Image Inspection Equipment

Abstract

To provide an image inspection device which can inspect an image of an inspection target object highly precisely while conveying a piece of print paper P from upper conveyance means to lower conveyance means.SOLUTION: An image inspection device 1 inspects a piece of print paper P, which first conveyance means 11 of a print device 2 has conveyed at a first conveyance rate V1, by first inspection means 21 while second conveyance means 12 of an inspection device 3 is conveying the print paper P at a second conveyance rate V2. The first inspection means 21 is arranged in a lower position distant from the middle position (C) between the first and second conveyance means by a size L1 larger than the half the length of the print paper. Since an inspection by the first inspection means is started after the rate of conveying the print paper becomes V2, even if the rate V1 and the rate V2 are not essentially the same, there is no disturbances in the image read by the first inspection means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image inspection device that inspects an image formed on a sheet-like object to be inspected, and in particular to an image inspection device that can inspect with high precision an image formed on an object to be inspected while the object to be inspected is transported from an upstream transport means by another downstream transport means. [Background technology]

[0002] Patent Document 1 discloses an invention of an image forming apparatus. As shown in FIG. 1 of the document, this image forming apparatus has a camera unit 230 for image inspection. This camera unit 230 is provided with a sheet conveying path 223 that conveys a sheet from upstream to downstream while being sandwiched between rollers, and two cameras 231 and 232 are arranged to face each other at the same positions above and below the sheet conveying path 223. In the camera unit 230, the sheet is conveyed in one direction along the sheet conveying path 223, during which the two cameras 231 and 232 read images of the upper and lower surfaces of the conveyed sheet, respectively. The sheet inspection device 150 inspects the image printed on the sheet using the captured image of the sheet sent from the camera unit 230. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2018-31963 Summary of the Invention [Problem to be solved by the invention]

[0004] The camera unit of the image forming apparatus disclosed in Patent Document 1 is provided with a roller conveying section in which pairs of rollers that rotate while pinching the sheet from above and below are arranged at a predetermined interval as a conveying means for conveying the sheet, and the camera unit is designed to capture an image of the sheet between the pairs of rollers. Because there is no member between the pairs of rollers that holds and guides the sheet, the position of the sheet conveyed at high speed is difficult to stabilize, and the sheet may exhibit a behavior in which its position fluctuates in a direction perpendicular to the paper surface. If the camera unit is an imaging device with a shallow focal depth, such as a CIS, it becomes impossible to read the image when the sheet moves in the focal depth direction in this way.

[0005] Therefore, the inventor of this application has invented an image inspection device that inspects the image of the print paper with a camera while transporting the print paper with a suction-type transport means, as shown in Figure 9. This image inspection device 1a is composed of a printing device 2, an inspection device 3a, and a post-processing device 4, which are arranged in this order along the direction in which the print paper moves.

[0006] The printing device 2 includes a plurality of storage sections 5 that store a plurality of types of printing paper, a loop-shaped transport path 6 that is connected to the storage sections 5 and can transport the printing paper twice along the same path by inverting it upside down, a first transport means 11 that is provided in a part of the transport path 6 and transports the printing paper by adsorbing it, and a printing means 7 that is provided above the first transport means 11 and ejects ink onto the printing paper transported by the first transport means 11 to form an image. The first transport means 11 includes a belt conveyor 8 that is a belt with many holes formed therein and that is wound around a plurality of rollers, and a suction means (not shown) that is provided on the underside of the belt of the belt conveyor 8 and adsorbs the printing paper to the upper side of the belt, and the suction means adsorbs the printing paper to the upper side of the belt, and the belt is moved to transport the printing paper. For convenience, the exposed side of the printing paper transported by the first transport means 11 is called the front side, and the opposite side is called the back side.

[0007] The inspection device 3a is connected to the first conveying means 11 of the previous printing device 2, and includes a second conveying means 12 that adsorbs and conveys the printed paper with the front side exposed on the upper side, and a first inspection means 21 that is arranged above the upstream side of the second conveying means 12 and faces downward to inspect the image on the front side of the printed paper. The configuration of the second conveying means 12 is generally the same as that of the first conveying means 11. In addition, on the downstream side of the second conveying means 12, there are provided a third conveying means 13 that adsorbs and conveys the printed paper sent from the previous second conveying means 12 with the back side exposed on the lower side, and a second inspection means 22 that is arranged below the upstream side of the third conveying means 13 and faces upward to inspect the image on the back side of the printed paper. The configuration of the third conveying means 13 is generally the same as that of the first conveying means 11 and the second conveying means 12, but is arranged in an inverted position with the top and bottom reversed.

[0008] The post-processing device 4 is a device that receives the print paper whose front and back images have been inspected by the inspection device 3a, performs various necessary post-processing thereon, and discharges it as a final product.

[0009] According to this image inspection device 1a, the first conveying speed V1 of the first conveying means 11 of the printing device 2 and the second conveying speed V2 of the second conveying means 12 of the inspection device 3a are controlled to be substantially identical, and if this control is performed correctly, no problems arise in the inspection of the image on the printed paper by the first inspection means 21 of the inspection device 3a.

[0010] However, when the first conveying speed V1 and the second conveying speed V2 are not substantially the same, problems occur in reading the image when the image on the printed paper is inspected by the first inspection means 21 of the inspection device 3a, as will be described below with reference to Figures 10(a) to (c). Figures 10(a) to (c) are diagrams continuously showing a state in which the printed paper is transferred from the first conveying means 11 to the second conveying means 12 and inspected by the first inspection means 21 when, for example, the second conveying speed V2 is faster than the first conveying speed V1 (when the conveying speed on the downstream side is faster than the upstream side).

[0011] 10(a) shows a state in which an image is formed by the printing means 7 while the printing paper P is being adsorbed and transported by the first transport means 11. The leading edge of the printing paper P has not yet reached the second transport means 12, and the printing paper P is being transported at the first transport speed V1 (<the second transport speed V2).

[0012] 10(b) shows a state in which an image is formed on the trailing end of the print paper P by the printing means 7 while the print paper P is being transported by the first transport means 11 and the second transport means 12. The leading end of the print paper P has already reached the second transport means 12, and inspection of the image by the first inspection means 21 has begun while the print paper P is receiving the transport force of the second transport means 12, but since the portion of the print paper P that is adsorbed and transported by the first transport means 11 is longer than the portion that is adsorbed and transported by the second transport means 12, the print paper P is being transported at the first transport speed V1 (<the second transport speed V2).

[0013] 10(c) shows a state in which image formation by the printing means 7 has been completed, and the print paper P is being inspected for the image by the first inspection means 21 while being transported by the first transport means 11 and the second transport means 12. The portion of the print paper P that is adsorbed and transported by the second transport means 12 is longer than the portion that is adsorbed and transported by the first transport means 11, so the print paper P is being transported at the second transport speed V2 (>first transport speed V1). In other words, the transport speed of the print paper P is faster.

[0014] FIG. 11 is a graph showing the behavior of the printing paper P in the image inspection shown in FIGS. 10(a) to (c) in terms of the relationship between the time elapsed since transport began (horizontal axis) and the position of the printing paper P relative to the position at which transport began (vertical axis). The slope of the straight line in this graph indicates the transport speed of the printing paper P. According to this graph, when a predetermined time has elapsed since transport of the printing paper P began and the printing paper P has reached a predetermined position, the transport speed of the printing paper P increases. In other words, as explained with reference to FIG. 10, the transport speed of the printing paper P increases from the first transport speed V1 of the first transport means 11 to the second transport speed V2 of the first transport means 12. 2 The conveying speed of the conveying means 11 is increased to a second conveying speed V2 (>first conveying speed V1).

[0015] Fig. 12 shows an example of an image read by the first inspection means 21 during image inspection of printing paper P in the image inspection device 1a, with Fig. 12(a) being the image when read normally and Fig. 12(b) being the image when read in the state shown in Fig. 10 and Fig. 11. The image shows hiragana characters from the "a" and "ka" rows lined up vertically, and is read by the first inspection means 21 from top to bottom in Fig. 12.

[0016] In reading an image by the image inspection device 1a, if the first conveying speed V1 and the second conveying speed V2 are substantially equal, the printing paper is conveyed at a uniform speed (V1=V2), so that no distortion occurs in the image read by the first inspection means 21 as shown in FIG. 12(a). However, as described with reference to FIG. 10 and FIG. 11, when the conveying speed of the printing paper P increases, when an image of the printing paper P conveyed at the relatively low first conveying speed V1 is read, it becomes a long image relatively elongated in the conveying direction as shown in the upper half of FIG. 12(b), and when an image of the printing paper P conveyed at the relatively high second conveying speed V2 is subsequently read, it becomes a short image relatively contracted in the conveying direction as shown in the lower half of FIG. 12(b). When the conveying speed of the printing paper P changes in the middle of reading the image in this way, the read image becomes distorted, which hinders correct inspection. The above has been an example in which the transport speed of the printing paper P increases while the image is being read. However, if the transport speed decreases, the image will become distorted, with the upper half being short and the lower half being long in the reading direction, as opposed to Figure 12(b).

[0017] The present invention is an invention made by the present inventor in consideration of the problems of the conventional technology, and aims to solve a newly discovered problem, and to provide an image inspection device that can inspect an image formed on an object to be inspected with high accuracy while transporting the object to be inspected from an upstream transport means to a downstream transport means. [Means for solving the problem]

[0018] The image inspection device of the present invention comprises: An image inspection device comprising: a downstream second conveying means for conveying a sheet-like inspection object conveyed by an upstream first conveying means at a first conveying speed, at a second conveying speed; and an inspection means for inspecting an image formed on the inspection object conveyed by the second conveying means, The first conveying speed and the second conveying speed are controlled to be the same, but they are not the same. Not yet, The inspection means includes: The first conveying means and the second conveying means are simultaneously conveyed, but the first conveying means Therefore, the portion conveyed by the second conveying means is longer than the portion being conveyed. Inspect the image of the object to be inspected. It is characterized by the following. Effect of the Invention

[0019] According to the image inspection device of the present invention, the image of the inspection object can be inspected by the inspection means while the inspection object is transported by the first transport means on the upstream side and the second transport means on the downstream side. In this case, even if the first transport speed and the second transport speed are not substantially the same, the timing when the inspection means starts inspecting the image of the inspection object is after the transport speed of the inspection object becomes the second transport speed, so that the transport speed of the inspection object during inspection is constant at the second transport speed and does not change, and therefore no disturbance occurs in the image read by the inspection means. [Brief description of the drawings]

[0020] [Figure 1] 1 is an overall configuration diagram of an image inspection device according to a first embodiment; [Diagram 2] 5A to 5C are diagrams successively illustrating steps of inspecting an image on a printed sheet in the image inspection device of the first embodiment when the second transport speed of the inspection device is faster than the first transport speed of the printing device. [Diagram 3] 4A to 4C are diagrams successively illustrating steps of inspecting an image on a printed sheet in the image inspection device of the first embodiment when a first transport speed of a printing device is faster than a second transport speed of an inspection device. [Figure 4] FIG. 11 is a diagram showing the overall configuration of an image inspection device according to a second embodiment. [Diagram 5] FIG. 13 is a diagram showing a part of the overall configuration of an image inspection device according to a third embodiment. [Figure 6]FIG. 13 is a diagram showing the overall configuration of an image inspection device according to a fourth embodiment. [Figure 7] FIG. 13 is a diagram showing a barcode that is an image pickup target of a camera in an image inspection device according to a fourth embodiment. [Figure 8] FIG. 13 is an overall configuration diagram of an image inspection device according to a fifth embodiment. [Figure 9] 1 is a diagram showing the overall configuration of an image inspection device proposed by the present inventor prior to the present invention. [Figure 10] 10 is a diagram successively showing steps of inspecting an image on a print sheet in the image inspection device shown in FIG. 9 when the second transport speed of the inspection device is faster than the first transport speed of the printing device. [Figure 11] 10 is a graph showing changes in the speed of a printing paper when inspecting an image on the printing paper in the image inspection device shown in FIG. 9 when the second transport speed of the inspection device is faster than the first transport speed of the printing device. [Figure 12] 10A and 10B show images of a printed sheet of paper read by an inspection means in the image inspection device shown in FIG. 9, where FIG. 10A shows an image read correctly when the first conveying speed of the printing device and the second conveying speed of the inspection device are substantially the same, and FIG. 10B shows an image read in a distorted state in the case shown in FIG. 9 and FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] A first embodiment of the present invention will be described with reference to FIGS. 1, this image inspection device 1 is configured such that a printing device 2, an inspection device 3, and a post-processing device 4 are arranged along the direction in which a print paper P moves. The printing device 2 forms an image on the print paper P, and the image formed on the print paper P is inspected by the inspection device 3. Therefore, the object to be inspected in the image inspection device 1 of this embodiment is the print paper P on which the image has been formed.

[0022] The printing device 2 is equipped with multiple storage units 5 that store multiple types of printing paper P, a loop-shaped transport path 6 that is connected to the storage units 5 and can transport the printing paper P twice over by inverting it, a first transport means 11 that is provided in part of the transport path 6 and absorbs and transports the printing paper P, and a printing means 7 that is disposed above the first transport means 11 and ejects ink onto the printing paper P transported by the first transport means 11 to form an image. The printing means 7 has multiple inkjet heads with different ink colors and can form color images on both sides of the printing paper P.

[0023] The first conveying means 11 has a belt conveyor 8 with a conveying belt 14 wound around a downstream driving roller 9, an upstream driven roller 10, and two other small driven rollers 10a and 10b. The conveying belt 14 has a number of through holes. A platen (not shown) with a number of through holes is in contact with the lower surface of the conveying belt 14 on the upper side of the first conveying means 11, and a chamber (not shown) is attached to the lower surface of the platen, and the inside of the chamber is sucked by a fan (not shown). In this way, the first conveying means 11 is an adsorption conveying means, and when the fan is driven, air is sucked into the chamber from above the conveying belt 14 through the through holes of the conveying belt 14 and the platen, so that the printing paper P is adsorbed to the upper surface side of the conveying belt 14, and when the conveying belt 14 is driven, the printing paper P can be conveyed at the first conveying speed V1.

[0024] The upstream side and downstream side are used to mean the upstream side and downstream side in the transport direction in which each transport means 11, 12, 13 transports the printing paper P. For convenience, the exposed surface of the printing paper P transported from the first transport means 11 to the second transport means 12 is called the front side, and the opposite side is called the back side.

[0025] The inspection device 3 includes a second conveying means 12 and a first inspection means 21. The second conveying means 12 is connected to the first conveying means 11 of the previous printing device 2, and adsorbs and conveys the print paper P with the front side exposed. The first inspection means 21 is set to read the image in synchronization with the second conveying speed V2 of the second conveying means 12. The configuration of the second conveying means 12 is generally the same as that of the first conveying means 11. The second conveying means 12 conveys the print paper P at the second conveying speed V2. The first inspection means 21 is disposed downward above the downstream side of the second conveying means 12, and inspects the image on the front side of the print paper P. The downstream position of the second conveying means 12 where the first inspection means 21 is disposed is a position downstream by a dimension L1 that is more than half the length of the print paper P from the midpoint between the first conveying means 11 and the second conveying means 12 shown by the center line C in FIG. 1. In the image inspection device 1, printing paper P of various sizes may be used. In such a case, it is preferable to select the one with the longest length in the conveying direction among the printing paper P that may be used as the criterion for setting the dimension L1.

[0026] If the dimension L1 is set as described above, when the leading edge of the printing paper P reaches the first inspection means 21, only the upstream portion of the printing paper P, which is less than half the length of the printing paper P in the transport direction, is subjected to the transport force of the first transport means 11, while the downstream portion, which is more than half the length of the printing paper P in the transport direction, is subjected to the transport force of the second transport means 12. In other words, the timing at which the first inspection means 21 starts inspecting the image of the printing paper P is after the transport speed of the printing paper P becomes the second transport speed V2, so the transport speed of the printing paper P during inspection is constant at the second transport speed V2 and does not change, and therefore no distortion occurs in the image read by the first inspection means 21.

[0027] On the downstream side of the second conveying means 12, there are provided a third conveying means 13 which adsorbs and conveys the printing paper P sent from the preceding second conveying means 12 in a position with the back surface exposed downward, and a second inspection means 22 which is disposed facing upward below the downstream side of the third conveying means 13 and which inspects the image on the back surface of the printing paper P. The configuration of the third conveying means 13 is generally the same as that of the first conveying means 11 and the second conveying means 12, but it is in an inverted position with the top and bottom reversed. In addition, the second inspection means 22 is installed at a position downstream away from the midpoint between the second conveying means 12 and the third conveying means 13 by a length that exceeds the dimension L1.

[0028] In addition, above the driven roller 10 of the second transport means 12 and below the driven roller 10 of the third transport means 13, there are provided pressure rollers 15 for preventing the leading edge of the printing paper P from floating up. These pressure rollers 15 rotate in accordance with the transport belt 14.

[0029] The first inspection means 21 and the second inspection means 22 are CIS (Contact Image Sensor) of the same specifications, but the inspection unit that reads the image formed on the printing paper P for inspection is not limited to a CIS, and may be a sensor with another principle or structure, or a camera.

[0030] The post-processing device 4 is a device that performs various post-processing on the printed paper P on which an image has been formed by the printing device 2 and the image has been inspected by the inspection device 3, and then discharges the printed paper P. The post-processing includes sorting operations such as sorting and stacking, stapling, inserting slip sheets, folding in various ways, inserting into envelopes, etc., and a post-processing device 4 equipped with the necessary functions can be provided according to the purpose.

[0031] According to this image inspection device 1, the first conveying speed V1 of the first conveying means 11 of the printing device 2, the second conveying speed V2 of the second conveying means 12 of the inspection device 3, and the third conveying speed V3 of the third conveying means 13 of the inspection device 3 are controlled to be substantially identical, and when this control is performed correctly, inspection of the image on the printing paper P by the first inspection means 21 and second inspection means 22 of the inspection device 3 is performed without any problems.

[0032] As explained in the section "Problem to be solved by the invention," the image inspection device 1a shown in Figure 9 had problems reading the image on the printing paper P when the first conveying speed V1 and the second conveying speed V2 were not substantially identical. However, as will be explained in detail below, the image inspection device 1 of this embodiment solves this problem by changing the arrangement of the inspection means 21, 22 described above.

[0033] Figures 2(a) to (c) are successive diagrams showing the state in which printing paper P is transferred from the first conveying means 11 to the second conveying means 12 and inspected by the first inspection means 21 when the second conveying speed V2 is greater than the first conveying speed V1 (when the conveying speed on the downstream side is greater than the conveying speed on the upstream side).

[0034] 2(a) shows a state in which an image is formed by the printing means 7 while the printing paper P is being adsorbed and transported by the first transport means 11. The leading edge of the printing paper P has not yet reached the second transport means 12, and the printing paper P is being transported at the first transport speed V1 (<the second transport speed V2).

[0035] 2(b) shows a state in which an image is formed on the rear end of the print paper P by the printing means 7 while the print paper P is being transported by the first transport means 11 and the second transport means 12. The leading edge of the print paper P has already reached the second transport means 12 and is receiving the transport force of the second transport means 12, but since the portion of the print paper P that is adsorbed and transported by the first transport means 11 is longer than the portion that is adsorbed and transported by the second transport means 12, the print paper P is transported at the first transport speed V1 (< the second transport speed V2). The leading edge of the print paper P has reached the second transport means 12, but has not yet reached the first inspection means 21 located near the downstream end of the second transport means 12, and inspection of the image on the print paper P has not yet begun.

[0036] FIG. 2(c) shows a state in which the printing means 7 has completed image formation and the printing paper P is being transported by the first transport means 11 and the second transport means 12. The printing paper P is not affected by the first transport means 11 because the portion of the printing paper P that is adsorbed and transported by the second transport means 12 is longer than the portion of the printing paper P that is adsorbed and transported by the first transport means 11, and is transported at the second transport speed V2 (>first transport speed V1). In other words, the transport speed of the printing paper P is faster than that shown in FIG. 2(b). However, the printing paper P has not yet reached the first inspection means 21, and inspection of the image on the printing paper P has not yet begun. After this, the printing paper P is inspected by the first inspection means 21 while being transported at the second transport speed V2, but since the transport speed is constant at the second transport speed V2 during the inspection, no distortion occurs in the read image, and appropriate inspection can be performed.

[0037] After the printing paper P has been inspected on the front side by the first inspection means 21 and passed through the second transport means 12, the printing paper P is inspected on the back side by the second inspection means 22 while being transported by the third transport means 13. As described above, the second transport speed V2 and the third transport speed V3 are controlled to be substantially the same speed, but even if they were not, the leading edge of the printing paper P reaches the second inspection means 22 and the inspection can start after more than half of the printing paper P has entered the third transport means 13 and the transport speed of the paper has become the third transport speed V3. Therefore, since the transport speed is constant at the third transport speed V3 during the inspection by the second inspection means 22, regardless of whether the third transport speed V3 and the second transport speed V2 are the same or not, no distortion occurs in the image read by the second inspection means 22, and appropriate inspection can be performed using the image read by the second inspection means 22.

[0038] Figures 3(a) to (c) are successive diagrams showing the state in which printing paper P is transferred from the first conveying means 11 to the second conveying means 12 and inspected by the first inspection means 21 when the first conveying speed V1 is greater than the second conveying speed V2 (when the conveying speed is greater on the upstream side than on the downstream side).

[0039] 3(a) shows a state in which an image is formed by the printing means 7 while the printing paper P is being adsorbed and transported by the first transport means 11. The leading edge of the printing paper P has not yet reached the second transport means 12, and the printing paper P is being transported at the first transport speed V1 (>second transport speed V2).

[0040] 3(b) shows a state in which an image is formed on the rear end of the print paper P by the printing means 7 while the print paper P is being transported by the first transport means 11 and the second transport means 12. The leading edge of the print paper P has already reached the second transport means 12 and is receiving the transport force of the second transport means 12, but since the portion of the print paper P that is adsorbed and transported by the first transport means 11 is longer than the portion that is adsorbed and transported by the second transport means 12, the print paper P is transported at the first transport speed V1 (>second transport speed V2). The leading edge of the print paper P has reached the second transport means 12, but has not yet reached the first inspection means 21 located near the downstream end of the second transport means 12, and inspection of the image on the print paper P has not yet begun.

[0041] FIG. 3(c) shows a state in which the printing means 7 has completed image formation and the printing paper P is being transported by the first transport means 11 and the second transport means 12. The printing paper P is not affected by the first transport means 11 and is transported at the second transport speed V2 (<first transport speed V1) because the portion of the printing paper P that is adsorbed and transported by the second transport means 12 is longer than the portion that is adsorbed and transported by the first transport means 11. In other words, the transport speed of the printing paper P is slower than that shown in FIG. 3(b). However, the printing paper P has not yet reached the first inspection means 21, and inspection of the image on the printing paper P has not yet begun. After this, the printing paper P is inspected by the first inspection means 21 while being transported at the second transport speed V2, but since the transport speed is constant at the second transport speed V2 during the inspection, no distortion occurs in the read image and appropriate inspection can be performed.

[0042] After the printing paper P has been inspected on the front side by the first inspection means 21 and passed through the second conveying means 12, it is inspected on the back side by the second inspection means 22 while being transported by the third conveying means 13. As explained with reference to Figure 2, regardless of whether the third conveying speed V3 of the third conveying means 13 and the second conveying speed V2 of the second conveying means 12 are the same or not, no distortion occurs in the image read by the second inspection means 22 and appropriate inspection can be performed.

[0043] A second embodiment of the present invention will be described with reference to FIG. Fig. 4 shows an image inspection device 1' of the second embodiment. The basic configuration of the image inspection device 1' of the second embodiment is the same as that of the image inspection device 1 of the first embodiment, and in Fig. 4, parts corresponding to those of the first embodiment are given the same reference numerals as those of Fig. 1, and the explanation of the first embodiment is incorporated herein. As will be described below, the second embodiment differs from the first embodiment in the arrangement of the first inspection means 21 and the second inspection means 22.

[0044] As shown in FIG. 4, the first inspection means 21 of the image inspection device 1' of the second embodiment is disposed facing downward above the upstream side of the second conveying means 12, and the distance L2 between the downstream end of the upstream first conveying means 11 is set to a dimension that exceeds the length of the printing paper. The downstream end of the first conveying means 11 does not mean the right end of the drive roller 9 around which the conveying belt 14, which is the end in shape, is wound, but means the rightmost position in the first conveying means 11 that can apply a conveying force to the printing paper P. In this embodiment, the maximum paper size used in this image inspection device 1' is A3, and in consideration of the vertical length of the paper being 420 mm, L2=420 mm. With this configuration, the length of the inspection device 3' in the conveying direction in the second embodiment is longer than that in the first embodiment.

[0045] 4, the second inspection means 22 of the image inspection device 1' of the second embodiment is disposed facing upward below the upstream side of the third conveying means 13. The second conveying means 12 and the third conveying means 13 are installed side by side with no gap between them, as in the first embodiment.

[0046] According to the image inspection device 1' of the second embodiment, even when A3 paper is transported vertically as the printing paper P, when the leading edge of the printing paper P reaches the first inspection means 21, the trailing edge of the printing paper P has already left the first transport means 11, and the printing paper P receives only the transport force of the second transport means 12. That is, the timing when the first inspection means 21 starts inspecting the image of the printing paper P is after the transport speed of the printing paper P becomes the second transport speed V2, so the transport speed during inspection of the printing paper P is constant at the second transport speed V2 and does not change, so no distortion occurs in the image read by the first inspection means 21. If the printing paper P is shorter in the transport direction than A3, the same effect can be obtained.

[0047] In the image inspection device 1' of the second embodiment, if the distance between the downstream end of the second conveying means 12 and the second inspection means 22 is 420 mm, the same as L2, the length of the inspection device 3' in the conveying direction will be longer than that shown in Fig. 4. However, when A3 printing paper P is conveyed in portrait orientation, even if the conveying speed V2 of the second conveying means 12 and the conveying speed V3 of the third conveying means 13 are not substantially the same, inspection by the second inspection means 22 begins after the printing paper P is conveyed at a constant speed of conveying speed V3, so no problems will occur in the inspection by the second inspection means 22.

[0048] In the first and second embodiments described above, an adsorption conveying means using a suction fan as a conveying means is shown, but the adsorption means may use the principle of electrostatic adsorption, and the adsorption principle and structure are not important. Also, problems in the image inspection on the downstream side due to the difference in the conveying speed on the upstream side and the conveying means on the downstream side occur not only when the conveying means is of the adsorption type, but also when the conveying means is of the roller conveying type, and an example of such a case will be described next as the third embodiment.

[0049] A third embodiment of the present invention will be described with reference to FIG. FIG. 5 shows an image inspection device 1" of the third embodiment. Among the configurations of the image inspection device 1" of the third embodiment, parts common to the first embodiment are given the same reference numerals as in FIG. 1, and the explanation of the first embodiment will be referred to. As will be explained below, the third embodiment differs from the first and second embodiments in that the conveying means is of the roller type and in the arrangement of the first inspection means 21.

[0050] As shown in Figure 5, the first conveying means 11' of the printing device 2' and the second conveying means 12' of the inspection device 3" are roller conveying means. The first conveying means 11' and the second conveying means 12' each have two pairs of combinations of drive rollers 9 and driven rollers 10 that convey the printing paper P by clamping it and providing a holding force. Also in Figure 5, symbol 25 indicates the conveying path for the printing paper P that runs downstream from the first conveying means 11' through the second conveying means 12'.

[0051] As shown in FIG. 5, the arrangement of the first inspection means 21 in the third embodiment is different from that in the first and second embodiments. In this embodiment, the first conveying speed V1 of the first conveying means 11' on the upstream side and the second conveying speed V2 of the second conveying means 12' on the downstream side are controlled to be the same, but due to the tolerance of components and the like, they may not be substantially the same. In such a case, when the printing paper P is held and conveyed only by the first conveying means 11' on the upstream side, the conveying speed of the printing paper P is V1, but when the printing paper P is simultaneously held and conveyed by the first conveying means 11' on the upstream side and the second conveying means 12' on the downstream side, the conveying speed of the printing paper P is not constant, and when the printing paper P is held and conveyed only by the conveying means on the downstream side, the conveying speed of the printing paper P is V2.

[0052] Therefore, in this embodiment, the first inspection means 21 is disposed downstream of the position of the leading edge of the printing paper P at the time when the printing paper P is given a holding force only from the second conveying means 12' and the conveying speed becomes the second conveying speed V2. That is, as shown in FIG. 5, if the distance from the nip point of the driving roller 9 and the driven roller 10 on the most downstream side where the first conveying means 11' gives a holding force to the printing paper P to the inspection position of the first inspection means 21 is L3, this L3 may be equal to or greater than the length of the printing paper P in the conveying direction minus the length of the margin from the leading edge of the printing paper P to the image reading start position. If the first inspection means 21 is disposed in this way, as shown in FIG. 5, immediately after the rear end of the conveyed printing paper P leaves the first conveying means 11' and the conveying speed becomes constant at the second conveying speed V2, the leading edge of the printing paper P passes the inspection position of the first inspection means 21 and inspection is started from the image closest to the leading edge.

[0053] As explained above, the conveying means in the present invention is not limited to the suction type as in the first and second embodiments, but when a roller conveying means as in the third embodiment is used, there is a possibility that the paper will flutter in a direction perpendicular to the paper surface during conveyance, so it is preferable to adopt another image inspection device with a shallow focal depth as the inspection means rather than a CIS with a deep focal depth.

[0054] A fourth embodiment of the present invention will be described with reference to FIGS. Fig. 6 shows an image inspection device 100 of the fourth embodiment. Among the configuration of the image inspection device 100 of the fourth embodiment, the parts common to the first embodiment are given the same reference numerals as those in Fig. 1, and the description of the first embodiment is incorporated herein. As will be described below, the fourth embodiment differs from the first embodiment in that the first inspection means provided facing downward above the second conveying means 12 includes two parts, a camera 31 as a first inspection unit, and a CIS 32 as a second inspection unit.

[0055] Although Fig. 6 does not show a configuration equivalent to the third transport means 13 in the first embodiment, this is not necessary if only the front surface of the print paper P is to be inspected. Of course, a configuration equivalent to the third transport means 13 in the first embodiment may be provided in Fig. 6 so that the back surface of the print paper P can also be inspected. In that case, a camera and a CIS may be provided as in the case of the second transport means 12 as the second inspection means 22 provided facing upward below the third transport means 13, as necessary.

[0056] Camera 31 has a deeper focal depth and a relatively larger allowable error in its installation position compared to CIS 32, which is the second inspection unit. As an example of numerical values, if the installation position is 120 mm from the object to be imaged, the allowable error is about ±2 to 3 mm. Also, its reading accuracy is relatively high compared to CIS 32, which is the second inspection unit, and as an example of numerical values, it is about 300 dpi. Because camera 31 has such high reading accuracy, it is used to capture images that require particularly high-precision reading out of the images formed on printing paper P, which is the object to be inspected.

[0057] FIG. 7 shows a barcode as an example of an image captured by the camera 31. The barcode is composed of a combination of narrow bars NB and wide bars WB, narrow spaces NS and wide spaces WS. The ratio of the width of the narrow bars NB and wide bars WB and the ratio of the width of the narrow spaces NS and wide spaces WS in the reading direction of the barcode (the vertical direction in FIG. 7, i.e., the direction perpendicular to the bars) is set to a predetermined value of, for example, about 1:2 to 1:3. The left diagram in FIG. 7 shows an image of a barcode read by the camera 31 when the paper is conveyed at a conveying speed V1, and the right diagram in FIG. 7 shows an image of the same barcode read by the camera 31 when the paper is conveyed at a conveying speed V2 that is higher than the conveying speed V1. That is, even if it is the same barcode, the image read when the paper is conveyed at a conveying speed V2 that is faster than the conveying speed V1 is stretched in the reading direction compared to the image read when the paper is conveyed at the conveying speed V1. Therefore, if the conveying speed of the paper changes while reading the barcode, the ratio of the image of the read barcode changes within one image, making it impossible to read. In addition, the extent to which the ratio of the width of the narrow bar NB to the wide bar WB specified in the barcode can deviate from the specified value before the barcode becomes unreadable depends on the performance of the reading device (camera).

[0058] Therefore, like the first inspection means 21 in the first embodiment, the camera 31 is disposed at a position where image inspection can begin when the conveying speed of the printing paper P becomes the second conveying speed V2. That is, the position is downstream by a dimension equal to or more than half the length of the printing paper P (indicated by L1 in FIG. 1 in the first embodiment) from the midpoint between the first conveying means 11 and the second conveying means 12, and in this embodiment, the position is in the vicinity of the drive roller 9 of the second conveying means 12.

[0059] The CIS32 has a shallow focal depth and a relatively small allowable error in the installation position compared to the camera 31, which is the first inspection unit. As a numerical example, if the installation position is 12 mm from the image pickup target, the allowable error is about ±0.2 mm. In addition, the reading accuracy is relatively low compared to the camera 31, which is the first inspection unit, and is about 200 dpi as a numerical example. Since the reading accuracy of the CIS32 is low, it is used to capture images other than those that require particularly high-precision reading among images formed on the printing paper P, which is the inspection object. For example, it is used when inspecting the entire surface of an image printed on the printing paper P based on bitmap data. There is little need to use the camera 31 to read such images, and the CIS32 is sufficient in terms of reading accuracy. In addition, even if the paper conveying speed changes during reading by the CIS32, it has little effect on reading, so there is little need to satisfy the conditions for the position where the CIS32 is installed, as in the case of the camera 31. That is, the CIS 32 may be provided in the vicinity of the pressure roller 15, which is on the upstream side of the camera 31 in the second conveying means 12.

[0060] According to the image inspection device 100 of the fourth embodiment, the object to be read by the camera 31 is a barcode that requires high-precision reading, but the reading accuracy of the camera 31 has the resolution required to read the barcode. In addition, the timing at which the camera 31 starts inspecting the image of the print paper P is after the conveying speed of the print paper P becomes the second conveying speed, so even if the first conveying speed and the second conveying speed are not substantially the same, the conveying speed of the print paper P is constant at the second conveying speed during the inspection of the print paper P by the camera 31 and does not change. Therefore, no distortion occurs in the image read by the camera 31, and there is no problem with reading. On the other hand, the object to be read by the CIS 32, which has a relatively low reading accuracy, is an image that does not require high-precision reading, so even if the conveying speed of the print paper P changes during conveyance, there is no substantial problem with reading by the CIS 32. Note that instead of the camera 31, a barcode reader that performs optical reading using a laser or the like can also be used.

[0061] A fifth embodiment of the present invention will be described with reference to FIG. Fig. 8 shows an image inspection device 200 of the fifth embodiment. Among the configuration of the image inspection device 200 of the fifth embodiment, the parts common to the first embodiment are given the same reference numerals as those in Fig. 1, and the description of the first embodiment is incorporated herein. As will be described below, the fifth embodiment differs from the first embodiment in that the first inspection means provided facing downward above the second conveying means 12 includes two cameras, camera 31a and camera 31b, as a first inspection section.

[0062] Note that Fig. 8 does not show a configuration equivalent to the third conveying means 13 in the first embodiment, but this is not necessary if only the front side of the printing paper P is to be inspected. Of course, a configuration equivalent to the third conveying means 13 in the first embodiment may be provided in Fig. 8 so that the back side of the printing paper P can also be inspected. In that case, two cameras may be provided as second inspection means 22, which is provided below the third conveying means 13 facing upward, as necessary, in the same manner as the second conveying means 12.

[0063] The camera 31a and the camera 31b are the same as the camera 31 in the fourth embodiment, and both are inspection means with high reading accuracy that have a greater focal depth and a relatively larger allowable error in the installation position compared to a CIS.

[0064] One of the cameras, 31a, is used to capture images that require particularly high-precision reading among images formed on the print paper P that is the object to be inspected, and specifically, reads barcodes as described in the fourth embodiment. Thus, like the camera 31 in the fourth embodiment, the camera 31a is disposed at a position where image inspection can begin when the conveying speed of the print paper P becomes the second conveying speed V2. That is, the camera 31a is located downstream from the midpoint between the first conveying means 11 and the second conveying means 12 by a dimension of more than half the length of the print paper P (indicated by L1 in FIG. 1 in the first embodiment), and in this embodiment, the camera 31a is located near the drive roller 9 of the second conveying means 12.

[0065] The other camera 31b is used to capture images formed on the print paper P, which is the object to be inspected, other than images that require particularly high-precision reading. For example, it is used when reading page numbers (numbers) on print paper and other characters. When reading characters with a camera, the influence on reading is smaller even if the paper conveyance speed changes during reading compared to the case of barcodes, etc., so the position where camera 31b is installed does not need to satisfy the conditions as in the case of camera 31a. In other words, camera 31b may be installed near the pressure roller 15, which is upstream of camera 31a on the second conveyance means 12.

[0066] According to the image inspection device 200 of the fifth embodiment, the object to be read by the camera 31a is a barcode that requires high-resolution reading, but the reading accuracy of the camera 31a has the resolution required to read the barcode. In addition, the timing at which the camera 31a starts inspecting the image of the print paper P is after the conveying speed of the print paper P becomes the second conveying speed, so even if the first conveying speed and the second conveying speed are not substantially the same, the conveying speed of the print paper P is constant at the second conveying speed during the inspection of the print paper P by the camera 31a and does not change. Therefore, no distortion occurs in the image read by the camera 31a, and there is no problem with reading. On the other hand, the object to be read by the camera 31b is a character that does not require high-resolution reading, so even if the conveying speed of the print paper P changes during conveyance, there is no substantial problem with reading by the camera 31b. Note that instead of the camera 31a, a barcode reader that performs optical reading using a laser or the like can also be used.

[0067] Configuration and Effects of Image Inspection Device 1 of Each Aspect in the Embodiments The image inspection apparatus 1, 1', 1" of the first embodiment is First conveying means 11 on the upstream side ,11’ The second conveying means 12 on the downstream side conveys the sheet-shaped inspection object P conveyed by the conveying means 11 at a first conveying speed V1 at a second conveying speed V2. ,12’ and the second conveying means 12 ,12’and an inspection means 21 for inspecting an image formed on an object to be inspected P conveyed by the image inspection device 1, 1', 1'', The first conveying speed V1 and the second conveying speed V2 are controlled to be the same. It is not one, The inspection means 21 includes: The first conveying means 11, 11' and the second conveying means 12, 12' are conveyed simultaneously. However, the portion transported by the second transport means is larger than the portion transported by the first transport means 11, 11'. The image of the object P, the portion of which is transported by the stages 12 and 12', is inspected. It is characterized by the following.

[0068] According to the image inspection apparatus 1, 1', 1" of the first aspect, The inspection means 21 can inspect the image of the inspection object P while the inspection object P is being transported by the first transport means 11 on the upstream side and the second transport means 12 on the downstream side. In this case, even if the first transport speed V1 and the second transport speed V2 are not substantially the same, the timing at which the inspection means 21 starts inspecting the image of the inspection object P is after the transport speed of the inspection object P becomes the second transport speed V2. Therefore, the transport speed of the inspection object P during inspection is constant at the second transport speed V2 and does not change, so no disturbance occurs in the image read by the inspection means 21.

[0069] The image inspection apparatus 1, 1', 1" of the second embodiment is the image inspection apparatus 1, 1', 1" of the first embodiment, covered The holding force that determines the transport speed of the test object is provided only by the second transport means 12, 12'. Attitude Started Time downstream of the position of the tip of the test object P at , the inspection means 21 It is characterized by being placed

[0070] According to the image inspection apparatus 1, 1', 1" of the second embodiment, The inspection means 21 can inspect the image of the inspection object P while the first conveying means 11 on the upstream side and the second conveying means 12 on the downstream side hold and convey the inspection object P. Here, the inspection means 21 is disposed downstream of the position of the tip of the inspection object P at the time when the holding force of the conveying means that determines the conveying speed of the inspection object P is applied by the second conveying means 12, 12'. Therefore, even if the first conveying speed V1 and the second conveying speed V2 are not substantially the same, the timing when the inspection means 21 starts inspecting the image of the inspection object P is after the conveying speed of the inspection object P becomes the second conveying speed V2 under the action of the holding force of the second conveying means 12, 12'. Therefore, the conveying speed of the inspection object P during inspection is constant at the second conveying speed V2 and does not change, so that no disturbance occurs in the image read by the inspection means 21.

[0071] The image inspection apparatus 1, 1', 1" of the third embodiment is the image inspection apparatus 1, 1', 1" of the first embodiment, covered Transport speed of inspection object P but The second conveying speed V 2 and Became Time downstream of the position of the tip of the test object P at , the inspection means 21 It is characterized by being placed

[0075] The image inspection apparatus 100 of the fourth aspect is the image inspection apparatus of the first aspect, The inspection means has a relatively high reading accuracy. camera 31 and From the camera 31 Relatively low reading accuracy CIS Contains 32, The above camera 31, The first conveying means and the second conveying means are conveyed simultaneously. It is characterized in that the inspection object P is disposed at a position where inspection of the image can be started when the transport speed of the inspection object P reaches the second transport speed V2.

[0076] According to the image inspection device 100 of the fourth embodiment, camera 31 is CIS It has higher reading accuracy than 32. Also, cameraThe timing when the inspection of the image of the inspection object P is started by the inspection device 31 is after the conveying speed of the inspection object P becomes the second conveying speed V2. Therefore, even if the first conveying speed V1 and the second conveying speed V2 are not substantially the same, camera During the inspection of the object P by the inspection device 31, the transport speed of the object P is constant at the second transport speed V2 and does not change. camera The image read by 31 is not distorted and there are no problems with reading. On the other hand, the reading accuracy is relatively low. CIS If the reading target of 32 is an image that does not require high-resolution reading, even if the conveying speed of the inspection object P changes during conveyance, CIS There are no substantial problems with reading it using 32.

[0077] The image inspection apparatus 200 of the fifth aspect is the image inspection apparatus of the first aspect, The inspection means , small At least two camera 31a, 31b, The at least two camera Of 31a and 31b, read images that require high accuracy. On the other hand The above camera 31a, The first conveying means and the second conveying means are conveyed simultaneously. It is characterized in that the inspection object P is disposed at a position where inspection of the image can be started when the transport speed of the inspection object P reaches the second transport speed V2. In the above embodiment, camera teeth camera 31a and camera 31b, but camera may be 3 or more, and these camera Among them, one or more of the following are required to read images with high accuracy: camera However, it is sufficient that the inspection object P is placed at a position where inspection of the image can be started when the transport speed of the inspection object P reaches the second transport speed V2.

[0078] According to the image inspection device 200 of the fifth aspect, camera 31a has a relatively high reading accuracy. Also, cameraThe timing when 31a starts inspecting the image of the inspection object P is after the conveying speed of the inspection object P becomes the second conveying speed V2. Therefore, even if the first conveying speed V1 and the second conveying speed V2 are not substantially the same, camera During the inspection of the object P by 31a, the transport speed of the object P is constant at the second transport speed V2 and does not change. camera The image read by 31a is not distorted, and there is no problem with reading. camera If the object to be read by 31b is an image that does not require high-resolution reading, even if the transport speed of the inspection object P changes during transport, no substantial problem occurs in the reading by the first inspection unit 31b. According to the sixth embodiment of the image inspection device 1, a state in which the portion transported by the second conveying means 12 is longer than the portion transported by the first conveying means 11 is a state in which the holding force that determines the transport speed of the object to be inspected P is provided only by the second conveying means 12, and the inspection means 21 is characterized in being positioned downstream from the midpoint between the first conveying means 11 and the second conveying means 12 by a dimension L1 that is more than half the length of the object to be inspected P. According to the seventh embodiment of the image inspection device 1, when the portion transported by the second conveying means 12 is longer than the portion transported by the first conveying means 11, the transport speed of the object to be inspected is the second transporting speed V2, and the inspection means 21 is arranged downstream from the midpoint between the first conveying means 11 and the second conveying means 12 by a dimension L1 that is more than half the length of the object to be inspected P. [Explanation of symbols]

[0079] 1,1',1”,100,200…Image inspection equipment 2,2'...Printing device 3, 3', 3" ... Inspection device that is the main part of the image inspection function in the image inspection device 4...After-treatment device 8…Conveyor belt 11, 11'...First conveying means 12, 12'...Second conveying means 13...Third conveying means 21...First inspection means 22...Second inspection means 31, 31a, 31b...First inspection unit as inspection means 32...Second Inspection Section as Inspection Means V1: First conveying speed V2: Second conveying speed V3: Third conveying speed P: Printing paper as the object to be inspected

Claims

1. An image inspection device comprising: a downstream second conveying means for conveying a sheet-like inspection object conveyed by an upstream first conveying means at a first conveying speed, at a second conveying speed; and an inspection means for inspecting an image formed on the inspection object conveyed by the second conveying means, The first conveying speed and the second conveying speed are controlled to be the same, but are not the same; The inspection means includes: An image inspection device characterized in that it inspects the image of an object to be inspected which is transported simultaneously by the first transport means and the second transport means, but the portion transported by the second transport means is longer than the portion transported by the first transport means.

2. An image inspection device as described in Claim 1, characterized in that the inspection means is arranged downstream of the position of the tip of the object to be inspected at the time when a state begins in which the holding force that determines the conveying speed of the object to be inspected is provided only by the second conveying means.

3. The image inspection device as described in Claim 1, characterized in that the inspection means is arranged downstream of the position of the tip of the object to be inspected at the time when the conveying speed of the object to be inspected becomes the second conveying speed.

4. The inspection means includes a camera having a relatively high reading accuracy and a CIS having a relatively lower reading accuracy than the camera, 2. The image inspection device according to claim 1, characterized in that the camera is positioned at a position where inspection of the image can be started when the conveying speed of the inspection object being conveyed simultaneously by the first conveying means and the second conveying means becomes the second conveying speed.

5. The inspection means includes at least two cameras; The image inspection device described in claim 1, characterized in that one of the at least two cameras, which reads images that require high accuracy, is positioned at a position where inspection of the image can be started when the conveying speed of the inspection object being conveyed simultaneously by the first conveying means and the second conveying means becomes the second conveying speed.

6. The state in which the portion transported by the second transport means is longer than the portion transported by the first transport means is The image inspection device described in claim 1, characterized in that the holding force that determines the transport speed of the object to be inspected is provided only by the second transport means, and the inspection means is positioned downstream from a position midway between the first transport means and the second transport means by a dimension equal to or more than half the length of the object to be inspected.

7. When the portion transported by the second transport means is longer than the portion transported by the first transport means, the transport speed of the test object is the second transport speed, 2. The image inspection device according to claim 1, wherein the inspection means is disposed downstream of a midpoint between the first conveying means and the second conveying means by a dimension equal to or greater than half the length of the object to be inspected.

Images