Stiffness measuring device and image forming system

Abstract

To further improve the accuracy of detecting the stiffness of recording materials. [Solution] The stiffness measuring device comprises: a holding unit that holds a recording material in transit in the vertical direction; a pressing unit that presses a portion of the recording material held by the holding unit that is located below the holding position of the holding unit; a stiffness detection unit that detects the reaction force from the recording material pressed by the pressing unit as the stiffness of the recording material; a pressing movement unit that moves the pressing unit in the direction of pressing the recording material; and a pressing control unit that controls the pressing movement unit to perform multiple pressing operations of the pressing unit on the recording material.

Description

Technical Field

[0001] The present invention relates to a stiffness measurement device and an image forming system.

Background Art

[0002] In image forming systems, a technique is known in which the stiffness of a recording material such as paper is detected, and various control parameters related to image formation are set based on the detection result. Various developments have also been made on stiffness measurement devices for measuring the stiffness of recording materials, and the applicant of the present application has also filed an application for a stiffness measurement device, the content of which has already been published (see Patent Document 1). The configuration of the stiffness measurement device according to the related art will be briefly described as follows.

[0003] A stiffness measurement device according to the related art includes a holding unit that holds a recording material being conveyed in the vertical direction, and a pressing unit that presses the recording material held by the holding unit below the holding position of the holding unit. Further, the stiffness measurement device according to the related art includes a stiffness detection unit (referred to as a pressing force detection unit in Patent Document 1) that detects, as the stiffness of the recording material, a reaction force from the recording material that is pressed and bent by the pressing unit. Further, the stiffness measurement device according to the related art includes a pressing movement unit (referred to as a movement mechanism in Patent Document 1) that moves the pressing unit in the direction of pressing the recording material.

[0004] According to the configuration of the stiffness measurement device of the related art, in a state where the recording material being conveyed in the vertical direction is held by the holding unit, the pressing unit presses the recording material below the holding position of the holding unit. At this time, the stiffness detection unit detects, as the stiffness of the recording material, a reaction force from the recording material that is pressed and bent by the pressing unit. Thereby, the stiffness of the recording material can be detected in a state where the influence of gravity acting on the recording material is suppressed, and the detection accuracy of the stiffness of the recording material can be improved.

Related Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Incidentally, when a stiffness measuring device is used in a low-humidity environment, the recording material, such as paper, is more likely to become electrically charged due to its transport, and this charge can cause the recording material to stick to the holding part or its surroundings. In such cases, the reaction force from the recording material being bent by the pressing part is joined as a disturbance by a peeling force that separates the recording material from the holding part or its surroundings. In particular, when detecting the stiffness of a recording material with low rigidity, such as thin paper, the addition of this peeling force to the reaction force from the recording material being bent by the pressing part becomes significant. Therefore, further improvements are desired in stiffness measuring devices of prior art in order to further improve the accuracy of detecting the stiffness of the recording material.

[0007] Therefore, the present invention aims to provide a stiffness measuring device and an image forming system that can further improve the accuracy of detecting the stiffness of a recording material. [Means for solving the problem]

[0008] One aspect of the stiffness measuring device of the present invention is A holding section that holds the recording material in transit in the vertical direction, A pressing section that presses the recording material held by the holding section below the holding position of the holding section, A stiffness detection unit detects the reaction force from the recording material being bent by the pressing unit as the stiffness of the recording material, A pressing movement unit that moves the pressing unit in the direction of pressing the recording material, The system includes a pressing control unit that controls the pressing movement unit to perform multiple pressing operations on the recording material.

[0009] One aspect of the image forming system of the present invention is An image forming unit that forms an image on the recording material while it is being transported, A recording material storage section for storing recording material, The system includes the stiffness measuring device provided between the image forming section and the recording material storage section. [Effects of the Invention]

[0010] According to the present invention, the accuracy of detecting the stiffness of the recording material can be further improved. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic front view of the image forming system according to this embodiment. [Figure 2] Figure 2 is a schematic front view of the stiffness measuring device according to this embodiment, showing the paper attached to the guide. [Figure 3] Figure 3 is a schematic diagram showing how paper is held by a pair of holding rollers while being transported vertically. [Figure 4] Figure 4 is a schematic diagram illustrating the previous pressing operation of the pressing part in the first embodiment of the stiffness measuring device according to this embodiment. [Figure 5] Figure 5 is a schematic diagram illustrating the next pressing operation of the pressing part in the first embodiment of the stiffness measuring device according to this embodiment. [Figure 6] Figure 6 is a schematic diagram illustrating the previous pressing operation of the pressing part in the second embodiment of the stiffness measuring device according to this embodiment. [Figure 7] Figure 7 is a schematic diagram illustrating the next pressing operation of the pressing part in the second embodiment of the stiffness measuring device according to this embodiment. [Figure 8] Figure 8 is a control block diagram of the image forming system according to this embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, the present 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 material such as a sheet of paper, and the downstream side refers to the downstream side in the conveyance direction of a recording material such as a sheet of paper. The vertical direction is not strictly limited to the exact vertical direction, and is intended to include directions inclined within a range of ±30 degrees relative 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, "upper" indicates the upward direction, and "lower" indicates the downward direction, respectively.

[0013] An overview of the image forming system 10 according to the present embodiment will be described with reference to Figure 1. Figure 1 is a schematic front view showing the image forming system 10 according to the present embodiment.

[0014] As shown in Figure 1, the image forming system 10 according to the present embodiment is a system that measures the rigidity of a sheet-shaped paper S, which is an example of a recording material, and forms an image on the paper S. 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 paper S by an electrophotographic method. The image forming system 10 includes a paper feeding device 14 disposed on the upstream side of the image forming apparatus 12, and the paper feeding device 14 is a device that feeds the paper S toward the image forming apparatus 12 side.

[0015] The image forming system 10 includes a paper conveying device (recording material conveying device) 16 disposed between the image forming apparatus 12 and the paper feeding device 14, and the paper conveying device 16 is a device that conveys the paper S fed from the paper feeding device 14 to the image forming apparatus 12. The image forming system 10 may include a post-processing device (not shown) disposed on the downstream side of the image forming apparatus 12, and the post-processing device is a device that performs post-processing such as stapling, cutting, and punching on the paper S on which an image has been formed.

[0016] Next, the configuration of the image forming apparatus 12 will be described with reference to Figure 1.

[0017] As shown in Figure 1, the image forming apparatus 12 includes a box-shaped apparatus main body (an apparatus main body for an image forming apparatus) 18, and the apparatus main body 18 constitutes a base frame of the image forming apparatus 12. Further, an image forming unit 20 that forms an image on a sheet of paper S by an electrophotographic method is provided at an upper portion inside the apparatus main body 18. The image forming unit 20 has four image forming units 22Y, 22M, 22C, and 22K for forming images with respective colored toners of a Y (yellow) component, an M (magenta) component, a C (cyan) component, and a K (black) component based on image data. The four image forming units 22Y, 22M, 22C, and 22K are arranged along the vertical direction.

[0018] The image forming units 22Y, 22M, 22C, and 22K for the Y component, M component, C component, and K component have the same configuration. For convenience of illustration and description, common constituent elements are denoted by the same reference numerals, and when distinguishing between them, the reference numerals are suffixed with Y, M, C, or K. In Figure 1, reference numerals are assigned only to the constituent elements of the image forming unit 22Y for the Y component, and reference numerals for the constituent elements of the other image forming units 22M, 22C, and 22K are omitted.

[0019] The image forming unit 22 includes a photosensitive drum 24, a charging section (not shown), an exposure section (not shown), and a developing section 26.

[0020] The photosensitive drum 24 is, for example, a negatively charged organic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on the peripheral surface of a conductive cylindrical body made of aluminum. The photosensitive drum 24 rotates at a constant peripheral speed by driving of a rotation motor (not shown). The charging section uniformly charges the outer peripheral surface of the photosensitive drum 24 to a negative polarity. The exposure section emits laser light as scanning light to perform scanning while exposing the outer peripheral surface of the photosensitive drum 24, thereby forming an electrostatic latent image on the outer peripheral surface of the photosensitive drum 24. The developing section 26 visualizes the electrostatic latent image on the outer peripheral surface of the photosensitive drum 24 to form a toner image by causing toner of each color component to adhere to the outer peripheral surface of the photosensitive drum 24.

[0021] As shown in Figure 1, a transfer unit 28 for transferring a toner image onto paper S is provided in the upper part of the main body 18 of the device. The transfer unit 28 has an endless intermediate transfer belt 30 and a secondary transfer roller 32.

[0022] The intermediate transfer belt 30 extends vertically so as to face the multiple photoreceptor drums 24 and is stretched over multiple support rollers (not shown). The intermediate transfer belt 30 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 30 and the outer surface of each photoreceptor drum 24 for transferring the toner image from each photoreceptor drum 24 to the intermediate transfer belt 30.

[0023] The secondary transfer roller 32 is positioned on the outer circumferential side of the intermediate transfer belt 30. The secondary transfer roller 32 rotates in cooperation with the intermediate transfer belt 30 while holding the paper S. A secondary transfer nip TN is formed between the outer circumferential surface of the secondary transfer roller 32 and the outer circumferential surface of the intermediate transfer belt 30 for transferring the toner image from the intermediate transfer belt 30 to the paper S.

[0024] As the intermediate transfer belt 30 passes through the primary transfer nip CN, the toner image on the photoreceptor drum 24 is sequentially transferred onto the intermediate transfer belt 30 as a primary transfer. Subsequently, as the paper S passes through the secondary transfer nip TN, the toner image on the intermediate transfer belt 30 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 34 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 18 of the apparatus. The fixing unit 34 has a heating roller 36, a fixing roller 38, an endless fixing belt 40, and a pressure roller 42.

[0026] The heating roller 36 has a hollow cylindrical core and a heating device (not shown), such as a halogen lamp, provided inside the core. The fixing roller 38 is positioned opposite the heating roller 36. The fixing roller 38 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 40 is stretched between the heating roller 36 and the fixing roller 38. The fixing belt 40 rotates as the heating roller 36 and the fixing roller 38 rotate.

[0027] The pressure roller 42 is located on the outside of the fixing belt 40, facing the fixing roller 38, and presses toward the fixing roller 38 with a predetermined fixing load. The pressure roller 42 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 38 and the pressure roller 42 for transporting the paper S while heating and pressurizing it.

[0028] As the pressure roller 42 rotates due to the drive of the rotary motor, the fixing belt 40 follows and rotates. As the fixing belt 40 rotates, the heating roller 36 and the fixing roller 38 follow and rotate. This allows the paper S to be transported while being heated and pressurized at the fixing nip FN, thereby fixing the toner image to the paper S.

[0029] As shown in Figure 1, the main transport path 44 is provided inside the main body 18 of the device for transporting the paper S fed from the paper transport device 16 in the transport direction via the secondary transfer nip TN and the fixing nip FN. The main transport path 44 has a plurality of transport roller pairs 46, including a registration roller pair 46R, and the plurality of transport roller pairs 46 are rotated by the drive of a transport motor (not shown).

[0030] Below the main transport path 44 within the device body 18, a reversal transport path 48 is provided for reversing the front and back sides of the paper S. The reversal transport path 48 is a transport path that transports the paper S when forming a toner image on the back side of the paper S. The inlet end of the reversal transport path 48 is connected to the downstream side of the fuser nip FN in the main transport path 44. The outlet end of the reversal transport path 48 is connected to the upstream side of the register roller pair 46R in the main transport path 44. The reversal transport path 48 has a plurality of transport roller pairs 50, 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 44 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 46R, 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 30 is transferred all at once to one side (front or back) of the paper S, and at the fixing nip FN, the toner image is fixed to the paper S. After that, the paper S with the formed image is discharged to the outside of the device body 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 also includes a box-shaped device body (device body for the paper feeder) 52 installed to the left of the main body 18 for the image forming apparatus, and the device body 52 constitutes the base frame of the paper feeder 14.

[0034] The main body 52 of the device is provided with multiple paper feed trays 54, which serve as recording material storage sections for accommodating multiple sheets of paper S. The multiple paper feed trays 54 are arranged in a stepped manner along the vertical direction. Each paper feed tray 54 accommodates a type of paper S that is pre-set according to basis weight, size, etc. The main body 52 of the device is also provided with a paper feed transport path 56 for feeding paper from each paper feed tray 54 to the paper transport device 16. The paper feed transport path 56 has multiple transport roller pairs 58, which are rotated by the drive of a transport motor (not shown).

[0035] Next, the configuration of the paper transport device (recording material transport device) 16 will be described with reference to Figures 1 and 2. Figure 2 is a schematic front view of the stiffness measuring device 66 according to this embodiment, showing the paper S attached to the guide 88.

[0036] As shown in Figure 1, the paper transport device 16 is a device that transports the paper S fed from the paper feed device 14 to the image forming apparatus 12, as described above. The paper transport device 16 also includes a box-shaped device body (device body for the paper transport device) 60 installed between the device body 18 for the image forming apparatus and the device body 52 for the paper feed device, and the device body 60 constitutes the base frame of the paper transport device 16.

[0037] The main body 60 of the device is provided with a main transport path 62 for transporting paper S fed from the paper feeder 14 to the image forming apparatus 12. The main transport path 62 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 62 is connected to the outlet end of the paper feed transport path 56 of the paper feeder 14. The outlet end of the main transport path 62 is connected to the inlet end of the main transport path 44 of the image forming apparatus 12. The main transport path 62 has a plurality of transport roller pairs 64, and the plurality of transport roller pairs 64 are rotated by the drive of a transport motor (not shown).

[0038] A stiffness measuring device 66 for measuring the stiffness of the paper S is provided above the main transport path 62 within the main body 60 of the device. In other words, the stiffness measuring device 66 is provided between the image forming unit 20 and the paper feed tray 54. Furthermore, a paper output tray 68 for discharging the paper S after its stiffness has been measured is provided at the top of the main body 60 of the device. Details of the stiffness measuring device 66 will be described later.

[0039] The main body 60 of the device is provided with a vertical transport path 70 for transporting paper S, which has been fed from the middle of the main transport path 62, to the output tray 68 via a stiffness measuring device 66. The vertical transport path 70 extends vertically from the main transport path 62 side to the output tray 68 side. The inlet end of the vertical transport path 70 can be connected to the middle of the main transport path 62, and the outlet end of the vertical transport path 70 is connected to the inlet side of the output tray 68.

[0040] The vertical transport path 70 has multiple transport roller pairs 72, which are rotated by the drive of a transport motor (not shown). The multiple transport roller pairs 72 include a holding roller pair 72G which constitutes a holding part of the stiffness measuring device 66. In addition, a path switching unit 74 (see Figure 8) is provided at an appropriate position within the device body 60 to switch the transport path of the paper S from the main transport path 62 to the vertical transport path 70.

[0041] As shown in Figures 1 and 2, a paper sensor 76 is provided below the holding roller pair 72G within the main body 60 of the device, serving as a paper detection unit for detecting the paper S. The paper sensor 76 consists of, for example, a reflective or transmissive photosensor, and detects the trailing end of the paper S in the transport direction as it is being transported vertically by changes in the received light intensity. In addition, a humidity sensor 78 is provided at an appropriate position within the main body 60 of the device, serving as a humidity detection unit for detecting the humidity of the operating environment of the stiffness measuring device 66.

[0042] As shown in Figure 1, an ionizer 80 is provided inside the main body 60 of the device as a static elimination unit that removes static electricity from the paper S being transported between the inlet end and the middle section of the main transport path 62, and the ionizer 80 extends in the front-rear direction. The ionizer 80 has a known configuration as shown in, for example, Japanese Patent Application Publication No. 2024-54937.

[0043] Next, with reference to Figures 2 to 7, the specific configuration of the stiffness measuring device 66 according to this embodiment will be described. Figure 3 is a schematic diagram showing how a sheet of paper S being transported in the vertical direction is held by the holding roller pair 72G. Figure 4 is a schematic diagram illustrating the previous pressing operation of the pressing unit 94 in the first embodiment of the stiffness measuring device 66 according to this embodiment. Figure 5 is a schematic diagram illustrating the next pressing operation of the pressing unit 94 in the first embodiment of the stiffness measuring device 66 according to this embodiment. Figure 6 is a schematic diagram illustrating the previous pressing operation of the pressing unit 94 in the second embodiment of the stiffness measuring device 66 according to this embodiment. Figure 7 is a schematic diagram illustrating the next pressing operation of the pressing unit 94 in the second embodiment of the stiffness measuring device 66 according to this embodiment.

[0044] As shown in Figures 2 and 3, the stiffness measuring device 66 is equipped with a pair of holding rollers 72G as a holding part that grips and holds the paper S being transported vertically from the horizontal left and right directions. The pair of holding rollers 72G is provided on a support frame 82 fixed inside the device body 60 and extends in the horizontal front-rear direction. The pair of holding rollers 72G has a drive roller 84 that is rotatably mounted on the support frame 82 and rotates by the drive of a transport motor (not shown). The drive roller 84 is configured to stop rotating when the transport motor stops when the paper sensor 76 detects the rear end of the paper S being transported vertically.

[0045] The holding roller pair 72G is rotatably mounted on the support frame 82 and has a driven roller 86 that rotates in conjunction with the rotation of the drive roller 84. The driven roller 86 works in cooperation with the drive roller 84 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 82 to bias the driven roller 86 toward the drive roller 84. The holding position of the holding roller pair 72G is the position in which the paper S is held by the holding roller pair 72G, and in this embodiment, it is the nip position in which the paper S is gripped by the cooperation of the drive roller 84 and the driven roller 86.

[0046] Near the lower side of the holding roller pair 72G in the support frame 82, a guide guide 88 is provided to guide the paper S to the holding position of the holding roller pair 72G, and the guide guide 88 extends in the front-rear direction. The stiffness measuring device 66 may omit the guide guide 88 from its components.

[0047] As shown in Figures 2 and 3, below the retaining roller pair 72G in the support frame, there is a pair of guide bars 90 (only one guide bar 90 is shown) extending horizontally in the left-right direction, and the pair of guide bars 90 are spaced apart in the front-rear direction. Movable bodies 92 are provided on the pair of guide bars 90 so as to be movable in the left-right direction.

[0048] As shown in Figures 2 to 5, the movable body 92 is provided with a pressing section 94 via a stiffness sensor 96, which acts as a stiffness detection section, to press the paper S held by the holding roller pair 72G in a leftward direction. The pressing section 94 presses the paper S in a leftward direction below the holding position of the holding roller pair 72G. The pressing section 94 bends the paper S held by the holding roller pair 72G in a leftward direction. The pressing section 94 extends in the front-rear direction and moves left-right integrally with the movable body 92. The pressing section 94 is electrically grounded, and the cross-sectional shape of the tip of the pressing section 94 along the vertical direction is formed in a curved shape (R shape).

[0049] The stiffness sensor 96, acting as a stiffness detection unit, detects the reaction force from the paper S, which is bent by the pressing unit 94, as the stiffness of the paper S. The stiffness sensor 96 is connected to the longitudinal center of the pressing unit 94 and moves integrally with the pressing unit 94 in the left-right direction. For example, a load cell can be used as the stiffness sensor 96.

[0050] As shown in Figures 2 to 5, a pressing movement unit 98 is provided at an appropriate position on the support frame to move the pressing unit 94 integrally with the movable body 92, etc., in the leftward direction, which is the direction in which the paper S is pressed. The pressing movement unit 98 has a moving motor 100 as a moving actuator that moves the movable body 92 in the left-right direction. The pressing movement unit 98 has a worm gear (not shown) and a rack and pinion mechanism (not shown) that interlock the output shaft (not shown) of the moving motor 100 with the movable body 92. Note that the mechanism that interlocks the output shaft of the moving motor 100 with the movable body 92 is not limited to a worm gear and a rack and pinion mechanism.

[0051] The pressing movement unit 98 is configured to perform multiple pressing operations of the pressing unit 94 on the paper S. In this embodiment, the number of pressing operations of the pressing unit 94 is, for example, two or three times.

[0052] As shown in Figures 4 and 5, in the first embodiment of the stiffness measuring device 66, the pressing movement unit 98 is configured to perform multiple pressing operations of the pressing unit 94 while changing the speed and amount of movement of the pressing unit 94 in each pressing operation. The pressing movement unit 98 is configured such that the speed Va of the previous pressing operation of the pressing unit 94 is faster than the speed Vb of the next pressing operation of the pressing unit 94. The pressing movement unit 98 is configured such that the amount of movement Da of the previous pressing operation of the pressing unit 94 is greater than the amount of movement Db of the next pressing operation of the pressing unit 94.

[0053] Here, the amount of movement of the pressing action of the pressing part 94 refers to the amount of movement in the leftward direction, which is the pressing direction, with respect to a virtual vertical line (vertical plane) VL passing through the holding position of the holding roller pair 72G. The previous pressing action of the pressing part 94 refers to the pressing action of the pressing part 94 other than the last of multiple pressing actions of the pressing part 94. For example, if the pressing action of the pressing part 94 is performed twice, the first pressing action of the pressing part 94 is the previous pressing action of the pressing part 94. If the pressing action of the pressing part 94 is performed three times, the first pressing action of the pressing part 94 and the second pressing action of the pressing part 94 are the previous pressing actions of the pressing part 94, respectively.

[0054] The next pressing action of the pressing unit 94 refers to the last pressing action of the pressing unit 94 out of multiple pressing actions of the pressing unit 94. For example, if the pressing unit 94 has been pressed twice, the second pressing action of the pressing unit 94 will be the next pressing action of the pressing unit 94. If the pressing unit 94 has been pressed three times, the third pressing action of the pressing unit 94 will be the next pressing action of the pressing unit 94.

[0055] As shown in Figures 6 and 7, in the second embodiment of the stiffness measuring device 66, the pressing movement unit 98 is configured to perform multiple pressing operations of the pressing unit 94 while maintaining a constant speed and movement amount for each pressing operation of the pressing unit 94. The speed of each pressing operation of the pressing unit 94 is the same as the speed Vb of the next pressing operation of the pressing unit 94 in the first embodiment of the stiffness measuring device 66, but may be a different speed. The movement amount of each pressing operation of the pressing unit 94 is the same as the movement amount Da of the next pressing operation of the pressing unit 94 in the first embodiment of the stiffness measuring device 66, but may be a different movement amount.

[0056] As shown in Figures 2 and 3, below the holding roller pair 72G in the support frame, a transport guide 102 is provided to guide the paper S in the transport direction (vertical direction), and the transport guide 102 constitutes part of the vertical transport path 70. The transport guide 102 is positioned to the right of a virtual vertical line VL, which is the opposite direction to the direction in which the paper S is pressed.

[0057] According to the configuration of the stiffness measuring device 66, when the paper sensor 76 detects the rear end of the paper S in the transport direction while it is being transported vertically, the drive of the transport motor stops, and the rotation of the drive roller 84 and the driven roller 86 stops. As a result, as shown in Figure 3, the paper S being transported vertically is held by the holding roller pair 72G from the left and right directions.

[0058] Then, as shown in Figures 4 to 7, the pressing movement unit 98 performs multiple pressing operations of the pressing unit 94. As a result, as shown in Figures 4 and 6, even if the paper S is stuck to the guide 88 etc. due to its charged surface, the previous pressing operation of the pressing unit 94 bends the paper S, allowing it to be detached from the guide 88 etc. Furthermore, as shown in Figures 5 and 7, when the paper S is no longer stuck to the guide 88 etc., the next pressing operation of the pressing unit 94 bends the paper S, and the stiffness sensor 96 detects the reaction force from the paper S as the stiffness of the paper S. In other words, the stiffness sensor 96 detects the stiffness of the paper S with the influence of the peeling force that detaches the paper S from the guide 88 etc. removed.

[0059] After detecting the stiffness of the paper S, the drive motor rotates the drive roller 84 and the driven roller 86, thereby transporting the paper S, whose stiffness has been measured, vertically along the vertical transport path 70.

[0060] The control configuration of the image forming system 10 according to this embodiment will be described with reference to Figures 1 to 8. Figure 8 is a control block diagram of the image forming system 10 according to this embodiment.

[0061] As shown in Figures 1 and 8, the image forming system 10 includes a control unit 104 that controls the paper feeder 14, image forming unit 20, transfer unit 28, fixing unit 34, path switching unit 74, ionizer 80, and press movement unit 98, etc. The control unit 104 is responsible for controlling the entire image forming system 10. Alternatively, the stiffness measuring device 66 in the image forming system 10 can be considered as having a control unit 104 that controls the press movement unit 98, etc. The control unit 104 includes a CPU (Central Processing Unit) 106, a ROM (Read Only Memory) 108, and a RAM (Random Access Memory) 110. The control unit 104 is connected to a storage unit 112, a communication unit 114, a paper sensor 76, etc.

[0062] The CPU 106 provides overall control over the operation of the image forming system 10. The CPU 106 reads various control programs and setting data stored in the ROM 108, stores them in the RAM 110, and executes the programs to perform various calculations. The RAM 110 provides the CPU 106 with a working memory space and stores temporary data. The CPU 106 also refers to various data stored in the storage unit 112 when performing various calculations. The storage unit 112 is composed of, for example, a non-volatile semiconductor memory or a hard disk drive.

[0063] The control unit 104 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 114. The control unit 104 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 114 is composed of, for example, a communication control card such as a LAN card.

[0064] As shown in Figures 1 and 8, when the control unit 104 receives an instruction to measure the stiffness of the paper S, it controls the path switching unit 74 to switch the transport path of the paper S from the main transport path 62 to the vertical transport path 70. By switching the transport path of the paper S from the main transport path 62 to the vertical transport path 70, the control unit 104 can send the paper S from the main transport path 62 to the vertical transport path 70 and transport it vertically by the vertical transport path 70.

[0065] As shown in Figures 3 and 8, when the paper sensor 76 detects the rear end of the paper S in the transport direction while it is being transported vertically, the control unit 104 stops the drive of the transport motor (not shown) and stops the rotation of the drive roller 84. By stopping the rotation of the drive roller 84, the control unit 104 can hold the paper S in the transport direction by gripping it from the left and right directions.

[0066] As shown in Figure 8, the control unit 104 (CPU 106) functions as an environment determination unit, a pressure control unit, a stiffness acquisition unit, a characteristic determination unit, and a parameter setting unit by executing various control programs. The specific details of each function of the control unit 104 are as follows.

[0067] As shown in Figures 1, 2, and 8, the control unit 104, acting as an environmental determination unit, determines whether the environment in which the stiffness measuring device 66 is used is a low-humidity environment based on the humidity of the environment in which the stiffness measuring device 66 is used, as detected by the humidity sensor 78. A low-humidity environment is an environment in which the humidity is high and the paper S is prone to becoming charged.

[0068] The control unit 104 determines whether the humidity of the environment in which the stiffness measuring device 66 is used is above the standard low humidity. If the humidity of the environment in which the stiffness measuring device 66 is used is above the standard low humidity, the control unit 104 determines that the environment in which the stiffness measuring device 66 is used is a low humidity environment. If the humidity of the environment in which the stiffness measuring device 66 is used is not below the standard low humidity, the control unit 104 determines that the environment in which the stiffness measuring device 66 is used is not a low humidity environment. The standard low humidity is the humidity used as a reference for determining whether the environment in which the stiffness measuring device 66 is used is a low humidity environment.

[0069] As shown in Figures 4 to 8, the control unit 104, acting as a pressing control unit, controls the moving motor 100 to perform multiple pressing operations of the pressing unit 94 on the paper S. The control unit 104 controls the moving motor 100 to perform multiple pressing operations of the pressing unit 94 on the paper S after a predetermined time has elapsed since the paper sensor 76 detected the rear end of the paper S in the transport direction while it was being transported vertically. The control unit 104 may also control the moving motor 100 to perform multiple pressing operations of the pressing unit 94 on the paper S, provided that it has determined that the operating environment of the stiffness measuring device 66 is a low-humidity environment.

[0070] Furthermore, the control unit 104 may control the moving motor 100 to perform a single pressing operation of the pressing unit 94 on the paper S, provided that it determines that the operating environment of the stiffness measuring device 66 is not a low-humidity environment.

[0071] As shown in Figures 4, 5, and 8, in the first embodiment of the stiffness measuring device 66, the control unit 104 controls the moving motor 100 to perform multiple pressing operations of the pressing unit 94 while changing the speed and amount of movement in each pressing operation of the pressing unit 94. The control unit 104 controls the moving motor 100 so that the speed Va of the previous pressing operation of the pressing unit 94 is faster than the speed Vb of the next pressing operation of the pressing unit 94. The control unit 104 controls the moving motor 100 so that the amount of movement Da of the previous pressing operation of the pressing unit 94 is greater than the amount of movement Db of the next pressing operation of the pressing unit 94.

[0072] The control unit 104 may also control the moving motor 100 to change either the speed or the amount of movement during the pressing operation of the pressing unit 94 each time.

[0073] In the first embodiment of the stiffness measuring device 66, the control unit 104, acting as a stiffness acquisition unit, acquires the stiffness of the paper S detected by the stiffness sensor 96 during the next pressing operation of the pressing unit 94. In other words, the control unit 104 acquires the stiffness of the paper S from the stiffness sensor 96 during the next pressing operation of the pressing unit 94.

[0074] As shown in Figures 6 to 8, in a second embodiment of the stiffness measuring device 66, the control unit 104 controls the moving motor 100 to perform multiple pressing operations of the pressing unit 94 while keeping the speed and amount of movement of the pressing unit 94 constant for each pressing operation.

[0075] In a second embodiment of the stiffness measuring device 66, the control unit 104, acting as a stiffness acquisition unit, acquires the stiffness of the paper S detected by the stiffness sensor 96 during each pressing operation of the pressing unit 94. In other words, the control unit 104 acquires the stiffness of the paper S from the stiffness sensor 96 during each pressing operation of the pressing unit 94.

[0076] In a second embodiment of the stiffness measuring device 66, the control unit 104, acting as a characteristic determination unit, determines whether or not the paper S has a characteristic of being prone to static electricity. The control unit 104 determines whether or not the paper S has a characteristic of being prone to static electricity based on the difference between the stiffness of the paper S obtained from the stiffness sensor 96 during the previous pressing operation of the pressing unit 94 and the stiffness of the paper S obtained from the stiffness sensor 96 during the next pressing operation of the pressing unit 94. In other words, a characteristic of being prone to static electricity is a characteristic of being prone to sticking to the drive roller 84 or its surroundings due to static electricity.

[0077] The control unit 104 determines that the paper S has predetermined adhesive characteristics if the difference between the stiffness of the paper S obtained during the previous pressing operation of the pressing unit 94 and the stiffness of the paper S obtained during the next pressing operation is outside the range of acceptable measurement error. The control unit 104 determines that the paper S does not have predetermined adhesive characteristics if the difference between the stiffness of the paper S obtained during the previous pressing operation of the pressing unit 94 and the stiffness of the paper S obtained during the next pressing operation is within the range of acceptable measurement error.

[0078] The control unit 104, acting as a parameter setting unit, sets control parameters related to image formation in the image forming unit 20 based on the stiffness of the paper S obtained from the stiffness sensor 96 during the next pressing operation of the pressing unit 94. Examples of control parameters include the charging potential of the charging unit, the transfer current to the secondary transfer roller 32, the fixing current of the fixing unit 34, and the fixing temperature of the fixing unit 34.

[0079] According to the configuration of the stiffness measuring device 66 in this embodiment, as described above, while the paper S being transported in the vertical direction is held by the holding roller pair 72G, the pressing unit 94 presses the paper S below the holding position of the holding roller pair 72G. At this time, the stiffness sensor 96 detects the reaction force from the paper S being bent by the pressing unit 94 as the stiffness of the paper S. This allows the stiffness sensor 96 to detect the stiffness of the paper S while suppressing the influence of gravity acting on the paper S.

[0080] Furthermore, according to the configuration of the stiffness measuring device 66 in this embodiment, as described above, the control unit 104 controls the moving motor 100 to perform multiple pressing operations of the pressing unit 94 on the paper S. Therefore, even if the paper S is stuck to the guide 88, etc. due to an accumulated charge, the previous pressing operation of the pressing unit 94 bends the paper S, allowing it to be detached from the guide 88, etc. Then, with the paper S no longer stuck to the guide 88, etc., the next pressing operation of the pressing unit 94 bends the paper S, and the stiffness sensor 96 can detect the reaction force from the paper S as the stiffness of the paper S. In other words, the stiffness sensor 96 can detect the stiffness of the paper S while removing the influence of the peeling force that detaches the paper S from the guide 88, etc.

[0081] Therefore, according to the stiffness measuring device 66 of this embodiment, the accuracy of detecting the stiffness of the paper S can be further improved.

[0082] Furthermore, according to the configuration of the stiffness measuring device 66 in this embodiment, the control unit 104 controls the moving motor 100 to perform multiple pressing operations of the pressing unit 94 on the paper S, provided that it has determined that the operating environment of the stiffness measuring device 66 is a low-humidity environment. Therefore, if the operating environment of the stiffness measuring device 66 is not a low-humidity environment, instead of multiple pressing operations of the pressing unit 94 on the paper S, only one pressing operation of the pressing unit 94 will be performed.

[0083] Therefore, according to the stiffness measuring device 66 of this embodiment, it is possible to prevent the time required for detecting (measuring) the stiffness of the paper S from becoming unnecessarily long.

[0084] Furthermore, according to the configuration of the stiffness measuring device 66 in this embodiment, as described above, the pressing portion 94 is electrically grounded. Therefore, it is possible to suppress the paper S from sticking to the pressing portion 94 due to the accumulated charge.

[0085] Therefore, the stiffness measuring device 66 according to this embodiment can further improve the accuracy of detecting the stiffness of the paper S.

[0086] Furthermore, according to the configuration of the first embodiment of the stiffness measuring device 66, as described above, the control unit 104 controls the moving motor 100 so that the speed Va of the previous pressing operation of the pressing unit 94 is faster than the speed Vb of the next pressing operation of the pressing unit 94. Therefore, if the paper S is stuck to the guide 88 or the like due to an accumulated charge, the peeling process to peel the paper S from the guide 88 or the like can be performed in a short time.

[0087] Therefore, according to the stiffness measuring device 66 of this embodiment, the stiffness detection process (measurement process) of the paper S can be performed efficiently.

[0088] Furthermore, according to the configuration of the first embodiment of the stiffness measuring device 66 according to this embodiment, as described above, the control unit 104 controls the moving motor 100 so that the amount of movement Da of the previous pressing operation of the pressing unit 94 is greater than the amount of movement Db of the next pressing operation of the pressing unit 94. Therefore, if the paper S is stuck to the guide 88 or the like due to an accumulated charge, the paper S can be reliably peeled off the guide 88 or the like.

[0089] Therefore, according to the stiffness measuring device 66 of this embodiment, the stiffness detection process (measurement process) of the paper S can be performed efficiently.

[0090] According to the configuration of the second aspect of the stiffness measuring device 66 of this embodiment, as described above, the control unit 104 determines whether or not the paper S has a tendency to become charged. Therefore, if it is determined that the paper S has a tendency to become charged, the paper S can be discharged by, for example, an ionizer 80 to remove static electricity from the same type of paper S, thereby suppressing paper S transport failures.

[0091] Therefore, according to the image forming system 10 of this embodiment equipped with a stiffness measuring device 66, image formation on the paper S can be performed stably.

[0092] Furthermore, according to the configuration of the stiffness measuring device 66 in this embodiment, as described above, the transport guide 102 is positioned to the right, which is the opposite side of the direction in which the paper S is pressed, with respect to the virtual vertical line VL. Therefore, it is possible to prevent the paper S from sticking to the left side portion of the guide 88, etc., due to the charged surface charge, and to reliably press the paper S with the pressing unit 94.

[0093] Therefore, according to the stiffness measuring device 66 of this embodiment, the stiffness of the paper S can be stably detected.

[0094] 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]

[0095] The present invention is useful as a stiffness measuring device and an image forming device that can further improve the accuracy of detecting the stiffness of recording material. [Explanation of Symbols]

[0096] 10 Image Forming Systems 12 Image forming apparatus 14. Paper feed device 16. Paper transport device (recording material transport device) 18. Main unit of the apparatus (main unit of the apparatus for image forming apparatus) 20 Image forming unit 22 Image forming unit 22Y Image Forming Unit 22M Image Forming Unit 22C Image Forming Unit 22K Image Forming Unit 24 Photoconductor drum 26. Developing Department 28 Transfer section 30 Intermediate transfer belt 32 Secondary transfer roller 34 Fixing section 36 Heating rollers 38 Fixing roller 40 Fixing belt 42 Pressure rollers 44 Main transport path 46 Conveyor Roller Pair 46R Resist Roller vs 48 Reversal transport path 50 Conveyor Rollers 52. Main unit of the device (main unit of the paper feed device) 54 Paper feed tray 56 Paper feed transport path 58 Conveyor roller pair 60. Main unit of the device (main unit of the paper transport device) 62 Main transport path 64 Conveyor Rollers 66 Stiffness measuring device 68 Paper Output Tray 70 Vertical transport path 72 Conveyor Roller Pair 72G Retaining Roller Pair (Retaining Part) 74 Route switching section 76. Paper sensor (paper detection unit) 78 Humidity sensor (humidity detection unit) 80 Ionizer 82 Support Frame 84 drive rollers 86 Driven roller 88 Guide 90 Guide Bar 92 Movable body 94 Pressing part 96. Stiffness sensor (stiffness detection unit) 98 Pressing and moving part 100 Mobile Motor (Mobile Actuator) 102 Conveyor Guide 104 Control Unit 106 CPU 108 ROM 110 RAM 112 Storage section 114 Communications Department CN primary transfer nip TN secondary transfer nip FN Fixing Nips S paper VL (Virtual Vertical Line)

Claims

1. A holding section that holds the recording material in transit in the vertical direction, A pressing section that presses the recording material held by the holding section below the holding position of the holding section, A stiffness detection unit detects the reaction force from the recording material being bent by the pressing unit as the stiffness of the recording material, A pressing movement unit that moves the pressing unit in the direction of pressing the recording material, The system includes a pressing control unit that controls the pressing movement unit to perform multiple pressing operations on the recording material. Stiffness measuring device.

2. A humidity detection unit for detecting the humidity of the environment in which the stiffness measuring device is used, The system includes an environment determination unit that determines whether the environment in which the stiffness measuring device is used is a low-humidity environment, based on the humidity of the environment in which the stiffness measuring device is used as detected by the humidity detection unit. The pressing control unit controls the pressing movement unit to perform multiple pressing operations on the recording material, provided that the environment determination unit determines that the operating environment of the stiffness measuring device is the low humidity environment. The stiffness measuring device according to claim 1.

3. The pressing portion is electrically grounded. The stiffness measuring device according to claim 1.

4. The pressing control unit controls the pressing movement unit such that the speed of the previous pressing operation of the pressing unit is faster than the speed of the next pressing operation of the pressing unit. Furthermore, the system includes a stiffness acquisition unit that acquires the stiffness of the recording material detected by the stiffness detection unit during the next pressing operation of the pressing unit. The stiffness measuring device according to claim 1.

5. The pressing control unit controls the pressing movement unit such that the amount of movement of the pressing unit in the previous pressing operation is greater than the amount of movement of the pressing unit in the next pressing operation. Furthermore, the system includes a stiffness acquisition unit that acquires the stiffness of the recording material detected by the stiffness detection unit during the next pressing operation of the pressing unit. The stiffness measuring device according to claim 1.

6. The pressing control unit controls the pressing movement unit to perform multiple pressing operations of the pressing unit while maintaining a constant speed and movement amount in each pressing operation of the pressing unit. Furthermore, the pressing unit is equipped with a stiffness acquisition unit that acquires the stiffness of the recording material detected by the stiffness detection unit during each pressing operation of the pressing unit. The stiffness measuring device according to claim 1.

7. The system includes a characteristic determination unit that determines whether or not the recording material has a tendency to become easily charged, based on the difference between the stiffness of the recording material obtained from the stiffness detection unit during the previous pressing operation of the pressing unit and the stiffness of the recording material obtained from the stiffness detection unit during the next pressing operation of the pressing unit. The stiffness measuring device according to claim 1.

8. Furthermore, it is provided with a transport guide located below the holding portion, positioned offset to the opposite side of the pressing direction with respect to a virtual vertical line passing through the holding position of the holding portion, and guiding the recording material in the transport direction. The stiffness measuring device according to claim 1.

9. An image forming unit that forms an image on the recording material while it is being transported, A recording material storage section for storing recording material, The device comprises a stiffness measuring device provided between the image forming unit and the recording material storage unit, according to any one of claims 1 to 8. Image forming system.

10. The image forming unit is provided upstream of the image forming unit and includes a static elimination unit for removing static electricity from the recording material during transport. The image forming system according to claim 9.

11. An image forming unit that forms an image on the recording material while it is being transported, A recording material storage section for storing recording material, A stiffness measuring device according to any one of claims 4 to 6 is provided between the image forming unit and the recording material storage unit, The system includes a parameter setting unit that sets control parameters for image formation in the image forming unit based on the stiffness of the recording material obtained from the stiffness detection unit during the next pressing operation of the pressing unit. Image forming system.

Images