The system refills all four print cartridges 70-76 simultaneously when any one of the print cartridge internal reservoir's ink volume has dropped below a threshold value. A refill sequence is initiated immediately after completion of the print that caused the print cartridge reservoir ink volume to drop below the threshold and thus a print should never be interrupted for refilling (except when doing a long-axis print that uses more than 15.5 ccs of ink of any color).
A narrow replaceable service station module 230 for each color ink is an important part of the IDS. Referring to
A spring-loaded datum system provides for the printhead cleaner 230 to be easily but precisely positioned in the service station carriage 251. Along a top portion of each slot 244, 246, 248, 250 is a z-datum ridge 252 which engages a corresponding datum ledge 254 along both sides of the module. An upwardly biased spring arm 260 assures a tight fit along those datum surfaces. A horizontal positioning is provided in each slot by a pair of protruding corners which act as latches against matching stops 258 on the module. Although not required, a biasing arm 262 may be employed in a rear wall of each slot.
The printer is configured to position the printhead carriage at the service area for performing service functions on the printheads by the service modules, and to provide relative motion between the printheads and the service modules to carry out the service functions. Mechanisms for accomplishing the relative movement are known in the art. Exemplary techniques are described in U.S. Pat. Nos. 6,135,585; 5,984,450; and 6,155,667, the entire contents of which are incorporated herein by this reference.
In accordance with one aspect of the invention, the design of a service station module for a fielded printer, e.g. printhead cleaner 230, is modified to adapt it to new failure modes. The modified service station module is then sent to the printer user, together with a printer's code procedure to activate the new module (sequence of printer commands that will adapt the printer service routines to make use of the new service station module).
This special service module will typically be targeted to address printhead problems that are infrequently seen, including a problem that only affects a small percentage of users, or a problem that affects a user only very occasionally.
In accordance with an aspect of the invention, to address newly discovered reliability problems, an exemplary process to be followed includes the following steps.
1. Identify the new reliability issue.
2. If a special service module solution is feasible, design and manufacture a new service module addressing the new issue.
3. Design a set of instructions for the printer and a user procedure for the new service.
4. Send a package with the special service module, the printer instructions (code) and the user instructions to the user, e.g. at the user's record address, e.g. at home or a business establishment.
Once the user receives this package, he or she can then follow the following exemplary procedure.
5. Remove the standard or normal service modules from the printer.
6. Install the new special service modules.
7. Download the printer instruction code from a computer connected to the printer, so the special service process starts.
8. Wait until completion of the special service process.
9. Remove the special service modules from the printer, and re-install the removed, standard service modules.
The special service modules can implement solutions that were not feasible on the normal service modules for several possible reasons. For example, there may be no more space available on the normal service module for a special cleaning tool, since the standard service module typically includes a cap, wiper and spittoon. The special service module need not include all these devices, and so considerable space is available for new devices. Another reason is that of cost, since the new solutions can incorporate more expensive mechanisms or tools, as they will be used much less often. Moreover, since the special service module will be used only infrequently, throughput concerns are not a significant issue, as the special service module is to be used only in special times. Thus, the special service process using the special service module can last much longer than the process using the normal printhead cleaner. Another issue which is less significant is reliability; some solutions would not be suitable for the normal service modules because of the hard working conditions of the service modules. Special service modules would not be exposed to these conditions, such as the number of cycles, aerosol, time in printer, transportation, usability, vibration and the like.
Thus, a much broader range of choices are available to design a special service module targeted to very specific user problems.
The use of a special service module in accordance with aspects of this invention can provide significant benefits for the user. With one special intervention, for example, using a special service module, the user can save one or more printheads which would otherwise be discarded, saving the user money while improving or maintaining print quality. Since the printheads in common use now are long-life, the savings are more relevant.
Some examples of these special service modules are now described. One problem which might arise is the degradation in print quality from fiber tracks on the print medium, resulting from fibers landing on the pen, typically the nozzle array and surrounding area. A special service module can be designed, which includes a brush to remove the fibers from the pens. An exemplary special service module 230A is shown in the simplified side view of
Another problem which can be addressed by a special service module is that of ink on the carriage electrical interconnect, i.e. the electrical contacts on the printer carriage which make contact with the corresponding electrical contacts on the printhead when it is installed in the carriage stall. A special service module can be provided with a special wiper brush that cleans the ink from the carriage interconnect. Such a brush 230A2 is illustrated in
Another potential problem is that of ink accumulation on the printhead nozzle plate. A special service module can be designed with a fluid, e.g. including water or alcohol, on an applicator tip such as a resilient foam structure or a textile wiper, to absorb the ink accumulation during a special cleaning mode operation.
An alternate solution to the problem of ink accumulation on the printhead is to provide a service module with a special ultra cleaning wiper made of silicon, or textile, or a special rubber.
Another problem is that of global deprime/starvation of the printhead nozzle array. To address this problem, a special service module can be provided with a negative pressure primer that is more effective against these particular issues.
There can also be shipping problems including excessive vibration or shock which can affect the printhead, e.g. where the user ships or moves the printer. These can be minimized by providing a special service module 230E with a special cap structure 230E1, as shown in
In the example of the special service module 230E, and even for the special service modules illustrated in
Another feature which can be incorporated into the special service module 230E is a locking feature such as tab 230E8 which enters a corresponding feature in the printhead carriage as the service module is raised to the position shown in
In the foregoing examples of special service modules illustrated in
It is understood that the above-described embodiments are merely illustrative of the possible specific embodiments which may represent principles of the present invention. Other arrangements may readily be devised in accordance with these principles by those skilled in the art without departing from the scope and spirit of the invention.
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| 20020101470 A1 | Aug 2002 | US |
