JP2007187786A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the deterioration in a developing device to the minimum by driving the developing device in start/finish timing of each developing device in an image forming apparatus equipped with a plurality of developing devices. <P>SOLUTION: The plurality of developing devices 2 are respectively equipped with: motive power transmitting means 4 to transmit motive power for driving the developing device 2; and with driving sources 5. The motive power transmitting means 4 has a clutch 6 for changing posture between motive power transmitting posture to transmit the motive power and motive power detaching posture to detach the motive power from the developing device 2. The posture of each clutch 6 is changed from the motive power detaching posture to the motive power transmitting posture at different time when paper 23 to be conveyed reaches the developing device 2. Then, the image by each developing device 2 is transferred and formed on the paper 23. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tandem development type image forming apparatus having a plurality of developing devices.

  2. Description of the Related Art As a tandem development type image forming apparatus including a plurality of developing devices, a device including a driving source that drives the developing device and a power transmission unit that transmits power to each developing device is generally known.

For example, Japanese Patent Laid-Open No. 2005-228867 discloses that the driving of the developing device is stopped and the developing device is separated from the photosensitive member, and the developing device is driven and the developing device is in contact with the photosensitive member. A technique of a color image forming apparatus configured to change the attitude of a color developer is disclosed.
JP 2003-122089 A

However, the technique of the color image forming apparatus disclosed in Patent Document 1 described above has a problem in that drive transmission / dissociation operations of a plurality of developing devices are performed at the same timing. In other words, multiple development devices arranged at each tandem interval differ in development start / end timing by the tandem time interval determined by the tandem interval and the printing speed. There was a problem that it was driven excessively over a long time.

  As described above, when the developing device is driven excessively beyond the time necessary for the development, the developer is subjected to mechanical stress due to the stirring of the developing device or is heated by heat due to friction during stirring. This caused the problem that the developing device deteriorated quickly.

The present invention has been made in view of the above-described problems. By driving each developing device in accordance with the start / end timing of each developing device, it is possible to minimize the deterioration of the developing device. It is an object to provide a forming apparatus.

  In order to solve the above problems, the present invention provides a tandem development type image forming apparatus including a plurality of developing devices, and each of the plurality of developing devices includes power transmission means for transmitting power for driving the developing device. Each of the power transmission means of the developing device includes a clutch capable of changing a posture between a power transmission posture for transmitting the power from the driving source to the developing device and a power separating posture for separating the power of the driving source from the developing device. The clutches of the respective power transmission means are changed in posture from the power separation posture to the power transmission posture at different times corresponding to the time when the conveyed paper reaches the developing device. An image forming apparatus characterized in that an image developed by a developing device is transferred and formed on a sheet.

According to the present invention, the clutch of each power transmission means of the developing device is between a power transmission posture for transmitting power from the driving source to the developing device and a power separation posture for separating the power of the driving source from the developing device. The posture can be changed. The developing devices are changed in posture from the power separating posture to the power transmitting posture at different times corresponding to the time when the conveyed paper reaches the developing device. The developed image is transferred and formed on the paper, so that the developing device is driven only when necessary, while the rotation of the developing device does not need to be continued when unnecessary, thereby preventing deterioration of the developing device. Will be able to.

  Further, since the drive source itself continues to rotate without being started or stopped, the transmitted power becomes uniform and stable, so that the development device is also driven stably.

  Here, the image forming apparatus includes a plurality of eccentric cams provided so as to have different rotation angle phases corresponding to the respective clutches of the power transmission unit, and a cam drive motor that rotates the plurality of eccentric cams. Each of the plurality of eccentric cams, and a plurality of clutch operation levers that are displaced by being pushed by the tops of the eccentric cams. The clutch operation levers are different from each other when the sheet reaches the developing device. It is preferable that, in time, the clutch is pushed and displaced by the top of the eccentric cam to change the posture of each clutch from the power separation posture to the power transmission posture.

  In this way, at different times when the paper reaches the developing device, the clutch operating levers are displaced by being pushed by the tops of the eccentric cams having different rotation angle phases corresponding to the clutches. Since the posture is changed from the power separation posture to the power transmission posture, it is possible to realize an image forming apparatus capable of changing the posture of each clutch from the power separation posture to the power transmission posture with a simple configuration.

  Each of the clutches of the power transmission means includes a clutch operation member that can swing around a drive shaft of a drive source, a rotation shaft provided on the clutch operation member, and a drive provided on the drive shaft of the drive source. An idle gear that is rotationally driven by the gear, and an output gear that transmits power to the developing device, and each of the clutch operating members is in contact with the clutch operating lever that is displaced by being pushed by the top of the eccentric cam. The idle gear is coupled to the output gear and is output from the drive gear when the clutch operation member is pushed by the plurality of clutch operation levers and swings through these operation ends. It must be provided so that the posture can be changed between a combined posture that can transmit power to the gear and a retracted posture that retracts from the output gear and separates the power from the drive gear and the output gear. Preferred.

  In this way, the clutch operating lever pushes and swings the clutch operating member via the operating end, so that power can be transmitted from the drive gear to the output gear, and the power from the drive gear and the output gear. Since the posture can be changed between the retracted posture and the retracted posture, the clutch capable of changing the posture from the power separation posture to the power transmission posture with a simple configuration can be realized.

  As described above, according to the present invention, at different times when the conveyed paper reaches the developing device, the clutch of each power transmission means changes the posture from the power separation posture to the power transmission posture, and the image is changed. Since the toner image is transferred and formed on the paper, the developing device can be driven only when necessary, and the rotation of the developing device does not have to be continued when unnecessary. As a result, deterioration of the developing device can be prevented. There is a remarkable effect.

  In addition, since the drive source itself continues to rotate without being started or stopped, the transmitted power becomes uniform and stable. As a result, the driving of the developing device is also stabilized. .

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG.
FIG. 2 is an explanatory view showing the configuration of the image forming apparatus 1 according to the embodiment of the present invention, and FIG. 2 is a conceptual view of the developing device 2 of the image forming apparatus 1 as viewed from the side. FIG. 3 is a side view showing the configuration of the power transmission means 4, the eccentric cam 7, the cam drive motor 8, and the clutch operation lever 9 of the image forming apparatus 1. 4 and 5 are side views showing the configuration of the power transmission means 4 and the drive source 5 of the image forming apparatus 1. FIG. 4 shows a state where the clutch 6 of the power transmission means 4 is in the power transmission posture. FIG. 5 shows a state in which the clutch 6 of the power transmission means 4 is in a power separation posture. FIG. 6 is a perspective view showing the configuration of the eccentric cam 7. FIGS. 6A and 6B are views of the eccentric cam 7 viewed from different angles.

  Referring to FIG. 1, the illustrated image forming apparatus 1 according to the embodiment of the present invention is a tandem developing type color image forming apparatus having a plurality of developing devices 2, and is included in the image forming apparatus main body 1a. The image forming apparatus includes four developing devices 2, a photoconductor 21 made of an OPC photoconductor or an a-Si photoconductor, and capable of holding an electrostatic latent image by being charged, and an exposure unit 22.

  The image forming apparatus 1 also includes a paper feed cassette 24 that accommodates a paper 23 that is a recording medium, a transport belt 25 that transports the paper 23, a developer container 26, and a charger for charging the photoreceptor 21. 22, a transfer device 28 for transferring the toner image on the photosensitive member 21 to a recording medium by a transfer bias, and a fixing device 29 for fixing the transferred toner image on the paper 23 onto which the toner images of the respective colors are sequentially transferred. It has.

  The image forming apparatus 1 sequentially transfers the toner images of the respective colors onto the paper 23 via the developing device 2, the photosensitive member 21, and the exposure unit 27, and the toner image is fixed by the fixing device 29. The paper is discharged.

  Here, the developing device 2 is a device configured to form an image on the surface of the photosensitive member 2 by stirring the developer 3 and supplying it to the photosensitive member 2, as shown in FIG. In a housing 31 configured to accommodate the developer 3, an agitation paddle 32 for agitating the developer 3, an agitation mixer 33 for agitating and mixing the developer 3 in the agitation paddle 32, and the agitation paddle 32 are adjacent to each other. And a developing roller 35 for supplying the developer 3 to the photosensitive member.

  As shown in FIGS. 3 and 4, the developing device 2 includes a power transmission unit 4 that transmits power for driving the plurality of development devices 2, and a drive source 5 that supplies power to the power transmission unit 4. (FIG. 4).

  The power transmission means 4 has a power transmission posture (FIG. 4) for transmitting power from the driving source 5 to the developing device 2 and a power separation posture (FIG. 5) for separating the power of the driving source 5 from the developing device 2. It has a clutch 6 that can change its posture.

  In addition, the image forming apparatus 1 includes a plurality of eccentric cams 7, a cam drive motor 8, and a plurality of clutch operation levers 9.

  The developer 3 is a developer called a so-called two-component developer containing a toner and a magnetic carrier. In this embodiment, the magnetic carrier is 106 Ωcm to 109 Ωcm, the saturation magnetization is 70 emu / g, the average A ferrite carrier having a particle size of 35 μm is employed. Further, the mixing ratio of the toner and the carrier of the developer 3 is about 2 to 40% by weight of the toner with respect to the total amount of the toner and the carrier.

The drive source 5 supplies power to the power transmission means 4, and one electric motor is employed for each power transmission means 4 in this embodiment. As shown in FIG. 4, the drive source 5 is fixed to motor bases 5 a provided in the power transmission means 4.

  Each of the clutches 6 is provided with a clutch operating member 6 a that can swing around the drive shaft 5 b of the drive source 5, a rotation shaft provided on the clutch operation member 6 a, and a drive shaft 5 b of the drive source 5. An idle gear 6c that is rotationally driven by the drive gear 6b and an output gear 6d that transmits power to the developing device 2 are provided, and at different times corresponding to the time when the conveyed paper 23 reaches the developing device 2, The posture of the clutch 6 of each power transmission means 4 is changed from the power separation posture (FIG. 5) to the power transmission posture (FIG. 4). As a result, the image developed on the photoreceptor 2 by each developing device 2 is transferred and formed on the paper 23.

  Here, each clutch operation member 6a has an operation end 6e that can be brought into contact with the clutch operation lever 9 that is pushed and displaced by the top of the eccentric cam 7, and the clutch operation member 6a is interposed via these operation ends 6e. Is pushed by the plurality of clutch operation levers 9 and swings, so that the idle gear 6c is coupled to the output gear 6d and can transmit power from the drive gear 6b to the output gear 6d (FIG. 4); The posture can be changed between a retracted posture (FIG. 5) for retracting from the output gear 6d and separating the power from the drive gear 6b and the output gear 6d.

  The plurality of eccentric cams 7 are provided so as to have different rotation angle phases corresponding to the respective clutches 6 of the power transmission means 4. In the present embodiment, the eccentric cams 7 are integrally formed as one member. Yes.

  The cam drive motor 8 rotates a plurality of eccentric cams 7 integrally formed as one member via gears 8a and 8b (FIG. 3), and a stepping motor so that the rotation angle can be adjusted. Is adopted.

  The plurality of clutch operation levers 9 (FIG. 3) are rod-shaped members that are provided corresponding to the plurality of eccentric cams 7 and are displaced by being pushed by the tops of the eccentric cams 7. These clutch operating levers 9 are normally urged in the direction of the eccentric cam 7 by an urging means (not shown), and the clutch 6 is in a power separating posture (FIG. 5). Corresponding to the time when the paper 23 arrives at the developing device 2, the clutch 23 is pushed and displaced by the top of the eccentric cam 7 at different times, and the power is transmitted from the power separating posture (FIG. 5). The posture is changed to the posture (FIG. 4).

  Next, the operation of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to FIGS. 3 to 6 and FIGS.

  In the image forming apparatus 1 according to the embodiment of the present invention, as shown in FIG. 3, the clutch operation lever 9 is normally urged in the direction of the eccentric cam 7 by an urging means (not shown). 6 is in a power separation posture (FIG. 5).

  Then, the cam drive motor 8 rotates the plurality of eccentric cams 7, and a plurality of clutch operation levers 9 provided corresponding to each of the plurality of eccentric cams 7 are pushed by the tops of the eccentric cams 7, and are not shown. Displaces against the biasing force of the biasing means.

  At this time, the clutch operating lever 9 is displaced by being pushed by the top of the eccentric cam 7 at different times just before the paper 23 reaches the developing device 2 corresponding to the time when the paper 23 reaches the developing device 2. Then, the posture of each clutch 6 is changed from the power separation posture (FIG. 5) to the power transmission posture (FIG. 4).

That is, the operation end 6e of the clutch operation member 6a contacts the clutch operation lever 9 that is displaced by being pushed by the top of the eccentric cam 7, and the clutch operation member 6a of the clutch 6 is respectively connected to the drive shaft 5b of the drive source 5. Swing around.

  In this way, the clutch operating member 6a is pushed by the plurality of clutch operating levers 9 via the operating end 6e and swings, so that the idle gear 6c is coupled to the output gear 6d and is connected to the output gear from the drive gear 6b. The posture is changed between a combined posture capable of transmitting power to 6d and a retracted posture that retracts from the output gear 6d and separates the power from the drive gear 6b and the output gear 6d.

  In this way, the posture of the clutch 6 of each power transmission means 4 is changed from the power separation posture to the power transmission posture at different times corresponding to the time when the conveyed paper 23 reaches the developing device 2. As a result, the image developed on the photosensitive member 2 by each developing device 2 is transferred and formed on the paper 23, and the operation of each power transmission means 4 is as shown in FIGS.

  That is, FIG. 7 shows a state where all the three developing devices 2 are in the power separation posture with the rotation angle of the eccentric cam being 0 °.

  Next, FIG. 8 shows a state in which the left developing device 2 is in the power transmission posture and the other developing devices are in the power separation posture with the rotation angle of the eccentric cam being 45 °.

  FIG. 9 shows a state in which the left and center developing devices 2 are in the power transmission posture and the right developing device is in the power separating posture with the rotation angle of the eccentric cam being 90 °.

  FIG. 10 shows a state where the eccentric cam has a rotational angle of 135 ° and all the three developing devices 2 are in the power transmission posture.

  Further, FIG. 11 shows a state in which all of the three developing devices 2 are in the power transmission posture with the rotation angle of the eccentric cam being 180 °.

  FIG. 12 shows a state in which all of the three developing devices 2 are in the power transmission posture with the rotational angle of the eccentric cam being 225 °.

  FIG. 13 shows a state in which the right and center developing devices 2 are in the power transmission posture and the left developing device is in the power separating posture with the rotation angle of the eccentric cam being 270 °.

  FIG. 14 shows a state in which the right developing device 2 is in the power transmission posture and the left and center developing devices are in the power separating posture with the rotation angle of the eccentric cam being 315 °.

  FIG. 15 shows a state in which all of the three developing devices 2 have returned to the power separation posture with the rotation angle of the eccentric cam being 360 °.

  In this way, the image of each developing device 2 is transferred and formed on the paper 23.

As described above, according to the image forming apparatus 1 according to the embodiment of the present invention, the clutch 6 of each power transmission unit 4 of the developing device 2 transmits power from the drive source 5 to the developing device 2. The posture can be changed between the transmission posture and the power separation posture for separating the power of the driving source 5 from the developing device 2. Then, at different times corresponding to the time when the conveyed paper 23 reaches the developing device 2, the clutch 6 of each power transmission means 4 changes its posture from the power separation posture to the power transmission posture. Since the image developed by the developing device is transferred and formed on the sheet 23, the developing device 2 is driven only when necessary, while the developing device 2 is driven when unnecessary.
Therefore, the developing device 2 can be prevented from deteriorating.

  Further, since the drive source 5 itself continues to rotate without being started or stopped, the transmitted power becomes uniform and stable, so that the driving of the developing device 2 becomes stable.

  Further, according to the image forming apparatus 1, at different times when the paper 23 reaches the developing device 2, the clutch operating lever 9 is pushed by the top of the eccentric cam 7 having a different rotational angle phase corresponding to the clutch 6. Displacement changes the posture of each clutch 6 from the power separation posture to the power transmission posture, so that it is possible to change the posture of each clutch 6 from the power separation posture to the power transmission posture with a simple configuration. The apparatus 1 can be realized.

  Further, when the clutch operating lever 9 pushes and swings the clutch operating member 6a via the operating end 6e, the coupling posture capable of transmitting power from the drive gear 6b to the output gear 6d and the power from the drive gear 6b Since the posture can be changed between the retracted posture for separating the output gear 6d, the clutch 6 capable of changing the posture from the power separating posture to the power transmitting posture can be realized with a simple configuration. It becomes like this.

  The above-described embodiment is merely a preferred specific example of the present invention, and the present invention is not limited to the above-described embodiment.

  For example, the image forming apparatus 1 according to the embodiment of the present invention includes a photoconductor 21, a paper feed cassette 24, a transport belt 25, a developer container 26, a charger 27, a transfer device 28, and a fixing device 29 as shown in FIG. It is not limited to the configuration. Further, the developer 3 is not limited to one using a ferrite carrier having 106 Ωcm to 109 Ωcm, a saturation magnetization of 70 emu / g, and an average particle size of 35 μm. Any image forming apparatus of a tandem development type that employs a developer containing toner and a magnetic carrier can be applied to various image forming apparatuses.

  Further, the developing device 2 is not necessarily limited to the one provided with the developing roller 8. The present invention can also be applied to a system in which the developer 3 is directly supplied from the magnetic roller 7 to the photoreceptor 21.

  In the present embodiment, one drive motor 5 is used for each power transmission unit 4, but one drive source 5 is not necessarily required for each power transmission unit 4. As long as power is supplied to the power transmission means 4, a system in which power is distributed from a common electric motor by a gear or the like is also possible.

  Moreover, the stirring mixer 6 is not necessarily required, and the design of the stirring unit can be changed in various ways.

  The configuration of the clutch 6 is not limited to the configurations of the clutch operation member 6a, the drive gear 6b, the idle gear 6c, and the output gear 6d as shown in the figure. Various clutch mechanisms can be employed as long as the posture can be changed between the power separation posture and the power transmission posture.

  Further, the rotation angle of the eccentric cam is not necessarily limited to the angle shown in FIGS. Changes can be made according to the configuration, specifications, dimensions, etc. of the related apparatus.

  In addition, it goes without saying that various design changes are possible within the scope of the claims of the present invention.

1 is an explanatory diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a conceptual diagram of a developing device of the image forming apparatus viewed from the side. FIG. 3 is a side view showing a configuration of a power transmission unit, an eccentric cam, a cam drive motor, and a clutch operation lever of the image forming apparatus. FIG. 2 is a side view showing the configuration of a power transmission unit and a drive source of the image forming apparatus, and shows a state where a clutch of the power transmission unit is in a power transmission posture. FIG. 3 is a side view showing a configuration of a power transmission unit and a drive source of the image forming apparatus, and shows a state where a clutch of the power transmission unit is in a power separation posture. It is a perspective view which shows the structure of an eccentric cam, (a) and (b) are the figures which looked at the eccentric cam from a different angle, respectively. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 0 degree. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 45 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 90 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 135 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 180 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 225 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 270 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 315 degrees. It is explanatory drawing which shows the state whose rotation angle of an eccentric cam is 360 degrees.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Developing apparatus 4 Power transmission means 5 Drive source 5b Drive shaft 6a Clutch operation member 6b Drive gear 6c Idle gear 6d Output gear 6e Operation end 6 Clutch 7 Eccentric cam 8 Cam drive motor 9 Clutch operation lever 23 Paper

Claims (3)

A tandem development type image forming apparatus including a plurality of developing devices,
Each of the plurality of developing devices includes power transmission means for transmitting power for driving the developing device,
Each power transmission means of the developing device has a clutch whose posture can be changed between a power transmission posture for transmitting power from the driving source to the developing device and a power separation posture for separating the power of the driving source from the developing device. And
Development is performed by each developing device by changing the posture of the power transmission means from the power separating posture to the power transmitting posture at different times corresponding to the time when the conveyed paper reaches the developing device. An image forming apparatus, wherein the formed image is transferred and formed on a sheet. A plurality of eccentric cams provided so as to have different rotation angle phases corresponding to the respective clutches of the power transmission means;
A cam drive motor for rotating the plurality of eccentric cams;
A plurality of clutch operation levers provided corresponding to each of the plurality of eccentric cams and displaced by being pushed by the tops of the eccentric cams;
The clutch operating lever is displaced by being pushed by the top of the eccentric cam at different times when the paper reaches the developing device, and changes the posture of each clutch from the power separating posture to the power transmitting posture. The image forming apparatus according to claim 1. Each of the clutches of the power transmission means includes a clutch operation member that can swing around a drive shaft of a drive source,
An idle gear that is provided with a rotation shaft on the clutch operation member and is driven to rotate by a drive gear provided on a drive shaft of a drive source;
An output gear for transmitting power to the developing device;
With
Each of the clutch operation members has an operation end capable of coming into contact with the plurality of clutch operation levers that are displaced by being pushed by the top of the eccentric cam,
When the clutch operation member is pushed by the clutch operation lever and swings via these operation ends, the idle gear is coupled to the output gear and is capable of transmitting power from the drive gear to the output gear. 3. The apparatus according to claim 1, wherein the position is changeable between a retracted attitude that retracts from the output gear and separates the power from the drive gear and the output gear. The image forming apparatus described.

Images