JPH08240954A - Image forming method and device - Google Patents

Abstract

PURPOSE: To prevent image crawling or image deviation from occurring by making the carrying speed of a transfer material to a transfer part on the upstream side from a transfer means higher than the circumferential speed of an image carrier by a specified ratio. CONSTITUTION: The transfer material 6 is allowed to pass between a photoreceptor drum 1 having the superposed toner image of two or more colors and a transfer roller 5, so that the toner image is electrostatically collectively transferred on the transfer material 6 altogether. It is satisfactory that the roller 5 is allowed to be in close contact with/separated from the drum 1, and a developing device is a non-contact developing means and a reversal developing means. Furthermore, it is satisfactory that the radius of curvature of the drum 1 at least at a transfer or separation part is >=40mm. The carrying speed of the transfer material 6 by a resist roller 10 set on the upstream side from the roller 5 is made higher than the circumferential speed of the drum 1 by about 0.05 to 4.5%. Thus, the contact of the transfer material 6 with the drum 1 becomes excellent, discharge is hardly caused between the drum 1 and the transfer material 6, the image crawling hardly occurs, and an appropriate density range becomes wider.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and apparatus,
In particular, the present invention relates to an image forming method and apparatus capable of preventing image repelling (image loss) and image shift.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus, for example, JP-A-63-202541 and JP-A-5-29773.
1 and Japanese Patent Laid-Open No. 5-333632.

FIG. 8 is an explanatory view of a conventionally known image forming apparatus, in which 1 is an image carrier (photosensitive drum or photosensitive belt) capable of carrying an electrostatic latent image on its outer periphery, and 2 is the photosensitive member. A charger 3 arranged to face the outer periphery of the drum 1 for charging the outer periphery of the photosensitive drum 1 also develops the electrostatic latent image formed on the photosensitive drum 1 by image exposure 4. Developing devices for forming toner images of different colors, 5 are transfer means such as a transfer roller for electrostatically collectively transferring the toner images on the photosensitive drum 1 onto the transfer material 6, and 7 is also the same. A separator for separating the transfer material 6 from the photoconductor drum 1, a cleaning blade 8 for removing toner remaining on the photoconductor drum 1, a pre-charging exposure means (PCL) 10 and a transfer 10 Upstream side resist for transporting material 6 Roller, 11 similarly shows the downstream registration roller.

[0004]

However, in such a conventional image forming apparatus as described above, the transfer material 6 such as paper enters between the transfer means 5 and the photosensitive drum 1 especially in a low temperature and low humidity environment. Image dropout called image repellency (transfer repellency) occurs due to electric discharge generated between the transfer unit, the transfer material, and the photosensitive drum.

That is, this phenomenon is caused by the discharge 12 generated between the photosensitive drum 1 and the transfer material 6 as shown in FIG.
By reversing the polarity of the toner and the electric potential on the photoconductor drum 1, a transfer root is generated at that portion, and when the image is seen, there are spots such as missing dots.

Further, when toner is transferred in a state of being superposed on the photosensitive drum 1, image deviation occurs particularly well, and the peripheral speed of the registration roller 10 on the upstream side of the peripheral speed of the photosensitive drum 1 is higher than that of the peripheral speed. Image shift occurs even when it is slower.

As a result of various experiments and studies, the present inventor has found that it is effective to bring the transfer material into close contact with the photosensitive drum before transfer in order to eliminate image repelling.

The present invention has been made based on such knowledge.

[0009]

In the image forming method of the present invention, a transfer material is passed between an image carrier having a toner image of two or more colors superposed and a transfer means, and the toner image is transferred onto the transfer material. In the image forming method of electrostatically transferring all of the particles at a time, the conveying speed of the transfer material on the upstream side of the transfer means to the transfer portion is 0.05 to 4.5% faster than the peripheral speed of the image carrier. .

Further, in the image forming method of the present invention, a transfer material is passed between an image carrier having a toner image of two or more colors of superimposed toners and a transfer means, and the toner image is electrostatically transferred onto the transfer material. In the image forming method in which the transfer is performed collectively on the transfer roller, the peripheral speed of the registration roller for conveying the transfer material, which is installed on the upstream side of the transfer unit, is set to 0.05 to 4.5 than the peripheral speed of the image carrier. % Make it faster.

Further, the image forming apparatus of the present invention comprises an image carrier capable of forming an electrostatic latent image, and a developing means for carrying out superimposing development of two or more colors on the image carrier with charged toner.
In an image forming apparatus including a transfer unit that electrostatically collectively transfers the toner image obtained by the development onto a transfer material, in a transfer unit of the transfer material on the upstream side of the transfer unit with respect to the peripheral speed of the image carrier. Transport speed until entering is 0.05 ~
Make it 4.5% faster.

The image forming apparatus of the present invention is obtained by the above-mentioned development, and an image carrier capable of forming an electrostatic latent image, a developing means for carrying out superimposing development of two or more colors with charged toner on the image carrier. In an image forming apparatus comprising a transfer means for electrostatically transferring a toner image onto a transfer material at one time and a registration roller for conveying the transfer material, which is installed on the upstream side of the transfer means. The speed is made 0.05 to 4.5% faster than the peripheral speed of the image bearing member.

The image bearing member is a photosensitive drum or a photosensitive belt. As the photosensitive drum here, Se, A
Materials such as s ₂ Se ₃ , a-Si and OPC are used.
Especially as OPC used here, JP-A-64-17
It is preferable to use Y-type titanyl phthalocyanine or polycrystalline titanyl phthalocyanine described in JP-A No. 066, JP-A-2-183258, JP-A-2-183265 and JP-A-3-128973.

The transfer means is in close contact with and separated from the image carrier.

The developing means is an image carrier for carrying an electrostatic latent image and a two-component developing means for superimposing a DC component and an AC component on a developing region carrying a two-component developer.

The developing means is a non-contact developing means.

The developing means is a reversal developing means.

The image carrier has a radius of curvature of 40 mm or more at least at the transfer or separation portion.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, the transfer speed of the transfer material 6 to the photosensitive drum 1 is set to be about 0.05 to 4.5% faster than the peripheral speed of the photosensitive drum 1.

More specifically, the upstream registration roller 1
The transfer speed of the transfer material 6 by 0 is set to be about 0.05 to 4.5% faster than the peripheral speed of the photosensitive drum 1.

Table 1 shows the case where paper is used as the transfer material 6,
It shows the relationship between the paper conveyance speed and the occurrence of image repelling and image misalignment.

[0023]

[Table 1]

The transfer roller 5 used in this experiment is an ion conductive type manufactured by Sumitomo Rubber Industries, Ltd., hardness 30 (Asker C
Hardness meter), electric resistance of 7 × 10 ⁷ Ω, diameter of 16 mm.

The photosensitive drum 1 has a diameter of 120 mm,
The peripheral speed is 100 mm / sec.

The separator 7 is made of stainless steel and has a thickness of 0.1 mm, a tooth pitch of 2 mm, and a depth of 3 mm.
mm sawtooth electrodes were used.

Regarding the electric resistance value of the transfer roller, the transfer roller manufactured by each company (different in material or composition of components) has a diameter of 16 mm, a length of 310 mm, and a wall thickness of 4 mm. 170 g
When pressed with a force of / cm ² , the temperature is 20 ° C and the humidity is 50%.
Is an electric resistance value between the rotating shaft of the transfer roller and the aluminum base tube, measured under the environment.

In Table 1, A shows the case where a registration roller is used for conveying paper as shown in FIG. 1, and B shows the case where a conveyance belt is used as shown in FIG.

Further, ● indicates the occurrence of image repelling. X indicates that the image shift is large and it cannot be used practically. Δ indicates that the image shift is moderate. ○ indicates that the image shift is small and there is no problem in practical use. ⊚ indicates that there is no image shift. (X) indicates that the paper has wrinkles.
(XX) indicates that a jam occurred before transfer.

From Table 1 above, A is excellent in the paper conveyance property, but is weak in the peripheral speed with the photosensitive drum, and B is inferior in the paper conveyance property. It can be seen that although the speed is strong, image repelling easily occurs. Also,
It can be seen that image misalignment is more likely to occur on thick paper.

When the conveying speed of the paper 6 with respect to the photosensitive drum 1 is 0.05 to 4.5% faster, the paper 6 has a good adhesion to the photosensitive drum 1 as shown in FIG. However, there is almost no discharge 12 between the photosensitive drum 1 and the paper 6, and image repelling hardly occurs, so that the appropriate density range becomes wide as shown in FIG.

On the other hand, paper 6 is attached to the photosensitive drum 1.
When the conveyance speed of is slow, the paper 6 becomes the state of FIG.
Image repelling easily occurs due to the discharge 12 between the photoconductor drum 1 and the paper 6, and thus the appropriate density range is narrowed as shown in FIG.

When the paper 6 is conveyed at a speed of 6.5% or more with respect to the photosensitive drum 1, a jam (conveyance failure) occurs on most of the paper before transfer, as shown in FIG.

The image bearing member may be an intermediate transfer member.

FIG. 10 shows such an intermediate transfer body 1a. When the intermediate transfer body 1a is used, the electrostatic latent image formed on the rotated image carrier 1 is transferred to the developing device 3. The toner image is developed by charged toner to form a toner image, the toner image is transferred from the image carrier 1 to the intermediate transfer member 1a, and the transfer unit in which the intermediate transfer member 1a and the transfer roller 5 are in pressure contact with each other is a paper feeding unit. After the electrostatic transfer is performed on the transfer material 6 that is fed from and is energized, the transfer material 6 is unloaded.

[0036]

As described above, according to the image forming method and apparatus of the present invention, there is a great advantage that image repelling and image deviation can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part of an image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram of a main part of the image forming apparatus of the present invention.

FIG. 3 is an explanatory diagram of a main part of the image forming apparatus of the present invention.

FIG. 4 is an explanatory diagram of the device shown in FIG.

5 is an explanatory diagram for comparison of the device shown in FIG.

FIG. 6 is an explanatory diagram of the device shown in FIG.

FIG. 7 is an explanatory diagram for comparison of the image forming apparatus of the present invention.

FIG. 8 is an explanatory diagram of a conventional image forming apparatus.

9 is an explanatory view of the device shown in FIG.

FIG. 10 is an explanatory diagram of an image forming apparatus using an intermediate transfer member.

[Description of Reference Signs] 1 image carrier 1a intermediate transfer member 2 charging device 3 developing device 4 image exposure 5 transfer means 6 transfer material 7 separator 8 cleaning blade 9 pre-charging exposure means 10 upstream registration roller 11 downstream registration roller 12 Discharge

Claims (10)

[Claims] 1. An image forming method in which a transfer material is passed between an image carrier having a toner image of two or more colors and a transfer means, and the toner images are electrostatically collectively transferred onto the transfer material. An image forming method is characterized in that the conveyance speed of the transfer material on the upstream side of the transfer means to the transfer portion is 0.05 to 4.5% faster than the peripheral speed of the image carrier. 2. An image forming method in which a transfer material is passed between an image carrier having two or more superimposed toner images and a transfer means, and the toner images are electrostatically collectively transferred onto the transfer material. The peripheral speed of the registration roller for transporting the transfer material installed on the upstream side of the transfer means is set to be 0.05 to 4.5% faster than the peripheral speed of the image carrier. Image forming method. 3. An image carrier capable of forming an electrostatic latent image, developing means for carrying out superposed development of two or more colors on the image carrier with charged toner, and a toner image obtained by the development as a transfer material. In an image forming apparatus composed of transfer means for electrostatically transferring all at once, a transfer speed of the transfer material on the upstream side of the transfer means from the peripheral speed of the image carrier to the transfer portion is 0.05 to An image forming apparatus characterized by being 4.5% faster. 4. An image bearing member capable of forming an electrostatic latent image, developing means for carrying out overlapping development of two or more colors with charged toner on the image bearing member, and a toner image obtained by the developing as a transfer material. In an image forming apparatus comprising a transfer means for electrostatically transferring all at once and a registration roller for transporting a transfer material installed on the upstream side of the transfer means, the peripheral speed of the registration roller is the image carrier. The image forming apparatus is characterized in that it is 0.05 to 4.5% faster than the peripheral speed. 5. The image forming apparatus according to claim 3, wherein the image carrier is a photosensitive drum or a photosensitive belt. 6. The image forming apparatus according to claim 3, 4 or 5, wherein the transfer means is in close contact with or separated from the image carrier. 7. The developing means is an image carrier for carrying an electrostatic latent image and a two-component developing means for superimposing a DC component and an AC component on a developing area carrying a two-component developer. The image forming apparatus according to claim 3, 4, 5, or 6. 8. The image forming apparatus according to claim 3, wherein the developing means is a non-contact developing means. 9. The image forming apparatus according to claim 3, wherein said developing means is a reversal developing means. 10. The image forming apparatus according to claim 3, wherein the image carrier has a curvature radius of 40 mm or more at least at a transfer or separation portion. .