JP2701224B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an improvement in an image forming apparatus provided with a developing device using a one-component developer. (Prior Art) Generally, in an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile, various apparatuses using a one-component developer as a developer have been developed in order to reduce the size of a developing section. ing. In a developing device using this one-component developer, a toner carrier of a developing device is arranged so as to be in contact with or close to a latent image carrier on which an electrostatic latent image is formed. Then, the toner supplied from the toner storage unit while being stirred is attached to the toner carrier, and the toner is conveyed to the electrostatic latent image side on the latent image carrier, and a predetermined developing operation is performed. I try to get a visual image. On the toner carrier, a toner regulating member for regulating the toner transport amount by uniformly thinning the toner supplied on the toner carrier is provided. Some of the toner carriers are formed of an elastic material so as to protect the latent image carrier from being damaged and to perform a good developing operation. However, in such a so-called soft development, as described above, if the toner regulating member is pressed against the softened toner carrier side, a depression-like surface is formed on the surface of the toner carrier by the pressing force of the toner regulating member. Deformation or distortion often occurs. At the concave portion of the concave deformed portion or the distorted portion, the pressing force of the toner regulating member is reduced, and a sufficient toner charge amount cannot be obtained, so that a so-called fogging phenomenon is likely to occur. On the other hand, in the convex portion, a sufficient amount of adhered toner cannot be obtained, which may lead to defective development, generation of a streak pattern, and the like. Such dent-like deformation or distortion often remains permanently as it is, and even if it returns to its original state, it often takes a long time until it is completely recovered. (Purpose) An object of the present invention is to provide an image forming apparatus in which soft development is performed using a one-component type developer, in which the deformation or distortion of a toner carrier due to a toner regulating member can be minimized. An object of the present invention is to provide a forming apparatus. (Structure) In order to achieve the above object, the toner carrier according to the present invention has an elastic layer made of a foamable elastic material having a thickness sufficient to soften the toner carrier, and has a larger size than the elastic layer. An endless cylindrical deformation relaxation amount comprising a thin layer of synthetic resin or a thin layer of electrodeposit, which has rigidity and surrounds the elastic layer, wherein the elastic layer and the deformation relaxation layer are not adhered to each other. It is characterized by being. In the image forming apparatus having such a configuration, the pressing force of the toner regulating member is received by the deformation alleviating layer, and almost no local load is applied to the elastic layer for softening the toner carrier. In the deformation alleviating layer, the deformation force by the toner regulating member is relaxed, so that the unevenness of the toner carrier is moderated, and the deformed portion is quickly restored to the original state. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 3, a photosensitive drum 1 serving as a latent image carrier is driven to rotate in the direction of arrow A, and a corona charger 2 for uniformly charging the entire surface of the photosensitive drum 1 is provided around the photosensitive drum 1. An exposure optical system 3 for forming an electrostatic latent image by forming the light image on the photosensitive drum 1; a developing device 4 for supplying and developing toner to the electrostatic latent image to obtain a visible image; A transfer pole 5 for transferring the obtained visible image to the recording material side, a separation pole 6 for separating the recording material from the photosensitive drum 1, a removing electrode 7 for removing toner remaining on the photosensitive drum 1 after the transfer, and a cleaning device. 8 etc. are arranged. A developing roller 12 as a toner carrier is provided in the casing 11 of the developing device 4 so as to be driven to rotate in the direction of arrow B, and a supply roller 13 for supplying toner to the developing roller 12 has an arrow. It is provided so as to be driven to rotate in the C direction. Further, on the rear side (the right side in FIG. 3) of the supply roller 13, there is provided an agitator 14 for conveying the toner toward the supply roller 13 while stirring the toner stored in the casing 11. Further, the developing roller 12 is provided with a blade 15 as a toner regulating member which presses the toner adhered to the developing roller 12 to a uniform and thin layer in a pressed state. As shown in FIG. 1, the developing roller 12 has an elastic layer 122 formed in a cylindrical shape fitted on the rotary drive shaft 121, and a deformation relaxation layer outside the elastic layer 122. A cylinder 123 is mounted, and a cylindrical electrode layer 124 and a toner carrying layer 12 are provided outside the cylinder 123.
5 are installed. The elastic layer 122 is made of a foamable elastic material having flexibility and a sufficient thickness as compared with the cylinder 123, such as urethane foam or sponge rubber. As a result, the entire developing roller 12 is made flexible. On the other hand, the cylinder 123 is formed of a thin layered elastic material having higher rigidity than the elastic layer 122. Examples thereof include synthetic resin materials such as polyester and vinyl chloride, and electrodeposits such as electroformed nickel. The layer thickness of the cylinder 123 is 20 to 200 μm, preferably 50 to 100 μm in the case of a synthetic resin material, and 10 to 100 μm, preferably 20 to 50 μm in the case of an electrodeposit. Further, the outer diameter of the elastic layer 122 is
It is formed slightly larger than the inner diameter of. And
When both are assembled, the elastic layer 122 is press-fitted into the cylinder 123 as shown in FIG. As a result, the elastic layer 122 and the cylinder 123 are mounted in a pressure-contact state, and are fixed without being shifted from each other due to mutual pressure-contact frictional force. In this case, both
They are not glued and are each deformed independently of each other. When the cylinder 123 is made of urethane foam, the outer diameter of the elastic layer 122 is formed to be larger by 0.2 to 40% of the inner diameter of the cylinder 123. When the cylinder 123 is made of sponge rubber,
It is formed to be larger by an amount corresponding to 0.1 to 15% of the inner diameter of the cylinder 123, and preferably by 0.2 to 10%. In such an embodiment, a blade 15 as a toner regulating member is pressed against a developing roller 12 as a toner carrier, whereby a uniform thin layer of toner conveyed while adhering to the developing roller 12 is formed. Tribocharging is performed. In this case, since the pressing force by the blade 15 is directly received by the cylinder 123 as a deformation relaxation layer, the elastic layer 122 that softens the developing roller 12 is used.
, No local load is applied by the leading edge of the blade 15. Therefore, the outer shape of the elastic layer 122 hardly deforms. On the other hand, since the cylinder 123 is formed of a thin layer of elastic material having greater rigidity than the elastic layer 122,
Even if the pressing force of 15 is directly received, the deformation force is reduced, and only a gentle depression-like deformation occurs. In addition, the deformed portion is quickly restored to the original state at the same time when the pressing force by the blade 15 is released. That is, the developing roller 12 is made flexible by the elastic layer 122 so that the photosensitive drum 1 is not damaged, and at the same time, the developing roller 12 is pressed by the blade 15 so as to maintain an appropriate pressure contact state. 123 provides gentle deformation and quick recovery. Therefore, in the pressure contact portion of the blade 15, non-uniformity of toner conveyance and poor charging caused by extreme deformation are prevented, and excellent toner conveyance is performed. In the present embodiment, the blade 15 is not an elastic blade as in the related art, but a hard blade. As a result, the vibration of the blade itself can be suppressed as much as possible, and a more favorable toner conveying operation can be realized. Examples of hard materials include fluorinated resin,
Silicone resin, rubber, polyethylene and the like can be considered. Further, as shown in FIG. 4 and FIG.
The angle α between the tangent line of the developing roller 12 and the tangent line 15 is set to be an acute angle, that is, less than 90 °, and preferably less than 75 °. FIG. 4 shows an embodiment in which the blades 15 are installed in the counter direction, and FIG. 5 shows an embodiment in which the blades 15 are installed in the trail direction.
This makes it possible to perform an efficient operation while minimizing the load on the blade 15. Further, as shown in FIGS. 6 and 7, if the tip pressure contact portion of the blade 15 is formed into a curved surface having a predetermined radius of curvature, a very appropriate pressure contact state can be obtained. In this embodiment, the radius of curvature is 5 to 500 μm. FIG. 6 shows the blade 15 as a single unit, and FIG. 7 shows the blade 15 with respect to the back plate 15a.
The figure shows a structure in which is fixed. Back plate
As 15a, metals such as stainless steel, aluminum and brass are desirable, but polycarbonate, acrylic resin,
Various plastic materials such as vinyl resin can be adopted. (Effects) As described above, in the toner carrier of the image forming apparatus according to the present invention, the elastic layer made of the foamable elastic material having a thickness sufficient to soften the toner carrier is directly controlled by the toner regulating member. In order not to be deformed, a deformation relaxation layer with great rigidity is installed on it,
Since the elastic layer and the deformation relaxing layer are not bonded to each other, the elastic body layer and the deformation relaxing layer are independently deformed,
In the press-contact portion of the toner regulating member, non-uniformity of toner conveyance and poor charging caused by local deformation are prevented, development defects such as streak patterns are eliminated, and a stable and defect-free image can always be obtained. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional configuration explanatory view showing a structure of a toner regulating member according to an embodiment of the present invention, and FIG. 2 shows an assembling operation of the toner carrier shown in FIG. FIG. 3 is a longitudinal sectional view showing the entire image forming apparatus, and FIGS. 4, 5, 6, and 7 show the state of contact of the toner regulating member with the toner carrier. It is the partial enlarged side view explanatory drawing which represented. 1 photosensitive drum, 4 developing device, 12 developing roller, 15 blade, 122 elastic layer, 123 cylinder.

Claims (1)

(57) [Claims] A toner carrier for supplying and developing toner on the electrostatic latent image side formed on the latent image carrier, and a toner carrier on the toner carrier such that the toner adhered on the toner carrier is uniformly thinned An image forming apparatus comprising: a toner regulating member that is pressed into contact with the toner carrier; wherein the toner carrier has an elastic layer made of a foamable elastic material having a thickness sufficient to soften the toner carrier; An endless cylindrical deformation-relaxation layer having a greater rigidity than the body layer and surrounding the elastic layer, comprising a thin layer of a synthetic resin or a thin layer of an electrodeposit, and the elastic layer and the deformation-relief layer And an image forming apparatus, wherein the image forming apparatus and the image forming apparatus do not adhere to each other.