Conveyance device and image forming device equipped with conveyance device

Abstract

To provide a conveyance device in which a rotational direction switching part that switches a rotational direction of a conveyance roller is realized with a configuration suitable for miniaturization, and an image forming device equipped with the conveyance device.SOLUTION: A conveyance device includes: an electric motor; a rotational direction switching part having an input gear that rotates upon receiving a rotational force of the electric motor, a first carrier that rotates in a first direction upon receiving the rotational force of the input gear, a second carrier that rotates in a second direction opposite to the first direction upon receiving the rotational force of the input gear, and an output gear that rotates in one of the first direction and the second direction upon receiving one of the rotational force of the first carrier and the rotational force of the second carrier, with rotational centers of the input gear, the first carrier, the second carrier, and the output gear aligned on a straight line, to select one of the rotational force of the first carrier and the rotational force of the second carrier and transmit the one to the output gear; and a conveyance roller that rotates upon receiving the rotational force of the output gear and conveys paper.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a conveying device and an image forming apparatus including the conveying device. [Background technology]

[0002] Generally, electrophotographic image forming devices have a double-sided printing function in which, after an image is formed on one side of a sheet of paper, the sheet is turned over and an image is formed on the other side of the sheet. In such image forming devices, the sheet of paper, which has an image formed on one side and is transported to the transport roller in front of the discharge tray, is sent back into the image forming device by switching the rotation direction of the transport roller to the reverse, and the sheet is turned over on the transport path inside the image forming device.

[0003] For example, Patent Document 1 discloses an image forming apparatus including a drive input gear that is rotationally driven by rotational force from a drive source, a first output gear that meshes with the drive input gear and rotates in the opposite direction to the drive input gear, a second output gear that meshes with the drive input gear via a counter gear and rotates in the same direction as the drive input gear, and a drive output gear that meshes with the first output gear and the second output gear and drives a conveyance roller. By switching between a first clutch that can disconnect or connect the transmission path of drive force from the drive input gear to the first output gear and a second clutch that can disconnect or connect the transmission path of drive force from the drive input gear to the second output gear, when the drive force of the first output gear is transmitted, the drive output gear rotates in the same direction as the drive input gear, and when the drive force of the second output gear is transmitted, the drive output gear rotates in the opposite direction to the drive input gear. With such a configuration, even with one drive source, it is possible to switch the rotation direction of the drive output gear and switch the transport direction of the paper transported by the transport roller driven by the drive output gear. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-023983 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the image forming apparatus of Patent Document 1, the drive input gear, first output gear, counter gear, second output gear, drive output gear, etc., which are components for switching the rotation direction of the transport roller, are arranged side by side on the same plane on one surface of a plate-shaped mounting frame. Therefore, in order to realize a configuration for switching the rotation direction of the transport roller, a fixing member with a large area is required to arrange many gears on the same plane, which poses a problem in that it is difficult to reduce the size of the transport device to be incorporated into the image forming apparatus.

[0006] The object of the present disclosure is to provide a conveying device equipped with one electric motor, in which a rotation direction switching unit that switches the rotation direction of a conveying roller that conveys paper is realized with a structure suitable for miniaturization, and an image forming apparatus equipped with such a conveying device. [Means for solving the problem]

[0007] A conveying device according to one embodiment of the present disclosure has an electric motor, an input gear that rotates in response to the rotational force of the electric motor, a first carrier that rotates in a first direction in response to the rotational force of the input gear, a second carrier that rotates in a second direction opposite to the first direction in response to the rotational force of the input gear, and an output gear that rotates in either the first direction or the second direction in response to either the rotational force of the first carrier or the rotational force of the second carrier, the rotation centers of the input gear, first carrier, second carrier, and output gear being arranged on a straight line, a rotation direction switching unit that selects either the rotational force of the first carrier or the rotational force of the second carrier and transmits it to the output gear, and a conveying roller that rotates in response to the rotational force of the output gear and conveys paper. [Brief description of the drawings]

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant explanations are omitted. Also, the embodiments described below do not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the embodiments are essential as the solution means of the present disclosure.

[0010] <Image Forming Apparatus> 1 is a schematic cross-sectional view showing the internal structure of an image forming apparatus 100 according to the present disclosure. The image forming apparatus 100 is, for example, a multifunction machine having a copying function, a printer function, a scanner function, a facsimile function, etc., and forms a multicolor or monochrome image on printing paper by electrophotography. Note that the image forming apparatus 100 according to the present disclosure is not limited to a multifunction machine, and may be, for example, a printing machine having only a printer function.

[0011] The image forming apparatus 100 includes, for example, an apparatus main body 101 including a housing that houses each component constituting the image forming apparatus 100, and an image reading device 102 disposed above the apparatus main body 101. The image reading device 102 includes a document feeder that automatically feeds documents one by one, and an image reading unit that reads an image of the document, and generates image data based on the image of the document read by the image reading unit.

[0012] The apparatus main body 101 includes a control unit 103, an image forming unit 104, an automatic paper feed tray 111, a manual paper feed tray 112, a conveying device 200, a paper output tray 113, and guide rollers 114. The image forming unit 104 includes a photosensitive unit 105, an exposure unit 106, a developing unit 107, an intermediate transfer unit 108, a secondary transfer roller 109, a fixing unit 110, and the like.

[0013] The control unit 103 is a device that controls the image forming apparatus 100. The control unit 103 is composed of a microcontroller and peripheral circuits. The microcontroller includes a processor and a memory. The processor executes a control program stored in the memory to operate the microcontroller and peripheral circuits as the control unit 103. All or part of the processing performed by the microcontroller may be performed by a dedicated electronic circuit. The control unit 103 includes a communication unit that receives data, signals, and the like from the outside. The control unit 103 transmits various data such as images, control signals, and the like to each unit and device included in the image forming apparatus 100 in response to an input operation by a user, reception of data from the outside, and the like, and causes the image forming apparatus 100 to perform various operations.

[0014] The photosensitive unit 105 includes a cylindrical base body having conductivity and a photosensitive layer provided on the outer side of the base body. The photosensitive layer exhibits insulating properties in a state where no light is irradiated, and the region irradiated with light exhibits conductivity. The circumferential surface of the photosensitive layer is charged to a predetermined potential. The photosensitive unit 105 has a rotation axis (not shown) along the axis and rotates about the rotation axis by a motor (not shown).

[0015] The exposure unit 106 irradiates light for exposing the circumferential surface of the photosensitive layer of the photosensitive unit 105. Based on the image data transmitted from the control unit 103, the exposure unit 106 irradiates the circumferential surface of the photosensitive layer of the photosensitive unit 105 with light for forming an image based on the image data. The circumferential surface of the photosensitive unit 105 charged by the light irradiated by the exposure unit 106 is exposed, and an electrostatic latent image corresponding to the image data is formed on the circumferential surface of the photosensitive layer of the photosensitive unit 105.

[0016] The developing unit 107 supplies toner onto the circumferential surface of the photosensitive layer of the photosensitive unit 105 and develops the electrostatic latent image on the circumferential surface of the photosensitive unit 105 to form a toner image. The present disclosure exemplifies an image forming apparatus 100 capable of printing a full-color image. By overlapping monochromatic images corresponding to each of the four colors of cyan, magenta, yellow, and black, full-color image printing is realized. Therefore, the image forming apparatus 100 includes four photosensitive units 105, four exposure units 106, and four developing units 107 corresponding to each of the above four colors. For example, each of the four photosensitive units 105 and the four developing units 107 has the same structure, and only the color of the toner supplied by the developing unit 107 to the photosensitive unit 105 is different. Although not shown in the present disclosure, an image forming apparatus capable of printing a monochrome image is composed only of a photosensitive unit, an exposure unit, and a developing unit corresponding to black, unlike full-color.

[0017] The intermediate transfer unit 108 is disposed above the four photosensitive units 105. The intermediate transfer unit 108 is an integrated unit including four intermediate transfer rollers corresponding to the four photosensitive units 105, an intermediate transfer belt onto which the toner image of the photosensitive unit 105 is transferred by the intermediate transfer rollers, a driving roller for stretching and rotationally driving the intermediate transfer belt, a tension roller, and the like. The intermediate transfer rollers are pivotally supported by the intermediate transfer unit 108 such that the intermediate transfer belt rotates therewith.

[0018] When current is supplied to the intermediate transfer rollers, a transfer electric field is formed between the photosensitive unit 105 and the intermediate transfer belt at the position of the intermediate transfer rollers. By the action of the transfer electric field, the toner image developed on the circumferential surface of the photosensitive unit 105 is transferred onto the intermediate transfer belt. By each of the four intermediate transfer rollers, toner images corresponding to each of the four colors of cyan, magenta, yellow, and black are sequentially transferred and superimposed onto the intermediate transfer belt, and a full-color toner image is formed on the intermediate transfer belt.

[0019] The secondary transfer roller 109 is a member for transferring the toner image onto the printing paper, and is disposed, for example, in contact with the intermediate transfer belt of the intermediate transfer unit 108. The printing paper supplied from the automatic paper feed tray 111 or the manual paper feed tray 112 is conveyed by a plurality of rollers and passes between the secondary transfer roller 109 and the intermediate transfer belt. When the printing paper passes between the secondary transfer roller 109 and the intermediate transfer belt, the toner image formed on the intermediate transfer belt is transferred onto one surface of the printing paper. The toner image transferred onto the printing paper is heated and pressure-bonded by a fixing unit 110 including a heating roller, a pressure roller, and the like, and is fixed onto the printing paper. As described above, the image forming unit 104 prints an image onto one surface of the printing paper based on the received image data.

[0020] The print paper, which has completed printing on one side, is transported to a transport device 200 provided between the fixing unit 110 and the paper output tray 113. The print paper is sandwiched between a transport roller 203 included in the transport device 200 and a guide roller 114 arranged opposite the transport roller 203. As will be described in detail later, the transport roller 203 is rotated by a driving force transmitted from an electric motor 201 included in the transport device 200. The guide roller 114 is rotatable by a rotary shaft, and rotates following the transport roller 203.

[0021] When the print settings specified by the user specify single-sided printing, in which an image is formed on only one side of the print paper, the transport rollers 203 rotate in a direction to transport the print paper toward the paper output tray 113. The print paper sandwiched between the transport rollers 203 and the guide rollers 114 is transported toward the paper output tray 113 and output onto the paper output tray 113.

[0022] When the print settings specified by the user specify double-sided printing in which images are formed on both sides of the print paper, the print paper on which printing on one side has been completed is conveyed in a direction in which it is sent back to the device body 101 by reversing the rotation direction of the conveyance roller 203 from a state in which it is sandwiched between the conveyance roller 203 and the guide roller 114. The print paper sent back to the device body 101 is turned over inside the device body 101, and then conveyed again between the image forming unit 104 and the secondary transfer roller 109, where the toner image is transferred to the other side. The toner image transferred to the other side of the print paper is fixed to the print paper by the fixing unit 110. The print paper on which images have been formed on both sides is conveyed again to the conveyance device 200, and is discharged onto the paper discharge tray 113 by rotating the conveyance roller 203 in a direction in which the print paper is conveyed toward the paper discharge tray 113. As described above, the transport device 200 can switch back the print paper by changing the rotation direction of the transport roller 203, thereby enabling double-sided printing.

[0023] <Embodiment 1> Next, the configuration of the conveying device 200 according to the first embodiment of the present disclosure will be described. Fig. 2 is a schematic perspective view of the conveying device 200 according to the first embodiment. Fig. 3 is a schematic side view of the conveying device 200 according to the first embodiment. Note that Figs. 2 and 3 also show a guide roller 114 provided in the device main body 101 and arranged opposite the conveying roller 203.

[0024] <Conveyor equipment> The conveying device 200 includes an electric motor 201, a transmission gear 204, a rotational direction switching unit 202, and conveying rollers 203, and is an integrated device in which these are arranged and fixed on one surface of a plate-shaped fixed frame 205. The electric motor 201 is the drive source for the conveying rollers 203, and the rotational force of the rotational shaft of the electric motor 201 is transmitted to the conveying rollers 203 via the rotational direction switching unit 202. A plurality of transmission gears 204 are provided between the electric motor 201 and the rotational direction switching unit 202, and each of the fixed shafts of the plurality of transmission gears 204 is fixed to the fixed frame 205. The rotational force of the rotational shaft of the electric motor 201 is transmitted to an input outer gear unit 301 of the rotational direction switching unit 202 via the plurality of transmission gears 204. As will be described in more detail below, the rotational direction switching unit 202 transmits the rotational force of the electric motor 201 to the transport roller 203 via the output external gear unit 602 to rotate it, and can also select and switch the rotational direction of the transport roller 203 between a rotational direction that transports the print paper toward the output tray 113, and a rotational direction that transports the print paper toward the device main body 101.

[0025] In the first embodiment, the case where there are two transmission gears 204 is illustrated, but the present disclosure is not limited to this configuration, and any number of transmission gears 204 may be used. Alternatively, the rotation shaft of the electric motor 201 may be in direct contact with the rotation direction switching unit 202 without providing the transmission gear 204, and the rotational force may be directly transmitted from the electric motor 201 to the rotation direction switching unit 202. The diameter of the transmission gear 204 may be changed to any value depending on conditions such as the rotation speed of the electric motor 201, the diameter of the rotation direction switching unit 202, and the transport speed of the print paper by the transport roller 203.

[0026] Further, the configuration for transmitting the rotational force from the electric motor 201 to the rotation direction switching unit 202 does not necessarily have to be by gears. For example, the rotating shafts of the input outer gear portion 301 and the electric motor 201 may be used as pulleys respectively, and the rotational force may be transmitted by a belt spanned between these multiple pulleys, or the pulleys and the belt may be replaced with sprockets and a chain. Similarly, the configuration for transmitting the rotational force from the rotation direction switching unit 202 to the conveying roller 203 does not necessarily have to be by gears. For example, the rotating shafts of the output outer gear portion 602 and the conveying roller 203 may be used as pulleys respectively, and the rotational force may be transmitted by a belt spanned between these multiple pulleys, or the pulleys and the belt may be replaced with sprockets and a chain. Therefore, in the drawings of the present disclosure, the illustration of gear teeth is omitted on the circumferential surfaces of the rotating shaft of the electric motor 201, the circumferential surface of the transmission gear 204, the circumferential surface of the input outer gear portion 301, the circumferential surface of the output outer gear portion 602, and the circumferential surface of the gear portion fixed to one end of the rotating shaft of the conveying roller 203, which can be replaced with pulleys or sprockets.

[0027] FIG. 4 is a schematic perspective view of a part of the conveying device 200 according to Embodiment 1 cut away. More specifically, in FIG. 4, a part of the rotation direction switching unit 202 included in the conveying device 200 is cut away to show a part of the internal structure. Also, in FIG. 4, the illustration of the fixed frame 205 is omitted.

[0028] <Rotation direction switching unit> FIG. 5 is a schematic perspective view of a part of the rotation direction switching unit 202 according to Embodiment 1 cut away. In FIG. 5, a part of the input gear 300, the second carrier 500, and the output gear 600 are cut away to show the internal structure of the rotation direction switching unit 202. FIGS. 6 and 7 are exploded perspective views of the rotation direction switching unit 202 according to Embodiment 1. More specifically, FIG. 6 is an exploded perspective view of the rotation direction switching unit 202 from the perspective with the first carrier 400 on the front side, and FIG. 7 is an exploded perspective view of the rotation direction switching unit 202 from the perspective with the input gear 300 on the front side. FIG. 8 is a cross-sectional view taken along the VIII-VIII section of FIG. 5.

[0029] As shown in FIGS. 5 to 8, the rotation direction switching unit 202 includes an input gear 300, a first carrier 400, a second carrier 500, and an output gear 600. These four components are combined so that their rotation centers are aligned in a straight line and integrated. In other words, the four gears of the input gear 300, the first carrier 400, the second carrier 500, and the output gear 600 are provided in a straight line, and their rotation centers coincide.

[0030] <Fixed shaft> In Embodiment 1, for example, as shown in FIGS. 5 to 8, the rotation direction switching unit 202 includes a fixed shaft 700 passing through the rotation centers of the input gear 300, the first carrier 400, the second carrier 500, and the output gear 600. An input gear shaft hole 303, which is a cylindrical hole for receiving the fixed shaft 700, is provided at the rotation center of the input gear 300. Also, a first carrier shaft hole 403, which is a cylindrical hole for receiving the fixed shaft 700, is provided at the rotation center of the first carrier 400. One end of the fixed shaft 700 in the axial direction is fixed to, for example, the fixed frame 205. Thereby, as shown in FIG. 8, the input gear 300 and the first carrier 400 use the fixed shaft 700 as a support shaft, and their rotation centers are aligned on a straight line that is the central axis of the fixed shaft 700. Although it will be described in detail later, as shown in FIG. 8, the second carrier 500 and the output gear 600 axially sandwiched between the input gear 300 and the first carrier 400 also have their rotation centers aligned on a straight line that is on the central axis of the fixed shaft 700.

[0031] <Input gear> As shown in FIGS. 4 and 5, the input gear 300 is, for example, a two-stage stepped gear, and has a first-stage input external gear portion 301 provided with an engagement structure for receiving the rotational force of the electric motor 201 on its circumferential surface, and a second-stage gear that protrudes from the axial side surface of the input external gear portion 301 and has a smaller diameter than the input external gear portion 301, which is an input sun gear portion 302 for transmitting the rotational force to the first carrier 400 and the second carrier 500. Further, the input gear 300 has an input gear shaft portion 304, which is a cylindrical portion having a smaller diameter than the input external gear portion 301, between the input external gear portion 301 and the input sun gear portion 302 in the axial direction. As shown in FIG. 4, due to the rotational force of the electric motor 201, the input gear 300 rotates in a predetermined first direction about the fixed shaft 700. In FIG. 4, the predetermined first direction in which the input gear 300 rotates is referred to as the input rotation direction. Also in the following description, the first direction will be referred to as the input rotation direction.

[0032] <Second carrier> As shown in FIGS. 6 and 8, the second carrier 500 is a disk-shaped member and has a second planetary gear 510, which is a gear rotatably provided on one end surface in the axial direction. For example, a second planetary boss 511, which is a cylindrical structure protruding from one end surface in the axial direction of the second carrier 500, is provided, and the second planetary gear 510 is pivotally supported thereby. Further, the second carrier 500 is provided with a second carrier shaft hole 503, which is a cylindrical hole penetrating the second carrier 500 in the axial direction. As can be seen from FIG. 8, the second carrier shaft hole 503 receives the input gear shaft portion 304, and the second carrier 500 can rotate about the input gear shaft portion 304. Furthermore, the second planetary gear 510 meshes with a partial region on the side closer to the input gear shaft portion 304 in the axial direction of the input sun gear portion 302, and transmits the rotation of the input sun gear portion 302 to the second carrier 500.

[0033] <First carrier> As shown in FIGS. 7 and 8, the first carrier 400 is a disk-shaped member and includes a first planetary gear 410 which is a gear rotatably provided on one end face in the axial direction, and an intermediate planetary gear 420 which is a gear rotatably provided on one end face in the axial direction and meshes with the first planetary gear 410. For example, a first planetary boss 411 and an intermediate planetary boss 421 in the form of a cylindrical structure protruding from one end face in the axial direction of the first carrier 400 are provided, and the first planetary gear 410 and the intermediate planetary gear 420 are pivotally supported. Further, the first carrier 400 is provided with a first carrier shaft hole 403 which is a cylindrical hole penetrating the first carrier 400 in the axial direction.

[0034] As can be seen from FIG. 8, the first carrier shaft hole 403 receives the fixed shaft 700, and the first carrier 400 rotates about the fixed shaft 700. Further, the first planetary gear 410 meshes with a partial region on the side far from the input gear shaft portion 304 in the axial direction of the input sun gear portion 302, and transmits the rotation of the input sun gear portion 302 to the first carrier 400. As shown in FIG. 8, in the axial direction, the region where the input sun gear portion 302 meshes with the first planetary gear 410 and the region where the input sun gear portion 302 meshes with the second planetary gear 510 are separated. Thereby, in the axial direction, the first planetary gear 410 and the second planetary gear 510 arranged adjacent to each other are prevented from interfering with each other.

[0035] <Output gear> As shown in FIGS. 5 to 8, the output gear 600 is sandwiched between the first carrier 400 and the second carrier 500 in the axial direction. The output gear 600 is an internal gear having gear teeth arranged inside a cylindrical member, and has an output internal gear portion 601 on its inner circumferential surface. As can be seen from FIGS. 5, 7, and 8, the intermediate planet gear 420 meshes with a partial region on the side closer to the first carrier 400 of the output internal gear portion 601 in the axial direction. Also, as can be seen from FIGS. 5, 6, and 8, the second planet gear 510 meshes with a partial region on the side closer to the second carrier 500 of the output internal gear portion 601 in the axial direction. As shown in FIG. 8, in the axial direction, the region where the output internal gear portion 601 meshes with the intermediate planet gear 420 and the region where the output internal gear portion 601 meshes with the second planet gear 510 are separated. Thereby, in the axial direction, the intermediate planet gear 420 and the second planet gear 510 arranged adjacent to each other are prevented from interfering with each other.

[0036] <Details of the Movements of Each Gear and Each Carrier> FIG. 9 is a cross-sectional view of the IX-IX cross-section of FIG. 8, and FIG. 10 is a cross-sectional view of the X-X cross-section of FIG. 8. FIG. 9 illustrates the transmission of the rotational force in the input sun gear portion 302, the first carrier 400, and the output gear 600 of the rotation direction switching portion 202. Also, FIG. 10 illustrates the transmission of the rotational force in the input sun gear portion 302, the second carrier 500, and the output gear 600 of the rotation direction switching portion 202. Although details will be described later, in FIGS. 9 and 10, in order to show the positions of the engagement devices 800 that stop the rotations of the first carrier 400 and the second carrier 500, they are partially represented in a side view.

[0037] <Details of the Movements of the Input Gear and the First Carrier> As shown in FIGS. 8 and 9, the first carrier 400 has a first planetary gear 410 that meshes with the input sun gear portion 302 and an intermediate planetary gear 420 that meshes with the first planetary gear 410 and the output internal gear portion 601, and receives the rotational force of the input gear 300 via the input sun gear portion 302. When the rotational force of the input sun gear portion 302 is transmitted to the first planetary gear 410 and the intermediate planetary gear 420, the first planetary gear 410 and the intermediate planetary gear 420 revolve around the input sun gear portion 302 between the output internal gear portion 601 and the input sun gear portion 302. Thereby, the first carrier 400 rotates around the input sun gear portion 302.

[0038] In Embodiment 1, the first carrier 400 has two-stage planetary gears of the first planetary gear 410 and the intermediate planetary gear 420. Thereby, the input rotation direction in which the input sun gear portion 302 rotates and the first carrier rotation direction in which the first carrier 400 rotates are opposite to each other. In other words, if the input rotation direction, which is the rotation direction of the input gear 300, is defined as the first direction, the first carrier 400 rotates in the second direction, which is the direction opposite to the first direction.

[0039] In Embodiment 1, the first carrier 400 is illustrated as having two first planetary gears 410 and two intermediate planetary gears 420 arranged along the circumferential direction. However, the number of the first planetary gears 410 and the intermediate planetary gears 420 may be at least one each, and may be three or more each. By having a plurality of first planetary gears 410 and a plurality of intermediate planetary gears 420, the rotation of the first carrier 400 due to the rotational force of the input sun gear portion 302 can be stabilized.

[0040] <Details of Movements of Input Gear and Second Carrier> 8 and 10 , the second carrier 500 has a second planetary gear 510 that meshes with the input sun gear portion 302 and the output internal gear portion 601, and receives the rotational force of the input gear 300 via the input sun gear portion 302. When the rotational force of the input sun gear portion 302 is transmitted to the second planetary gear 510, the second planetary gear 510 revolves around the input sun gear portion 302 between the output internal gear portion 601 and the input sun gear portion 302. This causes the second carrier 500 to rotate around the input sun gear portion 302. Therefore, the center of rotation of the second carrier 500, like the centers of rotation of the input gear 300 and the first carrier 400, is on a straight line that is the central axis of the fixed shaft 700.

[0041] In the first embodiment, the second carrier 500 has a single-stage planetary gear of the second planetary gear 510, so that the input rotation direction in which the input sun gear portion 302 rotates is the same as the second carrier rotation direction in which the second carrier 500 rotates. In other words, if the input rotation direction, which is the rotation direction of the input gear 300, is defined as a first direction, the second carrier 500 also rotates in the first direction.

[0042] As described above, the first planetary gear 410, the intermediate planetary gear 420, and the second planetary gear 510 are arranged in the axial direction so as not to interfere with each other, and therefore the first carrier 400 and the second carrier 500 also do not interfere with each other and can freely rotate in the first direction and the second direction, which are different from each other.

[0043] In the first embodiment, the second carrier 500 has two second planetary gears 510 arranged in the circumferential direction, but the number of second planetary gears 510 may be at least one, or may be three or more. By having multiple second planetary gears 510 in the second carrier 500, the rotation of the second carrier 500 due to the rotational force of the input sun gear portion 302 can be stabilized.

[0044] <When stopping the transport rollers> 4, 9, and 10 show the state of the rotation direction switching unit 202 when the rotation of the transport roller 203 is stopped. As shown in Fig. 9, the rotational force of the electric motor 201 transmitted from the input sun gear unit 302 is entirely used for the revolution of the first carrier 400 via the first planetary gear 410 and the intermediate planetary gear 420. Therefore, when the first carrier 400 can rotate freely, the rotational force of the input sun gear unit 302 is not transmitted to the output internal gear unit 601 of the output gear 600, and the output gear 600 does not rotate.

[0045] 10, the rotational force of the electric motor 201 transmitted from the input sun gear section 302 is entirely used for the revolution of the second carrier 500 via the second planetary gear 510. Therefore, when the second carrier 500 can freely revolve, the rotational force of the input sun gear section 302 is not transmitted to the output inner gear section 601 of the output gear 600, and the output gear 600 does not rotate. Therefore, no rotational force is transmitted from either the first carrier 400 or the second carrier 500 to the output gear 600, and the output gear 600 is in a stopped state without rotating. Therefore, when the second carrier 500 can freely rotate, the rotational force of the input sun gear section 302 is not transmitted to the output inner gear section 601 of the output gear 600, and the output gear 600 does not rotate. As described above, when both the first carrier 400 and the second carrier 500 are revolving, the output gear 600 does not rotate, and the transport roller 203 stops.

[0046] <When rotating the transport roller> 11 and 12 are diagrams showing a case where print paper is transported by rotating the transport roller 203 according to embodiment 1. As will be described in detail later, in the rotation direction switching unit 202 of embodiment 1, the rotation direction of the output gear 600 can be selected by selectively stopping the rotation of the first carrier 400 and the second carrier 500, and thereby switching the rotation of the transport roller 203, making it possible to change the direction in which the print paper is transported to any direction.

[0047] <Engagement device> In Embodiment 1, as a mechanism for selectively stopping the rotation of the first carrier 400 and the second carrier 500, the engagement device 800 included in the rotation direction switching unit 202 is exemplified. As shown in FIGS. 2 to 4 and FIGS. 9 to 12, the engagement device 800 includes a first engagement portion 801 having a claw shape at its tip and facing the circumferential surface of the first carrier 400, a second engagement portion 802 having a claw shape at its tip and facing the circumferential surface of the second carrier 500, a first drive portion 803 for driving the first engagement portion 801, and a second drive portion 804 for driving the second engagement portion 802.

[0048] As shown in FIG. 2, the first drive portion 803 is fixed to the fixed frame 205 so that the first engagement portion 801 faces the circumferential surface of the first carrier 400. The second drive portion 804 is fixed to the fixed frame 205 so that the second engagement portion 802 faces the circumferential surface of the second carrier 500. The first drive portion 803 can move to a position in contact with the circumferential surface of the first carrier 400 or a position separated from the circumferential surface of the first carrier 400. Further, the second engagement portion 802 is installed at a position facing the circumferential surface of the second carrier 500, and can move to a position in contact with the circumferential surface of the second carrier 500 or a position separated from the circumferential surface of the second carrier 500 by the second drive portion 804.

[0049] The first carrier 400 has a circumferential surface provided with a first engaged portion 401 with which the first engaging portion 801 can engage. The second carrier 500 has a circumferential surface provided with a second engaged portion 501 with which the second engaging portion 802 can engage. When the claw portion at the tip of the first engaging portion 801 engages with the first engaged portion 401, the first carrier 400 stops rotating, and when the claw portion at the tip of the second engaging portion 802 engages with the second engaged portion 501, the second carrier 500 stops rotating. In the first embodiment, the first engaged portion 401 is a plurality of first protruding portions 402 that protrude in the radial direction from the circumferential surface of the first carrier 400 and are aligned along the circumferential direction, and the second engaged portion 501 is a plurality of second protruding portions 502 that protrude in the radial direction from the circumferential surface of the second carrier 500 and are aligned along the circumferential direction. The greater the number of first protrusions 402 and second protrusions 502 arranged circumferentially, the shorter the time lag until the rotation of the first carrier 400 and the second carrier 500 is stopped, and the more quickly the rotation of the conveying roller 203 can be switched.

[0050] <When transporting print paper toward the output tray> FIG. 11 is a schematic perspective view showing the transport roller 203 according to the first embodiment transporting print paper to the paper output tray 113. As shown in FIG. 11, when the transport roller 203 transports print paper to the paper output tray 113, the first engaging portion 801 engages with the first engaged portion 401, stopping the rotation of the first carrier 400. This fixes the positions of the first planetary boss 411 and the intermediate planetary boss 421, and stops the orbital motion of the first planetary gear 410 and the intermediate planetary gear 420. Then, the rotational force of the input sun gear portion 302 is transmitted to the output internal gear portion 601 via the first planetary boss 411 and the intermediate planetary boss 421, causing the output gear 600 to rotate in a first output rotation direction. The first output rotation direction of the output gear 600 is the same as the input rotation direction, which is the rotation direction of the input gear 300. In other words, if the rotation direction of the input gear 300 is the first direction, the rotation direction of the output gear 600 is also the first direction.

[0051] On the circumferential surface of the output gear 600, an output external gear portion 602 for transmitting the rotational force to the conveying roller 203 is provided. The output external gear portion 602 meshes with a gear portion provided near one end in the axial direction of the rotation axis of the conveying roller 203. Thereby, the rotation axis of the conveying roller 203 that has received the rotational force of the output gear 600 rotates in the discharge rotation direction, which is the direction opposite to the first output rotation direction of the output gear 600. In Embodiment 1, the upstream side of the rotation in the discharge rotation direction is the side of the paper discharge tray 113, and the downstream side is the side of the apparatus main body 101. Therefore, the printing paper sandwiched between the conveying roller 203 rotating in the discharge rotation direction and the guide roller 114 is conveyed in the discharge direction, which is the direction toward the paper discharge tray 113, by the rotation of the conveying roller 203.

[0052] <When conveying the printing paper toward the apparatus main body> FIG. 12 is a schematic perspective view showing a case where the conveying roller 203 according to Embodiment 1 sends back the printing paper to the apparatus main body 101. As shown in FIG. 12, when the conveying roller 203 sends back the printing paper toward the apparatus main body 101, the second engaging portion 802 is engaged with the second engaged portion 501 to stop the rotation of the second carrier 500. Thereby, the position of the second planetary boss 511 is fixed, and the revolution of the second planetary gear 510 stops. Then, the rotational force of the input sun gear portion 302 is transmitted to the output internal gear portion 601 via the second planetary gear 510, and the output gear 600 rotates in the second output rotation direction. The second output rotation direction of the output gear 600 is the direction opposite to the input rotation direction, which is the rotation direction of the input gear 300. In other words, when the rotation direction of the input gear 300 is the first direction, the rotation direction of the output gear 600 is the second direction, which is the opposite of the first direction.

[0053] The rotation shaft of the transport roller 203 that receives the rotational force of the output gear 600 rotates in a reverse rotation direction that is opposite to the second output rotation direction of the output gear 600 and the discharge rotation direction. In the first embodiment, the upstream side of the rotation in the reverse rotation direction is the device body 101 side, and the downstream side is the paper output tray 113 side. Therefore, the print paper sandwiched between the transport roller 203 rotating in the reverse rotation direction and the guide roller 114 is transported in the direction toward the device body 101 by the rotation of the transport roller 203, and is sent back to the image forming unit 104, etc. through a transport path inside the device body 101.

[0054] As described above, the conveying device 200 of the first embodiment can change the conveying direction of the print paper by the conveying roller 203 by selectively stopping the rotation of the first carrier 400 and the second carrier 500, and can perform the switchback conveyance required for sending the print paper, for which printing on one side has been completed, back to the image forming unit 104 for double-sided printing, for example. Also, as can be seen from FIG. 3, the input gear 300, the first carrier 400, the second carrier 500, and the output gear 600 included in the rotation direction switching unit 202 can be arranged in a straight line along the central axis of the fixed shaft 700, so that when viewed from the axial direction, the installation area for fixing the rotation direction switching unit 202 to the fixed frame 205 can be made smaller than the ground contact area when the multiple gears and multiple carriers are arranged on a flat surface, making it easy to miniaturize the conveying device 200.

[0055] In the first embodiment, an example is given of a configuration in which when the rotation of the first carrier 400 is stopped, the transport roller 203 transports the printing paper to the paper discharge tray 113, and when the rotation of the second carrier 500 is stopped, the transport roller 203 sends the printing paper back to the apparatus main body 101. However, the present disclosure is not limited to such a configuration. For example, when the rotation of the second carrier 500 is stopped, the transport roller 203 may transport the printing paper to the paper discharge tray 113, and when the rotation of the first carrier 400 is stopped, the transport roller 203 may send the printing paper back to the apparatus main body 101. As long as the rotation directions of the transport roller 203 are opposite to each other when the first carrier 400 is stopped and when the rotation of the second carrier 500 is stopped, the relationship between the carrier to be stopped and the transport direction of the printing paper can be appropriately changed according to conditions such as the rotation direction of the rotation shaft of the electric motor 201, the number of transmission gears 204, and the setting of the transport direction of the printing paper with respect to the paper discharge tray 113 and the apparatus main body 101.

[0056] Also, in the first embodiment, an example is given of a configuration in which the first carrier 400 includes two types of planetary gears, i.e., the first planetary gear 410 and the intermediate planetary gear 420, and the second carrier 500 includes one type of second planetary gear 510. However, the present disclosure is not limited to such a configuration. As long as the rotation directions of the first carrier 400 and the second carrier 500 are opposite to each other, for example, the first carrier 400 may include one type of planetary gear, and the second carrier 500 may include two types of planetary gears.

[0057] Furthermore, regarding the configuration for stopping the rotation of the first carrier 400 and the second carrier 500, the present disclosure is not limited to the configuration of the engagement device 800 described above. For example, a configuration may be used in which brake shoes are pressed against the circumferential surfaces of the first carrier 400 and the second carrier 500 to brake the rotation of the first carrier 400 and the second carrier 500 by frictional force.

[0058] <Control unit> 13 is a block diagram showing a portion of image forming apparatus 100 according to the first embodiment. In conveying device 200, the rotational force of electric motor 201 is transmitted to first carrier 400 and second carrier 500 via input gear 300 of rotational direction switching unit 202. Control unit 103 controls rotational direction switching unit 202 to select the rotational force of either first carrier 400 or second carrier 500 and transmit it to output gear 600, thereby selecting the direction in which print paper is conveyed by conveying roller 203. In the first embodiment, control unit 103 controls engagement device 800 to stop rotation of either first carrier 400 or second carrier 500.

[0059] As described above, print paper that has completed printing on one side by the image forming unit 104 is transported to the transport device 200. At that point, the control unit 103 controls the transport roller 203 to transport the print paper in a direction toward the paper output tray 113. In the first embodiment, the control unit 103 controls the engagement device 800 to stop the rotation of the first carrier 400, so that the transport roller 203 rotates in the discharge rotation direction, as shown in FIG. 11 . As a result, the print paper is transported to a position where it is sandwiched between the transport roller 203 and the guide roller 114.

[0060] When the print settings specified by the user specify single-sided printing, which forms an image on only one side of the print paper, the control unit 103 controls the transport roller 203 to continue rotating in the discharge rotation direction. In the first embodiment, the control unit 103 controls the engagement device 800 to continue stopping the rotation of the first carrier 400. As a result, the print paper sandwiched between the transport roller 203 and the guide roller 114 is transported in the discharge direction toward the paper output tray 113 and is output onto the paper output tray 113. This completes the printing operation when single-sided printing is specified.

[0061] On the other hand, if the print settings specified by the user specify double-sided printing, which forms images on both sides of the print paper, the control unit 103 controls the transport roller 203 to temporarily stop rotation after the print paper is partially ejected while sandwiched between the transport roller 203 and the guide roller 114. In the first embodiment, the control unit 103 releases the engagement device 800 from stopping the rotation of the first carrier 400. This stops the rotation of the transport roller 203, and the transport of the print paper is temporarily stopped while the print paper is sandwiched between the transport roller 203 and the guide roller 114.

[0062] Next, the control unit 103 controls the transport roller 203 to rotate in a reverse rotation direction, which is opposite to the ejection rotation direction. In the first embodiment, as shown in FIG. 12, the control unit 103 controls the engagement device 800 to stop the rotation of the second carrier 500. As a result, the print paper sandwiched between the transport roller 203 and the guide roller 114 is transported in a direction toward the device main body 101, which is the direction opposite to the ejection direction, and is sent back to the device main body 101. The print paper sent back to the device main body 101 is turned over inside the device main body 101 and then returned to the image forming unit 104, where the toner image is transferred to the other side of the print paper. The toner image transferred to the other side of the print paper is fixed to the print paper by the fixing unit 110. The print paper with images formed on both sides is transported back to the transport device 200.

[0063] When the double-sided printed print sheet is transported to the transport device 200, the control unit 103 controls the transport roller 203 to transport the print sheet in a direction toward the paper output tray 113. Therefore, in the first embodiment, after the print sheet is sent back to the device main body 101, and before the double-sided printed print sheet is transported again to the transport device 200, the control unit 103 releases the engagement device 800 from stopping the rotation of the second carrier 500 and controls the first carrier 400 to stop rotation. As a result, the transport roller 203 rotates in the discharge rotation direction, and the print sheet is transported to a position where it is sandwiched between the transport roller 203 and the guide roller 114.

[0064] When the printed paper printed on both sides is conveyed, the control unit 103 controls the conveyance roller 203 to continue rotating in the discharge rotation direction. In Embodiment 1, the control unit 103 controls the engagement device 800 to continue stopping the rotation of the first carrier 400. Thereby, the printed paper sandwiched between the conveyance roller 203 and the guide roller 114 is conveyed in the discharge direction toward the discharge tray 113 and discharged onto the discharge tray 113. As described above, the printing operation when double-sided printing is specified is completed. As described above, by the control unit 103 controlling the conveyance device 200, the printed paper can be switched back by changing the rotation direction of the conveyance roller 203, thereby enabling double-sided printing.

[0065] <Embodiment 2> FIG. 14 is a schematic perspective view of the conveyance device 200 according to Embodiment 2 of the present disclosure. The conveyance device 200 of Embodiment 2 is different from that of Embodiment 1 in the configuration related to the engagement device 800, and the configurations other than the engagement device 800 are the same as those of Embodiment 1. In FIG. 14, the illustration of the fixed frame 205 shown in FIG. 2 is omitted.

[0066] In the transport device 200 of Embodiment 2, in the engagement device 800, the first drive unit 803 and the second drive unit 804 are adjacent to each other in a direction parallel to the axial direction of the first carrier 400 and the second carrier 500. For example, as shown in FIG. 14, the first drive unit 803 and the second drive unit 804 having substantially the same shape are adjacent to each other in a direction parallel to the axial direction of the fixed shaft 700 located at the position of the rotation shafts of the first carrier 400 and the second carrier 500. For example, the second drive unit 804 is fixed to the first drive unit 803, and the first drive unit 803 is fixed to a fixed frame 205 (not shown). With this configuration, in the transport device 200 of Embodiment 1, as shown in FIG. 3, when viewed from the perspective of the axial direction, an installation area for fixing the first drive unit 803 and the second drive unit 804 to the fixed frame 205 requires an area corresponding to the two drive units, whereas in the transport device 200 of Embodiment 2, both the first drive unit 803 and the second drive unit 804 can be installed in an area corresponding to one drive unit, making it easier to miniaturize the transport device 200.

[0067] Also, in FIG. 14, the engagement device 800 includes two drive units, the first drive unit 803 and the second drive unit 804, and is illustrated as having two engagement units, the first engagement unit 801 and the second engagement unit 802, which are driven by the first drive unit 803 and the second drive unit 804, respectively. However, the first engagement unit 801 and the second engagement unit 802 can also be made into one engagement unit. For example, when viewed from the perspective of the axial direction, by adopting a configuration in which one claw portion corresponding to the first engagement unit 801 and the other claw portion corresponding to the second engagement unit 802 are provided at both ends of one engagement unit, with the center in the direction intersecting the axial direction of one engagement unit as the fulcrum, it is possible to select whether to engage one claw portion with the first engaged portion 401 to stop the rotation of the first carrier 400 or engage the other claw portion with the second engaged portion 501 to stop the rotation of the second carrier 500. In that case, the number of drive units and the wiring connecting the drive units and the control unit 103 can be reduced to one, making it possible to further miniaturize the transport device 200.

[0068] Note that the present disclosure is not limited to the configurations of the above-described embodiments and modifications, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments and modifications, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

Explanation of Reference Numerals

[0069] 100: Image forming apparatus 101: Apparatus main body 102: Image reading device 103: Control unit 104: Image forming unit 105: Photosensitive unit 106: Exposure unit 107: Developing unit 108: Intermediate transfer unit 109: Secondary transfer roller 110: Fixing unit 111: Automatic document feeder tray 112: Manual document feeder tray 113: Output tray 114: Guide roller 200: Conveying device 201: Electric motor 202: Rotation direction switching unit 203: Conveying roller 204: Transmission gear 205: Fixed frame 300: Input gear 301: Input external gear portion 302: Input sun gear portion 303: Input gear shaft hole 304: Input gear shaft portion 400: First carrier 401: First engaged portion 402: First protruding portion 403: First carrier shaft hole 410: First planetary gear 411: First planetary boss 420: Intermediate planetary gear 421: Intermediate planetary boss 500: Second carrier 501: Second engaged portion 502: Second protruding portion 503: Second carrier shaft hole 510: Second planet gear 511: Second planet boss 600: Output gear 601: Inner output gear part 602: Outer output gear part 700: Fixed shaft 800: Engagement device 801: First engagement part 802: Second engagement part 803: First drive part 804: Second drive part

Claims

1. An electric motor, an input gear that rotates upon receiving the rotational force of the electric motor, a first carrier that rotates in a first direction upon receiving the rotational force of the input gear, a second carrier that rotates in a second direction opposite to the first direction upon receiving the rotational force of the input gear, and an output gear that rotates in either the first direction or the second direction upon receiving either the rotational force of the first carrier or the rotational force of the second carrier, wherein the rotational centers of the input gear, the first carrier, the second carrier, and the output gear are provided on a straight line, and a rotation direction switching unit that selects either the rotational force of the first carrier or the rotational force of the second carrier and transmits it to the output gear, a conveying roller that rotates upon receiving the rotational force of the output gear and conveys paper, a conveying device comprising the same.

2. The first carrier has a first engaged portion, the second carrier has a second engaged portion, the rotation direction switching unit further has a first engaging portion that can engage with the first engaged portion and a second engaging portion that can engage with the second engaged portion, when transmitting the rotational force of the first carrier to the output gear, the second engaging portion is engaged with the second engaged portion to stop the rotation of the second carrier, when transmitting the rotational force of the second carrier to the output gear, the first engaging portion is engaged with the first engaged portion to stop the rotation of the first carrier, the conveying device according to Claim 1.

3. When the rotation of the first carrier is stopped, the output gear rotates in one of the first direction and the second direction, and when the rotation of the second carrier is stopped, the output gear rotates in the other of the first direction and the second direction, the conveying device according to Claim 2.

4. The first engaged portion is a plurality of first protrusions that protrude radially from the circumferential surface of the first carrier and are arranged along the circumferential direction, the second engaged portion is a plurality of second protrusions that protrude radially from the circumferential surface of the second carrier and are arranged along the circumferential direction, the conveying device according to Claim 2.

5. The rotation direction switching unit further has a first driving unit that drives the first engaging portion and a second driving unit that drives the second engaging portion, the first driving unit and the second driving unit are adjacent to each other in a direction parallel to the axial direction of the first carrier and the second carrier, the conveying device according to Claim 2.

6. The input gear has an input external gear portion that receives the rotational force of the electric motor, and an input sun gear portion that transmits the rotational force to the first carrier and the second carrier. The output gear has an output internal gear portion that receives the rotational force of either the first carrier or the second carrier. One of the first carrier and the second carrier has a first planetary gear that meshes with the input sun gear portion, and an intermediate planetary gear that meshes with the first planetary gear and the output internal gear portion. The other of the first carrier and the second carrier has a second planetary gear that meshes with the input sun gear portion and the output internal gear portion. The conveying device according to claim 1.

7. One of the first carrier and the second carrier has the plurality of first planetary gears and the plurality of intermediate planetary gears arranged along the circumferential direction. The other of the first carrier and the second carrier has the plurality of second planetary gears arranged along the circumferential direction. The conveying device according to claim 6.

8. One of the first carrier and the second carrier has a first planetary boss that pivotally supports the first planetary gear, and an intermediate planetary boss that pivotally supports the intermediate planetary gear. The other of the first carrier and the second carrier has a second planetary boss that pivotally supports the second planetary gear. The conveying device according to claim 6.

9. The input gear has an input gear shaft portion between the input external gear portion and the input sun gear portion in the axial direction. A second carrier shaft hole for receiving the input gear shaft portion is provided at the rotation center of the second carrier. The conveying device according to claim 6.

10. The conveying device further includes a fixed shaft passing through the rotation centers of the input gear, the first carrier, the second carrier, and the output gear. An input gear shaft hole for receiving the fixed shaft is provided at the rotation center of the input gear. A first carrier shaft hole for receiving the fixed shaft is provided at the rotation center of the first carrier. The conveying device according to claim 6.

11. An output external gear portion for transmitting the rotational force to the conveying roller is provided on the circumferential surface of the output gear. The conveying device according to claim 6.

12. The output gear is sandwiched between the first carrier and the second carrier in the axial direction. The conveying device according to claim 6.

13. The conveying device according to claim 1, and a control unit that controls the rotation direction switching unit. An image forming apparatus.

14. The image forming apparatus further includes an image forming unit that prints an image on the sheet, and a paper discharge tray that discharges the sheet on which the image is printed. When the rotation direction switching unit selects either one of the rotational forces of the first carrier and the second carrier and transmits it to the output gear, the conveyance roller conveys the sheet in the discharge direction for discharging the sheet to the paper discharge tray. When printing an image on both sides of the sheet, the control unit controls the rotation direction switching unit so as to transmit the other of the rotational forces of the first carrier and the second carrier to the output gear after discharging the sheet halfway, and conveys the sheet in a direction opposite to the discharge direction to return it to the image forming unit. The image forming apparatus according to claim 13.

Images