JPH10247016A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device provided with a blade where the occurrence of defective image forming is prevented by removing toner welded on a surface without using abrasive material. SOLUTION: In the developing device 13, the blade 86 is formed of a material which easily wears for instance silicone rubber material. The blade 86 is worn, so that the toner welded on the blade 86 is removed. A spring 101 as a worn quantity compensating means is provided on the back surface 86f of the slidable contact part 86e of the blade 86. The blade 86 worn is displaced by the spring 101, so that the change of pressing force is suppressed. Thus, the defective image forming is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image formed on a photosensitive drum into a toner image in an image forming apparatus such as an electrostatic copying machine or a printer. In particular, it relates to a developing device using a non-magnetic one-component toner.

[0002]

2. Description of the Related Art Generally, a developing device using a non-magnetic one-component toner is a developing roller for bringing a toner layer into contact with a photosensitive drum in order to visualize an electrostatic latent image formed on the photosensitive drum as a toner image. And a blade for rubbing the peripheral surface of the developing roller with a predetermined pressure in order to form the toner supplied to the developing roller into a thin layer having a predetermined thickness.

For example, a blade is made of a glass plate,
The peripheral surface of the resin-made developing roller is rubbed with the plate surface while being pressed by the pressing means, and a thin layer of toner is formed on the peripheral surface of the developing roller. The blade is made of a material that can minimize abrasion when it rubs against the developing roller to which the toner has been supplied. The pressing means is set such that the plate surface of the blade at a predetermined position presses the peripheral surface of the developing roller with a predetermined force.

[0004]

By the way, toner is
In some cases, the heat is fused to the blade due to frictional heat generated when the blade is rubbed by the pressed blade, and remains on the blade surface as it is. With the blade to which the toner has been fused in this way, the layer thickness of the toner cannot be made uniform, resulting in poor image formation.

[0005] In some cases, an abrasive for shaving off the fused toner from the blade surface is mixed with the toner and used. However, there is a problem that the photosensitive drum is scraped by the abrasive. In order to prevent the color of the color toner from becoming cloudy, it is necessary to select the color of the abrasive.
In order to prevent these problems, there is also a demand for eliminating the need for using an abrasive.

Accordingly, an object of the present invention is to solve the above-mentioned technical problem based on a new idea, and to remove toner fused to a surface without using an abrasive to prevent occurrence of defective image formation. An object of the present invention is to provide a developing device having a blade which can prevent the developing device.

[0007]

According to a first aspect of the present invention, there is provided a developing device comprising: a developing device configured to reduce a layer thickness of a non-magnetic one-component toner supplied to a peripheral surface of a developing roller; In the developing device regulated by a predetermined portion of the blade to be pressed, at least a predetermined portion of the blade rubs the peripheral surface of the developing roller to which the toner is supplied so that the toner fused to the surface can be dropped. It is characterized by being made of a material that can be worn as a result.

According to this configuration, even when the toner is fused to the blade, the fused toner can be dropped off from the blade surface due to wear of the blade itself. It is possible to prevent image formation failure caused by the attached toner. In addition, since the abrasive for removing the fused toner does not need to be mixed with the toner, damage to the photosensitive drum and the like due to the above-mentioned abrasive can be prevented. The predetermined portion of the blade is a portion pressed against the peripheral surface of the developing roller.

Here, as a material that can be worn, a material that is softer than the developing roller and has low wear resistance can be used. As a material having low wear resistance, for example, there is silicone rubber. The developing device according to claim 2 is the developing device according to claim 1, wherein when the blade is worn, a change in a pressing force applied to the blade to be pressed is suppressed.
A wear amount compensating means for elastically pressing a back surface of a portion where the blade wears and displacing the back surface toward the developing roller with a stroke amount equal to the wear amount of the worn portion is further provided.

According to this structure, in addition to the effect of the first aspect of the present invention, even if the blade is worn, the blade is brought closer to the peripheral surface of the developing roller to reduce the pressing force of the blade against the developing roller. The toner layer thickness can be maintained satisfactorily. It is desirable that the change in the pressing force be suppressed to 0 to ± 10%. Further, since the blade can be pressed by the wear amount compensating means, it is not necessary to separately provide a configuration for pressing the blade. Therefore, the structure can be simplified.

According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, further comprising a regulating member for suppressing the bending of the blade. According to this configuration, in addition to the function of the invention according to claim 1 or 2, the following function is provided. In other words, a blade using a material that is generally easily worn is rich in flexibility and easy to bend. However, in the present invention, it is possible to prevent the blade from tending to bend in such a manner. The pressed state can be maintained, and as a result, a change in the layer thickness of the toner can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device according to an embodiment of the present invention will be described with reference to the accompanying drawings, taking a color printer provided with the developing device as an example. FIG. 1 is a schematic configuration diagram showing an internal cross section of a color printer A to which the developing device of the present embodiment is applied. This will be described with reference to FIG.

The color printer A includes four image forming units 10 for each color of black, magenta, cyan, and yellow arranged in a line along a sheet conveying path for conveying a sheet P in a straight line. Forming unit 10
Is a so-called tandem-type full-color printer that obtains a full-color image by sequentially superimposing and transferring the toner images of each color formed on each of the photosensitive drums 11 included in the above-described manner onto one sheet of paper P.

The color printer A is connected to an external device (not shown) such as a personal computer.
Image data is input from the connected external device.
In order to process the input image data, the color printer A includes a signal processing unit including a microcomputer and the like. In this signal processing unit, the color printer A decomposes the input image data into digital color image data representing the densities of black, magenta, cyan and yellow.

The color printer A transmits a laser beam from a laser light source (not shown) to a polygon mirror 21, a lens 22, a reflection mirror 23 to 23 in accordance with digital color image data separated into the above-described respective colors. 2
A laser beam scanning unit 20 provided for each of the above-described colors to obtain a predetermined light beam by scanning through the laser scanning unit 5 and the like, and a photosensitive drum for forming a latent image corresponding to the light from the laser scanning unit 20 11 and a developing device 13 for visualizing the electrostatic latent image formed on the photosensitive drum 11, the image forming units 10 provided for each color described above, Transport belt 46 for transporting P along a predetermined transport direction;
A transfer belt unit 40 including a transfer roller 50 provided opposite to each of the photosensitive drums 11 to transfer an image visualized on each of the photosensitive drums 11 to a sheet, and a toner image transferred to the sheet Unit 80 for heating and fixing the paper, a paper feed unit 91 at the preceding stage for feeding out the paper from the paper feed tray 3 and sending it to the transfer belt unit 40, and a fixing unit 8
The fixing unit 80 and the transfer belt unit 40 share the middle of the front and rear stages with a later-stage paper discharge unit 92 that discharges the paper fed from 0 to the discharge unit 18 formed on the upper surface of the main body. And a paper transport unit 90.

The image forming unit 10 includes the photosensitive drum 1
1, a charging charger 12, a developing device 13, and a cleaning device 14 are arranged in this order. The image forming unit 10 includes a charging charger 12
On the outer peripheral surface of the photosensitive drum 11 uniformly charged by
After irradiating a light beam from the laser scanning unit 20 to form a desired image to form an electrostatic latent image, the developing device 13 visualizes the electrostatic latent image into a toner image. The toner image visualized by each developing device 13 is transferred to a sheet P that is conveyed and passed by the conveying belt 46 between the photosensitive drum 11 and the transfer roller 50. Note that the residual toner on the photosensitive drum 11 is collected by the cleaning device 14.

The image forming unit 10, the laser scanning unit 20, and the transfer roller 50 are provided for each of black, magenta, cyan, and yellow. These components (in FIG. 1, the components for each color of black, magenta, cyan and yellow are indicated by reference numerals B, M, C and Y added to the reference symbols). In the order of yellow and yellow, they are arranged along the paper transport path formed by the transport belt 46 from the upstream side to the downstream side in the direction in which the paper P is transported (from right to left in FIG. 1). These units sequentially perform processing according to the image data for each color in synchronization with the transport timing of the paper P. For example, the laser scanning unit 20 irradiates a light beam corresponding to image data for each color to form a desired image on the photosensitive drum 11 to form an electrostatic latent image. The developing device 13 stores toner of each color, and develops the electrostatic latent image formed for each color into a toner image of each color as described above. Note that the processing for each color is substantially the same for each color, and therefore, a description of each color will be omitted below unless otherwise specified.

Next, the operation of the color printer A will be described. First, the paper supply unit 91 of the paper transport unit 90
Is fed from the paper feed tray 3 by the rotation of the paper feed roller 5, and is conveyed to the registration roller 7 through the conveyance path 4.
After temporarily stopping the sheet P, the registration roller 7 sends the sheet P to the transport belt 46 in synchronization with the toner image forming operation in the black image forming unit 10.

The sheet P sent to the conveyor belt 46 is
The toner is conveyed by the conveyance belt 46, and first, the black toner image is transferred by the black image forming unit 10. The paper P on which the black toner image is transferred
Is continuously transported by the transport belt 46, reaches the magenta image forming unit 10, and is transferred with the magenta toner image superimposed thereon. Thereafter, the paper P is transferred with toner images of cyan and yellow superimposed on each other, and then conveyed to the fixing unit 80.

The fixing unit 80 preheats the sheet P with the heat fixing belt 83 and then heats and presses the sheet P with the heat fixing belt 83 and the lower roller 85 to fix the toner on the sheet. Then, the paper discharge unit 92 of the paper transport unit 90
Discharges the sheet P on which the image is fixed to the discharge unit 18.

The developing device according to the present invention includes the developing device 13 described above.
And can be applied to any developing device 13 of each image forming unit 10. Further, the present invention is not limited to a tandem type full-color printer, and can be preferably applied to a developing device using a non-magnetic one-component toner. The details will be described below.

The developing device 13 is for developing the electrostatic latent image formed on the photosensitive drum 11 with a non-magnetic one-component toner. The developing device 13 includes a developing roller 15 having at least a surface formed of an elastic body such as urethane resin and supplying toner by contacting the photosensitive drum 11;
While being pressed by the developing roller 15, the developing roller 15
A sub-roller 16 rotating in the same direction as above to assist in the supply of toner to the developing roller 15, a blade 86 pressed against the developing roller 15, a stirring means 87 rotating to stir the toner in the developing device 13, And a developing container 88 containing these members and containing a non-magnetic one-component toner.

In the developing device 13, when the developing roller 15, the sub-roller 16 and the agitating means 87 are respectively rotated in predetermined directions, the toner in the developing container 88 is agitated and the developing roller 15 and the sub-roller 16 Due to the friction, the toner is frictionally charged and adheres to the surface of the sub-roller 16 and then adheres to the peripheral surface of the developing roller 15. Next, the toner adhered to the peripheral surface of the developing roller 15 is removed by the peripheral surface of the developing roller 15 and the blade 8 pressed against the peripheral surface.
6, the thickness of the toner layer adhering to the peripheral surface of the developing roller 15 is controlled to a constant layer thickness, and the toner forming the toner layer is rubbed with the blade 86 by rubbing. It is additionally strongly charged (arrows T1 to T1 in FIG. 2).
T3). Thereafter, the toner on the developing roller 15 is pressed against the photosensitive drum 11 at the nip position with the photosensitive drum 11 and selectively adheres according to the potential difference of the electrostatic latent image, so that the electrostatic latent image is formed. It is visualized as a toner image.

FIG. 2 is an enlarged front view of a main part of the schematic configuration of the developing device of FIG. A blade 86 in contact with the peripheral surface of the developing roller 15 around the developing roller 15, a spring 101 for pressing the blade 86, a spring 101 and the blade 86
And a blade holder 10 fixed to the developing container 88
2 are provided. The blade holder 102 has a recess for accommodating the blade 86 and the spring 101. The lower part of the recess is an entrance, and the upper part of the recess is closed. A portion from the center to the upper end of the blade 86 is accommodated near the entrance of the concave portion of the blade holder 102, and the blade 86 is held so as to be slidable along the radial direction of the developing roller 15. Further, a regulating member 102a for suppressing the bending of the blade 86 is provided at the entrance of the concave portion of the blade holder 102. Further, as described above, the blade 86 slidable in the radial direction of the developing roller 15 is pressed along the radial direction (that is, along the direction in which the wear of the blade 86 proceeds). The spring 101 feeds the blade 86 toward the developing roller 15 as the wear of the blade 86 progresses.
Is housed.

The spring 101 functions as a pressing means for pressing the blade 86 against the developing roller 15 with a predetermined pressing force. The spring 101 also functions as wear amount compensating means as described later, and serves as both the wear amount compensating means and the pressing means. The pressing means is not limited to the spring 101, but may be an elastic member such as a rubber material. The blade 86 is a plate-like member extending in the radial direction of the developing roller 15. The blade 86 has a substantially plate-shaped main portion and a sliding contact portion 86 e formed integrally with the main portion and pressed against the peripheral surface of the developing roller 15 as a predetermined portion. Blade 86
Is pressed by the spring 101 on the back surface 86f of the sliding contact portion 86e. The portion of the blade 86 pressed by the spring 101 and the sliding contact portion 86e of the blade 86
They are arranged side by side on a line extending in the radial direction of the developing roller 15. The direction in which the blade 86 extends is preferably set in a range of 0 degree to ± 10 degrees with respect to the radial direction of the developing roller 15.

The blade 86 is made of a material that can be worn by rubbing the peripheral surface of the developing roller 15 to which the toner is supplied so that the toner fused to the surface of the sliding contact portion 86e can be dropped. I have. Here, as the material that can be worn, a material that is softer than the developing roller 15 made of urethane resin and has low wear resistance, for example, silicone rubber is preferable.

The sliding contact portion 86e is formed in a flat shape at the end of the blade 86 and includes an edge of the flat surface, and this edge also contacts the peripheral surface of the developing roller 15. As described above, since the sliding contact portion 86e is a plane including the edge, a change in the contact area when the blade 86 is worn can be relatively reduced,
As a result, a change in the pressing force of the blade 86 can be reduced. On the other hand, when the sliding contact portion 86e has an edge shape, the change in the contact area when the blade 86 is worn is relatively large, and as a result, the change in the pressing force of the blade 86 is large.

The blade 86 made of a material that can be worn in this way can remove the fused toner. That is, when the blade 86 is rubbed on the peripheral surface of the developing roller 15, a frictional force acts, so that the surface of the blade 86 is scraped off, and the blade 86 is eventually worn.
It is assumed that the toner is fused to the surface of the blade 86. The surface of the blade 86 to which the toner has been fused (toner-fused portion) has a projecting shape with respect to the surface of the blade 86 to which toner has not been fused (the toner non-fused portion). The above-mentioned frictional force acts strongly on the projection-like toner fused portion. As a result, the fused toner portion is quickly scraped off together with the fused toner.

By the way, when the wear amount of the blade 86 increases, the pressing force to the developing roller 15 changes, and as a result, it is assumed that it may be difficult to regulate the toner layer thickness to be constant. . Therefore, in the present embodiment, a wear amount compensating means is provided. The above-mentioned spring 101 displaces the blade 86 toward the developing roller 15 so as to suppress a change in the pressing force applied to the pressed blade 86 when the blade 86 is worn.
It has.

The spring 101 is composed of a plurality of compression coil springs, and is arranged in a compressed state between the recess of the blade holder 102 and the blade 86 so that the compressible direction extends along the radial direction of the developing roller 15. ing. Each spring 101
Are arranged side by side in the axial direction of the developing roller 15 (perpendicular to the paper surface). The spring 101 resiliently holds the blade 86
Presses against the back surface 86f of the sliding contact portion 86e of the blade 86, which is the portion to be worn. Thus, when the blade 86 is worn, the sliding contact portion 86e of the blade 86 maintains contact with the developing roller 15, while the back surface 86f of the sliding contact portion 86e of the blade 86 reduces the amount of wear of the sliding contact portion 86e. It can be displaced by an equal stroke amount.

Further, since the spring 101 is elastically pressed, a pressing force can be generated even if the blade 86 is worn. The spring 101 presses the back surface 86f of the sliding contact portion 86e so as to suppress a change in the pressing force applied to the blade 86 when the blade 86 is worn. For example, the back surface 86 of the sliding portion 86e is worn due to wear.
Even if f is displaced, the pressing force applied to the sliding contact portion 86e may not change. When the pressing force changes, the change in the pressing force is desirably suppressed to 0 to ± 10%. To this end, the spring constant of the spring 101 may be set as follows. For example, when an assumed wear amount M, a change amount dF of the pressing force allowed for the wear amount M, and a spring constant K, K ≦ (dF / M) may be satisfied. Further, in order to obtain the required predetermined pressing force F, the number of springs and the amount of deformation of the springs may be set as appropriate.

As described above, when the blade 86 is worn, the spring 101 of the wear amount compensating means can press the blade 86 while suppressing the change in the pressing force. Therefore, the blade 86 can suppress the change in the toner layer thickness. In addition, the layer thickness of the toner can be maintained satisfactorily. In particular, the blade 86 is
Since the back surface 86f of the sliding contact portion 86e is pressed at 01, the wear portion is directly pressed, and as a result, the change in the pressing force due to abrasion can be surely suppressed as compared with the case where it is indirectly pressed. More preferred.

The wear amount compensating means is not limited to the spring 101 described above. For example, instead of the spring 101, an elastic member such as a rubber material may be used. By the way, a soft member such as the blade 86 is easily deformed when pressed by the developing roller 15. In particular, in the case of displaceably supporting as described above, deformation such as bending is likely to occur. When such deformation occurs, the pressing force changes, and as a result, the thickness of the toner layer may not be regulated to be constant, which is not preferable. Therefore, in the present embodiment, the regulating member 102a is provided.

The regulating member 102a is provided with the blade holder 10
2 extends from the entrance of the concave portion to the vicinity of the sliding contact portion 86e along the blade 86. When the blade 86 is moved along, the bending of the blade 86 from the entrance of the concave portion of the blade holder 102 to the sliding contact portion 86e. The deformation of the blade 86 can be suppressed in the tangential direction of the peripheral surface of the developing roller 15.

The regulating member 102a is provided with the blade holder 10
Since it is formed integrally with the hard member, the deformation of itself can be prevented. Also, the regulating member 102a
Is provided at one of the peripheral edges of the entrance of the concave portion of the blade holder 102, for example, on the side where the blade 86 bends when the blade 86 rubs against the developing roller 15 (the side in the rotational direction with respect to the developing roller 15). The blade holder 1
The reason why the regulating member is not provided on the other side of the periphery of the entrance of the concave portion 02 is that if toner enters between the regulating member provided here and the blade 86, the blade 86 may not be able to be displaced. . Further, the regulating member 102a may be provided separately from the blade holder 102, or may be provided on a member such as the developing container 88.

As described above, the regulating member 102a can suppress the bending of the blade 86, and
6, the pressure applied to the developing roller 15 can be maintained, and as a result, the layer thickness of the toner can be favorably maintained. This is because, when the sliding contact portion 86e of the blade 86 contacts so as to include the edge of the surface, if the blade 86 is tilted due to bending or the like, the blade 86 is moved only in the vicinity of the edge of the surface of the sliding contact portion 86e. Will come into contact with each other. When the wear of the blade 86 progresses, the sliding contact portion 86e wears in a chamfered shape, so that the area of the sliding contact portion 86e increases with the progress of the wear, and as a result, it is assumed that the pressure of the blade 86 decreases. This is because that.

As described above, according to the present embodiment, the blade 86 made of a material that can be worn so that the toner fused to the surface thereof can be dropped is worn by itself, so that the fused toner Can be dropped from the surface of the blade 86, and as a result, it is possible to prevent image formation defects caused by toner fused to the surface of the blade 86. Further, since it is not necessary to mix the abrasive with the toner in order to remove the fused toner, it is possible to prevent the abrasive from damaging a member such as the photosensitive drum 11 which is in contact with the toner.

In particular, since the blade 86 extends in the radial direction of the developing roller 15, in other words, in the direction in which the wear of the blade 86 proceeds, the blade 86 itself can compensate for the wear for a long time, and as a result, the fusion The removed toner can be dropped for a long period of time. The wear amount compensating means can maintain the pressing force of the blade 86 against the developing roller 15 by bringing the blade 86 close to the peripheral surface of the developing roller 15 when the blade 86 is worn, and as a result, the toner layer thickness can be improved. Can be maintained.

Further, the regulating member 102a can prevent the blade 86, which tends to bend, from bending, so that a desired pressing state of the blade 86 against the peripheral surface of the developing roller 15 can be maintained. As a result, the toner layer thickness can be reduced. Change can be prevented. Also, the spring 101 of the wear amount compensating means includes a blade 86.
, It is not necessary to separately provide a configuration for pressing the blade 86, so that the structure can be simplified.

As another embodiment of the present invention,
For example, as shown in the schematic configuration front view of FIG. 3, a configuration in which the above-described restricting member has a different configuration may be considered. That is, the blade 86 is a plate-like member extending in a tangential direction on the peripheral surface of the developing roller 15. It is preferable that the direction in which the blade 86 extends is 0 degrees to ± 10 degrees with respect to the tangential direction described above. On the back surface 86f of the sliding portion 86e of the blade 86,
An intervening member 103 as a regulating member for suppressing the bending of the blade 86 is arranged, and the spring 10 is
1 presses the blade 86. The interposition member 103 is
It is made of a rigid member having rigidity, and transmits the pressing force of the spring 101 to the blade 86 uniformly while suppressing the radial bending of the blade 86 of the developing roller 15. The blade 86 is supported at one end thereof by a developing container 88 so as to be rotatable and displaceable.
f is arranged, and can rotate with respect to the center of rotation of the blade 86. In addition, the above-mentioned one end of the blade 86 is
It may be fixed to the developing container 88 via a flexible member. According to this configuration, the intervening member 103 is
6 is provided along the back surface of the worn portion, so that the direction in which the bending is suppressed and the direction in which the blade is pressed can be made to coincide with each other. The pressing force applied to the blade 86 biased by the spring 101 can be made uniform. As a result, the change in the pressing force received by the blade 86 can be reduced, so that the toner layer thickness can be regulated to a constant value.

In the present embodiment, the blade 86
Was made entirely of wearable material,
It is not limited to this. At least, the surface of the sliding contact portion 86e of the blade 86 as a predetermined portion pressed against the peripheral surface of the developing roller 15 may be formed of the above-mentioned wearable material. For example, it is conceivable that the main body is formed of a rigid hard material. In this case, the deformation of the blade 86 can be prevented.

In addition, various design changes can be made without changing the gist of the present invention.

[0043]

According to the first aspect of the present invention, even if the toner is fused to the blade surface, the fused toner can be dropped off by abrasion of the blade itself. As a result, the fused toner can be removed. Can be prevented from being caused by image formation failure. Further, since it is not necessary to mix an abrasive for removing the fused toner with the toner, it is possible to prevent the members from being damaged due to the abrasive.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, even if the blade is worn, the back surface of the worn portion is brought closer to the developing roller by the wear amount compensating means. Therefore, the pressing force of the blade can be maintained, and as a result, the layer thickness of the toner can be favorably maintained. Further, since the blade can be pressed by the wear amount compensating means, there is no need to separately provide a configuration for pressing the blade, and as a result, the structure can be simplified.

According to the third aspect of the present invention, the following effects are obtained in addition to the effects of the first or second aspect of the present invention. In other words, a blade using a material that is generally easily worn is rich in flexibility and easy to bend. However, in the present invention, it is possible to prevent the blade from tending to bend in such a manner. The pressed state can be maintained, and as a result, a change in the layer thickness of the toner can be prevented.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a schematic configuration of a color printer to which a developing device according to an embodiment of the present invention is applied.

FIG. 2 is an enlarged front view of a main part of a schematic configuration of the developing device of FIG. 1;

FIG. 3 is an enlarged front view of a main part of a schematic configuration of a developing device according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 13 developing device 15 developing roller 86 blade 86e sliding contact portion (wearing portion) 86f back surface 101 spring (wear amount compensating means) 102a regulating member 103 intervening member (regulating member)

Claims (3)

[Claims] 1. A developing device for regulating a layer thickness of a non-magnetic one-component toner supplied to a peripheral surface of a developing roller by a predetermined portion of a blade pressed against the peripheral surface, wherein at least the predetermined portion of the blade is A developing device made of a material that can be worn by rubbing the peripheral surface of the developing roller to which the toner is supplied so that the toner fused to the surface can be dropped. 2. The developing device according to claim 1, wherein when the blade is worn, the back surface of the worn portion is elastically pressed so as to suppress a change in the pressing force applied to the pressed blade. And a wear amount compensating means for displacing the rear surface toward the developing roller by a stroke amount equal to the wear amount of the worn portion. 3. The developing device according to claim 1, further comprising a regulating member that suppresses deflection of the blade.