JPH04303855A - Automatic document feeding device - Google Patents

Abstract

PURPOSE:To offer an automatic document feeding device where electrification prevention processing is executed without damaging a carrying characteristic by an endless elastic belt. CONSTITUTION:A pinch roller 8 pressing the endless elastic belt to the glass side of a document platen from the inside is constituted of an electrical conductive shaft body 11 rotated by following the turning of the endless elastic belt and an electrical conductive elastic layer 12 formed on the outside circumference of the body 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder for an electrophotographic copying machine.

0002

2. Description of the Related Art Recently, electrophotographic copying machines that can continuously copy a plurality of original documents have been on the market. This copying machine is shown in Figure 2.
As shown in , simply place a plurality of originals 3 face down on the original placing table 2 provided at the top of the main body of the copying machine 1, tilt the original table cover 4 toward you, and press the switch (not shown). , the automatic document feeder 10 provided on the back side of the document table cover 4 operates, and the documents 3 on the document table 2 are conveyed one by one onto the document table glass 5 from above, and copies are made continuously. I'm starting to be able to do it.

[0003] The automatic document feeder 10 is usually shown in FIG.
As shown in , two drive rollers 7 are installed horizontally above the document table glass 5 (indicated by chain lines) at a predetermined interval in parallel, and an endless roller is stretched between the pair of drive rollers 7. It includes an elastic belt 6 and pinch rollers 8 disposed inside the endless elastic belt 6 in parallel with the drive roller 7 at predetermined intervals. Each pinch roller 8 has elastic layers 8b made of rubber or sponge provided at predetermined intervals on the outer periphery of a shaft 8a that is set to rotate following the rotational movement of the endless elastic belt 6. body layer 8
The endless elastic belt 6 is pressed from the inside toward the document table glass 5 side by the outer peripheral surface of b, and the endless elastic belt 6 and the document 3 are pressed together.
It works to increase the frictional force.

In such an automatic document feeder 10, separation charging occurs between the back side of the endless elastic belt 6 and the drive roller 7 and pinch roller 8, and the front side (transporting side) of the endless elastic belt 6 Frictional electrification occurs between the original 3 and the glass 5, and as the paper is fed repeatedly, the charged charges accumulate on both sides of the endless elastic belt 6 and become static electricity, making it difficult for the original 3 to separate from the belt conveying surface. 3 may pass through the fixed position of the document table 5, or the document 3 may pass through the original position on the document table 5.
This may cause problems such as the paper being stuck to the surface of the paper and not reaching the fixed position, or being unable to be transported and recovered after copying.

[0005]

[Problems to be Solved by the Invention] Therefore, in order to prevent the endless elastic belt 6 from being charged, conductive powder such as carbon black or metal powder may be dispersed in the belt 6, or a surfactant may be added to the belt 6. An attempt is being made to do so. However, the above-mentioned conductive powder is black or dark-colored, and it is not preferable to include the above-mentioned conductive powder in the belt 6, which originally requires a high degree of whiteness as the background of the original document 3. Further, when the conductive powder is dispersed and contained, the frictional characteristics and elastic modulus of the belt 6 change from the original characteristics of rubber, which causes problems in paper feeding. On the other hand, the above-mentioned surfactant has the disadvantage that its effect does not last long and that the surface of the belt 6 becomes sticky due to the bleed phenomenon, staining the original 3 and the original platen glass 5. For this reason, it was considered difficult to provide the belt 6 itself with an antistatic function, and conventionally,
The static charge is removed by pressing a static eliminating brush against the conveyance surface A of the belt 6. However, the static elimination effect was limited to the front side of the belt 6, and had almost no effect on charging on the back side.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an automatic document feeder that is subjected to antistatic treatment without impairing the conveyance characteristics of the endless elastic belt.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the automatic document feeder of the present invention transfers the originals placed on the original platen of an electrophotographic copying machine one by one onto the platen glass. This is an automatic document feeder that automatically feeds documents to documents, and includes two drive rollers arranged horizontally above the document table glass and facing each other in parallel at a predetermined interval, and an endless elastic roller that is stretched between the pair of drive rollers. a belt, and a pinch roller disposed inside the endless elastic belt in parallel with the drive roller and pressing the endless elastic belt from the inside toward the document table glass side by its own outer circumferential surface. a conductive shaft body in which the pinch roller rotates following the rotation of the endless elastic belt;
The structure is comprised of a conductive elastic layer formed on the outer periphery.

[0008]

[Operation] That is, the automatic document feeder of the present invention replaces the pinch roller, which conventionally had an elastic layer made of insulating rubber or sponge and had no electrical conductivity, with a conductive shaft and a conductive elastic layer. The endless elastic belt is made electrically conductive by being composed of body layers, and the electric charge charged on the endless elastic belt can be released to the outside through the pinch roller. Therefore, according to this device, the charges that are charged on the inner surface of the belt due to peeling charging are sequentially removed from the pinch roller, so that static electricity does not accumulate on the inner surface of the belt. Further, since the charge caused by frictional electrification on the front side of the belt is removed to some extent by the pinch roller, there is no problem in document feeding unlike in the conventional case. Moreover, since the endless elastic belt itself is the same as the conventional one, the original characteristics of the belt are maintained, and conveyance problems do not occur.

Next, the present invention will be explained in detail.

The automatic document feeder of the present invention has the same basic structure as the conventional one, but uses a conductive shaft as a pinch roller (indicated by 8 in FIG. 3), for example, as shown in FIG. A combination of a body 11 and a conductive elastic layer 12 is used. This is a major feature of this invention. Therefore, in this automatic document feeder, since the entire pinch roller 8 is electrically conductive, the electric charges that accumulate on the inner surface of the belt due to peeling electrification are sequentially removed from the pinch roller 8 and transferred to the inner surface of the belt. Static electricity does not accumulate. In addition, the charge due to frictional electrification on the front side of the belt is
Since it is removed to some extent by the pinch roller 8,
There is no problem with document feeding, unlike the conventional ones. Note that the pinch roller 8 has a shaft body 11.
is supported by bearings 13 that rotatably support the both ends of the . By connecting the pinch roller 8 to the ground 14 of the machine body, it can be set so that the electric charge escapes from the pinch roller 8 to the ground 14 in sequence.

The conductive shaft 11 of the pinch roller 8 is
Usually, a metal pipe or a metal round bar made of iron, copper, etc. is used.

The conductive elastic layer 12 of the pinch roller 8 is formed of a conductive composition in which a conductive substance is dispersed in an elastic material conventionally used for the elastic layer of the pinch roller. It is preferable that The above elastic material includes ethylene-propylene-diene rubber (EPDM),
Examples include rubber materials such as isoprene rubber (IR) and sponge materials such as urethane foam resin, and examples of the conductive material include carbon black, metals, metal oxides, cationic surfactants, and the like. These may be used alone or in combination of two or more.

The conductive elastic layer 12 is formed by forming the shaft body 11 in accordance with a conventional method using a conductive composition comprising the conductive substance, the elastic material, and various additives used as necessary. is formed around the outer periphery of the However, when preparing the above conductive composition, if the conductive substance is a conductive powder, it is preferable to mix 20 to 120 parts of this to 100 parts by weight (hereinafter abbreviated as "parts") of the elastic material. When the conductive substance is a surfactant, it is suitable to mix 0.5 to 5 parts of this. That is, if the amount of conductive powder exceeds 120 parts, the elastic properties of the resulting elastic layer 12 tend to deteriorate, while if it is less than 20 parts, sufficient conductivity cannot be obtained. In addition, in the case of surfactants, 5
If the limit is exceeded, a bleed phenomenon will occur, contaminating the surrounding parts of the pinch roller 8, and further damaging the original 3 and original platen glass 5 (Fig. 2).
(see). By adding each of the above-mentioned conductive substances, the electrical resistance value of the conductive elastic layer 12 is increased to 10.
When adjusted to 12Ωcm or less, the endless elastic belt 6 (Fig. 3
(Reference)), and setting the resistance to around 108 Ωcm provides particularly excellent effects.

The conductive elastic layer 12 may be provided in plural pieces at predetermined intervals in the axial direction of the shaft body 11 as shown in FIG. 1, or may be provided over the entire length of the shaft body 11. You can do it like this.

Next, examples will be explained together with comparative examples.

[0016]

[Examples 1 to 5] Using a conductive elastic material composition having the composition shown below, a conductive elastic material having a diameter of 20 mm and a length of 15 mm was placed at equal intervals around the outer circumference of a stainless steel rod having a diameter of 8 mm. Four body layers 12 were formed to obtain a pinch roller 8 as shown in FIG.

<Conductive elastic material composition> EPDM 100 parts Carbon black Process oil as shown in Table 1 below
5 to 55 parts (softening agent, vary within this range to maintain a constant hardness) 4 parts dicumyl peroxide (vulcanizing agent)

[0018]
For the five types of pinch rollers obtained in this way, the electrical resistance value of the conductive elastic layer was measured using a Kisley type resistance meter (manufactured by Kisley Co., Ltd.). 100 times built into the document feeder
Evaluation was made by feeding 0 originals and counting the number of failed sheets. These results are also shown in Table 1 below.

[0019]

[Table 1]

[0020]

Examples 6 to 10 Pinch rollers were obtained in the same manner as in the above examples using conductive elastic material compositions having the following compositions.

<Conductive elastic material composition> EPDM 100 parts silica
30 parts cationic surfactant As shown in Table 2 below Process oil 5 parts (softening agent) Dicumyl peroxide (vulcanizing agent) 4 parts

[0022]
The five types of pinch rollers thus obtained were evaluated in the same manner as in the above examples. These results are also shown in Table 2 below.

[0023]

[Table 2]

[0024]

[Comparative Example] A conventional pinch roller was obtained using a conductive elastic material composition having the composition shown below.

<Elastic material composition> EPDM 100 parts silica
30 parts process oil
5 parts (softening agent) Dicumyl peroxide (vulcanizing agent) 4 parts

[0026]
The pinch roller thus obtained was evaluated in the same manner as in the above example. These results are shown in Table 3 below.
Shown below.

[0027]

[Table 3]

From the above results, all of the example products have a conductive substance dispersed in the elastic layer of the pinch roller to enhance conductivity, so that static electricity due to charging does not occur.
It can be seen that the number of document conveyance problems has been drastically reduced compared to the comparative example product.

[0029]

As described above, in the automatic document feeder of the present invention, since the pinch roller is electrically conductive, when this automatic document feeder is applied to an electrophotographic copying machine, the endless elastic belt and drive roller The electric charge generated between the two escapes through the pinch roller. In addition, since the electrical charges on the front side of the endless elastic belt are also released to the outside of the device through the pinch roller, the entire endless elastic belt is not charged.
Document feeding is performed smoothly. Moreover, since we use the same endless elastic belt as before,
The belt's inherent rubber properties are utilized on the conveyance surface, so there are no conveyance problems.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a pinch roller used in the present invention.

FIG. 2 is a perspective view of the copying machine.

FIG. 3 is a partially enlarged perspective view of the automatic document feeder used in the copying machine.

[Explanation of symbols]

6 Endless elastic belt 7 Drive roller 8 Pinch roller 11 Shaft body 12 Conductive elastic layer

Claims (2)

[Claims] Claim 1: An automatic document feeder that automatically feeds originals placed on a document placing table of an electrophotographic copying machine onto a document glass plate one by one, the document feeder automatically feeding a document placed on a document table of an electrophotographic copying machine onto a document glass platen, one by one. two drive rollers arranged parallel to each other at a predetermined interval, an endless elastic belt stretched between the pair of drive rollers, and an endless elastic belt arranged parallel to the drive roller inside the endless elastic belt, A pinch roller that presses the endless elastic belt from the inside toward the platen glass side by its outer peripheral surface, and the pinch roller has a conductive shaft that rotates following the rotation of the endless elastic belt; An automatic document feeder comprising a conductive elastic layer formed on the outer periphery. 2. The automatic document feeder according to claim 1, wherein the electrical resistance value of the conductive elastic layer of the pinch roller is set to 1012 Ωcm or less.