JP3363634B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic type or electrostatic recording type image forming apparatus such as a copying machine or a laser beam printer, and more particularly to an image forming apparatus having an endless belt-like transfer material conveying means. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus which has adopted an electrophotographic system or an electrostatic recording system in an image forming process, a cylindrical photosensitive drum is used as an image carrier, and the periphery of the photosensitive drum is charged. It is well known that process means such as a container, an exposing means, a developing device, and a cleaning device are arranged, and further a transfer material conveying means for conveying a transfer material is arranged on the process means.

By the way, in recent years, in order to improve the transfer property of the transfer material, an endless belt member (hereinafter referred to as a transfer belt) is adopted as the transfer material transfer means, and the transfer material is supported on the transfer belt, and the transfer process is completed. After that, a system of transporting to the next process is proposed.

In particular, it has an image station for forming a plurality of different color images including a plurality of photosensitive drums, and the images formed by the respective image stations are sequentially transferred to a transfer material to form one color image. In this color image forming apparatus, a color image forming apparatus has been proposed in which a transfer material is attracted to a transfer belt, and the transfer material is conveyed to each image station by the movement of the transfer belt to perform the transfer process at each image station.

In the above-mentioned color image forming apparatus, the transfer material can be reliably supported on the transfer belt to perform the transfer step, so that transfer deviation and transfer omission can be prevented,
Further, it is possible to prevent color misregistration due to transfer misregistration.

[0006]

However, it is known that the image forming apparatus of the type having the transfer belt as described above has the following problems. (1) Due to the long-term deviation or meandering of the transfer belt, the end surface of the photosensitive drum and the transfer belt come into contact with each other, and the surface of the transfer belt is scratched or damaged and corrugated, which makes it impossible to uniformly support the transfer material. , Causing image defects such as missing transfer. (2) Furthermore, the transfer belt is destroyed and cannot be conveyed.

The above phenomenon is not limited to the contact between the transfer belt and the end surface of the photosensitive drum, but may occur due to the relative relationship between the transfer belt and the process means arranged around the photosensitive drum.

For example, in a developing device, an abutting roller is provided coaxially with the developing roller in order to maintain a developing gap between the developing roller and the photosensitive drum, and the abutting roller is brought into contact with the photosensitive drum. .

In this case, when the abutting roller of the developing device steps on the toner adhering to the peripheral surface of the photosensitive drum to form a lump of toner and adheres to the peripheral surface of the photosensitive drum, it is transferred to the photosensitive drum during the transfer process. The toner lumps attached to the peripheral surface of the photosensitive drum between the belt and the belt function as spacers, making it impossible to realize an appropriate transfer process and causing transfer omission. Furthermore, the transfer belt is damaged, and the transfer belt is damaged as described above.

Similarly, in the cleaning process, when the toner leaks from the defective portion of the cleaning device, the transfer belt is similarly damaged.

Therefore, a first object of the present invention is to provide an image forming apparatus capable of preventing the transfer material conveying means from being damaged by the contact between the end portion of the drum-shaped image carrier and the transfer material conveying means.

A second object of the present invention is to provide an image forming apparatus capable of preventing the transfer material conveying means from being damaged due to a defective cleaning means. Is to provide.

A third object of the present invention is to provide an image forming apparatus capable of preventing the transfer material conveying means from being damaged due to the developing means.

[0014]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention is
In an image forming apparatus having a drum-shaped image carrier for carrying an image and a transfer material carrying means including an endless belt member for supporting and carrying a transfer material, in an axial region having the same outer diameter of the image carrier. The relationship between the width L _D and the width L _B of the endless belt member is L _D > L _B , and the transfer material conveying unit is
Means that the belt member moves in the axial direction of the image carrier.
The width of the belt member.
Was added and L _B and the moving amount δ belt transfer zone L ₁ (= L _B
+ [Delta]) is an image forming apparatus, characterized in that it is L _D> L _1.

[0015]

The cleaning width L _{C in the} axial direction of the image carrier by the cleaning means for cleaning the residual image on the image carrier is preferably L _C > L _B or L _C > L ₁ .

Preferably, it has a collecting means for collecting the toner falling from the cleaning means, and the collectable width L _S of the collecting means is L _S > L _C.

Preferably, the image carrier has developing means for forming an image thereon, and the developing means is not in contact with the image carrier.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

First, the overall structure of the image forming apparatus according to this embodiment will be described with reference to FIG. In the figure, the image forming apparatus has four photosensitive drums 1 (specifically, 1a to 1d) as image bearing members that are independently arranged in parallel, and each photosensitive drum 1 has a laser scanning system 2 respectively. (Specifically, 2a to 2d) are provided, and a primary charger 3 that charges the surface of the photosensitive drum 1 in advance is provided around each photosensitive drum 1.
(Specifically 3a to 3d), developing device 4 (specifically 4a to 4d) having magenta, cyan, yellow, and black toners, and a transfer material using the toner image on each photosensitive drum 1 as a transfer medium. 5, a transfer device 6 (specifically 6a to 6d) for transferring to 5 respectively, a cleaner 7 (specifically 7a to 7d) for removing residual toner on each photosensitive drum 1, and a residual charge on each photosensitive drum 1. A static eliminator 8 (specifically, 8a to 8d) to be removed is provided.

The photosensitive drums 1a to 1d and the transfer devices 6 are also provided.
Transfer material conveying means including a transfer belt 9 that sequentially conveys the transfer material 5 to the transfer portion of each photosensitive drum 1 is rotatably arranged by the transfer belt drive roller 92 between the a and 6d. A sheet feeding unit 10 that supplies the transfer material 5 to the transfer belt 9 is disposed near the right end of the belt 9 in the figure. Further, near the left end of the transfer belt 9 in the figure, there are provided a fixing means 11 for fixing the toner image transferred and transferred onto the transfer material 5, and a discharging means 12 for discharging the transfer material after the fixing process.

In this embodiment, the photosensitive drum 1, the developing device 4, and the cleaner 7 of each image station are integrally supported by a support frame 1001 (hereinafter referred to as a process unit support), and the process unit support 10
By drawing 01 from the apparatus main body, it can be integrally taken out from the apparatus main body.

At the left and right ends of the process unit support body 1001 in the figure, rail members (accuride rails) 1002 and 1003 that are extendable and retractable with respect to the apparatus body for pulling out the process unit support body 1001 from the apparatus body.
Are arranged respectively.

Then, the process unit support 1001
Each developing device 4,
The cleaner 7 and the photosensitive drum 1 are configured to be attached to and detached from the process unit support 1001.

FIG. 3 shows the process unit support 10 described above.
2 shows a state in which 01 is pulled out from the apparatus main body to the front side in FIG. 2, and the process unit support body 1001 has the process unit support body front plate 1011 and the process unit support body rear plate 1012 in front of and in the rear side of the drawing direction. I have it. Further, in FIG. 3, the process unit support 1 is further added.
The process unit 101 is taken out from 001 in the upward direction indicated by arrow B.

The process unit 101 of this embodiment is a unit in which the developing unit 4 and the cleaner 7 are integrated, and the process unit 101 is replaced by the process unit support 100.
In the state of being taken out above 1, the photosensitive drum 1 is left on the process unit support 1001.

FIG. 4 is a schematic sectional view taken along the line DD of FIG. As shown in FIGS. 3 and 4, the photosensitive drum 1 has U-shaped grooves 1022a (1021a) of drum supporting members 1021 and 1022 in which the boss portions of the flanges 1A and 1B at both ends of the photosensitive drum 1 are fixed to the process unit supporting body 1001.
(Not shown) is supported in a depressed state.

Further, when the photosensitive drum 1 is taken out, it is achieved by lifting the photosensitive drum 1 in the upward direction shown by the arrow B from the state shown in FIGS.

On the contrary, when the photosensitive drum 1 and the process unit 101 are mounted on the main body of the apparatus, the reverse operation described above may be performed. That is, the process unit support 100
1 is pulled out from the main body of the apparatus, first, the photosensitive drum 1 is lowered in the direction of arrow C, and the process unit support 10
The drum supporting members 1021 and 1022 on 01 are placed on the U-shaped groove 1022a (U-shaped groove 1021a is not shown). After that, the process unit 101 is placed on the process unit support 1001, and the process support 1001 is slid in the direction of arrow E in FIG. 3 and pushed into the apparatus main body.

Then, the process unit support rear plate 101
2, the drum shaft 13 is inserted into the bearing 1014 on the upper part 2, and the bearing 99 (FIG. 4) of the process unit 101 is further inserted into the drum flanges 1B and 1A of the photosensitive drum 1.
And finally the drum shaft 13 is guided to the bearing 1013 of the process unit support front plate 1011.

The process unit support front plate 101
The pin 1016 of No. 1 engages with the hole 15a of the front side plate 15 of the apparatus main body, and the pin 104 of the process unit 101 engages with the hole 17a of the rear side plate 17 of the apparatus main body (see FIG. 1).

By the above operation, the process unit 101 of each station and the photosensitive drum 1 of each station
Completes the positioning with respect to the drum shaft and the apparatus main body.

Incidentally, FIG. 1 shows the process unit 101.
FIG. 2 shows a state in which the photosensitive drum 1 is mounted on the apparatus main body.
It is seen from the arrow A direction.

FIG. 5 is a partially omitted sectional view showing the image forming station in this state.

As shown in FIG. 1, the process unit 101 is supported by the drum shaft 13 via ball bearings 116 and 99 which are press-fitted into the front side plate 114 and the rear side plate 115, respectively. The ball bearing may be a slide bearing.

On the other hand, with respect to the photosensitive drum 1, the front flange 1A and the rear flange 1B at both ends of the photosensitive drum 1 are fitted and positioned by the drum shaft 13. That is, the process unit 101 and the photosensitive drum 1 are independently positioned on the drum shaft 13.

Therefore, the relative distance between the developing device 4 and the cleaner 7 in the process unit 101 with respect to the photosensitive drum 1,
That is, in the case of the developing device 4, the photosensitive drum 1 and the developing roller 4
In the case of the cleaner 7 and the gap with 4, the penetration amount of the blade 71 is guaranteed accurately.

In the state shown in FIGS. 1 and 5, the process unit 101 and the photosensitive drum 1 are respectively the drum shaft 1
3 and are floating above the process unit support 1001. That is, the photosensitive drum 1
Both flanges 1A, 1B of the process unit support 10
01 from the U-shaped grooves of the drum supporting members 1021 and 1022.

As described above, the process unit 101
The developing device 4 therein can be accurately positioned without contacting the photosensitive drum 1. Therefore, since there is no contact between the abutting roller and the surface of the photosensitive drum as in the conventional case, the surface of the photosensitive drum is not scratched or the toner mass is not fixed to the surface of the photosensitive drum. Therefore, it is possible to prevent the transfer belt 9 from being scratched or damaged due to scratches or adhered matter on the surface of the photosensitive drum.

The overall width of the cleaning blade 71 of the cleaner 7 is set to be longer than the overall width of the photosensitive drum 1. Therefore, the entire circumference of the photosensitive drum can be cleaned by the blade.

Further, in this embodiment, the process unit 1
When 01 is removed from the apparatus main body (see FIG. 4), a scooping sheet 18 which is a separate body from the cleaner 7 is installed in order to recover the toner flapping off on the cleaner blade 71.

As shown in FIG. 4, the photosensitive drum 1
A density sensor 19 for detecting the density of the toner image developed on the photosensitive drum 1 is disposed in the vicinity of, and the output of this density sensor 19 changes and corrects the conditions for image formation to correct the maximum density. It guarantees D _max and density linearity.

Further, the density sensor 19 in this embodiment is
In order to prevent contamination due to toner leakage from the lower part of the cleaner, it is arranged below the scooping sheet 18.

As is clear from the above description, the developing device supporting means around the photosensitive drum and the cleaning area by the cleaning blade are set to the entire area of the photosensitive drum.
The surface of the photosensitive drum is always kept uniform, and the transfer belt surface is prevented from being contaminated or scratched or damaged due to the contamination.

On the other hand, the width of the transfer belt 9 is set smaller than the width of the photosensitive drum 1 (see FIG. 1) and contacts the peripheral surface of the photosensitive drum 1 over the entire width of the transfer belt 9. In this case, the transfer belt 9 does not come off from the photosensitive drum area.

Next, the deviation control of the transfer belt 9 will be described with reference to FIG. Here, the deviation control is control for limiting the deviation or meandering amount of the transfer belt 9 that occurs when the transfer belt 9 is driven, and preventing the transfer belt 9 from dropping from a roller such as a transfer belt driving roller.

In this embodiment shown in FIG. 6, a protrusion-shaped rib 91 is provided on the inner peripheral surface of the transfer belt 9, and a groove is formed on the peripheral surface of the transfer belt driving roller 92 at a position corresponding to the rib 91. The ribs 91 are provided so that the ribs 91 enter the grooves 93 to regulate the deviation amount of the transfer belt 9. That is, when the width of the rib 91 of the transfer belt 9 is a and the width of the groove 93 provided in the transfer belt driving roller 92 is b, the transfer belt 9 is a moving amount or a deviation amount with respect to the transfer belt driving roller 92. Only b−a = δ can move in the roller axis direction.

Therefore, when the width of the transfer belt 9 is L _B , the movable range of the transfer belt in the axial direction of the transfer belt drive roller (hereinafter referred to as the transfer belt offset range) L ₁ is
The L ₁ = L _B + δ.

In this embodiment, the transfer belt deviation range L ₁ is the width L _{D of the} axial area of the photosensitive drum 1 having the same outer diameter d.
The transfer belt 9 is set to be smaller, and even if the transfer belt deviation amount is controlled to δ and the transfer belt deviation is caused by the deviation amount δ, the transfer belt 9 does not come off from the photosensitive drum.

FIG. 7 shows a thrust relationship diagram of this embodiment. The width L _D of the photosensitive drum 1 is set larger than the transfer belt L _{B and} larger than the shift range L ₁ of the transfer belt 9, that is, L _D > L ₁ > L _B.

On the other hand, since the cleaning blade 71 of the cleaner 7 is capable of cleaning the entire width of the photosensitive drum 1, the cleaning range L _C of the cleaner 7 is equal to the width L _D of the photosensitive drum 1, that is, L _C = L _It is set to _D.

Further, the toner collecting range L of the scooping sheet 18
_S is larger than the cleaning range L _C of the cleaner 7, L
_S > L _C is set. Therefore, even if the toner leaks from the cleaner end, or even if the toner drops from the drum end and the cleaner end when the process unit or the photosensitive drum is attached or detached, the scooping sheet catches the fallen toner. It is possible to collect.

Therefore, the transfer belt, the transfer device, or the functional parts driving the transfer belt, which are arranged under the cleaner, are not contaminated with toner and deteriorated in function.

Further, as another embodiment of the belt deviation control of the present invention, in addition to the system using the ribs on the inner peripheral surface of the transfer belt and the groove of the transfer driving roller as shown in FIG. 6, i) the transfer driving roller and others The roller member system of is set to be larger than both end portions in the central portion in the axial direction,
A method of regulating the deviation of the transfer belt so that the roller member takes on a crown shape as a whole, or ii) A belt detection sensor is provided on both sides of the transfer belt deviation movement direction, and the deviation of the transfer belt is detected by one sensor. Then, the tensioner roller may be tilted so that the transfer belt deviation direction is reversed to the other sensor side, and the tension distribution in the thrust direction of the transfer belt may be changed to control the transfer belt deviation.

[0055]

As is apparent from the above description, according to the image forming apparatus of the present invention, the width L _D of the axial region having the same outer diameter of the image carrier and the width L _{B of the} endless belt member. Is L _D > L _B , and the transfer material conveying means is
Means for regulating the amount of movement δ of the image carrier moving in the axial direction
And the width L _{B of the} belt member and the movement amount δ are added.
By the belt transfer zone _{L 1 (= L B + δ} ) is L _D> L _1, the following effects.

The long-term deviation or meandering of the endless belt of the transfer material conveying means is regulated to a certain amount or less, and the width of the image carrier is determined from the moving range in the thrust direction of the endless belt including the deviation amount and the meandering amount. Since it is set large, it is possible to contact the image carrier uniformly over the entire width of the endless belt. Therefore, it is possible to prevent the damage to the endless belt, the corrugation of the endless belt, and the like, which have been caused by the uneven contact between the endless belt and the image carrier, which have been conventionally problematic.

Since the cleaning range of the image carrier is set larger than the thrust movement range of the endless belt, the peripheral surface of the image carrier that contacts the endless belt is uniformly cleaned. Further, since the developing device is not in contact with the image carrier, generation of toner lumps or the like on the surface of the image carrier which comes into contact with the endless belt is prevented, and even if there is dust or other adhered matter on the image carrier. It is possible to clean the endless belt before it is scratched.

As a result of the above, it is possible to prevent the endless belt from being damaged, and to provide a high-quality image by preventing transfer defects such as transfer omissions, color misregistration and color unevenness caused by defective running of the endless belt. become able to.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an image station.

FIG. 2 is an overall configuration diagram of an image forming apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing a state in which the process unit support body of FIG. 2 is pulled out from the apparatus main body to the front side.

FIG. 4 is a schematic cross-sectional view taken along the line DD of FIG.

FIG. 5 is a schematic sectional view of an image station.

FIG. 6 is an explanatory diagram showing a relationship between a transfer belt and a transfer belt driving roller.

FIG. 7 is a thrust relationship diagram according to the present invention.

[Explanation of symbols]

1 Image carrier (photosensitive drum) 4 Developing device (developing means) 7 Cleaning means 9 Transfer belt (transfer material conveying means) 18 scooping sheet (collecting means) 91 ribs (regulating means) 92 Transfer belt drive roller 93 Groove (Regulation means)

Claims (4)

(57) [Claims] 1. A drum-shaped image carrier for carrying an image,
In an image forming apparatus having a transfer material conveying unit including an endless belt member that supports and conveys a transfer material, a width L _D of an axial region having the same outer diameter of the image carrier and a width of the endless belt member. The relationship with L _B is L _D > L _B , and in the transfer material conveying means, the belt member is the image carrier.
It has a means for regulating the amount of movement δ that moves in the axial direction of the body,
A bell obtained by adding the width L _{B of the} belt member and the movement amount δ.
DOO transfer zone _{L 1 (= L B + δ} ) is the image forming apparatus, characterized in that the L _D> L _1. 2. The cleaning width L _{C in the} axial direction of the image carrier by the cleaning means for cleaning the residual image on the image carrier is L _C > L _B or L _C > L _1. The image forming apparatus according to claim 1 . 3. The collecting means for collecting the toner falling from the cleaning means, and the collectable width L _S of the collecting means is L _S > L _C. Item 2
Image forming device. Wherein said a developing means for forming an image on the image bearing member, developing means image forming apparatus according to claim 1, wherein an image bearing member in a non-contact.