JPH071414B2 - Image forming device - Google Patents

Description

The present invention relates to a transfer material conveying device, and more particularly, to an image forming apparatus using an electrostatic transfer process such as an electrophotographic copying machine and a printer.

[Conventional technology]

A transferable toner image is formed on the surface of a running image carrier, and a transfer material mainly composed of paper that travels in synchronization with the image carrier is brought close to or in contact with the toner image on the surface of the image carrier to transfer the toner image. An image forming apparatus configured to transfer a transfer material to a material, separate the transfer material from the image carrier, and transfer the transfer material to a fixing portion via an appropriate conveying means is well known in the art.

By the way, various types of fixing devices have been conventionally proposed as a fixing device for fixing a toner image to a transfer material, but in recent years, a pair of rollers are pressed against each other and at least one roller is heated to transfer the toner to the transfer material. Heating / pressurizing method to melt and adhere to
Alternatively, a pressure fixing method of fixing only by pressure without heating means is widely used.

In other words, when such an image forming apparatus is viewed from the transfer material side, the transfer material is given a conveying action in order to move synchronously with the transfer position at a transfer position close to the image carrier, and then, after separation, a transfer belt or the like. The transporting action also acts on the transfer material even by the transporting means, and the transporting action also acts on the transfer material by passing between the pair of rollers that are in pressure contact with each other at the fixing portion, and the transfer action is performed at at least three places. A conveying force acts on the material.

Of course, when the image forming apparatus is large or the transfer material is very small and the transfer force at each of these parts acts on each independent transfer material, there is no particular problem. However, for example, as seen in an electrophotographic copying machine. With the rapid downsizing of equipment in recent years, even when the paper, such as A4 size or less, which is usually used most often, is used as the transfer material,
It is unavoidable that the front end of the transfer material after the transfer reaches the roller pair at the fixing portion, but the rear end still exists at the transfer portion.

In such a state, as described above, the respective portions that impart the conveying force to the transfer material mutually affect each other, and this is merely attached to the transfer material by the electrostatic attraction force. The inconvenience of disturbing an unstable toner image occurs.

For example, when the transfer material enters the pressure contact roller pair at the fixing portion, the load applied to the roller pair at that moment increases, and the rotation speed of the roller sharply decreases. This tends to push back in the direction, and the synchronization between the image bearing member and the transfer material is temporarily lost, which adversely affects the transfer.

Also, particularly when pressure fixing means is adopted, as is well known, the roller pair that presses each other in order to make the pressing force on the transfer material as uniform as possible over its entire length,
It is well known that some rollers are arranged such that their axes intersect at a small angle. However, in such a case, if the transfer material is sandwiched between the rollers, a uniform transfer action does not work in the width direction of the transfer material (the longitudinal direction of the roller), and the transfer material tends to deviate from the original traveling direction. For this reason,
On the upstream side (as viewed in the running direction of the transfer material), one side edge of the transfer material is bent and deformed, which, in combination with the elasticity of the transfer material itself, causes a gap between the transfer material part in the transfer part and the image bearing surface. It may occur and adversely affect the image quality.

Further, in this type of image forming apparatus, it is common to provide a space as wide as possible in the upper part of the conveying means so that the transfer material does not accidentally collide with various parts inside the apparatus. When the apparatus is downsized, such a problem becomes difficult, and the curved transfer material may collide with the internal member.

In order to avoid the above-mentioned drawbacks, it has been proposed to provide means by means of spur-shaped rollers having needle-like protrusions formed around them. However, it is suitable when the transfer material is smaller than the device, but when the transfer material exists from the transfer portion to the fixing portion as described above, the force is weak with a spur-shaped roller or the like. Therefore, it has a drawback that it cannot be pressed down by a strong transfer material such as a thick transfer paper or a plastic sheet.

As another method, it has been proposed to provide a pressing roller in the conveyance path. However, the unfixed toner adhered to the pressing roller and the trace thereof was generated on the transfer material.

[Object of the Invention]

The present invention has been made in view of such a current situation,
By sufficiently pressing and supporting the transfer material in the transport section, the influence of irregular running of the transfer material that occurs in the fixing section can be reliably prevented from reaching the transfer section, and unfixed toner may adhere to the pressing member. An object of the present invention is to provide an image forming apparatus capable of preventing such occurrence.

[Structure for achieving the purpose]

The configuration of the present invention for achieving the above-mentioned object includes an image forming unit that forms a toner image on a transfer material, and an image forming unit that presses the transfer material so that the toner image formed on the transfer material is fixed to the transfer material. A fixing roller pair that is sandwiched and conveyed, and a transfer material that is disposed between the image forming unit and the fixing roller pair and that is sent to the fixing unit, carries an unfixed toner image formed by the image forming unit. The surface of the pressing roller that comes into contact with the surface on which the unfixed toner image is carried is a rough uneven surface having a surface roughness d = 0.1 to 10.0μ. An image forming apparatus characterized by the above.

〔Example〕

FIG. 1 is a schematic side view showing an embodiment in which the present invention is applied to a copying machine having a pressure fixing device.

On the transferable toner image formed on the surface of the image carrier (photoreceptor) 1 formed in a cylindrical shape that rotates in the direction of arrow A, a transfer material supplied from a supply unit (not shown) is transferred to the transfer unit 4 as toner. Accept the image. After that, the transfer material is separated from the photoconductor 1 and advances to the left side in the figure on the conveyor belt 6, and then passes through the fixing device 9 including the roller pairs 9a and 9b that are in pressure contact with each other and is discharged to the outside of the device. It

An electrostatic latent image forming unit 2, a developing unit 3 that visualizes the electrostatic latent image, a transfer unit 4, a cleaner unit 5, and the like are provided around the photoconductor 1.

In addition to the above-mentioned structure, a pressing roller 8 is further arranged in a proper position in the conveying system, and is pressed against the lower roller 7 by a spring or the like (not shown) so that the pressing roller 8 and the lower roller 7 are paired with each other, and the arrow direction Rotate to press the transfer material and transport it.

FIG. 2 is a plan view of the transport system, in which a wide belt 6 for transporting the transfer material is provided at the center, and a pair of pressing roller members for pressing and rotating the transfer material are provided on both sides of the wide belt 6. The driving sources of the two drive in parallel with each other to carry. A support guide 10 for supporting the transfer material is arranged around the pressing roller.

The pressing rollers 8a and 8b are in contact with the surfaces of the lower rollers 7a and 7b.

The transport apparatus according to the present invention is configured as described above, and some embodiments will be described below.

The conveyor belt 6 is a rubber belt having a volume resistance of 10 ¹² Ω · cm or more, and may have a flat surface shape or an uneven shape in order to improve the conveyance property.

The lower rollers 7a and 7b have a two-layer structure or only a rigid body around the cored bar, which is composed of an elastic layer having elasticity such as rubber having a thickness of 1.0 to 3.0 mm and a cored bar.

The pressing roller 8 is pressed against the lower roller 7 by a pressing force of about 400 gr by a coil spring or the like. The surface of the pressing roller has a surface roughness of 0.1 to 10.0 μ. By controlling the roughness within this range, very little toner adheres to the surface of the pressing roller 8.

Usually, the toner has an average particle size of 10.0 μ or less. for that reason,
When the surface of the pressing roller 8 is 10.0 μ or more, the toner enters the gap and the toner on the transfer material is easily peeled off. When the toner adheres to the pressing roller 8, the toner is further peeled off due to the cohesive force of the toners. Therefore,
A trace of the toner peeled off remains on the unfixed portion, resulting in a defective image. Therefore, the pressure roller surface must be 10.0μ or less. Further, if it is 0.1 μm or less, the surface is too smooth and slips on the transfer material, and the relative speed is deviated and the image is disturbed. Therefore, the surface roughness is within 0.1 to 10.0 μ. Desirably, if it is 0.1 to 5.0 μ, the effect becomes more desirable.

The material of the pressing roller 8 may be a metal such as steel, brass, stainless steel or the like, or a plastic rigid body such as polyacetal resin, polyethylene resin or polyamide resin. Further, the same applies to a double structure in which a metal is used as a core metal portion and a plastic is used as a surface layer.

FIG. 3 shows another embodiment of the present invention. Instead of the lower roller, a supporting member 11 is provided, and on the supporting member 11, there is a rotatable belt. 8 is pressed. The transfer material passes between the pressing roller 8 and the belt 6.

FIG. 4 also shows another embodiment, in which the transport section is formed on a fixed transport guide 12, and only the portion where the pressing roller 8 contacts is flat. An uneven portion 12a (Fig. 5) is formed on the surface of the other portion, and the convex portion serves as a guide.

Here, the surface roughness is JIS 10-point average roughness (Rz) [JIS
B 0601]. That is, as shown in FIG. 6, a straight line parallel to the average line A of a portion extracted from the cross-section polar line by the reference length l and passing through the third peak from the highest (shown in the figure) and the deep one Although it passes through the third valley bottom (indicated by'in the figure) from, the distance between two straight lines is expressed in micrometers (μm), and the reference length l = 0.25 mm. The pitch of the pitch is 0.1
Those with a height of μ or more are counted as one mountain, and the reference length is 0.
It was calculated from the number of mountains in 25 mm.

The present invention presses and conveys the transfer material conveyed in the conveying section until it reaches the fixing section away from the transfer section, and the surface of the pressing roller has a roughness within a certain range. It is something that is being connected.

By adopting such a constitutional means, it is possible to prevent the transferred transfer material from having a bending tendency at its tip or in the vicinity thereof and absorbing these at the portion of the pressing roller to affect the transfer portion. . Furthermore, by setting the surface roughness of the pressing roller in contact with the unfixed surface within a certain range, the toner is not adhered from the transfer material to the pressing roller or the image is not disturbed due to the displacement of the transfer material. There is an effect. Therefore, a good quality image can be obtained.

〔The invention's effect〕

In the image forming apparatus of the present invention, the transfer material is pressed between the image forming means and the pair of fixing rollers by the pressing roller having the roughened surface having the surface roughness d = 0.1-10.0 μ as the outer peripheral surface. It is possible to reliably prevent the influence of irregular running of the transfer material caused by the roller pair from reaching the image forming portion, and also to prevent unfixed toner from adhering to the pressing roller or toner attached to the pressing roller from adhering to the transfer material. Can be prevented.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a carrying device according to the present invention, and FIG.
The same drawing is a plan view, FIG. 3 is a side view of another embodiment, and FIG.
FIG. 5 is a side view of still another embodiment, and FIG. 5 is an AA of FIG.
FIG. 6 is a cross-sectional view in the direction of the arrow, showing the surface roughness curve. 4 Transfer unit 6 Transport belt 7 Lower roller 8 Press roller 9 Fixing device

Continuation of front page (56) References JP-A-60-121478 (JP, A) JP-A-57-41660 (JP, A) JP-A-60-83061 (JP, A) JP-A-60-146278 (JP , A) JP 60-175068 (JP, A) JP 61-90167 (JP, A) JP 61-291344 (JP, A) JP 58-207066 (JP, A) JP 61-192658 (JP, A) JP-A-56-167169 (JP, A) JP-A-57-158864 (JP, A) JP-A-52-67641 (JP, A) JP-B-59-36749 (JP, A) B2) Japanese Patent Publication 5-48917 (JP, B2) Jikho Sho 57-8035 (JP, Y2) Jikkou 4-23243 (JP, Y2)

Claims (1)

[Claims] 1. An image forming means for forming a toner image on a transfer material, and a pair of fixing rollers for pressing the toner image on the transfer material and fixing the toner image on the transfer material. And a surface of the transfer material, which is arranged between the image forming unit and the fixing roller pair and is sent to the fixing unit, carrying the unfixed toner image formed by the image forming unit, while pressing the surface. An image forming method comprising: a pressing roller, wherein a surface of the pressing roller that comes into contact with a surface carrying an unfixed toner image is an uneven rough surface having a surface roughness d = 0.1 to 10.0 μ. apparatus.