JPH04280273A - Developing machine select and drive device for multicolor image formation device - Google Patents

Abstract

PURPOSE:To obtain a developing machine select and drive device enabling a work to be carried out smoothly with a small force, when necessary to select the predetermined developing machine from a plurality of developing machines by causing a shift gear and a drive gear to be engaged with and disengaged from each other. CONSTITUTION:A reverse rotation device 33 for reversing a motor 20 by the predetermined amount is provided for releasing the engagement of a shift gear 23 to transmit torque to a developing machine 12 with a drive gear 22 to receive power transmitted from the motor 20. The motor 20 is stopped to be released from engagement with the shift gear 23. In this state, both the shift gear 23 and drive gear 22 still remain subjected to a load from the developing machine 12. When the drive gear 22 is reversed by an amount such as backlash of the shift gear 23, drive gear 22 and the like with the reverse rotation device 33, therefore, the load acting on the shift gear 23 is eliminated, and the shift thereof becomes easy.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device switching drive device for a multicolor image forming apparatus equipped with a plurality of developing devices.

0002

2. Description of the Related Art First, the outline of a multicolor image forming apparatus will be explained with reference to FIG.
, yellow developer 12A, magenta developer 12B, cyan developer 12C, black developer 12D, transfer drum 1
3. A cleaning device 14 is provided, a paper feeding unit 15 is provided below the cleaning device 14, an optical unit 16 is provided above the cleaning device 14, and a fixing device 17, a paper discharge tray 18, etc. are provided to the left. Here, a developing sleeve 12a, etc., which rotates in a predetermined direction to perform a developing operation, is attached to each developing device 12. Also, a photosensitive drum 10, a charging roller 11, a developing device 12,
The cleaning device 14 forms a process cartridge 19 that is integrally inserted into and removed from the apparatus main body 1.

That is, when the image light L of the yellow image is exposed to the photosensitive drum 10 uniformly charged by the charging roller 11 through the optical unit 16, the photosensitive drum 10
An electrostatic latent image is formed thereon. The electrostatic latent image is moved toward the yellow developing device 12A as the photosensitive drum 10 rotates, and yellow toner is supplied through the developing sleeve 12a of the yellow developing device 12A to develop it as a toner image. This toner image is then transferred onto a transfer paper positioned and fixed on the transfer drum 13. When the residual toner is cleaned by the cleaning device 14, magenta, cyan, and black toner images are again created on the photosensitive drum 10, and these are similarly transferred onto the transfer drum 13. Multiple transfers are made on paper.

On the other hand, after the transfer paper is positioned and fixed on the outer surface of the transfer drum 13 via the paper feed unit 15 etc., toner images of multiple colors are multiple-transferred onto it via the photosensitive drum 10 etc., but this process is When this is completed, the toner image is transported to a fixing device 17, where the toner image is fixed as a permanent image. The transfer paper on which the color image has been formed is then stacked on the paper discharge tray 18.

The developing device 12 disposed around the photosensitive drum 10 is selectively switched and used depending on the type of image, but it is necessary to rotate the developing sleeve 12a and the like when using the developing device 12. Therefore, this developing device switching drive device will be explained below with reference to FIGS. 26, 2, and 3.

20 in FIG. 26 is a motor, and the motor 2
Power is transmitted from the photosensitive drum 10 via a belt 21 to a drive gear 22 coaxially provided with the drum shaft of the photosensitive drum 10 . Shift gears 23 are provided around the drive gear 22 in a number equal to the number of developing devices 12.
2, and is meshed with a driven gear 24 that transmits rotational force to the developing sleeve 12a, etc., which is the load of the developing device 12. As shown in FIGS. 2 and 3, the shift gear 23 is movable on a support shaft 30 attached to the inner wall 1a of the device body 1, and is normally attached in the direction of the arrow in FIG. 2 via a spring member 31. The rotational force of the driving gear 22 is transferred to the driven gear 2 by meshing with the driving gear 22 and the driven gear 24.
I am telling 4. Note that a conical pressing portion 23a is provided on the outer surface of the shift gear 23.

On the other hand, a pressure cam 25 is attached to the drive shaft 32 of the drive gear 22 and is rotated independently by a drive source different from the drive gear 22, and the side surface of the pressure cam 25 is shown in FIG. As shown, the pressing portion 23 of the shift gear 23
a, the shift gear 23 is moved to the vicinity of the main body inner wall 1a, and the shift gear 23 and the drive gear 2
2 has been disengaged. Note that even in this case, the shift gear 23 and the driven gear 24 maintain a partially meshed state.

Furthermore, since the pressure cam 25 is provided with a notch 25a as shown in FIG. The state of meshing with the drive gear 22 is maintained without being affected. That is, the yellow developing device 1A in FIG.
Only the shift gear 23 meshes with the drive gear 22, as shown in FIG.
4 to the load such as the developing sleeve 12a.

In order to select the desired developer 12 (for example, the cyan developer 12C), first the motor 20 is stopped to stop its rotation, and the shift gear for the yellow developer 12A is shifted as shown in FIG. 23 and the drive gear 22 must be disengaged. For this purpose, the pressure cam 25
rotate and insert the notch 25a into the cyan developer 12C.
When the shift gear 23 is moved toward the shift gear 23, the shift gear 23
The pressing portion 23a is pushed by the side surface of the pressing cam 25 and moves as shown in FIG. 3, and the engagement between the shift gear 23 and the drive gear 21 is released.

Simultaneously with this release, the motor 20 is driven and the drive gear 22 starts rotating, and the notch 25a of the pressure cam 25 is connected to the shift gear 23 of the cyan developing device 12C.
The shift gear 23 is pushed by the spring member 31, meshes with the drive gear 22, and rotates. Therefore, the shift gear 23 of the cyan developer 12C also rotates, and the load of the shift gear 23, such as the developing sleeve 12a, also rotates.

[0011]

However, in the developing device switching drive device according to the above-mentioned prior art, when the drive of the motor 20 is stopped and the engagement between the shift gear 23 and the drive gear 22 is released, the drive gear 22 , the shift gear 23 and the driven gear 24 are still loaded with a load corresponding to the torque required to rotationally drive the developing sleeve 12a, etc., so a large force is required to move the shift gear 23. Therefore, it is necessary to increase the driving source of the pressurizing cam 25, and if the shift gear 23 is moved against a large load, a large drive and noise will be generated during the movement, and the image quality will be degraded. There was a problem.

Furthermore, when the shift gear 23 is engaged with the drive gear 22, the drive gear 22 is rotating and
The developing device 12 is connected to the shift gear 23 via a driven gear 24.
Because the load on the side (developing sleeve 12a, etc.) is directly connected,
There was a problem in that the shift gear 23 was repelled by the drive gear 22 and the meshing thereof did not go smoothly. For this reason,
Although there is an idea to increase the elastic force of the spring member 31 of the shift gear 23, there is a problem in that the driving load on the pressure cam 25 becomes large.

The present invention has been made in view of the above problems, and its purpose is to select a predetermined developing device from a plurality of developing devices by engaging and disengaging the shift gear and the drive gear. To provide a developing unit switching drive device for a multicolor image forming apparatus, which can smoothly engage and disengage a drive gear and a shift gear with a small force.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present invention disposes driven gears that respectively rotate driven parts of a plurality of developing units around a driving gear that transmits power of a motor, and drives By moving a shift gear disposed between a gear and a driven gear and transmitting the power of the motor to the driven gear while being engaged with the driven gear and causing it to engage or disengage from the drive gear, the desired color can be achieved. In a developing device switching drive device of a multicolor image forming apparatus that is capable of driving a developing device containing toner, a reverse rotation device is provided that reverses the motor by a predetermined amount before stopping when disengaging the shift gear from the drive gear. It is characterized by:

Further, the present invention provides a drive gear that rotates the driven parts of a plurality of developing devices around the drive gear that transmits the power of the motor, and a drive gear that rotates the driven parts of the plurality of developing devices, and a drive gear that rotates the driven parts of the plurality of developing units. By moving the shift gear that transmits the power of the motor to the driven gear while being engaged with the driven gear and causing it to engage or disengage from the drive gear, it is possible to drive a developing device having a required color toner, and , in a developing device switching drive device of a multicolor image forming apparatus in which the driving gear is in a rotating state when the shift gear meshes with the driving gear, a predetermined amount of play is provided in the rotational direction between the driven portion of the developing device and the shift gear. In addition, the present invention is characterized in that a play retaining mechanism is provided that maintains this play in a direction opposite to the rotational direction of the driven part when the shift gear and the drive gear are disengaged.

[0016]

[Operation] When selecting a desired developing device from multiple developing devices, shift the shift gear that is provided corresponding to the developing device and is always in mesh with the driven gear (rotating the driven part) of the developing device. Then, it is necessary to mesh or disengage this with the drive gear that transmits the power of the motor.

That is, it is necessary to disengage the shift gear and drive gear of a developing device that is no longer needed, and to mesh the shift gear and drive gear of a necessary developing device. In this case, it is assumed that the rotation of the drive gear is stopped when the shift gear is disengaged, but the drive gear is rotated when the shift gear is engaged.

[0018] In the invention according to claim 1, a reverse rotation device is provided for reversing the motor by a predetermined amount when disengaging the shift gear from the drive gear. This reverse rotation device reversely rotates the drive gear and shift gear by the maximum amount of backlash between the gears. As a result, the load condition between the shift gear, the driving gear, and the driven gear is eased, and the shift gear can be easily moved.

Further, in the invention according to claim 3, when the shift gear and the drive gear are brought into mesh with each other, a predetermined amount of play is provided in the rotational direction between the driven portion of the developing device and the shift gear, and the shift gear and the drive gear are engaged with each other. A play retention mechanism is provided to maintain this play in the opposite direction to the rotational direction of the driven part when the mesh is released. Therefore, when the shift gear meshes with the drive gear, the gear interposed between the driven part of the developing device and the shift gear, for example, the driven gear, always has some play in the forward rotation direction, and the shift gear slightly engages the driven gear. Even if the developing device is engaged with the drive gear in a state where it is rotated, the driven portion of the developing device will not rotate. Therefore, the shift gear can easily mesh with the drive gear.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings.

First, a first embodiment of the present invention will be explained with reference to FIGS. 1 to 9.
This is explained by:

FIG. 1 shows a side view of a developing device switching drive device, etc. of a multicolor image forming apparatus. This developing device switching drive device includes a motor 20 as a drive source, a belt 21 that transmits the driving force of the motor 20, a drive gear 22 rotated by the belt 21, and a drive gear 22 that is spaced apart from each other around the drive gear 22. Yellow, magenta, cyan, and black developing units 12 installed
A, 12B, 12C, 12D four driven gears 24 that rotate the developing sleeve 12a, etc., which are loads, respectively;
..., shift gears 23 disposed between the driven gears 24 and the driving gears 22 by the number of driven gears 24, and the driving gears 22.
The pressure cam 25 is provided coaxially with the drive shaft 32 of No. 2, and is rotated by a drive source (not shown).

The shift gear 23 is movable on a support shaft 30 provided on the inner wall 1a of the main body of the image forming apparatus as shown in FIGS.
is urged in the direction of the arrow in FIG. On the other hand, the pressure cam 25 engages with the pressing portion 23a of the shift gear 23, as shown in FIG.
By pressing the shift gear 23 toward the a side, the meshing between the shift gear 23 and the drive gear 22 is released, and only the shift gear 23 located in the notch groove 25a provided on the outer circumference of the shift gear 23 is disengaged from the drive gear 22. I try to engage them selectively. That is, only the shift gear 23 located within the notch groove 25a of the pressure cam 25 meshes with the drive gear 22,
The driven gear 24 of the developing device 12 corresponding to the shift gear 23 is rotated, and loads such as the developing sleeve 12a are rotationally driven.

[0024] Here, the detailed structure and operation of this developer switching drive device and the structure and operation of a multicolor image forming apparatus equipped with this developer switching drive device are the same as those explained in the section of the prior art. , the explanation thereof will be omitted. In FIG. 1, 10 is a photosensitive drum, and 14 is a cleaning device.

Now, the shift gear 2 is
When releasing the mesh with the drive gear 22 of No. 3, the motor 20
After stopping the rotation of the drive gear 22, the shift gear 23 is moved to the main body inner wall 1a of the support shaft 30 via the pressure cam 25.
However, since the force for the load of the developing unit 12 (developing sleeve 12a, etc.) is still acting on the driving gear 22, shift gear 23, and driven gear 24, the pressure cam 25 The force acting on it becomes large.

Therefore, in the present invention, when disengaging the shift gear 23 from the drive gear 22, the motor 20 is
That is, the shift gear 23, the driving gear 23, and the driven gear 24
A reverse rotation device 33 is provided which reversely rotates the gears by the amount of backlash between the gears, and the operation of the reverse rotation device 33 creates a slight play between the shift gear 23, the drive gear 22, and the driven gear 24. . This makes it easy to move the shift gear 23, so the force applied to the pressure cam 25 is small, and vibrations, noise, etc. that occur when the shift gear 23 moves can be prevented.

In this case, as shown in FIGS. 4 and 5,
Of course, the shift gear 23 may be moved by the solenoid 26 via the actuating member 27 without using the pressure cam 25.

Next, a first modification of this embodiment will be explained with reference to FIGS. 6 to 8. In this modified example, shift gear 2
3 does not move on the support shaft 30 and remains meshed with the driven gear 24, as shown in FIGS. It is designed to selectively mesh with the shift gear 23. Movement of the drive gear 22 is performed by a moving member 34 fixed to the drive gear 22 and threaded onto a screw shaft 35, and by forward and reverse rotation of the screw shaft 35 rotated by a drive source (not shown). Note that the drive gear 22 is rotated via a motor 20, a belt 21, and a gear 28, as shown in FIG. Also in this modified embodiment, a reverse rotation device 33 for reversing the motor 20 when switching the developing device 12 is provided, and the drive gear 22 and shift gear 23
Since play is provided between the drive gear 24 and the driven gear 24, the same effects as in the first embodiment can be obtained.

Further, as a second modified embodiment, there is a developing device switching drive device shown in FIG. This is shift gear 23
and the driven gear 24 of the developing unit 12 are integrated via a belt member 29 etc., and this shift gear 23 is integrated with the driven gear 24 of the developing device 12.
By moving the shift gear 23 on the circumference of the driven gear 24 in a state in which the shift gear 23 is engaged with the drive gear 22, the shift gear 23 is selectively engaged with the drive gear 22, and the developing unit 12 is switched. Also in this modified embodiment, a reverse rotation device 33 for reversing the motor 20 when switching the developing device 12 is provided, and play is provided between the drive gear 22, the shift gear 23, and the driven gear 24, so that the shift gear 23 Switching becomes easy and the same effect as the first embodiment can be obtained.

Next, a second embodiment of the present invention will be explained with reference to FIGS. 10 to 16. Components having the same functions as those in the first embodiment are designated by the same reference numerals, and their explanations will be omitted.

In the first embodiment, when switching the developing device 12, the motor 20 is reversed by the reverse rotation device 33 to provide play between the drive gear 22 and the shift gear 23, etc. 33 is too small, the shift gear 23, drive gear 22, and driven gear 2
If the load between the drive gear 24 and the drive gear 4 cannot be removed sufficiently and the amount of rotation is too large, the driven gear 24 will rotate in the opposite direction, adversely affecting the developing sleeve 12a, etc., and also cause the shift gear 23, etc. to rotate in the opposite direction. This causes a problem in that the shift gear 23 becomes difficult to move.

Therefore, in the developing device switching drive device according to the present embodiment, even if the amount of reverse rotation by the reverse rotation device 33 of the motor 20 varies somewhat, there is sufficient play between the shift gear 23, the driving gear 22, and the driven gear 24. A play compensation mechanism was installed to compensate for this. The developing device switching drive device according to this embodiment is intended for the one shown in FIGS. 1 to 3 of the first embodiment.

FIGS. 10 to 12 are for explaining the first play compensation mechanism. Driven gear 24 and developer 1
The driven shaft 40 of the second load (developing sleeve 12a) is fitted in a half-moon shape as shown in FIG. As shown, the cutout allows the driven shaft 40 and the driven gear 24 to have some play in their rotational direction.

The shift gear 23 rotates in the direction shown in FIG. 11 and transmits its rotational force to the driven gear 24.
In this case, a portion 41a in the figure of the fitting hole 41 of the driven gear 24 engages with the driven shaft 40, and the driven gear 24 is rotated. Then, the motor 20 is reversed to switch the developing device 12, but in this case, the amount of reverse rotation of the drive gear 22 is greater than the amount of backlash between the drive gear 22, shift gear 23, and driven gear 24, and the driven gear 24 is Even when the driven gear 24 rotates slightly, there is sufficient play between the driven gear 24 and the driven shaft 40 until the chord part of the driven shaft 40 reaches the portion 41b of the fitting hole 41 of the driven gear 24. Therefore, the driven shaft 40 does not rotate in the opposite direction. Therefore, the shift gear 23
It also becomes easier to move.

FIGS. 13 and 14 show the second play compensation mechanism. A gear 42 having two bosses 42a, 42a is fixedly provided on the driven shaft 40, and the boss 42a of this gear 42 is inserted into the arcuate grooves 43, 43 provided in the driven gear 24.
, 42a are engaged.

That is, when the shift gear 23 rotates in the direction of the arrow in FIG.
The driven shaft 40 is rotated by engagement between the boss 42a and the boss 42a. Even if the amount of reverse rotation of the driving gear 22 is large when switching the developing device 12, the arc-shaped groove 43 of the driven gear 24
The driven shaft 40 will not rotate in the opposite direction until the boss 42a moves to the portion 3b. During this time, the shift gear 23 can also be easily moved. In this case, the power can be transmitted to another gear 44 via the gear 42, and the power can be quickly and smoothly transmitted to the load of the developing device 12.

FIG. 15 shows a third play compensation mechanism, and FIG. 16 shows a fourth play compensation mechanism. 15, the rotational force of the driven gear 24 is transmitted to the driven shaft 40 via the one-way clutch 45, and the motor 2
Regardless of the amount of reverse rotation of 0, the driven shaft 40 is not always reversed, and the shift gear 23 can be easily moved. Figure 1
In No. 6, the driven gear 24 is constituted by a spring clutch gear, and the slip of the spring 46 is used to prevent the driven shaft 40 from reversing, and it functions similarly to the one-way clutch 45.

Next, a third embodiment of the present invention will be described with reference to FIGS. 17 to 24. Components having the same functions as those in the first and second embodiments are designated by the same reference numerals and their explanations will be omitted.

In the developing device switching drive device according to the first embodiment shown in FIGS. 1 to 3, a predetermined developing device 12 is selected, its shift gear 23 is positioned in the cutout portion 25a of the pressure cam 25, and this is driven. When meshing with the gear 22, the driven gear 24 is directly connected to the load side of the developing device 12, and the drive gear 22 is rotating, so the shift gear 23 is connected to the drive gear 2.
The problem is that it is repelled by the second class and cannot mesh well with it.

Therefore, in the developing device switching drive device according to this embodiment, the driven gear 24 and the driven shaft 4 of the load of the developing device 12 are
0 in the rotational direction similar to that shown in the first embodiment, and when the shift gear 23 and the drive gear 22 are disengaged, this play is used to reduce the load on the developing device 12 (developing sleeve 12a, etc.). ) is provided, and when the shift gear 23 meshes with the drive gear 22, the shift gear 2 is held in the opposite rotational direction.
3 can be rotated independently of the driven shaft 40 of the developing device 12, that is, without any load. This allows the shift gear 23 to easily mesh with the drive gear 22.

17 to 19 show the first play retaining mechanism, and as shown in FIG. 19, there is a gap between the driven shaft 40 and the driven gear 24 that is the same as that shown in the second embodiment. A play in the rotational direction is formed. The driven gear 24 rotates in the direction of the arrow in FIG. 19, and the portion 41a of the fitting groove 41 engages with the string portion of the driven shaft 40, causing the driven shaft 40 to rotate. Further, as shown in FIGS. 18 and 19, the driven shaft 40 is provided with a coil spring 5 having one end fixed to the driven shaft 40 and the other end attached to the driven gear 24.
0 is attached, and the driven gear 24 is rotated in the opposite direction of rotation by the coil spring 50, that is, 41 of the fitting groove 41.
The b section is biased to engage with the string section of the driven shaft 40.

When the pressure cam 25 rotates when switching the developing device 12 and its notch groove 25a is positioned on the shift gear 23 of the desired developing device 12, the shift gear 23 is moved by the action of the spring member 31. As a result, the drive gear 22 attempts to engage with the drive gear 22. In this case, since a predetermined amount of play is secured between the shift gear 23 and the driven gear 24 without causing the driven shaft 40 to rotate, the shift gear 23 is not repelled by the drive gear 22, etc., and is securely rotated. It meshes with the drive gear 22.

FIGS. 20 and 21 show a second play retaining mechanism, in which the arcuate groove 52 of the driven gear 24 is engaged with the boss 51a of the gear 51 fixed to the driven shaft 40, and A spring member 5 is inserted between the boss 51a and the driven gear 24.
3 is attached so that the spring member 53 biases the driven gear 24 in a direction opposite to its rotational direction. Even in this case, play is maintained between the driven gear 24 and the driven shaft 40 to the extent that the boss 51a can move between the arcuate grooves 52,
Accordingly, the meshing of the shift gear 23 with the drive gear 22 is ensured.

FIGS. 22 and 23 show a third play retaining mechanism, in which coaxial first and second gears 54 and 55 are interposed between the shift gear 23 and the driven gear 24. The first gear 54 that meshes with the shift gear 23 has a boss 5.
4a, the boss 54a engages with the arcuate groove 56 of the second gear 55, and a coil spring 57 is attached between the boss 54a and the second gear 55, and the coil spring 57 causes the second gear to 55 is biased in a direction opposite to its rotational direction. Since the second gear 55 meshes with the driven gear 24, the shift gear 23 has some play in rotation to allow the boss 54a to move within the arcuate groove 56 regardless of the driven gear 24. Therefore, this shift gear 23 is reliably meshed with the drive gear 22.

FIG. 24 shows a fourth play retaining mechanism, in which coaxial first and second gears 54 and 55 are interposed between the shift gear 23 and the driven gear 24, as in the third play retaining mechanism. A plurality of cam protrusions 58 are provided on the side surface of the first gear 54 that meshes with the shift gear 23, and are engaged with a plurality of protrusions 55a of the second gear 55. First and second gears 54, 54
A spring member 60 is attached to the fixed shaft 59 of the cam projection 58 of the first gear 54, and the second gear 55 is biased toward the first gear 54 by the spring member 60. 58a.

When the first gear 54 rotates together with the rotation of the shift gear 23, the oblique side 58a of the cam protrusion 58 moves the second gear 55 against the elastic force of the spring member 60.
Push up the vertical part 58b of the cam projection 58 in the direction of the arrow in the figure.
The second gear 55 rotates as the side surface of the protrusion 55a engages with the protrusion 55a, thereby causing the driven gear 24 to rotate. On the other hand, when the rotation of the shift gear 23 stops, the second gear 55 is pushed by the spring member 60 and its protrusion 55a moves to the oblique side 58a of the cam protrusion 58. As a result, the first gear 54 rotates in the opposite direction by a predetermined amount, and the shift gear 2
3, a predetermined amount of play can be secured between the two.

[0047]

Effects of the Invention As is clear from the above description, according to the present invention, a reverse rotation device is provided for reversing the motor by a predetermined amount when disengaging the shift gear and the drive gear, so that the shift gear, the drive gear, and the driven gear are The load between the gears is released, and the shift gear can be smoothly disengaged from the drive gear with a small force. Therefore, the load on the disengagement mechanism is reduced, and vibration and noise are also reduced during disengagement.

Furthermore, when the shift gear and the drive gear are brought into mesh with each other, a play retainer is provided between the shift gear and the driven part of the developing device to provide play in the rotational direction of the driven part. The meshing is done smoothly with a small amount of force.

[Brief explanation of the drawing]

FIG. 1 is a side view of a developing device switching drive device according to a first embodiment.

FIG. 2 is a partial plan view of the developing device switching drive device.

FIG. 3 is an explanatory diagram of the operation of the developing device switching drive device.

FIG. 4 is an explanatory diagram when a shift gear of the developing device switching drive device is moved by a solenoid.

FIG. 5 is an explanatory diagram when the shift gear of the developing device switching drive device is moved by a solenoid.

FIG. 6 is a side view of a developing device switching drive device according to a first modified example of the first example.

FIG. 7 is a partial plan view of the developing device switching drive device.

FIG. 8 is an explanatory diagram of the operation of the developing device switching drive device.

FIG. 9 is a side view of a developing device switching drive device according to a second modified example of the first example.

FIG. 10 is a first example of a developing device switching drive device according to a second embodiment;
It is an explanatory view of the play compensation mechanism of.

11 is a view taken along the line X1-X1 in FIG. 10. FIG.

FIG. 12 is a diagram for explaining the mounting state of the driven gear and driven shaft of the first play compensation mechanism of the developing device switching drive device.

FIG. 13 is an explanatory diagram of a second play compensation mechanism of the developing device switching drive device.

FIG. 14 is a view taken along the line X2-X2 in FIG. 13;

FIG. 15 is an explanatory diagram of a third play compensation mechanism of the developing device switching drive device.

FIG. 16 is an explanatory diagram of a fourth play compensation mechanism of the developing device switching drive device.

FIG. 17 is a first example of a developing device switching drive device according to a third embodiment;
It is an explanatory view of the play retention mechanism of.

18 is a view taken along the Y1-Y1 arrow in FIG. 17. FIG.

FIG. 19 is a diagram for explaining the attachment state of the driven gear and the driven shaft of the first play retaining mechanism of the developing device switching drive device.

FIG. 20 is an explanatory diagram of a second play retaining mechanism of the developing device switching drive device.

21 is a view taken along the Y2-Y2 arrow in FIG. 20. FIG.

FIG. 22 is an explanatory diagram of a third play retaining mechanism of the developing device switching drive device.

23 is a view taken along the line Y3-Y3 in FIG. 22. FIG.

FIG. 24 is an explanatory diagram of a fourth play retaining mechanism of the developing device switching drive device.

FIG. 25 is a side sectional view of the multicolor image forming apparatus.

FIG. 26 is a side view of a developing device switching drive device according to the prior art.

[Explanation of symbols]

12 Developing device 20 Motor 22 Drive gear 23 Shift gear 24 Driven gear 33 Reverse rotation device

Claims (3)

[Claims] Claim 1: A driven gear that rotates each of the driven parts of a plurality of developing units is disposed around a drive gear that transmits power of a motor, and a driven gear that is disposed between the drive gear and the driven gear, and that is disposed between the drive gear and the driven gear. By moving the shift gear that transmits the power of the motor while meshing with the driven gear to engage or disengage it from the drive gear, it is possible to drive a developing device containing the necessary color toner. A developing unit of a multicolor image forming apparatus, characterized in that the developing unit switching drive device of the forming apparatus is provided with a reverse rotation device that reverses the motor by a predetermined amount before stopping when disengaging the shift gear from the drive gear. Switching drive. 2. The multicolor image forming apparatus according to claim 1, further comprising a play compensation mechanism that provides a predetermined amount of play in the rotational direction between the driven portion of the developing unit and the driven gear. Developer switching drive device. 3. A driven gear that rotates each of the driven parts of a plurality of developing units is disposed around a drive gear that transmits the power of the motor, and a driven gear that is disposed between the drive gear and the driven gear, and that is disposed between the drive gear and the driven gear. By moving the shift gear that transmits the power of the motor while being engaged with the driven gear to engage or disengage it with the drive gear, it is possible to drive the developing unit containing the necessary color toner, and the shift gear In a developing device switching drive device of a multicolor image forming apparatus in which the driving gear is in a rotating state when meshing with the driving gear, a predetermined amount of play is provided in the rotational direction between the driven portion of the developing device and the shift gear, and the shift gear 1. A developing unit switching drive device for a multicolor image forming apparatus, characterized in that a play holding mechanism is provided for holding this play in a direction opposite to the rotational direction of a driven part when meshing with a drive gear is released.