JP3826946B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus, and more particularly to a technique for repairing a recording defect caused by an image recording element of an ink jet recording apparatus or other image recording apparatus that records an image on a recording medium using a recording head having a plurality of image recording elements.

  An inkjet image recording apparatus has an inkjet head (printing head) in which a large number of nozzles are arranged, and ejects ink from the nozzles while relatively moving the printing head and the recording medium. An image is formed on.

  In such an ink jet system, ink may not be ejected due to nozzle clogging of the print head or dirt on the meniscus surface of the ink, and the flying direction of the ejected ink may not be normal. Sometimes. Such printing leakage is not noticeable due to the large multiplicity in the shuttle scan method, but in the case of a line head, the printing defect unevenness becomes remarkable.

  Therefore, various methods for repairing such printing defects have been proposed. For example, in an image recording apparatus that records an image by the dot matrix method, when recorded paper is switched back while shifting a predetermined amount in the width direction, and there is a printing defect, It is known to repair printing defects by printing dot data to be printed using only normal dot printing elements that are separated from each other by a predetermined amount (for example, see Patent Document 1) ). At this time, the predetermined amount is, for example, an integral multiple of the dot interval, and when there is no printing defect, the recording paper is discharged as it is without repairing the printing defect.

  Also known is a line type ink jet printer which has a means for detecting a nozzle defect, and when the nozzle of the line head has a defect, an image is formed using an auxiliary head attached to the line head. (See, for example, Patent Document 2).

Furthermore, in the barcode recording apparatus that records the barcode by discharging ink from a plurality of nozzles provided in the recording head, it has means for detecting unhealthy nozzles of the recording head, and detects unhealthy nozzles. In such a case, the barcode recording position is recorded such that the barcode recording position is shifted, rotated 90 °, or rotated 90 ° and shifted (for example, patents). Reference 3 etc.).
Japanese Patent Laid-Open No. 9-24627 Japanese Patent Laid-Open No. 11-334047 JP 2003-145734 A

  However, in the one described in Patent Document 1 or the like, the recorded paper that has been printed once is switched back to detect printing failure and determine whether to reprint. Regardless, there is a problem that productivity is poor because the recording paper always moves back and forth the print head. Furthermore, since printing is performed using only normal dot printing elements that are separated from the defective dot printing elements by a predetermined amount, printing defects are completely repaired due to the effect of skew of the recording paper. There is a problem that is not always.

  In addition, in the device described in Patent Document 2 and the like, there is a problem that the apparatus configuration is wasteful because an auxiliary head provided in addition to the normal line head is required for each color. Further, in the device described in Patent Document 3 or the like, when an unhealthy nozzle is detected, the barcode recording position is shifted or rotated by 90 ° with respect to the next barcode recording. It is intended to avoid printing defects such as white streak in advance, and there is no concept of reprinting or repairing a recording medium that has a printing defect. There is a problem of being wasted.

  The present invention has been made in view of such circumstances. Even if a recording failure such as a missing image occurs due to a defect in an image recording element such as nozzle clogging, a recording failure is not caused without wasting the recording medium. An object of the present invention is to provide an image recording apparatus capable of reliably repairing the image.

To achieve the above object, a first aspect of the present invention, a full-line type recording head and the recording medium in which a plurality of image recording elements arranged over a length corresponding to the entire width of the recording medium is cut sheet An image recording apparatus for recording an image on the recording medium by the recording head while transporting at least one of them in a direction substantially perpendicular to the width direction of the recording medium and relatively moving the recording head and the recording medium. And means for detecting defective pixels in the image recorded on the recording medium by the recording head, and a recording medium in which the defective pixels are detected when the defective pixels are detected in the image recorded on the recording medium. a position again recorded by the recording head, and transport means for transporting a different transport path from the transport path when initially recording an image on said recording medium, said conveying means Provided in the middle of the conveying path, a buffer for temporarily stocking a recording medium in which the defective pixel is detected, prior to recording medium in which the defective pixel is detected again recorded by the recording head, the defect A unit for detecting a pixel position; and a standby unit for storing the recorded recording medium in which a defective pixel has not been detected, provided in a discharge unit for discharging the recorded recording medium . When performing image recording, the recording medium in which defective pixels are not detected is stored in the standby unit, and the recording medium in which defective pixels are detected is temporarily stored in the buffer, and stored in the buffer. It has been conveyed to a position wherein the recording recording medium again, the pixels of the detected defective pixel position, by moving at least one of the recording medium and the recording head, Image recording is performed again using an image recording element different from the image recording element that records the defective pixels, or the image recording element that records the defective pixels is recovered and the image is recorded again. after the Tsu row repair defective pixels, collectively recorded recording medium of the repaired recording medium united with the recording medium in which the defective pixel is not detected to have been stored in the standby section 1 order of magnitude The image recording apparatus is characterized in that it is discharged .
As described above, according to the present invention, after image recording, defective pixels are detected, and only the recording medium in which the defective pixels are detected is transported to the recording position again, and the defective pixel position is detected again when recording again. Since the defective pixel is repaired, it is possible to accurately repair the defective portion. Further, if there is a recording medium in which defective pixels are detected at this time, even if only the recording medium having this defect is transported to the recording position again and recorded again, the recording medium for one order is correctly aligned. Can be output collectively.

Similarly, in order to achieve the above object, the invention according to claim 2 is a full-line type recording head in which a plurality of image recording elements are arranged over a length corresponding to the entire width of a recording medium which is roll paper. And recording the image on the recording medium by the recording head while relatively moving the recording head and the recording medium by conveying at least one of the recording medium in a direction substantially orthogonal to the width direction of the recording medium. A recording apparatus comprising: means for detecting defective pixels of an image recorded on the recording medium by the recording head; and cutting the recording medium that is the roll paper provided on the downstream side in the transport direction with respect to the recording head. A loop portion for storing the recording medium for one order formed between the recording head and the cutter, and a recording medium for one order. When a defective pixel is detected in the recorded image, the recording medium in which the defective pixel is detected is transported so as to return to the upstream side in the transport direction with respect to the recording head in order to record an image again by the recording head. And a means for detecting the position of the defective pixel prior to image recording of the recording medium in which the defective pixel is detected by the recording head again in the recording medium for one order. When an image having defective pixels is detected, the one-order recording medium in which a loop portion is formed on the downstream side of the recording head is returned to the upstream side of the recording head, and then the upstream side of the recording head. By forming a loop portion composed of a recording medium for one order and recording the image again while transporting the recording medium having the loop portion to the recording head again. After repairing the pixel Recessed provides an image recording apparatus characterized collectively by the cutter to discharge cut for each image of the recording medium 1 order of magnitude.
  As a result, when an image is recorded on a roll-shaped recording medium, even if there is an image in which defective pixels are detected, after the defect is repaired, the images for one order can be discharged together without being separated. it can.

  In the present invention, it is preferable that pixels around the defective pixel are interpolated and printed when the recording medium is recorded again by the recording head. At this time, it is preferable that the pixels around the defective pixel are interpolated and printed at a lighter density than in the previous recording. Thereby, the visibility of a restoration part can be improved.

  The present invention further includes means for changing a relative position of the recording medium and the recording head in the arrangement direction of the image recording elements when the recording medium is recorded again by the recording head. To do. Thereby, it is possible to quickly repair the defective pixel without performing the recovery operation of the defective image recording element.

  As described above, according to the image recording apparatus of the present invention, even if a recording defect such as a missing image occurs in a recorded image on the recording medium due to a defect in the image recording element, the recording defect is not wasted. Can be reliably repaired.

  Hereinafter, an image recording apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of an image recording apparatus according to the present invention. The image recording apparatus according to the first embodiment shown in FIG. 1 is a line-type inkjet printer in which a plurality of nozzles (image recording elements) that eject ink toward a recording medium are arranged in a straight line. A recording medium (roll paper) is cut to a predetermined length according to a print (image) to be created to form a cut sheet, and then image recording is performed by an inkjet method.

  As shown in FIG. 1, an image recording apparatus (inkjet printer) 10 generally includes a recording unit 12 having a plurality of recording heads 12K, 12C, 12M, and 12Y provided for each ink color, and each recording unit. An ink storage / loading unit 14 that stores ink to be supplied to the heads 12K, 12C, 12M, and 12Y, a paper feeding unit 18 that supplies recording paper (recording medium) 16, and a nozzle surface (ink ejection) of the recording unit 12 A suction belt transport unit 20 that transports the recording paper 16 while maintaining the flatness of the recording paper 16, and a discharge unit 22 that discharges the recorded recording paper (printed matter). ing.

  The recording unit 12 is a so-called full line type head in which a line type head having a length corresponding to the maximum paper width is arranged in a direction (main scanning direction) substantially orthogonal to the paper feeding direction (sub scanning direction). Yes. Here, the main scanning direction and the sub-scanning direction are accurately defined as follows. That is, when driving the nozzles with a full line head having a nozzle row corresponding to the full width of the recording paper, (1) whether all the nozzles are driven simultaneously or (2) whether the nozzles are driven sequentially from one side to the other (3) The nozzles are divided into blocks, and each nozzle is driven sequentially from one side to the other for each block, and the width direction of the paper (perpendicular to the conveyance direction of the recording paper) Nozzle driving that prints one line (a line made up of a single row of dots or a line made up of a plurality of rows of dots) in the direction of scanning is defined as main scanning. A direction indicated by one line or one strip line (longitudinal direction of the strip region) recorded by the main scan is referred to as a main scan direction.

  On the other hand, it is defined as sub-scanning that the above-described full-line head and recording paper are moved relative to each other so that one line or one band-like printing formed by the main scanning is repeated. A direction in which sub-scanning is performed is referred to as a sub-scanning direction. After all, the conveyance direction of the recording paper is the sub-scanning direction, and the direction orthogonal to it is the main scanning direction.

  Although a detailed description of the structure is omitted, each of the recording heads 12K, 12C, 12M, and 12Y has an ink discharge port (over the length exceeding at least one side of the maximum size recording paper 16 that is the target of the image recording apparatus 10). Nozzle) is composed of a line type head in which a plurality of nozzles are arranged.

  The recording head 12 prints each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction (paper transport direction) of the recording paper 16 indicated by an arrow in the figure. The recording heads 12K, 12C, 12M, and 12Y corresponding to are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the recording heads 12K, 12C, 12M, and 12Y while conveying the recording paper 16.

  As described above, according to the recording unit 12 in which the full line head covering the entire paper width is provided for each ink color, the operation of relatively moving the recording paper 16 and the recording unit 12 in the sub-scanning direction is performed. An image can be recorded on the entire surface of the recording paper 16 only by performing it once (that is, in one sub-scan). Thereby, it is possible to perform high-speed recording as compared with a shuttle type head that reciprocates in the main scanning direction of the recording head, and it is possible to improve productivity.

  In the illustrated example, KCMY standard colors (four colors) are configured. However, combinations of ink colors and the number of colors are not limited to the present embodiment, and light ink and dark ink are used as necessary. May be added. For example, a recording head that discharges light ink such as light cyan and light magenta may be added.

  The ink storage / loading unit 14 includes tanks that store inks of colors corresponding to the recording heads 12K, 12C, 12M, and 12Y. The tanks store the recording heads 12K, 12C, 12M, 12Y is communicated.

  The recording paper 16 is supplied by the paper supply unit 18. In FIG. 1, magazines 24a and 24b loaded with roll paper (continuous paper) 16R formed by winding recording paper 16 in a roll shape as the paper supply unit 18 are shown. Roll paper 16R having different paper width, paper quality, etc. may be loaded and used. Further, instead of or in combination with the magazines 24a and 24b of the roll paper 16R, the recording paper 16 may be supplied by a cassette in which cut sheets are stacked and loaded. When cut paper is used, the cassette is disposed between the cutters 28 a and 28 b and the recording unit 12. The magazines 24a and 24b are not limited to two, and may be one or more than two.

  For each of the magazines 24a and 24b, drawing rollers 26a and 26b for pulling out the recording paper 16 from the magazines 24a and 24b, and cutters 28a and 28b for cutting the drawn recording paper 16 to a predetermined length are installed. ing. In addition, when using cut paper, the cutters 28a and 28b are unnecessary. The recording paper 16 drawn from the magazines 24a and 24b by the drawing rollers 26a and 26b and cut to a predetermined length by the cutters 28a and 28b is sent to the suction belt conveyance unit 20 by the recording paper conveyance unit having a large number of conveyance rollers. It is supposed to be.

  The suction belt conveyance unit 20 has a structure in which an endless belt 32 is wound between rollers 30 and 31 so that at least a portion facing the nozzle surface of the recording unit 12 forms a flat surface. It is configured. The belt 32 has a width that is greater than the width of the recording paper 16, and a plurality of suction holes are formed on the belt surface. Further, an adsorption chamber 34 is provided at a position facing the nozzle surface of the recording unit 12 inside the belt 32 spanned between the rollers 30 and 31, and the adsorption chamber 34 is sucked by a suction fan 35. Thus, the recording paper 16 on the belt 32 is attracted and held by the belt 32 by setting the negative pressure.

  The discharge unit 22 has a large number of shelves 22a and moves up and down as indicated by arrows in the figure, and the recorded recording paper 16 is distributed to the shelves 22a, for example, for each order (each). It is constituted by what is called a sorter that stores the Here, one order is a unit of an order from a customer, which is also referred to as one case, and is, for example, one photographic film made up of 20 frames. As will be described later, in the present embodiment, the discharge unit 22 also serves as a standby unit for temporarily storing recorded recording paper. The image recording apparatus (inkjet printer) 10 of this embodiment has a configuration unique to the present invention as described below, in addition to the normal configuration as described above.

  That is, first, defective pixel detection means 36 for detecting whether there is a defective pixel in the image recorded on the recording paper 16 on the downstream side in the transport direction of the recording paper 16 indicated by an arrow in the drawing with respect to the recording unit 12. Is provided. The defective pixel detection means 36 is not particularly limited as long as it can detect a defective pixel. For example, non-ejection detection means for detecting that ink has not been ejected from the nozzles immediately after recording may be used, or a recorded image may be read by a line sensor and a defective nozzle may be determined from missing images.

  Further, as shown in the figure, one defective pixel detection means 36 may be provided for the entire recording heads 12K, 12C, 12M, and 12Y, but for each recording head 12K, 12C, 12M, and 12Y. You may make it provide in.

  At this time, if no defective pixel is detected, the recording paper 16 with good recording is stored as it is in one shelf 22a of the discharge unit (sorter) 22, and the processing for one order including the recording image is completed. Until it is stored there. In this manner, the discharge unit (sorter) 22 constitutes a standby unit for the recording paper 16 with good recording in which no defective pixel is detected. The standby unit does not necessarily have to be shared by the discharge unit 22 as described above. Of course, the standby unit and the discharge unit may be separate units.

  In addition, after recording, the recording paper 16 in which defective pixels are detected is repaired by recording the defective pixels again in order to eliminate waste of the recording paper 16. Therefore, a transport unit 38 is provided for transporting the recording paper 16 having defective pixels again to the recording unit 12. When the defective pixel detection unit 36 detects a defective pixel, the conveyance unit 38 receives the detection signal, changes the conveyance direction of the recording paper 16 by the conveyance path switching unit 39, and detects the defective recording pixel 16. Is conveyed again to the recording unit 12.

  Note that the conveyance path through which the conveyance unit 38 conveys the recording paper 16 to the recording unit 12 may constitute a completely different path from the conveyance path at the time of normal recording, or the conveyance path at the time of recording in the reverse direction. Alternatively, the recording paper 16 may be passed under the recording head. Further, when the number of recording papers 16 in which defective pixels are detected is large, in order to reduce the processing load on the recording unit 12 caused by returning them to the recording unit 12 at a time, the conveyance unit 38 is in the middle of the conveyance path. The recording paper 16 to be returned to the recording unit 12 may be temporarily stocked by providing a buffer 40.

  Further, a transport path switching unit 41 is provided in the preceding stage of the recording unit 12. The conveyance path switching means 41 is for inserting the recording paper 16 conveyed to the recording unit 12 by the conveyance means 38 into the conveyance path at the time of recording again. Similarly, in the preceding stage of the recording unit 12, the relative movement for changing the relative movement direction of the recording paper 16 inserted into the conveyance path at the time of recording by the conveyance path switching unit 41 with respect to the recording heads 12K, 12C, 12M, and 12Y. Direction changing means 42 is provided.

  If the recording paper 16 is moved relative to the recording heads 12K, 12C, 12M, and 12Y in the same manner as the previous time, the defective pixels are recorded again by the nozzle having the same defect as the previous time. I can't. Therefore, the relative movement direction changing unit 42 changes the relative movement direction of the recording paper 16 with respect to the recording heads 12K, 12C, 12M, and 12Y, and records defective pixels with other nozzles different from the previous one, thereby detecting defective pixels. It is intended to repair.

  In addition, a defective pixel position detecting unit 44 that detects a defective pixel position of the recording paper 16 having a defective pixel that needs to be recorded again is installed in the preceding stage of the recording unit 12. The defective pixel position detecting means 44 may also be one that, for example, reads a recorded image with a line sensor and determines the position of a defective nozzle from the missing image, like the defective pixel detecting means 36 described above. Thereby, the position of the defective pixel can be accurately grasped, and the recording unit 12 can perform recording so that the defective pixel can be reliably repaired by converting the image data in accordance with this.

  The recording paper 16 in which defective pixels are repaired in this way is sent to a discharge unit (sorter) 22. In the discharge unit 22, the repaired recording paper 16 is combined with the recorded paper 16 of the same order stored in the discharge unit 22, and is discharged as one order.

  FIG. 2 shows a plan view of the vicinity of the printing unit 12. As shown in FIG. 2, each of the print heads 12K, 12C, 12M, and 12Y has an ink ejection port (nozzle) extending over a length exceeding at least one side of the maximum size recording paper 16 targeted by the inkjet recording apparatus 10. Is composed of a full line type head in which a plurality of are arranged.

  As a defect recovery means of the image recording element, for example, as shown in FIG. 2, a maintenance unit including a cap 64 and a blade 66 is disposed at a position where the print head 12K (12C, 12M, 12Y) on the side of the belt 32 is not present. In the recovery, the print head 12K (12C, 12M, 12Y) is moved to the position of the maintenance unit, and the print head 12K (12C, 12M, 12Y, hereinafter, the print head is represented by reference numeral 50) is the blade 66. The defect can be recovered by wiping the print head 50 or attaching the cap 64 to the print head 50 and sucking ink from the print head 50 by the suction pump 67.

  At this time, the cap 64 may be common to all colors or may be individually provided for each color.

  In addition, a defective pixel position detecting unit 44 is disposed in front of the print head 50, and a relative movement direction changing unit 42 is disposed in front of the defective pixel position detecting unit 44. The relative movement direction changing means 42 moves in a direction substantially perpendicular to the movement direction of the recording paper 16 as indicated by an arrow F in the figure to change the relative movement direction of the recording paper 16.

  As a means for moving the relative movement direction changing means 42, for example, the motor 43a, the linear scale 43b, and the linear scale reading detector 43c can be combined with high accuracy for positioning. Thus, since the recording paper 16 can be moved in the direction perpendicular to the traveling direction, recording can be performed with an image recording element different from the previous one, and defective pixels can be reliably repaired.

  3 shows a cross-sectional view of a maintenance unit including a cap 64, a blade 66, and the like, and an outline of an ink supply system along the line AA in FIG.

  In FIG. 3, an ink tank 60 is a base tank for supplying ink to the print head 50, and is installed in the ink storage / loading unit 14 described with reference to FIG. There are two types of the ink tank 60: a method of replenishing ink from a replenishing port (not shown) and a cartridge method of replacing the entire tank when the remaining amount of ink is low. When the ink type is changed according to the usage, the cartridge method is suitable. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. 3 is equivalent to the ink storage / loading unit 14 shown in FIG. 1 described above.

  As shown in FIG. 3, a filter 62 is provided in the middle of the conduit connecting the ink tank 60 and the print head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter of the print head 50 (generally, about 20 μm).

  Although not shown in FIG. 3, a configuration in which a sub tank is provided in the vicinity of the print head 50 or integrally with the print head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface 50A.

  The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the print head 50 by a moving mechanism (not shown), and moves from a predetermined retracted position to a maintenance position below the print head 50 as necessary. You may do it.

  The cap 64 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The lifting mechanism is configured to cover the nozzle region of the nozzle surface 50 </ b> A with the cap 64 by raising the cap 64 to a predetermined raised position when the power is turned off or waiting for printing, and bringing the cap 64 into close contact with the print head 50.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink ejection surface (nozzle surface 50A) of the print head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matters adhere to the nozzle surface 50A, the nozzle surface 50A is wiped by sliding the cleaning blade 66 on the nozzle surface 50A to clean the nozzle surface 50A.

  During printing or standby, when a specific nozzle 51 is used less frequently and the ink viscosity in the vicinity of the nozzle 51 is increased, preliminary ejection toward the cap 64 is performed to discharge the ink that has deteriorated due to the increased viscosity. Is done.

  In addition, when bubbles are mixed in the ink in the print head 50 (ink in the pressure chamber 52), the cap 64 is applied to the print head 50, and the ink in the pressure chamber 52 (ink in which bubbles are mixed) is applied by the suction pump 67. The ink removed by suction is sent to the collection tank 68. This suction operation is also performed when the initial ink is loaded into the head or when the ink is used after being stopped for a long time, and the deteriorated ink solidified by increasing the viscosity is sucked and removed.

  That is, if the print head 50 does not discharge for a certain period of time, the ink solvent in the vicinity of the nozzles evaporates and the viscosity of the ink in the vicinity of the nozzles increases, and pressure generation means (not shown) for discharge driving is provided. Ink does not discharge from the nozzle 51 even if it operates. Therefore, before this state is reached (within the viscosity range in which ink can be ejected by the operation of the pressure generating means), the pressure generating means is operated toward the ink receiver, and the ink in the vicinity of the nozzle whose viscosity has increased is removed. “Preliminary discharge” is performed. Further, after the dirt on the nozzle surface 50A is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, the foreign matter is prevented from being mixed into the nozzle 51 by this wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  In addition, if bubbles are mixed in the nozzle 51 or the pressure chamber 52 or if the viscosity of the ink in the nozzle 51 exceeds a certain level, ink cannot be ejected by the preliminary ejection. Do.

  That is, when bubbles are mixed in the ink in the nozzle 51 or the pressure chamber 52, or when the ink viscosity in the nozzle 51 rises to a certain level or more, the ink is ejected from the nozzle 51 even if the pressure generating means is operated. become unable. In such a case, an operation in which the cap 67 is applied to the nozzle surface 50 </ b> A of the print head 50 and the ink or the thickened ink in which bubbles in the pressure chamber 52 are mixed is sucked by the pump 67.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 52, the ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible. The cap 64 described in FIG. 3 functions as a suction unit and can also function as a preliminary discharge ink receiver.

  Preferably, the inside of the cap 64 is divided into a plurality of areas corresponding to the nozzle rows by a partition wall, and each of the partitioned areas can be selectively sucked by a selector or the like. The defective nozzle (image recording element) is recovered by the operation of the maintenance unit as described above.

  Hereinafter, the operation of the first embodiment will be described with reference to the flowchart of FIG.

  FIG. 4 is a flowchart showing a flow of processing for repairing a defective pixel as an operation of the image recording apparatus 10 of the present embodiment. Note that the flowchart shown in FIG. 4 shows only processing for one order. In actual work, it is normal to process a plurality of orders, and even if processing for one order is completed. The process does not end, and the process shown in FIG. 4 is repeatedly executed.

  In the first embodiment, the first image recording is performed on a cut sheet (sheet). When each image (frame) in one order is recorded, a defective pixel is detected and there is no defect. The recorded recording paper is stored in the standby unit, and when a defect is detected, the defect pixel is returned to the recording unit 12 and the defective pixel is recorded again by using a nozzle different from that for the first recording. Pixels are repaired and merged with the recording paper stored in the standby unit so that one order is discharged together.

  First, in step S100 of FIG. 4, image recording is performed. When recording an image, the roll paper 16R in the magazine 24a (or 24b) of the paper supply unit 18 is pulled out by the pulling roller 26a (or 26b), and the cut paper having a predetermined length corresponding to the image size is obtained by the cutter 28a (or 28b). The sheet is cut into (sheets) and conveyed to the recording unit 12 by a number of conveying rollers. At the time of the first recording, the relative movement direction changing means 42 and the defective pixel position detecting means 44 do not operate. The sheet-like recording paper 16 conveyed to the recording unit 12 is conveyed by the suction belt conveyance unit 20 while being held by the belt 32 while maintaining a flat shape under the recording heads 12K, 12C, 12M, and 12Y. Images are recorded by the recording heads 12K, 12C, 12M, and 12Y.

  Next, in step S110, it is determined whether there is a defective pixel. This is performed by inspecting the recording paper 16 conveyed in a flat shape by the suction belt conveyance unit 20 by the defective pixel detection means 36.

  If it is determined in step S110 that no defective pixel is detected, the process proceeds to step S120, and a good recorded recording paper 16 having no defective pixel is stored in the standby unit. In this embodiment, since the carry-out unit (sorter) 22 also functions as a standby unit, it is stored in a predetermined shelf 22a of the carry-out unit 22.

  If a defective pixel is detected in step S110, in step S130, the recording paper 16 having the defective pixel is conveyed to the recording unit 12 for image recording again. That is, when the defective pixel detection unit 36 detects a defective pixel, the conveyance path switching unit 39 operates to guide the recording sheet 16 having the defective pixel into the conveyance path of the conveyance unit 38 that conveys the recording sheet to the recording unit 12. Like that.

  The recording paper 16 having defective pixels is conveyed to the recording unit 12 for recording again on the defective pixels, but is stocked in a buffer 40 provided in the middle of the conveying means 38 as necessary. The conveying means 38 conveys the recording paper 16 toward the recording section 12 while timing the image recording of the next recording paper 16 in the recording section 12, and the recording paper 16 to be recorded again by the conveying path switching means 41. It is carried into relative movement direction changing means 42.

  In the next step S140, the defective pixel is repaired by recording the defective pixel again in the recording unit 12. That is, the relative movement direction changing unit 42 changes the relative movement direction of the recording paper 16 to be recorded again from the first movement direction, and the recording paper 16 is moved by the suction belt conveyance unit 20 to the recording heads 12K, 12C, When transported under 12M and 12Y, defective pixels are recorded by nozzles different from those used in the first recording.

  For example, when the recording paper 16 is passed through the recording heads 12K, 12C, 12M and 12Y for the second time, the skew amount of the recording paper 16 with respect to the transport direction is transported so as to be different from the angle at the previous recording and repaired with different nozzles. Make recording (printing). Here, the different angle may be, for example, 90 ° or 180 ° rotation.

  At this time, the defective pixel position of the recording paper 16 can be accurately detected by the defective pixel position detecting means 44 provided immediately before the recording heads 12K, 12C, 12M, and 12Y, so that the defective pixels can be reliably repaired. To.

  Further, the recording unit 12 receives a detection signal from the defective pixel position detecting unit 44 and performs interpolation recording (interpolation) on pixels around the defective pixel (for example, a range of ± 1 to ± 5 pixels with respect to the defective pixel). Printing) may be performed. Further, at this time, the pixels around the defective pixel may be interpolated and recorded so that the density becomes lighter as the distance from the defective pixel position becomes smaller than the previous recording. Alternatively, the pixels around the defective pixel may be recorded widely at a density that is uniformly lower than the density at which the defective pixel is recorded. As means for reducing the density, for example, recording may be performed with dots smaller than the dots of the original image.

  A method of performing recording again on the defective pixel and repairing the defective portion will be specifically described below with reference to the drawings. FIG. 5A shows a graph D of the image density around the defective pixel. In this graph D, the horizontal direction represents the distance in the nozzle row direction (main scanning direction), and the vertical direction represents the image density. Thus, the defective pixel portion K is not printed with a width δ corresponding to one pixel or several pixels.

  On the other hand, the first repair method is a method for reprinting only the defective portion. As shown in FIG. 5 (b), the image pattern M1 having the same density as the original recording pixel by the width δ is accurately recorded on the defective portion, so that a properly restored image graph C1 is obtained. . However, in this case, it is necessary to print accurately within the defective pixel width. Thus, it is difficult to print accurately only at the defective pixel position, and as shown in FIG. It is considered that the graph C1 ′ is shifted by a certain distance. However, even with such a slight deviation, it is considered that there is not much problem in visual recognition because the high frequency cannot be discriminated from density changes and thus appears visually uniform.

  In the next second repair method, as shown in FIG. 5D, a pattern M2 having a peak at the defective portion δ is recorded again so that the reprinting position may be slightly shifted. In practice, the pattern M2 is not as smooth as this, but is a stepped (discrete) pattern that takes each density value for each pixel. As a result, a restoration image density graph such as graph C2 is obtained. In this case, it is possible to repair even if the printing position is slightly shifted, and the allowable width is wider than that of the first repairing method.

  Further, as a third repair method, as shown in FIG. 5E, a predetermined range including the defective portion δ, for example, a range three times the defective portion δ is uniformly reduced in image pattern M3 having a density lower than the previous time. To reprint the defective part. If the width of the image pattern M3 is too wide, defects may be visually recognized. Therefore, it is actually preferably about 2 to 5 times the width of the defective portion. A density graph C3 of the repaired image is obtained by recording the image pattern M3 so as to overlap the defective portion. At this time, if the printing position of the image pattern M3 is slightly shifted, a graph C3 'as shown in FIG. 5 (f) is obtained, but the defect is difficult to visually recognize and there is no particular problem.

  As described above, there are various methods for repairing a defect by reprinting, but the first method is most preferable if recording can be performed accurately. However, it is difficult to completely match the recording positions in this way, and the second and third methods can be sufficiently restored. Moreover, there is no difference in visual recognition between the second and third methods.

  After the recording is performed again on the defective pixels, the repaired recording paper 16 may be sent to the discharge unit 22 without performing the inspection by the defective pixel detecting means 36, or the repaired recording paper 16 Again, the defective pixel detection means 36 performs the inspection again, and if the defective pixel is detected again, it returns to the recording unit 12 again, and this time, the defective pixel is repaired by a method different from the previous one. Also good.

  When the defective pixels are repaired, in the next step S150, the repaired recording paper 16 sent to the discharge unit 22 is the same shelf as the good recording paper 16 having no defective pixels belonging to the same order already stored. It is conveyed to 22a and united.

  Next, in step S160, it is determined whether or not processing for one order has been completed. Although this method is not particularly limited, for example, the number of image frames in one order may be input in advance, and the number of recording sheets 16 carried into the discharge unit 22 may be counted and determined. If the processing for one order has not been completed yet, the processing returns to step S100 and the above processing is repeated.

  When the processing for one order is completed, in the next step S170, the recorded recording paper 16 belonging to one order collected in one shelf 22a of the discharge unit 22 is discharged. As a result, the recording papers 16 on which one-order images are recorded are collected without being separated, and are also neatly arranged and discharged.

  In the above-described example, the repair of the defective pixel is performed by changing the relative movement direction of the recording paper and the recording head when recording again to a direction different from the movement direction in the first recording. Although defective pixels are recorded using a different nozzle from that used for the second recording, the method for repairing defective pixels is not limited to this.

  For example, in the case of a line head, the position at which the recording paper is conveyed to the recording head at the time of re-recording may be moved (shifted) by several nozzles in the direction perpendicular to the conveying direction (main scanning direction). . According to this, since the defective pixel is recorded by the nozzle several nozzles away from the defective nozzle, the defective pixel can be repaired.

  Further, for example, the conveyance direction of the recording paper at the time of the first recording and the second recording may not be the same direction. That is, in the second recording, the recording sheet may be returned as it passes under the recording head in the reverse direction, and the recording may be performed again while returning. In this case, since the defective pixel portion is recorded by the same nozzle as the previous time, it is necessary to perform the recovery operation of the nozzle before re-recording.

  In addition, when performing the recovery operation of the nozzle, when a defective pixel is detected, the recording paper is returned and the recovery operation of the nozzle having the defect is performed, while carrying the same as in the first recording, The defective pixel may be recorded again with the same nozzle that has been repaired. In this case, since the recovery operation of the nozzle must be performed, it takes an extra time for maintenance. However, the recording paper can be simply returned and transported in the same way, and the relative movement can be performed. A sensor for changing the direction or detecting the defective pixel position is not particularly necessary.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 is a schematic configuration diagram showing a second embodiment of the image recording apparatus according to the present invention. The image recording apparatus of the second embodiment shown in FIG. 6 performs the first image recording as roll paper (continuous paper), detects defective pixels for each image frame after image recording, and processes for one order. Until the process is completed, a loop portion is formed and kept waiting without cutting, and when a defective pixel is detected, the recording paper for one order is returned before processing the next order. A loop portion is formed in front of the recording portion, and recording is performed again for the defective pixels, and an image (frame) for one order is collectively cut.

  That is, as shown in FIG. 6, the image recording apparatus 100 includes a recording unit 112 having a plurality of recording heads 112K, 112C, 112M, and 112Y provided for each ink color, and each recording head 112K, 112C, 112M, An ink storage / loading unit 114 that stores ink to be supplied to 112Y, a paper feeding unit 118 that supplies recording paper (recording medium) 116, and a nozzle surface (ink ejection surface) of the recording unit 112 are arranged to face each other. In addition, a suction unit 120 that holds the flatness of the recording paper 116 and a discharge unit 122 that discharges the recorded recording paper (printed matter) 116 are provided.

  These components are basically substantially the same as those of the first embodiment described above. However, in the present embodiment, since image recording is performed with the roll paper, there are some differences. For example, since the paper feeding unit 118 is handled as roll paper, it does not have a cutter that cuts the recording paper 116 into a predetermined length after the recording paper 116 is pulled out from the magazine 124. In addition, since the image recording apparatus 100 according to the present embodiment collectively processes one order of images (frames), the image recording apparatus 100 holds one order of images (frames) until the processing of one order is completed. The loop portions 148 and 150 are formed.

  In the present embodiment, since the recording paper 116 is conveyed in a continuous roll by a large number of conveyance rollers, the adsorption unit 120 includes a suction chamber 134 for holding the roll-shaped recording paper 116 in a flat shape, and A suction fan 135 is provided for sucking the suction chamber 134 to a negative pressure. Further, before and after the recording unit 112, a defective pixel detection unit 136 that detects a defective pixel after image recording and a defective pixel position detection unit 144 that detects a defective pixel position again immediately before recording for repairing the defective pixel are performed. Is provided.

  A loop unit 148 for storing an image (frame) for one order is formed at the subsequent stage of the recording unit 112, and an image for one order is returned and held at the previous stage of the recording unit 112 when recording again. A loop portion 150 is formed. That is, in the present embodiment, the loop unit 148 corresponds to the standby unit. In addition, after the processing for one order is completed, a cutter 146 for cutting together for each order and a discharge unit 122 for storing a recorded image for each order are provided. As in the first embodiment, the discharge unit 122 has a plurality of shelves 122a for storing images for each order, and moves up and down as indicated by arrows in the figure, and is cut for each image (frame). The recording paper 116 is stored.

  Hereinafter, the operation of the second embodiment will be described with reference to the flowchart of FIG.

  FIG. 7 is a flowchart showing a flow of processing for repairing a defective pixel as an operation of the image recording apparatus 100 of the present embodiment. Note that the flowchart of FIG. 7 shows only the processing for one order, similarly to the flowchart of FIG.

  First, in step S200, image recording is performed. For image recording, the roll paper 116R in the magazine 124 of the paper supply unit 118 is pulled out, and the recording paper 116 is conveyed to the recording unit 112 by a number of conveying rollers in a continuous state. During the first recording, the defective pixel position detecting means 144 does not operate. The continuous recording paper 116 conveyed to the recording unit 112 is adsorbed by the adsorption chamber 134 of the adsorption unit 120 and conveyed under the recording heads 112K, 112C, 112M, and 112Y while being held in a flat shape, and the recording head 112K. , 112C, 112M, and 112Y, images are recorded.

  Next, in step S210, defective pixels are detected by the defective pixel detection unit 136 installed at the subsequent stage of the recording heads 112K, 112C, 112M, and 112Y. As a result, when a defective pixel is detected, in the next step S220, information on which frame the defective pixel is detected is held in the control unit (not shown) of the image recording apparatus 100.

  Whether or not a defective pixel is detected, in the next step S230, a loop portion 148 is formed at the subsequent stage of the defective pixel detection means 136, and the cut is not performed until the processing for one order is completed. The continuous recording paper 116 is put on standby.

  In the next step S240, it is determined whether or not processing for one order has been completed. As a result, if the processing for one order has not been completed, the process returns to step S200, and image recording is performed on the next image in the one order.

  When the processing for one order is completed, it is determined whether or not a defective pixel is detected in the next step S250. This is determined because the control unit of the image recording apparatus 100 holds information indicating that a defective pixel is detected together with the frame information. If no defective pixels are detected in one order, the process immediately proceeds to step S270, and images (frames) for one order are cut together.

  On the other hand, if it is determined in step S250 that a defective pixel is detected in the one order, in step S260, the defective pixel is returned by one order, and the defective pixel is recorded again and repaired. That is, first, the recording paper 116 for one order, which has been waiting after forming the loop portion 148 in the subsequent stage of the recording unit 112, is transported back to the previous stage of the recording unit 112, and a loop composed of an image for one order. Part 150 is formed.

  Then, while passing the recording paper 116 from the loop unit 150 through the recording unit 112 again, based on the defective pixel detection information of the control unit (not shown) and the accurate position detected again by the defective pixel position detecting means 144, the defective pixel is detected. Recording is performed again only on the image in which is detected. For this recording method, the same method as in the first embodiment is applied. However, since the recording paper 116 is continuous this time, it is necessary to carry out the recording according to the method. In some cases, the recording paper 116 that has been waiting as the loop unit 148 is returned to the loop unit 150, and a recovery operation is performed on the defective nozzle, and the recording paper 116 is transported in the same manner as the previous time and recovered. Alternatively, defective pixels may be recorded using the same nozzle.

  When the defect repair for one order is completed in this way, in the next step S270, the one order is collectively cut into images for each frame by the cutter 146. The image (printed material) cut for each frame is stored in a predetermined shelf 122a of the discharge unit 122, and is discharged together for each order.

  As described above, in this embodiment, since one order is processed together, it is possible to prevent the images (printed matter) for one order from being separated.

  Although the image recording apparatus of the present invention has been described in detail above, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. Of course.

1 is a schematic configuration diagram showing a first embodiment of an image recording apparatus according to the present invention. It is a top view which shows the printing part vicinity of FIG. It is the schematic which shows the ink supply system in this embodiment containing sectional drawing of the maintenance unit in alignment with the AA in FIG. 4 is a flowchart showing a flow of processing for repairing defective pixels as an operation of the image recording apparatus of the first embodiment. It is a figure for demonstrating the repair method of a defective pixel, (a) is a graph of the image density which shows a defective part, (b) is description explaining the 1st repair method which reprints only a defective part. (C) is an explanatory view showing a case where the printing position is slightly shifted in the first repair method, (d) is an explanatory view showing a second repair method, and (e) is a view. FIG. 10 is an explanatory diagram illustrating a third repair method, and FIG. 10F is an explanatory diagram illustrating a case where the print position is slightly shifted in the third repair method. It is a schematic block diagram which shows 2nd Embodiment of the image recording apparatus which concerns on this invention. It is a flowchart which shows the flow of the process which repairs the defective pixel as an effect | action of the image recording device of this 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 ... Image recording apparatus, 12, 112 ... Recording part, 14, 114 ... Ink storage / loading part, 16, 116 ... Recording paper, 18, 118 ... Paper feeding part, 20, 120 ... Adsorption belt conveyance part, 22 , 122 ... discharge section (sorter), 24a, 24b ... magazine, 26a, 26b ... drawer roller, 28a, 28b ... cutter, 30, 31 ... roller, 32 ... belt, 34, 134 ... suction chamber, 35, 135 ... suction Fan, 36, 136 ... defective pixel detecting means, 38 ... conveying means, 39, 41 ... conveying path switching means, 40 ... buffer, 42 ... relative movement direction changing means, 44, 144 ... defective pixel position detecting means, 146 ... cutter 148, 150 ... loop part

Claims (5)

At least one of the full-line type recording head in which a plurality of image recording elements are arranged over a length corresponding to the entire width of the recording medium, which is a cut sheet, and the recording medium are arranged in a direction substantially orthogonal to the width direction of the recording medium. An image recording apparatus for recording an image on the recording medium by the recording head while conveying and relatively moving the recording head and the recording medium,
Means for detecting defective pixels in an image recorded on the recording medium by the recording head; and when a defective pixel is detected in an image recorded on the recording medium, the recording medium in which the defective pixel is detected Transport means for transporting the recording head at a position for re-recording by a transport path different from the transport path when the image is first recorded on the recording medium ;
A buffer provided temporarily in the transport path of the transport means for temporarily stocking the recording medium in which the defective pixel is detected;
Means for detecting the position of the defective pixel before recording the recording medium in which the defective pixel is detected again by the recording head;
A standby unit for storing the recorded recording medium in which a defective pixel is not detected, provided in a discharge unit for discharging the recorded recording medium;
When recording an image for one order , the recording medium in which defective pixels are not detected is stored in the standby unit, and the recording medium in which defective pixels are detected is temporarily stored in the buffer. Stock, transport the recording medium stocked in the buffer to a recording position again , move the pixel of the detected defective pixel position to at least one of the recording head and the recording medium, and The image is recorded again by using an image recording element different from the image recording element on which the image is recorded, or the defective pixel of the recording medium is recovered by recovering the defect of the image recording element on which the defective pixel is recorded and recording the image again. after the repair Tsu row, the repaired recording medium recorded SL of 1 order of magnitude coalesce and the recording medium where the defective pixel is not detected to have been stored in the standby section An image recording apparatus characterized in that recording media are discharged together . At least one of the full-line type recording head in which a plurality of image recording elements are arranged over a length corresponding to the entire width of the recording medium, which is roll paper, and the recording medium is arranged in a direction substantially orthogonal to the width direction of the recording medium. An image recording apparatus for recording an image on the recording medium by the recording head while conveying and relatively moving the recording head and the recording medium,
  Means for detecting defective pixels of an image recorded on the recording medium by the recording head;
  A cutter for cutting the recording medium, which is the roll paper, provided on the downstream side in the transport direction with respect to the recording head;
  A loop portion for storing the recording medium for one order formed between the recording head and the cutter;
  When a defective pixel is detected in an image recorded on the recording medium for one order, the recording medium in which the defective pixel is detected is recorded on the recording head to record the image again by the recording head. Transport means for transporting back to the upstream side in the transport direction;
  Means for detecting the position of the defective pixel before recording the image on the recording medium in which the defective pixel is detected again by the recording head;
  When an image having defective pixels is detected in the one-order recording medium, the one-order recording medium in which a loop portion is formed on the downstream side of the recording head is used as the recording head. A loop portion made of a recording medium for one order is formed upstream of the recording head, and image recording is performed again while transporting the recording medium having the loop portion to the recording head again. After the defective pixels are repaired by performing the above, the recording medium for one order is collectively cut and discharged by the cutter for each image.   3. The image recording apparatus according to claim 1, wherein when the image of the recording medium is recorded again by the recording head, the pixels around the defective pixel are subjected to interpolation printing.   4. The image recording apparatus according to claim 3, wherein the pixels around the defective pixel are subjected to interpolation printing at a density lower than that at the previous recording.   The image recording apparatus according to claim 1, further comprising means for changing a relative position of the recording medium and the recording head in the arrangement direction of the image recording elements when the recording medium records an image again by the recording head. 5. The image recording apparatus according to any one of 4 above.

Images