JP3800295B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a technical field of an image forming apparatus such as an electrostatic copying machine or a printer having 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 rotating body. In particular, the present invention belongs to the technical field of an image forming apparatus of a contact development type in which development is performed in a state where the developing roller of the developing device is in contact with the photosensitive member.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrostatic copying machine or a printer, there are various image forming apparatuses provided with 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 rotating body. Has been developed. In this image forming apparatus, a rotating body is rotated at the time of image formation, and the developing roller of each developing device is sequentially set to a developing position, and a latent image on the photosensitive body is sequentially developed for each color to form an image. Yes.
[0003]
In this type of conventional image forming apparatus, there is a contact developing type image forming apparatus in which development is performed by keeping the developing roller away from the photosensitive member during normal development and bringing the developing roller into contact with the photosensitive member during development. In this contact developing type image forming apparatus, since the developing roller comes in contact with and separates from the photosensitive member, there is a risk that the photosensitive member may be damaged by the contact and separation of the developing roller. It is suppressed when it is brought into contact with and separated from the photoconductor in the rotating state. Therefore, in order to prevent damage to the photoreceptor, it is necessary to bring the developing roller into contact with and away from the photoreceptor while the developer roller is always rotated.
[0004]
As described above, as a method of transmitting the driving force of the driving motor of the developing device to the developing roller in order to make the developing roller rotate when the developing roller contacts the photoconductor,
(a) a fixed driving gear to which the driving force of a driving motor is transmitted and a developing roller driving gear on the developing roller side that is movably meshed during development;
(b) Engage the drive gear, which is provided so as to be able to swing, to which the driving force of the drive motor is transmitted and the developing roller drive gear on the developing roller side by swinging the drive gear that can swing during development. How to match,
(c) a method in which a driving gear to which a driving force of a driving motor is transmitted and a developing roller driving gear on the developing roller side are engaged with each other by a rotating force of a rotary body such as a rotary during development;
Has been adopted.
[0005]
On the other hand, such an image forming apparatus needs to be initialized first after being shipped from the factory. In performing this initialization, since the developing roller is driven at a predetermined developing position, in the contact developing type image forming apparatus, as described above, in order to prevent damage to the photosensitive member, a dummy toner is previously set at the time of shipment from the factory. Is applied to the developing roller, and the photosensitive member is prevented from being damaged by the lubricating action of the dummy toner.
[0006]
[Problems to be solved by the invention]
However, in the above-described method (a) in which the driving force of the developing device driving motor is transmitted to the developing roller, motive power can be transmitted only within the range of operation in which the gears are in contact with or separated from each other. In some cases, the developing roller may come into contact with the photoreceptor before it rotates sufficiently. Also, in the method (b), as in the method (a), power can be transmitted only within an operation range in which the gears are in contact with or separated from each other. There is a risk of contact with the body. Furthermore, in the method (c), when the rotation of the rotary and the rotation of the developing roller are switched, the rotation of the developing roller may stop or may not exceed a predetermined number of rotations.
[0007]
As described above, in any of the conventional methods (a) to (c) described above, there are cases where the developing roller does not rotate or does not sufficiently rotate when contacting or separating from the photoreceptor. It is difficult to sufficiently and reliably prevent damage to the photosensitive member when the developing roller is in contact with and separated from the photosensitive member.
In any of the methods (a) to (c), vibration is generated when the gear is in contact with or separated from the gear, and this vibration adversely affects the image quality and generates noise.
[0008]
Further, in the conventional image forming apparatus described above, in order to prevent damage to the photosensitive member during initialization, the dummy toner is applied to the developing roller in advance at the time of shipment from the factory. This requires not only complicated operations at the time of shipment, but also requires dummy toner in addition to developing toner, resulting in high costs.
[0009]
The present invention has been made in view of such circumstances, and an object of the present invention is to bring the developing roller into and out of contact with the photosensitive member in a state where the developing roller is reliably rotated, and to rotate the developing roller by a predetermined amount. An object of the present invention is to provide an image forming apparatus in which a developing roller can be brought into contact with and separated from a photosensitive member in a state where the number is set to several or more.
Another object of the present invention is to provide an inexpensive image forming apparatus capable of suppressing vibration and simplifying an initialization operation.
[0010]
[Means for Solving the Problems]
In order to solve this problem, the invention of claim 1 includes a plurality of rotating bodies rotatably provided on a frame, and a plurality of developing rollers that are attached to the rotating bodies and are capable of contacting and separating from the photoreceptor. A developing device is provided, and the developing roller is separated from the photosensitive member during non-development, and the driving force of the developing device drive motor during development The The developer is sequentially transmitted to the developing roller via a developing device driving force transmitting means, and the developing roller is sequentially moved to a developing position where the rotating member abuts on the photosensitive member by the rotation of the rotating member, and the developing member is stopped by the rotation of the rotating member. In the image forming apparatus that performs multi-color development by setting the position, the developing device driving force transmission means is provided rotatably on the frame and is rotated by the driving force of the developing device drive motor; A predetermined number of idler gears rotatably provided on the frame, and have teeth, and are wound around the developing device driving motor gear and the predetermined number of idler gears so that the teeth mesh with each other, and the developing device driving motor gear An endless belt made of an elastic body that is rotated by the driving force of the developing device drive motor that is transmitted to the rotating body for each developing device. A developing device driving gear provided to each of the developing rollers to transmit a driving force of the developing device driving motor, and the developing roller that is in contact with the photoconductor by the rotation of the rotating body includes Before reaching the developing position in contact with the photosensitive member, the developing device driving gear corresponding to the developing roller meshes with the teeth of the endless belt, and the developing roller moves from the developing position to move from the photosensitive member. After the separation, the developing device driving gear corresponding to the developing roller is disengaged from the teeth of the endless belt.
[0011]
According to a second aspect of the present invention, when the rotating body engages with the teeth of the endless belt and the developing roller reaches a predetermined number of rotations or more, the developing roller is moved to the developing roller. It is characterized in that it is set to a position and brought into contact with the photosensitive member.
Further, in the invention of claim 3, the rotating body is configured to perform the development after the developing device driving gear meshes with the teeth of the endless belt and the developing roller exceeds a predetermined rotational speed and a predetermined time elapses. A roller is set at the developing position and is brought into contact with the photosensitive member.
[0012]
Furthermore, the invention of claim 4 is characterized in that when the developing body is engaged with the teeth of the endless belt and the developing roller is at a predetermined rotational speed or more, the rotating body moves the developing roller to the developing position. To move away from the photosensitive member.
Further, in the invention of claim 5, the teeth of the endless belt are provided at least inside the endless belt, and the developing device driving gear meshes with the teeth from the inside of the endless belt. Or the teeth of the endless belt are provided at least on the outside of the endless belt, and the developing device driving gear meshes with the teeth from the outside of the endless belt. Yes.
[0013]
Further, the invention according to claim 6 is one in which one of the developing device driving gears is used as a tooth of the endless belt in a state where the rotating body is set to a position where none of the developing rollers comes into contact with the photosensitive member. The toner is supplied to the developing roller corresponding to the one developing device driving gear, and the other developing device driving gears are sequentially engaged with the teeth of the endless belt in the same manner to each developing device driving gear. Initialization is performed by supplying toner to a corresponding developing roller.
[0014]
[Action]
In the image forming apparatus according to the first aspect of the present invention configured as described above, the developing device corresponding to the developing roller before the developing roller to be in contact with the photosensitive member reaches the developing position in contact with the photosensitive member. The driving gear meshes with the teeth of the endless belt, and the driving force of the developing device driving motor is reliably transmitted to the developing roller. As a result, the developing roller always abuts on the photoconductor in a surely rotated state. Therefore, when contacting the photoconductor, a toner layer is formed on the developing roller, and the developing roller contacts the photoconductor through the toner layer. Come into contact. Further, after the developing roller in contact with the photosensitive member moves from the developing position and is separated from the photosensitive member, the engagement between the developing device driving gear corresponding to the developing roller and the teeth of the endless belt is released, and this developing roller Transmission of the driving force of the developing device drive motor to is reliably interrupted. As a result, the developing roller is always separated from the photoconductor while being reliably rotated, so that the developing roller is separated from the photoconductor through the toner layer. Therefore, the developing roller always rotates reliably and comes into contact with and separates from the photoreceptor in a state where the toner layer is formed. However, since the toner in the toner layer functions as a lubricant at that time, the photoreceptor is damaged. Is prevented.
[0015]
In addition, since the endless belt is made of an elastic body, vibration is effectively absorbed when the teeth and the developing device drive gear mesh. As a result, adverse effects on image quality due to this vibration are prevented, and noise during meshing is reduced.
Furthermore, since the power transmission mechanism provided on the outer side of the rotating body is constituted by an endless belt, the axial length of the developing unit including a plurality of developing units and the rotating body is shortened.
[0016]
In the invention of claim 2, the developing roller comes into contact with the photosensitive member in a state where the developing roller is always rotated at a predetermined rotational speed or more. As a result, the developing roller comes into contact with the photoconductor in a state where the toner is more reliably supplied, and thus the photoconductor is more reliably prevented from being damaged when the developing roller comes into contact.
Further, in the third aspect of the invention, the developing roller comes into contact with the photosensitive member after a predetermined time has passed while the developing roller is reliably rotated at a predetermined rotational speed or more. As a result, the toner is uniformly dispersed on the developing roller, the toner layer is uniformly formed on the developing roller, and the rotation fluctuation of the developing roller is reduced, so that the photoreceptor is more reliably prevented from being damaged.
[0017]
Furthermore, in the invention of claim 4, the developing roller is always separated from the photoconductor while being rotated at a predetermined rotational speed or more. As a result, the developing roller is separated from the photoconductor in a state where the toner is more reliably supplied, so that the photoconductor is more reliably prevented from being damaged when the developing roller is separated.
Furthermore, in the invention of claim 5, the developing device drive gear meshes from the inside of the endless belt or meshes from the outside of the endless belt. When the developing device driving gear is engaged from the inside of the endless belt, it is easy to attach the endless belt, and when the developing device drive gear is engaged from the outside of the endless belt, it is advantageous in terms of space. .
Further, in the invention of claim 6, the driving force of the developing device driving motor is reliably transmitted to each developing roller in order in a state where none of the developing rollers contact the photosensitive member, and the developing roller rotates. . Therefore, the image forming apparatus can be easily initialized after shipment from the factory without damaging the photoreceptor.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention, and FIG. 2 is a left side view of FIG. In FIG. 1, some of the components shown in FIG. 2 are omitted, and in FIG. 2, some of the components shown in FIG. 1 are omitted.
[0019]
As shown in FIG. 1, the image forming apparatus 1 of this example includes a rotary developing device 2, and the rotary developing device 2 is rotatably supported by a rotary 3 and supported by the rotary 3. , Yellow (Y), magenta (M), cyan (C), and black (K) developing devices 4, 5, 6, and 7. Each of these developing devices 4, 5, 6, and 7 is disposed in the circumferential direction of the rotary 3 in this order in the clockwise direction and at equal intervals. The developing rollers 4a, 5a, 6a, and 7a and the supply roller 4b are respectively provided. , 5b, 6b, 7b. As the rotary 3 rotates, each of the developing units 4, 5, 6, and 7 has their developing rollers 4a, 5a, 6a, and 7a sequentially contacted with the photosensitive member (hereinafter also referred to as OPC) 8. It has come to be. The arrangement order of the developing devices 4, 5, 6, and 7 for each color is arbitrarily set without being limited to the above-described order. However, in the following description, for convenience of explanation, it is assumed that the developing devices 4, 5, 6, and 7 are arranged in the order of the above-described colors, that is, yellow, magenta, cyan, and black.
[0020]
As shown in FIGS. 1 and 2, the image forming apparatus 1 further transmits a stepping motor 9 that is a rotary drive motor for rotationally driving the rotary 3 and the driving force of the stepping motor 9 to the rotary 3. A rotary driving force transmission means 10 for developing, a developing device driving motor 11 for rotationally driving the developing rollers 4a, 5a, 6a, 7a of the developing devices 4, 5, 6, 7 and the developing devices 4, 5, Each developing device driving force transmitting means 12Y is provided for every 6 and 7, and transmits the driving force of the developing device driving motor 11 to the developing rollers 4a, 5a, 6a and 7a and the supply rollers 4b, 5b, 6b and 7b. , 12M, 12C, 12K.
[0021]
The stepping motor 9 can be stopped while the supply current to the motor is supplied by setting the hold current by the current control, so that the position can be easily set. The stepping motor 9 is driven and controlled by a central processing unit (CPU) of the image forming apparatus 1.
The rotary driving force transmission means 10 is concentric with the rotary 3, a rotary driving gear 10 a that is attached to the rotary shaft of the stepping motor 9 so as to be integrally rotatable, a rotary driving intermediate gear 10 b that is always meshed with the rotary driving gear 10 a, and the rotary 3. The rotary gear 10c is provided integrally with the rotary 3 and always meshes with the rotary drive intermediate gear 10b. The drive force of the stepping motor 9 is decelerated and transmitted to the rotary 3. The rotary shaft 3a of the rotary 3 and the rotary gear 10c is rotatably supported by the frame 13 of the image forming apparatus 1.
Similarly, the developing device drive motor 11 is also fixed to the frame 13 and is driven and controlled by the CPU in the same manner as the stepping motor 9.
[0022]
Further, the developing device driving force transmission means 12Y, 12M, 12C, and 12K all have the same configuration, and the developing device driving motor gear 14 is attached to the rotating shaft of the developing device driving motor 11 so as to be integrally rotatable. And the three first to third idler gears 15, 16, and 17 rotatably supported by the frame 13, and the developing device drive gear 14 and the first to third idler gears 15, 16, and 17, respectively. As shown in FIG. 3 (a), an endless timing belt 18 having an internal tooth 18a that always meshes with each of the gears 14, 15, 16, and 17 and made of an elastic material such as rubber, and each developing roller 4a, Development roller drive gears 19 (development roller drive gears of the development rollers 5a, 6a, and 7a are not shown) attached to the respective rotation shafts 5a, 6a, and 7a so as to be integrally rotatable. First developing device driving intermediate gears 20 that are always meshed with the respective driving gears 19 (the first developing device driving intermediate gears that mesh with the developing roller driving gears of the developing rollers 5a, 6a, 7a are not shown), The supply roller drive gears 21 (supply rollers 5b, 6b, and 6b, which are respectively attached to the rotation shafts of the supply rollers 4b, 5b, 6b, and 7b so as to be integrally rotatable and constantly mesh with the first developing device drive intermediate gears 20, respectively. 7b and the supply roller drive gears of the second developing devices and the second developing device drive intermediate gears 22 that always mesh with the supply roller drive gears 21 (not shown) and the supply roller drive gears of the supply rollers 5b, 6b, and 7b. The second developing device driving intermediate gears meshing with the second developing device driving intermediate gears 22 and the third developing devices provided concentrically and integrally with the second developing device driving intermediate gears 22, respectively. Moving intermediate gears 23 (the third developing device driving intermediate gears connected to the supplying roller driving gears of the supplying rollers 5b, 6b, and 7b via the second developing device driving intermediate gears are not shown), and these The fourth developer drive intermediate gears 24 that are always meshed with the respective third developer drive intermediate gears 23 (the second and third developer drive intermediate gears on the supply roller drive gears of the supply rollers 5b, 6b, and 7b). The fourth developer drive intermediate gears connected to each other via the gears are not shown in the figure, and the fourth developer drive intermediate gears 24 are provided concentrically and integrally rotatable with the fourth developer drive intermediate gears 24, respectively. And a developing device drive gear 25 detachably engaged with the internal teeth 18a.
[0023]
The developing device drive motor gear 14 and the first to third idler gears 15, 16, and 17 perform a developing operation on the internal teeth 18 a of the timing belt 18 that is stretched over the gears 14, 15, 16, and 17 during image formation. The developing device driving gear 25 corresponding to the developing device meshes with the timing belt 18 while being elastically bent, and the developing device driving gear 25 corresponding to the developing device not performing the developing operation is separated from the timing belt 18. The installation position of is set.
[0024]
Next, rotation control of the developing rollers 4a, 5a, 6a, 7a and the supply rollers 4b, 5b, 6b, 7b by the driving force of the developing device driving motor 11 by the timing belt 18 will be described. In this description, for the sake of convenience, it is assumed that the developing roller that is to contact the OPC 8 this time is the developing roller 4 a of the yellow developing device 4. In the state shown in FIG. 1, the yellow developing roller 4a is already in contact with the OPC 8 and is in the developing position, that is, the rotational position C of the rotary 3 (hereinafter simply referred to as the position C, and the other rotational positions are the same). The description of the control by the timing belt 18 starts from a state in which the developing roller 7a of the black developing device 7 is in a position C where the developing roller 7a contacts the OPC 8, and the yellow developing roller 4a is not in this position C. When the developing roller 7a of the black developing device 7 is in the position C, the developing roller 4a of the yellow developing device 4 is in the position A where it does not contact the OPC 8. Further, the developing device drive gear 25 corresponding to the developing roller 7a meshes with the internal teeth 18a of the timing belt 18 while elastically bending the timing belt 18. Further, the driving force of the developing device driving motor 11 is transmitted to the developing device driving motor gear 14, and the timing belt 18 rotates in the same direction as the rotating direction of the developing device driving motor gear 14.
[0025]
In this state, the rotary 3 rotates in the clockwise direction indicated by the arrow, the developing roller 7a of the black developing device 7 that has been in contact with the OPC 8 so far is separated from the OPC 8, and the developing roller 4a rotates and moves toward the position C. To do. As will be described in detail later, the developing device driving gear 25 corresponding to the developing roller 7a is separated from the timing belt 18 thereafter.
[0026]
When the developing roller 4a is rotationally moved to the position B where it does not come into contact with the OPC 8, the developing device drive gear 25 corresponding to the developing roller 4a of the yellow developing device 4 flexes the timing belt 18 elastically, and the internal teeth of the timing belt 18 Meshes with 18a. Then, the rotation of the timing belt 18 by the driving force of the developing device driving motor 11 is transmitted to the developing device driving gear 25 corresponding to the developing roller 4a, and the developing device driving gear 25 rotates in the same direction as the rotating direction of the timing belt 18. To do. The rotation of the developing device driving gear 25 is transmitted to the yellow developing roller 4a and the supply roller 4b via the yellow developing device driving force transmitting means 12Y, and both rollers 4a and 4b start to rotate.
[0027]
When the rotary 3 further rotates in the same direction and the developing roller 4a rotates and moves to the developing position C at which the developing roller 4a contacts the OPC 8 as shown in FIG. 1, the CPU stops the stepping motor 9 for driving the rotary, and the rotary 3 Stops rotating. At this time, the developing device driving gear 25 further flexes the timing belt 18 more elastically, the meshing between the developing device driving gear 25 and the internal teeth 18a of the timing belt 18 becomes more reliable, and the developing roller 4a rotates by a predetermined amount. Continues rotating at a rotational speed greater than the number.
As described above, the developing roller 4a starts rotating before the OPC 8 comes into contact, and is brought into contact with the OPC 8 while being rotated at a predetermined rotational speed or more to be set at the developing position.
[0028]
Next, when the yellow developing is completed and the stepping motor 9 is driven again and the rotary 3 rotates again in the same direction, the developing roller 4a is separated from the OPC 8 while rotating at a rotational speed equal to or higher than a predetermined rotational speed. When the developing roller 4a rotates and moves to the position D, the developing device driving gear 25 is separated from the timing belt 18, and the rotation of the developing roller 4a is stopped.
[0029]
The rotation control of the developing rollers 5a, 6a, 7a and the supply rollers 5b, 6b, 7b by the driving force of the developing device driving motor 11 in the magenta developing device 5, the cyan developing device 6 and the black developing device 7 is also performed. In this order, each developing device drive gear 25 is engaged with the internal teeth 18a of the timing belt 18, so that the same operation as that of the yellow developing device 4 is performed.
[0030]
Next, the operation at the time of image formation of the image forming apparatus 1 of this example configured as described above will be described.
In FIG. 1, the developing roller 4a of the yellow developing device 4 is shown in contact with the OPC 8, but the developing rollers 4a, 5a, 6a, and 7a of the developing devices 4, 5, 6, and 7 are not in contact with each other. During development, both are held at positions separated from the OPC 8. That is, with the yellow developing roller 4a positioned between the position A and the position B, the rotary 3 is stopped and held, and the couplings 12k are held in a disconnected state.
[0031]
When the operation of the image forming apparatus 1 for image formation is started, both the stepping motor 9 and the developing device drive motor 11 are driven by the CPU. Since the developing device driving motor gear 14 is rotated by the driving of the developing device driving motor 11, the timing belt 18 that is always meshed with the developing device driving motor gear 14 is rotated. Accordingly, during the image forming operation, the developing device drive motor gear 14 and the timing belt 18 are always rotating. At the same time, the rotary 3 is rotated clockwise by the driving of the stepping motor 9, and the yellow developing roller 4a is rotated toward the position B.
[0032]
When the developing roller 4a reaches the position B, the yellow developing device driving gear 25 starts to mesh with the internal teeth 18a of the timing belt 18 as described above, and both the developing roller 4a and the supply roller 4b start to rotate. Thus, toner is supplied from the supply roller 4b to the developing roller 4a, and a toner layer having a predetermined thickness is started to be formed on the surface of the developing roller 4a by a toner regulating member (not shown). When the rotary roller 3 further rotates in the same direction and the developing roller 4a reaches a position C where the developing roller 4a contacts the OPC 8 which is the developing position after a predetermined time has elapsed, the rotation of the rotary roller 3 stops. Since a predetermined time elapses from when the developing roller 4a starts to rotate to the developing position and there is a margin for the rotation rise time of the developing roller 4a, when the developing roller 4a reaches the developing position, the developing roller 4a is predetermined. Rotating above the number of rotations. Therefore, the toner is uniformly dispersed on the developing roller 4a, and a toner layer having a predetermined thickness is securely formed on the surface of the developing roller 4a. When the developing roller 4a contacts the OPC 8, damage to the OPC 8 is prevented. Is done. As a result, the developing roller 4a conveys a predetermined amount of toner toward the OPC 8, and the latent image on the OPC 8 is developed in yellow. The developed yellow image on the OPC 8 is intermediately transferred to the intermediate transfer medium 26.
When the yellow developing roller 4a is at position C, the developing roller 4a of the next magenta developing device 5 is at position A as shown in FIG.
[0033]
When the yellow development is completed, the rotary 3 rotates again in the same direction, and the developing roller 4a rotates away from the OPC 8. When the developing roller 4a reaches the position D, the developing device driving gear 25 is separated from the timing belt 18, the developing device driving gear 25 and the internal teeth 18a of the timing belt 18 are released from meshing, and the developing roller 4a and the supply roller 4b Both rotations stop.
[0034]
When the rotary 3 is further rotated and the developing roller 5a of the magenta developing device 5 reaches the position B, the developing device driving gear 25 is brought into contact with the internal teeth 18a of the timing belt 18 as in the case of the yellow developing device 4 described above. Engagement starts, and both the magenta developing roller 5a and the supply roller 5b start rotating. Thereafter, the developing operation by the magenta developing device 5 is performed in the same manner as the developing operation by the yellow developing device 4, whereby the magenta development is performed on the latent image on the OPC, and the development on the OPC is performed. The magenta image thus obtained is intermediately transferred to the intermediate transfer medium 14.
[0035]
Subsequently, in the same manner as the yellow development by the yellow developing device 4, the developing device driving gear 25 corresponding to the cyan developing by the cyan developing device 6 and the black developing by the black developing device 7 is included in the timing belt 18. The developed images are sequentially transferred by meshing with the teeth 18 a, and each developed image is intermediately transferred to the intermediate transfer medium 14. The four-color images intermediately transferred to the intermediate transfer medium 14 are color-matched, transferred to transfer paper by a transfer device (not shown), and fixed by a fixing device, thereby forming a full-color image.
[0036]
Incidentally, it is necessary to initialize the image forming apparatus 1 before the user uses the image forming apparatus 1 shipped from the factory. When the image forming apparatus 1 is initialized, a predetermined amount of toner must be supplied to the developing roller to form a toner layer on the surface of the developing roller in order to prevent OPC damage due to contact with the developing roller. Don't be. Therefore, in the image forming apparatus 1 of this example, the four developing rollers 4a, 5a, 6a, and 7a are not in contact with the OPC 8 in order and the developing device driving gear 25 is meshed with the internal teeth 18a of the timing belt 18. With the rotary 3 stopped, the developer rollers 4a, 5a, 6a, and 7a are rotated so that a predetermined amount of toner is supplied to the developer rollers 4a, 5a, 6a, and 7a. Yes.
That is, as shown in FIG. 1, the initialization position E is at an arbitrary position where the developing rollers 4a, 5a, 6a, 7a do not contact the OPC 8 and the developing device driving gear 25 meshes with the internal teeth 18a of the timing belt 18. Is set.
[0037]
When initializing the image forming apparatus 1 shipped from the factory, first, when the stepping motor 9 is driven to rotate the rotary 3 and the developing roller of one developing unit comes to the initialization position E, The driving of the stepping motor 9 is stopped by the CPU, and the rotation of the rotary 3 is stopped. Next, when the developing device driving motor 11 is driven by the CPU and the timing belt 18 is rotated, one developing device driving gear 25 is rotated, the developing roller and the supply roller of the developing device are rotated, and the developing roller is rotated. The toner is supplied to the surface to form a toner layer having a predetermined thickness on the surface. Next, with respect to the remaining developing devices, toner is supplied to the developing rollers in the same manner as described above, and a toner layer having a predetermined thickness is formed on the surface thereof. Thereby, the image forming apparatus 1 is initialized in a short time without damaging the OPC 8.
[0038]
As described above, according to the image forming apparatus 1 of this example, when the developing rollers 4a, 5a, 6a, and 7a are brought into contact with the OPC 8, respectively, the developing rollers 4a, 5a, 6a, and 7a are always rotated. In this case, the developing rollers 4a, 5a, 6a, and 7a can always be brought into contact with the OPC 8 while being rotated at a predetermined rotational speed or more. Further, when the developing rollers 4a, 5a, 6a, and 7a are separated from the OPC 8, respectively, the developing rollers 4a, 5a, 6a, and 7a can be separated from the OPC 8 in a state in which they are always rotated. In this case, the developing rollers 4a, 5a, 6a, 7a can be separated from the OPC 8 while being rotated at a predetermined rotational speed or more. As a result, the developing rollers 4a, 5a, 6a, 7a and the supply rollers 4c, 5c, 6c, 7c are rotated when the developing rollers 4a, 5a, 6a, 7a are brought into contact with and separated from the OPC 8, so that the developing rollers 4a, 5a , 6a, 7a can form a toner layer having a predetermined thickness. Accordingly, the developing rollers 4a, 5a, 6a, and 7a can be brought into contact with and separated from the OPC 8 through the toner layer, and the toner functions as a lubricant, so that damage to the OPC 8 can be effectively prevented.
[0039]
Further, by appropriately freely setting the meshing start position of the developing device driving gear 25 and the inner teeth 18a of the timing belt 18, the rotation of the developing rollers 4a, 5a, 6a, 7a and the supply rollers 4c, 5c, 6c, 7c is rotated. The drive position can be set freely, and there is a sufficient time until the developing rollers 4a, 5a, 6a, and 7a come into contact with the OPC 8, so that the toner is uniformly distributed to the developing rollers 4a, 5a, 6a, and 7a. Can be dispersed. In addition, even if there are load fluctuations in the developing rollers 4a, 5a, 6a, and 7a, the developing rollers 4a, 5a, 6a, and 7a have extra time for rotation, so that the developing rollers 4a, 5a, 6a, and 7a Before contact, the rotation speed of the developing rollers 4a, 5a, 6a, 7a equal to or higher than the predetermined rotation speed can be obtained more reliably, and the rotation fluctuation of the developing rollers 4a, 5a, 6a, 7a can be reduced. Therefore, a high-quality image can be formed and the life of the image forming apparatus 1 can be extended.
[0040]
Further, the developing rollers 4a, 5a, 6a, and 7a and the supply rollers 4c, 5c, 6c, and 7c are rotationally driven only in a predetermined area including the developing position, and the rotation is stopped in other areas. Toner scattering can be suppressed.
Furthermore, according to the image forming apparatus 1 of this example, power transmission to the developing roller and the supply roller is performed by meshing control between the internal teeth 18a of the timing belt 18 and the developing device driving gear 25, so that the configuration is simple. The developing rollers 4a, 5a, 6a, and 7a can be easily and reliably brought into contact with and separated from the OPC 8 in a rotating state. In this case, the developing device driving gear 25 elastically bends the timing belt 18 so that the inner teeth 18a and the developing device driving gear 25 are engaged with each other. Engagement can be performed.
[0041]
Furthermore, since the timing belt 18 is made of an elastic body such as rubber, vibrations can be effectively absorbed when the inner teeth 18a mesh with the developing device drive gear 25. Thereby, it is possible to prevent an adverse effect on the image quality due to the vibration and to reduce noise at the time of meshing.
Furthermore, since the part of the power transmission mechanism provided outside the rotary is constituted by the timing belt 18, the length of the developing device 3 in the axial direction can be shortened.
Furthermore, according to the image forming apparatus 1 of this example, since all the gears are arranged inside the timing belt 18, the mounting work over these gears is simplified.
[0042]
Furthermore, according to the image forming apparatus 1 of the present example, the developing rollers 4a, 5a, 6a, and 7a are sequentially set to positions that do not come into contact with the OPC 8 in the initialization after shipment from the factory, and the developing rollers are driven. As a result, each toner layer can be reliably formed on the surface of the developing roller, so that the initialization can be performed in a short time without damaging the OPC 8. This eliminates the need to apply dummy toner to the surfaces of the developing rollers 4a, 5a, 6a, and 7a, which has been conventionally performed at the time of factory shipment. Will be easier.
Furthermore, since no dummy toner is required, the cost can be reduced and only the toner for image formation is used, so that the toner can be recycled.
[0043]
FIG. 4 is a view similar to FIG. 1 showing another example of the embodiment of the present invention. Note that the same reference numerals are given to the same components as those in the above-described example, and detailed description thereof will be omitted.
In the above-described example, the developing device driving gear 25 is disposed inside the timing belt 18 so as to mesh with the internal teeth 18a of the timing belt 18. In the image forming apparatus 1 of this example, as shown in FIG. Thus, the developing device driving gear 25 is arranged outside the timing belt 18 so that the developing device driving gear 25 is engaged from the outside of the timing belt 18. That is, as shown in FIG. 3B, the inner teeth 18a and the outer teeth 18b are provided on both the inner and outer sides of the timing belt 18, respectively. The developing device driving motor gear 14 and the first and second idler gears 15 and 16 are always meshed with the inner teeth 18a from the inside of the timing belt 18, and the developing device driving gear 25 is removed from the outside of the timing belt 18 with the outside. The teeth 18b are detachably engaged with each other.
Other configurations of the image forming apparatus 1 in this example are the same as those in the above-described example.
The operation of the image forming apparatus 1 in the example is the same as that in the above example.
Furthermore, according to the image forming apparatus 1 of this example, the timing belt 18 can be arranged in a compact manner, which is advantageous in terms of space. Other functions and effects of the image forming apparatus 1 of this example are the same as those of the above-described example.
[0044]
In the above-described example, the present invention is applied to a full-color image forming apparatus having an intermediate transfer medium. However, the present invention is not limited to a plurality of developing units such as two or more single-color image forming apparatuses. Can be applied to any image forming apparatus as long as the image forming apparatus is mounted on the rotating body and the developing roller is in contact with the photosensitive member.
[0045]
【The invention's effect】
As is apparent from the above description, according to the image forming apparatus of the present invention, the developing roller is always in contact with and away from the photoconductor while being reliably rotated. At the time of separation, a toner layer can be formed on the surface of the developing roller. As a result, the developing roller can be brought into contact with and separated from the photoreceptor via the toner layer, and the toner functions effectively as a lubricant, thereby effectively preventing damage to the photoreceptor. Therefore, a high quality image can be formed and the life of the image forming apparatus can be improved.
[0046]
In addition, since the endless belt is made of an elastic body, it is possible to effectively absorb vibrations generated when the teeth and the developing device drive gear mesh. Thereby, it is possible to prevent an adverse effect on the image quality due to the vibration and to reduce noise at the time of meshing.
Furthermore, since the power transmission mechanism provided on the outer side of the rotating body is constituted by an endless belt, the length in the axial direction of the developing unit including a plurality of developing units and the rotating body can be shortened.
[0047]
In particular, according to the second aspect of the present invention, since the developing roller is in contact with the photosensitive member in a state where the developing roller is always rotated at a predetermined rotational speed or more, the toner can be supplied to the developing roller more reliably. It is possible to more reliably prevent the photoreceptor from being damaged when the roller contacts. Further, according to the invention of claim 3, since the developing roller is always reliably rotated at a predetermined rotational speed or more and is brought into contact with the photosensitive member after a predetermined time has elapsed, the toner is uniformly applied to the developing roller. While being able to disperse | distribute, the rotation fluctuation | variation of a developing roller can be suppressed. As a result, the toner layer can be uniformly formed on the developing roller, and the rotational fluctuation of the developing roller can be reduced, so that the photoreceptor can be more reliably prevented from being damaged. Therefore, it is possible to form a higher quality image and to further extend the life of the image forming apparatus.
[0048]
Furthermore, according to the invention of claim 4, since the developing roller is always separated from the photosensitive member in a state of rotating at a predetermined rotational speed or more, the developing roller is operated in a state where the toner is more reliably supplied to the developing roller. The photosensitive member can be separated from the photosensitive member, and damage to the photosensitive member can be more reliably prevented when the developing roller is separated.
Further, according to the invention of claim 5, the developing device driving gear is meshed from the inside of the endless belt or meshed from the outside of the endless belt. When meshing from the inside, the endless belt can be easily mounted, and when the developing device drive gear is meshed from the outside of the endless belt, it is advantageous in terms of space.
[0049]
Further, according to the invention of claim 6, since the developing roller can be rotated without contacting the photoconductor, the initialization of the image forming apparatus can be shortened after shipment from the factory without damaging the photoconductor. Easy to do in time. This also eliminates the need to apply dummy toner to the surface of each developing roller, which has been conventionally performed at the time of factory shipment, eliminating the need for dummy toner application at the time of factory shipment and simplifying the operation at the time of shipment. be able to.
Furthermore, since no dummy toner is required, the cost can be reduced and only the toner for image formation is used, so that the toner can be recycled.
[Brief description of the drawings]
FIG. 1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus of the present invention.
FIG. 2 is a left side view in FIG.
3 partially shows the timing belt in FIGS. 1 and 4 and each gear meshing with the timing belt, (a) is a sectional view partially showing the timing belt in FIG. 1, and (b) is a diagram. FIG. 6 is a cross-sectional view partially showing a timing belt in FIG.
FIG. 4 is a view similar to FIG. 1, schematically and partially showing another example of the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Developing device, 3 ... Rotary, 4 ... Yellow developing device, 5 ... Magenta developing device, 6 ... Cyan developing device, 7 ... Black developing device, 4a, 5a, 6a, 7a ... Developing roller, 4b, 5b, 6b, 7b ... Supply roller, 8 ... Photoconductor (OPC), 9 ... Stepping motor, 10 ... Rotary driving force transmitting means, 11 ... Developer driving motor, 12Y, 12M, 12C, 12K ... Developing device driving force transmission means 13... Frame 14. Developing device driving motor gear 15. First idler gear 16. Second idler gear 17. Third idler gear 18. Endless timing belt 19. Gear 20, first developing device driving intermediate gear 21, supply roller driving gear 22, second developing device driving intermediate gear 23, third developing device driving intermediate gear 24, fourth developing device driving intermediate gear 25 ... Image device drive gear, 26 ... intermediate transfer medium, the contact position of the OPC of C ... developing roller

Claims (6)

A rotating body provided rotatably on the frame, and a plurality of developing units each mounted on the rotating body and capable of coming into contact with and separating from the photosensitive body, and the developing roller being the photosensitive body when not developing The developing device drive motor driving force is sequentially transmitted to the developing roller via the developing device driving force transmitting means at the time of development, and the developing roller contacts the photoconductor in turn by the rotation of the rotating body. In an image forming apparatus that performs multicolor development by moving to a development position and setting the development position by stopping the rotation of the rotating body,
The developing device driving force transmission means is rotatably provided on the frame and is rotated by a driving force of the developing device drive motor, and a predetermined number of idler gears rotatably provided on the frame; Elasticity having teeth and being wound around the developing device driving motor gear and the predetermined number of idler gears so that the teeth mesh with each other and rotated by the driving force of the developing device driving motor transmitted to the developing device driving motor gear An endless belt comprising a body, and a developer driving gear provided on the rotating body so as to be rotatable for each developing unit, and transmitting a driving force of the developing unit driving motor to each developing roller,
The developing device driving gear corresponding to the developing roller is brought into contact with the teeth of the endless belt before the developing roller that is in contact with the photoconductor by the rotation of the rotating body reaches the developing position in contact with the photoconductor. An image is characterized in that the developer driving gear corresponding to the developing roller is disengaged from the teeth of the endless belt after the developing roller is moved from the developing position and separated from the photosensitive member. Forming equipment. When the developing device driving gear meshes with the teeth of the endless belt and the developing roller reaches a predetermined number of revolutions or more, the rotating body is set at the developing position and is attached to the photosensitive member. The image forming apparatus according to claim 1, wherein the image forming apparatus is in contact with the image forming apparatus. The rotating body sets the developing roller to the developing position after the developing device driving gear meshes with the teeth of the endless belt and the developing roller reaches a predetermined rotational speed or more and a predetermined time elapses. The image forming apparatus according to claim 1, wherein the image forming apparatus is brought into contact with the photosensitive member. The rotating body moves away from the photosensitive member by moving the developing roller from the developing position when the developing device driving gear meshes with the teeth of the endless belt and the developing roller is at a predetermined rotational speed or more. The image forming apparatus according to claim 1, wherein: Teeth of the endless belt are provided at least on the inner side of the endless belt, and the developing device driving gear meshes with the teeth from the inner side of the endless belt, or the endless belt 5. A tooth according to claim 1, wherein teeth are provided at least outside the endless belt, and the developing device driving gear meshes with the teeth from the outside of the endless belt. The image forming apparatus according to 1. With the rotating body set at a position where each of the developing rollers is not in contact with the photoconductor, one of the developing device driving gears is engaged with the teeth of the endless belt to drive this one developing device. The toner is supplied to the developing roller corresponding to the gear, and the other developing device driving gear is sequentially meshed with the teeth of the endless belt, and the toner is supplied to the developing roller corresponding to each developing device driving gear in the same manner. 6. The image forming apparatus according to claim 1, wherein the image forming apparatus performs initialization.

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