JP2017173352A - Mark position detection device, mark position detection method, image forming apparatus, and image development control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately derive the position of a mark on a medium to be printed.SOLUTION: A mark sensor 20 detects a mark M on a conveyed long-size paper 16a. A detection circuit 60 binarizes the output signal of the mark sensor 20 on the basis of a predetermined threshold. A control part 85 derives the passage timing of the central part of the mark from the binarized output signal on the basis of the detection timing of the end of the mark and decides the derived passage timing of the central part of the mark as the passage timing of the mark. The control part 85 specifies an image development timing by a drum/development device 31 on the basis of the decided passage timing of the mark and executes image development by the drum/development device 31 at the image development timing.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a mark position detection device, a mark position detection method, an image forming apparatus, and an image development control method.

  Conventionally, there is an electrophotographic image forming apparatus. In this image forming apparatus, the photosensitive drum of the developing device is uniformly charged and initialized, a latent image is formed on the photosensitive drum by optical writing, and the latent image is converted into a toner image (development). The toner image is directly or indirectly transferred to a printing medium and fixed by a fixing device.

  In the image forming apparatus, when an image is formed on a long paper as a printing medium or a label paper having a label affixed on a mount at a predetermined interval, the image forming apparatus has a predetermined interval (printing interval) on the printing medium. The position of the mark printed in advance, the position of the label, and the like are detected by an optical sensor arranged in the middle of the transport path of the printing medium, and a latent image is formed on the photosensitive drum (image) based on the detection timing. The timing of development is determined (see, for example, Patent Document 1).

JP 2014-198383 A

  In the above-described prior art, in the optical sensor, the amount of transmitted light (or reflected light) received by the light receiving unit gradually changes at the end of the mark or the end of the label. An output signal that changes to For this reason, the output signal of the optical sensor is binarized based on a predetermined threshold, and the mark position and the label position are discriminated based on the detection timing of the edge of the binarized output signal.

  However, since the mark position and label position determined in this way are determined based on the output signal that gradually changes at the mark or label end, the actual mark end or label end The detection timing of the part is not shown.

  Also, the distance of the optical sensor (light emitting unit, light receiving unit) from the printing medium, the degree of diffusion of the irradiated light, the color variation of the mark or printing medium, and the variation of the circuit parameters (threshold) during binarization Accordingly, the detection timing of the edge of the binarized output signal further varies.

  Therefore, in the prior art, an error occurs in the position of the mark or label (the end position of the mark or label), so that the image development timing for forming a latent image on the photosensitive drum and forming the toner image (development) is shifted. There was a problem that.

  Accordingly, an object of the present invention is to more accurately derive the position of a mark on a printing medium.

  A mark position detection apparatus according to the present invention includes a detection unit that detects a mark written on a print medium and having a predetermined length with respect to a conveyance direction, and an end portion of the mark detected by the detection unit. And determining means for determining the passage timing of the mark based on the detection timing.

  According to the mark position detection method of the present invention, a step of detecting a mark written on a print medium and having a predetermined length with respect to a transport direction by a sensor, and both ends of the mark detected by the sensor are detected. Determining the passage timing of the mark based on the detection timing.

  An image forming apparatus according to the present invention is an image forming apparatus including an image developing unit that develops an image to be formed on a printing medium, and is written on the printing medium and has a predetermined length with respect to a conveyance direction. Detection means for detecting a mark having, a determination means for determining the passage timing of the mark based on detection timings at both ends of the mark detected by the detection means, and a mark of the mark determined by the determination means A specifying unit that specifies an image development timing by the image developing unit based on a passage timing; and a control unit that executes image development by the image developing unit at the image development timing specified by the specifying unit. It is characterized by that.

  An image development control method according to the present invention is an image development control method for controlling the execution timing of image development by an image development unit provided in an image forming apparatus, which is written on a print medium and has a predetermined direction with respect to a conveyance direction. A step of detecting a mark having a length; a step of determining a passage timing of the mark based on a detection timing of both ends of the detected mark; and a step of determining the passage timing of the mark, A step of specifying an image development timing by the image development unit; and a step of executing an image development by the image development unit at the specified image development timing.

  According to this invention, the position of the mark on the printing medium can be derived more accurately.

1 is an overall conceptual diagram of an image forming apparatus 10 for printing on long paper (a printing medium) according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a mark sensor 20 and its detection circuit 60 of the image forming apparatus 10 according to the present embodiment. It is a conceptual diagram for demonstrating the correction method of the mark detection waveform of the image forming apparatus 10 by this embodiment. FIG. 2 is a block diagram illustrating a configuration of a control system 80 of the image forming apparatus 10 according to the present embodiment. 5 is a flowchart for explaining an operation (image development control process) of the image forming apparatus 10 according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A. Configuration of Embodiment FIG. 1 is an overall conceptual diagram of an image forming apparatus 10 for printing on long paper (a printing medium) according to an embodiment of the present invention. In the figure, the image forming apparatus 10 includes a long paper holding unit (paper feed roll holding unit) 15, a printer main body (image forming unit) 30, and a long paper winding unit (printing medium winding unit) 50. ing. The long paper holding unit 15 is installed in the lower part of the printer main body 30, and a paper feed roll 16 fitted to the unwinder shaft 28 is installed.

  More specifically, the paper feed roll 16 is made of a long paper (print medium) 16 a wound around a paper tube (winding core), and the paper tube (winding core) is fitted to the unwinder shaft 28. By doing so, it is installed in the long paper holder 15. The paper feed roll 16 is held rotatably about the unwinder shaft 28 as a rotation axis. The unwinder shaft 28 is not provided with a driving means (such as a motor), and is rotated when the long paper 16 a is pulled out from the paper feed roll 16 by the transport roller in the printer main body 30. The paper guide roller 17 changes the conveyance direction of the long paper (printed medium) 16 a drawn from the paper supply roll 16 and guides it to be conveyed toward the upper printer body 30.

  The edge sensor 18 is disposed between the paper guide roller 17 and a paper guide roller 19 to be described later, and detects the positions of both ends in the paper width direction perpendicular to the conveying direction of the long paper 16 a pulled out from the paper supply roll 16. To do. Although one end sensor 18 is shown in FIG. 1, as will be described later, it is disposed at each of both ends of the long paper 16a. In the present embodiment, the skew of the long paper 16a is detected from the positions of both ends of the long paper 16a detected by the end sensor 18 in the paper width direction.

  The paper guide roller 19 changes the transport direction of the long paper 16 a that has passed through the end sensor 18 and guides the transport to the upper printer body 30. The mark sensor 20 includes, for example, an optical sensor, and detects the mark M printed in advance on the long paper 16a from a change in the amount of transmitted light or reflected light with respect to the conveyed long paper 16a. In the following description, only the mark M will be described. However, in the case of a label paper in which the above-described label is affixed on the mount at a predetermined interval, or a printing medium in which holes are formed at a predetermined interval instead of the mark M Even so, it is the same.

  The paper transport rollers 21 and 23 sandwich the long paper 16 a fed from the paper feed roll 16 from both sides and transport it toward the upper printer body 30. Each of the sheet transport rollers 21 and 23 includes a clutch mechanism in at least one of the pair. When the clutch mechanism is turned on, the driving force of the rotating shaft is transmitted to the roller, and when it is turned off, the driving force from the rotating shaft is cut off and driven.

  At the start of printing, when the long paper 16a is transported into the printer main body 30 and is sandwiched between transport rollers in the printer main body 30 (main body entrance transport roller 47 described later), the driving force of the paper transport rollers 21 and 23 is applied. OFF (disengage the clutch). After the driving force of the paper transport rollers 21 and 23 is turned off, the long paper 16a is transported within the printer body 30 (main body entrance transport roller 47, secondary transfer backup roller 41 and secondary transfer roller 42 described later). , A roller in the fixing device 36). The paper transport rollers 21 and 23 are driven by the transported long paper 16a.

  The auto cutter 22 cuts the long paper 16a when the paper feed roll 16 is installed for the first time to feed the long paper 16a or when printing is completed. The paper passage sensor 24 detects the passage of the leading edge or the trailing edge of the long paper 16a conveyed to the printer main body 30.

  The unwinder 25 in which the paper feed roll 16 and the paper guide roller 17 are installed is configured on a separate frame in the long paper holding unit 15 and is configured to be movable in the paper width direction by slide bearings 26a and 26b. Has been. An actuator 27 that is expanded and contracted by, for example, electromagnetic force is disposed below the unwinder 25. When the actuator 27 expands and contracts, the unwinder 25 on the slide bearings 26a and 26b can be moved in the paper width direction.

  As described above, the long paper 16 a drawn from the paper feed roll 16 passes under the paper guide roller 17 from the unwinder 25 and passes through the paper guide roller 19, the paper transport roller 21, the auto cutter 22, and the paper transport roller 23. Then, the paper is fed to the printer main body 30.

  The printer main body 30 is an electrophotographic tandem color image forming apparatus of an intermediate transfer system, and includes a drum / developing device (image developing unit) 31, a transfer belt device 32, a toner cartridge 33, an electrical unit 34, and a paper feeding unit. 35, a fixing device 36, and the like.

  A toner cartridge 33 is disposed above the transfer belt device 32, and a drum / developing device 31 is disposed substantially immediately below the transfer belt device 32. The transfer belt device 32 includes an intermediate transfer belt 37, a driving roller 38, and a driven roller 39. The drum / developing device 31 is configured by contacting four lower developing devices 31k, 31c, 31m, and 31y in a multi-stage manner in contact with the lower running surface of the intermediate transfer belt 37 of the transfer belt device 32 from the right to the left in FIG. Is done.

  The developing devices 31k, 31c, 31m, and 31y include four toner cartridges 33, and black (K), cyan (C), magenta (M), and yellow (Y) indicated by K, C, M, and Y in FIG. ) Toner is supplied.

  The toner cartridge 33 is composed of four toner cartridges arranged above the upper running surface of the intermediate transfer belt 37. The four toner cartridges 33 contain black (K), cyan (C), magenta (M), and yellow (Y) supply toners, respectively. A toner vertical conveyance path 40 is disposed between the toner cartridge 33 and the drum / developing device 31, and a predetermined amount of toner is conveyed from the toner cartridge 33 into the drum / developing device 31.

  The developing device 31 includes four developing devices 31k, 31c, 31m, and 31y arranged in a multistage manner. Each of the developing devices 31k, 31c, 31m, and 31y has the same configuration except for the color of the toner that develops the image. Of the developing devices 31k, 31c, 31m, and 31y, the three upstream developing devices 31c, 31m, and 31y are cyan (C), magenta (M), and yellow (subtractive three primary colors), respectively. A color image of Y) color toner is formed on the intermediate transfer belt 37, and the developing device 31k generates a monochrome image of black (K) color toner mainly used for dark portions of characters and images on the intermediate transfer belt 37. To form.

  The transfer belt device 32 has an endless intermediate transfer belt 37 that extends in the shape of a flat loop in the left-right direction in the figure at the approximate center of the printer main body 30, and the intermediate transfer belt 37 is stretched over the intermediate transfer belt 37. A driving roller 38 and a driven roller 39 are provided to circulate and move the transfer belt 37 counterclockwise in the drawing.

  The transfer belt device 32 further includes a secondary transfer backup roller 41 over which an intermediate transfer belt 37 is stretched above the drive roller 38. A secondary transfer roller 42 is pressed against the secondary transfer backup roller 41 via an intermediate transfer belt 37.

  The long paper 16 a is pressed against the intermediate transfer belt 37 when being transported between the secondary transfer backup roller 41 and the secondary transfer roller 42. As a result, on the long paper 16a, a color image formed with the cyan (C), magenta (M), and yellow (Y) color toner and a monochrome image formed with the black (K) toner formed on the intermediate transfer belt 37 are formed. The images are sequentially transferred and supplied to the fixing device 36.

  The fixing device 36 is a belt-type heat fixing device, and fixes the toner image transferred to the long paper 16a. The long paper 16a carried out from the fixing device 36 is fitted to a rewinder shaft 52 of a long paper winding unit (rewinder) 50 via a face-up unit 45 including reversing guide rollers 45a and 45b. It is wound on a winding roll 51. The printer main body 30 can also feed and print a cut sheet (cut sheet) from the sheet feeding unit 35. Further, since the fixing device 36 has the strongest clamping force for clamping the long paper 16a in the printer main body 30, the conveyance speed in the fixing device 36 determines the overall conveyance speed of the long paper 16a. The fixing device 36 has a sufficient clamping force when printing cut paper (cut sheet paper) that is not wound.

  FIG. 2 is a circuit diagram showing the mark sensor 20 and the detection circuit 60 of the image forming apparatus 10 according to the present embodiment. In this embodiment, a transmission type mark sensor will be described. The mark sensor 20 includes a light emitting unit 55 and a light receiving unit 56. The long paper 16 a is conveyed between the light emitting unit 55 and the light receiving unit 56. Marks M are printed in advance on the long paper 16a at predetermined intervals. The light emitted from the light emitting unit 55 passes through the long paper 16 a and is received by the light receiving unit 56. The light receiving unit 56 outputs a detection signal S1 having a level corresponding to the amount of received light. That is, since the mark M functions to block light from the light emitting unit 55, the level of the detection signal S1 is high in the portion where the mark M is not present, and the level of the detection signal S1 is low in the portion where the mark M is present. . Details will be described later.

  The detection circuit 60 includes a comparator. The detection circuit 60 binarizes the detection signal S1 using the reference voltage 61 as a threshold value and converts it into a mark detection signal S2. That is, it is 1 when the detection signal S1 is equal to or smaller than the threshold value, and 0 when the detection signal S1 is larger than the threshold value (the level of the detection signal S1 is lowered at the mark M portion, and is inverted during digitization).

  FIG. 3 is a conceptual diagram for explaining the correction method of the mark detection waveform of the image forming apparatus 10 according to the present embodiment. 3 shows a long paper 16a and a mark M printed on the long paper 16a in advance at a predetermined interval. In the next row, an enlarged mark M is shown. The actual width of the mark M is represented by d. It can be said that the width d of the mark M has a predetermined length in the transport direction of the long paper 16a. As the long paper 16a moves in the direction of the arrow, the mark M gradually blocks light from the mark sensor 20. For this reason, as the detection signal S1 passes, the voltage value gradually decreases as the mark M passes, reaches the peak 71 of the waveform near the center, and the voltage value gradually increases. The direction in which the voltage value rises and falls, and the shape of the apex 71 differ depending on the sensor type (reflection type, transmission type) and circuit, but the shape of the waveform change is the same.

  When this detection signal S1 is binarized by the detection circuit 60, it becomes a mark detection signal S2. In this case, since the reference voltage 61 is binarized, the detection width 72 of the mark detection signal S2 is shorter than the actual width d of the mark M (the time during which the high level is “1” is shortened). That is, a deviation 73 occurs between the leading edge timing ts ′ (rising edge) of the mark detection signal S2 and the leading edge of the mark M.

  Since the image output timing in the drum / developing device 31 has been determined based on the mark detection signal S2, the error in the mark detection signal S2 remains as it is. A deviation in generation timing, that is, a positional deviation of the image with respect to the long paper 16a at the secondary transfer position (the position of the secondary transfer roller 42).

  Since the detection signal S1 of the mark sensor 20 is symmetrical as long as the transport speed of the long paper 16a is constant, the leading edge timing ts ′ (rising edge) and the trailing edge timing te ′ of the waveform of the mark detection signal S2 ( The center position 74 (mark center timing tc) of the mark detection signal S2 is exactly the center position of the actual mark M. Accordingly, in the mark detection signal S2 binarized with a constant threshold voltage, the mark is a half (1/2) of the time from the rising edge to the falling edge, that is, the center of the leading edge timing ts ′ and the trailing edge timing te ′. The center timing tc is always the center position of the mark M.

  Therefore, in the present embodiment, the mark detection signal S2 is utilized by utilizing the fact that half (1/2) of the time between the leading end timing ts ′ and the trailing end timing te ′ is the actual center position of the mark M. If the width d of M is measured in advance and given as fixed information (the width (length) of the mark M), the width d of the mark M passes if the conveyance speed (linear velocity) of the long paper 16a is known. The passage time required for the mark M can be derived), and the place where the time is traced back by 1/2 of the width d of the mark M from the central position 74 of the mark detection signal S2 can be derived as the accurate mark tip timing ts of the mark M. it can.

  In the present embodiment, the accurate mark leading edge timing ts of the mark M is derived by the above-described method, and the image development start timing in the drum / developing device 31 is determined based on the accurate mark leading edge timing ts of the mark M. As a result, a more accurate image position control method is realized.

  More specifically, the time corresponding to the difference between the distance from the mark sensor 20 to the secondary transfer roller 42 and the distance from the drum / developing device 31 (photosensitive drum) to the secondary transfer roller 42 is taken into consideration. Then, the image development start timing in the drum / developing device 31 is determined. As a result, an image can be accurately formed at a predetermined position on the long paper 16a.

  FIG. 4 is a block diagram illustrating a partial configuration of the control system 80 of the image forming apparatus 10 according to the present embodiment. It should be noted that portions corresponding to those in FIG. In FIG. 4, the control system 80 of the image forming apparatus 10 includes the mark sensor 20 described above, the detection circuit (comparator) 60 described above, the drum / developer 31 described above, the memory 81, the operation panel 82, and the intermediate transfer belt drive unit 83. , A conveyance roller driving unit 84, and a control unit 85.

  The memory 81 includes a RAM, a ROM, and the like, and stores programs executed by the CPU constituting the control unit 85, various parameters, and the like. In particular, in the present embodiment, the memory 81 temporarily stores an arithmetic value for deriving the mark leading edge timing ts of the mark M described above.

  The operation panel 82 inputs information related to printing such as printing start, the number of prints, and operation instructions. In particular, in the present embodiment, the operation panel 82 displays the type of the long paper 16a (plain paper thick paper / thin paper manufactured using pulp as a main raw material, synthetic paper using plastic as a raw material, backing paper and printing medium, and adhesive. Label paper made of an agent), the width d of the mark M, and the like. However, when the type or the width d of the mark M is printed at a predetermined position of the paper feed roll 16 by using a barcode or the like, it is input using a barcode reader or the like instead of the operation panel 82. Also good.

  The intermediate transfer belt drive unit 83 drives the intermediate transfer belt 37 at a predetermined timing based on the leading edge detection timing of the derived mark M under the control of the control unit 85. The conveyance roller drive unit 84 drives the sheet conveyance rollers 21 and 23, the main body entry conveyance roller 47, the secondary transfer backup roller 41 and the secondary transfer roller 42, rollers in the fixing device 36, and the like under the control of the control unit 85. To do.

  The control unit 85 includes a CPU and the like, and controls the operation of the image forming apparatus 10 by executing the program. In particular, in the present embodiment, the control unit 85 monitors the mark detection signal S2 supplied from the detection circuit 60, and the leading edge timing ts ′ related to the rising edge of the mark detection signal S2 and the trailing edge timing te related to the falling edge. The center (1/2) of the mark M is derived as the mark center timing ts of the mark M, and further, the mark tip timing ts which is the correct tip detection timing of the mark M based on the width d of the mark M from the mark center timing tc. Is derived.

  Further, the control unit 85 drives the drum / developing device 31 to start developing the toner image at the image development start timing specified from the position of the mark M (mark leading edge timing ts), and the intermediate transfer belt driving unit. 83, the intermediate transfer belt 37 is driven, and various conveying rollers by the conveying roller driving unit 84 (clutch mechanism / driving of the sheet conveying rollers 21, 23, the main body entering conveying roller 47, the secondary transfer backup roller 41, and the secondary transfer roller 42). The roller in the fixing device 36) is controlled to perform secondary transfer of the toner image onto the long paper 16a at the secondary transfer position (secondary transfer roller 42) and fixing in the fixing device 36. To do.

B. Operation of Embodiment Next, the operation of this embodiment will be described.
FIG. 5 is a flowchart for explaining the operation (image development control process) of the image forming apparatus 10 according to the present embodiment. The user attaches the paper feed roll 16 made of the long paper 16 a to the long paper holding unit 15, pulls out the long paper 16 a from the paper feed roll 16, and sets it so as to be sandwiched between the paper transport rollers 21.

  The control unit 85 controls the various conveying rollers (clutch mechanism / drive of the sheet conveying rollers 21 and 23, the main body entering conveying roller 47, the secondary transfer backup roller 41, the secondary transfer roller 42, and the fixing device 36) by the conveying roller driving unit 84. And the like are driven (step S10).

  Until the transport of the long paper 16a is started by the paper transport rollers 21 and 23, the long paper 16a is loosened between the paper feed roll 16 and the paper guide rollers 17 and 19, and load tension is generated. Not done. Then, when the conveyance is started by the sheet conveyance roller 21 and the slack of the long paper 16a is eliminated, a load tension is generated on the long paper 16a, and a rotational driving force is applied to the paper feed roll 16 and the unwinder shaft 28. Then, the rotating operation is started while being pulled from the stationary state to the long paper 16a.

  The mark sensor 20 detects the mark M on the conveyed long paper 16a and supplies a detection signal S1 to the detection circuit 60. The detection circuit 60 binarizes the detection signal S1 with the reference voltage 61 as a threshold value, converts it into a mark detection signal S2, and supplies it to the control unit 85.

  Next, the control unit 85 monitors the mark detection signal S2, and determines whether or not the mark M is detected, that is, whether or not the mark detection signal S2 = 1 (rising edge) is detected (step S12). . If the mark M is not detected (NO in step S12), the control unit 85 repeats step S12 until the mark M is detected, that is, until the rising edge is detected. Continue monitoring.

  When the mark M is detected, that is, when a rising edge is detected (YES in step S12), the control unit 85 stores the detection timing in the memory 81 as the tip timing ts ′ (see FIG. 3). Store (step S14). In the present embodiment, the rising edge detection timing is the leading edge timing ts'. However, in the case of negative logic, the rising edge detection timing is used. Therefore, the detection timing of the first edge may be set as the leading edge timing ts ′.

  Next, the control unit 85 determines whether or not the mark M is detected, that is, whether or not the mark detection signal S2 = 0 (falling edge) is detected (step S16). If no mark M is detected (NO in step S16), the control unit 85 repeats step S16 until the mark M is detected, that is, until a rising edge is detected. Continue monitoring S2.

  When no mark M is detected, that is, when a falling edge is detected (YES in step S16), the control unit 85 sets the detection timing as the rear end timing te ′ (see FIG. 3). Store in the memory 81 (step S18). In this embodiment, the falling edge detection timing is set to the trailing edge timing te '. However, as described above, in the case of negative logic, the rising edge detection timing is set. Therefore, the detection timing of the next edge following the first edge may be set as the rear end timing te ′.

  Next, the control unit 85 sets the center (1/2) of the leading edge timing ts 'and the trailing edge timing te' as the mark center timing tc (see FIG. 3) of the mark M (step S20). Next, the control unit 85 sets the timing before ½ of the width d of the mark M from the mark center timing tc as a new mark leading edge timing ts that is the correct leading edge detection timing of the mark M (step S22).

  Next, the control unit 85 waits until the image development start timing specified from the position of the mark M (mark leading edge timing ts) (step S24). More specifically, the control unit 85 responds to the difference between the distance from the mark sensor 20 to the secondary transfer roller 42 and the distance from the drum / developing device 31 (photosensitive drum) to the secondary transfer roller 42. Wait for time. In other words, the distance from the mark sensor 20 to the secondary transfer roller 42 (first distance) and the distance from the drum / developing device 31 (photosensitive drum) to the secondary transfer roller 42 (second distance). The timing at which the time corresponding to the difference (first distance> second distance) is added to the new mark tip timing ts is set as the image development start timing in the drum / developing device 31 (photosensitive drum).

  Then, when the image development start timing specified from the position of the mark M (mark tip timing ts) is reached, the control unit 85 drives the drum / developing device 31 to start image output (step S26). More specifically, the control unit 85 starts driving of the intermediate transfer belt 37 by the intermediate transfer belt driving unit 83 at the start of image output. As a result, the toner image primarily transferred to the intermediate transfer belt 37 and the print area indicated by the mark M detected by the mark sensor 20 reach the secondary transfer position (secondary transfer roller 42) at the same timing. Therefore, the toner image is secondarily transferred to a predetermined position on the long paper 16a.

  Next, the control unit 85 determines whether or not the printing has been completed (step S28). If the printing has not been completed (NO in step S28), the control unit 85 returns to step S12 and applies to the next mark M. The above process is repeated. In this way, printing is continuously performed on the long paper 16a.

  As a result, the mark sensor 20 detects the position of the mark M (front end timing ts ′ and rear end timing te ′) every time the mark M printed on the conveyed long paper 16a passes at a predetermined interval. Then, the accurate position of the mark M (mark tip timing ts) is derived from the center position of the mark M derived from these (mark center timing tc) and the width d of the mark M, and the accurate position of the mark M (mark tip timing). The drum / developing device 31 starts outputting an image at the image development start timing specified based on ts), and the toner image is placed at a predetermined position on the long paper 16a at the secondary transfer position (secondary transfer roller 42). Is secondarily transferred.

  On the other hand, when printing is completed (YES in step S28), the control unit 85 drives the auto cutter 22 at a predetermined timing to cut the long paper 16a, and further, at a predetermined timing, the long paper 16a. Is stopped (step S30). Thereafter, the control unit 85 ends the process.

  In the above-described embodiment, the position of the mark M (mark leading edge timing ts) is derived, and the image development start timing is determined based on the mark leading edge timing ts. However, the present invention is not limited to this and is derived in step S20. The image development start timing may be determined directly from the mark center timing tc indicating the center position of the mark M.

  In the above-described embodiment, a detection period (detection window) for detecting the position of the next mark M is set based on the derived mark center timing, and the mark M is detected in this detection period. May be. Further, in the case of roll paper in which labels that have been cut in advance on the mount are pasted at predetermined intervals, the detection period may be set to the gap between the labels. The same applies to the case of multiple slips in which holes are formed at predetermined intervals on both ends of the printing medium. Thus, noise detection can be prevented by setting a detection period (detection window) for detecting the position of the mark M.

  According to the above-described embodiment, the mark M that is printed in advance on the transported long paper 16a and has a predetermined length (width) in the transport direction is detected by the mark sensor 20, and the detection circuit 60 detects the mark M. The binarization is performed based on a predetermined threshold (reference voltage 61), and the mark center timing of the mark M is determined based on the leading end timing ts ′ and the trailing end timing te ′ of the mark M of the binarized mark detection signal S2. Since tc is derived and the mark center timing tc of the derived mark M is determined as the passing timing of the mark M, the error when binarized and the distance of the mark sensor 20 from the long paper 16a Even if there is a degree of diffusion of irradiated light, a variation in the color of the mark M or the long paper 16a, or a variation in circuit parameters at the time of binarization, the position of the mark M can be derived more accurately. Door can be.

  Further, according to the above-described embodiment, the detection timing of the first edge from the mark detection signal S2 binarized by the control unit 85 is set as the leading edge timing ts ′, and the detection timing of the next edge following the first edge is detected. Is the rear end timing te ′, and the center of the front end timing ts ′ and the rear end timing te ′ is derived as the mark center timing tc of the mark, so that the position of the mark M can be derived more accurately. Can do.

  Further, according to the above-described embodiment, the mark center timing tc of the mark M is determined as the passing timing of the mark M, and the image developing timing by the drum / developing device 31 is determined based on the determined passing timing of the mark M. Since the image development is executed by the drum / developing device 31 at the specified image development timing, the toner image can be secondarily transferred to an accurate position of the long paper 16a.

As mentioned above, although several embodiment of this invention was described, this invention is not limited to these, The invention described in the claim, and its equal range are included.
Below, the invention described in the claims of the present application is appended.

(Appendix 1)
The invention according to appendix 1 includes detection means for detecting a mark written on a print medium and having a predetermined length with respect to the transport direction, and detection timings of both ends of the mark detected by the detection means And a determination means for determining the passage timing of the mark based on the mark position detection device.

(Appendix 2)
According to the second aspect of the present invention, the detecting unit receives a light emitting unit that emits light, and light that is emitted from the light emitting unit and transmitted or reflected by the printing medium, and an output signal corresponding to the received light amount The mark position detection apparatus according to appendix 1, further comprising: a light receiving unit that outputs a signal and a detection circuit that binarizes an output signal output from the light receiving unit based on a predetermined threshold.

(Appendix 3)
According to the third aspect of the invention, from the output signal binarized by the detection circuit, the detection timing of the first edge is the leading edge timing, the detection timing of the next edge following the first edge is the trailing edge timing, Derivation means for deriving the center of the front end timing and the rear end timing as the passage timing of the central portion of the mark;
The mark position detection apparatus according to appendix 2, wherein the determining means determines the passage timing of the central portion of the mark derived by the deriving means as the passage timing of the mark.

(Appendix 4)
The invention according to appendix 4 further includes setting means for setting a detection period for detecting the position of the next mark based on the passage timing of the mark determined by the determination means, and the detection means includes: The mark position detection device according to any one of appendices 1 to 3, wherein the next mark is detected in the detection period.

(Appendix 5)
The invention according to appendix 5 is characterized in that the setting means sets the detection period between the labels when using a roll paper in which a label cut in advance on a mount is attached as the printing medium. It is a mark position detection apparatus as described in appendix 4.

(Appendix 6)
The invention according to appendix 6 includes a step of detecting by a sensor a mark written on the print medium and having a predetermined length in the transport direction, and detection timing of both ends of the mark detected by the sensor. And a step of determining the mark passage timing based on the mark position detection method.

(Appendix 7)
In the invention according to appendix 7, in the step of detecting the mark, the light emitted from the light emitting unit and transmitted or reflected by the printing medium is received, and an output signal corresponding to the received light amount is set to a predetermined threshold value. 7. The mark position detection method according to appendix 6, wherein binarization is performed based on the output.

(Appendix 8)
In the invention according to appendix 8, from the binarized output signal, the detection timing of the first edge is set as the leading edge timing, the detection timing of the next edge following the first edge is set as the trailing edge timing, and the leading edge timing and Deriving the center of the rear end timing as the passage timing of the central portion of the mark, and the step of determining determines the passage timing of the central portion of the mark as the passage timing of the mark, The mark position detection method according to appendix 7.

(Appendix 9)
The invention according to appendix 9 is an image forming apparatus including an image developing unit that develops an image to be formed on a printing medium, and is written on the printing medium and has a predetermined length with respect to a conveyance direction. Detection means for detecting a mark, determination means for determining the passage timing of the mark based on detection timings at both ends of the mark detected by the detection means, and passage of the mark determined by the determination means A specifying unit that specifies an image development timing by the image developing unit based on the timing; and a control unit that executes image development by the image developing unit at the image development timing specified by the specifying unit. An image forming apparatus characterized by the above.

(Appendix 10)
The invention according to appendix 10 is characterized in that the detection means receives a light emitting unit that emits light, and light emitted from the light emitting unit and transmitted or reflected by the printing medium, and an output signal corresponding to the received light amount The image forming apparatus according to appendix 9, further comprising: a light receiving unit that outputs a signal and a detection circuit that binarizes an output signal output from the light receiving unit based on a predetermined threshold.

(Appendix 11)
In the invention according to attachment 11, the detection timing of the first edge from the output signal binarized by the detection circuit is a leading edge timing, the detection timing of the next edge following the first edge is a trailing edge timing, Derivation means for deriving the center of the leading edge timing and the trailing edge timing as the passage timing of the central portion of the mark, and the deciding means determines the passage timing of the central portion of the mark derived by the derivation means. The image forming apparatus according to appendix 10, wherein the image forming apparatus determines the passage timing.

(Appendix 12)
The invention according to attachment 12 is characterized in that the specifying unit includes a distance from the light receiving unit to a transfer position at which the image formed by the image developing unit is transferred to the printing medium, and a distance from the image developing unit to the transfer position. 12. The image forming apparatus according to appendix 10 or 11, wherein a time corresponding to a difference from the distance is added to a timing of passing the mark as the image development timing by the image developing unit. .

(Appendix 13)
The invention according to appendix 13 is an image development control method for controlling the execution timing of image development by an image development unit provided in an image forming apparatus, which is written on a print medium and has a predetermined length with respect to the transport direction. Detecting a mark having a mark, determining a passage timing of the mark based on detection timings of both ends of the detected mark, and determining the image based on the determined passage timing of the mark An image development control method comprising: specifying an image development timing by a development unit; and executing image development by the image development unit at the specified image development timing.

10 Image forming apparatus 15 Long paper holder (paper feed roll holder)
16 Paper feed roll 16a Long paper (print medium)
17, 19 Paper guide roller 20 Mark sensor 21, 23 Paper transport roller 22 Auto cutter 24 Paper passage sensor 25 Unwinder 26a, 26b Slide bearing 27 Actuator 28 Unwind shaft 30 Printer body (image forming unit)
31, 31k, 31c, 31m, 31y Drum and developing device (image developing unit)
32 Transfer Belt Device 33 Toner Cartridge 34 Electrical Unit 35 Paper Feeding Unit 36 Fixing Device 37 Intermediate Transfer Belt 38 Drive Roller 39 Followed Roller 40 Toner Vertical Transport Path 41 Secondary Transfer Backup Roller 42 Secondary Transfer Roller 45 Face Up Units 45a and 45b Reversing guide roller 47 Main body entrance conveying roller 50 Long paper take-up section (rewinder, print medium take-up device)
51 Winding roll 52 Rewinder shaft (winding shaft)
55 Light Emitting Unit 56 Light Receiving Unit 60 Detection Circuit (Comparator)
61 Reference voltage (threshold)
S1 detection signal S2 mark detection signal 80 control system 81 memory 82 operation panel 83 intermediate transfer belt drive unit 84 transport roller drive unit 85 control unit

Claims (13)

Detection means for detecting a mark written on the print medium and having a predetermined length in the transport direction;
Determination means for determining the passage timing of the mark based on the detection timing of both ends of the mark detected by the detection means;
A mark position detection apparatus comprising: The detection means includes
A light emitting unit for emitting light;
A light receiving unit that receives light emitted from the light emitting unit and transmitted or reflected by the printing medium, and outputs an output signal corresponding to the received light amount;
A detection circuit that binarizes an output signal output from the light receiving unit based on a predetermined threshold;
The mark position detection apparatus according to claim 1, further comprising: From the output signal binarized by the detection circuit, the detection timing of the first edge is the leading edge timing, the detection timing of the next edge following the first edge is the trailing edge timing, and the leading edge timing and the trailing edge timing are Derivation means for deriving the center as the passage timing of the central portion of the mark,
The determining means includes
Determining the passage timing of the center of the mark derived by the deriving means as the passage timing of the mark;
The mark position detection apparatus according to claim 2, wherein Further comprising setting means for setting a detection period for detecting the position of the next mark based on the passage timing of the mark determined by the determining means;
The detection means detects the next mark in the detection period;
The mark position detection apparatus according to claim 1, wherein the mark position detection apparatus is a mark position detection apparatus. The setting means sets the detection period between the labels when using roll paper in which a label that has been cut in advance on a mount is used as the printing medium,
The mark position detection apparatus according to claim 4, wherein Detecting a mark written on the print medium and having a predetermined length in the transport direction by a sensor;
Determining the passage timing of the mark based on the detection timing of both ends of the mark detected by the sensor;
A mark position detection method comprising: Detecting the mark comprises:
Receiving light emitted from the light emitting unit and transmitted or reflected by the print medium, and outputting an output signal corresponding to the received light amount based on a predetermined threshold value;
The mark position detection method according to claim 6. From the binarized output signal, the detection timing of the first edge is the leading edge timing, the detection timing of the next edge following the first edge is the trailing edge timing, and the center of the leading edge timing and the trailing edge timing is the center Including the step of deriving as the passage timing of the central portion of the mark,
The determining step includes:
Determining the passage timing of the center of the mark as the passage timing of the mark;
The mark position detection method according to claim 7, wherein: An image forming apparatus including an image developing unit that develops an image to be formed on a printing medium,
Detection means for detecting a mark written on the print medium and having a predetermined length in the transport direction;
Determination means for determining the passage timing of the mark based on the detection timing of both ends of the mark detected by the detection means;
Specifying means for specifying the image development timing by the image developing unit based on the passage timing of the mark determined by the determining means;
Control means for executing image development by the image developing section at the image development timing specified by the specifying means;
An image forming apparatus comprising: The detection means includes
A light emitting unit for emitting light;
A light receiving unit that receives light emitted from the light emitting unit and transmitted or reflected by the printing medium, and outputs an output signal corresponding to the received light amount;
A detection circuit that binarizes an output signal output from the light receiving unit based on a predetermined threshold;
The image forming apparatus according to claim 9, further comprising: From the output signal binarized by the detection circuit, the detection timing of the first edge is the leading edge timing, the detection timing of the next edge following the first edge is the trailing edge timing, and the leading edge timing and the trailing edge timing are Derivation means for deriving the center as the passage timing of the central portion of the mark,
The determining means includes
Determining the passage timing of the center of the mark derived by the deriving means as the passage timing of the mark;
The image forming apparatus according to claim 10. The specifying means is:
The time corresponding to the difference between the distance from the light receiving unit to the transfer position at which the image formed by the image developing unit is transferred to the printing medium and the distance from the image developing unit to the transfer position is expressed as the mark. The timing added to the passage timing is the image development timing by the image development unit,
The image forming apparatus according to claim 10, wherein the image forming apparatus is an image forming apparatus. An image development control method for controlling execution timing of image development by an image development unit provided in an image forming apparatus,
Detecting a mark written on the print medium and having a predetermined length in the transport direction;
Determining the passage timing of the mark based on the detection timing of both ends of the detected mark;
Identifying an image development timing by the image development unit based on the determined passage timing of the mark;
Executing image development by the image development unit at the specified image development timing;
An image development control method comprising:

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