JP2005153313A - Imaging device and image checking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To subdue an adverse effect due to the deformation of an image recording medium or a defective conveyance. <P>SOLUTION: In the imaging device 10A, a rolled sheet 12A with a specified pattern 22 preprinted by an invisible imaging material is used; the pattern 22 is read from the rolled sheet 12A using a pattern reading part 90 at a specified position on a conveyance passage inside a main body part 16; and the state of the rolled sheet 12A is distinguished based on the results of a reading operation using a paper state analysis unit 92. That is, in case the changes in shape such as creases, a looseness or an undulation occurs in the rolled sheet 12A on account of a defective conveyance, the pattern reading part 90 cannot read the pattern 22 in a normal state, so that the pattern shown in the reading results by the pattern reading part 90 is distorted compared with the shape of an original pattern 22. Therefore, the sheet state analysis unit 92 can judge that the rolled sheet 12A is deformed. Consequently, the deformation of the rolled sheet 12A can be immediately detected and since the deformation of the rolled sheet can be detected as described, a defective printing can be prevented from occurring by an appropriate error correction process. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image inspection apparatus, and in particular, an image forming apparatus that forms an image while conveying a long image recording medium, and an image inspection apparatus that inspects an image formation result by the image forming apparatus. About.

  In an image forming apparatus such as a copying machine or a printer, a toner image is transferred onto a sheet or a fixing process is performed on the sheet while conveying the sheet as an image recording medium along a predetermined conveyance path. Print the image. There are two types of paper used in the image forming apparatus: roll paper that is long and wound in a roll, and cut paper that has been cut into a standard size in advance. Since roll paper can be smoothly conveyed, an image forming apparatus using roll paper is excellent in high speed and is advantageous when performing large-scale printing such as books. On the other hand, cut paper is superior to roll paper in terms of ease of handling of paper after printing.

  In this type of image forming apparatus, if the paper is deformed or poorly conveyed such as wrinkles, curls, unevenness (scratches), bending, sagging, waviness, skew (inclined with respect to the conveyance direction), Other than being detected by causing a paper jam, printing is performed as it is, resulting in defective printing. In the case of mass printing, it is difficult to find even if defective printing is mixed in the printing result. Also, when inspecting the print result of an image for calibration or the like, it is necessary to perform reading taking into consideration the state of the paper. Therefore, the image forming apparatus is required to automatically detect the state of the paper.

As a conventional technique for detecting the state of a sheet, there is a technique in which information about the sheet is printed on the sheet as invisible information in advance, and the invisible information is read at the time of printing (see Patent Document 1). Specifically, information such as paper weight, shape, setting direction, size, and expiration date is acquired from invisible information, and machine parameters for paper conveyance speed and processing (development processing, etc.) are set. .
JP 2003-140506 A

  However, in the prior art, the state of the paper obtained from the invisible information is a known state at the paper manufacturing stage or the like, and does not detect an unexpected paper state such as paper deformation or conveyance failure. In other words, it has been impossible to suppress the influence of deformation and conveyance failure on the paper.

  In particular, since roll paper is long, the surface of the paper is likely to be deformed such as wrinkles and irregularities due to conveyance failure, and roll paper is usually used for high-speed printing. If countermeasures are not taken immediately when a defect occurs, the number of defective prints will increase.

  Also, when inspecting the print result of an image, regardless of the type of roll paper / cut paper, if the paper has deformation or conveyance failure, accurate image reading cannot be performed, and Since distortion occurs, inspection accuracy is lowered.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus and an image inspection apparatus that can suppress the influence of deformation and conveyance failure of an image recording medium.

  In order to achieve the above object, the invention described in claim 1 is provided with a conveying means for conveying a long image recording medium, and an image for forming an image on the image recording medium conveyed by the conveying means. A pattern reading unit that reads a predetermined pattern that is recorded in advance on at least one surface of the image recording medium and that is invisible under visible light and visible under a specific wavelength light other than visible light; Based on the result of reading by the pattern reading means, the state determining means for determining whether or not the state of the image recording medium is normal, and the state determining means determines that the image recording medium is abnormal. In this case, an error processing means for performing predetermined error processing is provided.

  According to the first aspect of the present invention, at least one surface of the long image recording medium such as roll paper used in the image forming apparatus is invisible under visible light and has a specific wavelength other than visible light. A predetermined pattern that is visualized under light is recorded in advance. That is, since this pattern is invisible under visible light, it is not visually recognized by humans.

  In the image forming apparatus, the pattern reading unit reads this pattern from the image recording medium, and the state determination unit determines the state of the image recording medium based on the reading result by the pattern reading unit, and the image recording medium has an abnormality. Then, error processing is performed by error processing means. That is, when the long image recording medium is deformed or poorly conveyed, the pattern indicated by the reading result by the pattern reading unit is distorted unlike the original pattern shape. Error processing can be performed by detecting an abnormality. Thereby, it is possible to suppress the influence of deformation and conveyance failure on the image recording medium, that is, to prevent defective printing.

  According to a second aspect of the present invention, there is provided an image inspection apparatus that inspects an image formation result by an image forming apparatus, the image reading unit configured to read an image formed on the image recording medium by the image forming apparatus; Based on the result of image reading by the image reading means, the suitability determining means for determining the suitability of the image formed by the image forming apparatus; and under visible light recorded in advance on at least one surface of the image recording medium A pattern reading unit that reads a predetermined pattern that is invisible and visualized under a specific wavelength light other than visible light, and the image reading unit based on a pattern reading result by the pattern reading unit and before the determination by the suitability determining unit Correction means for correcting the image reading result so as to remove the geometric distortion included in the image reading result of the above.

  According to the invention described in claim 2, the predetermined pattern that is invisible under visible light and visualized under a specific wavelength light other than visible light on at least one surface of the image recording medium used in the image forming apparatus. Is recorded in advance. In the image inspection apparatus, the image formed on the image recording medium by the image forming apparatus is read by the image reading unit, and the pattern is also read from the image recording medium by the pattern reading unit. Then, prior to determining the suitability of the image based on the image reading result by the image reading means by the suitability judging means, the correction means removes geometric distortion from the image reading result based on the pattern reading result by the pattern reading means. Correct as follows. That is, when the image recording medium is deformed or poorly conveyed, the pattern indicated by the reading result by the pattern reading unit is the original pattern as well as the geometric distortion occurs in the image reading result by the image reading unit. Therefore, the state of the image recording medium can be detected from the pattern reading result by the pattern reading means, and the image reading result is geometrically corrected based on the pattern reading result. The geometric distortion included in the image reading result can be removed. Since the suitability of the image is determined after the correction, it is possible to suppress the influence of deformation and conveyance failure on the image recording medium, that is, to inspect the image formation result by the image forming apparatus with high accuracy.

  As described above, the present invention has an excellent effect that the influence of deformation of the image recording medium and conveyance failure can be suppressed.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
[Configuration of image forming apparatus]
FIG. 1 shows an image forming apparatus according to a first embodiment of the present invention. An image forming apparatus 10A shown in FIG. 1 performs printing on roll paper as a long image recording medium.

  The image forming apparatus 10A includes a roll paper supply unit 14 loaded with roll paper 12A, a main body unit 16 for printing an image on the roll paper 12A, and a roll winding unit that winds up the roll paper on which the image is printed. 18.

  The roll paper supply unit 14 feeds the roll paper 12 </ b> A wound in a roll shape and supplies it to the main body unit 16. As shown in FIG. 2, the roll paper 12A has a large number of feed holes 20 at both ends in the width direction at a constant pitch along the longitudinal direction (conveying direction). The roll paper 12A is transparent (invisible) under visible light, and transparent image forming materials (ink, toner, etc.) that are visiblely discolored by a specific wavelength light other than visible light such as ultraviolet rays. A predetermined grid pattern 22 (indicated by a dotted line in the figure) is printed in advance. That is, the pattern 22 printed with the transparent image forming material is not visible when visible light is formed, and even if it is printed on the entire surface, it is not visually recognized by humans.

  In general, the roll paper 12A may be white, and the pattern 22 may be printed with a white image forming material that is white under visible light and visiblely discolored by a specific wavelength light other than visible light. . Further, the pattern 22 is not limited to the lattice shape, and may be a pattern according to a predetermined rule such as a ladder pattern or a halftone dot.

  As shown in FIG. 1, the main body 16 is provided with a display unit 30 such as a liquid crystal display panel on the upper surface of the casing. The image forming unit 32, the fixing device 34, and the roll paper 12 </ b> A are conveyed inside the casing. As a conveying means for carrying out, a sheet conveying system including a plurality of conveying roller pairs 36, first and second tractors 38A and 38B, first and second scuff parts 40A and 40B, and the entire main body part 16 And a control unit 42 for controlling the operation.

  The paper transport system is driven by a paper transport system drive unit 44 (see FIG. 4). By driving the paper transport system, the roll paper 12A supplied from the roll paper feed unit 14 is guided to the image forming unit 32 and the fixing device 34 in this order in the main unit 16, and then discharged to the outside of the main unit 16. It is like that.

  Specifically, the roll paper 12 </ b> A supplied from the roll paper supply unit 14 to the main body unit 16 is first sent to the first tractor 38 </ b> A by the plurality of conveyance roller pairs 36.

  As shown in FIG. 3, the first tractor 38A is provided with two shafts 50, 50A parallel to the width direction of the roll paper and at a predetermined interval, and both ends of the two shafts 50, 50A. Endless belts 52 and 54 are respectively wound in the vicinity.

  Note that at least one of the endless belts, for example, the endless belt 54, can be moved in the width direction by a belt moving unit 56 (see FIG. 4). That is, the distance between the tractors 38A and 38B can be arbitrarily changed, and it is also possible to cope with a change in the size (dimension in the width direction) of the roll paper 12A supplied from the roll paper supply unit 14.

  On the outer peripheral surface of the endless belts 52 and 54, a number of projections 58 joined to the feed hole 20 are provided at the same pitch as the feed holes on the roll paper 12A along the longitudinal direction of the endless belt. Endless belts 52 and 54 are both rotated at a predetermined speed in the direction of arrow A by a pulley (not shown). That is, in the tractor 38, the rotation of the endless belts 52 and 54 causes the protrusions 58 of the endless belts 52 and 54 to sequentially enter the feed holes 20 provided at both ends in the width direction of the roll paper 12A, and the roll paper 12A is not fluttered. Can be transported. In the present embodiment, the roll paper 12A is conveyed with its printing surface (front surface) facing the endless belts 52 and 54.

  The image forming unit 32 is provided on the downstream side in the transport direction of the roll paper 12A by the first tractor 38A, and the roll paper 12A is sent to the image forming unit 32 by the first tractor 38A.

  The image forming unit 32 prints a desired image on the roll paper 12 </ b> A using an image forming material that is generally used conventionally, such as toner or ink that becomes visible under visible light. In this embodiment, as an example, an image forming unit 32 configured as follows is used.

  That is, the image forming unit 32 includes a cylindrical photosensitive member 60 that rotates at a constant speed in the direction of arrow B, and an optical scanning device 62 that outputs a light beam based on image data while scanning in the axial direction of the photosensitive member 60. ing. Further, around the photosensitive member 60, a charger 64, a developing unit 66, a transfer unit 68, a cleaner 70, a static elimination lamp (not shown), and the like are disposed.

  The surface of the photoreceptor 60 is uniformly charged by the charger 64. The charged photoconductor 60 is rotated in the direction of arrow B, so that a light beam based on image data is irradiated by the optical scanning device 62. As a result, an electrostatic latent image is formed on the photoreceptor 60. This electrostatic latent image is developed by the developing device 66. As a result, a toner image is formed on the photoreceptor 60.

  The roll paper 12A sent to the image forming unit 32 by the tractor 38 is sent between the photoconductor 60 and the transfer device 68, and after the toner image on the photoconductor 60 is transferred by the transfer device 68, the image forming unit. 32. The toner remaining on the surface of the photoconductor 60 after the transfer is removed by the cleaner 70 and discharged by the discharging lamp, and then charged by the charger 64 again for the next image formation.

  A second tractor 38B is arranged downstream of the roll paper 12A sent from the image forming unit 32 in the conveying direction. Since the second tractor 38B is the same as the first tractor 38A, detailed description thereof is omitted.

  The fixing device 34 is provided on the downstream side in the transport direction of the roll paper 12A by the second tractor 38B, and the roll paper 12A on which the toner image is transferred by the image forming unit 32 by the second tractor 38B is fixed to the fixing device 34. To be guided to. The fixing device 34 heats and pressurizes the roll paper 12A to perform a so-called fixing process, and fixes the image on the roll paper 12A.

  First and second scuff portions 40A and 40B are sequentially arranged on the downstream side of the fixing device 34 in the transport direction of the roll paper 12A. The first scuff portions 40A and 40B each have two rollers, a scuff flora 80 and a pinch roller 82, and the roll paper 12A is sandwiched between the two rollers and the scuff flora 80 is transported in the roll paper 12A. The tensile force in the conveyance direction is applied to the roll paper 12A. The roll paper 12A is transported in the transport direction by this pulling force.

  The roll paper 12A subjected to the fixing process by the fixing device 34 is conveyed while being slid by the first and second scuff parts 40A and 40B, and is discharged out of the main body part 16. The roll paper 12 </ b> A discharged to the outside of the main body portion 16 is wound up in a roll shape by the roll winding portion 18.

  Here, in the image forming apparatus 10 </ b> A according to the present embodiment, as shown in FIG. 1, pattern reading as a pattern reading unit that reads the pattern 22 from the roll paper 12 </ b> A along the roll paper conveyance path in the main body 16. A plurality of portions 90 are arranged.

  In this embodiment, as an example, the pattern reading unit 90 reads the pattern 22 for one line in the width direction of the roll paper 12A in one reading, and the reading result is used as an image signal (analog). When the roll paper 12A is conveyed, the reading position on the roll paper 12A moves, and the pattern 22 can be read two-dimensionally. Such a pattern reading unit 90 includes, for example, a light source that outputs light of a specific wavelength other than visible light that causes the pattern 22 to be discolored, and a CCD that detects reflected light from roll paper of light output from the light source. One-dimensionally arranged line sensors and an imaging optical system that forms an image on the light receiving surface of the sensor of reflected light from the reading area on the roll paper 12A of the light output from the light source can be configured.

  In the present embodiment, as an example, three pattern reading units 90A to 90C are arranged along the conveyance path of the roll paper 12A. Specifically, the first pattern reading unit 90A is provided in the vicinity of the first tractor 38A and so as to face the back surface of the roll paper 12A being conveyed by the first tractor 38A. The pattern 22 is read from the roll paper 12A being conveyed by the tractor 38A. The second pattern reading unit 90B is provided so as to face the surface of the roll paper 12A that is being conveyed between the second tractor 38B and the fixing device 34. From the roll paper 12A before the fixing device 34, the second pattern reading unit 90B is provided. The pattern 22 is read. The third pattern reading unit 90C is provided so as to face the surface of the roll paper 12A being conveyed between the fixing device 34 and the first scuff unit 40A, and in front of the first scuff unit 40A. The pattern 22 is read from the roll paper 12A.

  The arrangement position and the number of pattern reading units 90 are not limited to the above.

  In the present embodiment, since the pattern 22 is printed on both the front and back surfaces of the roll paper 12A, as described above, the pattern reading unit 90 includes a mixture of the one facing the front surface of the roll paper 12A and the one facing the back surface. However, the pattern 22 that the pattern reading unit 90 reads the pattern may be printed on only one of the front and back surfaces. The pattern reading unit 90 has the surface on which the pattern 22 of the roll paper 12A is printed. May be provided so as to face each other.

  Further, the main body unit 16 includes a paper state analysis unit 92, and outputs of the first to third pattern reading units 90A to 90C are connected to the paper state analysis unit 92 via A / D converters (not shown). Has been. An image signal indicating the result of reading the pattern 22 by the first to third pattern reading units 90 </ b> A to 90 </ b> C is digitally converted and input to the paper state analysis unit 92 as image data. The sheet state analysis unit 92 functions as a state determination unit of the present invention, analyzes input image data, and reads the reading position (specifically, the first tractor in each pattern reading unit 90). It is determined whether or not the state of the roll paper 12A at 38A, three positions before the fixing device 34 and three positions before the fixing device 34 is normal.

  As shown in FIG. 4, the display unit 30, the paper transport system driving unit 44, the image forming unit 32, the belt moving unit 56, and the paper state analysis unit 92 are connected to the control unit 42. The control unit 42 sends control signals to these units to control the overall operation of the image forming apparatus 10A. In the present embodiment, the control unit 42 also functions as error processing means of the present invention.

[Operation of image forming apparatus]
Next, the operation of the image forming apparatus 10A according to the first embodiment will be described.

  In the image forming apparatus 10 </ b> A, when roll paper is loaded into the roll paper supply unit 14, the roll paper is automatically fed out from the roll paper supply unit 14 and supplied to the main body unit 16. The main body 16 operates as follows under the control of the control unit 42.

  That is, in the main body unit 16, the belt moving unit 56 is driven to move the position of the endless belt 54 in the width direction, and the distance between the endless belts 52 and 54 depends on the paper width of the newly loaded roll paper 12A. And the paper transport system drive unit 44 is driven to transport the roll paper 12A in the paper transport system until the leading edge of the roll paper 12A reaches a predetermined position (for example, discharged outside the main body unit 16). Keep it. As a result, automatic paper feeding (auto loading) is performed on the main body 16.

  Thereafter, when printing is started, the paper transport system drive unit 44 is driven, and the transport of the roll paper 12A by the paper transport system is started. As a result, the roll paper 12A is guided from the conveying roller pair 36 to the first tractor 38A and is sent out to the image forming unit 32 by the first tractor 38A. In the image forming unit 32, a desired image (toner image) is printed on the roll paper 12A. The roll paper 12A on which the image has been printed is then sent to the fixing device 34 by the second tractor 38B, and after the fixing process is performed, the roll paper 12A is removed from the main body 16 by the first and second scuff parts 40A and 40B. And is taken up by the roll take-up unit 18.

  Further, in the image forming apparatus 10A, the state of the roll paper 12A in the main body portion 16 is monitored at three places, before being sent to the first tractor 38A and the fixing device 34, and before being sent to the first scuff portion 40A. ing. For this purpose, the main body 16 performs the monitoring process shown in FIG.

  That is, as shown in FIG. 5, in the main body unit 16, the first to third pattern reading units 90 </ b> C are transported to the fixing device 34 while the first tractor 38 </ b> A is being conveyed in step 100. A pattern 22 pre-printed with an invisible image forming material on the roll paper 12A is read from the roll paper 12A at each position before being fed into the scuff unit 40A.

  In the next step 102, the paper state analysis unit 92 analyzes the reading results by the first to third pattern reading units 90C, and in the next step 104, the roll paper 12A is in a normal state at each position. It is determined whether or not. Specifically, in the case of the lattice-like pattern 22, if the pattern 22 is normally read without distortion, that is, if the read pattern 22 shows a predetermined lattice-like shape, the corresponding reading position What is necessary is just to discriminate | determine that the roll paper 12A is a normal state.

  Then, roll paper is fed at all positions before being fed into the fixing device 34 and before being fed into the first scuff unit 40A during conveyance of the first tractor 38A by the first to third pattern reading units 90A to 90C. If the pattern 22 is normally read from 12A, it is determined that the roll paper is in a normal state at all positions, an affirmative determination is made in step 104, and the process proceeds to step 110 described later.

  On the other hand, during conveyance of the first tractor 38A, the pattern 22 cannot be normally read from the roll paper 12A at any one position before being sent to the fixing device 34 or before being sent to the first scuff unit 40A. If the pattern 22 has not been read normally, the roll paper 12A has been deformed at the position, and a negative determination is made in step 104, and the process proceeds to step 106. In step 106, error processing is appropriately performed under the control of the control unit 42. When the abnormal state is resolved by the error processing and the normal state is obtained, the process proceeds from the next step 108 to step 110.

  In step 110, if the main body 16 is being driven, a negative determination is made and the process returns to step 100. If the main body 16 is stopped by turning off the power of the image forming apparatus 10A, an affirmative determination is made in step 110. Then, the process of FIG.

  Next, the state of the roll paper 12A at each position before being sent to the fixing device 34 and before being sent to the first scuff unit 40A during conveyance of the first tractor 38A will be described.

  First, the state of the roll paper 12A being conveyed by the first tractor 38A is as follows if the distance between the endless belts 52 and 54 is appropriate for the width of the roll paper 12A as shown in FIG. Since the surface of the roll paper 12A conveyed by one tractor 38A is flat, the first pattern reading unit 90A can normally read the pattern 22 from the roll paper 12A.

  On the other hand, as shown in FIG. 6B, when the distance between the endless belts 52 and 54 is narrower than the width dimension of the roll paper 12A, the roll paper 12A conveyed by the first tractor 38A. Wrinkles (portions surrounded by dotted lines) in the transport direction. Therefore, when the pattern 22 is read from the roll paper 12A by the first pattern reading unit 90A, the pattern indicated by the reading result is distorted unlike the original pattern 22 shape. That is, the first pattern reading unit 90A cannot read the pattern 22 normally.

  In this case, since the roll paper being conveyed by the first tractor 38A is deformed, a negative determination is made in step 104 in FIG. 5 described above. Therefore, in step 106, the position of the endless belt 54 is set in the width direction as error processing. Move outward. If the distance between the endless belts 52 and 54 becomes appropriate to the width of the roll paper 12A due to this movement, the state shown in FIG. 6A is obtained, so that the abnormal state is resolved in step 108 in FIG. It is determined that

  Further, as shown in FIG. 7A, the state of the roll paper 12A in front of the fixing device 34 is the roll in the position in front of the fixing device 34 as long as the roll paper 12A is normally fed to the fixing device 34. Since the surface of the paper 12A is flat, the second pattern reading unit 90B can normally read the pattern 22 from the roll paper 12A.

  During automatic paper feeding, as shown in FIG. 7B, a paper jam is likely to occur near the paper entrance of the fixing device 34, and if such a paper jam occurs near the paper entrance of the fixing device 34, Sag occurs on the roll paper 12A in front (portion surrounded by a dotted line). Therefore, when the pattern 22 is read from the roll paper 12A by the second pattern reading unit 90B, the pattern indicated by the reading result is distorted unlike the original pattern 22 shape. That is, the second pattern reading unit 90B cannot read the pattern 22 normally.

  In this case, since the roll paper is deformed in front of the fixing device 34, a negative determination is made in step 104 of FIG. 5 described above. Therefore, in step 106, as an error process, for example, the display unit 30 clears a paper jam. Display a message to encourage work. When the paper jam is eliminated by the operator's work and the state shown in FIG. 7A is obtained, it is determined in step 108 in FIG. 5 that the abnormal state is eliminated and the normal state is obtained.

  In addition, as shown in FIG. 8A, the state of the roll paper 12A in front of the first scuff part 40A is as follows as long as the roll paper 12A is normally pulled by the scuff flora 80 of the first scuff part 40A. Since the surface of the roll paper 12A at a position before the scuff portion 40A is flat, the third pattern reading unit 90C can read the pattern 22 from the roll paper 12A normally.

  In the scuff roller 80, depending on the type of roll paper 12A used, a substance applied to the surface of the paper may adhere to the scuff roller 80, causing so-called scuff slip, and the paper may not be transported normally. That is, as shown in FIG. 8B, when such scuff slip occurs, the first scuff portion 40A cannot give a sufficient pulling force in the transport direction to the roll paper 12A. Waviness (portion surrounded by a dotted line) occurs in the roll paper 12A before the first scuff portion 40A. Therefore, when the pattern 22 is read from the roll paper 12A by the third pattern reading unit 90C, the pattern indicated by the read result is distorted unlike the original pattern 22 shape. That is, the third pattern reading unit 90C cannot read the pattern 22 normally.

  In this case, since the roll paper is deformed in front of the fixing device 34, a negative determination is made in step 104 of FIG. 5 described above. Therefore, in step 106, as an error process, for example, pressurization to the roll paper 12A of scuff flora To improve the scuffing. As a result, a sufficient pulling force in the conveying direction is applied to the roll paper 12A and the state shown in FIG. 8A is obtained. In step 108 in FIG. 5, it is determined that the abnormal state is resolved and the normal state is obtained. .

[Summary]
As described above, in the image forming apparatus 10 </ b> A according to the first embodiment, the roll paper 12 </ b> A on which the predetermined pattern 22 is printed in advance by the invisible image forming material is used, and the image forming apparatus 10 </ b> A is at a predetermined position on the conveyance path in the main body unit 16. The pattern reading unit 90 reads the pattern 22 from the roll paper 12A, and the paper state analysis unit 92 determines the state of the roll paper 12A based on the read result.

  That is, when the roll paper 12A is deformed such as wrinkles, sagging or undulation due to a conveyance failure, the pattern reading unit 90 cannot read the normal pattern 22, and the pattern reading unit 90 reads it. Since the pattern indicated by the result is in a distorted state from the original shape of the pattern 22, the paper state analysis unit 92 can determine that the roll paper 12A is deformed. Thereby, the deformation of the roll paper 12A can be detected immediately. Since the roll paper deformation can be detected in this way, it is possible to prevent defective printing by performing appropriate error processing. In other words, early detection and early resolution of conveyance failure can be achieved.

  In the above description, the case where wrinkles, sagging, and undulation are detected as deformation of the roll paper 12A has been specifically described. However, the present invention is not limited to this. Similarly, when the surface of the roll paper 12A has irregularities (scratches) or folds, the pattern reading unit 90 cannot read the normal pattern 22 from the roll paper 12A, and is thus detected as a deformation of the roll paper 12A. I can do it. In this case, if the image is printed by skipping a predetermined unit region (for example, a page) including a portion with irregularities or folds on the roll paper 12A, and printing is not performed on the portions with irregularities or folds, Defective printing can be prevented.

  Moreover, although the case where the pattern reading part 90 was provided in the main-body part 16 was demonstrated above, this invention is not limited to this. As shown by a dotted line in FIG. 1, a pattern reading unit 90D is provided in the roll paper supply unit 14, and the pattern 22 is read from the roll paper 12A fed out from the roll paper supply unit 14 by the pattern reading unit 90D. You may make it detect a state.

<Second Embodiment>
[Configuration of image forming apparatus]
FIG. 9 shows an image forming apparatus according to the second embodiment of the present invention. An image forming apparatus 10B illustrated in FIG. 9 performs printing on a cut sheet. In FIG. 9, members having the same functions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted below.

  The image forming apparatus 10B is provided with a display unit 30 such as a liquid crystal display panel on the upper surface, and prints a desired image on the sheet feeding tray 200 loaded with the cut sheet 12B and the cut sheet 12B. Image forming section 32, fixing device 34 for fixing the image printed on cut paper 12B, paper transport system including a plurality of transport roller pairs 36 for transporting cut paper 12B, and the printing apparatus A control unit 42 that controls the entire operation is provided.

  Cut sheets 12B cut to a predetermined size are stacked on the sheet feed tray 200. As shown in FIG. 10, the cut paper 12B has a lattice pattern on both the front and back surfaces thereof by a transparent image forming material (such as ink or toner) that is transparent under visible light and is discolored by a specific wavelength light other than visible light. A pattern 22 (indicated by a dotted line in the figure) is printed in advance. In general, the cut paper 12B may be printed using a white image forming material that is white under visible light and is visiblely discolored by light having a specific wavelength other than visible light. . The pattern 22 to be printed is not limited to a lattice pattern, and may be a predetermined two-dimensional pattern such as a ladder pattern or a halftone dot.

  From the paper feed tray 200, the stacked cut sheets 12B are fed out one by one. As such a sheet feeding tray 200, for example, a sheet that takes out one sheet by a feed belt from the uppermost part of the stacked sheet bundle can be used.

  The cut paper 12B taken out from the paper feed tray 200 is transported along a predetermined transport path L by a paper transport system, and is first guided to the image forming unit 32 and the fixing device 34 in this order. The As a result, an image is printed on the cut sheet 12B in the image forming unit 32, and a fixing process is performed on the cut sheet 12B in the fixing device 34, and the printed image is fixed on the cut sheet 12B.

  The transport path L is branched downstream of the fixing device 34 in the paper transport direction, and a reversing device 202 is provided on one side of the branch. The reversing device 202 employs a conventionally known inverter system, and reverses the front and back of the cut paper 12B by returning and transporting the cut paper 12B to return it to the image forming unit 32. That is, in the image forming apparatus 10B, after forming an image on the surface of the cut paper 12B, the reversing device 202 reverses the front and back of the cut paper 12B as necessary to form an image on the back surface of the cut paper 12B. Can be printed (double-sided printing is possible). Instead of the inverter system, it is also possible to provide an intermediate tray and invert the cut sheet 12B.

  In addition, on the other side of the conveyance path L branched on the downstream side in the sheet conveyance direction from the fixing device 34, the discharge of the cut sheet 12B on which the image is formed is discharged, and the discharge to the discharge tray 204 is stopped. A purge tray 206 from which the cut sheet 12B is discharged and an image inspection device 208 for inspecting the print result of the image are sequentially provided, and the cut sheet 12B is conveyed to any one of these.

  More specifically, the cut sheet 12B on which a desired image is printed by the image forming unit 32 and subjected to the fixing process by the fixing device 34 is discharged to the discharge tray 204 and stacked. On the other hand, on the purge tray 206, some trouble occurs during conveyance, and appropriate image forming processing cannot be performed, and unnecessary cut sheets 12B are discharged and stacked. Further, the cut sheet 12B on which a predetermined test image is printed is sent to the image inspection apparatus 208 for calibration.

  The image inspection apparatus 208 is shielded by a casing 208A so that external light does not enter, and a discharge tray 210 for discharging the cut sheet 12B after inspection is provided outside the casing 208A. In the image inspection apparatus 208, the cut sheet 12 </ b> B that has been fed is transported along the transport path L in the casing 208 </ b> A by the paper transport system and is discharged to the discharge tray 210.

  Further, the image inspection apparatus 208 has an image reading unit 212 as an image reading unit for reading an image printed on the cut paper 12B in the casing 208A, and a pattern reading unit for reading the pattern 22 printed in advance on the cut paper 12B. As a pattern reading unit 214, and a finish determination unit 216 for determining the finish state of the printed image.

  The image reading unit 212 is provided to face the surface of the cut sheet 12B conveyed along the conveyance path L, and reads an image from the cut sheet 12B under visible light. In this embodiment, as an example, as shown in FIG. 11, the image reading unit 212 reads an image for one line in the width direction of the cut sheet 12B by one reading, and shows the read image. An image signal is output, and when the cut sheet 12B is conveyed, the image reading position on the cut sheet 12B is moved by the image reading unit 212, whereby the entire surface of the cut sheet 12B can be read. It has become.

  A conventionally known CCD camera can be used for such an image reading unit 212. Specifically, for example, a light source that outputs white light, a line sensor in which CCDs that detect reflected light from roll paper of light output from the light source are arranged in a line in the width direction of the cut paper 12B, and a light source And an imaging optical system that forms an image of reflected light from the reading region on the cut sheet 12B on the light receiving surface of the sensor. If the image forming apparatus 10B can print a color image, a so-called three-line sensor provided with a line sensor for each of RGB colors may be used.

  The pattern reading unit 214 can be the same as the pattern reading unit 90 in the first embodiment. The pattern reading unit 214 is provided in the vicinity of the image reading unit 212 so that a pattern at substantially the same position as the reading position of the image reading unit 212 can be read. Thereby, the image reading unit 212 and the pattern reading unit 214 can read an image and a pattern at substantially the same position on the cut sheet 12B substantially simultaneously.

  Specifically, in the present embodiment, the cut sheet 12B on which the pattern 22 is printed on both the front and back sides is used, so that the pattern reading unit 214 moves to the transport path L by the paper transport system as shown in FIG. It may be provided adjacent to the image reading unit 212 so as to face the front surface of the cut paper 12B being conveyed along, or so as to face the back surface of the cut paper 12B as shown in FIG. Further, the image reading unit 212 may be provided so as to face the conveyance path L. When using the cut paper 12B on which the pattern 22 is printed only on one of the front and back surfaces, the pattern reading unit 214 may be provided so as to face the printing surface on which the pattern 22 is printed.

  Further, the image reading unit 212 and the pattern reading unit 214 can be integrally shaped. For example, if a line sensor that detects light of a specific wavelength is provided in line with the line sensor of the image reading unit 212 and a light source that can output light including specific wavelength light is used, the image reading unit 212 and the pattern reading unit 214 are integrated. Is possible.

  The outputs of the image reading unit 212 and the pattern reading unit 214 are connected to a finish determination unit 216 via an A / D converter (not shown). In the finish determination unit 216, image signals indicating the reading results of the image reading unit 212 and the pattern reading unit 214 are digitally converted and input as image data (see FIGS. 12 and 13).

  As shown in FIG. 13, the finish determination unit 216 includes a comparison / collation unit 216A that functions as the suitability determination unit of the present invention, and a function correction unit 216B as the correction unit of the present invention.

  The comparison / collation unit 216A uses image data (hereinafter referred to as image reading data) obtained as a result of reading by the image reading unit 212 indicating an actually printed image. Image data), and the final state of the printed image, that is, the suitability of the printed image is determined.

  In the image reading data obtained by reading by the image reading unit 212, the cut paper 12B is skewed or curled at the time of image reading by the image reading unit 212. If so, geometric distortion has occurred. The correction unit 216B grasps the geometric distortion state based on the image data (hereinafter referred to as pattern reading data) read by the pattern reading unit 90, and corrects the distortion so as to remove the distortion from the image reading data. Is.

  Further, the image forming apparatus 10B is provided with a pattern reading unit 90E at a predetermined position on the transport path L from the paper feed tray 200 to the discharge tray 204, as in the first embodiment, and is also used for paper state analysis. A unit 92 is also provided. That is, the image forming apparatus 10B can detect the deformation of the cut sheet 12B.

  In this embodiment, as an example, the pattern reading unit 90E is provided in the vicinity of the feeding portion of the cut paper 12B of the paper feed tray 200 so as to face the uppermost cut paper 12B stacked on the paper feed tray 200. Yes. When the cut paper 12B is fed out from the paper feed tray 200, the pattern reading unit 90E reads the pattern 22 from the fed cut paper 12B. If the cut paper 12B is deformed, the deformation can be detected. It has become. In this case, deformation of the cut sheet 12B to be detected is mainly deformation due to unevenness or flaws.

  As shown in FIG. 13, the control unit 42 is connected to the image forming unit 32, the fixing device 34, the paper state analysis unit 92, the image inspection device 208, and the paper transport system drive unit 44 that drives the paper transport system. ing. The control unit 42 sends control signals to these units to control the overall operation of the image forming apparatus 10B.

[Operation of image forming apparatus]
Next, the operation of the image forming apparatus 10B according to the second embodiment will be described.

  The image forming apparatus 10B operates as follows under the control of the control unit 42. That is, when a print instruction is input, the image forming apparatus 10B drives the paper transport system drive unit 44 to feed out the cut sheets 12B one by one from the paper feed tray 200. At the time of this feeding, the pattern reading is performed. The pattern 22 is read from the cut sheet 12B by the unit 90E. Then, based on the read result, the paper state analysis unit 92 determines whether or not the cut paper 12B fed out from the paper feed tray 200 is deformed.

  If there is no deformation, the cut paper 12B fed out from the paper feed tray 200 is transported along the transport path L and first sent to the image forming unit 32, and a desired image (toner image) is transferred to the cut paper 12B. Printed on. The cut paper 12B on which the image is printed is then sent to the fixing device 34 and subjected to fixing processing. The cut sheet 12B after the fixing process is discharged as it is to the discharge tray 204 in the case of single-sided printing, and is sent to the reversing device 202 in the case of double-sided printing, and is reversed and then returned to the image forming unit 32 again. Then, an image is printed on the back surface, and after fixing processing is performed by the fixing device 34, the image is discharged to the discharge tray 204.

  When the cut paper 12B fed out from the paper feed tray 200 is deformed, that is, the cut paper 12B in which the deformation is detected is transported along the transport path L and sent to the image forming unit 32, but printing is performed. Is output without being performed, and then discharged to the purge tray 206 via the fixing device 34. In this embodiment, the image forming apparatus 10B including the purge tray 206 has been described as an example. However, in the case of an image forming apparatus that does not include the purge tray 206, printing is stopped and an error message is displayed on the display unit 30. For example, the user may be notified of the abnormality of the cut sheet 12B.

  In the calibration, the image forming apparatus 10B prints a predetermined test image on the cut paper 12B after feeding the cut paper 12B fed from the paper feed tray 200 to the image forming unit 32 in the same manner as described above. After fixing the cut sheet 12B, the cut sheet 12B is conveyed to the image inspection apparatus 208. Then, the image inspection apparatus 208 performs the process shown in FIG. In the image inspection apparatus 208, the cut sheet 12 </ b> B is transported at a constant speed along the transport path L and discharged to the discharge tray 210.

  In the image inspection apparatus 208, as shown in FIG. 14, the image printed on the cut paper 12B is read by the image reading unit 212 in step 300 from the cut paper 12B conveyed in the image inspection apparatus 208. In 302, the pattern reading unit 214 reads the pattern 22 previously printed on the cut paper 12B, and returns to step 300 from the next step 304 until the reading of one page is completed, and the reading of the image and the pattern 22 is repeated. . As a result, the image reading data read by the image reading unit 212 for one page and the pattern reading data read by the pattern reading unit 214 are obtained and stored in a page memory (not shown).

  When reading of one page is completed, the process proceeds from step 304 to step 306, and the finish determination unit 216 analyzes the pattern reading data obtained by reading by the pattern reading unit 214 to determine the state of the cut sheet 12B. If so, the process proceeds from the next step 308 to step 312 as it is, and the image reading data obtained by reading by the image reading unit 212 is compared with the image data representing the image to be printed to determine the finished state. 14 is terminated.

  On the other hand, when the cut paper 12B has a conveyance failure or deformation, the process proceeds from step 308 to step 310, and the distortion state of the pattern 22 is obtained based on the pattern reading data obtained by reading by the pattern reading unit 214. In accordance with this distortion state, geometric correction is performed on the image reading data obtained by reading by the image reading unit 212.

  For example, if the pattern reading unit 214 is provided so as to face the surface (printing surface) of the cut sheet 12B being conveyed, the distortion state of the pattern 22 in the pattern reading data is approximated by a function, Image reading data is converted (for example, affine transformation) by an inverse function of the approximate function. Thereby, the distortion caused by the conveyance failure or deformation of the cut sheet 12B can be removed from the image reading data obtained by reading by the image reading unit 212.

  After this correction, the process proceeds to step 312 where the corrected image read data is compared with image data representing the image to be printed to determine the finished state, and the processing in FIG. 14 is terminated.

  The inspection result by the image inspection apparatus 208 described above, that is, the comparison / collation result in step 312 is sent to the control unit 42. The control unit 42 reflects this comparison / collation result on machine control parameters (for example, the exposure amount when the image forming unit 32 writes an image on the photoconductor 60).

  Next, the state of the cut sheet 12B in the image inspection apparatus 208 will be specifically described. FIG. 15 shows an example of the state of the cut sheet 12B being conveyed in the image inspection apparatus 208. In FIG. 15, the pattern 22 previously printed on the cut sheet 12B has a lattice shape (indicated by a dotted line in FIG. 15), and a triangular image is printed by the image forming apparatus 10B.

FIG. 15A shows a case where the cut sheet 12B is normally conveyed. in this case,
The pattern 22 read by the pattern reading unit 214 shows a predetermined lattice shape. That is, since the pattern reading unit 214 can normally read the pattern 22 from the cut sheet 12B, it is determined in step 308 in FIG.

  On the other hand, as shown in FIG. 15B, when the cut sheet 12B is inclined with respect to the conveyance direction, the pattern reading unit 214 is distorted (inclined with respect to the conveyance direction). The pattern 22 is read. That is, since the pattern reading unit 214 cannot normally read the pattern 22 from the cut sheet 12B, it is determined in step 308 of FIG. 14 that there is a conveyance failure or deformation. In this case, the inclination of the cut sheet 12B can be obtained by obtaining the distortion (tilt) state of the pattern 22 from the original state based on the inclination of each line constituting the lattice-like pattern 22 in the pattern read data. In the next step 310, geometric correction may be applied to the image read data obtained by reading by the image reading unit 212 so as to rotate by this inclination.

  As shown in FIG. 15C, when the cut sheet 12B is curled, the pattern reading unit 214 also reads the distorted pattern 22. That is, since the pattern reading unit 214 cannot normally read the pattern 22 from the cut sheet 12B, it is determined in step 308 of FIG. 14 that there is a conveyance failure or deformation. In this case, the distortion state of the pattern 22 from the original state can be obtained from the shape of each line constituting the grid pattern 22 in the pattern reading data, the position of the grid point, and the like. The image read data obtained by reading by the image reading unit 212 may be subjected to geometric correction so as to perform conversion for removing distortion.

  In the image forming apparatus 10 </ b> B, the cut sheet 12 </ b> B having unevenness (scratches) and folds is detected when the cut paper 12 </ b> B is fed out from the paper feed tray 200 and is discharged to the purge tray 206. In some cases, such deformation may occur after unwinding. In this case, as shown in FIG. 15D, the deformed cut sheet 12B is conveyed to the image inspection apparatus 208, and the pattern 22 on the cut sheet 12B is also distorted along with the deformation. The pattern reading unit 214 reads the distorted pattern 22. That is, since the pattern reading unit 214 cannot normally read the pattern 22 from the cut sheet 12B, it is determined in step 308 in FIG. 14 that there is a conveyance failure or deformation. Also in this case, the distortion state of the pattern 22 from the original state can be obtained from the shape of each line constituting the grid pattern 22 in the pattern read data, the position of the grid point, and the like, and FIG. As in the case of, in the next step 310, the image reading data obtained by reading by the image reading unit 212 may be subjected to geometric correction so as to perform conversion for removing this distortion. Further, in this case, the amount of distortion may locally increase, and the portion with the large amount of distortion may be excluded from the inspection (comparison / collation) region.

[Summary]
As described above, in the image forming apparatus 10B according to the second embodiment, the cut paper 12B on which the predetermined pattern 22 is printed in advance using the invisible image forming material is used, and the cut paper 12B is printed by the image forming apparatus 10B. When the image inspection apparatus 208 inspects the finished state of the image, the image reading unit 212 reads an image printed by the image forming apparatus 10B from the cut paper 12B, and the pattern reading unit 214 also reads the pattern 22 from the cut paper 12B. Based on the reading result of this pattern 22, the finish determination unit 216 determines the state of the cut sheet 12 </ b> B.

  That is, when the cut sheet 12B has conveyance failure or deformation, the pattern reading unit 214 cannot read the normal pattern 22, and the pattern indicated by the pattern reading unit 214 is the original pattern. Since the shape is distorted, the finish determination unit 216 can determine that the cut paper 12B is poorly conveyed or deformed. Then, the image reading result by the image reading unit 212 is geometrically corrected in accordance with the distortion state of the pattern indicated by the reading result by the pattern reading unit 214, and then the finished state of the image is determined. As a result, it is possible to remove the distortion caused by the conveyance failure or deformation in the cut paper 12B included in the image reading result, and even if the conveyance failure or deformation occurs in the cut paper 12B, the finished image is accurately inspected. can do.

  In the second embodiment, the example in which the present invention is applied to the image forming apparatus 10B that prints on the cut paper 12B has been described. However, the image forming apparatus that prints on the roll paper 12A as in the first embodiment. The present invention is also applicable to 10A.

1 is a diagram illustrating a configuration of an image forming apparatus according to a first embodiment. It is a figure which shows the roll paper used with the image forming apparatus which concerns on 1st Embodiment. It is a perspective view of a tractor. 1 is a diagram illustrating a configuration of an electrical system of an image forming apparatus according to a first embodiment. 3 is a flowchart illustrating a monitoring process performed by the image forming apparatus according to the first embodiment. It is a figure which shows the state of roll paper when the distance between the endless belts in a 1st tractor is suitable for the width dimension of roll paper (A), and when it is narrow (B). FIG. 6 is a diagram illustrating a roll paper state when the roll paper is normally fed into the fixing device (A) and when a paper jam occurs (B). It is a figure which shows the state of the roll paper when the roll paper is normally conveyed by the scuff part (A) and when the scuff slip is caused (B). It is a figure which shows the structure of the image forming apparatus which concerns on 2nd Embodiment. It is a figure which shows the cut paper used with the image forming apparatus which concerns on 2nd Embodiment. It is a perspective view of an image reading part. (A), (B) is a figure which shows the example of arrangement | positioning of the image reading part and pattern reading part in an image inspection apparatus. FIG. 6 is a diagram illustrating a configuration of an electrical system of an image forming apparatus according to a second embodiment. It is a flowchart which shows the process performed with an image inspection apparatus. (A)-(D) are top views which show the example of a state of the cut sheet currently conveyed in the inside of an image inspection apparatus.

Explanation of symbols

10A, 10B Image forming apparatus 12A Roll paper 12B Cut paper 14 Roll paper feeding part 16 Main body part 18 Roll winding part 20 Feed hole 22 Pattern 32 Image forming part 34 Fixing device 38A, 38B Tractor 40A, 40B Scuff part 42 Control unit 52 , 54 endless belt 80 scuff roller 82 pinch rollers 90A to D pattern reading unit 92 paper state analysis unit 208 image inspection device 212 image reading unit 214 pattern reading unit 216 finish determination unit

Claims (2)

An image forming apparatus that includes a transport unit that transports a long image recording medium, and forms an image on the image recording medium transported by the transport unit,
Pattern reading means for reading a predetermined pattern that is recorded in advance on at least one surface of the image recording medium and that is invisible under visible light and visible under a specific wavelength light other than visible light;
State determining means for determining whether or not the state of the image recording medium is normal based on a reading result by the pattern reading means;
An error processing means for performing a predetermined error processing when the state determination means determines that the image recording medium is abnormal;
An image forming apparatus comprising: An image inspection apparatus for inspecting an image formation result by an image forming apparatus,
Image reading means for reading an image formed on the image recording medium by the image forming apparatus;
Suitability determination means for determining suitability of an image formed by the image forming apparatus based on an image read result by the image reading means;
Pattern reading means for reading a predetermined pattern that is recorded in advance on at least one surface of the image recording medium and that is invisible under visible light and visible under a specific wavelength light other than visible light;
Correction means for correcting the image reading result based on the pattern reading result by the pattern reading means to remove geometric distortion included in the image reading result by the image reading means before the determination by the suitability determining means. When,
An image inspection apparatus characterized by that.

Images