KR20050012027A - Method for transfering paper of image forming apparatus - Google Patents

Abstract

PURPOSE: A method of conveying a sheet of paper is provided to reduce jitter noise in an image and obtain a uniform image quality by controlling rotation speed of a transfer roller, a feeding roller and a fusing roller. CONSTITUTION: A method is characterized in that whenever paper is conveyed, a linear velocity at the circumference of a transfer roller(126) is controlled to be larger than or equal to a linear velocity at the circumference of a feeding roller(124). Simultaneously, the linear velocity at the circumference of the feeding roller is controlled to be larger than or equal to a linear velocity at the circumference of a fusing roller(128).

Description

Method for transfering paper of image forming apparatus

example

The present invention relates to a paper transfer method of an image forming apparatus, and more particularly, to a paper transfer method of an image forming apparatus that improves image jitter or non-uniformity in a transfer part generated by an impact or stress of a paper during paper transfer. will be.

In general, in an image forming apparatus, when a print command from a PC enters a controller in the apparatus through a cable, the print data is generated by the control software that processes, stores, compresses, and controls all data, and the CPU that performs central processing. Is sent to the engine CPU. The print engine CPU sends a print signal to a laser scanning unit (LSU) for forming a latent image on the photosensitive member, and the photorefractive image is a latent image on the photosensitive member according to a signal received from the print engine CPU. To form. Then, the latent image is developed with a fine powder toner, and then transferred to the paper with a high voltage, the image is fixed on the paper at high temperature and high pressure, and the paper on which the image is fixed is discharged, thereby completing one cycle of the image forming process.

1 schematically shows an internal configuration of a general image forming apparatus.

Referring to FIG. 1, the sheet picked up by the pick-up roller (not shown) from the paper feed cassette or the paper feed tray by the pick-up roller (not shown) is aligned at the tip of the feed roller nip (NIP) formed between the pair of feed rollers 24 so that the photosensitive member is arranged. Is transferred to (22). When a printing signal is transmitted to the image forming apparatus, a latent image having a predetermined shape is formed on the photosensitive member 22 by the optical scanning device 32, and the latent image is developed by the developing roller 20, and then the paper and the transfer roller. The desired image is transferred onto the paper by the potential difference in the transfer nip formed between the 26. Then, the image transferred to the paper is fixed while passing through the fixing roller nip formed between the pair of fixing rollers 28, and then discharged through a batch roller (not shown). In the drawing, reference numeral 30 denotes a paper detection sensor that detects the paper entry when the paper enters the feed roller 24 and controls the operation of the feed roller 24. On the other hand, one side of the photosensitive member 22 is receiving power from the motor, the other side of the photosensitive member 22 is provided with a power transmission device for transmitting power from the photosensitive member 22 to the transfer roller 26.

FIG. 2 is a diagram for describing a paper conveying method of an image forming apparatus having the above configuration as disclosed in US Patent No. 5,357,325.

Referring to Fig. 2, when the sheet is conveyed by the transfer roller 26, the transfer roller 26 and the photosensitive member 22 are prevented from being shaken by an impact or the like while the tip of the paper is caught by the fixing roller (28 in Fig. 1). The rotational speed of the transfer roller 26 is larger than the rotational speed of the photosensitive member 22 in the transfer nip formed between the two ends.

That is, if the radius of the photosensitive member 22 is R _D , the angular velocity of the photosensitive member 22 is ω _D , the minimum radius of the transfer roller 26 is R ', and the angular velocity of the transfer roller 26 is ω _T , _{The relationship D} x ω _D <R 'x ω _T holds.

When the above relationship is satisfied, the paper can be prevented from shaking from backlash between gears due to impact.

However, since the above paper conveying method controls only the speed of the transfer roller 26 according to the impact of the paper, the feed rollers (Fig. 1) when the paper is simultaneously held by the feed roller (24 in Fig. 1) and the transfer roller 26 at the same time. When the rotational speed of 24) is greater than the rotational speed of the transfer roller 26, the transfer roller 26 having a small inertia force is primarily pushed out by the curvature stress of the paper, resulting in image shaking and 22) flow occurs between the backlash between the gears, resulting in a change in image length and a cause of jitter.

Then, the rotation of the fixing roller (28 in FIG. 1) when the paper is stuck between the transfer roller nip, the transfer nip and the fixing roller nip or between the transfer roller 26 nip and the fixing roller (28 in FIG. 1) nip. When the speed is greater than the rotational speed of the transfer roller 26, the transfer roller 26, which is also small inertia force, is pushed out primarily to cause image shaking, and the photosensitive member 22 has a flow between backlash between gears. And, consequently, provide a cause of the change in image length and jitter.

The present invention has been made to solve the above problems, and provides a paper conveying method of the image forming apparatus that improves the change in the length of the image and jitter by adjusting the rotation speed between the transfer roller, the transfer roller and the fixing roller. There is a purpose.

1 is a schematic configuration diagram of a general image forming apparatus.

2 is a view for explaining a conventional paper transfer method in the image forming apparatus.

3 is a view for explaining a paper transfer method according to the present invention in the image forming apparatus.

<Description of the symbols for the main parts of the drawings>

120 ... developing roller 122 ... photosensitive member

124 ... Transfer roller before transfer 126 ... Transfer roller

128 ... Fixing roller 130 ... Paper sensor

132 ... Optical scanning device

In accordance with the present invention to achieve the above object,

A transfer roller for transferring an image formed on the photosensitive member to the paper while rotating facing the photosensitive member, a fixing roller for fixing the image transferred to the paper by the transfer roller, and a transfer nip formed between the photosensitive member and the transfer roller. In the paper conveying method of the image forming apparatus having a conveying roller for conveying the sheet,

When the linear velocity of the outer circumferential surface of the transfer roller is V _T , the linear velocity of the outer circumferential surface of the fixing roller is V _F , and the linear velocity of the outer circumferential surface of the feed roller is V _R , a relation of V _T ≥ V _R ≥ V _F is satisfied.

Here, the difference between the linear velocity V _T on the outer circumferential surface of the transfer roller and the linear velocity V _R on the outer circumferential surface of the transfer roller is preferably 2% or less.

In addition, the difference between the linear velocity V _T on the outer circumferential surface of the transfer roller and the linear velocity V _F on the outer circumferential surface of the fixing roller is preferably 5% or less.

According to such a paper conveying method of the image forming apparatus according to the present invention, it is possible to improve the image jitter generated in the transfer unit during paper conveyance and to obtain a uniform image quality.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view for explaining a paper transfer method according to the present invention in the image forming apparatus.

Referring to FIG. 3, an image forming apparatus includes a photosensitive member 122 that is charged and rotated at a predetermined voltage, and a photorefractive device that forms an electrostatic latent image of a desired image by scanning light to the photosensitive member 122 to form a relative voltage difference. 132, a developing roller 120 for developing a latent electrostatic image formed on the photosensitive member 122 to form a toner image, and an image formed on the photosensitive member 122 while being rotated to face the photosensitive member 122, onto paper. A transfer roller 126, a pair of feed rollers 124 for transferring paper between the photosensitive member 122 and the transfer roller 126, and image heat transferred to the paper by the transfer roller 126; A pair of fixing rollers 128 for fixing by applying pressure are provided.

Reference numeral 130 denotes a paper detection sensor that detects the paper entry when the paper enters the feed roller 124 and controls the operation of the feed roller 124. On the other hand, although not shown in the figure, one side of the photosensitive member 122 is provided with a gear that receives power from the motor, the other side of the photosensitive member 122 transmits power from the photosensitive member 122 to the transfer roller 126. A power transmission device is provided.

In the above configuration, the sheet picked up by the pick-up roller (not shown) from the paper feed cassette or the paper feed tray by the pick-up roller (not shown) is aligned at the tip of the feed roller nip (NIP) formed between the pair of feed rollers 124 so that the photosensitive member It is transferred between the 122 and the transfer roller 126. Then, when a print signal is transmitted to the image forming apparatus, an electrostatic latent image having a predetermined shape is formed on the photosensitive member 122 by the optical scanning device 132, and the electrostatic latent image is developed by the developing roller 120, thereby forming the photosensitive member 122. A toner image is formed on. Subsequently, the image formed on the photosensitive member 122 is transferred to the paper in the transfer nip formed between the photosensitive member 122 and the transfer roller 126. Then, the image transferred to the paper is fixed while passing through a fixing roller nip formed between a pair of fixing rollers 128, and then discharged through a discharge roller (not shown).

In the process of conveying the paper as described above, according to the paper transport method according to the present invention satisfies the following relationship.

V _T ≥ V _R ≥ V _F

Here, V _T is the linear speed of the outer peripheral surface of the transfer roller 126 to rotate in the transfer nip, V _R is the linear speed of the outer peripheral surface of the feed roller 124 to rotate in the transfer roller nip, V _F is rotated in the fixing roller nip The linear velocity of the outer peripheral surface of the fixing roller 128.

Thus, according to the same equation, the transfer roller 126, the linear speed of the outer peripheral surface V _T is the transport roller 124, the linear speed of the outer peripheral surface V _R greater than or equal to, the transfer roller 124, the linear speed of the outer peripheral surface V _R is the fixing roller (128 ) It is greater than or equal to the linear velocity V _F of the outer circumferential surface.

On the other hand, in the above relation, the difference between the linear speed V _T on the outer circumferential surface of the transfer roller 126 and the linear speed V _R on the outer circumferential surface of the transfer roller 124 is preferably 2% or less, and the line on the outer circumferential surface of the transfer roller 126. The difference between the speed V _T and the linear speed V _F at the outer peripheral surface of the fixing roller 128 is preferably 5% or less.

When the above relation between the transfer roller 126, the transfer roller 124, and the fixing roller 128 is satisfied, first, the conveying speed of the paper in the transfer roller 126 is equal to or faster than that of the transfer roller 124. Therefore, there is no blur between backlash between the photosensitive member 122 and the components of the power transmission device provided on the transfer roller 126 on the paper supplied from the transfer roller 124 to the transfer roller 126, thereby obtaining a uniform image. .

In addition, when the paper is caught by the fixing roller 128, since the speed of the fixing roller 128 is equal to or slower than the speed of the transfer roller 126, any external influence is exerted between the parts of the power transmission device provided on the photosensitive member 122. Since power is transmitted without being received, the change of the image can be eliminated.

Although the preferred embodiment according to the present invention has been described above, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

As described above, according to the paper transfer method of the image forming apparatus according to the present invention, the linear velocity of the outer circumferential surface of the transfer roller is equal to or greater than the linear velocity of the outer circumferential surface of the transfer roller during paper transfer, and the linear velocity of the outer circumferential surface of the feed roller is fixed. By making it larger than or equal to the linear velocity of the outer circumferential surface of the roller, image jitter generated in the transfer portion can be improved and uniform image quality can be obtained.

Claims (3)

A transfer roller for transferring an image formed on the photosensitive member to the paper while rotating facing the photosensitive member, a fixing roller for fixing the image transferred to the paper by the transfer roller, and a transfer nip formed between the photosensitive member and the transfer roller. In the paper conveying method of the image forming apparatus having a conveying roller for conveying the sheet, When the linear velocity of the outer peripheral surface of the transfer roller is V _T , the linear velocity of the outer peripheral surface of the fixing roller is V _F , and the linear velocity of the outer peripheral surface of the feed roller is V _R , A paper transfer method of an image forming apparatus, characterized by satisfying a relational expression of V _T ≥ V _R ≥ V _F. The method of claim 1, And the difference between the linear velocity V _T on the outer circumferential surface of the transfer roller and the linear velocity V _R on the outer circumferential surface of the transfer roller is 2% or less. The method of claim 1, And the difference between the linear velocity V _T on the outer circumferential surface of the transfer roller and the linear velocity V _F on the outer circumferential surface of the fixing roller is 5% or less.