KR101329737B1 - Developing device and image-forming apparatus adopting the same - Google Patents

Abstract

A developing roller and an image forming apparatus employing the same are disclosed. The disclosed developing apparatus includes a developing roller for attaching and transporting a developer to an outer circumferential surface thereof, a film member provided to approach or contact the developing roller in a developer supply area at a lower side of the developing roller, and inserted into the film member to insert the film member. A toner transfer member having a support shaft rotatably supported thereon is provided.

Description

Developing device and image-forming apparatus adopting the same

1 is a view showing a schematic configuration of a developing apparatus according to a conventional example,

2 is a view showing a schematic configuration of a developing apparatus according to another conventional example;

3 is a view schematically showing the configuration of a developing apparatus according to another conventional example,

4 shows a schematic configuration of an image forming apparatus employing a developing apparatus according to the present invention;

5 is a diagram showing a schematic configuration of a developing apparatus according to a first embodiment of the present invention;

6 is a view for explaining the operation of the toner transport member shown in FIG.

7 is a diagram showing a schematic configuration of a developing apparatus according to a second embodiment of the present invention;

8 is a view for explaining the operation of the toner conveying member shown in FIG.

9 is a view schematically showing the configuration of a developing apparatus according to a third embodiment of the present invention;

10 is a view showing a state in which the electrostatic adsorption force does not operate between the film member and the developing roller shown in FIG. 9;

11 is a view showing a state where the toner passes while the static adsorption force is operated between the film member and the developing roller shown in FIG. 9;

12 is a view showing a first modified example of the layer regulating charging member shown in FIG. 9;

13 is a view showing a second modified example of the layer regulating charging member shown in FIG. 9;

<Description of the symbols for the main parts of the drawings>

140,240,340,340 ', 340' '... developing device

141,241,341 ... photosensitive drum 142,242,342 ... developing roller

143,344 ... layer regulated charging member 144,244,343 ... RS roller

145,245 Stirring element 147 Toner transfer member

148,345 Film member 149 Support shaft

346 Supporting member 348 Smile clearance

The present invention relates to a developing apparatus and an image forming apparatus employing the same, and more particularly, to a developing apparatus having a toner supply member and an image forming apparatus employing the same.

1 is a view showing a schematic configuration of a developing apparatus according to a conventional example.

Referring to FIG. 1, the developing apparatus 1 includes a developing roller 10 for attaching and transferring toner, a doctor blade 20 for regulating a layer of toner attached to the developing roller 10, and a developing roller 10. An RS roller 30 for removing residual toner remaining on the outer circumferential surface or supplying toner to the developing roller 10 and a stirring member 40 for stirring the toner are provided.

Looking at the toner transfer path of the developing device (1) configured as described above, the toner supplied from the toner container (not shown) is stirred by the stirring member 40 provided above the toner support 50, the base 60 Is supplied to the toner supply region C provided between the doctor blade 20 and the developing roller 10 fixed thereto. The toner supplied to the toner supply region C is formed into a charge and a thin layer while passing through the doctor blade 20 and attached to the developing roller 10. The toner attached to the developing roller 10 develops an electrostatic latent image formed on the photosensitive drum 5 at a position facing the photosensitive drum 5. The remaining toner remaining on the developing roller 10 is mechanically peeled off by the RS roller 30 made of foam 31 such as a sponge. Such a configuration is disclosed in Japanese Patent Laid-Open No. 11-167254.

The developing apparatus according to the conventional example as described above has a low toner supply ability to the developing roller 10.

2 is a view showing a schematic configuration of a developing apparatus according to another conventional example.

Referring to FIG. 2, the developing apparatus 1 ′ includes a developing roller 10 for attaching and transferring toner, a doctor blade 20 for regulating a layer of toner attached to the developing roller 10, and a developing roller 10. RS to remove the residual toner remaining on the outer peripheral surface of or to supply the toner to the developing roller (10).

The developing roller 10 and the RS roller 30 are rotated counterclockwise to form a toner pool D above the contact portion between the developing roller 10 and the RS roller 30. Since one end of the doctor blade 20 is located in the toner pool D, a sufficient amount of toner can be supplied to a gap formed between the developing roller 10 and the doctor blade 20.

  Therefore, the developing apparatus 1 shown in FIG. 1 supplies toner to a gap between the doctor blade 20 and the developing roller 10 by the pressure of the stirring member 40, but the developing apparatus shown in FIG. 1 ') has high toner supply capability because the developing roller 10 and the RS roller 30 contact each other and directly supply the toner to the gap between the doctor blade 20 and the developing roller 10.

For the above problem, for example, in order to actively supply toner remaining in the toner supply region C of FIG. 1 between the developing roller 10 and the doctor blade 20, the same roller as the RS roller 30 is used. It is conceivable to provide the toner supply region C. FIG.

However, in order to supply and peel the toner by the foam layer 31, the RS roller 30 needs the thickness of the foam layer 31 to be at least about 3 mm, and considering the central axis diameter, the diameter is about 10 mm. It should be a roller. For this reason, it is unpreferable in terms of installation constraints and cost of a roller.

In addition, when the roller is not provided in the toner supply area C as described above, the toner remains in the toner supply area C, and the toner supply amount between the developing roller 10 and the doctor blade 20 is reduced. Easy to change For this reason, the thickness of the toner layer on the developing roller 10 varies, and deterioration of image quality occurs. Therefore, it is preferable to provide a roller in the toner supply region C. As described above, the arrangement of the roller having the toner supply capability is difficult, and if necessary, an axis having only a stirring function is provided.

On the other hand, the doctor blade 20 of the developing device 1 ′ shown in FIG. 2 is firm along the rectangular direction and exerts a high linear pressure on the developing roller 10. For this reason, according to the nonuniformity of the nip by the planarity of the doctor blade 20, the cylindrical nonuniformity of the developing roller 10, or the variation of the nip state caused by the rotation of the developing roller 10, There is a problem that the toner layer becomes nonuniform or the nip state changes, resulting in deterioration of the image quality.

In order to solve this problem, as shown in Fig. 3, the flexible doctor blade 40 disclosed in Japanese Patent Laid-Open No. Hei 10-39623 has been proposed.

3 is a view schematically showing the configuration of a developing apparatus according to another conventional example.

Referring to FIG. 3, the flexible doctor blade 40 has a substantially L-shaped blade 41 supported by a thin gap adjusting plate 42, and a blade support member 44 with an elastic foam 43 interposed therebetween. It is fixed at. By providing the elastic foam 43 between the blade 41 and the blade supporting member 44, the followability to variations in the rotational direction of the developing roller 10 is improved, and the developing roller 10 is provided by the gap adjusting plate 42. The blade planarity in the trust direction is improved.

However, in the flexible doctor blade 40 shown in Fig. 3, both the doctor blade tracking in the direction perpendicular to the main surface of the developing roller 10 and the holding force of the toner in the developing roller rotation direction of the blade 41 are maintained. It's hard to do. For this reason, the wedge-shaped gap used as the inlet of toner fluctuates by the circumferential displacement of the blade 41 upstream of the developing roller rotation direction. As the gap fluctuates, there is a problem that the yield of toner fluctuates, or it is difficult to optimize the pressure by the elastic foam 43.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and includes a developing apparatus having a toner conveying member having a compact toner supply capability, and a layer regulating charging member capable of charging a toner and forming a uniform toner layer at the same time, and an image employing the same. It is an object to provide a forming apparatus.

In order to achieve the above object, the developer of the present invention includes a developing roller for attaching and transferring a developer to an outer circumferential surface thereof;

A film member provided near or in contact with the developing roller in a developer supply region at the lower side of the developing roller, and inserted into the film member, the predetermined distance between the inner surface of the film member along its circumferential direction; A gap is formed, the toner conveying member having a support shaft rotatably supporting the film member.

According to the invention, the support shaft is fixed so as not to rotate,

A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member to the developing roller is formed between the developing roller and the support shaft.

The film member is rotated in accordance with the rotation of the developing roller.

According to the invention, the support shaft is fixed so as not to rotate,

A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member on the support shaft is formed between the developing roller and the support shaft.

The film member causes sliding against the rotation of the developing roller.

According to the invention, the support shaft is installed to be rotatable,

A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member on the support shaft is formed between the developing roller and the support shaft.

The support shaft and the film member are rotated integrally.

According to another feature of the invention, the developing roller for transporting the developer attached to the outer peripheral surface;

A film member having flexibility, which charges the developer while simultaneously regulating a layer of a developer attached to the developing roller, and supporting the film member so that at least a part of the film member is externally circumscribed to an outer circumferential surface of the developing roller. It is provided with a layer regulating charging member having a support member,

The fixed end of the film member fixed to the support member is provided so that a small gap, which is an introduction port of the developer formed between the developing roller and the film member, becomes constant.

The free end of the film member is electrostatically adsorbed to the developing roller by applying a voltage to the film member, and the micro gap is 2 mm or less.

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According to the invention, the film member further comprises a medium resistance layer made of at least a medium resistance material, wherein the resistance value of the medium resistance layer is 104 to 109 Ω · cm.

According to the invention, it is provided to contact with one surface of the film member, further comprising a voltage supply member for applying a voltage to the film member.

According to the present invention, different voltages are applied to the film member and the developing roller.

According to the invention, the film member further comprises a surface resistive layer,

The upstream side in the rotational direction of the developing roller of the surface resistance layer is made of a low resistance material, and the downstream side of the rotational direction of the developer carrying member of the surface resistance layer is made of a high resistance material.

An image forming apparatus according to the present invention comprises: an image forming apparatus comprising at least one developing apparatus and a fixing apparatus for fusing an image onto a print medium,

The developing device

A developing roller for transferring the developer to the outer circumferential surface thereof;

A film member provided near or in contact with the developing roller in a developer supply region at the lower side of the developing roller, and inserted into the film member, the predetermined distance between the inner surface of the film member along its circumferential direction; A gap is formed, the toner conveying member having a support shaft rotatably supporting the film member.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a diagram showing a schematic configuration of an image forming apparatus employing a developing apparatus according to the present invention.

Referring to Figure 4, the lower side of the main body 101 is attached to the printing paper (S), the paper cassette 110 is installed detachably, the upper side of the paper cassette 110, the printing paper (S) Pick-up roller 120 for picking up one by one is installed.

The image forming apparatus 100 includes a developing device 140, an exposure device 142, a transfer roller 150, a fixing device 160, and a discharge device 170 provided along a transport path of the printing paper S. do.

The developing device 140 supplies a toner as a developer to the electrostatic latent image to develop the electrostatic latent image into a toner image, which is detachably installed on the main body 101, and has a photosensitive drum 141 partially exposed to the outside. Doing.

The exposure apparatus 142 forms an electrostatic latent image on the surface of the photosensitive drum 141 in response to printing data. In general, the exposure apparatus 142 emits light irradiated from a light source onto the surface of the photosensitive drum 141. Scanning unit (LSU) is used.

The transfer roller 150 is installed to face the photosensitive drum 141 to transfer the toner image formed on the photosensitive drum 141 to the printing paper S. FIG.

The fixing device 160 fuses the toner image onto the printing paper S by applying heat and pressure to the printing paper S on which the toner image is transferred. In general, it comprises a heating roller for generating heat and a pressure roller for applying pressure to the printing paper (S).

The discharge device 170 discharges the printing paper S on which the toner image is fused by the fixing device 160 to the outside of the main body 101.

FIG. 5 is a diagram showing a schematic configuration of a developing apparatus according to the first embodiment of the present invention, and FIG. 6 is a view for explaining the operation of the toner conveying member shown in FIG.

5 and 6, the developing apparatus 140 according to the first embodiment of the present invention regulates the layer of the developing roller 142 and the toner on the developing roller 142 to attach and transfer the toner as a developer. A layer regulating charging member 143 for charging the toner, an RS roller 144 for collecting residual toner on the developing roller 142, a stirring member 145 for stirring the toner, and a toner transport member provided in the toner supply area. 147 is provided.

The developing roller 142 is a circumferential developer carrying member for attaching and transporting toner, which is a developer, on its outer circumferential surface, and is disposed to extend in the inward direction of the paper of FIG. The developing roller 110 transfers the toner by rotating and supplies the toner for developing the electrostatic latent image to the photosensitive drum 141. The developing roller 142 is provided in close proximity to the photosensitive drum 141, and a voltage V1 is applied to form an electric field between the photosensitive drum 141. For example, the voltage V1 is applied to the developing roller 142 such that the voltage between the developing roller 142 and the photosensitive drum 141 is about 400V.

The layer regulating charging member 143 is a member for performing layer regulation and charging of the toner, and is formed of, for example, a plate member made of a conductive material. The layer regulating charging member 143 is provided so that one surface thereof faces the outer circumferential surface of the developing roller 142. On the upstream side of the developing roller 142 in the rotational direction, a toner supply region C for introducing toner is formed between the developing roller 142 and the layer regulating charging member 143. Further, a downstream side of the developing roller 142 in the rotational direction is provided so as to be charged while performing layer regulation of the toner. In addition, one end of the layer regulating charging member 143 is supported and fixed to the base 101a.

The RS roller 144 functions as a recovery member for recovering toner remaining in the developing roller 141 without being attached to the photosensitive drum 141. The outer circumferential portion of the RS roller 144 is made of a sponge layer 131, and is arranged to be in pressure contact with the developing roller 142. For example, a voltage is applied to the RS roller 144 such that it is substantially equipotential to the developing roller 142. In addition, although the RS roller 144 was used as a collection | recovery member in this embodiment, this invention is not limited to this example.

The stirring member 145 is a member for stirring the toner supplied to the developing roller 142. The toner supplied to the stirring member 145 and the remaining toner on the developing roller 142 recovered by the RS roller 144 and the newly supplied toner are agitated by the stirring member 145 rotating clockwise. As shown in FIG. 4, the stirring member 145 is provided with four wing members 145b provided at substantially equal intervals on the rotation shaft 145a, for example. The toner is supplied to the toner supply region C by rotating the wing member 145b by rotating the rotating shaft 145a of the stirring member 145.

The toner conveying member 147 includes a film member 148 for conveying toner and a support shaft 149 inserted into the film member 148. The film member 148 preferably includes a medium resistance layer formed of a material having a resistance value (volume resistance value or surface resistance value) of about 104 to 109 Ω.cm. The medium resistance layer is formed of, for example, a polymer film mainly made of polyimide, polycarbonate, polyamide, or the like. The film member 148 has a thickness of about 50 to 500 μm.

The support shaft 149 is a shaft for rotatably supporting the film member 148, and the support shaft 1493 itself is fixed to be rotatable. The support shaft 149 is made of metal such as aluminum, for example, and the diameter thereof is formed to be about 4 to 5 mm. In addition, a voltage V2 is applied to the support shaft 149 to supply voltage to the film member 148 by contact. In a state where there is no potential difference between the developing roller 142 and the support shaft 149 (initial state), a very small gap is provided between the outer circumferential surface of the support shaft 149 and the inner circumferential surface of the film member 148. Thus, the film member 148 may rotate around the support shaft 149. In this case, the outer peripheral surface of the support shaft 149 and the inner peripheral surface of the film member 148 are formed of a material having good sliding to facilitate rotation of the film member 148. In addition, in the initial state, the film member 148 is provided to approach or contact the outer peripheral surface of the developing roller 142.

The developing device 140 according to the present embodiment includes a voltage controller (not shown) for controlling a voltage applied to each member constituting the developing device 140. The voltage controller controls a voltage applied to the developing roller 142 and the support shaft 149. By controlling the voltage of each member, the strength of the electric field formed between the developing roller 142 and the support shaft 149 can be controlled.

The developing apparatus 140 according to the first embodiment as described above is characterized by including the toner transfer member 147 for transferring the toner supplied from the stirring member 145.

Hereinafter, the circulation of the toner in the developing apparatus 140 according to the first embodiment, in particular, the action of the toner conveying member 147 will be described with reference to FIGS. 5 and 6.

The toner stirred by the stirring member 145 is supplied to the toner supply region (C). The toner supply region C is an area formed by the developing roller 142 and the layer regulating charging member 143, and the toner conveying member 147 is provided. The toner supplied by the stirring member 145 is transferred by the toner conveying member 147 to the downstream side of the developing roller rotation direction of the layer regulating charging member 143.

In detail, when the toner is transferred by the toner transfer member 147, a predetermined voltage V2 is applied to the support shaft 149. On the other hand, since the voltage V1 is applied to the developing roller 142 to form an electric field between the photosensitive drums 141, an electric field is formed between the support shaft 149 and the developing roller 142. . The electric field is formed in the direction in which the film member 148 is charged and adsorbed on the outer circumferential surface of the developing roller 142. Therefore, the film member 148 is adsorbed to the developing roller 142 by the electrostatic attraction force (N1), and in contact with the developing roller 142 to form a nip of a predetermined width, for example about 1 to 2 mm. do. Here, a very small gap is provided between the film member 148 and the support shaft 149. For this reason, the film member 148 rotates around the support shaft 149 fixed in a non-rotable manner with the rotation of the developing roller 142.

As described above, the toner transfer member 147 is coated with a good sliding material such as fluorine such that the outer circumferential surface of the support shaft 149 and the inner circumferential surface of the film member 148 have a very small coefficient of friction. have. Sliding occurs between the film member 148 and the support shaft 149 from the relationship between the small coefficient of friction and the electrostatic attraction force N1. Therefore, the film member 148 can stably rotate around the fixed support shaft 149 without applying a large external force to the support shaft 149. In addition, since the film member 148 rotates with the rotation of the developing roller 142, a separate driving mechanism for rotating the film member 148 is also unnecessary. Thus, a roller having a small diameter and having a toner conveying capacity is formed.

In addition, an electrostatic attraction force is generated between the film member 148 and the support shaft 149. Accordingly, the film member 148 is somewhat electrostatically adsorbed to the support shaft 149, but its rolling angle is small, and the coefficient of friction of the outer circumferential surface of the support shaft 149 and the inner circumferential surface of the film member 148 is reduced. Since is very small, a large force does not act on the film member 148. Therefore, the film member 148 may rotate around the support shaft 149.

The toner transferred by the toner conveying member 147 to the downstream of the developing roller rotation direction of the layer regulating charging member 143 is layer regulated by passing between the developing roller 142 and the layer regulating charging member 143. It is charged. Uniformly layered and charged toner is attached to the developing roller 142 to be transferred to the opposing portion with the photosensitive drum 141, from the developing roller 142 to the photosensitive drum 141 according to the electrostatic latent image Attach.

On the other hand, the residual toner of the developing roller 142 is recovered by the RS roller 144. The residual toner recovered by the RS roller 144 is supplied to the stirring member 145 and stirred together with fresh toner supplied from a toner container (not shown). Then, the stirred toner is supplied to the toner supply area (C).

As described above, according to the developing apparatus 140 according to the first embodiment, the toner supply region C where toner easily tends to stay in the toner conveying member 147 for conveying the toner supplied from the stirring part material 145. To). The toner conveying member 147 is composed of the support shaft 149 which is fixed in a non-rotable manner, and the film member 148 supported by the support shaft 149 to be rotatable, and the support shaft 149 Between the and the developing roller 142, an electric field for electrostatically adsorbing the film member 148 to the developing roller 142 is formed. As a result, the film member 148 rotates stably in accordance with the rotation of the developing roller 142. In this manner, a separate driving mechanism for rotating the film member 148 is also unnecessary, and a roller having a toner conveying capacity with a small diameter can be formed.

FIG. 7 is a view showing a schematic configuration of a developing apparatus according to a second embodiment of the present invention, and FIG. 8 is a view for explaining the operation of the toner transfer member shown in FIG.

7 and 8, the developing apparatus 240 according to the second embodiment of the present invention is to remove the residual toner on the developing roller 242, the developer roller 242 to attach and transport the toner as a developer. RS roller 244, a stirring member 245 for stirring the toner, and a toner conveying member 247 provided in the toner supply area.

Each of these members is configured as in the first embodiment. The toner conveying member 247 of the developing apparatus 240 of the present embodiment is different from the developing apparatus 140 in the first embodiment in that the toner conveying ability, layer regulation and charging of the toner are also possible. For this reason, the developing device 240 does not have to be provided with a layer regulating charging blade for performing layer regulation and charging of the toner.

Hereinafter, the operation of the toner transfer member 247 according to the second embodiment of the present invention will be described in detail.

As the first embodiment, the toner transfer member 247 includes a flexible film member 248 and a support shaft 249 inserted into the film member 248. A voltage V2 is applied to the support shaft 249 and supplies voltage to the film member 248 by contact. In a state in which there is no potential difference between the developing roller 242 and the support shaft 249 (initial state), between the outer circumferential surface of the support shaft 249 and the inner circumferential surface of the film member 248 is very small as in the first embodiment. There is a gap.

In this embodiment, the voltage V2 applied to the support shaft 249 is greater than the voltage V2 in the first embodiment, and the toner charged between the support shaft 249 and the developing roller 242. Is set so that an electric field in the direction of being adsorbed by the developing roller 242 is formed. By this electric field, the film member 248 is electrostatically absorbed to the developing roller 242 by the electrostatic adsorption force (N1), the film member 248 and the developing roller 242 by a predetermined width, for example For example, a nip of about 1 to 2 mm is formed. At this time, the friction force F1 is generated between the developing roller 242 and the film member 247 from the relationship between the friction coefficient μ1 of the outer circumferential surface of the film member 248 and the electrostatic attraction force N1.

On the other hand, as shown in Figure 8, the electrostatic attraction force (N2) is generated between the film member 248 and the support shaft 249. However, only a small gap exists between the inner circumferential surface of the film member 248 and the outer circumferential surface of the support shaft 249. Small gaps between the inner circumferential surface of the film member 248 and the outer circumferential surface of the support shaft 249 are preferably smaller than those of the first embodiment. For this reason, the area | region which the said film member 248 contacts the said support shaft 249 becomes large. That is, the angle (rolling angle) that the film member 248 and the support shaft 249 adsorb becomes large, and as a result, the film member 248 is in the state of electrostatic adsorption on the support shaft 249.

At this time, the frictional force F2 between the inner circumferential surface of the film member 248 and the outer circumferential surface of the support shaft 249 from the relationship between the friction coefficient μ2 of the inner circumferential surface of the film member 248 and the electrostatic attraction force N2. ) Accordingly, the film member 248 does not rotate around the support shaft 249 by the action of the force F1 and the force F2 even when the developing roller 242 rotates. And sliding between the developing roller 242.

When toner is introduced between the film member 248 and the developing roller 249 in a state where sliding occurs between the film member 248 and the developing roller 242, the toner is slid with the film member 248. At the same time, the film member 248 is formed into a thin layer by the force adsorbed by the developing roller 242. By providing the toner transfer member 247 in the toner supply region C in this manner, the toner supplied by the stirring member 245 is easily mounted between the developing roller 242 and the film member 248. Supply of the toner is performed smoothly. In addition, the film member 248 may be adsorbed on the support shaft 249 so as not to rotate, and sliding may occur between the developing rollers 242 to charge the toner while performing layer regulation.

On the other hand, when the electric field formed between the film member 248 and the developing roller 242 is turned off at the time of non-image formation, the suction force on the support shaft of the film member 248 is slightly weakened. For this reason, the film member 248 is slightly rotated in accordance with the rotation of the developing roller 242. As a result, a portion of the film member 248 facing the developing roller 242 may be changed. Therefore, by changing the surface facing the developing roller 242 of the film member 248, adhesion and retention of anti-charge toner or the like to the surface of the film member 248 can be eliminated. As a result, the charge of the toner of the film member 248 and the life of the layer regulating portion can be extended.

As described above, according to the developing apparatus 200 according to the second embodiment of the present invention, the toner transport member 247 is provided in the toner supply region C where toner easily stays. The toner transfer member 247 is composed of a support shaft 249 fixedly rotatable and a film member 248 rotatably supported by the support shaft 249, and the support shaft 249 and the developing roller ( An electric field for electrostatically adsorbing the film member 248 to the developing roller 242 is formed between the 242. At this time, the film member 248 functions as an electrostatic adsorption force for adsorption on the developing roller 242 and a strong electrostatic adsorption force for adsorption on the support shaft 249. For this reason, the film member 248 adsorb | sucks to the support shaft 249, and makes sliding with the developing roller 242. As a result, the toner can be easily introduced between the developing roller 242 and the film member 248, and the toner can be regulated and charged.

9 is a view schematically showing the configuration of a developing apparatus according to a third embodiment of the present invention, Figure 10 is a view showing a state in which the electrostatic adsorption force does not operate between the film member and the developing roller shown in FIG. 11 is a view showing a state where the toner passes while the static adsorption force is operated between the film member and the developing roller shown in FIG. 9, and FIG. 12 shows a first modified example of the layer regulating charging member shown in FIG. FIG. 13 is a view showing a second modification of the layer regulating charging member shown in FIG. 9.

9, the developing apparatus 340 according to the third embodiment of the present invention supplies a developing roller 342 for attaching and conveying toner as a developer, and supplies the toner to the developing roller 342, And a layer regulating charging member 345 for performing layer regulation of the toner on the developing roller 342 and charging the toner. .

The developing roller 342 and the RS roller 343 have the same construction and operation as the first embodiment shown in FIG. 4 and the second embodiment shown in FIG.

The layer regulating charging member 345 is a member for performing layer regulation and charging of the toner, and is provided along the circumference of the developing roller 342. The RS roller 343 is disposed on the upstream side of the developing roller in the rotational direction with respect to the layer regulating charging member 345 so that the photosensitive drum 341 is positioned on the downstream side of the developing roller in the rotating direction. The layer regulating charging member 345 includes a film member 346 having flexibility and a support member 346 supporting the film member 346.

The film member 346 makes the layer of toner adhered to the developing roller 342 uniform and at the same time frictionally charges the toner. The film member 346 preferably includes at least a middle resistance layer formed of a material having a resistance value (volume resistance value or surface resistance value) of about 104 to 109 Ω · cm. The medium resistance layer is formed of, for example, a polymer film mainly made of polyimide, polycarbonate, polyamide, or the like.

Here, the film member 345 may include a surface resistance layer in addition to the medium resistance layer as shown in FIG. 11. In the case of forming the surface resistive layer, for example, the layer 347a on the upstream side of the developing roller rotation direction, which is an inlet for toner, is formed of a low resistance material, and the layer 347b on the downstream side of the developing roller rotation direction is high. It can be formed of a resistance material (insulation material). As a result, the upstream side of the developing roller rotation direction increases the electrostatic adsorption force, and can maintain the film member 345 and the micro gap 348 formed by the developing roller 342 more consistently to stabilize the inflow of toner. Can be.

On the other hand, the downstream side of the developing roller rotation direction becomes smaller electrostatic attraction force, it is possible to prevent the improvement of the free end of the film member 345. At this time, since the conducting is performed with the surface of the film member 345 interposed therebetween, a connecting member (not shown) for electrically connecting the heavy resistance layer of the film member 345 and the supporting member 346 is provided. As a connection member, electroconductive layered sheet members, such as a copper tape, are used, for example.

In addition, a coating layer (not shown) may be provided on a surface of the film member 345 facing the developing roller 342. For example, the upstream side of the developing roller rotation direction of the coating layer may be formed of a material having a high surface hardness to prevent breakage of the film member 345 due to toner. The layer with high surface hardness can be formed, for example with polyphenylene sulfide (PPS). In addition, a good wear resistance, polyurethane (PP) can be used. The downstream side of the developing roller rotational direction of the coating layer is formed of a material having a low surface energy, thereby preventing toner from adhering to the film member 345. The layer with low surface energy can be formed, for example, by fluorine coating or the like.

In addition, in the present embodiment, the thickness of the film member 345 is preferably formed to about 50 ~ 500μm. In addition, the film member 345 is formed of a material having flexibility so as not to apply high linear pressure to the developing roller 342.

As shown in FIG. 10, the film member 345 is fixed to the support member 346 at one end (hereinafter, referred to as a fixed end 345a) of an upstream side (A side) in the developing roller rotation direction. The other end (hereinafter, referred to as the free end 345b) side of the downstream side (B side) in the developing roller rotation direction is curved and provided so that at least a part thereof is circumscribed to the developing roller 342.

The fixed end 345a of the film member 345 is fixed to the position where the micro gap 348 is formed between the film member 345 and the developing roller 342 by the support member 346. The microgap 348 serves as an inlet for toner. The width of the microgap 348 is determined according to the size of the toner. The width of the microgap 348 varies depending on the thickness of the film member 345, the bending stiffness, and the like, but the end portion 346a and the developing roller 342 facing the developing roller 342 of the support member 346. Is regulated by the distance (d) to the outer peripheral surface. Here, the distance d is set, for example, about 2 mm or less, preferably about 0.3 to 0.5 mm. As such, the fixing end 345a of the film member 345 is fixed to the end portion 346a of the developing roller 342 side of the supporting member 346 so that the micro gap 348 does not change due to the conveying pressure of the toner. The toner layer may be regulated to a predetermined thickness at the inlet of the film member 345.

The free end 345b of the film member 345 is bent between the end portion 346a of the developing roller 342 side of the supporting member 346 and the developing roller 342 to form an English letter r, and the developing roller rotation direction It is disposed downstream of (B). At this time, at least a part of the free end 345b of the film member 345 is in contact with the outer circumferential surface of the developing roller 342. Further, as the film member 345 is directed downstream from the contact portion of the film member 345 and the developing roller 342 toward the downstream B in the developing roller rotation direction, the film member 345 has the developing roller 342 due to its toughness. It has a shape that seems to be spaced upward from the. The free end 345b of the film member 345 is provided to have a length in which at least a part of the free end of the film member 345 is in contact with the outer circumferential surface of the developing roller 342. The length of the free end 345b of the film member 345 may be, for example, about 5 to 10 mm in length.

In addition, the film member 345 has an electric field in the direction in which the toner charged between the film member 345 and the developing roller 342 is attached to the developing roller 342, that is, in the direction of the rotation center of the developing roller 342. The voltage V2 is applied so that it may be. The voltage supply to the film member 345 is determined according to the formation position of the middle resistance layer of the film member 345. For example, when the middle resistance layer is formed on the surface opposite to the developing roller 342 by the film member 345, as shown in FIG. 10, the support member 346 is formed of a conductive material, By applying the voltage V2 to the support member 346, the film member 345 may be electrically conductive in contact with the support member 346.

When the volume resistance of the film member 345 is a heavy resistance, for example, as shown in FIG. 12, a voltage supply member 349 for applying a voltage to the film member 345 may be provided. have. The voltage supply member 349 is formed of, for example, a conductive sponge member. The voltage supply member 349 is in contact with one surface of the film member 345 positioned above the contact portion of the film member 345 and the developing roller 342 (the surface opposite to the surface facing the developing roller 342). Prepared.

In addition, when the middle resistance layer is formed on the surface side facing the developing roller 342 of the film member 345, for example, as shown in FIG. It may be provided so as to be fixed to the downstream side of the developing roller rotation direction of 346. In this case, as shown in FIG. 10, the support member 346 is formed of a conductive material, and a voltage is applied to the film member 345 at the contact surface of the support member 346 by applying a voltage to the support member 346. Can be authorized. As such, according to the formation position of the heavy resistance layer of the film member 345, a voltage may be supplied to the film member 345.

When a voltage is applied to the film member 345 such that an electric field is formed between the developing roller 342, the film member 345 is electrostatically absorbed on the outer circumferential surface of the developing roller 342, and the film member 345. The nip width is increased between and the developing roller 342. The nip width increases in proportion to the magnitude of the voltage applied to the film member 345. In this embodiment, the nip is formed so that the width (width in the circumferential direction of the developing roller 342) is about 1 to 2 mm. As the toner passes through the nip, the toner becomes a uniform thin layer and the toner is triboelectrically charged.

In addition, the developing apparatus 340 according to the present embodiment includes a voltage controller (not shown) for controlling a voltage applied to the film member 345. By controlling the voltage applied to the film member 345 by the voltage controller, the strength of the electric field formed between the film member 345 and the developing roller 342 can be controlled.

Next, the operation of the developing apparatus 340 according to the present embodiment will be described along the circulation flow of the toner. In addition, the operation of the developing apparatus 340 at the time of image development is demonstrated.

The developing apparatus 340 according to the present embodiment supplies the toner contained in the toner container portion (not shown) to the developing roller 342 by the RS roller 343. Since the RS roller 343 is provided by pressing the developing roller 342, a nip is formed by the RS roller 343 and the developing roller 342. As shown in Fig. 9, for example, the RS roller 343 rotating in the counterclockwise direction carries the toner in the toner container and conveys it to the nip. On the other hand, the developing roller 342 is also rotating counterclockwise. For this reason, the toner conveyed by the RS roller 343 is rubbed into the developing roller 342 without entering the nip portion, and is attached to the developing roller 342.

The toner attached to the developing roller 342 is layer regulated and charged by the layer regulating charging member 344 provided along the main direction of the developing roller 342. Although the thickness of the toner layer before passing through the microgap 348 formed between the film member 345 and the developing roller 342 of the layer regulating charging member 344 is different, the toner passes through the microgap 348. Amount of toner passing through the nip formed by the film member 345 and the developing roller 342 is regulated.

As described above, the fixed end 345a of the film member 345 is supported by the support member 346, and the free end 345b of the film member 345 is the developing roller 342 of the support member 346. The film member 345 is bent at the side end 346a. Therefore, even if the conveying pressure of the toner increases, the free end 345b of the film member 345 is supported by the end portion 346a of the supporting member 346, so that the width of the microgap 348 is kept substantially constant. do. With such a configuration, since the microgap 348 does not change even when the conveying pressure of the toner varies, the amount of toner flowing into the nip can be regulated to be substantially constant.

As the toner passed through the microgap 348 formed between the film member 345 and the developing roller 342, as shown in FIG. 11, the nip formed by the film member 345 electrostatically adsorbed on the developing roller 342. To pass. The toner is triboelectrically charged by rubbing on the film member 345 as it passes through the nip.

Here, the film member 345 is configured to include a medium resistance layer made of a medium resistance material, as described above. For this reason, the electrostatic adsorption force functioning between the film member 345 and the developing roller 342 is weak compared with the conventional doctor blade 20 made of, for example, the metal thin plate shown in FIG. In addition, since the film member 345 is formed of a material having flexibility and toughness, the film member 345 functions flexibly with respect to the toner passing through the nip by the remaining film. Therefore, the linear pressure applied to the developing roller 342 can be lowered compared to the developing apparatus 1 in which a high linear pressure is applied to the conventional developing roller 10 shown in FIG. 2, and the stress applied to the toner passing through the nip can be reduced. Can be.

Further, in the nip, the toner layer on the developing roller 342, which is regulated to be an almost uniform layer in the microgap 348, is layer regulated so as to be a more uniform thin layer. The layer regulation of the toner layer is performed by pressing the toner against the developing roller 342 by passing the toner through a nip in which the electrostatic adsorption force functions in the rotational center direction of the developing roller 342. At this time, since the toner layer regulation has already been performed once in the microgap 348, a large pressing force is unnecessary for the layer regulation of the toner in the nip. Therefore, layer control can be performed without stressing the toner. As described above, the layer regulating charging member 344 according to the present embodiment regulates the inflow amount of the toner in the microgap 348 and further converges to the thin layer in the nip. By regulating the toner layer in two steps, a uniform and thin toner layer can be formed without requiring a large pressing force.

Here, the voltage control unit may control the voltage so that the current value of the electric field formed between the film member 345 and the developing roller 342 is constant. Thereby, despite the toner interposed between the film member 345 and the developing roller 342, the electrostatic adsorption force between both members can be kept constant, and the toner layer can be regulated more uniformly.

The toner on the developing roller 342, which is charged by passing through the nip and is made of a uniform thin layer, is partially attached to the photosensitive drum 341 at a position where the photosensitive drum 341 on which the electrostatic latent image is formed and the developing roller 342 are close to each other. do. The toner remaining in the developing roller 342 without adhered to the photosensitive drum 341 is mechanically separated from the developing roller 342 at the contact portion between the developing roller 342 and the RS roller 343. The peeled toner is conveyed by the RS roller 343 and supplied to the developing roller 342 again.

The developing apparatus 340 according to the third embodiment of the present invention as described above forms a nip by electrostatically adsorbing the film member 345 to the developing roller 342, and the toner on the developing roller 342 passes through the nip. The toner is charged at the same time as the layer regulation is performed. As described above, the electrostatic adsorption of the film member 345 applies a voltage to the film member 345 and depends on an electric field formed between the developing roller 342 and the film member 345. Therefore, the voltage control unit of the developing apparatus 340 according to the present embodiment may control the toner processing on the developing roller 342 by controlling the voltage applied to the film member 345 according to the driving state of the developing apparatus 340. have.

For example, at the time of development, since the voltage controller performs layer regulation and charging of the toner as described above, the film member 345 so as to function as an electrostatic adsorption force for adsorbing the film member 345 to the developing roller 342. Apply voltage to For example, the voltage is controlled so that the voltage between the film member 345 and the developing roller 342 is about 0 to 600V. Here, the voltage control unit may control the amount of toner passing through the nip by controlling the voltage applied to the film member 345 to adjust the strength of the electric field.

In the absence of development, the voltage control unit controls the voltage so that an electric field opposite to that in development is formed between the development roller 342 and the film member 345. Alternatively, voltage control is performed so as not to apply or apply voltage to the film member 345. By controlling the voltage applied to the film member 345 by the voltage controller in this manner, the toner charged with the reverse polarity is attached to the developing roller 342, not the toner charged with the normal polarity attached to the film member 345. Can be discharged. Alternatively, the voltage applied to the film member 345 may be lowered so that the electric field at the time of non-development becomes lower than the electric field at the time of development. In this case, the electrostatic adsorption force between the developing roller 342 and the film member 345 decreases, and the electrical adsorption force of the reverse polar toner by the electric field to the film member 345 also decreases, so that together with the positive toner Reverse polar toner can also be discharged.

At the end of the development, a voltage for removing the toner layer on the development roller 342 is applied to the film member 345 by the voltage control unit. That is, between the film member 345 and the developing roller 342, the voltage controller applies a voltage to the film member 345 so that a stronger electric field than the developing time or an electric field opposite to the developing time is formed. As a result, the toner layer on the developing roller 342 can be removed, thereby preventing mixing of color in the multicolor image forming apparatus, adhesion of toner when the developing apparatus is replaced, and the like.

The developing apparatus 340 according to the third embodiment of the present invention has been described above. The developing device 340 has a uniform nip along the longitudinal direction of the developing roller 342 by the electrostatic adsorption force, flexibly responds to the variation in the rotational direction of the developing roller 342, and also the developing roller 342. The toner layer, which is a uniform thin layer, can be formed on the outer circumferential surface of the substrate. As a result, the film member 345 adapts even if the outer diameter of the developing roller 342 changes due to a change in the environment, so that the toner layer formed on the developing roller 342 also changes in chargeability or toner layer thickness due to the environment. No image quality can be stabilized.

As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the claims, and they are naturally understood to belong to the technical scope of the present invention.

For example, in the above first and second embodiments, the support shaft is fixed so as not to rotate, but the present invention is not limited to this example and may be provided to be rotatable. In this case, during the development, the rotation of the support shaft is stopped to charge and layer the toner between the film member and the developing roller. On the other hand, at the time of non-image formation, the support shaft is slightly rotated in the state where the electric field is formed, and the opposite surface to the developing roller is changed. In the state in which the electric field is formed, since the film member is electrostatically absorbed by the support shaft, the film member and the support shaft are integrally rotated.

Moreover, in the said 2nd Example, although the rolling angle of the film member 248 and the support shaft 249 was enlarged by reducing the clearance gap between the inner peripheral surface of the film member 248 and the outer peripheral surface of the support shaft 249, this invention Is not limited to this example, and for example, the rolling angle can be increased by lowering the rigidity of the film member 248.

In the third embodiment, the voltage supply to the film member was supplied from the fixed end side of the film member, but the present invention is not limited to this example. For example, the voltage may be supplied from both the fixed end side and the free end side of the film member. At this time, when the voltage applied from the fixed end side is weaker than the voltage applied from the free end side, the electrostatic adsorption force generated on the fixed end side of the film member becomes larger than the electrostatic adsorption force on the free end side. As a result, the minute gap into which the toner is introduced can be kept more constant, and the inflow amount of the toner can be stabilized.

As described above, the developing apparatus and the image forming apparatus employing the same according to the present invention

First, it is provided with a toner conveying member having a small toner supply capacity, so that the toner is smoothly supplied to the developing roller and the layer regulating charging member,

Second, there is an effect of forming a uniform toner layer while simultaneously charging the toner.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (14)

A developing roller for transferring the developer to the outer circumferential surface thereof; A film member provided near or in contact with the developing roller in a developer supply region at the lower side of the developing roller, and inserted into the film member, the predetermined distance between the inner surface of the film member along its circumferential direction; And a toner transfer member having a gap formed therein and having a support shaft for rotatably supporting the film member. The method of claim 1, The support shaft is fixed so as not to rotate, A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member to the developing roller is formed between the developing roller and the support shaft. And the film member is rotated in accordance with the rotation of the developing roller. The method of claim 1, The support shaft is fixed so as not to rotate, A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member on the support shaft is formed between the developing roller and the support shaft. The film member is a developing apparatus, characterized in that for causing the sliding of the developing roller. The method of claim 1, The support shaft is installed to be rotatable, A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member on the support shaft is formed between the developing roller and the support shaft. And the support shaft and the film member are integrally rotated. A developing roller for attaching and conveying a developer to an outer circumferential surface thereof; A film member having flexibility, which charges the developer while simultaneously regulating a layer of a developer attached to the developing roller, and supporting the film member so that at least a part of the film member is externally circumscribed to an outer circumferential surface of the developing roller. It is provided with a layer regulating charging member having a support member, The fixed end of the film member fixed to the support member is provided so that a small gap, which is an introduction port of the developer formed between the developing roller and the film member, becomes constant. The free end of the film member is electrostatically adsorbed to the developing roller by applying a voltage to the film member, And the microgap is 2 mm or less. delete 6. The method of claim 5, And the film member further comprises a medium resistance layer made of at least a medium resistance material, wherein the resistance value of the medium resistance layer is 104 to 109 Ω · cm. 8. The method of claim 7, And a voltage supply member provided to contact one surface of the film member to apply a voltage to the film member. 6. The method of claim 5, And a different voltage is applied to the film member and the developing roller. 6. The method of claim 5, The film member further includes a surface resistive layer, The upstream side of the rotational direction of the developing roller of the surface resistance layer is made of a low resistance material, and the downstream side of the rotational direction of the developer carrying member of the surface resistance layer is made of a high resistance material. An image forming apparatus comprising at least one developing device and a fixing device for fusing an image onto a print medium, The developing device A developing roller for transferring the developer to the outer circumferential surface thereof; A film member provided near or in contact with the developing roller in a developer supply region at the lower side of the developing roller, and inserted into the film member, the predetermined distance between the inner surface of the film member along its circumferential direction; And a toner transfer member having a gap formed thereon and having a support shaft rotatably supporting the film member. 12. The method of claim 11, The support shaft is fixed so as not to rotate, A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member to the developing roller is formed between the developing roller and the support shaft. And the film member is rotated in accordance with the rotation of the developing roller. 12. The method of claim 11, The support shaft is fixed so as not to rotate, A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member on the support shaft is formed between the developing roller and the support shaft. And the film member causes sliding with respect to the rotation of the developing roller. 12. The method of claim 11, The support shaft is installed to be rotatable, A voltage is applied to the support shaft such that an electric field for electrostatically adsorbing the film member on the support shaft is formed between the developing roller and the support shaft. And the support shaft and the film member are integrally rotated.

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