Image forming device

Abstract

To deliver a recording medium accurately to a hold position with respect to a hold member in circulation as compared with a configuration in which the recording medium is delivered to the hold position based on position information of the hold member in circulation.SOLUTION: An image forming apparatus comprises: a plurality of rotary members to rotate; a circulation member that is formed annular and stretched over the plurality of rotary members so as to circulate with rotation of the rotary members; a holding member that is attached in an attaching portion of the circulation member and rotates together with the circulation member so as to hold a recording medium in a region where the attaching portion contacts one rotary member; an image forming unit that forms an image on the recording medium in an image forming position on a circulation path of the circulation member; a delivery unit that delivers the recording medium to a holding position where the holding member holds the recording medium; detection means that detects a rotation of the one rotary member; and a control unit that controls a delivery of the recording medium to the holding position by the delivery unit based on detection information detected at the detecting means.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Patent document 1 discloses an image forming apparatus comprising: a rotating body having a gripper provided on its surface for gripping a printing medium at a specific rotational position on the surface; a transport unit that transports the printing medium toward the specific rotational position; a printing unit that prints on the printing medium gripped by the gripper; a reading unit that reads an image of the printing medium printed by the printing unit; a calculation unit that calculates a correction amount for the amount of transport of the printing medium by the transport unit based on the positional relationship between the gripper and the leading edge of the printing medium in the transport direction indicated by the image read by the reading unit; a correction unit that calculates a correction speed at which the printing medium is transported by the transport unit based on the correction amount; and a change unit that changes the speed at which the printing medium is transported by the transport unit to the correction speed determined by the correction unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-49830 Summary of the Invention [Problem to be solved by the invention]

[0004] The image forming device may be configured to include a plurality of rotating members such as rotating sprockets, a circulating member such as a chain that is wrapped around the plurality of rotating members and rotates as the rotating members rotate, a holding member that is attached to the circulating member and rotates together with the circulating member to hold a recording medium such as paper, an image forming unit that forms an image on the recording medium at an image forming position on the circular path of the circulating member, a sending unit that sends the recording medium to the holding position where the holding member holds the recording medium, and a control unit that controls the sending unit to send the recording medium to the holding position based on position information of the holding member as it rotates.

[0005] In the above configuration, the timing of feeding out the recording medium may vary due to the expansion and contraction and vibration of the rotating member such as a chain, and the recording medium may be fed out to a position that is shifted from the holding position of the rotating holding member.

[0006] The present invention aims to feed a recording medium to a holding position of a rotating holding member with high accuracy, compared to a configuration in which a recording medium is fed to a holding position based on position information of the rotating holding member. [Means for solving the problem]

[0007] The image forming apparatus of the first embodiment includes a plurality of rotating rotating members; a circularly shaped circumferential member that is wrapped around the plurality of rotating members and rotates as the rotating members rotate; a holding member that is attached to an attachment portion of the circumferential member, rotates together with the circumferential member, and holds a recording medium in an area where the attachment portion contacts one of the rotating members; an image forming unit that forms an image on the recording medium at an image forming position in the rotational path of the circumferential member; a sending unit that sends out the recording medium to the holding position where the holding member holds the recording medium; a detection means that detects the rotation of the one of the rotating members; and a control unit that controls the sending out of the recording medium to the holding position by the sending unit based on detection information detected by the detection means.

[0008] The image forming apparatus of the second aspect is the image forming apparatus of the first aspect, in which the control unit controls the feeding so that the recording medium reaches the holding position at the timing when the attachment portion is in contact with the one rotating member.

[0009] The image forming apparatus of a third aspect is the image forming apparatus of the second aspect, wherein the control unit controls the feeding so that the recording medium reaches the holding position at the same time that the holding member reaches the holding position.

[0010] An image forming apparatus of a fourth aspect is an image forming apparatus of any one of the first to third aspects, wherein the control unit controls the timing of image formation by the image forming unit based on information detected by the detection means.

[0011] The image forming apparatus of a fifth aspect is the image forming apparatus of the fourth aspect, a drum that rotates together with the one rotating member and on which the recording medium held by the holding member is wound; The image forming unit includes a transfer body having a transfer image formed on its outer periphery, and transferring the transfer image to the recording medium wound around the drum at the image forming position.

[0012] An image forming apparatus of a sixth aspect is an image forming apparatus of any one of the first to fifth aspects, wherein the detection means comprises a light-blocking member that rotates together with the one rotating member, and an optical detection unit that is fixed to an apparatus body having a support unit that supports the rotating member and detects the light-blocking member passing through an optical path.

[0013] An image forming apparatus of a seventh aspect is the image forming apparatus of any one of the first to third aspects, and includes a first rotating member as the one rotating member, a second rotating member among the plurality of rotating members that is located downstream of the first rotating member in the conveying direction of the recording medium, a drum that rotates together with the second rotating member and around which the recording medium held by the holding member is wound, and a transfer body that is included in the image forming unit, has a transfer image formed on its outer periphery, and transfers the transfer image to the recording medium wound around the drum at the image forming position. Equipped with.

[0014] An eighth aspect of the image forming apparatus is the seventh aspect of the image forming apparatus, and is provided with a first detection means as the detection means for detecting the rotation of the first rotating member and a second detection means for detecting the rotation of the second rotating member, and the control unit controls the timing of the image forming unit forming a transfer image on the outer periphery of the transfer body based on the detection information detected by the second detection means.

[0015] An image forming apparatus of a ninth aspect is the image forming apparatus of the eighth aspect, wherein the first detection means comprises a first light blocking member that rotates together with the first rotating member, and a first light detection unit that is fixed to an apparatus body having a first support unit that supports the first rotating member and detects the first light blocking member passing through an optical path; The second detection means includes a second light-shielding member that rotates together with the second rotating member, and a second optical detection unit that is fixed to the device body and has a second support unit that supports the second rotating member, and that detects the second light-shielding member passing through the optical path.

[0016] An image forming apparatus of a tenth aspect is an image forming apparatus of the eighth or ninth aspect, wherein the period in which the first detection means detects the rotation of the first rotating member is the same as the period in which the second detection means detects the rotation of the second rotating member. [Effects of the Invention]

[0017] According to the configuration of the first aspect, the recording medium can be fed to the holding position of the rotating holding member with higher accuracy than in a configuration in which the recording medium is fed to the holding position based on position information of the rotating holding member.

[0018] According to the configuration of the second aspect, the recording medium can be sent out with high accuracy to the holding position of the holding member while it is rotating, compared to a configuration in which the recording medium reaches the holding position before the attachment portion of the rotating member comes into contact with one of the rotating members.

[0019] According to the configuration of the third aspect, the recording medium can be sent out more accurately to the holding position of the rotating holding member, compared to a configuration in which the recording medium reaches the holding position before the holding member reaches the holding position.

[0020] According to the fourth aspect of the configuration, it is possible to reduce variation in the position of the image formed on the recording medium compared to a configuration in which an image is formed at an image forming position on the recording medium held by the holding member based on position information of the holding member during rotation.

[0021] According to the configuration of the fifth aspect, color misregistration can be suppressed when forming an image of multiple colors, compared to a configuration in which an image of multiple colors is formed on a recording medium at an image forming position by ejecting ink droplets.

[0022] According to the configuration of the sixth aspect, the replacement cycle of the parts can be extended compared to a configuration in which the rotation of one rotating member is detected by contact between parts.

[0023] According to the seventh aspect, the size of the rotary member can be reduced compared to a configuration in which the holding position and the image forming position are set around one rotary member.

[0024] According to the configuration of the eighth aspect, compared to a configuration in which a transfer image is formed on the outer periphery of a transfer body based on detection information from a first detection means, an image can be formed with high precision at the image formation position on a recording medium held by a rotating holding member.

[0025] According to the configuration of the ninth aspect, the replacement cycle of the parts can be extended, compared to a configuration in which the rotation of each of the first and second rotating members is detected by contact between the parts.

[0026] According to the configuration of the 10th aspect, it is easier for the control unit to control the timing of sending the recording medium to the holding position and the timing of forming an image on the recording medium, compared to a configuration in which the detection period of the first detection means and the detection period of the second detection means are offset. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a front view showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged view of the periphery of an image forming position of the image forming apparatus of FIG. [Figure 3] 2 is an enlarged view showing a state in which a paper sheet is held by a gripper of the image forming apparatus of FIG. 1. FIG. [Figure 4] 2A and 2B are cross-sectional views showing the opening and closing operation of a gripper of the image forming apparatus of FIG. 1. [Figure 5]2 is an enlarged view showing a position adjustment unit of the image forming apparatus of FIG. 1. [Figure 6] 3A, 3B, and 3C are enlarged views showing the operation of holding the leading edge of a sheet by a gripper of the image forming apparatus of FIG. 1. [Figure 7] FIG. 2 is a perspective view showing the structure of a main part of the image forming apparatus of FIG. [Figure 8] 2 is a front view showing the transport of paper and the operation of a gripper in the image forming apparatus of FIG. 1. FIG. [Figure 9] FIG. 2 is a front view of a main part of the image forming apparatus of FIG. [Figure 10] 2 is an enlarged view of a second rotating member of the image forming apparatus of FIG. 1 as viewed from the axial direction. [Figure 11] FIG. 2 is a block diagram of a main part of the image forming apparatus of FIG. [Figure 12] 2 is an explanatory diagram for explaining timing of paper feeding and image formation in the image forming apparatus of FIG. 1. FIG. [Figure 13] 10 is an enlarged view of the periphery of an image forming position of an image forming unit of an image forming apparatus according to another embodiment, corresponding to FIG. 2. FIG. [Figure 14] 10 is an enlarged view of the periphery of an image forming position of an image forming unit of an image forming apparatus according to another embodiment, corresponding to FIG. 2. FIG. [Figure 15] 15 is an explanatory diagram for explaining timing of paper feeding and image formation in the image forming apparatus of FIG. 14. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0028] An example of an image forming apparatus according to an embodiment of the present invention will be described.

[0029] An image forming apparatus according to one embodiment of the present invention will be described with reference to FIGS. 1 to 12. Note that the arrow UP shown in each figure is vertical and points upward from the apparatus. The arrow RH is horizontal and points to the right when facing the apparatus as shown in FIG. 1. The arrow FR is horizontal and points to the front when facing the apparatus as shown in FIG. 7. Furthermore, in the following description, when a vertical direction is specified without any precondition, it means the vertical direction of the device shown in Fig. 1. In the following description, when a horizontal direction is specified without any precondition, it means the left and right directions when facing the device shown in Fig. 1. Furthermore, in the following description, when a depth direction is specified without any precondition, it means the depth direction when facing the device shown in Fig. 1.

[0030] [Overall configuration of image forming device] First, a description will be given of the configuration of the image forming apparatus 10. Fig. 1 is a front view showing an outline of the image forming apparatus 10 according to this embodiment.

[0031] 1, image forming apparatus 10 includes unit 10A located on the right side of the drawing and unit 10B located on the left side of the drawing. Image forming apparatus 10 also includes a sprocket (not shown) provided on transport drum 31, a sprocket 35 provided on transfer drum 36, a sprocket 37 provided on delivery drum 60, a chain 49 as an example of a circulating member, a gripper 42 as an example of a holding member, image forming unit 11, a position adjustment unit 50 as an example of a sending unit, a first detection device 80 as an example of first detection means, a second detection device 90 as an example of second detection means, and control unit 16. These device components are included in unit 10A. Image forming apparatus 10 also includes a paper feed tray 38 as an example of a storage unit and a paper discharge tray 39 as an example of a discharge unit. These device components are included in unit 10B. In this embodiment, the sprocket (not shown) provided on the transport cylinder 31, the sprocket 35 provided on the transfer cylinder 36, and the sprocket 37 provided on the delivery cylinder 60 are examples of the plurality of rotating members.

[0032] (Image forming section) The image forming unit 11 has a function of forming an image on a recording medium, paper P, at an image forming position on the circulation path D of the chain 49, which will be described later. Specifically, it has a function of forming an image on the surface (outer peripheral surface) of a transfer belt 22, which will be described later, and transferring the formed image to the paper P at a transfer position T, which is an image forming position, thereby forming an image on the paper P. As shown in FIG. 2, the image forming unit 11 has multiple print heads 12 and a transfer unit 30. More specifically, the image forming unit 11 has multiple print heads 12 for each color. Note that the image forming unit 11 of this embodiment has print heads 12 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K).

[0033] The print head 12 has a function of forming an ink image on the surface (outer peripheral surface) of the transfer belt 22 by inkjet printing. Specifically, the multiple print heads 12 are configured to form ink images on the surface of the transfer belt 22 for each color.

[0034] Yellow (Y), magenta (M), cyan (C), and black (K) are the basic colors for outputting color images. In the following description, when there is no need to distinguish between the colors of the print head 12, it will simply be referred to as the "print head 12," and the symbols Y, M, C, and K that indicate the print head corresponding to each color may be omitted as appropriate.

[0035] The print heads 12Y, 12M, 12C, and 12K are basically similar in configuration except for the inks they use. As shown in Figure 2, the print heads 12Y, 12M, 12C, and 12K are arranged side by side along the horizontal portion of the transfer belt 22, downstream of the particle supply device 13 (described later) in the rotation direction of the transfer belt 22 (the direction indicated by the arrow X in Figure 2).

[0036] Here, the print heads 12Y, 12M, 12C, and 12K eject superimposed ink droplets of the colors Y, M, C, and K based on image information input to the image forming device 10 onto a transfer belt 22 having an ink receptive particle 13A layer (not shown) formed on its surface by ink receptive particles 13A supplied from the particle supply device 13. The ink droplets ejected from the print heads 12Y, 12M, 12C, and 12K are received by the ink receptive particle 13A layer and form an ink image on the outer periphery of the transfer belt 22. In other words, the image forming unit 11 forms an image on the surface (outer periphery) of the transfer belt 22.

[0037] The transfer unit 30 has a function of transferring an image (ink image) formed on the surface of the transfer belt 22 onto a sheet P. Specifically, as shown in Fig. 2, the transfer unit 30 includes the transfer belt 22 as an example of a transfer body, a plurality of rolls 32, a transfer roll 33, and a transfer cylinder 36 as an example of a cylinder. Furthermore, the transfer unit 30 includes an adhesive layer forming device 14, a particle supplying device 13, and a cleaner 15.

[0038] 2, the transfer belt 22 is endless and is wound around and stretched around a plurality of rolls 32 and a transfer roll 33 so as to assume an inverted triangular shape when viewed from the front (when viewed from the front side in the depth direction of the device). The transfer belt 22 rotates in the direction of arrow X when at least one of the plurality of rolls 32 is driven to rotate. On the outer periphery of the transfer belt 22, print heads 12 for each color, a particle supply device 13, an adhesive layer forming device 14, and a cleaner 15 are arranged.

[0039] The transfer roll 33 is disposed inside the transfer belt 22 .

[0040] The transfer cylinder 36 is disposed on the opposite side of the transfer roll 33 across the transfer belt 22. As shown in FIG. 7, the transfer cylinder 36 extends in the depth direction of the apparatus.

[0041] 7, the transfer cylinder 36 has a shaft portion 36A extending in the apparatus depth direction and a roll portion 36B serving as a cylindrical portion provided at the axially intermediate portion of the shaft portion 36A. The above-mentioned sprockets 35 are attached to both axial ends of the shaft portion 36A. In other words, the roll portion 36B of the transfer cylinder 36 is disposed between the pair of sprockets 35.

[0042] 2, a chain 49 is wound around the sprocket 35 of the transfer cylinder 36. Therefore, the transfer cylinder 36 rotates in accordance with the rotation of the chain 49.

[0043] A recess (not shown) capable of accommodating the gripper 42 is formed in the roll portion 36B of the transfer cylinder 36. This recess has a groove-like shape that extends in the axial direction (the same direction as the depth direction of the device) from one end to the other end of the roll portion 36B.

[0044] The transfer cylinder 36 also has a built-in heat source (not shown) and is configured to be able to heat the outer periphery.

[0045] The transfer cylinder 36 forms a nip area with the transfer roll 33, which pushes the transfer belt 22 and presses it against the transfer cylinder 36. In other words, the nip area is formed between the transfer cylinder 36 and the transfer belt 22. The transfer cylinder 36, which rotates following the rotation of the chain 49, rotates the transfer belt 22 in the nip area. The transfer cylinder 36 transfers the ink image formed on the transfer belt 22 to the paper P while rotating the transfer belt 22 in the nip area, with the paper P conveyed by the chain 49 and the gripper 42 sandwiched between the heated outer periphery and the transfer belt 22. The nip area formed between the transfer cylinder 36 and the transfer belt 22 is a transfer position T, which is an example of an image forming position. That is, in the image forming apparatus 10 of this embodiment, the ink image formed on the surface of the transfer belt 22 by the image forming unit 11 is transferred to the surface of the paper P wrapped around the transfer cylinder 36 at the transfer position T.

[0046] 2, the adhesive layer forming device 14 is disposed upstream of the particle supplying device 13 in the rotation direction of the transfer belt 22, in the horizontal portion of the transfer belt 22 oriented in an inverted triangle shape. In other words, the adhesive layer forming device 14 is disposed to the left of the particle supplying device 13. The adhesive layer forming device 14 stores an adhesive inside, and applies the adhesive to the outer peripheral surface of the rotating transfer belt 22 to form an adhesive layer (not shown). For example, glue, organic solvent, etc. can be used as the adhesive.

[0047] The particle supply device 13 is disposed on the horizontal portion of the transfer belt 22, downstream of the adhesive layer forming device 14 in the rotation direction of the transfer belt 22. In other words, the particle supply device 13 is disposed to the right of the adhesive layer forming device 14. The particle supply device 13 contains ink receptive particles 13A capable of receiving ink droplets therein, and supplies the ink receptive particles 13A to the transfer belt 22 on which the adhesive layer has been formed. As a result, the ink receptive particles 13A supplied to the transfer belt 22 by the particle supply device 13 are adhered to the adhesive layer by the adhesive force of the adhesive layer, and a layer of ink receptive particles 13A is formed on the transfer belt 22.

[0048] The ink receptive particle 13A layer formed on the transfer belt 22 comes into contact with the paper P sandwiched between the transfer belt 22 and the transfer cylinder 36 at the transfer position T, and is heated by the transfer cylinder 36, thereby being transferred to the paper P. At this time, if the ink receptive particle 13A layer has received ink droplets and an ink image has been formed on the ink receptive particle 13A layer, the ink image is transferred to the paper P together with the ink receptive particle 13A layer.

[0049] The cleaner 15 is disposed downstream of the transfer position T in the rotation direction of the transfer belt 22 and upstream of the adhesive layer forming device 14 in the rotation direction. The cleaner 15 includes a blade 15A that contacts the outer peripheral surface of the transfer belt 22. The cleaner 15 functions to remove, with the blade 15A, the adhesive layer, ink receiving particles 13A, and other foreign matter (for example, paper dust when the paper P is paper) remaining on the portion of the transfer belt 22 that has passed through the transfer position T (nip area) as the transfer belt 22 rotates.

[0050] As shown in FIG. 1, paper transport path A has a function of transporting paper P supplied from paper feed tray 38. Image forming apparatus 10 in this embodiment is equipped with multiple paper feed trays 38. Paper P supplied from paper feed tray 38 is transported along paper transport path A. It then passes through transfer position T and is discharged to paper discharge tray 39. Specifically, paper transport path A is configured to pass through unit 10B, unit 10A, and unit 10B in that order. As a result, paper P transported along paper transport path A is supplied from paper feed tray 38 arranged in unit 10B, passes through unit 10A, and is then returned to unit 10B.

[0051] Meanwhile, downstream of receiving position D2, which will be described later, paper transport path A branches off into direction change path B, which changes the transport direction of the paper. This direction change path B is configured to merge with paper transport path A further downstream in the transport direction. Note that the path between direction change path B and circular path D on paper transport path A is a merging path where the transport path for the front side of paper P and the transport path for the back side of paper P merge. Note that circular path D will be described later. Also, each transport path is configured by multiple paper transport rolls (not shown). These rolls transport paper P along each transport path.

[0052] As shown in FIG. 2, the image forming apparatus 10 also includes a fixing unit 40 downstream of the transfer position T in the conveyance direction of the paper P. The fixing unit 40 has a function of fixing, to the paper P, the ink image transferred to the paper P by the transfer unit 30. Specifically, as shown in FIG. 2, the fixing unit 40 includes a heating roll 43 as a heating unit that contacts the conveyed paper P to heat the paper P, and a transport drum 31 (not shown) as a pressure unit that sandwiches the paper P between the heating roll 43 and the fixing unit 40 and presses the paper P against the heating roll 43. The transport drum 31 and the heating roll 43 are disposed opposite each other with the paper conveyance path A described above between them. That is, the paper P to be fixed is conveyed to pass between the transport drum 31 and the heating roll 43.

[0053] The transport drum 31 has the function of pressing the paper P by sandwiching it between itself and the heating roll 43. Specifically, the transport drum 31 has a shaft portion (not shown) extending in the depth direction of the device, a roll portion (not shown) as a cylindrical portion provided in the axial middle portion of the shaft portion, and a recess (not shown) provided on the outer surface of the roll portion. Sprockets (not shown) around which the chain 49 is wound are attached to both axial ends of the shaft portion of the transport drum 31. In other words, the roll portion of the transport drum 31 is disposed between the pair of sprockets.

[0054] 2, a chain 49 is wound around a sprocket on the conveying drum 31. Therefore, the conveying drum 31 rotates in accordance with the rotation of the chain 49.

[0055] A recess (not shown) capable of accommodating gripper 42 is formed in the roll portion of conveying drum 31. This recess has a groove-like shape that extends in the axial direction (the same direction as the depth direction of the device) from one end to the other end of the roll portion of conveying drum 31.

[0056] Heating roll 43 has a function of heating paper P. Specifically, conveying drum 31 has a shaft portion (not shown) extending in the device depth direction, and a roll portion (not shown) as a cylindrical portion provided at the axial middle of the shaft portion.

[0057] The outer peripheral surface of the roll portion of heating roll 43 comes into contact with the outer peripheral surface of the roll portion of transport drum 31, thereby forming a nip region in which paper P is sandwiched between transport drum 31. The nip region formed between this transport drum 31 and heating roll 43 is receiving position D2, which is an example of an image receiving position.

[0058] (Basic image formation operation) Next, an outline of the basic operation of forming an image on paper P in image forming apparatus 10 will be described.

[0059] Various operations in the image forming apparatus 10 are performed by a control unit 16 built into the apparatus. When the control unit 16 receives an image formation command from outside, it operates the print head 12 of the image forming unit 11. The control unit 16 also sends image data that has been subjected to image processing in an image signal processing unit (not shown) to the image forming unit 11. The image forming unit 11 forms an ink image on the surface of a transfer belt 22. The ink image is then transferred from the transfer belt 22 to a sheet P at a transfer position T, forming an image on the sheet P.

[0060] During double-sided printing, the paper P that has passed through receiving position D2 (described later) is further redirected in its transport direction along direction-changing path B provided on the transport path. The paper P is then transported along transport path C, which includes multiple rollers (not shown), and is transported back to paper transport path A.

[0061] (sprocket) As shown in FIG. 2, a chain 49 is wound around the sprockets of the transport drum 31, the sprocket 35 of the transfer drum 36, and the sprocket 37 of the delivery drum 60. A predetermined tension is applied to the chain 49 by winding around these sprockets. As shown in FIG. 7, the sprockets 37 are provided on both axial ends of a connecting shaft 61 extending in the depth direction of the device. The delivery drum 60 is equipped with the connecting shaft 61 and a pair of sprockets 37. The sprockets 37, 35, and the sprockets of the transport drum 31 are arranged in this order from upstream to downstream in the paper transport direction. The sprocket 37 in this embodiment is an example of a first rotating member. The sprocket 35 in this embodiment is an example of a second rotating member.

[0062] (chain) Chain 49 has the function of conveying paper P held by grippers 42 in the circumferential direction of chain 49 (the direction indicated by arrow D in the figure) via grippers 42 attached to chain 49. Specifically, chain 49 is formed in a ring shape, and is wound around and tensioned by sprockets, sprockets 35, and sprockets 37 of conveying drum 31. More specifically, one chain 49 is wound around sprockets, sprockets 35, and sprockets 37 of conveying drum 31 located on the front side in the depth direction, and the other chain 49 is wound around sprockets, sprockets 35, and sprockets 37 of conveying drum 31 located on the rear side in the depth direction. In the following description, when simply referring to chain 49, this refers to a pair of chains 49 on the front and rear sides in the depth direction. Chain 49 is configured to rotate in accordance with the driving rotation of any one of the sprockets on conveying drum 31, sprocket 35, and sprocket 37. The sprocket that is driven to rotate may be any one of the sprockets on conveying drum 31, sprocket 35, and sprocket 37, and the sprocket that is not driven to rotate rotates in accordance with the driving rotation of chain 49.

[0063] 3, the chain 49 has a structure in which roller links 59, each of which is made up of a bush fitted with a freely rotating roller and a link plate, are connected by pin links 57. A plurality of grippers 42 are attached to the chain 49 at preset intervals.

[0064] (gripper) As shown in FIGS. 3 and 4, the gripper 42 is attached to the chain 49 and rotates together with the chain 49 to hold the paper sheet P. Specifically, as shown in FIG. 8, the gripper 42 holds the leading edge P1 (see FIG. 3) of the paper sheet P being conveyed in an area where the attachment portion of the chain 49 to which the gripper 42 is attached comes into contact with the sprocket 37, and assists in conveying the paper sheet P by rotating together with the chain 49. A plurality of grippers 42 are attached to the chain 49 at preset intervals. The chain 49 comes into contact with the sprocket 37 by meshing with the sprocket 37. That is, the attachment portion of the chain 49 also comes into contact with the sprocket 37 by meshing with the sprocket 37. Therefore, the engagement of the attachment portion of the chain 49 with the sprocket 37 can also be referred to as the contact of the attachment portion with the sprocket 37, and the meshing area can also be referred to as the contact area.

[0065] The gripper 42 includes a clip 44, a rectangular case 46 that covers the clip 44, and a shaft 48 that extends in the depth direction.

[0066] The clip 44 is fixed to the shaft 48 and configured to rotate together with the shaft 48. A plurality of clips 44 are provided on the shaft 48 at intervals in the axial direction of the shaft 48 (the same direction as the depth direction of the device) (see FIG. 3).

[0067] The longitudinal direction of the case 46 is the depth direction of the device, and the case 46 is held by a shaft 48. The case 46 is configured to rotate independently of the rotation of the clip 44. The case 46 is also configured to cover the clip 44 on two sides, the upstream and downstream sides in the paper transport direction, and the back surface of the paper. Note that the "back surface" here refers to the surface of the paper P on which an image is not formed. In this structure, the tip 45 of the clip 44 and the fixed claw 47 at the rear end of the case 46 are configured to be able to clamp the tip P1 of the paper P in the transport direction. Note that the reference numeral 47A in FIG. 4 denotes the tip of the fixed claw 47.

[0068] The shaft 48 is held at both ends in the depth direction by a pair of chains 49. As these chains 49 rotate, the shaft 48 fixed to the pair of chains 49 also rotates. As a result, the gripper 42 is held by the pair of chains 49 and rotates along a predetermined rotation path D (see FIG. 2).

[0069] 1, the circular path D of the chain 49 is arranged so as to partially overlap with the paper transport path A when viewed from the front of the image forming apparatus 10. Specifically, the circular path D is configured to overlap with the paper transport path A from the time it passes the point of contact with the paper transport path A on the outer periphery of the sprocket 37 until it passes through a receiving position D2, which will be described later.

[0070] At the start of the overlap between paper transport path A and circular path D, tip 45 of clip 44 and fixed claw 47 of case 46 come close to each other, and gripper 42 grips tip P1 of paper P. The holding position of gripper 42 for paper P on circular path D is transfer position D1 where paper P is transferred from paper transport path A to gripper 42.

[0071] At the end point of the overlap between the circular path D and the paper transport path A, the tip 45 of the clip 44 and the fixed claw 47 of the case 46 separate, releasing the tip P1 of the paper P. The release position of the gripper 42 for the paper P on the circular path D is the receiving position D2 where the paper P is received from the gripper 42 into the paper transport path A.

[0072] In this embodiment, the rotation speed of the gripper 42 and the rotation speed of each sprocket are the same.

[0073] (Position adjustment part) The position adjustment unit 50 has a function of sending out the paper P to a delivery position D1, which is a holding position where the gripper 42 holds the paper P. Specifically, as shown in FIG. 1, the position adjustment unit 50 is disposed on a junction path in the paper transport path A, which is provided between the direction change path B and the delivery position D1. As shown in FIG. 5, the position adjustment unit 50 includes transport rolls 51 and 52, registration rolls 55 and 56, and passage sensors 62 and 64. Each roll is disposed above or below the paper transport path A. The upper transport roll 51 and the lower transport roll 52, and the upper registration roll 55 and the lower registration roll 56 rotate in pairs to transport the paper P.

[0074] Each of the passage sensors 62, 64 detects the passing or non-passing state of the paper P being transported along the paper transport path A. The control unit 16 receives signals from the passage sensors 62, 64 and appropriately controls the operations of the transport rolls 51, 52 and the registration rolls 55, 56. Here, as shown in Fig. 5, when the leading edge P1 (see Fig. 3) of the paper P reaches the registration rolls 55, 56, the transport of the paper P temporarily stops, and the registration rolls 55, 56 are rotated at a set timing, so that the paper P is sent to the delivery position D1.

[0075] As shown in FIGS. 6A to 6C, the sheet P sent out from the position adjustment unit 50 is clamped on the circumference of the sprocket 37 in FIG. 5 by the fixed claw portion 47 of the case 46 of the gripper 42 and the tip portion 45 of the clip 44. The gripper 42 is fed while moving along the circular path D in synchronization with the transport timing of the leading edge P1 of the sheet P. At this time, as shown in FIG. 6A, the case 46 and the clip 44 are in an open state. Also, as shown in FIG. 6B, the gripper 42 moves along the circular path D in synchronization with the transport timing of the sheet P sent out from the position adjustment unit 50 to the delivery position D1, and the case 46 and the clip 44 gradually approach each other. Then, the tip portion 45 of the clip 44 lifts the leading edge P1 of the sheet P from the sheet transport path A. 6(C), the leading end P1 of the paper P is further lifted by the clip 44, and is transferred from the paper transport path A to the circular path D while being clamped between the fixed claw portion 47 of the case 46 and the leading end 45 of the clip 44. Thereafter, the paper P is transported along the circular path D by the gripper 42. The position where the paper P is transferred from the paper transport path A to the circular path D is defined as the transfer position D1.

[0076] 1, after being delivered to the circulation path D, the paper P is turned over along the outer periphery of the transfer cylinder 36. The paper P is then transported to a transfer position T provided on the outer periphery of the transfer cylinder 36. In other words, the paper P is configured to pass through the transfer position T in the process of being turned over along the circulation path and the outer periphery of the transfer cylinder 36.

[0077] When the paper P passes through the transfer position T, the surface facing the transfer roll 33 is the image forming surface, that is, the front surface. In other words, at the position adjustment unit 50 and the delivery position D1, the paper P is transported with the back surface, which is the non-image forming surface, facing upward.

[0078] After passing through the transfer position T, the paper sheet P is received from the circular path D onto the paper transport path A. The branch point between the circular path D and the paper transport path A is the receiving position D2. At the receiving position D2, the gripper 42 holding the leading edge P1 of the paper sheet P is released, and the paper sheet P is received from the circular path D onto the paper transport path A.

[0079] [Main components] Next, the main configuration of this embodiment will be described.

[0080] (First detection device) The first detector 80 has a function of detecting the rotation of the sprocket 37. Specifically, the first detector 80 detects the rotation period of the connecting shaft 61 to which the sprocket 37 is attached. As shown in FIG. 5 , the first detector 80 includes a first light-shielding member 82 that rotates with the sprocket 37 and a first light detector 84 that is fixed to a device body (in this embodiment, the housing of the unit 10A) that supports the sprocket 37 and detects the first light-shielding member 82 passing through (or blocking) the optical path. More specifically, the first light-shielding member 82 is plate-shaped and attached to the outer periphery of the connecting shaft 61 that rotates with the sprocket 37. Note that in this embodiment, the first light-shielding member 82 is attached to the axial end of the connecting shaft 61 closer to the sprocket 37, but this is not limiting. The first light detector 84 is an optical sensor. The first light detector 84 is disposed radially outward of the connecting shaft 61, and when the first light blocking member 82 passes on the optical path, it detects the first light blocking member 82 and transmits a detection signal to the control unit 16. In other words, the first light detector 84 detects the first light blocking member 82, which rotates together with the sprocket 37, with each rotation and transmits a detection signal to the control unit 16.

[0081] (Second detection device) The second detector 90 has a function of detecting the rotation of the sprocket 35. Specifically, the second detector 90 detects the rotation period of the shaft 36A to which the sprocket 35 is attached. As shown in FIG. 10 , the second detector 90 includes a second light-shielding member 92 that rotates with the sprocket 35 and a second light detector 94 that is fixed to a device body (in this embodiment, the housing of the unit 10A) that supports the sprocket 35 and detects the second light-shielding member 92 passing through (blocking) the optical path. More specifically, the second light-shielding member 92 is plate-shaped and attached to the outer periphery of the shaft 36A that rotates with the sprocket 35. Note that in this embodiment, the second light-shielding member 92 is attached to the shaft 36A closer to the axial end than the sprocket 35, but this is not limiting. The second light detector 94 is an optical sensor. The second light detector 94 is disposed radially outward of the connecting shaft 61, and when the second light blocking member 92 passes through the optical path, it detects the second light blocking member 92 and transmits a detection signal to the control unit 16. In other words, the second light detector 94 detects the second light blocking member 92, which rotates together with the sprocket 35, with each rotation and transmits a detection signal to the control unit 16.

[0082] Furthermore, the period in which first detector 80 detects the rotation of sprocket 37 is the same as the period in which second detector 90 detects the rotation of sprocket 35. Specifically, in this embodiment, the total number of teeth 129 of sprocket 37 is the same as the total number of teeth (not shown) of sprocket 35. As a result, the rotation period detected by first detector 80 and the rotation period detected by second detector 90 are the same.

[0083] (Control unit) The control unit 16 has a function of controlling the entire image forming apparatus 10. The hardware configuration of the control unit 16 is made up of a computer including a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) that stores programs for implementing each processing routine, a RAM (Random Access Memory) that temporarily stores data, a memory as a storage means, a network interface, etc.

[0084] The control unit 16 controls the rotation speed and other parameters of the chain 49. Specifically, as shown in Fig. 11, the control unit 16 controls a drive source (not shown) of a chain drive mechanism 79 that drives the chain 49 to rotate. Note that the drive source of the chain drive mechanism 79 refers to, for example, a drive source that drives and rotates one of the multiple sprockets.

[0085] The control unit 16 also controls the rotation of the transport rolls 51 and 52 of the position adjustment unit 50 and the rotation of the registration rolls 55 and 56. The control unit 16 can adjust the transport speed of the fed sheet P by adjusting the rotation speed of the registration rolls 55 and 56 of the position adjustment unit 50. The control unit 16 may set the speed at which the sheet P is fed from the position adjustment unit 50 to be the same as or different from the speed at which the sheet P reaches the transfer position T. For example, the control unit 16 may control the speed at which the sheet P is fed from the position adjustment unit 50 to be slower than the speed at which the gripper 42 rotates, and control the rotation speed of the registration rolls 55 and 56 so that the speed of the sheet P is slowed down after the leading edge P1 of the sheet P enters the gripper 42. As an example, the control unit 16 may control the rotation speed of the registration rolls 55 and 56 so that the sheet P is fed from the position adjustment unit 50 at a speed faster than the speed at which the gripper 42 rotates, and then the speed of the sheet P is slowed down after the leading edge P1 of the sheet P enters the gripper 42.

[0086] The control unit 16 controls the position adjustment unit 50 to send out the sheet P to the delivery position D1 based on the detection information (detection signal CS1) detected by the first detection device 80. As an example, the control unit 16 in this embodiment controls the timing of sending out the sheet P to the delivery position D1. Specifically, the control unit 16 controls the rotation speed of the registration rolls 55, 56 so that the sheet P (the leading edge P1 of the sheet P) reaches the delivery position D1 at the timing when the attachment portion of the chain 49 to the gripper 42 contacts the sprocket 37 (in other words, when the gripper 42 is wrapped around the sprocket 37). More specifically, the control unit 16 controls the rotation speed of the registration rolls 55, 56 so that the sheet P (the leading edge P1 of the sheet P) reaches the delivery position D1 at the timing when the gripper 42 reaches the delivery position D1. Furthermore, the timing at which the attachment portion of the chain 49 to the gripper 42 is in contact with the sprocket 37 refers to the engagement period from when the attachment portion of the chain 49 to the gripper 42 engages with the teeth of the sprocket 37 until it disengages from the teeth.

[0087] Furthermore, the control unit 16 controls the timing of image formation by the image forming unit 11 based on the detection information (detection signal CS2) detected by the second detection device 90. Specifically, the control unit 16 controls the timing of image formation (start of image formation) on the outer periphery of the transfer belt 22 by the image forming unit 11 based on the detection information.

[0088] 12 shows the movement of the sheet P, the drive timing of the registration rolls 55 and 56, and the timing of image formation by the image forming unit 11. As shown in FIG. 12, the control unit 16 generates a trigger TR1 for sending out the sheet P from the position adjustment unit 50 based on a detection signal CS1 obtained periodically by the rotation of the sprocket 37, and causes the sheet P to be sent out toward the delivery position D1 (start of conveyance). When the sheet P reaches the delivery position D1, the leading edge P1 of the sheet P is held by the gripper 42 and the sheet P is conveyed together with the gripper 42. When the sheet P reaches the transfer position T, the image formed on the surface of the transfer belt 22 is transferred onto the sheet P. Meanwhile, the control unit 16 generates a trigger TR2 for starting image formation by the image forming unit 11 based on a detection signal CS2 obtained periodically by the rotation of the sprocket 35, prior to generating the trigger TR1. In the image forming unit 11, when trigger TR2 is generated, print heads 12Y, 12M, 12C, and 12A form ink images on the surface of transfer belt 22 in this order, and transfer the ink images to paper P that has reached transfer position T.

[0089] <effect> Next, the operation of this embodiment will be described. In the image forming apparatus 10 of this embodiment, the control unit 16 controls the position adjustment unit 50 to send out the sheet P to the delivery position D1 based on the detection information detected by the first detection device 80. Note that in this embodiment, the timing of sending out the sheet P to the delivery position D1 is controlled. Therefore, compared to a configuration in which the sheet P is sent out to the delivery position D1 based on the position information of the circulating gripper 42, the sheet P can be sent out with high accuracy to the delivery position D1 of the circulating gripper 42 even if the chain 49 is stretched or vibrating. In particular, the paper P is sent to the transfer position D1 based on the rotation period (detection signal) of the sprocket 37, which rotates together with the transfer cylinder 60, of the conveying cylinder 31, transfer cylinder 36, and transfer cylinder 60, on which the paper P is handed over to the gripper 42. Therefore, compared to a configuration in which the paper P is sent to the transfer position D1 based on the rotation period (detection signal) of another cylinder, the paper P can be sent to the transfer position D1 of the rotating gripper 42 with high accuracy.

[0090] Furthermore, the control unit 16 controls the feeding of the paper sheet P so that the paper sheet P reaches the delivery position D1 at the timing when the attachment portion of the gripper 42 on the chain 49 contacts the sprocket 37. Therefore, compared to a configuration in which the paper sheet P reaches the delivery position D1 at a timing before the attachment portion of the gripper 42 on the chain 49 contacts the sprocket 37, the paper sheet P can be fed with high precision to the delivery position D1 of the circulating gripper 42.

[0091] Furthermore, the control unit 16 controls the feeding of the paper sheet P so that the paper sheet P reaches the delivery position D1 at the same time that the gripper 42 reaches the delivery position D1. Therefore, compared to a configuration in which the paper sheet P reaches the delivery position D1 before the gripper 42 reaches the delivery position D1, the paper sheet P can be fed with high precision to the delivery position D1 of the circulating gripper 42.

[0092] As described above, in the image forming apparatus 10, the sheet P is sent out with high precision to the delivery position D1 of the circulating gripper 42, so that the gripper 42 can hold the sheet P reliably.

[0093] Furthermore, in the image forming apparatus 10, a delivery position D1 is set around the delivery cylinder 60, and a transfer position T is set around the transfer cylinder 36. Therefore, the cylinder can be made smaller than in a configuration in which the delivery position D1 and the transfer position T are set around one cylinder.

[0094] Furthermore, in the image forming apparatus 10, the control unit 16 controls the timing of image formation on the surface of the transfer belt 22 by the image forming unit 11 based on detection information detected by the second detection device 90. Therefore, compared to a configuration in which a transfer image is formed on the outer periphery of the transfer belt 22 based on position information of the circulating gripper 42 and the formed transfer image is transferred to the sheet P at the transfer position T, even if the chain 49 is stretched or vibrating, an image can be formed with high precision at the transfer position T on the sheet P held by the circulating gripper 42. In particular, since the transfer image is formed on the outer periphery of the transfer belt 22 based on the rotation period of the sprocket 35 of the transfer cylinder 36 that transfers the image to the sheet P among the conveying cylinder 31, the transfer cylinder 36, and the delivery cylinder 60, compared to a configuration in which a transfer image is formed on the outer periphery of the transfer belt 22 based on detection information from the first detection device 80, an image can be formed with high precision at the transfer position T on the sheet P held by the circulating gripper 42.

[0095] Furthermore, in the image forming device 10, the rotation of each of the sprockets 37 and 35 is detected by an optical sensor, which is an optical detection unit, and therefore the parts replacement cycle can be extended compared to a configuration in which the rotation of each of the sprockets 37 and 35 is detected by contact between parts.

[0096] Since the rotation period of sprocket 37 detected by first detection device 80 is the same as the rotation period of sprocket 35 detected by second detection device 90, it is easier for control unit 16 to control the timing of sending paper P to delivery position D1 and the timing of image formation on paper P compared to a configuration in which the rotation periods of sprocket 37 and sprocket 35 are offset.

[0097] The effects obtained in the above-described embodiment are not limited to inkjet image forming apparatuses, but also function similarly in, for example, electrophotographic image forming apparatuses that form images using toner. An image forming apparatus 210, which is an example of an electrophotographic image forming apparatus according to the present invention, will be described below. As shown in FIG. 13 , the image forming apparatus 210 includes an image forming unit 212 and a transfer unit 230, instead of the image forming unit 11 and transfer unit 30 of the image forming apparatus 10. The transfer unit 230 includes a transfer belt 232 and a secondary transfer roll 234, instead of the transfer belt 22 and transfer roll 33. The transfer unit 230 also includes primary transfer rolls 233, around which the transfer belt 232 is wound and which correspond to each color of the image. The image forming unit 212 includes multiple toner image forming units 220Y, 220M, 220C, and 220K that form toner images, instead of the print head 20 of the image forming apparatus 10. The toner image forming unit 220 for each color includes a photosensitive drum 221 for each color that is arranged on the opposite side of the transfer belt 222 from the corresponding primary transfer roll 233. The toner image forming unit 220 forms a toner image on the photosensitive drum 221 for each color and transfers the toner image to the transfer belt 222 at a primary transfer position formed between the photosensitive drum 221 and the primary transfer roll 233. The toner image transferred to the transfer belt 222 is transferred to paper P at a secondary transfer position T, which is an image forming position formed between the secondary transfer roll 234 and the transfer cylinder 36. Except for the above points, the electrophotographic image forming apparatus 210 has the same configuration as the inkjet image forming apparatus 10.

[0098] Furthermore, in the above-described embodiment, an ink image is formed on the surface of the transfer belt 22 and then transferred to the paper P, but the present invention is not limited to this configuration. For example, an ink image may be formed by spraying ink droplets directly from the print head 12 onto the paper P. Even in this case, the paper P can be sent with high accuracy to the delivery position D1 of the rotating gripper 42.

[0099] In the above-described embodiment, the timing at which the position adjustment unit 50 sends out the sheet P to the delivery position D1 is controlled based on the detection information detected by the first detection device 80, but the present invention is not limited to this configuration. For example, the speed at which the position adjustment unit 50 sends out the sheet P to the delivery position D1 may be controlled based on the detection information detected by the first detection device 80. Furthermore, both the timing and the speed at which the sheet P is sent out to the delivery position D1 may be controlled.

[0100] In the above-described embodiment, the gripper 42 holds the fed sheet P at the delivery position D1 around the delivery cylinder 60, and an image is formed on the sheet P held by the gripper 42 at the transfer position T around the transfer cylinder 36. However, the present invention is not limited to this configuration. For example, as in the image forming apparatus 300 shown in FIG. 14, the transfer cylinder 336 may have the function of the delivery cylinder 60. In this case, the sheet P fed from the position adjustment unit 50 is held by the gripper 42 at the delivery position D1 set around the transfer cylinder 336. The sheet P held by the gripper 42 is transported together with the gripper 42 by the chain 49 and is wrapped around the transfer cylinder 336. At the transfer position T, the transferred image formed by the image forming unit 11 is transferred onto the wrapped sheet P. Here, the cycle of the transfer cylinder 336, the movement of the sheet P in the image forming apparatus 300, and the timing of image formation in the image forming unit 11 are as shown in FIG. 15. In the image forming apparatus 300, the transfer cylinder 336 has the function of the delivery cylinder 60, so that the number of light blocking members and light detecting units can be reduced compared to the image forming apparatus 10.

[0101] Furthermore, in the first detection device 80 of the above-described embodiment, the rotation of the sprocket 37 is detected by the passage of the first light-blocking member 82 through the optical path of the first optical detector 84. However, in the present invention, as long as the rotation of the sprocket 37 can be detected, either continuous or intermittent detection is acceptable. For example, continuous detection can be achieved by continuously detecting (continuously monitoring) the location of a specific position (part or mark) on the sprocket 37 over a wide area. As an example, the location of a specific position (part or mark) on the sprocket 37 can be detected from image information around the sprocket 37. On the other hand, intermittent detection can be achieved by detecting when a specific position (part or mark) on the sprocket 37 passes a specific location (where an optical sensor is located), as in the first detection device 80. Note that the second detection device 90 may also be configured to continuously or intermittently detect the rotation of the sprocket 35, as described above.

[0102] In this embodiment, a chain is used as an example of a circumferential member, and a sprocket is used as an example of a rotating member, but the present invention is not limited thereto. For example, a timing belt having an uneven inner circumference may be used as an example of a circumferential member, and a timing pulley (i.e., a pulley having an uneven outer circumference) may be used as an example of a rotating member. Also, a belt may be used as an example of a circumferential member, and a pulley that rotates the belt by friction may be used as an example of a rotating member. In this configuration, the pulley rotates in contact with the belt, rather than meshing with it, causing the belt to rotate.

[0103] The configuration of the image forming apparatus is not limited to that of the above embodiment, and various other configurations are possible. Furthermore, the present invention can be embodied in various forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0104] 10 Image forming device 11 Image forming unit 22 Transfer belt (an example of a transfer body) 35 Sprocket (an example of a second rotating member) 36 Transfer cylinder (example of cylinder) 37 Sprocket (an example of a first rotating member) 42 Gripper (an example of a holding member) 49 Chain (an example of a rotating component) 50 Position adjustment unit (an example of a sending unit) 22 Transfer belt (an example of a transfer body) 80 First detection device (an example of first detection means) 82 first light blocking member 84 First light detection unit 90 Second detection device (an example of second detection means) 92 second light blocking member 94 Second optical detection unit 210 Image forming device 220 Toner image forming unit (an example of an image forming unit) 222 Transfer belt (an example of a transfer body) 300 Image forming device 336 Transfer cylinder (example of cylinder) P Paper (an example of a recording medium) D Circular Route D1 Delivery position (an example of a holding position) T Transfer position (an example of an image formation position)

Claims

1. A plurality of rotating members; a circumferential member formed in an annular shape, wound around the plurality of rotating members, and circumferentially rotating in accordance with the rotation of the rotating members; a holding member attached to an attachment portion of the rotating member, rotating together with the rotating member, and holding a recording medium in an area where the attachment portion contacts one of the rotating members; an image forming unit that forms an image on the recording medium at an image forming position in the rotation path of the rotating member; a feeding unit that feeds the recording medium to a holding position where the holding member holds the recording medium; a detection means for detecting the rotation of the one rotating member; a control unit that controls the sending unit to send out the recording medium to the holding position based on the detection information detected by the detection means; An image forming apparatus comprising: a first rotating member as the one rotating member; a second rotating member, among the plurality of rotating members, positioned downstream of the first rotating member in a conveying direction of the recording medium; a drum that rotates together with the second rotating member and on which the recording medium held by the holding member is wound; a transfer body included in the image forming unit, having a transfer image formed on its outer periphery, which transfers the transfer image to the recording medium wound around the drum at the image forming position; An image forming apparatus comprising:

2. The image forming apparatus according to claim 1 , wherein the control unit controls the feeding so that the recording medium reaches the holding position at a timing when the attachment portion is in contact with the first rotating member.

3. 3. The image forming apparatus according to claim 2, wherein the control unit controls the feeding so that the recording medium reaches the holding position at the same time that the holding member reaches the holding position.

4. a first detecting means as the detecting means for detecting rotation of the first rotating member; second detection means for detecting the rotation of the second rotary member; Equipped with The image forming apparatus according to any one of claims 1 to 3, wherein the control unit controls the timing of transfer image formation on the outer periphery of the transfer body by the image forming unit based on detection information detected by the second detection means.

5. the first detection means includes a first light blocking member that rotates together with the first rotating member, and a first optical detection unit that is fixed to an apparatus body having a first support unit that supports the first rotating member and detects the first light blocking member passing through an optical path; 5. The image forming apparatus according to claim 4, wherein the second detection means comprises: a second light-blocking member that rotates together with the second rotating member; and a second optical detection unit that is fixed to the apparatus main body and has a second support portion that supports the second rotating member, and that detects the second light-blocking member passing through the optical path.

6. 6. The image forming apparatus according to claim 4, wherein a period in which the first detecting means detects the rotation of the first rotating member is the same as a period in which the second detecting means detects the rotation of the second rotating member.

Images