JP2017125950A - Image formation system, image formation apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation system, an image formation apparatus and a program which can accurately align the position of an image already formed on a long sheet and the position of an image to be formed on the long sheet from now on.SOLUTION: An image formation apparatus 1B includes an image formation unit 40 and a control unit 80. The control unit 80 includes: a detection part 811 which detects the speed variation amount of the conveyance speed of a long sheet T; a calculation part 812 which calculates the image arrival time from detection of a first image formed on the long sheet T to arrival to a transfer position of an intermediate transfer belt 421 on the basis of the speed variation amount; and a timing control part 813 which controls the writing timing for starting writing of a second image by the toner image to be formed in accordance with the first image when the toner image arrival time to arrival of the toner image of a photoreceptor drum 413 transferred to the intermediate transfer belt 421 to the transfer position is made to match the image arrival time.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming system, an image forming apparatus, and a program.

  Conventionally, when an image forming system forms an image on a sheet while conveying the sheet, an image may not be formed at a preset position depending on the sheet conveyance environment.

  For example, if the conveyance rollers for conveying the paper are eccentric, the paper conveyance speed is not constant. In this case, a registration mark is formed in advance on a sheet, and the image forming timing in the sub-scanning direction of the sheet is corrected based on the measurement pitch of the registration mark and the ideal pitch (for example, Patent Documents). 1).

  Further, for example, even when the paper is deformed, a reference image is formed in advance on each of the front and back surfaces of the paper, and the paper is determined based on the reference position of the paper and the reference image formed on the paper. There has been proposed one that corrects the position of an image formed on the back surface of the image (for example, see Patent Document 2).

  Further, for example, depending on the paper conveyance path or the paper conveyance state, the paper conveyance time until the paper reaches the transfer position varies. In this case, there has been proposed one that corrects the timing for writing an image based on the conveyance speed of the sheet from the paper feed sensor to the paper discharge sensor and a preset conveyance speed (for example, Patent Documents). 3).

  Further, for example, depending on the state of the paper such as the thickness, material, and curl state of the paper, there is a variation in the paper transport time until the paper reaches the transfer position. In this case, the actual transport time from when the writing reference sensor detects the leading edge of the paper to when the registration sensor detects the leading edge of the paper, and after the writing reference sensor detects the leading edge of the paper, There has been proposed one that corrects the time until the sheet reaches the transfer position based on the maximum allowable time required until the leading edge is detected (see, for example, Patent Document 4).

JP 2003- 211770 A JP 2014-232141 A JP 2003-345215 A JP 2003-12197 A

  However, the conventional techniques as described in Patent Documents 1 to 4 form an image at a preset position according to the paper transport environment, but the paper transport speed may change.

  Therefore, as in the prior art described in Patent Document 1, even if the image formation timing in the sub-scanning direction of the paper is corrected based on the registration mark measurement pitch and the ideal pitch, the paper conveyance speed changes. There is a risk that it cannot respond.

  Further, as in the prior art described in Patent Document 2, even if the position of the image formed on the back surface of the sheet is corrected based on the reference position of the sheet and the reference image formed on the sheet, the sheet is conveyed. There is a possibility that it cannot respond to the change in speed.

  Further, as in the prior art described in Patent Document 3, the timing for writing an image is corrected based on the conveyance speed of a sheet from the paper feed sensor to the paper discharge sensor and a preset conveyance speed. However, there is a possibility that it cannot cope with a change in the paper conveyance speed.

  Further, as in the prior art described in Patent Document 4, even if the time required for the paper to reach the transfer position is corrected based on the actual paper required time and the maximum allowable time for the paper, the paper May not be able to cope with changes in the transport speed. The same applies to long paper.

  Therefore, in the conventional techniques as described in Patent Documents 1 to 4, when there is variation in the conveyance speed of paper, particularly long paper, the position of the image already formed on the long paper and the long paper from now on There is a possibility that the position of the image to be formed cannot be accurately adjusted.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide an image that has already been formed on a long paper even though the conveyance speed of the long paper varies. It is an object of the present invention to provide an image forming system, an image forming apparatus, and a program that can accurately match the position of the image and the position of an image to be formed on a long sheet from now on.

  In order to achieve the above object, an image forming system according to the present invention includes a paper feeding device, an image forming device that forms an image on a long sheet fed from the paper feeding device, and the image forming device that provides the image. An image forming system including a winding device that winds the long paper on which the paper is formed, the image forming device forming an image on the long paper by an intermediate transfer belt, A control unit that controls the image forming unit, and the control unit detects a speed fluctuation amount of the transport speed of the long paper, and based on the speed fluctuation amount detected by the detection unit, A calculation unit that calculates an image arrival time from when the first image formed on the long paper is detected to the transfer position of the intermediate transfer belt, and the image arrival time calculated by the calculation unit The intermediate transfer plate When the toner image arrival time until the toner image on the photosensitive drum transferred to the transfer position reaches the transfer position is matched, the writing of the second image by the toner image formed in accordance with the first image is started. And a timing control unit for controlling the write start timing.

  According to this image forming system, the position of the image already formed on the long paper and the position of the image to be formed on the long paper from now on, despite the variation in the conveyance speed of the long paper, Can be adjusted with high accuracy.

  In the image forming system according to the present invention, the image forming system further includes a position detection sensor that detects a plurality of position marks formed on the long paper at a constant pitch, and the detection unit detects the position detected by the position detection sensor. It is preferable that the speed fluctuation amount is detected based on a position mark detection cycle.

  According to this image forming system, the timing at which the toner image of the image written on the long paper reaches the transfer position can be accurately obtained.

  The image forming system according to the present invention further includes an acceleration sensor that detects an acceleration of the long paper, and the detection unit detects the speed according to the acceleration of the long paper detected by the acceleration sensor. It is preferable to detect the fluctuation amount.

  According to this image forming system, the timing at which the toner image of the image written on the long paper reaches the transfer position can be accurately obtained.

  In the image forming system according to the present invention, the image forming system further includes a rotary encoder that detects a rotational displacement of a driven roller that rotates as the long paper is conveyed, and the detection unit detects the rotation detected by the rotary encoder. It is preferable to detect the speed fluctuation amount based on the rotational displacement.

  According to this image forming system, the timing at which the toner image of the image written on the long paper reaches the transfer position can be accurately obtained.

  In the image forming system according to the present invention, when the detection unit is instructed to form the second image on the long paper, the second image is formed on the long paper. It is preferable to detect the speed fluctuation amount before starting.

  According to this image forming system, it is possible to accurately determine the writing timing for starting the writing of an image.

  The image forming system according to the present invention may further include an image detection sensor that detects the passage of the first image as the long paper is conveyed, and the detection unit includes the first paper on the long paper. While the two images are formed, the speed fluctuation amount before the passage of the first image is detected by the image detection sensor, and the passage of the first image is detected by the image detection sensor. If the speed fluctuation amount after the change is different, it is preferable to update the speed fluctuation amount to the latest one.

  According to this image forming system, it is possible to match the writing start timing for starting image writing with the current paper transport environment.

  The image forming system according to the present invention may further include an image processing unit that performs processing related to the image, and the image processing unit is configured to write the second image that is formed in accordance with the first image. When started, it is preferable that the position of the second image formed on the long paper is corrected in accordance with a deviation along the transport direction of the long paper based on the speed fluctuation amount.

  According to this image forming system, the position of the image already formed on the long paper and the position of the image to be formed on the long paper can be matched particularly remarkably accurately.

  In order to achieve the above object, an image forming apparatus according to the present invention includes an image forming unit that forms an image on a long sheet using an intermediate transfer belt, and a control unit that controls the image forming unit. A detection unit that detects a speed fluctuation amount of the transport speed of the long paper, and the first image formed on the long paper is detected based on the speed fluctuation amount detected by the detection unit. A calculation unit that calculates an image arrival time from the intermediate transfer belt to the transfer position of the intermediate transfer belt, and a toner image on the photosensitive drum transferred to the intermediate transfer belt at the image arrival time calculated by the calculation unit. When adjusting the arrival time of the toner image until reaching the transfer position, a timing for controlling the writing start timing for starting the writing of the second image by the toner image formed in accordance with the first image. And a timing controller.

  According to this image forming apparatus, as in the above image forming system, the position of the image already formed on the long paper and the long paper from now on, even though the transport speed of the long paper varies. The position of the image to be formed can be accurately matched.

  In order to achieve the above object, a program according to the present invention causes a computer to detect a speed fluctuation amount of a conveyance speed of a long paper, and the long time based on the speed fluctuation amount detected by the detection part. A calculation unit that calculates an image arrival time from when the first image formed on the paper is detected until the transfer position of the intermediate transfer belt is reached, and the image arrival time calculated by the calculation unit, When the toner image arrival time until the toner image on the photosensitive drum transferred to the intermediate transfer belt reaches the transfer position is adjusted, writing of the second image by the toner image formed in accordance with the first image is started. And function as a timing control unit for controlling the writing start timing.

  According to this program, as in the image forming system, the position of the image already formed on the long paper, and the paper to be formed on the long paper from now on, even though the transport speed of the long paper varies. The position of the image can be accurately adjusted.

  According to the present invention, the position of the image already formed on the long paper and the position of the image to be formed on the long paper from now on despite the variation in the transport speed of the long paper are accurately determined. Can be matched.

1 is a diagram illustrating an example of an overall configuration of an image forming system 1 according to Embodiment 1. FIG. 2 is a diagram illustrating an example of an internal configuration of an image forming apparatus 1B according to Embodiment 1. FIG. 3 is a diagram illustrating a positional relationship between a position detection sensor 31 and a long paper T according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a lower image 901 and a position mark 903 formed on a long paper T according to Embodiment 1. FIG. FIG. 5 is a diagram illustrating an example of variation in the conveyance speed of the long paper T according to the first embodiment. 3 is a block diagram illustrating an example of a functional configuration of an image forming apparatus 1B according to Embodiment 1. FIG. 5 is a flowchart illustrating a control example of a control unit 80 according to the first embodiment. 6 is a flowchart illustrating details of a conveyance speed detection process according to the first embodiment. 10 is a flowchart for explaining a control example of a control unit 80 according to the second embodiment. 10 is a flowchart illustrating details of image data correction processing according to the second embodiment. FIG. 10 is a diagram illustrating the position of an unformed image 902 that is corrected by image data correction processing according to the second embodiment. FIG. 10 is a block diagram illustrating an example of a functional configuration of an image forming apparatus 1B according to Embodiment 3. FIG. 10 is a block diagram illustrating an example of a functional configuration of an image forming apparatus 1B according to a fourth embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

Embodiment 1. FIG.
FIG. 1 is a diagram illustrating an example of the overall configuration of an image forming system 1 according to the first embodiment. As shown in FIG. 1, the image forming system 1 includes a paper feeding device 1A, an image forming device 1B, and a winding device 1C.

  The paper feeding device 1A feeds the long paper T to the image forming device 1B. Specifically, the paper feeding device 1A accommodates long paper T such as roll paper or continuous paper. Therefore, the paper feeding device 1A can feed the long paper T to the image forming device 1B based on an instruction from the image forming device 1B.

  Although details will be described later, the image forming apparatus 1B forms an image on the long paper T fed from the paper feeding device 1A and sends the image to the winding device 1C. In the image forming apparatus 1B, when the long paper T is fed from the paper feeding device 1A, the position detection sensor 31 detects the position mark 903 formed on the long paper T.

  The winding device 1C winds the long paper T sent from the image forming device 1B. An image is formed on the long paper T taken up by the take-up device 1C by the image forming device 1B.

  Next, the image forming apparatus 1B will be specifically described. FIG. 2 is a diagram illustrating an example of an internal configuration of the image forming apparatus 1B according to the first embodiment. As shown in FIG. 2, the image forming apparatus 1B is an apparatus that uses electrophotographic process technology.

  Specifically, in the image forming apparatus 1B, the photosensitive drum 413 corresponding to four colors of Y (yellow), M (magenta), C (cyan), and K (black) is used in the traveling direction (vertical) of the intermediate transfer belt 421. Direction). The image forming apparatus 1 </ b> B employs a vertical tandem system in which each color toner image is sequentially transferred to the intermediate transfer belt 421.

  Although details will be described later, the image forming apparatus 1B primarily transfers the YMCK color toner images formed on the photosensitive drum 413 to the intermediate transfer belt 421. The image forming apparatus 1 </ b> B forms an image on the long paper T by superimposing the four color toner images on the intermediate transfer belt 421, secondarily transferring and fixing the toner images on the long paper T.

  In the image forming apparatus 1B, the image processing unit 30 forms image data in accordance with the operation content from the operation display unit 20. In the image forming apparatus 1B, based on the image data formed by the image processing unit 30, the image forming unit 40 forms a color image by an intermediate transfer method.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as the display unit 21 and the operation unit 22.

  The display unit 21 displays various operation screens, operation states of functions, and the like based on a display control signal input from the control unit 80. The operation unit 22 includes various operation keys such as a numeric keypad and a start key. The operation unit 22 outputs an operation signal to the control unit 80 by accepting various input operations by the user. The user can perform image quality setting by operating the operation display unit 20. Further, the user can perform settings relating to image formation such as magnification setting, application setting, output setting, and paper setting by operating the operation display unit 20. Further, the user can issue a paper conveyance instruction by operating the operation display unit 20.

  The image processing unit 30 performs digital image processing on the input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on gradation correction data configured as a gradation correction table. The image processing unit 30 performs various correction processes such as color correction and shading correction, or compression processing on the input image data. The image processing unit 30 supplies the image data subjected to these processes to the image forming unit 40.

  The image forming unit 40 forms an image with each color toner of the Y component, the M component, the C component, and the K component based on the image data subjected to various processes in the image processing unit 30. A unit 41, an intermediate transfer unit 42, and a fixing unit 60 are provided.

  The image forming unit 41 includes four image forming units 41Y, 41M, 41C, and 41K for Y component, M component, C component, and K component. Since each of the image forming units 41Y, 41M, 41C, and 41K has similar constituent elements, common constituent elements are denoted by the same reference numerals, and description thereof is omitted. For example, in FIG. 2, reference numerals are given only to the constituent elements of the Y component image forming unit 41Y, and the constituent elements of the other image forming units 41M, 41C, 41K are omitted. Hereinafter, the function for the Y component will be described.

  Next, the image forming unit 41Y will be specifically described. The image forming unit 41Y forms a Y (yellow) color image. The image forming unit 41Y includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, and a drum cleaning device 415.

  The charging device 414 is disposed around the photosensitive drum 413, and uniformly charges the surface of the photosensitive drum 413 to a negative polarity by corona discharge.

  The exposure device 411 irradiates the photosensitive drum 413 with light corresponding to the image of the Y color component. Thereby, an electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 forms a toner image by visualizing the electrostatic latent image by attaching toner of Y color component to the surface of the photosensitive drum 413.

  A Y-color toner image is formed on the photosensitive drum 413 by the developing device 412. The toner image formed on the photosensitive drum 413 is primarily transferred to the intermediate transfer unit 42. Note that the photosensitive drum 413 is not limited as long as it has photoconductivity and functions as a photosensitive member that records an image as an electrostatic latent image. For example, instead of the photosensitive drum 413, a photosensitive belt that functions as a photosensitive member may be used.

  The drum cleaning device 415 removes transfer residual toner remaining on the surface of the photosensitive drum 413 after the primary transfer of the toner image formed on the photosensitive drum 413.

  Since each of the image forming units 41M, 41C, and 41K has the same configuration and function as the image forming unit 41Y except that the color of the image to be formed is different, the description thereof is omitted.

  Next, the intermediate transfer unit 42 will be specifically described. The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, and a belt cleaning device 426.

  The intermediate transfer belt 421 is composed of an endless belt and is stretched in a loop shape by a plurality of support rollers 423. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the support roller 423 disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. As the driving roller rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 via the intermediate transfer belt 421. As a result, a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421 is formed.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face one of the plurality of support rollers 423. The support roller 423 arranged to face the intermediate transfer belt 421 is called a backup roller. The secondary transfer roller 424 is pressed against the backup roller via the intermediate transfer belt 421, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the long paper T.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner image on the photosensitive drum 413 is primarily transferred onto the intermediate transfer belt 421 in order. Specifically, the primary transfer bias is applied to the primary transfer roller 422, and the charge having the opposite polarity to the toner constituting the toner image is applied to the back surface side of the intermediate transfer belt 421, that is, the side in contact with the primary transfer roller -422. By being applied, the toner image on the photosensitive drum 413 is electrostatically transferred to the intermediate transfer belt 421.

  When the toner image on the photosensitive drum 413 is electrostatically transferred to the intermediate transfer belt 421 and the long paper T passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is transferred to the long paper T two times. Next transferred. Specifically, a secondary transfer bias is applied to the secondary transfer roller 424, and a charge having a polarity opposite to that of the toner is applied to the back side of the long paper T, that is, the side in contact with the secondary transfer roller 424. As a result, the toner image on the intermediate transfer belt 421 is electrostatically transferred to the long paper T. The long paper T onto which the toner image on the intermediate transfer belt 421 has been transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 includes a belt cleaning blade that contacts the surface of the intermediate transfer belt 421. The belt cleaning device 426 removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer of the toner image on the intermediate transfer belt 421.

  Next, the fixing unit 60 will be specifically described. The fixing unit 60 includes an upper fixing unit 61, a lower fixing unit 62, a heating unit 63, and a temperature detection unit 67, and fixes the toner image transferred by the image forming unit 40 to the long paper T. The upper fixing unit 61 includes a fixing surface side member disposed on the fixing surface side of the long paper T, that is, the surface side on which the toner image is formed. The lower fixing unit 62 includes a back side support member disposed on the back side of the long paper T, that is, on the side opposite to the fixing surface.

  The upper fixing unit 61 includes a fixing roller 611a and a fixing roller 611b as fixing surface side members. A fixing belt is looped around the fixing roller 611a and the fixing roller 611b. The lower fixing unit 62 includes a pressure roller 621 as a back side support member. The position of the pressure roller 621 is controlled between the fixing roller 611b by being controlled by the control unit 80, and the pressure roller 621 is disposed in either the pressure-bonded state or the separated state.

  The heating unit 63 is disposed in or near the fixing surface side member and heats the fixing surface side member. The controller 80 controls the output of the heating unit 63 so that the fixing surface side member is heated. Accordingly, the fixing temperature of the fixing unit 60 reaches a temperature necessary for fixing the toner image secondarily transferred on the long paper T to the long paper T. The temperature detection unit 67 is disposed in the vicinity of the fixing surface side member and detects the fixing temperature of the fixing unit 60. That is, the control unit 80 controls the output of the heating unit 63 based on the detection result of the temperature detection unit 67.

  Under the control of the control unit 80, when the pressure roller 621 is brought into pressure contact with the fixing roller 611b and brought into a pressure-bonded state, a fixing nip is formed. The long paper T is nipped and conveyed by the fixing nip. Thereby, the long paper T is heated and pressurized when passing through the fixing nip. Therefore, the toner image secondarily transferred to the long paper T is fixed to the long paper T.

  Next, the transport path 50 for the long paper T will be described. The long paper T is guided to the transport path 50 by the paper feeding unit 51. That is, the paper feed unit 51 guides the long paper T conveyed from the paper supply device 1 </ b> A to the conveyance path 50. The paper feeding unit 51 applies a predetermined load to the long paper T according to the type of the long paper T. As a result, the long paper T is smoothly guided to the transport path 50. The conveyance path 50 is a sheet passing path for conveying the long paper T from the paper supply unit 51 to the paper discharge unit 52. The transport path 50 transports the long paper T fed from the paper feed unit 51 in the order of the image forming unit 40, the fixing unit 60, and the paper discharge unit 52 by a transport roller that transports the long paper T. The paper discharge unit 52 guides the long paper T conveyed from the conveyance path 50 to the winding device 1C. The transport roller is a generic term for rollers that transport the long paper T, and is not particularly limited as long as it is a roller that transports the long paper T. The transport roller is composed of a driven roller and a main roller. The main driving roller faces the driven roller and rotates the driven roller.

  Next, conveyance of the long paper T on which the lower image 901 is formed will be described. FIG. 3 is a diagram illustrating a positional relationship between the position detection sensor 31 and the long paper T according to the first embodiment. FIG. 4 is a diagram illustrating an example of the lower image 901 and the position mark 903 formed on the long paper T according to the first embodiment. FIG. 5 is a diagram illustrating a variation example of the transport speed of the long paper T according to the first embodiment.

  As shown in FIG. 3, the lower image 901 is already formed on the long paper T. Further, a position mark 903 is formed on the long paper T. When the long paper T is conveyed from the paper supply unit 51 into the casing 10 of the image forming apparatus 1B and discharged from the paper discharge unit 52, the position mark 903 is detected by the position detection sensor 31. The position detection sensor 31 can be appropriately moved by, for example, a stepping motor in accordance with the position where the position mark 903 is formed.

  As shown in FIG. 4, a long image T has a lower image 901 formed thereon. Therefore, the long paper T can be additionally printed by forming another image in accordance with the lower image 901. When performing reprint printing, a position mark 903 is formed on the long paper T so that the position of the lower image 901 and the position of the image to be formed are aligned. A plurality of position marks 903 are formed on the long paper T at a constant pitch. For example, in the example of FIG. 4, the position marks 903 are formed at a constant pitch along the end of the long paper T in the longitudinal direction. If such a position mark 903 is detected, it is possible to align the position of the lower image 901 with the position of an image to be formed in the case of performing overprint printing.

  However, in practice, the transport speed of the long paper T may vary due to the eccentricity of the transport roller. Further, as for the conveyance speed of the long paper T, the roller diameter of the conveyance roller may expand due to heat from the long paper T. Therefore, as shown in FIG. 5, the transport speed of the long paper T may fluctuate due to periodic fluctuations caused by the eccentricity of the transport roller. In addition, the transport speed of the long paper T may fluctuate due to a change with time due to thermal expansion. Moreover, both such periodic fluctuations and fluctuations with time may occur, or only one of them may occur. Therefore, there is a possibility that the reprinting cannot be accurately performed only by simply detecting the position mark 903.

  Therefore, the image forming system 1 obtains not only the temporal variation by obtaining the transport speed of the long paper T based on the detection cycle of the position marks 903 periodically formed at a constant pitch, that is, at regular intervals. It is possible to detect the transport speed of the long paper T including the period fluctuation. Therefore, the transport speed of the long paper T is the average speed detected correctly. Accordingly, the image forming system 1 can perform overprinting with high accuracy by obtaining the speed fluctuation amount from the correctly detected average speed and controlling the writing timing for starting the writing of the image.

  Next, a function for obtaining the speed fluctuation amount of the conveyance speed of the long paper T based on the detection cycle of the position mark 903 and controlling the writing timing for starting the writing of the image will be described. FIG. 6 is a block diagram illustrating an example of a functional configuration of the image forming apparatus 1B according to the first embodiment. Specifically, the control unit 80 mainly includes a CPU, a ROM, a RAM, and an I / O interface (not shown). In the control unit 80, the CPU reads out various programs corresponding to the processing contents from the ROM or a storage unit (not shown), expands the program in the RAM, and cooperates with the expanded various programs, whereby the operation of each unit of the image forming apparatus 1B is performed. For example, the image processing unit 30 and the image forming unit 40 are controlled.

  That is, the control unit 80 controls the operation of the image forming apparatus 1B, and can be realized by a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface (not shown). When the control unit 80 executes a predetermined control program, various functions including the detection unit 811, the calculation unit 812, and the timing control unit 813 in FIG. 6 are realized.

  The control unit 80 is supplied with the detection result of the position detection sensor 31. The position detection sensor 31 is not particularly limited as long as it detects the position mark 903. For example, if the position mark 903 is black, the long paper T is white, and the lower image 901 is other than black and white, the position mark 903 can be detected by using the difference in reflectance. The detection sensor 31 can be realized by a reflective photosensor.

  The control unit 80 is supplied with the detection result of the image detection sensor 39. The image detection sensor 39 is not particularly limited as long as it detects the lower image 901. For example, the image detection sensor 39 may be realized by a reflective photosensor as in the case of the position detection sensor 31. In this case, the position detection sensor 31 and the image detection sensor 39 may be realized by one reflective photosensor. That is, the reflective photosensor may realize a function of detecting the position mark 903 and a function of detecting the lower image 901.

  Here, details of the position mark 903 in FIG. 4 will be described. The position mark 903 in FIG. 4 functions as a cycle detection mark. It is only necessary that a large number of position marks 903 functioning as period detection marks are periodically formed on the long paper T. If a large number of position marks 903 are periodically formed, the detection signal of the position mark 903 is constant under an ideal transport environment of the long paper T so that the transport speed of the long paper T does not change. Detected at intervals. Therefore, if the detection signal of the position mark 903 is not detected at regular intervals, it can be considered that the transport speed of the long paper T has changed. Therefore, if a large number of the lower images 901 are periodically formed, the lower image 901 functions as a cycle detection mark. Therefore, the lower image 901 may be detected without detecting the position mark 903.

  As described above, the detection signal of the position mark 903 is not detected at regular intervals under the conveyance environment of the long paper T in which the conveyance speed of the long paper T varies. Therefore, by obtaining the detection cycle from the detection result of the position mark 903, the speed fluctuation amount of the transport speed of the long paper T can be obtained from the detection cycle. If the speed fluctuation amount of the transport speed of the long paper T is obtained, the path from the lower image 901 of the long paper T to the transfer position of the intermediate transfer belt 421, specifically, the long paper T Since the path from the lower image 901 of the paper T to the secondary transfer nip is determined, the image from the lower image 901 of the long paper T to the secondary transfer nip is determined. The arrival time can be obtained.

  Further, an image arrival time until the lower image 901 of the long paper T reaches the secondary transfer nip from the paper feeding unit 51 and a toner image arrival time until the toner image on the photosensitive drum 413 reaches the secondary transfer nip are determined. If they can be matched, the reprinting can be made with high accuracy.

  Therefore, in addition to the detection cycle of the position mark 903, it is necessary to accurately obtain the timing at which the lower image 901 of the long paper T passes through the paper feeding unit 51. Therefore, the lower image 901 is detected by the image detection sensor 39. In this case, the lower image 901 functions as an image detection mark. If the timing at which the lower image 901 passes through the paper feeding unit 51 can be accurately obtained, the image arrival time from when the lower image 901 of the long paper T passes through the paper feeding unit 51 to the secondary transfer nip can be accurately determined. Can be requested.

  If the image arrival time until the lower image 901 of the long paper T reaches the secondary transfer nip from the paper feeding unit 51 is accurately obtained, the image is written to match the toner image arrival time with the image arrival time. The timing to start can be controlled.

  In other words, by predicting the arrival timing shift of the lower image 901 to the transfer position due to the change in the conveyance speed of the long paper T from the detection cycle of the position mark 903, and correcting the output time of the image writing timing, reprinting is performed. Can be made with high accuracy.

  The position detection sensor 31 and the image detection sensor 39 are preferably arranged between the time when the long paper T enters the paper feeding unit 51 and before the paper enters the housing 10. In addition, the mounting tolerance between each of the position detection sensor 31 and the image detection sensor 39 and the secondary transfer nip that is the transfer position of the image to be matched with the lower image 901 is detected in advance and removed with an offset. preferable. Further, it is preferable that the speed fluctuation amount of the conveyance speed of the long paper T is detected before the printing of the image to be matched with the lower image 901 is started.

  Next, the detection unit 811, the calculation unit 812, and the timing control unit 813 predict a shift in the arrival timing of the lower image 901 from the detection cycle of the position mark 903 to the transfer position of the lower image 901 due to the change in the conveyance speed of the long paper T. A function for correcting the output time of the image writing timing will be specifically described.

  The detection unit 811 detects the speed fluctuation amount of the transport speed of the long paper T. That is, the detection unit 811 obtains the speed fluctuation amount of the transport speed of the long paper T based on the detection cycle of the position mark 903 detected by the position detection sensor 31. When there is an instruction to form an image on the long paper T, the detection unit 811 detects a speed fluctuation amount of the conveyance speed of the long paper T before the image formation is started on the long paper T. When the image to be matched with the lower image 901 is formed on the long paper T, the detection unit 811 detects the speed fluctuation amount of the transport speed of the long paper T before the passage of the lower image 901 is detected by the image detection sensor 39. If the speed fluctuation amount of the transport speed of the long paper T after the passage of the lower image 901 is detected by the image detection sensor 39 is different, the speed fluctuation amount of the transport speed of the long paper T is updated to the latest one. To do.

  Note that the speed fluctuation amount of the transport speed of the long paper T is preferably stored as a profile of the image forming apparatus 1B.

  The calculation unit 812 detects the lower image 901 formed on the long paper T based on the speed fluctuation amount of the conveyance speed of the long paper T detected by the detection unit 811, and then moves to the transfer position of the intermediate transfer belt 421. The image arrival time until it reaches is calculated.

  When the timing control unit 813 matches the image arrival time calculated by the calculation unit 812 with the toner image arrival time until the toner image on the photosensitive drum 413 transferred to the intermediate transfer belt 421 reaches the transfer position, the lower image 901 is displayed. The writing timing for starting the writing of the image formed in accordance with is controlled. For example, when image writing is started in accordance with the rise of the output signal of the image writing timing, the image writing timing can be controlled by correcting the output time of the image writing timing.

  Next, a control example of the control unit 80 will be described. FIG. 7 is a flowchart illustrating a control example of the control unit 80 according to the first embodiment. FIG. 8 is a flowchart illustrating details of the conveyance speed detection process according to the first embodiment.

  The follow-up printing process in FIG. 7 will be described. In step S11, it is determined whether there is a print instruction. If it is determined that there is a print instruction, the process proceeds to step S12. If it is determined that there is no print instruction, the process waits as it is.

  In step S12, the detection sensor is set to an on state. Specifically, the position detection sensor 31 can detect the position mark 903. The image detection sensor 39 can detect the lower image 901. Note that it is a warm-up period after it is determined that there is a print instruction and until printing is started. Therefore, the processing from step S12 to later-described steps S13, 14, and 15 is processing executed during the warm-up period.

  In step S13, the conveyance of the long paper T is started. Specifically, the conveyance of the long paper T from the paper feeding device 1A to the image forming device 1B is started.

  In step S14, a conveyance speed detection process for detecting the conveyance speed of the long paper T is executed. The details of the conveyance speed detection process will be described later.

  In step S15, the processing result of the conveyance speed detection process is stored as speed fluctuation information. The speed fluctuation information is specifically a speed fluctuation amount of the transport speed of the long paper T. Therefore, it is preferable to store the speed fluctuation information as a profile of the image forming apparatus 1B.

  In step S16, printing is started. Specifically, the image forming operation by the image forming unit 40 is started.

  In step S17, it is determined whether an image detection mark has been detected. If it is determined that the image detection mark has been detected, the process proceeds to step S18. If it is determined that the image detection mark is not detected, the process proceeds to step S23. As described above, for example, the image detection sensor 39 detects the image detection mark.

  In step S18, the image arrival time to reach the transfer position is calculated. Specifically, after the image detection sensor 39 detects the lower image 901, the time until the lower image 901 reaches the secondary transfer nip is calculated.

  In step S19, an image formation start signal is output. As a result, the image processing unit 30 outputs a command to form an image to the image forming unit 40, and the image forming process by the image forming unit 40 is started.

  In step S20, the write timing is set to the on state. Specifically, when the output signal of the image writing timing is output, in the image forming unit 40, the exposure device 411 irradiates the photosensitive drum 413 with light corresponding to the image, and the developing device 412 receives the electrostatic latent image. The toner image visualized on the photosensitive drum 413 is transferred to the intermediate transfer belt 421 through the primary transfer nip, and the toner image on the intermediate transfer belt 421 passes through the secondary transfer nip. The image is transferred to the long paper T, and the fixing unit 60 fixes the toner image to the long paper T.

  In step S21, it is determined whether or not printing has been completed. If it is determined that printing is complete, the process proceeds to step S22. On the other hand, if it is determined that printing is not completed, the process proceeds to step S23.

  In step S22, the detection sensor is set to an off state, and the follow-up printing process ends. Specifically, the position detection sensor 31 does not detect the position mark 903. The image detection sensor 39 does not detect the lower image 901.

  In step S23, a transport speed detection process for detecting the transport speed of the long paper T is executed as in step S14. The details of the conveyance speed detection process will be described later.

  In step S24, it is determined whether or not the speed fluctuation amount of the transport speed of the long paper T has changed. When it is determined that the speed fluctuation amount of the transport speed of the long paper T has changed, the process proceeds to step S25. On the other hand, when it is determined that the speed fluctuation amount of the transport speed of the long paper T does not change, the process returns to step S23.

  In step S25, among the processing results of the transport speed detection process, the change in the speed fluctuation amount of the transport speed of the long paper T is updated as speed fluctuation information, and the process returns to step S17.

  The conveyance speed detection process in FIG. 8 will be described. In step S41, the transport speed of the long paper T is detected. Specifically, since the position marks 903 are formed on the long paper T at a constant pitch, the pitch of the position marks 903 is determined. However, if the transport speed of the long paper T varies, the time from when the position mark 903 is detected until the next position mark 903 is detected varies. Therefore, the detection unit 811 measures the detection interval of the position mark detection signal that is the detection result of the position detection sensor 31. The detection unit 81 detects the transport speed of the long paper T based on the time measurement result of the detection interval of the position mark detection signal and the pitch of the position marks 903.

  In step S42, it is determined whether or not the sampling period of the position mark 903 has ended. If it is determined that the sampling period of the position mark 903 has ended, the process proceeds to step S43. On the other hand, if it is not determined that the sampling period of the position mark 903 has ended, the process returns to step S41.

  In step S43, the speed fluctuation amount of the transport speed of the long paper T is detected, and the transport speed detection process ends. Specifically, the speed fluctuation amount of the transport speed of the long paper T is detected based on the transport speed of the long paper T detected in step S41.

  From the above description, the image forming system 1 controls not only the temporal variation but also the periodic variation by controlling the writing timing of the image to be formed on the long paper T from now on based on the speed variation amount of the conveyance speed of the long paper T. The timing at which the toner image of the image written on the long paper T reaches the transfer position is formed on the transported long paper T according to the transport speed of the long paper T in which the average speed is correctly detected. The position of the image already formed on the long paper T and the length of the long paper T can be adjusted regardless of variations in the conveyance speed of the long paper T. The position of the image formed on the paper T can be accurately matched.

  In the above description, the image already formed on the long paper T corresponds to the lower image 901.

  Further, in the image forming system 1, the conveyance speed of the long paper T is detected by detecting the speed fluctuation amount of the conveyance speed of the long paper T based on the detection cycle of the position mark 903 detected by the position detection sensor 31. Since it is possible to obtain a variation including a periodic variation caused by the environment and a temporal variation caused by thermal expansion, it is possible to accurately obtain the timing at which the toner image of the image written on the long paper T reaches the transfer position. it can.

  In the image forming system 1, when there is an instruction to form an image on the long paper T, the speed fluctuation amount of the conveyance speed of the long paper T is changed before the image formation is started on the long paper T. By detecting this, it is possible to accurately determine the transport time required for the image already formed on the long paper T to be transported to the transfer position, so that the write start timing for starting the image write is accurately determined. be able to.

  Further, in the image forming system 1, when an image is formed on the long paper T in accordance with an image already formed on the long paper T, the passage of the image already formed on the long paper T is detected. When the speed fluctuation amount of the transport speed of the long paper T before the printing is different from the speed fluctuation amount of the transport speed of the long paper T after the passage of the image already formed on the long paper T is detected. By updating the speed fluctuation amount of the transport speed of the long paper T to the latest one, the image already formed on the long paper T is transported to the transfer position based on the latest speed fluctuation amount. Since the transport time required until the start of image writing can be obtained, the start timing for starting image writing can be matched with the current transport environment of the long paper T.

  As described above, according to the image forming system 1 according to the present embodiment, the paper feeding device 1A, the image forming device 1B that forms an image on the long paper T fed from the paper feeding device 1A, and the image formation. The image forming system 1 includes a winding device 1C that winds the long paper T on which an image is formed by the device 1B. The image forming device 1B forms an image on the long paper T by the intermediate transfer belt 421. The image forming unit 40 and a control unit 80 that controls the image forming unit 40 are provided. The control unit 80 is detected by a detection unit 811 that detects a speed fluctuation amount of the conveyance speed of the long paper T and a detection unit 811. A calculation unit 812 that calculates an image arrival time from when the first image formed on the long paper T is detected to the transfer position of the intermediate transfer belt 421 based on the speed variation amount, and a calculation unit 812 The image calculated by When the toner image arrival time until the toner image on the photosensitive drum 413 transferred to the intermediate transfer belt 421 reaches the transfer position is adjusted over time, the second image is written by the toner image formed in accordance with the first image. And a timing control unit 813 for controlling the write start timing for starting the process.

  Accordingly, the position of the image already formed on the long paper T and the position of the image to be formed on the long paper T from now on, despite the variation in the transport speed of the long paper T, can be accurately determined. Can be matched.

  In the above description, the first image corresponds to an image already formed on the long paper T, that is, the lower image 901. The second image corresponds to an image to be formed on the long paper T from now on. That is, when the second image is overprinted on the first image, the overprinting can be accurately performed by controlling the writing start timing of the second image based on the speed fluctuation amount of the transport speed of the long paper T. It can be carried out.

  The image forming system 1 according to the present embodiment further includes the position detection sensor 31 that detects a plurality of position marks 903 formed on the long paper T at a constant pitch, and the detection unit 811 includes the position detection sensor. The speed fluctuation amount is detected based on the detection cycle of the position mark 903 detected by 31.

  As a result, the image forming system 1 can accurately determine the timing at which the toner image of the image to be written on the long paper T reaches the transfer position.

  Further, according to the image forming system 1 according to the present embodiment, the detection unit 811 forms the second image on the long paper T when there is an instruction to form the second image on the long paper T. Before starting, the speed fluctuation amount is detected.

  As a result, the image forming system 1 can accurately determine the writing timing for starting the writing of the image.

  The image forming system 1 according to the present embodiment further includes the image detection sensor 39 that detects the passage of the first image as the long paper T is conveyed, and the detection unit 811 includes the long paper T. While the second image is formed, the speed fluctuation amount before the passage of the first image is detected by the image detection sensor 39 and the passage of the first image after the passage of the first image is detected by the image detection sensor 39. If the speed fluctuation amount is different, the speed fluctuation amount is updated to the latest one.

  Thereby, the image forming system 1 can match the writing timing for starting the writing of the image with the current transport environment of the long paper T.

  Further, the image forming apparatus 1B according to the present embodiment includes the image forming unit 40 that forms an image on the long paper T by the intermediate transfer belt 421, and the control unit 80 that controls the image forming unit 40. The unit 80 detects a speed fluctuation amount of the conveyance speed of the long paper T, and detects a first image formed on the long paper T based on the speed fluctuation amount detected by the detection unit 811. A calculation unit 812 that calculates an image arrival time from when the transfer reaches the transfer position of the intermediate transfer belt 421 to the image transfer time calculated by the calculation unit 812 of the photosensitive drum 413 transferred to the intermediate transfer belt 421 When the toner image arrival time until the toner image reaches the transfer position is adjusted, the writing timing for starting the writing of the second image by the toner image formed in accordance with the first image is controlled. And a timing control unit 813.

  As a result, the image forming apparatus 1B according to the present embodiment is already formed on the long paper T in spite of variations in the transport speed of the long paper T, as in the case of the image forming system 1. The position of the image and the position of the image to be formed on the long paper T can be accurately matched.

  Further, according to the program according to the present embodiment, the long paper is detected based on the detection unit 811 that detects the speed fluctuation amount of the conveyance speed of the long paper T and the speed fluctuation amount detected by the detection unit 811. A calculation unit 812 that calculates an image arrival time from when the first image formed at T is detected until it reaches the transfer position of the intermediate transfer belt 421, and the image arrival time calculated by the calculation unit 812 When the toner image arrival time until the toner image on the photosensitive drum 413 transferred to the transfer belt 421 reaches the transfer position is adjusted, writing is started to start writing the second image by the toner image formed in accordance with the first image. It functions as a timing control unit 813 that controls timing.

  As a result, the program according to the present embodiment, as in the case of the image forming system 1, is the position of the image already formed on the long paper T, even though the transport speed of the long paper T varies. And the position of the image to be formed on the long paper T from now on can be accurately matched.

Embodiment 2. FIG.
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the second embodiment, a process for correcting image data is further added before the start of image formation.

  The image processing unit 30 optimizes the image to be formed on the image forming unit 40 based on the speed fluctuation amount of the conveyance speed of the long paper T detected by the detection unit 811. The image optimization processing executed by the image processing unit 30 according to the present embodiment is, in particular, front / back position adjustment among front / back position adjustment, density adjustment, color adjustment, and the like of an image formed on the long paper T. .

  That is, in the present embodiment, the image processing unit 30 corrects the position of the image in particular among the color, position, or magnification of the image. Specifically, when the image processing unit 30 starts writing an image formed in accordance with the lower image 901, the image processing unit 30 moves in the transport direction of the long paper T based on the speed fluctuation amount of the transport speed of the long paper T. The position of the image formed on the long paper T is corrected according to the deviation along the line.

  Next, a processing example of the image processing unit 30 will be described. FIG. 9 is a flowchart illustrating a control example of the control unit 80 according to the second embodiment. FIG. 10 is a flowchart for explaining the details of the image data correction processing according to the second embodiment.

  The reprint process of FIG. 9 in the present embodiment is obtained by inserting an image data correction process between the process of step S18 and the process of step S19 in the reprint process of FIG. 7 of the first embodiment. . Therefore, in this embodiment, among the reprinting processes in FIG. 9, the processes in steps S51 to S58 correspond to steps S11 to S18 in FIG. 7, and the processes in steps S60 to S66 are in steps S19 to S19 in FIG. Since it corresponds to the process of S25, the description is omitted.

  The image data correction process in FIG. 10 will be described. In step S81, it is determined whether the image arrival time is different from the specified arrival time. If it is determined that the image arrival time is different from the specified arrival time, the process proceeds to step S82. On the other hand, when it is determined that the image arrival time is not different from the specified arrival time, the image data correction process ends. Here, the specified arrival time is from when the lower image 901 is detected by the image detection sensor 39 when the conveyance environment of the long paper T does not change with time until it reaches the secondary transfer nip. Is set.

  In step S82, it is determined whether or not there are two or more images formed on the long paper T. If there are two or more images formed on the long paper T, the process proceeds to step S83. On the other hand, when the number of images formed on the long paper T is less than 2, the image data correction process ends.

  In step S83, for the second and subsequent images, the position of the image formed on the long paper T is corrected according to the deviation along the transport direction of the long paper T.

  Next, the correction of the image position will be specifically described. FIG. 11 is a diagram illustrating the position of an unformed image 902 that is corrected by the image data correction process according to the second embodiment.

  When the transport speed of the long paper T is slower than the predetermined transport speed, the image arrival time requires more time than the predetermined arrival time. In this case, as shown in FIG. 11, the positions of the lower image 901 and the unformed image 902 can be aligned by shifting the unformed image 902 in the direction opposite to the conveyance direction of the long paper T.

  On the other hand, when the transport speed of the long paper T is faster than the transport speed defined in advance, the image arrival time does not require more time than the specified arrival time. In this case, as shown in FIG. 11, the lower image 901 and the unformed image 902 can be aligned by shifting the unformed image 902 in the same direction as the transport direction of the long paper T.

  From the above description, in the image forming system 1, when the writing of the second image formed in accordance with the first image is started, the deviation along the transport direction of the long paper T based on the speed fluctuation amount is detected. Accordingly, by correcting the position of the second image formed on the long paper T, it is possible to correct the image shift along the conveyance direction of the long paper T. The position of the current image and the position of the image to be formed on the long paper T from now on can be adjusted particularly remarkably accurately.

  In the above description, the first image corresponds to an image already formed on the long paper T, that is, the lower image 901. The second image corresponds to an image to be formed on the long paper T from now on, that is, an unformed image 902.

  As described above, the image forming system 1 according to the present embodiment further includes the image processing unit 30 that performs processing relating to an image, and the image processing unit 30 writes the second image to be formed in accordance with the first image. When started, the position of the second image formed on the long paper T is corrected according to the deviation along the transport direction of the long paper T based on the speed fluctuation amount.

  Thereby, the image forming system 1 can align the position of the image already formed on the long paper T with the position of the image to be formed on the long paper T in a particularly remarkable manner.

Embodiment 3. FIG.
In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted. In the third embodiment, an example using the acceleration sensor 32 instead of the position detection sensor 31 will be described.

  FIG. 12 is a block diagram illustrating an example of a functional configuration of the image forming apparatus 1B according to the third embodiment. The acceleration sensor 32 in FIG. 12 detects the acceleration of the long paper T. The detection unit 811 detects the speed fluctuation amount according to the acceleration of the long paper T detected by the acceleration sensor 32. Specifically, the acceleration sensor 32 is realized by, for example, a capacitance detection method.

  Since the acceleration sensor 32 can detect the acceleration when the long paper T is transported, the detection unit 811 compares the processing for obtaining the speed fluctuation amount of the transport speed of the long paper T from the position detection sensor 31. The amount of calculation required for the processing is reduced.

  From the above description, the image forming system 1 detects the speed fluctuation amount of the transport speed of the long paper T based on the acceleration of the long paper T detected by the acceleration sensor 32, and thereby the long paper T Therefore, the timing at which the toner image of the image written on the long paper T reaches the transfer position can be accurately obtained.

  As described above, the image forming system 1 according to the present embodiment further includes the acceleration sensor 32 that detects the acceleration of the long paper T, and the detection unit 811 detects the acceleration of the long paper T detected by the acceleration sensor 32. In response, the speed fluctuation amount is detected.

  As a result, the image forming system 1 can accurately determine the timing at which the toner image of the image to be written on the long paper T reaches the transfer position.

Embodiment 4 FIG.
In the fourth embodiment, the same components as those in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted. In the fourth embodiment, an example using a rotary encoder 33 instead of the position detection sensor 31 or the acceleration sensor 32 will be described.

  FIG. 13 is a block diagram illustrating an example of a functional configuration of the image forming apparatus 1B according to the fourth embodiment. The rotary encoder 33 in FIG. 13 detects the rotational displacement of the driven roller that rotates as the long paper T is conveyed. The detection unit 811 detects the speed fluctuation amount based on the rotational displacement detected by the rotary encoder 33. Specifically, the angular velocity is obtained by rotational displacement. Since the angular velocity and the transport speed of the long paper T have a correlation, it is only necessary to execute processing for converting the obtained displacement of the angular speed into a speed fluctuation amount of the transport speed of the long paper T.

  From the above description, in the image forming system 1, the speed fluctuation amount of the transport speed of the long paper T is detected based on the rotational displacement detected by the rotary encoder 33. Since the change with time can be obtained, the timing at which the toner image of the image written on the long paper T reaches the transfer position can be obtained accurately.

  As described above, the image forming system 1 according to the present embodiment further includes the rotary encoder 33 that detects the rotational displacement of the driven roller that rotates as the long paper T is conveyed. The amount of speed fluctuation is detected based on the rotational displacement detected by.

  As a result, the image forming system 1 can accurately determine the timing at which the toner image of the image to be written on the long paper T reaches the transfer position.

  As described above, the image forming system 1 according to the present invention has been described based on the embodiment. However, the present invention is not limited to this, and may be modified without departing from the spirit of the present invention.

  For example, in the present embodiment, an example in which the image detection sensor 39 is realized by a reflective photosensor has been described, but the present invention is not particularly limited thereto. For example, the image detection sensor 39 may be composed of a CCD or CMOS sensor as an image sensor.

  Moreover, although the example in which the position detection sensor 31 is movable by the stepping motor has been described, the present invention is not limited thereto, and the position detection sensor 31 may be movable by a linear motor.

  Further, although an example in which the position detection sensor 31 is movable has been described, the image detection sensor 39 may be movable in the same manner.

  Further, an example in which image writing is started according to the rise of the output signal at the image writing timing has been described. However, the present invention is not limited to this, and image writing is started according to the falling edge of the output signal at the image writing timing. Also good.

  Moreover, although the acceleration sensor 32 demonstrated an example implement | achieved by the electrostatic capacitance detection system, it should just be the structure which can detect not only this but an acceleration.

DESCRIPTION OF SYMBOLS 1 Image forming system 1A Paper feeder 1B Image forming apparatus 1C Winding device 10 Case 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 31 Position detection sensor 32 Acceleration sensor 33 Rotary encoder 39 Image detection sensor 40 Image formation Section 41, 41Y, 41M, 41C, 41K Image forming unit 42 Intermediate transfer unit 411 Exposure device 412 Developing device 413 Photosensitive drum 414 Charging device 415 Drum cleaning device 421 Intermediate transfer belt 422 Primary transfer roller 423 Support roller 424 Secondary transfer roller 426 Belt cleaning device 50 Conveyance path 51 Paper feed unit 52 Paper discharge unit 60 Fixing unit 61 Upper fixing unit 611, 611a, 611b Fixing roller 62 Lower fixing unit 621 Pressure roller 63 Heating unit 67 Temperature detection Part 80 control unit 811 detecting unit 812 calculating unit 813 a timing control unit 901 under the image 902 unformed image 903 position mark T long paper

Claims (9)

A paper feeding device;
An image forming apparatus for forming an image on long paper fed from the paper feeding device;
An image forming system comprising: a winding device that winds the long paper on which the image is formed by the image forming device;
The image forming apparatus includes:
An image forming unit that forms the image on the long paper by an intermediate transfer belt;
A control unit for controlling the image forming unit,
The controller is
A detection unit for detecting a speed fluctuation amount of the transport speed of the long paper;
Based on the speed fluctuation amount detected by the detection unit, an image arrival time from when the first image formed on the long sheet is detected until the transfer position of the intermediate transfer belt is reached is calculated. An arithmetic unit;
When the toner arrival time until the toner image on the photosensitive drum transferred to the intermediate transfer belt reaches the transfer position is matched with the image arrival time calculated by the calculation unit, the image arrival time is adjusted to the first image. A timing control unit for controlling the writing start timing for starting the writing of the second image by the toner image to be formed.
Image forming system. A position detection sensor for detecting a plurality of position marks formed at a constant pitch on the long paper;
The detector is
Detecting the speed fluctuation amount based on a detection cycle of the position mark detected by the position detection sensor;
The image forming system according to claim 1. An acceleration sensor for detecting the acceleration of the long paper,
The detector is
Detecting the speed fluctuation amount according to the acceleration of the long paper detected by the acceleration sensor;
The image forming system according to claim 1. A rotary encoder that detects rotational displacement of a driven roller that rotates as the long paper is conveyed;
The detector is
Detecting the speed fluctuation amount based on the rotational displacement detected by the rotary encoder;
The image forming system according to claim 1. The detector is
When there is an instruction to form the second image on the long paper, the speed fluctuation amount is detected before the formation of the second image on the long paper is started.
The image forming system according to any one of claims 2 to 4. Along with the conveyance of the long paper, further comprising an image detection sensor for detecting the passage of the first image,
The detector is
While the second image is formed on the long paper,
The speed fluctuation amount before the passage of the first image is detected by the image detection sensor and the speed fluctuation amount after the passage of the first image is detected by the image detection sensor. If different, update the speed fluctuation amount to the latest one,
The image forming system according to claim 5. An image processing unit that performs processing related to the image;
The image processing unit
When writing of the second image to be formed in accordance with the first image is started,
Correcting the position of the second image formed on the long paper according to the deviation along the transport direction of the long paper based on the speed fluctuation amount;
The image forming system according to claim 6. An image forming unit for forming an image on a long sheet by an intermediate transfer belt;
A control unit for controlling the image forming unit,
The controller is
A detection unit for detecting a speed fluctuation amount of the transport speed of the long paper;
Based on the speed fluctuation amount detected by the detection unit, an image arrival time from when the first image formed on the long sheet is detected until the transfer position of the intermediate transfer belt is reached is calculated. An arithmetic unit;
When the toner arrival time until the toner image on the photosensitive drum transferred to the intermediate transfer belt reaches the transfer position is matched with the image arrival time calculated by the calculation unit, the image arrival time is adjusted to the first image. An image forming apparatus comprising: a timing control unit configured to control a writing start timing for starting writing of the second image by the toner image formed in the first step. On the computer,
A detection unit for detecting the speed fluctuation amount of the conveyance speed of the long paper;
A calculation unit that calculates an image arrival time from when the first image formed on the long sheet is detected until the transfer position of the intermediate transfer belt is reached based on the speed fluctuation amount detected by the detection unit. When,
When the toner arrival time until the toner image on the photosensitive drum transferred to the intermediate transfer belt reaches the transfer position is matched with the image arrival time calculated by the calculation unit, it matches the first image. A timing control unit for controlling the writing timing for starting the writing of the second image by the toner image to be formed;
Program to function as.

Images