JP2004013031A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable image carriers, intermediate transfer bodies, etc., which are different in service life, to be independently replaced with ease and to prevent unnecessary increase in running cost, even in the case of coping with demands for the miniaturization and speed increase of an image forming apparatus using the plurality of image carriers and the plurality of intermediate transfer bodies. <P>SOLUTION: The apparatus is formed from two separate units, one being a first unit 2 in which at least the plurality of photosensitive drums are mounted and the other a second unit 5 in which at least the plurality of intermediate transfer drums are mounted. The first unit 2 and the second unit 5 are freely connected to and separated from each other. Also, they are freely attached/detached to/from a main body 1. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile, and a multifunction machine that forms an image made of a toner using an electrophotographic method or an electrostatic recording method, and more particularly, to an image forming apparatus formed on a plurality of image carriers. The present invention relates to an image forming apparatus of a type in which a toner image to be transferred is finally transferred to a recording sheet after being transferred to an intermediate transfer member to form an image.
[0002]
[Prior art]
In this type of image forming apparatus, a plurality of image carriers including a photosensitive drum and the like are charged by a charging device, and an electrostatic latent image of each color component based on image information is formed on the charged image carrier. Each latent image is developed by a developer of a color component corresponding to the color component of the latent image supplied from the developing device, and is visualized into a toner image of each color. A color (multicolor) image is formed by transferring the multi-toner image transferred on the intermediate transfer member onto the recording paper and fixing the transferred multi-toner image on the recording sheet after transferring the image in such a state as to be superimposed on the transfer member. It has become.
[0003]
Such an image forming apparatus is capable of forming a single-color image without being described in detail, but is particularly advantageous in that a full-color image can be formed at a relatively high speed.
[0004]
On the other hand, in such an image forming apparatus using a plurality of image carriers and an intermediate transfer member, from the viewpoint of preventing the occurrence of color misregistration (image misregistration) when forming a color image, each image carrier is It is a major problem to realize the alignment of each toner image formed on the intermediate transfer member or the like. In order to solve such a problem, for example, the related parts including the plurality of image carriers and the intermediate transfer body, which affect the alignment, are fixed to a common support frame as much as possible, and the installation positions of the related parts are accurately determined. It is said that the means for positioning is effective.
[0005]
[Problems to be solved by the invention]
Incidentally, an image forming apparatus using such a plurality of image carriers and an intermediate transfer member has the following new problems.
[0006]
That is, in recent years, as the miniaturization and high-speed of the apparatus have progressed, the miniaturization and high-speed operation of various components constituting the apparatus have been more strongly required, and particularly, the image carrier, the intermediate transfer body, and the like In such driving parts, wear, deterioration and the like have been promoted, and a difference in life between the driving parts has become remarkable.
[0007]
For this reason, for example, when a configuration is adopted in which a plurality of image carriers and intermediate transfer members are fixed to a common support frame as described above, all the parts integrated by the support frame usually consume one waste. Even if only a certain component (for example, an image carrier) has reached the end of its life and another component (for example, an intermediate transfer member) has not yet reached its end of life, it will be handled as a component. The whole must be replaced with new parts, and there is a risk that running costs may be relatively high, especially when replacement of parts having a long remaining life has to be replaced.
[0008]
Incidentally, Japanese Patent Application Laid-Open No. 2001-134042 discloses an image forming apparatus having a plurality of photoconductors and an intermediate transfer member, for the purpose of miniaturization and high speed, prevention of image misregistration, improvement of maintainability, and the like. There has been proposed a configuration in which a plurality of photoconductors are supported by one or two supports to form a detachable integrated unit, and can be pulled out upward or obliquely upward with respect to the main body.
[0009]
However, in this image forming apparatus, when the photosensitive member reaches the end of its life, the replacement operation can be performed separately and independently from the replacement operation of the intermediate transfer member, but the belt-shaped intermediate transfer member is fixedly installed on the main body. Therefore, it is difficult to easily perform the replacement work especially when the life of the intermediate transfer member reaches the end of its life, and it is also difficult to greatly reduce the running cost due to the complexity of the replacement work. Further, when both the integrated unit of the plurality of photoconductors and the intermediate transfer body are exchanged, there is a possibility that a displacement occurs between the new integrated unit and the intermediate transfer body. Further, for the purpose of reducing manufacturing costs and reducing drive unevenness (synchronization deviation) due to different drive sources (drive motors and the like), the plurality of photoconductors and the intermediate transfer member are driven by one drive source. There is also a problem that it is relatively difficult to make such a configuration (unification of a driving source).
[0010]
The present invention has been made to solve such problems, and a main object of the present invention is to reduce the size and speed of an image forming apparatus using a plurality of image carriers and an intermediate transfer member. Even in the case of responding to the request, it is possible to easily and independently replace the image bearing member, the intermediate transfer member, etc., which have a large difference in service life, thereby preventing unnecessary increase in running cost. It is an object of the present invention to provide an image forming apparatus capable of performing the above.
[0011]
[Means for Solving the Problems]
An image forming apparatus according to the present invention includes a main body, a plurality of image carriers on which an electrostatic latent image is formed and a toner image is formed by developing the latent image, and the image carrier is formed on each of the image carriers. An intermediate transfer body that carries a toner image and conveys it to a position where the toner image is transferred onto a recording sheet; and an image forming apparatus having the image carrier and the intermediate transfer body, wherein a first unit having at least the plurality of image carriers is mounted. A second unit having at least the intermediate transfer member mounted thereon, wherein the first unit and the second unit have a structure which can be freely combined and separated and which can be detachably attached to an image forming position of the main body. It is characterized by being.
[0012]
According to such an image forming apparatus, since the first unit and the second unit are detachable at the image forming position of the main body, for example, when the life of the image carrier is different from the life of the intermediate transfer body, the life of the intermediate transfer body is reduced. When it is necessary to replace the reached image carrier or intermediate transfer body, the unit on which the image carrier or intermediate transfer body to be replaced is mounted can be removed from the image forming position of the main body. The operation of replacing the image carrier or the intermediate transfer member can be performed independently and individually. Incidentally, the structure of the first unit and the second unit which can be freely combined and separated can be relatively easily combined and separated, as long as the two units can be easily aligned. Is not particularly limited. Also, the configuration of the detachable structure of the two units with respect to the main body is not particularly limited as long as the detaching operation can be easily performed.
[0013]
Further, it is preferable that the first unit and the second unit have a structure that can be attached to and detached from the image forming position of the main body only when they are in a connected state. In this case, as compared with a case where the first unit and the second unit are separately attached to and detached from the image forming position of the main body in a state in which the first unit and the second unit are separated from each other, the attaching and detaching work can be easily performed. It is possible to suppress the occurrence of a displacement between the two units at the time of attachment and detachment.
[0014]
Further, it is preferable that the first unit and the second unit have a structure that can be separated only when the first unit and the second unit are detached from the image forming position of the main body. In this case, the same operation and effect as in the case of the preferred structure described above can be obtained, but in addition to this, both units in the main body are compared with a case where both units are separated by the main body. It is possible to suppress the occurrence of a positional shift between the two units, and it is possible to relatively easily realize a structure for attaching and detaching the two units and a structure for aligning the two units. When the unit is removed from the image forming position on the main unit, it means that the entire unit is completely extended to the outside of the main unit, and a part of both units remains inside the main unit. The separation operation itself includes possible states.
[0015]
Further, the first unit and the second unit may be configured to have a single-system power transmission mechanism in which rotational power is transmitted between the plurality of image carriers and the intermediate transfer body by being connected at the time of coupling. Good.
[0016]
In this case, as a single-system power transmission mechanism, for example, a gear train mechanism using a combination of a plurality of gears can be applied. The part of the power transmission mechanism that is connected when the two units are connected may be configured by appropriately arranging gears that mesh with each other in accordance with the connection operation of the two units. When such a single-system power transmission mechanism is adopted, by combining both units, the single-system power transmission mechanism is combined to form a unified power transmission path. Will be. Thereby, for example, the rotation operation of the image carrier on the first unit side and the rotation operation of the intermediate transfer body on the second unit side can be easily synchronized, so that the occurrence of image shift at the time of transfer can be prevented. Become. In addition, a configuration in which the image carrier and the intermediate transfer member of each unit are rotated by the same drive source, for example, as described later, can be easily adopted.
[0017]
Further, in the case where a single-system power transmission mechanism as described above is employed, when the first unit and the second unit are mounted on the main body, one of the image carrier and the intermediate transfer body is located on the side of the main body. It is preferable to connect to one installed driving source and to input a rotational power by the driving source.
[0018]
With such a configuration, the image carrier or the intermediate transfer member is connected to a drive source provided on the main body side when both units are mounted on the main body. Then, the rotational power of the drive source is input to one of the connected image carrier or intermediate transfer member, and transmitted to the other intermediate transfer member or image carrier via the power transmission mechanism of the same system. Become so. This makes it easier to synchronize the rotation operation of the image carrier and the rotation operation of the intermediate transfer body, compared to a configuration in which the image carrier and the intermediate transfer body of both units are driven by individual driving sources. It is possible to prevent the occurrence of image shift during transfer. In addition, it is possible to reduce the manufacturing cost and the power consumption, such as reducing the installation space for the driving source.
[0019]
Here, the image carrier is usually in the form of a drum such as a photosensitive drum, but may be in the form of a belt. Further, the intermediate transfer member may be in a belt form or a drum form. In particular, in the present invention, when an intermediate transfer member using a plurality of drum-shaped transfer members is employed, the operation of replacing the plurality of intermediate transfer members can be performed separately and independently of the operation of replacing the image carrier. It is effective. The main body is a structure including a support frame and the like for supporting and fixing components such as an image carrier and an intermediate transfer member, and usually has a form having an internal space for disposing the components and the like. It becomes.
[0020]
The first unit mounts at least a plurality of image carriers on one or a plurality of common support members. If necessary, components (e.g., a charging device) disposed close to the periphery of the image carrier ) May be mounted together. The same applies to one second unit, in which at least the intermediate transfer member is mounted on one or more common support members. However, if necessary, other related components are also mounted together. You may comprise.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
1 and 2 show a color printer according to a first embodiment of the present invention. FIG. 1 is an internal schematic diagram of the color printer as viewed from the front side, and FIG. 2 is a configuration of a main part of FIG. FIG.
[0022]
<Overall configuration of printer>
This color printer is a so-called tandem type printer in which image forming engines are arranged in parallel for each color of yellow (Y), magenta (M), black (K) and cyan (C). And a full-color image composed of the four color toner images.
[0023]
In this printer, an image transfer drum unit 5, a paper feed unit 6, a fixing unit 7, and the like, including a photosensitive drum unit 2, an exposure unit 3, and a developing unit 4, which constitute an image forming engine, are provided in an internal space of a housing 1. They are arranged in a positional relationship as shown in FIG. The housing 1 is a three-dimensional structure formed by assembling, for example, a box using components such as a support frame, a support plate, and an exterior cover, but FIG. The illustration of the constituent parts such as the support frame, the support plate, and the like serving as the skeleton portion is omitted. The solid arrows in FIG. 2 indicate the rotation direction of each component.
[0024]
Further, in this printer, as shown in FIG. 3, the photosensitive drum unit 2 and the image transfer unit 5 have a structure that can be connected and separated from each other, and have a structure that is detachable from the image forming position of the housing 1. ing. The combined units 2 and 5 are stored and mounted in a predetermined mounting space 1S formed inside the housing 1. FIG. 3 does not show some of the components such as the paper feed unit 6 and the fixing unit 7.
[0025]
As shown in FIGS. 2 to 4 and the like, the photosensitive drum unit 2 is configured such that the toner images of the four colors (Y, M, K, C) are exclusively formed on a support frame 10 assembled in a rectangular frame shape. And a charging roll 12 for charging the peripheral surface of each of the photosensitive drums 11 (Y, M, K, C) to a predetermined background potential, and a peripheral surface of each of the photosensitive drums 11 (Y, M, K, C). The brush roller 13 for temporarily holding the toner and the like remaining on the surface is temporarily rotatably mounted and integrated. The photosensitive drum unit 2 is detachably attached to and integrated with the image transfer drum unit 5 as described later.
[0026]
Each of the photosensitive drums 11 (Y, M, K, and C) has a structure in which a cylindrical drum main body having the same outer diameter and on which a photosensitive layer made of an organic photosensitive material or the like is formed is supported by a rotating shaft 14. It is. These photosensitive drums 11 are mounted via bearings in such a manner that the respective rotating shafts 14 are parallel to the side plates 10A, 10B of the support frame 10 at predetermined intervals in the vertical direction.
[0027]
When the photosensitive drum unit 2 is coupled to the image transfer drum unit 5, a shaft end portion 14 a on the printer front side of the rotation support shaft 14 of the photosensitive drum 11 is connected to a shaft locking plate (described later) formed on the transfer drum unit 5 side. 6 and 8, the support frame 10 is attached to the front side plate portion of the support frame 10 so as to slightly protrude outside (front side) thereof. Further, an end portion 14b of the rotary support shaft 14 on the printer rear side is locked by a shaft locking plate (38) formed on the image transfer drum unit 5 side as described later, and a rear support plate of the housing 1 is provided. In order to be inserted into a positioning shaft hole (not shown) formed in the supporting frame 10, the supporting frame 10 is attached to the rear side plate portion of the supporting frame 10 so as to protrude outside (rear side) for a long time.
[0028]
The charging roll 12 is formed by coating a conductive elastic foam to a predetermined thickness around a metal roll body 15, and the elastic foam layer is provided on the upstream side of the photosensitive drum 11 in the rotation direction. The rotating shafts at both ends of the roll body 15 are rotatably attached to the side plate portions of the support frame 10 via bearings so as to abut against the surface portion of the roll body 15. In addition, the charging roll 12 is configured such that a DC voltage as a charging voltage is applied to the roll body 15 to generate a discharge in a minute gap between the elastic foam layer and the peripheral surface of the photosensitive drum 11. The peripheral surface of the photosensitive drum 11 is charged. The brush roll 13 for temporarily holding toner is provided with a plurality of brush bristles provided in a standing state around a metal roll body so as to have a predetermined distribution density, and rotating shafts at both ends of the roll body are provided. Are rotatably attached to the side plate portion of the support frame 10.
[0029]
Further, in the photosensitive drum unit 2, as shown in FIGS. 4B and 5, the same transmitted gear 16 is fixedly attached to the rotating shaft 14b on the rear side of each photosensitive drum 11 (Y, M, K, C). Have been. A transmission gear is fixedly attached to each rotation shaft 13 a on the front side of the charging roll 12 and the temporary toner holding roll 13, and each transmission gear is connected to the rotation shaft 14 on the front side of the photosensitive drum 11. And the transmission gear 18 fixed to the transmission gear 18. As a result, the charging roll 12 and the temporary toner holding roll 13 rotate at the same speed or almost the same speed as the photosensitive drum 11.
[0030]
As shown in FIGS. 2 and 3 and FIGS. 6 and 7, the image transfer drum unit 5 includes two first intermediate transfer drums 21 and 22 and one second transfer frame on a support frame 20 assembled in a rectangular frame shape. An intermediate transfer drum 23, a brush roller 24 for temporarily holding toner and the like that temporarily adhere to the peripheral surfaces of the respective intermediate transfer drums 21, 22, and 23; and respective intermediate transfer drums 21 and 22 , 23 are rotatable either directly or with the collection roll 25 that collects the toner held on the temporary toner holding brush roll 27 after returning to the circumferential surface of each drum. It is attached and integrated.
[0031]
Each of the first and second intermediate transfer drums 21 and 22 and the second intermediate transfer drum 23 is made of a metal pipe of the same outer diameter made of iron, aluminum, or the like, and made of conductive silicone rubber or the like having a low thickness of about 0.1 to 10 mm. Resistance elastic layer (resistance value: 10 ² -10 ³ Ω), and furthermore, on the surface of the low resistance elastic layer, a high release layer of 3 to 100 μm made of fluoro rubber or the like (resistance value: 10 ⁵ -10 ¹³ (Approximately Ω) is formed on the rotating shafts 26, 27, and 28 to support the drum body. These intermediate transfer drums 21 to 23 are rotated via bearings in such a state that the respective rotation support shafts 26 to 28 are parallel to the side plates 20A and 20B of the support frame 20 at predetermined intervals in the vertical direction. Mounted as possible.
[0032]
The first intermediate transfer drums 21 and 22 rotate while the peripheral surface of the transfer drum 21 contacts the photosensitive drum 11Y and the photosensitive drum 11M at the same time, while the peripheral surface of the transfer drum 22 contacts the photosensitive drum 11K and the photosensitive drum 11C. The rotation shafts 26 and 27 of the transfer drums 21 and 22 are attached to the side plate portions 20A and 20B of the support frame 20 at predetermined intervals in the vertical direction so that the transfer drums 21 and 22 rotate simultaneously. Have been. Further, the second intermediate transfer drum 23 has a positional relationship such that the peripheral surface thereof simultaneously contacts the first intermediate transfer drums 21 and 22 and rotates, and the rotation shaft 28 is attached to the side plate portions 20A and 20B of the support frame 20. Installed. Further, when the second intermediate transfer drum 23 is mounted on the housing 1, the second intermediate transfer drum 23 comes into contact with the final transfer roll 50 installed on the housing 1 side (see FIGS. 1 and 2).
[0033]
In order to electrostatically and primarily transfer the toner images on the photosensitive drums 11 to the first intermediate transfer drums 21 and 22, respectively, the surface potential of the drum main body is set to a predetermined potential (for example, +250 to +250). A first transfer bias for keeping the voltage at about 500 V) is applied from a bias power supply (not shown) via its rotation shafts 24 and 25. In addition, the surface potential of the drum main body is set to a predetermined potential (for example, +600) on the second intermediate transfer drum 23 in order to electrostatically secondary transfer the toner images on the transfer drums 21 and 22 to the drum. (To about 1200 V) is applied from a bias power source (not shown) via a rotating shaft 26 thereof.
[0034]
The temporary toner holding brush roll 24 has the same configuration as the temporary toner holding brush roll 13 used in the photosensitive drum unit 2, and is attached so as to rotate while being in contact with each of the intermediate transfer drums 21 to 23. ing. The collection roll 28 is a metal roll that rotates in contact with each of the intermediate transfer drums 21 to 23, and is applied with a bias voltage that can electrostatically attract unnecessary toner on each of the drums 21 to 23. Bias roller, a cleaning blade that abuts against the roll, and scrapes the toner adsorbed and collected by the bias roll, and a transport (not shown) that transports and sends the toner scraped by the blade to a collection box (not shown). And auger.
[0035]
In the image transfer drum unit 5, as shown in FIGS. 6 and 7, the same transmission gear 29 is fixedly attached to the rotation shafts 26b, 27b and 28b on the rear side of each of the intermediate transfer drums 21 to 23. The transmission gears 29 of the first intermediate transfer drums 21 and 22 are meshed with and connected to the transmission gear 29 of the second intermediate transfer drum. When any one of the three intermediate transfer drums 21 to 23 is rotated by employing such a power transmission mechanism of the gear system, the remaining intermediate transfer drums are also rotated via the transmission gear 29 to the respective intermediate transfer drums. In the same direction and at the same peripheral speed. Further, the transmission gear 29 of the first intermediate transfer drum 21 is engaged with and coupled to the transmission gears 14Y, 14M of the photosensitive drums 11Y, 11M at the same time when the first intermediate transfer drum 21 is coupled to the photosensitive drum unit 2. The transmitted gear 29 is set so that it can be engaged and connected simultaneously with the transmitted gears 14K, 14C of the photosensitive drums 11K, 11C (see FIG. 9).
[0036]
A transmission gear is fixedly attached to each rotary shaft on the front side of the temporary toner holding brush roll 24 and the collection roller 25, and each transmission gear is connected to the front side of each of the intermediate transfer drums 21 to 23. And the transmission gear 32 fixed to the rotating shafts 26a, 27a, 28a. As a result, the brush roll 24 and the collection roll 25 rotate at the same or almost the same speed as the respective intermediate transfer drums 21 to 23. Further, when the transfer drum unit 5 is mounted on the housing 1, the driving force of a drive motor (not shown) installed on the housing 1 is attached to the rotation shaft end 28 b on the rear side of the second intermediate transfer drum 23. The transmission gear 31 that meshes with the drive gear 51 to which the power is transmitted is fixedly mounted.
[0037]
The image transfer drum unit 5 is detachably attached to a front side surface portion of the housing 1 by a slide rail member 35 as shown in FIGS. In this example, the transfer drum unit 5 is held by a pair of upper and lower slide rail members 35A, 35B at the upper plate and the lower plate of the support frame 20, and is moved rearward by the slide movement function of the slide rail members 35A, 35B. While being pushed in and mounted inside the housing 1, it is pulled out to the front side by the sliding movement function and detached from the housing 1. The operation of pushing and pulling out the transfer drum unit 5 is performed by an operator grasping and using the lever 37 attached to the second side surface portion 20C on the front side of the support frame. The image transfer drum unit 5 has a structure that can be removed from the slide rail members 35A and 35B after being pulled out from the inside of the housing 1. Further, when the transfer drum unit 5 is mounted on the housing 1, it is inserted into a positioning hole formed in a rear frame plate (not shown) of the housing 1 and positioned on the rear side plate 20 </ b> B of the support frame. A plurality of positioning pins are formed so as to protrude.
[0038]
Further, the image transfer drum unit 5 has side plates 20A and 20B of the support frame 20 as shown in FIGS. 6 and 8 in order to enable the transfer drum 5 and the photosensitive drum unit 2 to be easily coupled and separated. Are provided with shaft locking plates 38A and 38B for locking and supporting the front and rear rotating shaft ends 14a and 14b of the photosensitive drums 11 of the photosensitive drum unit 2 at the time of coupling. The shaft locking plates 38A and 38B are capable of inserting the respective rotary shaft ends 14a and 14b from obliquely above and pulling them out obliquely upward. Further, each of the photosensitive drums 11 is a predetermined first intermediate transfer drum 21. , 22 are formed so that they can be supported and fixed at a predetermined position such that they can be supported and fixed at a predetermined position. It is formed so as to protrude to the two sides. In FIG. 6a, a part of the shaft locking plate 38A on the front side is not shown for convenience.
[0039]
The exposure unit 3 is for writing an electrostatic latent image on each of the photosensitive drums 11 of the photosensitive drum unit 2, and is based on a light source such as a semiconductor laser (not shown) inside the unit housing and image information from the light source. An optical system component such as a polygon mirror, a reflecting mirror, various lenses, and the like for guiding the light beam Bm emitted from the light source onto the corresponding photosensitive drum 11 for scanning exposure is appropriately arranged. The exposure unit 2 scans and exposes the light beam Bm onto each of the photosensitive drums 11 through the gap of the developing unit 4, thereby forming an electrostatic latent image having a predetermined surface potential on each of the photosensitive drums 11. It has become.
[0040]
As shown in FIG. 1, the developing unit 4 is provided with a unit frame 40 disposed at a position near the photosensitive drum unit 20 inside the housing 10, and the frame 40 faces each photosensitive drum 11 of the photosensitive drum unit 20. The main part is constituted by the four developing devices 41 arranged in an appropriate state. Each of the developing devices 41 employs a so-called magnetic brush developing method, and contains a two-component developer containing a toner and a carrier inside the device. Each of the developing devices 41 includes a developing roller 42 that rotates in close proximity to the photosensitive drum 11 at a predetermined minute interval, and the developer forms a magnetic brush on the developing roller 42. The photosensitive drum 11 is rubbed with the rotation of. Further, a developing bias voltage in which a DC component is superimposed on an AC component is applied to the developing roll 42, thereby causing toner to electrostatically adhere only to the electrostatic latent image (image portion) of the photosensitive drum 11. Thus, a toner image is formed.
[0041]
Further, in the developing unit 4, each developing device 41 is supported so as to be able to advance and retreat with respect to the unit frame 40 so as to retreat to a non-developing position slightly away from a developing position which is close to and opposed to the photosensitive drum 11. That is, each developing device 41 is displaced in a direction indicated by a double-headed arrow in FIG. The non-development position is a position that does not hinder slide movement when the photosensitive drum unit 2 and the image transfer drum unit 5 are attached and detached. Each developing device 41 is replenished with toner from a toner cartridge 49 (Y, M, K, C) (FIG. 1) containing toner of the four colors by a toner replenishing and conveying device (not shown) as necessary. It is supposed to be.
[0042]
The paper feed unit 6 includes a paper feed tray 60 that stores a plurality of recording papers P in a stacked state, and a delivery mechanism 61 that sends out the recording papers P from the paper supply tray 60 one by one. The recording paper P sent out from the paper supply unit 6 is transported and supplied at predetermined timing between the second intermediate transfer roll 23 and the final transfer roll 50 of the image transfer drum unit 5 through a pair of paper transport rolls 65, a pair of registration rolls 66, and the like. Is done. The dashed-dotted line in FIG. 1 is a paper transport path for the recording paper P. The paper transport path is formed by appropriately arranging a plurality of paper transport rolls 66 and 67, a registration roll 68, a paper transport guide (not shown), and the like.
[0043]
The fixing unit 40 mainly includes a unit frame, a heating roll 71 having a built-in heating lamp, a pressure roll 72 pressed against the heating roll 71, and a paper discharge roll 73. In the drawing, reference numeral 1a denotes a paper discharge unit having an inclined curved surface for accommodating the recording paper P discharged from the inside of the housing 1 after fixing.
[0044]
<Combining and mounting the photosensitive drum unit and image transfer unit>
When the color printer is used, the photosensitive drum unit 2 and the image transfer drum unit 5 are combined and integrated, as shown in FIG. Of the housing 1 (in the installation space 1S), and attached to a predetermined portion of the housing 1 as shown in FIG.
[0045]
As shown in FIG. 8, the photosensitive drum unit 2 is coupled to the image transfer drum unit 5 by connecting the rotating shaft ends 14a, 14b of the photosensitive drums 11 in the photosensitive drum unit 2 to the respective shaft locking plates 38A, 38B in the transfer drum unit 5. This is performed by inserting and supporting the locking grooves 39 respectively. In particular, in this example, the photosensitive drum unit 2 is coupled to the image transfer drum unit 5 as if the photosensitive drum unit 2 was hooked through the shaft locking plates 38A and 38B.
[0046]
By such coupling, each photosensitive drum 11 is held in a state of being in contact with the first intermediate transfer drums 21 and 22, respectively, as shown in FIG. Further, as shown in FIG. 9, the transmitted gear 16 of each photosensitive drum 11 is held in a state of being engaged with and coupled to the transmitted gear 29 of the first intermediate transfer drums 21 and 22, so that a gear train mechanism of the same system is used. It is formed. A stopper mechanism is provided for the rotation shaft end 14 of each photosensitive drum 11 supported by being inserted into the locking groove 39 of each of the shaft locking plates 38A and 38B so as not to come out of the locking groove 39 at the time of coupling. Good to put. With the above-described connection, the photosensitive drum unit 2 is in a state where the photosensitive drum unit 2 is basically positioned with respect to the image transfer drum unit 5.
[0047]
Further, the photosensitive drum unit 2 and the image transfer drum unit 5 can be stored and mounted in the mounting space 1S of the housing 1 only when in the coupled state as described above. Therefore, for example, the image transfer drum unit 5 cannot be pushed into the mounting space 1S of the housing 1 and the photosensitive drum unit 2 cannot be coupled to the transfer drum unit 5 in the pushed state.
[0048]
At this time, the rear rotation shaft end 14b of each photosensitive drum 11 in the photosensitive drum unit 2 is inserted into the positioning shaft hole of the rear support plate of the housing 1 and positioned. In addition, positioning pins formed on the rear side plate of the support frame 20 of the transfer drum unit 5 are inserted into positioning holes of the rear side support plate of the housing 1 and positioned. On the other hand, in the transfer drum unit 5, the front side plate portion of the support plate 20 is finally positioned with respect to the housing 1. The positioning of the front side plate portion with respect to the housing 1 can be realized by fixing a positioning member to a predetermined portion of the housing 1 by, for example, rotating the lever 37. Further, the transmitted gear 29 relating to the second intermediate transfer drum 23 of the transfer drum unit 5 is meshed with and connected to the drive gear 51 on the housing 1 side. Finally, when this mounting is completed, a front opening / closing cover (not shown) attached to the front side of the housing 1 is closed.
[0049]
<Color image printing operation>
Printing of a full-color image by this color printer is generally performed as follows.
[0050]
First, after the four photosensitive drums 11 are uniformly charged by the charging rolls 12 in the photosensitive drum unit 2, the surfaces of the charged photosensitive drums 11 correspond to the respective colors of Y, M, K, and C from the exposure unit 3. The respective laser beam lights Bm are separately irradiated, and an electrostatic latent image of each color is formed according to input information to the printer. Next, the electrostatic latent images on the respective photosensitive drums 11 are respectively developed by the developing devices 14 of the respective colors of the developing unit 4, and are visualized as toner images of respective colors of Y, M, K, and C.
[0051]
Subsequently, the toner images of the respective colors formed on the respective photosensitive drums 11 are primarily transferred electrostatically onto the first intermediate transfer drums 21 and 22. That is, the yellow and magenta toner images formed on the photosensitive drums 11Y and 11M are arranged on the first intermediate transfer drum 21 in the order of magenta and yellow, and the black and cyan toner images formed on the photosensitive drums 11K and 11C are cyan. , Black on the first intermediate transfer drum 22 so as to be superimposed on each other. As a result, a multiplex toner image composed of a magenta toner image and a yellow toner image is formed on the first intermediate transfer drum 21, while a cyan toner image and a black toner image are formed on the first intermediate transfer drum 22. A multi-toner image is formed.
[0052]
Subsequently, each of the multiple toner images formed on the first intermediate transfer drums 21 and 22 is secondarily electrostatically transferred onto the secondary intermediate transfer drum 23. Thus, the toner images (M, Y from the lower layer side) on the first intermediate transfer drum 21 and the toner images (C, K from the lower layer side) on the first intermediate transfer drum 22 are formed on the secondary intermediate transfer drum 23. Are transferred in this order to form a multi-toner image as superimposed in the order of Y, M, K, C from the lower layer side. Next, the multicolor toner image of the four colors is conveyed toward a final transfer portion that is in pressure contact with the final transfer roll 50 as the second intermediate transfer drum 23 rotates.
[0053]
The recording paper P is supplied from the paper supply unit 6 at a predetermined timing toward the final transfer section in accordance with the formation of such a toner image. That is, only one recording sheet P stored in the storage tray 31 is sent out to the sheet conveyance path by the sheet feeding device 32 and temporarily stopped by the registration roller 36, and then the final transfer unit is controlled by the registration roller 36 at a predetermined timing. Sent to. Thus, the toner images of the four colors (Y, M, K, C) on the secondary intermediate transfer drum 23 are sent to a final transfer section which is a press-contact portion between the secondary intermediate transfer drum 23 and the final transfer roll 24. The recording paper P is electrostatically and collectively transferred while being pressed.
[0054]
Next, the recording paper P on which the four color toner images have been transferred is sent to the fixing unit 7 and is heated and pressed by passing through a fixing nip portion between the heating roll 71 and the pressure roll 72 of the fixing unit 7. After the fixing process is performed, the sheet is discharged to the sheet discharge unit 1a. By performing a series of image forming processes as described above, a full-color image is formed on one recording sheet P.
[0055]
In this printer, as shown in FIG. 10, the rotational power from one drive source is transmitted from the drive gear 51 to the second intermediate transfer drum 23 of the image transfer drum unit 5 via the transmitted gear 31. (2) When the intermediate transfer drum 23 rotates, power is transmitted to the first intermediate transfer drums 21 and 22 via the transmission gear 29, and the intermediate transfer drums 21 and 22 rotate. Then, when the first intermediate transfer drums 21 and 22 rotate, power is transmitted to the respective photosensitive drums 11 via the transmitted gear 16 meshing with the transmitted gear 29, and the respective photosensitive drums 11 rotate.
[0056]
As described above, since the rotational power is transmitted to the plurality of intermediate transfer drums 21 to 23 and the plurality of photosensitive drums 11 by the same gear train mechanism, the rotation of the intermediate transfer drum and the rotation of the photosensitive drum are synchronized. (In this example, it is easy to synchronize the rotation operations of the plurality of intermediate transfer drums). In addition, since the intermediate transfer drum and the photosensitive drum are rotationally driven by the rotational power from one drive motor, the above-described synchronization can be easily achieved, as well as a plurality of drive motors and a power transmission mechanism. As compared with the case of adopting the above, space saving and cost reduction for installing the driving motors and the like can be achieved. As a result, it is easy to prevent the occurrence of transfer deviation during transfer from the photosensitive drum to the first intermediate transfer drum and the occurrence of transfer deviation during transfer from the first intermediate drum to the second intermediate transfer drum. Therefore, when printing a color image formed by superimposing a plurality of toner images such as the above-described full-color image, a high-quality color image in which color misregistration (image misregistration) due to transfer misregistration is unlikely to occur. Obtainable.
[0057]
<Replacement of consumable parts>
In this color printer, for example, the photosensitive drum 11 in the photosensitive drum unit 2 has a life target of 50,000 indices of the number of prints, and the first and second intermediate transfer drums in the image transfer drum unit 5 are used. When a life target of 100,000 sheets is used as the print target index as 21 to 23, a general printing operation is executed, and the photosensitive drum 11 as a consumable part is replaced with the intermediate transfer drum 21 as a consumable part. , The life of the intermediate transfer drums 21 to 23 has not yet reached. Such a life is detected by cumulatively counting the number of prints.
[0058]
In this case, it is necessary to replace only the photosensitive drum 11 which has reached the end of its life. However, this printer can replace only the photosensitive drum 11 independently of the intermediate transfer drum as described below.
[0059]
First, after the combined photosensitive drum unit 2 and image transfer drum unit 5 are pulled out from the inside of the housing 1 while being supported by the slide rail member 35, the photosensitive drum unit 2 is pulled up obliquely upward, as shown in FIG. As a result of the rotation shaft ends 14a and 14b of the photosensitive drum 11 being pulled out from the locking grooves 39 of the shaft locking plates 38A and 38B in the transfer drum unit 5, the photosensitive drum unit 2 is separated from the transfer drum unit 5 as shown in FIG. Removed. Thus, the removed old photosensitive drum unit 2 can be replaced with a new photosensitive drum unit. Then, the new photosensitive drum unit (2) is connected to the transfer drum unit 5 as described above, and is stored and mounted in the housing 1, so that the use of the printer can be resumed.
[0060]
After that, when only the intermediate transfer drums 21 to 23 have reached the end of their life (at this time, the photosensitive drum 11 has not reached the end of its life), the combined photosensitive drum unit 2 and image transfer drum 5 Then, the photosensitive drum unit 2 may be removed from the transfer drum unit 5 after being pulled out of the transfer drum unit 5. Thus, the old transfer drum unit 5 can be removed from the slide rail member 37, and can be replaced with a new transfer drum unit (5).
[0061]
As described above, in this color printer, the photosensitive drum and the intermediate transfer drum having different lifespans are used, and even if one of them has reached the lifespan, the photosensitive drum unit 2 having at least the photosensitive drum unit 11 and the intermediate transfer drum are used. It is possible to easily and independently replace only the transfer drum unit 5 which has at least the transfer drum and which has reached the end of its life. In addition, components that have not reached the end of their life do not have to be replaced at the same time as components that have reached their end of life, so that unnecessary increases in running costs can be suppressed.
[0062]
Incidentally, in the above-described example, a method of replacing the photosensitive drum unit 2 or the entire image transfer drum unit 5 of the photosensitive drum or the intermediate transfer drum which has reached the end of its life with a new one has been described. Only the drum 11 and the intermediate transfer drum 21 may be replaced with new ones.
[0063]
[Embodiment 2]
FIG. 11 is a configuration diagram showing a main part of a color printer according to Embodiment 2 of the present invention. This color printer is mainly implemented by applying an image transfer belt unit 8 in place of the image transfer drum unit 5 in the first embodiment, and making minor changes in the components accompanying the application of the unit 8. It has substantially the same configuration as the color printer according to the first embodiment. Among the components of the printer, the same reference numerals are given to components and the like that are common in terms of functions and the like to the components in the first embodiment.
[0064]
The image transfer belt unit 8 is configured such that at least two belt support rolls 81 and 82 are rotatably mounted on a unit support plate 80 and formed on each of the photosensitive drums 11 of the photosensitive drum unit 2 on the belt support rolls 81 and 82. The intermediate transfer belt 83 for transferring the toner image to be transferred is stretched and attached. In this example, the final transfer roll 50 is disposed so as to abut on the outer peripheral surface of the intermediate transfer belt 83 laid on the belt support roll 82 disposed on the lower side. The transfer belt unit 8 is provided with a transfer device for electrostatically transferring the toner image on the photosensitive drum to the unit support frame 80 at a primary transfer position facing each photosensitive drum 11 as necessary. You may. A conventionally known intermediate transfer belt 83 is used.
[0065]
In this color printer, the image transfer belt unit 8 is detachably attached to a casing (not shown) (see FIGS. 1 and 3) via a slide rail member (35). The photosensitive drum unit 2 is attached to such a transfer belt unit 8 via a shaft engaging plate 38 (see FIGS. 6 and 8) in a manner similar to that of the first embodiment so as to be separable.
[0066]
As shown in FIGS. 12 and 13, the photosensitive drum unit 2 has a rotary shaft 14b on the rear side of each photosensitive drum 11 (Y, M, C, K) due to the use of the image transfer belt unit 8. A fixed two-stage gear (a gear in which a large-diameter gear and a small-diameter gear are coaxially arranged) 16 is fixedly mounted on the supporting frame 10, and the small-diameter gear of each of the transmitted gears 16 is attached to the support frame 10. They are connected to one another via the same intermediate transmission gear 19 rotatably mounted. Thus, when one of the photosensitive drums 11 rotates, the other photosensitive drums 11 also rotate at the same speed in the same direction. When the transmission gear 16 (C) for the lowermost photosensitive drum 11 </ b> C is mounted on the housing 1 after coupling with the transfer belt unit 8, the transmission gear 16 (C) is installed on the housing 1 side (not shown). It is designed to mesh with a driving gear 51 to which a driving force from a driving motor is transmitted.
[0067]
On the other hand, in the image transfer belt unit 8, as shown in FIGS. 12 and 13, the same transmitted gear 86 is fixed to the rear end portion 85 b of each rotation shaft 85 of the belt support rolls 81 and 82, respectively. Installed. When the image transfer belt unit 8 and the photosensitive drum unit 2 are coupled to each other, the transmitted gear 86 attached to each of the rotating shaft ends 85b serves to rotate the rotating shafts of the uppermost photosensitive drum 11K and the lowermost photosensitive drum 11Y. The transmission gears 16 (K) and 16 (Y) attached to the rear end 14b are meshed and connected to each other.
[0068]
<Combining and mounting the photosensitive drum unit and image transfer unit>
In such a color printer, as shown in FIG. 11, the photosensitive drum unit 2 and the image transfer belt unit 8 are combined and integrated, and then the two units 2 and 8 are supported inside a housing 1 by a slide rail member. (Inside the installation space 1S shown in FIG. 3 and the like) and used after being pushed into the housing 1 by being pushed.
[0069]
The coupling of the photosensitive drum unit 2 to the image transfer belt unit 8 is similar to the coupling of the photosensitive drum unit 2 and the image transfer drum unit 5 in the first embodiment, and the rotation shaft ends 14a and 14b of each photosensitive drum 11 are transferred. This is performed by inserting and supporting each of the shaft locking plates (38) of the belt unit 8 in the locking grooves. By such coupling, each photosensitive drum 11 is held in a state of being in contact with the intermediate transfer belt 83, as shown in FIG. Further, as shown in FIG. 12, the transmitted gear 16 of each photosensitive drum 11 is held in a state of being engaged with and coupled to the transmitted gear 86 of the belt support rolls 81 and 82 to form a gear train mechanism of the same system. You. By the above coupling, the photosensitive drum unit 2 is in a state where the photosensitive drum unit 2 is basically positioned with respect to the image transfer belt unit 8.
[0070]
Also, the photosensitive drum unit 2 and the image transfer belt unit 8 can be stored and mounted in the mounting space of the housing 1 only when they are connected as described above, as in the first embodiment. It has become. Therefore, for example, the image transfer belt unit 8 cannot be pushed into the mounting space of the housing 1 first, and the photosensitive drum unit 2 cannot be connected to the transfer belt unit 8 in the pushed state. Note that the photosensitive drum unit 2 and the image transfer belt unit 8 stored in the housing are positioned with respect to the housing 1 in the same manner as in the case of the photosensitive drum unit 2 and the transfer belt unit 8 in the first embodiment. ing.
[0071]
<Color image printing operation>
Printing of a full-color image by the color printer is basically performed in the same manner as the printer according to the first embodiment.
[0072]
The difference is that the toner images of the respective colors Y, M, C, K formed on the respective photosensitive drums 11 (Y, M, C, K) are primarily transferred so as to be superimposed on the intermediate transfer belt 83. Thereafter, at the secondary transfer position where the intermediate transfer belt 83 and the final transfer roll 50 abut, the toner image on the belt 83 is collectively and secondarily transferred onto the recording paper P.
[0073]
Also in the case of this color printer, since the rotational power is transmitted between the plurality of photosensitive drums 11 and the intermediate transfer belt 83 by the same gear train mechanism, the rotation operation of the intermediate transfer belt and the rotation operation of the photosensitive drum are performed. (In this example, it is easy to synchronize the rotation operation of a plurality of photosensitive drums). In addition, since the intermediate transfer belt and the photosensitive drum are rotationally driven by rotational power from one drive motor, the above-described synchronization can be easily achieved, and in addition, a plurality of drive motors and a power transmission mechanism can be obtained. As compared with the case of adopting the above, space saving and cost reduction for installing the driving motors and the like can be achieved. As a result, it is easy to prevent transfer deviation from occurring at the time of transfer from the photosensitive drum to the intermediate transfer belt. Therefore, particularly when printing a color image such as the above-described full-color image, a high-quality color image in which color misregistration (image misregistration) due to transfer misregistration hardly occurs can be obtained.
[0074]
<Replacement of consumable parts>
Also in this color printer, for example, when the photosensitive drum 11 and the intermediate transfer belt 83 whose lifespans are different from each other are used as in the case of the first embodiment, only one of them reaches the lifespan and is replaced. Even when it is not necessary, only the photosensitive drum (or the intermediate transfer belt) which has reached the end of its life can be replaced independently of the intermediate transfer drum (or the photosensitive drum).
[0075]
That is, after the combined photosensitive drum unit 2 and image transfer belt unit 8 are pulled out of the housing 1 while being supported by the slide rail member, the photosensitive drum unit 2 is pulled up obliquely upward, so that the photosensitive drum unit 2 is transferred to the transfer belt unit. Removed from 8. Thereby, when the photosensitive drum 11 has reached the end of its life, the removed old photosensitive drum unit 2 can be replaced with a new photosensitive drum unit. When the life of the intermediate transfer belt 83 has expired, the old intermediate transfer belt unit 8 taken out of the housing can be replaced with a new intermediate transfer belt unit. Then, by combining the new photosensitive drum unit or the intermediate transfer belt unit with the new photosensitive drum unit or the intermediate transfer belt unit as described above, the printer can be used again by being stored and mounted in the housing 1.
[0076]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, even if the image forming apparatus uses a plurality of image carriers and the intermediate transfer member, the demand for miniaturization and speeding up is addressed. Since the first unit having at least the plurality of image carriers and the second unit having at least the intermediate transfer member are employed, the image carriers and the intermediate transfer members each having a large difference in service life are used. It can be easily and independently replaced independently, and a wasteful increase in running cost can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a color printer according to a first embodiment.
FIG. 2 is an enlarged configuration diagram of a main part of FIG. 1;
FIG. 3A is a perspective view showing a state where a photosensitive drum unit and an intermediate transfer drum unit are pulled out from the inside of a housing, and FIG. 3B is a perspective view showing a state where the photosensitive drum unit is removed from the pulled out intermediate transfer drum unit.
4A is a schematic perspective view of a photosensitive drum unit, and FIG. 4B is a cross-sectional view taken along line BB of FIG.
FIG. 5 is an explanatory view showing a single-line gear train mechanism of the photosensitive drum unit.
FIG. 6A is a perspective view when viewed from the front side of the intermediate transfer drum unit, and FIG. 6B is a perspective view when viewed from the rear side of the intermediate transfer drum unit.
7A is a sectional view taken along line AA in FIG. 6A, and FIG. 7B is an explanatory view showing a single-line gear train mechanism of the intermediate transfer drum unit.
FIG. 8 is a main part explanatory view showing a relationship between a shaft locking plate for coupling the photosensitive drum unit to the intermediate transfer drum unit and a rotating shaft end of the photosensitive drum.
FIG. 9 is an explanatory view of a main part showing a state of a gear train mechanism when the photosensitive drum unit is connected to the intermediate transfer drum unit.
FIG. 10 is an essential part explanatory view showing a coupled state of the coupled photosensitive drum unit, intermediate transfer drum unit, and drive gear.
FIG. 11 is a schematic configuration diagram showing a main part of a color printer according to a second embodiment.
FIGS. 12A and 12B schematically show a state in which the photosensitive drum unit and the intermediate transfer belt unit are combined, wherein FIG. 12A is a schematic diagram viewed from above, and FIG. 12B is a schematic diagram viewed from the rear side.
FIGS. 13A and 13B schematically show a state when the photosensitive drum unit and the intermediate transfer belt unit are separated, wherein FIG. 13A is a schematic diagram viewed from above, and FIG. 13B is a schematic diagram viewed from the rear side.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Housing (main body), 2 ... Photosensitive drum unit (1st unit), 5 ... Intermediate transfer drum unit (2nd unit), 8 ... Intermediate transfer belt unit (2nd unit), 11 ... Photosensitive drum (image carrier) Reference numerals 21 to 23: intermediate transfer drum (intermediate transfer member); 83: intermediate transfer belt (intermediate transfer member); P: recording paper.

Claims (6)

A main body, a plurality of image carriers on which an electrostatic latent image is formed and a toner image formed by developing the latent image, and a recording sheet carrying the toner images formed on each of the image carriers; An intermediate transfer member that conveys the image to a transfer position, and an image forming apparatus including the image carrier and the intermediate transfer member.
A first unit having at least the plurality of image carriers and a second unit having at least the intermediate transfer member,
Further, the image forming apparatus is characterized in that the first unit and the second unit have a structure that can be freely combined and separated, and have a structure that is detachable at an image forming position of the main body. The image forming apparatus according to claim 1, wherein the first unit and the second unit have a structure that can be attached to and detached from an image forming position of the main body only when the first unit and the second unit are connected. The image forming apparatus according to claim 1, wherein the first unit and the second unit have a structure that can be separated only when the first unit and the second unit are detached from an image forming position of the main body. 4. A power transmission mechanism of a single system, wherein the first unit and the second unit are connected at the time of their connection to transmit rotational power between the plurality of image carriers and the intermediate transfer member. The image forming apparatus according to any one of the above. When the first unit and the second unit are mounted on the image forming position of the main body, one of the image carrier and the intermediate transfer body is connected to one driving source installed on the side of the main body and the driving source The image forming apparatus according to claim 4, wherein the image forming apparatus has a structure in which the rotational power is input by the image forming apparatus. The image forming apparatus according to claim 1, wherein the intermediate transfer body is a plurality of intermediate transfer drums.

Images