JP2002023493A - Non-magnetic one-component developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To steadily form a toner layer of a uniform thickness on a developing roll by a toner layer thinning roll, in a non-magnetic one-component developing device. SOLUTION: The device has a developing roll on the surface of which a toner layer is formed from non-magnetic one-component developer, and a toner supply roll which is arranged in contact with the developing roll and supplies toner to the developing roll. The device also has the toner layer thinning roll 27 which is composed of a shaft 27a, an elastic body 27b provided on the periphery of the shaft 27a, and a metal pipe 27c, serving as a rigid member, provided on the periphery of the elastic body 27b and which forms a toner layer of a specific thickness on the developing roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic one-component developing apparatus using only a non-magnetic toner as a developer in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus.

[0002]

2. Description of the Related Art In image forming apparatuses, equipment using dry toner occupies the mainstream, and many copiers, laser printers,
It has been put to practical use as plain paper facsimile, etc., and has achieved remarkable development. This image forming apparatus is an apparatus to which an electrophotographic process technology is applied, and visualizes an electrostatic latent image formed on a photoconductor as an electrostatic latent image carrier by toner particles.

As a developing device used in such an image forming apparatus, an apparatus using a non-magnetic one-component developing apparatus which is advantageous in reducing the size and cost of the apparatus is becoming widespread.

Hereinafter, the configuration and operation of a conventional non-magnetic one-component developing apparatus will be described with reference to FIG.

FIG. 5 is a schematic view showing the structure of an image forming apparatus using a conventional non-magnetic one-component developing device.

The illustrated image forming apparatus is an image forming apparatus for visualizing an electrostatic latent image formed on a photoconductor by electrophotographic process technology using toner particles, and a photoconductor 1 as an electrostatic latent image carrier. have. The photoconductor 1 rotates in the circumferential direction and conveys a sheet described later.

[0007] A charger 2 is provided near the photoconductor 1. The charger 2 includes a metal shield plate 2b having an opening formed toward the photoreceptor 1 and a tungsten wire, for example, and is stretched in the width direction of the photoreceptor 1 in the shield plate 2b. It is composed of a charged wire 2a and a grid plate 2c attached to the opening.
Then, the photoconductor 1 is uniformly charged via the grid plate 2c by corona discharge by the charging wire 2a. And
When the photosensitive member 1 is irradiated with the exposure light beam 4 obtained from the exposure optical system 3, the photosensitive member 1 is exposed to form a predetermined electrostatic latent image.

A toner supply roller 6 for supplying the toner 10 stirred and conveyed to the surface of the developing roller 5 by a toner stirring member 11 rotatably supported at both ends of the developing hopper 9 is provided. The toner supply roller 6 is made of a metal shaft 6a made of stainless steel or the like, and an elastic member such as urethane or silicon is formed in a layered manner around the shaft 6a. Reference numeral 26 is connected to apply a DC supply voltage or a toner supply bias voltage in which DC and AC are superimposed.

The developing roller 5 has a shaft 5a made of metal such as stainless steel as a base material and an elastic member such as urethane or silicon formed in a layer on the outer peripheral surface. A developing bias voltage supply power supply 12 which is a constant voltage power supply is connected to the shaft 5a of the developing roller 5.

The toner 10 is a non-magnetic one-component toner. For example, carbon, wax,
It is composed of a material in which a charge control agent and the like are uniformly dispersed.

The developing roller 5 and the toner supply roller 6 are arranged in contact with each other, and are rotatably supported at both ends of a developing hopper 9 by shafts 5a and 6a, respectively. The developing roller 5 and the photoreceptor 1 contact each other and rotate in opposite directions.
And the toner supply roller 6 contact each other and rotate in the same direction.

The developing roller 5 is in contact with the photoreceptor 1, and supplies toner to a portion of the photoreceptor 1 where an electrostatic latent image is formed by a bias voltage applied from a developing bias voltage supply power supply 12. When the toner 6 is transferred and adhered by the roller 6, the electrostatic latent image is visualized.

Incidentally, the toner stirring member 11 is connected to the developing hopper 9
The toner 10 is prevented from aggregating, and the toner 10 is conveyed toward the toner supply roller 6.

A toner thinning blade 7 is provided in contact with the developing roller 5. This toner thinning blade 7
Is composed of a metal spring plate member 7a having elasticity and a toner thinning member 7b contacting on the developing roller 5. The toner thinning member 7b is formed by integrally forming an elastic member such as urethane rubber or silicon rubber at one end of a metal spring plate member 7a. Such a toner thinning blade 7 is screwed to a blade holder 8.

The toner thinning blade 7 presses the developing roller 5 with a predetermined linear pressure, and the toner 10 supplied from the toner supply roller 6 to the developing roller 5 is triboelectrically charged by the toner thinning blade 7. As a result, a thin toner layer is formed on the outer peripheral surface of the developing roller 5.

Paper 15 is stored in a paper cassette 14 provided at the starting point of the transport path. The paper 15 is sent out from the paper cassette 14 to the transport roller 17 one by one by a paper feed roller 16. Then, the fed sheet 15 is sandwiched between a pair of transport rollers 17 and is moved by an arrow A.
Is transported in the direction of the photoconductor 1 indicated by.

In order to match the paper 15 with the toner image formed on the photoreceptor 1, on the transport path before reaching the photoreceptor 1, a registration roller 18 abuts against a driven roller 19.
Is provided. Further, a transfer roller 20 is provided so as to be rotatably supported in contact with the photoconductor 1.

When the toner image reaches the contact portion between the transfer roller 20 and the photosensitive member 1 as the photosensitive member 1 rotates, the paper 15 is also brought into contact with the toner image by the registration roller 18 in timing. To reach. At this time, when a high voltage from a transfer bias voltage supply power supply 24 is applied to the metal shaft 20a of the transfer roller 20 to apply a charge having a polarity opposite to that of the toner 10 to the back surface of the sheet 15, the toner image is transferred onto the sheet 15. Is done.

A fixing unit 21 including a heat roller 22 having a heat source therein and a pressure roller 23 for sandwiching and conveying the sheet 15 together with the heat roller 22 is provided at a stage subsequent to the conveyance path. The paper 15 on which the toner image has been transferred is sent to the fixing device 21 where the toner image is fixed.

On the other hand, the photoreceptor 1 after the toner image has been transferred onto the paper 15 has the transfer residual toner scraped off by the cleaning blade 25, and is irradiated with light by the charge remover 13 to be discharged, and the next process is performed. Be provided.

[0021]

However, in the above-described non-magnetic one-component developing device, since the toner is charged by friction, when the printing speed is increased, the stress on the toner is increased. There is a problem that the toner aggregates at a contact portion with the thinning blade, and the toner eventually adheres to the surface of the toner thinning blade.

Further, in order to prevent an offset phenomenon in which the toner on the paper is transferred to the surface of the heat roller in the fixing step, wax such as polyethylene or polypropylene having a low molecular weight, which sufficiently melts when heated, is added to the toner. There is. Since such additives increase the cohesiveness of the toner, the problem that the toner adheres to the surface of the toner thinning blade occurs as described above.

If the toner adheres to the surface of the toner thinning blade, it becomes impossible to form a toner layer having a uniform thickness on the developing roller.

In order to solve these problems, it is effective to use a toner thinning roller system in which a rotating roller is disposed in contact with the developing roller to form a toner layer on the developing roller.
Generally, the toner thinning roller is made of a rigid body such as metal, and applies a load to both ends thereof to regulate the toner over the entire length of the developing roller in the axial direction.

However, in this toner thinning roller system, since a load is applied only to both ends of the developing roller, the toner thinning roller slightly bends, and the load on the central developing roller is reduced. As a result, a difference occurs in the amount of toner adhered on the developing roller, and unevenness in density occurs in the image.

Accordingly, an object of the present invention is to provide a non-magnetic one-component developing apparatus capable of stably forming a toner layer having a uniform thickness on a developing roller by a toner thinning roller.

[0027]

In order to solve this problem, a non-magnetic one-component developing apparatus according to the present invention comprises a developing roller having a toner layer made of a non-magnetic one-component developer formed on a surface thereof; And a toner supply roller for supplying toner to the developing roller, a shaft, an elastic member provided on the outer periphery of the shaft, and a rigid member provided on the outer periphery of the elastic member. And a toner thinning roller for forming a toner layer of a predetermined thickness on the developing roller.

Accordingly, when a load is applied to both ends of the shaft, the elastic body located inside the rigid member is deformed, and the load on the rigid member becomes uniform, so that the toner thinning roller does not bend. In addition, the pressing force of the toner thinning roller against the developing roller is made uniform, and a toner layer having a uniform thickness over the entire length of the developing roller can be stably formed by the toner thinning roller.

[0029]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a developing roller having a toner layer formed of a non-magnetic one-component developer formed on a surface thereof, and a developing roller are disposed in contact with the developing roller. A toner supply roller for supplying toner, a shaft, an elastic member provided on the outer periphery of the shaft, and a rigid member provided on the outer periphery of the elastic member; A non-magnetic one-component developing device having a toner thinning roller for forming a toner layer having a predetermined thickness on the upper surface thereof. When a load is applied to both ends of the shaft, an elastic body located inside the rigid member is deformed. As a result, the load on the rigid member becomes uniform, and the toner thinning roller does not bend, so that the pressing force of the toner thinning roller against the developing roller is uniform, and the toner thinning roller extends over the entire length of the developing roller. It has the effect that it is possible to stably form a uniform thin toner layer of the roller a toner layer thickness.

According to a second aspect of the present invention, there is provided the non-magnetic one-component developing device according to the first aspect, wherein the hardness of the elastic body is set to be smaller than the surface hardness of the developing roller. This has the effect that the pressing force of the layering roller against the developing roller is made more uniform, and a toner layer having a uniform thickness can be stably formed on the developing roller by the toner thinning roller.

According to a third aspect of the present invention, in the first or second aspect of the invention, the elastic body is a non-magnetic one-component developing device comprising a foam, and the elastic body is easily developed. The pressing force of the toner thinning roller against the developing roller can be made more uniform, since it can be made smaller than the hardness of the roller,
This has the effect that a toner layer having a uniform thickness can be stably formed on the developing roller by the toner thinning roller.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a toner seal for preventing toner leakage is provided at both ends of the toner thinning roller. A member is provided, and both ends of the elastic body are non-magnetic one-component developing devices located inside the rigid member. Since the elastic body and the toner seal member do not contact each other, it is possible to prevent toner leakage for a long time. Has the effect that it becomes possible.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is a schematic view showing the structure of an image forming apparatus using a non-magnetic one-component developing device according to an embodiment of the present invention, and FIG. 2 is a thin toner layer in the non-magnetic one-component developing device of FIG. 3 is a perspective view showing a main part of a non-magnetic one-component developing device according to another embodiment of the present invention, and FIG. 4 is a toner thin layer in the non-magnetic one-component developing device of FIG. It is a perspective view which shows a forming roller.

The image forming apparatus according to the present embodiment is an image forming apparatus for visualizing an electrostatic latent image formed on a photosensitive member (electrostatic latent image carrier) by electrophotographic process technology with toner particles. As shown in FIG. 1, a photosensitive drum such as selenium (Se) or an organic photoconductor (hereinafter, referred to as "OPC") is formed in a thin film on the outer peripheral surface of a metal drum such as aluminum as a base material. The photosensitive member 1 is formed by coating. The photoconductor 1 rotates in the circumferential direction to convey a sheet described later.

A charger 2 is provided near the photosensitive member 1 serving as an electrostatic latent image carrier. The charger 2 includes a metal shield plate 2 having an opening formed toward the photoconductor 1.
b, for example, a tungsten wire or the like, a charged wire 2a stretched in the width direction of the photoreceptor 1 in the shield plate 2b, and a grid plate 2c attached to the opening.
It is composed of Then, the photoconductor 1 is uniformly charged via the grid plate 2c by corona discharge by the charging wire 2a.

When the photosensitive member 1 is irradiated with an exposure light beam 4 obtained from an exposure optical system 3 by modulating the image signal with light intensity modulation or pulse width by a laser driving circuit (not shown), the photosensitive member 1 Upon exposure, a predetermined electrostatic latent image is formed.

The toner 10 stirred and conveyed by a toner stirring member 11 rotatably supported at both ends by a developing hopper 9 is supplied to the surface of the developing roller 5 as a toner carrier, and remains without being developed. Toner 1 on developing roller 5
In order to scrape 0, a toner supply roller 6 is provided. The toner supply roller 6 is formed by forming a conductive foam on an outer peripheral surface of a shaft 6a made of a metal such as stainless steel, and has a resistance value of 10 ⁶ Ω · cm. A toner supply bias voltage supply power supply 26, which is a constant voltage power supply, is connected to the shaft 6a of the toner supply roller 6, and a toner supply bias voltage is applied.
In the present embodiment, the nip width between the toner supply roller 6 and the developing roller 5 is 2 mm.

The developing roller 5 is intended a metal shaft 5a of stainless steel or the like of the single-layer silicon rubber was formed is a conductive elastic member on its outer circumferential surface as a base material, the resistance value, for example 10 ⁶ Ω · cm. A developing bias voltage supply power supply 12 which is a constant voltage power supply is connected to the shaft 5a of the developing roller 5.

Here, the rubber hardness of the developing roller 5 is preferably in the range of 30 to 60 degrees from the viewpoint of prevention of creep and dents, and the higher the surface roughness is, the thinner the toner layer is. Since uniformity can be achieved in the formation of
7 μmRz is preferred. The developing roller 5 according to the present embodiment has a rubber hardness of 40 degrees and a surface roughness of 2 μmR.
z.

The toner 10 is a non-magnetic one-component toner. For example, carbon, wax,
It is composed of a material in which a charge control agent and the like are uniformly dispersed.

The developing roller 5 and the toner supply roller 6 are arranged in contact with each other, and are rotatably supported by shafts 5a and 6a at both ends of the developing hopper 9, respectively.

As shown, the developing roller 5 and the photosensitive member 1
And the developing roller 5 and the toner supply roller 6 come into contact with each other and rotate in the same direction (in the counterclockwise direction indicated by an arrow C). The rotation direction of the photoconductor 1 indicated by an arrow D that is clockwise with respect to the rotation direction of the developing roller 5 and the rotation direction of the toner supply roller 6 indicated by an arrow B). Therefore, the developing roller 5 and the toner supply roller 6 are in frictional contact.

The developing roller 5 is in contact with or close to the photosensitive member 1, and a portion where an electrostatic latent image is formed on the photosensitive member 1 by a developing bias voltage applied from a developing bias voltage supply power supply 12. When the toner 10 is transferred and adhered by the toner supply roller 6, the electrostatic latent image is visualized.

The toner agitating member 11 draws a circular locus with the rotation of the toner supply roller 6 to prevent the toner 10 contained in the developing hopper 9 from aggregating, and to convey the toner 10 toward the toner supply roller 6. I do.

The toner thinning roller 27 that contacts the developing roller 5 to regulate the amount of toner supplied to the developing roller 5 and forms a toner layer having a predetermined thickness on the developing roller 5.
Is provided. Then, the toner thinning roller 2
7, a scraper 29 for removing the toner attached to the toner thinning roller 27 is provided.

As shown in detail in FIG. 2, the toner thinning roller 27 is provided with a shaft 27a as a rotating shaft, an elastic member 27b provided on the outer periphery of the shaft 27a, and an outer member of the elastic member 27b. And a metal pipe 27c which is a cylindrical rigid member.

To the toner thinning roller 27, a toner thinning bias voltage supply power supply 28 for applying a toner thinning bias voltage to the toner thinning roller 27 is connected, as shown by an arrow E. , In the same direction as the developing roller 5. As a result, the toner becomes thinner
And the developing roller 5 are sufficiently charged by friction. This rotation direction is a direction in which the toner 10 is collected in the developing hopper 9. This is the toner thinning roller 2
When the developing roller 7 is rotated in the opposite direction to the developing roller 5, the toner 10
Is ejected out of the developing hopper 9.

Here, the surface roughness of the outer peripheral surface of the metal pipe 27c is preferably 0.1 μmRz to 5 μmRz since the higher the surface smoothness, the more uniform the formation of the thin toner layer.
Is preferable. Metal pipe 2 in the present embodiment
7c, the surface roughness is 0.5 μmRz. The nip width between the toner thinning roller 27 and the developing roller 5 is 2 mm.

The photosensitive member 1, the developing roller 5, the toner supply roller 6, and the toner thinning roller 27 are arranged so as to be always in contact with each other at their contact portions.

Paper 15 is stored in a paper cassette 14 provided at the starting point of the transport path. The paper 15 is fed to a paper cassette 14 by a half-moon shaped paper feed roller 16.
Are fed out to the transport roller 17 one by one. Then, the fed recording sheet 15 is nipped by a pair of transport rollers 17 and transported in the direction of the photoconductor 1 indicated by an arrow A.

The paper 15 is temporarily stopped and waited, and the paper 1 is stopped.
In order to make the toner image 5 and the toner image formed on the photoconductor 1 coincide with each other, a driven roller 1
9 is provided with a registration roller 18.
Further, a transfer roller 20 is provided so as to be rotatably supported in contact with the photoconductor 1. The transfer roller 20 is formed by forming a conductive foam around a metal shaft 20a made of stainless steel or the like, and has a resistance value of 10 ⁷ Ω · cm. A transfer bias voltage supply power supply 24, which is a constant current power supply, is connected to the shaft 20a.

When the toner image reaches the contact portion between the transfer roller 20 and the photosensitive member 1 with the rotation of the photosensitive member 1, the paper 15 is also brought into contact with the toner image by the registration roller 18 in timing. To reach. At this time, when a high voltage from the transfer bias voltage supply power supply 24 is applied to the metal shaft 20a of the transfer roller 20 to apply a charge having a polarity opposite to that of the toner 10 to the back surface of the sheet 15, the toner image on the photoconductor 1 becomes The image is transferred onto the paper 15.

At the subsequent stage of the transport path, there is provided a fixing device 21 composed of a heat roller 22 having a heat source therein, and a pressure roller 23 for sandwiching and transporting the sheet 15 together with the heat roller 22. Accordingly, the paper 15 on which the toner image has been transferred is sent to the fixing device 21, where the toner image is fixed by pressure and heat by the sandwiching rotation of the heat roller 22 and the pressure roller 23. On the other hand, the photoreceptor 1 after the toner image has been transferred onto the paper 15 has the transfer residual toner scraped off by the cleaning blade 25, and is irradiated with light by the charge eliminator 13 to be neutralized, thereby preparing for the next process.

[0055]

Next, an embodiment of the present invention will be described.

In the electrophotographic apparatus using the non-magnetic one-component developing device shown in FIG. 1, the toner thinning roller 27 having the structure shown in FIG. The amount was measured to evaluate the toner thin layer uniformity. As a comparative example, the same evaluation was performed using a roller made of metal only.

Here, the peripheral speed of the photosensitive member 1 is 200 mm / sec, and the peripheral speed of the developing roller 5 is 3 mm.
20 mm / sec, the peripheral speed of the toner supply roller 6 is 16
0 mm / sec, the peripheral speed of the toner thinning roller 27 is 8
It was set to 0 mm / sec.

The evaluation results are shown in Table 1 below.

[0059]

[Table 1]

As is clear from Table 1, the elastic member 27
b and metal pipe 27c.
7, it can be seen that there is almost no difference in the amount of toner adhesion between the central portion and the end portion on the developing roller 5. On the other hand, when the metal roller is used, the toner adhesion amount at the center of the developing roller 5 is larger than that at the end, and the image density in this portion is increased, causing image density unevenness. .

This is due to the fact that the roller itself bends with the metal roller and the load at the center becomes small, and the toner thinning roller 27 composed of the elastic body 27b and the metal pipe 27c causes the bending. Probably because there is no. However, this is because the elastic body 27b located inside the metal pipe 27c when a load is applied to both ends of the shaft 27a.
Is deformed and the load on the metal pipe 27c becomes uniform, so that the smaller the hardness of the elastic body 27b, the more effective.

Specifically, if the hardness of the elastic body 27b is not smaller than the surface hardness of the developing roller 5 also made of an elastic body, the elastic body constituting the developing roller 5 is deformed and the elastic body 27b is hardly deformed. Therefore, the expected effect cannot be obtained. Therefore, the elastic body 27b needs to have a hardness smaller than that of the developing roller 5. It is clear that this condition can be easily achieved by forming the elastic body 27b with a soft foam.

Here, as shown in FIG. 3, a toner seal member 30 made of foam is provided on the outer periphery of both ends of the toner thinning roller 27 to prevent the toner from leaking out of the developing device.
Can be provided.

Here, when the elastic body 27b constituting the toner thinning roller 27 comes into contact with the toner seal member 30, the friction is large especially when the elastic body 27b is made of a foamed body. May deteriorate and toner leakage may occur over time. To prevent this, the elastic body 27b of the toner thinning roller 27 is used.
Mechanical interference between the toner seal member 30 and the toner seal member 30 may be eliminated.

That is, as shown in FIG.
Is shorter than the length of the metal pipe 27c in the axial direction, so that both ends of the elastic body 27b are inside the two ends of the metal pipe 27c by the width of the toner seal member 30. If the layering roller 27 is formed, the toner seal member 30 does not contact the elastic body 27b even when the toner seal member 30 is inserted in the direction of arrow A and pressed against the elastic member 27b.
It is possible to prevent toner leakage for a long time.

[0066]

As described above, according to the present invention, when a load is applied to both ends of the shaft, the elastic body located inside the rigid member is deformed, and the load on the rigid member becomes uniform, so that the toner thinning is achieved. Since the bending of the layering roller does not occur, the pressing force of the toner layering roller against the developing roller is made uniform, and the toner layer having a uniform thickness over the entire length of the developing roller is stably formed by the toner layering roller. An effective effect of being able to form is obtained.

As a result, an effective effect that a high quality image with a uniform density can be obtained is obtained.

Further, if the hardness of the elastic body constituting the toner thinning roller is made smaller than the hardness of the developing roller, the pressing force of the toner thinning roller against the developing roller is further uniformed, and the uniformity of the pressing force on the developing roller is improved. An effect is obtained that a toner layer having a small thickness can be stably formed by the toner thinning roller.

Further, by using a foam as the elastic body constituting the toner thinning roller, the elastic body can be easily made smaller than the hardness of the developing roller, and the pressing force of the toner thinning roller against the developing roller can be further increased. The effect is obtained that the toner layer which is uniform and has a uniform thickness on the developing roller can be stably formed by the toner thinning roller.

A toner seal member is provided on the outer periphery of both ends of the toner thinning roller, and both ends of the elastic body constituting the toner thinning roller are located inside both ends of the cylindrical rigid body. With this configuration, since the pressing force between the developing roller and the toner seal member does not act on the elastic body, it is possible to obtain an effective effect that it is possible to prevent toner leakage for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus using a non-magnetic one-component developing device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing in detail a toner thinning roller in the non-magnetic one-component developing device of FIG. 1;

FIG. 3 is a perspective view showing a main part of a non-magnetic one-component developing device according to another embodiment of the present invention.

FIG. 4 is a perspective view showing a toner thinning roller in the non-magnetic one-component developing device of FIG. 3;

FIG. 5 is a schematic diagram showing a configuration of an image forming apparatus using a conventional non-magnetic one-component developing device.

[Description of Signs] 5 Developing roller 6 Toner supply roller 27 Toner thinning roller 27a Shaft 27b Elastic body 27c Metal pipe (rigid member) 30 Toner seal member

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masakazu Aoki 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 2H077 AC04 AD06 AD14 AD17 AD22 CA12 EA14 FA22

Claims (4)

[Claims] A developing roller having a toner layer formed of a non-magnetic one-component developer formed on a surface thereof; a toner supply roller disposed in contact with the developing roller to supply toner to the developing roller; a shaft; And a rigid member provided on the outer periphery of the elastic body, and is provided in contact with the developing roller to form a toner layer having a predetermined thickness on the developing roller. And a non-magnetic one-component developing device comprising: 2. The non-magnetic one-component developing device according to claim 1, wherein the hardness of said elastic body is set smaller than the surface hardness of said developing roller. 3. The non-magnetic one-component developing device according to claim 1, wherein said elastic body is made of a foam. 4. A toner seal member for preventing toner from leaking is provided at both ends of the toner thinning roller, and both ends of the elastic body are located inside the rigid member. The non-magnetic one-component developing device according to claim 1, wherein the elastic body and the toner seal member do not contact each other.