JP2005271231A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high-resolution printing to the entire surface of a recording medium in an inkjet recording device. <P>SOLUTION: The inkjet recording device smoothly changes recording elements to be used by providing a scan not involving the contraction, expansion or movement of the range of recording elements to be used for printing from the start to completion of the reduction, expansion or movement of the range of recording elements of a recording element array to be used for printing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus capable of reducing, expanding or moving the range of recording elements used for printing in a recording element array during printing of the same page.

  Conventionally, as part of the operation for realizing borderless printing and mitigating the disturbance of the conveyance accuracy at the moment when the trailing edge of the sheet passes through the nip portion of the conveyance roller pair, during printing of the same page, Among them, ink jet recording apparatuses capable of reducing, expanding or moving the range of recording elements used for printing are widely known and used in PC printers, facsimiles, multifunction printers, and the like. Therefore, the prior art will be described by taking as an example borderless printing in which the range of recording elements used for printing is frequently reduced, enlarged or moved.

  First, the expansion of the range of recording elements used for printing when performing borderless printing on the leading edge of the sheet will be described with reference to FIG. It is necessary to print on the leading edge rather than the leading edge of the sheet so that a white edge does not remain at the leading edge of the sheet. For this reason, as shown in FIG. 10, a platen ink absorbing material 23 for collecting ink droplets ejected to a position protruding from the front end of the sheet is installed in a recess provided on the sheet passing surface of the platen 6. . Here, since the concave portion is provided on the sheet passing surface of the platen 6, when the width of the concave portion is long in the paper passing direction, when the sheet with the leading end curled downward passes, the leading end greatly falls into the concave portion, It causes a conveyance failure such as jam. In order to prevent this, it is preferable that the width of the concave portion in the paper passing direction is as narrow as possible. However, if the concave portion is narrower than the length of the recording element array, ink droplets ejected to a position protruding from the front end of the sheet pass through the platen 6. Landing on the paper surface, the back surface of the sheet passing therethrough is soiled. Therefore, the width of the concave portion in the paper passing direction is narrowed, and the range of the recording element used when performing borderless printing on the leading edge of the sheet is narrower than the width of the concave portion in the paper passing direction. When the leading edge of the sheet passes through the recording element array and ink droplets no longer protrude from the leading edge of the sheet, the range of recording elements used for increasing the printing speed is expanded to the entire recording element array. Here, as an example, the range of recording elements used when borderless printing is performed on the leading edge of the sheet is limited to about half of the upstream side of the recording element array. The printing method will be described by taking four-pass printing in which printing of the same area is completed by four scans of the carriage 16 as an example. As shown in FIG. 4, from the first scan to the eleventh scan at the start of printing, the sheet is conveyed by 1/8 of the length of the printing element array for each scan. In order to start the expansion of the range of the used recording elements from the twelfth scan, the transport amount is set to ¼ of the length of the recording element array, and the range of the used recording elements is also shifted to the downstream side for each scan. It expands by 1/8 of the length. Thereafter, when the 15th scan is completed, the entire area of the printing element array can be used.

  Next, the reduction of the range of recording elements used for printing when performing borderless printing on the trailing edge of the sheet will be described with reference to FIG. As with borderless printing at the leading edge of the sheet, it is necessary to print on the trailing edge rather than the trailing edge of the sheet so that no white edge remains at the trailing edge of the sheet. Further, as described above, the concave portion of the platen 6 has a width corresponding to about half of the upstream side of the recording element array, and in order to prevent ink droplets from being discharged onto the sheet passing surface of the platen 6, The recording elements used for borderless printing must be reduced from the entire area of the recording element array to about half of the upstream side. As shown in FIG. 5, the sheet is conveyed by 1/4 of the length of the printing element array for each scan until the reduction of the range of printing elements used is started. In order to start reducing the range of the used recording elements from the 89th scan, the transport amount is set to 1/8 of the length of the recording element array, and the range of the used recording elements is also increased upstream of each recording element array. Reduce by 1/8 of the length. After that, when the 92nd scan is completed, the used recording element array becomes about half of the upstream side. Then, after the trailing edge of the sheet passes through the recording element array, printing is finished, and borderless printing is completed.

  Further, in order to alleviate the disturbance of the conveyance accuracy in the scanning at the moment when the trailing edge of the sheet has passed through the nip portion of the conveying roller pair and the subsequent scanning, the trailing edge of the sheet is in the nip of the conveying roller pair. The sheet is transported at a predetermined distance before and after the moment when the trailing edge of the sheet exits the nip portion of the transport roller pair without stopping the printing in the vicinity of passing the section (hereinafter referred to as nozzle shift). Is known to be effective. For this purpose, as shown in FIG. 6, before the nozzle shift is started (71st scan), the used recording elements are reduced to about half of the upstream side of the recording element array. When the trailing edge of the sheet reaches 5/16 upstream of the length of the recording element array from the nip portion, the sheet is conveyed by 5/8 of the length of the recording element array by the nozzle shift operation. The trailing edge is discharged from the nip portion (72nd scan). The recording elements used at this time have moved to about half of the downstream side of the recording element array. Thereafter, in preparation for borderless printing at the trailing edge of the sheet, the used recording element is moved from about half on the downstream side of the recording element array to about half on the upstream side of the recording element array. This can be realized by moving the used recording element upstream by 1/8 of the length of the printing element array for each scan of the carriage 16 without carrying the sheet (73 to 76 scans).

  The above-described number of scans and reduction / enlargement magnification of the used recording element array are merely examples, and are different from actual ones.

  However, with the recent reduction in the size of ink droplets, more accurate ink droplet landing is required, and in the above-described conventional technology, the range of recording elements used for printing is reduced, expanded, or moved. Since the scanning is performed continuously, the recording element to be used is rapidly changed. Furthermore, since the recording elements have slightly different ink ejection speeds, ejection directions and ejection amounts, it seems that different recording heads were used before and after the reduction, expansion or movement of the recording element range used for printing. May cause a difference in color and the like, leading to a decrease in print quality.

  SUMMARY An advantage of some aspects of the invention is that it enables high-quality printing on the entire surface of a recording medium in an inkjet recording apparatus.

  In order to solve the problems in the conventional example, in the ink jet recording apparatus, the range of the recording element used for printing is reduced, enlarged or reduced from the start to the completion of the range, expansion or movement of the recording element used for printing. By providing a scan that does not involve a moving operation, the recording elements to be used are changed gradually.

  As a result, it is possible to alleviate the rapid change in color before and after the reduction, expansion or movement of the range of recording elements used for printing, and high-quality printing on the entire surface of the recording medium becomes possible.

  As described above, according to the present invention, the range of recording elements used for printing can be reduced, expanded or reduced from the start to the completion of the range of recording elements used for printing in the inkjet recording apparatus. By providing a scan that does not involve a moving operation, the recording elements to be used are changed gradually.

  As a result, it is possible to alleviate a sudden change in color before and after the reduction, expansion, or movement of the recording element array used for printing, and high-quality printing on the entire surface of the recording medium becomes possible.

(First embodiment of the invention)
The ink jet recording apparatus according to the embodiment of the present invention will be described below.

  The ink jet recording apparatus according to the present embodiment can be applied to a copying machine, a facsimile, and the like, and is not limited to being applied only to a PC printer.

  First, a schematic configuration of the entire apparatus will be described with reference to FIGS. The schematic configuration of the entire apparatus is the same in the present invention and the conventional example.

  The pressure plate 2 of the sheet feeding device 1 is rotatably supported by the sheet feeding device frame 3, and a sheet bundle is stacked on the upper surface thereof. At the time of sheet feeding, the sheet feeding roller 5 is rotated by a sheet feeding motor 4 as a driving source, and the pressure plate 2 is rotated toward the sheet feeding roller 5 by a pressure plate spring 7 so that the sheet bundle is pressed against the sheet feeding roller 5. . Further, when the sheet feeding roller 5 rotates, only the uppermost sheet of the sheet bundle is separated and fed downstream.

  The sheet separated and fed by the sheet feeding device 1 is fed to the conveying roller 8 by further rotation of the sheet feeding roller 5.

  Here, the leading edge of the sheet separated and fed by the sheet feeding device 1 rotates the sensor lever 9 by pressing the sensor lever 9 disposed between the sheet feeding roller 5 and the conveying roller 8, and further the sheet sensor. The leading edge of the sheet is detected when the sensor lever 9 comes off from 10. The detection of the trailing edge of the sheet is performed when the sensor lever 9 enters the sheet sensor 10.

  Then, based on the detection result of the leading edge of the sheet, the sheet roller 5 conveys a predetermined amount, and the conveyance roller 8 and the pinch roller 12 urged against the conveyance roller 8 by the pinch roller spring 11 contact each other. The leading edge of the sheet is bent by being abutted against the nip formed by the sheet feeding and further conveyed by a predetermined amount by the sheet feeding roller 5, and the leading edge of the sheet is pressed against the nip, and the registration operation is completed. Here, in order to keep the sheet interval constant, the center of the pinch roller 12 is offset downstream from the center of the conveying roller 8, and the sheet is pressed against the upper surface of the platen 6.

  After completion of the registration operation, the sheet is conveyed onto the platen 6 by the conveying roller 8 and is held by the upper surface of the platen 6 at a position facing the recording element array surface of the recording head 13. The conveyance roller 8 is rotated via a conveyance roller gear 15 by a stepping motor 14 that is a driving source.

  Next, printing is performed by the carriage 16 scanning on the sheet supported on the sheet passing surface of the platen 6 while ejecting ink droplets from the recording head 13 mounted on the carriage 16. The carriage 16 is supported by a guide shaft 17 and a guide rail 18 so as to be able to scan, and is driven via a timing belt 20 by driving from a carriage motor 19. Further, in order to improve the printing speed, ink is ejected in both the forward and backward scans of the carriage 16.

  Finally, the printed sheet is discharged out of the apparatus by a discharge roller 21 and a driven spur 22 pressed against the discharge roller 21 by a spur spring (not shown).

  Here, in the case of performing borderless printing that has been generalized in recent years, as shown in FIG. 9, for the actual sheet indicated by the solid line, as indicated by the two-dot broken lines from the four sheet edges, respectively, By performing printing so that only the predetermined amounts α1 to α4 protrude, borderless printing is realized.

  Next, a method for reducing, expanding or moving the range of the recording element used for printing in the present invention will be described in detail. Here, description will be made by taking as an example borderless printing in which the range of recording elements used for printing is frequently reduced, enlarged or moved.

  First, expansion of the range of recording elements used for printing when performing borderless printing on the leading edge of a sheet will be described with reference to FIG. It is necessary to print on the leading edge rather than the leading edge of the sheet so that a white edge does not remain at the leading edge of the sheet. For this reason, as shown in FIG. 10, a platen ink absorbing material 23 for collecting ink droplets ejected to a position protruding from the front end of the sheet is installed in a recess provided on the sheet passing surface of the platen 6. . Here, since the concave portion is provided on the sheet passing surface of the platen 6, when the width of the concave portion is long in the paper passing direction, when the sheet with the leading end curled downward passes, the leading end greatly falls into the concave portion, It causes a conveyance failure such as jam. In order to prevent this, it is preferable that the width of the concave portion in the paper passing direction is as narrow as possible. However, if the concave portion is narrower than the length of the recording element array, ink droplets ejected to a position protruding from the front end of the sheet pass through the platen 6. Landing on the paper surface, the back surface of the sheet passing therethrough is soiled. Therefore, the width of the concave portion in the paper passing direction is narrowed, and the range of the recording element used when performing borderless printing on the leading edge of the sheet is made narrower than the width of the concave portion in the paper passing direction. When the leading edge of the sheet passes through the recording element array and ink droplets no longer protrude from the leading edge of the sheet, the range of recording elements used for increasing the printing speed is expanded to the entire recording element array. Here, as an example, the range of recording elements used when borderless printing is performed on the leading edge of the sheet is limited to about half of the upstream side of the recording element array. The printing method will be described by taking an example of four-pass printing in which printing of the same area is completed by four carriage scans. As shown in FIG. 1, from the first scan to the eleventh scan at the start of printing, the sheet is conveyed by 1/8 of the length of the printing element array for each scan. Then, from the 12th scan, expansion of the range of the used recording element is started. In the twelfth scan, after the sheet is conveyed by a predetermined amount, printing is performed by expanding the range of the used recording elements to the downstream side by 1/8 of the length of the recording element array. Next, in the thirteenth scan, printing is performed without enlarging the range of the used recording elements after the sheet is conveyed by a predetermined amount. After that, a scan that expands the range of the used recording elements downstream by 1/8 of the length of the recording element array and a scan that does not expand the range of the used recording elements are repeated, and when the 18th scan is completed. The entire area of the printing element array can be used.

  Next, the reduction in the range of recording elements used for printing when performing borderless printing on the trailing edge of the sheet will be described with reference to FIG. As with borderless printing at the leading edge of the sheet, it is necessary to print on the trailing edge rather than the trailing edge of the sheet so that no white edge is left at the trailing edge of the sheet. Further, as described above, the concave portion of the platen has a width corresponding to about half of the upstream side of the recording element array, and in order to prevent ink droplets from being discharged onto the sheet passing surface of the platen, The recording element used for borderless printing must be reduced from the entire area of the recording element array to about half of the upstream side. As shown in FIG. 7, the reduction of the range of the used recording elements is started from the 86th scan. In the 86th scan, after a predetermined amount of the sheet is conveyed, printing is performed by reducing the range of the used recording elements to the upstream side by 1/8 of the length of the recording element array. Next, at the 87th scan, after the sheet is conveyed by a predetermined amount, printing is performed without reducing the range of the used recording element. After that, a scan that reduces the range of the used recording elements to the upstream side by 1/8 of the length of the recording element array and a scan that does not reduce the range of the used recording elements are repeated, and when the 92nd scan is completed. The used recording element array is about half of the upstream side. Then, after the trailing edge of the sheet passes through the recording element array, printing is finished, and borderless printing is completed.

  Further, in order to alleviate the disturbance of the conveyance accuracy in the scanning at the moment when the trailing edge of the sheet has passed through the nip portion of the conveying roller pair and the subsequent scanning, the trailing edge of the sheet is in the nip of the conveying roller pair. The sheet is transported at a predetermined distance before and after the moment when the trailing edge of the sheet passes through the nip portion of the transport roller pair without stopping the printing in the vicinity of passing through the section (hereinafter referred to as nozzle shift). Is known to be effective. For this purpose, as shown in FIG. 8, before the nozzle shift is started (71st scan), the used recording elements are reduced to about half of the upstream side of the recording element array. When the trailing edge of the sheet reaches 5/16 upstream of the length of the recording element array from the nip portion, the sheet is conveyed by 5/8 of the length of the recording element array by the nozzle shift operation. The trailing edge is discharged from the nip portion (72nd scan). The recording elements used at this time have moved to about half of the downstream side of the recording element array. Thereafter, in preparation for borderless printing at the trailing edge of the sheet, the used recording element is moved from about half on the downstream side of the recording element array to about half on the upstream side of the recording element array. This is a scan in which printing is performed by moving the used recording element by 1/8 of the length of the printing element array without performing sheet conveyance, and scanning in which printing is performed without moving the used recording element. This can be realized by repeating (73 to 79 scans).

  Here, the above-described number of scans and reduction / enlargement magnification of the range of recording elements used are merely examples, and various patterns are conceivable in practice.

  As described above, from the start to the completion of the recording element range used for printing, from the start to the completion of the recording element range, the scanning that does not involve the reduction, enlargement or movement operation of the recording element range used for printing. By alternately providing the recording elements, the recording elements to be used are gradually changed.

  As a result, it is possible to alleviate a sudden change in color before and after the reduction, expansion, or movement of the recording element array used for printing, and high-quality printing on the entire surface of the recording medium becomes possible.

(Second embodiment of the invention)
In the first embodiment, after a scan involving a reduction, enlargement, or movement operation of a recording element range used for printing, a scan that does not involve a reduction, enlargement, or movement operation of a recording element range used for printing is continuously performed. By providing a plurality of times, the recording element to be used is changed more gradually. Further, the number of scans that do not involve the reduction, expansion, or movement of the recording element range used for printing can be maximized from the start to the completion of the reduction, expansion, or movement of the recording element range used for printing. By calculating from the correct printing range, it is possible to change the optimum recording element to be used.

  As a result, it is possible to alleviate a sudden change in color before and after the reduction, expansion, or movement of the recording element array used for printing, and high-quality printing on the entire surface of the recording medium becomes possible.

(Third embodiment of the invention)
In the first and second embodiments, scanning without reduction, enlargement, or movement of the range of recording elements used for printing is provided after scanning that involves reduction, enlargement, or movement of the range of recording elements used for printing. By setting the optimum number of times according to the paper type and print density, it is possible to change the optimum recording element to be used.

  As a result, it is possible to alleviate a sudden change in color before and after the reduction, expansion, or movement of the recording element array used for printing, and high-quality printing on the entire surface of the recording medium becomes possible.

(Fourth embodiment of the invention)
Even in an ink jet recording apparatus that does not have a discharge roller pair and cannot perform borderless printing on the trailing edge of the sheet, the sheet leading edge is expanded in the range of recording elements used for printing described in the first to third embodiments. By applying, it is possible to obtain the same effect.

It is a figure which shows the expansion procedure of the range of the recording element used for the printing in the Example of this invention. 1 is a perspective view of an ink jet recording apparatus showing an embodiment of the present invention. 1 is a side sectional view of an ink jet recording apparatus showing an embodiment of the present invention. It is a figure which shows the expansion procedure of the range of the recording element used for printing in a prior art example. It is a figure which shows the reduction procedure of the range of the recording element used for printing in a prior art example. It is a figure which shows the movement procedure of the range of the recording element used for printing in a prior art example. It is a figure which shows the reduction procedure of the range of the recording element used for the printing in the Example of this invention. It is a figure which shows the movement procedure of the range of the recording element used for the printing in the Example of this invention. It is a figure which shows the image formation range at the time of borderless printing in the Example of this invention. It is a sectional side view which shows the platen and platen ink absorber in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feeder 2 Pressure plate 3 Paper feeder frame 4 Paper feed motor 5 Paper feed roller 6 Platen 7 Pressure plate spring 8 Conveyance roller 9 Sensor lever 10 Sheet sensor 11 Pinch roller spring 12 Pinch roller 13 Recording head 14 Stepping motor 15 Conveyance roller gear 16 Carriage 17 Guide shaft 18 Guide rail 19 Carriage motor 20 Timing belt 21 Discharge roller 22 Driven spur 23 Platen ink absorber

Claims (8)

A recording means including a recording head having at least one recording element array in which a plurality of recording elements are arranged in a predetermined direction;
A recording medium conveying means that is located upstream of the recording area by the recording head and comprises at least a pair of rollers;
A recording medium discharging means that is located downstream of the recording area of the recording head and comprises at least a pair of rollers;
Reduction of the range of recording elements to be used in the recording element array by repeating the recording medium conveyance by the recording medium conveying means or the recording medium discharging means, or by repeating the recording on the recording medium by the recording means, Use recording element range changing means for enlarging or moving;
Detecting means for detecting a leading edge and a trailing edge of the recording medium;
In an inkjet recording apparatus comprising:
Recording medium by the recording medium conveying means or the recording medium discharging means without reducing, expanding or moving the range of the recording element to be used from the start to the completion of the reduction, expansion or movement of the recording element range to be used An ink jet recording apparatus, wherein the recording means performs recording on the recording medium.   From the start of the reduction, expansion or movement of the range of the recording elements to be used to the completion of the movement, the recording medium conveying means or the recording medium ejecting means which is accompanied by reduction, expansion or movement of the range of the recording elements to be used. Conveyance or recording on a recording medium by the recording means, and recording medium conveyance or recording medium by the recording medium conveying means or the recording medium discharging means without reducing, expanding or moving the range of the recording elements to be used. 2. The ink jet recording apparatus according to claim 1, wherein recording on a recording medium by means is alternately performed.   From the start of the reduction, expansion or movement of the range of the recording elements to be used to the completion of the movement, the recording medium conveying means or the recording medium ejecting means which is accompanied by reduction, expansion or movement of the range of the recording elements to be used. After the recording or recording on the recording medium by the recording means is performed once, the recording medium conveying means or the recording medium discharging means without the reduction, expansion or movement of the range of the recording elements to be used is recorded. 2. The ink jet recording apparatus according to claim 1, wherein a printing operation is repeatedly performed for carrying or recording on the recording medium by the recording means a plurality of times.   The number of times the recording medium is conveyed by the recording medium conveying means or the recording medium ejecting means without reducing, expanding or moving the range of the recording element to be used, or the recording means continuously records on the recording medium. 4. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is calculated from a recording range required from the start to the completion of the reduction, expansion or movement of the range of the recording element to be used.   The number of times the recording medium is conveyed by the recording medium conveying means or the recording medium ejecting means without reducing, expanding or moving the range of the recording element to be used, or the recording means continuously records on the recording medium. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is different depending on a type of the recording medium.   The number of times the recording medium is conveyed by the recording medium conveying means or the recording medium ejecting means without reducing, expanding or moving the range of the recording element to be used, or the recording means continuously records on the recording medium. 4. The ink jet recording apparatus according to claim 1, wherein the recording density varies depending on the recording density on the recording medium.   The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is capable of borderless printing. A recording means including a recording head having at least one recording element array in which a plurality of recording elements are arranged in a predetermined direction;
A recording medium conveying means that is located upstream of the recording area by the recording head and comprises at least a pair of rollers;
Used recording element range changing means for expanding the range of recording elements to be used in the recording element array by repeating the recording medium conveyance by the recording medium conveying means and recording on the recording medium by the recording means a plurality of times. When,
Detecting means for detecting a leading edge and a trailing edge of the recording medium;
In an inkjet recording apparatus comprising:
From the start to the end of expansion of the range of recording elements to be used, recording medium conveyance by the recording medium conveyance means and recording on the recording medium without the expansion of the range of recording elements to be used are performed. An ink jet recording apparatus.

Images