JP2003098937A - Process cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge with which a good image can be realized by preventing an omission of toner image even when the end edge part of carried recording medium is bounced up between a transfer part and a fixing part, and an image forming device. SOLUTION: In the process cartridge which is attached to and detachable from the image forming device fixing an image at a fixing part after transferring the toner image at the transfer part to carried recording medium and provided with a photoreceptor drum 11 carrying the toner image, spurs 21 which can be rotated in contact with the recording medium carried from the transfer part to the fixing part are provided in plurality in the carrying direction of the recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detachably mountable process cartridge used in an image forming apparatus such as a copying machine or a printer, and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine using an electrophotographic system, as shown in FIG. 8, an electrostatic latent image is formed on a photosensitive drum 100 as an image bearing member. Toner is supplied to the electrostatic latent image to form a toner image, and the toner image is transferred to the recording medium S. The recording medium S to which the toner image is transferred is conveyed to the fixing device 101, where the toner image is fixed on the recording medium by using heat and pressure. Fuser
The heating roller 101 that heats the recording medium S is generally denoted by 101.
a and a pressure roller 101b for pressing the recording medium are provided, and the recording medium S includes these two rollers 101a and 101b.
The toner image is fixed on the recording medium by being conveyed while being sandwiched by.

[0003]

In the photoconductor drum 100 described above, from the transfer portion (the contact portion between the photoconductor drum 100 and the transfer roller 102) where the toner image is transferred to the recording medium S, the fixing portion A transport path for transporting the recording medium is formed between (the nip portion between the heating roller 101a and the pressure roller 101b of the fixing device 101).

In this conveying path, as shown in FIGS. 8 and 9, the heating roller 101a and the pressure roller 101 of the fixing device 101 are provided.
The rear end of the recording medium S being conveyed while being sandwiched by b may be in a state of bouncing toward the photosensitive drum. When the trailing edge of the recording medium bounces between the transfer unit and the fixing unit, the toner image formed on the recording medium comes into contact with surrounding parts and a part of the toner image is lost, resulting in an image defect. There is a risk.

Further, as shown in FIGS. 8 and 9, a fixing device
In the case of a conveyance path in which the position of 101 is above the photosensitive drum 100, the behavior of the trailing edge of the recording medium becomes complicated, and the toner image comes into contact with surrounding parts and a part of the toner image is removed. There is an increased risk that the image may be missing and cause an image defect.

The present invention is intended to solve the above problems,
An object of the present invention is to provide a process cartridge and an image forming apparatus capable of preventing a toner image from being lost and realizing a good image even if the trailing end of a recording medium being conveyed bounces between a transfer unit and a fixing unit. It is a thing.

[0007]

A typical structure according to the present invention for achieving the above object is to transfer a toner image to a recording medium to be conveyed at a transfer portion and then fix the image at a fixing portion. In a process cartridge having an image carrier for carrying a toner image, which is detachable from the main body of the image forming apparatus, the rotating body rotatable in contact with a recording medium conveyed from the transfer section to the fixing section is recorded. It is characterized by having a plurality in the medium transport direction.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus equipped with a process cartridge according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] FIGS. 1 to 5 show a process cartridge and an image forming apparatus according to a first embodiment, FIGS. 1 to 4 are explanatory views of the process cartridge, and FIG. FIG. 3 is an overall explanatory diagram of an image forming apparatus.

[Image Forming Apparatus] First, the overall structure of the process cartridge and the image forming apparatus will be briefly described with reference to FIG.

This image forming apparatus has an image reading section 2 and an image forming section 3 in an apparatus body 1, and the image reading section 2 is arranged above the image forming section 3. An ejecting space portion 4 for ejecting a sheet which is a recording medium recorded by the image forming unit 3 is formed in the apparatus casing between the two, which is a so-called in-machine ejecting type image forming apparatus.

In the present embodiment, an automatic document feeder (hereinafter referred to as "ADF") 5 is mounted on the image reading unit 2, and a document sent from the ADF 5 onto the platen glass 6 or The ADF 5 is rotated and opened, and the original set on the platen glass 6 is exposed and scanned by the image reading unit 2 to be read. That is, the image reading unit 2 irradiates a document on the platen glass 2a with light while scanning the light source, collects the reflected light on a photoelectric conversion element via a mirror and a lens, and converts it into an electrical digital signal. And then transmit. If this digital signal is transmitted to its own image forming section 3, it functions as a copying machine, and if it is transmitted to the image forming section of another machine, it functions as a facsimile machine.

The image reading unit 2 is not necessarily the ADF.
It is not necessary to wear 5. That is, an original pressing member for pressing the original set on the platen glass 6 of the image reading unit 2 may be provided.

The image forming section 3 uses an electrophotographic toner image on a sheet conveyed by a sheet feeding roller 9 and a conveying roller 10 from a sheet cassette 8 loaded in a sheet feeding section 7 disposed below the image forming section 3. Is formed.

That is, a photosensitive drum as an image bearing member.
The surface of 11 is uniformly charged by a charging roller 12, and the photosensitive drum 11 is selectively exposed by a laser scanner 13 which irradiates light based on image information transmitted from the image reading section 2 or a personal computer. By doing so, a latent image is formed. This latent image is toner-developed by the developing device 14 to form a visible image,
The toner image is transferred to the conveyed sheet by applying a bias to the transfer roller 15.

At this time, the toner remaining on the photosensitive drum without being completely transferred to the sheet is removed by the cleaning device 16.

The sheet on which the toner image has been transferred as described above is conveyed as it is to the fixing device 17 positioned substantially vertically upward, and the nip portion between the heating roller 17b containing the heater 17a and the pressure roller 17c ( After passing through the fixing section), heat and pressure are applied to fix the toner, and then the toner is discharged to the discharge tray 18 provided in the discharge space section 4.

{Process Cartridge} In the present embodiment, each member for executing the electrophotographic process is formed as a drum-integrated process cartridge and a sleeve-integrated developing cartridge. That is, as shown in FIG. 1, the photosensitive drum 11 and the charging roller
12, cleaning device 16 is a process cartridge
A developing device 14 which is made into a cartridge as 19, and in which a toner container portion 14a for storing toner and a developing sleeve 14b for supplying the toner to the photosensitive drum 11 are integrated, is made as a developing cartridge.

Each of the cartridges can be attached to and detached from the cartridge mounting portion of the apparatus main body 1 by opening the door cover 20 formed on the left side surface of FIG.

(Spurring of Process Cartridge) As described above, when the trailing edge of the sheet S conveyed while being sandwiched between the heating roller 17b and the pressure roller 17c bounces, the toner image formed on the sheet S is surrounded by the surroundings. There is a risk that a part of the toner image may be lost due to contact with the above-mentioned component, resulting in an image defect.

Therefore, in this embodiment, as shown in FIGS. 1 to 3, when the process cartridge 19 is mounted,
A transfer portion (a contact portion between the photosensitive drum 11 and the transfer roller 15),
Fixing part (nip part between heating roller 17b and pressure roller 17c)
A rotary body unit 21 having a plurality of spur-shaped rotary bodies 21a and 21b arranged in the sheet conveying direction is attached to the frame body of the process cartridge 19 located between the two. Specifically, as shown in FIGS. 2 and 3, five rows of rotating bodies 21a and 21b that are driven and rotatable in the sheet width direction are provided in two rows in the sheet conveying direction.

The "spur-like" rotating body has a small contact area with the sheet S, and even if it comes into contact with the sheet surface side on which the toner image is transferred, it does not disturb the toner image before fixing. The rotating body is, for example, a rotating body having a so-called “spur” shape in the present embodiment (hereinafter referred to as “spur”).

As described above, by arranging the spurs 21a and 21b, even if the rear end of the sheet S being conveyed while being sandwiched between the heating roller 17b and the pressure roller 17c is about to bounce, it will be difficult to obtain the results shown in FIGS. As shown in FIG. 4, the sprung portion is pressed by the spurs 21a and 21b. Therefore, even if the trailing edge of the sheet S bounces, the toner image formed at the trailing edge does not come into contact with surrounding parts or ribs.
Further, since the spurs 21a, 21b guide the sheet while rotating in the conveying direction by point contact, there is no risk of missing the unfixed image.

Since the way the trailing edge of the sheet S bounces depends on the shape of the conveying path, the type of paper, the environment, etc., the trailing edge of the sheet of the unfixed image bounces and contacts the surrounding parts. The position to try is not uniform. In particular, as in the image forming apparatus according to the present embodiment, when the fixing device 17 has a conveyance path (vertical path) that is substantially vertically above the photoconductor drum 11, the distance between the photoconductor drum 11 and the fixing device 17 is increased. The rear end portion of the sheet S behaves more intricately than in the case where the conveyance path is horizontal.

However, in this embodiment, as described above,
A plurality of (two rows in this embodiment) spurs are provided along the conveyance direction in the sheet conveyance path between the photoconductor drum 11 and the fixing device 17.
21a and 21b are arranged at the places where the rear end of the seat may bounce and come into contact with surrounding parts or ribs.
The toner image formed at the trailing edge of the sheet does not come into contact with surrounding parts or ribs, and there is no risk of image defects.

By providing the process cartridge 19 with two rows of spurs 21a and 21b, it is possible to eliminate a protruding portion such as a spur fixing portion on the apparatus main body 1 side. Therefore, there is nothing that prevents the process cartridge 19 from being attached or detached, and the process cartridge 19 and the developing cartridge 14 can be attached and detached smoothly.

Further, of the two rows of spurs 21a and 21b, the spur 21a on the upstream side in the sheet conveying path in the conveying direction is made smaller in diameter than the spur 21b on the downstream side, so that the front end of the sheet S is close to the spurs 21a and 21b. When passing through, as shown in FIG. 4, it can be conveyed without being caught by the spurs 21a and 21b.
Therefore, the occurrence of image defects is eliminated, and the sheet jam due to spurs can be prevented.

[Second Embodiment] As shown in FIG. 6, when the nip position between the heating roller 17b and the pressure roller 17c with respect to the photosensitive drum 11 is on the right side of the first embodiment, the photosensitive drum 11 and Since the transport path between the fixing devices 17 is longer than that in the first embodiment, the range in which the trailing edge of the sheet bounces and comes into contact with surrounding parts and ribs becomes wider. Therefore, in the two rows of spurs 21a and 21b, it is difficult to completely eliminate the portion where the seat rear end portion bounces and comes into contact with surrounding parts and ribs. Therefore, as shown in FIG. 7, the process cartridge 19 is provided with a third row spur 21c. As a result, it is possible to reliably eliminate a portion where the rear end of the sheet bounces and comes into contact with surrounding components or ribs, and it is possible to eliminate the possibility of image defects.

Further, when the conveyance path between the transfer section and the fixing section becomes long, the range in which the trailing edge of the sheet bounces and comes into contact with surrounding parts, ribs, etc. is further increased. By providing the sheet, it is preferable to prevent a portion where the rear end portion of the sheet bounces and comes into contact with surrounding parts, ribs, etc., and prevent defective images.

Further, although the process cartridge 19 described above is an example in which the process cartridge 19 is separate from the developing cartridge and can be attached and detached individually, the developing device may be integrated to form a process cartridge. That is, the process cartridge here means one having one of the photosensitive drum 11 as an image bearing member and the process means such as the charging roller 12, the developing device 14, and the cleaning device 16.

[0031]

As described above, according to the present invention, since a plurality of rotating bodies are provided between the transfer section and the fixing section, even if the trailing edge of the recording medium toward the fixing section bounces, the bounce of the recording medium is prevented. The part that has been pressed is held down by the rotating body. Therefore, the toner image formed on the rear end portion of the recording medium does not come into contact with surrounding parts, ribs, etc., and it is possible to prevent the occurrence of image defects. Further, by forming the rotating body in a spur shape, the area in contact with the recording medium is extremely smaller than that of the rib and the like, and the contact of the rotating body does not disturb the toner image.

Further, by making the diameter of the rotary body on the upstream side in the transport direction of the recording medium in the transport direction smaller than that of the rotary body on the downstream side, the recording medium can be transported without being caught when the front end passes near the rotary body. .

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view of a transfer unit to a fixing unit according to a first embodiment.

FIG. 2 is a cross-sectional explanatory diagram of a process cartridge.

FIG. 3 is a perspective explanatory view of a process cartridge.

FIG. 4 is an explanatory diagram showing a state in which the trailing edge of the sheet is conveyed between the transfer section and the fixing section.

FIG. 5 is a cross-sectional explanatory diagram of an image forming apparatus in which a process cartridge is mounted.

FIG. 6 is an explanatory view showing a state in which the rear end of the seat is out of the spur.

FIG. 7 is an explanatory diagram of an embodiment in which three rows of spurs are provided.

FIG. 8 is an explanatory diagram of a conventional technique.

FIG. 9 is an explanatory view showing a state where the rear end of the sheet bounces and comes into contact with the cartridge frame.

[Explanation of symbols]

S ... sheet 1 ... Device body 2 ... Image reading section 3 ... Image forming unit 4 ... Discharge space 5 ... ADF 6 ... Platen glass 7… Sheet feeding section 8 ... Sheet cassette 9 ... Feed roller 10… Conveyor roller 11 ... Photosensitive drum 12 ... Charging roller 13… Laser scanner 14 ... Developer 14a ... Toner container section 14b ... Development sleeve 15… Transfer roller 16… Cleaning device 17… Fixer 17a ... Heater 17b ... Heating roller 17c ... Pressure roller 18… Ejection tray 19… Process cartridge 20… Door cover 21 ... Rotary unit 21a, 21b ... Rotating body

Claims (5)

[Claims] 1. An image carrier, which is detachable from a main body of an image forming apparatus for transferring a toner image to a conveyed recording medium in a transfer unit and then fixing the image in a fixing unit, and has a toner image. The process cartridge is characterized in that it has a plurality of rotating bodies in contact with a recording medium conveyed from the transfer section to the fixing section and rotatable in a conveying direction of the recording medium. 2. The plurality of rotating bodies, wherein the rotating body closest to the transfer portion has a smaller diameter than the rotating body closest to the fixing portion. Process cartridge. 3. The process cartridge according to claim 1, wherein the rotating body has a spur shape and can be driven to rotate. 4. The image forming apparatus, wherein the process cartridge is detachably mountable, and the toner image is transferred onto the conveyed recording medium at the transfer section, and then the image is fixed at the fixing section. An image forming apparatus, comprising: a mounting unit for mounting the process cartridge according to any one of items 1 to 3; and a transporting unit for transporting a recording medium. 5. The image forming apparatus according to claim 4, wherein the recording medium is conveyed from the transfer section to the fixing section substantially vertically upward.