JP2014192722A - Image inspection device and image inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image inspection device and an image inspection method, with which it is possible to favorably read a print image on a print medium.SOLUTION: At an inspection part 21, a suction table 41 is provided with a suction port 45b for causing continuous paper WP to be suctioned by a suction surface 45a contacting a non-inspection surface of the continuous paper WP, and suctions the non-inspection surface of the continuous paper WP. With this construction, the continuous paper WP is arranged at a predetermined position at which the continuous paper WP is capable of being read by a CIS sensor 65 without contacting the CIS sensor 65 that is ordinarily used in contact with a reading target. Also, the CIS sensor 65 is moved by a movement mechanism 63 so that a distance between a reading surface 65a of the CIS sensor 65 and the suction surface 45a of the suction table 45 becomes a first distance G1 set in advance. As a result, it is possible to favorably read a print image of an inspection surface of the continuous paper WP suctioned by the suction surface 45a by means of the CIS sensor 65.

Description

  The present invention relates to an image inspection apparatus and an image inspection method for inspecting an image printed on a print medium.

  Image inspection apparatuses inspect images printed on a print medium, and there are two types. One is an image inspection apparatus for determining whether printing is good or bad for inspecting a printed image for dirt or missing. Since this image quality inspection device for determining whether or not printing is performed at the time of printing, the print image of the print medium being conveyed is read.

  The other is an image inspection apparatus for print adjustment for performing shading correction, ejection inspection, and the like (see, for example, Patent Document 1). Such an image inspection apparatus for print adjustment reads a print image of a print medium in a state where conveyance of the print medium is stopped and pulled from both sides and under tension.

  These image inspection devices for print quality determination and print adjustment include a CCD (charge coupled device) sensor as a reading sensor, and read a print image on a print medium.

  The print image of the print medium is recorded (printed) by a recording head of an ink jet printer as in Patent Document 2, for example. The ink jet printer of Patent Literature 2 includes a recording head and a medium support table facing the recording head. The medium support table includes a platen having a medium support surface that supports the roll paper, and the platen has a suction hole (suction port) penetrating from the medium support surface to the back surface. The print medium arranged on the platen is sucked through the plurality of suction holes.

  An adsorption table that adsorbs a print medium such as a print medium support table with an adsorption port can be applied to the surface of the adsorption table by roughening the surface or using a porous material as the material of the adsorption table. It is known to adsorb. In the case of a suction drum, it is known to provide a suction groove.

JP 2006-035727 A Japanese Patent Application Laid-Open No. 2012-196821

  As described above, the conventional apparatus uses a CCD sensor as a reading sensor that reads an inspection surface on which an image of a printing medium is printed. The CCD sensor includes a light source (illumination), a lens, a mirror, an image sensor (CCD), and the like. The image sensor of the CCD sensor is configured to be folded back by a mirror because the optical path length to the inspection surface (printing surface) of the print medium must be about several hundred mm. Therefore, the configuration of the CCD sensor is complicated. Therefore, it has been studied to adopt a CIS sensor (contact image sensor) having a relatively simple configuration.

  The CIS sensor needs to keep the distance to the inspection surface of the print medium within about 1 mm, and it is desirable to keep the inspection surface of the print medium within a readable range of the CIS sensor. In such a case, the distance between the CIS sensor and the inspection surface is maintained by contacting the CIS sensor and the print medium via the cover glass of the CIS sensor. However, since the cover glass that comes into contact with the print medium is contaminated, there has been a problem that the reading accuracy of the CIS sensor is lowered.

  SUMMARY An advantage of some aspects of the invention is that it provides an image inspection apparatus and an image inspection method that can satisfactorily read a print image on a print medium.

In order to achieve such an object, the present invention has the following configuration.
That is, the image inspection apparatus according to the present invention is provided with an adsorption table for adsorbing the print medium on an adsorption surface in contact with the non-inspection surface of the print medium, the adsorption table adsorbing the non-inspection surface, and the adsorption surface A reading sensor that reads a printed image on the inspection surface of the print medium adsorbed on the sheet, and when the adsorption table is adsorbing the print medium, a gap between the reading surface of the reading sensor and the adsorption surface is set in advance. And a moving mechanism for moving the reading sensor so as to be the first distance.

  According to the image inspection apparatus of the present invention, the suction table is provided with the suction port for sucking the print medium on the suction surface in contact with the non-test surface of the print medium, and sucks the non-test surface of the print medium. As a result, the print medium is arranged at a predetermined position that can be read by the reading sensor without being in contact with the reading sensor that is normally used in contact with the printing medium. Further, when the suction table is sucking the print medium, the reading sensor is moved by the moving mechanism so that the first distance between the reading surface and the suction surface of the reading sensor is set in advance. Therefore, the print image of the inspection surface of the print medium adsorbed on the adsorption surface can be satisfactorily read by the reading sensor.

  Moreover, in the above-mentioned invention, this inventor acquired the following knowledge. In the suction table, for example, it is assumed that a suction through hole is provided in a flat plate that is not subjected to surface processing or the like. In this case, only the periphery of the hole is adsorbed, and in the absence of the hole, “floating” occurs in which the print medium floats from the surface of the adsorption table. Furthermore, if the hole diameter is increased in order to widen the suction effective part and suppress the floating, a dent is generated in the suction hole (suction port). In such a dent or floating portion, an influence of reading such that the read image is blurred is produced. The same applies to the suction groove.

  In this regard, reducing the opening diameter of the suction holes to increase the number of holes, roughening the surface of the suction table with sandblasting, etc., and using a porous body as the material of the suction table, dents and floating parts are It can be suppressed. However, the surface processing cost and the material cost become high.

  The present invention based on such knowledge has the following configuration. That is, in the image inspection apparatus according to the present invention, it is preferable that the suction table is provided with unevenness formed on the entire surface of the suction surface by coating a base material with a paint in which granular beads are mixed. . Accordingly, the suction force can be generated not only through the portion where the suction port is provided, but also through a gap formed between the unevenness provided on the entire suction surface and the printing medium. As a result, the entire surface of the print medium in contact with the suction surface can be stably adsorbed, and dents and floating portions can be suppressed, and the print image on the inspection surface of the print medium can be read well. Also, the unevenness of the adsorption surface is formed by painting the base material with a paint mixed with granular beads, so it is simpler than, for example, surface treatment with sand blasting, etc. A highly rigid material can be used, and as a result, it can be formed at a low cost.

  In the image inspection apparatus according to the present invention, it is preferable that the reading sensor is a CIS sensor. Thereby, a structure can be simplified compared with a CCD sensor.

  Moreover, in the above-mentioned invention, this inventor acquired the following knowledge. That is, when the print medium is adsorbed to the adsorption table without loosening the tension, wrinkles are generated due to uneven tension in the print medium. When wrinkles are generated, the read image is blurred as in the case of the dents and floating portions.

  The present invention based on such knowledge has the following configuration. That is, the image inspection apparatus according to the present invention is further provided upstream and downstream of a transport path of the print medium with reference to the suction table, and a plurality of drive rollers that transport the print medium, and the upstream and downstream of the print roller The print medium is transported to the inside of the transport path sandwiched between driving rollers, and the print medium is placed on the suction surface while loosening the print medium, and after the print medium is placed on the suction surface, the print medium is placed on the suction surface. It is preferable to include a control unit that is adsorbed on the surface.

  As a result, the print medium is loosened, so that the tension applied unevenly in the print medium can be removed. Therefore, wrinkles are suppressed, and the print medium in a state where wrinkles are suppressed can be adsorbed on the adsorption surface.

  Further, in the image inspection apparatus according to the present invention, the conveyance of the print medium to the inside of the conveyance path sandwiched between the upstream and downstream drive rollers is provided on the upstream side and on the downstream side. It is preferable that this is performed by fixing any one of the driving rollers and rotating the other driving roller. Thereby, control of a drive roller can be simplified.

  Further, in the image inspection apparatus according to the present invention, the print medium is maintained at a second distance larger than the first distance with respect to the suction surface during conveyance, and the reading sensor is It is preferable to retract to a retract position that does not contact the print medium.

  That is, when the print medium is transported, the print medium is tensioned and the print medium may be wrinkled. The suction surface of the suction table and the non-inspected surface of the print medium may come into contact with each other, and the print medium may be damaged. There is. Further, when the ink of the print image on the print medium is not dried, wrinkles appear remarkably. Thus, the print medium is maintained at a second distance greater than the first with respect to the suction surface. As a result, the print medium can be transported in a state sufficiently separated from the suction surface. In addition, when the print medium is transported, the reading sensor is retracted to a retracted position where it does not come into contact with the printing medium, so that contact between the reading sensor and the printing medium can be prevented. Thereby, damage to the print medium due to the print medium coming into contact with the reading sensor can be prevented. Further, when the reading surface of the reading sensor comes into contact when the ink of the printed image of the printing medium is not dry, the ink adheres and troubles in reading by the reading sensor, but this can be prevented.

  In the image inspection apparatus according to the present invention, the movement direction of the reading sensor is a direction orthogonal to the conveyance path of the print medium on the inspection surface, and the retracted position is a position obtained by extending the movement direction. It is preferable that the position is outside the transport path. Thereby, when reading the print image of the continuous paper, it is possible to smoothly shift to the reading operation from the retracted position.

  The image inspection method according to the present invention may be configured such that the non-inspection surface is adsorbed by an adsorption table provided with an adsorption port for adsorbing the print medium on an adsorption surface in contact with the non-inspection surface of the print medium. The reading sensor is moved by a moving mechanism so that the reading surface maintains a preset first distance with respect to the suction surface, and a print image of the inspection surface of the print medium sucked on the suction surface is obtained. It is characterized by reading with a reading sensor.

  According to the image inspection method of the present invention, the suction table is provided with the suction port for sucking the print medium on the suction surface in contact with the non-test surface of the print medium, and sucks the non-test surface of the print medium. As a result, the print medium is arranged at a predetermined position that can be read by the reading sensor without being in contact with the reading sensor that is normally used in contact with the printing medium. Further, when the suction table is sucking the print medium, the reading sensor is moved by the moving mechanism so that the first distance between the reading surface and the suction surface of the reading sensor is set in advance. Therefore, the print image of the inspection surface of the print medium adsorbed on the adsorption surface can be satisfactorily read by the reading sensor.

  According to the image inspection apparatus and the image inspection method of the present invention, the suction table is provided with a suction port for sucking the print medium on the suction surface in contact with the non-test surface of the print medium, and the non-test surface of the print medium is provided. Adsorb. As a result, the print medium is arranged at a predetermined position that can be read by the reading sensor without being in contact with the reading sensor that is normally used in contact with the printing medium. Further, when the suction table is sucking the print medium, the reading sensor is moved by the moving mechanism so that the first distance between the reading surface and the suction surface of the reading sensor is set in advance. Therefore, the print image of the inspection surface of the print medium adsorbed on the adsorption surface can be satisfactorily read by the reading sensor.

It is a schematic block diagram of the inkjet printing apparatus which concerns on an Example. It is a schematic block diagram of a test | inspection part. (A) is a top view of a suction plate, (b) is a longitudinal cross-sectional view of a suction plate. (A) is a top view of the inspection part seen from the A direction of FIG. 2, (b) is a side view of the scanner seen from the C direction of (a). It is a flowchart with which it uses for operation | movement description of a test | inspection part. It is a figure for demonstrating the distance between continuous paper and a suction surface. It is a schematic block diagram of the inkjet printing apparatus which concerns on a modification.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an ink jet printing apparatus according to an embodiment, and FIG. 2 is a schematic configuration diagram of an inspection unit. FIG. 3A is a plan view of the suction plate, and FIG. 3B is a longitudinal sectional view of the suction plate.

  Please refer to FIG. The inkjet printing apparatus 1 includes an inkjet printing unit 2 that performs printing on a sheet-like continuous paper WP, a paper feeding unit 3 that supplies the continuous paper WP to the inkjet printing unit 2, and a continuous paper WP that has been printed in a roll shape. And a paper discharge unit 4 for winding. The continuous paper WP corresponds to the print medium of the present invention.

  The paper feed unit 3 holds a roll of continuous paper WP so as to be rotatable about a horizontal axis, and feeds the continuous paper WP from the roll of continuous paper WP to the inkjet printing unit 2 by unwinding. The paper discharge unit 4 winds the continuous paper WP printed by the inkjet printing unit 2 around the horizontal axis. When the supply side of the continuous paper WP is the upstream side and the discharge side of the continuous paper WP is the downstream side, the paper feed unit 3 is disposed upstream of the inkjet printing unit 2, and the paper discharge unit 4 is the inkjet printing unit 2. It is arranged downstream.

  The ink jet printing unit 2 includes a driving roller 7 for taking in the continuous paper WP from the paper feeding unit 3 on the upstream side. The continuous paper WP unwound from the paper feed unit 3 by the driving roller 7 is conveyed toward the downstream paper discharge unit 4 along a rotatable conveyance roller 9 having no driving mechanism. A driving roller 11 is disposed between an inspection unit 21 and a paper discharge unit 4 which will be described later. The drive roller 11 feeds the continuous paper WP that has passed through an inspection unit 21 described later toward the paper discharge unit 4.

  The inkjet printing unit 2 includes an edge position control unit 13, a driving roller 15, a printing unit 17, a drying unit 19, and an inspection unit 21 in that order from the upstream side between the driving roller 7 and the driving roller 11. Further, nip rollers 23 are rotatably provided on the drive rollers 7, 11 and 15, respectively. The nip roller 23 presses the driving rollers 7, 11, and 15 from the opposite side with the continuous paper WP interposed therebetween, thereby giving a grip force when the continuous paper WP is conveyed. The pressing force is given by, for example, an air cylinder. The nip roller 23 is made of an elastic body such as rubber.

  The edge position control unit 13 automatically adjusts when the continuous paper WP meanders so that the continuous paper WP flows to a correct position. The drive roller 15 rotates at a constant speed, and serves as a reference for the number of rotations of the other drive rollers 7 and 11 and a heat drum 27 described later.

  The printing unit 17 includes an inkjet head 25 that ejects ink droplets (ink). In the printing unit 17, a plurality of inkjet heads 25 are arranged in a staggered arrangement in the width direction (main scanning direction) 202 of the continuous paper WP orthogonal to the conveyance direction (sub-scanning direction) 201 of the continuous paper WP. Thus, ink droplets are ejected onto the continuous paper WP while the continuous paper WP is being sent while the position is fixed without moving the inkjet head 25 in the width direction 202 of the continuous paper WP. In the following, a plurality of inkjet heads 25 arranged in a staggered arrangement in the width direction 202 of the continuous paper WP will be described as one inkjet head 25. Reference numeral 203 denotes a conveyance path for the continuous paper WP.

  The printing unit 17 includes a plurality of inkjet heads 25 arranged along the conveyance direction 201 of the continuous paper WP. The plurality of inkjet heads 25 are configured to eject, for example, black (K), cyan (C), magenta (M), and yellow (Y) ink droplets. An ink supply unit (not shown) is connected to the printing unit 17 and supplies ink droplets to the printing unit 17 as necessary.

  The drying unit 19 dries the ink droplets ejected from the inkjet head 25 and attached to the continuous paper WP. The drying unit 19 includes a heat drum 27, for example. The heat drum 27 incorporates a heater and is driven to rotate. The inspection unit 21 inspects an image printed on the continuous paper WP, and details thereof will be described later. The inspected continuous paper WP is wound around the paper discharge unit 4 in a roll shape. The heat drum 27 corresponds to the drive roller of the present invention.

  The inkjet printing apparatus 1 includes a main control unit 29 and an operation unit 31. The main control unit 29 comprehensively controls each component of the inkjet printing apparatus 1 (for example, the printing unit 17, the inspection unit 21, the drive rollers 7, 11, 15 and the heat drum 27). The main control unit 29 is configured by a central processing unit (CPU) and the like. The operation unit 31 operates the ink jet printing apparatus 1 and includes, for example, a touch panel and various switches. The operation unit 31 may be configured by a personal computer and input an operation using a mouse, a keyboard, or the like. The driving rollers 7, 11, 15 and the heat drum 27 are rotationally driven by a driving mechanism such as a motor or a gear (not shown). The main control unit 29 corresponds to the control unit of the present invention.

<Configuration of inspection unit 21>
Next, a specific configuration of the inspection unit 21 will be described. As illustrated in FIG. 2, the inspection unit 21 includes a suction table 41 and a scanner (scanning unit) 43. The inspection unit 21 corresponds to the image inspection apparatus of the present invention.

<< Configuration of Suction Table 41 >>
The suction table 41 sucks the non-inspection surface, which is the back side of the inspection surface of the continuous paper WP, and fixes the continuous paper WP. The suction table 41 sucks the suction plate 45, the negative pressure chamber 47 provided on the opposite side of the continuous paper WP across the suction plate 45, and the negative pressure chamber 47 to suck out the gas in the negative pressure chamber 47. And a fan 49 to be in the state.

  The suction plate 45 is provided with a suction port 45b for sucking the continuous paper WP to a suction surface 45a that contacts the non-inspection surface of the continuous paper WP. The suction port 45 b is a hole penetrating from the suction surface 45 a to the negative pressure chamber 47 side, and a suction force is given by the negative pressure chamber 47 and the fan 49. As shown in FIG. 3A, a plurality of suction ports 45b are provided on the suction plate 45, are arranged two-dimensionally, and are provided in a region E that is in contact with the continuous paper WP. The opening diameter of the suction port 45 b is such that the depression of the continuous paper WP by the suction port 45 b is suppressed when the continuous paper WP is sucked, and the reading of the scanner 43 is not affected.

  Further, the suction plate 45 is provided with irregularities on substantially the entire suction surface 45a that contacts the continuous paper WP. In this embodiment, the unevenness is formed in the region F, but the unevenness may not be formed outside the region E. Regions E and F are shown larger for convenience of illustration.

  The unevenness of the suction surface 45a of the suction plate 45 is formed by coating a base material 45c, which is a basic material, with a paint in which granular beads B are mixed, as shown in FIG. The uneven | corrugated layer 45d is shown to the code | symbol 45d in FIG.3 (b). The beads are made of glass, resin, or the like, and the paint is made of a thermosetting resin or the like. The base material 45c is made of iron, which is a highly rigid material.

  The uneven layer 45d is controlled such that the bead particle size D1 and the coating film D2 have a preset size. Thereby, a minute gap can be formed between the continuous paper WP and the suction surface 45a. Therefore, it is possible to generate suction force other than the suction port 45b and stably suction the entire continuous paper WP that contacts the suction surface 45a. Thereby, it is possible to suppress the continuous paper WP from floating between the suction ports 45b. In addition, since the entire surface of the continuous paper WP can be stably adsorbed, the opening diameter of the adsorbing port 45b may be small, and dents can be suppressed. That is, floating and dent portions can be suppressed. Further, by changing the roughness of the adsorption surface 45a by changing the bead particle size D1 and the mixing ratio thereof, an appropriate roughness state can be set.

  Note that a minute gap formed between the continuous paper WP and the suction surface 45a will be supplementarily described. In FIG. 3B, the minute gaps are illustrated so as not to be connected to each other. However, since the minute gap is formed in a portion between the adjacent beads B, it is connected over the entire surface of the adsorption surface 45a. Therefore, it can adsorb | suck on the whole surface of the adsorption | suction surface 45a.

  As shown in FIG. 2, the negative pressure chamber 47 has a hollow inside. The fan 49 is composed of a counter rotating fan or the like. The fan 49 is controlled by a main control unit 29 configured by a CPU or the like.

<< Configuration of Scanner 43 >>
As shown in FIG. 2, the scanner 43 includes a scanner main body 61 and a moving mechanism 63. The scanner body 61 includes a CIS sensor 65 as a reading sensor that reads a printed image on the inspection surface of the continuous paper WP adsorbed on the adsorption surface 45 a of the adsorption plate 45, and a cover glass 67. The CIS sensor 65 includes a light source such as an LED, an image sensor (CMOS or the like), a lens, and the like, and can have a simpler configuration than the CCD sensor. A cover glass 67 is provided on the front surface of the reading surface (image pickup surface of the image pickup device) 65a of the CIS sensor 65 as a light transmission layer for preventing dust adhesion.

  4A is a plan view of the inspection unit 21 viewed from the direction A in FIG. 2, and FIG. 4B is a side view of the scanner viewed from the direction C in FIG. 4A. The CIS sensor 65 is configured in a line shape along the transport direction 201. As shown in FIG. 2, the moving mechanism 63 moves the CIS sensor 65 so that the distance (distance) between the reading surface 65a of the CIS sensor 65 and the suction surface 45a of the suction plate 45 becomes a preset first distance G1. The scanner main body 61 is moved. The moving mechanism 63 includes a guide rail 71 and a drive unit 73 as shown in FIG.

  The guide rail 71 is provided along the width direction 202 of the continuous paper WP, and movably supports the scanner main body 61 having the CIS sensor 65. The guide rail 71 is configured by a slide bearing or the like. Both ends of the guide rail 71 are fixed to the frame 75.

  The drive unit 73 moves the scanner main body 61 along the guide rail 71, and the drive unit 73 includes a motor, a pulley, a belt, and the like. As the scanner main body 61 moves along the guide rail 71, the reading surface 65a and the suction surface 45a of the CIS sensor 65 maintain a preset first distance G1.

  4A is a retracted position of the scanner main body 61 having the CIS sensor 65. When the continuous paper WP is conveyed, the continuous paper WP is retracted to the retreat position J so as not to contact the continuous paper WP. As shown in FIG. 4A, the moving direction of the scanner main body 61 is the width direction 202 of the continuous paper WP orthogonal to the conveyance path 203 of the continuous paper WP on the inspection surface of the continuous paper WP. The retreat position J is a position where the moving direction of the scanner main body 61 is extended and is a position outside the conveyance path 203. Thereby, when reading the print image of the continuous paper WP, it is possible to smoothly shift to the reading operation from the retracted position J. The scanner 43 is controlled by the main control unit 29.

  2, the inspection unit 21 includes an A / D converter 77 that converts an analog image output from the CIS sensor 65 into a digital image, a digital image converted by the A / D converter 77, and the like. And a memory 79 for storing.

<Description of Operation of Inspection Unit 21>
Next, the operation of the inspection unit 21 will be described with reference to the flowchart of FIG.

[Step S01] Printing Adjustment Chart The adjustment chart (print image) is printed by the printing unit 17 on the continuous paper WP. The printing chart is a pattern printed for shading correction, discharge inspection, and the like. The continuous paper WP portion on which the adjustment chart is printed is conveyed to the inspection unit 21 by the drive rollers 7, 11, 15 and the heat drum 27. In addition, when passing the drying part 19, the ink which comprises the adjustment chart is dried. Further, during printing on the continuous paper WP and transportation of the continuous paper WP, the scanner main body 61 having the CIS sensor 65 is retracted to a retracted position J (see FIG. 4A) outside the transport path 203.

[Step S02] Operation to loosen the continuous paper WP When the continuous paper WP portion on which the adjustment chart is printed is conveyed to a position facing the suction plate 45 of the inspection unit 21, the main control unit 29 sets the drive rollers 7, 11, 15 and the heat drum 27 are controlled to loosen the continuous paper WP, and the continuous paper WP is placed on the suction surface 45a by its own weight.

  This operation will be specifically described. As shown in FIGS. 1 and 2, drive rollers 7 and 15 and a heat drum 27 are provided upstream of the conveyance path 203 of the continuous paper WP with reference to the suction table 41 of the inspection unit 21. On the other hand, the driving roller 11 is provided downstream of the conveyance path 203.

  The main control unit 29 fixes any one of the drive rollers 7 and 15 and the heat drum 27 provided upstream and the drive roller 11 provided downstream. For example, the drive rollers 7 and 15 and the heat drum 27 which are upstream drive rollers are fixed. Further, the other driving roller 11 is rotated. That is, since the drive rollers 7 and 15 and the heat drum 27 provided upstream are fixed, the drive roller 11 provided downstream is rotated.

  As a result, the driving roller 11 conveys the continuous paper WP to the inside (see arrow H in FIG. 2) on the conveying path 203 sandwiched between the upstream and downstream driving rollers 7 and 15 and the heat drum 27, and the continuous paper WP. Is put on the suction surface 45a. By loosening the continuous paper WP, it is possible to remove the tension that is applied non-uniformly within the continuous paper WP. Note that the carry amount of the continuous paper WP is set in advance.

[Step S03] Adsorption of Continuous Paper WP After the continuous paper WP is placed on the adsorption surface 45a, the main control unit 29 controls the fan 49 to apply an adsorption force to the adsorption port 45b, so that the non-inspection surface of the continuous paper WP Is adsorbed on the adsorption surface 45 a of the adsorption plate 45. In other words, the negative pressure chamber 47 is brought into a negative pressure state by the fan 49, the suction force is applied to the suction port 45 b, and the non-inspecting surface of the continuous paper WP is sucked to the suction surface 45 a of the suction plate 45.

  As shown in FIGS. 3 (a) and 3 (b), the suction surface 45a is provided with a suction port 45b, and a substrate 45c is coated on the substantially entire surface with a paint in which granular beads B are mixed. The unevenness | corrugation formed by doing is provided. Therefore, since the continuous paper WP is sucked to the suction surface 45a not only through the suction port 45b but also through a minute gap formed by unevenness provided on the suction surface 45a, the undulation of the continuous paper WP due to the formation of a dent or a floating portion is suppressed. be able to. Further, since a highly rigid material can be used for the base material 45c, the base paper 45c is hardly deformed, and the continuous paper WP adsorbed on the adsorption surface 45a is arranged at a predetermined position that can be read by the CIS sensor 65. Can do.

[Step S04] Scan Operation The CIS sensor 65 reads the adjustment chart for the inspection surface of the continuous paper WP adsorbed on the adsorption surface 45a of the adsorption table 41. That is, the CIS sensor 65 is moved by the moving mechanism 63 so that the reading surface 65a of the CIS sensor 65 maintains the first distance G1 set in advance with respect to the suction surface 45a. Thereby, the CIS sensor 65 reads the adjustment chart for the inspection surface of the continuous paper WP adsorbed on the adsorption surface 45a.

  The analog image read and output by the CIS sensor 65 is converted into a digital image by the A / D converter 77 and stored in the memory 79. Then, the main control unit 29 performs shading correction, discharge inspection, and the like based on the digital image of the adjustment chart. After the reading by the CIS sensor 65 is completed, the scanner main body 61 having the CIS sensor 65 is moved by the drive unit 73 to the retracted position J on the extension of the guide rail 71.

  Here, the second distance G2 between the non-inspection surface of the continuous paper WP and the suction surface 45a will be described with reference to FIG. The continuous paper WP performs an operation of loosening the continuous paper WP as in S02 in order to prevent the continuous paper WP from being attracted to the suction surface 45a in a state where wrinkles due to tension are generated.

  Since tension is applied to the continuous paper WP during conveyance, wrinkles may occur in the continuous paper WP, and the suction surface 45a may come into contact with the non-inspected surface of the continuous paper WP, possibly damaging the continuous paper WP. In addition, when the ink of the printed image on the continuous paper WP is not dried, wrinkles appear remarkably. Therefore, the continuous paper WP is maintained at a second distance G2 that is greater than the first distance G1 with respect to the suction surface 45a. Thereby, the continuous paper WP can be conveyed in a state sufficiently separated from the suction surface 45a.

  In addition, when the continuous paper WP is conveyed, the CIS sensor 65 is retracted to the retreat position J that does not contact the continuous paper WP, so that contact between the CIS sensor 65 and the continuous paper WP can be prevented. By this. The continuous paper WP can be prevented from being damaged due to the continuous paper WP coming into contact with the CIS sensor 65. Further, when the ink of the printed image on the continuous paper WP is not dried, if the scanner main body 61 comes into contact, the ink adheres to the surface 67a of the cover glass 67, which causes trouble in reading of the CIS sensor 65, but this is prevented. can do.

[Step S05] Release of Adsorption of Continuous Paper WP After the reading operation by the CIS sensor 65 or the shading correction based on the image of the adjustment chart read by the CIS sensor 65, the discharge inspection, etc., the continuous paper WP is adsorbed on the adsorption surface 45a. Release the adsorption. That is, the main control unit 29 stops the fan 49 and releases the suction of the continuous paper WP to the suction surface 45a.

[Step S06] Applying Tension to Continuous Paper WP The main control unit 29 controls the driving rollers 7, 11, 15 and the heat drum 27 to apply a preset tension to the continuous paper WP. Then, a normal printing operation or the like is performed.

  According to the present embodiment, the suction table 43 is provided with the suction port 45b for sucking the continuous paper WP to the suction surface 45a in contact with the non-test surface of the continuous paper WP, and sucks the non-test surface of the continuous paper WP. . Thus, the continuous paper WP is disposed at a predetermined position that can be read by the CIS sensor 65 without being in contact with the CIS sensor 65 that is normally used in contact with the continuous paper WP. Further, when the suction table 45 is sucking the continuous paper WP, the moving mechanism 63 moves the CIS sensor 65 so that the first distance G1 is set between the reading surface 65a of the CIS sensor 65 and the suction surface 45a. Move by. Therefore, the printed image of the inspection surface of the continuous paper WP adsorbed on the adsorption surface 45a can be satisfactorily read by the CIS sensor 65.

  Further, when the inspection surface of the continuous paper WP is sucked by the suction table 41 and the continuous paper WP on the inspection surface is read by the CIS sensor 65 via the suction surface 45a of the suction table 41, the ink of the print image is dried. However, in this embodiment, the non-inspected surface of the continuous paper WP is sucked by the suction table 41, so that the dirt due to the ink adheres to the CIS sensor 65. It is possible to prevent troubles in reading by the CIS sensor 65.

  Further, the suction table 41 is provided with unevenness formed on the substantially entire surface of the suction surface 45a by coating the base material 45c with a paint in which granular beads B are mixed. Accordingly, the suction force can be generated not only through the portion provided with the suction port 45b but also through the gap formed between the unevenness provided on the entire suction surface 45a and the continuous paper WP. Therefore, the entire continuous paper WP in contact with the suction surface 45a can be stably adsorbed, dents and floating portions can be suppressed, and the printed image on the inspection surface of the continuous paper WP can be read well. Further, since the unevenness of the adsorption surface 45a is formed by coating the base material with a paint in which granular beads B are mixed, for example, it is easier than forming the surface by sandblasting aluminum. . In addition, for example, when aluminum, which is relatively easy to surface-treat, is used as a substrate, there is a problem that it is easily deformed. However, a highly rigid material such as iron can be used as the substrate. As a result, it can be formed inexpensively.

  The inspection unit 21 may include drive rollers 9, 11, 15 and a heat drum 27, and a main control unit 29. The main control unit fixes any one of the driving rollers 9 and 15 and the heat drum 27 provided upstream and the driving roller 11 provided downstream, and rotates the other driving roller. As a result, the continuous paper WP is transported inside the transport path 203 sandwiched between the upstream and downstream drive rollers 9, 11, 15 and the heat drum 27, and the continuous paper WP is placed on the suction surface 45a while being loosened. Then, the main control unit 29 places the continuous paper WP on the suction surface 45a and then sucks the continuous paper WP on the suction surface 45a.

  As a result, the continuous paper WP is loosened, so that the tension applied to the continuous paper WP can be released. Therefore, the uneven tension state is eliminated in the continuous paper WP, and wrinkles are generated by a simple procedure from the thin and low-rigidity continuous paper WP to the thick and high-rigidity continuous paper WP. The continuous paper WP can be adsorbed to the adsorbing surface 45a in a state where the above is suppressed.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the embodiment described above, the upstream and downstream drive rollers 7 and 11 are fixed by fixing the upstream drive rollers 7 and 15 and the heat drum 27 and rotating the downstream drive roller 11. , 15 and the heat drum 27, the continuous paper WP is transported inside the transport path 203, and the continuous paper WP is placed on the suction surface 45a while being loosened. In this regard, the driving roller 11 provided downstream may be fixed, and the driving rollers 7 and 15 and the heat drum 27 provided upstream may be rotated.

  Alternatively, the driving rollers 7 and 15 and the heat drum 27 provided on the upstream side and the driving roller 11 provided on the downstream side may be rotated together so that the continuous paper WP is loosened and placed on the suction surface 45a. However, in this method, all of the drive rollers 7, 11, 15 and the heat drum 27 are rotated, so that these controls are complicated. Therefore, control can be simplified by using a method in which one of the upstream and downstream drive rollers is fixed and the other is rotated.

  Further, in the case of the inkjet printing apparatus 1A that prints both sides of the continuous paper WP shown in FIG. 7, the drive rollers 9A, 11A, 15A, 9B, 11B, and 15B and the heat drum extend across both of the adjacent inkjet printing units 2A and 2B. Control of 27A and 27B complicates the control.

  Therefore, in the inspection by the inspection units 21A and 21B, in FIG. 7, in the inkjet printing unit 2A that prints the surface (one surface) of the continuous paper WP, the driving roller 11A downstream of the inspection unit 21A is fixed and the upstream The driving rollers (heat drums) 7A, 15A, and 27A are rotated. In the inkjet printing unit 2B that prints the back surface (the other surface) of the continuous paper WP, the upstream driving rollers (heat drums) 7B, 15B, and 27B of the inspection unit 21B are fixed, and the downstream driving roller 11B is rotated. . Thereby, the control of placing the continuous paper WP on the suction surface 45a while relaxing the continuous paper WP can be easily performed. Reference numeral 81 denotes a mechanism for reversing the front and back of the continuous paper WP.

  The ink jet printing units 2A and 2B have the same configuration as the ink jet printing unit 2 in FIG. 2, but for convenience of illustration, driving rollers (heat drums) 7A, 11A, 15A, 27A, 7B, 11B, Only 15B and 27B, inspection part 21A and 21B, and the nip roller 23 shall be shown.

  (2) In the above-described embodiment and modification (1), the inspection unit 21 is an image inspection apparatus for print adjustment for performing shading correction, discharge inspection, and the like. In this regard, the inspection unit 21 may further include an image inspection configuration for determining whether or not printing is performed so as to inspect whether a printed portion is free from dirt or missing.

  (3) In the above-described embodiments and modifications, the continuous paper WP is described as an example of the print medium. However, the print medium is not limited to paper, and may be a plastic film, a metal thin film, or the like.

  (4) In the above-described embodiments and modifications, the continuous paper WP is described as an example of the print medium. However, the inspection unit shown below may be not only the continuous paper WP but also a separated sheet. . That is, the inspection unit is provided with a suction port 45b for adsorbing the continuous paper WP on the suction surface 45a in contact with the non-inspection surface of the continuous paper WP, and the base material 45c is coated with a paint in which granular beads B are mixed. The suction table 41 in which the unevenness formed by this is provided on substantially the entire surface of the suction surface 45a, the CIS sensor 65 for reading the print image on the inspection surface of the continuous paper WP sucked by the suction surface 45a, and the CIS sensor 65 And a moving mechanism 63 that moves the CIS sensor 65 so that the first distance G1 is set between the reading surface 65a and the suction surface 45a.

  (5) In the above-described embodiment and each modification, the retracted position of the CIS sensor 65 is set to a direction orthogonal to the transport direction 201 of the continuous paper WP, but the vertical direction (that is, the suction surface) of the transport direction 201 of the continuous paper WP. The CIS sensor 65 may be retracted in a direction orthogonal to 45a. Further, the width of the CIS sensor 65 may be equal to or larger than the width orthogonal to the conveyance direction 201 of the continuous paper WP.

  (6) In the above-described embodiments and modifications, an inkjet printing apparatus has been described as an example of a printing apparatus. However, a printing apparatus such as a rotary press used for offset printing, gravure printing, or the like may be used.

DESCRIPTION OF SYMBOLS 1,1A ... Inkjet printer 7,7A, 7B ... Drive roller 11, 11A, 11B ... Drive roller 15, 15A, 15B ... Drive roller 17 ... Printing unit 21, 21A, 21B ... Inspection part 27, 27A, 27B ... Heat Drum 29 ... Main control unit 41 ... Suction table 43 ... Scanner 45 ... Suction plate 45a ... Suction surface 45b ... Suction port 45c ... Substrate 45d ... Uneven layer B ... Beads H ... Transport direction J ... Retraction position G1 ... Reading of CIS sensor Distance between surface and suction surface G2 ... Distance between continuous paper and suction surface 63 ... Movement mechanism 65 ... CIS sensor 65a ... Reading surface 71 ... Guide rail 73 ... Drive unit WP ... Continuous paper 203 ... Conveyance path

Claims (8)

An adsorption table for adsorbing the print medium on an adsorption surface in contact with the non-inspection surface of the print medium, and an adsorption table for adsorbing the non-inspection surface;
A reading sensor for reading a print image of the inspection surface of the print medium adsorbed on the adsorption surface;
A moving mechanism that moves the reading sensor so that the first distance between the reading surface of the reading sensor and the suction surface is a preset first distance when the suction table is sucking the print medium;
An image inspection apparatus comprising: The image inspection apparatus according to claim 1,
An image inspection apparatus, wherein the suction table is provided with unevenness formed by coating a base material with a paint in which granular beads are mixed, on the entire surface of the suction surface. The image inspection apparatus according to claim 1 or 2,
The image inspection apparatus, wherein the reading sensor is a CIS sensor. In the image inspection apparatus according to any one of claims 1 to 3,
A plurality of drive rollers that are provided upstream and downstream of a transport path of the print medium with respect to the suction table, and transport the print medium;
The print medium is transported inside the transport path sandwiched between the upstream and downstream drive rollers, the print medium is slackened and placed on the suction surface, and the print medium is placed on the suction surface and then printed. An image inspection apparatus comprising: a control unit that adsorbs a medium to the adsorption surface. The image inspection apparatus according to claim 4,
The conveyance of the print medium to the inside of the conveyance path sandwiched between the upstream and downstream drive rollers is to fix either the drive roller provided upstream or the drive roller provided downstream, An image inspection apparatus, which is performed by rotating the other driving roller. In the image inspection apparatus according to any one of claims 1 to 5,
The print medium is maintained at a second distance greater than the first distance with respect to the suction surface during conveyance,
The image inspection apparatus according to claim 1, wherein the reading sensor is retracted to a retracted position that does not contact the print medium during conveyance. The image inspection apparatus according to claim 6,
The moving direction of the reading sensor is a direction orthogonal to the transport path of the print medium on the inspection surface,
The image inspection apparatus according to claim 1, wherein the retreat position is a position obtained by extending a moving direction of the retreat position and is a position outside the transport path. Adsorb the non-inspection surface by an adsorption table provided with an adsorption port for adsorbing the print medium to an adsorption surface in contact with the non-inspection surface of the print medium,
Printing the inspection surface of the print medium adsorbed on the adsorption surface by moving the read sensor by a moving mechanism so that the first distance between the reading surface of the reading sensor and the adsorption surface is set in advance. An image inspection method, wherein an image is read by the reading sensor.

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