JPH0462575A - Carrier for multicolor image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 1 bundle to Nagi Tatsufuda] The present invention includes a registration roller that conveys a transfer material to an image transfer section at a predetermined timing, and a transfer section conveyance device that conveys the transfer material in the image transfer section. The present invention relates to a conveyance device for a multicolor image forming apparatus that has a transfer material and transfers images of a plurality of colors onto a transfer material in an overlapping manner.

Traditionally, in multicolor image forming devices such as color copying machines, paper is fed from a paper feed section, passes through a transfer section and a fixing section in order, and then the transfer material on which the image is formed is discharged outside the machine. A conveyance device is provided that conveys the transfer material along a series of conveyance paths. The conveyance device includes a plurality of conveyance members that are adjacent to each other along the conveyance path, such as a paper feed roller of a paper feed member, a registration roller, a transfer conveyance belt, a fixing roller, a paper ejection roller, etc. between the roller and the transfer conveyor belt.
If there is a difference in the conveying speed of the transfer material, image blurring, rubbing, etc. will occur, and the image quality will deteriorate. In the case of the above-mentioned color copying machine, this problem causes not only blurring and scratches but also color tone unevenness, color shift, etc., and the color image quality is significantly deteriorated.

In general, the motors for the conveyor belt and registration rollers in the transfer section are controlled by PLL control, etc., but rotational irregularities caused by the drive transmission system and the diameters of the transfer roller and registration roller for the transfer section conveyance belt may be affected. Conveyance speed differences tend to occur due to speed differences caused by errors.

In consideration of this problem, a method has been proposed in which a surface speed detection means of the transfer belt is provided and the drive motor is controlled by a signal from this detection means, for example, in Japanese Patent Application Laid-open No. 62-242964. Speed differences are unavoidable depending on the accuracy and precision of the registration roller diameter. In order to prevent this difference in linear speed, the publication proposed that an adsorption charger be installed upstream of the transfer section of the transfer belt, the transfer material should be adsorbed to the transfer belt in advance, and the transfer material should be transported at the same speed as the transfer belt. has been done.

In this case, which the invention aims to solve, in order to charge the transfer material in advance, it is necessary to increase the transfer voltage in order to transfer the image on the image carrier to the transfer section, and especially for color images. When performing multiple transfers, it is necessary to increase the transfer voltage for each transfer, which results in a considerably high voltage, which is undesirable from a safety standpoint. In addition, the adsorption force for adsorbing the transfer material to the transfer belt due to charging is proportional to the contact area, so at the leading edge of the transfer material, the nipping and conveying force of the registration rollers is greater than the adsorption force, and the speed of the transfer material increases. It depends on the transport speed of the parts. Particularly when the paper pressure is thick, the paper is stiff and therefore tends to depend on the conveyance speed of the paper feed unit. In order to prevent this, the distance from the adsorption charger to the transfer section can be increased, but this poses a problem in that the machine becomes larger.

SUMMARY OF THE INVENTION An object of the present invention is to provide a conveying device for a multicolor image forming apparatus that can solve the above-mentioned conventional problems and can prevent image quality from deteriorating due to differences in linear speed with a simple configuration.

to solve the problem The structure of the present invention that achieves the above object is as follows.

A multi-color system that includes a registration roller that conveys a transfer material to an image transfer section at a predetermined timing and a transfer section conveyance device that conveys the transfer material at the image transfer section, and that transfers images of multiple colors onto the transfer material in an overlapping manner. In the conveyance device of the image forming apparatus, the linear speed of the registration roller is set to be slower than the linear speed of the transfer unit conveyance device, and a conveyance path length is set in a conveyance guide section between the registration roller and the transfer unit conveyance device. 1. A conveyance device for a multicolor image forming apparatus, comprising an elastic displacement member movable between a first position where the length of the conveyance path is extended and a second position where the length of the conveyance path is shortened.

According to the above configuration, the linear speed of the registration roller is set lower than the linear speed of the transfer unit conveyance device, and the conveyance path length is extended in the conveyance guide section between the registration roller and the transfer unit conveyance device. By providing an elastic displacement member that is movable between a first position where the conveyance path length is shortened and a second position where the conveyance path length is shortened, when the transfer material is pulled under the conveyance action of the transfer unit conveyance device, the elastic displacement member The displacement member is displaced from the first position to the second position, and the length of the conveyance path is shortened, so that the tension of the transfer material can be absorbed.

outside of class 11 Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows a color copying machine to which the present invention is applicable.

In FIG. 1, the color copying machine includes a scanner section 1 for reading originals, an image processing section 2 that electrically processes image signals output as digital signals from the scanner section 1, and an image processing section 2 that electrically processes image signals output as digital signals from the scanner section 1. The printer section 3 forms an image on copy paper as a transfer paper material based on the image recording information of each color. The scanner part 1 has a lamp 5, such as a fluorescent lamp, for scanning and illuminating the document on the document table 4.

The reflected light from the document when illuminated by the fluorescent lamp 5 is
The light is reflected by the mirror 6.7.8 and enters the imaging lens 9. The image light is focused on the dichroic prism 10 by the imaging lens 9, for example, red R, green G.
, blue B, and enters the light receiver 11 for each wavelength, for example, CGDIIR for red, CCD 11G for green, and CCDIIB for blue. Each CCDIIR5IIG, 11B converts the incident light into a digital signal and outputs it, and the output is sent to the image processing unit 2.
The necessary processing is performed to record color information for each color, such as black (hereinafter abbreviated as Bk) and yellow (abbreviated as Y).
, magenta (abbreviated as M), and cyan (abbreviated as C).

Although FIG. 1 shows an example of forming images in four colors, Bk, C, M, and Y, it is also possible to form a color image using only three colors. In that case, the number of recording devices can be reduced by one compared to the example shown in FIG.

The signal from the image processing section 2 is input to the printer section 3,
Laser light emitting devices 12Bk, 12C, 1 for each color
Sent to 2M and 12Y.

In the example shown in the figure, the printer section includes four sets of recording devices 13Bk,
13C, 13M, and 13Y are arranged side by side. Since each recording device 13 is made of the same constituent members, in order to simplify the explanation, the recording device for C will be explained, and the explanations for other colors will be omitted. For each color, the same parts are given the same reference numerals, and in order to distinguish the configuration of each color, an appendix indicating each color is attached to the reference number.

The recording device 13C has a photoreceptor 14C1, for example, a photoreceptor drum, outside the laser beam emitting device 12C.

A charger 15C, an exposure device including a laser beam emitting device 12C, a developing device 16C, a transfer charger 17C, and the like are attached to the photoreceptor 14C in the same manner as in a known copying apparatus. Note that the reference numeral 24 is a drum shaft.

Photoreceptor 1 uniformly charged by charger 15C
4C is by the laser beam emitting device 12C.

A latent cyan light image is formed and developed by the developing device 16C to form a developed image. Paper feed section 19 by paper feed roller 18,
For example, the copy paper supplied from either of the two paper feed cassettes is transferred to the transfer belt 20 as a transfer unit conveyance device at the same time that its leading edge is aligned by the registration roller 2o.
sent to. The copy paper conveyed by the transfer belt 21 is transported by photoreceptors 14Bk, 14C, and 14C, each having a developed image formed thereon.
It is sequentially sent to 14M and 14Y, and a developed image is transferred under the action of a transfer charger 17. The transferred copy paper is fixed by a fixing roller 22 and discharged by a paper discharge roller 23.

By being electrostatically attracted to the transfer belt 21, the copy paper can be conveyed with high precision at the speed of the transfer belt.

In FIG. 2, the conveying device of the present invention has registration rollers 2.
A conveyance guide section consisting of an upper guide plate 25 and a lower guide plate 26 is provided between the transfer belt 21 and the transfer belt 21, and the upper guide plate 25 is provided with an elastic displacement member configured as a leaf spring 27. The upper end of the leaf spring 27 is attached to the upper guide plate, and the lower end is curved to become a free end. The leaf spring 27 is normally held at a first position where the length of the conveyance path between the registration roller 20 and the transfer belt 21 is extended by its elastic force. That is, the leaf spring 27
The curved portion protrudes downward with respect to the shortest linear distance connecting the nip of the registration roller 20 and the position where the copy paper contacts the transfer belt 21, extending the length of the conveyance path.
When the copy paper is pulled, it is displaced to a second position, which will be described later.

Further, the conveying device is set so that the linear velocity (1) of the registration roller 20 is slightly slower than the linear velocity (2) of the transfer belt 21. In this case, considering the tolerances of the registration rollers 20 and transfer belt 21 and the slip rate from experimental values, the registration rollers 20 side is the fastest and the transfer belt 21 side is the slowest, and Vl<V2. Therefore, V1=V2
It is set so that it does not.

In the conveying device configured as described above, the copy paper P is transported by the registration rollers 20.
As shown in FIG. 3, when the sheet is held between the rollers 21 and 21, it is conveyed along the curved portion of the leaf spring 27 at the first position at the linear velocity V1 of the registration rollers 20. Then, the copy paper P is transferred to the transfer charger 17 of the first recording device 13Bk.
When subjected to the action of Bk, the copy paper P is electrostatically attracted to the transfer belt 21 and is conveyed at the linear velocity v2 of the transfer belt 21. Therefore, from the above relationship Vl<V2, the copy paper P is attracted to the transfer belt 21. The tension is applied between the registration rollers 20 and the transfer belt 21, and due to this tension, the leaf spring 27 is pushed upward and displaced to a deformed second position as shown in FIG. The conveyance path length is shortened and tension can be absorbed.

Thus, the present invention provides the registration roller 20 and the transfer belt 2.
It is possible to prevent image quality from deteriorating due to a linear velocity difference of 1. Furthermore, since the slow speeds of the registration rollers 20 and the transfer belt 21 are not made the same with high accuracy, a speed detector or the like is not required, and the cost is low.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways.

For example, the elastic displacement member is not limited to a leaf spring, but may be made of rubber, plastic, or the like that is elastically displaced by the tensile force of the transfer material, or may be a rigid plate pivotally attached with a spring interposed therebetween. Furthermore, the transfer unit conveyance device is not limited to a transfer belt, but can also be applied to a transfer drum.

Furthermore, the elastic displacement member can also be provided on the lower guide plate depending on the conveyance direction.

Effects According to the above configuration, the present invention has a simple configuration in which the linear speed of the registration roller is set lower than the linear speed of the transfer section conveyance device, and the conveyance guide section is provided with an elastic displacement member that extends the conveyance path length. Even if the transfer material is pulled between the registration rollers and the transfer unit conveyance device, the elastic displacement member deforms, shortening the conveyance path length and absorbing the tension of the transfer material, improving image quality due to the difference in linear speed. We were able to prevent a decline in

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a color copying machine to which the present invention is applied, FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are explanatory diagrams showing the mode of operation thereof. be. 20...Registration roller 21...Transfer belt 25.26...Upper and lower guide plate

Claims (1)

[Scope of Claims] A registration roller that conveys a transfer material to an image transfer section at a predetermined timing, and a transfer section conveyance device that conveys the transfer material in the image transfer section, and includes images of a plurality of colors on the transfer material. In a conveyance device of a multicolor image forming apparatus that transfers images in an overlapping manner, the linear speed of the registration roller is set to be slower than the linear speed of the transfer section conveyance device, and the conveyance between the registration roller and the transfer section conveyance device is A multicolor image forming apparatus characterized in that a guide section is provided with an elastic displacement member movable between a first position where the length of the conveyance path is extended and a second position where the length of the conveyance path is shortened. Conveyance device.