JP2010189136A - Paper carrying device, paper carrying method and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent inconvenience of recognizing it as "a jam since a sensor does not reach" though paper is carried in the normal timing, by surely detecting the edge of the paper tip by a sensor, even when succeeding paper is stopped in response to register stopping of preceding paper, in a paper carrying device for driving a paper carrying roller by a stepping motor. <P>SOLUTION: This paper carrying device has a paper feeding-carrying means for performing paper feeding-carrying by driving force of the stepping motor, a register sensor 15 arranged in a position just before a register roller part 16, and longitudinal carrying sensors 12A, B and C arranged in a carrying passage after feeding paper. When continuously feeding the paper, when the paper is carried by ordinary carrying of the stepping motor at a distance of carrying the paper in response to through-down when stopping at least the stepping motor more than time of predicting that the longitudinal carrying sensors 12A, B and C detect the tip of the paper, detection of the longitudinal carrying sensors 12A, B and C is started before such a time or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus, a sheet conveying method, and an image forming apparatus.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, a paper conveying roller is rotated by a driving force of a stepping motor or the like, and an end face position in the paper conveying direction is detected by a sensor disposed in the paper conveying path. A technique for controlling the conveyance of paper is already known. In these, a certain virtual distance is set from the leading end in the transport direction of the paper to the downstream side in the transport direction in order to start detection by the sensor.

  For example, when a virtual distance of 30 mm is set from the leading edge of the sheet, the sensor starts to be viewed 30 mm before the next sheet is scheduled to reach the sensor. On the contrary, when the detection of the sensor is completed and a virtual distance of 50 mm is set upstream (rear) from the leading edge of the sheet, the sensor is continuously viewed until 50 mm after the next sheet is scheduled to reach the sensor. The virtual distance for detection by these sensors is set in consideration of the plus or minus variation that can be allowed for control or the like with respect to the arrival time of the aim of the paper. Therefore, if there is no problem in conveyance that causes a problem, the sheet ON is detected within the detection time of the sensor, and the sheet is conveyed without any delay. On the other hand, if the sheet does not turn on within the detection time of the sensor, it is determined that a jam has occurred and a jam has occurred. As described above, a technique that is useful for paper conveyance control and jam detection by acquiring a paper ON signal by a sensor is already known.

  As such a technique, in order to provide a control method for an image forming apparatus and an image forming apparatus capable of accurately detecting a jam when a paper conveying means for intermittent conveyance is provided, a through-up characteristic of a stepping motor, A configuration for determining the timing of jam detection according to the through-down characteristic is disclosed (for example, see Patent Document 1).

  However, in the conventional paper transport device that drives the paper transport roller with the stepping motor as described above, when the subsequent paper is stopped along with the registration stop of the preceding paper, the sensor is There is a condition that, even though the sheet is still undetected, the subsequent sheet is conveyed to the undetected sensor as the stepping motor is slewed down. As a result, under such conditions, the edge of the paper cannot be detected by the sensor, and there is a problem that the sensor does not reach the jam.

  The present invention has been made in view of the above, and in a paper transport device that drives a paper transport roller with a stepping motor, even when the subsequent paper is stopped along with the registration stop of the preceding paper, An object of the present invention is to reliably detect the leading edge of a sheet with a sensor to prevent a problem that the sheet is recognized as “jammed without reaching the sensor” even though the sheet is being conveyed at a normal timing.

  In order to solve the above-described problems and achieve the object, the present invention provides a sheet feeding / conveying unit that feeds and conveys a sheet by a driving force of a stepping motor, a registration sensor disposed immediately before a registration roller, With a transport path sensor arranged in a transport path after feeding, and at the time of continuous feeding, at least when the transport path sensor is predicted to detect the leading edge of the paper, at least when the stepping motor is stopped through. And a paper transport control means for starting detection of the transport path sensor before the time required for transporting the paper by the normal transport of the stepping motor.

  According to the present invention, in a paper transport device that drives a paper transport roller with a stepping motor, the edge of the leading edge of the succeeding paper is detected by the transport path sensor even when the succeeding paper is stopped as the registration of the preceding paper is stopped. By reliably detecting the error, it is possible to prevent a problem that the paper is recognized as “jammed without reaching the sensor” even though the continuous paper is being conveyed at a normal timing.

FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus equipped with a paper transport system according to this embodiment. FIG. 2 is an explanatory diagram showing a paper feed / conveyance path from the third-stage paper feed tray to the registration roller portion in FIG. FIG. 3 is a block diagram showing the control configuration of the paper feed / conveyance system according to this embodiment. FIG. 4 is a flowchart showing an operation example (part 1) of the paper feed conveyance control according to this embodiment. FIG. 5 is a flowchart showing an operation example (No. 2) of the paper feed conveyance control of this embodiment. FIG. 6 is a timing chart showing an operation example (part 1) of the paper feed conveyance control of FIG. FIG. 7 is a flowchart showing an example of the operation of conventional paper feed control. FIG. 8 is a timing chart showing an operation example of the paper feed conveyance control of FIG.

  Exemplary embodiments of a sheet conveying apparatus, a sheet conveying method, and an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus equipped with a paper transport system according to this embodiment. In FIG. 1, reference numeral 1 denotes an image forming apparatus such as a copying machine, reference numeral 2 denotes a paper feeding device, reference numeral 3 denotes a paper stacking unit (paper feeding tray) that accommodates a plurality of sheets, and reference numeral 4 denotes a paper feeding / conveying target. Paper, reference numeral 5 denotes an FRR paper feeding unit using the FRR paper feeding method, reference numeral 6 denotes a vertical conveyance unit (conveyance path) between the paper feeding and the relay rollers, reference numeral 7 denotes a pickup roller for sending out the paper, and reference numeral 8 denotes one sheet at a time. Feed roller for feeding paper, reference numeral 9 is a reverse roller that rotates forward / reversely and has a double feed prevention function, reference numeral 10 is a paper feed sensor that detects the paper immediately after feeding, and reference numeral 11 is vertical transport of the vertical transport unit 6 A roller 12 is a vertical conveyance sensor that is turned on when a sheet in the vertical conveyance unit 6 is detected. As the above sensor, for example, an optical sensor such as a reflective photo interrupter in which a light emitting element and a light receiving element are integrated is used.

  In FIG. 1, reference numeral 13 denotes a relay roller that conveys the paper to the registration roller unit 16, reference numeral 14 denotes a relay sensor that detects the paper that has reached the relay roller 13, and reference numeral 15 denotes the registration roller unit 16. A registration sensor that is disposed immediately before and detects the leading edge of the paper, 16 is a registration roller unit that transports the paper in timing with the image on the photoconductor 18, and 17 is an image that transfers the image on the photoconductor 18 to the paper. Reference numeral 18 denotes a photosensitive member that forms an electrostatic latent image. In FIG. 1, an image is formed by electrophotography, and other necessary mechanisms are omitted.

  The FRR paper feeding method is an abbreviation of Feed River Roller, and includes a pickup roller 7, a feed roller 8, a torque limiter, and a reverse roller 9 that rotates forward (paper feeding direction) / reversely rotates (return direction). This is a paper feeding method having a function of preventing a multi-sheet feed. That is, in FRR paper feeding, the feed roller 8 and the reverse roller 9 are usually moved in the paper feeding direction, but when two or more sheets enter the nip portion of both rollers, the reverse roller 9 rotates in the reverse direction. Thus, the paper feeding method has a mechanism for returning two or more sheets. Each roller has a surface layer portion made of a rubber material having a high friction coefficient and high durability.

  An image forming apparatus 1 shown in FIG. 1 has a three-stage sheet stacking unit 3 below the image forming unit. In this embodiment, the case where paper is fed from the third-stage paper feed portion will be described as an example. The paper 4 stacked on the third-stage paper stacking section (paper feed tray) 3 reaches the registration roller section 16 via the third-stage FRR paper feeding section 5 and the transport section 6 and temporarily stops. When the registration roller unit 6 stops, the sheet stops at a slightly overfeed state at the nip portion, and after a predetermined registration adjustment operation (positioning with the image on the photoconductor 18 and skew correction), the registration roller is moved. The ra unit 16 is restarted and transported again. Thereafter, the toner image is transferred to the paper 4, and after being fixed by the action of heat and pressure, the paper 4 is discharged out of the apparatus.

  Hereinafter, the sheet conveyance in the “paper feeding to conveyance” unit will be described in detail. FIG. 2 is an explanatory diagram showing a paper feed / conveyance path from the third-stage paper feed tray 3 to the registration roller unit 16 in FIG. 1, and the first-stage and second-stage configurations are omitted. In FIG. 2, C is added to the end of the code for the element in the third stage, and A is added to the first stage and B is added to the second stage. 2, reference numeral 10 </ b> C is a paper feed sensor, reference numeral 20 </ b> C is a stepping motor, reference numeral 21 </ b> C is a solenoid for separating (depressurizing) the reverse roller 9 from the feed roller 8, and reference numeral 22 </ b> C is a bottom plate of the paper feed tray 3. A bottom plate raising motor for ascending, reference numeral 23C is a high sensor for detecting the position (paper surface position) of the pickup roller 7, and reference numeral 24C is a solenoid for separating the pickup roller 7 from the paper surface.

  FIG. 3 is a block diagram showing the control configuration of the paper feed / conveyance system described above. As shown in the figure, the image forming apparatus 1 is comprehensively controlled by the system controller 30. The system controller 30 is constituted by a microcomputer system having a CPU, ROM, RAM, timer, and the like, and the CPU executes control of sheet feeding and conveyance described later according to a program stored in the ROM.

  In FIG. 3, the stepping motor at each stage is referred to as each stage SPM, and each stage SPM is driven by a driver in accordance with a signal from the system controller 30. Reference numeral 20D denotes a double-sided SPM (stepping motor) for double-sided conveyance. In FIG. R is an abbreviation for a pickup roller, R and R are reverse rollers, and SOL is a solenoid.

  As shown in FIGS. 2 and 3, the pickup roller 7 is provided with a mechanism by solenoids 24 </ b> A, B, and C at each stage for separating the pickup roller 7 from the paper surface after the feeding operation to the feed roller 8. Further, the reverse roller 9 is provided with a mechanism by solenoids 21A, 21B, and 21C at each stage for releasing pressure after separation and conveyance and preventing dragging of the lower sheet due to double feeding of sheets. The pickup roller 7 is provided with high sensors 23A, B, and C for making the paper surface heights of the bottom plate raising motors 22A, 22B, and 22C constant (feeding pressure constant). It has been.

  Here, the operation of the conventional paper feed control will be described with reference to the flowchart shown in FIG. 7 and the timing chart shown in FIG. In addition, about the apparatus structure here, the structure of FIGS. 1-3 is referred. The flowchart of FIG. 7 shows a case where the registration stop by the preceding paper enters between “ON position of the third-stage paper feed sensor 10C and ON of the third-stage vertical conveyance sensor 12C”.

  In FIG. 7, the upper surface of the sheet bundle is kept at a predetermined position by the ON-OFF operation of the third-stage bottom plate raising motor 22C (step S1). The next feed of the third stage is started by using the start signal for the image forming apparatus 1 or the removal of the third-stage sheet feed sensor 10C at the rear end of the preceding sheet as a trigger (step S2). Subsequently, the stepping motor 20C in the paper feed stage is energized with a start signal for the image forming apparatus 1 or the removal of the paper feed sensor 10C at the trailing edge of the preceding paper as a trigger (through if there is a preceding paper) Excitation after down). At the same time, the pickup roller solenoid 24C and the reverse roller solenoid 21C in the paper feed stage are also ON-controlled (step S3). Thereafter, at a predetermined timing, the third stepping motor 20C rotates CW (clockwise: clockwise), and the first and second stepping motors (20A, 20B) rotate CCW (counterclockwise: counterclockwise). (Step S4). Subsequently, the third stage paper feed sensor 10C provided immediately after the feed roller 8 is turned on at the front end of the paper 4 (step S5) as a trigger, and the third stage pickup roller solenoid 24C is turned off. (Step S6). Here, if there is a registration stop due to the preceding paper, all the motors are stopped simultaneously (step S7). In this case, the motor starts through-down and stops after completion of the through-down. After the start of through-down, detection of unreached jam at the third stage vertical conveyance sensor 12C is started (step S8). Thereafter, the sheet is conveyed by through-down, and the third-stage vertical conveyance sensor 12C is turned ON (step S9). At this time, the through-down of the stepping motor 20C is completed and stopped (step S10). As described above, the leading edge of the succeeding paper may exceed the third-stage vertical conveyance sensor 12C during the through-down for stopping. Thereafter, the resist restarts (step S11). If the registration stops before the third-stage vertical conveyance sensor 12C is turned ON, the system controller cannot detect ON of the third-stage vertical conveyance sensor 12C during the registration stop period. For this reason, it is determined that the paper has not come, and the jam of the stepping motor is timed out (step S12).

  Further, in the conventional control operation shown in FIGS. 7 and 8, the registration stop period is entered before the start of detection even though the sheet is normally conveyed in step S9 in FIG. Therefore, ON of the third-stage vertical conveyance sensor 12C could not be recognized. In step S9, since the system controller does not recognize that the third-stage vertical conveyance sensor 12C is ON, the system controller tries to send it to the third-stage vertical conveyance sensor 12C by CW rotation. In step S12, since the leading edge of the sheet cannot be detected, a predetermined time-out occurs. In this way, in the image forming apparatus such as a copying machine, when the succeeding sheet is stopped along with the registration stop of the preceding sheet, the succeeding sheet is moved to the stepping motor even though the sensor is not yet detected. As a result, there is a condition that the sheet is transported to the undetected sensor as a result of the through-down, and as a result, the sensor cannot detect the edge of the leading edge of the succeeding paper, and the sensor does not reach the jam. There was a problem that would occur.

  FIG. 4 is a flowchart showing an operation example (part 1) of the paper feed conveyance control according to this embodiment. FIG. 6 is a timing chart showing an operation example (part 1) of the paper feed conveyance control of FIG. The timing chart shown in FIG. 6 is particularly characterized by the detection start timing of the third stage vertical conveyance sensor 12C. The operation shown in this flowchart is executed by the system controller 30 in an integrated manner. FIG. 4 shows an example in which the registration roller portion 16 is stopped by the preceding paper between “ON position of the third-stage sheet feed sensor 10C and ON of the third-stage vertical conveyance sensor 12C”.

  In FIG. 4, first, a predetermined number of papers 4 to be fed are placed on the bottom plate provided in the third-stage paper feed tray 3 and set in the paper feeder 2. The sheet 4 is lifted by the third-stage bottom plate raising motor 22C so that the upper surface position is substantially constant (the position of the pickup roller 7 is detected by the high sensor 23C) (step S101). The next feed of the third stage is started by using the start signal for the image forming apparatus 1 or the removal of the third-stage sheet feed sensor 10C at the trailing edge of the preceding sheet as a trigger (step S102). In the case of this example, each conveyance roller is driven by one stepping motor per sheet feed stage, and the roller to be rotationally driven is switched as follows according to the rotation direction of the stepping motor and a drive system (not shown).

  When the third stage stepping motor 20C rotates CW (clockwise), the third stage pickup roller 7, the feed roller 8, and the vertical conveyance roller 11 rotate forward in the paper conveyance direction, and the third stage reverse The roller 9 rotates in the reverse direction in the paper return direction. When the third stepping motor 20C rotates CCW (counterclockwise: counterclockwise), the third vertical transport roller 11 rotates forward in the paper transport direction, and the third reverse roller 9 returns the paper 4. Reverse rotation in direction.

  The stepping motor 20C in the paper feed stage is energized to be triggered by the start signal for the image forming apparatus 1 or the removal of the paper feed sensor 10C at the trailing edge of the preceding paper. (If there is a preceding sheet, the stepping motor 20C in the third stage is excited after the through-down). At the same time, the pickup roller solenoid 24C and the reverse roller solenoid 21C in the sheet feeding stage are also ON-controlled (step S103).

  The pickup roller 7 is pressed against / separated from the sheet bundle 4 by turning on / off the pickup roller solenoid 24C. Further, the reverse roller 9 is brought into pressure contact / separation (depressurization) with respect to the feed roller 8 by turning ON / OFF the reverse roller solenoid 21C. Thereafter, at a predetermined timing, the third stepping motor 20C rotates CW, and the first and second step motors (20A, 20B) rotate CCW (step S104).

  As described above, the pickup roller 7 in contact with the paper 4 sends out the paper 4 from the paper feed tray 3. Next, the paper 4 is conveyed to the feed roller 8 and the reverse roller 9 where it is separated into one sheet. Thereafter, the third stage paper feed sensor 10C provided immediately after the feed roller 8 is turned on at the leading edge of the paper 4 (step S105), and the third stage pickup roller solenoid 24C is turned off. (Step S106). Further, the detection of an unreached jam at the third stage vertical conveyance sensor 12C downstream in the conveyance direction is also started using the ON of the third stage paper feed sensor 10C as a trigger (step S107).

  Specifically, based on the distance “from the ON position of the third-stage sheet feed sensor 10C to the third-stage vertical conveyance sensor 12C being turned on” by the system controller, the ON prediction of the third-stage vertical conveyance sensor 12C is performed. The detection of the state of the vertical conveyance sensor 12C at the third stage starts a certain distance before time. In this example, with respect to the predicted ON time of the third stage vertical conveyance sensor 12C, the distance that the sheet C is conveyed in accordance with the through-down of the stepping motor is converted into the time required for normal conveyance, 3 The ON detection start position of the stage vertical conveyance sensor 12C is advanced. Since the third-stage paper feed sensor 10C and the third-stage vertical conveyance sensor 12C are sensors that are turned on when a sheet is detected, this is based on the estimated time when the leading edge of the sheet is detected by the third-stage vertical conveyance sensor 12C. In other words, the ON detection start position of the third-stage vertical conveyance sensor 12C is advanced by an amount corresponding to the time required for normal conveyance when the distance that the sheet C is conveyed in accordance with the through-down of the stepping motor.

  As described above, after the detection is started, when there is a preceding sheet, all the motors are stopped at a predetermined timing. Thereby, the gap between the preceding sheets is adjusted (step S108). After all the motors are stopped, the leading edge of the sheet passes through the third-stage vertical conveyance sensor with the through-down, and the third-stage vertical conveyance sensor 12C is turned on (step S109). Since the detection has already started, the system controller can recognize ON of the third-stage vertical conveyance sensor 12C even during the resist stop period. Thereafter, the through-down of the third stepping motor 20C is completed (step S110). After the desired paper gap is obtained, the third stepping motor 20C is rotated CCW and the first and second stepping motors 20A, B are CCW ON (step S111).

  FIG. 5 is a flowchart showing an operation example (No. 2) of the paper feed conveyance control of this embodiment. FIG. 5 shows an example in which the registration roller unit 16 is not stopped by the preceding paper between “ON position of the third stage paper feed sensor 10 and ON of the third stage vertical conveyance sensor 12 </ b> C”. The operation from step S121 to step S127 in FIG. 5 is the same as step S107 in the flowchart shown in FIG. Therefore, the redundant description is omitted here, and different operations will be described.

  After step S127 is completed, the sheet is conveyed and the third-stage vertical conveyance sensor 12C is turned on (step S128). Thereafter, only the third stepping motor 20C is turned OFF in order to obtain a predetermined sheet interval (step S129). Then, the sheet 4 is conveyed by the through-down amount of the third stepping motor 20C (step S130), and after obtaining a desired sheet space, the third stepping motor 20C is rotated CCW (step S131). After that, the sheet is conveyed to the registration roller unit 16 through the upper vertical conveyance roller 11 and the relay roller 13 to perform the registration process.

  By the way, most recent image forming apparatuses have a plurality of paper feed stages, and the conveyance direction length of the paper 4 corresponds to the irregular paper (in this example, the irregular paper between 139.7 mm and 432 mm). Is supported). As a result, there is a case where the registration roller unit 16 stops due to the preceding paper at the timing just before the expected “ON timing of the third-stage vertical conveyance sensor 12C”.

  On the other hand, in this embodiment, the distance at which the sheet C is conveyed at least with the through-down of the stepping motor is converted into time with respect to the predicted ON time of the third stage vertical conveyance sensor 12C. Since the ON detection start position of the third-stage vertical conveyance sensor 12C is advanced earlier, the third-stage vertical conveyance sensor 12C is surely in the ON detection waiting state before the stepping motor 20C enters through-down. Yes. That is, even when the registration roller unit 16 enters the stop state, “the detection itself continues, that is, the ON detection wait state”.

  As in the prior art described above, “the succeeding sheet 4 is in the undetected state as the stepping motor 20C is slewed down even though the vertical conveyance sensor 12 is still undetected. As a result, it is possible to reliably prevent the problem that the leading edge of the succeeding paper cannot be detected by the sensor and the sensor does not reach the jam.

  In addition, the “distance that the paper 4 is transported in accordance with the through-down of the stepping motor 20C” hardly changes depending on the paper size, so that the transport control is complicated by setting a constant value regardless of the paper size. And can be controlled.

  In this embodiment, the paper feeding / conveying from the third stage has been described as an example. However, if the length of the paper feeding direction or the paper feeding stage is different, a malfunction may occur in other stages. Needless to say, it is better to use the same control. In this example, the case where there is one conveyance motor per stage has been described as an example. However, it goes without saying that the present invention can also be applied to a case where a plurality of conveyance motors per sheet feeding stage are provided.

  Therefore, according to the above-described embodiment, the sheet conveying roller is rotated by the driving force of the stepping motor, and the sheet conveying direction end face position is detected by the sensor disposed in the sheet conveying path to control the sheet conveying. In the paper transport device to be used, the paper is transported at least as the stepping motor slews down the detection start position of the sensor set downstream in the transport direction from the front end in the transport direction of the paper from the predicted detection timing of the front end of the paper In the paper transport device that drives the paper transport roller with a stepping motor, the following paper is stopped when the preceding paper is stopped. However, by detecting the leading edge of the paper with a sensor, the paper is being transported at a normal timing. It is possible to prevent the problem that would recognize that not reach the sensor jam ".

  As described above, the sheet conveying apparatus, the sheet conveying method, and the image forming apparatus according to the present invention are useful for image forming apparatuses such as copying machines and printers, feeder apparatuses that convey and process various sheets, and in particular, stepping motors. It is suitable for devices and systems that drive and control paper feed rollers and transport rollers.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper feeder 3 Paper feed tray 4 Paper 5 FRR paper feed part 7 Pickup roller 8 Feed roller 9 Reverse roller 10A, B, C Paper feed sensor 12A, B, C Vertical conveyance sensor 14 Relay sensor 15 Registration sensor 16 Registration roller section 20C Stepping motor 30 System controller

JP 2007-54962 A

Claims (5)

A paper feeding and conveying means for feeding and conveying the paper by the driving force of the stepping motor;
A registration sensor placed in front of the registration roller;
A transport path sensor arranged in the transport path after feeding,
During the continuous feeding, the normal conveyance of the stepping motor is equal to or more than the distance at which the paper is conveyed with the through-down when the stepping motor is stopped than when the conveyance path sensor is predicted to detect the leading edge of the paper. Paper transport control means for starting detection of the transport path sensor before the time taken when transported by
A sheet conveying apparatus comprising:   2. The paper conveyance control unit performs a detection start position by the conveyance path sensor set at a downstream side of a conveyance direction from a leading end portion in a conveyance direction of a sheet with a constant value regardless of a sheet size. The paper transport device described in 1. At least a sheet feeding and conveying unit that feeds and conveys the sheet by the driving force of the stepping motor; a registration sensor that is disposed immediately before the registration roller; and a conveyance path sensor that is disposed in the conveyance path after feeding. A paper transport method for a paper transport device, comprising:
During the continuous feeding, the normal conveyance of the stepping motor is equal to or more than the distance at which the paper is conveyed with the through-down when the stepping motor is stopped than when the conveyance path sensor is predicted to detect the leading edge of the paper. A paper conveyance method characterized by controlling paper feed conveyance so that the detection of the conveyance path sensor is started at least before the time required for conveyance by (1).   4. The paper transport method according to claim 3, wherein a detection start position by the transport path sensor set downstream of the front end of the paper transport direction is set to a constant value regardless of the paper size. .   An image forming apparatus comprising the sheet conveying device according to claim 1.

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