1. Field of the Invention
The present invention relates to a technique for recording dots on the surface of a recording medium with the aid of a dot-recording head, and more particularly to a technique for printing images up to the edges of printing paper without soiling the platen.
2. Description of the Related Art
Printers in which ink is ejected from the nozzles of a print head have recently become popular as computer output devices.
When an attempt is made to print images up to the edges of printing paper with the aid of such a printer, it is necessary to arrange the printing paper such that the edges of the printing paper are disposed underneath the print head (that is, on the platen) and to cause ink droplets to be ejected from the print head. With such printing, however, the ink droplets sometimes miss the edges of the printing paper (for which the droplets have been originally intended) and end up depositing on the platen due to errors developing during the feeding of the printing paper, a shift in the impact location of the ink droplets, or the like. In such cases, the ink deposited on the platen soils the printing paper transported over the platen in the next step.
It is an object of the present invention, which was perfected in order to overcome the above-described shortcomings of the prior art, to provide a technique that allows images to be printed up to the edges of printing paper while preventing ink droplets from depositing on the platen.
Perfected in order to at least partially overcome the above-described shortcomings, the present invention envisages performing specific procedures for a dot-recording device designed to record ink dots on a surface of a print medium with the aid of a dot-recording head provided with a plurality of dot-forming elements for ejecting ink droplets. The dot-recording device comprises a platen configured to extend in the main scanning direction and to be disposed opposite the dot-forming elements at least along part of a main scan path, the platen being configured to support the print medium, a width of the slot in the sub-scanning direction corresponding to a specific sub-scanning range on a surface of the dot recording head including at least part of the plurality of dot-forming elements.
The specific sub-scanning range preferably includes at least one of two end ranges in the sub-scanning at opposite ends of the dot-recording head, each end range including at least one dot-forming element.
The printing (dot-forming) procedure performed by such a printing device entails driving the dot-recording head and/or the print medium to perform main scanning, driving at least some of the dot-forming elements to form dots, and causing the print medium to undergo sub-scanning by being driven across the main scanning direction in between the main scans. In the process, printing near an edge of the printing medium is effected in a first recording mode, in the first recording mode the controller performing edge printing by ejecting ink droplets from at least some of the dot-forming elements disposed opposite the slot when the print medium is supported on the platen, and the edge of the print medium is disposed above the slot. Printing in an intermediate portion of the print medium is effected in a second recording mode, a maximum sub-scan feed amount in the second recording mode being greater than a maximum sun-scan feed amount in the first recording mode.
According to this embodiment, ink droplets can be prevented from depositing on the plate, and areas extending all the way to the edges of printing paper can be printed without blank spaces with the aid of dot-forming elements disposed opposite the slot.
The edge portions should preferably be printed such that the ink droplets are prevented from being ejected by any dot-forming elements other than those disposed opposite the slot. Adopting this embodiment makes it possible to prevent ink droplets from soiling the platen when the preceding portion of the print medium is insufficiently fed in the sub-scanning direction and the front edge of the print medium being printed fails to reach the position above the slot; that is, when the front edge of the print medium rests on the platen, and part of the platen is disposed directly opposite the dot-recording head. The same applies to cases in which the print medium is fed in the sub-scanning direction in an excessive manner and the rear edge of the print medium passes beyond the slot when images are printed on the rear edge of the print medium.
Images should preferably be printed in the edge portions when the front edge of the print medium is above the slot in cases in which the slot is provided at a position opposite at least a dot-forming element that is disposed along a downstream edge in the sub-scanning direction. Such an embodiment allows images to be printed without blank space along the front edge of the print medium.
In addition, images should preferably be printed in the edge portions when the rear edge of the print medium is above the slot opening in cases in which the slot is provided at a position opposite at least a dot-forming element that is disposed along an upstream edge in the sub-scanning direction. Such an embodiment allows images to be printed without blank spaces along the rear edge of the print medium.
The following benefits are obtained when dots are recorded in this manner in accordance with an embodiment in which the sub-scanning unit for performing sub-scanning in a printing device comprises an upstream sub-scanning unit configured to hold and move the print medium, the upstream sub-scanning unit being disposed on an upstream side in the sub-scanning direction with respect to the dot-recording head; and a downstream sub-scanning unit configured to hold and move the print medium, the downstream sub-scanning unit being disposed on a downstream side in the sub-scanning direction with respect to the dot-recording head.
In the above-described printing device, sub-scanning is accomplished solely with the upstream or downstream sub-scanning unit when images are printed in the edge portions of a print medium. According to the printing procedure adopted for this printing device, the printing distance can be reduced by accomplishing sub-scanning solely with the upstream or downstream sub-scanning unit.
The sub-scanning of the first recording mode should preferably be performed in a feed amount corresponding to a single dot pitch in the sub-scanning direction. Adopting this arrangement makes it possible to print images in the edge portions of the recording medium with nozzles that are close to the edge portions in the sub-scanning direction in the dot-recording head.
Such printing should preferably involve generating image data representing an image extending outside the print medium beyond the edge on which the edge printing is performed, and forming dots on the basis of these image data. Adopting this arrangement makes it possible to print images on the portions of the print medium extending beyond the intended position on the basis of images provided for an area outside the print medium even when the print medium is positioned incorrectly.
A length of an area of the image outside the print medium is preferably set less than the slot width. According to this arrangement, the print medium can be positioned relative to the dot-recording head such that the ink droplets for recording images in an area beyond the edge portion on which images are printed in accordance with the edge-portion printing routine adopted for the print medium are caused to descend into the slot when these ink droplets fail to deposit on the print medium.
Perfected in order to at least partially overcome the above-described shortcomings, the present invention envisages performing specific procedures for a dot-recording device designed to record dots on the surface of a print medium with the aid of a dot-recording head provided with a plurality of dot-forming elements for ejecting ink droplets.
This dot-recording device comprises a platen configured to extend in the main scanning direction while disposed opposite the dot-forming elements at least along part of a main scan path. The platen has an upstream slot that extends in the main scanning direction at a position opposite a dot-forming element disposed at an upstream edge of the dot-recording head in the sub-scanning direction. The platen has also a downstream slot that extends in the main scanning direction at a position opposite a dot-forming element disposed at a downstream edge of the dot recording head in the sub-scanning direction.
In the printing, the dot-recording head and/or the print medium are/is driven to perform main scanning, driving at least some of the dot-forming elements to form dots, and causing the print medium to undergo sub-scanning by being driven across the main scanning direction in between the main scans. Print data is prepared that is containing the image data for recording images in an expanded area that extends lengthwise beyond at least the front and rear edges of the print medium. Ink droplets are ejected onto the expanded area on the basis of the print data. Performing printing with the aid of such a dot-recording device makes it possible to print images up to the edges of printing paper while preventing ink droplets from depositing on the platen.
In the printing on the expanded area, the position of the print medium in the sub-scanning direction is preferably selected such that the print medium is supported on the platen, the front edge of the print medium is brought to a point above the downstream slot, and the front edge reaches a point located in the sub-scanning direction upstream of the dot-forming element on the downstream edge in the sub-scanning direction when ink droplets are ejected onto the front edge of the print medium. The position of the print medium in the sub-scanning direction is preferably selected such that the print medium is supported on the platen, the rear edge of the print medium is brought to a point above the upstream slot, and the rear edge of the print medium reaches a point located in the sub-scanning direction downstream of the dot-forming elements on the upstream edge in the sub-scanning direction when ink droplets are ejected onto the rear edge of the print medium. Adopting this embodiment makes it possible to extend printing up to edge portions without soiling the platen by printing images at the front edge of the print medium above the upstream slot, and at the rear edge of the print medium above the downstream slot.
Following embodiment is preferable in the case that the dot-recording method is such that the platen further has a pair of lateral slots separated apart at a distance substantially equal to a width of the print medium, the lateral slots extending in a sub-scanning range in which ink droplets are ejected from the plurality of dot-forming elements. The image represented by the image data extends widthwise into opposite expanded areas beyond left and right edges of the print medium but remains between outside edges of the pair of lateral slots. Adopting this embodiment makes it possible to print images without blank spaces at the left and right edges of the print medium.
In the printing on the expanded area, the position of the print medium in the main scanning direction is preferably selected such that the print medium is supported on the platen, and the two edges of the print medium are kept at positions above the corresponding lateral slots. Adopting this embodiment makes it possible to print images without blank spaces at the left and right edges of the print medium without soiling the platen.
The print data preferably includes information about a recording condition of dots in pixels in the expanded areas. Adopting this embodiment can make it easier to specify the portions of an expanded area that lie beyond the edges of a print medium.
Perfected in order to at least partially overcome the above-described shortcomings, the present invention envisages performing specific procedures for a dot-recording device designed to record dots on the surface of a print medium with the aid of a dot-recording head provided with a plurality of dot-forming elements for ejecting ink droplets. The platen of this printer comprises a first support, a first slot and a second support. The first support supports the print medium and extends in the main scanning direction at a position opposite a first sub-group of dot-forming elements selected from the plurality of dot-forming elements. The first slot extends in the main scanning direction at a position opposite a second sub-group of dot-forming elements which are disposed in the sub-scanning direction downstream from the first sub-group of dot-forming elements. The second support supports the print medium and extends in the main scanning direction at a position opposite a third sub-group of dot-forming elements which are disposed in the sub-scanning direction downstream from the second sub-group of dot-forming elements. The platen of this printer may further comprise a second slot. The second slot extends in the main scanning direction at a position opposite a fourth sub-group of dot-forming elements which are disposed in the sub-scanning direction downstream from the third sub-group of dot-forming elements.
Adopting such an embodiment allows the upper-edge portion of the print medium, which is fed over the platen from the upstream side (in the course of sub-scanning), to be supported on the first support. It is therefore unlikely that the upper-edge portion (front-edge portion) will fall into the first slot during sub-scanning. It is also possible to print images without blank spaces all the way to the edges of the print medium with the aid of the second sub-group of dot-forming elements (disposed opposite the first slot) and/or the third sub-group of dot-forming elements (disposed opposite the second slot).
The printing (dot-forming) procedure performed by such a printing device entails forming dots on a print medium with the aid of the second to fourth sub-groups of dot-forming elements without the use of the first sub-group of dot-forming elements in accordance with a first image-printing mode for printing images without blank spaces up to the front and/or rear edges of the print medium. The printing procedure also entails forming dots on the print medium with the aid of the first to fourth sub-groups of dot-forming elements in accordance with a second image-printing mode for printing images with blank spaces along the front and rear edges of the print medium. Adopting such an embodiment makes it possible to prevent ink droplets from depositing on the platen and to print images without blank spaces along the edges of the print medium with the aid of dot-forming elements disposed opposite the slots in accordance with the first image-printing mode. Images can be printed faster with the second image-printing mode than with the first image-printing mode because the first sub-group of dot-forming elements is used in addition to the dot-forming elements involved in performing the first image-printing mode.
Assuming that the surface area of the print medium is divided into an upper-edge portion containing the front edge of the print medium, a lower-edge portion containing the rear edge of the print medium, and an intermediate portion disposed between the upper-edge portion and lower-edge portion, the following embodiment is preferable. In the upper-edge portion of the print medium, dots are formed with the aid of the fourth sub-group of dot-forming elements without the use of any of the first to third sub-groups of dot-forming elements. In the intermediate portion of the print medium, dots are formed with the aid of the second to fourth sub-groups of dot-forming elements without the use of the first sub-group of dot-forming elements. In the lower-edge portion of the print medium, dots are formed with the aid of the second sub-group of dot-forming elements without the use of the first, third, or fourth sub-group of dot-forming elements. As used herein, the term “using sub-groups of dot-forming elements” refers to the partial use of at least some of the dot-forming elements when an image is printed. The term “a sub-group of dot-forming elements is left unused” refers to the fact that none of the dot-forming elements belonging to this sub-group of dot-forming elements is used even once when an image is printed.
Because this embodiment entails using the fourth sub-group of dot-forming elements to print images in the upper-edge portion of the print medium, ink droplets are directed to the second slot, and the platen supports are prevented from being soiled when the ink droplets thus ejected miss the upper-edge portion. Similarly, using the second sub-group of dot-forming elements to print images in the lower-edge portion allows ink droplets to be directed to the first slot and prevents platen supports from being soiled when the ink droplets miss the lower-edge portion. It is therefore possible to prevent platen supports from being soiled and to form dots all the way to the front and rear edges of the print medium. Fast printing can be achieved for the intermediate portion because of the use of the second to fourth sub-groups of dot-forming elements.
In the case that the dot-recording device is such that the dot-recording head is aligned in the main scanning direction and provided with a plurality of dot-forming element groups for ejecting different types of ink, the following embodiment is preferable. The first slot is a single slot provided opposite the second sub-groups of dot-forming elements selected from the plurality of dot-forming element groups. The second slot is a single slot provided opposite the fourth sub-groups of dot-forming elements selected from the plurality of dot-forming element groups. Adopting such an embodiment allows dots to be formed using different types of ink in accordance with the first image-printing mode.
The present invention can be implemented as the following embodiments.
(1) A dot-recording method, print control method, or printing method.
(2) A dot-recording device, print control device, or printing device.
(3) A computer program for operating the device or implementing the method.
(4) A storage medium containing computer programs for operating the device or implementing the method.
(5) A data signal carried by a carrier wave and designed to contain a computer program for operating the device or implementing the method.
Embodiments of the present invention will now be described through embodiments in the following sequence.
A. Overview of Embodiments
B. First Embodiment
C. Second Embodiment
D. Third Embodiment
E. Fourth Embodiment
F. Fifth Embodiment
G. Sixth Embodiment
H. Modifications
Printing should preferably be carried out by repeatedly scanning the medium in the sub-scanning direction in small feed-per-dot increments when images are printed near the front edge Pf of the printing paper P. This approach makes it easier to print images in the area containing the front edge of the printing paper above the downstream slot 26r.
Printing should preferably be carried out by repeatedly scanning the medium in the sub-scanning direction in small increments when images are printed near the rear edge Pr of the printing paper. This approach makes it easier to print images in the area containing the rear edge of the printing paper above the upstream slot 26f.
The image data Dn used to record images on the printing paper P are compiled as information about the images to be recorded as dots in each pixel of a rectangular grid that covers the image area. In
When set in the guides, the printing paper P is fed in the course of sub-scanning in the direction of arrow SS. The feeding of the printing paper P in the course of sub-scanning stops when the front edge thereof reaches a position upstream of nozzle No. 1 above the downstream slot 26r. Nozzle Nos. 1 and 2 subsequently start printing images in the upper-edge portion Pf of the printing paper P (located downstream in
A serial input/output interface (SIO) 88 is also connected to the bus 80. The SIO 88 is connected to a modem 18, and to a public telephone network PNT via this modem 18. The computer 90 is connected to an external network through the agency of the SIO 88 and modem 18, and a connection to a specific server SV allows image processing software to be downloaded to the hard disk 16. The required software can also be copied from a floppy disk FD or CD-ROM and executed by the computer 90.
When the application program 95 generates a printing command, the printer driver 96 of the computer 90 receives image data from the application program 95, and the resulting data are converted to a signal that can be processed by the printer 22 (in this case, into a signal containing multiple values related to the colors cyan, magenta, light cyan, light magenta, yellow, and black). In the example shown in
The role of the resolution conversion module 97 is to convert the resolution of the color image data handled by the application program 95 (that is, the number of pixels per unit length) into a resolution that can be handled by the printer driver 96. Because the image data converted in terms of resolution in this manner are still in the form of video information composed of three colors (RGB), the color correction module 98 converts these data into the data for each of the colors (cyan (C), magenta (M), light cyan (LC), light magenta (LM), yellow (Y), and black (K)) used by the printer 22 for individual pixels while the color correction table LUT is consulted.
The color-corrected data have a gray scale with 256 steps, for example. The halftone module 99 executes a halftone routine for expressing this gray scale in the printer 22 by forming dispersed dots. The halftone module 99 executes the halftone routine upon specifying the dot formation patterns of the corresponding ink dots in accordance with the gray scale of the image data by consulting the dot-forming pattern table DT. The image data thus processed are sorted according to the data sequence to be transferred to the printer 22 by the rasterizer 100, and are outputted as final print data PD. The print data PD contain information about the amount of feed in the sub-scanning direction and information about the condition of dot recording during each main scan.
The data about the condition of dot recording and the data about the amount of feed in the sub-scanning direction both in the print data PD correspond to image data D, which substantially specify the images to be printed. Specifically, these data contain, as image data, information about the manner in which dots are recorded in each pixel inside the expanded area.
In the present embodiment, the sole role of the printer 22 is to form ink dots in accordance with the print data PD without processing the images, although it is apparent that such processing can also be carried out by the printer 22.
The overall structure of the printer 22 will now be described with reference to
The mechanism for reciprocating the carriage 31 perpendicular to the direction of transport of the printing paper P comprises a sliding shaft 34 mounted perpendicular to the direction of transport of the printing paper P and designed to slidably support the carriage 31, a pulley 38 for extending an endless drive belt 36 from the carriage motor 24, a position sensor 39 for sensing the original position of the carriage 31, and the like.
The carriage 31 can support a cartridge 71 for black ink (K) and a color-ink cartridge 72 containing inks of the following six colors: cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). A total of six ink-ejecting heads 61 to 66 are formed in the print head 28 in the bottom portion of the carriage 31, and introduction tubes 67 for guiding the ink from the ink tank to each color head are provided to the bottom portion of the carriage 31. Mounting the cartridge 71 for the black (K) ink and the cartridge 72 for the color inks on the carriage 31 causes the introduction tubes 67 to enter the connection holes provided to each cartridge and allows the ink to be fed from the ink cartridges to the ejection heads 61 to 66.
The color heads 61 to 66 in the bottom portion of the carriage 31 are provided with 48 nozzles Nz for each color, and each nozzle is provided with a highly responsive piezoelectric (electrostrictive) element PE. The piezoelements PE are disposed at locations adjacent to the ink conduits for guiding the ink to the nozzles Nz. As is well known, a piezoelement PE changes its crystal structure under the application of voltage and very rapidly converts electrical energy to mechanical energy. In the present embodiment, applying a voltage for a prescribed period between the electrodes disposed at both ends of a piezoelement PE causes the piezoelement PE to expand during the application of voltage, and deforms the lateral wall of the corresponding ink conduit. As a result, the volume of the ink conduit 68 decreases in accordance with the expansion of the piezoelement PE, the ink forms particles Ip in proportion to this contraction, and the particles are ejected at a high speed from the tip of the corresponding nozzle Nz. Images are printed as a result of the fact that the ink particles Ip penetrate into the paper P mounted on the platen 26.
The print head 28 moves back and forth in the main scanning direction over the platen 26 sandwiched between the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d. The printing paper P is held by the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d, and an intermediate portion thereof is supported by the upper surface of the platen 26 while disposed opposite the rows of nozzles in the print head 28. The paper is fed in the sub-scanning direction by the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d, and images are sequentially recorded by the ink ejected from the nozzles of the print head 28. In the present claims, the upstream paper feed rollers 25a and 25b are referred to as an upstream sub-scanning unit, and the downstream paper feed rollers 25c and 25d as a downstream secondary drive/scan unit.
The platen 26 is provided with an upstream slot 26f and a downstream slot 26r, which are located on the upstream and downstream sides, respectively, in the sub-scanning direction. The width of the upstream slot 26f or downstream slot 26r in the main scanning direction is greater than the maximum width of the printing paper P that can be accommodated by the printer 22. In addition, absorbent members 27f and 27r for accepting and absorbing ink droplets Ip are disposed in the bottom portions of the upstream slot 26f and downstream slot 26r, respectively. The downstream slot 26r is disposed opposite those nozzles Nz of the print head 28 that form a downstream group of nozzles Nr (the hatched group of nozzles in
The inner structure of the control circuit 40 (see
In the printer 22 thus configured, the carriage 31 is reciprocated by the carriage motor 24 while paper P is transported by the paper feed motor 23, the piezoelement of each of the nozzle units belonging to the print head 28 is actuated at the same time, ink droplets Ip of each color are ejected, and ink dots are formed to produce multicolored images on the paper P.
In the printer of the present embodiment, the areas near the top and lower edges of printing paper are printed differently from the intermediate area of the printing paper because the upper edge Pf of the printing paper P is printed over the downstream slot 26r, and the lower edge Pr is printed over the upstream slot 26f. In the present specification, the routine whereby images are printed in the intermediate area of printing paper will be referred to as an “intermediate routine,” the routine whereby images are printed in the area near the upper edge of printing paper will be referred to as a “upper-edge routine,” and the routine whereby images are printed in the area near the lower edge of printing paper will be referred to as a “lower-edge routine.” The width of the upstream slot 26f and downstream slot 26r in the sub-scanning direction can be expressed as follows.
W=p×n+a
In the formula, p is a single feed increment in the sub-scanning direction during a top- or lower-edge routine, n is the number of feed increments in the sub-scanning direction during a top- or lower-edge routine, and a is an estimated feed error in the sub-scanning direction during a top- or lower-edge routine. The a-value of the lower-edge routine (upstream slot 26f) should preferably be set to a level above that of the a-value for a upper-edge routine (downstream slot 26r). Specifying the slot width of the platen according to this formula makes it possible to provide the slots with a width sufficient to adequately receive the ink droplets ejected from the nozzles during a top- or lower-edge routine.
In
The operation then proceeds to the intermediate routine and the 5-, 2-, 3-, and 6-dot feed increments are repeated in the order indicated. The intermediate routine involves printing images in accordance with the second recording mode. The system in which sub-scanning is performed by combining different feed increments in this manner is referred to as “non-constant feeding.” Such feeding in the sub-scanning direction allows each raster line (with the exception of some raster lines) to be recorded by two nozzles. In other words, the present embodiment allows each raster line to be printed by two nozzles. In the example shown in
In
In
In the present embodiment, images can be recorded without blank spaces up to the upper edge of the printing paper. As described above, the present embodiment is such that images can be recorded by selecting the fifth and greater raster lines (printable area), as counted from the upstream edge in the sub-scanning direction, from among the raster lines on which dots can be recorded by the nozzles of the print head 28. Consequently, images could theoretically be recorded very close to the upper edge of printing paper by starting dot recording after the printing paper is positioned relative to the print head 28 such that the fifth raster line (as counted from the upper edge) is disposed exactly at the position occupied by the upper edge of the printing paper. There are, however, cases in which the feed increment errors occur during feeding in the sub-scanning direction. There are also cases in which the direction in which ink droplets are ejected shifts away as a result of a manufacturing error or another factor related to the print head. The formation of blank spaces along the upper edge of the printing paper should preferably be prevented in cases in which the position at which the ink droplets are ejected on the printing paper is shifted for these reasons. It is thus assumed with reference to the present embodiment that the image data D used for printing are provided starting from the fifth raster line, which is counted from the upstream edge in the sub-scanning direction and is selected from the raster lines on which dots can be recorded by the nozzles of the print head 28, and that printing is started from a state in which the upper edge of the printing paper P assumes the position occupied by the seventh raster line, as counted from the upstream edge in the sub-scanning direction. Consequently, the prescribed position occupied by the upper edge of the printing paper in relation to each raster line during the start of printing coincides with the position occupied by the seventh raster line, as counted from the upstream edge in the sub-scanning direction (
Specifically, images can be recorded in accordance with the image data D in an expanded area (shown by the dashed line in
In the present embodiment, two raster lines are selected for the width of the portion of image data D provided up to the area outside the printing paper P beyond the upper edge Pf of the printing paper P. Similarly, two raster lines are selected for the width of the portion of image data D provided up to the area outside the printing paper P beyond the lower edge Pr of the printing paper P. In the present specification, the terms “upper edge (portion)” and “lower edge (portion)” are used to designate the edges of the printing paper P corresponding to the top and bottom of the image data recorded on the printing paper P, and the terms “front edge (portion)” and “rear edge (portion)” are used to designate the edges of the printing paper P corresponding to the direction in which the printing paper P is advanced during sub-scanning in the printer 22. In the present specification, the term “upper edge (portion)” corresponds to the front edge (portion) of the printing paper P, and the term “lower edge (portion)” corresponds to the rear edge (portion).
In
As described above, the upper edge Pf of the printing paper P reaches the position of the seventh raster line (as counted from the upstream edge in the sub-scanning direction), which is one of the raster lines on which dots are recorded by the nozzles of the print head 28. Specifically, it follows from
There are also cases in which the upper edge of the printing paper P reaches the position occupied by the second raster line from the top of the printable area or by the raster line disposed in the uppermost tier of the printable area if the feed increment of the printing paper P exceeds the designed increment for any reason. The present embodiment is configured such that nozzle Nos. 1 and 2 are still capable of ejecting ink droplets Ip to cover the aforementioned raster lines at a position beyond the upper edge Pf of the printing paper P in such cases, making it possible to record images along the upper edge of the printing paper P and to prevent blank spaces from forming. Specifically, blank spaces can be prevented from forming along the upper edge of the printing paper P when the feed increment of the printing paper P exceeds the designed increment but the excessive feed increment is still no more than two raster lines, as shown by the dashed line in
It is the CPU 41 that causes images to be printed in the area (expanded area) that extends beyond the upper edge Pf of the printing paper P in this manner. Specifically, the CPU 41 corresponds to the edge printing unit.
Another possibility is that the feed increment of the printing paper P falls short of the designed increment for any reason. In such cases the printing paper fails to arrive at the designated position, and the ink droplets Ip end up depositing on the underlying structure. In the present embodiment, the two raster lines along the intended upper-edge position of the paper sheet are recorded by nozzle Nos. 1 and 2, as shown in
It is the CPU 41 that specifies the position of the printing paper P in the sub-scanning direction in the above-described manner such that the upper edge Pf of the printing paper P assumes a position above the opening of the downstream slot 26r during sub-scanning. The position assumed by the upper edge Pf is located upstream of the nozzles at the downstream edge in the sub-scanning direction. Specifically, the CPU 41 functions as an upper-edge positioning unit.
The printing paper P should be held and fed in the sub-scanning direction by two groups of rollers composed of the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d. The reason is that this arrangement allows paper to be fed in the sub-scanning direction with higher accuracy than when the sheet is held and fed in the sub-scanning direction by a single roller. However, the printing paper P is held and fed in the sub-scanning direction solely by the upstream paper feed rollers 25a and 25b when images are printed along the upper edge Pf of the printing paper. In the present embodiment, printing is started when the seventh raster line, as counted from the upstream edge in the sub-scanning direction and selected from raster lines on which dots can be recorded by the nozzles of the print head 28, reaches the position occupied by the upper edge Pf of the printing paper (see
The printing paper P is supported at two locations on the platen 26 and the upstream paper feed rollers 25a and 25b when images are printed on the area occupied by the upper edge. For this reason, the upper-edge portion of the printing paper P has comparatively high resistance to downward bending when disposed above the downstream slot 26r. It is therefore less likely that the quality of printing in the upper-edge portion will be adversely affected by the bending of the printing paper.
The printing paper P is held solely by the upstream paper feed rollers 25a and 25b when images are printed in the upper-edge portion. The upper-edge portion of the printing paper P will therefore likely to bend downward over the upstream slot 26f. There is, therefore, a comparatively high possibility that the print quality will decrease when images are printed in the upper-edge portion.
(iii) Lower-Edge Routine of First Embodiment
In
In
In the present embodiment, images can be recorded without blank spaces up to the lower edge in the same manner for the upper edge. As described above, the present embodiment is such that images can be recorded by selecting the fifth and greater raster lines (printable area), as counted from the downstream edge in the sub-scanning direction, from among the raster lines that can be used to record dots by the nozzles of the print head 28. It is assumed, however, that images are recorded on the printing paper starting from the seventh raster line (as counted from the downstream edge in the sub-scanning direction) because of considerations related, among other things, to the feed increment errors that occur during feeding in the sub-scanning direction. Specifically, ink droplets Ip are ejected over the fifth and sixth raster lines, and the final main scan of the printing operation is performed in a state in which the lower edge of the printing paper is at a position corresponding to the seventh raster line, as counted from the upstream edge in the sub-scanning direction. Consequently, the intended position of the lower edge of the printing paper in relation to each raster line during the end of printing coincides with the position occupied by the seventh raster line, as counted from the downstream edge in the sub-scanning direction (
If the feed increment of the printing paper P falls below the designed increment for any reason, nozzle Nos. 7 and 8 move beyond the lower edge Pr of the printing paper P and discharge ink droplets Ip for the designated raster lines (fifth and sixth raster lines from bottom in
It is the CPU 41 that prints images in the area (expanded area) beyond the lower edge Pr of the printing paper P in this manner. Specifically, the CPU 41 corresponds to the edge printing unit.
The two raster lines (seventh and eighth raster lines from bottom in
It is the CPU 41 that specifies the position of the printing paper P in the sub-scanning direction in the above-described manner such that the lower edge Pr of the printing paper P assumes a position above the opening of the upstream slot 26f during sub-scanning. The position assumed by the lower edge Pr is located downstream of the nozzles at the upstream edge in the sub-scanning direction. Specifically, the CPU 41 functions as a lower-edge positioning unit.
In the present embodiment, printing is completed when the seventh raster line, as counted from the downstream edge in the sub-scanning direction and selected from raster lines on which dots can be recorded by the nozzles of the print head 28, reaches the position occupied by the lower edge Pr of the printing paper (that is, a position two raster lines in front of nozzle No. 7 in
The printing paper P is supported at two locations on the platen 26 and the downstream paper feed rollers 25c and 25d when images are printed on the area occupied by the lower edge. For this reason, the lower-edge portion of the printing paper P has comparatively high resistance to downward bending when disposed above the upstream slot 26f. It is therefore less likely that the quality of printing in the upper-edge portion will be adversely affected by the bending of the printing paper.
The printing paper P is held solely by the downstream paper feed rollers 25c and 25d when images are printed in the lower-edge portion. The lower-edge portion of the printing paper P will therefore likely to bend downward over the downstream slot 26r. There is, therefore, a comparatively high possibility that the print quality will decrease when images are printed in the lower-edge portion.
During the upper-edge routine of the second embodiment, 3-dot incremental feeding in the sub-scanning direction is repeated 11 times, as shown in
Instead of an intermediate routine being performed immediately thereafter, a transitional routine is carried out prior to the intermediate routine. Similar to the upper-edge routine, the transitional routine involves repeating 3-dot feed increments four times in the sub-scanning direction. All the nozzles (Nos. 1-11) are used in the transitional routine. The operation then proceeds to the intermediate routine, and constant 11-dot feed increments are then repeated, as shown in
In
In the second embodiment, images can be recorded by selecting the seventh and greater raster lines (printable area), as counted from the upstream edge in the sub-scanning direction, from among the raster lines on which dots can be recorded by the nozzles of the print head 28a. The image data D used for printing are provided starting from the seventh raster line, as counted from the upstream edge in the sub-scanning direction. For the same reasons as those described with reference to the first embodiment, printing is started when the upper edge of the printing paper P reaches the position occupied by the 23rd raster line rather than the seventh raster line, as counted from the upstream edge in the sub-scanning direction. Specifically, the intended position of the upper edge of the printing paper P in relation to each raster line at the start of printing coincides with the position occupied by the 23rd raster line, as counted from the upstream edge in the sub-scanning direction (
Another feature of the second embodiment is that nozzle Nos. 1-3 are the only nozzles involved in the recording of the 20 raster lines counted from the position occupied by the upper edge and the 16 preset raster lines extending beyond the intended position of the upper edge of the printing paper P. A downstream slot 26ra is disposed underneath nozzle Nos. 1-3. Ink droplets can therefore be prevented from depositing on a platen 26a when these droplets are ejected onto the 16 preset raster lines beyond the intended position of the upper edge of the printing paper P (that is, onto the area beyond the printing paper). It is also possible to prevent the ink droplets from depositing on the platen 26a when these droplets are ejected onto the raster lines in an area outside the upper-edge portion of the printing paper P in a state in which a feed error affecting the printing paper P has occurred and the printing paper P fails to arrive at the intended position, provided the feed error is within 20 raster lines.
In the present embodiment, 3-dot feeding is repeated four times in accordance with a transitional routine after 11-dot constant feeding has been repeated in the sub-scanning direction from the (n+1)-th cycle to the (n+3)-th cycle in accordance with an intermediate routine, as shown in
In the second embodiment, images can be recorded by selecting the seventh and greater raster lines (printable area, counted from the bottom) from the raster lines on which dots can be recorded by the nozzles of the print head 28, as shown in
In
In the second embodiment, images can be recorded by selecting the eighth and greater raster lines, as counted from the downstream edge in the sub-scanning direction, from among the raster lines on which dots can be recorded by the nozzles of the print head 28a. The image data D used for printing are provided starting from the eighth raster line. For the same reasons as those described with reference to the first embodiment, printing is completed when the lower edge of the printing paper P reaches the position occupied by the 38th raster line rather than the eighth raster line, as counted from the downstream edge in the sub-scanning direction. Specifically, the intended position of the lower edge of the printing paper P in relation to each raster line at the end of printing coincides with the position occupied by the 38th raster line, as counted from the downstream edge in the sub-scanning direction (
Another feature of the second embodiment is that nozzle Nos. 9-11 are the only nozzles involved in the recording of the 20 upstream raster lines counted from the position occupied by the lower edge and the 30 preset raster lines extending beyond the intended position of the lower edge of the printing paper P. An upstream slot 26fa is disposed underneath nozzle Nos. 9-11. Ink droplets can therefore be prevented from depositing on a platen 26a when these droplets are ejected onto the preset raster lines beyond the intended position of the lower edge of the printing paper P (that is, onto the area beyond the printing paper). It is also possible to prevent the ink droplets from depositing on the platen 26a when these droplets are ejected onto the raster lines in an area outside the lower-edge portion of the printing paper P in a state in which a feed error affecting the printing paper P has occurred and the printing paper P is fed in an excessive manner, provided the feed error is within 20 raster lines.
The printing paper P travels a longer distance when images are recorded in the area along the lower edge of the printing paper P than when images are recorded in the area along the upper edge of the printing paper P. It is highly likely, therefore, that when images are recorded the area along the lower edge of the printing paper P is recorded, the positional error of the printing paper P will be greater than when images are recorded in the area along the upper edge of the printing paper P. In addition, the downstream paper feed roller 25d is a gear-type roller, and the combined downstream paper feed rollers 25c and 25d can feed the sheet with less accuracy than when the upstream paper feed rollers 25a and 25b are involved. This is another factor that increases the likelihood that the error created during the recording of the area along the lower edge will be greater than the positional error of the printing paper P created during the recording of the area along the upper edge. Consequently, the number of raster lines recorded solely by the nozzles (Nos. 9-11) above the upstream slot 26fa in the lower-edge portion of the printing paper P should preferably be set above the number of raster lines recorded solely by the nozzles (Nos. 1-3) above the downstream slot 26ra in the upper-edge portion of the printing paper P in the manner adopted in the second embodiment. For image data D, the number of raster lines selected for the area beyond the lower edge of the printing paper P should preferably be set above the number of raster lines selected for the area beyond the upper edge of the printing paper P.
During the upper-edge routine of the third embodiment, 6-dot incremental feeding in the sub-scanning direction is repeated ten times, as shown in
A transitional routine is subsequently carried out. The transitional routine is similar to the upper-edge routine is that feeding in 6-dot increments is carried out twice in the sub-scanning direction. The transitional routine is also similar to the upper-edge routine in that the final feed is followed by an operation in which dots are recorded by nozzle Nos. 1-12. Nozzle Nos. 1-30 are used after the second feed. The operation then proceeds to the intermediate routine, and 24-dot constant feeds are repeated, as shown in
In
In the third embodiment, the image data D used for printing are specified based on the seventh raster line (as counted from the upstream edge in the sub-scanning direction), which constitutes the upper edge of the printable area. For the same reasons as in the first embodiment, printing is started after the upper edge of the printing paper P reaches the position occupied by the 37th raster line, as counted from the upstream edge in the sub-scanning direction. This position is labeled in
Another feature of the third embodiment is that nozzle Nos. 1-12 above the downstream slot 26rb are the only nozzles involved in the recording of the 42 raster lines counted from the position occupied by the upper edge and the 36 preset raster lines extending beyond the intended position of the upper edge of the printing paper P. Ink droplets can therefore be prevented from depositing on the platen 26a when these droplets are ejected onto the 36 preset raster lines beyond the intended position of the upper edge of the printing paper P (that is, onto the area beyond the printing paper). It is also possible to prevent the ink droplets from depositing on the platen 26b when these droplets are ejected onto the raster lines in an area outside the upper-edge portion of the printing paper P in a state in which a feed error affecting the printing paper P has occurred and the printing paper P has failed to arrive at the intended position, provided the feed error is within 42 raster lines.
In the present embodiment, 24-dot constant feeds are repeated in accordance with the intermediate routine, and a single 6-dot feed is performed in accordance with the transitional routine, as shown in
In the third embodiment, images may be recorded by selecting the seventh and greater raster lines (printable area, counted from the bottom) from the raster lines on which dots can be recorded by the nozzles of the print head 28, as shown in
In
In the third embodiment, the image data D used for printing are specified up to the ninth raster line from the bottom. For the same reasons as in the first embodiment, printing is completed after the lower edge of the printing paper P reaches the position occupied by the 49th raster line rather than the position occupied by the ninth raster line, as counted from the downstream edge in the sub-scanning direction.
Another feature of the third embodiment is that nozzle Nos. 37-48 above the upstream slot 26fb are the only nozzles involved in the recording of the 36 raster lines counted from the position occupied by the lower edge and the 40 preset raster lines extending beyond the intended position of the lower edge of the printing paper P. Ink droplets can therefore be prevented from depositing on the platen 26b when these droplets are ejected onto the preset raster lines beyond the intended position of the lower edge of the printing paper P (that is, onto the area beyond the printing paper). It is also possible to prevent the ink droplets from depositing on the platen 26a when these droplets are ejected onto the raster lines in an area outside the lower-edge portion of the printing paper P in a state in which a feed error affecting the printing paper P has occurred and the printing paper P is fed in an excessive manner, provided the feed error is within 36 raster lines.
Yet another feature of the third embodiment is that the number of raster lines recorded solely by the nozzles (Nos. 37-48) disposed above the upstream slot 26fb in the lower-edge portion of the printing paper P is set above the number of raster lines recorded solely by the nozzles (Nos. 1-12) disposed above the downstream slot 26rb in the upper-edge portion of the printing paper P. For image data D, the number of raster lines selected for the area beyond the lower edge of the printing paper P is set above the number of raster lines selected for the area beyond the upper edge of the printing paper P.
The above description was given with reference to an embodiment in which a printer 22 comprising an upstream slot 26f and a downstream slot 26r in a platen 26 was used to print images on the basis of image data D (see
The left slot 26na and right slot 26nb should be configured such that one of the side-edge portions (side-edge portion Pa) of the printing paper P in the main scanning direction is disposed above the opening of the left slot 26na, and the other side-edge portion (side-edge portion Pb) is disposed above the opening of the right slot 26nb when the printing paper P is brought to a specified main-scan position by the guides 29a and 29b. An arrangement in which the side-edge portions of the printing paper P are disposed at a point located inward or outward from the center lines of the left slot 26na and right slot 26nb can therefore be adopted for the left slot 26na and right slot 26nb in addition to an embodiment in which the side-edge portions of the printing paper P are disposed along the center lines of the left slot 26na and right slot 26nb when the printing paper is brought into a specified position in this manner.
The upstream slot 26f, downstream slot 26r, left slot 26na, and right slot 26nb are connected to each other, forming a quadrilateral slot. An absorbent member 27 for receiving and absorbing ink droplets Ip is disposed on the bottom thereof.
The printing paper P passes above the openings of the upstream slot 26f and downstream slot 26r when fed in the sub-scanning direction by the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d. The printing paper P is positioned on the platen 26n by the guides 29a and 29b in the main scanning direction such that the left edge Pa is disposed above the left slot 26na, and the right edge Pb is disposed above the right slot 26nb. The two side edges of the printing paper P are thereby fed while kept at positions above the openings of the left slot 26na and right slot 26nb, respectively, during sub-scanning.
In the embodiment shown in
Such printing allows images to be formed without blank spaces along the right and left edges of the printing paper P even when the printing paper P is shifted somewhat in the main scanning direction. Because the nozzles for printing images in the two side-edge portions of the printing paper are disposed above the left slot 26na or right slot 26nb, ink droplets deposit in the left slot 26na or right slot 26nb rather than in the central portion 26c of the platen 26 when shifted away from the printing paper P. It is therefore possible to prevent situations in which the printing paper P is soiled by the deposition of ink droplets in the central portion 26c of the platen 26.
In the fifth embodiment shown in
The platen 26 of the printer comprises, in order from the upstream side in the sub-scanning direction, an upstream support 26sf, an upstream slot 26f, a central support 26c, and a downstream slot 26r. The printer has a first image-printing mode for printing images without blank spaces all the way to the lower and upper edges of printing paper, and a second image-printing mode for printing images in the regular manner, with blank spaces formed along the upper and lower edges of the printing paper during printing. The second image-printing mode is performed using all the nozzles (nozzle Nos. 1-11 from nozzle groups Nr, Ni, Nh, and Nf) of the print head 28 throughout the entire process of printing images on printing paper. By contrast, the first image-printing mode is performed using solely nozzle Nos. 1-8 (nozzle groups Nr, Ni, and Nh) of the print head 28.
In the first image-printing mode, the upper-edge portion Pf of the printing paper P is disposed above the downstream slot 26r when images are printed along the upper (front) edge Pf of the printing paper P. The images in the upper-edge portion are printed by nozzle Nos. 1 and 2 (nozzle group Nr), which are located above the downstream slot 26r. The images in the intermediate portion of the printing paper P are printed by nozzle Nos. 1-8 (nozzle groups Nr, Ni, and Nh). The lower edge of the printing paper P is disposed above the upstream slot 26f when images are printed along the lower (back) edge of the printing paper P. The printing is accomplished using nozzle Nos. 8 and 9 (nozzle group Nh), which are located above the upstream slot 26f.
In the embodiment shown in
The nozzle group Nr disposed above the downstream slot 26r is used when images are printed in the upper-edge portion of the printing paper P, and the nozzle group Nh disposed above the upstream slot 26f is used when images are printed in the lower-edge portion. The images can therefore be printed without blank spaces all the way to the upper and lower edges of the printing paper while the platen 26 is prevented from being soiled. Faster printing can be achieved in the intermediate portion because images are printed in this portion with the aid of the nozzle group Nr, the nozzle group Nh, and the interposed nozzle group Ni. Chronologically, images are printed first by the downstream portion of the nozzle group Nr; then by the nozzle groups Nr, Ni, and Nh; and finally by the upstream portion of the nozzle group Nh. In other words, the nozzles used for printing are smoothly shifted in the sub-scanning direction from the downstream side to the upstream side. The resulting advantage is that high-quality printing results can be obtained without the need to reverse the direction in which printing paper is fed during sub-scanning.
The portion of the platen further upstream of the upstream slot 26f is referred to as “a upstream support 26sf.” The portion between the upstream slot 26f and downstream slot 26r of the platen 26 is referred to as “a central support 26c.” The portion of the platen further downstream of the downstream slot 26r is referred to as “a downstream support 26sr.” The upstream slot 26f corresponds to the first slot, and the downstream slot 26r corresponds to the second slot. The upstream support 26sf corresponds to the first support, and the central support 26c corresponds to the second support.
A description will now be given in order from the upstream side in the sub-scanning direction. First, the upstream support 26sf is provided such that it extends in the main scanning direction at a position opposite the first nozzle group Nf, which belongs to the nozzles of the print head 28 and is disposed on the most upstream side. The upstream support 26sf is provided with a flat upper surface. The upstream slot 26f is then provided such that it extends in the main scanning direction at a position opposite the second nozzle group Nh, which is disposed downstream of the first nozzle group Nf. The central support 26c is provided such that it extends in the main scanning direction at a position opposite the third nozzle group Ni, which is disposed downstream of the second nozzle group Nh. The downstream slot 26r is then provided such that it extends in the main scanning direction at a position opposite the fourth nozzle group Nr, which is disposed downstream of the third nozzle group Ni. Finally, the downstream support 26sr is provided such that it extends in the main scanning direction at a position in the sub-scanning direction downstream from those nozzles of the print head 28 that are disposed at the downstream edge in the sub-scanning direction. In the print head 28 depicted in
According to the first image-printing mode described below, the printing routine employed for the areas near the upper and lower edges of printing paper is different from that employed for the intermediate portion of the printing paper because the images at the upper edge Pf of the printing paper P are printed above the downstream slot 26r, and the images at the lower edge Pr are printed above the upstream slot 26f. In the present specification, the printing routine employed for the intermediate portion of printing paper will be referred to as “an intermediate routine,” and the printing routines employed for the areas near the upper and lower edges of the printing paper will be referred “an upper-edge routine” and “a lower-edge routine,” respectively. The term “upper and lower printing routines” will be used to collectively refer to the upper-edge routine and lower-edge routine.
The user first selects either the first or second image-printing mode for printing. Selection information about the image-printing mode is specified for an application 95 through a keyboard 14, mouse 13, or other input device connected to a computer 90 (see
The front-edge portion Pf of a printing paper P is supported by the upstream support 26sf when the paper is first fed in the course of sub-scanning by the upstream paper feed rollers 25a and 25b over the platen 26. The front-edge portion Pf then passes over the upstream slot 26f and reaches a point above the central support 26c, as shown in
In the embodiment shown in
The upstream support 26sf faces the first nozzle group Nf and has a specific length Rsf in the sub-scanning direction. The printing paper P is therefore supported over a specific distance by the upstream paper feed rollers 25a and 25b and the upstream support 26sf, which has a specific length in the sub-scanning direction. Consequently, the portion of the printing paper P in front of the upstream paper feed rollers 25a and 25b can consistently maintain constant orientation, and the front-edge portion Pf is unlikely to fall into the upstream slot 26f.
The upstream support 26sf has a flat upper surface, and the printing paper P assumes a shape close to that of the upper surface of the flat upstream support 26sf under the action of gravity when the paper is on the upstream support 26sf. Consequently, at this point as well, the portion of the printing paper P in front of the upstream paper feed rollers 25a and 25b has a substantially flat shape, and the front-edge portion Pf is unlikely to fall into the upstream slot 26f.
The printer of the comparative example is configured such that the section 26sc1 of the platen 26 is disposed further upstream from the print head 28, as are the upstream paper feed rollers 25a and 25b for supporting the printing paper P; and the interval between them is less than in the first embodiment. Adopting such an embodiment makes it more likely that the front-edge portion Pf of the printing paper P will fall into the upstream slot 26fo when the paper is first fed by the upstream paper feed rollers 25a and 25b over the platen 26 in the course of sub-scanning. In addition, the front-edge portion Pf is apt to fall into the upstream slot 26fo when the printing paper P is in the form of curved roll paper with a convex shape. The front-edge portion Pf is less likely to fall into the upstream slot 26fo if the section 26sc1 of the platen 26 has sufficient length in the sub-scanning direction on the upstream side, but adopting such an embodiment increases printer dimensions in the sub-scanning direction.
The first and second image-printing modes employ different patterns of feeding the system in the course of sub-scanning during printing. Whereas the first image-printing mode entails performing different feed patterns for sub-scanning in the upper-edge routine, intermediate routine, and lower-edge routine, the second image-printing mode is performed using the same feed patterns for sub-scanning. Such feeding in the course of sub-scanning is described below separately for the upper-edge and intermediate routines of the first image-printing mode, the lower-edge routine of the first image-printing mode, and the second image-printing mode.
A single row of nozzles consists of 11 nozzles spaced at 3-raster line intervals. The eight nozzles disposed on the downstream side in the sub-scanning direction are the only nozzles used in the first image-printing mode, however. Accordingly, the manner in which raster lines are recorded by these nozzles in an area near the upper edge (tip) of printing paper is the same as shown in
As a result of such printing, the area from the fifth to the eighth raster line (as counted from the uppermost raster line on which dots can be recorded by the print head) is recorded solely by nozzle Nos. 1 and 2 (fourth nozzle group Nr). The ninth and greater raster lines are recorded using Nos. 1-8 (nozzle groups Nr, Ni, and Nh). The relation between these raster lines and the printing paper P, and the effect thereof, will be described below.
In the first image-printing mode, two raster lines are selected for the width (see
The fourth nozzle group Nr, which is shown above in
According to this embodiment, ink droplets can be prevented from depositing on the plate, and areas extending all the way to the upper edges of printing paper can be printed without blank spaces with the aid of dot-forming elements disposed opposite the slot as long as first embodiment.
The above-described results can be obtained by adopting an arrangement in which ink droplets are ejected from at least some of the nozzles belonging to the fourth nozzle group Nr (fourth sub-group of dot-forming elements), and dots are formed on a sheet of printing paper P when the upper edge of the printing paper P passes above the opening of the downstream slot 26r during the printing of images along the upper edge of the printing paper P.
The printing of images in the upper-edge portion of the printing paper P by the fourth nozzle group Nr (nozzle Nos. 1 and 2) is done by a CPU 41 (see
As a result of such printing, the area from the fifth to the tenth raster line (as counted from the lowermost raster line on which dots can be recorded by the print head) is recorded solely by nozzle Nos. 7 and 8 (second nozzle group Nh). The ninth and greater raster lines are recorded using Nos. 1-8 (nozzle groups Nr, Ni, and Nh).
According to this embodiment, ink droplets can be prevented from depositing on the plate, and areas extending all the way to the lower edges of printing paper can be printed without blank spaces with the aid of dot-forming elements disposed opposite the slot as long as first embodiment.
The above-described results can be obtained by adopting an arrangement in which ink droplets are ejected from at least some of the nozzles belonging to the second nozzle group Nh (second sub-group of dot-forming elements), and dots are formed on a sheet of printing paper P when the lower edge of the printing paper P passes above the opening of the upstream slot 26f during the printing of images along the lower edge of the printing paper P. The intermediate routine that precedes the lower-edge routine is also carried out using solely the second nozzle group Nh (nozzle Nos. 7 and 8), third nozzle group Ni (nozzle Nos. 3-6), and fourth nozzle group Nr (nozzle Nos. 1 and 2). In other words, the routine dispenses with the use of the first nozzle group Nf, which is disposed further upstream from the second nozzle group Nh used for the lower-edge routine. A transfer from the intermediate routine to the lower-edge routine can therefore be accomplished in a smoother manner than through the use of all the nozzles (nozzle Nos. 1-11), which include the first nozzle group Nf, during the intermediate routine.
In the present embodiment, the sheet is fed in the sub-scanning direction solely by the downstream paper feed rollers 25c and 25d, and the printing operation is completed in a comparatively short feeding, because the recording on the lower edge of the paper is executed above the upstream slot 26f not above the down stream slot 26r. Accordingly, the printing operation yields better image quality.
The printing paper P is supported at three locations on the central portion 26c and the downstream support 26sr of the platen 26 and the downstream paper feed rollers 25c and 25d when images are printed on the area occupied by the lower edge. For this reason, the lower-edge portion of the printing paper P has comparatively high resistance to downward bending when disposed above the upstream slot 26f. It is therefore less likely that the quality of printing in the upper-edge portion will be adversely affected by the bending of the printing paper.
The above-described printing of images in the lower-edge portion of the printing paper P by the second nozzle group Nh (nozzle Nos. 7 and 8) is done by a CPU 41 (see
In the second image-printing mode, the system is alternately fed in 5- and 6-dot increments in the sub-scanning direction throughout the printing process, as can be seen in
No particular restrictions are imposed on the nozzles for forming dots in the upper- and lower-edge portions of printable areas. With the second image-printing mode, in which images are printed while blank spaces are formed in the edge portions of the printing paper P, no inconvenience is encountered, however, because there is no need to print images near the upper or lower edge only by the nozzles (Nos. 1, 2, 7, and 8) above the slots. By contrast, the second image-printing mode is performed using all the nozzles (Nos. 1-11), allowing images to be printed faster than with the first image-printing mode, in which only a limited number of nozzles are used for printing.
As described above, it is the CPU 41 that controls the units and allows printing to be performed according to the second image-printing mode. In other words, the CPU 41 functions as the second image-printing unit. The second controller 41e is shown in
The first nozzle group Nfa of the second embodiment is an assembly corresponding to the first sub-group of dot-forming elements, and the second nozzle group Nha is an assembly corresponding to the second sub-group of dot-forming elements. The third nozzle group Nia is an assembly corresponding to the third sub-group of dot-forming elements, and the fourth nozzle group Nra is an assembly corresponding to the fourth sub-group of dot-forming elements.
The second embodiment is performed without overlap printing. In other words, each raster line is recorded by a single nozzle in the course of a main scan. The nozzles employed for the first image-printing mode are nozzle Nos. 1-11 (nozzle groups Nra, Nia, and Nha), and the nozzles employed for the second image-printing mode are nozzle Nos. 1-13 (nozzle groups Nra, Nia, Nha, and Nfa).
The manner in which raster lines are recorded by these nozzles in an area near the upper edge (tip) of printing paper is the same as shown in
The manner in which raster lines are recorded by these nozzles in an area near the lower edge of printing paper is the same as shown in
In the present embodiment, 3-dot feeding is repeated four times in accordance with a transitional routine using nozzle Nos. 1-11 (the nozzle groups Nra, Nia and Nha) after 11-dot constant feeding has been repeated in the sub-scanning direction from the (n+1)-th cycle to the (n+3)-th cycle in accordance with an intermediate routine, as shown in
The number of raster lines recorded solely by the nozzles (Nos. 9-11) (the second nozzle group Nha) above the upstream slot 26fa in the lower-edge portion of the printing paper P should preferably be set above the number of raster lines recorded solely by the nozzles (Nos. 1-3) (the second nozzle group Nra) above the downstream slot 26ra in the upper-edge portion of the printing paper P in the manner adopted in the second embodiment.
The present invention is not limited by the above-described embodiments or embodiments and can be implemented in a variety of ways as long as the essence thereof is not compromised. For example, the following modifications are possible.
The first, second, and third embodiments involved performing constant feeding in 1-, 3-, and 6-dot increments, respectively, in accordance with upper- and lower-edge routines. However, the feeding method of the upper- and lower-edge routines is not limited thereby and may include constant feeding in 2-, 4-, or 5-dot increments, depending on the nozzle pitch or the number of nozzles in a nozzle row. In other words, any feeding method may be adopted as long as the maximum feed increment in the sub-scanning direction is less than the maximum feed increment in the sub-scanning direction for the intermediate routine. In should be noted that adopting smaller feed increments in the sub-scanning direction for the upper-edge routine allows the upper edge of printing paper to be recorded with the nozzles disposed further downstream in the sub-scanning direction. The downstream slot can therefore be narrowed, and the upper platen surface for supporting the printing paper can be broadened. Similarly, adopting smaller feed increments in the sub-scanning direction for the lower-edge routine allows the upper edge of printing paper to be recorded with the nozzles disposed further upstream in the sub-scanning direction. The upstream slot can therefore be narrowed, and the upper platen surface for supporting the printing paper can be broadened.
Neither is the feeding method of the intermediate routine limited to constant feeding in 11-dot increments, constant feeding in 24-dot increments, or an non-constant feeding arrangement in which the system is repeatedly fed in 5-, 2-, 3-, and 6-dot increments in the order indicated. For example, feeding the system in 5-, 3-, 2-, and 6-dot increments may be adopted for the structure described in the first embodiment. Depending on the number of nozzles, the nozzle pitch, or the like, combinations of other feed increments may be adopted, or constant feeding methods involving other feed increments carried out. In other words, any type of secondary scan feeding may be adopted as long as the maximum feed increment in the sub-scanning direction is less than the maximum feed increment in the sub-scanning direction for the upper or lower-edge routine.
The above-described embodiments were configured such that the images provided beyond the edges of printing paper extended over two raster lines along both the upper and lower edges in the first embodiment, and constituted 16 raster lines along the upper edge and 30 raster lines along the lower edge in the second embodiment. In the third embodiment, the images extend over 30 raster lines along the upper edge and 40 raster lines along the lower edge. The images that extend beyond the edges of printing paper are not limited by these dimensions, however. For example, the width of the portion occupied by the image data D for an area lying outside the printing paper P beyond the upper edge Pf of the printing paper P may be half that of the downstream slot 26r. Similarly, the width of the portion occupied by the image data D for an area lying outside the printing paper P beyond the lower edge Pr of the printing paper P may be half that of the upstream slot 26f. In other words, the width of the portion occupied by the image data for an area lying outside a printing paper beyond either edge should be less than the width of the downstream slot 26r along the upper edge, and less than the width of the upstream slot 26f along the lower edge. Adopting this arrangement makes it possible to prevent the ink droplets Ip for recording the images lying beyond a printing paper P from being deposited on the upper surface of the platen 26 when the ends of the printing paper P fail to reach the intended position. Approximately the same amount of shift can be permitted both in cases in which the printing paper P is shifted upstream and in cases in which the paper is shifted downstream, assuming that the affected area is about half the slot width.
The same applies to the right and left edges. That is, the width of the portion occupied by the image data for an area lying outside a printing paper beyond either edge should be less than the width of the left slot 26na or the right slot 26nb. Approximately the same amount of shift can be permitted both in cases in which the printing paper P is shifted upstream and in cases in which the paper is shifted downstream, assuming that the affected area is about half the slot width.
Although the above embodiments were described with reference to cases in which both the upper- and lower-edge routine were carried out, it is also possible to perform only one of these routines as needed. In addition, the printing devices of the present embodiments were configured such that the platen 26 was provided with an upstream slot 26f and a downstream slot 26r on the upstream side and downstream sides, respectively, in the sub-scanning direction, although providing only one of them is also acceptable.
In the fifth embodiment, a downstream slot 26r is disposed underneath nozzle Nos. 1 and 2, and images are printed in the upper-edge portion by nozzle Nos. 1 and 2 in accordance with a first image-printing mode. The sixth embodiment is similar in the sense that images are printed in the upper-edge portion by nozzle Nos. 1-3, which are disposed above the slot. However, this arrangement is not the only possible option for the relation between the downstream slot and the nozzles for printing images in the upper-edge portion of printing paper. The embodiment in which each nozzle row has 48 nozzles may, for example, be configured such that a downstream slot is disposed underneath nozzle Nos. 1-5, and images are printed in the upper-edge portion by nozzle Nos. 1-5 (fourth sub-group of dot-forming elements). Specifically, adopting an arrangement in which dots are formed in the upper-edge portion of a print medium with the aid of the fourth nozzle group Nr (fourth sub-group of dot-forming elements) above the opening of the downstream slot has the effect of allowing images to be printed without blank spaces in the upper-edge portion while preventing platen soiling.
In the fifth embodiment, an upstream slot 26f is disposed underneath nozzle Nos. 7 and 8, and images are printed in the lower-edge portion by nozzle Nos. 7 and 8 in accordance with a first image-printing mode. The sixth embodiment is similar in the sense that images are printed in the lower-edge portion by nozzle Nos. 9-11, which are disposed above the slot. The relation between the upstream slot and the nozzles for printing images in the lower-edge portion of printing paper is not limited, however, by the embodiments adopted for the fifth and sixth embodiments. The embodiment in which each nozzle row has 48 nozzles may, for example, be configured such that an upstream slot is disposed underneath nozzle Nos. 31-34, and images are printed in the lower-edge portion by nozzle Nos. 31-34 (second sub-group of dot-forming elements). Specifically, adopting an arrangement in which dots are formed in the lower-edge portion of a print medium with the aid of the second sub-group of dot-forming elements above the opening of the upstream slot has the effect of allowing images to be printed without blank spaces in the lower-edge portion while preventing platen soiling. The first to fourth nozzle groups should each contain one or more nozzles.
The present invention can be adapted to monochromatic printing in addition to color printing. The use of the present invention is not limited to ink-jet printers alone and commonly includes all dot-recording devices in which images are recorded on the surface of a print medium by a print head having a plurality of dot-forming element arrays. As used herein, the term “dot-forming element” refers to a dot-forming constituent element such as an ink nozzle of an ink-jet printer.
In the above embodiments, software can be used to perform some of the functions carried out by hardware, or, conversely, hardware can be used to perform some of the functions carried out by software. For example, a host computer 90 can be used to perform some of the functions carried out by the CPU 41 (
The computer programs for performing such functions may be supplied as programs stored on floppy disks, CD-ROMs, and other types of computer-readable recording media. The host computer 90 may read the computer programs from these recording media and transfer the data to internal or external storage devices. Alternatively, the computer programs can be installed on the host computer 90 from a program-supplying device via a communications line. Computer programs stored by an internal storage device are executed by the host computer 90 when the functions of the computer programs are to be performed. Alternatively, computer programs stored on a storage medium may be executed directly by the host computer 90.
As used herein, the term “host computer 90” refers both to a hardware device and to an operating system, and designates a hardware device capable of operating under the control of an operating system. Computer programs allow such a host computer 90 to perform the functions of the above-described units. Some of the aforementioned functions can be performed by an operating system rather than an application program.
As used herein, the term “computer-readable recording medium” is not limited to a portable recording medium such as a floppy disk or a CD-ROM and includes various RAMs, ROMs, and other internal computer storage devices as well as hard disks and other external storage devices fixed to the computer.
Number | Date | Country | Kind |
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2000-294074 | Sep 2000 | JP | national |
2000-294142 | Sep 2000 | JP | national |
2000-294172 | Sep 2000 | JP | national |
This application is a continuation of U.S. patent application Ser. No. 12/912,592, filed Oct. 26, 2010, which is a continuation of U.S. patent application Ser. No. 12/042,223, filed Mar. 4, 2008, which is a continuation of U.S. patent application Ser. No. 10/888,403, filed Jul. 9, 2004, now U.S. Pat. No. 7,360,888, which is a continuation of U.S. patent application Ser. No. 09/960,618, filed Sep. 21, 2001, now U.S. Pat. No. 6,930,696. All of the foregoing patents and patent applications are hereby incorporated by reference herein in their entirety for all purposes.
Number | Date | Country | |
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Parent | 12912592 | Oct 2010 | US |
Child | 13284649 | US | |
Parent | 12042223 | Mar 2008 | US |
Child | 12912592 | US | |
Parent | 10888403 | Jul 2004 | US |
Child | 12042223 | US | |
Parent | 09960618 | Sep 2001 | US |
Child | 10888403 | US |