JP2004299891A - Image forming apparatus and reversal carrying unit installable thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of discharging and reversal carrying sheets by a simple drive transmission mechanism with suppressed number of parts such as an electromagnetic clutch with drive sources in an apparatus body and in a reversal carrying part and a reverse carrying unit installable thereon. <P>SOLUTION: When a planet gear 56 is positioned on the lower side and meshed with a drive gear 51, the rotating driving of a first motor 50 is transmitted to a sheet discharge roller 30 by vertically moving the rotating driving of the first motor 50 on the apparatus body side and the rotating driving of a second motor 61 on a reverse carrying unit 40 by a switching lever 68 to which the planet gear 56 is fitted. When the planet gear 56 is positioned on the upper side and meshed with an idler gear 65, the rotating driving of the second motor 61 is transmitted to the sheet discharge roller 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine or a facsimile apparatus, which includes an image forming apparatus provided with an inverting and conveying unit used for forming an image on both sides of a sheet, and an inverting conveying unit in which the inverting and conveying unit is detachably configured. About the unit.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus, a motor is provided as a drive source in an apparatus main body to drive a recording unit including a photosensitive drum or the like for forming an image and a sheet conveying unit including a conveying roller. In such an image forming apparatus, when an image is formed on both sides of a sheet, it is possible to carry out image formation on one side of the sheet and then reversely rotate the sheet discharge roller in order to reverse the sheet and carry the sheet into the reverse conveyance path. Is being done. However, if the rotation of the discharge roller and the photosensitive drum is controlled by one motor, the photosensitive drum cannot be rotated in the reverse direction, so that only the discharge roller needs to be reversely rotated.
[0003]
As a solution to such a problem, for example, in Patent Document 1, a motor is provided in each of the image forming apparatus main body and the double-sided conveying unit, and when the paper is conveyed in the paper discharging direction, the motor in the apparatus main body corrects the discharge roller. It is described that the motor in the unit rotates the paper discharge roller in the reverse rotation direction when the paper is rotated in the reverse direction and the sheet is transported in the reverse direction. According to Patent Document 2, when the duplex unit is not mounted, the discharge roller is driven to rotate by the main motor in the apparatus main body, and when the duplex unit is mounted, the discharge roller is rotated forward and reverse by the motor in the unit. It is described that the sheet is driven to discharge the sheet and carry the sheet into the unit.
[0004]
[Patent Document 1]
JP 2002-154727 A [Patent Document 2]
JP-A-9-136772
[Problems to be solved by the invention]
In Patent Document 1, in order to drive and transmit one of the driving forces of two motors in an image forming apparatus main body and a two-sided conveyance unit to a discharge roller, complicated drive transmission such as an electromagnetic clutch, a spring clutch, and a rotation delay device is performed. Since the mechanism is used, there are disadvantages in that the number of components to be used for drive transmission increases, the number of control targets increases, the control sequence becomes complicated, and the number of wires increases. Therefore, the cost also increases. In Patent Document 2, when the unit is mounted, the discharge roller is driven by the motor in the unit, so that a load is applied to the motor in the unit. Therefore, a motor for driving the reverse conveyance roller is separately provided in the unit. However, an increase in the number of parts is inevitable, such as the need for extra parts.
[0006]
Therefore, the present invention provides an image forming apparatus capable of discharging and reversing a sheet by a driving source in the apparatus main body and a reversing conveyance section with a simple drive transmission mechanism with a reduced number of parts such as an electromagnetic clutch, and an image forming apparatus mounted thereon. It is an object of the present invention to provide a reversible transport unit.
[0007]
[Means for Solving the Problems]
An image forming apparatus according to an aspect of the invention includes a sheet conveying unit that conveys a sheet conveyed from a sheet feeding unit to a recording unit and conveys the sheet to a discharge tray, and a downstream side of the recording unit in a sheet conveying path of the sheet conveying unit. An image forming apparatus comprising: a reversing conveyance unit that conveys a sheet conveyed from the upstream of the recording unit; a sun gear that is always in a state in which drive can be transmitted to a discharge roller of the sheet conveyance unit; A planetary gear meshing with a gear; and a first position for transmitting the driving force from the first driving source of the paper transport unit or a second position for transmitting the driving force of the second driving source of the reverse transporting unit. And a positioning means for selectively positioning, and the driving force of the first driving source and the second driving source is selectively transmitted to the discharge roller. Further, the positioning means comprises an operation member fixed to a planetary gear, and an electric actuator for operating the operation member. Further, the positioning means includes an urging means for urging the operation member so that the planetary gear is positioned at the first position.
[0008]
Further, a reverse transport unit according to the present invention is characterized in that the reverse transport unit in the above-described image forming apparatus is configured to be detachable. In addition, a reverse transport unit in which the reverse transport unit in the image forming apparatus described above is detachably configured, wherein the electric actuator is provided.
[0009]
With the above configuration, if the planetary gear is selectively positioned at the first position for transmitting the driving force from the first driving source or the second position for transmitting the driving force of the second driving source, it is simple. In addition, the driving force of the first driving source and the driving force of the second driving source can be switched, and only the positioning means for moving the planetary gears suffices.
[0010]
If the operation member fixed to the planetary gear is operated by the electric actuator, the driving force can be switched by one electric actuator, so that a simple mechanism can be realized. Further, by providing an urging means for urging the operating member so that the planetary gear is positioned at the first position, the electric actuator is always positioned at the first position when the electric actuator is off, and only when positioned at the second position. It is only necessary to turn on the electric actuator, and the power consumption can be minimized.
[0011]
If the electric actuator is provided in the reverse transport unit, the electric actuator can be driven only when the reverse transport unit is mounted, and the number of components mounted in the apparatus main body can be reduced.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail. FIG. 1 is a schematic sectional view of the entire image forming apparatus according to the present invention. A document reading unit 2 is disposed above the image forming apparatus 1, and a sheet feeding unit 3 and a recording unit 4 are disposed below the image reading unit 2 from the bottom.
[0013]
In the document reading section 2, a document placed on a document tray 11 provided with a document cover 10 is transported by a document transport device 12 to a position facing reading means (not shown), and a document reading operation is performed. 13 is discharged. When reading a book or the like, the document cover 10 is rotated upward, a portion to be read such as a book is placed on the flatbed platen 14, and a reading operation is performed by a reading unit. The above configuration is the same as that of a conventional document reading apparatus called a so-called ADF or flatbed type.
[0014]
In the paper feed unit 3, a paper feed cassette 15 is arranged, and a plurality of sheets of a predetermined size are stacked on the flapper 16. At the right end of the paper feed cassette 15, a pickup roller 17 is arranged. The flapper 16 is urged upward so that the upper surface of the stacked sheets is pressed against the pickup roller 17. When the pickup roller 17 is driven to rotate in this state, the sheets are fed one by one to the sheet transport path by the frictional force.
[0015]
The fed paper is first conveyed to the recording unit 4 by the feed roller 18 and the press roller 19. The recording unit 4 includes a toner container 20, a memory removing brush 21, a corona charger 22, a photosensitive drum 23, a corotron wire 24 for transfer, an exposure head 25, and a fixing roller 26 for recording on a conveyed sheet. Provided. First, the surface of the photosensitive drum 23 is uniformly charged by using the memory removing brush 21 and the corona charger 22, and the charged photosensitive drum 23 is exposed by the exposure head 25 in accordance with an image recording signal, so as to be static. An electrostatic latent image is formed. Next, the toner in the toner container 20 is transferred from the supply roller 27 to the electrostatic latent image formed on the photosensitive drum 23 via the developing roller 28 to be visualized. The toner image formed on the surface is transferred to paper. Then, the transferred toner image is nipped by the fixing roller 26 and the press roller 29, heated and pressed, and fixed on the sheet. The fixed sheet is sandwiched between the sheet ejection roller 30 and the press roller 31 and is carried out to the sheet ejection tray 32.
[0016]
In FIG. 1, the portion from the sheet feeding section 3 to the sheet discharge tray 32 is indicated by a dashed line in the sheet transport path. The transport rollers and the paper guide disposed along the paper transport path constitute a paper transport unit.
[0017]
A reverse transport unit 40 is detachably mounted on a side surface of the apparatus main body, and a paper outlet 41 and a paper inlet 42 are formed on the mounting side. In the transport unit 40, two pairs of transport rollers, a feed roller 43 and a press roller 44, and a feed roller 45 and a press roller 46, are disposed vertically. Then, as shown by the two-dot chain line in FIG. 1, the reversing conveyance path branches off from the paper conveyance path between the paper discharge roller 30 and the fixing roller 26, and the two pairs of conveyance rollers 43 and 44, 45 and 46 It is formed so as to pass through the gap and to join the sheet transport path between the roller pairs 18 and 19 and the pickup roller 17. The transport roller and the paper guide disposed along the reverse transport path constitute a reverse transport unit.
[0018]
In the sheet transport path, a sheet detection sensor 33 is disposed between the sheet discharge roller 30 and the fixing roller 26 of the recording unit 4, and a sheet detection sensor 34 is also provided between the roller pairs 18 and 19 and the pickup roller 17. Is arranged.
[0019]
FIG. 2 is a schematic diagram relating to a driving mechanism of the discharge roller 30. A first motor 50 is provided on the apparatus main body side, and the first motor 50 rotates the photosensitive drum 23, the fixing roller 26, the feed roller, and the like. A driving gear 51 is attached to a rotation shaft of the fixing roller 26, and the driving gear 51 is rotated by a drive transmission mechanism (not shown) from the first motor 50 to drive the fixing roller 26. A drive gear 52 is mounted on the rotation shaft of the paper discharge roller 30.
[0020]
A sun gear 53 is rotatably attached to the apparatus main body between the drive gear 51 and the drive gear 52, and one end of a lever member 55 is pivotally attached to a rotation shaft 54 of the sun gear 52. A planetary gear 56 is rotatably mounted on the central portion of the lever member 55 in a state in which the planetary gear 56 is meshed with the sun gear 53. It turns around 53. When the lever member 55 rotates downward, the planetary gear 56 meshes with the drive gear 51. When the lever member 55 rotates upward, the planetary gear 56 meshes with the idler gear 57 and is connected to the drive gear 52.
[0021]
A spring 59 is attached to the other end 58 of the lever member 55 and urges the lever member 55 downward. Therefore, the lever member 55 is held in a state of being rotated downward, and the planetary gear 56 is in a state of being always meshed with the drive gear 51.
[0022]
On the other hand, a mounting board 60 is fixed to the reverse transport unit 40 side, and a second motor 61 is mounted on the mounting board 60. The second motor 61 drives the feed rollers 43 and 45 in the reverse transport unit 40 to rotate. An idler gear 63 meshing with a motor gear 62 of a second motor 61 is rotatably mounted on the mounting substrate 60, and is rotatably arranged in a state in which idler gears 64 and 65 are sequentially meshed from the idler gear 63 toward the apparatus main body. Have been.
[0023]
A solenoid 66 is provided in the reverse transport unit 40, and a drive bar 67 is provided on the solenoid 66 so as to project upward. In FIG. 2, the solenoid 66 is off. The switching lever 68 has a central portion rotatably attached to a shaft 69, and one end portion pivotally attached to an upper end portion of the drive bar 67. The other end of the switching lever 68 is located below the other end of the lever member 55 provided on the apparatus main body side.
[0024]
In FIG. 2, since the planet gear 56 is held at a position meshed with the drive gear 51 by the spring 59, when the drive gear 51 rotates, the planet gear 56 and the sun gear 53 rotate to rotate the idler gear 57 to the drive gear 52. , The paper discharge roller 30 rotates, and the paper discharge operation is performed. Since the planetary gear 56 is not meshed with the idler gear 65 on the reverse transport unit 40 side, the rotational drive of the second motor 61 is not transmitted to the paper discharge roller 30.
[0025]
Next, as shown in FIG. 3, when the solenoid 66 is turned on, the drive bar 67 moves downward, the switching lever 68 is pulled downward, and the switching lever 67 rotates clockwise. Therefore, the other end of the switching lever 68 rises and pushes up the other end 58 of the lever member 55. When the other end 58 of the lever member 55 rises against the urging force of the spring 59, the planetary gear 56 is in a state of meshing with the idler gear 65.
[0026]
In this state, when the second motor 51 is driven to rotate, the driving force is transmitted from the drive gear 62 to the idler gears 63, 64, and 65, and the planetary gear 56 and the sun gear 53 rotate. The rotation is transmitted from 57 to the drive gear 52, and the paper discharge roller 30 rotates to operate to carry out the paper to the reverse transport unit.
[0027]
In the case of performing the reverse conveyance control of the paper, the leading end of the paper on which an image is formed on one side is nipped by the paper ejection roller 30 and the press roller 31, and then the paper ejection roller 30 is rotated counterclockwise by the first motor 50 to be ejected. The discharge operation to the tray 32 is performed, and the driving of the first motor 50 is stopped when the trailing edge detection sensor 33 detects the trailing edge of the sheet. During this time, the solenoid 66 is in the off state, and the planetary gear 56 is positioned so as to mesh with the drive gear 51. At this time, the rear end of the sheet is sandwiched between the sheet discharging roller 30 and the press roller 31. Thereafter, the solenoid 66 is turned on, the planetary gear 56 is positioned at a position where it meshes with the idler gear 65 as shown in FIG. 3, and the driving of the second motor 61 in the reverse transport unit 40 is started. The rotation drive of the second motor 61 is transmitted, and the paper discharge roller 30 is rotated clockwise to carry the paper from the rear end of the paper into the paper outlet 41 and transport the paper to the reverse transport path. The feed roller 43 and the feed roller 45 rotate in conjunction therewith, and the paper is conveyed through the reverse conveyance path and is carried in from the paper entrance 42. When the leading edge detection sensor 34 detects the leading edge of the sheet, the driving of the second motor 61 is stopped, and the leading edge of the sheet is brought into contact with the feed roller 18. Thereafter, the solenoid 66 is turned off and the first motor 50 starts driving, the paper is conveyed through the paper conveyance path from the feed roller 18, and the remaining surface is image-formed by the recording unit 4 to form the image on both surfaces. Control is performed.
[0028]
【The invention's effect】
As described above, in the present invention, if the planetary gears are selectively positioned at the first position for transmitting the driving force from the first driving source or the second position for transmitting the driving force of the second driving source, it is simple. In addition, the driving force of the first driving source and the driving force of the second driving source can be switched, and only the positioning means for moving the planetary gears suffices.
[0029]
If the operation member fixed to the planetary gear is operated by the electric actuator, the driving force can be switched by one electric actuator, so that a simple mechanism can be realized. Further, by providing an urging means for urging the operating member so that the planetary gear is positioned at the first position, the electric actuator is always positioned at the first position when the electric actuator is off, and only when positioned at the second position. It is only necessary to turn on the electric actuator, and the power consumption can be minimized.
[0030]
If the electric actuator is provided in the reverse transport unit, the electric actuator can be driven only when the reverse transport unit is mounted, and the number of components mounted in the apparatus main body can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an entire image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a drive transmission mechanism that performs reverse conveyance.
FIG. 3 is a schematic diagram illustrating a drive transmission mechanism that performs reverse conveyance.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 image forming apparatus 2 document reading unit 3 paper feed unit 4 recording unit 30 paper discharge roller 31 press roller 33 paper detection sensor 34 paper detection sensor 40 reverse transport unit 41 paper carry-in port 42 paper carry-out port 43 feed roller 44 press roller 45 feed Roller 46 press roller 50 first motor 51 drive gear 52 drive gear 53 sun gear 54 rotation shaft 55 lever member 56 planetary gear 57 idler gear 59 spring 60 mounting board 61 second motor 62 drive gear 63 idler gear 64 idler gear 65 idler gear 66 solenoid 67 drive Bar 68 Switching lever 69 Shaft

Claims (5)

A paper transport unit that transports the paper conveyed from the paper supply unit to the recording unit and transports the paper to the discharge tray; and a recording unit that transports the paper conveyed from the downstream side of the recording unit in the paper transport path of the paper transport unit. An image forming apparatus provided with a reversing conveyance unit that carries out an upstream side of the sun gear, a sun gear that is always in a state in which drive can be transmitted to a discharge roller of the paper conveyance unit, a planet gear that meshes with the sun gear, Positioning means for selectively positioning the planetary gear at a first position transmitting a driving force from a first driving source of the paper transport unit or at a second position transmitting a driving force of a second driving source of the reverse transport unit; An image forming apparatus, wherein the driving force of the first driving source and the second driving source is selectively transmitted to the discharge roller. The image forming apparatus according to claim 1, wherein the positioning unit includes an operation member fixed to a planetary gear, and an electric actuator that operates the operation member. The image forming apparatus according to claim 2, wherein the positioning unit includes a biasing unit configured to bias the operation member so that the planetary gear is positioned at the first position. A reverse transport unit, wherein the reverse transport unit in the image forming apparatus according to claim 1 is detachably configured. A reversing transport unit in which the reversing transport unit in the image forming apparatus according to claim 2 or 3 is configured to be detachable, wherein the electric actuator is provided.

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