Image forming apparatus and program

Abstract

The present invention provides an image forming apparatus and program that can suppress positional misalignment of the toner image formed by two image forming units, compared to a case where positional misalignment is adjusted based on the temperature at a single location within the apparatus. [Solution] The system comprises image forming units 30 and 50, a transport belt 21, a detection device 150 for detecting pattern images, a first temperature sensor 100, a second temperature sensor 200, and a control device 80. When the temperature difference between the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200 is greater than or equal to a preset first threshold, the control device 80 causes all image forming sections 32 and 52 of the image forming units 30 and 50 to form a pattern image on the transport belt 21, and uses the detection result of the detection device 150 to adjust the positional misalignment of the toner image formed by the image forming units 30 and 50.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus and a program.

Background Art

[0002] Patent Document 1 discloses an image forming apparatus that arranges temperature sensors at respective positions of a front-side frame and a rear-side frame, grasps a temperature rise, predicts a generated displacement amount, and corrects it.

[0003] Patent Document 2 discloses an image forming apparatus that measures the temperature inside the apparatus with a temperature sensor, performs a registration control adjustment based on a prediction table when the absolute value of the change amount of the temperature inside the apparatus is less than a threshold value, forms a registration adjustment patch and measures the displacement amount when the absolute value of the change amount of the temperature inside the apparatus is greater than or equal to the threshold value, and corrects the value in the prediction table to the measured value when the measured displacement amount and the value in the prediction table are far apart.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, in order to expand the color gamut of images formed by image forming machines, images are being formed not only using basic CMYK toners but also using toners of special colors other than CMYK. In such image forming machines, a configuration is sometimes used in which a toner image is formed on paper using multiple image forming units, each equipped with multiple image forming sections that form toner images. In each image forming unit, the toner images formed by the multiple image forming sections are first transferred onto an intermediate transfer surface, and the toner images on the intermediate transfer surface are then secondarily transferred onto the paper that has been transported along the paper transport path.

[0006] Furthermore, the components that make up each image forming unit expand due to temperature increases within the device and contract due to temperature decreases. As a result, positional shifts in the image forming position may occur due to temperature changes within the device. Therefore, a temperature sensor detects temperature changes within the image forming device, and when the detected temperature change becomes large, each image forming unit forms a pattern image for adjusting the positional shift. The pattern image is then secondarily transferred onto the conveyor belt, and a detection device reads it to adjust the positional shift of the toner image.

[0007] In a configuration where two image forming units are placed within an image forming apparatus, the image forming unit that is closer to the fuser than the other image forming unit is more susceptible to the heat generated by the fuser and tends to become hotter. Conversely, the image forming unit that is further from the fuser than the other image forming unit is less affected by the heat generated by the fuser and tends to remain cooler. When the temperature difference between the two image forming units becomes large, the difference in the amount of positional displacement of the toner images formed by each of the two image forming units also becomes large.

[0008] Therefore, if only one temperature sensor is installed in the image forming apparatus and positional misalignment is adjusted based solely on temperature changes at one location within the apparatus, the amount of positional misalignment caused by the temperature difference between the two image forming units may become large.

[0009] The object of the present invention is to provide an image forming apparatus and program that can suppress the positional misalignment of the toner image formed by two image forming units, compared to the case in which the misalignment is adjusted based on the temperature at one location within the apparatus. [Means for solving the problem]

[0010] An image forming apparatus according to a first aspect of the present disclosure includes: a first image forming unit having a plurality of image forming units and an intermediate transfer body on which toner images formed by the plurality of image forming units are first transferred; a second image forming unit arranged adjacent to the first image forming unit and having a plurality of image forming units and an intermediate transfer body on which toner images formed by the plurality of image forming units are first transferred; a transport belt for transporting paper to secondary transfer positions on which toner images formed on the intermediate transfer bodies of the first and second image forming units are secondarily transferred; and a transport belt provided downstream of the two secondary transfer positions in the transport direction in which the paper is transported by the transport belt, which is used to transport the toner images secondarily transferred onto the transport belt. The system includes a detection device for detecting a pattern image, a first temperature sensor positioned to detect the temperature around the first image forming unit, a second temperature sensor positioned to detect the temperature around the second image forming unit, and a processor. The processor, when the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is greater than or equal to a preset first threshold, uses all the image forming parts of the first and second image forming units to form a pattern image on the transport belt, and uses the detection result of the detection device to adjust the misalignment of the toner image formed by the first and second image forming units.

[0011] An image forming apparatus according to a second embodiment of the present disclosure, wherein the image forming apparatus according to the first embodiment is equipped with a memory, the memory stores the temperatures detected by the first temperature sensor and the second temperature sensor, respectively, when the positional misalignment was adjusted in the previous instance. The processor, even if the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is less than the first threshold, if the temperature difference between the temperature detected by the first temperature sensor when the positional misalignment was adjusted in the previous instance stored in the memory and the temperature detected by the first temperature sensor this time is greater than or equal to a preset second threshold, forms a pattern image on the transport belt using a plurality of image forming sections of the first image forming unit, and adjusts the positional misalignment of the toner image formed by the first image forming unit using the detection result of the detection device.

[0012] In the third embodiment of the present disclosure, the image forming apparatus, in the image forming apparatus of the second embodiment, if the temperature difference between the temperature detected by the second temperature sensor when the previous misalignment adjustment was performed and the temperature detected by the second temperature sensor this time is greater than or equal to a preset third threshold, the processor forms a pattern image on the transport belt using a plurality of image forming sections of the second image forming unit, and adjusts the misalignment of the toner image formed by the second image forming unit using the detection result of the detection device.

[0013] In the image forming apparatus of the fourth embodiment of the present disclosure, in the image forming apparatus of the first embodiment, the processor forms pattern images of other colors between predetermined reference color pattern images in the second image forming unit when forming a pattern image on the transport belt using all the image forming sections of the first image forming unit and the second image forming unit.

[0014] In the fifth aspect of the present disclosure, the image forming apparatus of the fourth aspect is such that the image forming unit used as the reference color is the image forming unit closest to the secondary transfer position.

[0015] In the sixth aspect of this disclosure, the image forming apparatus is an image forming apparatus of the fourth aspect, in which the reference color is black.

[0016] A program according to a seventh aspect of this disclosure causes a computer to perform the following steps: when the temperature difference between the temperature detected by a first temperature sensor positioned to detect the temperature around the first image forming unit and the temperature detected by a second temperature sensor positioned to detect the temperature around the second image forming unit positioned adjacent to the first image forming unit is greater than or equal to a preset first threshold, the program forms a pattern image on a transport belt using all the image forming parts of the first image forming unit and the second image forming unit; and when the program forms a positional misalignment of the toner image formed by the first image forming unit and the second image forming unit using the detection results of the detection device. [Effects of the Invention]

[0017] According to the image forming apparatus of the first embodiment of this disclosure, the positional misalignment of the toner image formed by two image forming units can be suppressed compared to the case in which the positional misalignment is adjusted based on the temperature at one location within the apparatus.

[0018] According to the image forming apparatus of the second aspect of this disclosure, the adjustment time for positional misalignment can be shortened compared to the case in which a pattern image is formed by all image forming sections of two image forming units.

[0019] According to the image forming apparatus of the third aspect of this disclosure, the adjustment time for positional misalignment can be shortened compared to the case in which a pattern image is formed by all image forming sections of two image forming units.

[0020] According to the image forming apparatus of the fourth aspect of this disclosure, the accuracy of positional misalignment can be improved compared to the case in which no reference color is used.

[0021] According to the image forming apparatus of the fifth aspect of the present disclosure, the adjustment accuracy of misalignment can be improved as compared with the case where the image forming unit closest to the secondary transfer position is not used as the reference color.

[0022] According to the image forming apparatus of the sixth aspect of the present disclosure, the adjustment accuracy of misalignment can be improved as compared with the case where an image forming unit of a color with high reflectance is used.

[0023] According to the program of the seventh aspect of the present disclosure, the misalignment of the image formation positions of the toner images formed by the two image forming units can be suppressed as compared with the case where misalignment adjustment is performed based on the temperature at one location in the apparatus. <000​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0026] [Image forming apparatus] Figure 1 shows the configuration of an image forming apparatus 10, which is one embodiment of the present disclosure.

[0027] As shown in Figure 1, the image forming apparatus 10 includes a storage section 12 for storing PP paper, a transport section 11 for transporting the PP paper along a transport path 19, and image forming units 30 and 50 for forming toner images to be transferred to the PP paper. Image forming unit 30 is used as the first image forming unit. Image forming unit 50 is used as the second image forming unit.

[0028] The storage section 12 is retractable from the main body 10A of the image forming apparatus 10, and contains PP paper.

[0029] The transport unit 11 is equipped with, in order from the upstream side in the transport direction, a discharge roll 13, a transport roll 14, a pair of resist rolls 15, a transport belt device 20, a fixing device 18, and a discharge roll 17, etc.

[0030] The delivery roll 13 sends the PP paper stored in the storage section 12 to the transport path 19 that constitutes the transport section 11. The transport roll 14 transports the PP paper along the transport path 19.

[0031] The resist roll pair 15 transports the PP paper conveyed by the transport roll 14 to the downstream secondary transfer position TJ2, which will be described later. This resist roll pair 15 sandwiches the PP paper between the resist roll 15A and the pinch roll 15B and transports the PP paper downstream in the transport direction.

[0032] The conveyor belt device 20 transfers the toner image formed by the image forming units 30 and 50 onto the PP paper while transporting the PP paper downstream along the transport path 19. Details of the conveyor belt device 20 will be described later.

[0033] The fixing device 18 has a pair of fixing rolls 16, and heats and pressurizes the PP paper on which the toner image has been transferred as it passes between the pair of fixing rolls 16, thereby fixing the toner image to the PP paper.

[0034] The discharge roll 17 discharges the PP paper, on which the toner image has been fixed by the fuser unit 18, to the discharge unit 9.

[0035] The image forming unit 30 and the image forming unit 50 are arranged adjacent to each other. In this embodiment, the image forming unit 50 is positioned above the image forming unit 30. From another perspective, the image forming unit 50 is positioned downstream of the image forming unit 30 in the paper transport direction.

[0036] The image forming unit 30 forms toner images of special colors other than the basic colors, such as yellow, magenta, cyan, and black. The image forming unit 30 comprises four image forming sections 32 and an intermediate transfer belt 40, which serves as an intermediate transfer body to which the toner images formed by the four image forming sections 32 are first transferred. The intermediate transfer belt 40 is endless and is mounted so as to be rotatable counterclockwise when viewed from the front in Figure 1, and onto which the toner images formed by the four image forming sections 32 are transferred.

[0037] The image forming unit 32 comprises an image forming unit 32P that forms a special pink toner image, an image forming unit 32S that forms a silver toner image, an image forming unit 32G that forms a gold toner image, and an image forming unit 32Gr that forms a special green toner image. These four image forming units 32 are arranged in the order of image forming unit 32P, image forming unit 32S, image forming unit 32G, and image forming unit 32Gr, starting from the upstream side (closer to the support roll 44 described later) in the direction of rotation of the intermediate transfer belt 40. Hereafter, the upstream side in the direction of rotation of the intermediate transfer belt 40 will be referred to as the "upstream side in the direction of rotation," and the downstream side in the direction of rotation will be referred to as the "downstream side in the direction of rotation." In other words, in the image forming unit 32, the image forming unit 32Gr is located furthest downstream in the direction of rotation. Furthermore, in the image forming unit 32, the image forming unit 32Gr is located closest to the secondary transfer position TJ2.

[0038] Note that P, S, G, and Gr are omitted in descriptions where it is not necessary to distinguish between them.

[0039] As shown in Figure 2, the image forming unit 32 includes a photoreceptor 33, a charging member 34 that charges the surface of the photoreceptor 33, an exposure device 35 that irradiates the charged photoreceptor 33 with exposure, and a developing device 36 that develops the electrostatic latent image formed by the exposure and visualizes it as a toner image. The developing device 36 has a developing roll 39 to which a developing bias is applied.

[0040] Furthermore, primary transfer rolls 37P, 37S, 37G, and 37Gr are positioned opposite each photoreceptor 33 across the intermediate transfer belt 40 to transfer the toner image formed by the image forming unit 32 to the intermediate transfer belt 40. The intermediate transfer belt 40 is wrapped around a support roll 44 that supports the intermediate transfer belt 40 and a backup roll 42 that is positioned in the upstream secondary transfer unit 74, which will be described later. The primary transfer unit 70 is composed of the photoreceptor 33, the primary transfer rolls 37, and the intermediate transfer belt 40. The positions between the photoreceptors 33P, 33S, 33G, and 33Gr and the intermediate transfer belt 40 are designated as primary transfer positions TP1, TS1, TG1, and TGr1, respectively.

[0041] The image forming unit 50 has the same configuration as the aforementioned image forming unit 30, except that it forms images of different colors. The image forming unit 50 forms toner images of basic colors such as yellow, magenta, cyan, and black.

[0042] The image forming unit 50 comprises four image forming sections 52 and an intermediate transfer belt 60. The intermediate transfer belt 60 is mounted so as to be rotatable counterclockwise when viewed from the front in Figure 1, and onto which the toner image formed by the four image forming sections 52 is transferred.

[0043] As shown in Figure 2, the image forming section 52 has the same configuration as the image forming section 32 of the image forming unit 30, except that the color being formed is different. The intermediate transfer belt 60 and the primary transfer roll 57 (described later) also have the same configuration as the intermediate transfer belt 40 and primary transfer roll 37 of the image forming unit 30. Furthermore, the other components constituting the image forming unit 50 are the same as those of the image forming unit 30.

[0044] The image forming unit 52 comprises an image forming unit 52Y that forms a yellow toner image, an image forming unit 52M that forms a magenta toner image, an image forming unit 52C that forms a cyan toner image, and an image forming unit 52K that forms a black toner image. The four image forming units 52 are arranged in the order of image forming unit 52Y, image forming unit 52M, image forming unit 52C, and image forming unit 52K, starting from the upstream side in the rotation direction (the side closer to the support roll 64, which will be described later). In other words, in the image forming unit 52, the image forming unit 52K is located on the downstream side in the rotation direction. Also, in the image forming unit 52, the image forming unit 52K is located at the position closest to the secondary transfer position TK2.

[0045] Note that Y, M, C, and K are omitted in descriptions where it is not necessary to distinguish between them.

[0046] The image forming unit 52 includes a photoreceptor 53, a charging member 54, an exposure device 55, and a developing device 56. The developing device 56 has a developing roll 59 to which a developing bias is applied.

[0047] Furthermore, primary transfer rolls 57Y, 57M, 57C, and 57K are positioned opposite each photoreceptor 53 across the intermediate transfer belt 60. The intermediate transfer belt 60 is wound around a support roll 64 and a backup roll 62 located in the downstream secondary transfer section 76, which will be described later. The primary transfer section 72 is composed of the photoreceptors 53, the primary transfer rolls 57, and the intermediate transfer belt 60. The positions between the photoreceptors 53Y, 53M, 53C, and 53K and the intermediate transfer belt 60 are designated as primary transfer positions TY1, TM1, TC1, and TK1, respectively.

[0048] In the image forming unit 30, a first temperature sensor 100 is positioned between the image forming unit 32Gr, which is closer to the secondary transfer position TJ2 than the other image forming units 32P, 32S, and 32G, and the transport belt 21. The first temperature sensor 100 is configured to detect the ambient temperature around the image forming unit 30. In addition, a second temperature sensor 200 is positioned between the image forming unit 50, which is closer to the secondary transfer position TK2 than the other image forming units 52Y, 52M, and 52C, and the transport belt 21. The second temperature sensor 200 is configured to detect the ambient temperature around the image forming unit 50.

[0049] Next, we will describe the details of the conveyor belt device 20.

[0050] As shown in Figure 1, the conveyor belt device 20 includes an endless conveyor belt 21, support rolls 22 and 23 that support the conveyor belt 21, and secondary transfer rolls 24 and 25 positioned opposite the backup rolls 42 and 62, with the intermediate transfer belts 40 and 60 in between.

[0051] The transport belt 21 is configured to transport paper to secondary transfer positions TJ2 and TK2 where toner images formed on the intermediate transfer belts 40 and 60 of the image forming units 30 and 50 are secondarily transferred. Furthermore, the transport belt 21 is configured so that when the positional adjustment process is performed, the toner images formed on the intermediate transfer belts 40 and 60 of the image forming units 30 and 50 are secondarily transferred.

[0052] The secondary transfer roll 24, with the paper PP and transport belt 21 sandwiched between it and the backup roll 42, secondarily transfers the toner image formed on the intermediate transfer belt 40 of the image forming unit 30 to the paper PP. Similarly, the secondary transfer roll 25, with the paper PP and transport belt 21 sandwiched between it and the backup roll 62, secondarily transfers the toner image formed on the intermediate transfer belt 60 of the image forming unit 50 to the paper PP.

[0053] The secondary transfer section 74 includes a backup roll 42, a secondary transfer roll 24, and an intermediate transfer belt 40. The secondary transfer section 76 includes a backup roll 62, a secondary transfer roll 25, and an intermediate transfer belt 60.

[0054] A transfer bias is applied to the secondary transfer rolls 24 and 25, respectively.

[0055] Furthermore, the space between the intermediate transfer belt 40 and the transport belt 21 of the image forming unit 30 is defined as secondary transfer position TJ2, and the space between the intermediate transfer belt 60 and the transport belt 21 of the image forming unit 50 is defined as secondary transfer position TK2. Note that secondary transfer position TK2 is the furthest downstream secondary transfer position.

[0056] Furthermore, the conveyor belt device 20 is equipped with a belt cleaning device 78 for cleaning the conveyor belt 21. The belt cleaning device 78 performs cleaning on the downstream side of the paper conveying direction of the furthest downstream secondary transfer position TK2 and downstream of the detection device 150, which will be described later. The position on the conveyor belt 21 that is cleaned by the belt cleaning device 78 is referred to as the cleaning position CL.

[0057] Here, as shown in Figure 3(C), each image forming section 32 of the image forming unit 30 and each image forming section 52 of the image forming unit 50 form a pattern image BC for positional misalignment adjustment processing using each color toner.

[0058] The pattern image BC includes toner images of eight colors: yellow (Y), magenta (M), cyan (C), black (K), spot pink (P), silver (S), gold (G), and spot green (Gr). The symbols Y, M, C, K, P, S, G, and Gr written after the pattern image BC represent the toner colors, and these are omitted when distinction is not necessary. All pattern images BC for each color have the same shape and include horizontal lines and diagonal lines extending in the main scanning direction (up and down in the figure) of the image forming units 30 and 50.

[0059] The pattern image BC consists of three rows of patterns extending in the sub-scanning direction (left-right direction in the figure) of the image forming units 30 and 50. The pattern in each row is the same, with pattern images BCK (black, which is the reference color) and pattern images BC (non-black) arranged alternately. In addition, each pattern image is arranged at equal intervals.

[0060] In this embodiment, the pattern images BCP, BCS, BCG, and BCGr for misalignment adjustment processing are formed on the intermediate transfer belt 40. Additionally, the pattern images BCY, BCM, BCC, and BCK for misalignment adjustment processing are formed on the intermediate transfer belt 60. Finally, each of these is secondarily transferred to the conveyor belt 21.

[0061] As shown in Figure 1, the detection device 150 is located near the upper end of the conveyor belt 21. The detection device 150 is located downstream of the secondary transfer positions TJ2 and TK2 in the conveying direction in which the PP paper is conveyed by the conveyor belt 21. The detection device 150 is located downstream of the furthest downstream secondary transfer position TK2 in the paper conveying direction and upstream of the belt cleaning device 78 in the paper conveying direction.

[0062] The detection device 150 is configured to detect a pattern image BC formed by toner images that have been secondarily transferred to the transport belt 21 at the downstream side of the paper transport direction of the secondary transfer position TK2 and the upstream side of the paper transport direction of the cleaning position CL.

[0063] In other words, the detection device 150 is positioned to detect the pattern image BC downstream of the furthest downstream secondary transfer unit 76 in the paper transport direction. In other words, the detection device 150 is positioned to detect all the pattern images BC formed by all the image forming units 32P, 32S, 32G, 32Gr, 52Y, 52M, 52C, and 52K.

[0064] The detection device 150 of this embodiment includes three detection units 150A, 150B, and 150C that are spaced apart along the axial direction, or in other words, the width direction of the conveyor belt 21 (also called the paper width direction or main scanning direction) (see Figure 3(C)). The pattern image BC is formed in three rows corresponding to the positions of the detection units 150A, 150B, and 150C.

[0065] In this way, by using three rows of pattern images BC extending in the sub-scanning direction, positional misalignments at three locations in the main scanning direction (for example, both ends and the center) can be adjusted independently.

[0066] The pattern image BC for positional misalignment adjustment processing is formed as follows. First, as shown in Figure 3(A), the pattern images BCP, BCS, BCG, and BCGr are first transferred to the intermediate transfer belt 40 by the image forming unit 30.

[0067] Furthermore, as shown in Figure 3(B), the image forming unit 50 first transfers multiple pattern images BCK, which will be the reference color, to the intermediate transfer belt 60 so that when they are secondarily transferred to the conveyor belt 21, the pattern images BCP, BCS, BCG, and BCGr are arranged between the multiple pattern images BCK. Then, the pattern images BCY, BCM, and BCC are first transferred to the intermediate transfer belt 60 so that they are arranged between the multiple pattern images BCK.

[0068] Finally, as shown in Figure 3(C), the pattern images BC that have been primary transferred to the intermediate transfer belts 40 and 60 are secondary transferred to the transport belt 21 to become pattern images BC for positional misalignment adjustment. That is, pattern images BC of other colors are formed between multiple pattern images BCK of a predetermined reference color, for example, black. In this way, by using a black pattern image BCK, which is closest to the downstream secondary transfer position TK2 and has low reflectivity, as the reference color, the accuracy of positional misalignment adjustment can be improved.

[0069] [Control device] Next, using Figure 4, we will describe the control device 80 that controls the operation of the image forming apparatus 10.

[0070] As shown in Figure 4, the control device 80 is electrically connected to the image forming unit 30, the image forming unit 50, the detection device 150, the transport unit 11, the communication unit 90, the first temperature sensor 100, and the second temperature sensor 200, among others.

[0071] As shown in Figure 4, the control device 80 includes a CPU (Central Processing Unit) 81, ROM (Read Only Memory) 82, RAM (Random Access Memory) 83, a storage device 85 such as a hard disk drive, and an input / output interface (abbreviated as I / O) 84 that inputs and outputs data to and from each device via a network. These components are connected to each other via a control bus.

[0072] Here, ROM 82 stores an image formation control program (not shown) that is to be executed by CPU 81. The CPU 81 then reads the image formation control program (not shown) from ROM 82 and loads it into RAM 83, thereby executing the printing process according to the image formation control program (not shown).

[0073] Furthermore, I / O84 is connected to the image forming unit 30, image forming unit 50, detection device 150, transport unit 11, communication unit 90, first temperature sensor 100, and second temperature sensor 200, among others. The communication unit 90 is an interface for data communication between a terminal device such as a personal computer and the image forming apparatus 10.

[0074] The storage device 85 stores the installation positions of the image forming sections 32 and 52 for each color in the image forming units 30 and 50. Furthermore, when a positional misalignment adjustment process is performed, the storage device 85 stores the amount of misalignment and the correction amount used during the adjustment process. Also, as shown in Figure 5, when a positional misalignment adjustment process is performed, the storage device 85 stores the temperature detected by the first temperature sensor 100 and the second temperature sensor 200 at the time of the adjustment process (referred to as the previous temperature), and the temperature detected by the first temperature sensor 100 and the second temperature sensor 200 at the time of power-on or printing start (referred to as the current temperature). The storage device 85 is used as memory.

[0075] The control device 80 performs various controls to form toner images on the intermediate transfer belts 40 and 60 using the image forming sections 32 and 52 of each color in the image forming units 30 and 50.

[0076] Furthermore, the control device 80 controls the development bias applied to the development rolls 39 and 59 of the development devices 36 and 56, respectively. In addition, the control device 80 controls the transfer bias applied to the secondary transfer rolls 24 and 25, respectively.

[0077] Furthermore, the control device 80 controls the supply timing, supply time, and supply amount of toner for each color from each color toner cartridge to the developing devices 36 and 56.

[0078] Furthermore, the control device 80 calculates the temperature difference between the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200. Then, according to the calculated temperature difference, the control device 80 forms a pattern image on the conveyor belt 21 using the image forming sections of each color in the image forming unit 30 and / or the image forming unit 50.

[0079] Here, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it could be A alone, or B alone, or a combination of A and B.

[0080] Furthermore, the control device 80 calculates the temperature difference between the temperature detected by the first temperature sensor 100 when the previous misalignment adjustment was performed, as stored in the storage device 85, and the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing. The control device 80 also calculates the temperature difference between the temperature detected by the second temperature sensor 200 when the previous misalignment adjustment was performed, as stored in the storage device 85, and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing. Then, according to these calculated temperature differences, the control device 80 forms a pattern image on the transport belt 21 using the image forming sections of each color in the image forming unit 30 and / or image forming unit 50.

[0081] The control device 80 then detects the pattern image BC using the detection device 150. Based on the detection result, the control device 80 controls the timing of toner image formation on the intermediate transfer belts 40 and 60, specifically the exposure timing of each exposure device 35 and 55, the development bias applied to each development roll 39 and 59, and the transfer bias applied to the secondary transfer rolls 24 and 25. In other words, it uses the detection result of the detection device 150 to perform positional misalignment adjustment processing for the toner image formed by the image forming unit 30 and the image forming unit 50.

[0082] The control device 80 then stores the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200 in the storage device 85 during the positional misalignment adjustment process.

[0083] [Image forming process] Next, an overview of the image forming process in the image forming apparatus 10 will be described.

[0084] First, the control device 80 controls each image forming unit 32 so that a toner image is formed on the intermediate transfer belt 40 of the image forming unit 30. Similarly, the control device 80 controls each image forming unit 52 so that a toner image is formed on the intermediate transfer belt 60 of the image forming unit 50.

[0085] Specifically, the control device 80 applies a voltage to the charged members 34 and 54, and the charged members 34 and 54 charge the surfaces of the photoreceptors 33 and 53 to a predetermined potential. Subsequently, based on the image data acquired via the communication unit 90, the control device 80 irradiates the surfaces of the photoreceptors 33 and 53, which have been charged by the charged members 34 and 54, with exposure devices 35 and 55 to form an electrostatic latent image. As a result, an electrostatic latent image corresponding to the image data is formed on the surfaces of the photoreceptors 33 and 53.

[0086] Next, the control device 80 develops the electrostatic latent image formed by the exposure devices 35 and 55 using the developing devices 36 and 56, and visualizes it as a toner image. Furthermore, the control device 80 uses the primary transfer rolls 37 and 57 to transfer the toner images formed on the surfaces of the photoreceptors 33 and 53 of each color onto the intermediate transfer belts 40 and 60.

[0087] In this way, the image forming unit 30 forms a toner image on the intermediate transfer belt 40 by superimposing, for example, special pink (P), silver (S), gold (G), and special green (Gr) toners. Similarly, the image forming unit 50 forms a toner image on the intermediate transfer belt 60 by superimposing, for example, yellow (Y), magenta (M), cyan (C), and black (K) toners.

[0088] Here, the PP paper, which has been sent from the storage unit 12 to the transport path 19 by the delivery roll 13, is sent to the secondary transfer position TJ2 after the transport timing is adjusted by the register roll pair 15 based on the control of the control device 80. At this secondary transfer position TJ2, the PP paper is transported between the backup roll 42 and the secondary transfer roll 24, and the toner image on the outer surface of the intermediate transfer belt 40 is transferred to the PP paper. The PP paper with the transferred toner image is then transported downstream in the transport direction to the secondary transfer position TK2 downstream in the transport direction.

[0089] At this time, the control device 80 adjusts the timing of starting image formation so that the toner image formed on the intermediate transfer belt 60 of the image forming unit 50 is superimposed and transferred onto the toner image on the PP paper that has been transported from the upstream side in the transport direction.

[0090] The PP paper, onto which the toner images of each color formed by the image forming units 30 and 50 are superimposed and transferred, is fixed by the fixing roll pair 16 of the fixing device 18, and then discharged by the discharge roll 17 to the discharge section 9 located at the top of the main body 10A of the image forming device.

[0091] [Position misalignment adjustment process] Next, an example of the positional misalignment adjustment process in the image forming apparatus 10 will be explained using Figure 6.

[0092] First, in step S11, the control device 80 determines whether the temperature difference between the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200 is greater than or equal to a preset first threshold (for example, 5°C or more) when the image forming apparatus 10 is powered on or when printing starts. If the temperature difference between the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200 is greater than or equal to the first threshold, the process proceeds to step S14; otherwise, the process proceeds to step S12.

[0093] Then, in step S12, the control device 80 determines whether the temperature difference between the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200 is less than the first threshold, and whether the temperature difference between the temperature detected by the first temperature sensor 100 when the previous misalignment adjustment process was performed and the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing is greater than or equal to a preset second threshold (for example, 5°C or more). If the temperature difference between the temperature detected by the first temperature sensor 100 when the previous misalignment adjustment process was performed and the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing is greater than or equal to the preset second threshold, the process proceeds to step S13; otherwise, the process proceeds to step S16.

[0094] Then, in step S13, the control device 80 determines whether the temperature difference between the temperature detected by the first temperature sensor 100 when the previous misalignment adjustment process was performed (stored in the storage device 85) and the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing is greater than or equal to the second threshold, if the temperature difference between the temperature detected by the second temperature sensor 200 when the previous misalignment adjustment process was performed (stored in the storage device 85) and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is greater than or equal to a preset third threshold (for example, 5°C or more). If the temperature difference between the temperature detected by the second temperature sensor 200 when the previous misalignment adjustment process was performed and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is greater than or equal to the preset third threshold, the process proceeds to step S14; otherwise, the process proceeds to step S15.

[0095] Then, in step S14, the control device 80 uses all the image forming sections 32 and 52 of the image forming unit 30 and the image forming unit 50 to form the pattern image BC on the transport belt 21. Specifically, the image forming sections 32P, 32S, 32G, and 32Gr of the image forming unit 30 are used to first transfer the toner image onto the intermediate transfer belt 40. The image forming sections 52Y, 52M, 52C, and 52K of the image forming unit 50 are used to first transfer the toner image onto the intermediate transfer belt 60. The toner images first transferred onto the intermediate transfer belts 40 and 60 are then secondarily transferred onto the transport belt 21 to form the pattern image BC. At this time, as shown in Figure 3(C), a black pattern image BCK, which is the reference color, is formed between each of the pattern images BCP, BCS, BCG, BCGr, BCY, BCM, and BCC.

[0096] Then, in step S15, if the temperature difference between the temperature detected by the second temperature sensor 200 during the previous misalignment adjustment process stored in the storage device 85 and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is less than the third threshold, the image forming units 32P, 32S, 32G, and 32Gr of the image forming unit 30 are used to first transfer toner images onto the intermediate transfer belt 40, and the image forming unit 50's image forming unit 52K, which is the reference color, is used to first transfer toner images onto the intermediate transfer belt 60. Then, the toner images first transferred onto the intermediate transfer belts 40 and 60 are secondarily transferred onto the transport belt 21 to form the pattern image BC. At this time, as shown in Figure 7(A), a black pattern image BCK, which is the reference color, is formed between each of the pattern images BCP, BCS, BCG, and BCGr. At this time, any of the image forming units 32 of the image forming unit 30 may be used as the reference color. For example, if a special green color is used as the reference color, the image forming unit 30 alone is used to form a pattern image BCGr of the special green color, which is the reference color, between the pattern images BCP, BCS, and BCG, respectively.

[0097] Then, in step S16, the control device 80 determines whether the temperature difference between the temperature detected by the first temperature sensor 100 when the previous misalignment adjustment process was performed (stored in the storage device 85) and the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing is less than a preset second threshold, and whether the temperature difference between the temperature detected by the second temperature sensor 200 when the previous misalignment adjustment process was performed (stored in the storage device 85) and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is greater than or equal to a preset third threshold. If the temperature difference between the temperature detected by the second temperature sensor 200 when the previous misalignment adjustment process was performed and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is greater than or equal to a preset third threshold, the process proceeds to step S17. If it is less than the third threshold, the process ends without performing the misalignment adjustment process.

[0098] Then, in step S17, if the temperature difference between the temperature detected by the second temperature sensor 200 when the previous misalignment adjustment process was performed, which is stored in the storage device 85, and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is greater than or equal to the third threshold, the control device 80 uses the image forming sections 52Y, 52M, 52C, and 52K of the image forming unit 50 to transfer toner images onto the intermediate transfer belt 60, respectively, and then transfers the toner images transferred onto the intermediate transfer belt 60 to the transport belt 21, thereby forming the pattern image BC. At this time, as shown in Figure 7(B), a black pattern image BCK, which is the reference color, is formed between each of the pattern images BCY, BCM, and BCC.

[0099] Specifically, for example, if the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing is 21°C and the temperature detected by the second temperature sensor 200 is 22°C, the temperature difference between these two temperatures will be 1°C. In other words, if the first threshold is set to 5°C, the temperature difference between the temperature detected by the first temperature sensor 100 and the temperature detected by the second temperature sensor 200 will be less than the first threshold.

[0100] Furthermore, if the temperature detected by the first temperature sensor 100 during the previous misalignment adjustment process, which is stored in the storage device 85, was 25°C, and the temperature detected by the first temperature sensor 100 at the time of power-on or start of printing is 21°C, then the temperature difference between these two temperatures is 4°C. In other words, if the second threshold is set to 5°C, the temperature difference between the temperature detected by the first temperature sensor 100 last time and this time will be less than the second threshold.

[0101] Furthermore, the control device 80 will determine that if the temperature detected by the second temperature sensor 200 during the previous misalignment adjustment process, which is stored in the storage device 85, was 28°C, and the temperature detected by the second temperature sensor 200 at the time of power-on or start of printing is 22°C, the temperature difference between these two temperatures will be 6°C. In other words, if the third threshold is set to 5°C, the temperature difference between the temperature detected by the second temperature sensor 200 last time and this time will be greater than or equal to the third threshold.

[0102] In this case, the control device 80 uses the image forming sections 52Y, 52M, 52C, and 52K of the image forming unit 50, where the temperature difference is greater than or equal to the third threshold, to first transfer toner images onto the intermediate transfer belt 60, and then secondarily transfers the toner images transferred onto the intermediate transfer belt 60 onto the transport belt 21 to form a pattern image BC.

[0103] Then, in step S18, the control device 80 performs positional misalignment adjustment processing based on the formed pattern image BC. Specifically, the control device 80 detects each of the formed pattern images BC with the detection device 150 and performs positional misalignment adjustment processing based on the detection results of the detection device 150.

[0104] Here, when performing the positional misalignment adjustment process between colors, the positional misalignment amount of the pattern images BC (other than black) is obtained using the black pattern image BCK (the reference color) as the reference. Then, a correction value is calculated from the positional misalignment amount with pattern image BCK, and the exposure timing of exposure units 35P, 35S, 35G, 35Gr, 55Y, 55M, 55C, and 55K is adjusted.

[0105] In other words, the control device 80 adjusts the positional misalignment so that the pattern images BCP, BCS, BCG, and BCGr of the image forming unit 30 are in predetermined positions and relative positions with respect to the pattern image BCK. Similarly, the control device 80 adjusts the positional misalignment so that the pattern images BCY, BCM, and BCC of the other colors of the image forming unit 50 are in predetermined positions and relative positions with respect to the pattern image BCK.

[0106] In this way, temperature sensors are placed around adjacent image forming units 30 and 50, and each image forming unit 32 and / or image forming unit 52 forms a pattern image BC and performs positional misalignment adjustment processing according to the temperature difference between the image forming units 30 and 50 and the temperature difference from the temperature at the time of the previous positional misalignment adjustment processing. This makes it possible to reduce the amount of positional misalignment caused by the temperature difference between the two image forming units 30 and 50.

[0107] Furthermore, compared to the case where all image forming units 32 and 52 always form a pattern image BC of all colors and perform positional misalignment adjustment processing, the reading time can be shortened, resulting in a reduction in positional misalignment adjustment time and improved adjustment efficiency. In addition, compared to the case where a pattern image of all colors is formed, the amount of toner consumed in the positional misalignment adjustment processing can be reduced.

[0108] Furthermore, the positional misalignment adjustment process may be performed by any method, not limited to the embodiments described above.

[0109] Furthermore, in this embodiment, the detection device 150 detects the pattern image BC that has been secondarily transferred to the conveyor belt 21, which improves the detection accuracy compared to detecting the pattern image BC that has been secondarily transferred to PP paper, which has different surface conditions depending on the material.

[0110] <Other forms> This disclosure is not limited to the embodiments described above.

[0111] For example, the above embodiment was described using a configuration in which the image forming unit 50 is positioned above the image forming unit 30, but it is not limited to this. The image forming unit 30 and the image forming unit 50 may be positioned adjacent to each other in the lateral direction.

[0112] Furthermore, in the above embodiment, the first temperature sensor 100 and the second temperature sensor 200 are provided around the image forming sections 32Gr and 52K, which are close to the secondary transfer positions TJ2 and TK2 of the respective image forming units, but the system is not limited to this. They should be provided in positions that can detect the temperature around the respective image forming units 30 and 50.

[0113] Furthermore, in the above embodiment, the detection device 150 for detecting the pattern image BC that has been secondarily transferred to the conveyor belt 21 is provided downstream of a plurality of secondary transfer positions TJ2 and TK2, but is not limited to this. The detection device 150 may also be provided at other locations.

[0114] Furthermore, a detection device may be provided to detect the pattern image BC between the downstream primary transfer positions TGr1, TK1 and the secondary transfer positions TJ2, TK2 in the intermediate transfer belts 40, 60.

[0115] Furthermore, although the above embodiment describes the use of a black pattern image BCK as the reference color when performing the positional misalignment adjustment process, it is not limited to this. Other colors may be used as the reference color.

[0116] Furthermore, the image forming unit 30 and 50 may use the image forming section of the least expensive color as the reference color. This reduces the consumption of toner for more expensive colors.

[0117] In addition, in the above embodiment, a pattern image BC may be formed for each image forming unit 30, 50 without using a reference color to detect the amount of displacement.

[0118] Furthermore, although the above embodiment describes the case where a positional misalignment adjustment process is performed using a pattern image BC, it is not limited to this. Color adjustments other than positional misalignment adjustment, such as density adjustment, may also be performed.

[0119] Furthermore, in the above embodiment, the detection device 150 was configured to detect the pattern image BC that was secondarily transferred to the conveyor belt 21, but it is not limited to this. The detection device 150 may also be configured to detect the pattern image BC that was secondarily transferred to the paper PP.

[0120] Furthermore, the configuration of the image forming apparatus is not limited to the configuration of the above embodiment, and various configurations are possible. Moreover, the present invention can be implemented in various forms without departing from the spirit of the invention.

[0121] Furthermore, in the above embodiment, the term "processor" refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPUs) and dedicated processors (e.g., GPUs: Graphics Processing Units, ASICs: Application Specific Integrated Circuits, FPGAs: Field Programmable Gate Arrays, programmable logic devices, etc.).

[0122] Furthermore, the operation of the processor in the above embodiments may not be performed by a single processor, but may be performed by multiple processors located in physically separate locations working together. Also, the order of the processor operations is not limited to the order described in each of the above embodiments, but may be changed as appropriate.

[0123] The technology disclosed herein can also be applied to programs and program products.

[0124] [Note] The following are preferred forms of this disclosure.

[0125] (((1))) A first image forming unit having a plurality of image forming units and an intermediate transfer body on which toner images formed by the plurality of image forming units are first transferred, A second image forming unit is arranged adjacent to the first image forming unit and has a plurality of image forming sections and an intermediate transfer body on which the toner images formed by the plurality of image forming sections are first transferred. A transport belt that transports paper to a secondary transfer position where the toner images formed on the intermediate transfer surfaces of the first image forming unit and the second image forming unit are secondarily transferred, A detection device is provided downstream of the two secondary transfer positions in the transport direction in which the paper is transported by the transport belt, and detects a pattern image formed by the toner image secondary transferred onto the transport belt. A first temperature sensor is positioned to detect the temperature around the first image forming unit, A second temperature sensor is positioned to detect the temperature around the second image forming unit, Equipped with a processor, The aforementioned processor, When the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is greater than or equal to a preset first threshold, all of the image forming units of the first image forming unit and the second image forming unit form a pattern image on the conveyor belt. Using the detection results of the detection device, the misalignment of the toner image formed by the first image forming unit and the second image forming unit is adjusted. Image forming apparatus.

[0126] (((2))) Equipped with memory, The memory stores the temperatures detected by the first temperature sensor and the second temperature sensor, respectively, at the time of the previous misalignment adjustment. The aforementioned processor, Even if the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is less than the first threshold, if the temperature difference between the temperature detected by the first temperature sensor when the previous misalignment adjustment was performed and the temperature detected by the first temperature sensor this time is greater than or equal to a preset second threshold, the plurality of image forming units of the first image forming unit will form a pattern image on the transport belt. Using the detection results of the detection device, the misalignment of the toner image formed by the first image forming unit is adjusted. The image forming apparatus described in (((1))).

[0127] (((3))) The aforementioned processor, If the temperature difference between the temperature detected by the second temperature sensor during the previous misalignment adjustment stored in the memory and the temperature detected by the second temperature sensor this time is greater than or equal to a preset third threshold, the plurality of image forming units of the second image forming unit form a pattern image on the conveyor belt. Using the detection results of the detection device, the misalignment of the toner image formed by the second image forming unit is adjusted. The image forming apparatus described in (((2))).

[0128] (((4))) The image forming apparatus according to (((1))), wherein the processor, when forming a pattern image on the transport belt with all the image forming sections of the first image forming unit and the second image forming unit, forms pattern images of other colors between predetermined reference color pattern images in the second image forming unit.

[0129] (((5))) The image forming unit used as the reference color is the image forming unit closest to the secondary transfer position, as described in (((4)))).

[0130] (((6))) The image forming apparatus according to (((4))), wherein the reference color is black.

[0131] (((7))) The steps include: forming a pattern image on a conveyor belt by all image forming sections of the first and second image forming units if the temperature difference between the temperature detected by a first temperature sensor positioned to detect the temperature around the first image forming unit and the temperature detected by a second temperature sensor positioned to detect the temperature around the second image forming unit positioned adjacent to the first image forming unit is greater than or equal to a preset first threshold; The steps include: adjusting the positional misalignment of the toner image formed by the first image forming unit and the second image forming unit using the detection results of the detection device; A program that causes a computer to execute something.

[0132] The effects of the configuration described below are explained below.

[0133] According to the image forming apparatus (((1))), the positional displacement of the toner image formed by the two image forming units can be suppressed compared to the case where the positional displacement is adjusted based on the temperature at one location within the apparatus.

[0134] According to the image forming apparatus of (((2))), the adjustment time for positional misalignment can be shortened compared to the case in which a pattern image is formed by all image forming sections of two image forming units.

[0135] According to the image forming apparatus of (((3))), the adjustment time for positional misalignment can be shortened compared to the case in which a pattern image is formed by all image forming sections of two image forming units.

[0136] According to the image forming apparatus of (((4))), the accuracy of positional misalignment adjustment can be improved compared to the case where a reference color is not used.

[0137] According to the image forming apparatus of (((5))), the accuracy of positional misalignment adjustment can be improved compared to the case in which the image forming section closest to the secondary transfer position is not used as the reference color.

[0138] According to the image forming apparatus of (((6))), the accuracy of positional misalignment adjustment can be improved compared to the case in which an image forming unit with a high reflectivity color is used.

[0139] According to the program in (((7))), the positional displacement of the toner image formed by the two image forming units can be suppressed compared to the case where the positional displacement is adjusted based on the temperature at one location within the apparatus. [Explanation of symbols]

[0140] 10 Image forming apparatus 21 Conveyor belt 30 Image forming unit 50 Image forming units 80 Control device 100 First temperature sensor 150 detection devices 200 Second temperature sensor

Claims

1. A first image forming unit having a plurality of image forming units and an intermediate transfer body on which toner images formed by the plurality of image forming units are first transferred, A second image forming unit is arranged adjacent to the first image forming unit and includes a plurality of image forming sections and an intermediate transfer body on which toner images formed by the plurality of image forming sections are first transferred. A transport belt that transports paper to a secondary transfer position where the toner images formed on the intermediate transfer surfaces of the first image forming unit and the second image forming unit are secondarily transferred, A detection device is provided downstream of the two secondary transfer positions in the transport direction in which the paper is transported by the transport belt, and detects a pattern image formed by the toner image secondary transferred onto the transport belt. A first temperature sensor is positioned to detect the temperature around the first image forming unit, A second temperature sensor is positioned to detect the temperature around the second image forming unit, Equipped with a processor, The aforementioned processor, When the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is greater than or equal to a preset first threshold, all of the image forming units of the first image forming unit and the second image forming unit form a pattern image on the conveyor belt. Using the detection results of the detection device, the misalignment of the toner image formed by the first image forming unit and the second image forming unit is adjusted. Image forming apparatus.

2. Equipped with memory, The memory stores the temperatures detected by the first temperature sensor and the second temperature sensor, respectively, at the time of the previous misalignment adjustment. The aforementioned processor, Even if the temperature difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor is less than the first threshold, if the temperature difference between the temperature detected by the first temperature sensor when the previous misalignment adjustment was performed and the temperature detected by the first temperature sensor this time is greater than or equal to a preset second threshold, the plurality of image forming units of the first image forming unit will form a pattern image on the conveyor belt. Using the detection results of the detection device, the misalignment of the toner image formed by the first image forming unit is adjusted. The image forming apparatus according to claim 1.

3. The aforementioned processor, If the temperature difference between the temperature detected by the second temperature sensor during the previous misalignment adjustment stored in the memory and the temperature detected by the second temperature sensor this time is greater than or equal to a preset third threshold, the multiple image forming units of the second image forming unit form a pattern image on the conveyor belt. Using the detection results of the detection device, the misalignment of the toner image formed by the second image forming unit is adjusted. The image forming apparatus according to claim 2.

4. The image forming apparatus according to claim 1, wherein the processor, when forming a pattern image on the transport belt using all the image forming sections of the first image forming unit and the second image forming unit, forms pattern images of other colors between predetermined reference color pattern images in the second image forming unit.

5. The image forming apparatus according to claim 4, wherein the image forming unit used as the reference color is the image forming unit closest to the secondary transfer position.

6. The image forming apparatus according to claim 4, wherein the reference color is black.

7. The steps include: forming a pattern image on a conveyor belt by all image forming sections of the first and second image forming units if the temperature difference between the temperature detected by a first temperature sensor positioned to detect the temperature around the first image forming unit and the temperature detected by a second temperature sensor positioned to detect the temperature around the second image forming unit positioned adjacent to the first image forming unit is greater than or equal to a preset first threshold; The steps include adjusting the positional misalignment of the toner image formed by the first image forming unit and the second image forming unit using the detection results of the detection device, A program that causes a computer to execute something.

Images