JP4189468B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer. Specifically, the present invention accurately detects the size of an indeterminate sheet placed on a sheet feeding unit and selects an appropriate size from a plurality of sheets. The present invention relates to an image forming apparatus for selecting a sheet and transferring and fixing a toner image.

  In a sheet feeding device used in an image forming apparatus, with the diversification of sheet sizes to be used, a configuration that can supply various types of regular and irregular size sheets from one sheet feeding cassette has been adopted. ing. Hereinafter, the standard size refers to a standardized sheet size such as A4 and B5, and the irregular size refers to a sheet size other than the standard size. The standard sheet refers to a standard size sheet.

  In the paper feeding apparatus having such a configuration, it is necessary to select an appropriate sheet in order to achieve the size harmony with the toner image formed on the image forming apparatus. However, the initial sheet selection is often manually input by the user. It was. However, in recent years, various size detection methods and the like have been proposed for automatically detecting the size of a sheet placed on a cassette, including an indeterminate size, more automatically.

  For example, in Patent Document 1, a restricting plate that guides the side edges of the stacked sheets is movably provided, and the movable restricting plate is moved according to the sheet size. Some detection mechanisms such as a micro switch and a photo sensor that operate in conjunction with this are provided, and the sheet size is detected in an ON / OFF state of the detection mechanism. In addition, when detecting the size including the indefinite type sheet, for example, a variable resistor or the like (hereinafter referred to as a position sensor) whose value is continuously changed according to the movement of the movable restricting plate is provided. A method has been proposed.

  In Patent Document 2, a conversion member that converts the output of the detection mechanism that changes according to the position of the movable restricting plate into a certain code is provided, and it is known that the indefinite sheet is set according to the code. A paper feeding device that determines the sizes of a regular sheet and an irregular sheet has been proposed. Further, in Patent Document 3, a code and a position sensor are combined when detecting the sheet size, level detecting means (code detection) that changes stepwise depending on a predetermined position, and linear that changes repetitively and continuously for each predetermined position. There has been proposed a size detection device and an image forming apparatus that constitute a detection mechanism with a detection means (position sensor) and more accurately determine the size of an indeterminate sheet according to a combination of outputs of the detection means.

JP 05-24710 JP 2001187763 A JP 2002-193485 A

  However, when detecting the sheet size, it is effective to use a position sensor that can output continuously according to the movement of the movable restricting plate as the size detection element. In order to accurately distinguish the irregular sheet, it is necessary to detect the position of the movable restricting plate in units of several millimeters. It is extremely difficult to realize this accuracy only with the mechanism of the movable restricting plate without malfunction, and the cost becomes high.

  Further, in a sheet size detection apparatus using a position sensor, if a detectable sheet size difference (size range) becomes large, for example, sheet detection from A5 size to A3 size is possible. Since the output fluctuation value of the position sensor is small, errors due to variations in resistance value cannot be ignored. For example, even if the sheet size is the same, the output is not constant due to variations in the resistance value, and the size may be erroneously detected.

  The present invention has been made in view of such circumstances, and greatly improves the size detection accuracy of an indeterminate sheet with a simple configuration without being affected by variations in detection elements, and selects an appropriate sheet accurately. An object of the present invention is to provide an image forming apparatus with high operability.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a fixed size value storage unit that stores a size value of a fixed sheet in advance, and a fixed position on a sheet end surface of a fixed sheet placed on a sheet feeding unit. The displacement amount detecting means for detecting the displacement amount to the end face position of the sheet placed on the sheet feeding unit, and the size value of the sheet placed on the sheet feeding unit from the displacement amount and the size value of the standard sheet. And a calculation means for calculating.

  In particular, in the image forming apparatus according to claim 2, in the image forming apparatus according to claim 1, the image forming apparatus is placed on the sheet feeding unit from a fixed position of a sheet end surface of the fixed sheet placed on the sheet feeding unit. The displacement amount up to the end surface position of the sheet is amplified, and an accurate displacement amount is calculated on the basis of the amplified displacement amount.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the displacement amount detecting means is fixed at a fixed position on the sheet end surface of the fixed sheet placed on the sheet feeding unit. It is composed of a standard sheet restricting member and an auxiliary restricting member that abuts against the sheet end surface of the sheet placed on the paper feed unit, and is configured to detect the amount of displacement between the auxiliary restricting member and the regular sheet restricting member. Yes.

  The image forming apparatus according to claim 4 is the image forming apparatus according to claim 3, wherein the auxiliary regulating member is supported by a support shaft rotatably attached to one end of the fixed sheet regulating member. The displacement is detected by the rotation angle formed between the shaft and the fixed sheet regulating member.

  In the image forming apparatus according to claim 5, in the image forming apparatus according to claim 4, the rotation angle between the support shaft and the fixed sheet regulating member is amplified by the gear train, and the displacement amount is determined by the amplified rotation angle. The size value of the sheet placed on the sheet feeding unit is calculated based on the detected value. According to the above-described means configuration, the following operational effects can be obtained.

  The image forming apparatus according to the present invention is configured to detect the amount of displacement from the fixed position of the sheet end face of the fixed sheet placed on the paper feed section to the end face position of the sheet placed on the paper feed section. Therefore, the reference position for detecting the displacement can be changed according to the size value of the standard sheet. As a result, the output fluctuation range of the position sensor for detecting the displacement amount can be increased, so that erroneous detection of the size due to the variation of the detection element can be reduced, and the irregular sheet can be selected appropriately. It can be a forming device.

  Further, the amount of displacement from the standard position of the sheet end face of the standard sheet placed on the paper feed unit to the end face position of the sheet placed on the paper feed unit is amplified, and calculation is performed based on the amplified displacement amount. With this configuration, it is possible to improve the accuracy of the amount of displacement to be detected without correcting variation, and it is possible to detect the sheet size of an irregular sheet more accurately.

  Further, the displacement amount detecting means includes a fixed sheet restricting member fixed at a fixed position on a sheet end surface of the fixed sheet placed on the paper feed unit, and an auxiliary restricting member contacting the end surface of the sheet placed on the paper feed unit. If it is configured to detect the amount of displacement between the auxiliary restricting member and the standard sheet restricting member, the size of the indeterminate sheet can be obtained with a simple mechanical structure without significant change from the conventional structure. Detection is possible.

  Further, the auxiliary restricting member is supported by a support shaft rotatably attached to one end of the standard sheet restricting member, and the displacement amount is detected by a rotation angle formed between the support shaft and the regular sheet restricting member. In this case, the displacement amount can be detected more easily, and the amplification by the gear train can be easily performed. Therefore, the accurate displacement amount can be easily detected with a simple configuration.

  As described above, in the image forming apparatus according to the present invention, the displacement detected by the sensing element is amplified to improve the detection accuracy, while a plurality of displacement ranges that can be detected by amplification are reduced. By providing a reference position of the standard sheet and detecting a displacement from the reference position, the detection width that can be detected by one detection element is reduced to improve the detection accuracy as a whole.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 includes an automatic document feeder 10, an image reading unit 20, an image processing unit (not shown), an image forming unit 30, a paper feeding unit 40, a fixing device 50, and a paper discharge unit 60. An image reading unit 20 is mounted on the upper part of the main body of the image forming apparatus 100, and an automatic document feeder 10 is further mounted thereon.

  The automatic document feeder 10 includes a document table 11, a sheet discharge table 19, a document pressing plate 12 constituting a sheet feeding mechanism 13, a plurality of roller groups 14, 15 and 16, and a document transport path. The roller group of the paper feed mechanism 13 includes three types of rollers: a pickup roller 14 that pulls out a document from the document table 11, a feed roller 15 that feeds the document to a document transport path, and a separation roller 16 that prevents document multi-feeding.

  The document table 11 has a sheet feeding tray on which a plurality of documents can be set. A pair of regulating plates 18 for positioning the document in the width direction are provided on the sheet feeding plate so as to be movable in the width direction. The document placed on the document table 11 with the copy surface facing upward is urged upward by the document pressing plate 12 to come into contact with the pickup roller 14 and is fed from the document table 11 by the rotation of the pickup roller 14. The sheets are separated one by one by the feed roller 15 and the separation roller 16 and fed into the document conveyance path.

  A slit glass 17 is provided at the boundary of the image reading unit 20 at the end of the document transport path, and a paper discharge table 19 is provided below the document table 11. When the document sent to the document conveyance path by the sheet feeding mechanism 13 passes through the slit glass 17, the image is read by the image reading unit 20, and then conveyed on the sheet discharge path and placed on the sheet discharge table 19. Is done.

  The image reading unit 20 includes a scanning unit 21 including a light source L that irradiates a document and a mirror 22, a traveling body 25 including two mirrors 23 and 24 that guide reflected light, an imaging lens 26, and a CCD image sensor 27 (hereinafter, referred to as “scanning unit”) CCD sensor 27). In the image reading unit 20, when the document passes over the slit glass 17 provided in the document conveyance path, the light source L of the scanning unit 21 stopped below the slit glass 17 irradiates the document, thereby obtaining image data. The reflected light is read and guided to the CCD sensor 27 through the traveling body 25 and the imaging lens 26 including the two mirrors 23 and 24 to form an image.

  The CCD sensor 27 converts the read optical image into electronic image data and sends it to an image processing unit (not shown) formed on the system board. The image processing unit performs analog processing, A / D conversion, shading correction, image compression processing, and the like on the electronic image data, and then transports digitized image information data to the image forming unit 30.

  The image forming unit 30 has a drum-shaped photoconductor 1 on the surface of which a latent image is formed, and the surface of the photoconductor 1 is substantially uniform in the order of operation along the outer peripheral surface of the photoconductor 1. A charging device 31 that charges the surface of the photosensitive member 1, an exposure device 32 that writes an electrostatic latent image on the surface of the photosensitive member 1, and a toner image transferred to the latent image formed on the surface of the photosensitive member 1 to form a toner image. A developing device 33, a transfer separation device 34 for transferring the toner image carried by the photosensitive member 1 to the recording sheet, separating the recording sheet from the photosensitive member 1, and a cleaning device 35 for cleaning the surface of the photosensitive member 1 after the transfer. It is arranged.

  The exposure device 32 of the image forming unit 30 electrically modulates the semiconductor laser based on the digitized image information data, and performs sub-scanning with a polyhedral reflecting mirror 36 (polygon mirror) and a lens group through a collimator lens. . Further, the main scanning is performed by rotating the photosensitive member 1, and the electrostatic latent image of the original image is reproduced on the photosensitive member 1.

  Prior to exposure, a predetermined surface charge is applied to the photosensitive member 1 by corona discharge of the charging device 31, but the charge of the exposed portion is reduced in accordance with the exposure amount by laser light irradiation, resulting in an image. An electrostatic latent image corresponding to the information data is formed on each photoconductor 1. The electrostatic latent image is visualized by the developer toner supplied from the developing device 33 and becomes a toner image.

  A paper feed unit 40 is provided at the lower part of the main body of the image forming apparatus 100. A movable plate 42 that is lifted upward by lifting means is disposed at the bottom of the paper feed tray 41 that stores recording sheets. The movable plate 42 on which the recording sheet is placed receives the paper feed start signal and lifts the recording sheet to the upper limit position limited by the upper limit detection sensor. At the same time, the pickup roller 43 falls so that the uppermost recording sheet placed thereon comes into contact with the pickup roller 43.

  The recording sheet in contact with the pickup roller 43 is fed from the paper feed tray 41, separated one by one by the feed roller 44 and separation roller 45, and then fed to the registration roller 47 by being guided by the intermediate roller 46. The The recording sheet is conveyed to the transfer / separation device 34 after the recording sheet is bent and fed by a registration roller 47, and the toner image formed on the surface of the photoreceptor 1 is transferred onto the recording sheet by the transfer / separation device 34. Batch transfer.

  The recording sheet from which the toner image has been transferred and separated is conveyed to a fixing device 50 through a sheet conveying path B formed in a substantially vertical direction and subjected to a fixing process. The recording sheet heated for the fixing process is cooled by a cooling fan (not shown), discharged by a discharge roller 61, and placed on a discharge tray 62. Alternatively, the single-sided image processed recording sheet sent to the re-conveying path 64 by the paper discharge path switching plate 63 is again subjected to double-sided image processing in the image forming unit 30 and then discharged by the paper discharge roller 61 of the paper discharge unit 60. The paper is discharged onto the table 62.

  Hereinafter, the paper feed tray 41 of the image forming apparatus 100 constituting the gist of the present invention will be described. FIG. 2 is a conceptual configuration diagram viewed from the upper surface of the paper feed tray 41 excluding the movable plate 42. The paper feed tray 41 includes side edge restricting plates 71 and 71 for restricting both end surfaces of the recording sheet S, a pair of rack gears 72 and 72 for transmitting driving force to the side edge restricting plates 71 and 71, and a pair of rack gears 72. , 72 and a pinion gear 73 rotating, a regulating plate fixing member 74 for fixing the side edge regulating plate 71 at a fixed position, a rear end regulating plate 75 for regulating the rear end surface of the recording sheet S, and the like. It is configured.

  The pair of side edge restricting plates 71 and 71 can move along the restricting plate fixing member 74 in a direction perpendicular to the paper feeding direction (the direction of the heel), and either one of the side edge restricting plates 71 is manually moved. By moving, the rack gear 72 is moved simultaneously, and the other side edge regulating plate 71 is also moved simultaneously via the pinion gear 73. The pair of side edge regulating plates 71 and 71 are always moved at equal positions around the rotation center axis of the pinion gear 73. The rear end restricting plate 75 is configured in substantially the same manner and detailed description is omitted, but the rear end restricting plate 75 moves in the paper feeding direction along the rear restricting plate fixing member 76.

  A pair of rack gears 72, 72, a pinion gear 73, and the like are disposed below the bottom plate 70 of the sheet feed tray 41, and the sheet S is placed on the bottom plate 70 via a movable plate 42 (not shown). The placed sheet S has its side end surface in contact with the pair of side edge regulating plates 71, 71 to regulate the placement position, and its rear end surface in contact with the rear end regulating plate 75 to regulate the placement position. . As a result, the sheet S is held in a stable state at a fixed position on the paper feed tray 41.

  When the placed sheet S is a standard size sheet S such as B5 or A4, a notch 741 is provided at a predetermined position of the regulating plate fixing member 74 corresponding to each sheet size. Thus, the side edge regulating plate 71 is fixed by engaging with the protrusion 711 provided at the end of the side edge regulating plate 71. As a result, the sheet S can be stably held at the placement position on the paper feed tray 41. The held sheet S comes into contact with the pickup roller 43 by a copy command, and is conveyed to the outside of the paper feed tray 41 by its rotational frictional force.

  FIG. 3 is a top view showing a detailed configuration of the side edge regulating plate 71. FIG. 6A is a diagram illustrating a state on one side when an irregular-size sheet S is placed on the paper feed tray 41, and FIG. 9B is a diagram illustrating a state on one side when a regular-size sheet S is placed. FIG. FIG. 4 is an explanatory diagram showing the function of the displacement detection unit 83 (displacement detection means) according to the present invention. A detection method by the displacement amount detection unit 83 in the image forming apparatus 100 will be described with reference to FIGS.

  The side edge regulating plate 71 can be translated in a direction perpendicular to the paper feeding direction using the slide shaft 78 as a guide shaft. When the sheet S is placed on the sheet feeding tray 41, the sheet S is moved in accordance with the side end surface of the sheet S. Usually, it is fixed at a fixed position (in the case of FIG. 3A) that is the same as the sheet width of the placed sheet S or larger and closest to the fixed position (in the case of FIG. 3B).

  The side edge regulating plate 71 is fitted with a rotating support shaft 712 in the vicinity of the rear end portion as viewed from the paper feeding direction, and a support shaft 81 is provided that is rotatably attached around the rotating support shaft 712. ing. The other end of the support shaft 81 is rotatably attached to a rotation support shaft 801 fitted to the auxiliary regulating plate 80. As a result, the auxiliary regulating plate 80 can move in parallel with the side edge regulating plate 71 while being supported by the support shaft 81.

  A pressing member 82 is disposed between the auxiliary regulating plate 80 and the side edge regulating plate 71. The pressing member 82 is always urged in the direction of pulling the auxiliary regulating plate 80 away from the side edge regulating plate 71, and the pressing member 82 is maintained so that the auxiliary regulating plate 80 is in contact with the side end surface of the sheet S. It gives a pressing force to. Therefore, the pressing member 82 is longer than the maximum distance among the two notch portions 741 provided adjacent to the regulating plate fixing member 74 in a state where no stress is applied.

  A displacement amount detector 83 is provided coaxially on the rotation support shaft 712 of the side edge regulating plate 71. The displacement amount detection unit 83 forms a two-stage speed-up gear train by a large gear 831 that rotates coaxially with the rotation support shaft 712 and a small gear 832 that meshes with the large gear 831. Although not shown, the rotation shaft of the small gear 832 is coaxially connected to a slider which is a variable contact point of the position sensor. When the auxiliary restriction plate 80 moves and the large gear 831 rotates, the rotation is transmitted to the small gear 832. The rotation angle is amplified by the gear ratio, converted into a voltage value by a position sensor, and the amount of displacement is detected. The position sensor can use a rotary volume whose output changes depending on the angle.

  The functional operation of the image forming apparatus of the present invention will be described below. FIG. 5 is a block diagram showing a functional configuration of the image forming apparatus 100 according to the present invention. The paper feed unit 40 is provided with a displacement amount detection unit 83, and the paper feed unit 40 that has detected that the sheet S has been set supplies the selected standard size information and the displacement amount data detected from the standard size value. It is conveyed to the paper control unit 2. The paper feed control unit 2 is provided with a size calculation control unit 84 and a storage unit 85 in which the size values of various standard sheets are stored, and the sheet size is specified by converting the displacement amount into mm units. The specified sheet size value is displayed on the display unit 86.

  For example, when a B4 standard sheet is placed on the paper feed tray 41 (see FIG. 3B), the side edge regulating plate 71 is moved along the slide shaft 78, and the sheet side end of the standard sheet is moved. 77. The position is a fixed position (referred to as a size position of the fixed sheet), and the protrusion 711 of the side edge restricting plate 71 and the notch 741 of the restricting plate fixing member 74 are engaged with each other at that position. Can be fixed. At this time, the auxiliary restricting plate 80 is integrated with the side edge restricting plate 71, and the displacement amount of the support shaft 81 from the side edge restricting plate 71 is 0. Therefore, the sheet size is the standard size stored in the storage unit 85. The sheet size value of the sheet is used and displayed on the display unit 86.

  Next, when an irregular sheet having a width slightly smaller than the regular sheet B4 is placed on the sheet feeding tray 41 (see FIG. 3A), the side edge regulating plate 71 is directly connected to the sheet side of the regular sheet. Even if it is brought into contact with the end 77, the side edge regulating plate 71 cannot be fixed to the regulating plate fixing member 74. Therefore, the side edge regulating plate 71 is fixed at a fixed position closest to the sheet side end 77 located outside. Then, the auxiliary restricting plate 80 is urged by the pressing member 82 and separated from the side edge restricting plate 71 and comes into contact with the sheet side end portion 77.

  In a state where the auxiliary regulating plate 80 regulates the side end surface of the irregular sheet, the support shaft 81 shows the value of the rotation angle t ° as the displacement amount from the side edge regulating plate 71, and this rotation angle t ° is detected as the displacement amount. After being amplified by the gear ratio of the large gear 831 and the small gear 832 of the unit 83, it is converted into an electrical displacement amount from the position sensor and sent to the size calculation control unit 84. The size calculation control unit 84 calculates the sheet size of the sheet S placed on the sheet feed tray 41 from the standard size value at the position where the side edge regulating plate 71 is fixed and the displacement amount, and converts the sheet size into mm units. It is displayed on the display unit 86.

  In the above configuration, when the displacement amount (rotation angle) of the support shaft 81 becomes large (when t ° is close to 90 degrees), the rate of change in angle with respect to the parallel movement of the auxiliary regulating plate 80 becomes small, and detection accuracy cannot be ensured. Since the case is considered, it is necessary to set the fixing position of the side edge regulating plate 71 to a position closest to the sheet side end portion 77. Further, when the displacement amount of the support shaft 81 is large, the detection accuracy can be increased by detecting the linear displacement amount instead of the rotation angle.

  The example in which the sheet size in the width direction with respect to the sheet feeding direction of the sheet S is detected has been described above. However, the sheet size in the length direction can be detected in the same manner by using the trailing edge regulating plate 75. This makes it possible to accurately detect the vertical and horizontal sheet sizes of the irregular sheet. Since its function is the same as that of the side edge regulating plate 71, its description is omitted.

  In addition, it supplements below about the effect of this invention. FIG. 6 is a graph showing a numerical value (voltage) obtained by converting a mechanical displacement amount (rotation angle) on the X axis and converting the displacement amount into an electrical displacement by a rotary volume on the Y axis. As shown in FIG. 6, when the amplification of the mechanical displacement amount is increased (in the case of the straight line 1) and when it is small (in the case of the straight line 2), when the amplification is small, the detection range of the displacement amount is widened. However, since the voltage change with respect to the mechanical displacement is small, the detection accuracy must be sacrificed.

  When the amplification is increased (in the case of the straight line 1), the voltage change with respect to the mechanical displacement amount can be increased, so that the detection accuracy per unit displacement amount can be improved, but the detectable range is narrowed. . In the present invention, the size detection means of the standard sheet can be detected with a simple configuration, and the size of the irregular sheet is calculated based on the detection means, thereby widening the detection range while maintaining high displacement detection accuracy. It is comprised as follows. Note that the same effect can be obtained by using a slide volume in addition to the rotary volume and amplifying the displacement (length).

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is a conceptual block diagram which looked at the paper feed tray from the upper surface. It is a top view which shows the detailed structure of a side edge control board. FIG. 6A is a diagram illustrating a state in which an irregular size sheet is placed on a sheet feeding tray. FIG. 6B is a diagram illustrating a state in which a standard size sheet is placed on the sheet feeding tray. It is explanatory drawing showing the function of the displacement amount detection part (displacement amount detection means) concerning this invention. 2 is a block diagram illustrating a functional configuration of the image forming apparatus according to the present invention. FIG. It is the graph which showed the numerical value which converted the mechanical displacement amount into the X-axis, and converted the displacement amount into the electrical displacement with the rotary volume to the Y-axis.

Explanation of symbols

2 Paper feed control unit 10 Automatic document feeder 20 Image reading unit 30 Image forming unit 40 Paper feed unit 41 Paper feed tray 70 Bottom plate 71 Side edge regulating plate 72 Rack gear 73 Pinion gear 74 Restricting plate fixing member 75 Rear end regulating plate 76 Rear part Restriction plate fixing member 78 Slide shaft 80 Auxiliary restriction plate 81 Support shaft 82 Press member 83 Displacement amount detection unit (displacement amount detection means)
84 Size calculation control unit (calculation means)
85 Storage means 86 Display unit 100 Image forming apparatus

Claims (5)

Fixed size value storage means for storing the size value of the fixed sheet in advance;
A displacement amount detecting means for detecting a displacement amount from a fixed position of a sheet end surface of the fixed sheet placed on the sheet feeding unit to an end surface position of the sheet placed on the sheet feeding unit;
An arithmetic means for calculating a size value of the sheet placed on the paper feeding unit based on the displacement amount and the size value of the standard sheet;
An image forming apparatus. The amount of displacement is
Amplifying a displacement amount from a fixed position of a sheet end surface of the fixed sheet placed on the sheet feeding unit to an end surface position of the sheet placed on the sheet feeding unit, and using the amplified displacement amount; The image forming apparatus according to claim 1. The displacement amount detecting means includes
A fixed sheet restricting member fixed at a fixed position on an end face of a fixed sheet placed on the paper feed unit; and an auxiliary restricting member that contacts an end face of the sheet placed on the paper feed unit, The image forming apparatus according to claim 1, wherein a displacement amount between a member and the fixed sheet regulating member is detected. The auxiliary regulating member is supported by a support shaft that is rotatably attached to one end of the fixed sheet regulating member,
The image forming apparatus according to claim 3, wherein the amount of displacement is detected by a rotation angle between the support shaft and the fixed sheet regulating member.   The image forming apparatus according to claim 4, wherein the rotation angle is amplified by a gear train, and the amount of displacement is detected by the amplified rotation angle.

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