JP2006126596A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve stop position precision of a rotary without pursuing high precision of components by achieving a calm situation upon positioning the rotary while securing drive stability of the rotary. <P>SOLUTION: An image forming apparatus separates a second elastic friction member 26c from a first elastic friction member 24c by switching on a solenoid 29 and turning a swing bracket 25 by the excitation force clockwise by centering a turning shaft 23a. Thereby a locking means 21 is at a non-locked position, and is in an unlocking state of the rotary 13. The image forming apparatus contacts the second elastic friction member 26c on the first elastic friction member 24c by switching off the solenoid 29 and turning the swing bracket 26c on the first elastic friction member 24c by biasing force of a biasing spring 27 counterclockwise by centering the rotating shaft 23a. Thereby the locking means is at a locked position and is in a locking state of the rotary 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technology of an image forming apparatus such as an electrostatic copying machine or a printer, which includes a developing device of a rotary developing system that performs multi-color development of two or more colors such as full color by a plurality of developing devices mounted on the rotary. In particular, the image includes a locking unit that positions and locks the rotary at a predetermined position so that the developer carriers of a plurality of developing units are selectively set at the development position with respect to the latent image carrier. The present invention relates to the technical field of forming apparatuses.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as an electrostatic copying machine or a printer, an image forming apparatus including a developing device that performs multicolor development of two or more colors such as full color by a plurality of developing devices mounted on a rotary. Various devices have been developed. In this image forming apparatus, a rotary is rotated during an image forming operation so that the developing roller of each developing device is sequentially set to the developing position, and the latent image on the photoreceptor is sequentially developed for each color to form an image. Yes.

  The simplest way to position and lock the rotary in place is to use the holding force of the drive motor to rotate the rotary, but consider the power consumption and holdability of the drive motor during hold. Then, it is desirable to position the rotary by some mechanical means without depending on the holding force of the drive motor. Therefore, conventionally, it has been proposed to mechanically position the rotary by engaging the convex portion or concave portion of the lever provided in the image forming apparatus main body with the concave portion or convex portion of the rotary, respectively (for example, (See Patent Document 1 and Patent Document 2).

In these mechanical rotary positioning means disclosed in Patent Document 1, a biasing spring is attached to a concave groove of a cam in which a stop roller, which is a convex portion provided on a lever, is provided so as to be integrally rotatable with a rotary. The rotary is mechanically positioned by engaging with the force, and the rotary is unpositioned by letting the stop roller escape from the cam groove with the cam profile of the cam. Further, the mechanical rotary positioning means disclosed in Patent Document 2 is such that the concave portion provided in the lever is provided integrally with the rotary, and the rotary is mechanically engaged with the convex portion by the biasing force of the biasing spring. In addition to positioning, the rotary position is released by causing the concave portion of the lever to escape from the convex portion of the rotary by the excitation force of the solenoid.
[Japanese Patent Publication No.7-1117784] [Japanese Patent Laid-Open No. 2004-145272]

  However, in the mechanical rotary positioning means disclosed in Patent Documents 1 and 2 described above, when the lever is engaged with the rotary to position the rotating rotary, a collision noise between the rotary and the lever is generated. In particular, along with the recent increase in image formation speed, the rotary switching speed of the rotary is also increased, and the switching operation between the lever rotary position and the engagement release position is also speeded up. Therefore, there is a problem that the impact between the rotary and the lever becomes large, and the collision sound due to the impact cannot be ignored.

  For this reason, it is conceivable to reduce the impact and reduce the impact sound by using a damper such as a cushioning material. However, when such a damper is used, the rotational load of the rotary caused by an imbalance of the remaining amount of toner in a plurality of developing units, the non-mounting of some developing units in the rotary, or the development driving during development If the lever is moved to release the engagement with the rotary while the rotary is twisted due to the moment generated by the reaction force, etc., the surface friction in the release direction of the lever and the rotary increases. As a result, the force for releasing the lever from the engagement with the rotary is increased, which causes a problem that the driving stability of the rotary is affected.

Moreover, the rotational stop position shift of the rotary occurs due to the elastic deformation of the gear caused by the backlash and inertia of the gear power transmission mechanism that transmits the driving force of the motor to the rotary in the rotary drive unit. Therefore, it is necessary to provide clearance (engagement) to the concave and convex portions (engagement portions) of the lever and the rotary. However, after the motor is stopped, the rotary is stopped at the position where the engagement is moved indefinitely from the position where the rotary is stopped due to the above-described offset load. For this reason, if the engagement is excessively large, the stop position of the rotary is greatly shifted, and particularly in the case of a stepping motor frequently used for a rotary drive motor, the motor may step out at the next start-up. There is. Specifically, as the converted angle on the rotary shaft, the rotary stop position angle error is δ, the backlash of the rotary drive unit is B, the engagement of the stop means is s, the rotary drive reduction ratio is n, and the drive If the motor step angle is θ,
δ = B + s <n × θ
Must be satisfied. However, in order to satisfy this, it is necessary to reduce the above-mentioned clearance. To that end, not only the dimensional tolerance of the concave and convex portions of the lever and the rotary has to be set strictly but also the engagement of the concave and convex portions. Defects may occur, or the moving force at the time of releasing the lever engagement may increase due to the aforementioned twisting of the rotary.

  In this way, the control of the solenoid that controls the engagement between the lever and the rotary is precisely matched with the rotary rotation control, and the dimensional tolerances of the parts are set strictly. There is a problem that adjustment is necessary and it is necessary to improve the accuracy of parts such as a lever and a rotary.

  The present invention has been made in view of such circumstances, and the object thereof is to achieve quietness when positioning the rotary while ensuring the driving stability of the rotary, An object of the present invention is to provide an image forming apparatus capable of improving the stop position accuracy of a rotary without pursuing higher accuracy.

  In order to solve the above-mentioned problems, the invention of claim 1 is a rotary device that is rotatably provided and includes a plurality of developing devices, a drive source that rotationally drives the rotary devices, and the developing devices are selectively specified. Locking means for positioning the rotary to set the position and locking to the positioning position, and positioning the rotary by the locking means to selectively select one of the plurality of developing devices. In the image forming apparatus which is set at a development position facing the image carrier and the latent image on the image carrier is developed by the developing device set at the development position, the lock unit includes the image forming unit. A first gear that is provided in the apparatus main body so as to rotate in conjunction with the rotation of the rotary and is fixed in position, and a first gear that rotates concentrically and integrally with the first gear. And a second gear provided on the image forming apparatus main body in association with the rotation of the rotary and so as to rotate in the same rotation direction as the rotation direction of the first gear and to be able to swing. A second elastic friction member that is concentric with the two gears and that rotates integrally with the first gear, and is detachable from the first elastic friction member; and the second elastic friction member is attached to the first elastic friction member. And a separation / contact control means for controlling the separation / contact.

According to a second aspect of the present invention, a rotary gear to which the driving force of the driving source is transmitted is provided so as to be rotatable integrally with the rotary, and both the first and second gears are idler gears. It is characterized in that it is always connected in rotation.
Further, the invention of claim 3 is such that the driving force of the driving source is transmitted to the rotary via a gear power transmission mechanism, and the first gear is a gear of the gear power transmission mechanism. It is characterized by that.
Furthermore, the invention according to claim 4 is characterized in that the separation / contact control means includes a solenoid that separates the second elastic friction member from the first elastic friction member when the solenoid is on, and the second elastic friction member when the solenoid is off. It is characterized by comprising an urging spring abutting against the first elastic friction member.

  According to the image forming apparatus of the present invention configured as described above, the rotary state of the rotary is set to the pressure contact of the second elastic friction member to the first elastic friction member and the first of the second elastic friction member, respectively. Since it is set by the separation from the elastic friction member, the rotary can be positioned and locked easily.

  In this case, since the rotation directions of the first and second elastic friction members are set to be the same, the tangential movement of the first elastic friction member and the second direction are pressed at the press contact portions of the first and second elastic friction members. Since the movement of the elastic friction member in the tangential direction is opposite to each other, the first elastic force that rotates the friction material between the first and second elastic friction members, such as a general friction brake, that does not rotate. This is much larger than when it is simply pressed against the friction member. Therefore, a large locking force can be obtained and the rotary lock can be ensured. Thereby, the stop position accuracy of the rotary can be improved.

Furthermore, since only the second elastic friction member is brought into pressure contact with the first elastic friction member, the impact when the rotary positioning is stopped can be reduced, so that the collision noise due to the impact can be reduced. In particular, since the two members engaged with each other are elastic friction members, the collision noise can be reduced more effectively.
As a result, with the recent increase in image formation speed, there has been a great impact on the demand for faster rotary switching speed and the demand for faster switching between the rotary lock position and unlock position. And it can respond flexibly without generating a loud collision sound.

  Furthermore, since the second elastic friction member is simply brought into contact with the first elastic friction member and is merely separated from the first elastic friction member, the remaining amount of toner in each developing device and some developments When the rotary is unlocked when the rotary is twisted due to the unbalanced load of the rotary caused by the non-mounting of the container in the rotary or the moment generated in the rotary due to the development drive reaction force during development, etc. There is no increase in surface friction between the friction member and the second elastic friction member in the direction in which the second elastic friction member is separated from the first elastic friction member, and the second elastic friction member is connected to the first elastic friction member. The force for releasing the engagement can be reduced, and the driving stability of the rotary can be ensured.

  Moreover, since the rotary stop position accuracy can be made high, adjustment for ensuring the stop position accuracy can be eliminated. Accordingly, since adjustment for ensuring the stop position accuracy of the rotary can be eliminated, the accuracy of each component such as the lock means and the rotary can be reduced to a very high level.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows an example of an embodiment of an image forming apparatus according to the present invention, and FIG. 2 schematically shows a rotary developing device used in the image forming apparatus of this example.

  As shown in FIG. 1, the image forming apparatus 1 of this example is generally exposed by an exposure device 2, a rotary developing device 3, and an exposure device 2 to form an electrostatic latent image and this electrostatic image. The latent image is developed with the toner from the rotary developing device 3 to form a visible toner image, the photosensitive member 4, the intermediate transfer medium 5 including an endless transfer belt, and the toner image on the photosensitive member 4. Primary transfer device 6 for primary transfer to the intermediate transfer medium 5, and secondary transfer for secondary transfer of the toner image primarily transferred onto the intermediate transfer medium 5 to a recording medium 7 such as paper (hereinafter, paper will be described as an example). The transfer device 8, the paper 7 accommodated in the paper feed cassette 9 is fed to the secondary transfer device 8 by the paper feed roller 10 a, and the fixing unit 11 is used to fix the toner image secondarily transferred to the paper 7. And a predetermined image fixed by the fixing unit 11. There has been from the sheet discharge tray 12 for accommodating the paper 7 which is formed.

  As shown in FIG. 2, the rotary developing device 3 includes a rotary 13 having a rotary frame 13a rotatably provided, and yellow (Y) and magenta (mounted on the rotary 13 and configured by a developing cartridge. M), cyan (C), and black (K) developing devices 14, 15, 16, and 17.

  In FIG. 2, the developing devices 14, 15, 16, and 17 are disposed in the circumferential direction of the rotary 13 in the clockwise direction and at equal intervals in this order, respectively, and developing rollers 14a, 15a, 16a, and 17a, The developing roller drive gears 14b, 15b, 16b, and 17b provided coaxially with each of the developing rollers 14a, 15a, 16a, and 17a and integrally rotatable therewith, and the driving force of a developing device driving motor (not shown) are input. And the developing roller driving gears 14b, 15b, 16b, 17b corresponding to the driving forces of the developing device driving motors input to the input gears 14c, 15c, 16c, 17c, and the input gears 14c, 15c, 16c, 17c, respectively. Are provided with gear power transmission mechanisms 14d, 15d, 16d, and 17d. Although not shown, each of the developing devices 14, 15, 16, and 17 includes a toner storage unit and a toner supply unit that supplies the toner stored in the toner storage unit to the developing rollers 14a, 15a, 16a, and 17a, as in the related art. Needless to say, a toner regulating means for regulating a thin layer of toner on the developing rollers 14a, 15a, 16a, and 17a conveyed to the photosensitive member 4 is provided.

  Further, the driving force from the developing device driving motor is transmitted close to the outer periphery of the rotary 13 on one end side in the axial direction of the rotary 13 (direction orthogonal to the drawings of FIGS. 1 and 2), and this driving force is transmitted. A developing drive output gear 18 that can be selectively engaged with one of the input gears 14c, 15c, 16c, and 17c and transmitted is provided rotatably. The developing drive output gear 18 is connected to a developing device drive driving motor (not shown) through a gear power transmission mechanism (not shown), and the driving force of the developing device drive driving motor is decelerated by the gear power transmission mechanism and developed. It is transmitted to the output gear.

  Further, the development drive output gear 18 has a built-in one-way clutch. When the rotary 13 described later is driven, the one-way clutch corresponds to the rotation direction of the rotary 13 even if one of the development drive output gear 18 and the development drive input gears 14c, 15c, 16c, and 17c is engaged. Due to idling in the rotation direction, no driving force is transmitted to the development drive input gears 14c, 15c, 16c, and 17c. Further, when any one of the developing devices 14, 15, 16, and 17 is selectively driven (that is, when the developing operation is performed), the one-way clutch is locked (connected) with respect to the rotation direction corresponding to the developing direction. Thus, the driving force is transmitted to the selected development drive input gear of the development drive input gears 14c, 15c, 16c, and 17c.

Further, a rotary gear 19 is provided on one end side of the rotary 13 in the same axial direction so as to be coaxial with the rotary 13 and rotatable integrally therewith, and meshes with the rotary gear 19 and is shown in FIG. A rotary drive output gear 20 to which the drive force from the drive motor 30 is transmitted is rotatably provided. The rotary drive output gear 20 is connected to a rotary drive motor 30 via a gear power transmission mechanism (not shown). The driving force of the rotary drive motor 30 is decelerated by the gear power transmission mechanism and transmitted to the rotary drive output gear 20.
Note that the developing device drive motor and the rotary drive motor described above can be configured by a single common drive motor.

  The rotary type developing device 3 configured as described above is configured such that each of the developing units 14, 15, 16, and 17 is driven by rotating the rotary 13 by 90 degrees counterclockwise as indicated by arrows in FIG. The electrostatic latent image on the photoconductor 4 is sequentially developed into a toner image for each color.

  By the way, when each developing device 14, 15, 16, 17 is set to the developing position and performs the developing operation, the rotary 13 is stopped at the developing position, that is, positioned at the locking position and held at the locking position. Must. Further, it is necessary to position the rotary 13 at a predetermined lock position at a position other than the development position and hold it at the lock position.

  Therefore, in the image forming apparatus 1 of this example, as shown in FIG. 3, a lock unit 21 that positions the rotary 13 at a predetermined lock position and holds it at the lock position is provided on one end side in the axial direction of the rotary 13. ing. The lock unit 21 includes a fixed bracket 22 fixed to the main body of the image forming apparatus, an idle gear 23 that is rotatably supported by the fixed bracket 22 by a rotation shaft 23 a and that is always meshed with the rotary gear 19, and the fixed bracket 22. The first lock operating gear 24b (corresponding to the first gear of the present invention) 24b and the first lock operating gear 24b that are rotatably supported by the rotating shaft 24a and supported at a fixed mounting position and are always meshed with the idle gear 23. A first lock actuating mechanism 24 having a first elastic friction member 24c concentrically and integrally rotated, a swing bracket 25 provided so as to be swingable about a rotation shaft 23a of the idle gear 23, and A second lock operating gear (which is rotatably supported by the rotary shaft 26a on the swing bracket 25 and is always meshed with the idle gear 23). 26b and a second elastic friction member 26c that is concentrically and integrally rotated with the second lock operating gear 26b and that is detachably attached to the first elastic friction member 24c. In a direction in which the second elastic friction member 26c comes into contact with the first elastic friction member 24c (ie, counterclockwise in FIG. 3) which is contracted between the second lock operating mechanism 26, the fixed bracket 22 and the swing bracket 25. An urging spring 27 for urging the oscillating bracket 25, a lever 28 for rotating the oscillating bracket 25 rotatably provided on the image forming apparatus main body, and a solenoid 29 for operating the lever 28 are provided. Yes.

In FIG. 3, reference numeral 30 denotes a rotary drive motor composed of, for example, a stepping motor that is a drive source of the rotary 13. The drive force of the rotary drive motor 30 is applied to the rotary drive output gear 20 via a gear power transmission mechanism (not shown). When the rotary drive output gear 20 is transmitted and rotates, the rotary 13 is driven to rotate.
In the image forming apparatus 1 of this example, both the first and second lock operating gears 24 b and 26 b are always connected to the rotary gear 19 via the idler gear 23 and are connected to the rotary 13 in conjunction with the rotation. And rotate in the same direction.

In the lock means 21, when the solenoid 29 is turned on (excited) as shown in FIG. 3, the solenoid 29 rotates the lever 28 counterclockwise by the exciting force. Then, the swing bracket 25 rotates clockwise around the rotation shaft 23a against the urging force of the urging spring 27 by the rotational force of the lever 28, so that the second elastic friction member 26c has the first elasticity. The locking means 21 is in the unlocked position, being separated from the friction member 24c in the radial direction of the first elastic friction member 24c. At this time, since the second elastic friction member 26c and the second lock operation gear 26b rotate clockwise around the rotation shaft 23a of the idle gear 23, the engagement between the second lock operation gear 26b and the idle gear 23 is Maintained.
As a result, the first and second lock operating gears 24b and 26b are both free, and the idle gear 23 is also free to rotate. Accordingly, the rotary 13 can rotate and the rotary 13 is unlocked.

  As shown in FIG. 4, when the solenoid 29 is turned off (non-excited), the solenoid 29 does not act on the lever 28. Then, the swing bracket 25 is rotated counterclockwise around the rotation shaft 23a by the urging force of the urging spring 27, so that the second elastic friction member 26c is moved to the first elastic friction member 24c. Abutting in the radial direction of the member 24c, the locking means 21 is in the locked position. At this time, since the second elastic friction member 26c and the second lock operating gear 26b rotate counterclockwise around the rotation shaft 23a of the idle gear 23, the engagement between the second lock operating gear 26b and the idle gear 23 is achieved. Is maintained. For example, when the rotary 13 tries to rotate counterclockwise, the idle gear 23 tries to rotate clockwise, and the first and second lock operating gears 24b and 26b both try to rotate counterclockwise. . However, since the second elastic friction member 26c is in pressure contact with the first elastic friction member 24c by the urging force of the urging spring 27, the first and second elastic friction members 24c and 26c are caused by the friction force between the first and second elastic friction members 24c and 26c. Both the two-lock operating gears 24b and 26b are not rotatable. For this reason, since both the first and second lock operating gears 24b and 26b do not rotate, the idle gear 23 also cannot rotate. Accordingly, the rotary 13 cannot be rotated, and the rotary 13 is locked.

At this time, in the pressure contact portions of the first and second elastic friction members 24c and 26c, the tangential movement of the first elastic friction member 24c and the tangential movement of the second elastic friction member 26c are opposite to each other (counter The frictional force between the first and second elastic friction members 24c and 26c is the second friction material that does not attempt to rotate, such as a general friction brake. This is much larger than the case where the elastic friction member 26c is simply pressed. Therefore, a large locking force is obtained, and the rotary 13 is locked securely.
Further, since the stop position error of the rotary 13 is within the displacement angle due to the backlash of the gear of the gear power transmission mechanism, the concavo-convex member in the concavo-convex fitting method of the lever as disclosed in the aforementioned Patent Documents 1 and 2 Therefore, the stop position of the rotary 13 can be set with high accuracy without requiring high accuracy and assembly adjustment of parts.

Further, since the locking function by the locking means 21 is reversible, the rotary 13 is conversely rotated clockwise in the locking position of the locking means 21 where the first and second elastic friction members 24c and 26c are pressed against each other. In this case, the rotary 13 cannot rotate and the rotary 13 is locked. Therefore, when the locking means 21 is in the locked position, for example, the uneven load of the rotary 13 caused by, for example, an imbalance of the remaining amount of toner in the four developing units or the non-mounting of some developing units into the rotary 13 or the like. A moment is generated in the rotary 13 due to a developing driving reaction force at the time of development, and even if the rotary 13 tries to rotate forward (counterclockwise; that is, the rotation direction during the developing operation) or reverse, it is reliably held in a locked state. .
In this way, the solenoid 29 and the biasing spring 27 constitute the separation / contact control means of the present invention that controls the separation of the first and second elastic friction members.

Next, the operation of positioning the rotary 13 to the lock position corresponding to the development position by the lock means 21 in order to switch the developing devices 14, 15, 16, and 17 to be set at the development positions will be described.
Now, as shown in FIGS. 1 and 2, it is assumed that the yellow (Y) developing device 14 is set to the developing position and the rotary 13 is set to the locked state shown in FIG. When the development of the yellow (Y) by the developing device 14 is completed, first, the rotary drive motor 30 is driven, and then the solenoid 29 is turned on as shown in FIG. 3 to turn the second elastic friction member 26c into the first elastic friction member 24c. The rotary 13 is unlocked at a distance from

  Then, the rotary 13 is driven to rotate counterclockwise by the driving force of the rotary drive motor 30. At this time, since both the first and second lock operating gears 24 b and 26 b meshed with the idle gear 23 are free to rotate, the idle gear 23 can also freely rotate. Since both the idle gear 23 and the first and second lock operating gears 24b and 26b rotate idly, the rotary 13 is affected by the idle gear 23, the first and second lock operating gears 24b and 26b. It rotates smoothly.

When the rotary drive motor 30 rotates 90 degrees to the locked position, the control device turns off the solenoid 29 and presses the second elastic friction member 26c against the first elastic friction member 24c by the urging force of the urging spring 27. After a sufficient time has elapsed for the second elastic friction member 26c to fully contact the first elastic friction member 24c, the control device stops the rotary drive motor 30. As a result, the rotary 13 stops at the locked position and the locked state is maintained. At the lock position of the rotary 13, the next magenta (M) developing device 15 is set to the developing position. Similarly, the locked state and the unlocked state of the rotary 13 are set and the rotational drive of the rotary 13 is controlled, so that the cyan (C) developing unit 16 and the black (K) developing unit 17 are sequentially developed. Set to position.
The setting of the lock position of the rotary 13 by the lock means 21 is not limited to the developing position of the developing machine, but can be performed when the rotary 13 is locked at a desired predetermined position.

  According to the image forming apparatus 1 of this example, the locked state and the unlocked state of the rotary 13 of the rotary developing device 3 are respectively set to the pressure contact of the second elastic friction member 26c to the first elastic friction member 24c and the second elastic friction member. Since the member 26c is set by being separated from the first elastic friction member 24c, the rotary 13 can be positioned and locked easily.

  At this time, since the rotation directions of the first and second elastic friction members 24c and 26c are set to be the same, the first elastic friction member 24c of the first and second elastic friction members 24c and 26c is contacted with the first elastic friction member 24c. Since the movement in the tangential direction and the movement in the tangential direction of the second elastic friction member 26c are opposite to each other (counter direction), the frictional force between the first and second elastic friction members 24c and 26c is, for example, general The friction material that does not rotate, such as a typical friction brake, is much larger than when it is simply pressed against the first elastic friction member 24c. Therefore, a large locking force can be obtained, and the lock of the rotary 13 can be ensured. Thereby, the stop position accuracy of the rotary 13 can be improved.

Furthermore, since only the second elastic friction member 26c is pressed against the first elastic friction member 24c, the impact at the time of stopping the positioning of the rotary 13 can be reduced. Can be realized. In particular, since the two members engaged with each other are elastic friction members, the collision noise can be reduced more effectively.
As a result, with the recent increase in the image forming speed 1, there is also a demand for an increase in the switching rotational speed of the rotary 13 and a request for an expeditious switching operation between the lock position and the unlock position of the rotary 13. It is possible to respond flexibly without generating a large impact and a large collision sound.

  Further, the second elastic friction member 26c is brought into contact with the first elastic friction member 24c in the radial direction of the first elastic friction member 24c, and from the first elastic friction member 24c to the radial direction of the first elastic friction member 24c. Since they are separated from each other, the unbalanced amount of toner in each of the developing units 14, 15, 16, and 17 and the unbalanced load of the rotary 13 caused by some of the developing units not being installed in the rotary 13 or during development When the rotary 13 is unlocked in a state in which the rotary is twisted by a moment generated in the rotary 13 by the development driving reaction force or the like, the second elastic friction member 26c is interposed between the first elastic friction member 24c and the second elastic friction member 26c. The surface friction in the direction in which the elastic friction member 26c is separated from the first elastic friction member 24c does not increase, and the second elastic friction member 26c is released from the engagement with the first elastic friction member 24c. Forces can be reduced, it is possible to ensure the driving stability of the rotary 13.

  Moreover, since the stop position accuracy of the rotary 13 can be made high, adjustment for ensuring this stop position accuracy can be made unnecessary. Therefore, the accuracy of each component such as the lock means 21 and the rotary 13 can be reduced without being so high.

  FIG. 5 shows another example of the embodiment of the present invention, and is a view similar to FIG. 3 showing the unlocked state of the rotary. FIG. 6 is a view similar to FIG. 4 showing the locked state of the rotary in this example. It is. Note that the same components as those in the above example are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example shown in FIG. 3 and FIG. 4 described above, dedicated parts for the idle gear 23 and the first lock gear 24b of the first lock actuating mechanism 24 are used for the lock means 21, but these are shown in FIG. 5 and FIG. Thus, in the image forming apparatus 1 of this example, the existing rotary drive output gear 20 is used instead of the idle gear 23, and the first lock gear of the first lock operating mechanism 31 is used instead of the first lock gear 24b. As an example, an existing motor pinion 31 b that is a gear of a gear power transmission mechanism between the rotary drive motor 30 and the rotary drive output gear 20 and always meshes with the rotary drive output gear 20 is used. In the case of this example, the rotary drive output gear 20 is rotatably provided on the fixed bracket 22 by the rotary shaft 20a, and the motor pinion 31b is rotatably provided by the rotary shaft 31a.

The first lock operating mechanism 31 includes a first elastic friction member 31c that is concentric with and integrally rotates with the motor pinion 31b. Further, a swing bracket 25 that rotatably supports the second lock gear 26b of the second lock operating mechanism 26 is supported rotatably about the rotation shaft 20a of the rotary drive output gear 20, and the second lock The gear 26 b is always meshed with the rotary drive output gear 20.
The first elastic friction member 31c of the first lock operating mechanism 31 and the second elastic friction member 26c of the second lock operating mechanism 26 of this example are the same as the first elastic friction member 24c and the second elastic friction member 26c of the above-described example. The same action is performed.

According to the image forming apparatus 1 of this example, the existing rotary drive output gear 20 and the motor pinion 31b are used without using dedicated parts such as the idle gear 23 and the first lock gear 24b of the above example. Therefore, the number of parts can be reduced, and the rotary developing device 3 can be formed in a compact and inexpensive manner.
Other configurations, other operations, and other effects of the image forming apparatus 1 of this example are the same as those of the above-described example.

  In each of the above-described examples, both the first and second lock gears 24b and 26b are not directly meshed with the rotary drive gear 19, but both the first and second lock gears 24b and 26b are both rotary drive gears. It can also be made to mesh directly with 19. In this case, the swing bracket 25 may be swingably provided on the rotary shaft (not shown) of the rotary 13.

  Further, in the above-described examples, the idle gear 23 or the rotary drive output gear 20 that is always meshed with the rotary drive gear 19 and the first lock gear 24b or the motor pinion 31b as the first lock gear that meshes with each other are respectively provided. For example, a motor pinion 31b that always meshes with the rotary drive output gear 20 as an idle gear, and another motor pinion that always meshes with the motor pinion 31b as a first lock gear. Only the gears of the mechanism can be used.

  The image forming apparatus of the present invention includes a developing device of a rotary developing system that performs multicolor development of two or more colors such as full color by a plurality of developing devices mounted on a rotary, and a plurality of developing devices for a latent image carrier. Suitable for use in image forming apparatuses such as electrostatic copying machines and printers equipped with locking means for positioning and locking the rotary at a predetermined position so as to selectively set the developer carrier of the developing unit to the developing position. can do.

1 is a diagram schematically showing an example of an embodiment of an image forming apparatus of the present invention. It is a figure which shows typically the rotary type developing device used for the image forming apparatus of this example. It is a figure which shows the lock release state of the rotary in the image forming apparatus of this example. It is a figure which shows the lock state of the rotary in the image forming apparatus of this example. It is the same figure as FIG. 3 which shows the other example of embodiment of this invention, and shows the lock release state of a rotary. FIG. 5 is a view similar to FIG. 4 showing a rotary locked state in the image forming apparatus of this example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Exposure apparatus, 3 ... Rotary type developing device, 4 ... Photoconductor, 5 ... Intermediate transfer medium, 6 ... Primary transfer apparatus, 7 ... Recording medium, 8 ... Secondary transfer apparatus, 10 ... Feed Paper device, 11: fixing unit, 13: rotary, 14, 15, 16, 17 ... yellow (Y), magenta (M), cyan (C), and black (K) developers, 19: rotary gear, DESCRIPTION OF SYMBOLS 20 ... Rotary drive output gear, 21 ... Locking means, 22 ... Fixed bracket, 23a ... Rotating shaft, 23 ... Idle gear, 24, 31 ... First lock operation mechanism, 24b, 31b ... First lock operation gear, 24c, 31c DESCRIPTION OF SYMBOLS 1st elastic friction member, 25 ... Swing bracket, 26 ... 2nd lock operation mechanism, 26b ... 2nd lock operation gear, 26c ... 2nd elastic friction member, 27 ... Energizing spring, 28 ... Lever, 29 ... Solenoid 30 ... Rotary drive motor 31 ... first locking actuation mechanism, 31b ... motor pinion, 31c ... first elastic friction member

Claims (4)

A rotary provided rotatably and mounted with a plurality of developing devices, a drive source for rotationally driving the rotary, and positioning the rotary to selectively set the developing device at a predetermined position. Locking means for locking, and by positioning the rotary by the locking means, one of the plurality of developing devices is selectively set at a developing position facing the image carrier, and the developing position is set at the developing position. In the image forming apparatus configured to develop the latent image on the image carrier with a set developer,
The lock means rotates in conjunction with the rotation of the rotary on the image forming apparatus main body and is fixedly attached to the first gear, and rotates concentrically and integrally with the first gear. A first elastic friction member, and a second gear provided on the image forming apparatus main body so as to rotate in the same rotation direction as the rotation direction of the first gear and to be able to swing in association with the rotation of the rotary. A second elastic friction member that is concentric with and integrally with the second gear and is detachable from the first elastic friction member; and the second elastic friction member is connected to the first elastic friction member. An image forming apparatus comprising: a contact / separation control unit that controls contact / separation with respect to the image. A rotary gear to which the driving force of the drive source is transmitted is provided so as to be rotatable integrally with the rotary, and both the first and second gears are always connected to the rotary gear via an idler gear. The image forming apparatus according to claim 1. The driving force of the driving source is transmitted to the rotary via a gear power transmission mechanism, and the first gear is a gear of the gear power transmission mechanism. 2. The image forming apparatus according to 2. The separation / contact control means contacts the first elastic friction member with a solenoid that separates the second elastic friction member from the first elastic friction member when the solenoid is turned off, and the solenoid when the solenoid is turned off. 4. The image forming apparatus according to claim 1, further comprising an urging spring.

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