Stiffness measuring device

Abstract

This method suppresses a decrease in paper transport performance and allows for optimal measurement of paper stiffness. [Solution] The stiffness measuring device 50 includes a holding roller 51 capable of stopping and holding a sheet of paper S being transported along the transport direction D1, a pressing unit 52 positioned upstream of the holding roller 51 in the transport direction D1 and pressing the sheet of paper S held by the holding roller 51 from one main surface side, a stiffness acquisition unit that measures the reaction force of the sheet of paper S when pressed by the pressing unit 52 and acquires the stiffness of the sheet of paper S, and a guide unit 55 positioned upstream of the holding roller 51 in the transport direction D1 and guiding the sheet of paper S to the holding roller 51. The guide unit 55 is positioned opposite the pressing unit 52 via the transport path of the sheet of paper S and includes a movable guide 58 that can be retracted from that position.

Description

Technical Field

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[0001] The present invention relates to a stiffness measuring device for measuring the stiffness of paper.

Background Art

[0002] In an image forming system that forms an image on paper (sheet material), a technique for detecting the stiffness of the paper and setting various control parameters is known. For example, in the technique described in Patent Document 1, the stiffness of the paper is measured by holding the paper in a stopped state and pressing the end of the paper to measure the reaction force.

Prior Art Documents

Patent Documents

[0003] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​A pressing section is positioned upstream of the holding section in the conveying direction and presses the sheet material held by the holding section from one of its main surfaces, A stiffness acquisition unit that measures the reaction force of the sheet material when pressed by the pressing unit and obtains the stiffness of the sheet material, A guide portion is positioned upstream of the holding portion in the transport direction and guides the sheet material to the holding portion, Equipped with, The guide portion is positioned opposite the pressing portion via the paper transport path and includes a movable guide that can be retracted from that position. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress a decrease in paper transport performance and suitably measure the stiffness of the paper. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing an image forming system according to an embodiment. [Figure 2] This diagram schematically shows the configuration of the stiffness measuring device according to the embodiment. [Figure 3] This figure shows a modified example of the first fixed guide according to the embodiment. [Figure 4] This is a perspective view showing a modified example of the operation of the movable guide according to the embodiment. [Figure 5] This is a block diagram showing a schematic control configuration of a stiffness measuring device according to an embodiment. [Figure 6] This is a flowchart showing the operation flow of the stiffness measuring device according to the embodiment. [Figure 7] This is a diagram illustrating the operation of the stiffness measuring device according to an embodiment. [Figure 8] This is a diagram illustrating the operation of the stiffness measuring device according to an embodiment. [Figure 9] This is a diagram illustrating the operation of the stiffness measuring device according to an embodiment. [Figure 10] This figure shows a modified example of the first fixed guide according to the embodiment.

Embodiment for Carrying out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] [Configuration of Image Forming System] FIG. 1 is a diagram showing an image forming system 1 according to the present embodiment. As shown in this figure, the image forming system 1 includes a paper feeding device 10, a paper conveying device 20, an image forming device 30, and a post-processing device 40.

[0011] The paper feeding device 10 includes a plurality of paper feeding trays 12 on which various papers S classified by basis weight, size, etc. are mounted. The paper feeding device 10 supplies a predetermined paper S one by one to the paper conveying device 20 based on a print job from a control unit (not shown). The paper S is a recording medium on which an image is formed and is an example of the sheet material according to the present invention. The material of the paper S is not particularly limited as long as it is a sheet material capable of measuring stiffness.

[0012] The paper conveying device 20 is disposed on the downstream side in the conveying direction of the paper feeding device 10 and on the upstream side in the conveying direction of the image forming device 30. The paper conveying device 20 has a first conveying path 21 for conveying the paper S conveyed from the paper feeding device 10 to the image forming device 30, and a second conveying path 22 provided by branching from the first conveying path 21. The second conveying path 22 conveys the paper S branched from the first conveying path 21 to the second discharge port 23, for example, when acquiring and registering information of the paper S. A stiffness measuring device 50 for acquiring the stiffness of the paper S is provided in the second conveying path 22. As will be described later, the stiffness measuring device 50 measures the stiffness of the paper S whose conveyance is temporarily stopped in the middle of the second conveying path 22. The stiffness of the paper S is an index indicating the resistance when the paper S is bent and can be represented by various physical quantities. Details of the configuration of the stiffness measuring device 50 and the like will be described later.

[0013] The image forming apparatus 30 forms an image (transfer, printing) of the image read from the document on the sheet S conveyed from the paper feeding apparatus 10 by using an electrophotographic process. Further, the image forming apparatus 30 receives job data including image data in PDL (Page Description Language) format, setting information, etc. from an external client terminal through a network, and forms an image on the sheet S based on this job data. The client terminal is, for example, a PC, a tablet terminal, a smartphone, etc. The image forming apparatus 30 discharges the sheet S on which the image has been formed to the post-processing apparatus 40.

[0014] The post-processing apparatus 40 executes predetermined post-processing on the sheet S on which the image has been formed by the image forming apparatus 30 based on a post-processing job from a control unit (not shown). Examples of the post-processing include, for example, perforation, folding, foil stamping, binding, cutting, stapling, pasting, sewing, etc. The post-processing apparatus 40 discharges the sheet S on which the post-processing has been completed to the first discharge port 42.

[0015] [Configuration of the Stiffness Measuring Device] FIG. 2 is a diagram schematically showing the configuration of the stiffness measuring device 50. As shown in FIG. 2, the stiffness measuring device 50 is disposed in the second conveyance path 22 of the paper conveyance device 20. In the second conveyance path 22, the sheet S is conveyed from the lower side to the upper side by a plurality of conveyance rollers 25. The stiffness measuring device 50 measures the stiffness of the sheet S at a portion of the second conveyance path 22 where the conveyance direction D1 of the sheet S is vertically upward. Hereinafter, the vertical direction along the conveyance direction D1 is referred to as the Z direction. Further, the direction orthogonal to the recording surface (main surface) of the sheet S conveyed in the conveyance direction D1 is referred to as the Y direction, and the width direction of the sheet S orthogonal to both the Z direction and the Y direction is referred to as the X direction.

[0016] Specifically, the stiffness measuring device 50 includes a pair of holding rollers 51, a pressing portion 52, a reaction force measuring portion 53, and a guide portion 55. The pair of holding rollers 51 are holding parts capable of stopping and holding the paper S being transported along the transport direction D1. Specifically, the pair of holding rollers 51 are arranged side by side in the Y direction and are biased, for example, in a direction toward each other, thereby gripping and holding the paper S with a predetermined holding force. The pair of holding rollers 51 hold the paper S with its main surface oriented approximately perpendicular to the Y direction. Furthermore, although not particularly limited, it is preferable that the pair of holding rollers 51 also serve as drivable transport rollers.

[0017] The pressing section 52 presses the edge of the paper S during stiffness measurement. Specifically, the pressing section 52 is positioned upstream (below) the holding roller 51 in the transport direction D1 and on one side in the Y direction (right side in Figure 2) of the transport path R. Here, the transport path R refers to the path of the paper S along the Z direction in the stiffness measuring device 50. The pressing section 52 is long in the X direction so as to be able to contact the entire width of the paper S, and is formed in a blade shape with a pointed tip on the other side in the Y direction (left side in Figure 2). During stiffness measurement, the pressing section 52 presses the lower end of the paper S held by the holding roller 51 in a pressing direction D2 along the Y direction from one main surface side (right side in Figure 2) to the other side, causing the paper S to bend. The pressing portion 52 is supported by a moving mechanism 521 so as to be movable in the Y direction. The moving mechanism 521 includes, for example, a rack gear extending in the Y direction and integrally configured with the pressing portion 52, and a stepping motor that meshes with the rack gear. The pressing portion 52 moves in the Y direction by the drive of the stepping motor. However, the configuration of the moving mechanism 521 is not particularly limited as long as it is able to move the pressing portion 52 in the Y direction.

[0018] The reaction force measuring unit 53 measures the reaction force of the paper S when it is pressed by the pressing unit 52. The reaction force measuring unit 53 is, for example, a load cell (pressure sensor) positioned between the pressing unit 52 and the moving mechanism 521. The reaction force measuring unit 53 outputs the acquired reaction force value to the control unit 60 (see Figure 5). The stiffness measuring unit according to the present invention is composed of the reaction force measuring unit 53 and the control unit 60.

[0019] The guide section 55 is positioned upstream of the holding roller 51 in the transport direction D1 and guides the paper S to the holding roller 51. In this embodiment, the guide section 55 causes the paper S to enter the holding roller 51 along the vertical direction. Specifically, the guide section 55 includes a first fixed guide 56, a second fixed guide 57, and a movable guide 58. Each of the first fixed guide 56, the second fixed guide 57, and the movable guide 58 is formed, for example, in the shape of a plate and is arranged to cover both sides of the transport path R in the Y direction.

[0020] The first fixed guide 56 is located upstream of the holding roller 51 in the transport direction D1 and fixed to one side in the Y direction relative to the transport path R. The first fixed guide 56 has a through hole 56a that penetrates in the Y direction in the guide surface that guides the paper S. The through hole 56a is formed in a shape that is elongated in the X direction, corresponding to the shape of the pressing part 52 (pressing surface) when viewed from the other side in the Y direction. The pressing part 52 is located on one side in the Y direction of the through hole 56a when the paper S is not being pressed, and it moves in and out of the through hole 56a in the Y direction when the paper S is being pressed. Furthermore, it is preferable that the gap between the pressing portion 52 and the through hole 56a in the normal state be as small as possible to prevent the paper S from getting stuck in it during transport. Furthermore, as shown in Figure 3, the through-hole 56a may have a step T in the Y direction between its open ends such that the downstream end in the transport direction D1 is further away in the Y direction from the transport path R than the upstream end in the transport direction D1. In this case, the occurrence of problems where the paper S being transported enters the through-hole 56a can be suppressed.

[0021] As shown in Figure 2, the second fixed guide 57 is fixed upstream of the holding roller 51 in the transport direction D1 and on the other side of the transport path R in the Y direction. More specifically, the second fixed guide 57 is positioned opposite the lower half of the first fixed guide 56 across the transport path R. The upper end of the second fixed guide 57 is spaced apart from the nip portion of the holding roller 51 by a distance L1 in the vertical direction. Therefore, as will be described later, the second fixed guide 57 is located upstream of the lower end (rear end) of the sheet S held by the holding roller 51 in the conveyance direction D1 during stiffness measurement (see FIG. 7). Further, a detection sensor 571 capable of detecting the position of the sheet S in the conveyance direction D1 is fixed to the second fixed guide 57. The detection sensor 571 is a sensor capable of detecting the passage of the sheet S in the conveyance direction D1, that is, the lower end of the sheet S, and outputs the detection result to the control unit 60. Note that the detection sensor 571 may be fixed to the first fixed guide 56 instead of the second fixed guide 57.

[0022] The movable guide 58 is disposed at a position facing the upper half of the first fixed guide 56 via the conveyance path R and above the second fixed guide 57. The movable guide 58 of the present embodiment is configured to be movable in the Y direction, for example, by driving a drive motor 581 (see FIG. 5). As will be described later, the movable guide 58 is normally disposed at a position close to the conveyance path R to guide the sheet S, and moves to the other side in the Y direction and away from the conveyance path R during stiffness measurement. Further, the lower end of the movable guide 58 is spaced apart from the nip portion of the holding roller 51 by a distance L2 (<L1) in the vertical direction. Therefore, as will be described later, the lower end of the movable guide 58 is located upstream of the lower end of the sheet S held by the holding roller 51 in the conveyance direction D1 during stiffness measurement (see FIG. 7). Note that the operation mode of the movable guide 58 is not particularly limited as long as it is configured to be retractable from a position facing the pressing portion 52 via the conveyance path R. For example, as shown in FIG. 4, instead of moving in the Y direction, it may move in the Z direction (illustrated by a broken line), or may rotate to the other side in the Y direction (illustrated by a one-dot chain line). Alternatively, only a part including a portion facing the pressing portion 52 via the conveyance path R may be configured to move (illustrated by a two-dot chain line).

[0023] FIG. 5 is a block diagram showing a schematic control configuration of the stiffness measurement device 50. As shown in this figure, the stiffness measuring device 50 includes a control unit 60. The control unit 60 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc., and controls the operation of each part of the stiffness measuring device 50. Specifically, the control unit 60 controls the operation of the holding roller 51, the moving mechanism 521, and the drive motor 581 based on the output from the detection sensor 571, etc., and acquires the stiffness of the paper S based on the output from the reaction force measuring unit 53. Note that the control unit 60 does not have to control only the stiffness measuring device 50, but may, for example, control the entire image forming system 1.

[0024] [Operation of the stiffness measuring device] The operation of the stiffness measuring device 50 during stiffness measurement will be explained. Figure 6 is a flowchart showing the operation flow of the stiffness measuring device 50 during stiffness measurement. Figures 7 to 9 are diagrams illustrating the operation of the stiffness measuring device 50. Here, for example, the stiffness measurement of the paper S being transported is performed based on an execution command from the control unit 60.

[0025] As shown in Figure 6, during stiffness measurement, the control unit 60 first stops the transporting paper S at a predetermined position using the holding roller 51 based on the output of the detection sensor 571 and holds it (step S1; Figure 7). Specifically, the control unit 60 stops transporting the paper S and holds the paper S with the holding roller 51 after a predetermined time has elapsed since the detection sensor 571 detected the passage of the rear end of the paper S. As a result, the paper S is held at a predetermined stiffness measurement position where its rear end is located at a vertical distance L3 from the nip portion of the holding roller 51. Here, distance L3 is smaller than the vertical distance L1 between the upper end of the second fixed guide 57 and the nip portion of the holding roller 51. In other words, the upper end of the second fixed guide 57 is located upstream in the transport direction D1 from the rear end of the paper S held by the holding roller 51. This prevents the bent paper S from coming into contact with the second fixed guide 57 when the pressing unit 52 presses the paper S in the Y direction in step S3 described later. Consequently, the stiffness measurement can be performed with accuracy. The vertical gap (i.e., L1-L3) between the rear end of the paper S and the upper end of the second fixed guide 57 is set to ensure a predetermined distance, taking into account the stopping accuracy of the paper S and the dimensional tolerances of each component. Furthermore, the distance L3 is smaller than the vertical distance L2 between the lower end of the movable guide 58 and the nip portion of the holding roller 51. In other words, the lower end of the movable guide 58 is located upstream in the transport direction D1 from the rear end of the paper S held by the holding roller 51. This prevents the gap between the lower end of the movable guide 58 and the second fixed guide 57 located below the movable guide 58 from becoming too large. Consequently, it prevents paper jams caused by paper S getting stuck in this gap.

[0026] Next, the control unit 60 drives the drive motor 581 to move the movable guide 58, retracting it from the position facing the pressing unit 52 via the transport path R (step S2; Figure 8). In this embodiment, the movable guide 58 is moved to the other side in the Y direction, separating it from the paper S (transport path R). At this time, the amount of movement of the movable guide 58 in the Y direction is greater by a predetermined amount (for example, 10 mm) than the amount of pressure (distance L4) of the pressing part 52 in step S3, as will be described later.

[0027] Next, the control unit 60 drives the moving mechanism 521 to move the pressing unit 52 in the pressing direction D2, pressing the rear end of the paper S (step S3; Figure 9). As a result, the rear end of the paper S is pushed and bent to the other side in the Y direction, with the nip portion of the holding roller 51 as the base end. Specifically, the control unit 60 detects, for example, the position where the tip of the pressing unit 52 begins to contact the main surface of the paper S, based on the output of the reaction force measuring unit 53, and sets this position as the reference position of the pressing unit 52. The control unit 60 moves the pressing unit 52 to the other side in the Y direction by a predetermined distance L4 (for example, several mm) from the reference position. As a result, the pressing unit 52 presses and bends the rear end of the paper S. Here, as described above, the amount of movement (retraction) of the movable guide 58 in the Y direction in step S2 is a predetermined amount greater than the amount of pressure (distance L4) applied by the pressing part 52. This prevents the bent paper S from coming into contact with the movable guide 58, even if, for example, the paper S is warped (shown by a dashed line in Figure 9). Consequently, the stiffness measurement can be performed with high accuracy.

[0028] Next, the control unit 60 measures the reaction force that the pressing unit 52 receives from the paper S and obtains the stiffness of the paper S based on the measured reaction force (step S4). Specifically, the control unit 60 obtains the reaction force received by the pressing unit 52 from the paper S from the reaction force measuring unit 53, and obtains this reaction force (pressing force) as the stiffness of the paper S.

[0029] Next, the control unit 60 returns the movable guide 58 to its normal position before retraction and releases the pressure on the paper S by the pressing unit 52 (step S5). Specifically, first the control unit 60 drives the drive motor 581 to move the movable guide 58 to one side in the Y direction, returning it to its normal position (position in Figure 2) that guides the paper S to the holding roller 51. The control unit 60 also drives the moving mechanism 521 to move the pressing unit 52 in the Y direction, returning it to its normal position (position in Figure 2) to one side in the Y direction from the transport path R. This releases the pressing state of the paper S by the pressing unit 52.

[0030] Next, the control unit 60 releases the paper S from the holding roller 51 and transports the paper S with the transport roller 25 to discharge it from the second discharge port 23 (step S6). This completes the measurement of the paper's stiffness. The acquired stiffness of the paper's stiffness is used to set control parameters related to image formation. These control parameters may be set in the same manner as the parameter setting process described in, for example, Japanese Patent Application Publication No. 2024-019982.

[0031] [Technical effects of this embodiment] As described above, according to this embodiment, the guide portion 55 that guides the paper S (sheet material) to the holding roller 51 is positioned opposite the pressing portion 52 via the transport path R of the paper S, and includes a movable guide 58 that can be retracted from that position. Therefore, when stiffness measurement is not being performed, the movable guide 58 can guide the paper S to a position facing the pressing section 52. On the other hand, when stiffness measurement is being performed, the movable guide 58 can be retracted from the position facing the pressing section 52, allowing the pressing section 52 to press the paper S. This eliminates the need to provide a large gap in the guide section 55 and avoids interference between the guide section 55 and the pressing section 52 (or the paper S). Thus, a decrease in the transport performance of the paper S can be suppressed, and the stiffness of the paper S can be measured appropriately.

[0032] Furthermore, according to this embodiment, the second fixed guide 57 is positioned upstream of the paper S held by the holding roller 51 in the transport direction D1, and at a predetermined distance from the paper S in the transport direction D1. This prevents the paper S from coming into contact with the second fixed guide 57 when the pressing part 52 presses the paper S in the Y direction. Consequently, stiffness measurement can be performed with greater accuracy.

[0033] Furthermore, according to this embodiment, the end of the movable guide 58 on the upstream side (lower side) in the transport direction D1 is positioned upstream of the paper S held by the holding roller 51 in the transport direction D1. This prevents the gap between the lower end of the movable guide 58 and the second fixed guide 57 located below the movable guide 58 from becoming too large. Consequently, it prevents paper jams caused by paper S getting stuck in this gap.

[0034] Furthermore, according to this embodiment, the guide section 55 guides the paper S into the holding roller 51 along the vertical direction, and the pressing section 52 presses the paper S in a direction perpendicular to the vertical direction. This minimizes the effect of gravity when pressing down on the paper S, and consequently, allows for more accurate stiffness measurements.

[0035] Furthermore, according to this embodiment, the first fixed guide 56 has a through hole 56a on the guide surface that guides the paper S, corresponding to the shape of the pressing portion 52. When the paper S is pressed, the pressing portion 52 extends and retracts from the through hole 56a of the first fixed guide 56. This allows the first fixed guide 56 to guide the paper S appropriately in the space surrounding the pressing portion 52.

[0036] Furthermore, according to this embodiment, the through hole 56a of the first fixed guide 56 may have an opening on the downstream side in the transport direction D1 that is further away from the transport path R than the opening on the upstream side in the transport direction D1. This makes it possible to suppress the occurrence of problems where the paper S gets stuck in the through-hole 56a while being transported.

[0037] Furthermore, according to this embodiment, the movable guide 58 moves in the same direction as the pressing direction D2 by an amount greater than the amount of pressure (distance L4) applied by the pressing section 52, after the holding roller 51 has held the paper S but before the pressing section 52 presses the paper S. This prevents situations where the bent paper S comes into contact with the movable guide 58, even if the paper S is warped, for example. Consequently, stiffness measurement can be performed with greater accuracy.

[0038] Furthermore, according to this embodiment, a detection sensor 571 capable of detecting the position of the paper S is fixed to the second fixed guide 57 (or the first fixed guide 56). Therefore, unlike when the detection sensor 571 is placed on the movable guide 58, the position of the detection sensor 571 can be fixed. This makes it possible to suppress the deterioration of the accuracy of the paper S position control based on the output of the detection sensor 571.

[0039] [others] Although one embodiment of the present invention has been described above, the embodiments to which the present invention can be applied are not limited to the embodiments and their modifications described above, and can be modified as appropriate without departing from the spirit of the present invention.

[0040] For example, in the above embodiment, the pressing part 52 is made to extend and retract from a through hole 56a provided in the first fixed guide 56. However, as shown in Figure 10, for example, instead of providing a through hole in the first fixed guide 56, the first fixed guide 56 may be configured to retract from the operating range of the pressing part 52. In this case, paper jams caused by paper S entering the through hole 56a can be suppressed.

[0041] Furthermore, in the above embodiment, the transport direction D1 of the paper S is assumed to be aligned with the vertical direction, but the transport direction according to the present invention does not have to be aligned with the vertical direction. Furthermore, in the above embodiment, the case in which the stiffness measuring device 50 is provided on the paper transport device 20 was described. However, the position of the stiffness measuring device in the image forming system is not particularly limited, and it may be placed, for example, on the image forming device. [Explanation of Symbols]

[0042] 1. Image forming system 25 Conveyor rollers 50 Stiffness measuring device 51 Retaining roller (retaining part) 52 Pressing part 53 Reaction force measurement section (stiffness acquisition section) 55 Guide section 56. First Fixed Guide 56a Through hole 57. Second Fixed Guide 58 Movable Guide 60 Control section (stiffness acquisition section) 571 Detection Sensor D1 Conveying direction D2 Pressing direction R transport route S Paper (Sheet Material)

Claims

1. A holding unit capable of stopping and holding sheet material being transported along the transport direction, A pressing section is positioned upstream of the holding section in the conveying direction and presses the sheet material held by the holding section from one of its main surfaces, A stiffness acquisition unit that measures the reaction force of the sheet material when pressed by the pressing unit and obtains the stiffness of the sheet material, A guide portion is positioned upstream of the holding portion in the transport direction and guides the sheet material to the holding portion, Equipped with, The guide portion is positioned opposite the pressing portion via the conveying path of the sheet material and includes a movable guide that can be retracted from that position. Stiffness measuring device.

2. The aforementioned guide section is A first fixing guide fixed to one of the main surfaces of the transport path, A second fixing guide is fixed to the other main surface side of the sheet material, relative to the aforementioned transport path. including, The stiffness measuring device according to claim 1.

3. The second fixing guide is positioned upstream of the sheet material held by the holding portion in the transport direction, and at a predetermined distance from the sheet material in the transport direction. The stiffness measuring device according to claim 2.

4. The movable guide is positioned such that its upstream end in the transport direction is located upstream of the sheet material held by the holding portion in the transport direction. The stiffness measuring device according to claim 1.

5. The guide portion causes the sheet material to enter the holding portion along the vertical direction. The pressing portion presses the sheet material in a direction perpendicular to the vertical direction. The stiffness measuring device according to claim 1.

6. The first fixing guide has a through hole in the guide surface that guides the sheet material, corresponding to the shape of the pressing portion. The pressing portion extends and retracts from the through hole of the first fixing guide when pressing the sheet material. The stiffness measuring device according to claim 2.

7. The through hole of the first fixed guide has an opening on the downstream side in the conveying direction that is further away from the conveying path than the opening on the upstream side in the conveying direction. The stiffness measuring device according to claim 6.

8. The movable guide moves in the same direction as the pressing direction of the pressing part by an amount greater than the amount of pressure applied by the pressing part, after the holding part has held the sheet material and before the pressing part presses the sheet material. The stiffness measuring device according to claim 1.

9. The system includes a detection sensor fixed to the first or second fixing guide, which is capable of detecting the position of the sheet material. The stiffness measuring device according to claim 2.

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