JPH11231651A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device permitting to prevent a developer carrier or an image carrier from coming in contact with each other and being damaged by turning operation of the developing device, when developer is not being carried on the developer carrier. SOLUTION: A tension part is arranged so as to be able to come in contact with a developing roller of the developing unit positioned at a developing position by arranging back-up rollers 35 for pushing outward the photoreceptor belt 1 to be movable, positioning them usually at the side of color developing unit as shown by solid lines, and pushing outward one tension part on the side of the color developing unit, of the two tension parts on the photoreceptor belt 1. And, at the time of setting up, the above-mentioned tension part is separated from the above-mentioned developing roller so as not to come in contact with each other by positioning the tense expansion part on the opposite side of the color developing unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.
An image carrier and a plurality of developing devices are arranged around a rotation axis, and any one of the plurality of developing devices is rotated to a development position facing the image carrier around the rotation axis. The present invention relates to an image forming apparatus provided with a developing device for moving and developing using a developer carried on a developer carrying member.

[0002]

2. Description of the Related Art Conventionally, a rotating body is opposed to a latent image carrier, and a plurality of developing units are supported at predetermined positions by the rotating body, and each developing unit is opposed to the latent image carrier. Rotary developing device using a one- or two-component developer that develops the latent image on the latent image carrier with each color toner by sequentially rotating and transporting it to the developing position Have been.

In an image forming apparatus having a rotary developing device of this type, when the image forming device is delivered, the developing device is separately packed to prevent damage during transportation. Therefore, when installing the image forming apparatus, it is necessary for the user or service person to install a new rotary developing device.
Further, there is a case where the rotary developing device is replaced depending on the life of the components of the rotary developing device. The new rotary developing device installed in the image forming apparatus does not contain the developer during transportation in order to prevent leakage, scattering, or aggregation of the developer in the rotary developing device, It is unfilled. Therefore, when a new rotary developing device is mounted on the image forming apparatus, it is necessary to supply a developer to each developing device and set up the developing device in a state where development is possible.

[0004] The applicant of the present invention has previously disclosed an image forming apparatus capable of replenishing a sufficient amount of developer in a developing device and setting up the apparatus in a state where development can be performed when a developing apparatus in which developer is not enclosed is mounted. As `` a plurality of developing devices are arranged around the rotation axis, and any developing device among the plurality of developing devices is
A developing device that rotates around the rotation shaft to a developing position facing the latent image carrier to perform development, a developer accommodating portion disposed at one end of the developing device, A developer cartridge rotatably attached to and rotatable integrally with the developing device; and a transport member for transporting the developer in a longitudinal direction of the developing device facing the latent image carrier. An image forming apparatus that supplies a developer to the developer container, conveys the developer in the developer container in a longitudinal direction of the developing device facing the latent image carrier by the conveying member, and supplies the developer to the developing device; In the apparatus, when the developing device in which the developer is not stored in the developing device is mounted on the image forming apparatus, the rotation operation of the developing device that promotes the movement of the developer in the developer cartridge to the developer accommodating portion is performed. The feature is that it was configured to perform That image forming apparatus "was proposed (Japanese Patent Application No. Hei 9-208703).

[0005]

However, in the image forming apparatus having the above-described structure, when a developing device in which no developer is stored is mounted in the developing device and the developing device is rotated, the developing device may be rotated. The developer carrier for carrying the developer and supplying it to the image carrier may come into contact with or rub against the image carrier. At this time, unlike the normal operation of the apparatus, the developer is not carried on the developer carrier. If the developer carrier and the image carrier are directly contacted or rubbed without the intermediary of the developer, the image carrier or the surface of the developer carrier may be damaged.

[0006] Such a problem is caused not only by an image forming apparatus in which a developing device in which a developer is not yet stored is mounted but which rotates the developing device,
This can occur in an image forming apparatus that can be brought into contact with the image carrier by the rotation of the developing device in a state where the developer is not carried on the developer carrier.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide a structure in which the developer is rotated by a rotating operation of the developing device when the developer is not carried on the developer carrying member. An object of the present invention is to provide an image forming apparatus capable of preventing a developer carrier or an image carrier from being damaged by contact between the carrier and the image carrier.

[0008]

To achieve the above object, according to the first aspect of the present invention, an image carrier and a plurality of developing devices are arranged around a rotation axis. A developing device for rotating an arbitrary developing device to a developing position facing the image carrier about the rotation axis and performing development using the developer carried on the developer carrier; In the forming device, the developing device and the image carrier are mounted in the device,
Further, it is characterized in that the developer carrier and the image carrier can be brought into contact with each other by the rotation of the developing device.

In this image forming apparatus, since the developer carrier and the image carrier can be brought into contact with each other by the rotation of the developing device, the developer is placed on the developer carrier. When the developer is not carried, the above state can be taken so that the developer carrier and the image carrier do not come into contact with each other even when the developing device rotates.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, a state in which the developer carrier and the image carrier are not in contact with each other due to the rotation of the developing device, and At least a portion of at least one of the developer carrier and the image carrier is moved so that the developer carrier and the image carrier can be selectively brought into contact with each other by a rotation operation. A moving means is provided.

In this image forming apparatus, by the moving means, the developer carrier and the image carrier are not brought into contact with each other by the rotating operation of the developing device, and by the rotating operation of the developing device. At least a part of at least one of the developer carrier and the image carrier is moved so that the developer carrier and the image carrier can be selectively brought into contact with each other. Accordingly, when the developer is not carried on the developer carrier, the developing device takes a state in which the developer carrier and the image carrier do not come into contact with each other by the rotating operation of the developing device, and Even when the apparatus rotates, the developer carrier and the image carrier can be prevented from contacting each other.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, when the developing device in which the developer is not yet stored is mounted, the developing device rotates. Prior to performing the movement operation, a movement control means for controlling the movement means is provided so that the developer carrier and the image carrier are not brought into contact with each other by the rotating operation of the developing device. It is characterized by having.

In this image forming apparatus, prior to performing the rotation operation of the developing device by the movement control means when the developing device in which the developer has not yet been stored is mounted, the movement of the developing device is controlled. The moving means is controlled so that the developer carrier and the image carrier do not come into contact with each other by the rotation operation. This prevents the developer carrier and the image carrier from coming into contact with each other when the developer is not carried on the developer carrier during the rotation operation.

According to a fourth aspect of the present invention, in the image forming apparatus according to the second or third aspect, when the developing device in which the developer is not yet stored is mounted, the developing device rotates.
Detecting means for detecting whether or not the rotating operation of the developing device is completed; and detecting the completion of the rotating operation of the developing device by detecting the rotating operation of the developing device. A second movement control means for controlling the movement means so that the developer carrier and the image carrier can come into contact with each other is provided.

In this image forming apparatus, the detecting means detects whether or not the rotating operation of the developing device, which is performed when the developing device in which the developer has not been stored yet, is mounted. When the completion of the rotation of the developing device is detected by the detection unit, the developer carrier and the image carrier are brought into contact with each other by the rotation of the developing device. As described above, the moving means is controlled by the second moving control means. Thus, the developing operation for normal image formation can be performed by bringing the developer carrier and the image carrier into contact with each other.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a schematic configuration and operation of the entire color image forming apparatus according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of the entire color image forming apparatus according to the present embodiment. In FIG. 1, a flexible belt-shaped photoconductor as an image carrier (hereinafter, referred to as a “photoconductor belt”)
1 is installed between the rotating rollers 2 and 3, and is rotated and conveyed in the direction of arrow A (clockwise) in the figure by the rotation of the rotating roller 2. Around the photoreceptor belt 1, a charging charger 4 as a charging unit for uniformly charging the surface of the photoreceptor belt, a laser writing unit 5 as an exposure device for forming an electrostatic latent image, yellow, magenta, and cyan A rotary color developing unit (hereinafter referred to as a "color developing unit") as a rotary developing device (also referred to as a "revolver type" or "rotary type") integrally provided with three developing devices each containing a color developer. ), A black developing device 7 and the like as a developing device containing a black developer separate from the color developing unit 6.

The laser writing unit 5 includes a semiconductor laser (not shown), a polygon mirror 5B rotated by a drive motor 5A, an f-θ lens 5C, and a reflection mirror 5.
D is housed in a unit case 5E as a holding housing, and is incorporated in a lower part of the apparatus main body. A bottom plate (not shown) is provided between the paper feed cassette 17 and the laser writing unit 5. A laser writing unit 5 is incorporated on the bottom plate, and side plates (not shown) of the apparatus main body provided on the left and right (rear side and front side in FIG. 1) in the roller axis direction to support each unit correspond to the bottom plate. Has been assembled.

The charging position by the charging charger 4, the irradiation position of the light beam L from the laser writing unit 5, and the cleaning position by the photosensitive member cleaning blade 15A are lower than the two rotating rollers 2 and 3. Is set at a portion where the photosensitive belt 1 is wound around the rotating roller 2 on the side.

Each of the color developing unit 6 and the black developing device 7 has a developing roller as a developer carrying member which comes close to or comes into contact with the photosensitive belt 1 at a predetermined position. Has a function of visualizing by a non-contact development or a contact development method. In addition,
The color developing unit 6 and the black developing device 7 will be described later in detail.

The upper rotating roller 3 of the photosensitive belt 1
An intermediate transfer belt 10 as an intermediate transfer member is provided so as to come into contact with a portion wound around the intermediate transfer belt. The intermediate transfer belt 10 is installed between the rotation rollers 11 and 12 so as to be inclined, and is rotated and conveyed in the direction of arrow B (counterclockwise) in the figure by driving the rotation roller 11. The extended portion on the lower left side of the inclined intermediate transfer belt 10 in the drawing is in contact with the portion of the photosensitive belt 1 wrapped around the upper rotating roller 3, and the first transfer on the photosensitive belt 1 is performed. The developed image is transferred onto the intermediate transfer belt 10 by a conductive bias brush 13 as a primary transfer member provided inside the intermediate transfer belt 10 (primary transfer). The tip of the bias brush 13 is in contact with the back surface of the intermediate transfer belt 10 under predetermined conditions. A transfer roller 14 as a secondary transfer member is provided at a portion where the intermediate transfer belt 10 is wound around the rotation roller 11 so as to come into contact with and separate from the intermediate transfer belt 10.
The transfer roller 14 transfers an image superimposed on the intermediate transfer belt 10 onto transfer paper as a transfer material (secondary transfer). Here, the distance on the intermediate transfer belt 10 from the primary transfer position to the secondary transfer position is:
It is set to be longer than the maximum image output length.

Cleaning device 15 for photosensitive belt
Is a cleaning blade 15A that constantly contacts the photoconductor belt 1 and cleans the toner on the photoconductor belt 1;
A waste toner collecting container 15B and the like are provided. The cleaning device 16 for the intermediate transfer belt includes a cleaning blade 16A for cleaning the surface of the intermediate transfer belt 10, an auger 16B for conveying the toner, and the like.
The cleaning blade 16A for the intermediate transfer belt is kept at a position separated from the surface of the intermediate transfer belt 10 during image formation, and abuts on the surface of the intermediate transfer belt 10 as shown only during cleaning after the secondary transfer. Is done.

In the above-described color image forming apparatus,
After the photoconductor belt 1 is uniformly charged by the charging charger 4, the laser beam (laser beam) L modulated based on image information is scanned by the laser writing unit 5 to be exposed, and the surface is electrostatically charged. A latent image is formed. Here, the image information used for the exposure is monochromatic image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. Laser light L generated by a semiconductor laser (not shown) based on this image information
Is rotationally scanned by a polygon mirror 5B rotated at high speed by a drive motor 5A, passes through an f-θ lens 5C,
The optical path is adjusted by the reflection mirror 5D.

The electrostatic latent image formed on the photoreceptor belt 1 is developed by a color developing unit 6, which will be described later, with a predetermined yellow toner, a magenta toner, and a cyan toner, respectively. Further, the electrostatic latent image formed based on the black color information is developed with black toner by a black developing device 7 to be described later, and each color image (toner image) is sequentially formed on the photosensitive belt 1. You.

Each single-color image (toner image) formed on the photosensitive belt 1 rotating in the direction of arrow A in FIG. 1 is applied to the bias brush 13 for each of the single colors of yellow, magenta, cyan, and black. Due to the predetermined transfer bias, the image is sequentially transferred onto the intermediate transfer belt 10 rotating in the direction of arrow B in synchronization with the photosensitive belt 1. Intermediate transfer belt 1
The images of yellow, magenta, cyan, and black superimposed on the image No. 0 are transferred from a sheet feeding table (sheet feeding cassette) 17 through a sheet feeding roller 18, a pair of conveying rollers 19A and 19B, and a pair of registration rollers 20A and 20B. Is collectively transferred by the transfer roller 14 onto the transfer paper 17 </ b> A conveyed to the printer. After the transfer, the image is fixed by the fixing device 80 to complete the full-color image. Transfer paper 1 on which this full-color image is formed
7A is discharged to a discharge stack 82 via a pair of discharge rollers 81A and 81B.

The photoreceptor belt 1, the charging charger 4,
The intermediate transfer belt 10, the cleaning device 16, the registration roller 20B, and the like are integrally formed as a process cartridge 31, and the waste toner collecting container 15C is removably incorporated in the process cartridge 31. The case exterior part of the registration roller 20B of the process cartridge 31 also has a function as a paper conveyance guide.

The waste toner scraped off from the intermediate transfer belt 10 by the cleaning blade 16A is
An auger 16B provided in the cleaning device 16 transports the device in the forward direction, and further transports the waste toner collecting container 15C by a transport unit (not shown) provided on the side surface on the front side of the process cartridge 31. By replacing the process cartridge 31 when a predetermined amount or more of waste toner is stored in the waste toner collecting device 15C, the life of the process cartridge 31 can be extended.

Next, the black developing device 7 used in the present color image forming apparatus will be described. FIG. 2 shows a black developing device 7.
1 is a schematic configuration diagram showing the inside of the device together with a color developing unit 6. The black developing device 7 contains a black developer (toner) in a developing container 71, and has a developing roller 23 </ b> K as a developer carrier in an opening 71 </ b> A of the developing container 71 facing the photoreceptor belt 1. This is a developing device integrally formed as a so-called developing cartridge in which the life of the developing device is replaced when the toner runs out.

In the developing container 71, a developing roller 23 is provided.
Parallel to K, and contacts the developing roller 23K at a predetermined contact pressure, and rotates so as to slide in a direction opposite to the developing roller surface moving direction at a contact portion with the developing roller 23K while forming a nip. For example, a toner supply roller 25K made of foamed polyurethane or the like is provided. In the vicinity of the opening 71A downstream of the sliding portion between the toner supply roller 25K and the developing roller 23K in the direction of movement of the developing roller surface, a toner layer regulation made of a springy thin plate such as stainless steel or an elastic material such as urethane rubber. A blade 26K as a member has a developing roller 23 near one end thereof.
It is provided so as to be in contact with K.

In the developing container 71, a first agitator 73 for stirring the toner in the container and transporting the toner to the toner supply roller 25K and the developing roller 23K is provided.
The second agitator 7 also stirs the toner in the developing container 71 and conveys the toner to the first agitator 73 side.
4 are provided. The first and second agitators 73 and 74 are disposed such that their rotation axes are parallel to the toner supply roller 25K and the developing roller 23K. Both agitators 73 and 74 are provided with a film-like elastic sheet or the like at the tip thereof so that the tip thereof slides on the bottom surface of the developing container 71.
The toner in the developing container 71 can be efficiently transported, and the remaining amount of the toner in the developing container 71 can be reduced. It is desirable that the rotation speed of the agitators 73 and 74 be as low as possible so as not to apply extra stress to the toner.

Further, the black developing device 7 is movable in the horizontal direction with respect to the photosensitive belt 1, is separated from the photosensitive belt 1 during non-development, and the developing roller 23 approaches or contacts the photosensitive belt 1 during development. A separating operation for moving to the developing position is performed. Normally, the black developing device 7 is retracted to a position where the developing roller 23K does not come into contact with the surface of the photoreceptor belt opposed thereto as shown in FIG. When the electrostatic latent image corresponding to the black image formed on the photoreceptor belt 1 is developed, the entire developing device 7 is moved in a horizontal direction along a guide member (not shown) by the operation of the cam 75. Then, the developing roller 23K is brought into contact with the surface of the photoreceptor belt in a state where a predetermined nip is formed therebetween.

Note that the developing roller 23K is a photosensitive belt 1
When the developing roller 23K is not in contact with the developing container 23, the driving of the developing roller 23K is stopped, the developing roller 23K is controlled so as not to rotate, the toner scatters and leaks from the opening 71A of the developing container 71, the developing roller 23K, and other developing devices. 7 prevents early deterioration of the components.

In this embodiment, the black developing device 7 (developing cartridge) of a type containing toner is used. However, the present invention is not limited to this type. A developing device of a type that replaces a cartridge and replenishes toner may be used.

Next, the color developing unit 6 used in the present color image forming apparatus will be described. FIG. 4 is a schematic configuration diagram showing the inside of the color developing unit 6 together with the black developing device 7, and FIG.
FIG. 2 is a front view showing C along with the photosensitive drum 1. As described above, the color developing unit 6 as a rotary developing device is disposed near the photoreceptor belt 1.

FIG. 4 shows a state in which the developing unit 22C for cyan is at the developing position. This color developing unit 6
The inner casing 21 which is a rotating body is rotatably provided around a rotation axis O. The inner casing 21 can be rotated in a direction indicated by an arrow D (clockwise) in FIG. I have. The inner casing 21 is provided with yellow, magenta, and cyan developing units 22.
(−Y, M, C) are integrally held. The developing units 22 (-Y, M, C) of the respective colors have the same form and are configured to perform the same operation. Each of the developing units 22Y, M, and C has a cylindrical developing roller 23Y as a developer carrier.
M and C are provided. Each developing roller 23Y, M, C
Is arranged such that a part thereof is exposed to the outside from an opening 21A formed in the inner casing 21, and is synchronized with the color information by a drive mechanism (not shown) by an arrow C in the figure.
, And develops the corresponding electrostatic latent image. At this time, the black developing device 7 is held at a position where the developing roller 23K is separated from the surface of the photosensitive belt 1 by a cam 75 and a spring (not shown).

Each of the developing devices 22Y, 22M, and 22C is a developing device using a non-magnetic one-component developer, and contains a yellow toner, a magenta toner, and a cyan toner, respectively.
Then, as the inner casing 21 rotates about the rotation axis O, each of the developing devices 22Y, M, and C is selectively moved to the developing position, and the static belts formed on the photoreceptor belt 1 are sequentially formed as described above. Develop the latent image.

Since the developing units 22 (-Y, M, C) of the respective colors have the same form and are configured to perform the same operation, only the developing unit 22C of one color (cyan) will be described below.

In FIG. 5, one of the two extending portions between the rotating rollers 2 and 3 of the photosensitive belt 1 on the color developing unit 6 side (black developing device 7 side) is pushed outward. Thus, the backup roller 35 is provided,
The upper portion of the one extension portion is transported in the vertical direction, and the lower portion is transported in a state of being slightly inclined.
The black developing device 7 is opposed to the upper part of the extended portion of the photosensitive belt 1 extruded by the backup roller 35, and the color developing unit 6 is opposed to the lower part of the extended portion. Here, the extending portion of the intermediate transfer belt 10 is inclined more greatly than the photosensitive belt 1 so that the extending portion of the photosensitive belt 1 is substantially vertical. Space for disposing the waste toner collecting containers 15B and 15C having a large capacity can be secured.

An opening 21A is formed above the cyan developing unit 22C. A developing roller 23C is disposed in the opening 21A so as to face the photoreceptor belt 1. The developing roller 23 </ b> C
With a predetermined peripheral speed ratio, the photosensitive drum 1 is rotationally driven in the direction indicated by the arrow in the figure so that the surface moves in the same direction as the movement direction (A direction) of the belt at the portion facing the photosensitive belt 1. Below the developing roller 23C, a toner supply roller 25C as a toner supply member made of an elastic material such as foamed urethane is used.
Are provided so as to rub against the developing roller 23C.
The toner supply roller 25C is rotationally driven so as to move in the same direction as the surface movement direction of the roller 23C at a rubbing portion with the development roller 23C at a predetermined peripheral speed ratio with the development roller 23C.

Further, in the vicinity of the opening 21A, on the downstream side of the sliding portion between the developing roller 23C and the toner supply roller 25C in the direction of movement of the developing roller surface, a thin plate made of a spring such as stainless steel or urethane rubber is used. Blade 26C as toner layer regulating member made of elastic material
However, it is provided such that the vicinity of one end thereof is in contact with the surface of the developing roller 23C. Further, a screw-shaped first toner conveying member 27 to be described later conveys toner as a developer from the front side to the rear side in FIG.

As shown in FIG. 6, one end of the color developing unit 6 in the axial direction of the developing roller (the front side of the apparatus in FIG. 5).
Is provided with a toner hopper 29C as a toner storage unit. The screw-shaped first toner conveying member 2
7C is arranged in parallel with the developing roller 23C and the toner supply roller 25C from the toner hopper 29C to the side plate of the developing device 22C on the inner side of the color developing device unit 6 in FIG.

The inner casing 21 is disposed so that a part thereof is in contact with the toner supply roller 25C, and is formed by the developing roller 23C, the toner supply roller 25C and the inner casing 21 as shown in FIG. 1
The toner transport space S surrounding the toner transport member 27C is formed.

The screw-shaped first toner conveying member 27C is interlocked with the developing roller 23C and the toner supply roller 25C so as to convey the toner from the front side to the rear side in FIGS. And a predetermined peripheral speed ratio. With this rotation,
The first toner transport member 27C transports the toner from the toner hopper 29C into the toner transport space S, and supplies the toner onto the toner supply roller 25C. The toner supplied onto the toner supply roller 25C is supplied while being charged on the surface of the developing roller 23C by the toner supply roller 25C, and is carried on the surface of the developing roller 23C. The toner carried on the surface of the developing roller 23C is uniformly and thinned to a predetermined thickness by the blade 26C, and is used for developing the electrostatic latent image formed on the surface of the photoreceptor belt 1. This development is performed by contact development or non-contact development.

The toner not used in the developing step is conveyed by the first toner conveying member 27C to the rear end of the developing unit 22C opposite to the front side where the toner hopper 29C is provided. The toner reaches the toner circulating portion 32C provided outside the effective diameter portion of the developing roller 23C and the toner supply roller 25C in the axial direction, and the toner drops to the lower part of the developing device 22C by gravity.

At the lowermost part of the developing unit 22C located at the developing position, a screw-shaped second toner conveying member 28 is provided.
C is provided in parallel with the developing roller 23C, the toner supply roller 25C, and the first toner conveying member 27C,
Is rotated so as to convey the toner in a direction opposite to the toner conveying member 27, and conveys the toner not used in the developing step to the toner hopper 29C. These first toner conveying member 27C and second toner conveying member 28
By appropriately setting the toner transport amount of C, the developing device 22
A small color developing device capable of supplying toner onto the toner supply roller 25C without detecting the amount of toner in C or performing complicated control of the amount of supplied toner, has a large degree of freedom in layout, and has a small sectional occupation ratio to the photosensitive belt 1. Unit 6
It has become.

The toner cartridge 30C shown in the perspective view of FIG. 7 is detachably mounted on the toner hopper 29C. The toner cartridge 30C is mounted when the color developing device unit 6 is newly mounted, and is replaced when the toner runs out, so that a necessary amount of toner is always stored in the toner hopper 29C.

Except during the image forming operation of the present color image forming apparatus, as shown in FIG. 3, in the black developing device 7, the developing roller 23K is driven by the cam 75 and a spring (not shown). It is held at a position separated from the surface of the belt 1. On the other hand, at times other than the image forming operation, that is, before and after the image forming operation, the color developing unit 6 stops at the rotational position as shown in FIG. In the present embodiment, the rotational position as shown in FIG.
A substantially intermediate position between the developing roller 23C of the cyan developing device 22C and the developing roller 23Y of the yellow developing device 22Y is opposed to the photosensitive belt 1, and the rollers 23C and 23Y of the color developing unit 6 are not in contact with the photosensitive belt 1. The rotation position is the "home position". The home position is determined by the cyan developing device 22C, which is used first when performing the color developing operation in the present embodiment, when the developing device rotates in the direction of arrow D in FIG. It is a position that can be reached quickly and accurately.
Further, at the time of non-image forming operation, it is possible to prevent the photosensitive belt 1 and the developing roller 23 from being deteriorated or damaged due to unnecessary contact between the photosensitive belt 1 and the developing roller 23, and to adhere and fix toner outside a predetermined area. It is also a position where it can be prevented.

Next, the configuration of the main body of the present color image forming apparatus will be described with reference to FIGS. As a device main body structure, a main body frame 9 as an immovable portion housing is provided.
And a front frame 8 as a front housing capable of opening a transfer path of the transfer paper 17A. A paper feed cassette 17 is disposed below the main body frame 9, a color developing unit 6, a black developing device 7, and a process cartridge 31 are replaceably disposed at a central portion, and a fixing device 80 is disposed further thereabove. A discharge stack 82 is formed on the upper part of the main body.

The front frame 8 is supported so as to be rotatable around a rotation support shaft 9A provided on the main body frame 9 serving as a rotation fulcrum. Normally, as shown in FIG. Is kept closed.
When a jam of the transfer paper 17A occurs in the transfer paper transport path, the front frame lock mechanism (not shown) is released, and the front frame 8 is rotated clockwise as shown in FIG. 8 to be opened. The open state of the front frame 8 can be maintained by power such as a tension spring. Since the front frame 8 holds a registration roller 20A, a transfer roller 14, and the like which are part of the transfer paper transport path, when the front frame 8 is opened, the transfer paper transport path is opened as shown in FIG. Jam processing can be easily performed. When the front frame 8 is opened, the units of the image forming system such as the color developing unit 6 are in a stationary state, so that problems such as scattering and leakage of toner do not occur.

When the amount of the cyan toner in the cyan developing device 22C becomes equal to or less than a predetermined amount, the toner end is detected by a conventionally known toner end detecting means or the like, and a toner replacement display is displayed. In this case, as shown in FIG. 9, the toner cartridge 30C is replaced with the front frame 8 opened.

Next, a mechanism for supplying toner from the toner cartridge 30C to the toner hopper 29C will be described. FIGS. 10A to 10D show the toner cartridges 30Y and 30Y when the color developing unit 6 rotates.
FIG. 5 is a diagram illustrating a positional relationship between M, 30C and toner storage units 29Y, 29M, 29C. FIG. 10A shows the position of each toner cartridge and each toner storage unit when the color developing unit is at the home position. Here, the configuration and operation for toner replenishment are the same in the cyan developing unit 22C, the magenta developing unit 22M, and the yellow developing unit 22Y, and therefore, the cyan developing unit 22C will be described here. In a normal image forming operation, when the formation of a black image by the black developing device 7 is completed, the color developing unit 6 is moved in the direction of arrow D in the drawing so that the cyan developing device is located at the developing position in order to form a cyan image. Rotate. At this time, each toner cartridge and each toner hopper are located at the positions shown in FIG. When the color developing unit 6 is sequentially rotated to form a magenta image and a yellow image, respectively, following the formation of the cyan image, the toner cartridges and the toner hoppers rotate as shown in FIGS.
It will be located at the position shown in (d). When the color developing unit 6 rotates in this manner, the toner inside the cyan toner cartridge 30C is removed by its own weight as shown in FIG.
As shown in (a) to (d), the toner cartridge moves within the toner cartridge. The toner cartridge 30C is integrally formed with a partition portion 43C as a developer passage preventing portion.
In the vicinity of the toner hopper 29C mounting portion, a toner storage portion 44C is provided.
Are formed. Then, when rotating from the rotation position shown in FIG. 10C to the rotation position shown in FIG. 10D, the toner in the toner cartridge 30C moves onto the innermost wall 45C on the most upstream side in the cartridge rotation direction. And
When shifting from the rotation position shown in FIG. 10D to the rotation position of FIG. 10A which is the home position, and further to the rotation position of FIG. 10B where the cyan developing device is located at the development position, Part of the toner in the toner cartridge is blocked by the partition 43C and stored in the toner storage 44C. And the stored toner is
The toner flows into the hopper 29C from an opening provided in the toner cartridge 30C and the hopper 29C. As mentioned above,
By rotating the color developing unit 6, a required amount of toner can be stably supplied from the toner cartridge to the toner hopper without using any toner transport mechanism.

By the way, when a new color image forming apparatus main body is purchased or the life of the color image forming apparatus main body is shorter, the life of the color developing unit 6 mounted on the apparatus is shorter.
When the unit needs to be replaced, a new color developing unit 6 is mounted on the color image forming apparatus main body. Here, when a new color developing unit 6 is delivered, the color developing unit 6 is set in a state where the toner is not enclosed for the purpose of preventing abnormalities such as leakage and scattering of toner during transportation and aggregation of toner. . For this reason,
At the time of setting up the image forming apparatus at the delivery destination, it is necessary to put toner in each of the developing units of the color developing unit 6 to make it developable.

In the above-described color developing unit 6, the toner is transported into each developing unit by the toner hoppers 29Y and 29 provided at one end of the color developing unit 6.
M and 29C, the toner cartridges 30Y, 30M and 30
C is mounted, and after storing a necessary amount of toner in the toner hopper, the drive is transmitted to at least the first toner conveying member 27.

To fill the toner hoppers 29Y, 29M, and 29C with toner, the color developing unit 6 is rotated in a predetermined direction with the toner cartridges 30Y, 30M, and 30C mounted as described above. Good. However, new toner cartridges 30Y, 30M, 30C
The toner inside has a non-uniform degree of cohesion and the like during transportation and storage, and it may not be possible to easily fill the empty toner hoppers 29Y, 29M, and 29C with sufficient toner. For this reason, in this color image forming apparatus, the toner cartridge 30
Y, 30M, 30C to toner hoppers 29Y, 29M,
In order to sufficiently fill the 29C with toner, the rotation operation of the color developing unit 6 is performed separately from the rotation operation during the normal image forming operation.

In the color image forming apparatus, when the color developing unit 6 is set up, a continuous rotation operation, for example, about one rotation / 1 second to one rotation / 10 seconds, which is slower than a normal color switching operation, is performed. Thereafter, in each color developing position, each developing unit is driven, and the first toner conveying member 27 conveys and supplies the toner in the longitudinal direction inside the developing unit. Although the length of the developing unit in the longitudinal direction varies depending on the maximum image forming width, in order to supply toner from a state where there is no toner in the developing unit, it is necessary to supply the toner into each toner hopper by rotating the color developing unit 6 once. In some cases, only the used toner is insufficient. In this case, the rotation of the color developing unit 6 and the operations of conveying and supplying the toner may be performed a plurality of times.

The above operation is performed in a state where the front frame is closed, the interlock SW is connected, and each part in the apparatus is located at the same position as in the normal developing operation, due to problems in safety standards and the like. Therefore, when the color developing unit 6 rotates, the photoreceptor belt 1 and the developing roller 23 come into contact with each other and may be rubbed and damaged.

Therefore, in the color image forming apparatus according to the present embodiment, even when the color developing unit 6 is rotated during the setup, the photosensitive belt 1 and the developing roller 23 are exposed to a position where they do not come into contact with each other. The structure which can position the body belt 1 is adopted.

Specifically, the color developing unit 6
The developing roller 23 and the photosensitive belt 1 are not in contact with each other due to the rotation of the developing roller 23, and the developing roller 23 and the photosensitive belt 1 are in contact with each other by the rotating operation of the color developing unit 6. A moving means for moving at least a part of at least one of the developing roller 23 and the photoreceptor belt 1 is provided so that a desired state can be selectively obtained. In the illustrated apparatus, the photosensitive belt 1
11 can be moved in a direction indicated by an arrow E in FIG. 11, and is normally located on the color developing unit 6 side as shown by a two-dot chain line in FIG. The photosensitive belt 1 is positioned on the side opposite to the color developing unit 6 as shown in FIG.
Are moved respectively.

FIG. 12 is an explanatory diagram showing an example of a moving mechanism of the backup roller 35. Note that FIG.
, The photoreceptor belt 1 has rotating rollers 2 and 3
Only a portion of the two extending portions relatively close to the rotating roller 3 is illustrated, and other illustrations are omitted. The illustration of the rotating roller 2 is also omitted. This moving mechanism includes a solenoid 102 whose ON / OFF control is performed by a main control unit (not shown), an arm whose end is connected to a plunger 103 of the solenoid 102, and which is swingably provided about a center point 101a. 101. The backup roller 35 is fixed to an end of the arm 101 on the opposite side to the connection with the plunger 103. (Hereinafter, margin)

In the present color image forming apparatus,
Prior to the turning operation of the color developing unit 6 during the setup, the turning operation of the color developing unit 6 is such that the developing roller 23 and the photosensitive belt 1 do not come into contact with each other. In addition, a configuration in which a movement control means for controlling a movement mechanism as the movement means is provided. Further, detecting means for detecting whether or not the rotation operation of the color developing unit 6 at the time of the setup is completed, and detecting the completion of the rotation operation by the color developing unit when the detection means detects the completion of the rotation operation. And a second movement control means for controlling the movement mechanism so that the developing roller 23 and the photosensitive belt 1 can be brought into contact with each other by the rotating operation of the image forming unit 6. . Specifically, a function as the movement control means and the function as the second movement control means is provided in a main control unit (not shown).

In this color image forming apparatus, the solenoid is normally turned off by the main control unit. The arm 101 is pressed by an urging means (not shown), for example, a spring, a leaf spring, etc.
It is located at the position shown by the solid line in FIG. At this time, of the two extended portions of the photoreceptor belt 1, the extended portion on the side of the color developing unit 6 is pushed outward by the backup roller 35, and the developing position of the three developing units of the color developing unit 6 is changed. Is in a state in which the developing roller 23 of the developing device located at the position. On the other hand, when the apparatus is set up, the solenoid 102 is turned on by the main control unit, and the plunger 103 moves in the direction of arrow G in FIG.
02 is pulled into the body. Then, along with this, the arm 101 swings in the direction of arrow H in the figure, and is displaced to the position shown by the two-dot chain line in the figure. Thereby, the backup roller 35 moves in the direction opposite to the arrow F direction in the figure,
Of the two extending portions of the photosensitive belt 1, the extending portion on the side of the color developing unit 6 is separated from the developing roller 23 of the developing device located at the developing position, and the photosensitive belt 1 is attached to the developing roller 23. It will not be in contact. Accordingly, it is possible to prevent the developing roller 23 from contacting the photosensitive belt 1 and the developing roller or the photosensitive belt 1 from being damaged in a state where the toner is not present on the surface of the developing roller 23. In addition, the backup roller 35 pushes out an expansion portion different from the expansion portion on the color developing unit 6 side to prevent the belt from sagging.

When the setup is completed, a setup completion signal is output by a detection unit (not shown), and the solenoid is again turned on by the main control unit (not shown).
F. As a result, the solenoid plunger 10
3, the arm 101, the backup roller 35, and the photoreceptor belt 1 are located at positions indicated by solid lines in the drawing.

As described above, according to the embodiment, the rotation of the color developing unit 6 causes the developing roller 2 to rotate.
3 and a state in which the developing roller 23 and the photosensitive belt 1 can be in contact with each other by selectively rotating the color developing unit 6. obtain. Therefore, the developing roller 23
When the toner is not carried thereon, the color developing device unit 6 takes a state in which the developing roller 23 and the photoreceptor belt 1 do not come into contact with each other by the rotating operation of the color developing device unit 6. Even when the roller 6 rotates, the developing roller 23 and the photosensitive belt 1 can be prevented from contacting each other. Therefore, it is possible to prevent the developing roller 23 or the photosensitive belt 1 from being damaged by the contact. The photoreceptor belt 1 is configured to be movable toward and away from the color developing unit 6 by moving the entire photoreceptor belt 1, and the color developing unit 6 is connected to the photoreceptor using a cam mechanism or the like. The belt 1 may be configured so as to be able to contact and separate therefrom.

In the above-described embodiment, prior to performing the rotating operation of the color developing unit 6 at the time of the setup, the rotating operation of the color developing unit 6 causes the developing roller 23 and the photosensitive belt to rotate. Since the moving mechanism is controlled by the main control unit as the moving control means so as not to come into contact with the device 1, the operability is improved.

Further, in the above embodiment, a detecting means for detecting whether or not the turning operation of the color developing unit 6 performed at the time of the setup is completed, and the detecting means for detecting that the turning operation is completed. The movement mechanism is controlled by a main control unit as the movement control means so that when the developer is detected, the developer carrier and the image carrier can be brought into contact with each other by the rotation of the developing device. Since control is performed, operability is further improved.

[0065]

According to the first to fourth aspects of the present invention, when the developer is not carried on the developer carrier, the developer carrier and the image carrier come into contact with each other by the rotation of the developing device. Thus, there is an excellent effect that the developer carrier or the image carrier can be prevented from being damaged.

In particular, according to the invention of claim 3, there is an excellent effect that operability is improved.

According to the invention of claim 4, there is an excellent effect that operability is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of the entire color image forming apparatus.

FIG. 2 is a sectional view showing the internal structure of a color developing unit and a black developing device of the color image forming apparatus.

FIG. 3 is a sectional view showing the internal structure of the color developing unit and the black developing device during non-image formation.

FIG. 4 is a cross-sectional view showing the internal structure of the color developing unit and the black developing device during color development.

FIG. 5 is a sectional view showing the internal structure of a cyan developing unit of the color developing unit.

FIG. 6 is a cross-sectional view of the cyan developing device as viewed from the side.

FIG. 7 is a perspective view of the color developing unit.

FIG. 8 is a cross-sectional view of the color image forming apparatus in an open state of a front frame.

FIG. 9 is an explanatory diagram of an attaching / detaching operation of a toner cartridge in the color image forming apparatus.

FIGS. 10A to 10D are diagrams illustrating a positional relationship between each toner cartridge and each toner storage unit when the color developing unit rotates.

FIG. 11 is an explanatory diagram of a photosensitive belt in the color image forming apparatus.

FIG. 12 is an explanatory diagram illustrating an example of a movement mechanism of a backup roller in the color image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2, 3 rotating roller 4 charging charger 5 light writing unit 6 rotating color developing unit 7 black developing device 8 front frame 9 main body frame 10 intermediate transfer belt 21 inner casing 22 developing device 23 developing roller 31 process cartridge 35 Backup roller 101 Arm 102 Solenoid 103 Plunger

Claims (4)

[Claims] An image carrier and a plurality of developing units are arranged around a rotation axis, and an arbitrary one of the plurality of developing units faces the image carrier around the rotation axis. The image forming apparatus includes a developing device that rotates to the developed developing position and performs development using the developer carried on the developer carrier. The developing device and the image carrier are mounted in the device, and An image forming apparatus configured to be able to take a state in which the developer carrier and the image carrier do not come into contact with each other by rotating the developing device. 2. The image forming apparatus according to claim 1, wherein the developer carrier and the image carrier do not come into contact with each other by the rotating operation of the developing device, and the developing device rotates the developer carrier. Moving means for moving at least a part of at least one of the developer carrier and the image carrier is provided so as to selectively take a state in which the developer carrier and the image carrier can come into contact with each other. An image forming apparatus comprising: 3. The image forming apparatus according to claim 2, wherein the rotating operation of the developing device is performed when the developing device in which the developer is not yet stored is mounted. Prior to this, a moving control means for controlling the moving means is provided so that the developer carrier and the image carrier are not brought into contact with each other by the rotation of the developing device. Image forming apparatus. 4. The image forming apparatus according to claim 2, wherein the rotating operation of the developing device is performed when the developing device in which the developer is not stored yet is mounted. Detecting means for detecting whether or not the developing operation has been completed; and, when the detecting means detects that the rotating operation of the developing device has been completed, the developing device rotates the developer carrier and the image. An image forming apparatus, comprising: a second movement control means for controlling the movement means so as to take a state where it can come into contact with a carrier.