TW201339079A - Conveying device of sheet material, image-reading device, and image-forming device - Google Patents

Abstract

The present invention provides a conveying device of sheet material. Under the circumstances of reading both sides of the sheet material and driven by a single means to convey the sheet material, while suppressing the slanting movement of the sheet material, it starts conveying the second sheet material before discharging the precedent first sheet material. If the paper conveyed on the normal conveying path 130 reaches the position of the paper-discharging roll 125, then the control part can make the rotation direction of the driving means in reverse rotation direction. As a result, the paper-discharging roll 125 rotates in the reverse direction, so that the paper can be conveyed on the connection-conveying path 131. If the paper reaches the position of the pulling-out conveyance roll 114, then the control part will transmit the driving power to the pulling-out conveyance roll 114, and make the rotation direction of the driving means in positive rotation direction. If the rear end of paper passes through the position of pulling-out conveyance roll 114, then the control part will stop transmitting the driving power to the pulling-out conveyance roll 114, and transmit the driving power to the feeding roll 113.

Description

Sheet conveying device, image reading device and image forming device

The present invention relates to a sheet conveying device, an image reading device, and an image forming device.

Patent Document 1 describes an original document reading device which is constructed by using one of two conventional driving sources, thereby achieving downsizing and cost reduction.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent No. 3546822

It is an object of the present invention to enable a sheet conveying device driven by a single driving means to convey the sheet on both sides of the readable sheet, while suppressing the skew of the sheet while being positioned Before the first sheet on the front side is discharged, the subsequent conveyance of the second sheet is started.

In the sheet conveying device according to the first aspect of the invention, the first conveying path of the sheet is provided from the reading position of the supply sheet to the discharge position of the image through which the sheet can be read. a discharge position of the sheet; a second conveyance path of the sheet from the first position on the first conveyance path to In the second position, the second position is located on the upstream side of the first conveyance path in the sheet conveyance direction, and the single drive means selectively rotates in the first direction and the second direction. In the first transporting path, the first transporting roller is rotated by the driving force generated by the driving means at a position upstream of the second position in the transporting direction, and is transported. In the second conveying roller, the second conveying roller rotates by the driving force generated by the driving means to convey the sheet, and the third conveying roller is on the first conveying path. The sheet is conveyed by a driving force generated by the driving means at a position downstream of the first position in the conveying direction, and the rotating member is rotated regardless of the rotation direction of the driving means. In the transport path, the second transport roller is rotated by the sheet conveyed from the second position to the first position, and the first switching means switches and does not drive. a state of power transmission, the driving force is transmitted from the driving means to the first conveying roller, and the second switching means is switched between a state in which the driving force is not transmitted, and the driving force is transmitted from the driving means to the first a conveying roller for controlling the driving means, the first switching means, and the second switching means, wherein the control means rotates the driving means in the first direction to start conveying from the supply position In the first sheet to be fed, the first sheet passes through the position of the first conveyance roller, and the first switching means transmits the driving force to the first conveying roller. Switched to state In the first transport path, after the first sheet passes the position of the second transport roller, the second transfer means transmits the driving force to the second transport by the second switching means. When the state of the roller is not in the state of the transfer, when the first sheet is conveyed to the position of the third conveyance roller, the driving means is rotated in the second direction, and the state is changed. In the rotation direction of the third conveyance roller, the first sheet is conveyed to the position of the second conveyance roller via the second conveyance path, and the driving force is transmitted to the second conveyance roller by the second switching means. The state is switched to the state in which the transfer is performed, and the driving means is rotated in the first direction to change the rotation direction of the third conveyance roller. When the first sheet passes the position of the second conveyance roller, the above-mentioned first sheet is used. The second switching means switches from a state in which the driving force is transmitted to the second conveying roller to a state in which the transmission is not performed, and the driving force is never performed by the first switching means. The state of the first conveyance roller is switched to the state in which the transfer is performed, and the conveyance of the second sheet to be conveyed after the first sheet is started, and the second sheet is passed through the reading position until the second sheet is conveyed. The first sheet is conveyed and discharged by the third conveyance roller during the rotation period in the first direction by the driving means at the position of the third conveyance roller.

In the sheet conveying device according to the first aspect of the invention, the sheet conveying device according to the first aspect of the invention includes the roller separating means for opposing the third conveying roller and the third conveying roller Separating the opposite roller, on In the control means, when the leading end of the sheet reaches the position of the second conveying roller while the driving means is rotated in the second direction, the driving means is transmitted from the second switching means to the first (2) The state of the conveyance roller is switched to a state in which the transmission is not performed, and then the driving means is rotated in the first direction, and the third conveyance roller and the opposite roller are separated by the roller separation means.

The image reading apparatus according to the third aspect of the invention, comprising the sheet conveying device according to the first or second aspect of the invention, and the image reading device, wherein the image reading device is transported by the sheet conveying device The sheet is used to read the image.

The image forming apparatus according to the fourth aspect of the present invention, characterized in that the image reading apparatus according to the third aspect of the invention, and an image forming apparatus that reads the image read by the image reading apparatus The image is formed on a recording medium.

According to the invention of the first aspect of the invention, when the sheet conveying device driven by the single driving means conveys the sheet on both sides of the readable sheet, the sheet can be prevented from being skewed. The subsequent conveyance of the second sheet is started before the first sheet located on the front side is discharged.

According to the invention of the second aspect of the invention, the sheet can be pulled by the second conveying roller and the third conveying roller that rotate in opposite directions.

According to the invention of the third aspect of the invention, in the case where the sheet conveying device according to the first or second aspect of the invention is not provided, the image can be read in the reading direction specified for the sheet to be the original document. Direction and position adjusted The image on the formed sheet is read.

According to the invention of the fourth aspect of the invention, the image reading device according to the third aspect of the invention can be oriented in the direction of the image with respect to the reading direction specified by the sheet to be the original document. The image is formed on the recording medium in a state where the position is adjusted.

(structure)

FIG. 1 is a schematic configuration diagram of an image forming apparatus 100 including a sheet conveying device 10 according to an embodiment of the present invention as seen from the front side. Here, the front side refers to a surface on which the user operates the image forming apparatus 100 by operating means such as a touch panel and an operation key. On the other hand, the back side refers to a surface that is opposite to the front side. The image forming apparatus 100 is mainly composed of a sheet conveying device 10, a paper feeding unit 20, an image forming unit 30, and an image reading unit 40. The sheet conveying device 10 is a paper conveying device that conveys paper that has been read as a document to a reading position of the image reading unit 40 and discharges the paper after the image is read. Paper is an example of the sheet of the present invention. The paper feed unit 20 supplies the paper to the image forming position of the image forming unit 30. The image forming unit 30 forms an image on the sheet fed by the paper feed unit 20 after each step of an electrophotographic method such as charging, exposure, development, transfer, and fixing. In the present embodiment, the image forming unit 30 is a means for forming a color image, but may be a means for forming a monochrome image. The image reading unit 40 is formed to be transported to the reading position in the sheet conveying device 10 The image on the paper is read, and the reading result is supplied to a control unit (not shown). The control unit supplies the reading result to the image forming unit 30 as necessary, and the image forming unit 30 forms an image corresponding to the supplied reading result on the sheet. The image reading unit 40 is an example of the image reading means of the present invention. Further, a device including at least the sheet conveying device 10 and the image reading unit 40 is an example of the image reading device of the present invention.

The sheet conveying device 10 includes a document placing unit 11 , a discharge paper loading unit 12 , and a conveying unit 13 . The document placing unit 11 is a tray on which sheets to be read as originals are placed. The conveying unit 13 is composed of a plurality of rollers for conveying paper. The sheet conveying device 10 is detachably attached to the image reading unit 40 via an opening and closing mechanism (not shown). A slit glass 14 is embedded in a part of the surface of the sheet conveying device 10 that is in contact with the image reading unit 40. When the paper is conveyed to the slit glass 14 by the conveyance unit 13, the image reading unit 40 passes through the slit glass 14 to read an image formed on the paper. The paper imaged by the image is discharged by the transport unit 13 to the discharge paper loading unit.

The paper feed unit 20 includes a paper storage unit 21 for accommodating paper sheets and a paper feed unit 22 that transports the paper sheets stored in the paper storage unit 21 to a plurality of image forming positions of the image forming unit 30. Made up of rollers.

The image forming unit 30 forms an image by using a so-called intermediate transfer method using toners of four colors of yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit 30 includes a photoreceptor drum 31, a charger 32, an exposure device 33, a developing device 34, toner cartridges 35Y, 35M (magenta), 35C (cyan), 35K, The intermediate transfer belt 36 and the fixing device 37. Further, among the constituent elements shown in FIG. 1, a letter (Y, M, C or K) is attached to the end of the component symbol, indicating that the constituent element corresponds to one of the above four colors. These constituent elements have the same main structure and function although the colors of the toners used are different. Therefore, in the following description of these constituent elements, when it is not necessary to distinguish colors, the end of the component symbol is omitted, and these are collectively referred to as "toner cartridge 35".

The photoreceptor drum 31 is a cylindrical member in which a photoconductive film is laminated on the surface and rotated about the axis, and is an image holder that holds an electrostatic latent image formed on the surface. The charger 32 causes the photoreceptor drum 31 to have a predetermined charged potential. The exposure device 33 exposes the photoreceptor drum 31 to form an electrostatic latent image. The developing device 34 develops the electrostatic latent image and forms an image on the surface of the photoconductor drum 32 by supplying the toner to the electrostatic latent image. The toner cartridge 35 accommodates toner of various colors and supplies it to the developing device 33 as needed. The intermediate transfer belt 36 is a means for holding the toner image transferred from the photoreceptor drum 31. The intermediate transfer belt 36 is supported by a plurality of support rollers and moves around one side in the direction indicated by an arrow A1 in the drawing. The fixing device 37 fixes the image on the sheet by heating and pressurizing the sheet on which the image is transferred from the intermediate transfer belt 34. The photoreceptor drum 31, the charger 32, the exposure device 33, the developing device 34, the intermediate transfer belt 36, and the fixing device 37 function as an example of the image forming means of the present invention by the cooperation.

2 is a view showing the sheet conveying device 10 and the main body of the image forming apparatus 100. A block diagram of the hardware structure. The sheet conveying device 10 includes a control unit 101, a storage unit 102, and a communication unit 103. Each department is electrically connected by a bus bar. The control unit 101 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a time measuring unit for measuring time. The CPU controls each unit connected to the control unit 101 by executing a control program stored in the ROM or the storage unit 102. The control unit 101 is an example of the control means of the present invention. The storage unit 102 is a storage device such as a flash memory for storing, for example, a control program. The communication unit 103 communicates with the communication unit 183 of the main body of the image forming apparatus 100 under the control of the control unit 101.

The image forming apparatus 100 includes a control unit 181, a storage unit 182, a communication unit 183, a UI unit 184, and an image forming unit 30. Each part is connected by a bus bar. The control unit 181 has a CPU, a ROM, and a RAM. The CPU controls each unit connected to the control unit 181 by executing a control program stored in the ROM or the storage unit 182. The storage unit 182 is a storage device such as a hard disk for storing, for example, a control program and image data. Under the control of the control unit 181, the communication unit 183 communicates with the communication unit 103 of the sheet conveying device 10 and the communication terminal operated by the user. The UI (User Interface) unit 184 includes, for example, a touch panel or a plurality of buttons, and notifies the control unit 181 of an instruction based on the user's operation. The control unit 181 performs processing in accordance with an instruction notified by the UI unit 184. The image forming unit 30 is the same as described above, and the root is The image according to the image data is formed on the paper.

FIG. 3 is an enlarged view of the conveying unit 13 in the sheet conveying device 10 from the front side. The transport unit 13 includes a paper pull-in roller 111, a paper reading sensor 112, a feed roller 113, a pull-out transport roller 114, a paper passing sensor 116, a resist roller 117, and an image reading timing sensor 119. The output roller 121, the paper passing sensor 123, the discharge roller 125, the solenoid 127, the plurality of driven rollers 115, 118, 122, 126, the normal transport path 130, the connecting transport path 131, and the reverse Transfer path 132. The transport unit 13 has a drive mechanism for driving the rollers (not shown in FIG. 3) in addition to the plurality of rollers shown in FIG. 2, but for the sake of convenience of explanation, first, the main portion of the transport unit 13 is performed. And the description of each roller, and then explain the drive mechanism.

In the normal transport path 130, in FIG. 3, the paper is pulled from the paper roll 111, and the paper is fed through the feed roller 113, the pull-out conveyance roller 114, the resist roller 117, the slit glass 14, and the output roller 121 up to the discharge roller 125. The path when transporting to the position of each roller. On the other hand, the connection conveyance path 131 is connected to the connection portion L1 (an example of the first position) from the normal conveyance path 130 and the connection conveyance path 131 in the vicinity of the discharge roller 125, and to the pull-out conveyance roller 114. A path of the adjacent normal transport path 130 and the connection portion L2 (an example of the second position) of the connection transport path 131. In the normal conveyance path 130, the connection portion L2 is located on the upstream side of the paper conveyance direction from the connection portion L1. In the normal conveyance path 130, the reverse conveyance path 132 is located downstream of the connection portion L2 in the sheet conveyance direction, and is reversely moved. In the conveyance path 132, the conveyance direction of a paper is reversed. In the following description, when it is simply referred to as "paper conveyance direction", it means a direction in which the paper is conveyed toward the discharge roller 125 on the normal conveyance path 130.

The sheet conveying device 10 of the present embodiment is a double-sided reader. In the conveyance unit 13, the control unit 101 rotates the drive source of the drive mechanism in the normal rotation direction, and temporarily transports the paper to the position of the discharge roller 125 on the reverse conveyance path 132 via the normal conveyance path 130, and then By rotating the drive source in the reverse direction, the paper is returned to the normal conveyance path 130 again via the connection conveyance path 131. When the paper is transported to the position where the transport roller 114 is pulled out on the transport path 131, the control unit 101 causes the rotational direction of the drive source of the drive mechanism to be the forward rotation direction. Then, the paper is conveyed on the normal conveyance path 130 and reaches the position of the discharge roller 125 again. At this time, the paper has a surface on the upper surface, and if the paper discharged in this state is placed on the discharge paper loading portion 12, the arrangement order of the papers is reversed before the conveyance. Therefore, in order to discharge the paper surface as a lower surface, the control unit 101 causes the rotation direction of the drive source of the drive mechanism to be reversed again, thereby transporting the paper in the continuous transport path 131. Then, the paper is conveyed on the normal conveyance path 130, and when the surface reaches the lower state, the paper conveys to the discharge paper placement unit 12 by the discharge roller 125. By combining the normal conveyance path 130 and the reverse conveyance path 132, it can function as an example of the 1st conveyance path of the sheet of this invention. Moreover, the connection conveyance path 131 is an example of the 2nd conveyance path of the sheet of this invention.

The paper pull-in roller 111 is located on the normal conveyance path 130 at the most upstream of the paper conveyance direction. The paper pull-in roller 111 is rotated by the rotation of the feed roller 113 by the belt that is stretched between the feed roller 113 and the feed roller 113, and the paper placed on the document placing portion 11 is pulled into the inside of the transport unit 13. . The feed roller 113 is located on the upstream side of the paper conveyance direction of the connection portion L2 on the normal conveyance path 130, and conveys the paper by the rotation of the driving force generated by the drive source. An electromagnetic clutch to be described later is connected to the feed roller 113, whereby the electromagnetic clutch controls the transmission of the driving force from the drive source. Hereinafter, in the electromagnetic clutch, the driving side of the electromagnetic clutch is connected to the non-driving side by the on/off control of the electromagnet, and the electromagnetic clutch is connected, and the electromagnetic clutch is driven. The state in which the side is not connected to the non-driving side is referred to as making the electromagnetic clutch non-connected. That is, when the electromagnetic clutch is not connected, the feed roller 113 does not rotate. The feed roller 113 is an example of the first conveyance roller of the present invention. Further, the position of the feed roller 113 is a supply position of the supply paper.

The paper reading sensor 112 is disposed between the paper pull-in roller 111 and the feed roller 113 on the normal transport path 130. If paper is detected at this position, the fact that the paper is detected is notified to the control unit 101. . Upon receiving this notification, the control unit 101 causes the electromagnetic clutch connected to the feed roller 113 to be in a connected state to transport the paper.

The pull-out conveyance roller 114 is located at the portion of the connection portion L2, and is rotated by the driving force generated by the drive source to convey the paper. Pulling out the transport roller 114 An additional electromagnetic clutch different from the electromagnetic clutch connected to the feed roller 113 is connected thereto, whereby the electromagnetic clutch controls the transmission of the driving force from the drive source. That is, when the electromagnetic clutch is in the non-connected state, the pull-out conveyance roller 114 does not rotate. The pull-out conveyance roller 114 is an example of the 2nd conveyance roller of this invention. The driven roller 115 rotates in accordance with the rotation of the pull-out conveyance roller 114 to convey the paper. The paper passing sensor 116 is located on the normal transport path 130 on the upstream side of the paper transport direction of the pull-out transport roller 114 and the driven roller 115. If the paper passes the position, the detected fact is notified. The control unit 101 is provided. Upon receiving the notification, the control unit 101 causes the electromagnetic clutch connected to the pull-out conveyance roller 114 to be in a connected state when the time counted by the timer unit has elapsed in advance. Thereby, the pull-out conveyance roller 114 is rotated, and the driven roller 115 is rotated to convey the paper. The predetermined time is the time when the paper passing through the position of the paper passing sensor 116 is brought to the pull-out conveyance roller 114 until the positions in the width direction of the leading end of the paper are aligned with the position of the pull-out conveyance roller 114. The approximate time.

The resist roller 117 transfers the image formed on the paper by the image reading unit 40 by conveying the paper onto the slit glass 14 at a timing determined in advance. The position of the slit glass 14 is located at the reading position of the image on which the paper is read. The driven roller 118 rotates in conjunction with the rotation of the resist roller 117 to convey the paper. The image reading timing sensor 119 is located on the normal conveying path 130 on the downstream side of the sheet conveying direction by the blocking roller 117 and the driven roller 118, and if detected, The front end of the paper is notified to the control unit 101 of the fact. The control unit 101 receives this notification and controls the manner in which the driving by the driving means is stopped until the image reading unit 40 becomes a time at which the image can be read. As a result, since the resist roller 117 does not rotate during this driving stop period, the paper is not conveyed and is positioned on the slit glass 14. When the communication unit 103 receives the notification of the readable timing from the communication unit 183 of the main body of the image forming apparatus 100, the control unit 101 controls the drive generated by the drive means to restart. As a result, the sheet conveyed by the resist roller 117 and the driven roller 118 passes through the slit glass 14, and the image formed on the sheet is read by the image reading portion 40.

The output roller 121 is for conveying paper that has finished image reading. The driven roller 122 rotates in accordance with the rotation of the output roller 121, and conveys the paper. The paper passing sensor 123 is located on the normal transport path 130 on the downstream side of the paper transport direction by the output roller 121 and the driven roller 122, and is a timing for determining the rotation direction of the driving force of the drive source to be the reverse direction. Sensor. If the paper passes the sensor 123 to detect that the trailing end of the sheet passes the position, the fact is notified to the control unit 101. After receiving the notification, the control unit 101 controls the timing of the driving force of the driving mechanism to be the reverse direction when the timing of the timer unit is only a predetermined time. At this time, one end portion of the paper is located at the position of the discharge roller 125, and is located on the reverse conveyance path 132.

In order to discharge the paper conveyed on the normal conveyance path 130 toward the discharge The position of the roller 125 is moved, and the normal conveyance path 130 must be communicated to the position of the discharge roller 125. Downstream of the output roller 121, a press bar 124 is provided in the vicinity of the normal transport path 130 side of the connection portion L2. In a state where no physical force is applied, the press bar 124 hangs down due to its own weight, and the portion where the normal transport path 130 is connected to the reverse transport path 132 is closed at the connection portion L2. When the paper conveyed on the normal conveyance path 130 reaches the press bar 124, the press bar 124 will be pushed up by the paper. Then, when the paper passes, the presser bar 124 is lowered by its own weight, and the path from the connection portion L2 toward the normal conveyance path 130 is blocked, and the paper conveyed backward is moved toward the connection conveyance path 131.

The discharge roller 125 is located on the downstream side of the paper conveyance direction on the normal conveyance path 130, and is located on the reverse conveyance path 132, and is rotated by the driving force generated by the drive source to convey the paper. When the discharge roller 125 rotates in the normal rotation direction, the paper that has been read on both sides of the image that has been completed by the image reading unit 40 is discharged to the discharge paper loading portion 12, and when rotated in the reverse direction, The paper is conveyed toward the connection transport path 131. Further, in the paper on which the image is read on both sides of the unfinished image, the discharge roller 125 causes the rotation direction of the driving force to be reversed in the reverse direction, and the paper is conveyed along the connection path 101. The discharge roller 125 is an example of the third conveyance roller of the present invention. Further, the position at which the discharge roller 125 is located is the discharge position at which the paper is discharged. The driven roller 126 rotates in accordance with the rotation of the discharge roller 125 to convey the paper. The driven roller 126 is the present invention An example of the opposing roller facing the third conveying roller. The solenoid 127, more specifically, a solenoid actuator, for example, is obtained by spirally winding a coil around the outer circumference of a metal core. The solenoid 127 moves the metal core up and down by flowing an electric current. The solenoid 127 is disposed at a position where the driven roller 126 is lifted when the metal core thereof moves up and down. When the paper is conveyed along the transport path 101 and the leading end of the paper reaches the position where the transport roller 114 is pulled out, the control unit 101 causes a current to flow through the solenoid 127, thereby lifting the driven roller 126 upward to make the discharge roller 125 is separated from the driven roller 126. Thereby, the pull-out conveyance roller 114 and the discharge roller 125 that rotate in opposite directions are not pulled in the opposite direction, and the paper is not caught in the position of the discharge roller 125 and the driven roller 126, since it acts at this position. The resistance on the paper is reduced, so that the paper can be smoothly conveyed by the pull-out conveyance roller 114. The solenoid 127 is an example of the roller separating means of the present invention. Next, the drive mechanism will be described.

4 is a schematic enlarged view of the drive mechanism of the conveyance unit 13 from the front side. In FIG. 4, in order to show the position of each member in the depth direction, a step is provided in the depth, and the members located at the depth positions of the respective stages are respectively indicated by lines of different shapes. First, the member which the inner side of the conveyance part 13 is located from the front side is shown by the solid line. Further, a member which is located more outward than the member indicated by the solid line in the direction of the paper surface is indicated by a broken line. Further, a member which is located one step further toward the outer side of the paper surface is indicated by a chain line. In addition, the two-point chain line indicates that it is located in a chain line. The component is a component of the outer side of the paper. The members of the drive mechanism represented by the differently shaped wires are located closer to the back side than the respective rollers. Further, each roller is indicated by a solid line thicker than the member of the drive mechanism. Further, for convenience of explanation, the description of the portions already explained in FIG. 3 will be omitted.

The conveyance unit 13 includes a motor 140, a large diameter gear 141, a small diameter gear 142, gears 144, 145, 146, 147, and 160, electromagnetic clutches 143 and 148, a fixed direction rotation mechanism 149, and a belt 161. Further, the motor 140 shown in the drawing actually represents a gear that is directly coupled to the drive shaft of the motor. The gear 144 is coupled to the rotating shaft of the discharge roller 125, the gear 147 is coupled to the rotating shaft of the feed roller 113, and the electromagnetic clutch 148 is coupled to the rotating shaft of the pull-out conveying roller 114. The gears 144, 147 and the electromagnetic clutch 146 transmit the driving force generated by the motor 140 to the connected rollers. The large diameter gear 141 and the small diameter gear 142 have the same rotation axis, for example, a double gear. Further, the electromagnetic clutch 143 and the gear 145 have the same rotating shaft, for example, a double-layer gear. The electromagnetic clutches 143 and 148 have gears that are connected/separated from the drive side by the action of the electromagnet. This gear becomes engaged with each gear.

The motor 140 is selectively rotatable in the normal rotation direction and the reverse direction opposite to the normal rotation direction to generate a driving force. The motor 140 is an example of a single driving means of the present invention. Further, the forward rotation direction is an example of the first direction of the present invention, and the reverse rotation direction is an example of the second direction of the present invention. Here, the case where the motor 140 rotates in the normal rotation direction will be described as an example, and the transmission of the driving force between the respective rollers and the gears will be described. When the motor 140 rotates in the forward direction, The gear that is connected to the drive shaft of the motor 140 is rotated in the direction of the arrow R1 shown in the figure. Thereby, the large-diameter gear 141 that meshes with the gear of the motor 140 rotates in the direction of the arrow R2, and accordingly, the small-diameter gear 142 also rotates in the same direction, that is, in the R3 direction. The small diameter gear 142 meshes with the gear 144. Thereby, the gear 144 is rotated in the direction of the arrow R4. The gear 144 transmits the driving force to the discharge roller 125, whereby the discharge roller 125 is rotated in the direction in which the sheet is discharged.

In addition, the small diameter gear 142 meshes with the gear of the electromagnetic clutch 143. Thereby, the drive side gear of the electromagnetic clutch 143 is rotated in the direction of the arrow R5. The electromagnetic clutch 143 controls the transmission of the driving force to the gear 145. That is, when the driving side gear of the electromagnetic clutch 143 is separated from the driven side (ie, the non-connected state), the driving force is not transmitted to the gear 145, and on the other hand, the driving side gear of the electromagnetic clutch 143 is When the driven side is connected (ie, the connected state), the driving force is transmitted to the gear 145, and the gear 145 is rotated in the direction of the arrow R6. Gear 145 meshes with gear 146, which meshes with gear 147. Thereby, the gear 146 rotates in the direction of the arrow R7, and the gear 147 rotates in the direction of the arrow R8 shown. The gear 147 transmits the driving force to the feed roller 113, and the feed roller 113 rotates in the direction in which the sheet is conveyed. That is, the electromagnetic clutch 143 switches between a state in which the driving force is transmitted from the motor 140 to the feed roller 113 and a state in which the transmission is not performed. The electromagnetic clutch 143 is an example of the first switching means of the present invention.

The electromagnetic clutch 148 controls the transmission of the driving force transmitted from the fixed-direction rotating mechanism 149 to the pull-out conveying roller 114. That is, in the electromagnetic clutch 148 When it is in the non-connected state, the driving force is not transmitted to the pull-out conveyance roller 114. On the other hand, when the electromagnetic clutch 148 is in the connected state, the driving force is transmitted to the pull-out conveyance roller 114, and the pull-out conveyance roller 114 rotates in the direction in which the sheet is conveyed. That is, the electromagnetic clutch 148 switches between a state in which the driving force is transmitted from the motor 140 to the pull-out conveyance roller 114 and a state in which the transmission is not performed. The electromagnetic clutch 148 is an example of the second switching means of the present invention. The fixed-direction rotating mechanism 149 is a mechanism for rotating the electromagnetic clutch 148 and the pull-out conveying roller 114 having the same rotating shaft as the electromagnetic clutch 148 in the fixed direction by the planetary gear mechanism. A belt 161 is placed on the gear 160, the resist roller 117, and the output roller 121. Thereby, the driving force is transmitted from the gear 160 to the resist roller 117 and the output roller 121. Next, the fixed direction rotation mechanism 149 will be described.

FIG. 5 is a perspective view of the fixed-direction rotating mechanism 149 and the electromagnetic clutch (the driving-side gear) 148 as viewed from the back side of the sheet conveying device 10. The fixed-direction rotating mechanism 149 is composed of an internal gear 150, a sun gear 151, a planetary gear holder 152, and planetary gears 153, 154, and 155. The internal gear 150 is a disk-shaped member and has a gear on the outer peripheral side. In the drawings, for convenience of explanation, the shape of the gear is omitted and drawn as a circle. This is also the same for the sun gear 151. A sun gear 151 is provided on the same rotating shaft as the internal gear 150. That is, the internal gear 150 and the sun gear 151 constitute a double-layer gear. On the outer circumference of the sun gear 151, a planetary gear holder 152 which is a groove in which the rotation shafts of the planetary gears 153 and 154 are fitted is cut in a circular shape. If the sun gear 151 rotates, then the planet The gears 153 and 154 are rotated about the respective rotation axes by meshing with the sun gear 151, and are circumferentially moved along the planetary gear holder 152 around the sun gear 151.

For example, the sun gear 151 is rotated in the direction of the arrow L1a. In this case, the planetary gear 153 rotates in the L2a direction and performs a circular motion in the direction approaching the electromagnetic clutch 148. Moreover, since the gears of the planetary gear 153 and the electromagnetic clutch 148 are meshed, the electromagnetic clutch 146 rotates in the direction of the arrow L3a. On the other hand, the sun gear 151 is rotated in the direction opposite to the arrow L1a, that is, in the direction of L1b. In this case, the planetary gear 154 rotates in the L2b direction and performs a circular motion toward the planetary gear 155. Moreover, since the planetary gear 154 and the planetary gear 155 mesh, the planetary gear 155 rotates in the direction of the arrow L3b. Moreover, since the gears of the planetary gear 155 and the electromagnetic clutch 148 are meshed, the electromagnetic clutch 148 is rotated in the direction of the arrow L4b. As described above, since the arrow L3a and the arrow L4b indicate the same rotation direction, in the fixed direction rotation mechanism 149, the (the drive side gear) 148 of the electromagnetic clutch always rotates in the fixed direction regardless of the direction in which the sun gear 151 rotates. Thereby, the fixed-direction rotation mechanism 149 rotates the pull-out conveyance roller 114 on the normal conveyance path 130 in the rotation direction of the position where the paper is conveyed from the position of the connection part L2 to the connection part L1. The fixed direction rotation mechanism 149 is an example of the rotation mechanism of the present invention.

(action)

Next, the operation of the sheet conveying device 10 will be described. 6 and 7 are schematic views for explaining the operation of the sheet conveying device 10. In FIGS. 6 and 7, a schematic diagram in which the sheet conveying apparatus 10 is enlarged from the front side is assigned a serial number in an increasing order in accordance with the timing of the operation. Hereinafter, for example, a map assigned the number "1" in FIG. 6 is referred to as No. 1 of FIG. If the flow from the start of the conveyance of the paper to the double-sided reading until the discharge is performed in order, it will become No. 1 of FIG. 6, No. 2 of FIG. 6, No. 3 of FIG. 6, No. 4 of FIG. 6, and FIG. No. 5, No. 6 of FIG. 7, No. 3 of FIG. 6, No. 4 of FIG. 6, No. 5 of FIG. 7, No. 6 of FIG. 7, No. 7 of FIG. 7, No. 8 of FIG. The reason for repeating No. 3 of FIG. 6, No. 4 of FIG. 6, No. 5 of FIG. 7, and No. 6 of FIG. 7, as described above, is to adjust the order of the discharged sheets to be the same as before. Duplicate descriptions will be omitted for the drawings relating to such actions. In addition, in FIG. 6 and FIG. 7, the rotation direction of each roller is shown by the arrow. A roller that does not indicate the direction of rotation by an arrow indicates a driven roller or a roller that is not driven at the time.

No. 1 in Fig. 6 indicates a case where the paper P1 is pulled in and started to be transported. First, if the paper reading sensor 112 detects the leading end of the sheet P1, the fact is notified to the control unit 101. Upon receiving the notification, the control unit 101 causes the electromagnetic clutch 143 to be in the connected state when the timing unit has notified that the predetermined time has elapsed. Thereby, the driving force generated by the rotation of the motor 140 in the normal rotation direction is transmitted to the large diameter gear 141, the small diameter gear 142, the electromagnetic clutch 143, the gear 145, the gear 146, and the gear 147, and the feed roller 113 is shown in the figure. The direction of the arrow rotates. Along with this, the feed roller 113 is connected to the pulley. The paper pull-in roller 111 also rotates in the direction of the arrow shown. Further, at this time, the driving force generated by the rotation of the motor 140 in the normal rotation direction is transmitted to the large diameter gear 141, the small diameter gear 142, and the gear 144, and the discharge roller 125 is rotated in the direction of the arrow shown. Further, at this time, the driving force generated by the rotation of the motor 140 in the normal rotation direction is transmitted to the internal gear 150 and the sun gear 151, and further transmitted from the gear 160 to the resist roller 117 and the output roller 121 on which the belt 160 is placed. Thereby, the resist roller 117 and the output roller 121 are rotated in the direction of the arrow shown. Further, at this time, since the electromagnetic clutch 148 is in the non-connected state, the driving force generated by the rotation of the motor 140 is not transmitted, and the pull-out conveying roller 114 does not rotate.

No. 2 of FIG. 6 shows a case where the paper P1 is conveyed by the pull-out conveyance roller 114. If the paper passes the sensor 116 to detect the leading end of the sheet P1, the fact is notified to the control unit 101. Upon receiving the notification, the control unit 101 causes the electromagnetic clutch 148 to be in a connected state and the electromagnetic clutch 143 to be in a disconnected state when the time counted by the timer unit has elapsed only for a predetermined period of time. As a result, since the driving force is not transmitted, the feed roller 113 stops its rotation. Further, along with this, the paper pull-in roller 111 also stops its rotation. On the other hand, since the electromagnetic clutch 148 is in the connected state, the driving force is transmitted by the fixed-direction rotating mechanism 149, and the pull-out conveying roller 114 is rotated in the direction of the arrow shown. Here, the control unit 101 counts the number of times the electromagnetic clutch 148 is in the connected state as the variable C, and stores it in the RAM. The initial value of the variable C is zero. In order to read both sides of the paper and make the table The surface is discharged as follows, and the same sheet of paper has to be conveyed three times at a position where the conveyance roller 114 is pulled out, that is, the surface reading conveyance, the back surface reading conveyance, and the inner and outer reverse conveyance. Since the value of the variable C is "3", only the paper currently being conveyed has been ejected, so that the next sheet can be transported. When the transfer of the next paper is started, the control unit 101 clears the variable C to the initial value. At the timing of No. 2 in Fig. 6, the value of the variable C is "1". If the paper passes the sensor 116 to detect the trailing end of the sheet P1, the fact is notified to the control unit 101. After receiving the notification, the control unit 101 causes the electromagnetic clutch 146 to be in a disconnected state when the time counted by the timer unit has passed only a predetermined time.

No. 3 of FIG. 6 indicates a case where the image formed on the sheet P1 is read by the image reading unit 40, and the front end of the next sheet P2 is abutted against the feed roller 113. When the sheet P1 is conveyed to the position of the resist roller 117 and the image reading timing sensor 119 detects the leading end of the sheet P1, the image reading timing sensor 119 notifies the control unit 101 of this fact. Upon receiving the notification, the control unit 101 temporarily stops the driving of the motor 140 until the image reading unit 40 receives the notification of the preparation for reading the completed image. When the control unit 101 receives the notification of the preparation for reading the completed image from the communication unit 183 of the image forming apparatus 100 main body, the control unit 101 restarts the driving of the motor 140. As a result, the paper P1 is conveyed again, and when it passes through the slit glass 14, the image reading unit 40 reads the image formed on the paper P1, and supplies the reading result to the control unit 181. The control unit 181 causes the reading result to be stored In the RAM, and as necessary, the image forming portion 30 is instructed to form an image of the reading result on the sheet.

The sheet P1 passing through the slit glass 14 is conveyed by the output roller 121. In the No. 3 of Fig. 6, since the leading end of the paper is pressed against the pressing rod 124, the pressing rod 124 is raised. Here, if the paper passes the sensor 123 to detect the trailing end of the sheet P1, the fact is notified to the control unit 101. After receiving the notification, the control unit 101 causes the rotation direction of the motor 140 to be the reverse direction when the time counted by the timer unit is only a predetermined time. This predetermined time is, for example, the time required from the paper passing through the sensor 123 to detect the rear end of the sheet P1 until the trailing end of the sheet P1 is conveyed to the discharge roller 125. The raised pressure bar 124 will accompany the passage of the paper due to its own weight.

No. 4 of FIG. 6 indicates a case where the motor 140 rotates in the reverse rotation direction and the paper P1 is conveyed on the connection conveyance path 131. The paper P1 is conveyed by the discharge roller 125, and its leading end moves in the direction in which the conveyance roller 114 is pulled out.

No. 5 of FIG. 7 indicates a case where the paper P1 is transported on the connection transport path 131. If the paper passes the sensor 116 to detect the leading end of the sheet P1, the fact is notified to the control unit 101. Upon receiving the notification, the control unit 101 causes the electromagnetic clutch 148 to be in a connected state when the time counted by the timer unit has elapsed for a predetermined period of time. The control unit 101 increments the variable C, and as a result, the value of the variable C becomes "2". At this time, although the rotation direction of the motor 140 is the reverse direction, the rotation is performed by the above fixed direction. The action of the mechanism 149 causes the direction of rotation of the electromagnetic clutch 148 to be a fixed direction, that is, a forward direction. Thereby, the pull-out conveyance roller 114 also rotates in the normal rotation direction, and conveys the paper P1.

No. 6 in Fig. 7 indicates a case where the motor 140 performs forward rotation again, and the solenoid 127 lifts the driven roller 126. When the electromagnetic clutch 148 is in the connected state, the control unit 101 controls the driven roller 126 by causing a current to flow through the solenoid 127 when the value of the variable C is "2" or "3". Was raised. Further, at this time, the control unit 101 changes the rotation direction of the motor 140 from the reverse direction to the forward rotation direction. At this time, although the rotation direction of the pull-out conveyance roller 114 and the discharge roller 125 is a reverse direction, since the driven roller 126 is lifted, the state in which the sheets are pulled in the opposite directions is released, and the discharge roller 125 and the follower are released. The position of the roller 126 does not sandwich the paper, and the resistance is reduced, so that the paper P1 is conveyed by the pull-out conveyance roller 114.

Then, the same operations as those described in No. 3 of Fig. 6, No. 4 of Fig. 6, No. 5 of Fig. 7, and No. 6 of Fig. 7 are performed. When the operation of No. 5 of Fig. 7 is completed for the second time, the value of the variable C becomes "3". When the operation of No. 6 of Fig. 7 is performed for the second time, the value of the variable C is "3", and the next sheet can be transported. Therefore, after a predetermined time has elapsed from the paper passing sensor 116 detecting the trailing end of the sheet P1, the control unit 101 causes the electromagnetic clutch 148 to be in a non-connected state, and the electromagnetic clutch 143 is brought into a connected state. Thereby, the feed roller 113 and the paper pull-in roller 111 are rotated in the normal rotation direction, and the next paper P2 is conveyed. Thus, the control unit 101, by switching the electromagnetic clutch 148 and the electromagnetic clutch The transmission state of the driving force of 143 controls the timing of paper conveyance. Further, the control unit 101 clears the value of the variable C to the initial value.

No. 7 of Fig. 7 indicates a case where the sheet P1 is in the middle of discharge and the next sheet P2 is brought to the feed roller 113. If the paper passes the sensor 116 to detect the leading end of the sheet P2, the fact is notified to the control unit 101. When the control unit 101 receives the notification, if the time counted by the timer unit passes a predetermined time, the electromagnetic clutch 148 is brought into a connected state, and the electromagnetic clutch 143 is brought into a non-connected state.

No. 8 of Fig. 7 shows a case where the sheet P1 is discharged and the next sheet P2 is conveyed. Since the electromagnetic clutch 148 is in the connected state, the pull-out conveyance roller 114 rotates in the direction of the arrow shown, and conveys the paper P2. The paper P1 is conveyed by the discharge conveyance roller 125, and is discharged to the discharge paper loading unit 12.

According to the present embodiment, the control unit 101 rotates the motor 140 in the normal rotation direction, and starts the conveyance of the first paper fed from the supply position, and after the first paper passes the position of the feed roller 113 on the normal conveyance path 130, The electromagnetic clutch 143 is switched from a state in which the driving force is transmitted to the feed roller 113 to a state in which the transmission is not performed. Further, the control unit 101 switches the state in which the driving force is transmitted to the drawing conveyance roller 114 by the electromagnetic clutch 148 after the position where the first paper passes the position where the conveyance roller 114 is pulled out by the electromagnetic conveyance path 138, so that the transmission is not performed. status. Further, when the first paper is conveyed to the discharge roller 125 at the normal conveyance path 130, the control unit 101 rotates the motor 140 in the reverse rotation direction to change the rotation of the discharge roller 125. In the turning direction, the first paper is conveyed to the position where the conveyance roller 114 is pulled out via the connection conveyance path 131. In addition, the control unit 101 switches the state in which the driving force is transmitted to the pull-out conveyance roller to the state in which the transmission is performed, and the motor 140 is rotated in the normal rotation direction to change the rotation direction of the discharge roller 125. When the first paper passes the position where the transport roller 114 is pulled out, the control unit 101 switches the state in which the driving force is transmitted to the pull-out transport roller 114 to the state in which the transfer is not performed by the electromagnetic clutch 148. In the state where the transmission of the driving force to the feed roller 113 is not performed, the electromagnetic clutch 143 is switched to the state in which the transfer is performed, and the conveyance of the second paper to be conveyed after the first paper is started. In addition, the first paper is conveyed and discharged by the discharge roller 125 while the motor 140 is rotated in the normal rotation direction until the position at which the second paper is conveyed to the discharge roller 125 via the image reading position.

According to this configuration, since the drive source is the single motor 140, the rotation direction of each roller is always determined to be a certain direction, so that the control of the motor 140 by the control unit 101 is simplified. Further, when the leading end of the sheet reaches the position of the feed roller 113 and the pull-out conveyance roller 114, the electromagnetic clutches 143 and 148 are used to transfer the driving force to the feed roller 113 and the pull-out conveyance roller 114, respectively. The state of the transfer is switched to a state in which the transfer is not performed, whereby the leading end of the sheet conveyed obliquely is brought into contact with each roller, and the positions in the width direction of the leading end of the sheet are aligned at the positions of the respective rollers. Thereby, the edge of the leading end of the paper is conveyed in a state parallel to the rotation axis direction of each roller, and the inclination of the paper can be suppressed. Row. By suppressing the skew of the paper, the image formed by the image reading unit 40 is adjusted in the direction in which the image formed on the paper is aligned with respect to the reading direction specified by the paper to be the original. Read. Further, by reading the image formed on the paper as described above, when the image forming unit 30 forms an image based on the reading result on the paper, the reading is specified with respect to the paper that becomes the original. The direction forms an image on the paper in a state where the direction and position of the image are adjusted. In addition, since the subsequent conveyance of the second paper can be started before the first paper is discharged, the productivity of the sheet conveying device 10 and the image forming apparatus 100 can be improved. According to the present embodiment, when the sheet conveying device driven by the single driving means conveys the paper on both sides of the readable paper, it is possible to prevent the paper from being skewed while being positioned in front. Before the first paper is discharged, the subsequent conveyance of the second paper is started.

10‧‧‧Sheet conveying device

11‧‧‧Original Loading Department

12‧‧‧Discharge paper loading section

13‧‧‧Transportation Department

14‧‧‧Slit glass

20‧‧‧Feeding Department

21‧‧‧ Paper Storage Department

22‧‧‧Feeding means

30‧‧‧Image Formation Department

31‧‧‧Photoreceptor roller

32‧‧‧Electrical appliances

33‧‧‧Exposure device

34‧‧‧developer

35‧‧‧Toner card

36‧‧‧Intermediate transfer belt

37‧‧‧Fixing device

40‧‧‧Image Reading Department

100‧‧‧Image forming device

101‧‧‧Control Department

102‧‧‧ Storage Department

103‧‧‧Communication Department

111‧‧‧paper pull-in roller

112‧‧‧paper reading sensor

113‧‧‧feed rolls

114‧‧‧ Pull out the transport roller

115‧‧‧ driven roller

116‧‧‧paper passing sensor

117‧‧‧Barrier roller

118‧‧‧ driven roller

119‧‧‧Image reading timing sensor

121‧‧‧ Output Roller

122‧‧‧ driven roller

123‧‧‧paper passing sensor

124‧‧‧Press

125‧‧‧ discharge roller

126‧‧‧ driven roller

127‧‧‧ Solenoid

130‧‧‧Normal transport path

131‧‧‧Connected transport path

132‧‧‧Reverse transport path

140‧‧‧Motor

141‧‧‧ Large diameter gear

142‧‧‧ Small diameter gear

143‧‧‧Electromagnetic clutch

144‧‧‧ Gears

145‧‧‧ gears

146‧‧‧ Gears

147‧‧‧ Gears

148‧‧‧Electromagnetic clutch

149‧‧‧ Fixed direction rotating mechanism

150‧‧‧Internal gear

151‧‧‧Sun Gear

152‧‧‧ Planetary gear holder

153‧‧‧ planetary gear

154‧‧‧ planetary gear

155‧‧‧ planetary gear

160‧‧‧ gears

161‧‧‧ drive belt

181‧‧‧Control Department

182‧‧‧ Storage Department

183‧‧‧Communication Department

184‧‧‧U1

A1‧‧‧ arrow

L1‧‧‧ connection site

L2‧‧‧ connection site

L1a, L1b, L2a, L2b, L3a, L3b, L4b‧‧‧ arrows

P1‧‧‧ paper

P2‧‧‧ paper

R1~R8‧‧‧ arrow

FIG. 1 is a schematic configuration view of an image forming apparatus including a sheet conveying device according to an embodiment of the present invention as seen from the front side.

Fig. 2 is a block diagram showing a hardware structure of a sheet conveying device.

3 is a schematic view showing an enlarged portion of a conveying unit of the sheet conveying device from the front side.

4 is a schematic view showing the drive mechanism enlarged and perspective from the front side.

Fig. 5 is a perspective view of the fixed-direction rotating mechanism as seen from the back side of the sheet conveying device.

Fig. 6 is a schematic view for explaining the operation of the sheet conveying device.

FIG. 7 is a schematic view for explaining the operation of the sheet conveying device.

14‧‧‧Slit glass

111‧‧‧paper pull-in roller

112‧‧‧paper reading sensor

113‧‧‧feed rolls

114‧‧‧ Pull out the transport roller

115‧‧‧ driven roller

116‧‧‧paper passing sensor

117‧‧‧Barrier roller

118‧‧‧ driven roller

121‧‧‧ Output Roller

119‧‧‧Image reading timing sensor

122‧‧‧ driven roller

123‧‧‧paper passing sensor

125‧‧‧ discharge roller

124‧‧‧Press

127‧‧‧ Solenoid

126‧‧‧ driven roller

131‧‧‧Connected transport path

130‧‧‧Normal transport path

L1‧‧‧ connection site

132‧‧‧Reverse transport path

L2‧‧‧ connection site

Claims (4)

A sheet conveying device comprising: a first conveying path of a sheet, which is discharged from a reading position of an image of the sheet to a discharge position at which the sheet is discharged from a supply position of the sheet to be discharged a second transport path of the sheet from the first position to the second position on the first transport path, wherein the second position is located on the first transport path and is located in the sheet transport more than the first position An upstream side of the direction; a single driving means selectively rotating in the first direction and the second direction to generate a driving force; and the first conveying roller is closer to the second position on the first conveying path The position on the upstream side in the conveyance direction is rotated by the driving force generated by the driving means to convey the sheet, and the second conveyance roller is driven by the driving force generated by the driving means at the second position. The third transporting roller is rotated by the driving force generated by the driving means at a position on the downstream side of the first transport position in the transport direction on the first transport path. And rotating the sheet; the rotating mechanism rotates the sheet in the rotation direction of the sheet from the second position to the first position on the first conveying path regardless of the rotation direction of the driving means The second transfer roller; the first switching means switches between the driving force and the driving force, the driving force is transmitted from the driving means to the first conveying roller; and the second switching means switches and does not drive State of force transmission, The driving force is transmitted from the driving means to the second conveying roller, and a control means for controlling the driving means, the first switching means, and the second switching means, wherein the control means is to cause the driving means to The first direction is rotated, and the first sheet supplied from the supply position is started to be conveyed, and the first sheet is passed through the position of the first conveyance roller on the first conveyance path, and the first switching means is used. The state in which the driving force is transmitted to the first conveying roller is switched to a state in which the transmission is not performed, and the first sheet is passed through the position of the second conveying roller on the first conveying path. The second switching means switches the state in which the driving force is transmitted to the second conveyance roller to a state in which the transmission is not performed, and the first sheet is conveyed to the third conveyance in the first conveyance path. The position of the roller rotates the drive means in the second direction, changes the rotation direction of the third conveyance roller, and conveys the first sheet to the second conveyance path via the second conveyance path. The position of the feed roller is switched from the state in which the driving force is transmitted to the second conveyance roller to the state in which the transfer is not performed, and the drive means is rotated in the first direction to change the third conveyance. In the rotation direction of the roller, when the first sheet passes the position of the second conveyance roller, the state in which the driving force is transmitted to the second conveyance roller is switched to a state in which the transmission is not performed by the second switching means. On the other hand, the state in which the driving force is transmitted to the first conveying roller is not switched by the first switching means. In the state in which the transfer is performed, the conveyance of the second sheet to be conveyed after the first sheet is started, and the second sheet is conveyed to the position of the third conveyance roller via the reading position. In the first rotation period in the first direction by the driving means, the first sheet is conveyed and discharged by the third conveyance roller. The sheet conveying apparatus according to the first aspect of the invention, further comprising a roller separating means for separating the third conveying roller and the opposing roller facing the third conveying roller, wherein the control means When the driving means rotates in the second direction, when the leading end of the sheet reaches the position of the second conveying roller, the second switching means switches the state in which the driving force is transmitted to the second conveying roller to In the state where the transfer is not performed, the driving means is rotated in the first direction, and the third transfer roller and the counter roller are separated by the roller separating means. An image reading apparatus comprising: a sheet conveying device according to claim 1 or 2; and an image reading device that reads from a sheet conveyed by the sheet conveying device Take the image. An image forming apparatus comprising: an image reading apparatus according to item 3 of the patent application; and an image forming means for forming an image read by the image reading apparatus in a recording In the media.