JPH0223130A - Sheet transfer device of image recorder - Google Patents

Abstract

PURPOSE:To reduce the quantity of electric charge at both the transfer and the recovery time and improve the sheet arrangement by using the electrically conductive rubber material for the surface of a driving roller and using metal for the surface of a press roller. CONSTITUTION:A copy sheet carried into a cassette 41 or 42 is delivered via a pair of feed rollers 45 and 46 and a travel guide 47 to the position of an image transfer separation pole 13 by a single sheet separation supply and transfer device 43 or 44 synchronously with the peripheral speed of a photosensitive drum 10 so that the toner image on the drum is transferred onto the copy sheet. The image-transferred sheet passes through the travel guide 48, goes under a fixing roller 15 and the press roller 16 thereof and is recovered into a sorter via a pair of sheet ejection rollers 18 and 19 and a pair of sheet ejection rollers 22 and 23 of the sorter 20. In this example, the driving roller 22 for a pair of paper ejection rollers feeding sheets to the arbitrary rack of the sorter 20 is made of electrically conductive rubber and the press roller 23 is of metal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in countermeasures for eliminating static electricity during conveyance of sheets such as recording paper in image recording apparatuses such as copying machines and printers.

[Conventional technology]

Taking an electrophotographic copying device as an example of an image recording device, a document screen placed on a document table is irradiated with a light source, and an optical system including a projection lens and a mirror transfers the image onto a charged photoreceptor. The image is formed into a latent image, which is developed with toner at a development position to become a visible image, and furthermore, at a transfer position, the visible image is transferred onto the sheet that is fed and conveyed one by one from a copying sheet supply device. The copied copy sheet is transferred to the fixing position and is thermally fixed by the fixing roller.The fixed sheet is sent out as is by the paper ejection roller and collected on a collection stand, or if a sorter is provided. Then, the originals are stacked on a sorter in the order of the pages after passing through a paper ejection roller, and are collected in a predetermined number of sets.

Sheets, including paper such as copying sheets, plastic recording sheets, and in some cases original sheets, are stored in image recording devices such as copying machines and printers, mainly in conveyance devices that form roller pairs such as supply rollers, conveyance rollers, and discharge rollers. The recording sheets on which images have been recorded are collected on a collection table or sorter, and the original sheets are collected on a collection table of original sheets if a document feeding device such as an ADF is installed.

However, insulating rollers are conventionally used in the pair of rollers used to convey the sheet mentioned above, and even if the rollers are grounded through their fixed shafts in order to eliminate the charges generated and accumulated on the rollers, the charges cannot be removed and tend to accumulate. Even if an attempt is made to remove the electric charge on the paper generated during the process from feeding the sheet to discharging the sheet by discharging using an electric discharge brush or the like, it is difficult to sufficiently increase the electric charge removal effect, and the following problems have occurred.

[Problem to be solved by the invention]

That is, the sheets of paper etc. that are discharged and collected are not well aligned.

Further, in the sorter, the sheets tend to stick to each column (bin), resulting in poor alignment, and therefore the number of sheets stored on the shelf (bin) cannot be increased.

Furthermore, when a person picks up a recorded sheet from a collection table or sorter, a person feels a static shock.

The present invention aims to solve problems including these problems.

[Means to solve the problem]

This object is to provide an image recording apparatus characterized in that in a sheet conveying section of the image recording apparatus, at least one pair of sheet conveying rollers has a driving roller surface made of a conductive rubber roller and a pressing roller surface made of metal. This is achieved by a sheet conveying device.

〔Example〕

First, an electrophotographic copying apparatus incorporating an embodiment of the sheet conveying apparatus of the image recording apparatus of the present invention will be explained with reference to the schematic diagram of FIG. This will be explained using FIG. 1, and the static elimination results are shown in FIG. However, the present invention is not limited to these embodiments.

The document placed on the document table at the top of the electrophotographic copying device l is placed on a first traveling table including a light source lamp 4 and a mirror 5, and a mirror 6.
．． 7 and runs at 1/2 the speed of the first carriage.
A scanning optical system consisting of a traveling table, a projection lens 8, and a mirror 9 forms an image on the photoreceptor drum 10 charged by a charger, forming a latent image, which is developed with toner by a developing device 12 to form a latent image. A visual image is created on the drum.

On the other hand, a copying sheet placed in a cassette 41 or 42 is transferred by a single-sheet separation supply conveyance device 43 or 44 through a pair of conveyance rollers 45, 46 and a running guide 47 in synchronization with the circumferential speed of the photoreceptor drum IO. The drum is fed to a certain position of the separation pole 13 so that the toner image on the drum is transferred onto the copying sheet. The copy sheet onto which the toner image has been transferred passes through the running guide 48, enters the fixing roller 15 of the fixing device and its pressing roller 16, is thermally fixed, and is transferred to a pair of paper discharge rollers 18, 19 and a pair of paper discharge rollers 22 to the sorter 20. .23 before being collected by a sorter.

The sorter 20 has shelves (bins) for 20 to 50 sheets, and pages are arranged and stacked in each column (bin) in the same order as the originals, and the required number of bins are operated and placed on standby in sequence at the paper ejection port. That's what I do.

A pair of paper ejection rollers 22.
23 is disposed at a fixed position on the sorter 20, and the bins connected to the elevating mechanism are sequentially moved to the paper ejection roller position by the required number of copies, and the above movement is repeated by the required number of original pages.

And the always necessary tya<bin) is the paper ejection roller pair 22.
It is designed so that it can stand by facing 23. In Figure 3, the shelves (bins) covered by 29 are the paper output (sheets).
This shows the status of waiting for collection. The bottle 29 has sufficient space between each column (bin) indicated by 28 above the bottle 29 to be collected.

Now, as mentioned above, in this embodiment, the conveyor roller pairs are those in the copy sheet supply path represented by 45 and 46, the paper discharge roller 18 and 19 immediately after the fixing roller, and the paper discharge roller 22 to the sorter. It is .23.

However, the number of transport roller pairs is not limited to this embodiment, and although not shown in the figure, the automatic document feeder (A
DF) is also provided in the device if it is equipped with one.

The present invention is characterized in that at least one pair of these conveyance rollers is not an electrically insulated roller but a conductive roller. The driving roller 22 was a conductive rubber roller, and the pressing roller 23 was a metal (aluminum) roller. Further, as shown in detail in FIG. 1, a discharge brush 32 touches the recording sheet discharged into the bin 29, and the brush also touches the pressure roller 23 of the pair of discharge rollers.

Furthermore, when there is no recording sheet, the surface of the drive roller may also be touched. Furthermore, contrary to FIG. 1, the static elimination brush can be attached to the back side of the sheet so that the brush also touches the back side of the sheet and the drive roller, and the same effect as the former can be achieved.

In the experiment of this example, the static elimination brush 31 shown in FIG. 1 was not operated and was removed. As for the other pairs of conveying rollers, both the driving roller and the pressing roller were left as electrically insulating rollers.

In order to confirm the difference in the effect between the roller pair of the present invention and the conventional roller pair, we conducted various experiments including using the conventional materials for the driving roller and the pressing roller of the sheet discharge roller to the sorter 2o. Compare the amount of charge generated on each ejected sheet.

However, as shown in Figure 1, when charged copy paper is discharged onto a sorter shelf (bin), the amount of charge on the copy paper is measured by measuring the opposite polarity charge induced in the bin. estimated.

The amount of charge on each paper was estimated by changing the pressure roller or drive roller from a conventional insulating roller to a metal or conductive rubber roller.

As shown in FIG. 1, in order to measure the charges of opposite polarity induced in the bin 29 from which the sheets are discharged, a resin plate 29a is inserted between the bin 29 and the bin 29b below it to insulate it. The metal plate constituting the bin 29 is connected to an electrometer 51 which is a digital ammeter so as not to be influenced by the bin, and the output thereof is input to an analyzing recorder 52 to convert it into an analog signal. The integral amount was defined as the amount of charge.

In other words, the amount of reverse charge generated on the shelf (bottle) - QbinQ pa
per and the Q bin are Q papers −Q
It becomes a bin relationship.

The copy paper used in this experiment was Konica Pap.
er (Ubix Paper) A 4 size 55. Further, the copying speed at that time was 40 sheets/min.

The materials of the upper and lower rollers used were as shown in the table below.

Here, the electrical resistance value of conductive carbon-containing chloroprene rubber is 10"Ω. The electrical resistance value of insulating chloroprene rubber is 1.
It is about 0@Ω.

In the experiment, five sheets were continuously copied at a time, and the average charge amount per sheet was recorded in units of nC (nanocoulombs), and this was repeated several times for measurement.

The results of the experiment are shown in Figure 2. The material No. 1 is the same as before and has not changed, so-called blank.

N004 is one embodiment of the conveyance device of the present invention,
Compared to the blank, the amount of charge on the bottle, that is, the amount of charge on the paper, is 6.
It can be seen that this decreases to about 1/7 to 1/7.

Regarding the pressure roller No. 4, we tested both a roller entirely made of a metal roller and a roller made of a resin roller whose surface was plated with metal, and both obtained the same effect without any difference.

In this way, according to the present invention, the amount of charge per sheet of copy paper is 2.
The amount of charge becomes 0 nC (nanocoulomb) or less, and with this amount of charge, there is no possibility of electrostatic shock when collecting sheets such as copy paper.

In this embodiment, the effect was achieved by using a metal roller and a chlorobrown rubber roller containing conductive carbon only as the paper ejecting roller pair to the sorter, but rollers made of the same material may be used for any other roller pairs. This further improves the static elimination effect on sheets such as copy paper.

〔Effect of the invention〕

According to the present invention, the amount of electrostatic charge during conveyance and collection of sheets such as copy paper is drastically reduced, which improves the alignment of the collected sheets in the bins of trays and sorters, eliminates flapping and turning up of the sheets in the bins, and therefore prevents the sheets from being stored in the bins. The number of sheets has increased, the sheets have become more stable, and there is no longer a situation where a person feels a static shock when trying to take out the sheets.

[Brief explanation of the drawing]

FIG. 1 shows 151! of the sheet conveying device of the present invention. A schematic diagram of an example and its effect measurement method. FIG. 2 is a graph showing the comparison results of the amount of charge in the embodiment of the present invention and when the material of the roller is varied. FIG. 3 is a schematic diagram of an electrophotographic copying apparatus incorporating an embodiment of the present invention. 18.22.45...Roller pair drive roller 19.2
3.46...Roller pair pressure roller 20...Sorter 28, 29...Shelf (bin) 31.32.
・Static neutralization brush

Claims (1)

[Claims] A sheet of an image recording device, characterized in that in at least one pair of sheet conveying rollers in a sheet conveying section of the image recording device, the surface material of the driving roller is a conductive rubber roller, and the material of the pressing roller surface is metal. Conveyance device.