JP2015051535A - Record device and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a sheet transport state with high accuracy even there is a defective part on the sheet.SOLUTION: Provided is the record device for transporting a sheet and recording an image to the sheet by a record head. The record device comprises a marking head for recording a predetermined pattern to a sheet for detecting a transport amount of the sheets, the marking head is disposed on an upstream side of the record head in a sheet transport direction. Then, a sensor disposed on an upstream side of a position where the marking head is installed in the sheet transport direction, detects a predetermined mark indicating there is a defective part on the sheet. In addition, when the mark is detected, the marking head records a pattern which is more prominent than the predetermined pattern and different from the predetermined pattern. Thereby, the record device performs control.

Description

  The present invention relates to a recording apparatus using a recording head that performs recording in accordance with, for example, an ink jet method and a sheet movement detection method.

  When recording is performed while a sheet is being conveyed, the amount of movement may vary due to the conveyance error, resulting in density unevenness in the recorded image, which may degrade image quality. To cope with this problem, a detection pattern with fine ink dots is recorded on the surface of the sheet by a recording device, and the detection pattern recorded on the conveyed sheet is imaged a plurality of times at a predetermined timing, and this is processed. There is a method for detecting the amount of sheet movement with high accuracy.

  For example, the method disclosed in Patent Document 1 detects the amount of sheet movement as follows. First, in order to detect the amount of movement of the sheet, a detection pattern is recorded on the sheet, and the detection pattern is imaged twice at different timings by an image sensor such as an image sensor. After that, a specific template image is extracted from the image data obtained by the first imaging, and where the template image exists in the second imaging image is detected using the existing pattern matching technology. From this result, the movement amount of the sheet is calculated.

JP 2011-095162 A

  In a long roll-shaped sheet, defective parts such as dirt, bubbles, scratches, dust, wrinkles, and density unevenness may occur on the surface of the sheet due to defects in the manufacturing method. For this reason, a mark for notifying the presence of the defective portion is provided immediately before the defective portion.

  However, when the detection pattern is recorded on the surface of the sheet and imaged as in Patent Document 1, if the dots constituting the detection pattern are hit on a mark that informs the defective portion or the defective portion of the sheet, the defective portion or Dot becomes inconspicuous because the dot is buried in the landmark. For this reason, there is a possibility that the detection accuracy of pattern matching is lowered.

  The present invention has been made in view of the above-described conventional example, and provides a recording apparatus and a detection method capable of detecting a moving state such as a conveyance amount and a conveyance speed of a sheet with high accuracy even if there is a defective portion on the sheet. The purpose is to provide.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  That is, a recording apparatus that records an image on a sheet by a recording head, the conveying unit that conveys the sheet, and the sheet conveying direction, provided upstream of a position where the recording head is installed, In order to detect the movement state, a marking head that records a pattern on the sheet and a mark that is provided on the upstream side of the marking head in relation to the sheet conveyance direction and that indicates that the sheet has a defective portion is detected. And a control means for controlling to record a pattern different from the pattern by the marking head when the mark is detected by the detection means.

  According to another aspect of the present invention, a pattern is recorded on a moving sheet by a marking head, and the moving state of the sheet is detected by detecting the recorded pattern, the upstream side of the marking head. A mark indicating that there is a defective portion on the sheet is detected by a sensor provided on the sheet, and when the mark is detected, a pattern different from the pattern is recorded by the marking head. A detection method is provided.

  According to the present invention, there is an effect that the moving state of the sheet can be detected with high accuracy even if the sheet has a defective portion such as dirt, bubbles, scratches, dust, wrinkles and density unevenness.

1 is a schematic perspective view of an ink jet recording apparatus which is a typical embodiment of the present invention. It is a figure which shows the internal structure of the recording part in the recording device shown in FIG. 3 is a configuration diagram of a sensor unit 701. FIG. It is a figure which shows the outline | summary of the movement amount detection of a sheet | seat. 7 is a flowchart illustrating a movement amount detection process for a sheet including a defective portion according to the first embodiment. It is a figure which shows detection pattern rewriting in the defective part of a sheet | seat. It is a figure which shows arrangement | positioning of the sensor unit 701 according to Example 2. FIG.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the already demonstrated part and duplication description is abbreviate | omitted.

  Examples of the ink jet recording apparatus will be described. This recording apparatus is a high-speed line printer using a continuous sheet (recording medium) wound in a roll shape. For example, it is suitable for a large number of print fields in a print laboratory or the like.

  FIG. 1 is a schematic perspective view of an ink jet recording apparatus (hereinafter referred to as a recording apparatus) which is a typical embodiment of the present invention. As shown in FIG. 1, the recording apparatus generally includes a recording unit 1, a sheet supply unit 2, a sheet winding unit 3, and a control unit 6.

  The sheet supply unit 2 holds the roll sheet 4 wound in a roll shape, and supplies the continuous sheet to the recording unit 1 while pulling out the continuous sheet from the roll. The recording unit 1 sequentially records a plurality of images on a sheet 8 that is a continuous sheet. The recorded continuous sheet is wound up as a roll sheet 5 by the sheet winding unit 3. The control unit 6 has a controller, a memory, and various I / O interfaces, and controls the entire recording apparatus. The control unit 6 may be built in the recording apparatus itself, or may be an external host computer connected to the recording apparatus. Note that at an arbitrary position in the sheet conveyance path, the side close to the sheet supply unit 2 is referred to as “upstream”, and the opposite side is referred to as “downstream”.

  2 is a diagram showing an internal configuration of the recording unit 1, FIG. 2 (a) is a top view of the recording unit 1, and FIG. 2 (b) is a side view of the recording unit 1. FIG.

  Four ink jet recording heads 17 to 20 are mounted on the head holder 10 of the recording unit 1, and these four recording heads are held together. These are a black head 17 for black ink, a cyan head 18 for cyan, a magenta head 19 for magenta, and a yellow head 20 for yellow according to the color of the ejected ink. Each recording head is a full-line recording head in which nozzle rows are formed in a range that covers the maximum recording width expected to be used. As the inkjet recording method, a method using a heating element, a method using a piezo element, a method using an electrostatic element, a method using a MEMS element, or the like can be adopted.

  The number of ink colors and the number of recording heads are not limited to four, and a larger or smaller number of ink colors may be used, and a larger or smaller number of recording heads may be used. It may be used. In this embodiment, an ink tube is connected to each recording head, and ink is supplied from an ink tank (not shown). However, each recording head may be a unit integrated with an ink tank for storing the corresponding color ink.

  With such a recording head arrangement, the sheet is recorded in the order of black, cyan, magenta, and yellow while the sheet is conveyed in the direction of arrow A.

  A sheet 8 which is a continuous sheet wound in a roll shape is supplied from the sheet supply unit 2 to the recording unit 1 and conveyed in the direction of arrow A as shown in FIG. As a sheet conveyance mechanism in the recording unit 1, a main conveyance roller pair including a conveyance roller 11 and a pinch roller 12 that is driven to rotate is provided. On the downstream side of each color head, four sets of sub-conveying roller pairs including a conveying roller 13 and a pinch roller 14 that is driven to rotate are provided.

  A sensor unit 701 and a marking head 500 are provided on the upstream side of the four recording heads. As can be seen from FIG. 2A and FIG. 2B, the marking head 500 and the sensor unit 701 are arranged on the upstream side of the recording head and substantially in the center in the width direction of the sheet. The marking head 500 is an ink jet recording head having an ink ejection surface 501 and is provided in the head holder 7. Further, a blade 31 for cleaning the ink receiver 30 and the ink discharge surface 501 of the marking head 500 is provided on the side facing the ink discharge surface 501.

  The sensor unit 701 is used to detect the moving amount or moving speed of the sheet 8 by pattern matching based on the image data captured thereby. The marking head 500 records an auxiliary image for detection, that is, auxiliary dots.

  Such an arrangement of the sensor unit 701 and the marking head 500 can cope with borderless full-surface printing, is not easily affected by the mist of each recording head, and detects an average amount of movement with respect to minute meandering and minute skew of the sheet. it can.

  Further, a defective paper mark detection sensor 700 for detecting a defective paper mark attached on the sheet is disposed further on the sheet feeding side than the marking head 500. The defective paper mark detection sensor 700 is a reflective optical sensor composed of a light emitting element and a light receiving element, and can discriminate between the white of the sheet 8 and the black mark (mark) on the sheet 8.

  3 is a configuration diagram of the sensor unit 701, FIG. 3A is a top view of the sensor unit 701, and FIG. 3B is a side sectional view of the sensor unit 701. FIG.

  The sensor unit 701 is mainly an optical sensor unit that includes a light emitting unit, a light receiving unit, and an image processing unit, and these are integrated as a unit.

  Light emitted from a light source 703 including a light emitting element such as an LED is guided by a light guide 702 to illuminate the surface of the sheet 8 from an oblique direction. The image of the illumination area on the sheet 8 is formed on the image sensor 705 by the lens 706. The transparent protective cover 704 prevents ink mist and the like from entering from the sheet 8 side and stains on the lens 706.

  An image including a detection pattern recorded on the sheet 8 by the marking head 500 is read by the image sensor 705. An imaging signal obtained from the image sensor 705 is A / D converted and transferred to the image processing unit 707. The image processing unit 707 compares a plurality of image data obtained by performing imaging a plurality of times with the movement of the sheet 8 by image processing including a pattern matching process, and moves the sheet (moving amount / carrying amount). Alternatively, the moving speed / conveying speed) is detected. The sheet movement information thus obtained is fed back to the control unit 6.

  Next, a process for detecting the movement amount of the sheet from the image data captured by the image sensor 705 will be described.

  FIG. 4 is a diagram showing an outline of sheet movement amount detection.

  As shown in FIG. 4 (a), the sheet 403 is conveyed in the direction of arrow A, FIG. 4 (a) shows the state before the sheet moves, and FIG. 4 (b) shows that the sheet moves at a specified time. Shows the state after.

  In the example shown in FIG. 4A, the nozzle 411 of the marking head 500 records a detection pattern for calculating the movement amount of the sheet 8. The detection patterns 401, 412, 413, 414, and 415 are recorded by the nozzle 410 of the marking head 500, and the hatched area 402 represents an image area captured by the image sensor 707. An area 400 surrounded by a square in FIG. 4A represents a template image area including a detection pattern extracted from the imaging area 402 by the image sensor 707.

  The detection pattern 401 moves until the second image pickup by the image sensor 707 and is shown as a detection pattern 405 as shown in FIG. A region 407 indicated by diagonal lines in FIG. 4B represents an image region captured by the image sensor 707 as in FIG. A region 408 surrounded by a square in FIG. 4B represents a search region for detecting the template image region 400 extracted in the first shooting in the region 407 in the second shooting. The search area 408 is wider than the template image area, and it is detected by pattern matching at which pixel position in the search area the same image as the template image exists. Then, the movement amount of the sheet is calculated from the detection result.

  For example, originally, a detection pattern should exist at the position 409 in FIG. 4B, but if it is detected by pattern matching that the detection pattern exists at the position 405, the deviation of the distance is detected. Is the amount of movement of the sheet. An area 406 becomes a template image for calculating the next movement amount, and the movement amount of the sheet is calculated in real time by repeating the same processing.

  Next, several embodiments of the conveyance state detection process when a sheet including a defective portion is used in the recording apparatus having the above-described configuration will be described.

  Here, a method of detecting the amount of movement of the sheet 8 when a defective paper mark is detected will be described with reference to FIGS.

  FIG. 5 is a flowchart illustrating the movement amount detection processing for a sheet including a defective portion according to the first embodiment.

  FIG. 6 is a diagram showing rewriting of the detection pattern at a defective portion of the sheet.

  When the recording operation is started, the sheet 8 is conveyed from the sheet supply unit 2 in step S501. During the conveyance, in step S502, the defective paper mark detection sensor 700 checks whether there is a defective paper mark on the sheet 8. If it is determined that the sheet has no defective paper mark, that is, a sheet having no different defective portion, the process proceeds to step S505, and the detection pattern 401 is recorded by the marking head 500 as shown in FIG. 6B. The

  On the other hand, when there is a defective paper mark, that is, when it is determined that a square defective paper mark 601 is recorded in advance on the surface of the sheet 8 as shown in FIG. The process proceeds to step S503. The length of the defective paper area 602 is defined by the size (width) of the defective paper mark 601. In the defective area 602, there are small dirt 603, dust 604, and scratches 605 that do not hinder the conveyance. The defective area 602 is an area in which image recording is not possible because there may be visible dirt 603, dust 604, and scratches 605, but the detection pattern can be recorded on the entire surface of the sheet including such areas.

  In step S 503, the defective paper detection pattern 605 is recorded by the marking head 500. As shown in FIG. 6B, the defective paper detection pattern 605 is a conspicuous pattern large enough to cover the defective paper factors (dirt, foam, dust, scratches). The defective paper detection pattern 605 is recorded using black having the highest contrast with the white paper. By using this defective paper detection pattern, it is possible to prevent a detection error caused by the image sensor and a decrease in detection accuracy even if there is a cause of the defective paper on the sheet.

  In step S504, it is checked whether or not the defective portion has been completed. This is done by comparing the length of the defective paper area defined by the size (width) of the defective paper mark 601 with the transport amount. Here, if it is determined that the defective portion is completed by the conveyance of the sheet, the process proceeds to step S505, and if it is determined that the defective portion still continues, the process returns to step S503.

  In step S505, the detection pattern 401 is recorded as shown in FIG. 6B by switching to the normal detection pattern as described above. Thereafter, in step S506, the detection pattern is imaged by the imaging unit 701, and in step S507, the movement amount of the sheet is calculated. In step S508, a recording timing is generated from the calculated movement amount, and recording is performed.

  Next, in step S509, it is confirmed whether or not the recording data is finished. If it is determined that the recording data is not finished, the process returns to step S501 and the above-described process is repeated. On the other hand, if it is determined that the recording data is finished, the process returns to step S510, the sheet is discharged, and the process is terminated.

  In this case, the discharge means that the roll paper as in this embodiment is used as a sheet and is discharged from the recording unit 1 and wound on the sheet winding unit 3.

  Therefore, according to the embodiment described above, when a sheet including a defective portion is used, a defective paper mark is detected prior to actual recording, and a defective paper detection pattern can be clearly recorded again. As a result, even if there is a defective part on the sheet, a detection pattern for defective paper that is clearly distinguished from the defective part can be detected by the sensor unit on the downstream side of the sheet conveyance, so that the movement state of the sheet can be detected with high accuracy. Can be detected.

  In this embodiment, the example in which the defective paper mark is a square mark has been described, but the present invention is not limited thereto. For example, instead of such a predetermined figure, a method of making a hole in paper or sticking a tape on paper may be used. Although a plurality of large circular patterns are used for detection, other patterns may be used as long as they can enter the imaging template and calculate the movement amount. Further, although the cause of defective paper is foam, dust, or scratches, it may be uneven density or wrinkles on the sheet as long as there is no trouble in conveyance and the size can be covered with the detection pattern for defective paper.

  Here, another example of reading the defective paper mark 601 and the detection pattern 401 will be described.

  FIG. 7 is a diagram illustrating an arrangement of the sensor unit 701 according to the second embodiment.

  As shown in FIG. 7, unlike the configuration of the first embodiment shown in FIG. 6, in this embodiment, the sensor unit 701 is installed on the upstream side in the conveyance direction of the sheet 8 from the installation location of the marking head 500. Install in a tilted direction.

  With such an installation, the sensor unit 701 can simultaneously image the defective paper mark 601 and the detection pattern 401. Therefore, by setting the template image area referred to in FIG. 4 to an area that can be imaged at once by the sensor unit 701, the defective paper mark 601 and the detection pattern 401 are made of the same template without providing the defective paper mark detection sensor 700. Can be read.

Claims (11)

A recording apparatus for recording an image on a sheet by a recording head,
Conveying means for conveying the sheet;
A marking head that is provided upstream of the position where the recording head is installed with respect to the conveyance direction of the sheet, and that records a pattern on the sheet in order to detect the movement state of the sheet;
With respect to the conveyance direction of the sheet, a detection unit that is provided upstream of the marking head and detects a mark indicating that the sheet has a defective portion;
And a control unit that controls to record a pattern different from the pattern by the marking head when the mark is detected by the detection unit. The detection means is an optical sensor capable of detecting the mark and the pattern recorded by the marking head,
The recording apparatus according to claim 1, wherein the optical sensor is installed to be inclined with respect to a conveyance direction of the sheet.   The recording apparatus according to claim 1, further comprising a sensor unit that is provided on a downstream side of the marking head with respect to a conveyance direction of the sheet and detects a pattern recorded by the marking head. The sheet is a roll-shaped continuous sheet,
The recording apparatus according to claim 1, wherein the mark includes information indicating a length of the defective portion with respect to a conveyance direction of the sheet. The control means includes
Determination means for determining the end of the defective portion during conveyance of the continuous sheet by the conveyance means;
The recording apparatus according to claim 4, further comprising a switching unit that switches the recording by the marking head to the pattern when the determination unit determines the end of the defective portion.   6. The mark according to claim 1, wherein the mark includes any one of a hole formed in the sheet, a tape attached to the sheet, and a figure having a predetermined shape. The recording device described.   The defective portion of the sheet includes at least one of dirt, bubbles, scratches, dust, wrinkles, and density unevenness generated on the sheet. The recording apparatus according to claim 1.   The recording apparatus according to claim 1, wherein the recording head is a full-line recording head having a recording width corresponding to a width of the sheet.   The recording apparatus according to claim 8, wherein the full line recording head is an ink jet recording head.   The recording apparatus according to claim 9, wherein the different pattern is a more conspicuous pattern recorded by the inkjet recording head. A method of detecting a moving state of a sheet by recording a pattern on a moving sheet with a marking head and detecting the recorded pattern,
By a sensor provided upstream from the marking head, a mark indicating that the sheet has a defective portion is detected,
When the mark is detected, a pattern different from the pattern is recorded by the marking head.

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