Image forming device

Abstract

To obtain an image forming apparatus that can reduce the size of the entire apparatus compared with a configuration in which a paper feeding direction and a paper ejection direction are the same direction.SOLUTION: An image forming apparatus 10 has: a holding unit that holds a recording medium to be conveyed; circulation units that circulate with the holding unit being fixed, and form a part of a paper conveyance path A for conveying the recording medium; an image forming unit that forms an image on the recording medium at an image forming position 18 on a circulation path D of the circulation units; a delivery point D1 at which the recording medium is delivered on the circulation path D; and a receiving point D2 that is provided on the same side as the delivery point D1 with respect to the image forming position 18, and at which the recording medium is received from the circulation path D.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] The transfer transport device described in Patent Document 1 is a transfer paper transport device for a recording device that moves a recording head having a light-emitting element array and an imaging system at a constant speed approximately in the direction of the generatrix of a photosensitive drum that rotates at a constant speed, scans the photosensitive drum spirally to form a latent image, develops this and transfers the resulting toner image onto transfer paper.The transfer paper transport device comprises a pair of endless chains or belts that are transported in a direction perpendicular to the axis of the photosensitive drum, gripper means that are pinned at both ends to each of the pair of endless chains or belts and grip the leading edge of the transfer paper to transport it, and means for variably controlling the relative positional relationship of the transport directions of the pair of chains or belts, and is characterized in that prior to transporting the transfer paper to the transfer position, the direction of the gripper means is tilted by the same angle as the angle of the main scanning direction of the spiral recording on the photosensitive drum relative to the drum circumferential direction, so that the transfer paper is transported in an inclined state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 59-007966 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an image forming apparatus that can reduce the overall size of the apparatus compared to an arrangement in which the paper feed direction and the paper discharge direction are the same. [Means for solving the problem]

[0005] The image forming device according to the first aspect includes a holding section that holds the recording medium to be transported, a circulating section that fixes and rotates the holding section and forms part of a transport path along which the recording medium is transported, an image forming section that forms an image on the recording medium at an image forming position on the circulating path of the circulating section, a transfer point on the circulating path that hands over the recording medium, and a receiving point that is located on the same side of the transfer point as the image forming position and receives the recording medium from the circulating path.

[0006] An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the delivery point is disposed below the receiving point.

[0007] An image forming apparatus according to a third aspect is the image forming apparatus according to the first or second aspect, wherein the circulation path is configured such that the path along which the recording medium passes through the image forming unit is inclined upward.

[0008] An image forming apparatus according to a fourth aspect is an image forming apparatus according to any one of the first to third aspects, wherein the circular path is configured to pass through a fixing unit that fixes an image onto the recording medium at a fixing position located downstream of the image forming unit, and the fixing position is located above the image forming position on the circular path.

[0009] An image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect, wherein a position adjustment unit that adjusts the position of the recording medium is arranged below the fixing position on the transport path of the recording medium and between the fixing position and the image forming position in the horizontal direction. An image forming apparatus according to a sixth aspect is an image forming apparatus according to any one of the first to fifth aspects, which is composed of multiple units and further includes a position adjustment unit that adjusts the position of the recording medium, and the image forming unit, the rotation unit, and the position adjustment unit are arranged in the same unit. An image forming apparatus according to a seventh aspect is the image forming apparatus according to the sixth aspect, wherein the circular path has an inclined portion that slopes downward from the receiving point toward the transfer point, the inclined portion forms a space between the inclined portion and the conveying path toward the transfer point, and the position adjustment unit is arranged in the space.

[0010] An image forming apparatus according to an eighth aspect is an image forming apparatus according to any one of the first to seventh aspects, wherein the circulating portion is attached to both ends of the holding portion in the width direction of the recording medium being transported.

[0011] The image forming apparatus according to the ninth aspect has a holding section that extends in the width direction of the recording medium being transported and holds the recording medium, and a circulating section that fixes and rotates the holding section, transports the recording medium to an image forming section that forms an image on the recording medium, and flips the recording medium over on the circulating path.

[0012] An image forming apparatus according to a tenth aspect is the image forming apparatus according to the ninth aspect, wherein the circulating unit passes through the image forming unit in the process of reversing the recording medium.

[0013] An image forming apparatus according to an eleventh aspect is the image forming apparatus according to the ninth or tenth aspect, wherein the circulating unit constitutes a part of a back-side transport path for forming an image on the back side of the recording medium.

[0014] An image forming apparatus according to a twelfth aspect is an image forming apparatus according to any one of the ninth to eleventh aspects, further comprising: a confluence path in the transport path of the recording medium, upstream of the circular path, where the transport path for the front surface of the recording medium and the transport path for the back surface of the recording medium join; and a position adjustment unit provided in the confluence path that adjusts the position of the recording medium. [Effects of the Invention]

[0015] According to the image forming apparatus of the first aspect, the overall size of the apparatus can be reduced compared to a configuration in which the paper feed direction and the paper discharge direction are the same.

[0016] According to the image forming apparatus of the second aspect, it is easier to arrange the paper discharge path on the upper side compared to a configuration in which the delivery point is arranged above the receiving point.

[0017] According to the image forming device of the third aspect, compared to a configuration in which the path passing through the image forming unit in the circular path is arranged horizontally, the paper discharge path after passing through the image forming unit can be arranged higher than the paper feed path before passing through the image forming unit.

[0018] According to the image forming apparatus of the fourth aspect, compared to a configuration in which the fixing unit is disposed below the image forming position, the exhaust heat generated in the fixing unit is less likely to be transmitted to the image forming position.

[0019] According to the image forming device of the fifth aspect, the overall size of the device can be reduced compared to a configuration in which the position adjustment unit is positioned at the same height as the fixing position or outside the space between the fixing position and the image forming position in the horizontal direction. According to the image forming device of the sixth aspect, adjustment of the position adjustment unit when installing the image forming device can be simplified compared to a configuration in which the position adjustment unit is arranged in a unit separate from the unit in which the image forming unit and the circulating unit are arranged. According to the image forming device of the seventh aspect, in a configuration in which a space is formed between the circular path and the conveying path, the positional accuracy of the recording medium being conveyed to the transfer point is higher than in a configuration in which the position adjustment unit is located upstream of the space in the conveying direction of the recording medium.

[0020] According to the image forming apparatus of the eighth aspect, tilt of the recording medium in the width direction can be suppressed compared to a configuration in which the circumferential portion is attached only to the center portion in the width direction of the holding portion.

[0021] According to the image forming apparatus of the ninth aspect, the overall size of the apparatus can be reduced compared to a configuration in which a circulation unit that turns over the recording medium is provided separately from the circulation path.

[0022] According to the image forming device of the tenth aspect, the overall size of the device can be reduced compared to a configuration in which the process of reversing the recording medium from its front to back on the circular path and the position where the image forming unit passes through are located in different positions.

[0023] According to the image forming apparatus of the eleventh aspect, the overall size of the apparatus can be reduced compared to a configuration in which the circulating unit and the back-side transport path are provided separately.

[0024] According to the image forming apparatus of the twelfth aspect, the overall size of the apparatus can be reduced compared to a configuration in which the joining path and the position adjustment unit are provided separately. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a front view showing an image forming apparatus according to a first embodiment. [Figure 2] 2 is an enlarged view of the periphery of an image forming position in the image forming apparatus according to the first embodiment. FIG. [Figure 3] 3 is an enlarged view showing a state in which a sheet is held by a gripper in the image forming apparatus according to the first embodiment. FIG. [Figure 4] 3A to 3C are cross-sectional views showing the operation of a gripper in the image forming apparatus according to the first embodiment. [Figure 5] FIG. 2 is an enlarged view showing a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 6] 4 is an enlarged view showing the operation of holding the leading edge of the paper by the gripper in the image forming apparatus according to the first embodiment. FIG. [Figure 7] 3 is an enlarged view showing the structure of a position adjustment unit in the image forming apparatus according to the first embodiment. FIG. [Figure 8] 5A and 5B are enlarged views showing the operation of a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 9] 5A and 5B are enlarged views showing the operation of a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 10] 5A and 5B are enlarged views showing the operation of a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 11] 5A and 5B are enlarged views showing the operation of a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 12] 5A and 5B are enlarged views showing the operation of a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 13] 5A and 5B are enlarged views showing the operation of a position adjustment unit in the image forming apparatus according to the first embodiment. [Figure 14] FIG. 10 is a front view showing an image forming apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] First Embodiment An image forming apparatus (simply referred to as "apparatus" as appropriate) according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 13. The arrow UP shown in each drawing is vertical and points upward from the apparatus. The arrow RH is horizontal and points to the right side when facing the apparatus as shown in FIG. 1. In the following description, when a vertical direction is specified without any precondition, it means the vertical direction of the apparatus shown in FIG. 1. In the following description, when a horizontal direction is specified without any precondition, it means the left (= L) and right (= R) directions when facing the apparatus shown in FIG. 1. In the following description, when a depth direction (= front and back) is specified without any precondition, it means the depth direction when facing the apparatus shown in FIG. 1.

[0027] [Overall Configuration of Image Forming Apparatus 10] 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.

[0028] As shown in FIG. 1, image forming apparatus 10 includes unit 10A, which is located on the right side of unit 10A, unit 10B, which is located to the left of unit 10A, and unit 10C, which is located to the left of unit 10B. Units 10B and 10C each contain paper P (an example of a recording medium) for image recording and include a paper tray 38 that feeds paper P toward unit A. Unit 10C also includes a paper discharge tray 39. Unit 10A includes an image forming section that forms an image on paper P. The image forming section includes image forming unit 12 for forming an image by electrophotography, an intermediate transfer belt 22 for holding the formed image, and an intermediate transfer unit 14 for mounting and supporting intermediate transfer belt 22. Image forming apparatus 10 also includes a transfer body 36, which transfers the image from intermediate transfer unit 14 to paper P, located below and to the left of intermediate transfer unit 14.

[0029] The contact point between the intermediate transfer belt 22 and the transfer body 36 is a secondary transfer position 18 (corresponding to an example of an image forming position) described later. At this secondary transfer position 18, the toner image formed by the image forming unit 12 is transferred onto the surface of the paper P via the intermediate transfer belt 22 attached to the intermediate transfer unit 14.

[0030] The image forming apparatus 10 is provided with a plurality of image forming units 12 for forming toner images of each color. In this embodiment, a total of four image forming units 12 are provided, one for each color: a yellow image forming unit 12Y, a magenta image forming unit 12M, a cyan image forming unit 12C, and a black image forming unit 12K.

[0031] In this embodiment, yellow (=Y), magenta (=M), cyan (=C), and black (=K) are the basic colors for outputting a color image. In the following description, when it is not necessary to distinguish between the colors of each image forming unit 12, they will simply be referred to as "image forming unit 12," and the symbols Y, M, C, and K representing the image forming units corresponding to each color will be omitted as appropriate.

[0032] The image forming units 12 for each color are basically configured the same, except for the type of toner used. As shown in FIG. 2, each image forming unit 12 includes a rotating, cylindrical photoconductor 24 and a charger 26 that charges the photoconductor 24. The image forming unit 12 also includes an exposure device 28 that irradiates the charged photoconductor 24 with exposure light to form an electrostatic latent image, and a developing device 30 that develops the electrostatic latent image into a toner image using a developer containing toner. The image forming unit 12 also includes a cleaner 29 that removes any toner remaining on the surface of the photoconductor 24 after the toner is transferred from the photoconductor 24 to the intermediate transfer belt 22.

[0033] The photoconductors 24 of each color are configured to be able to come into contact with the outer peripheral surface of the intermediate transfer belt 22. As shown in Fig. 1, the image forming units 12 corresponding to yellow, magenta, cyan, and black are arranged side by side from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 22 (= the direction of arrow X in Fig. 1).

[0034] (Intermediate transfer unit 14) The intermediate transfer unit 14 includes a primary transfer roll 34 disposed opposite the image forming units 12 of each color, and a backup roll 33 disposed opposite a transfer body 36. The transfer body 36 will be described in detail later.

[0035] (Intermediate transfer belt 22) As shown in FIG. 1, the intermediate transfer belt 22 is endless. The intermediate transfer belt 22 is wound around a plurality of rolls 32 to determine its position. In this embodiment, the intermediate transfer belt 22 is elongated in the width direction of the device when viewed from the front, and has a generally obtuse triangular shape with an obtuse-angled convex portion facing downward. One of the rolls 32 (not shown) has the function of rotating the intermediate transfer belt 22 in the direction of arrow X using the power of a motor (not shown). By rotating in the direction of arrow X, the intermediate transfer belt 22 transports the primarily transferred image to a secondary transfer position 18 (described later).

[0036] The intermediate transfer belt 22 is configured to be able to rotate in the direction of arrow X while being in contact with or spaced from the photosensitive members 24 of the respective colors.

[0037] (Primary Transcript) 1, each primary transfer section 19 is configured by a contact portion between a photoconductor 24, an intermediate transfer belt 22, and a primary transfer roll 34. The primary transfer roll 34 is disposed opposite the photoconductor 24, with the intermediate transfer belt 22 sandwiched therebetween. The primary transfer roll 34 and the intermediate transfer belt 22 are configured to contact each other with a predetermined load.

[0038] A voltage is applied to the primary transfer roll 34 by a power supply unit (not shown). This voltage is a primary transfer voltage for primarily transferring the toner image formed on the photoreceptor 24 onto the intermediate transfer belt 22 between the photoreceptor 24 and the primary transfer roll 34.

[0039] (transcript) 1, a transfer body 36 is provided at a position facing the backup roll 33 across the intermediate transfer belt 22. The transfer body 36 has a cylindrical shape with its axis extending in the depth direction of the image forming apparatus 10, and is provided so as to be rotatable in the circumferential direction. A recess (not shown) is formed on the outer periphery of the transfer body 36 to accommodate a gripper 42, which will be described later.

[0040] A voltage is applied to the transfer body 36 by a power supply unit (not shown). This voltage is used as a secondary transfer voltage when the toner image transferred and superimposed on the intermediate transfer belt 22 is secondarily transferred onto the paper P transported to the secondary transfer position 18.

[0041] (Secondary transcription) 1, the secondary transfer position 18 (corresponding to an example of an image forming position) is formed by the contact portion between the intermediate transfer belt 22 and the transfer body 36 formed in a roll shape. The intermediate transfer belt 22 is configured to contact the transfer body 36 with a predetermined load by a backup roll 33 arranged opposite the transfer body 36.

[0042] (fixing device) The fixing device 40 is disposed downstream of the secondary transfer position 18 in the transport direction of the paper P. The fixing device 40 includes a pair of opposing rolls. The pair of rolls are disposed so as to face each other across a paper transport path A, which will be described later. In other words, the paper P to be fixed is transported so as to pass between the pair of rolls.

[0043] (Paper transport path) 1, paper transport path A (an example of a transport path) has a function of transporting paper P supplied from paper tray 38 of unit 10B or unit 10C to unit 10A. Paper transport path A also has a configuration in which paper P supplied from paper tray 38 is transported while passing through secondary transfer position 18 and a fixing position (details will be described later) in unit 10A, and is discharged via unit 10B to paper discharge tray 39 of unit 10C.

[0044] Meanwhile, the portion of the paper transport path A downstream of the fixing device 40 branches into a direction-changing path B for changing the transport direction of the paper P. The direction-changing path B has a function of changing the transport direction of the paper P, which branches off from the paper transport path A and is transported to the direction-changing path B, to the opposite direction from the transport direction of the paper transport path A downstream of the fixing device 40. In other words, the direction-changing path B changes the transport direction of the paper P transported to the direction-changing path B, thereby switching the relationship between the leading and trailing ends of the paper P and transporting the paper P downstream of the direction-changing path B. The downstream portion of the direction-changing path B is configured to merge with the paper transport path A toward the secondary transfer position 18. Note that the path between the direction-changing path B and the circular path D (described in detail later) on the paper transport path A is a merging path where the transport path for the front side and the transport path for the back side of the paper P merge. Note that each of the above transport paths includes multiple paper transport rolls (not shown). The rolls transport the paper P along each transport path.

[0045] (Basic image formation operation) Next, an outline of the image forming operation on the paper P in the image forming apparatus 10 will be described.

[0046] Various operations in the image forming apparatus 10 are performed by a control unit 16 (see FIG. 1) built into the apparatus. When the control unit 16 receives an image formation command from the outside, it activates each image forming unit 12. The photoconductors 24 of each color are charged by chargers 26 while rotating. The control unit 16 also sends image data that has been subjected to image processing in an image signal processing unit (not shown) to each exposure device 28. Each exposure device 28 irradiates each photoconductor 24 with exposure light in accordance with the image data, thereby exposing each charged photoconductor 24. As a result, an electrostatic latent image is formed on the outer peripheral surface of each photoconductor 24. The electrostatic latent image formed on each photoconductor 24 is developed by each developing device 30, and a toner image of each color is formed on the photoconductor 24 corresponding to each color.

[0047] The toner images of each color formed on the photoreceptors 24 of each color are primarily transferred to the intermediate transfer belt 22 by the primary transfer rolls 34 of each color at the respective primary transfer portions. At this time, as the intermediate transfer belt 22 rotates, the toner images of each color are sequentially primarily transferred to the intermediate transfer belt 22 while being superimposed on each other. The superimposed toner images are transported to the secondary transfer position 18 by the rotation of the intermediate transfer belt 22. The superimposed toner images are then transferred from the intermediate transfer belt 22 to the paper P at the secondary transfer position 18.

[0048] The paper P onto which the toner image has been secondarily transferred is transported toward the fixing device 40. In the fixing device 40, the paper P is heated and pressed by the fixing rolls. As a result, the toner images formed by the image forming units 12 are fixed onto the paper P.

[0049] The image forming apparatus 10 has a configuration in which it can perform double-sided printing on the paper P by having the direction change path B. Double-sided printing in the image forming apparatus 10 will be described in detail later.

[0050] [Main components] Next, the main configuration of this embodiment will be described.

[0051] (gripper) 4, the image forming apparatus 10 includes a gripper 42 (corresponding to an example of a holding section) that holds the leading edge P1 of the transported paper P and assists in transporting the paper. 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.

[0052] A plurality of clips 44 are provided across the depth direction of the device. The clips 44 are fixed to a shaft 48 and are configured to be rotatable in accordance with the rotation of the shaft 48 in the circumferential direction.

[0053] The case 46 has a longitudinal direction in the depth direction and 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 in two directions, the upstream and downstream sides in the paper transport direction, and in the direction of the back surface of the paper (i.e., the direction of the non-image-forming surface of the paper P). In this structure, the leading end 45 of the clip 44 and the rear end 47 of the case 46 are configured to be able to clamp the leading end P1 of the paper P in the transport direction.

[0054] (shafts and conveyor chains) As shown in FIG. 3, both ends of the shaft 48 of the gripper 42 in the depth direction are held by a conveying chain 49 (corresponding to an example of a circulating portion) described below. In other words, the conveying chain 49 is attached to both ends of the gripper 42 in the depth direction. The shaft 48 of the gripper 42 is held by the conveying chain 49 so as to rotate together with the conveying chain 49 as the conveying chain 49 rotates. As a result, the gripper 42 is held by the conveying chains 49 provided on the front and rear sides of the image forming apparatus 10 and rotates along a predetermined circulating path D (see FIG. 1). The conveying chains 49 are a pair of endless chains held along the circulating path D by a plurality of sprockets (not shown).

[0055] (Circuit Route D) 1, the circular path D is provided so that a portion of the circular path D overlaps a portion of the paper transport path A in a front view of the image forming apparatus 10. In this embodiment, the orientation of the circular path D is elongated in the device width direction in a front view, and is a generally triangular shape having a downward convex portion. More specifically, the circular path D is configured to overlap with the paper transport path A from the time it passes through the contact point with the paper transport path A on the outer periphery of a sprocket 37 provided below the transfer body 36 until it passes through the fixing device 40. The position where the circular path D passes through the fixing device 40 is referred to as the fixing position (which corresponds to an example of the fixing position).

[0056] At the start point of overlap between paper transport path A and circular path D, leading end 45 of clip 44 and trailing end 47 of case 46 come close to each other, and gripper 42 clamps the leading end of paper P. In other words, the start point of overlap between paper transport path A and circular path D is referred to as the position where gripper 42 starts to hold paper P on circular path D. The position where gripper 42 starts to hold paper P on circular path D is referred to as transfer point D1 (equivalent to an example of a transfer point) where paper P is handed over from paper transport path A to gripper 42.

[0057] (CL.2 requirements) Furthermore, at the end point of the overlap between the circular path D and the paper transport path A, the leading end 45 of the clip 44 and the trailing end 47 of the case 46 separate, releasing the leading end of the paper P. The position at which the gripper 42 releases the paper P on the circular path D is the receiving point D2 (corresponding to an example of the receiving point) where the paper P is received from the gripper 42 and transferred to the paper transport path A. The receiving point D1 is located below the receiving point D2.

[0058] 1, in this embodiment, when the paper P is transferred from the paper transport path A to the circular path D, the paper P is transferred from the left side to the right side with respect to the image forming position. In other words, the paper feed direction at the transfer point D1 is from the left side to the right side.

[0059] On the other hand, when the sheet P is received on the circular path D, the sheet P is received from the right side to the left side with respect to the secondary transfer position 18. In other words, the sheet is discharged from the receiving point D2 in the direction from the right side to the left side.

[0060] From another perspective, the receiving point D2 and the handover point D1 are both provided on the left side (i.e., the same side) of the secondary transfer position 18 in FIG. 1 on the circular path of the circular path D. Also, the paper feed direction and the paper discharge direction are configured to be opposite to each other.

[0061] Further, the direction in which the paper P passes through the secondary transfer position 18 (that is, the image forming position) on the circulation path D is set so as to be inclined upward from the lower right side to the upper left side.

[0062] The path of the circular path D from passing through the secondary transfer position 18 to passing through the fixing device 40 is configured to be inclined upward. As a result, the fixing device 40 is positioned above the secondary transfer position 18.

[0063] The path of the circular path D is configured to slope downward from the time it passes through the fixing device 40 (receiving point D2) until it passes through the junction with the paper transport path A (transfer point D1). The path that slopes downward from the receiving point D2 toward the transfer point D1 is the sloped portion DT. With this configuration, the sloped portion DT forms a space S sandwiched between the sloped portion DT and the paper transport path A. In this embodiment, the space S has a vertical height that decreases horizontally from the receiving point D2 side toward the transfer point D1 side. In other words, the space S has a vertical height that decreases horizontally from the fixing device 40 side toward the secondary transfer position 18 side.

[0064] (Position adjustment section)

[0065] 1, a portion of the upper side of position adjustment unit 50 is disposed in space S, and has the function of adjusting the position of paper P being transported to transfer point D1. That is, position adjustment unit 50 is disposed on a junction path in paper transport path A that is provided between direction change path B and transfer point D1.

[0066] As shown in FIG. 7, the position adjustment unit 50 includes a plurality of rolls 51-56, a plurality of sensors 61-64, and a stopper 72. Each roll is disposed above or below the paper transport path A. Specifically, roll 51, roll 53, and roll 55 are disposed above the merging path in order along the transport direction of the paper P. Rolls 52, 54, and 56 are disposed below the merging path in pairs with rolls 51, 53, and 55, respectively. These roll pairs transport the paper P by rotating with the paper P sandwiched between the upper and lower rolls. Roll 54 is disposed so as to be separable from the paper transport path A.

[0067] At the contact point between the rolls 53 and 54, stoppers 72 formed in a generally N-shape are disposed on the front and rear sides in the depth direction. The downstream end of this stopper 72 in the paper transport direction forms a gate section 73 that is raised so as to intersect with the paper transport path A. When the leading edge P1 of the paper P supplied to the position adjustment section 50 abuts against the gate section 73, the timing of paper transport, misalignment in the paper width direction, or paper inclination, etc., are adjusted. In other words, the position adjustment section 50 adjusts the position of the paper P transported to the delivery point D1 by the gate section 73 provided at the pair of rolls 53 and 54.

[0068] On the upstream side of stopper 72 in the paper transport direction, there are provided a fan-shaped gear 74 and a circular gear 76 that meshes with gear 74. When a motor (not shown) attached to gear 76 rotates, gears 76 and 74 rotate, and as a result, gate portion 73 of stopper 72 attached to gear 74 moves up and down in FIG.

[0069] When gate unit 73 is moved upward, gate unit 73 is moved to a position where it blocks paper transport path A. In this case, paper P transported along paper transport path A is stopped at the position of gate unit 73. On the other hand, when gate unit 73 is moved downward, gate unit 73 is moved to a position where it does not block paper transport path A. In this case, paper P being transported is transported along paper transport path A without being interfered with by gate unit 73.

[0070] Each of the sensors 61-64 detects whether the paper P is passing or not passing through the paper transport path A. Upon receiving signals from each of the sensors 61-64, the control unit 16 controls the operation of each of the rolls 51-56 as appropriate.

[0071] The position adjustment unit 50 is disposed so that its position in the horizontal direction overlaps with the inclined portion DT of the circulation path D. In other words, the position adjustment unit 50 is disposed between the fixing device 40 and the secondary transfer position 18 in the horizontal direction. Furthermore, the position adjustment unit 50 is disposed in the space S on the delivery point D1 side of a bisector (not shown) that bisects the space S into upstream and downstream sides in the conveying direction toward the delivery point D1. That is, the rolls 53 and 54 are disposed in the space S on the delivery point D1 side of a bisector (not shown) that bisects the space S into upstream and downstream sides in the conveying direction toward the delivery point D1. In other words, the gate unit 73 is disposed in the space S on the delivery point D1 side of a bisector (not shown) that bisects the space S into upstream and downstream sides in the conveying direction toward the delivery point D1. Moreover, the position adjustment unit 50 is disposed in the unit 10A in which the image forming unit and the conveyor chain 49 are disposed. That is, in the image forming apparatus 10, the image forming unit, the conveyor chain 49, and the position adjustment unit 50 are disposed in the same unit 10A.

[0072] (Operation in position adjustment section) 8 to 13 show the operation of each part in the position adjustment unit 50 when the position of the paper sheet P is adjusted. As shown in Fig. 8, when the paper sheet P is transported, the gate unit 73 is disposed so as to block the paper transport path.

[0073] 8, the leading edge P1 of the paper P transported along the paper transport path A passes through the sensor 61. Then, the rolls 51 and 52 are driven based on the timing of the paper passing as determined by the sensor 61 until the leading edge P1 of the paper P reaches the gate section 73. Whether the leading edge P1 of the paper P has reached the gate section 73 can also be predicted based on the timing of the leading edge P1 passing through as determined by the sensor 62 provided before the gate section 73.

[0074] 9, when the leading edge P1 of the paper P reaches the gate section 73, the rolls 53 and 54 are separated from each other. Specifically, the lower roll 54, which is movable in the vertical direction, has moved downward. Then, the paper P whose leading edge P1 has been transported to the gate section 73 is further transported by the rolls 51 and 52 for a predetermined time.

[0075] 10, the paper P is further sent out by the rolls 51 and 52 with the leading edge P1 abutting against the gate section 73, and is put into a state of being bent between the rolls 51 and 52 and the gate section 73. As a result, the tilt of the paper P in the width direction is corrected by the gate section 73.

[0076] 11, after the skew of the paper P is corrected, the roll 54 moves upward. As a result, the rolls 53 and 54 sandwich the leading edge P1 of the paper P. At this time, the skew of the leading edge P1 of the paper P has been corrected by the gate section 73, so the rolls 53 and 54 maintain the skew-corrected state.

[0077] 12, the gate section 73 is moved downward while the leading edge P1 of the paper P is held by the rolls 53 and 54. At this time, the rolls 53 and 54 are stationary.

[0078] As shown in FIG. 13, after gate portion 73 is moved downward, rolls 53 and 54 are driven, and paper P is conveyed again. Leading edge P1 of the conveyed paper P passes through sensor 63, which is disposed between rolls 53 and 55. Leading edge P1 of paper P is then supplied to rolls 55 and 56. Leading edge P1 of paper P is further conveyed by driving rolls 55 and 56. At this time, sensors 63 and 64 detect the passing timing of leading edge P1 of paper P, and the driving states of rolls 55 and 56 are controlled.

[0079] (Paper handover) 6(A) to 6(C), the paper sheet P that has passed through the position adjustment unit 50 is clamped on the circumference of the sprocket 37 in FIG. 5 by the rear end 47 of the case 46 of the gripper 42 and the leading end 45 of the clip 44. The gripper 42 is fed while moving along the circular path D in accordance with the transport timing of the leading end P1 of the paper sheet P. At this time, as shown in FIG. 6(A), the case 46 and the clip 44 are in an open state.

[0080] 6(B), gripper 42 is configured so that case 46 and clip 44 gradually approach each other while moving along circular path D in synchronization with the transport timing of paper sheet P. Then, tip 45 of clip 44 lifts tip P1 of paper sheet P from paper transport path A.

[0081] 6(C), leading end P1 of paper P is further lifted by clip 44, and is transferred from paper transport path A to circular path D while being clamped between rear end 47 of case 46 and leading end 45 of clip 44. Thereafter, gripper 42 transports paper P along circular path D.

[0082] (Paper reversal) As shown in FIG. 1, after being delivered to the circulation path D, the paper P is turned over along the outer periphery of the transfer body 36. That is, the conveyance chain 49 along the circulation path D turns over the paper P on the circulation path D. The paper P is then conveyed to the secondary transfer position 18 provided on the outer periphery of the transfer body 36. That is, the secondary transfer position 18 is configured so that the paper P passes through the secondary transfer position 18 in the process of being turned over along the circulation path D and the outer periphery of the transfer body 36. In other words, the conveyance chain 49 along the circulation path D passes through the image forming unit in the process of turning over the paper P.

[0083] The surface of the paper P facing the backup roll 33 when it passes through the secondary transfer position 18 is the image forming surface (= front surface). That is, at the position adjustment unit 50 and the delivery point D1, the paper P is transported with the back surface facing upward.

[0084] (Receiving the form) After the paper P passes through the fixing device 40, the paper 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 point D2 (an example of a receiving point). At the receiving point D2, the gripper 42 holding the leading edge of the paper P is released, and the paper P is received from the circular path D onto the paper transport path A.

[0085] (double-sided printing) During double-sided printing, the sheet P received by the sheet transport path A after passing through the receiving point D2 is transported to the direction-changing path B, where its transport direction is changed, and then transported to the sheet transport path A toward the secondary transfer position 18 via the merging path. At this time, the sheet P whose transport direction has been changed by the direction-changing path B and whose transport direction is toward the secondary transfer position 18 via the merging path has a side facing upside down opposite to the side of the sheet P that is transported from the supply tray 38 to the secondary transfer position 18 via the merging path. In other words, the sheet P whose transport direction has been changed by the direction-changing path B and whose transport direction is toward the secondary transfer position 18 via the merging path is transported with its front side facing upward. The sheet P transported to the sheet transport path A toward the secondary transfer position 18 via the merging path is then handed over to the circulation path D again at the delivery point D1, and then turned over along the outer periphery of the transfer body 36 and transported to the secondary transfer position 18. At this time, the side of the sheet P facing the backup roll 33 is the back side, so an image is formed on the back side. That is, the conveyor chain 49 along the circular path D constitutes a part of the back-side conveyance path for forming an image on the back side of the paper P.

[0086] <effect> Next, the operation of the image forming apparatus according to the first embodiment of the present invention will be described.

[0087] 1, in the image forming apparatus 10, the receiving point D2 and the delivery point D1 are both provided on the left side (i.e., the same side) of the secondary transfer position 18 (i.e., the image forming position) on the circular path of the circular path D. With this configuration, the size of the entire apparatus can be made smaller than in a configuration in which the delivery point D1 and the receiving point D2 are provided on different sides of the image forming position.

[0088] Furthermore, in the image forming apparatus 10, the delivery point D1 is provided below the receiving point D2. With this configuration, it becomes easier to arrange the conveyance path (i.e., the paper discharge path) leading to the paper discharge tray 39 provided downstream of the delivery point D1 on the paper conveyance path A above the conveyance path (i.e., the paper feed path) arranged from the paper tray 38 in the image forming apparatus 10. Furthermore, with this configuration, when the paper discharge tray 39 is positioned at a high position in the image forming device 10 and the paper tray 38 is positioned at a low position, there is no need for an unnecessary height-adjusting transport path to adjust the transport path.

[0089] Furthermore, the circulation path D of the image forming apparatus 10 is configured so that the direction in which the paper P passes through the secondary transfer position 18 (i.e., the image forming position) is inclined upward, from the lower right to the upper left. This allows the horizontal size of the entire apparatus to be smaller than when the paper P passes horizontally. More specifically, because each component provided at the secondary transfer position 18 can be arranged diagonally, the horizontal width can be configured to be shorter than the transport distance of the corresponding part. Furthermore, with this configuration, even when a transfer belt type transfer device or an inkjet type image forming unit, etc., is provided at the secondary transfer position 18, the horizontal length of the entire apparatus can be configured to be shorter than the transport distance of the recording medium, for the same reason.

[0090] Furthermore, in the image forming apparatus 10, the fixing device 40 is disposed above the secondary transfer position 18. With this configuration, heat generated in the fixing device 40 is less likely to be transmitted to the secondary transfer position 18 than in a configuration in which the fixing device 40 is disposed below the secondary transfer position 18. Furthermore, with this configuration, the distance of the transport path between the secondary transfer position 18 and the fixing device 40 can be ensured to be longer than the horizontal distance of the transport path. This makes it easier to ensure space between the secondary transfer position 18 and the fixing device 40 to install a preliminary fixing device for performing preliminary fixing, a static eliminator for performing static elimination processing to improve image quality, and the like.

[0091] Furthermore, in the image forming apparatus 10, the position adjustment unit 50 is disposed horizontally between the fixing device 40 and the secondary transfer position 18. Therefore, the image forming apparatus 10 can reduce the horizontal size of the entire apparatus compared to a configuration in which the position adjustment unit 50 is disposed outside the gap between the fixing device 40 and the secondary transfer position 18 in the horizontal direction.

[0092] Furthermore, in the image forming apparatus 10, the image forming unit, the conveyor chain 49, and the position adjustment unit 50 are all arranged in the same unit 10A. In the comparative example in which the position adjustment unit 50 is arranged in the unit 10B, adjustment of the position adjustment unit 50 during installation of the image forming apparatus 10 requires adjustment that takes into account the installation accuracy of the unit 10B relative to the unit 10A. On the other hand, in the image forming apparatus 10, because the image forming unit, the conveyor chain 49, and the position adjustment unit 50 are all arranged in the same unit 10A, adjustment of the position adjustment unit 50 does not require consideration of the installation accuracy of the unit 10B relative to the unit 10A. Therefore, in the image forming apparatus 10, adjustment of the position adjustment unit 50 during installation of the image forming apparatus 10 can be simplified compared to the comparative example.

[0093] Furthermore, the image forming apparatus 10 has a sloped portion DT where the circuit path D slopes downward from the receiving point D2 toward the transfer point D1. The image forming apparatus 10 also has a configuration in which the position adjustment unit 50 is disposed in a space S sandwiched between the sloped portion DT and the paper transport path A. With this configuration, the distance between the position adjustment unit 50 and the transfer point D1 is shorter than in a configuration in which the position adjustment unit 50 is disposed upstream of the space S in the transport direction of the paper P. Thus, the shorter the distance between the position adjustment unit 50 and the transfer point D1, the less likely it is that a deviation in paper transport accuracy will occur. Therefore, the image forming apparatus 10 has higher positional accuracy of the paper P transported to the transfer point D1 than in a configuration in which the position adjustment unit 50 is disposed upstream of the space S in the transport direction of the paper P. This also improves the accuracy of the position at which the gripper 42 holds the paper P compared to a configuration in which the position adjustment unit 50 is located upstream of the space S in the conveyance direction of the paper P.

[0094] Furthermore, the image forming apparatus 10 has a configuration in which the conveying chain 49 is attached to both axial ends of the gripper 42. Therefore, the image forming apparatus 10 can suppress tilting of the recording medium in the width direction, compared to a configuration in which the conveying chain 49 is attached only to the center of the gripper 42 in the axial direction.

[0095] Furthermore, the image forming apparatus 10 has a configuration in which the conveying chain 49 along the circular path D turns over the paper P on the circular path D. With this configuration, the size of the entire apparatus can be made smaller than in a configuration in which a path for turning over the paper P is provided separately from the circular path D.

[0096] Furthermore, the image forming apparatus 10 has a configuration in which the conveying chain 49 along the circular path D passes through the image forming unit in the process of reversing the front and back of the paper P. With this configuration, the size of the entire apparatus can be made smaller than with a configuration in which the paper reversing path is provided separately from the circular path D (i.e., part of the paper conveying path A).

[0097] Furthermore, in the image forming apparatus 10, the conveying chain 49 along the circular path D constitutes a part of the back-side conveying path for forming an image on the back side of the paper P. With this configuration, the entire apparatus can be made smaller than a configuration in which the circular part and the back-side conveying path are provided separately.

[0098] Furthermore, in the image forming apparatus 10, the position adjustment unit 50 is disposed on a junction path provided between the direction change path B and the transfer point D1 on the paper transport path A. This configuration allows the overall size of the apparatus to be more compact than a configuration in which the junction path and the position adjustment unit 50 are provided separately. This configuration also allows the common position adjustment unit 50 to perform position adjustments for the front side transport of the paper P and for the back side transport. That is, in the image forming apparatus 10, the position adjustment unit 50 serves both as a position adjustment unit for the front side transport and a position adjustment unit for the back side transport. Therefore, this configuration allows the overall size of the apparatus to be more compact than a configuration in which a position adjustment unit for the front side transport path and a position adjustment unit for the back side transport path are provided separately.

[0099] Second Embodiment Next, an image forming apparatus 110 according to a second embodiment of the present invention will be described with reference to Fig. 14. Note that since the image forming apparatus 110 according to the second embodiment is a modified example of the image forming apparatus according to the first embodiment, the same or related numbers will be used where appropriate to omit the description of overlapping content.

[0100] As shown in FIG. 14, image forming apparatus 110 includes unit 110A disposed in the center, unit 110B disposed on the right side, and unit 110C disposed on the left side in the left-right direction of the figure.

[0101] (Paper transport path) Paper transport path A in image forming apparatus 110 is configured to pass through unit 110B, unit 110A, and unit 110C in this order. As a result, paper P transported along paper transport path A is supplied from paper tray 38 arranged in unit 110B, passes through unit 110A, and is discharged to unit 110C.

[0102] In this embodiment, the image forming surface of the paper P is the upper surface when the paper P is stored in the paper tray 38. In other words, the paper P is transported from the state stored in the paper tray 38 to the secondary transfer position 18 without being turned over.

[0103] On the other hand, during double-sided printing, when an image is formed on the reverse side of the image-forming side of the paper P, the paper P is transported along the direction-changing path B provided in units 110C and 110A, where the transport direction is changed, and then the paper P is supplied again to the circular path D. In other words, the direction-changing path B and the circular path D constitute a reverse-side transport path for forming an image on the reverse side of the paper P. In other words, the circular path D constitutes a part of the reverse-side transport path.

[0104] (Circular route) The circular path D in the image forming apparatus 110 is disposed in the left-right direction in Fig. 14 relative to the secondary transfer position 18. A transfer point D1 where the paper P is handed over from the paper transport path A to the circular path D when the paper P is being transported on the front side is disposed on the right side in Fig. 14 relative to the secondary transfer position 18. A receiving point D2 where the paper P is received from the circular path D to the paper transport path A is disposed on the right side in Fig. 14 relative to the secondary transfer position 18. On the other hand, a re-transfer point D3 where the paper P is handed over again from the direction change path B to the circular path D when the paper P is being transported on the back side is disposed on the left side in Fig. 14 relative to the secondary transfer position 18.

[0105] (Position adjustment section) Image forming apparatus 110 is configured to include position adjustment units 50A and 50B. Position adjustment unit 50A is arranged upstream in the paper transport direction from the position where paper transport path A merges with circular path D. On the other hand, position adjustment unit 50B is arranged upstream in the paper transport direction from the position where direction change path B merges with circular path D.

[0106] The position adjustment unit 50A is responsible for adjusting the position of the paper P when it is transported for image formation on the front side. On the other hand, the position adjustment unit 50B is responsible for adjusting the position of the paper P when it is transported for image formation on the back side.

[0107] <effect> The operation of the image forming apparatus 110 according to the second embodiment of the present invention will be described below.

[0108] 14, in image forming apparatus 110, when an image is formed on the back side of paper P after an image is formed on the front side, paper P is turned over at the right end of circuit path D. In other words, circuit path D is configured to include a part of the transport path on the back side of the paper. With this configuration, the size of the entire apparatus is smaller than in a configuration in which the transport path on the back side of the paper and circuit path D are provided separately.

[0109] In addition, in image forming device 110, sprocket 37 is disposed on the right side of secondary transfer position 18 in FIG. 14 so that image formation is performed during the paper inversion process on circular path D. With this configuration, the size of the entire device is smaller than with a configuration in which the paper inversion path is provided separately from circular path D (i.e., part of paper transport path A).

[0110] Furthermore, in image forming apparatus 110, delivery point D1 is located lower than receiving point D2. With this configuration, when paper discharge tray 39 is located at a high position in image forming apparatus 110 and paper tray 38 is located at a low position, it is possible to eliminate unnecessary conveyance paths for adjusting the height of the conveyance path.

[0111] <Other aspects> Although the image forming apparatus according to each embodiment has been described above, it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention.

[0112] For example, in each embodiment, the method of forming an image on the paper P is explained using an electrophotographic method as an example, but it is not limited to this. For example, an inkjet method or an offset printing method may also be adopted.

[0113] Furthermore, the paper transport direction and the layout of each component in each embodiment are examples and can be changed as appropriate. For example, in each embodiment, the paper transport path A may be laid out in the opposite direction.

[0114] Furthermore, the paper tray 38 that supplies the paper P to the paper transport path A may be provided on both the left and right sides of the unit 10A or 110A that includes the image forming section.

[0115] Furthermore, in each of the above embodiments, the gripper 42 is exemplified as a configuration that physically holds the leading edge of the paper, but it is not limited to such a structure and may, for example, hold the leading edge of the paper P by the force of sucking air. [Explanation of symbols]

[0116] 10 Image forming device 18 Secondary transfer position (equivalent to an example of an image forming position) 40 Fixing section 42 Gripper (equivalent to an example of a holding unit) 49 Conveyor chain (equivalent to an example of a circular part) 50 Position adjustment section A Paper transport path D Circular Route D1 Delivery point D2 Receiving point DT slope part P Paper (equivalent to an example of recording media)

Claims

1. a holding unit that holds the recording medium to be conveyed; a rotating section that rotates while fixing the holding section and that forms part of a transport path along which the recording medium is transported; an image forming unit that forms an image on the recording medium at an image forming position on the rotation path of the rotation unit; a transfer point on the circular path where the recording medium is transferred; a receiving point that is provided on the same side as the transfer point in the horizontal direction with respect to the image forming position and receives the recording medium from the circulation path; and the circulation path is configured to pass through a fixing unit that fixes an image on the recording medium at a fixing position provided downstream of the image forming unit, A position adjustment unit that adjusts the position of the recording medium is disposed below the fixing position in the conveyance path of the recording medium and between the fixing position and the image forming position in the horizontal direction. Image forming device.

2. The image forming apparatus according to claim 1 , wherein the delivery point is located below the receiving point.

3. 3. The image forming apparatus according to claim 1, wherein the circulation path is configured such that a path along which the recording medium passes through the image forming unit is inclined upward.

4. The image forming apparatus is composed of a plurality of units, a position adjusting unit that adjusts the position of the recording medium; 4. The image forming apparatus according to claim 1, wherein the image forming section, the rotation section, and the position adjustment section are arranged in the same unit.

5. The circular path has an inclined portion that slopes downward from the receiving point toward the handover point, the inclined portion forms a space between the inclined portion and the conveying path leading to the delivery point, The image forming apparatus according to claim 4 , wherein the position adjustment unit is disposed in the space.

6. An image forming apparatus as described in any one of claims 1 to 5, wherein the circulating portion is attached to both ends of the holding portion in the width direction of the recording medium being transported.

Images