JP2008150183A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily remove a recording paper in contact with a transporting roller by rotating the transporting roller when a drive motor is not driven in an image forming device. <P>SOLUTION: A clutch mechanism 30 disposed in a power transmission path between the drive motor and the transporting roller comprises a drive gear 32 driven by the drive motor, a driven gear 33 driving the transporting roller, a clutch ring 34 disposed between the drive gear 32 and the driven gear 33, and a spring 35 biasing the clutch ring 34 toward the drive gear 32. When the drive motor is driven, the clutch ring 34 is slid toward the driven gear 33, the engagement teeth 34a, 34b formed thereon, respectively, are meshed with each other, and a drive force is transmitted from the drive gear 32 to the driven gear 33. When the drive motor is not driven, engagement teeth 34a, 33a are biased by the spring 35, and the meshing of the engagement teeth is released. Consequently, the drive gear 33 can be independently rotated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a recording sheet while conveying the recording sheet inside a casing.

  In the image forming apparatus, when the recording paper is transported inside the housing by the transport roller driven by the drive motor, the recording paper is poorly transported, such as being jammed on the transport path inside the housing. There are things to do. When a conveyance failure occurs, it is necessary to remove the recording paper remaining in the housing and return it to a printable state again. Here, when the conveyance roller is in a state of interlocking with the drive motor, if the recording paper in which conveyance is defective is in contact with the conveyance roller, the conveyance roller is difficult to rotate due to the resistance force of the drive motor. It is difficult to remove the paper. Therefore, conventionally, a clutch mechanism constituted by a planetary gear or the like is provided in the transmission path of the driving force from the driving motor to the conveying roller so that the conveying roller can freely rotate when not driven by the driving motor, The recording paper can be easily removed when the conveyance is poor.

  However, in the clutch mechanism as described above, if a drive failure occurs when the drive motor drives the transport roller, and the drive motor is released as it is, the clutch mechanism There is a problem in that the transmission path is maintained while being linked to the drive motor, and it is difficult to remove the recording paper due to the resistance force of the drive motor. Further, when a planetary gear that requires high component accuracy is used for the clutch mechanism, there is a problem that the manufacturing cost of the image forming apparatus increases.

  Here, Patent Document 1 discloses a configuration of an image forming apparatus in which a pressing member is used to press a pressing gear against a gear driving a heat roller when the driving motor is driven so that the driving force can be transmitted to the heat roller. It is shown. When the drive motor is not driven, the pressing gear is pushed back by the force of the spring so that the heat roller can freely rotate and the recording paper sandwiched between the heat rollers can be easily removed. It is configured. However, in this configuration, since the pressing gear itself moves in the thrust direction, friction is generated between the tooth surfaces of the gear meshing with the pressing gear, and the tooth surfaces may be damaged.

Patent Document 2 discloses a configuration of an image forming apparatus in which a connection between a driving motor and a conveyance roller is released by moving a gear using an actuator so that a recording sheet can be easily removed when conveyance is defective. However, in this configuration, an actuator is required to move the gear, so that the configuration of the image forming apparatus becomes complicated and the manufacturing cost increases. Patent Document 3 discloses a configuration of an image forming apparatus in which a ratchet mechanism is provided between a rotation shaft and a drive gear so that a recording sheet sandwiched between the rotation shafts can be pulled out in a predetermined direction. Yes. However, with this configuration, the rotation shaft can be rotated only when the recording paper is pulled out in one direction, and it is difficult to remove the recording paper depending on the state of the recording paper remaining inside the housing. There are cases.
JP-A-9-114287 Japanese Patent Laid-Open No. 10-265089 JP 2002-70981 A

  The present invention has been made in view of the above problems, and for example, without using a complicated structure such as a planetary gear, the transport roller can be rotated when the drive motor is not driven, An object of the present invention is to provide an image forming apparatus capable of easily removing a recording sheet in contact with a conveying roller.

  In order to achieve the above object, the invention of claim 1 includes a housing, a paper feed tray attached to the housing, on which recording paper is placed, a transport roller that rotates in contact with the recording paper, and the roller. A recording motor transport mechanism for transporting the recording paper placed on the paper feed tray on a predetermined transport path inside the housing; and An image forming unit that forms an image on a recording sheet conveyed by the recording sheet conveying mechanism; and a control unit that controls the drive motor and the image forming unit to form an image on the recording sheet. The mechanism is provided in a power transmission path for transmitting the driving force of the drive motor to the transport roller, and has a clutch mechanism for cutting and connecting the power transmission path between the drive motor and the transport roller. A forming device comprising: The latch mechanism includes a holding shaft supported by the housing, a driving gear that is rotatably held by the holding shaft and is driven in a predetermined rotating direction by the drive motor, and is rotatable by the holding shaft. A driven gear for rotating the conveying roller, and a clutch ring disposed between the driving gear and the driven gear so as to be rotatable and slidable in the direction of the rotation axis; A spring that is disposed between the clutch ring and the driven gear in a compressed state from a natural state and biases the clutch ring away from the driven gear by its restoring force; A plurality of square rib-shaped pressing teeth arranged on the circumference at predetermined intervals are formed on a portion of the driving gear that faces the clutch ring, and the pressing gear faces the pressing teeth in the clutch ring. Part Includes a plurality of transmission teeth formed so as to be able to contact the side portions of the plurality of pressing teeth, and a protrusion between the transmission teeth toward the drive gear in a predetermined rotation direction of the drive gear. A taper portion that is slidably contacted with the tip of the pressing tooth, and a portion of the driven gear that faces the clutch ring; A plurality of meshing teeth arranged on the circumference so as to be able to mesh with each other are formed at a portion facing the driven gear, and the meshing teeth of the clutch ring are directed toward a predetermined rotation direction of the driving gear. The toothed teeth of the driven gear are protruded toward the clutch ring toward the predetermined rotation direction of the driven gear. A saw with a small amount When the drive motor is driven, torque is applied to the drive gear so that the tip of the pressing tooth slides on the tapered portion, and the clutch ring compresses the spring. While sliding toward the driven gear, the meshing teeth of the clutch ring mesh with the meshing teeth of the driven gear so that the driven gear is interlocked with the driving gear, and the driving force motor When the driving motor is not driven, the clutch ring is separated from the driven gear by the restoring force of the spring, and the meshing teeth of the clutch ring and the driven gear are The meshing teeth with the meshing teeth are released, and the drive gear and the driven gear can be rotated independently of each other. Sometimes, in a state where the drive motor is not driven, but that is configured to be able to easily remove the recording sheet from the conveying path of the recording paper by rotating the conveying rollers.

  According to a second aspect of the present invention, there is provided a clutch mechanism that is provided in a power transmission path for transmitting the driving force of the drive motor to the transport roller, and that disconnects and connects the power transmission path between the drive motor and the transport roller. An image forming apparatus provided with a recording paper transport mechanism having a holding shaft supported by the housing, a holding shaft rotatably supported by the holding shaft, and a predetermined rotation by the drive motor A driving gear that is driven in a direction, a driven gear that is rotatably held by the holding shaft and that rotates in conjunction with the transport roller, and a rotation between the driving gear and the driven gear. A clutch ring that is slidable in the direction of its rotation axis, and is arranged in a compressed state between the clutch ring and the driven gear, and the clutch ring is A spring that urges the driven gear away from the driven gear, and when the driving motor is driven, torque is applied to the driving gear so that the clutch ring meshes with the driven gear. When the driven gear is interlocked with the driving gear, the driving force of the driving force motor is transmitted to the transport roller, and the driving motor is not driven, the restoring force of the spring causes the clutch ring to Is disengaged from the driven gear, the engagement of the clutch ring and the driven gear is released, and the driving gear and the driven gear can rotate independently of each other.

  According to a third aspect of the present invention, in the second aspect of the present invention, a plurality of pressing teeth arranged at predetermined intervals on a circumference are formed in a portion of the drive gear that faces the clutch ring. A portion of the clutch ring that faces the pressing teeth has a plurality of transmission teeth formed so as to be able to abut on the side portions of the plurality of pressing teeth, and a predetermined rotation of the drive gear between the transmission teeth. A taper portion is formed so that a protruding amount toward the driving gear in a moving direction is increased, and a tip portion of the pressing tooth is slidably contacted with the clutch ring of the driven gear. A plurality of meshing teeth arranged on the circumference so as to be able to mesh with each other are formed on the facing part and the part of the clutch ring facing the driven gear, and the meshing teeth of the clutch ring are: Predetermining the drive gear It is formed in a substantially saw-tooth shape so that the amount of protrusion toward the driven gear is increased in the rotation direction, and the meshing teeth of the driven gear are directed in a predetermined rotation direction of the driving gear, and the clutch It is formed in a substantially sawtooth shape so that the amount of protrusion toward the ring is small.

  According to the first aspect of the present invention, the clutch ring is provided between the driving gear and the driven gear, and the clutch ring is engaged with the driven gear when torque for driving the conveying roller by the driving motor is applied. When the motor and the transport roller are interlocked and the drive motor is not driven, the clutch ring is separated from the driven gear by the spring and the driven gear can be rotated independently of the drive gear. When this occurs, the recording paper can be easily removed by rotating the conveying roller. Since it is not necessary to use high-precision parts such as planetary gears for the clutch mechanism, the manufacturing cost of the image forming apparatus can be reduced. Further, since the meshing teeth of the driven gear and the meshing teeth of the clutch ring that are meshed with each other are formed in a substantially serrated shape, when the clutch ring slides and meshes with each other, the meshing teeth of the clutch ring and the driven gear Even if the phases of the meshing teeth are different from each other, the phases are matched as the meshing teeth come closer to each other, and the meshing teeth mesh smoothly and reliably, and the driving force can be reliably transmitted.

  According to the invention of claim 2, when the drive motor is not driven, the clutch ring is separated from the driven gear by the spring and the meshing is released, and the driven gear can be rotated independently of the driving gear. When a conveyance failure of the recording paper occurs, the recording paper can be easily removed by freely rotating the conveyance roller. Since it is not necessary to use high-precision parts such as planetary gears for the clutch mechanism, the manufacturing cost of the image forming apparatus can be reduced.

  According to the invention of claim 3, since the meshing teeth of the driven gear and the meshing teeth of the clutch ring that are meshed with each other are formed in a substantially sawtooth shape, when the clutch ring slides and the meshing teeth mesh with each other, Similarly, the meshing teeth mesh smoothly and reliably, and the driving force can be reliably transmitted.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an image forming apparatus according to this embodiment. The image forming apparatus 1 is a so-called laser beam printer, which is connected to, for example, an external personal computer, and forms an image on the recording paper P by electrophotography based on image data sent from the personal computer. (Print). The image forming apparatus 1 includes a paper feed cassette (paper feed tray) 110 that is disposed at the bottom of the housing 100 and on which the recording paper P is placed substantially horizontally, and is ejected from the housing 100 provided at the top of the housing 100. The recording paper P loaded thereon, the recording paper transport mechanism 20 that transports the recording paper P loaded in the paper feed cassette 110 into the housing 100, and the recording paper transport mechanism 20. An image forming unit 10 that forms an image on the recording paper P and an electronic circuit having, for example, a CPU, ROM, RAM, and the like, and controls the operation of each unit of the apparatus and prints the image on the recording paper P 40. An opening / closing lid 100a is pivotally supported on the rear surface of the housing 100 so as to be openable / closable with respect to the housing 100 by a shaft support portion 100b. The opening / closing lid 100a is opened as indicated by a two-dot chain line in the figure. As a result, the recording paper P remaining inside the housing 100 can be removed when the recording paper P is poorly transported, or the image forming unit 10 can be exposed to the outside to perform maintenance work or the like. ing. The paper feed cassette 110 is provided so as to be drawable with respect to the housing 100. The image forming apparatus 1 is configured such that the recording paper P can be loaded and placed by pulling out the paper feed cassette 110 from the housing 100. Instead of the paper feed cassette 110, a paper feed tray fixed to the housing 100 may be provided so that the recording paper P can be loaded from the outside.

  The recording paper transport mechanism 20 includes a pickup roller 21 disposed above the paper feed cassette 110, a transport roller 22 that transports the recording paper P inside the housing 100, and the recording paper P on the top of the housing 100. The transport roller 23 is disposed at the downstream end of the transport path, and includes a drive motor 25 that is driven by the control unit 50 to drive the transport rollers 22 and 23. The conveyance roller 23 is connected to the conveyance roller 22 through a gear or the like, and is configured such that when the driving force of the drive motor 25 is transmitted to the conveyance roller 22, the conveyance rollers 22 and 23 are driven in conjunction with each other. Has been. A recording paper guide 15 for changing the transport direction along the recording paper P is disposed on the upper and lower portions of the housing 100 on the back side. The recording paper P is transported by the recording paper transport mechanism 20 on a predetermined transport path constituted by the recording paper guide 15 and the like inside the housing 100. That is, the pick-up roller 21 abuts on the uppermost recording paper P placed on the paper feed cassette 110 and rotates to bring the recording paper P along the recording paper guide 15 into the housing 100. Feed inward. The fed recording paper P is transported to the image forming unit 10 by the transport roller 22, and after the image is formed by the image forming unit 10, the paper discharge unit 120 is transported by the transport roller 23 on the paper discharge unit 120 side. Discharged to the top.

  The image forming unit 10 includes a photosensitive drum 2 having a photosensitive layer formed on the surface, a cleaner 3, a charger (charging means) 4, a scan unit 5, a developing brush (developing device) 6, a transfer roller 7, and a transfer roller 7. On the other hand, the fixing roller 8 is disposed on the downstream side in the conveyance direction of the recording paper P. These photosensitive drums 2, rollers, and the like are arranged inside the casing 100 so that the main scanning direction substantially orthogonal to the conveyance direction of the recording paper P (indicated by an arrow A in the figure) is the longitudinal direction. ing.

  The cleaner 3 removes toner and paper powder before one stroke (one rotation) adhering to the surface of the photosensitive drum 2 and cleans the surface of the photosensitive drum 2. The charger 4 uniformly charges the surface of the photosensitive drum 2 cleaned by the cleaner 3. In this image forming apparatus 1, the photosensitive drum 2, the cleaner 3, and the charger 4 are all attached to a common housing as the photosensitive unit 50, and are exchangeably mounted inside the housing 100. That is, even when the number of times of cumulative printing increases and the photosensitive drum 2 reaches the end of its service life, it is possible to print again by replacing only the photosensitive unit 50 with another one.

  The scan unit 5 irradiates the laser beam L while scanning the surface of the photosensitive drum 2 charged by the charger 4, thereby forming a latent image on the surface of the photosensitive drum 2. The scan unit 5 is powered by a power supply device (not shown), and a drive voltage for emitting the laser beam L is applied by the power supply device. The developing brush 6 is detachably mounted inside the housing 100 as a toner cartridge 60 together with a toner tank 6a filled with toner, and the toner adheres to the surface of the photosensitive drum 2 where the latent image is formed. To form a toner image. When printing on the recording paper is repeated and the amount of toner in the toner tank 6a decreases, the printing can be further repeated by replacing the toner cartridge 60 with another one having a large amount of remaining toner. ing.

  The transfer roller 7 is provided so as to face the surface of the photosensitive drum 2 at a predetermined transfer position downstream of the developing brush 6 in the rotation direction of the photosensitive drum 2 (the direction of arrow T in the figure). The transfer roller 7 is attached to a roller holding member 71 fixed to the opening / closing lid 100a. The transfer roller 7 rotates while pressing the recording paper P against the surface of the photosensitive drum 2 to charge the surface of the recording paper P, and the toner image formed on the surface of the photosensitive drum 2 is transferred to the recording paper P. Transfer on top of. A transfer voltage for charging the surface of the recording paper P is applied to the transfer roller 7 from a power supply device. The recording paper P on which the image is formed on the surface by the transfer roller 7 is conveyed to the fixing roller 8. The fixing roller 8 fixes the toner by applying heat and pressure to the recording paper P while sandwiching the recording paper P between the fixing roller 8 and the pressing roller 8a disposed opposite thereto. Heat for fixing the toner is supplied from a heater (for example, a halogen lamp) built in the fixing roller 8. The heater generates heat when a fixing voltage is applied by the power supply device. The photosensitive drum 2, the transfer roller 7, the fixing roller 8, and the pressing roller 8 a are driven by the driving motor 25 so that the recording paper P is conveyed inside the housing 100 at a predetermined speed. It is configured.

  Here, in the image forming apparatus 1, the power transmission path is arranged between the drive motor 25 and the conveyance roller 22 in a power transmission path constituted by gears and the like, and the power transmission path is cut according to the drive torque by the drive motor 25. A clutch mechanism 30 configured to be connected is provided. Hereinafter, the configuration and operation of the clutch mechanism 30 will be described.

  2 and 3 (a) and 3 (b) show the clutch mechanism 30. FIG. The clutch mechanism 30 is driven by the holding shaft 31 supported by the housing 100, the drive gear 32 having a tooth surface 32 g to which the driving force from the driving motor 25 is transmitted, and driven by the driving motor 25, and the conveying roller 22. A driven gear 33 having a tooth surface 33g for transmitting force and driving the conveying roller 22, and a clutch ring 34 disposed so as to be sandwiched between the driving gear 32 and the driven gear 33; The coil spring 35 is disposed between the clutch ring 34 and the driven gear 33. The driving gear 32 and the driven gear 33 are pivotally supported on the holding shaft 31 so as to be rotatable about the holding shaft 31 as a rotation shaft. A groove 31 a is formed at the tip of the holding shaft 31. The clutch mechanism 30 is assembled by attaching a retaining clip (not shown) to the groove 31a in a state where the driving gear 32, the driven gear 33, the clutch ring 34, and the spring 35 are attached to the holding shaft 31.

  As shown in FIG. 3B, the drive gear 32 has a tooth surface 32g on the outer peripheral portion, and is arranged in a part facing the clutch ring 34 so as to be arranged at equal intervals on the circumference. Six pressing teeth 32b are provided. Further, a holding cylinder portion 32c having a predetermined thickness is formed at a portion closer to the holding shaft 31 than the pressing teeth 32b so as to protrude from the portion where the pressing teeth 32b are formed toward the clutch ring 34 side. . The pressing teeth 32b are formed in a square rib shape, for example, as shown in the figure. The drive gear 32 is driven by a drive motor 25 and is configured to rotate in a predetermined rotation direction indicated by an arrow R in the drawing.

  As shown in FIG. 3A, the driven gear 33 has a tooth surface 33 g at a part of the outer peripheral portion, and a plurality of meshes arranged on the circumference at a portion facing the clutch ring 34. It has teeth 33a. Of the side surface on which the meshing teeth 33a are provided, a portion closer to the outer peripheral portion than the meshing teeth 33a is configured to be substantially flat, and is configured such that one end portion of the spring 35 abuts on this site.

  4 (a) and 4 (b) show the clutch ring 34. FIG. In the present embodiment, the clutch ring 34 is mounted on the outer peripheral portion of the holding cylinder portion 32 c of the driving gear 32 between the driving gear 32 and the driven gear 33, and the rotation shaft of the driving gear 32 and the driven gear 33 is provided. It is arrange | positioned so that rotation is possible centering | focusing on the rotation axis | shaft which becomes coaxial. In a state where the driving gear 32 and the driven gear 33 are mounted on the holding shaft 31, a gap is provided between the driving gear 32 and the driven gear 33. The gap is slidable in the direction of the rotation axis. A meshing tooth 34 a that can mesh with the meshing tooth 33 a is formed at a portion of the clutch ring 34 that faces the meshing tooth 33 a of the driven gear 33. In addition, for example, six pieces formed on the circumference of the clutch ring 34 facing the pressing teeth 32b at substantially the same pitch as the pressing teeth 32b and capable of coming into contact with the side portions of the pressing teeth 32b. Transmission teeth 34b are formed. As shown in the figure, a tapered portion 34c is formed between the transmission teeth 34b so as to increase the amount of protrusion toward the drive gear 32 in the rotational direction R of the drive gear 32. .

  Here, in the image forming apparatus 1, the meshing teeth 33 a and 34 a formed on the driven gear 33 and the clutch ring 34 are each formed in a substantially sawtooth shape. The meshing teeth 34 a of the clutch ring 34 are formed in a substantially saw-tooth shape so that the amount of protrusion toward the driven gear 33 increases in the rotational direction R of the driving gear 32. The meshing teeth 33a of the driven gear 33 are substantially saw-toothed so that the amount of protrusion toward the clutch ring 34 becomes smaller in the rotational direction R of the driving gear 32, contrary to the meshing teeth 34a of the clutch ring 34. It is formed into a shape. Thereby, in a state where the meshing teeth 33a and 34a are meshed with each other, the driving torque in the rotation direction R can be transmitted from the clutch ring 34 to the driven gear 33.

  The spring 35 is disposed between the driven gear 33 and the clutch ring 34 in a compressed state as compared with the natural state. That is, since the spring 35 is disposed, the clutch ring 34 is biased toward the drive gear 32 by the restoring force of the spring 35.

  FIG. 5A shows a side cross section of the clutch mechanism 30 when the drive gear 32 is not driven by the drive motor 25. At this time, the clutch ring 34 is biased in a direction away from the driven gear 33 (in the direction of arrow B in the figure) by the restoring force of the spring 35, and the meshing teeth 34 a of the clutch ring 34 and the meshing teeth of the driven gear 33. The meshing with 33a is released, and the drive gear 32 and the driven gear 33 are rotatable independently of each other. At this time, the clutch ring 34 is stationary with the tip portion of the pressing tooth 32b in contact with the tapered portion 34c, and the clutch ring is pushed into the driving gear 32 by the spring 35. The side of 32b where the protruding amount of the tapered portion 34c is large is not in contact with the transmission tooth 34b.

  FIG. 5B shows a side cross-section of the clutch mechanism 30 when the drive motor 25 is driven and a drive torque in the rotation direction R is applied to the drive gear 32. In the present embodiment, since the clutch ring 34 is biased toward the drive gear 32 by the spring 35, a drive torque is applied to the drive gear 32, and the tip of the pressing tooth 32b slides on the tapered portion 34c. The clutch ring 34 is subjected to a force of sliding toward the driven gear 33 as indicated by an arrow F in the drawing. That is, when the drive motor 25 is driven, the clutch ring 34 slides toward the driven gear 33 while compressing the spring 35, and the meshing teeth 34 a of the clutch ring mesh with the meshing teeth 33 a of the driven gear 33. Further, since the drive gear 32 is driven in a state where the tip end portion of the pressing tooth 32b is in contact with the tapered portion 34c or in a state where the transmission tooth 34b is in contact with the side portion of the pressing portion 32b, the driving gear 32 and the clutch ring 34 are driven. Both rotate in the rotation direction R. Therefore, when the drive motor 25 is driven, the meshing teeth 33a and 34a mesh with each other, and the drive torque can be transmitted from the drive gear 32 to the driven gear 33 via the clutch ring 34. Is transmitted to the transport rollers 22 and 23, and the transport rollers 22 and 23 are driven. When the drive motor 25 stops and the drive torque is not applied to the drive gear 32 from the state where the drive motor 25 is driven and the clutch mechanism 30 is connected, the direction toward the driven gear 33 of the clutch ring 34 is reduced. Since the biasing force disappears, the clutch ring 34 is pushed back to the drive gear 32 by the restoring force of the spring 35, the meshing teeth 33a and 34a are disengaged, the clutch mechanism 30 is disconnected, and the drive gear 32 and the driven gear 33 are disengaged. And can be rotated independently of each other.

  As described above, in this embodiment, when the drive motor 25 is not driven, the driven gear 33 can be rotated independently of the drive gear 32. Therefore, when a conveyance failure of the recording paper P occurs, By rotating the transport rollers 22 and 23, it is possible to easily remove the recording paper P in which the transport failure has occurred. Since it is not necessary to use high-precision parts such as a planetary gear for the clutch mechanism 30, it is possible to reduce the manufacturing cost of the image forming apparatus 1. Further, since the meshing teeth 33a of the driven gear 33 and the meshing teeth 34a of the clutch ring 34 that are meshed with each other are formed in a substantially serrated shape, when the clutch ring 34 slides and the meshing teeth 33a and 34a mesh with each other, the clutch Even if the meshing teeth 34a of the ring 34 and the meshing teeth 33a of the driven gear 33 are different in phase, the meshing teeth 33a, 34a are in phase with each other, and the meshing teeth 33a, 34a mesh smoothly and reliably. The driving force can be transmitted reliably.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, the shape of the meshing teeth is not limited to the shape of the sawtooth as described above, and the meshing teeth on the clutch ring side and the meshing teeth on the driven gear side, such as a square rib shape and a mountain shape, are mutually connected. What is necessary is just to be comprised so that a driving force can be transmitted when it meshes | engages. Further, the clutch mechanism is not limited to the transport roller, and for example, a power transmission path from the drive motor to the photosensitive drum, transfer roller, fixing roller, and the like may be provided so that the clutch mechanism is provided for each roller. A plurality of sets may be provided. Furthermore, the image forming apparatus is not limited to the one that prints on the recording paper by the electrophotographic method, and may be configured to print by the inkjet method, for example.

1 is a side view showing an example of an image forming apparatus according to an embodiment of the present invention. The perspective view which shows the clutch mechanism of the said apparatus. (A) is a perspective view which shows the components structure of the said clutch mechanism, (b) is a perspective view which shows when (a) is seen from a different direction. (A) is a perspective view which shows the clutch ring of the said clutch mechanism, (b) is a perspective view which shows when (a) is seen from a different direction. (A) is a perspective view showing a side section when the driving force of the clutch mechanism is not transmitted, (b) is a perspective view showing a side section when the driving force of the clutch mechanism is transmitted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image forming part 15 Recording paper guide 20 Recording paper conveyance mechanism 22, 23 Conveyance roller 25 Drive motor 30 Clutch mechanism 31 Holding shaft 32 Drive gear 32b Pressing tooth 33 Driven gear 33a Engagement tooth 34 Clutch ring 34a Engagement tooth 34b Transmission teeth 34c Taper portion 35 Spring 100 Housing 110 Paper feed cassette (paper feed tray)
P Recording paper

Claims (3)

A housing,
A paper feed tray attached to the housing and on which recording paper is placed;
A recording roller that has a transport roller that contacts and rotates with the recording paper and a drive motor that drives the roller, and transports the recording paper placed on the paper feed tray on a predetermined transport path inside the housing. A paper transport mechanism;
An image forming unit that is arranged inside the housing and forms an image on a recording sheet conveyed by the recording sheet conveying mechanism;
A control unit that controls the drive motor and the image forming unit to form an image on recording paper,
The recording paper transport mechanism is provided in a power transmission path for transmitting the driving force of the drive motor to the transport roller, and is a clutch that cuts and connects the power transmission path between the drive motor and the transport roller. An image forming apparatus having a mechanism,
The clutch mechanism is
A holding shaft supported by the housing;
A drive gear rotatably held on the holding shaft and driven in a predetermined rotation direction by the drive motor;
A driven gear that is rotatably held by the holding shaft and rotates the transport roller;
A clutch ring disposed between the drive gear and the driven gear so as to be rotatable and slidable in the direction of the rotation axis;
A spring that is disposed between the clutch ring and the driven gear in a compressed state from a natural state and biases the clutch ring away from the driven gear by its restoring force;
A plurality of rectangular rib-shaped pressing teeth arranged at predetermined intervals on the circumference are formed on a portion of the driving gear that faces the clutch ring,
A portion of the clutch ring facing the pressing teeth has a plurality of transmission teeth formed so as to be in contact with the side portions of the plurality of pressing teeth, and a predetermined distance of the driving gear between the transmission teeth. Provided so that the amount of protrusion toward the drive gear in the direction of rotation is increased, and a tapered portion is formed on which the tip of the pressing tooth is slidably contacted;
A plurality of meshing teeth arranged on the circumference so as to be able to mesh with each other are formed in a portion of the driven gear that faces the clutch ring and a portion of the clutch ring that faces the driven gear. And
The meshing teeth of the clutch ring are formed in a substantially saw-tooth shape such that the amount of protrusion toward the driven gear increases toward a predetermined rotation direction of the driving gear,
The meshing teeth of the driven gear are formed in a substantially saw-tooth shape such that the amount of protrusion toward the clutch ring is reduced in the predetermined rotation direction of the driving gear,
When the drive motor is driven, torque is applied to the drive gear, the tip of the pressing tooth slides on the tapered portion, and the clutch ring compresses the spring toward the driven gear. By sliding, the meshing teeth of the clutch ring mesh with the meshing teeth of the driven gear so that the driven gear is interlocked with the driving gear, and the driving force of the driving force motor is applied to the transport roller. Communicated,
When the driving motor is not driven, the clutch ring is separated from the driven gear by the restoring force of the spring, and the meshing teeth of the clutch ring and the meshing teeth of the driven gear are released, The driving gear and the driven gear can be rotated independently of each other,
Thus, when the recording paper is poorly conveyed, the recording roller can be easily removed from the recording paper conveyance path by rotating the conveyance roller in a state where the drive motor is not driven. An image forming apparatus. A recording paper transport mechanism is provided in a power transmission path for transmitting the driving force of the drive motor to the transport roller, and has a clutch mechanism for cutting and connecting the power transmission path between the drive motor and the transport roller. An image forming apparatus,
The clutch mechanism is
A holding shaft supported by the housing;
A drive gear rotatably held on the holding shaft and driven in a predetermined rotation direction by the drive motor;
A driven gear that is rotatably held by the holding shaft and rotates in conjunction with the transport roller;
A clutch ring disposed between the drive gear and the driven gear so as to be rotatable and slidable in the direction of the rotation axis;
A spring that is disposed between the clutch ring and the driven gear in a compressed state from a natural state and biases the clutch ring away from the driven gear by its restoring force;
When the drive motor is driven, torque is applied to the drive gear, the clutch ring is engaged with the driven gear, and the driven gear is interlocked with the drive gear. Is transmitted to the transport roller,
When the driving motor is not driven, the clutch ring is separated from the driven gear by the restoring force of the spring, and the meshing between the clutch ring and the driven gear is released, and the driving gear and the driven gear are released. Are capable of rotating independently of each other. A plurality of pressing teeth arranged at predetermined intervals on the circumference are formed at a portion of the driving gear that faces the clutch ring.
A portion of the clutch ring facing the pressing teeth has a plurality of transmission teeth formed so as to be in contact with the side portions of the plurality of pressing teeth, and a predetermined distance of the driving gear between the transmission teeth. Provided so that the amount of protrusion toward the drive gear in the direction of rotation is increased, and a tapered portion is formed on which the tip of the pressing tooth is slidably contacted;
A plurality of meshing teeth arranged on the circumference so as to be able to mesh with each other are formed in a portion of the driven gear that faces the clutch ring and a portion of the clutch ring that faces the driven gear. And
The meshing teeth of the clutch ring are formed in a substantially saw-tooth shape such that the amount of protrusion toward the driven gear increases toward a predetermined rotation direction of the driving gear,
The meshing teeth of the driven gear are formed in a substantially saw-tooth shape so that a projecting amount toward the clutch ring is reduced toward a predetermined rotation direction of the driving gear. The image forming apparatus described in 1.

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