JP2007161383A - Image recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a constitution capable of surely separating paper sheets even in a state that double feed caused by burrs and bite-in at the tip of a paper sheet and the attraction of the paper sheets to each other by static electricity easily occurs in a paper feeding device for feeding the stacked paper sheets to a succeeding process by taking only one sheet from the top of the stacked paper sheets by using an inclined surface. <P>SOLUTION: When starting paper feeding, the top-positioned paper sheet is vibrated forward and backward in the paper sheet conveying direction in relation to the following paper sheet so as to separate the paper sheets adhered to each other by burrs and bite-in, and thereafter, paper feeding operation is started. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a paper feed mechanism used in an image recording apparatus such as an ink jet printer, a copying machine, or a facsimile.

  2. Description of the Related Art Conventionally, recording apparatuses such as printers, copiers, and facsimiles have a paper feed mechanism that supplies paper to a normal image recording unit. As such a sheet feeding mechanism, for example, a slope member is provided at the downstream end of the sheet stacking direction of the sheet stacking unit, and the sheet is brought into contact with the sheet fed by the sheet feeding unit by the slope member. There is a configuration that separates them one by one.

  2 and 3 show a schematic configuration of a conventional paper feeding apparatus 200 that uses a method of separating sheets by such a slope member. 2 and 3, reference numeral 201 denotes a paper cassette main body, 202 is a separation plate, 203 is paper, 204 cassette lid, 205 is a swing arm, 206 is paper feed gear, 207 is belt, 208 paper feed pulley, 209 Is a paper feed roller. As shown in FIG. 2, sheets 203 are stacked on the sheet feeding cassette 201, and a swing arm 205 is positioned above the sheets 203. Further, the sheet 203 is covered with a cassette lid 204 so that foreign matter does not adhere to the sheet 203 on the sheet feeding cassette 201. As shown in FIG. 3, the swing arm 205 holds a paper feed roller 209 connected to the paper feed gear 206, belt 207, paper feed pulley 208 and the like via a shaft and a gear. When the paper feed gear is rotated by a drive mechanism (not shown), the paper feed roller 209 is rotated to convey the paper 203 in the direction of the arrow in FIG. The conveyed sheet 203 is pressed against a separation plate 202 provided on the downstream side in the sheet conveying direction. At this time, due to the frictional force relationship between the separation plate 202 and the sheet 203, the sheets 203 are separated one by one, and only the uppermost sheet 203 is conveyed to an image recording unit (not shown). In order to avoid the problem of skewing of paper during paper feeding, a plurality of paper feed rollers are provided in the direction perpendicular to the paper transport direction to suppress variations in paper transport force in the paper width direction and to the side edge of the paper. It is effective to arrange the side guides positioned as far as possible to guide the paper movement.

In the sheet feeding device using such a slope member, there are ones in which the slope member surface is configured by a curved surface (for example, refer to Patent Document 1), and those in which the surface roughness of the slope member is changed (for example, Patent Document 1). 2).
JP 2002-249249 A JP 2003-81473 A

  However, in the paper feeding device using the method of separating the sheet by the inclined member as described above, when burrs or paper entanglement occurs at the leading edge of the paper due to the cutting state or packaging state of the paper, FIG. As shown in FIG. 4, when the uppermost paper is conveyed by the rotation of the paper feed roller 209, the uppermost paper is caught by the portion where the next paper is caught as shown in part A in FIG. It starts to move. Even if the leading edge of the sheet comes into contact with the separating plate 202 at this time, the friction force by the separating plate 202 cannot be applied to the leading edge of the uppermost sheet due to such burrs or entrainment. The upper sheet cannot be separated and the sheets are double fed. Also, not only burrs and entanglements, but also when sheets are adsorbed by static electricity, there is a problem of double feeding if the electrostatic adsorption force is larger than the frictional force applied from the separation plate 202.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to realize a configuration capable of reliably separating sheets even in a sheet state in which double feeding is likely to occur, such as burrs or entanglements at the leading end of the sheet, or adsorption between sheets due to static electricity. To do.

In order to solve the above problems,
(1) A plurality of paper feed rollers that can be driven in both forward and reverse directions are arranged in a direction perpendicular to the paper transport direction.

(2) The feed roller in contact with the top sheet at the start of feeding is driven in both forward and reverse directions for a short time. (3) Due to the movement of the feed roller, the top sheet is Vibrates in the upstream / downstream direction with respect to the sheet transport direction.

  (4) By the operation of (3), the leading edge of the paper that is in close contact due to burrs, entrainment, or static electricity is separated.

  With such a configuration, occurrence of double feeding can be prevented.

  In the paper feeding device of the present invention, the top paper is vibrated with respect to the next paper at the start of paper feeding, and the paper feeding operation is started after separating the closely contacted paper by burr or wrapping or the like to prevent the occurrence of double feeding. I can do it.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

(First embodiment)
Hereinafter, an ink jet printer using the paper feed mechanism according to the present invention will be described in detail. FIG. 5 is a layout diagram of the ink jet printer according to the present invention. The ink jet printer 1 includes a paper feeding device 100, an exterior cover 2, an outer guide 3a, an inner guide 3b, a registration roller pair 4, a print head 5, a platen 6, a paper discharge roller pair 7, a paper discharge tray 8, and a paper detection sensor. 9 etc.

  The paper feeding device 100 includes a paper feeding cassette 110 that is a paper stacking means for stacking paper, a swing arm 120 that is a paper supply means, and a separating means that separates only the uppermost paper when a plurality of paper is conveyed. And a motor and gear train (not shown) for driving the swing arm 120, the registration roller pair 4, the paper discharge roller pair 7, and the like. Further, the paper feed cassette 110 is detachable from the paper feed device 100, and is configured to be set in the paper feed mechanism 100 after the sheets are stacked by the user.

  The exterior cover 2 is formed so as to cover the entire inkjet printer 1 including the paper feeding device 100. The outer guide 3a is a guide member when the sheet conveyed from the sheet feeding device 100 is conveyed to the next process. In the case of the present embodiment, the conveyed paper is so-called U-turned and conveyed to the print head 5 which is an image forming unit, but the outer conveyance path through which the paper passes is regulated in the U-turn, and the next process Guide you smoothly. The inner guide 3b, like the outer guide 3a, regulates the inner conveyance path through which the paper passes during the U-turn and smoothly guides to the next process.

  The registration roller pair 4 includes a driving side LF roller 4a and a driven side pinch roller 4b. The LF roller 4a is driven to convey a required amount of paper by a motor and gear train (not shown). The pinch roller 4b is biased toward the LF roller 4a by a biasing means (not shown). By nipping and conveying the sheet to the nip of the registration roller pair 4, the sheet can be conveyed in the direction of the print head 5 which is an image forming unit. The registration roller pair 4 during image formation is intermittently conveyed by a predetermined amount by the motor (not shown) described above.

  Further, the registration roller pair 4 corrects the skew of the sheet by abutting the leading end of the sheet conveyed from the upstream side by the conveyance from the sheet feeding device 100 to the nip in the stopped state. In addition, after skew correction by abutment, the sheet is conveyed with an accurate feed amount by intermittent driving during image formation by the print head 5. Since the feed amount during intermittent conveyance of paper by the registration roller pair 4 has a great influence on the quality of the image, the registration roller pair 4 usually has a large conveyance force in the conveyance means of the ink jet printer. Accurate drive control is performed.

  The print head 5 is configured to form an image by ejecting ink droplets from a surface facing the print surface of the paper while reciprocating in the direction orthogonal to the conveyance direction, that is, the paper width direction, by a carriage (not shown). The print head 5 is also configured so that ink of a necessary color and amount is appropriately supplied by an ink supply means (not shown).

  The platen 6 is configured to appropriately maintain the flatness of the printing surface of the paper, the clearance with the print head 5, and the parallelism when an image is printed by the print head 5. The reason why the positional relationship between the print head 5 and the sheet needs to be maintained in this way is to increase the landing position accuracy of the ink droplets ejected from the print head 5.

  It is further preferable that a sheet suction unit (not shown) is separately provided and the sheet is brought into close contact with the platen 6 by sucking the sheet onto the conveying surface of the platen 6 so as to maintain the above-described flatness, clearance, and parallelism. It becomes.

  The paper discharge roller pair 7 includes a drive-side paper discharge roller 7a and a driven-side spur 7b. The paper is sandwiched and conveyed by a motor (not shown) with a conveyance force weaker than that of the registration roller pair 4 described above. It is configured. The paper discharge roller 7a is formed of a high friction member such as rubber, for example, contacts the non-printing surface of the image-formed paper, and conveys the paper to the paper discharge tray 8 described later by the action of the spur 7b. Since the spur 7b must be brought into direct contact with the printing surface of the sheet immediately after printing, it is necessary to reduce the contact area as much as possible. Therefore, in this embodiment, the spur 7b has a shape in which a large number of needle-like protrusions are formed on the outer peripheral portion thereof.

  The paper discharge tray 8 is configured so that a predetermined amount of printed paper discharged from the paper discharge roller pair 7 can be stacked.

  The outer guide 3 a is provided with a paper detection sensor 9 for detecting the leading edge of the paper conveyed from the paper feeding device 100.

  Next, the mechanism and operation of the sheet feeding device 100 in this embodiment will be described in more detail.

  FIG. 6 is a detailed view of the paper feed cassette 110. The sheet cassette 110 includes a cassette body 111, a rear end guide 112, a side guide 113, a sheet 114, and a separation plate 130. In the present embodiment, when dealing with various paper sizes, a method based on either one of the side edges of the paper is adopted, that is, the paper 114 loaded on the paper feed cassette 110 is not in the cassette main body 111. The cassette body wall surface 111a is used as a reference surface, one lateral end of the paper 114 is abutted, the rear end is regulated by the rear end guide 112, and the lateral end surface opposite to the reference side is regulated by the side guide 113. Is done. At this time, the side guide 113 guides the vicinity of the leading end of the sheet 114 in order to suppress the occurrence of skew during conveyance of the sheet 114. Further, when stacking a sheet having a different size from the sheet 114 in the figure, the rear end guide 112 and the side guide 113 are moved in the directions of the arrows along the grooves 111b to 111c of the cassette body 111, respectively. It has become. Here, the paper 114 in FIG. 6 represents the paper 114 of the minimum size, and when using a paper 114 of a larger size, the side guide is moved toward the left side in the figure with respect to the paper 114. The separation plate 130 separates the paper 114 conveyed by a paper feed roller held by a swing arm, which will be described later, one by one due to the frictional force relationship with the paper 114. In this embodiment, a plurality of separation plates 130 are provided to cope with various paper sizes. In this embodiment, the separation plate 130 is attached to the cassette body 110, but the present invention is not necessarily limited thereto.

Next, a basic operation of the swing arm 120 will be described below with reference to an arrow view from the lateral direction of the swing arm 120 shown in FIG. The symbols in FIG. 6 are the swing arm stay 121, the paper feed roller 122, the paper feed gear 123, the belt 124, the paper feed pulley 125, the pressure arm 126, and the drive gear 10, a ₁ are the rotation center of the swing arm stay 121. a ₂ is the paper feed roller rotation center, S ₁ is the paper top surface.

Swing arm stay 121 is a pendulum-like member supported on a frame by rotation around a ₁ not swingably shown, rotatably supports a feed roller 122 to the pendulum of the tip. More specifically, the rotational center a ₁ of the swing arm stay 121 is rotatably supported on the above frame (not shown) in and feed direction of the upstream side of the rotation center a ₂ above the paper feed roller 122 to be described later .

Paper feed roller 122 is supported by the center of rotation a ₂ to swing the tip of the swing arm stay 121, the surface has a high coefficient of friction in a cylindrical shape. The paper feed roller 122 is configured to always follow and contact the uppermost sheet S ₁ of the sheet S by swinging of the swing arm stay 121. Further, integral gear unit and the center of rotation a ₂ coaxially and feed roller 122 is formed, connected feed roller to the gear portion of the paper feed roller 122 rotates via a gear unit (not shown) of the paper feed pulley 125 122 is driven to rotate and conveys the uppermost sheet S ₁ of the sheet 114 held in the cassette 110 in the downstream direction.

Sheet feeding gear 123 is rotatably supported coaxially to the rotational center a ₁ of the swing arm stay 121. When the paper feed gear 123 is rotationally driven by a final drive gear 10 driven by a motor (not shown), a belt 124 described later is provided by a pulley portion 123 a of the paper feed gear 123 formed integrally with the paper feed gear 123. It is comprised so that it may drive.

  The belt 124 is connected to a pulley portion 123a formed integrally with the paper feed gear 123 described above and a paper feed pulley 125 described later. The gear part of the paper feed roller 122 is driven.

  The paper feed pulley 125 is connected to the pulley portion 123a of the paper feed gear 123 by the belt 124 described above, and as described above, the paper feed roller 122 is formed by the gear portion integrally formed with the paper feed pulley 125. Drive the gear part. With these configurations, the paper feed roller 122 is driven in the paper feed direction by the drive gear 10.

With the above-described configuration, the swing arm stay 121 swings in the B direction by its own weight and / or friction torque associated with driving described later, and follows the uppermost sheet S ₁ of the stacked sheets S to supply it. The paper roller 122 is configured to apply a load in the direction of the paper feeding pressure N with respect to the uppermost paper S ₁ . When the drive gear 10 rotates in the CCW direction in FIG. 7, the swing arm 120 itself swings in the B direction due to friction torque or the like derived from the drive mechanism in the swing arm stay 121, and It is configured to apply a load in the paper feed pressure N direction by biting into the paper S ₁ . If the sheet feeding roller 122 rotates in the sheet feeding direction due to these, the sheet feeding pressure N increases and the sheet feeding force _Fp is generated. Here, if the friction coefficient between the surface of the sheet feeding roller and the sheet S is the friction coefficient μ ₁ , the sheet feeding force F _p is expressed as follows.

F _p = μ ₁ × N (Equation 1)
Thus the swing arm 120 provides a feeding force F _p on the sheet S ₁ of the top surface of the loading the paper S, to convey the sheet S ₁ in the feeding direction A.

  The above is the normal operation of the swing arm 120. In addition, this embodiment has a significant feature at the start of the paper feeding operation. The details will be described below with reference to the schematic diagram of the swing arm drive system shown in FIG. 8 and the flowchart shown in FIG. 1, in addition to FIG. The symbols in FIG. 8 are 127 drive motors, 127a drive motor gears, and 128 electromagnetic clutches 129a-c are gears ac.

  When the printing operation is started in S100 of FIG. 1, the electromagnetic clutch 128 existing between the drive motor 127 and the paper feed gear 10 in FIG. 8 is turned on in S200. For this reason, the gear a129a and the gear b129b are directly connected, and the rotation of the drive motor 127 is transmitted from the drive motor gear 127a to the paper feed gear 10 through the gears a to c, and the paper feed roller 122 is rotated according to the rotation of the drive motor 127. It will be in a rotating state. At the same time as the electromagnetic clutch 128 is turned on, the pressurizing arm 126 in FIG. 7 moves in the direction of arrow C in the figure, and the rotational operation of the swing arm 120 is restricted.

Here, the role of the pressure arm 126 will be described below. As described above, the swing arm 120 according to the present embodiment has a configuration in which when the paper feed gear 10 rotates in the CCW direction in FIG. 7, the paper feed roller 122 bites into the paper S ₁ to generate a predetermined paper feed pressure. However, if the paper feed gear 10 is rotated in the opposite direction to the CCW in order to reverse the paper feed roller 122, the swing arm 120 is opposite to the B direction due to friction torque derived from the drive mechanism in the swing arm stay 121. The predetermined paper feeding pressure cannot be generated for the paper S ₁ . In order to prevent this problem, in this embodiment, the electromagnetic clutch 128 is turned on in S200, and the pressurizing arm 126 restricts the movement of the swing arm 120 so that the predetermined feeding is performed regardless of the rotation direction of the paper feeding roller. The paper pressure is generated.

When the sheet feeding roller 122 in the forward reverse by the forward reverse repetition of the driving motor 127 in this order S300, the uppermost sheet S ₁ of the inner sheet cassette 110 vibrates in the vertical flow direction of the sheet conveyance direction. At this time, the uppermost sheet S ₁ is repeatedly vibrated back and forth with respect to the next sheet S ₂ , thereby eliminating the adhesion of the sheet due to burrs, entanglements and static electricity. The number of vibrations at this time is incorporated in a motor control mechanism (not shown) as a set number of vibrations, which can be sufficiently eliminated from the close contact of the paper, which has been confirmed in advance through experiments or the like. When the forward / reverse rotation of the paper feeding roller for the set number of vibrations is completed, the pressure arm 126 is retracted out of the rotational operation range of the swing arm 120 so as not to disturb the operation of the swing arm 120. For this reason, the operation of the swing arm 120 is the normal operation described above.

Then paper feeding in S400 roller rotates forward, to start conveying and the uppermost sheet S ₁ to the paper conveyance direction downstream side. At this time, the rotation amount of the motor is controlled so as to give the sheet S _{1 a} conveyance amount at which the leading edge of the sheet S ₁ can reach the sheet detection sensor A. In normal operation, the sheet detection sensor detects the sheet S during the conveyance process. _{1 The} tip is detected. If the leading edge of the sheet S ₁ is detected in S500, the motor control mechanism abuts against the nip of the registration roller pair in a state where the leading edge of the sheet S ₁ is stopped in S600 so as to correct the skew of the sheet S ₁ . a predetermined conveyance amount rotates a certain time the motor so as to provide the sheet S _1.

Here when the sheet S ₁ tip registration roller reaches, at the same time the sheet S ₁ tip is nipped by the registration roller, around the sheet S ₁ rear is in the state of being nipped by the feed roller. If for sheet S ₁ by the rotation of the registration rollers while the sheet S ₁ is nipped in the paper feed roller will rotate with the feed roller also combined when start moving to the sheet conveyance direction upstream side, the electromagnetic clutch is ON, i.e. a load is applied in the opposite direction to the conveying direction to the sheet S ₁ is in a state where the paper feed roller and the motor are connected, causing deteriorating the feed accuracy of the sheet S _1. For this reason, in this embodiment, the electromagnetic clutch is turned off in S700, and the rotation of the registration roller is started in S800 after the rotation of the sheet feeding roller is not rotated and transmitted to the motor. ing. When the trailing edge of the sheet S ₁ is detected by the sheet detection sensor 9 in S900, the sheet feeding operation for the next sheet S ₂ is started. At this time, if the feeding operation to the next sheet S ₂ is started immediately after the trailing edge of the sheet S _{1 is} detected, there is a possibility that the trailing edge of the sheet S ₁ and the leading edge of the next sheet S ₂ come into contact with each other and a jam occurs. For this reason, in this embodiment, the feeding operation for the next sheet S ₂ is started after a preset time for sufficiently printing to the rear end of the sheet S ₁ has elapsed.

  On the other hand, if the leading edge of the sheet is not detected by the sheet detection sensor A in S500, the sheet is jammed in the middle of conveyance. Therefore, in S510, the sheet feeding roller is again set for a certain time to reconvey the jammed sheet. Rotate forward. In this operation, when the leading edge of the sheet is detected by the sheet detection sensor A in S520, the process proceeds to the above-described S600, but if not detected, the electromagnetic clutch is turned off in S530. If the electromagnetic clutch is in the ON state, when the user pulls the paper during the jam processing, the rotation of the paper feed roller is transmitted to the motor as described above, resulting in a very heavy load. Is done. Therefore, in this embodiment, before shifting to the jam processing mode in S540, the electromagnetic clutch is turned off in S530 so that the jam processing is performed after the rotation of the paper feed roller is not transmitted to the motor. ing.

  In the paper feeding device 100 having the above-described configuration, a configuration in which paper can be reliably separated by avoiding a paper state in which double feeding is likely to occur, such as burrs or entanglement at the leading edge of the paper, or adsorption of paper due to static electricity, is realized. can do.

(Second embodiment)
Hereinafter, an ink jet printer using the paper feed mechanism according to the present invention in the second embodiment will be described in detail. FIG. 9 is a layout diagram of the ink jet printer in the present embodiment. The difference from the first embodiment is that the paper detection sensors are provided at two locations, 9a paper detection sensor A and 9b paper detection sensor B. . The other symbols and configurations are the same as those in FIG. Details of the present embodiment will be described below with reference to flowcharts shown in FIGS.

The operation from S100 to S800 in the flowchart of FIG. 10 is the same as that of the first embodiment in this embodiment, and double feeding such as burrs or entanglement of the leading end of the sheet or adsorption of sheets due to static electricity occurs. It is configured to avoid easy paper conditions. However, the sheet S ₁ trailing edge at the sheet detecting sensor A9a in S900 in the present embodiment is detected, the electromagnetic clutch is turned ON at S1000 immediately, forward and reverse rotation of the feed roller 122 is performed in S1100, next order sheet S ₂ is driven a predetermined time motor at S1200 is conveyed. When next order sheet S ₂ tip in the motor drive at S1300 is detected by the sheet detection sensor A9a, the motor is stopped at S1400, after the electromagnetic clutch 128 is turned OFF at S1500, next order sheet S ₂ has its front end waits in a state that is between the sheet detecting sensor A9a and the paper detection sensor B9b.

If here next order sheet S ₂ tip be finished motor driving a certain time is not detected in the paper detection sensor A9a, attempts to re-feed S1310 following steps are executed. If that next order sheet S ₂ tip is not detected in the paper detection sensor A9a, it will be performed S1330 following steps jam mode.

Next, when the trailing edge of the sheet S ₁ is detected by the sheet detection sensor B9b in S1600, the sheet feeding operation for the next sheet S ₂ is started again. At this time, as in the first embodiment, when the feeding operation to the next sheet S ₂ is started immediately after the trailing edge of the sheet S _{1 is} detected, the trailing edge of the sheet S ₁ and the leading edge of the next sheet S ₂ come into contact with each other. Therefore, after a preset time has elapsed for the trailing edge of the sheet S ₁ to pass the registration roller pair 4, the process proceeds to S 400 and the sheet feeding operation for the next sheet S ₂ is started. It has become.

  By adopting such a configuration, it is possible to avoid a paper state in which double feeding is likely to occur such as burrs or entanglement at the leading edge of the paper, or adsorption of paper due to static electricity, and to realize a configuration that can reliably separate the paper. In addition, when a large amount of sheets are continuously printed, the interval between sheets can be shortened, and throughput can be improved.

Flowchart of printing operation according to the present invention Schematic diagram of conventional paper feeder Schematic diagram of the swing arm inside a conventional paper feeder Schematic diagram when double feeding occurs due to paper burrs or entrainment Schematic diagram of an ink jet printer using a paper feeding device according to the present invention. Schematic drawing Detailed view of the paper feeding cassette of the paper feeding device according to the present invention Detailed view of swing arm of sheet feeding device according to the present invention Schematic diagram of swing arm drive mechanism according to the present invention Schematic diagram of an ink jet printer using a paper feeding device according to the present invention in Example 2. Flowchart of printing operation according to the present invention in Embodiment 2

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Exterior cover 3a Outer guide 3b Inner guide 4 Registration roller pair 5 Print head 6 Platen 7 Paper discharge roller pair 8 Paper discharge tray 9 Paper detection sensor 10 Drive gear 100 Paper feed device 110 Paper feed cassette 111 Cassette main body 111a Paper Reference surface 111b Rear end guide groove 111c Side guide groove 112 Rear end guide 113 Side guide 114 Paper 120 Swing arm 121 Swing arm stay 122 Paper feed roller 123 Paper feed gear 124 Belt 125 Paper feed pulley 126 Pressure arm 127 Drive motor 127a Drive motor gear 128 Electromagnetic clutch 129a-c Gear a-c
130 separator

Claims (2)

In an image recording apparatus provided with a paper feeding mechanism for taking out only one sheet from the top surface of the stacked paper and feeding it to the next process,
Paper stacking means for stacking paper,
A paper transport means that is in contact with the uppermost surface of the stacked paper and that can transport the paper in both directions on the upstream and downstream sides of the paper transport direction;
Separating means for separating the paper conveyed by the paper conveying means into only the uppermost paper;
With
An image recording apparatus comprising: a paper feeding mechanism that performs a paper feeding operation after the uppermost paper is vibrated upstream and downstream with respect to the next paper by the paper transporting means. The image recording apparatus according to claim 1,
An image recording apparatus that performs a paper feeding operation after vibrating the next paper to the upstream and downstream sides in the paper conveyance direction during conveyance of the uppermost paper.

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