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1. Field of the Disclosure
The present disclosure relates generally to media feed systems used in inkjet imaging devices such as inkjet printers or multifunction devices having printing capability and more particularly to a media feed system having a star wheel with adjustable bias.
2. Description of the Related Art
In inkjet imaging device media feed systems, it is now common practice to advance media by pinching the media between a driven media feed roll and one or more star wheels. In simplex printing, the media feed roll touches the non-printed back side of the media and the star wheels touch the printed front side. Star wheels minimize contact with wet ink by minimizing the points of contact with the media. This reduces smearing and other print defects.
In a typical media feed system, star wheels are supported by springs. The springs provide a bias directed toward the media feed rolls. This bias is not adjustable during operation and is not adjusted to optimize the media feed system in response to, for example, different media properties. Also, since the star wheels continuously ride on either media or on rolls, the star wheels may experience excessive wear over the life of the imaging device, especially if the roll is abrasive. Further, the star wheels may become contaminated with ink buildup if they have excessive contact with wet ink. Once contaminated, the star wheels may transfer ink to the media causing print defects.
It would be advantageous to have a media feed system that minimizes these and other shortcomings of typical star-wheel media feed systems.
The invention, in one form thereof, is directed to a print media feed system in an inkjet printer, the system has a feed roll, a first star wheel mounted opposing the feed roll forming a nip therebetween for receiving a sheet of media, an adjustable biaser coupled to the first star wheel, and a controller in operable communication with the biaser. The controller is configured to adjust the biaser to provide one of a plurality of biasing forces to the star wheel, each of the plurality of biasing forces having a unique magnitude, a unique direction, or a unique magnitude and direction.
The invention, in another form thereof, is directed to a print media feed system in an inkjet printer, the system having a feed roll, a first star wheel mounted opposing the feed roll forming a nip therebetween for receiving a sheet of media, an adjustable directional biaser coupled to the first star wheel, and a controller in operable communication with the biaser. The controller is configured to adjust the biaser to provide in a first position a biasing force to move the star wheel toward the feed roll and in a second position to provide a biasing force to move the star wheel away from the feed roll with the biasing force changing magnitude and direction as the directional biaser moves between the first and second position.
The invention, in yet another form thereof, is directed to a print media feed system in an inkjet printer, the system having a feed roll, a first star wheel mounted opposing the feed roll forming a nip therebetween for receiving a sheet of media, a first lever having a first end pivotally mounted in the inkjet printer and a second end rotatably coupled to the star wheel, a first cam coupleable to a motor, a first biasing member holding the first lever against the first cam, and a controller in operable communication with the motor. The controller is configured to adjust the angular position of the motor which adjusts the angular position of the cam and the first lever to provide one of a plurality of biasing forces to the star wheel, each of the plurality of biasing forces having a unique magnitude, a unique direction, or a unique magnitude and direction.
The above-mentioned and other features and advantages of the disclosed embodiments, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of the disclosed embodiments in conjunction with the accompanying drawings.
It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.
Spatially relative terms such as “top”, “bottom”, “front”, “back”, “rear” and “side”, “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the relative positioning of one element to a second element. Terms like “horizontal” and “vertical” are used in a similar relative positioning as illustrated in the figures. These terms are generally used in reference to the position of an element in its intended working position within an imaging device. The terms “left” and “right” are as viewed with respect to the insertion direction of a unit into the imaging device. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
The term “image” as used herein encompasses any printed or digital form of text, graphic, or combination thereof. The term “output”, as used herein, encompasses output from any printing device such as color and black-and-white copiers, color and black-and-white printers, and so-called “all-in-one devices” that incorporate multiple functions such as scanning, copying, and printing capabilities in one device. The term “button” as used herein means any component, whether a physical component or graphic user interface icon, that is engaged to initiate a signal such as an input or output signal.
Referring now to the drawings and particularly to
Directional biaser 310 includes a lever 312, a spring 314, and a cam 316. Cam 316 is operably coupleable to a motor 318. At a first end 312-1, lever 312 is pivotally mounted to a support 330 provided in the inkjet printer. At a second end 312-2, lever 312 is rotatably coupled to star wheel 304. Spring 314 is operably coupled at a first end 314-1 to lever 312 and at a second end 314-2 to a support 332 provided in the inkjet printer. As cam 316 rotates, lever 312 remains in contact with the cam 316 due to the force of spring 314 acting on lever 312. Lever 312 is made of a flexible material, such as spring steel, so that the lever 312 will flex and apply a variable biasing force to the star wheel 304 as the cam 310 is rotated. The flexed state of lever 312 is shown in dotted lines. The downward-directed force generated by flexing the lever 312 is larger than the upward-directed force generated by the spring 314, resulting in a downward-directed biasing force applied to the star wheel 304. Thus, rotating the cam adjusts the biaser 310 to provide one of a plurality of biasing forces to the star wheel 304 via lever 312, each of the plurality of biasing forces having a unique magnitude, a unique direction, or a unique magnitude and direction.
Cam 316 may be operably coupled to motor 318 in a number of configurations. Cam 316 may in one form be mounted directly on an output shaft 320 of motor 318 (See
Biaser motor 318 is in operable communication with a controller 360 via communications link 362 for controlling the operation of biaser motor 318. Biaser motor 318 may be, for example, a stepper motor and controller 360 adjusts the angular position of cam 316 by stepping biaser motor 318 to a given angular position allowing cam 316 to remain at that position. Controller 360 is also shown in operable communication via communications link 364 with feed roll motor 370 that is operably coupled to feed roll 302 for controlling the operation of feed roll 302.
As cam 316 on shaft 322 rotates to a first position of maximum biasing force, lever 312 rotates about its first end 312-1 and support 330 to apply a biasing force to star wheel 304 that is counter to that of spring 314 so that star wheel 304 is driven in a first direction toward feed roll 302. The maximum biasing force applied by lever 312 occurs when major axis 316M of cam 316 would be perpendicular to lever 312. Cam 316 is shown approaching this position in
In
It will be realized that as cam 316 is rotated between a first position where its major axis 316M is approximately perpendicular to lever 312 and a second position where its minor axis 316m is approximately perpendicular to lever 312, the magnitude and direction of the biasing force applied to star wheel 304 can be varied and that the height of nip 306 can also be controllably varied. In other words as the angular position of cam 316 changes and thus the biasing force applied to star wheel 304 via lever 312 changes, one of a plurality of biasing forces is applied dependent on the angular position of cam 316. Thus, directional biaser 310 can be used to vary the force that star wheel 304 applies to a sheet of media when present in nip 306. It may also be used to adjust the height of nip 306 to accommodate thicker media or to move star wheel 304 away from contact with feed roll 302.
The biasing force of adjustable directional biaser 310 may be adjusted to optimize the media feed system in response to different media properties. For example, a stronger biasing force on star wheel 304 may be used when feeding thin media than when feeding thicker card stock. Also, the biasing force may be reduced when feeding photo media to avoid the tips of star wheel 304 making print-defect divots in the surface 342 of the sheet of media 340.
Other adjustable directional biasers are contemplated. For example, in
Each star wheel 510a-510d has a corresponding media feed roll 512a-512d, respectively. Star wheels 510a, 510d are biased by adjustable directional biasers 550a, 550b while stars wheels 510b, 510c are biased by adjustable directional biasers 550c, 550d, respectively. Directional biasers 550a-550d each comprise cams 551a-551d, springs 553a-553d, and levers 555a-555d, respectively, that function and are cooperatively engaged as previously described. The innermost star wheels 510b, 510c and corresponding feed rolls 512b, 512c are nested between the outermost star wheels 510a, 501d and corresponding feed rolls 512a, 512d as viewed perpendicular to the media feed path 508. Cams 551b, 551c for the innermost star wheels 510b, 510c are driven by a common shaft 514 by biaser motor 560b which allows for concurrent adjustment to the biasing forces applied to the innermost star wheels 510b, 510c. Cams 551a, 551d for the outermost star wheels 510a, 510d are driven by a second common shaft 516 by biaser motor 560a which again allows for the concurrent adjustment of the biasing forces applied to outer star wheels 510a, 510d.
When printing narrow media, for example, the innermost star wheels 510b, 510c may be biased by biaser 550b so that they pinch the sheet of media against their corresponding media feed rolls 512b, 512c to assist in feeding the sheet of media in the media feed direction 508. At the same time, the outermost star wheels 510a, 510d may be biased by biasers 550a, 550d so that they lift off of their corresponding media feed rolls 512a, 512d to avoid unnecessary wear on the star wheels 510a, 510b. When printing a sheet of wider media, all of the star wheels 510a-510d may be biased to touch the wider media.
Of course, inkjet printer 500 may be designed such that the biasing force applied to each star wheel 510a-510d is independently controlled as indicated by optional biaser motors 560c, and 560d shown in dashed lines. Shafts 514, 516 would not be installed with such an arrangement and biaser motors 560c, 560d would be operatively coupled to respective cams 551c, 551d as indicated by the dashed line. Controller 580 would control optional biaser motors 560c, 560d via communication link 584.
Controllers 360, 580 may be formed, for example, as an application specific integrated circuit (ASIC), and may include a processor, such as a microprocessor, and associated memory 363, 583. Memory 363, 583 may be any volatile or non-volatile memory of combination thereof such as, for example, random access memory (RAM), read only memory (ROM), flash memory and/or non-volatile RAM (NVRAM). Alternatively, memory 363, 583 may be in the form of a separate electronic memory (e.g., RAM, ROM, and/or NVRAM), a hard drive, a CD or DVD drive, or any memory device convenient for use with controllers 360, 580. Memory 363, 583 may be used to store program instructions for controllers 360, 580 to control biaser motors 560a-560d and their corresponding directional biasers 550a-550d. Look up tables 365, 585 may be provided in memories 363, 583, respectively. Look up tables 365, 585 may store biaser positions corresponding to provide biasing forces dependent on the media thickness, media stiffness, print density, as well as default biasing positions.
As used herein, the term “communications link” generally refers to structure that facilitates electronic communication between two components, and may operate using wired or wireless technology. Accordingly, communications links may be a direct electrical wired connection, a direct wireless connection (e.g., infrared or r.f.), or a network connection (wired or wireless), such as for example, an Ethernet local area network (LAN) or a wireless networking standard, such as IEEE 802.11. Although separate communications links are shown between controller 360, 580 and the other controlled elements, a single communication link can be used to communicatively couple the controller 360, 580 to all of the controlled elements for example controller 580 to such as motor 503, feed motor 570, biaser motors 560, etc.
At block 602, the method 600 establishes a density criteria based upon the number of pixel to be printed and at least one of media type, humidity or color space An example density criteria is the number of pixels to be printed within a given area. Since plain paper is somewhat absorptive, printing must be relatively dense before ink will remain on the surface long enough to touch the star wheel. In contrast, photo paper is much less absorptive and printing may be less dense and still cause star wheel contamination. Humidity and color space may also influence the density required to cause star wheel contamination.
At block 604 the method 600 analyzes print data to identify an area of printing that aligns with the star wheel and calculates the area density.
At block 606, the method 600 prints the area of printing onto a sheet of print media.
At block 608, a determination is made to see if the area density exceeds the density criteria. If NO, the area density is less than the density criteria, method 600 proceeds to block 610 where the area of printing of the sheet of media is advanced to the star wheels. Because the area density is less than the density criteria, the need to lift the star wheels for the printed area is not needed as there is little likelihood of contamination of the star wheel. If YES, the area density exceeds the density criteria and star wheel contamination is a concern, the method 600 proceeds to block 612.
At block 612 the method 600 uses the adjustable biaser to lift the star wheel off of the sheet of media before the area of printing touches the star wheel. At block 614 the method 600 advances the area of printing of the sheet past the star wheel. At block 616, the star wheel is lowered back onto the sheet by the biaser after the area of printing has advanced past the star wheel.
At block 706, method 700 determines a classification of a sheet of media based on media thickness. The determination may be made, for example, based on a user selection of media thickness, a measurement of media thickness, a measurement of media stiffness, etc. At block 708, a determination is made to see if the media is thick. If YES, the media is thick, method 700 proceeds to block 710 where the method 700 uses a biaser to increase nip height or decrease star wheel force. The amount of increase or decrease may be found by controller 360 in a look up table in memory 601 based upon the media thickness. At block 712, method 700 clamps the media between the star wheel and the media feed roll. If NO, media is not thick, method 700 proceeds to block 714 where a determination is made to see if the media is thin. If YES, media is thin, method 700 proceeds to block 716 where method 700 uses a biaser to decrease nip height or increase star wheel force then proceeds to block 712. Again the amount of increase or decrease may be found by controller 360 in a look up table in memory 601 based upon the media thinness. If NO, media is not thin, method 700 proceeds to block 718 where method 700 uses a biaser to set nip height to default height or to set star wheel force to default force then proceeds to block 712. The default height may be stored in memory 601. This method may be used, for example, to prevent wearing the star wheel against a rotating media feed roll when media is not present. This method may also be used, for example, to improve paper feeding across a range of media thicknesses.
The foregoing description of several embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.
The present application is related to U.S. patent application Ser. No. ______, (Attorney Docket No. P89-US2) entitled “METHOD OF USING STAR WHEEL WITH ADJUSTABLE DIRECTIONAL BIASER” filed concurrently herewith and assigned to the assignee of the present application.