JPH0223385A - Sheet destaticizing device for image recorder - Google Patents

Abstract

PURPOSE:To improve destaticizing efficiency by using long bristles for destaticizing a brush provided on a sheet carrying path from their top to middle, and permitting the brush to abut on the sheet surface with its long bristles. CONSTITUTION:The destaticizing brushes 31 and 32 are provided on the sheet carrying path so that their bristles from the top to middle can abut on the sheet surface. Consequently, when sheets are carried and recovered, electrification quantity is drastically decreased, whereby the recovered sheets can be collated more readily on a tray or in the bin of a sorter. Therefore, they never fly out or float in the bin to contain much more sheets in the bin more stably and surely. When a user takes out sheets, he never feels electrostatic shock.

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 illuminated by a light source, and an image is formed on a charged photoreceptor by an optical system including a projection lens and a mirror. The latent image is developed with toner at a development position to become a visible image, and the visible image is further transferred at a transfer position onto the sheet fed and conveyed one by one from a copying sheet supply device, The copied copy sheet is conveyed to the fixing position and thermally fixed by the fixing roller, and the fixed sheet is sent out as it is by the paper ejection roller and collected on the collection stand, or if a sorter is provided, it is The originals are stacked on the sorter in the order of the pages after passing through the previous 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, the pair of rollers used to convey the sheet mentioned above uses insulating rollers made in the United States, and even if the rollers are grounded through the fixed shaft of the rollers in order to eliminate the electric charges generated and accumulated on the rollers, the electric charges cannot be removed and tend to accumulate. If a static eliminating brush is not used on the sheet at least at one point during the process from sheet feeding to sheet ejection, as shown in Figure 4, electric charge will continue to build up on the sheet each time copies are made, resulting in the following problems. was occurring.

[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.

In order to avoid this problem, conventionally it was thought that the most effective way to remove static electricity from the sheet was to bring the bristles of the static elimination brush into light contact with the sheet being conveyed or to remove static electricity from the sheet by keeping it 1 to 2 mm away from the sheet. It's not enough.

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 the bristle part of the static elimination brush provided on the sheet conveyance path of the image recording apparatus is arranged so that the long limbs from the tip of the bristle to the abdomen come into contact with the surface of the sheet. The problem is solved by a sheet static eliminator.

〔Example〕

First, an electrophotographic copying apparatus in which an embodiment of the sheet static eliminator for an image recording apparatus of the present invention is incorporated will be explained with reference to the schematic diagram of FIG. This will be explained with reference to the drawings, and the static elimination results are shown in No. 2130.

However, the present invention is not limited to these embodiments.

A document placed on the document table at the top of the electrophotographic copying device 1 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 composed of a traveling table, a projection lens 8, and a mirror 9 forms an image on the photoreceptor drum 10 charged by a charger to form a latent image, which is then developed with toner by a developing device 12. A visual image is created on the drum.

On the other hand, the copying sheet placed in the cassette 1-41 or 42 is conveyed by a single sheet separation supply conveyance device 43 or 44, through a pair of conveyance rollers 45, 46, and a running guide 47, and is synchronized with the circumferential speed of the photoreceptor drum 10. The toner image on the drum is transferred onto the copying sheet. The copy sheet with the toner image transferred passes through the running guide 48, enters the fixing roller 15 of the fixing device and its pressing roller 16, and is thermally fixed.
The sheets are collected by the sorter through a pair of sheet discharge rollers 18 and 19 and a pair of sheet discharge rollers 22 and 23 to the sorter 20.

The sorter 2θ has shelves (bins) for 20 to 50 sheets, and pages are stacked in each column (bin) in the same order as the originals, and the required number of bins are operated and placed on standby at the paper ejection port in sequence. 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 yK pages. And the shelf (bin) that is always required is the paper ejection roller pair 22.2
It is designed so that it can stand by facing 3. In FIG. 3, the shelves (bins) 29 are shown in a state where they are waiting to collect discharged paper (sheets). The bottle 29 has sufficient space between each column (bin) indicated by 28 above the bottle 29 to be collected.

In the present invention, at least one set of static eliminating brushes is provided to eliminate static electricity from the sheets conveyed on the sheet conveyance path in this way. The driving roller 22 of the paper ejection roller pair was a conductive rubber roller, the pressing roller 23 was a metal (aluminum) roller, and a static elimination brush was disposed downstream thereof. The brush is arranged so as to come into contact with the recording sheet being conveyed and also with the surface of the pressing roller of the pair of rollers. Of course, the brush may also come into contact with the surface of the drive roller when there is no recording sheet. As for the other pairs of conveying rollers, both the driving roller and the pressing roller were left as electrically insulating rollers.

Incidentally, the static elimination brush 31 shown in FIGS. 1 and 3 was not operated but removed for the experiment.

When a static elimination brush that contacts both the recording sheet surface and the pressing roller surface is provided and grounded as in this embodiment, the length of the bristles of the brush away from the sheet surface and the length of the bristles The amount of charge generated on each ejected sheet was plotted by varying the length of the bristles in contact with the sheet surface from the tip to the back of the brush. This is expressed in the graph of Figure 2. However, as shown in Figure 1, when charged copy paper is ejected to Bin III (bin) of a sorter, the charges of opposite polarity induced in the bin are measured. The amount was estimated.

In addition, as shown in FIG. 1, in order to measure the charge 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 for insulation. said bin 2 without being influenced by other bins.
The metal plate 9 is connected to an electrometer 51, which is a digital ammeter, and the output thereof is input to an analyzing recorder 52, where it is converted into an analog signal, and the integrated amount is taken as the amount of charge.

In other words, the amount of reverse charge generated on the shelf (bottle) - Qbin is Q p
aper and the Qbin are Q paper# -Q
It becomes a bin relationship.

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

As for the upper and lower rollers used, the driving roller 22 was a conductive rubber roller, and the pressing roller 23 was a metal (A4 type) roller.

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.

In addition, a stainless steel fiber brush was used for the static elimination brush. That is, as shown in the front view of Fig. 5 and the side view of Fig. 6, the length of the hair is 12 mm, and the implantation pitch P of the hair is 1.
．． 5 mm, the number of hairs per l pitch is 100, and the total length is 322 mm. This stainless fiber static elimination brush is a brush that belongs to the positive triboelectrification series for sheets that have a static elimination effect on positively charged sheets. The conveyed sheet may be negatively charged depending on the material of the conveying device, but in this case, a static elimination brush made of carbon fiber, etc., which belongs to the negative frictional electrification series, is just as effective as the former case. be.

In Figure 2, the horizontal axis represents the amount of contact between the brush and the sheet, the (+) side represents the contact length from the tip of the bristles to the belly, and the (-) side represents the contact length between the bristles and the sheet surface. It represents the interval between. Moreover, the average amount of charge per sheet is plotted on the vertical axis. The setting of the conventional static electricity removal plan is that the contact 1 is 1.2 mm.
It was common to set it at ~0. When the amount of contact becomes smaller than -2 mm (when the distance between the sheet and the bristles increases), the amount of charge on the sheet increases extremely. When the tip of the bristles reaches a distance of 17 mm from the sheet, the amount of charge reaches 60 nC, which is the same as the amount of charge when the neutralization brush is not used.

On the other hand, if you increase the contact amount in the (+) direction, 1~
Up to 2mm, the effect is not that different from the conventional static elimination brush, but as the amount of contact increases beyond that, the static elimination effect increases, and when the amount of contact increases to 4+++m and 6mm, the amount of static electricity is 11n, respectively.
It can be seen that the concentration decreases drastically to 6nC.

Therefore, bringing the limbs of the static eliminating brush into deep contact with the sheet can be judged to be a much more efficient static eliminating means compared to static eliminating using a conventional static eliminating brush.

In this embodiment, a static elimination brush was provided downstream of the sheet discharge roller pair 18 to the sorter, and the brush was brought into contact with the sheets and the pressing roller to improve the effect. By bringing the static eliminating brush 31 provided downstream of the .19 into contact with the sheet and the pressing roller, the static neutralizing effect on sheets such as copy paper collected on a normal collection table is improved in the same manner as on sheets collected on a sorter.

In addition, in the third embodiment, static eliminating brushes are provided both downstream of the pair of paper discharge rollers after fixing and downstream of the pair of paper discharge rollers at the paper discharge port to the sorter, and are brought into contact with the sheets and the pressure roller, respectively. When the sheet is collected at the same time, the amount of static charge is reduced by half. However, in practice, it is sufficient to provide a static elimination brush at the paper discharge port to the former sorter.

Incidentally, contrary to what is shown in FIGS. 1 and 3, the static eliminating 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 surface of the drive roller. In this case as well, the same static elimination effect as in FIG. 2 is obtained. Further, it is also possible to have such static eliminating blanks coexist on the front and back sides, and the static eliminating effect can be further enhanced.

〔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 is a schematic diagram of a sheet static eliminator according to one embodiment of the present invention and a method for measuring its effectiveness. FIG. 2 is a graph showing the relationship between the amount of contact of the static elimination brush to the sheet and the amount of charge. FIG. 3 is a schematic diagram of an electrophotographic copying apparatus incorporating an embodiment of the present invention. FIG. 4 is a front view of the static elimination brush. FIG. 5 is a side view of the static elimination brush. 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 (2)

[Claims] (1) An image recording apparatus characterized in that the bristle part of the static elimination brush provided on the sheet conveyance path of the image recording apparatus is arranged so that the long limbs from the tip of the bristle to the abdomen come into contact with the surface of the sheet. Sheet static eliminator. (2) The static elimination brush is a brush made of a material that has a positive frictional electrification series for a positively charged sheet, and a brush that is made of a material that has a negative frictional electrification series for a negatively charged sheet. 2. A sheet static eliminator for an image recording apparatus according to claim 1.