Patent Grant
7036919
The present application is related to co-pending U.S. patent application Ser. No. 10/460,848, entitled PRINTER SYSTEM AND PRINTING METHOD, and having the same inventors as the present application and filed on the same date as the present application, the full disclosure of which is hereby incorporated by reference.
The present application is related to co-pending U.S. patent application Ser. No. 10/460,890 entitled INTERPOLATION USING AT LEAST ONE BOUNDARY POINT IN A BOUNDARY SURFACE, filed on the same date herewith by Jay S. Gondek, Jay S. Agar, Ufuk A. Schramm and Morgan Thomas, the full disclosure of which is hereby incorporated by reference.
The present application is related to co-pending U.S. patent application Ser. No. 10/460,891, entitled RENDERING USING AT LEAST TWO LEVELS OF GRAY, filed on the same date herewith by Jay S. Gondek, Stephen W. Bauer, Matthew A. Shepherd, Guo Lee and Luann E. J. Rolly, the full disclosure of which is hereby incorporated by reference.
Various printing systems presently exist for printing color or black and white images upon a print medium such as paper. Inkjet printing systems typically include print cartridges (also known as pens) which contain ink and also include a printhead with nozzles to eject drops of ink onto a page or sheet of the print media. The print cartridges are typically mounted on a carriage which is arranged to scan across the print media along an axis as the print cartridges print a series of individual drops of ink on the print media. The series of drops collectively form a band of an image, such as a picture, chart or text. Between such scans, the print medium is advanced relative to the scan axis.
Known color inkjet printing systems typically utilize the following inks: dark cyan (C), dark magenta (M), yellow (Y), light cyan (c), light magenta (m), pigment black (k) and dye black (Z). In some systems, the C, M and Y inks are contained in a single print cartridge having three chambers communicating with a printhead. The c, m and Z inks are typically contained in a second three-chambered print cartridge. This print cartridge is often referred to as “photo” print cartridge. Because the k ink is particularly used for textual or monochrome printing, some systems additionally include a print cartridge having a single chamber containing the k ink.
Despite the many advances that have been made over the years, existing printing systems and print cartridges fail to provide consistent high-quality results when printing photos. Existing printing systems and inkjet print cartridges also fail to facilitate convenient, inexpensive printing of different image types.
Carriage drive 32 is shown schematically and generally comprises a conventionally known or future developed actuator configured to move carriage 30 along scan axis 40 across medium 20 in response to control signals from controller 36. Media drive 34, schematically shown, comprises a conventionally known or future developed actuator configured to feed and move medium 20 relative to carriage 30 and whatever print cartridges are supported at print cartridge locations 42, 44 and 46. The exact configuration of media drive 34 may be varied depending upon the characteristics of medium 20 being fed past carriage 30. For example, media drive 34 may have different configurations depending upon whether medium 20 is provided as a roll or as individual sheets, and depending upon the particular dimensions of medium 20. U.S. Pat. No. 5,659,345 by Altendorf and issued on Aug. 19, 1997, the full disclosure of which is hereby incorporated by reference, describes examples of a carriage drive 32 and a media drive 34.
Controller 36 generally comprises a processor unit configured to generate control signals which are transmitted to carriage drive 32, media drive 34 and whatever print cartridges 24, 26, 28 that are mounted to carriage 30. Controller 36 may comprise a conventionally known or future developed processing unit that executes sequences of instructions contained in a memory (not shown). Execution of the sequences of instructions causes the processing unit to perform steps such as generating control signals. The instructions may be loaded in a random access memory (RAM) for execution by the processing unit from a read only memory (ROM), a mass storage device, or some other persistent storage. In other embodiments, hard wired circuitry may be used in place of or in combination with software instructions to implement the functions described. Controller 36 is not limited to any specific combination of hardware circuitry and software, nor to any particular source for the instructions executed by the processing unit.
Controller 36 receives data representing an image to be printed from a source (not shown) such as a computer, a portable memory storage device such as flash memory, disk, cassette, card and the like, or directly from memory of a device, such as a video camera, digital camera and the like. Controller 36 further senses the characteristics and locations of print cartridges 24, 26, 28 or other print cartridges mounted to carriage 30. Based upon such information, controller 36 controls carriage drive 32 to move carriage along scan axis 40, controls media drive 34 to move medium 20 relative to carriage 30 in directions generally perpendicular to scan axis 40, and controls the application of inks from one or more of print cartridges 24, 26, 28, 14 or 16 supported by carriage 30.
Print cartridges 24, 26 and 28 (schematically shown) are substantially identical to one another, except for different inks or ink combinations contained within the print cartridges. In particular, each of print cartridges 24, 26 and 28 generally comprise a conventionally known or future developed inkjet print cartridge having a printhead 50 and a plurality of distinct chambers 52 which communicate with the printhead 50. Printhead 50 includes a plurality of individual nozzles, wherein each chamber 52 is in communication with one or more of the plurality of nozzles. Based upon control signals from controller 36, ink is dispensed from the chambers 52 through the nozzles 50 onto print medium 20. In the particular embodiment illustrated, each of print cartridges 24, 26 and 28 includes three chambers 52 in communication with printhead 50. An example of a three chambered ink jet print cartridge that may be employed is disclosed in U.S. Pat. No. 5,969,739 by Altendorf et al. which issued on Oct. 19, 1999, the full disclosure of which is hereby incorporated by reference. As will be described in greater detail hereafter, the three chambers provided by each of print cartridges 24, 26 and 28 enables printer system 12 to utilize unique ink combinations for improved image reproduction quality and for printing unique modes.
Print cartridge 24 includes three chromatic inks contained within its three chambers 52. In the embodiment illustrated, print cartridge 24 includes a dark cyan ink (C), a dark magenta ink (M) and a yellow ink (Y). Print cartridge 26 includes a light cyan ink (c), a light magenta ink (m) and a pigment black ink (k) in its three chambers 52.
For purposes of this disclosure, “dark” and “light” inks are to be identified based upon their light absorbance. Absorbance is generally used to determine the concentration of a given substance such as a dye in a solution. Many molecules and ions have the ability to absorb visible light. When such ions or molecules are present in the solution, the amount of light absorbed is directly related to the number of molecules in solution. Each ion or molecule has a characteristic absorption spectra wherein the various wave lengths of light present in visible “white” light are differentially absorbed. It is generally desirable in most cases to measure the absorbance where the absorbance is strongest (LAMBDAMAX) or most sensitive. The absorbance of an ink is measured on a sample of the ink diluted one part in 10,000 at a point of maximum peak absorbance (LAMBDAMAX) within a given wave length range. Accordingly, Beers Law:
Absorbance=Ebc
where E is equal to molar absorptivity or extinction coefficient which is an intrinsic property of the molecule
Print cartridge 28 includes three achromatic inks within its three chambers 52, wherein the three achromatic inks have distinct L* values. For purposes of this disclosure, an “achromatic” ink shall mean an ink having a small or visually negligible amount of chroma. For purposes of this disclosure, the term “L* value” refers to the CIE 76 L* values which are determined based upon standards relating to perceptual lightness promulgated by the International Committee on Illumination or CIE (Commission Internationale de L'Eclairage) in 1976. According to such standards, an L* value of 100 generally equals an ideal diffused perfectly white reflector. In the particular embodiment illustrated, print cartridge 28 includes a light gray ink (g), a medium gray ink (G) and a dye-based black ink (Z). In the embodiment shown, the light gray ink (g) has a first L* value, the medium gray ink (G) has a second smaller L* value, and the dye-based black ink has a third L* value less than the first L* value of the light gray ink and less than the second L* value of the medium gray ink. The light gray ink has an L* value greater than or equal to the L* value of the light cyan ink and the light magenta ink. In one embodiment, the light gray ink has an L* value of between about 50 and 70, the medium gray ink has an L* value of between about 25 and 50, and the dye-based black ink has an L* value of between about 0 and 5. By way of comparison, dark cyan (C) ink and dark magenta (M) ink typically have an L* value of between about 35 and 55 while light cyan (c) ink and light magenta (m) ink have L* values of between about 60 and 85. In particular applications, the L* values of the achromatic inks contained in print cartridge 28 may slightly vary depending upon the L* value of the medium 20 being printed upon. In particular, in applications where medium 20 has a first L* value (L*1) and where the dye-based black ink has an L* value of less than the first L* value by a difference D, the dark gray ink may have an L* value of between L*1 minus 0.5 D and L*1 minus 0.75 D. The light gray ink may have an L* value of between L*1 minus 0.3 D and L*1 minus 0.5 D.
The light gray (g) ink, the medium gray (G) ink and the dye-based black (Z) ink may also be identified by their absorbance values. However, unlike chromatic colors, achromatic colors typically have a flat response rather than a peak absorbance. As a result, the wave length range where such peak absorbance occurs is much broader. Applying the Beers Law of Measurement, the black (Z) ink, medium gray (G) ink and light gray (g) inks have the following absorbance values:
In contrast to conventional printing systems that combine a yellow ink (Y) contained in a first print cartridge with a light cyan ink (c) or a light magenta ink (m) contained in a second print cartridge to produce a composite gray (i.e. a gray color created by printing a plurality of different chromatic ink dots in close proximity to one another, a technique commonly referred to as halftoning), printer system 12 utilizes a single print cartridge 28 providing a plurality of achromatic inks having distinct L* values such as light gray ink (g), medium gray ink (G) and dye-based black ink (Z). As a result, printer system 12 prints images with (1) greater consistently, (2) improved economy and (3) higher quality. First, in contrast to those systems that print composite grays, printing system. 12 may print more consistent images that are less likely to experience hue shift. In particular, it has been found that images printed by printing system 12 using print cartridge 28 do not experience hue shift in conditions where dot grain varies such as when different media is used or such as when humidity changes. In other words, printing system 12 achieves results that are consistent regardless of the type of media being printed upon or the particular humidity during such printing. In addition, because each of the three achromatic inks utilized by system 12 are contained in a single print cartridge 28, images printed by system 12 do not experience hue shift which occurs when different print cartridges produce differently sized drops of ink given the same electrical signals as a result of manufacturing tolerances (also known as “pen drop weight variation”).
Moreover, unlike those systems that must print composite grays, system 12 and print cartridge 28 prints images having reduced metamerism effects that result in color shifts under different illuminants. For example, grays produced by system 12 utilizing print cartridge 28 do not look purple under office lights but green under daylight.
Second, printing system 12 enables more efficient and economical use of ink. In conventional systems, each composite gray that is printed typically requires the yellow ink (Y), resulting in excessive consumption of such yellow ink. Because system 12 prints grays utilizing print cartridge 28, system 12 achieves more balanced usage of inks contained within the CMY print cartridge 24 and, ultimately, a longer useful life for the CMY print cartridge.
Third, in contrast to conventional systems which print composite grays, printing system 12 produces higher quality images. In particular, system 12 achieves improved or increased gamut in color images and improved true black-and-white images. As described in greater detail in co-pending U.S. patent application Ser. No. 10/460,891, entitled “RENDERING USING AT LEAST TWO LEVELS OF GRAY”, filed on the same date herewith by Jay S. Gondek, Stephen W. Bauer, Matthew A. Shepherd, Guo Lee, and Luann E. J. Rolly, the full disclosure of which is hereby incorporated by reference, transitions from solid colors to black may be defined by utilizing a light gray ink, a medium gray ink and a black ink in combination with not more than two additional colorants. As a result, global hue cast problems in images are eliminated, more accurate color reproduction and less need for printer calibration is achieved, cyan dots in skin colors are eliminated, ink usage is reduced, and grain is reduced. In addition, for a given dot visibility, the gray inks achieve better darkening properties when printed beyond dot-overlap due to uniform absorption. Because of the uniform absorptive properties of the gray ink, the use of gray in conjunction with color inks results in an improved gamut for dark colors. Moreover, utilizing at least two gray inks enables fine gray or black details to be reproduced without color fringing. Similar benefits are achieved when black and white images are being printed.
Printer system 12 also achieves improved photo quality images as compared to those systems that utilize print cartridges containing a single ink and that recommend mounting seven print cartridges (C, M, Y, c, m, k and light black ink print cartridges) to the carriage for photo printing. In particular, because print cartridge 28 includes a light gray ink (g) having an L* value greater than or equal to the L* value of the light cyan ink (c) and the light magenta ink (m), system 12 achieves light tone characteristics in its printed images that are better than those systems employing light cyan and light magenta inks to produce composite grays. At the same time, because system 12 utilizes a print cartridge 28 also including a medium gray ink (G) having an L* value between the L* value of the black ink and the L* value of the light gray ink, system 12 also achieves a smooth transition between the light gray ink (g) and the black ink (k) without a noticeable increase in grain in midtones in image 18. Because print cartridge 28 includes two gray inks, g, G, in addition to a black ink, Z, print cartridge 28 may utilize a light gray having an L* value greater than the L* value of typical light cyan (c) and light magenta (m) inks and a medium gray ink having an L* value greater than a typical dark cyan (C) or dark magenta (M) inks. Because print cartridge 28 utilizes balanced gray inks, system 28 may produce a lighter dot utilizing the light gray ink as compared to the light cyan ink or the light magenta ink. Similarly, system 12 may also produce a lighter dot using the medium gray ink as compared to those prior systems which utilize dark cyan ink or dark magenta inks. The end result is less grain in light regions as well as less grain in mid-tone regions.
As further shown by
Print cartridge 16 generally comprises a conventionally known or future developed inkjet cartridge or print cartridge having a printhead 50 in a single chamber 52 containing a black pigment ink. As conventionally known, black pigment ink is particularly useful for printing text. In particular applications where image 18 consists solely of text, print cartridge 16 may be exchanged with one of print cartridges 24, 26, 28 (or 14) mounted to carriage 30.
In one alternative embodiment, print cartridge 28 includes two achromatic inks and a chromatic ink within its three chambers 52. For example, in one embodiment, print cartridge 28 may include a light gray (g) ink and a medium gray (G) ink as, discussed above, but may alternatively include a color or chromatic ink in lieu of the dye-based black (Z) ink. In still other embodiments, print cartridge 28 may alternatively include only two chambers 52 containing the light gray (g) ink and the medium gray (G) ink discussed above. In such alternative embodiments, provision of a light gray ink and a medium gray ink in a single print cartridge achieves high image quality and versatile printing capabilities.
Adding to the versatility of system 112, kit 110 enables one or more of print cartridges 14, 16 and 26 to be swapped with print cartridges 24 and 28 for printing even additional types of print or effects. For example, print cartridge 14 may be simply switched with print cartridge 24 to print artistic effects by utilizing ink from both print cartridges 14 and 28. Examples of such artistic effects include overall color cast effects like sepia or blue-toned images, or variable color washes over elements in a black-and-white image. One example of a color was is a “faux” hand-colored mode that simulates hand-colored photos. By swapping print cartridges 16 and 24, the pigment black ink contained in print cartridge 16 may be utilized in conjunction with three achromatic dye-based inks in print cartridge 28 to achieve extremely high-quality black-and-white printing on media type such as plain paper that require pigment black to achieve a sufficiently dark black image. In such a configuration, combinations of the three achromatic dye-based inks are half-toned together to form gray highlights and mid-tones and the pigment black is half-toned into the mix for darker tones and black.
Overall, kit 110 achieves much higher quality black-and-white photo printing and color photo printing while utilizing a more compact and generally less expensive two-print cartridge printer 122 having a carriage 130 with only two print cartridge locations 142 and 146. Although kit 110 is illustrated as including print cartridges 14, 16, 24, 26 and 28, kit 110 may alternatively include fewer than all five print cartridges so long as kit 110 includes print cartridge 28 which provides printing system 112 with its printing versatility.
Although the present invention has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present invention is relatively complex, not all changes in the technology are foreseeable. The present invention described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.
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