JPH06301270A - Charge (or charge removal) member - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To obtain a charging / discharging member provided with conductive fibers in a brush shape for use in an image forming apparatus. [Structure] At least a part of fibers of a brush-shaped fiber 401 that does not come into contact with a surface to be charged (or static elimination) is held by a yarn 40.
It is converged and held at 2 to prevent it from falling and falling.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus utilizing an electrostatic transfer process such as an electrostatic copying machine and a printer, and more particularly to a charging member suitable for use in the apparatus.

In the well-known image forming apparatus as described above, when a uniform charged surface is formed on the image carrier, the transfer material is transferred from the image carrier when the toner image on the surface is transferred to the transfer material. A charging or static eliminating means is used for separation and the like.

Examples of such charging / discharging means are those that do not come into contact with the surface to be charged, such as an image carrier such as a corotron or a grounded discharging needle, and blades, brushes and rollers made of a conductive material. There are many known ones that contact the surface to be charged.

The former charging / discharging means that does not come into contact with the image carrier or the like requires a high voltage as a bias voltage for obtaining a necessary electric field, which makes the power source large and generates ions. There's a problem. In addition, among the contact types, those that are normally driven to rotate, such as cylindrical rollers and brushes, are likely to cause variations in the resistance value in the rotation direction and contact unevenness. It is necessary to suppress it.

On the other hand, a plate-shaped blade or brush does not require a drive mechanism, and it is not necessary to consider the occurrence of uneven charging in the rotation direction due to the drive mechanism. If it is possible to obtain good results.

At the same time, in the contact type charging means such as the charging brush extending in the axial direction of the image carrier or the like,
There is a problem that electrification failure occurs due to hair removal and fallen hair, and it is difficult to uniformly abut this on the image carrier or the like over the entire length, and uneven charging due to uneven contact pressure, and in the brush longitudinal direction There are problems such as short life of the brush due to uneven force.

In the brush type charging member as described above, the hair fall can be prevented by shortening the free length of the brush portion and strengthening the waist, but this method grinds the charged surface excessively. This is not desirable.

The present invention has been made in order to cope with such a situation as described above, and of the brushes for charging or discharging, which are arranged to extend in the longitudinal direction of the surface to be charged, contact the member to be charged or discharged. A charging member that can effectively prevent falling and pulling out of fibers that form a brush by converging and holding the unwound portion, and that can constantly and stably contact the charged or neutralized surface with an appropriate contact pressure. It is intended to provide.

[0009]

[Constitution of the invention]

In order to achieve the above object, the present invention relates to a charging (or discharging) member provided with a brush-shaped fiber which is in contact with a surface to be charged (or discharging). The fibers of a part of the free length portion that does not come into contact with the surface to be charged (or static elimination) of the filamentous fibers are converged and held by the holding yarn, or the fibers are not converged and held by the holding yarn in the member. The free-length portion is shorter than the other portions in the vicinity of both ends of the brush-like fiber.

According to this structure, it is possible to obtain a charging or discharging member which is less likely to cause the fibers to be removed or fallen while maintaining the advantages of the brush-shaped charging or discharging member.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a mode in which the above-described charging or discharging means is used in a color image forming apparatus having a relatively narrow contact pressure range will be briefly described with reference to FIG.

Inside the main body of the apparatus, there is provided an image carrier 1 in the form of a rotary cylinder extending in the direction perpendicular to the plane of the drawing, and a transfer drum 8 formed of a sheet made of a dielectric material comes into contact with the image carrier 1. It rotates synchronously with the image carrier 1.

The surface of the image carrier 1 is uniformly charged by the primary charging means 2, and a laser beam modulated by an image signal of a yellow component color of a document (not shown) is projected on the charged surface by a polygon mirror 17. The electrostatic latent image is formed by scanning. This latent image reaches the developing site where the developing device 3 is arranged oppositely. The developing device 3 is provided with four developing devices 3a, 3b, 3c and 3d, as shown in the drawing, and is rotatably arranged. The developing device 3 accommodates yellow toner, magenta toner and cyan toner, respectively. It is adapted to be brought to a developing position close to the carrier 1.

When the latent image of the yellow component color arrives at the developing portion, the developing device 3a containing the yellow toner has arrived at the developing portion by this time, and the yellow toner image is formed by the toner supplied from now. The yellow toner image reaches a transfer portion facing the transfer drum 8 as the image carrier 1 rotates.

The transfer drum 8 is formed by cylindrically forming a sheet made of a dielectric resin material such as polyethylene terephthalate, polyvinylidene fluoride, and polyurethane, and rotates in synchronization with the image carrier 1.

As described above, when the yellow toner image reaches the transfer portion, the transfer material 6 in the cassette 60 is not taken out by this time and is supplied to the transfer drum 8 via the registration roller 13. The transfer material is conveyed to the transfer portion at the same timing as the yellow toner image in a state where the transfer material is adsorbed and fixed to the transfer drum by a charging means 16 for adsorption provided on the transfer drum side and an adsorption roller 16a serving as an opposite electrode. .

When the yellow toner image on the image carrier and the transfer material on the transfer drum reach the transfer portion, a transfer bias is applied to the transfer charging means 4, and the yellow toner image is transferred by the action of the electric field formed. Transfer to wood. After that, the transfer material rotates together with the transfer drum while carrying the toner image, and reaches the transfer portion again.

The image carrier on which the yellow toner image is applied to the transfer material is rotated as it is, the residual toner which has not contributed to the transfer is removed by the cleaner 5, and the charged surface is formed again by the charging means 2, and the original is formed on this surface. When a latent image of magenta component color is formed and the latent image reaches the developing portion, the developing device 3 that has reached the developing portion by this time
Magenta toner is applied by b to form a magenta toner image, which reaches the transfer portion.

Here, by the operation of the transfer charging means 4, the magenta toner image is superposed and transferred onto the yellow toner image of the transfer material. Similarly, the cyan toner image and the black toner image are sequentially transferred to the transfer material, and the transfer process is completed.

When the transfer step is completed, the transfer material is released from the adsorption on the transfer drum by the action of the separation charging means 15, and is removed from the transfer drum 8 by the action of the separation discharge preventing charger 14 by the action of the separation discharge preventing charger 14. Then, the toner of each color is melted and mixed at a fixing portion, which is a nip of the differential roller 7a and the pressure roller 7b, through a conveyance path 23, and is fixed as a color image on the transfer material. Is discharged.
The floating toner and the like attached to the transfer drum 8 are to be removed by the cleaning means 17 and the facing member 17a.

In such an apparatus, as can be seen from the figure, it can be used in various places such as a primary charging means 2, a transfer means 4, a cleaning means 17, an adsorption charging means 16 and an unbalanced means 15 as a charging or discharging means. . Examples of the brush charging means used in such a part are "FIG. 5" and "FIG. 6".
Explained by. The one shown in the figure is used as a transfer means, but is not limited to this. Figure 5 "
Is a perspective view of the charging brush, and FIG. 6 is a side view showing a state in which the charging brush is used as a transfer unit.

The charging means 4 implants conductive fibers 401 in a brush shape on the conductive holding member 4a and transfers the conductive fibers 401 at a transfer portion where the image carrier 1 and the transfer drum 8 come into contact with each other as shown in FIG. A transfer bias is applied from the inside of the drum by pressing against it. Here, as the conductive fiber, it is possible to use a generally known one such as metal fiber of aluminum, stainless steel, etc., acrylic, rayon, etc. in which carbon black or the like is mixed to appropriately adjust the volume resistivity. .

In this case, the brush portion 401 of the charging means 4
If the contact pressure on the transfer drum is too weak, a minute gap is generated between the inner surface of the transfer drum and the conductive fibers of the brush, which causes deterioration of image quality. Further, if the contact pressure is too strong, there is a problem in that the toner inside the line area is not transferred when the line image is output, and the image density decreases.

FIG. 1 is a perspective view of a charging member showing an embodiment of the present invention, in which a conductive member 401 as described above is planted in a brush shape on a holding member 4a made of a conductive material such as aluminum. The holding yarn 40 is provided in the lateral direction in the figure, leaving an appropriate length on the side of the fiber 401 that abuts the surface to be charged.
Formed by weaving 2. As the holding yarn 402, the same one as the fiber 401 can be used.

In order to manufacture such a charging member, the fibers 401 are used as warp yarns, the fibers 402 are used as weft yarns, and are woven in a plain weave shape, cut into an appropriate length, and one edge is held by the holding member 4a.
Then, a suitable number of weft yarns on the free edge side of the fiber may be removed.

When the charging member having such a structure is used, for example, as shown in the above-mentioned "FIG. 6", by appropriately setting the length of the tip portion of the brush-like fiber portion of the charging member where the weft does not exist, Since each fiber rubs the surface to be charged in relation to each other, the difference in the contact pressure of each fiber to the surface to be charged is dispersed and averaged, and a uniform contact pressure is obtained as a whole, and hair removal, Resistant to falling hair.

FIG. 2 is a perspective view of a charging member showing another embodiment, in which the charging member as shown in FIG. 5 has a fiber portion protruding from the holding member 4a. A weft yarn which is a holding yarn is arranged. It can be easily understood that the structure as described above can achieve the same operation as that of the above-mentioned embodiment.

FIG. 3 is a perspective view of a charging member showing still another embodiment. It has been found that when the charging member is brought into contact with the surface to be charged as shown in the above-mentioned "FIG. 6", the fibers at both ends of the brush-like fibers are prone to fall over.
In this embodiment, both side portions E are provided to prevent this.
The holding thread 402 in the section is appropriately bent to shorten the free length of the brush fiber. With this structure, the strength of the free length portion is substantially increased to prevent collapse, and the contact pressure at the end portion where the contact pressure tends to be weak can be increased.

Although the charging member used in the transfer portion has been described above, the present invention is not limited to this, and the charging member and the charge removing member used in each part of the image forming apparatus as described above are also applicable. Of course, it can be applied to.

[0030]

As described above, according to the present invention, the surface to be charged can be evenly contacted and abutted, and hair removal,
It is possible to obtain a highly reliable and highly durable charging or discharging member by preventing hair fall.

[Brief description of drawings]

FIG. 1 is a perspective view of a charging member showing an embodiment of the present invention.

FIG. 2 and

FIG. 3 is a perspective view of a charging member showing another embodiment, respectively.

FIG. 4 is a schematic side sectional view of an image forming apparatus suitable for applying the present invention.

FIG. 5 is a perspective view showing a known charging member.

FIG. 6 is a side view of a main part when the above member is used as a transfer charging member.

[Explanation of symbols]

 1 image carrier 2 primary charging means 3 developing device 4 transfer charging means 4a holding member 7 fixing device 8 transfer drum 15 separation charging means 16 adsorption charging means 401 brush-like fiber 402 holding thread

Claims (2)

[Claims] 1. A charging (or static eliminator) member comprising brush-shaped fibers that come into contact with a surface to be charged (or static eliminator), wherein a free-length portion of the brush-shaped fiber that does not come into contact with the surface to be charged (or static eliminator) A charging (or neutralizing) member characterized in that a part of each fiber is converged and held by a holding yarn. 2. The charging (or neutralizing) member according to claim 1, wherein the free length portion where the fibers are not converged and held by the holding yarn is shorter than the other portions in the vicinity of both ends of the brush-like fiber.