JP2007084158A - Sheet loading device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet loading device which senses stably the surface of the uppermost sheet accurately without hindering the aligning operation of an aligning means, despite existence of a curl or surface asperity to a minor degree, a dispersion in the friction coefficient of sheets, and dispersion in the optical properties of sheets. <P>SOLUTION: A sheet sensor 70 is structured so that a roller 73 rolling in the transporting direction is contacted with the surface of the uppermost sheet on a stacking tray 18, whereby the rising/falling motions of the roller 73 are sensed so as to change the output condition. The sensor 70 includes: a sheet surface sensing lever 74 whose fulcrum is supported by a casing structure 410, where the roller 73 is borne at the forefront of rotating; and a photo-interrupter 72 to invert the output condition upon sensing the turning of the lever 74. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus that stacks sheets discharged from an image forming apparatus such as a copying machine, a printer, and a multifunction machine while aligning them, and an image forming apparatus that mounts / connects the sheet stacking apparatus.

  When the processed sheets discharged one by one from the image forming apparatus such as a copying machine or a printer are sequentially stacked on the stacking surface, the vertical and horizontal end surfaces are positioned and stacked, that is, aligned, and thereafter. 2. Description of the Related Art Sheet stacking devices designed for convenience such as packing, organizing, and stapler (binding) processing have been put into practical use.

  Such a sheet stacking apparatus has a sheet stacking unit for stacking discharged sheets, and is rotationally driven with flexibility, and in contact with the sheet during the rotation process, moves in a predetermined direction on the sheet stacking unit. Alignment means (see Patent Document 1).

  Here, an abutting surface is arranged on one end side in the sheet receiving direction, and each time a sheet is discharged, a flexible alignment means called a paddle is rotated once toward the abutting surface, and the paddle is at its maximum. The sheet surface is rubbed while being deformed by being pressed against the upper sheet surface.

  Another sheet stacking apparatus has a housing structure that supports the sheet stacking means so that the sheet stacking means can be moved up and down, and a switch is disposed inside the housing structure along the lifting path of the sheet stacking means, so that the sheet stacking means is provided. Is detected. (See Patent Document 2).

JP 2001-130817 A JP 2002-68561 A

  In a sheet stacking apparatus that operates the aligning unit each time a sheet is discharged and stacks sheets on the sheet stacking unit, the aligning unit becomes cramped as the sheet stacking progresses. Therefore, it is necessary to increase the interval between the sheet stacking unit and the aligning unit according to the sheet stacking height. Therefore, it has been studied to detect / measure the uppermost sheet surface on the sheet stacking means in a non-contact manner using an optical sensor, a television camera, an ultrasonic sensor, a laser distance meter, or the like. However, the calculation burden of image analysis is large in a television camera, and the burden of measurement calculation is large in an ultrasonic sensor or a laser distance meter. Both are expensive and impractical.

  On the other hand, an optical sensor having a light-emitting diode and a phototransistor whose optical axes are fixed at a predetermined crossing angle detects reflected light by emitting infrared light to a stacked sheet. When it becomes, an output peak is formed. This optical sensor is inexpensive and has a simple output calculation process. However, the output level changes depending on the color of the stacked sheets, so that it fails to detect the sheet surface on a black sheet or a black / white / dark mixed printing surface. there is a possibility. Naturally, even when the sheet is curled, wrinkled, or bent three-dimensionally, normal reflected light cannot be obtained, and the sheet surface may be erroneously detected.

  Therefore, the rotation end of the lever member with the fulcrum fixed to the housing structure of the sheet stacking device is positioned on the stacking surface of the sheet stacking means, and this rotation end is brought into contact with the uppermost sheet surface so that the lever member Attempts were made to detect rotation with a microswitch or the like. However, in this mechanical contact method, the contact friction between the lever member and the sheet surface hinders the movement of the sheet and hinders the alignment operation. When the friction on the sheet surface is large, the sheet is caught by the lever member and the alignment is disturbed. There is a problem.

  In addition, when the sheet end portion is curled upward, there is a problem that the sheet end portion hits the lever member and the alignment is disturbed.

  Even if there is some curl or unevenness, the coefficient of friction of the sheet varies, or the optical property of the sheet varies, the alignment operation by the aligning means is not disturbed, and the uppermost level is stable and accurate. An object of the present invention is to provide a sheet stacking apparatus that can detect the sheet surface of the sheet.

  The sheet stacking apparatus according to the present invention includes a sheet stacking unit on which an accepted sheet is stacked, and an aligning unit that moves the sheet in a predetermined direction on the sheet stacking unit. Sheet detecting means for detecting the uppermost sheet stacked on the sheet, and the sheet detecting means includes a rotating member that contacts the uppermost sheet and is rotatable in the predetermined direction. The rotating member is driven to rotate on the surface of the sheet moved by the means.

  In the sheet stacking apparatus of the present invention, the rotating member captures the surface of the sheet and rotates smoothly. Therefore, even if the friction coefficient of the sheet surface is different, the movement resistance of the sheet is uniformly small rotational resistance of the rotating member. Thus, the movement of the sheet by the aligning means is not hindered. The rotating member rotates with the relative movement of the sheet and crushes the sheet curl or bend without colliding with the sheet to correct the sheet evenly. The uppermost sheet surface can be detected accurately.

  Naturally, because of mechanical detection, the optical property difference on the sheet surface does not affect the detection accuracy.

  1 is an explanatory diagram of an image forming apparatus including a sheet stacking apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a mechanism of the sheet stacking apparatus, FIG. 3 is a side view of a sheet detection sensor, and FIG. FIG. 5 is an explanatory view of the operation of the sheet detection sensor, and FIG. 6 is a partial side view of the sheet detection sensor of the comparative example.

  A sheet stacking apparatus 400 according to an embodiment of the present invention includes, for example, a stacking tray 18 that is a sheet stacking unit of the present invention, a paddle 17 that is a matching unit of the present invention, and a sheet detection unit of the present invention, such as a sheet. The sheet detection sensor 70 includes, for example, a rotating roller 73 that is a rotating member of the present invention, a sheet surface detection lever 74 that is a lever member of the present invention, and a photo switch that is a switch means of the present invention, for example. And an interrupter 72.

  As shown in FIG. 1, a sheet stacking apparatus 400, which is an example of an embodiment of the present invention, is disposed on the downstream side of the copying machine 500 and stacks sheets S discharged from the copying machine 500 in alignment. The copying machine 500 includes a reader unit 200 that reads a document and converts it into image data, and a printer unit 300 that forms an image based on the image data. An automatic document feeder (ADF) 100 for feeding is provided.

  The printer unit 300 includes a sheet cassette 321 that can store a large number of sheets S, and forms image data as a visible image on one side or both sides of the sheet S. The reader unit 200 reads a document conveyed by the automatic document feeder 100 at a reading position above the scanner unit 211, but the operator opens the automatic document feeder 100 rearward and places the document on the platen glass 210. For example, the scanner unit 211 can be moved in the left-right direction to read an image on the original surface.

  In any case, the reflected light from the original obtained with the illumination light of the scanner unit 211 forms an image on the CCD image sensor unit 214 via the mirrors 212 and 213. The formed original image is subjected to photoelectric conversion / digital processing by the CCD image sensor unit 214 to form an image signal, and the image signal is input to the printer unit 300.

  The image signal input to the printer unit 300 is modulated and converted into an optical signal, and then the exposure light source 311 is operated. The light emitted from the exposure light source 311 is scanned by the scan unit 312 and enters the photoconductor unit 313. The photoconductor unit 313 is configured integrally with a photoconductor drum 314, a cleaning device (not shown), and a charging device, and forms a latent image on the surface of the photoconductor drum 314 on which the light emitted from the scanned exposure light source 311 rotates. The latent image on the photosensitive drum 314 is developed by the developing unit 315 to become a toner image, and the toner image is transferred to the sheet S conveyed from the sheet cassette 321 in synchronization with the leading edge of the toner image. Thereafter, the sheet S is carried on the conveyance belt 322 and sent to the fixing unit 323, and the toner image is fixed on the sheet S by the fixing unit 323. When single-sided printing or double-sided printing is completed, the sheet S is supplied to the sheet stacking device 400 via the discharge roller 325 as it is.

  The sheet stacking apparatus 400 includes stacking trays 18 and 37, paddles 17 and 34, tray motors 56 and 57, and the like, and stacks sheets S supplied from the copier 500 while aligning them on the stacking trays 18 and 37.

  As shown in FIG. 2, the sheet S supplied to the sheet stacking device 400 is fed to the upper transport path PU and the lower transport path PD according to the inclination of the flapper 13 driven by the solenoid 14 at the upper right in the drawing. It is distributed to. Then, the sheet S proceeding to the transport path PU is stacked on the upper stacking tray 18, and the sheet S proceeding to the lower transport path PD is stacked on the lower stacking tray 37.

  The base of the upper stack tray 18 is fixed to the tray base 44, and guide rollers 46 and 47 that are rotatably attached to the tray base 44 are engaged with the guide rail 64. The timing belt 54 connected to the tray base 44 is driven from a tray motor 56 via a timing belt 58, a worm gear 50, and a worm wheel 51. When the tray motor 56 drives the timing belt 54, the tray table 44 and the stacking tray 18 move up and down together with the guide rollers 46 and 47 guided by the guide rail 64.

  On the other hand, the base of the lower stacking tray 37 is fixed to the tray base 45, and guide rollers 48 and 49 that are rotatably attached to the tray base 45 are engaged with the guide rail 65. The timing belt 55 connected to the tray base 45 is driven from a tray motor 57 via a timing belt 59, a worm gear 52, and a worm wheel 53. When the tray motor 57 drives the timing belt 55, the tray base 45 and the stacking tray 37 are moved up and down together with the guide rollers 48 and 49 guided by the guide rail 65.

  The sheet S conveyed on the upper conveyance path PU is driven by the conveyance drive motor 6 to rotate, and the inlet roller 1 and the driven roller 2. The sheet discharge roller 11 and driven roller rotated by the discharge drive motor 7 are rotated. 12, and is discharged above the stacking tray 18. The rotation of the conveyance drive motor 6 is transmitted to the inlet roller 1 through the timing belts 5 and 3, and the driven roller 2 is in pressure contact with the inlet roller 1. The rotation of the discharge drive motor 7 is transmitted to the paper discharge roller 11 through the timing belts 8 and 10, and the driven roller 12 is in pressure contact with the paper discharge roller 11.

  When the sheet S is discharged from between the discharge roller 11 and the driven roller 12, the discharge roller 11 cooperates with the left and right alignment plates 66 and 67 to execute the alignment operation in the width direction of the sheet S. Then, the paddle motor 16 is activated simultaneously with the discharge of the sheet S, and the flexible paddle 17 starts to rotate counterclockwise in the drawing. The paddle 17 contacts the sheet S discharged onto the stacking tray 18, rubs against the upper surface of the sheet S while undergoing bending deformation, and sweeps the sheet S between the knurled belt 19 and the stacking tray 18. At this time, the knurled belt 19 has already been rotated counterclockwise in the drawing in conjunction with the paper discharge roller 11 by the timing belt 10, and the sheet S is abutted against the reference wall 20 to align the trailing ends of the sheet S.

  The sheet S conveyed on the lower conveyance path PD is driven by the conveyance drive motor 6 to rotate, the entrance roller 21, the first vertical path roller 24, the second vertical path roller 27, the conveyance roller 22, and the driven roller 25. , 28 and the sheet discharge roller 30 and the driven roller 31 which are driven and rotated by the discharge drive motor 7, and are discharged to the upper side of the lower stacking tray 37.

  The rotation of the conveyance drive motor 6 is transmitted to the entrance roller 21 via the timing belt 5, the rotation of the entrance roller 21 is transmitted to the longitudinal path first roller 24 via the timing belt 23, and further the rotation of the longitudinal path first roller 24. Is transmitted to the vertical path second roller 27 via the timing belt 26. The entrance roller 21 is in pressure contact with the transport roller 22. The driven rollers 25 and 28 are in pressure contact with the vertical path first roller 24 and the vertical path second roller 27, respectively. The rotation of the discharge roller 11 driven by the discharge drive motor 7 is transmitted to the discharge roller 30 via the timing belt 29, and the driven roller 31 is in pressure contact with the discharge roller 30.

  When the sheet S is discharged from between the discharge roller 30 and the driven roller 31, the discharge roller 30 cooperates with the left and right alignment plates 68 and 69 to perform the alignment operation in the width direction of the sheet S. Then, simultaneously with the discharge of the sheet S, the lower paddle motor 33 is activated and the flexible paddle 34 starts to rotate counterclockwise in the drawing. The paddle 34 contacts the upper surface of the sheet S discharged to the stacking tray 37, rubs against the upper surface of the sheet S while undergoing bending deformation, and sweeps the sheet S between the knurled belt 36 and the stacking tray 37. The knurled belt 36 has already been rotated counterclockwise in the drawing in conjunction with the sheet discharge roller 30 by the timing belt 40, and the sheet S abuts against the reference wall 38 to align the trailing ends of the sheet S.

  A control unit 420 disposed below the sheet stacking device 400 communicates with the copier 500 shown in FIG. 1 and, based on outputs of various sensors (not shown) and the sheet detection sensors 70 and 80, a conveyance drive motor. 6, discharge drive motor 7, tray motors 56, 57, paddle motors 16, 33, drive motors for alignment plates 66, 67, 68, 69, solenoid 14 and the like to control conveyance, discharge, alignment, stacking, stacking The operations of raising / lowering the trays 18 and 37 are executed in a harmonious manner.

  Now, a sheet detection sensor 70 that detects the uppermost sheet S on the stacking tray 18 is disposed at substantially the same height as the knurled belt 19. In addition, a sheet detection sensor 80 that detects the uppermost sheet S on the stacking tray 37 is disposed at substantially the same height as the knurled belt 36. The sheet detection sensor 70 and the sheet detection sensor 80 are configured to be different at different mounting locations, and the stacking tray 18 and the stacking tray 37 are controlled equally. Therefore, in order to avoid duplication and complication, the upper stacking tray will be described below. 18 and the sheet detection sensor 70 will be described.

  As shown in FIG. 3, the sheet detection sensor 70 is configured by attaching a rotating roller 73 to a rotation end of a paper surface detection lever 74 that is rotatable with a shaft 71 fixed to a housing structure 410 of the sheet stacking device 400. The A photo interrupter 72 is fixed behind the reference wall 20 with a paper surface detection lever 74 interposed therebetween. The photo interrupter 72 has a light emitting diode and a phototransistor opposed to each other by an optical axis 76, and a rotation path of the paper surface detection lever 74 is disposed at a distance between the opposed surfaces.

  As shown in FIG. 4, the wide rotating roller 73 is rotatably supported by a shaft 75.

  In the sheet stacking apparatus 400 configured as described above, when a stacking request signal is sent from the copier 500 shown in FIG. 1 to the control unit 420, the control unit 420 causes the sheet detection sensor 70 to load the stacking surface of the stacking tray 18. 3, that is, the stacking tray 18 is raised and stopped to a height position where the photo interrupter 72 shown in FIG. 3 detects the paper surface detection lever 74. Then, when the sheet stacking device 400 sends out a carry-out permission signal to the copying machine 500, the sheets S on which images are formed are successively supplied from the copying machine 500 and stacked on the stacking tray 18 of the sheet stacking device 400. When the stacking progresses between the rotary roller 73 and the stacking tray 18 and the paper surface detection lever 74 is lifted and is not detected by the photo interrupter 72, the control unit 420 detects the paper surface detection lever 74 again. The stacking tray 18 is lowered to the vertical position. In this manner, the stacking tray 18 is sequentially lowered as much as the sheets S are stacked, and the relative positional relationship between the uppermost sheet S and the paddle 17 on the stacking tray 18, that is, the distance between the two is constant. Maintained.

  When the stacking of the final sheets S is completed and an unloading end signal is sent from the copying machine 500 to the control unit 420, the control unit 420 loads the stacked sheets so that the operator can easily take out the stacked sheet bundle. The tray 18 is lowered to the minimum height position.

  As shown in FIG. 5, when the sheet S is discharged onto the stacking tray 18 from between the rotating discharge roller 11 and the driven roller 12, the paddle 17 rotates in the counterclockwise direction in FIG. Sweeping between the knurled belt 19 and the stacking tray 18, the rotating roller 73 rolls on the surface of the sheet S at this time, and the sheet S moves on the stacking tray 18 almost without resistance. Even if the reference wall 20 side of the sheet S, that is, the rear end side of the conveyance is curled upward, the sheet S can be moved almost without resistance by pressing from the top without hitting the edge of the curl.

  Note that each time one sheet S is discharged, the paddle 17 shown in FIG. 5 rotates once from the 90 ° position shown around the shaft 17C, returns to the same 90 ° position, and stops. Wait until the sheet is discharged. The paddle 17 is configured by bonding a paddle 17A that first hits the paper and a paddle 17B that contacts the paddle 17A.

  On the other hand, in the sheet detection sensor 70J having no rotating roller 73 as shown in FIG. 6, the friction between the sheet S and the sheet detection sensor 70J prevents the movement of the sheet S, and the surface of the sheet S is scratched. In some cases. Further, when the trailing edge of the sheet S is curled upward, the edge of the curl comes into contact with the sheet detection sensor 70J to prevent the movement of the sheet S.

  That is, the paddle 17 comes into contact with the sheet S discharged from the paper discharge roller 11, the movement of the sheet S in the discharge direction is stopped by the paddle 17, a force toward the reference wall 20 is applied, and the sheet S is guided to the knurled belt 19. . Then, the sheet S is pulled to the reference wall 20 by the knurled belt 19. Further, when the sheet S is discharged from between the discharge roller 11 and the driven roller 12, the discharge roller 11 cooperates with the left and right alignment plates 66 and 67 in a direction orthogonal to the conveyance direction. Push to complete alignment. When stacking a large number of sheets S, the sheet S is stacked on the stacking tray 18 by repeating these operations. When the sheet S is pulled by the knurled belt 19, the sheet S is slid under the rotating roller 73 attached to the sheet surface detection lever 74 so that the sheet surface detection lever 74 is placed on the surface of the sheet S. When the sheets S are stacked until the rotary roller 73 reaches a certain height, the stacking tray 18 repeatedly descends by a predetermined amount and maintains an appropriate position. When the sheet detection sensor 70 detects that there is no sheet S by removing the sheet S, the tray 18 rises.

  A sheet S carried out from a general image forming apparatus such as the copying machine 500 generally has a curl, and the curl shape is generally directed upward or downward, or curved in a diagonal line. The sheet detection sensor 70J shown in FIG. 6 is likely to cause an error in detecting the sheet height, particularly when a local curl that is curved only at a part of the front end or the rear end is generated.

  Therefore, the sheet detection sensor 70 detects the sheet height at a position that avoids a local curl position by positioning the rotary roller 73 at a position closer to the front end side in the sheet S conveyance direction by a predetermined amount than the reference wall 20. It becomes possible. Further, the rotation of the rotary roller 73 can prevent damage to the sheet S.

  According to the sheet stacking apparatus 400 of the embodiment configured as described above, it is possible to prevent jamming and buckling due to the sheet S being pulled back, and to improve the alignment. In addition, it is possible to prevent movement traces due to the contact movement of the sheet S and the sheet detection sensor 70 due to the raising and lowering of the stacking tray 18.

  Further, since the rotary roller 73 that can rotate in the alignment direction is brought into contact with the uppermost sheet surface on the stacking tray 18 and the sheet detection sensor 70 that detects the up-and-down movement of the rotary roller 73 and changes the output state is provided. Since the roller 73 captures the surface of the sheet and rotates smoothly, the movement resistance of the sheet S uniformly becomes a small rotational resistance of the rotating roller 73 even if the friction coefficient of the sheet surface is different. Movement is not hindered. The rotating roller 73 rotates with the relative movement of the sheet S to crush and curl the sheet S curl and bend without colliding with each other, so that even the sheet S in which the curl or bend has occurred is net loaded. The top sheet surface can be detected accurately at the height. Naturally, because of mechanical detection, the optical property difference on the sheet surface does not affect the detection accuracy.

  Therefore, it is possible to adopt a paddle having a small size and light weight and a weak force, and it is possible to avoid the damage and wrinkles of the sheet S at the time of a jam as in the case of using a paddle with a strong force.

  Further, the stacking tray 18 is supported so as to be movable up and down with respect to the housing structure 410, and the paddle 17 is fixedly disposed on the housing structure 410 above the stacking tray 18, and the control unit 420 includes the sheet detection sensor 70. By raising and lowering the stacking tray 18 based on the output state, the relative height between the uppermost sheet surface and the paddle 17 is maintained substantially constant. Therefore, the force with which the paddle 17 drives the sheet S from the beginning to the end of the stacking. Even if the minimum frictional force is set so as not to be excessive and insufficient, the sheet S can be reliably and precisely aligned with a stable force.

  Further, the sheet detection sensor 70 also serves as a means for detecting the height position of the stacking tray 18, and the control unit 420 stops the stacking tray 18 to the stacking start height based on the output state of the sheet detection sensor 70. There is no need to provide a separate sensor or measuring instrument (encoder or the like) for returning the origin of the stacking tray 18. The number of ports and calculation load of the control unit 420 are also reduced.

  Further, the sheet detection sensor 70 supports the fulcrum supported by the housing structure 410 and detects the rotation of the paper surface detection lever 74 in which the rotary roller 73 is pivotally supported on the leading end side of the rotation, and the rotation of the paper surface detection lever 74. Since the photo interrupter 72 that reverses the state is provided, the number of parts is small, the light weight is small, and the structure is highly reliable, so that the design of the housing structure 410 is not hindered.

  In addition, since the sheet stacking apparatus 400 is excellent in this way, the image forming apparatus including the copying machine 500 can be improved to have a high stacking quality, less accidents, and high reliability.

  The sheet stacking apparatus of the present invention is used even when combined with other image forming apparatuses such as a copying machine, a printer, a facsimile machine, and a multi-function machine, and can also be configured integrally with these image forming apparatuses. Further, the present invention is not limited to the image forming apparatus, and can be used in combination with an upstream apparatus that performs various inspections, processing, processing, and the like. It is not limited to.

1 is an explanatory diagram of an image forming apparatus including a sheet stacking apparatus according to an embodiment of the present invention. It is explanatory drawing of the mechanism of a sheet stacking apparatus. It is a side view of a sheet detection sensor. It is a partial front view of a sheet detection sensor. It is explanatory drawing of operation | movement of a sheet | seat detection sensor. It is a partial side view of the sheet detection sensor of a comparative example.

Explanation of symbols

6 Conveyance drive motor 7 Discharge drive motor 11, 30 Discharge roller 12, 31 Driven roller 16, 33 Paddle motor (alignment means)
17, 34 Paddle (alignment means)
17A Paddle which hits the paper first 17B Paddle 18 and 37 which contacts the paddle Stacking tray (sheet stacking means)
19, 36 Knurled belt 20, 38 Reference wall 56, 57 Tray motor (sheet stacking means)
66, 67 Alignment plates 70, 80 Sheet detection sensor (sheet detection means)
71, 71, 75, 17C Rotating shaft 72 Photo interrupter 73 Rotating roller 74 Paper surface detection lever

Claims (5)

Sheet stacking means on which received sheets are stacked;
A sheet stacking apparatus comprising: an alignment unit configured to move the sheet in a predetermined direction on the sheet stacking unit;
Sheet detecting means for detecting the uppermost sheet stacked on the sheet stacking means,
The sheet detection means has a rotating member that is rotatable in the predetermined direction in contact with the uppermost sheet,
The sheet stacking apparatus, wherein the rotating member is driven to rotate on the surface of the sheet moved by the aligning means. The sheet stacking means is supported to be movable up and down with respect to the housing structure,
The alignment means is disposed in the housing structure above the sheet stacking means,
Control means for lowering the sheet stacking unit based on the output of the sheet detecting unit to maintain a substantially constant interval between the uppermost sheet and the aligning unit in the sheet stacking process. The sheet stacking apparatus according to claim 1. The sheet detection means also serves as a means for detecting the height position of the sheet stacking means when the sheets are not stacked.
3. The sheet stacking apparatus according to claim 2, wherein the control unit is a unit that stops the sheet stacking unit to a stacking start height based on the output of the sheet detecting unit. The sheet detecting means has a lever member pivotally supported on the housing structure,
4. The sheet stacking apparatus according to claim 2, wherein the rotating member is pivotally supported on a front end side of the rotation of the lever member. 5. An image forming apparatus comprising: an image forming unit that forms an image on the sheet; and the sheet stacking apparatus according to claim 1.

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