JPS62168176A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a sharp image having no fog by putting an electrostatically charged developer opposite an image carrier by rotating a developer support body which carries the charged developer by a layer forming means. CONSTITUTION:The developer support body 3 faces the image carrier 1 across a gap (g) and rotates in a direction different from the rotational direction of the image carrier 1 to carry a developer on its surface. The contained developer 10 is supplied to the support body 3 according to the rotation of the developer support body 3, and the supplied developer 10 is pressed and charged electrostatically by the layer forming member 7. The developer support body 3 which carries the developer 10 charged by the layer forming member 7 is rotated to put the charged developer 10 opposite the image carrier 1. Consequently, the developing device which forms a sharp image having no fog is obtained.

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a developing device that visualizes an electrostatic image. (Prior Art) As developing devices for visualizing electrostatic images, those using fur brush development, cascade development, and magnetic plan development are known. (Study points to be solved by the invention) In these conventional developing devices, since the developer is indiscriminately brought into contact with the holder that holds the electrostatic image, the holder is Developer adheres not only to areas where electrostatic images exist (called image areas), but also to areas where there are no electrostatic images, and where the temperature does not reach ℃ (referred to as non-image areas). The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a developing device that can obtain clear images without causing fogging. purpose. [Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention arranges a rotating image carrier and a developer support to face each other with a gap therebetween, and to The developer supports are made to differ from each other, the developer is supported on the surface by rotation of the developer support, and the developer is further charged by a layer forming means. (Function) Since the developer is uniformly charged by the layer forming means, charging failures are prevented and images without fogging can be obtained. (Example) The present invention will be described below with reference to illustrated examples. FIG. 1 is a front view showing an embodiment of the present invention, showing a schematic configuration. Reference numeral 1 denotes a holder for holding an electrostatic image, and has an insulating layer or a photosensitive layer on its surface. - As an example, a diameter of 78 m
A photosensitive drum was used, in which the surface of an aluminum drum with a thickness Q of 13 mm was coated with fine zinc oxide powder dispersed in a resin dispersion medium. An electrostatic image 2 is formed on the surface of this holder. In the above-mentioned example, the electrostatic image 2 is formed by gradually charging the surface of the holder 10 by a well-known corona charging method or the like, and then performing imagewise exposure. Of course, other patterns depending on the image to be formed may be formed using a cathode ray tube or laser light, or a dot pattern of electrostatic charges may be formed using a needle electrode or the like. Now, the above-mentioned holder 1 moves at a circumferential speed of 80 in the direction of the arrow shown in the figure.
It was rotated once at a rate of mm/sec, and the potential of the electrostatic image 2 on the surface was -500V. Note that the aluminum drum of the holder 1 is grounded. A moving member 3 is provided opposite the holding body 1. The moving member 3 is, for example, an aluminum whamlow with a diameter of 25 mm.
The surface of No. 2 was treated with a satin finish. This matte finish is performed, for example, in such a way that the depth of the unevenness formed by this process is the same as or several times the particle size of the developer. The moving member 3 has a shaft 4
- for example, at a circumferential speed of 80 mm.
It is rotated at /sec. Further, the movable member 3 is connected to ground or to a power source 5 for AC bias, and is switched to either connection by a switch. As a switch, a switch 6 having one circuit and two contacts as shown in the figure was used. The moving member 3 is arranged opposite to the holder 1 with a gap g. According to experiments, the gap g is 50 μm.
~300 μm is suitable; a gap g of 80 μm was set as an example. - 10,000, the layer forming member 7 is pressed into contact with the moving member 3. These 71 members are made of an elastic material, such as a rubber blade with a hardness of 60 to 70, and one end of this rubber blade is held by a holder 8. The center portion of the rubber plate is pressed against the moving member 3. When the pressing force of the member 7 is strengthened, the density of the developer in the developer layer formed on the surface of the moving member 3 decreases, and when the pressing force is weakened, the density increases. These moving member 3 and I-forming member 7 are housed in a case 9 that forms the outer shape of a developing device. Case 9 is a housing made of an unsuitable material such as glass stick, and contains an image brightening agent]0 (hereinafter referred to as toner).
is stored. The toner 10 has a particle size of 12 to 15
The lower end of the case 9 is sealed by a sealing member 11 such as urethane so that the toner 10 leaks out. There is no such thing. Further, the movable member 3 is pressed against a scraping member 2. This member 2 is, for example, a phosphor-backed copper plate, and has the function of scraping off the toner 10 stuck to the moving member 3 and always supporting new toner 10 on the surface of the moving member 3. Note that the movable member 3 rotates in the direction shown in the figure, and the circumferential speed is the same as that described above. You can increase the # degree of the image. As mentioned above, rubber grade was used for the layer forming member 7 for the housing, and this rubber grade with a hardness of 60 to 70 degrees was used.
The toner 10 was brought into pressure contact with the movable member 3 with a width of 2 mm, and the pressure at the contact point was 700 g/cm 2 , and the layer of toner 10 formed in this case had a diameter of approximately 100 toner particles. To explain the operation of the above configuration, the square holder 10
An electrostatic image 2 is formed on the surface. Its surface potential is -50
0V, and this negatively charged portion becomes the image area. Since the movable member 3 moves in the direction of the arrow shown in the figure, the toner 10 also moves along with this movement, and eventually moves between the members 7 and 3 together with the member 3 against the pressing force of the member 7. Moving. And at this time, toner] 0 is toner - 10
Physical contact between toner 10 and member 7 (this member 7
As mentioned above, rubber grade is used, but
The resistance value is triboelectrically charged by physical contact with the material (a resistance value of 10 to 100 is chosen as an example). In this case, since the image area is negatively charged, the toner 10 is positively charged. Therefore, it is triboelectrically charged by the layer forming member 7,
Furthermore, a thin layer T of the toner 10 is formed on the surface of the moving member 30 due to the pressing force. This thin layer T moves while being supported by the moving member 3, and eventually reaches the development area DK. That is, since the toner 10 is electrically charged, it is electrostatically absorbed by the movable member 3, and reaches the developing area in a state of being blown. And in the area,
Since the electrostatic image 2 faces the image 2, the toner 10 is attracted to the support 1 side by the negative charge of the image 2, and is finally blown away. That is, the positively charged toner 10 is
Coulomb force f3 acting between and moving member 3;
Coulomb force fj acting between toner 10 and support 1
As a result, a force is applied in the right direction in FIG. 1, respectively. Then, in the development area, f(f), the toner 10 will fly toward the support 1, and the toner 10
is attached to image 2. When the development is performed in this manner, the movable member 3 continues to move in the direction of the arrow, so it eventually passes the sealing member 11 and then faces the scraping member. Then, the layer T' of residual toner adhering to the surface of the moving member 3 is scraped off by the scraping member 12. Then, by further moving the moving member 3, it again faces the layer formation &15@' 7, and the above-described operation is repeated. In this way, continuous development is performed. Note that when the switch 6 is switched and the moving member 3 is grounded,
We were able to obtain clear images with the least amount of fog. On the other hand, switch 6 to switch the AC bias to power supply 5.
Although some fogging occurred when the toner was applied, the flying efficiency of the toner 10 was significantly increased, and the gap g could be set correspondingly larger. It is also possible to apply a DC bias to have the effect of a well-known developing electrode, and by using AC and DC bias together,
The two effects mentioned above can also be obtained. Now, some other embodiments will be described further with reference to FIG. This shows another example of the layer forming member 7, in which the member 7 is coated with aluminum electrodes 14 on conductive rubber grade 14.
It has a structure obtained by polymerizing No. 3. Note that the moving member 3 is supported by a shaft 4 here.

[A shaft-supported metal roller 3aK4 with a surface 3b made of electrically conductive rubber is used. Further, a switch ] 7 is connected to the member 7 via an electrode 13 , and the switch ] 7 is connected to ground or a power source 16 . Then, when electric power 16 is applied to member 7, toner 10
Charging was performed well. In addition, the surface 3 of the moving member 3
Since b has elasticity, it is possible to buffer the pressing force applied to the toner at the part where it comes into pressure contact with the member 7, so that a large physical force is not applied to the toner and does not affect its charging characteristics. do not have. Furthermore, if a wire 5 is stretched in contact with the surface of the movable member 3 in the axial direction in the current W region, as the movable member 3 moves, more toner T collides with the wire 15. The efficiency with which the toner 10 leaves the moving member 3 and flies toward the holder 1 can be increased. This can be said to mechanically obtain the effect of the AC bias mentioned above (the former obtains this effect by electrical means). Note that the formation of the charged toner layer T by the member 7 and the developing mechanism are the same as in the example shown in FIG. 1, and therefore will not be described in detail. Moreover, FIG. 3 shows another example of the moving member 3. That is, the member 3 is formed by providing a wire mesh roller 3c with an insulating layer, for example, a layer 3d coated with Mylar or Teflon (all trade names). In front of the position where the member 3 faces the member 7,
It is charged by a charger 18. Emperor 11! A contact type container 18 is used here. In this case, a carbon vapor 20 is provided in the holder 19, a 4-electroconductive adhesive l-21 is provided on this vapor 20, and this layer 2
1 is flocked with conductive fibers, such as Il, EC-A (trade name), and is heated to a temperature of .degree. This fiber is awned at 22. With such a configuration, when a negative voltage is applied to the charger 18 from the power supply 23, a minute discharge between the fibers 22 causes the insulation layer 3 of Mylar or Woma Teflon to be damaged.
d is negatively charged. Then, by rotating clockwise in FIG. 3, the moving member 3 eventually faces the member 7. and. Here, NiT of the toner 10 is formed. At this time, as described above, the toner 10 is triboelectrically charged by the pressing force of the member 7. Furthermore, since the layer 3d is negatively charged, the electrostatic absorption force between the toner 0 and the member 3 is
It is larger than the example in FIG. Then, when the member 3 faces the image 2, a Coulomb force f/ acts on the toner 10 and the member 3, as shown in FIG. Force f/
j acts, and the force relationship between these becomes fl, (when flj, the toner 1o separates from the member 3 and flies along with the holder).And here, as mentioned above, the trap, the layer 3
Since d is negatively charged and has a negative charge, f'>-, the energy of the VC from which the toner 10 is separated can be controlled, and fogging can be prevented in the same manner as the effect of the DC bias described above. The configuration described above has the following effects. - Since the movable member moves with a gap relative to the holding body,
The developer is attracted by Coulomb force due to the presence of electric charges in the image area, and since the developer does not come into contact with non-image areas, the developer is layered only in the image area, making it possible to obtain a clear image without fogging. . In addition, since the charged developer is supported by the moving member,
No special developer conveying means such as magnetic force is required. Furthermore, since the moving member moves faster than the holding body,
Since the developer layer facing the image area is replenished one after another, the image density can be increased. Furthermore, by using a non-magnetic component developer, there are no problems such as unreliability of the magnetic developer conveyance means and poor transfer efficiency as with magnetic component developers. This is a point where the #iS advantage of applying the present invention to indirect electrophotography has sufficient merits. Furthermore, by using an elastic body that presses against the moving member as the layer forming member, it is possible to triboelectrically charge the cedar gap agent and form a uniform developer. In addition, since the moving member is electrically conductive and is grounded, a potential difference between the moving member and the holder in the developing area can be stably established, resulting in a clear image. By applying an AC bias to the moving member, the developer flying efficiency is reduced. By forming irregularities on the surface of the movable member, the developer can be reliably supported by the movable member, and the developer can be prevented from spilling during movement. This also prevents fogging. Furthermore, by pre-charging the transferred #JJVA material, the energy used when the developer is blown away can be controlled and fogging can be prevented. In addition, the present invention can be modified in several ways. For example, in addition to the layer-forming member described above, a special electric rubber blade, a metal grade, etc. can be used. By bringing the central portions of these elastic grades into contact with the moving member, the grades are brought into smooth pressure contact and developer band 1! A uniform layer can be formed without affecting the properties. [Effects of the Invention] As explained above, according to the present invention, clear images without fogging can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front view of one embodiment of the present invention, FIG. 2 is a front view of an implementation row of bases, and FIG. 3 is a front view of a bowl portion of still another embodiment. 1...Holding body, 2...Static N, image, 3...Moving member,
5... Power supply, 3d... Insulating layer, 18... Charger. Agent Patent Attorney Nori Yutaka Chika Norio Daiko Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] A device for visualizing an electrostatic latent image formed on an image carrier rotating in a predetermined direction using a non-magnetic component developer, comprising: an electrostatic latent image formed on an image carrier rotating in a predetermined direction; and a developer support that rotates in a direction different from the rotational direction of the image carrier and supports the developer on its surface, and a developer support that accommodates the developer and that the accommodated developer contacts the developer support. a supply means for supplying the developer to the developer support as the developer rotates; and a supply means for supplying the developer to the developer support by the supply means in the vicinity of the developer support. and a layer forming means for pressing the charged developer and charging the developer passing through this pressing portion, and rotating the developer support carrying the developer charged by the layer forming means. 1. A developing device, wherein a developer charged with a charge is made to face the image carrier.