JPH0748122B2 - Development device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a developing device, and in particular, it is used in an image forming device in which an electrophotographic system or an electrostatic recording system is adopted in an image forming process. The present invention relates to a developing device that visualizes an electrostatic latent image formed in an image forming device with a one-component developer.

As is well known in the prior art, a developing device of this type is disclosed in
An apparatus that employs a so-called jumping development method such as that disclosed in JP-A-54-42141 and a float electrode development method such as that disclosed in JP-A-58-97071 are adopted. Many proposals have been made for such devices, and they are actually commercialized. FIG. 9 shows an example of such a conventional developing device. The outline of the developing device shown in FIG. 9 is as described below. That is, the one-component developer 103 contained in the toner hopper 104 is supported by the developing sleeve 102 that is rotatably supported in the opening of the toner hopper 104 that is set close to the image carrier 101. And the one-component developer 103 is supplied to the image carrier 101 by the developing bias voltage applied to the developing sleeve 102. Thereby, the electrostatic latent image formed on the image carrier 101 is visualized.

To further explain the above-mentioned configuration, one end side (not shown) is attached to the toner hopper section 104 at the opening of the toner hopper section 104, and the other end side is brought close to the outer peripheral surface of the developing sleeve 102 to develop. Agent control member 1
05 is installed. The developer regulating member 105 regulates the layer thickness of the one-component developer 103 held on the outer peripheral surface of the developing sleeve 102 to a predetermined thickness, and removes the excess one-component developer 103 from the outer periphery of the developing sleeve 102. Toner hopper section 10
It is designed to be scraped into the inside. The developing sleeve 102
The DC voltage, the AC voltage, or the pulsating voltage in which the AC voltage component is superimposed on the DC voltage component is applied as the developing bias voltage described above between the image carrier 101 and the image carrier 101.

In the developing device having the above-described configuration, the one-component developer 103 formed on the outer peripheral surface of the developing sleeve 102 by the developer-regulating member 105 is formed into a uniform layer. This is an extremely important technique for ensuring the uniformity of the visualized solid image when the so-called solid image is visualized in the electrostatic latent image formed on the image bearing member 101 by using 103. Therefore, conventionally, the developer regulating member 105 is made of an insulating material, is made of a conductive material, or is made of an elastic body. Various proposals have been made with respect to the developer regulating member 105, such as the use of a magnetic material or a non-magnetic material.

Problems to be Solved by the Invention By the way, in order to improve the image density of the visible image of the electrostatic latent image formed on the above-mentioned image bearing member 101, or to perform more faithful development of the electrostatic latent image. , By moving the toner hopper 104 toward the image carrier 101, the developer layer 103 on the outer peripheral surface of the developing sleeve 102 relative to the image carrier 101 may be brought closer to the outer peripheral surface of the image carrier 101, Alternatively, a method of contacting is considered.
However, if the above-described method is adopted in the conventional developing device having the above-mentioned configuration, the developing sleeve 10
2 end region (that is, the layer thickness of the developer layer in the region corresponding to the non-image forming region of the image carrier 101, and the inner region of the developing sleeve 102 (that is, the image forming region of the image carrier 101 Since the layer thickness of the developer layer in the area corresponding to (1) is equal to the non-image forming area on the outer peripheral surface of the image carrier 101, the one-component developer 103 in the end area of the developing sleeve 102 adheres to the non-image forming area. As a result, the one-component developer 1 attached to the non-image forming area of the image bearing member 101.
03 remains in the main body of the image forming apparatus without being transferred from the image carrier 101 to a transfer material such as a transfer paper and directly adheres to the non-image forming area of the image carrier 101. There was a problem that it would contaminate the.

The above-mentioned problems are caused in the image forming apparatus including the developing device containing the two-component developer including the carrier and the toner and the developing device containing the conductive one-component developer even in the one-component developer, This is not so problematic, and even in the case of a one-component developer, it was particularly remarkable in an image forming apparatus equipped with a developing device that accommodates a so-called high-resistance one-component developer utilizing tribo. As described above, the reason why the above-mentioned problems are particularly remarkable in the image forming apparatus provided with the developing device containing the so-called high-resistance one-component developer utilizing tribo is supposed to be as follows. . That is, since the ratio of the surface area of the developing sleeve 102 to one particle of the one-component developer 103 is much smaller than the ratio of the surface area of the carrier to one particle of the toner in the two-component developer, the one-component developer 103 The contact probability between each of the particles and the outer peripheral surface of the developing sleeve 102 is much smaller than the contact probability between one toner particle and one carrier particle in the two-component developer. Therefore, in the one-component developer 103, it is not possible to contact the outer peripheral surface of the developing sleeve 102, and tribo cannot be obtained due to friction between the outer peripheral surface of the developing sleeve 102 and the reverse polarity. It is considered that there is a high probability that the state of having the electric charge of will be mixed. The probability that such a one-component developer 103 having a charge of the opposite polarity will be mixed increases as the layer thickness of the developer formed on the outer peripheral surface of the developing sleeve 102 increases. When the one-component developer 103 having a charge of the opposite polarity adheres to the image forming area of the image carrier 101,
By being transferred from the image carrier 101 to the transfer material, it is discharged out of the apparatus main body. Contrary to this, when the one-component developer 103 having the opposite polarity charge adheres to the non-image forming area of the image carrier 101, there is no opportunity to be discharged to the outside of the apparatus main body and the cleaner part The inside of the device body is contaminated in some form such as being accumulated or scattered. Therefore, as a measure for preventing the occurrence of such a problem, the diameter of the portion of the developing sleeve 102 corresponding to the non-image forming area in the image carrier 101 is
A method has been proposed in which the diameter of the portion of the developing sleeve 102 corresponding to the image forming area of the image carrier 101 is made smaller. However, in the above method, it is difficult to obtain accuracy when manufacturing developing sleeves having different diameters,
There is a drawback that the number of man-hours increases and the cost increases. In addition to the above method, the developing sleeve 102 described above is also used.
Although a method of sealing the developer layer on both ends of the sheet with a felt material or the like has been proposed, it has a drawback that the amount of the developer scattered into the apparatus increases when the developer layer is thick.

Therefore, the present invention was devised in order to solve the above-mentioned problems and drawbacks, and its purpose is to develop a non-image-forming image of an image carrier in a developing device which accommodates a one-component developer for development. By forming the one-component developer layer on the developing sleeve corresponding to the forming area to be thinner than the one-component developer layer on the developing sleeve corresponding to the image forming area on the image carrier, a thin layer is formed. It is possible to prevent the formed one-component developer layer from adhering to the non-image forming area on the image carrier, and as a result, prevent the one-component developer from scattering in the apparatus main body. It is to provide a developing device capable of performing the above.

Means for Solving the Problems The above object is achieved by the developing device according to the present invention. In summary, the present invention relates to a developer container for containing a one-component developer, a developer carrier provided at an opening of the developer container facing the image carrier, and a developer carrier on the developer carrier. In the developing device having an elastic regulating member for regulating the layer thickness of the developer, the elastic regulating member has a length corresponding to the image forming region,
A magnetic regulation member that regulates the layer thickness of the developer on the developer carrier by magnetic force is provided corresponding to the non-image forming area outside the elasticity regulation member, and the magnetic regulation is performed more than the layer thickness regulated by the elasticity regulation member. The developing device is characterized in that the layer thickness regulated by the member is thin.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

As described above, the developing device according to the present invention is preferably used for visualizing an electrostatic latent image formed by an image forming apparatus such as an electrophotographic copying machine or a laser beam printer. As is apparent from FIG. 1 showing the first embodiment according to the present invention, the developing device is arranged close to the image carrier, that is, the photosensitive drum 1 in the image forming apparatus. In FIG. 1, the developer container, that is, the toner hopper 4 is arranged so as to be close to the outer peripheral surface of the photosensitive drum 1 when the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1 is visualized. In this case, the reciprocating movement is provided in the apparatus main body (not shown) so as to be separated. The toner hopper 4 contains, for example, a one-component developer 3 having a high electric resistance value as a developer, and the toner hopper 4 has a portion facing the outer peripheral surface of the photosensitive drum 1. The opening 4a is formed. The developer carrier, that is, the developing sleeve 2 is exposed to the opening 4a. At the same time, in the opening 4a, the first developer layer thickness regulating means, that is, the elastic regulating member 6 whose one end side is close to the outer peripheral surface of the developing sleeve 2 and whose other end side is supported and fixed by the toner hopper 4. Also, a second developer layer thickness regulating means, that is, a magnetic rigidity regulating member 7 is provided. The above configuration will be described in more detail below. That is, the developing sleeve 2
Is rotatably supported in the toner hopper 4 in the counterclockwise direction in FIG. 1 formed of a non-magnetic metal material such as aluminum whose surface is oxidized, and has a substantially cylindrical shape inside thereof. A magnet 5 having a shape is fixedly interposed. To the developing sleeve 2, for example, a developing bias voltage in which an AC voltage component is superimposed on a DC voltage component is applied. The magnet 5 is a one-component system developer that has been conveyed toward the developing sleeve 2 by a developer circulating and conveying means provided in the toner hopper 4, such as a developer feeding screw and a developer returning screw (neither shown). The agent 3 is attracted to and held by the developing sleeve 2 by a magnetic force. N ₁ ,
It has four magnetic poles, S ₁ , N ₂ and S ₂ . The developing sleeve 2 draws up the one-component developer 3 that has moved in the toner hopper 4 toward the developing sleeve 2 by the developer feeding screw and the developer returning screw from the magnet 5 and pulls up the developer by the magnetic force of the pole S ₂ . Thus, the one-component developer 3 attracted and held by the rotation is carried out toward the outside of the toner hopper 4. The elastic restriction member 6 and the magnetic rigidity restriction member 7 described above are
As is apparent from FIG. 1 and FIG. 2, a straight line is formed on the outer peripheral surface of the developing sleeve 2 along the rotation axis of the developing sleeve 2 while partially contacting each other. Are arranged in contact with or close to the outer peripheral surface of the developing sleeve 2, respectively. The elastic restriction member 6 is
The magnetic rigidity restricting member 7 is formed so that the cross-sectional shape is substantially a letter shape so that the magnetic rigidity regulating member 7 is substantially a letter shape. The elastic regulating member 6 is a one-component system developing device that is carried in a first region on the developing sleeve 2 corresponding to the image forming region of the photosensitive drum 1, that is, a central region in the rotation axis direction of the developing sleeve 2. The agent layer is shown in FIG.
The thickness is regulated to a predetermined thickness as shown in. or,
The magnetic rigidity regulating member 7 is a developer carried in a second region on the developing sleeve 2 corresponding to the non-image forming region of the photosensitive drum 1, that is, a region at both end portions in the rotation axis direction of the developing sleeve 2. As shown by reference numeral 3B in FIG. 2, the layer is regulated to a thickness smaller than the layer thickness of the one-component developer layer 3A in the central region of the developing sleeve 2 in the rotation axis direction.

The process by which the present inventors came up with the developing device having the above-described structure, that is, the developing device according to the first embodiment of the present invention, is as follows. That is, as shown in FIGS. 1 and 2, the method of using the elastic regulating member 6 as the first developer layer thickness regulating means described above is disclosed in JP-A-54-43038 and JP-A-58-116559. As described in each of the publications and the like, even if the environmental conditions in which the image forming apparatus main body is placed vary, the developer layer thickness set on the outer peripheral surface of the developing sleeve 2 may be affected thereby. This is an extremely excellent method since the thickness of the developing layer is constantly regulated to a predetermined thickness. In this method, the elastic regulating member 6 is pressed against the outer peripheral surface of the rotating developing sleeve 2 so that the one-component developer 3 carried on the outer peripheral surface of the developing sleeve 2 and the outer peripheral surface of the developing sleeve 2. The frictional force generated between and becomes large, and the tribo value applied to the one-component developer 3 also becomes high. Therefore, the mirroring force between the one-component developer 3 and the developing sleeve 2 is increased, and a thick developer layer is obtained. As a result, a copy image having a high development density is obtained. However, as described above, when the layer thickness of the one-component developer layer 3B carried in the regions of the developing sleeve 2 at both ends in the rotation axis direction is large, the non-image forming region on the outer peripheral surface of the photoconductor drum 1 becomes uniform. Since the component type developer 3 is attached, there is a drawback that the non-image forming area of the transfer material is contaminated. Therefore, in this embodiment, the one-component developer layer 3B carried in the regions of the developing sleeve 2 at both ends in the rotational axis direction is regulated in magnetic rigidity as described in JP-B-59-8831. By using the member 7 or the like, the thickness of the developing sleeve 2 is regulated to be smaller than that of the one-component developer layer 3A in the central portion of the developing sleeve 2 in the rotational axis direction. The one-component type developer layer 3B carried in the partial region is less likely to adhere to the non-image forming region on the outer peripheral surface of the photosensitive drum 1, and the non-image forming region is not contaminated by the one-component type developer 3 and is good and high. It was possible to obtain a copied image having a high quality. The reason why such a preferable result is obtained is that the magnetic rigidity regulating member 7 is used for the second developer layer thickness regulating means to regulate the layer thickness of the developer by magnetic cutting. The frictional force generated between the system developer 3 and the outer peripheral surface of the developing sleeve 2 becomes small, so that the value of the tribo imparted to the one-component system developer 3 becomes low and the mirroring force does not become so large. It is considered that the developer layer thickness becomes relatively thinner than the developer layer thickness regulated by the elasticity regulation member 6.

As described above, according to the first embodiment of the present invention, the developer layer thickness regulated by the magnetic rigidity regulation member 7 is relatively thinner than the developer layer thickness regulated by the elasticity regulation member 6. Since it can be set so that it is possible to obtain a copied image having good and high quality. Further, since the magnet 5 and the magnetic rigidity regulating member 7 are installed so that the ends of the magnet 5 are located near the central portion of the magnetic rigidity regulating member 7, respectively.
For example, as shown in FIG. 3A and FIG. 3B, the end of the magnet 5 provided inside the developing sleeve 2 and the end of the magnetic rigidity regulating member 7 are As in the case where they are positioned close to each other, the lines of magnetic force are dense and the one-component developer 3 is integrated on the outer peripheral surface of the developing sleeve 2 to become a developer block 18 and the outer peripheral surface of the developing sleeve 2. It is also possible to prevent the occurrence of problems such as dropping from above and contaminating the inside of the developing device or the inside of the image forming device.

FIG. 4 shows a developing device according to the second embodiment of the present invention. As is apparent from FIG. 4, the developing device according to the second embodiment of the present invention includes an elastic regulation member 6 and a magnetic rigidity regulation member between the elastic regulation member 6 and the magnetic rigidity regulation member 7 described above. This is characterized in that a seal member 8 for partitioning the member 7 is provided. The seal member 8 is made of any one material such as Mylar, polyethylene, and maltoprene. According to the present embodiment, since the seal member 8 is provided between the elastic regulation member 6 and the magnetic rigidity regulation member 7, the respective contact surfaces and proximity surfaces of the elastic regulation member 6 and the magnetic rigidity regulation member 7 are arranged. Need not exist on the same straight line on the outer peripheral surface of the developing sleeve 2 along the rotational axis direction of the developing sleeve 2. Furthermore, since the elastic regulation member 6 can be fixedly attached to the magnetic rigidity regulation member 7, the configuration of the developing device as a whole can be simplified.

FIG. 5 shows a developing device according to the third embodiment of the present invention. In the developing device according to the third embodiment of the present invention, as apparent from FIG. 5, the elastic restricting member 6 described above is added to the first developer layer thickness regulating means and the second developer layer thickness regulating means. It was used. The portion 6A (hereinafter, referred to as "elasticity regulating member 6A") of the elasticity regulating member 6 corresponding to the central portion in the rotation axis direction on the outer peripheral surface of the developing sleeve 2 is pressed against the outer peripheral surface of the developing sleeve 2. , A portion 6B corresponding to both end portions in the rotation axis direction on the outer peripheral surface of the developing sleeve 2 of the elastic regulating member 6 (hereinafter, referred to as "elastic regulating member 6B").
It is set so as to be stronger than the pressure contact force with respect to the outer peripheral surface of the developing sleeve 2). That is, the stronger the pressure of the one-component developer 3 on the outer peripheral surface of the developing sleeve 2, the greater the frictional force generated between the one-component developer 3 and the outer peripheral surface of the developing sleeve 2, and the one-component developer. Since the tribo value given to No. 3 becomes high, the developer layer formed on the outer peripheral surface of the developing sleeve 2 becomes thicker. Therefore, at the central portion in the direction of the rotation axis on the outer peripheral surface of the developing sleeve 2, a thick one-component developer layer 3A is formed by the elastic regulating member 6A that presses the one-component developer 3 strongly.
Further, at the end portions on the outer peripheral surface of the developing sleeve 2 in the direction of the rotation axis, a thin one-component developer layer 3B is formed by the elastic regulating members 6B that are in weak contact with the one-component developer 3. Therefore, it is possible to obtain substantially the same effect as in the first and second embodiments described above. When the same elastic body is used for both the elastic regulating members 6A and 6B, the pressure contact force of the elastic regulating member 6A against the outer peripheral surface of the developing sleeve 2 is stronger than the pressure contact force of the elastic regulating member 6B against the outer peripheral surface of the developing sleeve 2. Just set it. Further, since it is possible to use elastic bodies having different elastic moduli for the elastic regulating member 6A and the elastic regulating member 6B, the design of the developing device becomes easy.

FIG. 6 and FIG. 7 show a developing device according to the fourth embodiment of the present invention. The developing device according to the fourth embodiment of the present invention, as will be apparent from FIG.
~ Elasticity regulating member 6 (6A, 6B) shown in the third embodiment,
Rigidity restricting members 9 and 10 are provided in place of the magnetic rigidity restricting member 7, and a charger 11 is provided in the space defined by the rigidity restricting member 9 and the rigidity restricting member 10 in close proximity to the outer peripheral surface of the developing sleeve 2. It was decided. The rigidity regulating members 9 and 10 may be made of a magnetic rigid material or a non-magnetic rigid material, but at least the rigidity regulating member 10 is made of a magnetic rigid material. It is possible to obtain a remarkable effect by using the above-mentioned member. The charger 11 is configured to apply a charge of a predetermined polarity to the one-component developer layer 3A carried on the outer peripheral surface of the developing sleeve 2 at the central portion in the rotation axis direction. In the configuration as described above, when the developing sleeve 2 starts to rotate, first, the developer carried on the outer peripheral surface of the developing sleeve 2 by the rigidity regulating member 9 arranged on the upstream side in the rotating direction of the developing sleeve 2. The layer is uniformly regulated to a predetermined layer thickness. Of the one-component developer layer regulated by the rigidity regulating member 9 to have a uniform layer thickness, the one-component developer layer 3A carried on the outer peripheral surface of the developing sleeve 2 in the central region in the direction of the rotation axis is When the developing sleeve 2 reaches a portion facing the charger 11 by the rotation of the developing sleeve 2, the charger 11 having a charging region equal to the above-mentioned region imparts a charge of a predetermined polarity. Thereby, the one-component developer layer existing in the area
Tribo value of 3A is increased. On the other hand, the one-component developer layer 3B carried in the regions of the outer peripheral surface of the developing sleeve 2 at both ends in the direction of the rotation axis is not charged with the charge but is charged with the rotation of the developing sleeve 2. Together with the one-component developer layer 3A, it moves toward the magnetic rigidity regulating member 10 disposed on the downstream side in the rotation direction of the developing sleeve 2. Of the one-component developer layers 3A and 3B that have moved to the magnetic rigidity regulating member 10 side, the one-component developer layer 3B is a one-component developer layer 3B magnetically cut by the magnetic rigidity regulating member 10. , The layer thickness becomes thin. On the contrary, the one-component developer layer 3A acts between the one-component developer 3 and the outer peripheral surface of the developing sleeve 2 because the tribo value is increased by the charger 11. The reflection power is great,
The thick one-component developer layer 3A is held as it is. Therefore, for the one-component developer layer 3A, it is possible to keep the layer thickness as it is, and for the one-component developer layer 3B, the layer thickness can be made thinner, which is more reliable. It became possible to regulate the layer thickness of various developers.

In each of the first to fourth embodiments described above, the difference in the magnitude of the tribo values applied to the one-component developer layer 3 is used to make the center of the outer peripheral surface of the developing sleeve 2 in the rotation axis direction. The layer thickness of the one-component developer layer 3A carried on the parts is thicker than the layer thickness of the one-component developer layer 3B carried on the both ends of the outer peripheral surface of the developing sleeve 2 in the rotation axis direction. It is the one to be set.

FIG. 8 shows a developing device according to the fifth embodiment of the present invention. The developing device according to the fifth embodiment of the present invention, as apparent from FIG.
In place of the elastic regulation member 6 (6A, 6B) and the magnetic rigidity regulation member 7 shown in the above embodiment, the shape corresponding to the central portion in the rotation axis direction on the outer peripheral surface of the developing sleeve 2 is recessed. The magnetic rigidity regulating member 12 is provided. In this embodiment, the one-component developer 3 carried on the outer peripheral surface of the developing sleeve 2 is the magnetic rigidity regulating member 12
The developer layer thickness is regulated to a predetermined thickness by the magnetic rigidity regulating member 12, but the magnetic rigidity regulating member 12 has a recessed portion corresponding to the central portion of the outer peripheral surface of the developing sleeve 2 in the rotation axis direction. Therefore, the one-component type developer layer 3A carried on the site
The layer thickness can be set to be thicker than the layer thickness of the one-component developer layer 3B carried on the outer peripheral surface of the developing sleeve 2 at both end portions in the rotation axis direction. Therefore, it is possible to provide a developing device that achieves the effects described above with a very low cost and a simple structure.

EFFECTS OF THE INVENTION As described above, according to the present invention, one component on the developer carrying member corresponding to the non-image forming area of the image carrying member in the developing device containing the one-component developer for development. The one-component developer layer formed in a thin layer by forming the system developer layer in a thinner layer than the one-component developer layer on the developer carrier corresponding to the image forming area on the image carrier. To provide a developing device capable of preventing the toner from adhering to the non-image forming area on the image carrier, and consequently preventing the one-component developer from scattering in the main body of the device. be able to.

[Brief description of drawings]

FIG. 1 is a partial longitudinal sectional view showing a developing device according to the first embodiment of the present invention. FIG. 2 is a partial front view showing the developing device according to the first embodiment of the present invention. FIGS. 3A and 3B are explanatory views showing the phenomenon of dropping of the one-component developer block from the developing sleeve. FIG. 4 is a partial vertical sectional view showing a developing device according to the second embodiment of the present invention. FIG. 5 is a partial front view showing the developing device according to the third embodiment of the present invention. FIG. 6 is a partial vertical sectional view showing a developing device according to the fourth embodiment of the present invention. FIG. 7 is a partial front view showing the developing device according to the fourth embodiment of the present invention. FIG. 8 is a partial vertical sectional view showing a developing device according to the fifth embodiment of the present invention. FIG. 9 is a partial vertical sectional view showing a developing device according to the prior art. 1: Photosensitive drum 2: Development sleeve 3: One-component developer 4: Toner hopper 4a: Openings 6, 6A, 6B: Elastic regulation members 7, 10, 12: Magnetic rigidity regulation member 8: Sealing member 9: Rigidity regulation Member 11: Charger

Claims (1)

[Claims] 1. A developer container for containing a one-component developer,
In a developing device having a developer carrier provided in an opening of a developer container facing the image carrier, and an elastic regulating member for regulating a layer thickness of the developer on the developer carrier, The elastic regulation member has a length corresponding to the image forming area,
A magnetic regulation member that regulates the layer thickness of the developer on the developer carrier by magnetic force is provided corresponding to the non-image forming area outside the elasticity regulation member, and the magnetic regulation is performed more than the layer thickness regulated by the elasticity regulation member. A developing device having a thin layer thickness regulated by a member.