Paper conveying device and image forming device

Abstract

To reduce an occurrence of a transport failure compared to maintaining a constant suction area in a width direction of paper regardless of a size of the paper when transporting the paper on which an image has been transferred, to a fixing device while sucking the paper.SOLUTION: A transport mechanism sucks paper P on which an image has been transferred and transports it to a fixing device. A switching mechanism switches a suction area in a width direction of the transport mechanism corresponding to a width direction of the paper P according to a size of the paper P.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a paper transport device. [Background technology]

[0002] 2. Description of the Related Art A device for transporting paper in an image forming apparatus is known.

[0003] Patent Document 1 describes a mechanism that changes the area where an adhesive force acts on a sheet of paper being transported by a paper transport belt so that the area is approximately the same as the width of the sheet of paper in a direction perpendicular to the transport direction of the sheet of paper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-316011 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a device that sucks paper onto which an image has been transferred and transports it to a fixing device, if the suction area in the width direction of the paper is kept constant regardless of the size of the paper, depending on the size of the paper, paper jams, misalignment, or paper wrinkles may occur during transport.

[0006] The object of the present invention is to suppress the occurrence of transport problems when transporting paper with an image transferred thereon to a fixing device while suctioning the paper, compared to when the suction area in the width direction of the paper is maintained constant regardless of the size of the paper. [Means for solving the problem]

[0007] The invention according to claim 1 is It consists of an intake section and multiple conveyor belts.a conveying mechanism that conveys the paper onto which the image has been transferred to a fixing device while suctioning the paper; and a switching mechanism that switches a suction area in the width direction of the conveying mechanism that corresponds to the width direction of the paper according to the size of the paper. an operating unit that is installed between the plurality of conveyor belts and that operates the switching mechanism to switch a suction area in the width direction of the conveyor mechanism; A paper transport device having the above structure.

[0008] The invention of claim 2 is a paper conveying device as described in claim 1, in which a virtual line is defined connecting the position where the image is transferred to the paper and the position where the image is fixed to the paper by the fixing device, and the conveying mechanism is installed at a position farther from the virtual line than a first position where no area is secured between the virtual line and the conveying mechanism for bending the paper.

[0009] The invention of claim 3 is a paper transport device as described in claim 2, in which the transport mechanism is installed at a second position farther from the virtual line than the first position and closer to the virtual line than the second position where transport problems may occur with the paper.

[0010] The invention of claim 4 is a paper transport device described in any one of claims 1 to 3, wherein the switching mechanism switches between a first suction area in the width direction of the transport mechanism and a second suction area different from the first suction area depending on the size of the paper, and in the first suction area, the width direction ends of the paper are not sucked by the transport mechanism, and in the second suction area, suction is performed including the area outside the width direction ends of the paper.

[0011] The invention according to claim 5 is 10. An image forming apparatus including the paper transport device according to claim 1, wherein the operation unit is installed closer to the front of the image forming apparatus than the center of the transport mechanism in the width direction. is. The invention of claim 6 is the image forming apparatus of claim 5, wherein the operating unit is installed between the first and second of the multiple conveying belts from the front side of the image forming apparatus. [Effects of the Invention]

[0012] According to the invention of claim 1, when a sheet of paper with an image transferred thereon is suctioned while being transported to a fixing device, the occurrence of transport problems can be suppressed compared to when the suction area in the width direction of the paper is maintained constant regardless of the size of the paper.

[0013] According to the invention as set forth in claim 2, the paper can be conveyed to the fixing device in a flexed state.

[0014] According to the invention of claim 3, it is possible to suppress sheet transport failures compared to when the transport mechanism is installed at a position farther from the imaginary line than the second position.

[0015] According to the invention of claim 4, it is possible to prevent a decrease in suction force for relatively narrow paper, while preventing transport problems from occurring for relatively wide paper.

[0016] Claim 5 ,6 According to the invention, when a paper transport device is installed in an image forming device that forms an image on paper, it becomes easier for an operator to operate the operation unit compared to when the operation unit is installed in the center of the transport mechanism. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a secondary transfer unit, a fixing device, and a paper transport device. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 2 is a diagram showing the configuration of the paper transport device other than the transport belt. [Figure 6] FIG. [Figure 7] FIG. 2 is a diagram showing the configuration of the paper transport device other than the transport belt. [Figure 8] FIG. [Figure 9] FIG. 2 is a diagram illustrating a secondary transfer unit, a fixing device, and a paper transport device. [Figure 10] FIG. 2 is a diagram illustrating a secondary transfer unit, a fixing device, and a paper transport device. [Figure 11]FIG. 2 is a diagram illustrating a secondary transfer unit, a fixing device, and a paper transport device. [Figure 12] FIG. 2 is a diagram illustrating a secondary transfer unit, a fixing device, and a paper transport device. [Figure 13] 10A and 10B are diagrams illustrating the results of conveyance depending on the distance between the virtual line and the paper conveying device. [Figure 14] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] An image forming apparatus according to an embodiment will be described with reference to FIG. 1. For convenience of explanation, an X direction, a Y direction, and a Z direction that are orthogonal to each other are defined. The X direction and the Y direction are horizontal directions, and the Z direction is vertical. For example, the X direction corresponds to the width direction of the image forming apparatus 10, the Y direction corresponds to the depth direction of the image forming apparatus 10, and the Z direction corresponds to the height direction of the image forming apparatus 10. Note that the names of the width direction, depth direction, and height direction of the image forming apparatus 10 are given for convenience of explanation and do not limit the significance of each direction of the image forming apparatus 10.

[0019] The image forming apparatus 10 includes an image forming section 12, a storage section 14, a conveying section 16, and a control device 18.

[0020] The image forming unit 12 forms a toner image by, for example, electrophotography. The storage unit 14 stores paper P, which is an example of a recording medium. The transport unit 16 transports the paper P stored in the storage unit 14 along a transport path 20 toward the image forming unit 12. The transport unit 16 also transports the paper P transported along the transport path 20 along a reversing path 22 to invert the paper P and transport it again toward the image forming unit 12.

[0021] The toner image formed by the image forming unit 12 is formed on the surface of the paper P transported along the transport path 20. The paper P on which the toner image has been formed is discharged to the outside of the housing 10a of the image forming apparatus 10.

[0022] When a toner image is formed on the back side of the paper P, the paper P with the toner image formed on the front side is transported along the reverse path 22, and the toner image is again formed on the back side of the paper P by the image forming unit 12. The paper P is then ejected to the outside of the housing 10a. Note that, in the example shown in FIG. 1, the image forming device 10 has the function of forming a toner image on both sides of the paper P, but it may also have the function of forming a toner image on only one side of the paper P.

[0023] The image forming unit 12 includes, for example, image forming units 24Y, 24M, 24C, and 24K, a transfer unit 26, and a fixing device 28, and forms a toner image for each color. The image forming unit 24Y forms a yellow (Y) toner image using yellow (Y) toner. The image forming unit 24M forms a magenta (M) toner image using magenta (M) toner. The image forming unit 24C forms a cyan (C) toner image using cyan (C) toner. The image forming unit 24K forms a black (K) toner image using black (K) toner. The transfer unit 26 transfers the toner images formed by the image forming units 24Y, 24M, 24C, and 24K to the paper P. The fixing device 28 fixes the toner images transferred to the paper P by the transfer unit 26 to the paper P. Although four colors of toner are used in the example shown in FIG. 1, this is merely an example, and five or more colors of toner may be used. For example, other spot colors may be used in addition to yellow, magenta, cyan, and black. Alternatively, only black toner may be used.

[0024] The image forming units 24Y, 24M, 24C, and 24K have basically the same configuration except for the toner used. For example, the image forming units 24Y, 24M, 24C, and 24K each include a rotating cylindrical image carrier, a charger that charges the image carrier, an exposure device, and a developing device. The exposure device irradiates the charged image carrier with light to form an electrostatic latent image. The developing device develops the electrostatic latent image into a toner image using a developer containing toner.

[0025] The transfer unit 26 includes a transfer belt 30, a primary transfer roll 32, a secondary transfer roll 34, and a roll 36. The transfer belt 30 is wound around multiple rolls including the roll 36 and rotates in the direction of the arrow in FIG. 1. Between the secondary transfer roll 34 and the transfer belt 30, a secondary transfer unit NT (i.e., Nip portion) is formed, which transfers a toner image onto the paper P.

[0026] The fixing device 28 is disposed downstream of the secondary transfer portion NT in the conveying direction of the paper P.

[0027] The storage section 14 includes a storage member 38 and a feed roll 40. The storage member 38 stores the paper sheet P. The feed roll 40 feeds the paper sheet P stored in the storage member 38 to the transport path 20.

[0028] The transport section 16 includes a plurality of transport rolls and a paper transport device 42. The paper P sent out from the storage section 14 is transported along the transport path 20 by the plurality of transport rolls. The paper transport device 42 transports the paper P onto which the toner image has been transferred while sucking it, and delivers it to the fixing device 28.

[0029] The control device 18 controls each part of the image forming apparatus 10 .

[0030] According to the image forming apparatus 10, an image is formed on the paper P as will be described below.

[0031] First, in each of the image forming units 24Y, 24M, 24C, and 24K, the surface of the image carrier is charged by a charger, and the surface of the image carrier is exposed to light by an exposure device to form an electrostatic latent image. The electrostatic latent image is then developed by a development device. As a result, a toner image is formed on the surface of the image carrier. The toner images of each color are transferred sequentially to the transfer belt 30 by a primary transfer roll 32.

[0032] The paper P is sent out from the storage member 38 to the transport path 20 by the delivery roll 40, and is sent along the transport path 20 to the secondary transfer unit NT. At the secondary transfer unit NT, the paper P is transported between the transfer belt 30 and the secondary transfer roll 34, so that the toner image transferred to the transfer belt 30 is transferred onto the surface of the paper P.

[0033] The paper P onto which the toner image has been transferred is transported by the paper transport device 42 to the fixing device 28. The toner image transferred onto the surface of the paper P is fixed to the paper P by the fixing device 28. The paper P onto which the toner image has been fixed is ejected to the outside of the housing 10a.

[0034] When a toner image is also formed on the back side of the paper P, the transport unit 16 transports the paper P that has passed through the fixing device 28 along the reversal path 22 to invert the paper P, and transports the inverted paper P along the transport path 20 to the secondary transfer unit NT. The toner image is transferred to the back side of the paper P at the secondary transfer unit NT, and the toner image is fixed to the paper P by the fixing device 28. The paper P with the fixed toner image is discharged from the housing 10a to the outside.

[0035] The paper transport device 42 will be described below with reference to Figures 2 and 3. Figure 2 shows the secondary transfer unit NT, the fixing device 28, and the paper transport device 42. Figure 3 shows the configuration of the paper transport device 42 when viewed from the Z direction.

[0036] As shown in FIG. 2, the paper transport device 42 is disposed downstream of the secondary transfer unit NT and upstream of the fixing device 28 in the paper transport direction.

[0037] The fixing device 28 includes a fixing roll 28a and a pressure roll 28b. The fixing roll 28a and the pressure roll 28b are cylindrical rolls mounted on a rotation shaft whose axis is in the Y direction and are rotatable. The fixing roll 28a is rotated by a motor (not shown). The fixing roll 28a also has a built-in heater such as a halogen lamp and heats the paper P. The pressure roll 28b is disposed opposite the fixing roll 28a across the transport path of the paper P. The pressure roll 28b is pressed against the fixing roll 28a by an elastic member such as a spring. As a result, the pressure roll 28b presses the paper P toward the fixing roll 28a. A fixing section N (i.e., a nip section) that fixes the toner image to the paper P is formed between the fixing roll 28a and the pressure roll 28b. The paper P transported to the fixing section N is heated by the fixing roll 28a and pressed toward the fixing roll 28a by the pressure roll 28b. This fixes the toner image to the paper P. Alternatively, a fixing belt wound around the fixing roll 28a may be used, and a fixing section N may be formed between the fixing belt and the pressure roll 28b, so that the toner image is fixed to the paper P.

[0038] 2, a virtual line V is defined. The virtual line V is a line connecting the position where the toner image is transferred onto the paper P (i.e., the secondary transfer portion NT) and the position where the toner image is fixed onto the paper P by the fixing device 28 (i.e., the fixing portion N).

[0039] The paper transport device 42 includes transport belts 44A, 44B, 44C, and 44D, support rolls 46A, 46B, 46C, and 46D, drive rolls 48A, 48B, 48C, and 48D, an air intake unit 50, and a shutter 52.

[0040] Conveyor belts 44A, 44B, 44C, and 44D are belts for conveying paper P. Conveyor belt 44A is wound around support roll 46A and drive roll 48A. Conveyor belt 44B is wound around support roll 46B and drive roll 48B. Conveyor belt 44C is wound around support roll 46C and drive roll 48C. Conveyor belt 44D is wound around support roll 46D and drive roll 48D.

[0041] The support rolls 46A, 46B, 46C, and 46D are cylindrical members whose axial direction is in the Y direction, and are arranged at intervals in the Y direction on the secondary transfer unit NT side (i.e., upstream side) of the intake unit 50. The support rolls 46A, 46B, 46C, and 46D are attached to a rotation shaft 54 ​​whose axial direction is in the Y direction. The rotation shaft 54 ​​is supported by a bearing member (not shown) and is rotatable.

[0042] Drive rolls 48A, 48B, 48C, and 48D are cylindrical members whose axial direction is in the Y direction, and are arranged at intervals in the Y direction on the fixing device 28 side (i.e., downstream side) of intake section 50. Drive rolls 48A, 48B, 48C, and 48D are attached to a rotation shaft 56 whose axial direction is in the Y direction. Rotation shaft 56 is supported by a bearing member (not shown), and is rotated by being driven by a motor (not shown).

[0043] The support roll 46A and the drive roll 48A are arranged with the intake section 50 between them in the transport direction of the paper P. The support roll 46B and the drive roll 48B are arranged with the intake section 50 between them in the transport direction of the paper P. The support roll 46C and the drive roll 48C are arranged with the intake section 50 between them in the transport direction of the paper P. The support roll 46D and the drive roll 48D are arranged with the intake section 50 between them in the transport direction of the paper P.

[0044] The conveyor belts 44A, 44B, 44C, and 44D are, for example, endless belts (e.g., silicone rubber belts). The conveyor belts 44A, 44B, 44C, and 44D are formed with a plurality of holes 58 that penetrate from the inside to the outside.

[0045] The intake unit 50 draws in air inside the conveyor belts 44A, 44B, 44C, and 44D. For example, an intake fan is disposed inside the intake unit 50. When the intake fan is operated, the intake unit 50 draws in air above the conveyor belts 44A, 44B, 44C, and 44D. As a result, the paper P is attracted to the conveyor belts 44A, 44B, 44C, and 44D.

[0046] When the motor rotates the rotary shaft 56, thereby rotating the drive rolls 48A, 48B, 48C, and 48D, the conveyor belts 44A, 44B, 44C, and 44D revolve to convey the paper P from the secondary transfer unit NT to the fixing device 28. The air intake unit 50 also draws in air above the conveyor belts 44A, 44B, 44C, and 44D, so that the paper P is attracted to the conveyor belts 44A, 44B, 44C, and 44D and conveyed from the secondary transfer unit NT to the fixing device 28. The conveyance direction T of the paper P is shown in FIGS. 2 and 3.

[0047] The conveyor belts 44A, 44B, 44C, and 44D and the air intake unit 50 are an example of a conveyor mechanism.

[0048] The shutter 52 is disposed in the space between the support rolls 46A, 46B, 46C, 46D and the drive rolls 48A, 48B, 48C, 48D in the space between the conveyor belts 44A, 44B, 44C, 44D and the suction unit 50. The shutter 52 is a member that is movable in the width direction of the conveyor mechanism, and is a member that switches the suction area in the width direction of the conveyor mechanism by moving in the width direction of the conveyor. The shutter is an example of a switching mechanism.

[0049] The width direction of the transport mechanism refers to the width direction of the transport belts 44A, 44B, 44C, and 44D. The width direction of the transport mechanism coincides, for example, with the axial direction of the rotation shafts 54 and 56 (i.e., the direction in which the support roll and drive roll extend) and coincides with the direction perpendicular to the direction in which the transport belts 44A, 44B, 44C, and 44D rotate. In the example shown in FIG. 3, the Y direction is the width direction of the transport mechanism. The width direction of the transport mechanism corresponds to the width direction of the paper P. Here, as an example, the width direction of the paper P is defined as the width direction of the transport mechanism.

[0050] As shown in FIG. 3, the paper transport device 42 further includes a knob 60 and a guide member 62. The knob 60 is a member for operating the movement of the shutter 52 in the width direction of the transport mechanism. The knob 60 is a member that is movable between the rotation shaft 54 ​​and the rotation shaft 56. The guide member 62 is a member that is disposed between the rotation shaft 54 ​​and the rotation shaft 56 and guides the movement of the knob 60. A groove is formed in the guide member 62 along the direction from the rotation shaft 54 ​​to the rotation shaft 56, and the knob 60 is moved along the groove. The knob 60 is operated by an operator such as a user.

[0051] For example, the knob 60 and the guide member 62 are installed between the conveyor belts 44C and 44D. In other words, the knob 60 and the guide member 62 are installed closer to the end of the conveyor mechanism than the center O in the width direction of the conveyor mechanism. The top of the knob 60 is installed at a position lower than the surface of the conveyor belts 44A, 44B, 44C, and 44D through which the paper P passes (i.e., the surface to which the paper P is attracted). This prevents the knob 60 from obstructing the conveyance of the paper P.

[0052] The widthwise center O of the conveying mechanism corresponds to the widthwise center when the conveying belts 44A, 44B, 44C, and 44D are arranged in that order, and more specifically, corresponds to the center between the conveying belts 44B and 44C.

[0053] Because the knob 60 is disposed closer to the end than the center O, it is easier to operate the knob 60 from the end side (for example, the conveyor belt 44D side) than when the knob 60 is disposed at the center O. For example, when the conveyor belt 44D is disposed on the front side of the image forming apparatus 10, it is easier to operate the knob 60 from the front side than when the knob 60 is disposed at the center O. In other words, because the knob 60 is disposed closer to the front than the center O, the distance from the front side to the knob 60 is shorter than when the knob 60 is disposed at the center O, so it is possible to operate the knob 60 without having to reach all the way to the back of the image forming apparatus 10.

[0054] The shutter 52 will be described in detail below with reference to Figures 4 and 5. Figure 4 shows the shutter 52. Figure 5 shows the configuration of the paper transport device 42, excluding the transport belts 44A, 44B, 44C, and 44D.

[0055] The shutter 52 has a rectangular frame shape as a whole. Specifically, the shutter 52 includes short side members 52a and 52b and long side members 52c and 52d.

[0056] The short side members 52a and 52b are members facing each other. The short side members 52a and 52b are arranged in the direction from the rotation shaft 54 ​​to the rotation shaft 56 in the spaces between the support rolls 46A, 46B, 46C, and 46D and the drive rolls 48A, 48B, 48C, and 48D. The short side member 52a is arranged closer to the position where the support roll 46A and the drive roll 48A are arranged than the center O in the width direction of the conveying mechanism, and the short side member 52b is arranged closer to the position where the support roll 46D and the drive roll 48D are arranged than the center O in the width direction of the conveying mechanism.

[0057] The long side members 52c and 52d are opposed to each other. The long side members 52c and 52d are arranged along the rotation shafts 54 and 56 in the spaces between the support rolls 46A, 46B, 46C, and 46D and the drive rolls 48A, 48B, 48C, and 48D. The long side member 52c is arranged on the rotation shaft 56 side, and the long side member 52d is arranged on the rotation shaft 54 ​​side.

[0058] The short-side members 52a and 52b are connected by the long-side members 52c and 52d. That is, the end of the short-side member 52a facing the rotation shaft 56 is connected to one end of the long-side member 52c, and the end of the short-side member 52b facing the rotation shaft 56 is connected to the other end of the long-side member 52c. Furthermore, the end of the short-side member 52a facing the rotation shaft 54 ​​is connected to one end of the long-side member 52d, and the end of the short-side member 52b facing the rotation shaft 54 ​​is connected to the other end of the long-side member 52d.

[0059] The shutter 52 may be a single component in which the short side members 52a, 52b and the long side members 52c, 52d are integrated, or the short side members 52a, 52b and the long side members 52c, 52d may be separate components, and the shutter 52 may be formed by assembling the short side members 52a, 52b and the long side members 52c, 52d.

[0060] The space 52e is a space surrounded by the short side members 52a and 52b and the long side members 52c and 52d. The intake unit 50 draws air above the conveyor belts 44A, 44B, 44C, and 44D through the space 52e.

[0061] The short side members 52a and 52b function as members that block the intake by the intake unit 50. That is, the intake unit 50 takes in air through the space 52e, but the short side members 52a and 52b block the intake by the intake unit 50 at the locations where the short side members 52a and 52b are arranged, and the intake unit 50 does not take in air above the conveyor belts 44A, 44B, 44C, and 44D. Therefore, the paper P is attracted to the conveyor belts 44A, 44B, 44C, and 44D by the intake unit 50 at the locations corresponding to the space 52e, but is not attracted at the locations where the short side members 52a and 52b are arranged.

[0062] Side 52f of short-side member 52b, which contacts space 52e, is formed obliquely with respect to the direction from rotation shaft 54 ​​toward rotation shaft 56. For example, side 52f is formed obliquely so that the width of short-side member 52b (i.e., the length in the direction corresponding to the width direction of the conveying mechanism) gradually increases from the rotation shaft 54 ​​side toward rotation shaft 56 side. In other words, side 52f is formed obliquely from short-side member 52b side toward short-side member 52a side, from long-side member 52d to long-side member 52c.

[0063] The portion of side 52f on the rotation shaft 54 ​​side and the portion on the rotation shaft 56 side are formed along the direction from rotation shaft 54 ​​to rotation shaft 56 so that knob 60 can be disposed thereon. In the example shown in Fig. 4, knob 60 is disposed on the portion of side 52f on the rotation shaft 54 ​​side.

[0064] A portion 52g of the long-side member 52d corresponding to the center O of the conveying mechanism in the width direction protrudes toward the space 52e. A support member 52h is installed on the space 52e side of the protruding portion 52g. One end of a spring 52k is attached to the support member 52h. The spring 52k is installed along the width direction of the conveying mechanism. As shown in FIG. 5, the other end of the spring 52k is attached to a member 64. The member 64 is arranged closer to the short-side member 52a than the spring 52k. The spring 52k applies a force acting in the width direction of the conveying mechanism to the shutter 52. The spring 52k is an example of an elastic member. Rubber or the like may be used as an elastic member other than the spring 52k.

[0065] As described with reference to Fig. 3, the knob 60 is a member that can move along the guide member 62 between the rotation shaft 54 ​​and the rotation shaft 56. More specifically, the knob 60 can move in the A1 direction or the A2 direction between the long side member 52c and the long side member 52d within the space 52e. The A1 direction is the direction toward the long side member 52d. The A2 direction is the direction toward the long side member 52c.

[0066] In response to movement of the knob 60 in the A1 direction or the A2 direction, the shutter 52 is moved in the width direction of the transport mechanism.

[0067] Specifically, when the knob 60 is moved in the A1 direction, the shutter 52 is moved toward the conveyor belt 44A in the width direction of the conveyor mechanism. In the example shown in Fig. 4, the shutter 52 is moved in the B1 direction. As the shutter 52 moves, the spring 52k expands, generating an elastic force in the direction toward the conveyor belt 44D (the B2 direction in Fig. 4).

[0068] Furthermore, when the knob 60 is moved in the A2 direction, the shutter 52 is moved toward the conveyor belt 44D in the width direction of the conveyor mechanism. In the example shown in Fig. 4, the shutter 52 is moved in the B2 direction. As the shutter 52 moves, the spring 52k contracts, generating an elastic force in the direction toward the conveyor belt 44A (the B1 direction in Fig. 4).

[0069] The operation of shutter 52 will be described below with reference to Fig. 5 to Fig. 8. Fig. 6 and Fig. 8 are diagrams showing paper transport device 42. Fig. 7 is a diagram showing the configuration of paper transport device 42, excluding transport belts 44A, 44B, 44C, and 44D. In Fig. 6 and Fig. 8, shutter 52 is shown by a dashed line.

[0070] When the knob 60 is moved in the A1 direction, the shutter 52 is moved toward the conveyor belt 44A, i.e., in the B1 direction, as shown in FIGS. 5 and 6. This defines at least the center O and its surrounding area as the area where air is sucked by the suction unit 50. The area where air is sucked when the shutter 52 is moved in the B1 direction is an example of the second suction zone. As shown in FIG. 6, the area having a width W2 in the width direction of the conveyor mechanism is the second suction zone. In the areas outside the second suction zone in the width direction, the short-side members 52a and 52b block the air from the holes 58. For example, the air from the holes 58 formed in the conveyor belt 44A is blocked by the short-side member 52a, and the air from the holes 58 formed in the conveyor belt 44D is blocked by the short-side member 52b. As a result of the air being blocked in the areas outside the second suction zone, the suction force in the second suction zone increases.

[0071] When the knob 60 is moved in the A2 direction, the shutter 52 is moved toward the conveyor belt 44D, i.e., in the B2 direction, as shown in FIGS. 7 and 8. As a result, the center O, its periphery, the widthwise end regions of the conveyor belt 44A, and the widthwise end regions of the conveyor belt 44D are defined as regions to be sucked by the air intake unit 50. That is, air is sucked by the air intake unit 50 not only through the holes 58 formed in the center O and its periphery, but also through the holes 58 formed at the outermost widthwise positions of the conveyor belt 44A and the holes 58 formed at the outermost widthwise positions of the conveyor belt 44D. The suction region when the shutter 52 is moved in the B2 direction is an example of a first suction region. As shown in FIG. 8, the region having a width W4 in the width direction of the conveyor mechanism is the first suction region. That is, a first suction area is formed from the position of the hole 58 formed on the outermost side in the width direction of the conveyor belt 44A to the position of the hole 58 formed on the outermost side in the width direction of the conveyor belt 44D.

[0072] In this way, the shutter 52 has a function of switching the area in the width direction of the transport mechanism where air is sucked by the air intake unit 50. In other words, the shutter 52 has a function of switching the area in the width direction of the transport mechanism where the paper P is sucked.

[0073] For example, the first suction area and the second suction area can be switched by moving the knob 60 in the A1 direction or the A2 direction depending on the size of the paper P. The knob 60 functions as an operating unit for operating the shutter 52 to switch the suction area.

[0074] For example, as shown in Fig. 6, when paper P having a width W1 in the width direction of the conveying mechanism is used, the knob 60 is moved in the A1 direction as shown in Fig. 5. This causes the shutter 52 to move in the B1 direction as shown in Figs. 5 and 6, and as a result, the center O and its surroundings are defined as the area to be sucked in by the suction unit 50 (i.e., the second suction area having a width W2).

[0075] A sheet of paper P having a width W1 passes through an area including the center O of the sheet transport device 42. For example, the sheet of paper P is transported by the transport belts 44B and 44C while being sucked through some of the holes 58 formed in the transport belts 44B and 44C.

[0076] As described above, in the outer region of the second suction area in the width direction, the suction force in the second suction area increases because the short side members 52a and 52b block the intake of air from the holes 58. This increases the suction force on the paper P, preventing paper jams and other transport problems caused by a decrease in suction force.

[0077] As shown in FIG. 6, the width W2 of the second suction zone is longer than the width W1 of the paper P, and the second suction zone is wider than the paper P in the width direction of the transport mechanism. Therefore, the paper P is sucked, including the area outside the ends of the paper P in the width direction. In other words, a suction zone having a width W2 wider than the width W1 of the paper P is formed, so the entire width of the paper P is sucked, and further, the outside areas of the paper P in the width direction are also sucked. When small-sized paper P, such as paper P having a width W2, is used, the ambient temperature may rise. By sucking the areas outside the ends of the paper P in the width direction, the ambient temperature rise is suppressed.

[0078] For example, when postcard-sized paper P (e.g., paper 100 mm wide and 148 mm long) is used, it is assumed that the knob 60 is moved in the A1 direction to set the second suction zone. This increases the suction force on the paper P when using relatively small-sized paper P, preventing transport problems. When using paper like postcard-sized paper P, which is narrow, has a length in the transport direction T that is shorter than the distance between the secondary transfer unit NT and the fixing unit N, and is longer than the length of the paper transport device 42 in the transport direction T, forming the first suction zone to suck the paper P weakens the suction force on the paper P, which can result in transport problems such as paper jams. Furthermore, when images are formed on both sides of the paper P, the front and back sides may become misaligned. By increasing the suction force by forming the second suction zone, transport problems such as paper jams are prevented, and transport problems such as paper jams are also prevented.

[0079] Furthermore, for example, when a sheet P having a width W3 in the width direction of the conveying mechanism is used as shown in Fig. 8, the knob 60 is moved in the direction A2 as shown in Fig. 7. This causes the shutter 52 to move in the direction B2 as shown in Figs. 7 and 8. As a result, the center O, its periphery, the regions on the widthwise end sides of the conveyor belt 44A, and the regions on the widthwise end sides of the conveyor belt 44D are defined as the region where air is sucked by the air suction unit 50 (i.e., the first suction region). In other words, the first suction region is formed from the position of the hole 58 formed on the outermost side in the width direction of the conveyor belt 44A to the position of the hole 58 formed on the outermost side in the width direction of the conveyor belt 44D.

[0080] A sheet of paper P having a width W3 passes through an area including the center O of the sheet transport device 42. For example, the sheet of paper P is sucked through a plurality of holes 58 formed in all of the transport belts (i.e., transport belts 44A, 44B, 44C, and 44D) and transported by all of the transport belts.

[0081] 8, the width W4 of the first suction area is shorter than the width W3 of the paper P, and the first suction area is narrower than the paper P in the width direction of the transport mechanism. Therefore, both ends of the paper P in the width direction are not sucked by the suction unit 50. In this way, because the ends of the paper P in the width direction are not sucked, the ends of the paper P are prevented from being sucked and getting caught on the transport belts 44A, 44D, and as a result, the occurrence of paper wrinkles and the like is prevented.

[0082] For example, when A4-sized paper P (e.g., paper 210 mm wide and 297 mm long) or wider paper P (e.g., paper approximately 330 mm wide) is used, it is assumed that the knob 60 is moved in the A2 direction to set the first suction zone. Also, when thin paper P (e.g., paper approximately 52 gsm) is used, it is assumed that the first suction zone is set. When such paper P is used, forming the second suction zone to suck the paper P may cause transport problems such as twisting or flapping of the paper P between the secondary transfer unit NT and the fixing unit N. In contrast, forming the first suction zone, which is wider than the second suction zone, to suck the paper P prevents transport problems such as twisting or flapping. For example, when thin paper P is used, forming the second suction zone may cause unstable behavior at both ends of the paper P in the width direction, which may result in damage or wrinkles on the paper P when the paper P is transported to the fixing unit N. By forming the first suction area and sucking the sheet P in an area wider than the second suction area, the behavior of both widthwise ends of the sheet P is stabilized, preventing damage to the sheet P and the occurrence of paper wrinkles.

[0083] 9 to 12, the positional relationship between the imaginary line V and the paper transport device 42 will be described. 9 to 12 show the secondary transfer section NT, the fixing device 28, and the paper transport device 42.

[0084] There are various transport modes depending on the length of the paper P in the transport direction T. For example, the following modes (1) and (2) are assumed. Hereinafter, the length of the paper P in the transport direction T will be referred to as the "length of the paper P."

[0085] Mode (1) When the length of the paper P is longer than the distance between the secondary transfer section NT and the fixing section N, the leading end portion of the paper P may be located at the fixing section N, and the trailing end portion of the paper P may be located at the secondary transfer section NT.

[0086] Mode (2) When the length of the paper P is shorter than the distance between the secondary transfer unit NT and the fixing unit N, the leading edge of the paper P may be located at the fixing unit N, and the trailing edge of the paper P may not be located at the secondary transfer unit NT. Alternatively, the leading edge of the paper P may not reach the fixing unit N, and the trailing edge of the paper P may be located at the secondary transfer unit NT. In these cases, the leading edge of the paper P may not be located at the fixing unit N, and the trailing edge of the paper P may not be located at the secondary transfer unit NT.

[0087] 9 to 11 show the embodiment (1), and FIG. 12 shows the embodiment (2).

[0088] For example, if the size of the paper P is A4 size (e.g., paper with a width of 210 mm and a length of 297 mm), then mode (1) occurs. If the size of the paper P is postcard size (e.g., paper with a width of 100 mm and a length of 148 mm), then mode (2) occurs.

[0089] In the following, for ease of explanation, paper P whose length is longer than the distance between the secondary transfer unit NT and the fixing unit N will be referred to as "long paper P," and paper P whose length is shorter than the distance between the secondary transfer unit NT and the fixing unit N will be referred to as "short paper P."

[0090] The paper transport device 42 is installed at a position farther from the imaginary line V than the first position. The first position is a position where no area is secured between the imaginary line V and the paper transport device 42 for bending the paper P. The paper transport device 42 is installed at a position closer to the imaginary line V than the second position. The second position is a position farther from the imaginary line than the first position, and is a position where transport problems with the paper P may occur. In other words, the paper transport device 42 is installed at a position farther from the imaginary line V than the first position and closer to the imaginary line V than the second position. This allows the long paper P to be conveyed from the secondary transfer unit NT to the fixing unit N while being deflected, and allows the short paper P to be conveyed from the secondary transfer unit NT to the fixing unit N while suppressing a decrease in suction force on the short paper P. This point will be described in detail below.

[0091] When a long sheet of paper P is used, if the leading edge of the sheet of paper P is located at the fixing unit N and the trailing edge of the sheet of paper P is located at the secondary transfer unit NT, paper wrinkles and the like may occur. For example, if the transport speed of the sheet of paper P at the fixing unit N is slower than the transport speed of the sheet of paper P at the secondary transfer unit NT, the trailing edge of the sheet of paper P will be transported faster than the leading edge, which may result in paper wrinkles and the like. To prevent this, the sheet of paper P is bent between the virtual line V and the sheet transport device 42 between the secondary transfer unit NT and the fixing unit N. The sheet transport device 42 is installed at a position where an area for bending the sheet of paper P can be secured between the virtual line V and the sheet transport device 42. The position where an area for bending the sheet of paper can be secured is a position farther from the virtual line V than the first position. By installing the sheet transport device 42 at a position farther from the virtual line V than the first position, the sheet of paper P is bent between the virtual line V and the sheet transport device 42, preventing paper wrinkles and the like.

[0092] The longer the distance between the virtual line V and the paper transport device 42 (i.e., the farther the paper transport device 42 is from the virtual line V), the wider the area in which the paper P is bent, resulting in a lower frequency of paper wrinkles and the like. On the other hand, the farther the paper transport device 42 is from the virtual line V, the weaker the suction by the air intake unit 50 at the position of the virtual line V, resulting in a weaker suction force on the paper P. If the paper transport device 42 is installed at a position farther from the virtual line V than the second position, problems with suction-based transport will occur. In other words, suction force sufficient for suction-based transport will not be obtained, resulting in transport problems. For example, when short paper P is used, the paper P may stand up between the secondary transfer unit NT and the fixing unit N, causing transport problems such as paper jams. To prevent this, the paper transport device 42 is installed at a position closer to the virtual line V than the second position.

[0093] In the example shown in Fig. 9, paper transport device 42 is placed at a position where the linear distance between virtual line V and paper transport device 42 is distance L1. The position of distance L1 corresponds to the first position. When paper transport device 42 is placed at this position, as shown in Fig. 9, no area is secured between virtual line V and paper transport device 42 in which paper P can bend.

[0094] In the example shown in Fig. 10, the paper transport device 42 is installed at a position where the linear distance between the virtual line V and the paper transport device 42 is distance L2. Distance L2 is longer than distance L1, and the position at distance L2 corresponds to the second position. When the paper transport device 42 is installed at this position, an area for bending the paper P is secured between the virtual line V and the paper transport device 42, as shown in Fig. 10. However, when short paper P is used, the suction force on the paper P decreases, which can result in transport problems.

[0095] In the example shown in FIG. 11, the paper transport device 42 is installed at a position where the linear distance between the virtual line V and the paper transport device 42 is distance L3. Distance L3 is the distance between distances L1 and L2, and the position of distance L3 is farther from the virtual line V than the first position and closer to the virtual line V than the second position. By installing the paper transport device 42 at the third position, the long paper P is transported while being bent between the virtual line V and the paper transport device 42, between the secondary transfer unit NT and the fixing unit N, and a decrease in the suction force on the short paper P is suppressed. This prevents the long paper P from wrinkling and other problems from occurring, and prevents the short paper P from being transported improperly.

[0096] FIG. 13 shows the results of transport depending on the distance L between the imaginary line V and the paper transport device 42.

[0097] If the distance L is 4 mm or less, an area for bending the long paper P is not secured between the virtual line V and the paper conveying device 42 (bending area "X" in Figure 13), and poor conveyance (e.g., paper wrinkles) occurs for the long paper P (e.g., A4 size paper) (running property "X" in Figure 13).

[0098] If the distance L is greater than 4 mm and equal to or less than 8 mm (4 to 8 mm), there is insufficient area for bending the long paper P (bending area "△" in FIG. 13), and conveyance problems such as paper wrinkles may occur in the long paper P (running property "△" in FIG. 13). Note that when short paper P (e.g., postcard-sized paper) is used, the suction force of the suction unit 50 is increased (e.g., the suction force is increased by about 20 to 50%), and the area of ​​the suction area in the paper conveying device 42 is reduced (e.g., by 70 to 90% of the area).

[0099] When the distance L is greater than 8 mm and less than 14 mm (8 to 14 mm), an area is secured to deflect the long paper P (deflection area "◯" in Figure 13), and the occurrence of paper wrinkles, etc. is prevented (traveling property "◯" in Figure 13).

[0100] If the distance L is 14 mm or more, an area for bending long paper P is secured (bending area "◯" in Figure 13), but the suction force for sucking and transporting short paper P is not obtained, resulting in poor transport of short paper P (running ability "×" in Figure 13).

[0101] 13, a distance between 4 and 8 mm corresponds to an example of distance L3. In other words, by arranging paper transport device 42 at a position where distance L from virtual line V is in the range of 4 to 8 mm, paper P can be transported without transport failures occurring for both long paper P and short paper P.

[0102] 13 are merely examples and may vary depending on the distance between the secondary transfer unit NT and the fixing unit N, the size of the interior of the image forming apparatus 10, the strength of the suction force of the intake unit 50, and the size of the paper transport device 42. For example, it is expected that the distance L3 can be obtained by experiment, simulation, etc. for each image forming apparatus 10 or each type of apparatus.

[0103] The shape of the knob 60 will be described below with reference to Fig. 14. Fig. 14 is a perspective view of the knob 60. The knob 60 has a disk-like shape. A recess 60a is formed in the circumferential direction along the side surface of the knob 60. For example, it is expected that a worker such as a user will operate the knob 60 by hooking their finger into the recess 60a. [Explanation of symbols]

[0104] 10 image forming device, 42 paper transport device, 44A, 44B, 44C, 44D transport belt, 50 suction unit, 52 shutter, 60 knob.

Claims

1. A conveying mechanism that is composed of an intake section and a plurality of conveying belts and that conveys paper onto which an image has been transferred to a fixing device while sucking the paper; a switching mechanism for switching a suction area in the width direction of the conveying mechanism corresponding to the width direction of the paper in accordance with the size of the paper; an operating unit that is installed between the plurality of conveyor belts and that operates the switching mechanism to switch a suction area in the width direction of the conveyor mechanism; A paper transport device having:

2. a virtual line is defined that connects a position where the image is transferred onto the paper and a position where the image is fixed onto the paper by the fixing device; The transport mechanism includes: the conveying mechanism is disposed at a position farther from the imaginary line than a first position where no area for bending the paper is secured between the imaginary line and the conveying mechanism; The paper transport device according to claim 1 .

3. The transport mechanism includes: a second position that is farther from the virtual line than the first position and that is closer to the virtual line than the second position at which a paper transport failure may occur; The paper transport device according to claim 2 .

4. The switching mechanism is switching between a first suction area in the width direction of the conveying mechanism and a second suction area different from the first suction area according to the size of the paper; In the first suction zone, the edge of the paper in the width direction is not suctioned by the conveyance mechanism, In the second suction area, suction is performed including an area outside the edge of the paper in the width direction. The paper transport device according to any one of claims 1 to 3.

5. An image forming apparatus equipped with the paper conveying device according to claim 1, the operation unit is installed closer to the front of the image forming apparatus than the center of the transport mechanism in the width direction; Image forming device.

6. The operation unit is installed between the first and second conveyor belts from the front side of the image forming device, The image forming apparatus according to claim 5 .

Images