JPH0245231Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a paper feeding device for feeding out sheets one by one from a paper container in a copying machine, a printer, a facsimile machine, etc.

"Prior Art" In copying machines, printers, facsimile machines, etc., recording paper or original documents are stacked and stored in a paper storage section such as a paper cassette or paper tray.
A paper feeding device that feeds sheets one by one is generally provided.

Some of these paper feeding devices have a rubber roller that presses against the top layer of paper stored in a stack in the paper storage section, and feeds the paper using the frictional force generated by the rotation of the rubber roller. There is one that sucks the top layer of paper and sends it out.

By the way, in paper feeding devices that use rubber rollers, paper powder, dust, oil used in equipment bearings, etc. may adhere to the surface of the rubber roller, or the rubber may become damaged due to long-term use or due to the influence of ions due to corona discharge. If the quality of the rubber changes or if the hardness of the rubber changes due to the effects of temperature or humidity, the coefficient of friction between the rubber and the paper will decrease. If the coefficient of friction between the rubber roller and paper decreases, slips will occur between the rubber rollers and the paper, resulting in misfeed. Furthermore, the rubber rollers must be replaced from time to time, which is troublesome.

On the other hand, in an air suction type paper feeding device, suction errors will occur unless the position of the top layer of paper is always kept constant, so the mechanism for this purpose is quite complicated. Furthermore, since it is an air suction type, noise is generated, and to solve this problem, a silencing mechanism is required, which increases the size and cost of the device.

In order to solve these problems, a paper feeding device has been proposed that feeds paper using the attraction force caused by static electricity.

9 and 10 show an example of such a conventional paper feeding device (Japanese Unexamined Patent Application Publication No. 1989-1999).
(See No. 114424). In this paper feeding device, a composite layer consisting of a conductive layer 2, an insulating layer 3, and an electrode pattern 4 is provided on the surface of a rotating body 1 for feeding paper.
A voltage of at most several volts is applied between the electrode pattern 4 and the electrode pattern 4, and the electrostatic field formed thereby attracts the paper 5 and sends it out.

FIG. 11 shows another example of a conventional paper feeding device. (Refer to Japanese Patent Application Laid-Open No. 109631/1983). In this paper feeding device, a positive electrode 12, an insulator 13, and a negative electrode 14 are provided in this order on the surface of the feeding roller 11, and the feeding roller 11 is charged with static electricity to adsorb and feed the paper 15. At this time, double feeding is prevented by the multiple feeding paper prevention tongue piece 16, and the paper is peeled off by the peeling plate 17 and fed to the paper guide plate 18.

However, in such a paper feeding device, the insulator layer 3
Alternatively, since it is extremely difficult for current to flow through the insulator 13, even when a switch for controlling voltage application is turned on, it takes time until static electricity is generated, resulting in a problem of poor responsiveness. Further, even if the switch is turned off, static electricity remains on the insulator layer 3 or the insulator 13.

However, in such paper feeding devices, the paper is generally fed out to a certain extent by the paper feeding rotating body 1 or the feeding roller 11, and then the paper is transported normally by the registration rollers in time with the recording section, etc. There is. With this kind of paper feeding device,
When the registration rollers are rotated, the paper feeding rotating body 1 or the feeding roller 11 is made free and the voltage application is stopped. However, if static electricity remains on the paper feeding rotor 1 or the feeding roller 11 at this time, almost the entire area in the paper transport direction will be charged, and paper jams may occur in the paper transport path.
In the case of a copying machine or the like, there is a problem in that there is a possibility that a transfer defect may occur. Furthermore, especially in the paper feeding device as shown in FIG. 11, the leading edge of the second sheet comes into contact with the feeding roller 11 just before the trailing edge of the first sheet from the top leaves the feeding roller 11. There is a problem in that the second sheet of paper is also sent out following the first sheet of paper, which may cause double feeding. If the delivery roller 11 is not in the form of a roll but in the form of a belt, double feeding may particularly occur.

Therefore, the present inventor first proposed a paper feeding device that can solve these problems.

FIGS. 12 and 13 show a paper feeding device previously proposed by the present inventor. This paper feeding device has a volume resistivity of 10 ¹⁰ Ω・cm when mixed with carbon.
A dielectric layer 21 of about 100 mm is provided on one side of the substrate 22, and a positive electrode 23 is provided on almost the entire area of one side of the dielectric layer 21, and a comb-shaped negative electrode 24 is provided on the other side. , 24, a strong electric field is generated on the other side of the dielectric layer 21, and the static electricity generated thereby is used to attract the paper. The reason why the dielectric layer 21 having a volume resistivity of about 10 ¹⁰ Ω·cm is used is that when a switch (not shown) for controlling the voltage application to both electrodes 23 and 24 is turned off, the dielectric layer 21 is used. This is to provide some conductivity in order to prevent static electricity from remaining in 21, so that electrostatic adsorption force is generated immediately when the switch is turned on. Also, with this paper feeder,
The dielectric layer 21 and the like are reciprocated along the paper, and a high DC voltage is applied only during the forward movement, thereby feeding the paper.

In this paper feeding device, even if the application of voltage to both electrodes 23 and 24 is stopped, static electricity does not remain in the dielectric layer 21, so that the dielectric layer 21 does not remain on the dielectric layer 21, especially on the rear end side of the paper.
Even if it comes into contact with 1, it will not be charged. As a result, paper jams and transfer failures occur in the paper conveyance path, which often leads to problems.

However, in such a paper feeding device, the dielectric layer 2
1 has some conductivity, so the current consumption increases,
There is a problem of high operating costs.

"Problems to be Solved by the Invention" The present invention has been made in view of the above circumstances, and aims to provide a paper feeding device that can reduce current consumption.

"Means for solving the problem" In the present invention, one electrode is provided entirely on one surface of the dielectric layer, and an insulator is provided on the other surface of the dielectric layer at a location corresponding to one electrode. A paper conveyance body in which the other electrode is distributed across the layer so that the other surface of the dielectric layer is exposed, and a voltage application means for applying a DC high voltage to both electrodes of the paper conveyance body. The dielectric layer improves responsiveness and prevents static electricity from remaining, and the insulator layer reduces current consumption. Here, the dielectric layer refers to a material made of a material with a volume resistivity of approximately 10 ⁸ to ^{10 12} Ω・cm, and the insulator layer refers to a material made of a material with a volume resistivity of approximately 10 ¹³ Ω・cm or more. say.

"Outline of the Present Invention" FIGS. 1 and 2 show the main parts of a paper feeding device for explaining the outline of the present invention.

This paper feeding device includes a paper transport body 31 having a flat dielectric layer 32. dielectric layer 32
The volume resistivity with ionic conductivity is
10 ¹¹ It is made of a plastic plate (for example, product name: Bayon, manufactured by Kureha Chemical Industry Co., Ltd.) with a resistance of about Ω·cm and a thickness of about 1 mm. For example, a conductive paint made of silver paste or the like is applied to the back surface of the dielectric layer 32.
One rectangular electrode 33 is formed by applying the solution to a cm square area. On the surface of the dielectric layer 32, there is also a 13 cm square with a depth of about 0.2 mm and a width of 1 mm.
Comb-shaped recess 3 with a gap of about 6 mm
4 is formed. An insulating layer 35 is formed by applying an insulating paint made of epoxy resin or the like to a thickness of about 0.1 mm to the recess 34, and then a conductive paint made of silver paste or the like is applied to the remaining recess. Thus, the other comb-shaped electrode 36 is formed.

In this paper conveying body 31, both electrodes 33, 3
When a DC high voltage is applied between 6 and 6, the dielectric layer 32
A strong electric field is generated in the exposed portion of the other surface of the paper, that is, in the gap between the other comb-shaped electrodes 36, and static electricity for attracting the paper is generated in this portion. Therefore, the dielectric layer 32 and the other electrode 3
Even if the insulating layer 35 is provided between the paper sheets 6 and 6, there will be no problem in adsorbing the paper.

When the voltage-current characteristics of this paper conveyance body 31 were investigated, the results indicated by the symbol A in FIG. 3 were obtained. On the other hand, the voltage of a paper conveying body 31 having a similar structure but not having an insulating layer 35 is -
When the current characteristics were investigated, the results indicated by the symbol B in the figure were obtained. Note that in FIG. 3, the horizontal axis represents the DC voltage applied to both electrodes 33 and 36 of the paper transport body 31, and the vertical axis represents the current flowing through the dielectric layer 32 at that time.

As is clear from this experimental result (Figure 3),
It can be seen that the insulator layer 35 contributes to reducing current consumption.

"Example" The present invention will be described in detail with reference to Examples below.

FIG. 4 shows the main parts of a copying machine to which an embodiment of the present invention is applied.

This copying machine is equipped with a belt-shaped paper conveyor 41. As shown in FIG. 5, the paper conveyor 41 has a dielectric layer 43 adhered to the surface of an insulating support layer 42 made of polyester film or the like, and a protective layer 44 pressure-bonded to the surface of the dielectric layer 43. It has a unique structure. One electrode 45, an insulating layer 46, and another electrode 47 are provided on the back and front surfaces of the dielectric layer 43, and the materials and dimensions of these electrodes are as explained in the "Summary of the Present Invention" section. There is. However, one end in the width direction of one electrode 45 and one end in the width direction of the other electrode 47 (the part corresponding to the handle of the comb) are both exposed, and these exposed parts are connected to the DC high voltage power supply 48 via a brush or the like (not shown). ing. The protective layer 44 is provided from the viewpoint of safety, and is mainly composed of, for example, thermoplastic synthetic resin and synthetic rubber, with addition of appropriate pigments, stabilizers, plasticizers, anti-aging agents, etc. as necessary. It is made of a plastic sheet with a volume resistivity of about 10 ⁸ to 10 ¹² Ω·cm and a thickness of about 0.1 mm.

In this copying machine, a paper cassette 51 is detachably loaded. Paper cassette 5
1 has a well-known structure, and when loaded into a copying machine,
Due to the force of a spring (not shown), the top layer of sheets 52 stacked and stored on the belt-shaped sheet conveying body 4
1, that is, the surface of the protective layer 44, in the same manner at all times.

In this copying machine, when a paper feeding motor (not shown) is driven, a belt-shaped paper conveying body 41 is rotated in the direction of the arrow. When the paper transport body 41 is rotated in the direction of the arrow and at the same time a DC high voltage of, for example, 1500 V is applied to both electrodes 45 and 47, only the uppermost layer of paper 52 is sent out from the paper cassette 51. The leading edge of the fed paper 52 comes into contact with a pair of registration rollers 53 and 54 and is stopped, thereby adjusting its posture. After that, at a predetermined timing, the pair of registration rollers 53, 5
4 is rotated in the direction of the arrow, conveyance of the paper 52 is started. When the leading edge of the paper 52 passes between the pair of registration rollers 53 and 54, a sensor (not shown) detects this and stops the paper transport body 41 and stops applying voltage to both electrodes 45 and 47. . Thereafter, the paper 52 is conveyed by a pair of registration rollers 53 and 54, and sent to a toner image transfer site on a photosensitive drum 56 via a paper guide plate 55.

Now, the inventor of the present invention further conducted various studies and experiments, and measured the incidence of paper double feeding by changing the gap between the other comb-shaped electrodes 47, and the results shown in FIG. 6 were obtained. Obtained. At this time, the other comb-shaped electrode 47 serves as the belt-shaped paper conveyor 41.
Using 6 types with a gap interval of 1 to 6 mm,
The applied voltage was about 1500V.

As is clear from this experimental result (Figure 6),
The gap between the other comb-shaped electrodes 47 is 1 to 4 mm.
It can be seen that double feeding is less likely to occur if the value is lower than or higher than that, and double feeding is likely to occur if the value is lower or higher.

By the way, in the paper feeding device as shown in FIG. 4, the leading edge of the paper 52 sent out from the paper cassette 51 is charged by the static electricity of the paper transport body 41, which may cause paper jams in the paper transport path or transfer problems. Failure to do so may result in defects.

FIG. 7 shows the main parts of a copying machine equipped with a paper feeding device that can solve these problems. In this figure, the same parts as in FIG. 4 are designated by the same reference numerals, and the explanation thereof will be omitted as appropriate.

In this copying machine, a pair of charge eliminating brushes 61 and 62 are provided between a belt-shaped paper conveyor 41 and a pair of registration rollers 53 and 54. The static eliminating brushes 61 and 62 are made of carbon-dispersed acrylic fibers (for example, manufactured by Toray Industries, Inc. designated as SA-7) with a thickness of about 30 to 40 μm and a volume resistance of about 10 ⁴ Ω・cm and a length of 5 mm. They are planted on a base material at a density of about 50,000 plants per square inch. These static eliminating brushes 61 and 62 are arranged so that the tips of their respective fibers are located on substantially the same plane. Further, the length of the static eliminating brushes 61 and 62 may be the same as the width of the paper 52, or may be the same as the width of the belt-shaped paper transport body 41. It goes without saying that the static eliminating brushes 61 and 62 are both grounded.

In this copying machine, when paper 52 is sent out from a paper cassette 51 by the action of a belt-shaped paper conveyor 41, it is transferred to a pair of static eliminating brushes 61 and 62.
A pair of registration rollers 53, 54 pass between the
It will be sent between. When the paper 52 passes between the pair of static eliminating brushes 61 and 62, both the front and back surfaces thereof come into contact with each fiber of the pair of static eliminating brushes 61 and 62, thereby eliminating static electricity.

Here, the paper transport body 31 as shown in FIG.
A high DC voltage of 1000V was applied, a 10 x 10 cm sheet of paper was adsorbed to it, and then it was peeled off and the amount of charge was measured, and it was found to be charged to about 0.05 μc/100 cm ² . On the other hand, the entire surface of the paper that has been peeled off from the paper transport body 31 is covered with a static eliminating brush 6 as shown in FIG.
1,62 and then measured the amount of charge, it was found to be extremely small at about 0.0015 μc/100 cm ² . If the amount of charge is about 0.05 μc/100 cm ² , there is a risk of paper jams or poor transfer, but if it is about 0.0015 μc/100 cm ² , there is no risk of such problems occurring.

By the way, in the copying machine shown in FIG. 7, the lower surface of the paper 52 sent out from the paper cassette 51 comes into contact with the fibers of the lower static elimination brush 62 and is subjected to resistance. Therefore, even if double feeding occurs and two sheets of paper 52 are sent out from the paper cassette 51 at the same time, the suction force of the paper conveyor 41 against the second sheet of paper 52 is weak as described above.
The sheet of paper 52 comes into contact with the fibers of the lower static elimination brush 62 and is held there. Therefore, the weight generation rate is further reduced. Especially paper 5
2 is thin, such as mail paper with a thickness of about 55 μm, the paper cassette 51
Although there is a risk that two sheets may be fed out at the same time, double feeding can be effectively prevented by the static elimination brush 62 on the lower side.

In the above embodiment, the other electrode 4 is inserted into the comb-shaped recess formed in the dielectric layer 43 via the insulator layer 46.
7 is provided, but the present invention is not limited to this, and any structure may be used as long as the dielectric layer 43 and the other electrode 47 are isolated by the insulating layer 46. For example, as shown in FIG. 8, a dielectric layer 43 is provided in the gaps and around the comb-shaped insulator layer 46 to form a sheet, and one electrode 45 is provided on one surface of the dielectric layer 43. The other electrode 47 on the other side
It is also possible to have a structure in which

Further, in the above embodiment, one electrode of the paper conveyance body is shaped like a comb, but it is not limited to this, and may have any shape as long as it is dispersed, such as a mesh. Alternatively, one electrode may be set to the negative side and the other electrode may be set to the positive side, and a high DC voltage may be applied between these electrodes. In this case, a protective layer may be particularly provided to prevent electric shock. Furthermore, although the paper conveyance body is in the form of a belt or a flat plate, it is of course possible to have a roller shape. When the paper transport body is made into a flat plate, the driving force of the paper feed motor is transmitted to the paper transport body via a transmission mechanism consisting of a wire or a pinion and a rack, etc., and the paper transport body is made to perform linear reciprocating motion. do it.

Further, although a pair of static eliminating brushes is used in the above embodiment, it is also possible to use only one of the upper and lower ones. Further, the static eliminating brush may be formed into a roller and can be freely rotated, and furthermore, a group of metal pieces may be used instead of fibers.

The copy paper is made by sandwiching an aluminum plate with paper, for example, so that when the metal detector installed in the copying machine detects the aluminum plate, the copying operation will not be performed, thereby making it possible to re-copy. Although there are some devices in which this is not possible, the present invention can of course be applied to such paper feeding.

"Effects of the Invention" As explained above, according to the present invention, current consumption is reduced, so operating costs can be reduced.

[Brief explanation of drawings]

FIGS. 1 and 2 are a plan view and a cross-sectional view taken along the line X-X of a paper conveyance body shown for explaining the outline of the present invention, respectively, and FIG. 3 shows the voltage-current characteristics of the paper conveyance body. Diagram shown for explanation, No. 4
The figure is a schematic configuration diagram showing the main parts of a copying machine to which an embodiment of the present invention is applied, Figure 5 is a cross-sectional view of a belt-shaped paper conveyor of the same copying machine, and Figure 6 is a diagram showing the same paper conveyor. FIG. 7 is a diagram illustrating the incidence of double feeding due to a difference in the spacing between the other comb-shaped electrodes, and FIG. 7 is a schematic configuration showing the main parts of a copying machine to which another embodiment of the present invention is applied. FIG. 8 is a sectional view of a part of a paper conveying body in still another embodiment of the present invention,
9 and 10 are a side view and a cross-sectional view of a part thereof, respectively, showing an example of a conventional paper feeding device, and FIG. 11 is a side view showing another example of a conventional paper feeding device,
FIGS. 12 and 13 are a plan view and a sectional view taken along the line Y--Y of a paper conveying body of a paper feeding device previously proposed by the inventor of the present invention, respectively. 31, 41... Paper transport body, 32, 43... Dielectric layer, 33, 45... One electrode, 35, 46
... Insulator layer, 36, 47 ... Other electrode, 42
... Support layer, 44 ... Protective layer, 51 ... Paper cassette, 52 ... Paper, 61, 62 ... Static elimination brush.

Claims (1)

[Scope of utility model registration request] One electrode is provided entirely on one surface of the dielectric layer, and the other electrode is provided on the other surface of the dielectric layer through an insulating layer at a location corresponding to one electrode on the other surface of the dielectric layer. A paper transport body is distributed so that one surface is exposed, and a high DC voltage is applied to both electrodes of this paper transport body to generate static electricity to attract the paper to the other surface of the dielectric layer. 1. A paper feeding device comprising: voltage application means for applying voltage.