JP4868153B2 - Intermittent drive device and image forming apparatus - Google Patents

Description

  The present invention relates to an intermittent driving device, a paper feeding device having the intermittent driving device, and an image forming apparatus having the paper feeding device.

  In this type of image forming apparatus, an intermittent driving device that transmits a driving force of a driving source to a movable member at a predetermined timing by using a tooth-missing gear is generally used. In this type of intermittent drive device, when the tooth-missing gear and the drive gear that drives the tooth-missing gear mesh with each other, the tooth tips may collide with each other, causing abnormal noise and damage to the gear. It was. Therefore, for example, a gear having a toothed tooth that intermittently drives the delivery means is known (for example, Patent Document 1). In addition, for example, there is also known one that is cut so that the height of the top of the drive transmission side tooth surface is higher than the height of the top of the driven transmission side tooth surface (for example, Patent Document 2).

JP 2004-227183 A Japanese Patent No. 3466752

  However, in the above prior art, since the tooth tip is made thin, there is a problem that the strength of the gear is lowered and the life of the apparatus is shortened.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an intermittent drive device that solves the above-mentioned conventional problems, maintains strength and realizes smooth operation, a paper feed device having the intermittent drive device, and an image forming apparatus having the paper feed device. It is to provide.

  In order to achieve the above object, a first feature of the present invention is that a tooth missing gear having a tooth missing portion lacking a part of a tooth, a driving gear for driving the tooth missing gear, and the driving gear. Is an intermittent drive device having escape means for escaping the drive gear in the rotational direction when meshed with the chipped gear.

  Preferably, the apparatus further includes a drive shaft connected to the drive gear, and the escape means includes an engagement portion formed on the drive shaft and an engaged portion formed on the drive gear, A circumferential clearance is provided between the engaging portion and the engaged portion.

  Preferably, the escape means comprises a one-way clutch.

  Preferably, the angle of the gap is not less than the angle of the pitch of the drive gear.

  The present invention includes a paper feeding device having the intermittent drive device described above.

  The present invention includes an image forming apparatus having the above-described paper feeding device.

  The second feature of the present invention is that a tooth missing gear having a tooth missing portion lacking a part of a tooth, a drive gear for driving the tooth missing gear, and the drive gear meshing with the tooth missing gear. An image forming apparatus comprising: an intermittent drive device having escape means for escaping the drive gear in the rotational direction when matched, and at least one developing device connected to the intermittent drive device.

  According to the present invention, it is possible to maintain the strength of the gear and realize a smooth operation.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 according to a first embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12. A paper feeding device 14 is disposed below the image forming apparatus main body 12, and a paper discharge unit 16 is disposed above the image forming apparatus main body 12. Is formed.

  The paper feeding device 14 has a paper feeding cassette 18, and a large number of sheets are stacked on the paper feeding cassette 18. A paper feed roll 20 that comes into contact with the stacked paper is disposed at one upper end of the paper feed cassette 18, and a separating roll 22 is provided to face the paper feed roll 20. The sheet at the top of the sheet feeding cassette 18 is picked up by the sheet feeding roll 20, and the sheet is rolled and conveyed by the cooperation of the sheet feeding roll 20 and the separating roll 22.

  The sheet conveyed from the sheet feeding cassette 18 is temporarily stopped by a registration roller 24, and discharged at a predetermined timing between a photosensitive unit 26 and a belt unit 28, which will be described later, and through a fixing device 30 by a discharge roller 32. 16 is discharged.

  In the image forming apparatus main body 12, a photosensitive unit 26, a belt unit 28, a power supply unit 34, and a control unit 36 are disposed as image forming means. In the photoconductor unit 26, for example, four photoconductors 40 are rotatably supported by the photoconductor unit main body 38. Around each photoconductor 40, a charging device 42 as a charging unit provided with a charging roll for uniformly charging the photoconductor 40, and a developer containing toner on the electrostatic latent image written on each photoconductor 40 A developing device 44 as a developing means that develops and visualizes the toner, a neutralizing device 46 that neutralizes the photoconductor 40 after transfer, and a toner removing device 48 that removes residual toner on the surface of the photoconductor 40 after transfer. Have. The photoconductor unit 26 includes four photoconductors 40, a charging device 42, a developing device 44, a charge removal device 46, and a toner removal device 48, and is detachable from the image forming apparatus main body 12. .

  The power supply unit 34 is disposed on the upper part of the image forming apparatus main body 12 and supplies power to the paper feeding device 14, the belt unit 28, the charging device 42, the developing device 44, and the like described above.

  The four toner boxes 50 are connected to the back side of the photoconductor unit 26. Each toner box 50 is for magenta, yellow, cyan, and black, and a toner supply unit 52 and a toner recovery unit 54 are integrated. The toner supply unit 52 is connected to the developing device 44 to supply the toner of each color to the developing device 44, and the toner recovery unit 54 is connected to the toner removing device 48 to recover the toner of each color.

  Each of the optical writing devices 56 is composed of a laser exposure device, and is arranged on the back side of the photoconductor unit 26 at a position corresponding to each photoconductor 40, and irradiates the uniformly charged photoconductor 40 with a laser. Thus, a latent image is formed.

  The belt unit 28 is on the front side of the photoconductor unit 26 and is arranged in the vertical direction so as to face the photoconductor unit 26. The belt unit 28 has two support rolls 58 provided in the vertical direction, and a conveyor belt 60 is hung on the support rolls 58. Further, a transfer roll 62 is provided so as to face each photoconductor 40 with the conveyance belt 60 interposed therebetween.

  The cleaning device 64 is disposed on the front side of the belt unit 28 so as to face the belt unit 28. The cleaning device 64 includes a cleaning device main body 66, a cleaning blade 68 as a cleaning member, a collection container 70, and a charge removal film 72, and removes deposits such as toner and paper dust on the surface of the conveyance belt 60. It is like that.

  A user interface (UI) device 73 is provided integrally with the image forming apparatus main body 12 or via a network, and is electrically connected to the control unit 36. The UI device 73 is provided with a display panel 73a and an input button 73b as display means for selecting and displaying processing contents of the image forming apparatus 10.

  Therefore, each photoconductor 40 is uniformly charged by the charging device 42, a latent image is formed by the optical writing device 56, and the latent image is visualized by toner by the developing device 44. The toner images formed on the respective photoreceptors 40 are transferred onto the sheet conveyed by the transfer roll 62 of the belt unit 28 in order from below, and are fixed on the sheet by the fixing device 30.

2 to 8 show details of the sheet feeding device 14 and the intermittent drive device 76. FIG.
The paper feeding device 14 has a paper feeding device main body (not shown), and an intermittent driving device 76 is provided in the paper feeding device main body. The intermittent drive device 76 includes an intermittent drive device main body 78 (shown in FIG. 5). The intermittent drive device main body 78 includes a drive gear 80 that is an example of a drive gear and a tooth-missing gear that is an example of a tooth-missing gear. 82, a solenoid 84, and an urging spring 86 are provided.

  As shown in FIGS. 3 to 5, the tooth-missing gear 82 is fixed to a rotating shaft 88 (shown in FIG. 5) that is rotatably provided on the intermittent drive device main body 78, and has a predetermined pitch on the outer periphery. A tooth portion 82a in which a plurality of teeth are formed and a tooth missing portion 82b in which a portion of the tooth is not provided (a portion of the tooth is missing) are formed. In addition, a cylindrical boss portion 90 protruding in the axial direction (tooth width direction) is formed integrally with the tooth missing gear 82 in the tooth missing gear 82. The boss portion 90 (shown in FIG. 4) is formed with a sliding surface 90a on which a movable piece 98 of a solenoid 84 described later slides. A part of the sliding surface 90a is provided with a locking part 90b. The engagement of the locking part 90b and the movable piece 98 of the solenoid 84 restricts the rotation of the chipped gear 82. It is like that. In addition, the above-described paper feed roll 20 is fixed to the rotary shaft 88, and the paper feed roll 20 (shown in FIG. 2) rotates as the toothless gear 82 rotates.

  The drive gear 80 is rotatably supported by a support shaft 95 (shown in FIGS. 4 and 5). A drive shaft 92 connected to the drive gear 80 is rotatably provided on the support shaft 95. As shown in FIG. 8, an input gear 92a is formed at one end of the drive shaft 92, and a plurality of convex portions 92b as engaging portions are formed at the other end of the drive shaft 92 (this example). 2) are formed. Also, as shown in FIG. 7, a plurality (two in this example) of recesses 80 a as engaged portions are formed on the side surface of the drive gear 80. As shown in FIG. 6, the drive gear 80 and the drive shaft 92 are connected by engaging the convex portion 92 b of the drive shaft 92 and the concave portion 80 a of the drive gear 80. The circumferential size (L1 in FIG. 8) of the convex portion 92b of the drive shaft 92 is smaller than the circumferential size (L2 in FIG. 7) of the concave portion 80a of the drive gear 80, and FIGS. As shown in FIG. 5, a circumferential gap 96 is formed between the convex portion 92b and the concave portion 80a.

  The size of the gap 96, that is, the difference between the circumferential size of the projection 92b and the circumferential size of the recess 80a (L2-L1) is set to be larger than the pitch angle of the drive gear 80. Yes. Here, the pitch angle of the drive gear 80 is an angle obtained by dividing (dividing) the circumference (360 °) of the drive gear 80 by the number of teeth of the drive gear 80. Further, the angle of the gap portion 96, that is, the angle formed by the convex portion 92b and the concave portion 80a (the angle α in FIG. 9A) is set to be larger than the pitch angle of the drive gear 80. .

  The input gear 92 a is connected to a driving source (not shown) such as a motor, and the driving force of the input gear 92 a is transmitted to the driving gear 80 via the driving shaft 92. The drive gear 80 is disposed at a position where the drive gear 80 meshes with the tooth portion 82 a of the tooth missing gear 82, and is rotationally driven to transmit power to the tooth missing gear 82. When the drive gear 80 and the tooth missing portion 82 b of the tooth missing gear 82 are opposed to each other, the drive gear 80 idles so that the power from the drive gear 80 is not transmitted to the tooth missing gear 82.

  The solenoid 84 is disposed in the vicinity of the tooth missing gear 82 and has a movable piece 98 and a coil spring 100 (shown in FIG. 5). The movable piece 98 is formed with a locking claw 98a whose tip is bent in an L shape. The coil spring 100 urges the locking claw 98a of the movable piece 98 toward the sliding surface 90a of the toothless gear 82. The locking claw 98 a is configured to regulate the rotation of the tooth missing gear 82 by engaging with the locking portion 90 b of the tooth missing gear 82.

  One end of the biasing spring 86 is locked to a spring hooking portion 82c provided on the side surface of the toothless gear 82, and the other end is locked to a drive device main body 78 (shown in FIG. 5). A predetermined urging force is applied to 82. More specifically, the biasing spring 86 applies a biasing force for rotating the tooth missing gear 82 until the tooth portion 82a of the tooth missing gear 82 and the drive gear 80 are engaged with each other. The biasing spring 86 and the solenoid 84 described above lock the rotation of the toothless gear 82 at a position where the drive gear 80 and the toothless portion 82b of the toothless gear 82 face each other, and release the lock. Thus, an operating means for rotating the tooth missing gear 82 and meshing with the drive gear 80 is configured.

Next, the operation of the intermittent drive device 76 in the embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 9A, when the solenoid 84 is in a non-excited state (off), the locking claw 98a of the solenoid 84 and the locking portion 90b of the tooth missing gear 82 are engaged, and the tooth missing The rotation of the gear 82 is restricted by the movable piece 98. At this time, the drive gear 80 faces the tooth missing portion 82 b of the tooth missing gear 82, and the driving force from the driving gear 80 is not transmitted to the tooth missing gear 82. The drive gear 80 receives power from the drive shaft 92 via the convex portion 92b of the drive shaft 92, and rotates in the direction of arrow A in FIG.

  When the solenoid 84 is in an excited state (on), a magnetic attractive force acts on the movable piece 98, and the movable piece 98 is pulled against the urging force of the coil spring 100. As a result, the engagement between the locking portion 90 b of the tooth missing gear 82 and the locking claw 98 a of the movable piece 98 is released, and the tooth missing gear 90 rotates in the arrow B direction by the biasing force of the biasing spring 86. At this time, as shown in FIG. 9B, the tooth tip portion of the drive gear 80 may collide with the tooth tip portion of the tooth portion 82 b of the tooth missing gear 82. When the tooth tip portion of the drive gear 80 collides with the tooth tip portion of the tooth portion 82b of the tooth missing gear 82, the drive gear 80 escapes in the rotational direction as shown in FIG. More specifically, the drive gear 80 is pressed by the tooth portion 82b of the tooth missing gear 82 and rotates within the gap portion 96 at a faster speed than the drive shaft 92 (rotates in the direction of arrow A in FIG. 9C). ) Thereby, the tooth surface of the drive gear 80 and the tooth surface of the tooth portion 82a of the tooth missing gear 82 are brought into mesh with each other, and a smooth operation is realized.

  As described above, the drive gear 80 is connected to the toothless gear 82 in the convex portion 92b of the drive shaft 92, the concave portion 80a of the drive gear 80, and the gap portion 96 formed in the circumferential direction between the convex portion 92b and the concave portion 80a. It is used as an escaping means for escaping the drive gear 80 in the rotational direction when meshing.

Next, an intermittent drive device 76 according to a second embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 10, in each developing device 44 (shown in FIG. 1), developing rolls 74Y, 74M, 74C, and 74K for developing each color toner are provided. These developing rolls 74Y, 74M, 74C, and 74K are driven by a driving force transmitted by a drive transmission unit 102 described later.

  The drive transmission unit 102 is provided in the image forming apparatus main body 12 (shown in FIG. 1) and has a plurality of gears. More specifically, the drive transmission unit 102 includes a drive source 104, first transmission gears 106a, 106b, and 106c, second transmission gears 108a and 108b, third transmission gears 110a and 110b, and a fourth transmission gear. 112 a, 112 b, 112 c, development drive transmission gears 114 a, 114 b, 114 c, 114 d and an input gear 126 and an output gear 128 of an intermittent drive device 76 described later.

  The developing roller 74K is driven from the driving source 104 via the first transmission gears 106a, 106b, 106c and the developing driving gear 114d. When the driving force is transmitted from the driving source 104 to the second transmission gears 108a and 108b and the driving force is transmitted from the input gear 126 to the output gear 128, the third transmission gears 110a and 110b and the fourth transmission gear are transmitted. The developing rolls 74Y, 74M, and 74C are driven through the gears 112a, 112b, and 112c and the developing driving gears 114a, 114b, and 114c.

11 and 12 show details of the drive transmission device 115 having the intermittent drive device 76 of the present embodiment.
As shown in FIGS. 11 and 12, the drive transmission device 76 according to the present embodiment switches the connection / release of the drive transmission unit 102 described above by the intermittent drive device 76 and the toothless gear 82 of the intermittent drive device 76. A drive switching unit 116 (shown in FIG. 12) is provided, and the drive switching unit 116 is provided with a driven gear 118 and a coupling 120. Here, the drive source (not shown) of the intermittent drive device may be the same as or different from the drive transmission unit 102.

  The tooth missing gear 82 is rotatably provided in the intermittent drive device main body 78, and a gear portion 90 c that meshes with the driven gear 118 is formed on the boss portion 90 of the tooth missing gear 82. The drive gear 80 is connected to a drive shaft 92 that is rotatably supported by the support shaft 95 via a one-way clutch 117. The one-way clutch 117 rotates only in one direction (the direction opposite to the arrow A direction in FIG. 11) with respect to the input from the drive shaft 92, and is locked in the other direction (the arrow A direction in FIG. 11). It has become. That is, the drive gear 80 is rotated together with the drive shaft 92 by the drive force of the drive shaft 92 in the direction of arrow A, and is rotatable when the drive gear 80 is rotated in the direction of arrow A.

  The driven gear 118 is rotatably provided in the intermittent drive device main body 78 and is disposed at a position where the driven gear 118 meshes with the gear portion 90 c of the tooth missing gear 82. A cam 122 is formed integrally with the driven gear 118 on one side surface of the driven gear 118. The cam 122 is formed integrally with the driven gear 118 in a substantially half-circular (about 180 °) portion of the side surface of the driven gear 118, and is provided so as to contact the slide member 130 of the coupling 120. The cam 122 rotates in unison with the driven gear 118 so as to give a periodic motion to the slide member 130. Note that the gear ratio between the driven gear 118 and the gear portion 104b of the tooth missing gear 90 is 1: 2, and when the tooth missing gear 82 makes one revolution, the driven gear 118 makes a half rotation.

  The coupling 120 is rotatably provided on a rotation support shaft 124 formed in the intermittent drive device main body 78 and includes an input gear 126, an output gear 128, and a slide member 130. As described above, the input gear 126 is disposed at a position that meshes with the second transmission gear 108b. Further, the input gear 126 has an engaging portion 126 a that engages with the engaged portion 130 a of the slide member 130.

  The slide member 130 is provided so as to be slidable in the axial direction with respect to the rotation support shaft 124, and an engaged portion 130 a that engages with the engaging portion 126 a of the input gear 126 is formed at the distal end portion. The slide member 130 supports the output gear 130 so as to rotate integrally with the output gear 128 and is slidable with respect to the output gear 128. As described above, the output gear 130 is disposed at a position that meshes with the third transmission gears 110a and 110b.

  The output gear 128 is slidably supported by the slide member 130 and rotates together with the slide member 130. The coil spring 132 is provided between the intermittent drive device main body 78 and the slide member 130, and biases the slide member 130 in the direction of the input gear 126. In this way, the coupling 120 performs connection or disconnection of power between the input gear 126 and the output gear 128.

Next, the operation of the drive transmission device 115 having the intermittent drive device 76 in this embodiment will be described with reference to FIG.
As shown in FIG. 13A, when the drive switching unit 116 of the drive transmission device 115 is in the first operation state, the power between the input gear 126 and the output gear 128 is connected. More specifically, the portion of the side surface of the driven gear 118 where the cam 122 is not formed contacts the slide member 130 of the coupling 120, and the engaging portion 126 a of the input gear 126 and the slide member are urged by the biasing force of the coil spring 132. 130 engaged parts 130a are engaged. Accordingly, the input gear 126 and the output gear 128 are rotated by the driving force transmitted from the second transmission gear 108b. Accordingly, the output gear 126 operates the developing rolls 74Y, 74M, and 74C via the third transmission gears 110a and 110b, the fourth transmission gears 112a to 112c, and the development driving gears 114a to 114c. As described above, when the drive switching unit 116 of the drive transmission device 115 is in the first operation state, the developing rolls 74Y, 74M, 74C, and 74K are operated.

  Subsequently, when the solenoid 84 is energized (ON), the tooth missing gear 82 is rotated by the biasing force of the biasing spring 86. When the tooth missing gear 82 further rotates and the drive gear 80 and the tooth portion 82a of the tooth missing gear 82 mesh with each other, the tooth missing gear 82 is rotated by the power of the drive gear 80. At this time, the tooth tip portion of the drive gear 80 may collide with the tooth tip portion of the tooth portion 82 b of the tooth missing gear 82. When the tooth tip portion of the drive gear 80 collides with the tooth tip portion of the tooth portion 82b of the tooth missing gear 82, the drive gear 80 escapes in the rotational direction (the direction of arrow A in FIG. 11) by the action of the one-way clutch 117. . Thereby, the tooth surface of the drive gear 80 and the tooth surface of the tooth portion 82a of the tooth missing gear 82 are brought into mesh with each other, and a smooth operation is realized.

  As described above, the one-way clutch 117 is used as a release means for releasing the drive gear 80 in the rotation direction when the drive gear 80 meshes with the tooth missing gear 82.

  When the tooth missing gear 82 rotates approximately once, the tooth missing portion 82b again faces the meshing position with the drive gear 80, and the tooth missing gear 82 and the drive gear 80 are disengaged. When the toothless gear 82 and the drive gear 80 are disengaged from each other, the locking portion 90b of the toothless gear 82 abuts against the locking claw 98a of the movable piece 98, and the rotation of the toothless gear 82 is restricted by the movable piece 98. . As a result, the tooth missing gear 82 is again held at the operation start position, and the drive switching unit 116 of the drive transmission device 115 enters a second operation state described later.

  As shown in FIG. 13B, when the drive switching unit 116 of the drive transmission device 115 is in the second operation state, the power connection between the input gear 126 and the output gear 128 is released. ing. More specifically, as compared with the first operation state, the driven gear 118 is rotated by about 180 °, and the cam 122 of the driven gear 118 resists the biasing force of the coil spring 132 and the sliding member of the coupling 120. 130 is pressed, and the slide member 130 is slid in the direction opposite to the input gear 126. Thereby, the engagement between the engaging portion 126a of the input gear 126 and the engaged portion 130a of the slide member 130 is released. Accordingly, only the input gear 126 is rotated by the driving force transmitted from the second transmission gear 108c, the transmission of the driving force from the input gear 126 to the output gear 128 is released, and the developing rolls 74Y, 74M, and 74C are operated. Stopped. On the other hand, the developing roller 74K continues to operate by the driving force of the driving source 104. As described above, when the drive switching unit 116 of the intermittent drive device 76 is in the second operation state, the developing roller 74K is operated, and the operations of the developing rollers 74Y, 74M, and 74C are stopped.

As described above, the drive transmission device 115 having the intermittent drive device 76 in this embodiment switches the transmission of the driving force to the developing rolls 74Y, 74M, 74C, and 74K by switching the operation state of the drive switching unit 116. It is like that.
In the description of the second embodiment of the present invention, the same parts as those in the first embodiment of the present invention are denoted by the same reference numerals and the description thereof is omitted.

1 is a side view showing an image forming apparatus according to a first embodiment of the present invention. 1 is a perspective view illustrating a sheet feeding device of an image forming apparatus according to a first embodiment of the present invention. It is a perspective view which shows the intermittent drive device which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the intermittent drive device which concerns on the 1st Embodiment of this invention. It is a front view which shows the intermittent drive device which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the drive gear which concerns on the 1st Embodiment of this invention. The drive gear which concerns on the 1st Embodiment of this invention is shown, (a) is a perspective view, (b) is a front view. It is a perspective view which shows the drive gear which concerns on the 1st Embodiment of this invention. The operation | movement of the intermittent drive device which concerns on the 1st Embodiment of this invention is shown, (a) is the state before a drive gear and a tooth missing gear mesh | engage, (b) is the top of a drive gear, and a tooth missing gear. FIG. 6C is a diagram illustrating a state in which the top collides, and FIG. 5C illustrates a state in which the drive gear escapes in the rotation direction. It is a schematic diagram explaining the drive transmission unit which concerns on the 2nd Embodiment of this invention. It is a front view which shows the drive transmission device which has an intermittent drive device which concerns on the 2nd Embodiment of this invention. It is a side view which shows the drive transmission device which has an intermittent drive device which concerns on the 2nd Embodiment of this invention. The operation state of the drive transmission apparatus which has the intermittent drive device which concerns on the 2nd Embodiment of this invention is shown, (a) is a 1st operation state, (b) is a front view explaining a 2nd operation state. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Paper supply apparatus 44 Developing apparatus 74 Developing roll 76 Intermittent drive apparatus 80 Drive gear 80a Concave part 82 Tooth missing gear 82a Tooth part 82b Tooth missing part 92 Drive shaft 92b Convex part 96 Crevice part 117 One-way clutch

Claims (4)

A tooth-missing gear having a tooth-missing portion lacking a part of the tooth;
A drive gear that is rotationally driven to transmit drive force to the toothless gear;
A drive switching unit that is driven by the driving force transmitted from the drive gear via the tooth-missing gear, and that connects or disconnects the power;
A one-way clutch for releasing the drive gear in the rotational direction when the drive gear meshes with the tooth-missing gear;
Have
The drive switching portion includes at least two gears rotating on the same axis, an engaged portion that transmits power between the two gears, and a coupling having an engaging portion that engages with the engaged portion; A cam portion that gives a periodic motion to the coupling,
Whenever the drive gear and the tooth missing portion face each other, at least one of the engaged portion and the engaging portion of the coupling is moved by the rotation of the cam portion to connect the power between the at least two gears. Or the intermittent drive device characterized by performing connection cancellation | release . Actuating means for locking the rotation of the tooth-missing gear at a position where the tooth-missing portion faces the drive gear and releasing the lock to rotate the tooth-missing gear and mesh with the driving gear. The intermittent drive device according to claim 1, wherein the intermittent drive device is provided. A tooth-missing gear having a tooth-missing portion in which a part of the tooth is missing, a driving gear that rotates to transmit a driving force to the tooth-missing gear, and a drive that is transmitted from the driving gear via the tooth-missing gear A drive switching unit that is driven by force to connect or release the power, and a one-way clutch that releases the drive gear in the rotational direction when the drive gear meshes with the tooth-missing gear, and the drive switching unit includes: A coupling having at least two gears that rotate on the same axis, an engaged portion that transmits power between the two gears, and an engaging portion that engages with the engaged portion, and the coupling periodically Each time the drive gear and the tooth missing portion face each other, at least one of the engaged portion and the engaging portion of the coupling is moved by the rotation of the cam portion. And at least 2 An image forming apparatus of the intermittent drive unit and performs connection or uncoupling of the power between the gears, and at least one developing means connected to said intermittent driving devices, characterized in that it has a. The image forming apparatus according to claim 3, wherein the intermittent driving device releases transmission of power to at least one of the developing units.

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