JP2004125999A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus constituted so that toner and a photoreceptive layer are not deteriorated before all the developing cartridges and image carriers are used to the limit and troubles of a defective image and toner-scattering, etc., are prevented with a simple constitution and at a low cost. <P>SOLUTION: As for the typical constitution of the image forming apparatus, the apparatus is provided with the image carrier, several developing units equipped a developing means for forming a toner image on the image carrier, a drive transmission means arranged in the apparatus body so as to transmit the drive to the several developing units, and a means for connecting/disconnecting the drive to/from the developing units, the drive is transmitted from one driving source to the several developing units, the image forming apparatus is provided with a means for selectively connecting/disconnecting the drive to/from at least one developing unit among the several developing units. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic method.
[0002]
[Prior art]
In an image forming apparatus, an electrostatic latent image is formed on a surface of a photosensitive drum or a photosensitive belt as an image carrier, and the electrostatic latent image on the image carrier is developed with toner or the like as a developer. A device configured to transfer a developed image into a visible image, transfer the developed image onto a transfer material by a transfer device to carry the image, and fix the toner image on the transfer material onto the transfer material by a fixing device using pressure, heat, or the like. There is. Further, in order to obtain a multi-color image (a so-called color image), it is possible to use a multi-color developer. If a yellow, magenta, or cyan developer is used in principle, a full-color image can be obtained by mixing colors. In addition, by using a black developer in addition to the above three types, only a black developer is used when forming a black and white image having a high output frequency such as a document, thereby suppressing consumption of a multicolor developer. Can do things.
[0003]
A typical configuration of a color image forming apparatus is provided with a developing device for accommodating the developer for each color, arranging the plurality of developing devices on a straight line or a curve, and forming an electrostatic latent image corresponding to the developer of each color. Develop the image. There are a direct transfer method and an intermediate transfer method as a method of superimposing a plurality of color images in a color image forming apparatus until a final image is obtained on a transfer material such as paper or a plastic sheet.
[0004]
The former direct transfer method is a case where a transfer material transfers a developed image on an image carrier adjacent to (or included in) the developing device in the next step. An electric bias is formed to attract the developer on the image carrier to the transfer material when the transfer material contacts or passes through the image carrier at a small gap, and the image is directly transferred from the image carrier to the transfer material. Let it. In a color image forming apparatus having a plurality of developing devices and a plurality of image carriers, a transfer material is moved to an image carrier corresponding to each color, and a developed image corresponding to each color is sequentially transferred to the transfer material.
[0005]
On the other hand, in the latter intermediate transfer method, there is a second image carrier that holds all the developed images of each color during the process of transferring the image from the image carrier to the transfer material. From the image carriers corresponding to each color, the second image carrier once holds all the developed images, and the second image carrier and the transfer material downstream from the transfer position between the first and second image carriers. And an electric bias is formed at the contact point to transfer the image from the second image carrier to the transfer material. This second image carrier is called an intermediate transfer member.
[0006]
The color image forming apparatus using the intermediate transfer method is more advantageous than the direct transfer method in terms of stability of the formed image. When transferring a single-color developed image on the image carrier corresponding to each color in the next step, the developer must be superposed. In the direct transfer method, since the developer is transferred from the image carrier to the transfer material, the transfer environment is different depending on the physical properties, thickness, stiffness, etc. of the transfer material, resulting in instability during superposition. Further, the transferability of the transfer material also affects the image. Depending on the attraction force of the transfer material, the developer already transferred to the transfer material may be re-transferred to the downstream image carrier. On the other hand, in the intermediate transfer method, the transfer target in the superposition process is always the same object, so that a stable superimposed image can be obtained. Then, since the image is transferred from the intermediate transfer member to the transfer material at a time, the transfer conditions may be set for the worst condition transfer material.
[0007]
However, even in a color image forming apparatus, when a black and white image of a document or the like is frequently output, if a color developing unit that does not develop while black and white (monochrome) recording is continued is operated, the color developing unit is not operated. There has been a problem that the image carrier and the developer deteriorate and the life is shortened. In order to solve this problem, as described in JP-A-06-258914, JP-A-2001-242680, and JP-A-2001-209234, the problem is caused by retracting the transfer roller facing the image carrier of the color developing device. Has been resolved.
[0008]
[Patent Document 1]
JP-A-06-258914
[Patent Document 2]
JP 2001-242680A
[Patent Document 3]
JP-A-2001-209234
[Problems to be solved by the invention]
However, in the above conventional example, as shown in FIG. 15, the input gear 101 (101Y, 101M, 101C, 101K) for transmitting the drive to a plurality of developing cartridges is configured to be driven and transmitted by a single motor 100 by a gear train. In the image forming apparatus, when recording only a single color, for example, in the case of K single color recording, the input gears 101 of the developing cartridges of the respective colors YMC that are not recorded are simultaneously driven. At this time, the toner in the developing cartridge tends to deteriorate as the toner is agitated by the toner feed screw or the like. The problem is that the deterioration of the toner is promoted, and the deteriorated toner causes image failure and toner scattering.
[0009]
Further, as shown in FIG. 16, when a single motor 100 'drives and transmits the drive gears of a plurality of image carriers by a gear train, similarly, only a single color is recorded. In this case, the drive gear 102 (102Y, 102M, 102C, 102K) and the coupling 103 (103Y, 103M, 103C, 103K) of the image carrier of each color of YMC that are not recorded are simultaneously driven. At this time, the photosensitive layer of the image carrier is scraped or scratched by an abutting member such as a cleaning unit for the image carrier. Then, in the case of a user who has a large output in K single color, the deterioration of the photosensitive layer of the image carrier of each color of YMC is promoted even though the full-color image is not recorded, the image quality is deteriorated, and the image carrier is subjected to the target recording. It has been a problem that a phenomenon that the service life is reached before the number of sheets is reached occurs.
[0010]
Therefore, the present invention provides an image forming apparatus which has a simple configuration and low cost, does not deteriorate the toner or the photosensitive layer until all the developing cartridges and the image bearing members reach the end of their life, and does not cause problems such as image defects and toner scattering. It is intended to provide.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a typical configuration of an image forming apparatus according to the present invention includes an image carrier, a plurality of developing units having a developing unit for forming a toner image on the image carrier, and a developing unit provided on the apparatus main body. An image forming apparatus, comprising: a drive transmitting unit for transmitting drive to the plurality of developing units; and a unit for driving connection or disconnection to the developing units, and transmitting drive from one drive source to the plurality of developing units. Wherein said plurality of developing units are provided with means for selectively driving connection or disconnection to at least one developing unit.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
[First embodiment]
A first embodiment of the image forming apparatus according to the present embodiment will be described.
(Overall description of image forming apparatus)
First, the overall configuration of the image forming apparatus will be schematically described with reference to FIG. FIG. 14 is an explanatory diagram of the overall configuration of a color laser printer which is an embodiment of the image forming apparatus.
[0013]
The printer shown in FIG. 14 has an image forming section having an image carrier 21 rotating at a constant speed for each of Y, M, C, and K colors and an image forming section having developing units 2Y, 2M, 2C, and 2K. And an intermediate transfer unit 3 for holding the transferred color image and further transferring it to the transfer material P fed from the feeding unit. The transfer material P on which the color image has been transferred is transported to the fixing unit 50 to fix the color image on the transfer material P, and is discharged to a discharge unit 65 on the upper surface of the apparatus by a discharge roller. The four color developing units 2 are configured to be individually detachable from the printer main body.
[0014]
Next, regarding the configuration of each part of the image forming apparatus, parts related to the present invention will be sequentially described in detail.
[0015]
(Image carrier)
The image carrier 21 (21Y, 21M, 21C, 21K) is integrally formed with a container 24 (24Y, 24M, 24C, 24K) of a developing device, and the developing unit 2 (2Y, 2M, 2C, 2K) is a printer. The unit is detachably supported by the main body, and is configured so that the unit can be easily replaced according to the life of the image carrier 21. The image carrier 21 according to the present embodiment is a photosensitive drum in which an organic photoconductor layer is applied to the outside of an aluminum cylinder, and is rotatably supported by a container 24 of the image carrier 21. Further, by transmitting the driving force of a driving motor (not shown) to one end on the rear side in the figure, the image carrier 21 is rotated counterclockwise in the figure in accordance with the image forming operation.
[0016]
(Intermediate transfer member)
The intermediate transfer member 35 of the intermediate transfer unit 3 performs multiple transfer of the toner image on the image carrier 21 visualized by each developing unit 2 during the operation of the printer. Rotate around. The toner image formed on the image carrier 21 is disposed at a position opposite to the image carrier 21 with the intermediate transfer member 35 interposed therebetween, and a primary transfer roller 34 (34Y, 34M, 34C, 34K) to which a voltage is applied. Are transferred onto the intermediate transfer member 35 at the primary transfer portions T1 (T1Y, T1M, T1C, and T1K), which are the contact points. The intermediate transfer body 35 that has undergone the multiple transfer is transported with the transfer material P sandwiched and transported by the secondary transfer roller 51 to which a voltage is applied in the secondary transfer portion T2, so that each color on the intermediate transfer body 35 is transferred to the transfer material P. Simultaneous multiple transfer of toner images.
[0017]
The intermediate transfer body 35 (intermediate transfer belt) according to the present embodiment is formed of a seamless resin belt having a circumference of about 620 mm. The intermediate transfer member 35 is stretched around three axes of a drive roller 31, a secondary transfer opposing roller 32, and a tension roller 33, and both ends of the tension roller 33 are loaded with springs. Even if it changes due to changes in humidity or diameter, the amount of change can be absorbed.
[0018]
A guide rib 36 made of rubber is attached by an adhesive to the entire periphery of one side edge inside the intermediate transfer body 35. A flange made of resin is disposed at one end of the tension roller 33 and has a slope. The guide rib 36 and the flange regulate the movement (deviation) in the direction perpendicular to the running direction of the intermediate transfer body 35. ing.
[0019]
The intermediate transfer body 35 is supported by the main body with the driving roller 31 as a fulcrum, and by transmitting a driving force of a driving motor (not shown) to one end on the rear side of the driving roller 31 in the drawing, the intermediate transfer body 31 is moved in accordance with an image forming operation. It is rotated clockwise in the figure.
[0020]
(Transfer section)
The transfer section has a transfer roller 51 that can swing. The transfer roller 51 has a metal shaft wound around a medium-resistance foamed elastic body, and is movable substantially vertically in the figure and has a drive. The transfer roller 51 is pressed by a cam member (not shown) at an upper position, that is, the intermediate transfer body 35 via the transfer material P with a predetermined pressure at the timing of transferring a color image onto the transfer material P. At this time, a bias is applied to the transfer roller 51 at the same time, and the toner image on the intermediate transfer body 35 is transferred to the transfer material P. Here, since the intermediate transfer body 35 and the transfer roller 51 are driven respectively, the transfer material P sandwiched between them is conveyed at a predetermined speed to the left in the figure at the same time as the transfer process is performed. The sheet is conveyed by the belt 52 toward the fixing section 6 which is the next step.
[0021]
(Image forming operation)
Next, an operation when image formation is performed by the apparatus configured as described above will be described. First, the feed roller 41 is rotated to separate one transfer material P in the feed cassette 4 and transported to the registration roller 44. On the other hand, the image carrier 21 and the intermediate transfer member 35 rotate at a predetermined outer peripheral speed V (process speed) in the direction indicated by the arrow. The image carrier 21 whose surface is uniformly charged by the charging means 23 receives exposure from the laser 10 and forms an electrostatic latent image.
[0022]
To explain using the formation of a yellow image as an example, the scanner unit 1Y irradiates the laser 10Y of the yellow image to form a yellow latent image on the image carrier 21Y. Simultaneously with the formation of the latent image, the yellow developing device 22Y is driven, and a voltage having substantially the same potential as the charging polarity of the image carrier 21Y is applied so that the yellow toner adheres to the latent image on the image carrier 21Y. Perform yellow development. At the same time, the yellow toner image on the image carrier 21 is primarily transferred to the outer periphery of the intermediate transfer body 35 in the primary transfer section T1Y downstream of the developing section. At this time, a voltage having a polarity opposite to that of the yellow toner is applied to the intermediate transfer member 35 to perform primary transfer.
[0023]
Hereinafter, similarly, for the images of magenta, cyan, and black, an electrostatic latent image is formed by the scanner units 1M, 1C, and 1K so that the image formed on the image carriers 21M, 21C, and 21K has the same leading edge as the image. Then, the toner is developed by each of the color developing units 22M, 22C, and 22K to form a toner image of each color, and is primary-transferred onto the intermediate transfer body 35 so as to overlap with the previously transferred image. As a result, a full-color image composed of four kinds of toners of yellow, magenta, cyan, and black is formed on the surface of the intermediate transfer member 35.
[0024]
Before the transfer of the black toner to the intermediate transfer member 35 is completed, that is, before the image leading end of the intermediate transfer member 35 having formed the full-color image after the primary transfer of the fourth color black toner reaches the secondary transfer portion T2 Then, the transfer material P, which has been waiting by the above-described registration roller 44, is conveyed and started at the same timing. The secondary transfer roller 51 waits downward during the primary transfer and is in a non-contact state with the intermediate transfer body 35, and is moved upward by a cam (not shown) at the same time as the transfer of the transfer material P is started. At the secondary transfer portion T2 of the intermediate transfer member 35. Further, a bias having a characteristic opposite to that of the toner is applied to the secondary transfer roller 51, and the full-color image on the intermediate transfer body 35 is secondarily transferred to the transfer material P in a batch of four colors. The transfer material P having passed through the secondary transfer portion T2 is peeled off from the intermediate transfer member 35, is conveyed to the fixing portion 6, and after fixing the toner, is discharged onto a discharge tray 56 at the upper portion of the main body via discharge roller pairs 53, 54, 55. The image is discharged with the image side facing down, and the image forming operation ends.
[0025]
(Drive transmission means)
Next, the configuration of the drive transmission means, which is the center of the present invention, will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a drive transmission unit to a developing unit according to the first embodiment.
[0026]
As shown in FIG. 1, in this embodiment, since the four color developing units 2 are driven by one motor 7, the input gear 25 (25Y, 25M, 25C, 25K) of each color developing unit 2 is formed by a gear train. The drive is transmitted. The gear train is branched from the middle, and the drive train is transmitted to the input gear 25 of the developing unit 2 of each color.
[0027]
In the present invention, assuming two patterns of monochrome recording and full-color recording, the print job corresponds to monochrome recording or full-color recording. In monochrome recording, the developing units 2Y and 2M of three colors of yellow, magenta, and cyan are used. The drive transmission to the input gears 25Y, 25M, and 25C for driving the 2C is cut off, and the drive is transmitted only to the input gear 25K of the black developing device K to reduce toner deterioration of three colors of yellow, magenta, and cyan. To prevent. In the case of full-color recording, drive is transmitted to the input gear 25 of the developing unit 2 for all colors to drive the developing unit 2 to form a full-color image.
[0028]
Specifically, first, the drive of the motor 7 is transmitted to the gear 70a, and then to the input gear 25K to the black developing unit 2K via the gear 70b and the output gear 72K on the apparatus main body side. Drive is always transmitted to the black developing unit 2K by the gear train A including the gears 70a and 70b, the output gear 72K, and the input gear 25K.
[0029]
A gear 70c is connected to the gear 70a to divide the driving force, and is connected to the electromagnetic clutch 71 and the gear 70d, and to the output gears 72C and 72M. Drive is transmitted from 72M to an output gear 72Y via a gear 70e. The output gears 72Y, 72M, and 72C are connected to input gears 25Y, 25M, and 25C for driving the developing units 2Y, 2M, and 2C for three colors of yellow, magenta, and cyan, respectively. Here, the electromagnetic clutch 71 is a means for driving connection or disconnection, and is provided in the middle of the gear train B for driving the three-color developing units 2Y, 2M, 2C. Driving can be connected and disconnected collectively.
[0030]
With this configuration, it is possible to arbitrarily connect or disconnect the drive to the developing units 2Y, 2M, and 2C other than the black developing unit 2K during monochrome recording and full-color recording. As described above, the drive of the input gear 25 to the developing unit 2 can be selected between monochrome recording and full-color recording with the inexpensive configuration, and the developing units 22 for each color can be arbitrarily operated.
[0031]
[Second embodiment]
A second embodiment of the image forming apparatus according to the present invention will be described. FIG. 2 is a diagram for explaining the configuration of the drive transmission means to the developing unit according to the second embodiment. Parts that are the same as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. .
[0032]
In the above-described first embodiment, the drive transmission of the developing units 2Y, 2M, and 2C for colors other than black is connected or disconnected. In the present embodiment, a connecting or disconnecting unit is arranged for each color, and the connection or disconnection is performed. It is possible to arbitrarily select a color to be processed.
[0033]
As shown in FIG. 2, a plurality of gears for transmitting driving are connected to a gear 70a connected to the motor 7, and electromagnetic clutches 71Y, 71M, 71C are respectively connected to output gears 72Y, 72M, 72C, 72K. , 71K. With this configuration, it is possible to arbitrarily connect or disconnect the developing unit 2 for each color. Therefore, for example, in the case of monocolor recording, the driving of the color cartridges other than the recording colors is cut off to reduce the deterioration of the toner of the unused color. Can be prevented.
[0034]
[Third embodiment]
A third embodiment of the image forming apparatus according to the present invention will be described. FIG. 3 is a diagram for explaining the configuration of the drive transmission means to the developing unit according to the third embodiment. Parts that are the same as those in the above-described embodiments are given the same reference numerals, and description thereof is omitted.
[0035]
In the first and second embodiments, an electromagnetic clutch has been described as a means for driving connection or disconnection. However, in the present embodiment, the drive connection or disconnection is performed by moving the gears apart.
[0036]
As shown in FIG. 3, in the present embodiment, the output gears 72Y ', 72M', 72C ', and 72K' on the apparatus main body side are rotatably supported by arms 78Y, 78M, 78C, and 78K, respectively. (Not shown) so as to be swingable. By swinging the output gear 72 ′ so that the output gear 72 ′ comes into contact with or separates from the input gear 25, it is possible to arbitrarily connect or disconnect each color to the developing unit 2.
[0037]
[Fourth embodiment]
A fourth embodiment of the image forming apparatus according to the present invention will be described. FIG. 4 is a diagram for explaining the connection state of the coupling, and FIG. 5 is a diagram for explaining the disconnection state of the coupling. Omitted.
[0038]
In the present embodiment, drive transmission from the apparatus main body to the developing unit 2 is performed by coupling the coupling 73 on the main body side and the coupling 26 on the developing unit 2 side instead of using the input gear 25. . That is, when the developing unit 2 that is detachable from the apparatus main body is mounted on the apparatus main body, the couplings 73 and 26 are coupled to transmit the drive.
[0039]
Here, as shown in FIG. 4, the apparatus main body is provided with a separation / contact means 74 for retracting the coupling 73, so that the coupling of the couplings 73 and 26 can be arbitrarily released with the developing unit 2 mounted. it can.
[0040]
The separation / contact means 74 can be realized, for example, by actuating a pair of cams having slopes with each other at the timing of driving connection or disconnection, and physically bringing the coupling 73 on the main body side into and out of contact in the axial direction. At this time, the separating / contacting means 74 can be operated by using an electromagnetic clutch, a solenoid, or a motor, and the connection / disconnection of the driving of each color to the developing unit 2 can be arbitrarily controlled.
[0041]
[Fifth embodiment]
A fifth embodiment of the image forming apparatus according to the present invention will be described. FIG. 6 is a diagram illustrating a configuration of a drive transmission unit to an image carrier according to a fifth embodiment, FIG. 7 is a diagram illustrating a connection state of a coupling, and FIG. 8 is a diagram illustrating a disconnection state of the coupling. In addition, the same reference numerals are given to the same portions as those in the above embodiments, and the description is omitted.
[0042]
In the above embodiments, the case where the drive is transmitted to the developing unit 2 has been described. However, the present invention can be similarly applied to a drive transmission unit that transmits the drive to the image carrier. Here, the image quality can be more effectively maintained by connecting or disconnecting the drive to the developing unit 2 at the same time as connecting or disconnecting the corresponding image carrier as described above.
[0043]
As shown in FIG. 6, in the present embodiment, since the image carriers 21 of four colors are driven by one motor 80, output gears 75 (75Y, 75M, 75C, 75K) corresponding to the image carriers 21 of each color. The drive is transmitted to the image carrier 21 by the gear train and the coupling 76 (76Y, 76M, 76C, 76K). The gear train is branched from the middle, and the drive train is transmitted to the output gear 75 of the image carrier 21 of each color.
[0044]
In the present invention, assuming two patterns of monochrome recording and full-color recording, the print job corresponds to monochrome recording or full-color recording. In monochrome recording, the image carriers 21Y of three colors of yellow, magenta, and cyan are used. The couplings 76Y, 76M, and 76C of the 21M and 21C are separated from each other, and connected only to the coupling 76K of the black image carrier 21K to transmit the drive, so that the image carrier 21 of three colors of yellow, magenta, and cyan is provided. Of the photosensitive layer is prevented from deteriorating. Further, in the case of full-color recording, the coupling 76 of the image carrier 21 of all colors is connected and transmitted to drive to form a full-color image.
[0045]
More specifically, as shown in FIGS. 7 and 8 (one of the couplings 27 corresponding to four colors is shown), when the drive transmission is performed by the coupling 27, the coupling 76 on the main body side is used. Can be arbitrarily cut off by retracting by the separating means 74 '. The separation / contact means 74 'can be realized, for example, by operating a pair of cams having inclined surfaces at the timing of driving connection or disconnection, and physically bringing the coupling 76 on the main body side into and out of contact in the axial direction. At this time, the separation / contact means 74 'can be operated by using an electromagnetic clutch, a solenoid, or a motor, and the connection or disconnection of the drive to or from the image carrier 21 of each color can be arbitrarily controlled.
[0046]
[Sixth embodiment]
A sixth embodiment of the image forming apparatus according to the present invention will be described. FIG. 9 is a diagram illustrating the configuration of a drive transmission unit to an image carrier according to a sixth embodiment. FIG. 10 is a perspective view illustrating the configuration of a main part of a gear train. The same reference numerals are given to the same parts and the description is omitted.
[0047]
In the fifth embodiment, the coupling 76 corresponding to the image carrier 21 of each color is provided with the separation / contact means 74 ′. However, in the present embodiment, the image carrier 21 of three colors of yellow, magenta, and cyan is provided. It is connected or disconnected by one means of drive transmission.
[0048]
As shown in FIG. 9, in the gear train for transmitting the drive to the image carrier 21, first, the gear train C for transmitting the drive train for the drive transmission to the output gear 75K of the black image carrier 21K, and the yellow , Magenta, and cyan are branched into a gear train D that transmits drive to output gears 75Y, 75M, and 75C of image carriers 21Y, 21M, and 21C. A means for driving connection or disconnection is arranged in a gear train D that branches from the branch to the input gears 25Y, 25M, and 25C of the yellow, magenta, and cyan color image carriers 21Y, 21M, and 21C. In this embodiment, an electromagnetic clutch 77 is disposed at a portion where the gear trains C and D are branched as a means for driving connection or disconnection.
[0049]
As shown in FIG. 10, the electromagnetic clutch 77 is configured by combining an idling gear 77a and a gear 77b. The idle gear 77a is connected to the gear train C, and the drive is input from the motor 80 via the gears 80a and 80b, and the drive is constantly transmitted to the output gear 75K of the black image carrier 21K.
[0050]
The gear 77b is connected to the output gear 75C of the gear train D, but is not connected to the gear 80b as a drive input, and does not transmit the drive to the gear train D when the electromagnetic clutch 77 is open. When the electromagnetic clutch 77 is held, the gear 77b rotates in synchronization with the gear 77a to transmit the drive to the gear train D, and the output gears of the yellow, magenta, and cyan image carriers 21Y, 21M, and 21C. 75Y, 75M, and 75C can be driven.
[0051]
Therefore, during monochrome recording and full-color recording, it is possible to arbitrarily connect or disconnect the driving of the image carriers 21Y, 21M, and 21C of colors other than the black image carrier 21K. As described above, the drive of the output gear 75 of the image carrier 21 can be selected between monochrome recording and full-color recording with an inexpensive configuration.
[0052]
[Seventh embodiment]
A seventh embodiment of the image forming apparatus according to the present invention will be described. FIG. 11 is a view for explaining the configuration of the drive transmitting means to the image carrier according to the seventh embodiment. Parts which are the same as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted. .
[0053]
In the fifth and sixth embodiments, the drive transmission of the image carriers 21Y, 21M, and 21C of colors other than black is collectively connected or disconnected, but the color to be connected or disconnected is arbitrarily selected. The electromagnetic clutch 77 may be arranged at an appropriate place. Also, as shown in FIG. 11, if four electromagnetic clutches 77 are arranged, each color can be arbitrarily connected or disconnected for driving, so that the driving of the image carrier 21 of a color other than the recording color is cut off, for example, in monocolor recording. Thus, the deterioration of the image carrier 21 can be prevented.
[0054]
[Eighth Embodiment]
An eighth embodiment of the image forming apparatus according to the present invention will be described. FIG. 12 is a configuration diagram of a main part of an image forming apparatus according to the eighth embodiment. Parts that are the same as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.
[0055]
In the fifth to eighth embodiments, the drive to the image carrier 21 is connected or disconnected. However, in consideration of protecting the intermediate transfer member 35, the intermediate transfer member 35 of the primary transfer roller 34 is further connected. It is desirable to release the bias on.
[0056]
As shown in FIG. 12, the primary transfer rollers 34Y, 34M, and 34C corresponding to the respective colors of yellow, magenta, and cyan are attached to separating means 39 such as a frame and are configured to be movable. Is configured to be able to be separated from and connected to. In the present embodiment, the black primary transfer roller 34K is always energized.
[0057]
When the drive of the image carrier 21 is arbitrarily cut off as described in each of the above-described embodiments (the configuration of the drive transmission means is not shown), the corresponding primary transfer roller 34 is simultaneously retracted, so that the image carrier is surely removed. 21 and the intermediate transfer member 35 can be brought into a non-contact state, and the surface of the image carrier 21 can be protected without being rubbed against the intermediate transfer member 35.
[0058]
[Ninth embodiment]
A ninth embodiment of the image forming apparatus according to the present invention will be described. FIG. 13 is a configuration diagram of a main part of an image forming apparatus according to the ninth embodiment. Parts that are the same as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.
[0059]
In the configuration described in the eighth embodiment, as shown in FIG. 13, the drive source of the separation unit 39 of the primary transfer roller 34 of each color and the drive source of the separation unit 74 ′ of the image carrier 21 are common. When driven by one motor 81 in this way, a simple and inexpensive configuration is obtained.
[0060]
Specifically, as described in the fifth embodiment (FIGS. 7 and 8), the drive transmission between the main body and the image carrier 21 is performed by the couplings 76 and 27, and the drive is connected by the separation / contact means 74 '. Or, it is assumed to be configured to be cut. In this case, when switching between full-color printing and mono-color printing, the output gears 75Y, 75M, and 75C of the image carriers 21Y, 21M, and 21C for the yellow, magenta, and cyan colors that are not used during mono-color printing are coupled with the couplings 76Y, 76M, and 75C. The separation / contact means 74'Y, 74'M, 74'C for retracting the 76C is constituted by one drive train, and the separation / contact means 74'K for retracting the coupling 76K of the output gear 75K of the black image carrier 21K. And split.
[0061]
On the other hand, among the primary transfer rollers 34 of each color, the black primary transfer roller 34K, which is always used in both mono / full-color recording, is fixed in the intermediate transfer unit 3, and the yellow, magenta, and cyan colors used only during full-color recording are used. The primary transfer rollers 34Y, 34M, and 34C are configured to be retractable. The primary transfer rollers 34Y, 34M, and 34C of the three colors are arranged on a frame 39b of the separating unit 39. The frame 39b is configured to be switchable between a contact position and a separation position, and a cam 39c is provided for switching to each position. Then, a drive train for rotating the cam 39c is provided, the drive train is branched from the coupling separating / contacting means 74'Y, 74'M, 74'C, and the drive is transmitted from the motor 81 which is the same drive source. ing.
[0062]
With such a configuration, the mode for mono / full-color recording can be switched at the same timing, and furthermore, since the same motor 81, that is, one drive transmission path is used, the control and device configuration Can be simplified.
[0063]
In this embodiment, the configuration is divided into black and other colors, but the color can be arbitrarily selected. In addition, in the case where a unit for driving connection or disconnection with the developing unit 2 is provided, in addition to the separation / contact unit 74 ′ of the coupling 76, a separation source for operating the connection or disconnection unit and retracting the primary transfer roller 34. The object of the present invention can be achieved by configuring the means 39 with one drive train and controlling with one drive source.
[0064]
Further, even during the image forming operation, if the operation timing of the cam 39c of the separation means 39 of the primary transfer roller 34 and the operation timing of the separation / contact means 74 'of the coupling 76 are shifted, first the primary transfer roller 34 Of the coupling 76, and then, after a lapse of a predetermined time, the separation / contact means 74 'of the coupling 76 can be operated, thereby achieving the object of the present invention.
[0065]
Further, the configuration described in each of the above embodiments is not limited to an image forming apparatus using an intermediate transfer member, and may be similarly applied to an image forming apparatus using a photosensitive belt and a transfer belt. Thus, the effects of the present invention can be obtained.
[0066]
【The invention's effect】
As described above, the image forming apparatus according to the present invention has a configuration in which drive is transmitted from one drive source to a plurality of developing units or image carriers, and selectively drives at least one developing unit or image carrier. Since the developing unit and the image carrier can be driven only when necessary by having a means for driving connection or disconnection, unnecessary stirring of the toner and idle rotation of the image carrier are prevented. It is possible to suppress the deterioration of the toner and the deterioration of the photosensitive layer of the image carrier, and it is possible to obtain a good output from the initial stage to the replacement of the cartridge. Further, toner scattering due to toner deterioration can be prevented.
[0067]
In addition, the provision of the separation / contact means for the transfer means prevents wear of the photosensitive layer of the image carrier and image defects due to static electricity due to friction, and also reduces transfer members such as an intermediate transfer member and a photosensitive belt. The protection can be achieved, and the durability of the device can be improved. Further, since the drive unit or the means for driving connection or disconnection to the developing unit or the image carrier is constituted by one drive transmission path, the contact and separation can be performed at the same timing with a simple configuration. It can be simplified.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a drive transmission unit to a developing unit according to a first embodiment.
FIG. 2 is a diagram illustrating a configuration of a drive transmission unit to a developing unit according to a second embodiment.
FIG. 3 is a diagram illustrating a configuration of a drive transmission unit to a developing unit according to a third embodiment.
FIG. 4 is a diagram illustrating a connection state of a coupling.
FIG. 5 is a diagram illustrating a disconnected state of the coupling.
FIG. 6 is a diagram illustrating a configuration of a drive transmission unit to an image carrier according to a fifth embodiment.
FIG. 7 is a diagram illustrating a connection state of a coupling.
FIG. 8 is a diagram illustrating a disconnected state of the coupling.
FIG. 9 is a diagram illustrating a configuration of a drive transmission unit to an image carrier according to a sixth embodiment.
FIG. 10 is a perspective view illustrating a configuration of a main part of a gear train.
FIG. 11 is a diagram illustrating a configuration of a drive transmission unit to an image carrier according to a seventh embodiment.
FIG. 12 is a main part configuration diagram of an image forming apparatus according to an eighth embodiment.
FIG. 13 is a main part configuration diagram of an image forming apparatus according to a ninth embodiment.
FIG. 14 is an explanatory diagram of an overall configuration of a color laser printer which is an embodiment of an image forming apparatus.
FIG. 15 is a diagram illustrating a drive transmission unit to a drive unit according to a conventional example.
FIG. 16 is a diagram illustrating a drive transmission unit to a drive unit according to another conventional example.
[Explanation of symbols]
T1 ... primary transfer unit
T2: Secondary transfer unit
P: Transfer material
1 ... Scanner section
2 Developing unit
3. Intermediate transfer unit
4… feed cassette
6 ... fixing unit
7 Motor
10. Laser
21 ... Image carrier
22 Developing device
23 ... charging means
24… container
25 ... input gear
26… Coupling
27… Coupling
31 ... drive roller
32: Secondary transfer facing roller
33 ... tension roller
34… Primary transfer roller
35… Intermediate transfer member
36… Guide rib
39 ... separation means
39a ... swinging fulcrum
39b ... frame
39c… Cam
41… Feed roller
44… Registration roller
50 ... fixing unit
51: Secondary transfer roller
52… Conveyer belt
53 ... discharge roller pair
54… Discharge roller pair
55 ... discharge roller pair
56 ... discharge tray
65 ... discharge section
70a ... gear
70b ... gear
70c ... gear
70d ... gear
70e ... gear
71 ... Electromagnetic clutch
72 ... output gear
73… Coupling
74 ... separating means
75 ... output gear
76… Coupling
77… Electromagnetic clutch
77a ... idling gear
77b ... gear
78 ... arm
79 ... Frame
80 ... motor
80a ... gear
80b ... gear
81… Motor
100 ... single motor
101 ... input gear

Claims (18)

A plurality of developing units having an image carrier and a developing unit for forming a toner image on the image carrier; a drive transmitting unit provided in an apparatus main body and transmitting drive to the plurality of developing units; and a drive to the developing unit. Means for connecting or disconnecting, wherein the image forming apparatus transmits drive from one drive source to the plurality of developing units,
An image forming apparatus comprising: means for selectively drivingly connecting or disconnecting at least one developing unit to the plurality of developing units. The image forming apparatus according to claim 1, wherein the drive transmitting unit that transmits the drive to the developing unit includes a gear train. 3. The image forming apparatus according to claim 2, wherein an electromagnetic clutch is provided in the middle of the gear train as means for driving connection or disconnection to the developing unit. The image forming apparatus according to claim 1, wherein the drive transmitting unit that transmits the drive to the developing unit is configured by a coupling. The image forming apparatus according to claim 4, further comprising a unit for connecting and disconnecting the coupling as a unit for driving connection or disconnection to the developing unit. A plurality of developing units each having an image carrier and a developing unit for forming a toner image on the image carrier; a drive transmitting unit provided in an apparatus main body for transmitting a drive to the plurality of image carriers; Means for driving connection or disconnection, and an image forming apparatus that transmits drive from one drive source to the plurality of image carriers,
An image forming apparatus comprising: means for selectively drivingly connecting or disconnecting at least one image carrier with respect to the plurality of image carriers. 7. The image forming apparatus according to claim 6, wherein the drive transmitting unit that transmits the drive to the image carrier is configured by a gear train. 8. The image forming apparatus according to claim 7, wherein an electromagnetic clutch is provided in the middle of the gear train as a means for driving connection to or disconnection from the image carrier. 7. The image forming apparatus according to claim 6, wherein the drive transmitting means for transmitting the drive to the image carrier is constituted by a coupling. The image forming apparatus according to claim 9, further comprising a means for connecting and disconnecting the coupling as a means for driving connection to or disconnection from the image carrier. A plurality of developing units each having an image carrier and a developing unit for forming a toner image on the image carrier; a drive transmitting unit provided in an apparatus main body for transmitting a drive to the plurality of image carriers; Means for driving connection or disconnection, and transmits drive from one drive source to the plurality of image carriers,
In an image forming apparatus having a plurality of transfer units respectively facing the plurality of image carriers and transferring a toner image from the image carrier to a second image carrier or a transfer material,
An image forming apparatus comprising: means for selectively driving connection or disconnection to at least one of the plurality of image carriers; and separating means for separating and transferring a corresponding transfer means. The image forming apparatus according to claim 11, wherein the drive transmitting unit that transmits the drive to the image carrier is configured by a coupling. 13. The image forming apparatus according to claim 12, further comprising: means for connecting or disconnecting the coupling as a means for driving connection to or disconnection from the image carrier. 14. The image forming apparatus according to claim 13, wherein a part of the plurality of coupling separation / contact means is operated by one drive transmission path. The image forming apparatus according to claim 11, further comprising a separation unit that separates the transfer unit. The image forming apparatus is characterized in that the transfer means of the transfer means is constituted by a cam. 12. The image forming apparatus according to claim 11, wherein a unit for driving connection or disconnection to the image carrier and a separating / contacting unit for the transfer unit are constituted by one drive transmission path. 12. The image forming apparatus according to claim 11, wherein the drive of the image carrier is cut off after a predetermined time has elapsed after the transfer unit has been retracted by the separation / contact unit.

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