JPH03114086A - Developing device - Google Patents

Abstract

PURPOSE:To enable a thin good toner layer to be formed and maintained for a long time by forming the top of a toner layer regulating member into a continuous face comprising a curved face and a flat face and pressing a toner carrier with the flat face. CONSTITUTION:The top of the toner layer regulating member 2b to be pressed to the toner carrier 2 is formed into the continuous face comprising the curved face and the almost flat face and the carrier 2 is pressed with a part of flat face, thus permitting the toner layer thickness to be regulated by low pressure by pressing the end of the member 2b, the driving power of the carrier 2 to be reduced, and the toner not to firmly attach to the member 2b for a long operation time.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a developing device that visualizes a latent image in an electrophotographic device or an electrostatic recording device, and more specifically relates to a developing device that visualizes a latent image in an electrophotographic device or an electrostatic recording device. The present invention relates to a developing device having means for forming a thin toner layer on a body and performing development using the thinned toner layer.

(Prior art) In a developing device that forms a thin toner layer on a toner carrier and develops (visualizes) a latent image, regulating the toner layer thickness is an extremely important point that determines the quality of the image. becomes.

The following two types of means are conventionally known as the toner layer thickness regulating means.

(2) Press the belly of the plate-shaped toner layer thickness regulating member against the toner carrier.

(2) Press the tip of the plate-shaped toner layer thickness regulating member against the toner carrier.

The method or means of pressing the surface of the plate-shaped toner layer thickness regulating member film (3) is disclosed in, for example, Japanese Patent Publication No. 16738/1983, Japanese Patent Application Laid-Open No. 165866/1982, and Japanese Patent Application Laid-open No. 73649/1989.
No. 61-138987, U.S. Patent No. 4
, 521,098, etc., by pressing the bottom surface of a plate-like regulating member made of an elastic body against a toner carrier, a thin toner layer with a nearly uniform thickness can be formed and at the same time. The toner particles are reliably triboelectrified, making it possible to obtain the required visible image.

On the other hand, the method (3) of pressing the tip of the plate-shaped toner layer thickness regulating member is disclosed in Japanese Patent Publication No. 51-36070 and Japanese Patent Application Laid-Open No. 53-1989.
Publication No. 23638. Japanese Patent Application Laid-Open No. 116559/1983,
Japanese Patent Publication No. 60-15068, Japanese Patent Publication No. 82-9555
9, JP-A-62-98981, JP-A-62-98981
This is disclosed in, for example, Japanese Patent No. 113178. These known means for pressing the tip are further classified into the following three types.

(I) A method of pressing a tip processed into a cylindrical shape (Japanese Patent Publication No. 38070/1983).

(II) Method of pressing the sharp tip (Japanese Unexamined Patent Publication No. 53-23638, etc.).

(m) A method of pressing a flat tip (Japanese Unexamined Patent Publication No. 62-95559, etc.).

According to these methods, the desired toner thin layer can be formed with a relatively low pressing force, so that there is no possibility that the donor will stick to the toner carrier or regulating member, which is related to the above method of pressing the bottom surface. This problem can be avoided. However, these methods of pressing the ends also have the following problems. First, when pressing the sharp tip (n), the contact area between the toner carrier and the regulating member is extremely small and the pressure is concentrated, so the pressure setting for the entire regulating member must be strictly controlled. . In addition, there have been other drawbacks, such as a slight defect in processing accuracy at the tip leading to non-uniformity of the toner layer, and in general, the thickness of the toner layer is excessively thin, resulting in poor quality. In the method (m), the end cross section of the plate-shaped regulating member is pressed against the toner carrier, so the problem related to the method (II) does not occur under normal conditions, but if the regulating member is installed slightly Due to such fluctuations, the edge of the end cross section may come into contact with the toner carrier, and a problem similar to that in case (II) may occur. On the other hand, in method (1), there are no sharp edges at the end of the regulating member, so even if the mounting condition of the regulating member changes slightly, problems like those in cases (II) and (III) will occur. This makes manufacturing and assembly of the device extremely easy. In addition, by making the edges curved, it is possible to obtain an intermediate effect between the method of pressing the inner surface and the method of pressing the sharp edges, making it possible to thin the toner layer with relatively low pressure. Reliable charging of toner particles can be achieved.

(Problem to be Solved by the Invention) However, in these developing devices that press the bottom surface of the plate-shaped regulating member described in (2) above, the wedge-shaped space formed between the regulating member and the toner carrier is Since toner particles tend to stay and subsequent toner particles try to push them out, the regulating member must be pressed against the toner carrier with a relatively high pressure to form the desired toner thin layer (f). As a result, problems such as the toner sticking to the toner carrier and the regulating member and the increased force required to drive the toner carrier have arisen.

On the other hand, among the means for pressing the end of the plate-shaped regulating member described in (2) above, the most practical method (I) of pressing the tip processed into a cylindrical surface also has the following drawbacks. has become clear. For example, Japanese Patent Publication No. 51-88070 discloses that a regulating member made of polytetrafluoroethylene, polyformaldehyde (trade name: Delrin), etc., and whose end face is processed into a cylindrical shape is suitable. However, according to additional tests conducted by the inventor of the present invention, the processing accuracy of the regulating member, especially warping and waviness in the longitudinal direction, leads to non-uniformity of the toner layer. It has been found that there are drawbacks such as the inability to absorb defects in processing accuracy and processing accuracy, which tends to cause non-uniformity of the toner layer, and the difficulty in processing to obtain a highly accurate cylindrical surface.

Further, due to long-term use, toner tends to stick to the surface of the regulating member, resulting in non-uniformity of the toner layer.

The present invention has been made in response to the above circumstances, and can regulate the toner layer thickness and triboelectrically charge toner particles with a relatively low pressing force, and does not require high processing precision or assembly precision.
It is an object of the present invention to provide a developing device capable of forming and maintaining a good toner thin layer over a long period of time.

[Structure of the Invention] (Means for Solving the Problem) The present invention includes a toner carrier disposed close to a latent image carrier that forms and holds a latent image, and a toner carrier that is in contact with the toner carrier and placed on the toner carrier. and a toner layer thickness regulating member for forming a thin toner layer on the surface of the developing device, and for developing the latent image with the toner formed in the thin layer, a first aspect of the present invention is characterized in that the toner layer thickness regulating member has a tip end thereof. The second invention provides an elastic pressing means for the toner layer thickness regulating member, which is formed of a continuous surface of a curved surface and a flat surface, and configured to press this flat portion against the toner carrier. The main feature of the present invention is that at least one of the toner layer thickness regulating members is configured to press the center of the toner layer thickness regulating member toward the upstream side in the moving direction of the toner carrier, thereby solving the above problem.

(Function) Since the present invention is of a type in which the end portion of the toner layer thickness regulating member is pressed, compared to the case where the belly surface of the plate-like elastic body is pressed,
The toner layer thickness can be regulated at a pressure lower than °.

Therefore, a small driving force for the toner carrier is sufficient, and toner does not stick to the regulating member even during long-term use. Additionally, compared to pressing on sharp edges,
Since the pressure is not concentrated in a small area, the state of the formed toner layer will not change significantly even if the pressure, mounting, and other condition settings vary somewhat. Furthermore, for the same reason, the requirements for machining accuracy of the end portions can be relatively moderate. However, in the conventional method of pressing the end plane,
Due to slight variations in various conditions, the edges of the end plane may come into contact with the toner carrier, causing uneven toner layer thickness, but in the case of the present invention, the curved surface is continuous with the plane. , the occurrence of such problems is completely eliminated.

On the other hand, according to the second invention, it is possible to prevent the toner layer from becoming uneven due to the bending of the toner layer thickness regulating member due to the movement of the toner carrier, and to press the end portion of the toner layer thickness regulating member. This method is effective for forming a toner layer.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of essential parts showing an example of the configuration of a developing device according to the present invention. A toner layer thickness regulating member 2b that regulates the supplied toner to form a uniform toner layer on the developing roller 2, and a toner layer thickness regulating member 2b that faces the developing roller 2 that rotates while carrying the toner layer. A photoreceptor drum 3 on which an electrostatic latent image formed and carried on the surface is visualized; a glue cover blade 2c1 for collecting the toner remaining after development into the toner container 1; and agitation of the toner 1a in the toner container 1. The toner layer thickness regulating member 2b is composed of a spring 2d that presses the toner layer thickness regulating member 2b against the developing roller 2 with a constant load.

In FIG. 1, numeral 4 is a charger for applying a required electrostatic charge to the photoreceptor drum 3 as a latent image holder, 5 is an exposure means for forming a required electrostatic latent image, and 6 is the aforementioned A transfer device 7 transfers a visualized electrostatic latent image on a photosensitive drum 3 as a latent image holder onto a support such as paper, and 7 is a developing roller 2 and a toner supply roller 2a. A DC power source supplies the required current, and 8 is a protective resistor.

Next, the components of the developing device having the above configuration will be explained. The developing roller 2 is made of metal such as aluminum or stainless steel, phenol resin, acrylic resin, urethane resin,
Hard or soft resins such as fluororesin, polyamide resin, silicone resin, melamine resin, polystyrene resin, polyester resin, and epoxy resin, or composites of these resins can be used, and magnetic poles are arranged inside. A magnetic roller or the like may also be used. In this embodiment, a non-magnetic (or non-magnetized) developing roller 2 having elasticity and conductivity will be exemplified.

The developing roller 2 having elasticity and conductivity includes a conductive rubber layer around the shaft, such as urethane rubber, silicone rubber, or ethylene propylene rubber.

A rubber such as NBR, chloroprene rubber, butyl rubber, etc. that has a resistance value of less than 1.5 XIO'Ω・G by dispersing conductive carbon particles, metal particles, metal fibers, etc., or The surface of the roller is coated with silicone resin, urethane resin, fluororesin, etc., the surface of a high-resistance or insulating rubber roller is coated with conductive resin, or semi-conductive (1,5XI
A conductive layer with a hardness of less than O'Ω・M) provided on the surface of a rubber roller is preferable, but here we particularly use a conductive layer with a hardness of 30 degrees (
A conductive urethane paint was applied to the surface of an EPDM rubber roller (JISA type), and an elastic conductive roller was adjusted so that the resistance between the metal shaft and the coating surface was less than 1.5 XIO'Ω. . Here, the outer diameter of the metal shaft was 8 mm, the outer diameter of the rubber roller was 1811111%, and the thickness of the conductive urethane paint was 20 to 200 μm.

As a method for developing a latent image, there is a method in which the latent image surface and the surface of the developing roller 2 are kept in a non-contact state, and development is carried out by making the toner particles 1a fly by a developing electric field, and a method in which the toner particles 1a are caused to fly by a developing electric field, and a method in which the two are brought into contact and transferred or slid. There is a method of developing by forming a direct current electric field between the two, and a method of developing by forming an alternating current electric field between the two. In the case of the apparatus of the present invention, any method can be applied, but in this embodiment, a method in which the developing roller 2 is brought into contact with the latent image surface is adopted.

Further, the toner layer thickness regulating member 2b is made of a plate-like polymer material having a rubber hardness of 30 degrees to 100 degrees (JI SA type) and whose tip is processed to have a cylindrical surface or a continuous surface of a curved surface and a flat surface. , the flat surface of the tip is in contact with the surface of the developing roller 2 by the pressing force of the spring 2b. Regulation member 2
The fact that the cross-sectional tip of b has a continuous shape of a circular arc or a curved line and a straight line is that it has an intermediate effect between the effect when pressing the antinode surface and the effect when pressing a sharp edge, as described in the section of the effect above. It is possible to form a desired toner thin layer with a relatively low pressing force, and to reliably triboelectrically charge toner particles. Furthermore, it is possible to prevent fog from occurring immediately after toner replenishment, which tends to occur when only the cylindrical surface is pressed or when the edges are pressed. Furthermore, it is possible to prevent the toner layer from becoming non-uniform due to edges when the end shape is configured only by a flat surface.

Therefore, good results can be obtained when the radius of curvature of the cylindrical surface or curved surface at the tip of the toner layer thickness regulating member 2b is between 0.3 aua and 15 mm, preferably between 0.5 mm and 8 mm. In addition, the length of the plane of the tip (the length of the straight line in the cross section) is 0.6 mm to 10 m, preferably 1 mm to 8 m.
Good results are obtained when m. In other words, when the radius of curvature of the cylindrical surface or curved surface is less than 0.3 mm, the toner layer is likely to become uneven due to the edges when the end shape is composed of only flat surfaces. This is because there are some problems that occur when pressing, and when the length of the flat part is less than 1 mm, problems similar to those caused when pressing a sharp edge or fogging that occurs immediately after toner replenishment occur. There are things to do,
This is because if it exceeds 10 mm, some problems will occur when pressing the antral surface.

Note that the surface roughness of the tip end surface of the toner layer thickness regulating member 2b has a large effect on the uniformity of the toner layer. JIS standard 80
As a result of investigating the correlation between surface roughness and image uniformity using the ten-point average roughness Rz and the maximum height Rl1laX among the surface roughness indications specified in 601, it was found that the regulating member 2b
At least the developing roller 2 of the end plane or end face
The surface roughness of the part that comes into contact with is 10 μmRz or less. czmR+++ax or less, preferably 5μmRz
It has been found that a toner layer with substantially no unevenness in thickness can be obtained when the toner layer is below 10 μHRmax, and an image with good uniform density can be obtained. When it exceeds 10 μmRz or 30 μlRmaw, significant thickness unevenness occurs in the toner layer, and there is a tendency for streak-like density unevenness to occur in the image.

In the developing device according to the present invention, flexibility of the regulating member 2b is extremely important in forming a uniform toner layer. If a material with a measured value of more than 100 degrees using a type A rubber hardness meter specified in JIS 6301 is used, it tends to be difficult to form a uniform toner layer with low pressure. In other words, the developing roller 2 and the toner layer thickness regulating member 2
There is a practical limit to the processing accuracy of b, and in order to absorb these unavoidable accuracy defects, the regulating member 2b must be pressed against the developing roller 2 with strong pressure. On the other hand, if the hardness of the regulating member 2b is less than 30 degrees, the tip may curl or become excessively deformed due to contact with the developing roller 2 or the pressure of the toner aggregate, resulting in an uneven toner layer. .

Using materials within the range of 30 degrees to 100 degrees, preferably 50 degrees to 85 degrees, maintains a uniform thickness of the toner layer by a moderate deformation effect.

In connection with the above deformation problem, etc., the toner layer thickness regulating member 2b
There are appropriate values for the plate thickness and free length as an elastic plate. The plate thickness is preferably in the range of 0.5 mm to 15 mm, and the free length, ie, the distance from the end of the support body 2C of the regulating member 2b to the free end, is preferably longer than the plate thickness. Plate thickness is 0.
When it is less than 5 mm, it is difficult to manufacture it accurately by molding, and when it exceeds 15 mm, the free length must be set long in order to obtain sufficient flexibility as the regulating member 2b, and the device becomes larger. Problems such as storage may occur.

In FIG. 1, the tip shape of the regulating member 2b is a continuous surface of a cylindrical surface and a plane from the upstream side, but other shapes as shown in cross section in FIGS. 2 and 3 may also be applied. Second
In the case of the shape shown in the figure, there is no edge at the end, so installation is easy, and in the case of the shape shown in Fig. 3, the upstream side of the surface of the developing roller 2 and the regulating member 2b hold a relatively large amount of toner. In order to form a space 9 in which the inner surface of the regulating member 2b is pressed, an effect similar to the toner supply effect obtained when pressing the inner surface of the regulating member 2b, that is, even when a large amount of toner is consumed, toner is quickly supplied to the surface of the roller 2. The effect that is supplied is obtained.

The regulating member 2b is required to have a function of triboelectrically charging the toner particles 1a to a predetermined polarity in addition to regulating the toner layer thickness. Therefore, as the material constituting the regulating member 2b, it is necessary to select a material that is easily charged to a polarity opposite to that of the toner particles in the well-known triboelectrification order.

Therefore, when the toner particles 1a are negatively charged, silicon rubber, formalin resin, PMMA, polyamide,
Melamine resin, polyurethane rubber, polyurethane sponge, etc. are used. On the other hand, when toner particles 1a are positively charged, fluororesin, polyethylene, acrylonitrile, natural rubber, epoxy resin, nitrile rubber, etc. are suitable. However, if a dye or the like is mixed into these materials to control the triboelectric charging properties, it is also possible to impart the opposite charging properties. Another characteristic required of the material constituting the regulating member 2b is that toner does not stick to the regulating member 2b even after long-term use. Such toner adhesion causes non-uniformity of the formed toner layer and also causes insufficient charging of the toner.

According to detailed experiments by the present inventors, among the above materials,
It has been found that those containing silicone rubber or urethane rubber as the main component give the best results for this purpose. In particular, because of its releasability, silicone rubber did not cause any toner sticking even when used for an extremely long period of time (approximately 10,000 cycles of printing process). However, it is preferable that these rubbers do not contain additives such as migratory plasticizers, vulcanizing agents, and anti-aging agents, or even if they are mixed, the amount thereof is extremely small. That is, it is extremely important to select a material that does not contaminate the toner material, the developing roller 2, and even the photoreceptor 3 due to the precipitation phenomenon of contained substances called bleed or bloom.

When using silicone rubber, it is also necessary to pay attention to its wear resistance.

In other words, since silicone rubber is generally inferior to other rubber materials in terms of wear resistance, it is necessary to use one that has been improved by adding fillers or the like. According to experiments conducted by the present inventors, when the contact area between the regulating member 2b and the developing roller 2 becomes 5 times or more compared to the initial state due to wear, the state of the toner layer, especially the thickness of the toner layer, changes unfavorably. . However, such a phenomenon was likely to occur when the edges or curved surfaces of the ends were brought into contact, but in the case of the present invention, 5
It does not double or more, and the lifespan can be significantly extended.

By using the regulating member 2b made of the material and structure described in detail above, it is possible to easily form a thin toner layer with an extremely uniform thickness over a long period of time, but it is desirable to pay attention to one more thing. That is, the toner layer may easily become non-uniform depending on the method of supporting and suppressing when pressing the end of the plate-like regulating member 2b. Such a phenomenon occurs because the regulating member 2b is an elastic body and is deflected by the movement of the toner carrier 2, resulting in uneven pressure and contact with the toner carrier 2. This phenomenon will be explained with reference to FIG. FIG. 4 shows the relationship between the toner carrier (developing roller) 2, the regulating member 2b, and the supporting member 2e that supports the regulating member 2b, which are among the components of the developing device.
FIG. 3 is a plan view of the developing device seen from above. In this configuration, the regulating member 2b is moved in the vertical direction (in the paper) by the supporting member 2e.
It is supported so that it can move vertically (perpendicular to the plane of the paper),
It is elastically pressed against the toner carrier 2 by a spring or the like. In this state, when the toner carrier 2 moves in the direction of the arrow, the regulating member 2b bends in a curve similar to that when a heavy distributed load is applied to the support beams, as shown by the broken line. Therefore, the pressure and contact with the toner carrier 2 become uneven, resulting in an uneven toner layer. In order to prevent this phenomenon, there is a method of increasing the rigidity of the regulating member 2b, but this does not necessarily eliminate deflection and is expensive.

As a relatively inexpensive means, as shown in FIG. 5, all the above problems can be solved by inserting and disposing the core member IO inside the regulating member 2b during so-called insert molding. can do.

The core member 10 is preferably a metal plate with a thickness of 0.1 mm to 3 mm, and the length from the tip of the core member IO to the tip of the regulating member 2b, that is, the free length of the regulating member 2b, is preferably 1 mm to 10 mm. If the length of the regulating member 2b is equal to or longer than the length of the regulating member 2b, the elasticity of the regulating member 2b will be utilized and a more uniform toner layer type will be possible.

A problem to be noted when molding and processing the elastic regulating member 2b is the problem of "sink marks" at both ends. The term "sink" as used herein means that the length C shown in FIG. 5 is different between both ends and the center in the longitudinal direction. -As an example! -10mm, tm3mm, tip radius 1.5mm, length 200cm silicone rubber regulating member 2b was molded and the processing accuracy was examined, and a "sink mark" occurred in the range of 15+u+ from both ends in the longitudinal direction. In this range, to<n511 mm. This "sink" mainly occurs when the molded product is pulled out of the mold, and it is difficult to eliminate it completely, and the molded product tends to warp due to the difference in thermal expansion coefficient between the metal and the material. Therefore, in the second invention, the regulating member 2b
This problem is solved by using an odd number of springs 2d, which are the elastic pressing means, and pressing the vicinity of the center so that a component force acts toward the upstream side. For example, in FIG. 4, the area A is pressed so that the contact pressure with the toner carrier 2 is at an appropriate value and a component force is obtained in the direction to prevent deflection.

Here, the pressure for obtaining a component force in the direction of preventing deflection may be a method of directly pressing with a spring, or a method of pressing via another member. In addition, although the number of springs 2d is usually two, it is also possible to use one, and in order to press the vicinity of the center and to press evenly, an odd number of pressing means such as springs may be used. Furthermore, as shown in FIG. 6, the toner carrier 2 and the regulating member 2b can be placed in any position, and as shown in FIG. An elastic body having a shape may also be used.

As described above, according to the present invention, when pressing the end portion of the regulating member 2b against the toner carrier to form a toner layer, uniformity in the longitudinal direction of the toner carrier can be easily maintained.

[Effects of the Invention] As described above, according to the first invention, sufficient toner charging can be achieved with low pressure, so fogging immediately after toner replenishment can be prevented. Since there is no edge at the end of the toner layer thickness regulating member, it is easy to form a uniform toner layer, and even when a large amount of toner is consumed, it is possible to supply a sufficient amount of toner. In addition, there is little variation in the contact area due to wear, making it possible to form a uniform toner layer over a long period of time.
Good development can always be performed.

Furthermore, according to the second aspect of the invention, the occurrence of unevenness due to the bending of the toner layer thickness regulating member can be easily prevented. Therefore, the occurrence of unevenness in the toner layer in the longitudinal direction of the toner carrier can be prevented over a long period of time, and good development can always be performed.

Moreover, when the toner layer thickness regulating member is composed of a flexible plate-like polymer and a rigid support member inserted and disposed inside the polymer, the plate-like polymer is easily deformed. , the toner layer will not become non-uniform.

Furthermore, when manufacturing the toner layer thickness regulating member,
Since the rigid support member and the elastic polymer body can be easily integrally molded using methods such as insert molding, post-processing such as gluing the elastic polymer body to the support member is no longer necessary. Manufacturing and assembly processes are simplified.

Furthermore, in the conventional method of pressing the edge, a sufficient contact area with the toner carrier cannot be obtained, and the toner tends to be insufficiently charged, especially immediately after putting new toner into the developing device. Whereas the toner is insufficiently charged and tends to cause blurring, the present invention completely eliminates such problems.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a developing device showing one embodiment of the present invention, and FIGS. 2 and 3 are side views showing different configuration examples of the toner layer thickness regulating member in the developing device according to the present invention. ,
FIG. 4 is a plan view of essential parts of the developing device according to the present invention, FIG. 5 is a perspective view showing different configuration examples of the toner layer thickness regulating member in the developing device according to the present invention, and FIGS. 6 and 7 teeth,
FIG. 7 is a side view showing different examples of arrangement of toner layer thickness regulating members in the developing device according to the present invention. 1...Toner container 1a...Toner 2...Toner carrier (developing roller) 2a...
... Toner supply roller 2b ... Toner layer thickness regulating member 2c ... Recovery member 2d ... Spring 2e ... Supporting toner layer thickness regulating member supporting member (guide) 3... latent image holder (photosensitive drum) 4...
・Charger 5... Exposure means (laser light) 6... Transfer device 7... DC power supply 8... Protective resistor 9... Closed space 10...Core member d Suf 9 rim °. Figure 1 Figure 2 2e Figure 6 Figure 3 Figure 0 Figure 5 Figure 7

Claims (2)

[Claims] (1) A toner carrier disposed close to a latent image carrier that holds a latent image, and a toner layer thickness regulating member whose tip abuts the toner carrier and forms a thin toner layer on the toner carrier. In the developing device that develops the latent image using the toner formed in the thin layer, the toner layer thickness regulating member has a tip pressed against the toner carrier that is processed into a continuous surface of a curved surface and a substantially flat surface. A developing device, wherein at least a part of the substantially flat surface is configured to press the toner carrier. (2) A toner carrier disposed close to a latent image carrier that holds a latent image, and a toner layer thickness regulating member whose tip abuts the toner carrier and forms a thin toner layer on the carrier. and a developing device for developing the latent image with the toner formed in the thin layer, wherein at least one means for elastically pressing the toner layer thickness regulating member carries toner near the center of the toner layer thickness regulating member. A developing device characterized in that it is configured to press toward the upstream side in the direction of movement of the body.