JPH03216689A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a transfer material from wrinkling and an image from blurring by specifying the relation among a conveying speed, the feed speed of a paper feed roller, the transfer speed of a transfer material after transfer, a fixation feed speed, and a discharge speed, and the relations amongst the frictional force by a discharge roll, the frictional force by a fixing roller, and the frictional force by the paper feed roller. CONSTITUTION:The conveying speed V1 of a photosensitive body 1, the feed speed V2 of the paper feed roller 5, the conveying speed V3 of a conveyor belt 19, the fixation feed speed V4 of a fixing roller 13, and the discharge speed V5 of the discharge roller 15 are so set that V1 = V2 = V3 <= V4 < V5. Further, the frictional force (holding force) F1 by the discharge roller 15 which operates on the transfer material 6, the frictional force F2 by the fixing roller 13 which operates on the transfer material 6, and the frictional force F3 by the paper feed roller 5 which operates on the transfer material 6 are so set that F1 + F2 <= F3. Consequently, the photosensitive body 1 and transfer material 6 are prevented from having a speed difference. Consequently, the transfer material is prevented from wrinkling and the image is prevented from blurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electronic copying machine or a printer. [Prior Art] Image forming apparatuses, such as electronic copying machines, are known in which an image formed on a photoreceptor by charging, exposure, and development is exposed and fixed, and is discharged by a discharge roller.

A pressure roller or a pressure belt that presses against the fixing roller is known as a pressure means in a fixing device, and the pressure roller or pressure belt may be driven by frictional contact with the fixing roller.

In a fixing device that uses this type of pressure means, setting the conveyance speed of the transfer material becomes a major issue.

Depending on the setting of the conveyance speed, there is a problem that wrinkles may occur on the transfer material during fixing or the image may bleed.

In order to prevent wrinkles on the transfer material and blurring of the image, the speed at which the fixing device transports the transfer material is set lower than the speed at which the photosensitive drum transports the transfer material. For example, Japanese Patent Laid-Open No. 52-70841 discloses that setting the transfer material conveyance speed to a small value
It is proposed by the publication No. In this embankment plan, the transfer material is slackened between the photosensitive drum and the conveyance device,
This is intended to prevent wrinkles in the transfer material by preventing tension from occurring in the transfer material at the transfer portion of the photosensitive drum, and further by creating tension between the conveying device and the fixing device.

When the fixing device is composed of a fixing roller and pressure means such as a pressure roller or a pressure belt, and the pressure means is any of various devices driven by frictional contact with the fixing roller, the transfer material is composed of the fixing roller and the pressure means. When the pressure means is inserted between the transfer material and the fixing roller, the pressure means comes into frictional contact with the fixing roller via the transfer material.

For this reason, in the case of a transfer material that is considerably narrower than the width of the fixing roller, there is a portion where the fixing roller and pressure means directly contact each other without the transfer material intervening, so the pressure means is the same as the fixing roller. The fixing rollers are moved at the same speed and the fixing material is also conveyed at a predetermined speed, but if the width of the transfer material is wide, the transfer material will be present in most of the width of the fixing roller, resulting in a problem. When slipping occurs in this way, the transfer material 5
1 is not conveyed at a predetermined speed by the fixing roller 52 and the pressure roller 53, and slack occurs at the entrance of the fixing roller 52. The unfixed toner image on the sagging transfer material will be rubbed by the fixing roller 52, causing smearing in the copied image. Furthermore, if the transfer material 51 becomes sagging, it becomes more likely to wrinkle. Furthermore, the degree of slack in the transfer material between the photosensitive drum and the conveyance device and the degree of tension between the conveyance device and the fixing device cumulatively increase in proportion to the length of the transfer material being conveyed. This method is not suitable for long transfer materials, and has the problem of requiring an additional device such as a suction device to firmly hold the transfer material as a conveying device. In other words, even the above proposal cannot completely solve the problem.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide an image forming apparatus that does not cause wrinkles in the transfer material or sagging of the image.

[Means to solve the problem]

The present invention solves the above problem in an image forming apparatus that fixes and discharges a transfer material to which a photoreceptor image has been transferred by a fixing device having a fixing roller and a pressure means for pressurizing the fixing roller transfer material. , a conveyance speed (■1) to the photoreceptor, a feed speed (■) of a paper feed roller that conveys the transfer paper to the photoreceptor,
Conveying speed ■3 for conveying the transfer material after transfer to the fixing device;
The fixing feed speed ■4 by the fixing roller of the fixing device and the discharge speed ■4 by the discharge roller are V, =V, =V. The relationship is set such that ≦V a < V s, and the frictional force Fl by the discharge roller acting on the transfer material,
The frictional force F2 due to the fixing roller and the frictional force F3 due to the paper feed roller are F + + F! This problem was solved by an image forming device that is set so that ≦F3. [Function] According to the present invention, the transfer material is fed by the paper feed roller, the photoreceptor, the conveying device, the fixing device, and the discharge roller, and transfer and fixing are performed during this time. At this time, the conveyance speed of the discharge roller is set higher than the conveyance speed of other parts, tension is applied to the transfer material, and the slippage of the pressure means against the fixing roller can be ignored. Therefore, the transfer material is fed to the fixing device without sagging, and wrinkles and smearing are prevented. Since the conveying speed due to the tensile force of the fixing device and the discharge roller is higher than the conveying speed of the photoreceptor, the transfer material being transferred is pulled, causing it to slide against the photoreceptor, resulting in image disturbance. This point is determined by the holding force of the paper feed roller against the transfer material (
(or frictional force) is set to be larger than the sum of the holding force by the fixing roller and the holding force by the discharge roller, and by maintaining a predetermined conveyance speed by the paper feed roller, slipping on the photoreceptor is prevented. As a result, when a tension greater than a predetermined tension is applied to the transfer material, the ejection roller idles, the transfer material is prevented from slipping against the photoreceptor, and an adverse effect on the transfer of the toner image from the photoreceptor is prevented.

〔Example] The details of the present invention will be explained based on the following embodiments.

In an electronic copying machine as an example of an image forming apparatus shown in FIG. An electrostatic latent image is formed by exposing the original image to light, and is developed by the developing device 4 to form a toner image as a developed image. The toner image on the photoreceptor 1 is transferred to a transfer material 6 fed by a paper feed roller 5 under the action of a transfer corona discharger 7 .

The transfer material 6 after transfer is transferred to the photoreceptor 1 by a separate corona discharger 8.
The image is then separated and sent to the fixing device 10 by the conveying belt device 9 to be fixed.

After the transfer, the photoreceptor 1 is cleaned of residual toner by a cleaner 11, neutralized by a static elimination lamp 12, and the next image forming process starting from charging by a corona discharger 2 is repeated. The transfer material 6 is fed by the paper feed roller 5, guided by the paper guide l6, and sent to the transfer position by the photoreceptor 1. After the transfer, the transfer material 6 is transported by the conveyance device 9, and is then processed by the fixing roller l3 of the fixing device 10. Pressure roller 1 as pressure means
4 and is heated and pressurized to fix it, and then the discharge roller 1
5, it is fed and discharged. The conveying device 9 has a conveying belt l9 wrapped around a driving roller 17 and a guide roller 18, and the transfer material 6, which is sandwiched and pulled between the fixing roller l3 and the pressure roller 14, is stretched between the paper guide I6 and exposed to light. It is sent so that it touches body 1. If the transfer material 6 is undulated at this time, the contact with the photoreceptor 1 becomes unstable and transfer omission occurs.In order to prevent this instability, the transfer material 6 is placed at a position immediately after it leaves the photoreceptor 1. A guide roller 18 is disposed or a guide plate is provided so as to push up the transfer material slightly above the common tangent between the paper guide 16, the photoreceptor 1, and the fixing roller l3, for example, above 1 to 2.

The conveyor belt 19 is inclined so as to gradually descend downstream in the feeding direction of the transfer material 6, and the leading edge of the transfer material 6 conveyed by the conveyor belt 19 is guided by the guide plate 20 to the fixing roller 1.
3 and then passed between the fixing roller 13 and the pressure roller 14. The conveyance speed ■ of the photoconductor l, the conveyance speed v2 of the paper feed roller 5, the conveyance speed ■of the conveyance belt 19, the fixing feed speed ■4 of the fixing roller 13, and the discharge roller 1.
The discharge speed V, according to No. 5, is set to be V, =V, =V3≦v4×v, Therefore, after the leading edge of the transfer material 6 is passed between the fixing roller 13 and the pressure roller l4, As the transfer material is stretched between the fixing roller 13 and the guide roller 18, it becomes separated from the conveyor belt 19.

Since the transfer material is sent at the fastest speed by the discharge roller 15, even if there is slippage on the transfer material due to frictional drive between the fixing roller l3 and the pressure roller l4, the transfer material will be transferred without taking this into account. The transfer material is fed and the transfer material is prevented from sagging. By setting the frictional force F2 acting on the transfer roller 6 and the frictional force F acting on the transfer material 6 at the paper feed roller 5 so that F+ +Fx≦F, the tensile force due to the fast discharge roller l5 is reduced. Even if the transfer material is pulled by the tensile force of the fixing roller, the transfer material is firmly held by the feed roller 5, and a speed difference between the photoreceptor 1 and the transfer material 6 is prevented from occurring. This prevents image distortion.

The speed difference acting on the transfer material between the ejection roller l5 and the paper feed roller 5 is compensated by everything between the ejection roller 15 and the transfer material 6. As the pressure means of the fixing device 10, in contrast to the example of the pressure roller 4 shown in FIG. 1, as shown in FIG.
It is also possible to use a pressure belt 14' wrapped around and 22.

〔effect〕

According to the present invention, wrinkles and image smearing are prevented from occurring on the transfer material.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to the present invention, FIG. 2 is an explanatory diagram of a modified example of a fixing device, and FIG. 3 is an explanatory diagram showing a state in which sagging occurs in a transfer material of a conventional fixing device. DESCRIPTION OF SYMBOLS 1... Photoreceptor 5... Paper feed roller 6... Transfer material 7... Transfer corona discharger 9... Conveyance belt device IO... Fixing device 13... Fixing roller 14...
・Pressure roller (pressure means) 14'... Pressure belt (pressure means) 15... Discharge roller

Claims (1)

[Scope of Claims] An image forming apparatus that fixes and discharges a transfer material onto which an image on a photoreceptor has been transferred by a fixing device having a fixing roller and a pressure means that presses the transfer material to the fixing roller, comprising: conveyance speed V_1 of the paper conveyance roller that conveys the transfer material to the photoreceptor, conveyance speed V_3 that conveys the transfer material after transfer to the fixing device, and fixing feed by the fixing roller of the fixing device. The speed V_4 and the discharge speed V_5 by the discharge roller are V_1=V_2=V_3≦
The relationship is set to be V_4<V_5, and the frictional force F_1 due to the discharge roller acting on the transfer material, the frictional force F_2 due to the fixing roller, and the frictional force F_3 due to the paper feed roller are F_1+F_2.
An image forming apparatus characterized in that the image forming apparatus is set such that ≦F_3.