JPH047234A - Paper feeder for picture forming device - Google Patents

Abstract

PURPOSE:To suppress an escape of charged electricity so as to successfully perform transcription by connecting a guide member and a conveying roller, which feed a transcription sheet to a picture transcribing part, to the earth through a resistance element while electrically insulating these guide roller and conveying roller from a machine body and providing an auxiliary feed roller, having conductivity for a small size sheet, in the guide member just before the transcribing part. CONSTITUTION:An auxiliary feed roller 63 for a small size sheet is positioned just before a transcribing part to give a feed to a sheet. In this way, the sheet, even when it is in small size, can be surely presented to transcription without interruption of conveyance midway. A conveying roller 36 and guide members 61, 62 are respectively placed in an insulated condition from a machine body and connected to the earth through a resistance element 68. As a result, an escape of charged electricity, given to the transcription sheet for transcription, can be suitably suppressed even when the conveying roller and the guide members are brought into contact with the transcription sheet presented for transcription.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a paper feeding device for an image forming apparatus that forms images using an electrophotographic method, and more particularly to a paper feeding device that feeds a transfer sheet to a transfer section. .

2. Description of the Related Art In order to guide and convey a transfer sheet to a transfer section, this type of paper feeding device comes into contact with a transfer sheet that is undergoing transfer. For this reason, if the conveyance roller or the guide plate is directly grounded, the transfer charges charged by the transfer charger to the back surface of the transfer sheet will be released, causing a transfer failure. This is noticeable in high humidity conditions where the conductivity of the transfer sheet becomes high. Furthermore, if the paper feeding device is completely ungrounded, the power will be cut off along with the transfer sheet, causing toner to adhere to various parts of the paper feeding device and staining the transfer sheet.

As a solution to this inconvenience, Japanese Patent Application Laid-Open No. 1986-
There are those described in Japanese Utility Model Publication No. 112082 and Japanese Utility Model Application Publication No. 153060/1983. In these devices, a guide member in the paper feeding device is grounded via a resistive element.

As a result, it is possible to appropriately restrict the electric charge charged on the transfer sheet from escaping via the guide member, and the above-mentioned problem can be solved.

Problems to be Solved by the Invention However, it is not only the guide member that comes into contact with the transfer sheet during transfer in the paper feeding device, but also the conveyance rollers such as timing rollers that come into contact with the transfer sheet and cause the electrostatic charge on the transfer sheet to escape. However, the conventional method described above cannot cope with this.

Furthermore, in order to reliably transfer small-sized transfer sheets such as postcards, it is preferable to provide a conveyance roller close to the transfer section. However, this also causes the charge on the transfer sheet to escape.

Therefore, it is conceivable to ground all of these via resistive elements. However, it is difficult to adopt the conventional individual grounding structure immediately before the transfer section, where the conveyance rollers and guide members are crowded in a narrow space. Taking these points into consideration, the present invention improves the paper feeding structure, has a conveyance roller for small sizes, and uses a simple structure to prevent the inconvenient escape of electrical charges on the transfer sheet at the paper feeding section. An object of the present invention is to provide a paper feeding device for an image forming apparatus that can perform the following steps.

Means for Solving the Problems In order to achieve the above-mentioned problems, the invention of the present application tube 1 electrically insulates the guide member and the conveyance roller for feeding the transfer sheet to the image transfer section from the machine body, and also This apparatus is characterized in that it is grounded through a resistive element and is provided with a conductive auxiliary feed roller for small-sized sheets on the guide member in front of the transfer section surface.

The invention of the present application tube 2 is further characterized in that the resistance element is a constant voltage element in the first invention.

Effects According to the above structure of the invention of the cylinder 1, the auxiliary feed roller for small-sized sheets is located immediately before the transfer section to feed the sheets, so even if the sheets are small, the conveyance is interrupted midway. It can be used for transcription without any problems.

In addition, each of the conveyance roller and guide member is insulated from the machine body and grounded via a resistive element, so even if they are in contact with the transfer sheet being transferred, the transfer sheet is not provided for transfer. In addition, the auxiliary feed roller is conductive and is provided immediately before the transfer portion of the guide member, and is grounded through the guide member and the resistive element. Therefore, the escape of the charge on the transfer sheet can be similarly suppressed in the same way as in the other cases described above.

Therefore, even small-sized transfer sheets can be reliably transferred using the auxiliary feed roller, and the transfer is prevented by suppressing the escape of electrical charges through all the members that come into contact with the transfer sheet during transfer, including the auxiliary feed roller. It is possible to guarantee that the process will be carried out successfully. Also, the excess charge on each member of the paper feeding section will be released beyond the suppressing action of the resistor element, so the excess charge will accumulate and toner will adhere to the transfer sheet. This will avoid contamination.

According to the above structure of the invention of the present invention cylinder 2, since the resistance element is a constant voltage element, it is possible to appropriately release the electrical charges on the transfer sheet according to the characteristics of the resistance element.

EXAMPLE A paper feeding device of an image forming apparatus as an example of the present invention shown in FIGS. 1 to 4 will be described below.

FIG. 1 shows a copying machine having an exposure optical system according to the present invention. This copying machine includes an exposure optical system 1, an image forming mechanism 3 that forms an image through exposure by the exposure optical system 1 and transfers it to a transfer sheet 2, and a transfer sheet 2 that is connected to the image forming mechanism 3.
It has a paper feeding mechanism 4 that feeds the paper. The exposure optical system 1, image forming mechanism 3, and paper feeding mechanism 4 are individually housed in independent optical system box 6, image forming box 7, and paper feeding box 8, respectively. The boxes 6 to 8 are stacked and connected to form a fuselage 9.

The exposure optical system 1 includes a lamp 13 that is supported by a first slider 12 that moves under a platen glass 11 to scan an original on the platen glass 11, a first mirror 14, a second slider 15, and a third slider. second to fifth mirrors 17 to 20 that move to keep the optical path length constant;
It includes a projection lens 21 provided between the third and fourth mirrors 18 and 19, and a sixth mirror 22 that performs optical path length correction during zooming by moving the projection lens 21 in the optical axis direction.

The image forming mechanism 3 includes a photosensitive drum 31, a charging charger 32 disposed around it, a developing bag 't 33, a transfer charger 34, a separation charger 135, and a cleaning device 1.
36, etc., and forms a toner image corresponding to the exposed original image on the photosensitive drum 31 by a known electrophotographic method, and transfers it to the transferred transfer sheet 2. In front of the transfer section where the photosensitive drum 31 and the transfer charger 34 face each other, there is provided a paper feed conveyance path 35 for feeding the transfer sheet 2 received from the paper feed box 8 to the transfer section, and a timing roller is provided on the way. 36 are provided. The timing roller 36 is fed the transfer sheet 2 in a stopped state, and corrects the skew of the transfer sheet 2 by aligning its leading edge, and adjusts the timing of feeding the transfer sheet 2 to the transfer section depending on when to start conveyance. .

After the transfer unit, there is a conveyance device 37 that conveys the transferred transfer sheet 2 while adsorbing it to a belt, and a fixing device 38 that performs a fixing process on the transfer sheet 2 conveyed by the conveyance device 37.
, a paper discharge roller 39 for discharging the transfer sheet 2 sent out from the fixing device 38 is provided.

The paper feeding mechanism 4 has three paper feeding sections 41 to 43 that accommodate transfer sheets 2 of different sizes and selectively feed them. Each paper feed unit 41 to 43 has a paper feed cassette 44 to
Pickup roller 4 that sends out the transfer sheet 2 in 46
7 to 49, and a handling vat 51 for handling the transferred transfer sheets 2 one by one. Each paper feed section 41 to 43
Each of the blocks is divided into blocks, and the blocks can be exchanged by exchanging two blocks for one block for multiple sheets. Each paper feed section 41 to 43
The paper feed cassettes 44 to 46 are of a front loading type in which they are inserted and removed from the front side of the machine body 9, which in FIG. 1 is from the front side of the page.

The transport path of the transfer sheet 2 in the image forming mechanism 3 is shown in detail in FIG. The paper feed conveyance path 35 includes a timing roller 36 and sheet guides 61 and 62 provided before and after the timing roller 36.
An auxiliary feed roller 63 for small-sized sheets such as postcards is provided on the sheet guide 62 immediately in front of the transfer section, and directly supports this. Each of the timing roller 36, sheet guides 61, 62, and auxiliary feed roller 63 is in contact with the transfer sheet 2 during transfer, and if they are directly grounded, the charges that should be charged on the transfer sheet 2 will be released. Also, when the contact with the ground is completely released, the timing roller 3
6. The sheet guides 61 and 62 and the auxiliary feed roller 63 are charged with electricity and toner adheres to them, causing problems such as staining the transfer sheet 2.

In order to solve these problems, in this embodiment, the timing roller 61 and the sheet guides 61, 62 are provided with insulating support parts 65, 66, .
67, and is electrically insulated from the fuselage 9. Also, the auxiliary feed roller 63
is made of a conductive material such as metal or conductive rubber, and is electrically connected to the sheet guide 62. These timing rollers 36 and sheet guides 61.6
2 is grounded via Harris Staro 8. As a result, the auxiliary feed roller 63 is also grounded through the sheet guide 62 and the varistor.

The transfer sheet 2 during transfer is transferred to the timing roller 36,
Even when the transfer sheet 2 contacts the sheet guides 61, 62 and the auxiliary feed roller 63, it is possible to suppress the charge on the transfer sheet 2 from escaping and ensure that the transfer is performed successfully. Also, timing roller 36, sheet guide 61.6
2. Even if each of the auxiliary feed rollers 63 is excessively charged, the excess charge is released beyond the control of the Harris Starro 8. This prevents excess charge from remaining and causing toner to adhere and staining the transfer sheet 2.

Further, in the conveyance device 37 located behind the transfer portion surface, at least the portion of the resin frame 72 that supports the porous belt 71 that contacts the transfer sheet 2 is made of antistatic resin. In this embodiment, the entire resin frame 72 and the resin transfer sheet guide 73 disposed beside each porous belt 71 are made of antistatic resin. The antistatic resin has a resistance of, for example, 108
It has a surface resistivity of about 1013Ω and has an antistatic effect. This allows the transfer sheet 2 after transfer.
Even if the sheet reaches the conveyance device 37 and comes into contact with the resin frame 72, transfer sheet guide 73, etc., it will not be attracted to them due to static electricity and will be conveyed smoothly. Therefore, it is possible to reduce costs and reduce weight by using resin for the main structure of the conveying device 37, which can be achieved without problems in conveying the transfer sheet 2.The antistatic resin is ABS resin manufactured by Toshi Co., Ltd. There is TOYOLAC Barrel, a permanent antistatic resin.

As shown in FIGS. 2 to 4, the perforated belt 71 is stretched by rollers 75 and 76 that are supported by U-shaped bearings 74 formed on the upper surface of the resin frame 72. Each transfer sheet guide 73 has rollers 75 and 76 attached to the bearing portion 7.
It also has the function of holding it down within 4 and ensuring stable rotation. Here, the perforated belt 71 is stretched by the roller 7
5.76, as shown in FIG. 4, by fitting each roller 75, 76 into the opposing bearing part 74 from the same side with the hooks being crossed, and then pressing each part with the transfer sheet guide 73. It can be easily assembled to the resin frame 72. The transfer sheet guide 73 is attached to the resin frame 72 using screws 95 and engagement pieces 96.

A suction box 77 for sucking the transfer sheet 2 is located inside the perforated belt 71 and must be attached to the resin frame 72 with screws 78. The procedure for this operation is to insert the suction box 77 inside the perforated belt 71 before either or both of the rollers 75 and 76 are fitted into the bearing portion 74. Next, when both or the remaining rollers 75 and 76 are fitted into the bearing part 74 and the porous heald 71 is placed along the top surface of the resin frame 72, the suction box 77 can also be placed along the top surface of the resin frame 72 at the same time, and the suction box 77 can be placed along the top surface of the resin frame 72. It can be screwed with a screw 78. In other words, the porous heald 71 and the suction box 77 inside it can be attached to the resin frame 72 from one side all at once.

The suction box 77 is formed by coupling an upper plate 77a and a lower plate 77b by elastic engagement between an engagement spring 81 and an engagement hook 82. Each porous belt 71 is attached to the upper plate 77a.
A suction port 83 facing the suction fan 84 is formed in the lower plate 77b, and a connection port 85 with a suction fan 84 is formed in the lower plate 77b.

The suction fan 84 has upper and lower casings 84a and 84b.
A separate car 86 is housed in between, and is attached to the resin frame 72 from the back side, so that the suction port 87 passes through the connection port 85 of the suction box 77 through the connection port 88 of the resin frame 72. It's Nishide. 89 is suction fan 8
4 exhaust port.

By the way, as shown in FIG. 2, the sheet guide 62 forms a bent sheet feeding path from the timing roller 36 to the transfer section, so that when a thick sheet such as a postcard passes through the timing roller 36, it The edge jumps up, and the vibration of the transfer sheet 2 at that time affects the transfer and distorts the image. To solve this problem, an elastic resin sheet 91 extending toward the timing roller 36 is attached to the upper guide 62a of the sheet guide 62. This sheet 91
is a slightly stiff and thin elastic sheet made of polyethylene terephthalate (PET), and even if the rear end of the thick transfer sheet 2 passes through the timing roller 36 and tries to jump up, it is prevented by its own elasticity, and the transfer sheet 2 can be stably transferred until the end.

Furthermore, in the case where the fuser 38 performs heat fixing, if the transfer sheet 2 is in a high humidity state, a lot of steam will be generated during the fixing, and this will cause a large temperature difference between the transfer sheet 2 and the fuser 38 part in particular. That is, dew condensation occurs on the sheet guide 93 and the like on the side farther away from the fixing device 38. For this reason, when the transfer sheet 2 leaving the fixing device 38 reaches the sheet guide 93, the leading edge of the transfer sheet 2 comes into close contact with the sheet guide 62, which may result in jamming without being conveyed. This is thin transfer sheet 2
Significant in cases of In this embodiment, in order to solve this problem, an elastic resin sheet 94 extending toward the paper ejection roller 39 is provided at the bent portion of the front end of the upper guide 93a of the sheet guide 93, where the transfer sheet 2 is likely to adhere. Elastic resin sheet 94
is the elastic resin sheet 91 immediately after the timing roller 36
The transfer sheet 2 may be of the same quality as the metal sheet guide 93, and the steam is less likely to condense, and the transfer sheet 2 can be smoothly guided to the paper ejection roller 39 and reliably ejected.

Note that in this embodiment, the timing roller 3 of the paper feed conveyance path 35
6. Although a varistor is used to ground the sheet guides 61 and 62, the present invention is not limited to this, and any material can be used as long as it can appropriately suppress the escape of charge. In this sense, a resistor or the like may be used, and in general, a resistive element may be used. Further, although this embodiment has been shown only in the case of a copying machine, the present invention can be applied to all image forming apparatuses that form images using an electrophotographic method, such as printers.

Effects of the Invention According to the first invention of the present application, since the above-described structure and operation are achieved, even a small-sized transfer sheet can be reliably transferred by the auxiliary feed roller, and the auxiliary feed roller is included in the transfer sheet. The roller that comes into contact with the transfer sheet during transfer,
It is possible to suppress the escape of electrical charges through the sheet guide and ensure that the transfer is performed successfully.

In addition, excess electric charge from each member of the paper feeding section is released beyond the control of the resistive element, and it is possible to avoid a situation where excessive electric charge accumulates and toner adheres to the transfer sheet. Since the auxiliary feed roller is made of its own material and supported by the sheet guide, no special support member or grounding structure is required, the structure is not particularly complicated, and it can be provided at a relatively low cost.

Further, according to the second invention of the present application, since the resistive element is a constant voltage element, it is possible to appropriately release the electrical charges on the transfer sheet depending on the characteristics of the resistive element.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view of a copying machine having a paper feeding device as an embodiment of the present invention, FIG. 2 is an enlarged view showing the conveyance path of a transfer sheet, and FIG. 3 is an enlarged front view of a suction conveyance device. FIG. 4 is an exploded perspective view of the suction conveyance device. 2-・-1-------.--1--Transfer sheet 35--1 to 111--Paper feed conveyance path 36-・−−−m−−−・−・−1−−−・・
-Timing roller 61.62- ・----1----
−Sheet guide 63−−−−・−−−−−−−・−・−
・−・−Auxiliary feed roller 6, t−−−−−−−1・−
Support frame 65.66.6 Frame--Insulating member 6
B-----------1・-----Varisku agent Patent attorney Masaru Ishihara

Claims (2)

[Claims] (1) The guide member and conveyance roller that feed the transfer sheet to the image transfer unit are electrically insulated from the machine body and grounded via a resistive element, and the guide member just before the transfer unit is conductive for small size sheets. 1. A paper feeding device for an image forming apparatus, characterized in that an auxiliary feed roller having a auxiliary feed roller is provided. (2) A paper feeding device for an image forming apparatus according to claim 1, wherein the resistive element is a constant voltage element.