JP2003034449A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device for eliminating nonuniformity of static elimination of a transfer material, and causing no image failure and carrying jam. SOLUTION: In the typical constitution of this image forming device, the image forming device is provided with a sheet metal carrying guide 4 for guiding a carry of a sheet material P, a carrying rib 3 partially protrusively arranged on a transfer material carrying passage surface of the sheet metal carrying guide 4, and a static eliminating needle 5 arranged in the direction almost orthogonal to the transfer material carrying direction in a position opposed to the sheet metal carrying guide 4, and eliminating static electricity of the carrying sheet material P. The static eliminating needle 5 of a position opposed to the carrying rib 3 reduces a static eliminating effect more than a part unopposed to the carrying rib 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used in electrophotographic printers, copying machines and the like.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic method has been widely used as an image forming method for forming an image on a transfer material. The general method is to charge and expose a photoconductor using a photoconductive material to form an electrical latent image, develop the latent image with a colored toner, and visualize the latent image. It is a thing.

The toner image developed on the photoreceptor is electrically attracted from the back side of the transfer material conveyed at a predetermined timing by a corona discharge or bias applying means such as an elastic roller. After that, the transfer material is separated from the surface of the photoconductor by the charge eliminating means provided in the vicinity of the curvature of the photoconductor and the transfer bias applying means, and is guided to the conveying path. Further, the transfer material is conveyed to a fixing device and heated and pressed together with the transfer material to melt and fix the toner to obtain a fixed image.

In such an image forming apparatus, as a conveying path for conveying the transfer material to the transfer portion after being fed, there is a conveying guide made of a resin molding member such as ABS having a rib on the surface. . The rib has the role of reducing the sliding resistance between the transfer material and the conveyance guide and smoothing the conveyance to the transfer portion.

When the transfer is performed, the transfer material is charged by applying a transfer bias from the back side of the recording surface, but the transfer material is charged by the sliding resistance with the transfer guide in the transfer path before the transfer. In particular, in an apparatus using a curling means for curling the tip of the transfer material in the separation direction in advance in order to increase the separation latitude after the transfer, the transfer material is more remarkable by passing through a curled roller under pressure. To be charged.

Therefore, conventionally, the transfer material is appropriately discharged by a discharging means such as a discharging needle. If static electricity is not removed, the sliding resistance between the transfer material and the transport guide will increase, causing not only skew and jam due to sticking, but also the charge on the transfer material will leak to the transport guide, causing a sudden change in the electric field. An image defect called a "polka dot" occurs, in which the surrounding toner image is disturbed. Further, if the charge removal amount is extremely different partially in the transfer material conveyance direction, image unevenness such as “black streak” and “white streak” will occur.

Therefore, it is necessary to eliminate the charges on the transfer material appropriately and uniformly over the entire transfer material.

[0008]

However, the above-mentioned conventional image forming apparatus has the following problems. For example, when a conveyance guide integrated with conveyance ribs made of ABS resin is used, there is a slight difference in the amount of electrification by rubbing between a rib portion and a place without ribs, but the toner image on the transfer material is disturbed. Is few.

However, in the structure in which the charge elimination needles are arranged on the opposite surfaces of the conveyance guides having the conveyance ribs to eliminate the charge on the transfer material passing between the conveyance guides, the unfixed toner image on the transfer material corresponding to the ribs is not formed. Distortion and "black streaks" may occur. This phenomenon occurs because the conveyance guide is positively charged due to the rubbing of conveyance, the conveyance rib serves as an antenna, penetrates the transfer material, and is discharged toward the charge eliminating needle that is the GND, leaving a discharge mark on the transfer material. In particular, weigh 60 to 90 g / m2,
This is likely to occur when a sheet having a relatively high resistance of 1012 Ω or more is continuously conveyed.

Further, in the case where the automatic double-sided device is provided, a phenomenon that is particularly noticeable when recording the second side where the sheet has a high resistance after passing through the fixing device or when used in a low humidity environment. Is.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that eliminates uneven charge removal of a transfer material and that does not cause image defects and conveyance jams.

[0012]

In order to solve the above problems, a typical structure of an image forming apparatus according to the present invention is a conveyance guide member for guiding the conveyance of a transfer material, and a transfer guide member transfer. The transfer rib is provided so as to partially project on the material transfer path surface, and is provided at a position facing the transfer guide member with the transfer material interposed therebetween, and in a direction substantially orthogonal to the transfer material transfer direction, and is transferred. In an image forming apparatus provided with a charge eliminating member for eliminating charge of a transfer material, the charge eliminating effect of the charge eliminating member at a position facing the carrying rib portion is lower than that of a portion not facing the carrying rib portion. To do.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment A first embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a charge eliminating member according to the present embodiment, and FIG. 2 is an explanatory diagram of a transfer material conveyance path. First, an electrophotographic copying machine, which is an example of the electrophotographic image forming apparatus according to the present invention, will be described with reference to FIG.

As shown in FIG. 5, the electrophotographic copying machine main body 10
In 0 (hereinafter referred to as the apparatus main body), the original is placed on the original table glass 102. Then, an optical image according to the image information of the document is output from the plurality of mirrors M and lenses Ln of the optical unit 103.
Thus, an image is formed on the electrophotographic photosensitive drum 104. The recording material P loaded in the cassette 105 (hereinafter, "sheet material")
(Hereinafter referred to as “the sheet material size information of the cassette 105”), an appropriate sheet material is selected from the information input by the user from the operation unit or the sheet material size of the document. Here, the sheet material is not limited to paper, and an OHP sheet or the like can be appropriately selected.

Then, one sheet material P conveyed by the feeding / separating device 105A is conveyed to the registration roller 110 via the conveying section 109 and the pre-registration conveying guide section 130, and the drum 104 rotates and The sheet is conveyed by synchronizing the scanning timing of the unit 103. Then, by the transfer charger 111,
The toner image formed on the drum 104 is transferred to the sheet material P, and the separation charging device 112 separates the sheet material P to which the toner image is transferred from the drum 104.

After that, the sheet material P conveyed by the conveying section 113 is fixed with a toner image on the sheet material by a fixing device 114 by heat and pressure. After passing through the discharge reversal unit 115, the outside discharge roller
After passing through the outside discharge sensor 137 for detecting the passage of the sheet material P arranged on the upstream side, the outside discharge roller 116 discharges the sheet material P to the outside of the main body apparatus. In the case of double-sided copying, the flapper 118 of the discharging and reversing unit 115 controls the paper to be temporarily conveyed to the reversing path 120 via the re-feeding and conveying path 119.
Here, the trailing edge of the sheet material P passes through the re-feeding / conveying path 119, and the reversing roller 122 is reversely rotated at the timing when it is still sandwiched by the reversing roller 122, so that the sheet material P is conveyed again into the apparatus. After that, after passing through the pre-registration transport guide unit 130 again to the registration roller 110 via the double-sided path 121, the sheet is discharged to the outside of the main body apparatus along the same route as in the case of single-sided copying.

In such a sheet material flow, the pre-registration conveyance guide section 130, which is a feature of the first embodiment of the present invention.
The configuration will be described in detail. As shown in FIG. 2, the curling roller pair 1 curls the tip of the transfer material in the separation direction in advance in order to increase the separation latitude after the transfer. The mold transport guide 2 is formed of a resin molding member such as ABS having a transport rib 3 on its surface. The metal sheet metal conveyance guide 4 is a conveyance guide member arranged for the transfer material conveyance path, and has high slidability and is GND-connected. The static elimination needle 5 is a static elimination member that is electrically connected and that eliminates electrostatic charges on the sheet material P and the sheet metal transport guide 4 that pass between the transport ribs 3 and the sheet metal transport guides 4. It is fixed at a position substantially orthogonal to the transfer material conveyance direction.

A4 size sheet material (weighing 60 to 90 g / m
2. A sheet with a relatively high resistance of 1012 Ω or more) is used in a low humidity environment (water content 0.86 gr / Kg) 450
When 3000 sheets are continuously conveyed at a speed of mm / s, the mold conveyance guide 2 is charged up to DC 3.0 to 3.5 kV. Here, as shown in FIG. 1 (a view from the arrow A in FIG. 2), the charge elimination needle 5 connected to GND is arranged so as to face the mold conveying guide 2, and only the portion facing the conveying rib 3 is cut away. There is. For this reason, even when the entire mold transport guide 2 is charged at a high potential under the above conditions, the static elimination needle does not exist on the opposing surface of the transport rib 3 serving as the antenna, so that the sheet material S penetrates and leaks. There is no fear.

As described above, by notching only the position of the discharging needle 5 facing the conveying rib 3, it is possible to surely eliminate the discharge trace due to the leak while maintaining the discharging effect of the sheet material P.

Second Embodiment Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 3 is an explanatory diagram of the charge eliminating member according to the present embodiment, and FIG. 4 is an explanatory diagram of a transfer material transporting path. The same parts as those of the first embodiment will be designated by the same reference numerals and the description thereof will be omitted.

In FIGS. 3 and 4, reference numeral 6 denotes an insulating sheet, which is covered only by the static elimination needle 5 facing the conveying rib 3.

Therefore, even when the mold transfer guide 2 as a whole is charged at a high potential under the conditions described in the first embodiment, the insulating surface of the transfer rib 3 serving as the antenna is covered with the charge elimination needle. Since the sheet 6 does not fall to GND, there is no risk of leaking through the sheet material S.

As described above, the insulating sheet 6 covers only the position of the discharging needle 5 which faces the conveying ribs 3, so that the discharging effect of the sheet material P can be maintained and the discharge can be ensured as in the first embodiment. It is possible to eliminate the discharge trace due to the leak.

It should be noted that when the convex carrying rib 3 is extremely triboelectrically charged, it is sufficient if the discharging amount of the discharging needle 5 on the facing surface is reduced or reduced to 0, for example, only the facing surface of the carrying rib 3. The same effect can be obtained by selecting a material having a high volume and low efficiency for the charge elimination needle 5.

Further, in the above-mentioned embodiment, only the charge elimination effect at the time of single-sided conveyance is explained. However, at the time of double-sided recording, one recording surface side and the other recording surface side are automatically conveyed respectively through the conveying path. Since the automatic double-sided device is provided, it is possible to more surely prevent the image defect due to the above-mentioned factors even when the second side, which passes through the fixing device and has a high resistance, is recorded.

[0026]

As described above, according to the present invention,
The transfer material conveys ribs even when the guide is extremely charged up while keeping the effect of preventing skewing and jamming due to sticking by suppressing the increase in the friction resistance between the transfer material and the convey guide by the static elimination needle. It is possible to uniformly eliminate the charge on the entire transfer material without leaking in a portion, and it is possible to provide a stable image that is not affected by the operating environment.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a charge eliminating member according to a first embodiment.

FIG. 2 is an explanatory diagram of a transfer material conveyance path.

FIG. 3 is an explanatory diagram of a charge eliminating member according to a second embodiment.

FIG. 4 is an explanatory diagram of a transfer material conveyance path.

FIG. 5 is a configuration diagram of an image forming apparatus.

[Explanation of symbols] [Explanation of symbols]

Ln ... Lens M ... Mirror P ... Sheet material 1… Roller pair 2… Mold transfer guide 3 ... Transport ribs 4 ... Sheet metal transport guide 5 ... Static elimination needle 6… Insulation sheet 100… Electrophotographic copying machine body 102… Platen glass 103… Optics 104 ... Electrophotographic photosensitive drum 105 ... cassette 105A… Feeding separation device 109… Transport section 110… Regist rollers 111… Transfer charger 112 ... Separation charger 113… Transport section 114… Fixer 115… Emission reversal section 116… Outer roller 118… flapper 119… Refeeding and conveying path 120… Inversion path 121… Double-sided pass 122… Reversing roller 123… Inside discharge roller 130… Transport guide section before cash register 137… External emission sensor

Claims (5)

[Claims] 1. A transport guide member for guiding the transport of a transfer material, a transport rib portion partially projecting on a transfer material transport path surface of the transport guide member, and the transport material sandwiching the transport material. In an image forming apparatus, which is provided at a position facing the guide member and in a direction substantially orthogonal to the transfer material transport direction, and includes a charge removing member for removing charge of the transferred transfer material, the image forming apparatus faces the transport rib portion. An image forming apparatus characterized in that a charge removing effect is reduced as compared with a portion of the charge removing member located at a position not facing the conveying rib portion. 2. The image forming apparatus according to claim 1, wherein the charge removing member is formed so as to be cut out only at a position facing the conveying rib portion to reduce the charge removing effect. 3. The image forming apparatus according to claim 1, wherein the charge removing effect is reduced by covering the position of the charge removing member facing the conveying rib portion with an insulating member. 4. The image forming apparatus according to claim 1, wherein the static elimination effect is reduced by increasing the volume resistivity only at a position of the static elimination member facing the conveying rib portion. 5. A double-sided recording is possible by providing an automatic double-sided device in which one recording surface side and the other recording surface side are automatically conveyed through the conveying path, respectively. The image forming apparatus described.