JP5175618B2 - Drive transmission device and full-color image forming apparatus having the same - Google Patents

Description

The present invention relates to a drive transmission device that transmits rotation of a motor to a plurality of units via a plurality of drive trains to rotate each unit, and a full-color image forming apparatus including the drive transmission device.

  For example, in a color image forming apparatus such as a color copying machine or a color printer that forms a full color image on paper by electrophotography, four image forming units of magenta, cyan, yellow, and black are arranged in tandem to form each image. There is a type that employs a system in which a toner image of each color formed in a unit is superimposed and transferred onto an intermediate transfer belt to form a full-color toner image, and this full-color toner image is collectively transferred onto a sheet.

  In such a color image forming apparatus, in addition to a color mode for forming a full color image using four color toners, a monochrome mode for forming a monochrome image using only black toner can be selected. When selected, the units used for forming magenta, cyan and yellow color toner images other than black are stopped. For example, in the four toner containers that replenish toner to the developing devices of the image forming units for each color, all four toner containers are driven in the color mode, only the black toner container is driven in the monochrome mode, The driving of the magenta, cyan and yellow toner containers is stopped.

By the way, in the color image forming apparatus that employs the method of driving all four units in the color mode and driving only the black unit in the monochrome mode as described above, the unit is driven according to the color mode and the monochrome mode. as a method of switching the motor to place the every four units, to switch the driving of the unit by oN / OFF control of each motor, method employed for switching the drive unit by oN / OFF control of the electromagnetic clutch or solenoid (For example, refer to Patent Document 1).

  However, in the above-described conventional method, the use of a plurality of motors increases the cost, and when an electromagnetic clutch or solenoid is used, it is impossible to energize for a long time due to the heat generated, and the operation noise becomes noise. Problems occur.

The present invention has been made in view of the above problems, and the object of the present invention is that a single motor can be used to drive a plurality of units, and the driving of the units can be switched with a simple configuration. And a full-color image forming apparatus including the drive transmission device.

In order to achieve the above object, according to the first aspect of the present invention, the rotation of the motor is transmitted to the black image forming unit and the plurality of magenta, cyan and yellow color image forming units via the plurality of drive trains. In a drive transmission device of a full-color image forming apparatus that rotationally drives
Dividing the plurality of drive trains into two,
Wherein the first drive train for driving only the black image forming unit, provided the rotational movement gear selectively engaged by the forward and reverse rotation of the motor to either of the two driven gears,
The second image train that drives the color image forming unit selectively drives the color image forming unit by selectively transmitting the rotation of the motor by turning on and off by forward / reverse rotation of the motor. A one-way clutch,
It is possible to switch between a color mode for driving all of the black image forming unit and the color image forming unit and a monochrome mode for driving only the black image forming unit by forward and reverse rotation of the motor.

  According to a second aspect of the present invention, in the first aspect of the present invention, the rotational movement gear is supported so as to be rotatable about a rotation shaft of a gear meshing with the gear, and is rotated by a load torque caused by meshing of both gears. And selectively meshing with any one of the driven gears.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the black image forming unit driven by the first drive train is the same regardless of which of the driven gears meshes with the rotary gear. It is configured to rotate in the direction.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, an idle gear is meshed with one of the driven gears.

Full-color image forming apparatus according to claim 5 is provided with a plurality of image forming units, wherein the digits set the drive transmission device according to any one of 請 Motomeko 1-4.

According to the first aspect of the present invention, the first drive train always transmits the rotation to the black image forming unit even by forward / reverse rotation of the motor to always drive the black image forming unit, while the second drive train Since the one-way clutch is provided, the second drive train selectively drives the color image forming unit by forward and reverse rotation of the motor. Accordingly, all the image forming units can be driven by a single motor, and the driving mode is switched between a color mode for driving all the image forming units and a monochrome mode for driving only the black image forming unit by forward and reverse rotation of the motor. In addition to the simplification of the structure and the associated cost reduction, continuous operation and noise reduction are possible.

  According to the second aspect of the present invention, the rotational movement gear rotates around the rotation shaft of the gear meshing with the motor even when the motor is rotated in the forward and reverse directions, and selectively selects one of the two driven gears. Because of the meshing, some units can always be driven by the first drive train.

According to the third aspect of the present invention, even if the driving of the image forming unit is switched by forward / reverse rotation of the motor, that is, regardless of which of the color mode and the monochrome mode is selected, the first driving train The driven black image forming unit can be rotationally driven in the same direction. That is, when the color mode for driving all image forming units is selected, all the image forming units are rotated in the same direction, and when the monochrome mode for driving only the black image forming unit is selected, The black image forming unit is driven to rotate in the same direction (the same direction as in the color mode in which all the image forming units are driven), and the snake transfer direction of the black image forming unit is reversed by selecting the driving mode (color mode or monochrome mode). There is nothing.

  According to the fourth aspect of the present invention, the unit can be driven to rotate in the same direction with a simple configuration in which the idle gear is engaged with one of the driven gears.

  According to the fifth aspect of the present invention, in the full-color image forming apparatus, a plurality of image forming units can be driven using a single motor to form a full-color image, and a black image can be formed. Since only the black image forming unit can be driven and the driving of the image forming unit can be switched with a simple configuration, the number of parts of the full-color image forming device can be reduced, cost reduction, continuous operation, low noise, etc. can do.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[ Full-color image forming device]
FIG. 1 is a cross-sectional view of a color laser printer as an embodiment of a full-color image forming apparatus according to the present invention. The illustrated color laser printer is a tandem type, and a magenta image is formed at the center in the main body 100. The unit 1M, the cyan image forming unit 1C, the yellow image forming unit 1Y, and the black image forming unit 1K are arranged in tandem at regular intervals.

  In each of the image forming units 1M, 1C, 1Y, and 1K, photosensitive drums 2a, 2b, 2c, and 2d, which are image carriers, are disposed, respectively, and a charging roller 3a is disposed around each of the photosensitive drums 2a to 2d. 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d and drum cleaning devices 6a, 6b, 6c, 6d, respectively.

  Here, the photosensitive drums 2a to 2d are drum-shaped photosensitive members, and are rotationally driven at a predetermined process speed in the direction of the arrow (clockwise) by a motor (not shown). The charging rollers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing devices 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (K) toner, respectively, and are formed on the photosensitive drums 2a to 2d. In addition, the toner of each color is attached to each electrostatic latent image to visualize each electrostatic latent image as a toner image of each color.

  The transfer rollers 5a to 5d are arranged so as to be able to contact the photosensitive drums 2a to 2d via the intermediate transfer belt 7 in the respective primary transfer portions. Here, the intermediate transfer belt 7 is stretched between the secondary transfer counter roller 8 and the tension roller 9 and is disposed on the upper surface side of each of the photosensitive drums 2a to 2d. The roller 8 is disposed so as to be in contact with the secondary transfer roller 10 via the intermediate transfer belt 7 in the secondary transfer portion. A belt cleaning device 11 is provided in the vicinity of the tension roller 9.

  Incidentally, toner containers 12a, 12b, 12c, and 12d for supplying toner to the developing devices 4a to 4d are arranged in a line above the image forming units 1M, 1C, 1Y, and 1K in the apparatus main body 100. It is installed. Although not shown, inside each of the toner containers 12a to 12d, a stirring member (paddle) for stirring the toner and a conveying screw for supplying toner to each of the developing devices 4a to 4d are provided. These agitating members and the conveying screw are selectively rotated by a drive transmission device described later.

  In addition, a laser scanner unit (LSU) 13 is disposed below the image forming units 1M, 1C, 1Y, and 1K in the apparatus main body 100, and a paper feed cassette 14 is detachably attached to the bottom of the main body 100 below the image forming units. is set up. A plurality of sheets (not shown) are stacked and accommodated in the paper feed cassette 14, and a pickup roller 15 for taking out the paper one by one from the paper feed cassette 14 is taken out in the vicinity of the paper feed cassette 14. A feed roller 16 and a retard roller 17 are provided for feeding the fed paper to the transport path L.

  In addition, the conveyance path L extending in the vertical direction on the side of the apparatus main body 100 includes a conveyance roller pair 18 that conveys the sheet, and the secondary transfer counter roller 8 and the second transfer opposing roller 8 at a predetermined timing after the sheet is temporarily held. A registration roller pair 19 is provided to be supplied to a secondary transfer portion which is a contact portion with the next transfer roller 10. Next to the transport path L, another transport path L ′ used for forming an image on both sides of the sheet is formed, and a plurality of transport roller pairs 20 are appropriately used in the transport path L ′. Are provided at regular intervals.

  By the way, the conveyance path L arranged in the vertical direction on one side in the apparatus main body 100 extends to the paper discharge tray 21 provided on the upper surface of the apparatus main body 100, and the fixing device 22 and the discharge path are in the middle. A paper roller pair 23 is provided.

  Next, an image forming operation by the color laser printer having the above configuration will be described with reference to FIG.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate at a predetermined process speed in the direction of the arrow in FIG. 1 (clockwise) in each of the image forming units 1M, 1C, 1Y, and 1K. The drums 2a to 2d are uniformly charged by the charging rollers 3a to 3d. The laser scanner unit 13 emits a laser beam modulated by a color image signal for each color, irradiates the surface of each photosensitive drum 2a to 2d with the laser beam, and each color is applied to each photosensitive drum 2a to 2d. An electrostatic latent image corresponding to the color image signal is formed.

  First, magenta toner is attached to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charged polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. This magenta toner image is transferred to the arrow shown in FIG. 1 by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied at the primary transfer portion (transfer nip portion) between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 7 which is rotationally driven in the direction.

  The intermediate transfer belt 7 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred to the magenta toner image on the intermediate transfer belt 7 in the primary transfer portion in the same manner as described above.

  Similarly, yellow and black toners respectively formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1K on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 7, respectively. The images are sequentially superimposed at each primary transfer portion, and a full-color toner image is formed on the intermediate transfer belt 7. The transfer residual toner which is not transferred onto the intermediate transfer belt 7 and remains on the photosensitive drums 2a to 2d is removed by the drum cleaning devices 6a to 6d, and the photosensitive drums 2a to 2d are prepared for the next image formation. It is done.

  Then, the pickup from the paper feed cassette 14 is performed in accordance with the timing at which the front end of the full color toner image on the intermediate transfer belt 7 reaches the secondary transfer portion (transfer nip portion) between the secondary transfer counter roller 8 and the secondary transfer roller 10. The sheet fed to the conveyance path L by the roller 15, the feed roller 16 and the retard roller 17 is conveyed to the secondary transfer unit by the registration roller pair 19. Then, a full-color toner image is collectively transferred from the intermediate transfer belt 7 to the sheet conveyed to the secondary transfer unit by the secondary transfer roller 10 to which a secondary transfer bias having a polarity opposite to that of the toner is applied. .

  Thus, the sheet on which the full-color toner image has been transferred is conveyed to the fixing device 22, and the sheet on which the full-color toner image has been fixed by being heated and pressurized and thermally fixed on the surface of the sheet. Then, the paper is discharged onto the paper discharge tray 21 by the paper discharge roller pair 23 to complete a series of image forming operations. The transfer residual toner that is not transferred onto the sheet and remains on the intermediate transfer belt 7 is removed by the belt cleaning device 11, and the intermediate transfer belt 7 is prepared for the next image formation.

[Drive transmission device]
Next, a drive transmission device according to the present invention will be described with reference to FIGS.

  2 is a front view of the drive transmission device according to the present invention, FIG. 3 is a front view showing the operation of the drive transmission device in the color mode, and FIG. 4 is a front view showing the operation of the drive transmission device in the monochrome mode. 5 is a view in the direction of arrow A in FIG. 3, and FIG. 6 is a perspective view of the rotational movement gear.

  The drive transmission device according to the present embodiment is for driving the four toner containers 12a to 12d shown in FIG. 1. As shown in FIG. 2, the housing 24 has a motor 25 as a drive source. Drive shafts 26a, 26b, 26c, and 26d connected to stirring members (paddles) (not shown) incorporated in the toner containers 12a to 12d, and the rotation of the motor 25 are transmitted to the drive shafts 26a to 26d. A plurality of drive trains are provided for rotationally driving the drive shafts 26a to 26d and the stirring members of the toner containers 12a to 12d. Here, the drive train drives the first drive train G1 for driving the toner container 12d containing black toner and the three toner containers 12a to 12c containing magenta, cyan and yellow color toners. The second drive train G2 is divided. Details of the configuration of these drive trains G1, G2 will be described below with reference to FIGS.

  As shown in FIG. 5, a small-diameter pinion gear Gp is connected to the output shaft end of the motor 25, and the gear G11 of the first drive train G1 and the gear of the second drive train G2 are connected to the pinion gear Gp. G21 is engaged.

  Here, in addition to the gear G11, the first drive train G1 rotates around the rotation shaft 27 of the gear G11 and selectively selects one of the two driven gears (stage gears) G13, G13 ′. , The rotational gear G12 meshed with the gear, the driven gears G13, G13 ′, the gears G14, G15, Gd sequentially meshed with the driven gear G13, and the gears G13 ′, G14 ′ disposed between the driven gear G13 ′ and the gear G14. An endless drive belt 29d wound between an idle gear G16 meshing with G14, a pulley (not shown) attached to the rotation shaft 30d of the gear Gd, and a pulley 28d attached to the drive shaft 26d. I have.

  Incidentally, as shown in FIG. 6, the rotational movement gear G12 is rotatably supported at the tip end of a holder 31 that swings about the rotation shaft 27 of the gear G11, and is mounted between the holder 31 and the rotary movement gear G12. The pressing spring 32 is pressed against the inner wall of the holder 31. In the present embodiment, the gear G11 and the rotational movement gear G12 that mesh with each other are constituted by helical gears.

  On the other hand, in addition to the gear G21, the second drive train G2 includes gears G22, G23, G24, Gc, Gb, G25, Ga that sequentially mesh with the gear G21, and the rotation shafts 30a to 30c of the gears Ga to Gc. And endless drive belts 29a to 29c wound around pulleys (not shown) bound to the pulleys 28a to 28c bound to the drive shafts 26a to 26c, respectively. Here, as shown in detail in FIG. 5, the gear G <b> 23 and the gear G <b> 24 are disposed on the same shaft 33, and the gear G <b> 23 is provided with a one-way clutch 34. The one-way clutch 34 is turned on when the motor 25 is rotated forward, and the rotation of the motor 25 is transmitted to the gears G24, Gc, Gb, G25, Ga downstream of the gear G23, and turned off when the motor 25 is rotated in reverse. The function of preventing the rotation of the motor 25 from being transmitted to the gears G24, Gc, Gb, G25, Ga downstream of the gear G23.

  Next, the operation in the color mode and the monochrome mode of the drive transmission apparatus configured as described above will be described based on FIGS.

  When the color mode is selected to form a full-color image, as shown in FIG. 3, the motor 25 is rotated in the forward direction and the pinion gear Gp rotates in the direction indicated by the arrow (clockwise). Then, in the first drive train G1, the gear G11 that meshes with the pinion gear Gp and the rotational movement gear G12 that meshes with the pinion gear Gp rotate in the direction of the arrow, respectively, and the load torque due to the meshing of these gears G11 and the rotational movement gear G12. As a result, the holder 31 and the rotational movement gear G12 supported by the holder 31 rotate in the direction of the arrow (counterclockwise) about the rotational shaft 27 of the gear G11, and the rotational movement gear G12 moves to one driven gear G13 as shown in the figure. Mesh.

  Accordingly, in the first drive train G1, the rotation of the rotational movement gear G12 is transmitted to the gear Gd through the gears G13, G14, G15 in sequence, and the gear Gd is in the same direction as the rotation of the motor 25 (forward rotation direction). Is driven to rotate. The rotation of the gear Gd is transmitted to the drive shaft 26d through a pulley (not shown) coupled to the rotation shaft 30d of the gear Gd, the drive belt 29d, and the pulley 28d, and the black toner container 12d is transmitted by the drive shaft 26d. A stirring member (paddle) (not shown) incorporated in (see FIG. 1) is driven to rotate in the same direction (clockwise) as the motor 25 rotates.

In the second drive train G2, since the one-way clutch 34 is turned on as described above when the motor 25 is rotating forward, the motor 25 rotates from the pinion gear Gp through the gears G21, G22, G23, G24 to the gear Gc. Is transmitted from the gear G24 to the gear Gb, and further transmitted from the gear Gb to the gear Ga through the gear G25, and the three gears Ga, Gb, Gc are simultaneously rotated in the same direction (clockwise). The Thus, when the three gears Ga, Gb, Gc are simultaneously driven to rotate in the same direction, pulleys (not shown) respectively connected to the rotation shafts 30a to 30c of the gears Ga to Gc and the drive shafts 26a to 26a. Rotation is transmitted to the drive shafts 26a to 26c via the pulleys 28a to 28c and the drive belts 29a to 29c, which are attached to the drive shaft 26c. The magenta, cyan, and yellow toner containers 12a to 12c are transmitted to the drive shafts 26a to 26c. A stirring member (paddle) (not shown) incorporated in (see FIG. 1) is driven to rotate in the same direction (clockwise) as the motor 25 rotates.

  As described above, when the motor 25 is rotated forward in the color mode, the rotation is transmitted to all the drive shafts 26a to 26d by the first and second drive trains G1 and G2, and by the drive shafts 26a to 26d. The stirring members incorporated in all the toner containers 12a to 12d are rotationally driven in the same direction (clockwise in FIG. 3).

  On the other hand, when the monochrome mode is selected to form a monochrome image, as shown in FIG. 4, the motor 25 is reversed and the pinion gear Gp rotates in the direction indicated by the arrow (counterclockwise). Then, in the first drive train G1, the gear G11 that meshes with the pinion gear Gp and the rotational movement gear G12 that meshes with the pinion gear Gp rotate in the direction of the arrow, respectively, and the load torque due to the meshing of these gears G11 and the rotational movement gear G12. As a result, the holder 31 and the rotational movement gear G12 supported by the holder 31 rotate in the direction of the arrow (clockwise) about the rotational shaft 27 of the gear G11, and the rotational movement gear G12 moves to the other driven gear G13 ′ as shown in the figure. Mesh.

Therefore, in the first drive train G1, the rotation of the rotational movement gear G12 is transmitted to the gear Gd through the driven gear G13 ′, the idle gear G16, and the gears G14 to G16 in sequence, and the gear Gd is rotated with the rotation of the motor 25. It is rotationally driven in the reverse direction (clockwise). The rotation of the gear Gd is transmitted to the drive shaft 26d via the pulley and drive belts 29d and the pulley 28d, not shown, it is bound to a rotating shaft 30d of the gear Gd, black toner container by the drive shaft 26d A stirring member (paddle) (not shown) incorporated in 12d (see FIG. 1) is driven to rotate in the direction opposite to the rotation of the motor 25 (clockwise). In this embodiment, since the idle gear G16 is interposed between the driven gear G13 ′ and the gear G14, the rotation direction of the drive shaft 26d is the same as that in the color mode even when the motor 25 is reversed, and the toner container 12d. There is no reversal of the stirring guilt built in.

  In the second drive train G2, since the one-way clutch 34 is turned off as described above when the motor 25 is reversely rotated, the rotation of the motor 25 is transmitted from the pinion gear Gp to the gear G23 via the gears G21 and G22. The gear G23 only freely rotates on the shaft 33 and does not transmit the rotation to the subsequent gears G24, Gc, Gb, G25, Ga. Accordingly, in the second drive train G2, the rotation of the motor 25 is not transmitted to the drive shafts 26a to 26c, but is incorporated in the drive shafts 26a to 26c and the magenta, cyan and yellow toner containers 12a to 12c. The stirring member is stopped without being driven.

  As described above, when the motor 25 is reversely rotated in the monochrome mode, the rotation is transmitted to the drive shaft 26d by the first drive train G1, and only the stirring member built in the black toner container 12d is rotationally driven. Since the rotation of the motor 25 is not transmitted to the other three drive shafts 26a to 26c, the stirring members built in the magenta, cyan and black toner containers 12a to 12c are not driven.

  Thus, according to the drive transmission device according to the present embodiment, the first drive train G1 always transmits the rotation to the black toner container 12d even when the motor 25 is rotated in the forward and reverse directions, so that the toner container 12d is always driven. On the other hand, since the one-way clutch 34 is provided in the second drive train G2, the second drive train G2 selectively selects the magenta, cyan, and yellow toner containers 12a to 12c by forward and reverse rotation of the motor 25. To drive. Specifically, the magenta, cyan, and yellow toner containers 12a to 12c are driven only when the motor 25 is rotated forward in the color mode.

  Therefore, according to the drive transmission device according to the present embodiment, all the toner containers 12a to 12d can be driven by the single motor 25 in the color mode, and the motor 25 is reversed in the monochrome mode. Only the toner container 12d can be driven. In other words, the motor 25 can be switched between the color mode for driving all the toner containers 12a to 12d and the monochrome mode for driving only the black toner container 12d by rotating the motor 25 forward and backward. In addition to cost reduction associated with this, continuous operation and noise reduction are possible.

  In the present embodiment, the motor 25 is rotated forward and backward to switch the drive modes of the toner containers 12a to 12d with a simple configuration in which the idle gear G16 is interposed between the driven gear G13 ′ and the gear G14. That is, regardless of whether the color mode or the monochrome mode is selected, the black toner container 12d driven by the first drive train G1 can be rotationally driven in the same direction. That is, when the color mode for driving all the toner containers 12a to 12d is selected, the agitating members of all the toner containers 12a to 12d are driven to rotate in the same direction, and the monochrome driving only the black toner container 12d is performed. When the mode is selected, the stirring member of the black toner container 12d is driven to rotate in the same direction (the same direction as when all the toner containers 12a to 12d are driven in the color mode). The rotation direction of the stirring member built in the toner container 12d does not reverse.

  The drive transmission device that rotationally drives the stirring member of the toner container has been described above. However, the present invention can be similarly applied to a drive transmission device that rotationally drives any other unit. It is.

1 is a cross-sectional view of a full-color image forming apparatus (color laser printer) according to the present invention. It is a front view of the drive transmission device concerning the present invention. It is a front view which shows the operation | movement at the time of the color mode of the drive transmission apparatus which concerns on this invention. It is a front view which shows the operation | movement at the time of the monochrome mode of the drive transmission apparatus which concerns on this invention. It is a figure of the arrow A direction of FIG. It is a perspective view of the rotational movement gear used for the drive transmission device concerning the present invention.

Explanation of symbols

1M Magenta image forming unit 1C Cyan image forming unit 1Y Yellow image forming unit 1K Black image forming unit 2a to 2d Photosensitive drum 3a to 3d Charge roller 4a to 4d Developing device 5a to 5d Transfer roller 6a to 6d Drum cleaning device 7 Intermediate transfer belt 8 Secondary transfer counter roller 9 Tension roller 10 Secondary transfer roller 11 Belt cleaning device 12a to 12d Toner container (unit)
13 Laser scanner unit (LSU)
DESCRIPTION OF SYMBOLS 14 Paper feed cassette 15 Pickup roller 16 Feed roller 17 Retard roller 18 Conveyance roller pair 19 Registration roller pair 20 Conveyance roller pair 21 Paper discharge tray 22 Fixing device 23 Paper discharge roller pair 24 Drive transmission device housing 25 Motor 26a-26d Drive shaft 27 Rotating shaft 28a to 28d Pulley 29a to 29d Driving belt 30a to 30d Rotating shaft 31 Holder 32 Pressing spring 33 Shaft 34 One-way clutch G1 First driving train G11 Gear G12 Rotating gear G13, G13 ′ Driven gear G14, G15 Gear G16 Idle gear G2 Second drive train G21 to G26 Gear Ga to Gd Gear Gp Pinion gear 100 Image forming apparatus main body L, L ′ Conveyance path

Claims (5)

In a drive transmission device of a full-color image forming apparatus that transmits rotation of a motor to a black image forming unit and a plurality of magenta, cyan, and yellow color image forming units through a plurality of drive trains to rotate each unit.
Dividing the plurality of drive trains into two,
Wherein the first drive train for driving only the black image forming unit, provided the rotational movement gear selectively engaged by the forward and reverse rotation of the motor to either of the two driven gears,
The second image train that drives the color image forming unit selectively drives the color image forming unit by selectively transmitting the rotation of the motor by turning on and off by forward / reverse rotation of the motor. A one-way clutch,
A drive transmission device characterized in that it can be switched between a color mode for driving all of the black image forming unit and the color image forming unit and a monochrome mode for driving only the black image forming unit by forward and reverse rotation of the motor.   The rotational movement gear is supported so as to be rotatable about a rotation shaft of a gear meshing with the gear, and is rotated by a load torque caused by meshing of both gears to selectively mesh with any one of the driven gears. The drive transmission device according to claim 1. 3. The black image forming unit driven by the first drive train is configured to rotate in the same direction regardless of which of the driven gear meshes with the driven gear. Drive transmission device.   4. The drive transmission device according to claim 3, wherein an idle gear is engaged with one of the driven gears. In a full-color image forming apparatus provided with a plurality of image forming units,
A full-color image forming apparatus characterized by digits set the drive transmission device according to any one of claims 1 to 4.

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