Image forming apparatus
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KONICA MINOLTA INC
- Filing Date
- 2025-01-22
- Publication Date
- 2026-08-03
Smart Images
Figure 2026125273000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an image forming apparatus.
Background Art
[0002] In an image forming apparatus, a technique is known in which the stiffness of a sheet of paper, which is a recording medium, is detected, and various control parameters for forming an image on the paper and the like are set based on the detection result. Various developments have also been made on a stiffness measurement unit for measuring the stiffness of paper, and the applicant of the present application has also filed an application for a stiffness measurement unit, and its content has already been published (see Patent Document 1). Briefly explaining the configuration of the stiffness measurement unit according to the prior art (referred to as a stiffness measurement device in Patent Document 1), it is as follows.
[0003] The stiffness measurement unit includes a holding unit that holds the paper being conveyed in the vertical direction, and a pressing member (referred to as a pressing unit in Patent Document 1) that presses the paper horizontally below the holding position of the holding unit. Further, the stiffness measurement unit includes a stiffness detection unit (referred to as a pressing force detection unit in Patent Document 1) that detects the reaction force from the paper bent by the pressing member as the stiffness of the paper. Furthermore, the stiffness measurement unit includes a pressing movement unit (referred to as a movement mechanism in Patent Document 1) that linearly moves the pressing member in the horizontal direction.
[0004] According to the configuration of the stiffness measurement unit according to the prior art, the stiffness of the paper can be detected by the pressing member linearly moving horizontally and pressing the paper while the paper being conveyed in the vertical direction is held by the holding unit. Thereby, in the detection of the stiffness of the paper, the influence of the gravity acting on the paper can be suppressed, and the detection accuracy of the stiffness measurement unit can be improved.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
[0006] Incidentally, in the stiffness measuring unit of the prior art, the pressing member presses the paper while moving linearly in the horizontal direction, while the paper is bent in an arc shape around the holding position of the holding part. Therefore, when the pressing member presses the paper, a displacement (positional misalignment) occurs at the tip of the pressing member relative to the paper, and consequently, the catching force (frictional force) of the pressing member against the paper is generated as noise in the detection of the paper's stiffness. For this reason, further improvements are desired in the stiffness measuring unit of the prior art in order to further improve the accuracy of detecting the paper's stiffness.
[0007] Therefore, the object of the present invention is to provide an image forming apparatus that can further improve the accuracy of detecting the stiffness of a recording medium such as paper. [Means for solving the problem]
[0008] One aspect of the image forming apparatus of the present invention is: A holding unit that holds the recording medium in transit in the vertical direction, A pressing member that presses the paper below the holding position of the holding part, A stiffness detection unit detects the reaction force from the recording medium being bent by the pressing member as the stiffness of the recording medium, The system includes a pressing movement unit that moves the pressing member to suppress displacement of the tip of the pressing member relative to the recording medium when the pressing member presses the recording medium. [Effects of the Invention]
[0009] According to the present invention, the accuracy of detecting the rigidity of the recording medium can be further improved. [Brief explanation of the drawing]
[0010] [Figure 1] Figure 1 is a schematic diagram showing the image forming system according to this embodiment. [Figure 2] Figure 2 is a schematic plan view of the stiffness measurement unit according to this embodiment. [Figure 3] Figure 3 is an enlarged view along line II in Figure 2, showing the state before the pressing member presses against the paper. [Figure 4] Figure 4 is an enlarged view along line II in Figure 2, showing the state after the pressing member has pressed the paper. [Figure 5] Figure 5 is a schematic plan view of a stiffness measuring unit according to another embodiment of this model. [Figure 6] Figure 6 is an enlarged view along the line II-II in Figure 5, showing the state before the pressing member presses against the paper. [Figure 7] Figure 7 is an enlarged view along the line II-II in Figure 5, showing the state after the pressing member has pressed the paper. [Figure 8] Figure 8 is a schematic plan view of a stiffness measuring unit according to another embodiment of this model. [Figure 9] Figure 9 is an enlarged view along the line III-III in Figure 8, showing the state before the pressing member presses against the paper. [Figure 10] Figure 10 is an enlarged view along the line III-III in Figure 8, showing the state after the pressing member has pressed the paper. [Figure 11] Figure 11 is a control block diagram of the image forming system according to this embodiment. [Modes for carrying out the invention]
[0011] Hereinafter, this embodiment will be described with reference to the drawings. In the specification and claims of the present application, the upstream side refers to the upstream side in the conveyance direction of a recording medium such as paper, and the downstream side refers to the downstream side in the conveyance direction of a recording medium such as paper. The vertical direction is not limited to the exact vertical direction, but includes a direction inclined within a range of ±30 degrees with respect to the exact vertical direction. In the drawings, "front" indicates the front direction, "rear" indicates the rear direction, "left" indicates the left direction, "right" indicates the right direction, "up" indicates the upward direction, and "down" indicates the downward direction, respectively.
[0012] Referring to FIG. 1, an overview of the image forming system 10 according to this embodiment will be described. FIG. 1 is a schematic diagram showing the image forming system 10 according to this embodiment.
[0013] As shown in FIG. 1, the image forming system 10 according to this embodiment is a system that forms an image on a sheet S as an example of a recording medium and performs post-processing on the sheet S on which the image has been formed. The image forming system 10 includes a tandem type image forming apparatus 12, and the image forming apparatus 12 is an apparatus that forms an image on the sheet S by an electrophotographic method. The image forming system 10 includes a paper feeding apparatus 14 installed upstream of the image forming apparatus 12, and the paper feeding apparatus 14 is an apparatus that feeds the sheet S toward the image forming apparatus 12.
[0014] The image forming system 10 includes a paper conveyance apparatus (medium conveyance apparatus) 16 installed between the image forming apparatus 12 and the paper feeding apparatus 14, and the paper conveyance apparatus 16 is an apparatus that conveys the sheet S fed from the paper feeding apparatus 14 to the image forming apparatus 12. The image forming system 10 includes a post-processing apparatus 18 installed downstream of the image forming apparatus 12, and the post-processing apparatus 18 is an apparatus that performs post-processing on the sheet S on which the image has been formed.
[0015] Note that, as described above, the image forming system 10 includes the image forming apparatus 12, the paper feeding apparatus 14, the paper conveyance apparatus 16, and the post-processing apparatus 18. However, it may be considered that the image forming apparatus 12 includes the paper feeding apparatus 14, the paper conveyance apparatus 16, and the post-processing apparatus 18. In other words, it may be considered that the paper feeding apparatus 14, the paper conveyance apparatus 16, and the post-processing apparatus 18 respectively constitute a part of the image forming apparatus 12.
[0016] Subsequently, referring to FIG. 1, the configuration of the image forming apparatus 12 will be described.
[0017] As shown in FIG. 1, the image forming apparatus 12 includes a box-shaped apparatus main body (apparatus main body for the image forming apparatus) 20, and the apparatus main body 20 constitutes the base frame of the image forming apparatus 12. Further, an image forming unit 22 for forming an image by an electrophotographic method is provided in the upper part inside the apparatus main body 20. The image forming unit 22 has four image forming units 24Y, 24M, 24C, and 24K for forming an image by each of the colored toners of the Y (yellow) component, M (magenta) component, C (cyan) component, and K (black) component based on image data. The four image forming units 24Y, 24M, 24C, and 24K are arranged along the vertical direction.
[0018] The image forming units 24Y, 24M, 24C, and 24K for the Y component, M component, C component, and K component have the same configuration. For the sake of convenience of illustration and description, common components are denoted by the same reference numerals, and when distinguishing each of them, Y, M, C, or K is added to the reference numeral. In FIG. 1, only the components of the image forming unit 24Y for the Y component are denoted by reference numerals, and the components of the other image forming units 24M, 24C, and 24K are omitted.
[0019] The image forming unit 24 has a photosensitive drum 26, a charging unit (not shown), an exposure unit (not shown), and a developing unit 28.
[0020] The photoreceptor drum 26 is a negatively charged organic photoreceptor, for example, made of aluminum, with an undercoat layer, a charge generation layer, and a charge transport layer sequentially laminated on its circumferential surface. The photoreceptor drum 26 rotates at a constant peripheral speed driven by a rotary motor (not shown). The charging unit uniformly charges the outer surface of the photoreceptor drum 26 with negative polarity. The exposure unit emits laser light as scanning light and scans the outer surface of the photoreceptor drum 26 while exposing it, thereby forming an electrostatic latent image on the outer surface of the photoreceptor drum 26. The developing unit 28 deposits toner of each color component onto the outer surface of the photoreceptor drum 26, thereby visualizing the electrostatic latent image on the outer surface of the photoreceptor drum 26 and forming a toner image.
[0021] As shown in Figure 1, a transfer unit 30 for transferring a toner image onto paper S is provided in the upper part of the main body 20 of the device. The transfer unit 30 has an endless intermediate transfer belt 32 and a secondary transfer roller 34.
[0022] The intermediate transfer belt 32 extends vertically so as to face the multiple photoreceptor drums 26 and is stretched over multiple support rollers (not shown). The intermediate transfer belt 32 rotates due to the rotation of the multiple support rollers. A primary transfer nip CN is formed between the outer surface of the intermediate transfer belt 32 and the outer surface of each photoreceptor drum 26 for transferring the toner image from each photoreceptor drum 26 to the intermediate transfer belt 32.
[0023] The secondary transfer roller 34 is positioned on the outer circumferential side of the intermediate transfer belt 32. The secondary transfer roller 34 rotates in cooperation with the intermediate transfer belt 32 while holding the paper S. A secondary transfer nip TN is formed between the outer circumferential surface of the secondary transfer roller 34 and the outer circumferential surface of the intermediate transfer belt 32 for transferring the toner image from the intermediate transfer belt 32 to the paper S.
[0024] As the intermediate transfer belt 32 passes through the primary transfer nip CN, the toner image on the photoreceptor drum 26 is sequentially transferred onto the intermediate transfer belt 32 as a primary transfer. Subsequently, as the paper S passes through the secondary transfer nip TN, the toner image on the intermediate transfer belt 32 is transferred to the paper S as a secondary transfer, forming an image on the paper S.
[0025] As shown in Figure 1, a fixing unit 36 for fixing the toner image to the paper S is provided at the exit side of the secondary transfer nip TN inside the main body 20 of the device. The fixing unit 36 has a heating roller 38, a fixing roller 40, an endless fixing belt 42, and a pressure roller 44.
[0026] The heating roller 38 has a hollow cylindrical core and a heating device (not shown), such as a halogen lamp, provided inside the core. The fixing roller 40 is positioned opposite the heating roller 38. The fixing roller 40 has a hollow cylindrical core and a surface layer provided on the outer surface of the core, which is made of, for example, silicone rubber. The fixing belt 42 is stretched between the heating roller 38 and the fixing roller 40. The fixing belt 42 rotates as the heating roller 38 and the fixing roller 40 rotate.
[0027] The pressure roller 44 is located on the outside of the fixing belt 42, facing the fixing roller 40, and presses toward the fixing roller 40 with a predetermined fixing load. The pressure roller 44 has a hollow cylindrical core, an elastic layer made of, for example, silicone rubber, provided on the outer surface of the core, and a surface layer made of, for example, a PFA tube, provided on the surface of the elastic layer. A fixing nip FN is also formed between the fixing roller 40 and the pressure roller 44 for transporting the paper S while heating and pressurizing it.
[0028] As the pressure roller 44 rotates due to the drive of the rotary motor, the fixing belt 42 follows and rotates. As the fixing belt 42 rotates, the heating roller 38 and the fixing roller 40 follow and rotate. This allows the paper S to be transported while being heated and pressurized at the fixing nip FN, thereby fixing any unarrived toner images to the paper S.
[0029] As shown in Figure 1, the main transport path 46 is provided inside the main body 20 for transporting the paper S fed from the paper transport device 16 toward the post-processing device 18. The main transport path 46 extends from the paper transport device 16 side toward the post-processing device 18 side. The main transport path 46 is a path for transporting the paper S fed from the paper transport device 16 toward the post-processing device 18 side via the secondary transfer nip TN and the fixing nip FN. The main transport path 46 has a plurality of transport roller pairs 48, including a register roller pair 48R, and the plurality of transport roller pairs 48 are rotated by the drive of a transport motor (not shown).
[0030] Below the main transport path 46 within the device body 20, a reversal transport path 50 is provided for reversing the front and back sides of the paper S. The reversal transport path 50 is the path for transporting the paper S when forming a toner image on the back side of the paper S. The inlet end of the reversal transport path 50 is connected to the downstream side of the fuser nip FN in the main transport path 46. The outlet end of the reversal transport path 50 is connected to the upstream side of the register roller pair 48R in the main transport path 46. The reversal transport path 50 has a plurality of transport roller pairs 52, which are rotated by the drive of a transport motor (not shown).
[0031] The paper S, fed from the paper transport device 16, is transported by the main transport path 46 towards the secondary transfer nip TN via the secondary transfer nip TN and the fixing nip FN. At this time, the tilt of the paper S is corrected by the registration roller pair 48R, and the transport timing of the paper S is adjusted. Then, at the secondary transfer nip TN, the toner image from the intermediate transfer belt 32 is transferred to one side (front or back) of the paper S in one go, and at the fixing nip FN, the toner image is fixed to the paper S. After that, the image-formed paper S is transported to the post-processing device 18.
[0032] Next, with reference to Figure 1, the configuration of the paper feed device 14 will be briefly explained.
[0033] As shown in Figure 1, the paper feeder 14 is a device that feeds paper S to the image forming apparatus 12, as described above. In other words, the paper feeder 14 is a device that feeds paper S to the paper transport device 16. The paper feeder 14 is part of the image forming system 10, but it can also be considered as part of the image forming apparatus 12. The paper feeder 14 also includes a box-shaped device body (device body for the paper feeder) 54 installed to the left of the main body 20 for the image forming apparatus, and the device body 54 constitutes the base frame of the paper feeder 14.
[0034] The main body 54 of the device is equipped with multiple paper feed trays 56 for accommodating multiple sheets of paper S, and the multiple paper feed trays 56 are arranged in a stepped manner along the vertical direction. Each paper feed tray 56 accommodates a predetermined type of paper S according to its basis weight, size, etc. The main body 54 of the device is also equipped with a paper feed transport path 58 for feeding paper from each paper feed tray 56 to the paper transport device 16. The paper feed transport path 58 has multiple transport roller pairs 60, and the multiple transport roller pairs 60 are rotated by the drive of a transport motor (not shown).
[0035] Next, with reference to Figure 1, the configuration of the paper transport device (media transport device) 16 will be described.
[0036] As shown in Figure 1, the paper transport device 16 is a device that transports the paper S fed from the paper feeder 14 to the image forming apparatus 12, as described above. The paper transport device 16 is part of the image forming system 10, but it may also be considered as part of the image forming apparatus 12. The paper transport device 16 also includes a box-shaped device body (device body for the paper transport device) 62 installed between the device body 20 for the image forming apparatus and the device body 54 for the paper feeder, and the device body 62 constitutes the base frame of the paper transport device 16.
[0037] The main body 62 of the device is provided with a main transport path 64 for transporting paper S fed from the paper feeder 14 to the image forming apparatus 12. The main transport path 64 extends in a left-right direction from the paper feeder 14 side to the image forming apparatus 12 side. The inlet end of the main transport path 64 is connected to the outlet end of the paper feed transport path 58 of the paper feeder 14. The outlet end of the main transport path 64 is connected to the inlet end of the main transport path 46 of the image forming apparatus 12. The main transport path 64 has a plurality of transport roller pairs 66, and the plurality of transport roller pairs 66 are rotated by the drive of a transport motor (not shown).
[0038] A stiffness measuring unit 68 for measuring the stiffness of the paper S is provided above the main transport path 64 within the main body 62 of the device. Details of the stiffness measuring unit 68 will be described later. In addition, a paper output tray 70 for ejecting the paper S whose stiffness has been measured is provided at the top of the main body 62.
[0039] The main body 62 of the device is provided with a vertical transport path 72 for transporting paper S, which has been fed from the middle of the main transport path 64, to the output tray 70 via the stiffness measuring unit 68. The vertical transport path 72 extends vertically from the main transport path 64 side to the output tray 70 side. The inlet end of the vertical transport path 72 is connected to the middle of the main transport path 64, and the outlet end of the vertical transport path 72 is connected to the inlet side of the output tray 70. The vertical transport path 72 also has a plurality of transport roller pairs 74, which are rotated by the drive of a transport motor (not shown). The plurality of transport roller pairs 74 include a holding roller pair 74G which constitutes a holding part that forms part of the stiffness measuring unit 68. Furthermore, a path switching unit 76 (see Figure 11) is provided at an appropriate location within the main body 62 to switch the transport path of paper S from the main transport path 64 to the vertical transport path 72.
[0040] As shown in Figure 1, a paper sensor 78 is provided below the holding roller pair 74G within the main body 62 of the device, serving as a paper detection unit for detecting the paper S. The paper sensor 78 consists of, for example, a reflective or transmissive photosensor, and detects the rear end of the paper S in the transport direction as it is being transported vertically by changes in the light reception intensity.
[0041] Next, with reference to Figure 1, the configuration of the post-processing device 18 will be briefly explained.
[0042] As shown in Figure 1, the post-processing device 18 is a device that performs post-processing on the image-formed paper S, as described above. The post-processing device 18 is part of the image forming system 10, but it may also be considered as part of the image forming apparatus 12. The post-processing device 18 also includes a box-shaped device body (device body for the post-processing device) 80 installed to the left of the main body 20 for the image forming apparatus, and the main body 80 constitutes the base frame of the post-processing device 18.
[0043] The main body 80 of the device is equipped with a post-processing unit 82 for performing post-processing on the image-formed paper S, such as stapling, cutting, and perforating. A paper output tray 84 for discharging the post-processed paper S is provided on the left side of the main body 80. Above the paper output tray 84 on the left side of the main body 80 is a paper output tray 86 for discharging the paper S that has not undergone post-processing.
[0044] The main body 80 of the device is provided with a paper discharge transport path 88 for transporting paper S sent from the image forming apparatus 12 to the paper discharge tray 84 via the post-processing unit 82. The inlet end of the paper discharge transport path 88 is connected to the outlet end of the main transport path 64 of the image forming apparatus 12. The outlet end of the paper discharge transport path 88 is connected to the inlet side of the paper discharge tray 84. The paper discharge transport path 88 has a plurality of transport roller pairs 90, which are rotated by the drive of a transport motor (not shown).
[0045] The main body 80 of the device is provided with a paper discharge transport path 92 for transporting paper S sent from the image forming apparatus 12 to the paper discharge tray 86 without passing through the post-processing unit 82. The inlet end of the paper discharge transport path 92 is connected to the outlet end of the main transport path 64 of the image forming apparatus 12. The outlet end of the paper discharge transport path 92 is connected to the paper discharge tray 86. The paper discharge transport path 92 has a plurality of transport roller pairs 94, which are rotated by the drive of a transport motor (not shown).
[0046] Next, the specific configuration of the stiffness measuring unit 68 according to this embodiment will be described with reference to Figures 1 to 4. Figure 2 is a schematic plan view of the stiffness measuring unit 68 according to this embodiment. Figures 3 and 4 are enlarged views along line II in Figure 2, with Figure 3 showing the state before the pressing member 102 presses the paper S, and Figure 4 showing the state after the pressing member 102 presses the paper S.
[0047] As shown in Figures 1 to 4, the stiffness measuring unit 68 is equipped with a pair of holding rollers 74G as a holding part that grips and holds the paper S being transported in the vertical direction from the horizontal direction (horizontal left-right direction). The pair of holding rollers 74G is provided on a support frame 96 which is a fixed part fixed inside the main body of the device 62 and extends in the horizontal front-rear direction. The pair of holding rollers 74G has a drive roller 98 which is rotatably provided on the support frame 96 and rotates by the drive of a transport motor (not shown). The drive roller 98 is configured to stop rotating when the paper sensor 78 detects the rear end in the transport direction of the paper S being transported in the vertical direction.
[0048] The holding roller pair 74G has a driven roller 100 that is rotatably mounted on the support frame 96 and rotates in conjunction with the rotation of the drive roller 98. The driven roller 100 works in cooperation with the drive roller 98 to grip the paper S from the horizontal left and right directions. In addition, a spring (not shown) is provided at an appropriate position on the support frame 96 to bias the driven roller 100 toward the drive roller 98. The holding position of the holding roller pair 74G is the position in which the paper S is held by the holding roller pair 74G, and in this embodiment, it is the position in which the paper S is gripped by the cooperation of the drive roller 98 and the driven roller 100.
[0049] As shown in Figures 2 to 4, a pressing member 102 is provided between the holding roller pair 74G and the paper sensor 78, below the holding position of the holding roller pair 74G, to press the paper S horizontally to the left. The pressing member 102 presses the paper S horizontally to the left while the paper S is being transported vertically and is being held by the holding roller pair 74G. The pressing member 102 extends horizontally in the front-rear direction, and the tip side (left end side) of the pressing member 102 is formed in a plate shape. The cross-sectional shape of the tip of the pressing member 102 along the vertical direction may be a curved shape (R shape).
[0050] A stiffness sensor 104 is provided at the base end of the pressing member 102, and the stiffness sensor 104 detects the reaction force from the paper S that is bent by the pressing member 102 as the stiffness of the paper S. It may also be thought of that the stiffness sensor 104 is connected to the base end of the pressing member 102. For example, a load cell can be used as the stiffness sensor 104.
[0051] The stiffness measuring unit 68 includes a pressing movement unit 106 that moves the pressing member 102 so that the pressing member 102 bends the paper S. The pressing movement unit 106 moves the pressing member 102 so that when the pressing member 102 presses the paper S, the tip of the pressing member 102 traces an arc around the holding position of the holding roller pair 74G. In other words, the pressing movement unit 106 moves the pressing member 102 so as to suppress the displacement (positional misalignment) of the tip of the pressing member 102 relative to the paper S when the pressing member 102 presses the paper S. The pressing movement unit 106 may also move the pressing member 102 so that the tip of the pressing member 102 traces an arc around the vicinity of the holding position of the holding roller pair 74G.
[0052] The pressing and moving section 106 has a U-shaped arm section 110 in plan view, which is pivotably mounted on the support frame 96 around the axes of a pair of pivot shafts 108, and the arm section 110 extends in the front-rear direction. The axis of each pivot shaft 108 is the horizontal pivot axis of the arm section 110, which passes through the holding position of the holding roller pair 74G. The axis of each pivot shaft 108 may also be a horizontal pivot axis that passes near the holding position of the holding roller pair 74G.
[0053] A stiffness sensor 104 is connected to the central part of the arm portion 110. In other words, the central part of the arm portion 110 is connected to the pressing member 102 via the stiffness sensor 104. To put it another way, the pressing member 102 is mounted on the support frame 96 so as to be able to swing around the axis of a pair of pivot shafts 108 via the arm portion 110 and the stiffness sensor 104. The distance from the axis of each pivot shaft 108 to the tip of the pressing member 102 is the same as the distance from the holding position of the holding roller pair 74G to the pressing position of the pressing member 102. The pressing position of the pressing member 102 is the position where the paper S is pressed by the pressing member 102.
[0054] The pressing and moving section 106 has a cam mechanism 112 for swinging the arm section 110 around the axis of the pivot shaft 108. The cam mechanism 112 has contact pieces 114 integrally provided on both ends of the arm section 110, and each contact piece 114 protrudes to the right. The cam mechanism 112 has a cam shaft 116 rotatably provided on the right side of the retaining roller pair 74G in the support frame 96, and the cam shaft 116 extends in the front-rear direction.
[0055] The cam mechanism 112 has cam plates 118 integrally provided on both ends of the cam shaft 116, and each cam plate 118 contacts each contact piece 114. The rotation center of each cam plate 118 is eccentric with respect to the axis of the cam shaft 116. The outer shape of each cam plate 118 is formed such that the distance from the contact position between the contact piece 114 and the cam plate 118 to the axis of the cam shaft 116 changes with the rotation of the cam shaft 116. The cam mechanism 112 also has a spring 120 provided between an appropriate position on the support frame 96 and each contact piece 114. Each spring 120 biases the arm portion 110 in the opposite direction (counterclockwise in Figures 3 and 4) so that each contact piece 114 contacts each cam plate 118.
[0056] The pressing and moving section 106 is provided at an appropriate position on the support frame 96 and has a rotary motor 122 as a rotary actuator that rotates each cam plate 118 integrally with the cam shaft 116. The output shaft (not shown) of the rotary motor 122 is linked to the cam shaft 116 via a gear train (not shown) or the like. Each cam plate 118 rotates in the forward direction (clockwise in Figures 3 and 4) and the reverse direction (counterclockwise in Figures 3 and 4) by the drive of the rotary motor 122.
[0057] According to the configuration of the stiffness measuring unit 68, when the paper sensor 78 detects the trailing end of the paper S in the transport direction while it is being transported vertically, the rotation of the drive roller 98 and the driven roller 100 stops. As a result, as shown in Figure 3, the paper S being transported vertically is held by the holding roller pair 74G from the horizontal direction.
[0058] Then, as shown in Figures 3 and 4, the rotation motor 122 drives each cam plate 118 in the forward direction, causing the arm portion 110 to swing in the forward direction around the axis of the pivot shaft 108 against the biasing force of each spring 120. As a result, the pressing member 102 moves so that its tip traces an arc around the holding position of the holding roller pair 74G, pressing the paper S. At this time, the stiffness sensor 104 detects the reaction force from the paper S being bent by the pressing member 102 as the stiffness of the paper S.
[0059] After detecting the stiffness of the paper S, the cam plates 118 are rotated in opposite directions by the drive of the rotary motor 122, returning the arm portion 110 and the pressing member 102 to their original positions. The rotation of the drive roller 98 and the driven roller 100 is then resumed to transport the paper S, whose stiffness has been detected, in the vertical direction.
[0060] Next, with reference to Figures 1, 5 to 7, the configuration of another aspect of the stiffness measuring unit 124 according to this embodiment will be described. Figure 5 is a schematic plan view of another aspect of the stiffness measuring unit 124 according to this embodiment. Figures 6 and 7 are enlarged views along the line II-II in Figure 5, where Figure 6 shows the state before the pressing member 102 presses the paper S, and Figure 7 shows the state after the pressing member 102 presses the paper S.
[0061] As shown in Figure 1, the paper transport device 16 may be equipped with a stiffness measuring unit 124 according to another embodiment of this embodiment instead of the stiffness measuring unit 68 according to this embodiment. The stiffness measuring unit 124 according to another embodiment of this embodiment has the same configuration as the stiffness measuring unit 68 according to this embodiment. The differences in the configuration of the stiffness measuring unit 124 according to another embodiment of this embodiment from the configuration of the stiffness measuring unit 68 according to this embodiment will be described below. For the sake of convenience of explanation, components that have the same function as the components described in the stiffness measuring unit 68 according to this embodiment will be denoted by the same reference numerals and their descriptions will not be repeated.
[0062] As shown in Figures 5 to 7, the stiffness measuring unit 124 includes a pressing movement unit 126 that moves the pressing member 102 so that the pressing member 102 bends the paper S. The pressing movement unit 126 moves the pressing member 102 so that the tip of the pressing member 102 traces an arc around the holding position of the holding roller pair 74G, while maintaining the posture of the pressing member 102 when the pressing member 102 presses the paper S. In other words, the pressing movement unit 126 moves the pressing member 102 so as to suppress the displacement (positional misalignment) of the tip of the pressing member 102 relative to the paper S when the pressing member 102 presses the paper S. The pressing movement unit 126 may also move the pressing member 102 so that the tip of the pressing member 102 traces an arc around the vicinity of the holding position of the holding roller pair 74G.
[0063] The pressing and moving section 126 has guide members 128 provided on the underside of each end of the holding roller pair 74G in the support frame, which serves as the fixed section. Each guide member 128 guides each side end of the pressing member 102 so as to maintain the posture of the pressing member 102. Each guide member 128 has an arc-shaped first guide groove 128c formed therein. The first guide groove 128c of each guide member 128 slidably guides the first slider 130 provided at the tip end portion of the side end of the pressing member 102. In other words, the first guide groove 128c of each guide member 128 slidably guides the tip end portion of the side end of the pressing member 102 via the first slider 130.
[0064] A second arc-shaped guide groove 128g is formed in each guide member 128 at a position shifted diagonally downward to the right with respect to the first guide groove 128c. The second guide groove 128g of each guide member 128 slidably guides the second slider 132, which is provided at the base end portion of the side end of the pressing member 102. In other words, the second guide groove 128g of each guide member 128 slidably guides the base end portion of the side end of the pressing member 102 via the second slider 132.
[0065] Here, the radius of curvature and center of curvature of the first guide groove 128c, the radius of curvature and center of curvature of the second guide groove 128g, etc. are set so that the tip of the pressing member 102 traces an arc centered on or near the holding position of the holding roller pair 74G.
[0066] The pressing movement section 126 has a cam mechanism 134 for moving the pressing member 102 while each side end of the pressing member 102 is guided by each guide member 128. The cam mechanism 134 has a contact plate 136 integrally connected to the stiffness sensor 104, and the contact plate 136 extends in the front-rear direction. The cam mechanism 134 has a cam shaft 138 rotatably provided on the right side of the retaining roller pair 74G in the support frame 96, and the cam shaft 138 extends in the front-rear direction.
[0067] The cam mechanism 134 has a pair of cam plates 140 integrally provided on the central side of the cam shaft 138, and the pair of cam plates 140 are spaced apart in the front-rear direction. Each cam plate 140 abuts against a contact plate 136, and the center of each cam plate 140 is eccentric with respect to the axis of the cam shaft 138. The outer shape of each cam plate 140 is formed such that the distance from the contact position between the contact plate 136 and the cam plate 140 to the axis of the cam shaft 138 changes with the rotation of the cam shaft 138. The cam mechanism 134 also has a pair of springs 142 provided between an appropriate position on the support frame 96 and the contact plate 136, and biasing the contact plate 136 in the direction of contact with the pair of cam plates 140.
[0068] The pressing and moving section 126 is provided at an appropriate position on the support frame 96 and has a rotary motor 144 as a rotary actuator that rotates each cam plate 140 integrally with the cam shaft 138. The output shaft (not shown) of the rotary motor 144 is linked to the cam shaft 138 via a gear train (not shown) or the like. Each cam plate 140 rotates in the forward direction (clockwise in Figures 6 and 7) and the reverse direction (counterclockwise in Figures 6 and 7) by the drive of the rotary motor 144.
[0069] According to the configuration of the stiffness measuring unit 124, when the paper sensor 78 detects the rear end of the paper S in the transport direction while it is being transported vertically, the rotation of the drive roller 98 and the driven roller 100 stops. As a result, as shown in Figure 6, the paper S being transported vertically is held by the holding roller pair 74G from the horizontal direction.
[0070] Then, as shown in Figures 6 and 7, the rotating motor 144 drives each cam plate 140 to rotate in the forward direction. As a result, while maintaining the posture of the pressing member 102, the pressing member 102 moves so that its tip traces an arc around or near the holding position of the holding roller pair 74G, thereby pressing the paper S. At this time, the stiffness sensor 104 detects the reaction force from the paper S being bent by the pressing member 102 as the stiffness of the paper S.
[0071] After detecting the stiffness of the paper S, the pressing member 102 returns to its original position by rotating each cam plate 140 in the opposite direction using the drive of the rotary motor 144. At the same time, the rotation of the drive roller 98 and the driven roller 100 is resumed to transport the paper S, whose stiffness has been detected, in the vertical direction.
[0072] Next, with reference to Figures 1 and 8 to 10, the configuration of another stiffness measuring unit 146 according to this embodiment will be described. Figure 8 is a schematic plan view of another stiffness measuring unit 146 according to this embodiment. Figures 9 and 10 are enlarged views along the line III-III in Figure 8, where Figure 9 shows the state before the pressing member 102 presses the paper S, and Figure 10 shows the state after the pressing member 102 presses the paper S.
[0073] As shown in Figure 1, the paper transport device 16 may be equipped with a stiffness measuring unit 146 according to another embodiment of this embodiment instead of the stiffness measuring unit 68 according to this embodiment. The stiffness measuring unit 146 according to another embodiment of this embodiment has the same configuration as the stiffness measuring unit 68 according to this embodiment. The differences in the configuration of the stiffness measuring unit 146 according to another embodiment of this embodiment from the configuration of the stiffness measuring unit 68 according to this embodiment will be described below. For the sake of convenience of explanation, the same reference numerals are used for members that have the same function as the members described for the stiffness measuring unit 68 according to this embodiment, and their descriptions will not be repeated.
[0074] As shown in Figures 8 to 10, the stiffness measuring unit 146 includes a pressing movement unit 148 that moves the pressing member 102 so that the pressing member 102 presses and bends the paper S. The pressing movement unit 148 moves the pressing member 102 while maintaining the posture of the pressing member 102 when the pressing member 102 presses the paper S. In other words, the pressing movement unit 148 moves the pressing member 102 in a way that suppresses misalignment between the tip of the pressing member 102 and the paper S when the pressing member 102 presses the paper S.
[0075] The pressing and moving parts 148 are positioned on both ends of the holding roller pair 74G in the support frame 96, which serves as the fixed part, and each has a parallel link mechanism 150 for moving the pressing member 102 horizontally. Each parallel link mechanism 150 has a pair of swing links 154 that are swingably provided on the side end of the holding roller pair 74G in the support frame 96 via a swing shaft 152, and the pair of swing links 154 swing while maintaining a parallel state with each other. Each swing shaft 152 in each parallel link mechanism 150 is rotatably supported by the support frame 96 and is integrally connected to the base end of each swing link 154.
[0076] Each parallel link mechanism 150 has a parallel movement link 156 that connects the ends of a pair of oscillating links 154, and the parallel movement link 156 is movable in the horizontal direction (horizontal left-right direction). The parallel movement link 156 in each parallel link mechanism 150 is connected to each side end of the pressing member 102. In other words, the pressing member 102 is provided on the support frame 96 via a pair of parallel link mechanisms 150. The pressing member 102 is positioned between the pair of parallel link mechanisms 150.
[0077] The pressing and moving section 148 is provided at an appropriate position on the support frame 96 and has a rotary motor 158 as a rotary actuator that rotates a predetermined oscillating shaft 152. The output shaft (not shown) of the rotary motor 158 is linked to the predetermined oscillating shaft 152 via a gear train (not shown) or the like. The predetermined oscillating shaft 152 rotates in the forward direction (clockwise in Figures 9 and 10) and the reverse direction (counterclockwise in Figures 9 and 10) by the drive of the rotary motor 158.
[0078] According to the configuration of the stiffness measuring unit 146, when the paper sensor 78 detects the trailing end of the paper S in the transport direction while it is being transported vertically, the rotation of the drive roller 98 and the driven roller 100 stops. As a result, as shown in Figure 9, the paper S being transported vertically is held by the holding roller pair 74G from the horizontal direction.
[0079] Then, as shown in Figures 9 and 10, the rotation motor 158 drives a predetermined pivot shaft 152 in the forward direction, causing each pair of pivot links 154 to pivot in the forward direction while each translation link 156 moves horizontally to the left. As a result, while maintaining the posture of the pressing member 102, the pressing member 102 moves horizontally in parallel and presses the paper S horizontally. At this time, the stiffness sensor 104 detects the reaction force from the paper S being bent by the pressing member 102 as the stiffness of the paper S.
[0080] After detecting the stiffness of the paper S, the rotary motor 158 drives a predetermined oscillating shaft 152 in the opposite direction, causing each pair of oscillating links 154 to oscillate in the opposite direction, while each translation link 156 moves horizontally to the right, returning the pressing member 102 to its original position. The rotation of the drive roller 98 and the driven roller 100 is then resumed to transport the paper S, whose stiffness has been detected, in the vertical direction.
[0081] The control configuration of the image forming system 10 according to this embodiment will be described with reference to Figures 1 and 11. Figure 11 is a control block diagram of the image forming system 10 according to this embodiment.
[0082] As shown in Figure 11, the image forming system 10 includes a control unit 160 that controls the paper feeder 14, image forming unit 22, transfer unit 30, fixing unit 36, path switching unit 76, stiffness measuring units 68, 124, or 146, post-processing unit 82, etc. The control unit 160 is responsible for controlling the entire image forming system 10. The control unit 160 has a CPU (Central Processing Unit) 162, ROM (Read Only Memory) 164, and RAM (Random Access Memory) 166. The control unit 160 is connected to a storage unit 168, a communication unit 170, a paper sensor 78, etc.
[0083] The CPU 162 provides overall control over the operation of the image forming system 10. The CPU 162 reads various control programs and setting data stored in the ROM 164, stores them in the RAM 166, and executes the programs to perform various calculations. The RAM 166 provides the CPU 162 with working memory space and stores temporary data. The CPU 162 also refers to various data stored in the storage unit 168 when performing various calculations. The storage unit 168 is composed of, for example, a non-volatile semiconductor memory or a hard disk drive.
[0084] The control unit 160 transmits and receives various data to and from external devices (e.g., personal computers) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 170. The control unit 160 receives, for example, a print job sent from an external device and forms a toner image on the paper S based on the image data contained in the print job. The communication unit 170 is composed of, for example, a communication control card such as a LAN card.
[0085] As shown in Figures 1 and 11, when the control unit 160 receives an instruction to measure the stiffness of the paper S, it controls the path switching unit 76 to switch the transport path of the paper S from the main transport path 64 to the vertical transport path 72. By switching the transport path of the paper S from the main transport path 64 to the vertical transport path 72, the control unit 160 can send the paper S from the main transport path 64 to the vertical transport path 72 and transport it vertically by the vertical transport path 72.
[0086] When the control unit 160 detects the rear end of the paper S in the transport direction while it is being transported vertically using the paper sensor 78, it stops the drive of the transport motor (not shown) and stops the rotation of the drive roller 98 (see Figures 2 and 3). By stopping the rotation of the drive roller 98, the control unit 160 allows the holding roller pair 74G to grip and hold the paper S from the horizontal direction while it is being transported vertically.
[0087] The control unit 160 drives the rotary motors 122, 144, or 146 after a predetermined time has elapsed since the paper sensor 78 detected the rear end of the paper S in the transport direction while it was being transported vertically. When the control unit 160 drives the rotary motors 122, 144, or 158, the pressing member 102 moves as described above and presses the paper S, and the stiffness sensor 104 detects this as the stiffness of the paper S.
[0088] The control unit 160 sets various control parameters for image formation on the paper S based on the stiffness of the paper S obtained from the stiffness sensor 104. Examples of these control parameters include the charging potential of the charging section, the transfer current to the secondary transfer roller 34, the fixing current of the fixing section 36, and the fixing temperature of the fixing section 36.
[0089] According to the configuration of the stiffness measuring unit 68, 124, or 146 of this embodiment, as described above, the stiffness of the paper S can be detected when the pressing member 102 presses against the paper S while the paper S is being transported in the vertical direction and is being held by the holding roller pair 74G. Therefore, the influence of gravity acting on the paper S can be suppressed when detecting the stiffness of the paper S.
[0090] Furthermore, as described above, the pressing movement units 106, 126, or 148 move the pressing member 102 in such a way as to suppress the displacement of the tip of the pressing member 102 relative to the paper S when the pressing member 102 presses the paper S. Therefore, the catching force (frictional force) of the pressing member 102 relative to the paper S when the pressing member 102 presses the paper S can be sufficiently suppressed.
[0091] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 68, 124, or 146 can be further improved.
[0092] Furthermore, according to the configuration of the stiffness measuring unit 68 in this embodiment, as described above, the pressing movement unit 106 moves the pressing member 102 such that the tip of the pressing member 102 traces an arc. Therefore, the catching force of the pressing member 102 against the paper S when the pressing member 102 presses the paper S can be suppressed more effectively. In particular, when the tip of the pressing member 102 traces an arc centered on the holding position of the holding roller pair 74G, the catching force of the pressing member 102 can be suppressed even further.
[0093] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 68 can be further improved.
[0094] Furthermore, according to the configuration of the stiffness measuring unit 68 in this embodiment, as described above, the pressing movement unit 106 has an arm portion 110 that can swing around a pivot axis that passes through the holding position of the holding roller pair 74G or its vicinity. The arm portion 110 is connected to the pressing member 102 via a stiffness sensor 104. Therefore, by swinging the arm portion 110 around the pivot axis, the pressing member 102 can be moved so that the tip of the pressing member 102 traces an arc. As a result, the catching force of the pressing member 102 against the paper S when the pressing member 102 presses the paper S can be suppressed more effectively. In particular, when the distance from the axis of each pivot axis 108 to the tip of the pressing member 102 is the same as the distance from the holding position of the holding roller pair 74G to the pressing position of the pressing member 102, the catching force of the pressing member 102 can be further suppressed.
[0095] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 68 can be further improved.
[0096] Furthermore, according to the configuration of the stiffness measuring unit 68, 124, or 146 in this embodiment, as described above, the cross-sectional shape of the tip of the pressing member 102 along the vertical direction is curved. Therefore, the catching force of the pressing member 102 on the paper S when the pressing member 102 presses the paper S can be suppressed more effectively.
[0097] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 68, 124, or 146 can be further improved.
[0098] Furthermore, according to the configuration of the stiffness measuring unit 124 or 146 in this embodiment, as described above, the pressing movement unit 126 or 148 moves the pressing member 102 while maintaining the posture of the pressing member 102 when the pressing member 102 presses the paper S. Therefore, the catching force of the pressing member 102 against the paper S when the pressing member 102 presses the paper S can be suppressed more effectively. In particular, when the tip of the pressing member 102 traces an arc around the holding position of the holding roller pair 74G, the catching force of the pressing member 102 can be suppressed even further.
[0099] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 124 or 146 can be further improved.
[0100] Furthermore, according to the configuration of the stiffness measuring unit 124 in this embodiment, as described above, each guide member 128 guides each side end of the pressing member 102 so as to maintain the posture of the pressing member 102. Therefore, the pressing movement unit 126 can move the pressing member 102 while maintaining the posture of the pressing member 102 when the pressing member 102 presses the paper S. As a result, the catching force of the pressing member 102 on the paper S when the pressing member 102 presses the paper S can be suppressed more effectively.
[0101] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 124 can be further improved.
[0102] Furthermore, according to the configuration of the stiffness measuring unit 146 in this embodiment, as described above, each parallel link mechanism 150 is movable in the horizontal direction and has a parallel movement link 156 connected to each side end of the pressing member 102. Therefore, the pressing movement section 148 can move the pressing member 102 while maintaining the posture of the pressing member 102 when the pressing member 102 presses the paper S. As a result, the catching force of the pressing member 102 on the paper S when the pressing member 102 presses the paper S can be suppressed more effectively.
[0103] Therefore, according to the image forming system 10 (image forming apparatus 12) of this embodiment, the accuracy of detecting the stiffness of the paper by the stiffness measuring unit 146 can be further improved.
[0104] Although this embodiment has been described in detail above, the present invention is not limited to the specific embodiments described above. Various modifications and changes are possible to the specific examples described in the above embodiments within the scope of the gist of the present invention as described in the claims. [Industrial applicability]
[0105] This invention is useful as an image forming apparatus that can further improve the accuracy of detecting the stiffness of a recording medium. [Explanation of Symbols]
[0106] 10 Image Forming Systems 12 Image forming apparatus 14 Paper feed device 16. Paper transport device (media transport device) 18 Post-processing equipment 20. Main unit of the device (main unit of the device for the image forming apparatus) 22 Image forming unit 24 Image forming unit 24Y Image Forming Unit 24M Image Forming Unit 24C Image Forming Unit 24K Image Forming Unit 26 Photoconductor drum 28. Developing Department 30 Transfer section 32 Intermediate transfer belt 34 Secondary transfer roller 36 Fixing section 38 Heating rollers 40 Fixing roller 42 Fixing belt 44 Pressure rollers 46 Main transport path 48 Conveyor Roller Pair 48R Resist Roller vs 50 Reversal transport path 52 Conveyor Roller Pair 54. Main unit of the device (main unit of the paper feed device) 56 Paper feed tray 58 Paper feed transport path 60 Conveyor Rollers 62. Main unit of the device (main unit of the paper transport device) 64 Main transport path 66 Conveyor Roller Pair 68. Stiffness Measurement Unit 70 Paper output tray 72 Vertical transport path 74 Conveyor Roller Pair 74G Retaining roller pair (retaining part) 76 Route switching section 78. Paper sensor (paper detection unit) 80. Main unit of the device (main unit of the device for the post-processing device) 82 Post-processing 84 Paper Output Tray 86 Paper Output Tray 88 Paper output transport path 90 Conveyor Rollers 92 Paper output path 94 Conveyor Roller Pair 96 Support frame (fixing part) 98 Drive Roller 100 Driven Rollers 102 Pressing member 104 Stiffness sensor (stiffness detection unit) 106 Pressing and moving part 108 Pivoting axis 110 Arm section 112 Cam mechanism 114 Contact piece 116 Camshaft 118 Cam plate 120 Spring 122 RPM motor 124 Stiffness Measurement Unit 126 Pressing and moving part 128 Guide member 128c First guide groove 128g, 2nd guide groove 130 First slider 132 Second Slider 134 Cam mechanism 136 Contact plate 138 Camshaft 140 cam plate 142 Springs 144 RPM motor 146 Stiffness Measurement Unit 148 Pressing and moving part 150 Parallel Link Mechanism 152 Pivot axis 154 Oscillating Link 156 Translation Link 158 RPM motor 160 Control Unit 162 CPU 164 ROM 166 RAM 168 Storage section 170 Communications Department CN primary transfer nip TN secondary transfer nip FN Fixing Nips S paper
Claims
1. A holding unit that holds the recording medium in transit in the vertical direction, A pressing member that presses the paper below the holding position of the holding part, A stiffness detection unit detects the reaction force from the recording medium being bent by the pressing member as the stiffness of the recording medium, The pressing member is further equipped with a pressing movement unit that moves the pressing member in order to suppress displacement of the tip of the pressing member relative to the recording medium when the pressing member presses the recording medium. Image forming apparatus.
2. The pressing movement unit moves the pressing member such that the tip of the pressing member traces an arc when the pressing member presses the recording medium. The image forming apparatus according to claim 1.
3. The center of the arc is the holding position of the holding part. The image forming apparatus according to claim 2.
4. The pressing and moving part has an arm portion that is pivotable around a horizontal pivot axis passing through the holding position of the holding part or its vicinity and is connected to the pressing member. The image forming apparatus according to claim 1.
5. The distance from the pivot axis of the arm portion to the tip of the pressing member is the same as the distance from the holding position of the holding portion to the pressing position of the pressing member. The image forming apparatus according to claim 4.
6. The pressing and moving part further includes a cam mechanism for swinging the arm part around the pivot axis. The image forming apparatus according to claim 4.
7. The pressing movement unit moves the pressing member while maintaining the posture of the pressing member when the pressing member presses the recording medium. The image forming apparatus according to claim 1.
8. The pressing movement unit moves the pressing member such that the tip of the pressing member traces an arc when the pressing member presses the recording medium. The image forming apparatus according to claim 7.
9. The pressing and moving part is provided on the fixed part and has guide members that guide each side end of the pressing member so as to maintain the posture of the pressing member. The image forming apparatus according to claim 7.
10. The pressing and moving section has a cam mechanism for moving the pressing member while each side end of the pressing member is guided by the respective guide members. An image forming apparatus according to claim 9.
11. The pressing and moving parts are arranged on both ends of the holding part and have parallel link mechanisms for moving the pressing member in a parallel horizontal direction. Each parallel link mechanism has a parallel movement link that is movable horizontally and connected to the pressing member. The image forming apparatus according to claim 7.
12. The pressing member is positioned between a pair of parallel link mechanisms. The image forming apparatus according to claim 11.
13. The cross-sectional shape of the tip of the pressing member along the vertical direction is curved. The image forming apparatus according to claim 1.