JP2009298013A - Image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct the print position of an image accurately as compared with a case where the image data of several pages is handled as the image data of one page when an image is formed using an image formation device of friction conveyor system by conveying a perforated continuous sheet of paper. <P>SOLUTION: The image formation device 10 includes image formation means 11-14 for printing an image on a continuous sheet of paper 15 which is conveyed as a drive roll 21 rotates, a sensor 24 which detects perforations when a continuous sheet of paper is perforated, a means for setting a perforation which is the detection object of the sensor 24 and a reference time at which the perforation must be detected for each page on which image data is printed, and a means for correcting the conveyance speed of the continuous sheet of paper according to the time difference between the reference time which is set by the setting means and the time when a perforation detection means detects the perforation of detection object for each print page. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  The belt-like continuous paper used for image formation includes continuous paper in which feed holes are provided at regular intervals in the paper length direction and continuous paper (pinless paper) in which no feed holes are provided. Also, some image forming apparatuses that handle continuous paper form an image by transporting continuous paper that is not provided with a feed hole (see, for example, Patent Document 1). When this type of image forming apparatus is used to transport continuous paper with feed holes to form an image, the position of the feed holes is recognized using an optical sensor or the like, and Is set to the top (boundary) of a page (page), and an image is formed on a continuous sheet in page units.

  The length per page of image information (image data) (hereinafter also referred to as “page length”) applied when printing an image on continuous paper varies depending on the size of image data, printing conditions, and the like. Therefore, when the relationship between the spacing between the feed holes and the page length is an integer ratio (the page length is an integer multiple of the feed holes), the feed hole and the printed page (the page on which image data for one page is printed) The positional relationship is constant. Therefore, in that case, for any print page, the image is printed on continuous paper by setting the space between the holes as the head of the page.

  On the other hand, when the relationship between the spacing between the feed holes and the page length is not an integer ratio, the positional relationship between the feed holes and the printed pages changes in units of pages. For this reason, for example, when the spacing between the feed holes is 1/2 inch and the page length is 12 inches + 1/6 inch, the relationship between the spacing between the feed holes and the page length is virtually an integer ratio relationship. As described above, by handling the image data for three pages as the image data for one page, the page length of printing is set to 36 inches + 1/2 inch to print an image on continuous paper. In this case, the print page length is three times the page length of the image data.

JP 2006-82430 A

  In general, when forming an image by transporting continuous paper with feed holes using an image forming apparatus capable of transporting continuous paper without feed holes, the length direction of the continuous paper (paper transport) In the direction), the hole position of the feed hole is detected at a cycle according to the page length of the image data, and the print position of the image is corrected based on the detected hole position. For this reason, when the relationship between the spacing between the feed holes and the page length of the image data is not an integer ratio, the hole position of the feed holes cannot be detected at a cycle corresponding to the page length of the image data. Therefore, as described above, when image data for a plurality of pages is handled as image data for one page, the hole position of the feed hole is detected for each of the plurality of pages, and an image is printed based on the detected hole position. The position will be corrected. For this reason, the correction accuracy is lower than when the print position of the image is corrected for each page.

  The present invention provides image information for a plurality of pages when an image forming apparatus capable of transporting continuous paper without feed holes is used to form images by transporting continuous paper with feed holes. It is an object of the present invention to provide a mechanism that can accurately correct the printing position of an image as compared with the case of handling image information for one page.

  According to the first aspect of the present invention, there is provided a sheet conveying unit that conveys a continuous sheet of continuous belt, an image forming unit that prints an image on the continuous sheet conveyed by the sheet conveying unit, and a feed hole in the continuous sheet Each print page on which the image information is printed based on the feed hole detecting means for detecting the feed hole, and the interval between the feed holes and the page length of the image information to be printed. And setting means for setting the feed hole to be detected by the feed hole detecting means, a reference time for detecting the feed hole, and the reference time set by the setting means and the feed for each print page. An image forming apparatus comprising: a paper conveyance correction unit that corrects a conveyance speed of the continuous paper according to a time difference from a detection time when the hole detection unit detects the feed hole to be detected.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the exposure correction unit corrects the exposure time of the latent image formation in the image forming unit according to the time difference between the reference time and the detection time. It is characterized by providing.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the first detection means provided in a state facing the first surface of the continuous paper, and the second surface of the continuous paper. And a page reference mark detection means for detecting the page reference mark when the continuous sheet is provided with a page reference mark for defining the leading position of each page. One of the first detection means and the second detection means functions as the feed hole detection means, and the other detection means functions as the page reference mark detection means. Features.

  According to a fourth aspect of the present invention, there is provided a sheet conveying unit that conveys a continuous sheet that is continuous in a belt shape, an image forming unit that prints an image on the continuous sheet conveyed by the sheet conveying unit, and an image position on the continuous sheet. The registration mark printing means for printing the registration mark for alignment, and the feed hole position and the print for each print page on which image information is printed when the continuous paper is provided with feed holes. An image forming apparatus comprising: a printing position correcting unit that corrects a printing position of the alignment mark based on a relationship with a top position of a page.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the registration mark detecting means for detecting the alignment mark and the printing position of the alignment mark corrected by the mark printing position correcting means. Accordingly, the registration mark detection means includes mark detection time correction means for correcting the time at which the alignment mark is detected.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth aspect, when a page reference mark that defines the top position of a page is provided on the continuous sheet, a page reference that detects the page reference mark is provided. A mark detection unit; and a page setting unit that sets a top position of a printed page based on a time when the page reference mark detection unit detects the page reference mark. The mark print position correction unit includes the page setting unit. The printing position of the alignment mark is corrected based on the relationship between the head position of the printed page set by the means and the hole position of the feed hole.

  According to the first aspect of the present invention, when an image forming apparatus capable of transporting continuous paper not provided with feed holes is used to transport continuous paper provided with feed holes to form an image, Compared with the case where image information for a plurality of pages is handled as image information for one page, the print position of the image can be corrected with high accuracy.

  According to the second aspect of the present invention, when the positional deviation of the image due to the time difference between the reference time and the detection time cannot be corrected only by correcting the conveyance speed of the continuous paper, the correction of the exposure time is insufficient. Can be supplemented.

  According to the third aspect of the present invention, the first and second portions provided corresponding to the front and back sides of the continuous paper are provided on both sides of the front and back surfaces of the continuous paper. Both the page reference mark and the feed hole can be detected using the detection means.

  According to the invention described in claim 4, when an image is formed by transporting continuous paper provided with feed holes using an image forming apparatus capable of transporting continuous paper provided with no feed holes, Even if the relationship between the spacing between the feed holes and the page length of the image information is not an integer ratio, the alignment mark can be printed at a position avoiding the hole positions of the feed holes.

  According to the fifth aspect of the present invention, the alignment mark detection means can detect the alignment mark at a time that matches the printing position of the alignment mark corrected by the mark printing position correction means.

  According to the sixth aspect of the present invention, when handling continuous paper provided with a page reference mark, it is possible to accurately grasp the head position of the printed page and correct the printing position of the alignment mark.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the technical scope of the present invention is not limited to the embodiments described below, and various modifications and improvements have been made within the scope of deriving specific effects obtained by the constituent requirements of the invention and combinations thereof. Also includes form.

  FIG. 1 is a schematic view showing an example of an image forming apparatus to which the present invention is applied. The illustrated image forming apparatus 10 has a tandem configuration including four image forming units 11, 12, 13, and 14. Each of the image forming units 11, 12, 13, 14 forms (prints) an image of a different color on the continuous paper 15 that is continuous in a band shape. The continuous paper 15 is transported from the right side to the left side in the drawing in the direction in which the four image forming units 11, 12, 13, and 14 are arranged. In this paper transport direction, the four image forming units 11, 12, 13, and 14 are, for example, black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side to the downstream side. They are arranged in color order.

  The image forming units 11 to 14 have a common configuration. For this reason, here, the configuration of the image forming unit 11 will be described as a representative, and description regarding the configurations of the other image forming units 12, 13, and 14 will be omitted. The image forming unit 11 includes a drum-shaped photoconductor 11a, a latent image writing device 11b, a developing device 11c, a transfer device 11d, and the like.

  The photoreceptor 11a is rotationally driven at a constant speed in the counterclockwise direction in the figure. The latent image writing device 11b exposes the surface of the photoconductor 11b charged to a predetermined potential by a charger (not shown) in the photoconductor rotation axis direction (depth direction in the drawing) with laser light based on the black component image signal. By scanning, an electrostatic latent image is formed.

  The developing device 11c develops the electrostatic latent image formed on the surface of the photoreceptor 11a by the latent image writing device 11b using toner as a developer. The transfer device 11d transfers the toner image developed by the developing device 11c onto the continuous paper 15. In the vicinity of the transfer device 11d, a pair of auxiliary rolls 11e are provided for stably transferring the image. In addition, a photoconductor cleaner that removes toner remaining on the surface of the photoconductor without being transferred by the transfer device 11d is provided around the photoconductor 11a.

  In the image forming unit 11 having the above structure, the electrostatic latent image formed by the latent image writing device 11b on the surface of the photoreceptor 11a is developed into a toner image by the developing device 11c, and the toner image is transferred to the transfer device. The image is transferred to the continuous paper 15 by 11d.

  The image forming operation by the image forming unit 11 is controlled by the image forming control unit 16, and the image forming operation by the image forming unit 12 is controlled by the image forming control unit 17. The image forming operation by the image forming unit 13 is controlled by the image forming control unit 18, and the image forming operation by the image forming unit 14 is controlled by the image forming control unit 19.

  When forming a color image using the image forming apparatus 10, original image data (image information) that is an object of image formation is divided into black, cyan, magenta, and yellow color components by the image output control unit 20. . The image formation control unit 16 receives black component image data from the image output control unit 20. Therefore, the image forming control unit 16 controls the operation of the image forming unit 11 based on the black component image data. The image formation control unit 17 is input with cyan component image data from the image output control unit 20. Therefore, the image forming control unit 17 controls the operation of the image forming unit 12 based on the cyan component image data.

  The image formation control unit 18 receives magenta color component image data from the image output control unit 20. Therefore, the image formation control unit 18 controls the operation of the image formation unit 13 based on the image data of the magenta color component. The image formation control unit 19 receives yellow color component image data from the image output control unit 20. For this reason, the image formation control unit 19 controls the operation of the image forming unit 14 based on the image data of the yellow color component.

  Further, the image forming apparatus 10 employs a friction conveyance method as a conveyance method for the continuous paper 15. The friction conveyance method is a method of conveying a sheet using a frictional force. The friction conveyance system is a mechanism realized by the main drive roll 21 and the sub drive roll 22. The main drive roll 21 is provided upstream of the image forming unit 11 in the paper transport direction. The sub drive roll 22 is provided on the downstream side of the image forming unit 14 in the paper transport direction. The main drive roll 21 and the sub drive roll 22 each utilize a frictional force acting between the paper surface of the continuous paper 15 and the outer peripheral surface of the roll that sandwiches the continuous paper 15 by sandwiching and rotating the continuous paper 15 with a pair of rolls. Thus, a conveying force is applied to the continuous paper 15.

  The continuous paper 15 is conveyed according to the rotation amount and rotation speed of the main drive roll 21. Therefore, the conveyance speed of the continuous paper 15 depends on the rotation speed of the main drive roll 21. The sub-drive roll 22 conveys the continuous paper 15 while applying an appropriate tension so that the continuous paper 15 fed out according to the rotation of the main drive roll 22 does not sag. A sheet conveyance path for conveying the continuous sheet 15 is formed by using the above-described two drive rolls 21 and 22 and a plurality of guide rolls 23a, 23b, 23c, and 23d.

  In the paper conveyance path, a first detection sensor 24 and a second detection sensor 25 are provided between the main drive roll 21 and the guide roll 23b. The first detection sensor 24 is provided as a feed hole detection unit that detects feed holes provided in the continuous paper 15 at regular intervals. The first detection sensor 24 is disposed so as to face a surface (first surface) on which an image of the continuous paper 15 is transferred (formed). The first detection sensor 24 optically detects the feed hole of the continuous paper 15 using, for example, a light emitting element and a light receiving element, and when the feed hole exists at the sensing position of the first detection sensor 24. The on / off state switches when it does not exist. For this reason, the first detection sensor 24 outputs a pulse signal (hereinafter also referred to as “hole detection signal”) having a period corresponding to the conveyance speed of the continuous paper 15 and the interval between the feed holes.

  The second detection sensor 25 functions as a page reference mark detection means for detecting a page reference mark (page reference mark) that defines the top position of each page when the continuous paper 15 is divided into pages in the length direction. It is. The second detection sensor 25 is arranged in a state of facing the surface (second surface) opposite to the surface on which the image of the continuous paper 15 is transferred (formed). When image data for a plurality of pages is continuously printed on the continuous paper 15, the end position of the page to be printed in advance is the head position of the page to be printed subsequently. For this reason, the end position of the preceding page and the start position of the subsequent page are the same position (page boundary position). The page reference mark may be provided on the surface on which the image of the continuous paper 15 is transferred (formed). Therefore, for the first detection sensor 24 and the second detection sensor 25, for example, the first detection sensor 24 is used as a feed hole detection unit depending on whether the page reference mark is printed on the front or back of the continuous paper 15. In the case of functioning, the second detection sensor 25 is caused to function as the page reference mark detection means. On the other hand, in the case of causing the first detection sensor 24 to function as the page reference mark detection means, the second detection sensor 25 is used. May function as a feed hole detecting means. In that case, one detection sensor serves as both the feed hole detection means and the page reference mark detection means.

  Further, a third detection sensor 26 is provided between the image forming unit 14 and the guide roll 23c in the paper conveyance path. The third detection sensor 26 functions as an alignment mark detection means for detecting an alignment mark (alignment mark) for image alignment (for color registration control). The third detection sensor 26 is disposed so as to face the surface on which the image of the continuous paper 15 is transferred. A flash fixing type fixing device 27 is provided between the guide roll 23c and the guide roll 23d. The fixing device 27 fixes the toner image transferred to the continuous paper 15 by the image forming units 11 to 14 on the paper surface by heat treatment.

  The first detection sensor 24, the second detection sensor 25, and the third detection sensor 26 are configured using, for example, a reflective laser sensor. However, the present invention is not limited to this, and each of the detection sensors 24, 25, and 26 may be configured using, for example, a CCD (Charge Coupled Device) sensor. Each of the detection sensors 24, 25, and 26 is provided to be movable in the paper width direction by a sensor moving mechanism (not shown). The reason why each detection sensor 24, 25, 26 is moved in the paper width direction is, for example, when the width dimension of the continuous paper 15 to be handled is changed, each detection sensor 24, 25, 26 is moved in the paper width direction accordingly. This is for arranging at an appropriate position. The paper width direction is a direction perpendicular to the paper length direction.

  A page setting unit 28 is connected to the first detection sensor 24 and the second detection sensor 25. The page setting unit 28 is provided as page setting means. The page setting unit 28 virtually prints on the surface of the continuous paper based on the time when the first detection sensor 24 detects the feed hole and / or the time when the second detection sensor 25 detects the page reference mark. This is to set the top position of the page. The page head position information set by the page setting unit 28 is given to the image forming control unit 16 that controls the operation of the image forming unit 11 arranged at the most upstream position in the sheet conveying direction. As used herein, “time” is a term synonymous with “timing”.

  An image misalignment detection unit 29 is connected to the third detection sensor 26. The image misregistration detection unit 29 performs black alignment based on the reading result when the third detection sensor 26 reads the alignment mark printed separately for each color component of black, cyan, magenta, and yellow. With reference to the mark, the amount of displacement of the cyan, magenta, and yellow color component images with respect to the main scanning direction and the sub-scanning direction is detected. The main scanning direction corresponds to the scanning direction of laser light when the latent image writing device writes an electrostatic latent image on the surface of the photoreceptor. The sub-scanning direction corresponds to a direction orthogonal to the main scanning direction. The width direction of the continuous paper corresponds to the main scanning direction, and the length direction of the continuous paper (paper conveyance direction) corresponds to the sub-scanning direction.

  Image misregistration information (including the misregistration amount and misregistration direction) detected by the image misregistration detection unit 29 is provided to the image formation control unit 16. The image formation control unit 16, based on the image position shift information detected by the image position shift detection unit 29, corrects the print position of the cyan image based on the black image, and the black image. M correction values for correcting the print position of a magenta image with reference to the image, and Y correction values for correcting the print position of a yellow image with reference to a black image, respectively. , 19. The C correction value is a correction value for aligning a cyan image with a black image. The M correction value is a correction value for aligning the magenta image with the black image, and the Y correction value is the correction value for aligning the yellow image with the black image. It becomes.

  In the image formation control unit 17 to which the C correction value is given from the image formation control unit 16, based on the C correction value, the exposure time when the image forming unit 12 forms an electrostatic latent image on the surface of the photoreceptor, The image writing position in the main scanning direction is corrected. Similarly, in the image formation control unit 18 to which the M correction value is given from the image formation control unit 16, when the electrostatic latent image is formed on the surface of the photoreceptor by the image forming unit 13 based on the M correction value. In the image forming control unit 19 that corrects the exposure time and the image writing position in the main scanning direction and is given a Y correction value from the image forming control unit 16, the image forming unit 14 performs photoconductors on the basis of the Y correction value. The exposure time at the time of forming an electrostatic latent image on the surface and the image writing position in the main scanning direction are corrected.

  In the image forming apparatus 10 configured as described above, the image forming unit 11 produces a black toner image on the continuous paper 15 conveyed by the rotational drive of the main drive roll 21 and the sub drive roll 22, and the image formation unit 12 provides the black toner image. The cyan toner image, the magenta toner image by the image forming unit 13, and the yellow toner image by the image forming unit 14 are sequentially transferred in a superimposed manner. Thereby, one color image is formed on the continuous paper 15. This color image is fixed on the surface of the continuous paper 15 by the fixing device 27.

  FIG. 2 is a block diagram showing a partial configuration of a control system of the image forming apparatus according to the embodiment of the present invention. In FIG. 2, the main control unit 31 includes an image formation timing signal generation unit 32, a setting unit 33, a reference signal cycle generation unit 34, a reference signal generation unit 35, a time difference detection unit 36, and a paper conveyance control unit 37. And an exposure control unit 38. The hole detection signal output from the first detection sensor 24 is captured by the image formation timing signal generation unit 32, the reference signal cycle generation unit 34, and the time difference detection unit 36. The mark detection signal output from the second detection sensor 25 is captured by the image formation timing signal generation unit 32, the reference signal cycle generation unit 34, and the time difference detection unit 36. The image forming timing signal generation unit 32 generates a timing signal for forming an image of each color component in each of the image forming units 11 to 14. The exposure control unit 38 controls the exposure operation in each of the image forming units 11 to 14 according to the timing signal output from the image forming timing signal generating unit 32.

  The setting unit 33 functions as a setting unit. In the first embodiment of the present invention, when the setting unit 33 handles the continuous paper 15 provided with feed holes, the setting hole 33 and the page length of the image data to be printed in the paper length direction. Based on the above, for each print page on which image data is printed, the first detection sensor 24 sets a feed hole to be detected and a reference time for detecting the feed hole. A specific setting method will be described in detail later. Information on the reference time set by the setting unit 33 is given to the reference signal cycle generation unit 34. The reference signal cycle generation unit 34 instructs the reference signal generation unit 35 to output a reference signal at a cycle according to the reference time given from the setting unit 33. The reference signal generation unit 35 generates a reference signal in accordance with an instruction from the reference signal cycle generation unit 34. The time difference detector 36 detects the time difference between the output times based on the phase difference between the reference signal output from the reference signal generator 35 and the hole detection signal output from the first detection sensor 34 on the time axis. To do. The detection result of the time difference detection unit 36 is given to the image formation timing signal generation unit 32, the paper conveyance control unit 37, and the exposure control unit 38.

  The paper transport control unit 37 controls the transport speed of the continuous paper 15 with the paper transport motor 39 serving as a drive source for transporting the continuous paper 15 being the target of drive control. The sheet conveyance control unit 37 functions as a sheet conveyance correction unit. The exposure control unit 38 controls the exposure operation when the latent image writing device forms an electrostatic latent image on the surface of the photoreceptor in each of the image forming units 11 to 14. In this case, the image formation timing signal generation unit 32 gives an instruction of an exposure start time and an exposure end time that define an exposure cycle for one page for each page of image data. The exposure control unit 38 functions as an exposure correction unit.

(First embodiment)
FIG. 3 is a flowchart showing an operation procedure of the image forming apparatus according to the first embodiment of the present invention. FIG. 4 is a time chart showing an operation procedure of the image forming apparatus according to the first embodiment of the present invention. The following apparatus operations are performed according to the control process of the main control unit 31.

  First, the page length of image data to be printed is set by analyzing printing conditions designated by the user using the operation unit of the image forming apparatus (step ST1). “Page length of image data” defines the length per page of image data. For this reason, for example, when printing image data to be printed on a continuous sheet with a letter size (11 inches × 8.5 inches) per page, the page length of the image data is in the sheet length direction. 11 inches for a vertically oriented image and 8.5 inches for a horizontally oriented image. Incidentally, when image data for a plurality of pages is printed side by side in a print area for one page on the surface of the continuous paper 15, the length of the print area is set to the page length of the image data.

  Next, on the basis of the relationship between the spacing between the feed holes provided in the continuous paper used for printing the image and the page length of the image data set in step ST1, for each print page on which the image data is printed, A feed hole to be detected by one detection sensor 24 and a reference time for detecting the feed hole are set (step ST2). This processing is performed by the setting unit 33. The interval between the feed holes may be recognized by referring to the paper information designated by the user using the operation unit of the image forming apparatus or the like. A hole may be detected and certified based on the detection result (output period of the hole detection signal). Since the operation in the case where the relationship between the feed hole interval and the page length of the image data is an integer ratio is not different from the conventional case, the case where the dimensional relationship is not an integer ratio will be described here.

  As an example, it is assumed that the interval between the feed holes provided in the continuous paper is ½ inch and the page length of the image data is set to 12 inches + 1/6 inch. In this case, the page length of the image data is not an integral multiple of the interval between feed holes (1/2 inch), and a multiple (36 inches + 1/2 inch) when the page length of the image data is tripled is It is an integral multiple of the hole spacing. Therefore, the positional relationship between the feed hole and the printed page returns to the same positional relationship every time image data for three pages is printed. In such a case, with respect to the first to third pages, the feed hole to be detected by the first detection sensor 24 and the reference time at which the first detection sensor 24 should detect the feed hole for each printed page. Set.

  That is, for the first page, one feed hole corresponding to the first printed page is set as a detection target, and a reference time for detecting the feed hole is set to T1. For the second page, one feed hole corresponding to the second printed page is set as a detection target, the reference time for detecting the feed hole is set to T2, and for the third page, One feed hole corresponding to the third printed page is set as a detection target, and a reference time for detecting the feed hole is set to T3. The reference time T1 is applied every third page, such as the first page, the fourth page, the seventh page,. Further, the reference time T2 is applied every second page, the fifth page, the eighth page,... And the reference time T3 is applied every third page, the sixth page, the ninth page,. Applies to The reference time is defined by the length of time on the time axis.

  As shown in FIG. 5, when the interval between the feed holes provided in the continuous paper is ½ inch and the page length of the image data is set to 12 inches + 1/6 inch, the first page, With respect to the third and third pages, the feed holes to be detected and the reference time at which the feed holes are to be detected are set as follows. First, for the first page, the feed is located at a position that is an integer multiple of the feed hole interval and closest to the page length of the image data from the feed holes detected by the first detection sensor 24 at a predetermined time. In addition to setting a feed hole to be detected on the first printed page, a reference time at which the feed hole is to be detected is set. Specifically, a feed hole located at a distance of 12 inches from a feed hole detected at a predetermined time is set as a feed hole to be detected on the first printed page, and the feed hole is The reference time T1 to be detected is set to a time equivalent to 12 inches.

  Further, regarding the second page, two feed holes located at a distance that is an integer multiple of the feed hole interval and closest to the page length of the image data from the feed hole set as the detection target on the first page are 2 A feed hole to be detected is set on the printed page of the page, and a reference time for detecting the feed hole is set. Specifically, a feed hole located at a distance of 12.5 inches from the feed hole set as the detection target on the first page is set as a feed hole to be detected on the second printed page. The reference time T2 at which the feed hole should be detected is set to a time corresponding to 12.5 inches.

  Further, regarding the third page, a feed hole located at a position that is an integer multiple of the feed hole interval and closest to the page length of the image data from the feed hole set as the detection target in the second page is 3 A feed hole to be detected is set on the printed page of the page, and a reference time for detecting the feed hole is set. Specifically, the feed hole located 12 inches away from the feed hole set as the detection target on the second page is set as the feed hole to be detected on the third printed page, and A reference time T3 at which the feed hole is to be detected is set to a time corresponding to 12 inches. As a result, the total from the first page to the third page is equivalent to three times the page length of the image data. The “equivalent time” described here means the time required to convey the continuous paper by the length of the numerical value. The fourth and subsequent pages are repeated in the same manner as the first to third pages.

  If such setting conditions are adopted, the feed hole to be detected for each print page in the state where the interval between the feed holes to be detected is closest to the cycle of the print page in the length direction of the continuous paper 15. And the reference time for detecting the feed hole is set. However, the present invention is not limited to this. For example, the reference time T1 applied to the first page is set to a time corresponding to 12 inches so that the total of the reference times T1 to T3 for three pages corresponds to a time equivalent to three times the page length of the image data. The reference time T2 applied to the second page may be set to 12 inch equivalent time, and the reference time applied to the third page may be set to 12.5 inch equivalent time. Also, the reference time T1 applied to the first page is set to 12.5 inch equivalent time, the reference time T2 applied to the second page is set to 12 inch equivalent time, and the reference time applied to the third page is set to 12 inch equivalent time. May be. In any setting condition, the setting variation of the reference times T1 to T3 can be suppressed to a time corresponding to a minimum of 0.5 inch (feed hole interval).

  Next, the conveyance of the continuous paper 15 is started by the rotational drive of the main drive roll 21 and the sub drive roll 22 (step ST3). This process is performed by the paper transport control unit 37 driving the paper transport motor 39. Next, it is determined whether or not the conveyance speed of the continuous paper 15 has become a constant speed (step ST4). Whether the continuous paper 15 is conveyed at a constant reference speed at a predetermined reference speed is determined by the paper conveyance control unit 37 in consideration of, for example, the acceleration characteristics of the paper conveyance motor 39 serving as the drive source of the main drive roll 21. It may be determined whether or not the elapsed time from the start of the sheet conveyance has reached a predetermined time. Further, the determination may be made based on whether or not the output period of the hole detection signal output from the first detection means 24 has become a constant period. Alternatively, the rotational speed of the main drive roll 21 may be detected by an encoder or the like, and it may be determined whether or not the detected rotational speed is stabilized at a preset speed.

  Next, after the hole detection enable signal is raised from OFF to ON (step ST5), if the first detection sensor 24 detects the first feed hole (Yes in step ST6), the first timer Time measurement and time measurement by the exposure start timer are started simultaneously (step ST7). Here, the time at which the first detection sensor 24 detects the first feed hole is the “predetermined time”.

  Next, it is confirmed whether or not the measured value of the first timer has reached the reference time T1 (step ST8), and when it reaches, the time measurement by the second timer is started (step ST9).

  Next, it is determined whether or not there is a time difference between the time when the measurement value of the first timer reaches the reference time T1 and the detection time when the first detection sensor 24 actually detects the feed hole at the time (step). ST10). The time difference is detected by the time difference detector 36. If a time difference Δt1 occurs at those times, the conveyance speed and exposure time of the continuous paper 15 are corrected according to the time difference (difference) Δt1 (step ST11). The paper conveyance speed is corrected by the paper conveyance control unit 37, and the exposure time is corrected by the exposure control unit 38.

  Here, there is a continuous time difference between the time when the measurement value of the first timer reaches the reference time T1 and the detection time when the first detection sensor 24 actually detects the feed hole at that time. This corresponds to the case where the transport position of the paper 15 is advanced or delayed from the reference transport position. For this reason, the correction of the conveyance speed of the continuous paper 15 is performed in order to eliminate the advance and delay of the paper conveyance. In addition, the conveyance speed of the continuous paper 15 is corrected by changing the rotation speed of the paper conveyance motor 39 serving as the drive source of the main drive roll 21 until the paper conveyance control unit 37 completes the exposure period for one page. In accordance with the time difference (difference) described above, the acceleration or deceleration is performed.

  However, when correcting the paper conveyance speed, it is necessary to gradually change the conveyance speed in order to reduce the influence on the image quality due to the speed fluctuation. For this reason, there may be a case where the error corresponding to the time difference cannot be completely corrected only by correcting the paper conveyance speed due to limitation of a correctable period. In order to deal with such a case, here, the exposure time is corrected in addition to the sheet conveyance speed. The exposure time refers to the exposure time of the laser beam applied when the latent image writing device forms an electrostatic latent image on the surface of the photoreceptor in each of the image forming units 11 to 14 described above. The exposure time includes an exposure start time and an exposure end time that define an exposure period for one page of image data. In step ST11, the exposure control unit 38 corrects both the exposure start time and the exposure end time so that the exposure period is shifted to one side or the other side on the time axis.

  Next, it is confirmed whether or not the measurement value of the second timer has reached the reference time T2 (step ST12), and when it reaches, the time measurement by the third timer is started (step ST13).

  Next, it is determined whether or not there is a time difference between the time when the measured value of the second timer reaches the reference time T2 and the detection time when the first detection sensor 24 actually detects the feed hole at the time (step). ST14). If a time difference Δt2 occurs at those times, the conveyance speed and exposure time of the continuous paper 15 are corrected according to the time difference (difference) Δt2 (step ST15).

  Next, it is confirmed whether or not the measurement value of the third timer has reached the reference time T3 (step ST16), and when it reaches, the time measurement by the first timer is started (step ST17).

  Next, it is determined whether or not there is a time difference between the time when the measurement value of the third timer reaches the reference time T3 and the detection time when the first detection sensor 24 actually detects the feed hole at the time (step). ST18). If there is a time difference Δt3 at those times, the conveyance speed and exposure time of the continuous paper 15 are corrected according to the time difference (difference) Δt3 (step ST19). Thereafter, the process returns to step ST8. When the image data for the fourth page is printed, the reference times T1 to T3 for three pages are applied in order as described above, but the time differences Δt4, Δt5, Δt6,... Are detected for each page. The

  FIG. 6 is a flowchart showing a procedure of exposure control including exposure time correction. This process is performed by the exposure control unit 38.

  First, it is confirmed whether or not the measured value of the exposure start timer that has started time measurement in step ST7 has reached a preset exposure start reference time Tw (step ST21), and when it reaches, exposure is started (step ST22). ).

  Next, a preset time before the end of exposure in the exposure period for one page where exposure is started in step ST22 (for example, a time for scanning a position 1/2 inch before the exposure end time). Is reached (step ST23), and if it is reached, it is confirmed whether there is image data to be printed on the next page (step ST24). If there is no image data to be printed on the next page, the process ends without performing the exposure process for the next page.

  If there is image data to be printed on the next page, it is determined whether exposure time correction is necessary (step ST25). This determination is affirmative when the exposure time is corrected in steps ST11, ST15, and ST19, and negative otherwise.

  When it is determined that the exposure time needs to be corrected, the exposure time is corrected (changed) in the direction of shortening or extending the exposure period based on the time difference detected by the time difference detection unit 36 in steps ST10, ST14, and ST18. (Step ST26). That is, for the image data of the first page, if the time converted to the page length of the image data is Tfcb (for example, Tfcb = 12 inches + 1/6 inch equivalent time), the exposure period is Tfcb + α · Δt1. The exposure time is corrected. α is a coefficient for correcting the exposure time by the amount that cannot be corrected by correcting the conveyance speed. Similarly, the exposure time is corrected so that the exposure period is Tfcb + α · Δt2 for the image data of the second page, and the exposure period is Tfcb + α · Δt3 for the image data of the third page. Correct the time. Further, with respect to the image data on the fourth page, the exposure cycle is corrected so that the exposure period is Tfcb + α · Δt4, and with respect to the image data on the fifth page, the exposure time is set so that the exposure period is Tfcb + α · Δt5. Correct. The exposure time is similarly corrected for subsequent pages.

  When the exposure time is corrected in a direction that shortens the exposure period (in other words, when the exposure start time of the next page is advanced), the image is changed from the stage approaching the end of the exposure period in accordance with the exposure time correction amount. The exposure time is corrected by thinning (subtracting) the number of data scans at a predetermined rate. When correcting the exposure time in the direction of extending the exposure period (in other words, when delaying the exposure start time of the next page), the exposure time is adjusted according to the exposure time correction amount from the stage approaching the end of the exposure period. The exposure time is corrected by interpolating (adding) the number of scans of image data at a predetermined rate. Then, after starting the exposure of the next page (step ST27), the process returns to step ST23.

(Second Embodiment)
FIG. 7 is a flowchart showing an operation procedure of the image forming apparatus according to the second embodiment of the present invention. FIG. 8 is a time chart showing the operation procedure of the image forming apparatus according to the second embodiment of the present invention. The following apparatus operations are performed according to the control process of the main control unit 31. Here, it is assumed that a page reference mark that defines the top position of the page is printed on the continuous paper 15. In addition, the top position of each page on the continuous paper 15 is defined by a position that is separated from the position where the page reference mark is printed on one side or the other side in the paper length direction. For example, in the image forming system having a double-layered structure (double-sided printing method) in which two image forming apparatuses illustrated in FIG. In some cases, a page reference mark is printed, and the page start mark is used to define the top position of the page in the subsequent image forming apparatus. In some cases, a page reference mark is printed in advance on continuous paper before printing, such as preprinted paper. The present invention may be applied to either case.

  First, the page length of image data to be printed is set by analyzing the printing conditions designated by the user using the operation unit of the image forming apparatus (step ST31). This processing is performed by the setting unit 33. Next, the conveyance of the continuous paper 15 is started by the rotational drive of the main drive roll 21 and the sub drive roll 22 (step ST32). This process is performed by the paper transport control unit 37 driving the paper transport motor 39. Next, it is determined whether or not the conveying speed of the continuous paper 15 has become a constant speed (step ST33).

  Next, after the mark detection enable signal is raised from off to on (step ST34), if the first page reference mark is detected by the second detection sensor 25 (Yes in step ST35), the positional relationship is detected. Time measurement by the timer, time measurement by the exposure start timer, time measurement by the first mark detection timer, and time measurement by the second mark detection timer are started simultaneously (step ST36).

  Next, when the first detection hole is detected by the first detection sensor 24 (Yes in step ST37), the time measurement by the positional relationship detection timer is stopped (step ST38). As a result, the measured value of the positional relationship detection timer is detected by the first detection sensor 24 from the time when the second detection sensor 25 detects the first page reference mark after the enable signal is raised. This value indicates the elapsed time up to the time.

  Next, based on the time value measured by the positional relationship detection timer, it is determined to which case the positional relationship between the page reference mark and the feed hole corresponds (step ST39). Here, as an example, it is assumed that the interval between the feed holes provided in the continuous paper is 1/2 inch and the page length of the image data is set to 3 inches + 1/6 inch. In such a case, the positional relationship between the feed hole and the printed page returns to the same positional relationship every time image data for three pages is printed. Therefore, the positional relationship between the page reference mark that defines the top position of the printed page and the feed hole is divided into three cases A, B, and C as shown in FIG. As shown in the figure, the feed holes 41 are provided on both sides of the continuous paper 15 at regular intervals. Further, on the continuous paper 15, one page reference mark 42 is printed per page at intervals corresponding to the page length in the paper transport direction. Case A in the figure is reproduced every third page, such as the first page, the fourth page, the seventh page,. In addition, case B in the figure is reproduced every third page, such as the second page, the fifth page, the eighth page,..., And case C in the figure is the third page, the sixth page, and the ninth page. It is reproduced every third page. In the illustrated example, the top position of the first page is set between two feed holes that are adjacent in the sheet length direction (intermediate position).

  Next, based on the positional relationship between the page reference mark and the feed hole, the printing position of the alignment mark is set for each printed page (step ST40). That is, when the positional relationship between the page reference mark and the feed hole corresponds to case A in FIG. 9, the first feed hole 41 is located at a position 1/4 inch away from the top position of the page defined by the page reference mark 42. Therefore, the print position of the alignment mark is set downstream of the feed hole 41 in the paper transport direction so as not to overlap with the feed hole 41.

  Further, when the positional relationship between the page reference mark and the feed hole corresponds to case B in FIG. 9, the first position is 1/4 inch + 2/6 inch apart from the top position of the page defined by the page reference mark 42. Since the feed hole 41 exists, the printing position of the alignment mark is set downstream of the feed hole 41 in the paper transport direction so as not to overlap the feed hole 41.

  When the positional relationship between the page reference mark and the feed hole corresponds to the case C in FIG. 9, the first position is 1/4 inch + 1/6 inch apart from the top position of the page defined by the page reference mark 42. Since the feed hole 41 exists, the printing position of the alignment mark is set downstream of the feed hole 41 in the paper transport direction so as not to overlap the feed hole 41.

  Thus, comparing the case A and the case B, the position where the alignment mark is printed in the case B is 2/6 inches from the top position of the page than the position where the alignment mark is printed in the case A. Only the position shifted to the downstream side in the sheet conveyance direction is set. Further, comparing the case A and the case C, the position where the alignment mark is printed in the case C is only 1/6 inch from the top position of the page than the position where the alignment mark is printed in the case A. It is set at a position shifted to the downstream side in the paper transport direction.

  The print position of the alignment mark is set by the image forming timing signal generator 32, for example. In this case, the image formation timing signal generation unit 32 sets an alignment mark (alignment mark) for each print page on which image data is printed based on the relationship between the hole position of the feed hole and the start position of the print page. It functions as a printing position correcting means for correcting the printing position.

  In the image forming apparatus 10 shown in FIG. 1, the alignment mark stores mark image data to be applied to printing of the alignment mark in each of the image formation control units 16, 17, 18, and 19, for example. Based on the mark image data, each image formation control unit 16, 17, 18, 19 controls the operation of the corresponding image formation unit 11, 12, 13, 14 to print on the continuous paper 15. Is done. In this case, the registration mark printing means is realized by the image forming units 11, 12, 13, and 14 and the image forming controllers 16, 17, 18, and 19.

  The alignment marks are printed in four groups as shown in FIG. 10, for example. The first set is a set of black (K) and cyan (C) that are printed with bar-shaped marks along the main scanning direction. The second set is a set of magenta (M) and yellow (Y) that are printed with bar-shaped marks along the main scanning direction. The third set is a black and cyan set printed with bar-shaped marks inclined obliquely with respect to the main scanning direction. The fourth set is a set of magenta and yellow printed with bar-like marks inclined obliquely with respect to the main scanning direction. The alignment marks of each set are formed at positions separated by the same interval (P1 = P2 = P3) as the interval between the feed holes in the length direction of the continuous paper 15. For this reason, the printing position of the alignment mark on each page (printing range of the alignment mark in the paper length direction) is shifted as a whole in accordance with the setting of the printing start position. For this reason, when the alignment mark is printed on the continuous paper 15 according to the above setting, the result is as shown in FIG. As can be seen from FIG. 11, in cases A, B, and C, the relationship between the top position of the page and the hole position of the feed hole 41 is different, but the relationship between the hole position of the feed hole 41 and the printing position of the alignment mark is different. Are equal.

  Next, the time for detecting the alignment mark is set according to the printing position of the alignment mark set in step ST40 (step ST41). That is, when the print start position of the alignment mark is set to a position that is 1/4 inch apart from the top position of the page (when the positional relationship between the reference mark and the feed hole corresponds to case A), the position is changed accordingly. The detection time of the alignment mark is set to Troca. Also, if the printing start position of the alignment mark is set to a position that is 1/4 inch + 2/6 inch apart from the top position of the page (when the positional relationship between the reference mark and the feed hole corresponds to case B), this Accordingly, the detection time of the alignment mark is set to Trocb. In addition, if the print start position of the alignment mark is set to a position 1/4 inch + 1/6 inch apart from the top position of the page (when the positional relationship between the reference mark and the feed hole corresponds to case C), Accordingly, the detection time of the alignment mark is set to Trocc. For example, the setting unit 33 sets the detection time of the alignment mark. In this case, the setting unit 33 functions as a mark detection time correction unit that corrects the time at which the alignment mark detection unit detects the alignment mark according to the printing position of the alignment mark corrected by the mark printing position correction unit. Will do. Thereafter, the four processes shown in FIGS. 12 to 15 are performed in parallel.

  In the processing shown in FIG. 12, first, it is confirmed whether or not the measurement value of the first mark detection timer has reached the time Tfcb corresponding to the page length (3 inches + 1/6 inch) of the image data (step ST51). Then, the measurement value of the first mark detection timer is reset to zero and time measurement is started again (step ST52). Whether or not the measurement value of the first mark detection timer has reached the page length equivalent time Tfcb of the image data is confirmed by the reference signal synchronization generation unit 34. When it is confirmed that the measurement value of the first mark detection timer has reached the page length equivalent time Tfcb of the image data, a page reference mark detection reference signal is output from the reference signal generator 35.

  Next, the time when the measurement value of the first mark detection timer reaches the page length equivalent time Tfcb of the image data in step ST51 and the detection that the second detection sensor 25 actually detected the page reference mark at the time. It is determined whether there is a time difference from the time (step ST53). The time difference is detected by the time difference detector 36. If a time difference Δt1 occurs between these times, the conveyance speed and exposure time of the continuous paper 15 are corrected according to the time difference (difference) Δt1 (step ST54). Thereafter, the process returns to step ST51 and the same processing is repeated.

  In the process shown in FIG. 13, first, it is confirmed whether or not the measured value of the exposure start timer has reached a preset exposure start reference time Tw (step ST61), and when reached, exposure is started (step ST62).

  Next, a preset time before the end of exposure (for example, a time for scanning a position 1/2 inch before the exposure end time) in the exposure period for one page where exposure is started in step ST62. Is reached (step ST63), and if it is reached, it is confirmed whether there is image data to be printed on the next page (step ST64). If there is no image data to be printed on the next page, the process ends.

  If there is image data to be printed on the next page, the printing position of the alignment mark is set depending on which case the positional relationship between the page reference mark and the feed hole corresponds to on the next page (step ST65). . That is, when the positional relationship between the page reference mark and the feed hole corresponds to case A, the print start position of the alignment mark is set to a position that is 1/4 inch apart from the top position of the page. When the positional relationship between the page reference mark and the feed hole corresponds to case B, the printing start position of the alignment mark is set at a position 1/4 inch + 2/6 inch apart from the top position of the page, and the page reference is set. When the positional relationship between the mark and the feed hole corresponds to Case C, the printing start position of the alignment mark is set to a position that is 1/4 inch + 1/6 inch apart from the top position of the page.

  Next, it is determined whether exposure time correction is necessary when printing image data on the next page (step ST66). This determination is affirmative when the exposure time is corrected in step ST54, and negative otherwise.

  If it is determined that the exposure time needs to be corrected, the exposure time is corrected in a direction to shorten or extend the exposure period based on the time difference generated in step ST53 (step ST67). Then, after starting the exposure of the next page (step ST68), the process returns to step ST63.

  In the process shown in FIG. 14, first, it is confirmed whether or not the page reference mark is detected by the second detection sensor 25 (step ST71). When the page reference mark is detected by the second detection sensor 25, time measurement by the positional relationship detection timer is started (restarted) (step ST72).

  Next, when the first detection hole is detected by the first detection sensor 24 (Yes in step ST73), the time measurement by the positional relationship detection timer is stopped (step ST74). As a result, for the first page, the measured value of the positional relationship detection timer is S1, and for the first page, the measured value of the positional relationship detection timer is S2. For the third page, the measured value of the positional relationship detection timer is S3, and for the fourth page, the measured value of the positional relationship detection timer is S4. For the fifth page, the measured value of the positional relationship detection timer is S5, for the sixth page, the measured value of the positional relationship detection timer is S6, and for the seventh page, the measured value of the positional relationship detection timer is S7.

  Next, based on the time value measured by the phase difference detection timer, it is determined which case the positional relationship between the page reference mark and the feed hole corresponds (step ST75).

  Next, based on the positional relationship between the page reference mark and the feed hole, the printing position of the alignment mark to be applied to the next page is set (step ST76).

  Next, according to the printing position of the alignment mark set in step ST76, the time for detecting the alignment mark is set by a combination of the previously detected case and the current detected case (step ST77). Thereafter, the process returns to step ST71.

  FIG. 16 shows a specific combination of cases and alignment mark detection time setting conditions based on this combination. As shown in the figure, if the previous detection case is Case A and the current detection case is Case A, the detection time of the alignment mark applied to the next page is equivalent to Tfcb (3 inches + 1/6 inch). Set to time. If the previous detection case is Case A and the current detection case is Case B, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb + 2/6 inch. If the previous detection case is case A and the current detection case is case C, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb + 1/6 inch.

  If the previous detection case is Case B and the current detection case is Case A, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb-2 / 6 inch. If the previous detection case is Case B and the current detection case is Case B, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb. If the previous detection case is case B and the current detection case is case C, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb-1 / 6 inch.

  If the previous detection case is case C and the current detection case is case A, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb-1 / 6 inch. If the previous detection case is Case C and the current detection case is Case B, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb + 1/6 inch. If the previous detection case is Case C and the current detection case is Case C, the detection time of the alignment mark applied to the next page is set to a time equivalent to Tfcb.

  In the process shown in FIG. 15, first, the measured value of the second mark detection timer reaches the detection time Troc (Troca in case A, Trocb in case B, Trocc in case C). (Step ST81), if reached, the measurement value of the second mark detection timer is reset to zero and time measurement is started again (step ST82).

  Next, a time difference Δtc between the time when the measurement value of the second mark detection timer reaches the detection time Troc in step ST81 and the detection time when the third detection sensor 26 actually detects the alignment mark at the time. It is determined whether there is (Δtc1, Δtc2, Δtc3, Δtc4, Δtc5,...) (Step ST83). If there is a time difference between these times, the exposure time is corrected in order to align the position of each color image according to the time difference (step ST84). Thereafter, the process returns to step ST81 and the same processing is repeated.

  With the above processing, for the image data of the first page, if the time converted to the page length of the image data is Tfcb (for example, Tfcb = 3 inches + 1/6 inch equivalent time), the exposure period is Tfcb + α · Δt1. The exposure time is corrected so that For the image data of the second page, the exposure time is corrected so that the exposure period is Tfcb + α · Δt2. For the image data of the third page, the exposure time is corrected so that the exposure period is Tfcb + α · Δt3 + β · Δtc1. β is a coefficient for preventing the oscillation of the control caused by the time shift when correcting the shift of each color. For the image data of the fourth page, the exposure time is corrected so that the exposure period is Tfcb + α · Δt4 + β · Δtc2. For the image data of the fifth page, the exposure time is corrected so that the exposure period becomes Tfcb + α · Δt5 + β · Δtc3. For the image data on the sixth page, the exposure time is corrected so that the exposure period is Tfcb + α · Δt6 + β · Δtc4. The exposure time is similarly corrected for subsequent pages.

  For the first page, the fourth page, the seventh page,..., The alignment mark exposure is started when the time Ta has elapsed from the exposure start time of each page. For the second page, the fifth page, the eighth page,..., The alignment mark exposure is started when the time Tb has elapsed from the exposure start time of each page. As for the third page, the sixth page, the ninth page,..., The alignment mark exposure is started when the time Tc elapses from the exposure start time of each page. When the interval between the feed holes is 1/2 inch and the page length of the image data is 3 inches + 1/6 inch, Ta = 1/4 inch equivalent time, Tb = Ta + 2/6 inch equivalent time, Tc = Ta + 1/6 Inch equivalent time. “Alignment mark printing time” in FIG. 8 indicates the time (period) during which exposure for printing the alignment mark is performed in the exposure period for one page of image data.

  In the second embodiment, the case of handling the continuous paper 15 on which the page reference mark is printed in advance has been described. However, the present invention is not limited to this, and the continuous paper 15 on which the page reference mark is not printed is described. It may be applied when handling In that case, what is necessary is just to prescribe | regulate the head position of each page as follows. That is, for the first page, the top position of the page is defined with reference to the time when the first feed hole is detected in the state where the mark detection enable signal is raised. What is necessary is just to prescribe | regulate the head position of each page according to length.

  In the second embodiment, the page reference mark is detected by the second detection sensor 25 for each page on which image data is printed, and the position is determined according to each case from the positional relationship with the feed hole. Although the printing position of the alignment mark is corrected, the present invention is not limited to this. That is, whether the positional relationship between the page reference mark and the feed hole corresponds to cases A to C is determined by the relationship between the feed hole interval and the page length of the image data. Later, if the time from the time when the first page reference mark is detected to the time when the first feed hole is detected is measured, the page reference mark is not detected for each printed page. The printing position of the alignment mark can be corrected. The operation procedure of the image forming apparatus applied in that case is shown in the time chart of FIG. As can be seen from this time chart, the time S elapsed from the time when the first page reference mark was detected to the time when the first feed hole was detected in the state where the mark detection enable signal was raised is the position relation detection timer. After that, the time is not measured by the positional relationship detection timer, and the exposure start time of the image data, the exposure start time of the alignment mark, and the detection time of the alignment mark are set in the same manner as described above ( Corrected).

1 is a schematic diagram illustrating an example of an image forming apparatus to which the present invention is applied. FIG. 2 is a block diagram illustrating a partial configuration of a control system of the image forming apparatus according to the embodiment of the present invention. 3 is a flowchart showing an operation procedure of the image forming apparatus according to the first embodiment of the present invention. 3 is a time chart showing an operation procedure of the image forming apparatus according to the first embodiment of the present invention. It is a figure which shows the relationship between a feed hole and detection time. It is a flowchart which shows the process sequence of exposure control. 6 is a flowchart (part 1) illustrating an operation procedure of the image forming apparatus according to the second exemplary embodiment of the present invention. 6 is a time chart showing an operation procedure of the image forming apparatus according to the second embodiment of the present invention. It is a figure which shows the positional relationship of a page reference mark and a feed hole. It is a figure which shows an example of the alignment mark. It is a figure which shows the example of a setting of the printing position of an alignment mark. 12 is a flowchart (part 2) illustrating an operation procedure of the image forming apparatus according to the second exemplary embodiment of the present invention. 12 is a flowchart (No. 3) showing an operation procedure of the image forming apparatus according to the second embodiment of the present invention. 12 is a flowchart (No. 4) showing an operation procedure of the image forming apparatus according to the second embodiment of the present invention. 12 is a flowchart (No. 5) showing an operation procedure of the image forming apparatus according to the second embodiment of the present invention. It is a figure which shows the example of a setting of the detection time of an alignment mark. 6 is a time chart showing another operation procedure of the image forming apparatus according to the second embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 11, 12, 13, 14 ... Image forming unit, 15 ... Continuous paper, 21 ... Main drive roll, 22 ... Sub drive roll, 24 ... 1st detection sensor, 25 ... 2nd detection sensor , 26 ... third detection sensor, 28 ... page setting unit, 31 ... main control unit, 32 ... image formation timing signal generation unit, 33 ... setting unit, 34 ... reference signal synchronization generation unit, 35 ... reference signal generation unit, 36... Time difference detector 37. Paper transport controller 38. Exposure controller 39 39 Paper transport motor

Claims (6)

A paper transporting means for transporting continuous paper that is continuous in a strip shape;
Image forming means for printing an image on the continuous paper conveyed by the paper conveying means;
When a feed hole is provided in the continuous paper, a feed hole detecting means for detecting the feed hole;
Based on the interval between the feed holes and the page length of the image information to be printed, for each print page on which the image information is printed, the feed holes to be detected by the feed hole detecting means and the feed holes are determined. Setting means for setting a reference time to be detected;
A sheet for correcting the conveyance speed of the continuous sheet according to a time difference between the reference time set by the setting unit and the detection time when the feed hole detection unit detects the detection target feed hole for each print page. An image forming apparatus comprising: a conveyance correction unit. The image forming apparatus according to claim 1, further comprising an exposure correction unit that corrects an exposure time of latent image formation in the image forming unit according to a time difference between the reference time and the detection time. First detection means provided in a state facing the first surface of the continuous paper;
Second detection means provided in a state facing the second surface of the continuous paper;
A page reference mark detecting means for detecting the page reference mark when the continuous paper is provided with a page reference mark that defines the top position of each page;
One of the first detection means and the second detection means functions as the feed hole detection means, and the other detection means functions as the page reference mark detection means. Item 3. The image forming apparatus according to Item 1 or 2. A paper transporting means for transporting continuous paper that is continuous in a strip shape;
Image forming means for printing an image on the continuous paper conveyed by the paper conveying means;
An alignment mark printing means for printing an alignment mark for image alignment on the continuous paper;
When the continuous paper is provided with feed holes, the registration mark is printed on each print page on which image information is printed based on the relationship between the hole position of the feed hole and the top position of the print page. An image forming apparatus comprising: a printing position correcting unit that corrects a printing position. Alignment mark detecting means for detecting the alignment mark;
A mark detection time correction unit that corrects a time at which the alignment mark detection unit detects the alignment mark in accordance with the printing position of the alignment mark corrected by the mark printing position correction unit. The image forming apparatus according to claim 4. A page reference mark detecting means for detecting the page reference mark when the continuous paper is provided with a page reference mark that defines the top position of the page;
Page setting means for setting the top position of the printed page based on the time when the page reference mark detection means detects the page reference mark;
The mark printing position correcting means corrects the printing position of the alignment mark based on the relationship between the start position of the printed page set by the page setting means and the hole position of the feed hole. The image forming apparatus according to claim 4.

Images