JPH08220884A - Developing device - Google Patents

Abstract

PURPOSE: To provide a high reliable developing device capable of forming a uniform developer thin layer with a desired layer thickness on a developing roller over a long period. CONSTITUTION: Toner 15 supplied to a developing roller 10 from a supplying roller 12 passes through the gap 19 formed between a layer thickness regulating roller 11 and the developing roller 10, to form a uniform toner thin layer 22 having the thickness almost equal to the size of the gap 19 on the developing roller 10. The gap 19 is formed in such a manner that the developing roller 10 is brought into press-contact with the layer thickness regulating roller 11 with projecting parts 21 formed on both end parts 26 of the roller 10. Since the gap 19 is formed to a desired size, the uniform toner thin layer 22 having the desired layer thickness can be formed over the long period, with a simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly to a developing device using a one-component developer used in an image recording device such as a printer, a fax machine or a copying machine which utilizes an electrostatic latent image of an electrophotographic system. .

[0002]

2. Description of the Related Art Conventionally, in a one-component developing device, a uniform thin developer layer having a desired layer thickness is formed on a developer carrier.
It is extremely important to convey the thin developer layer onto the electrostatic latent image in order to realize good image recording without density unevenness. In the conventional one-component developing device as a means for forming a thin layer of such a developer, Japanese Patent Laid-Open Nos. 60-73648, 4-69685 and 5-303269 are available.
A method using an elastic blade is generally used, as described in Japanese Patent Laid-Open Publication No. 2003-242242. That is, FIG. 8 (a)
As shown in (b) and (b), a plate-shaped elastic body having one free end is used as a developer layer thickness regulating member (elastic blade) 24, and the layer thickness regulating member 24 is a developing roller which is a developer carrier. A thin layer of the developer 15 is formed on the developing roller 10 by bringing the developer 15 into contact with the entire outer peripheral surface in the axial direction with a uniform pressure and passing the developer 15 between the layer thickness regulating member 24 and the developing roller 10. Is going. As the layer thickness regulating member 24, a metal leaf spring or an elastic blade in which a soft elastic body is adhered to the tip of a metal leaf spring is generally used, and the layer thickness of the developer 15 is the development of the layer thickness regulating member 24. It is adjusted by the magnitude of the pressing force applied to the roller 10.

Further, in Japanese Patent Laid-Open No. 4-204977,
In the method using such an elastic blade, another developing device in which the layer thickness regulating method is improved is disclosed. Figure 9
As shown in FIG. 9A, a developer 15 containing gap holding particles 25 having a uniform particle size larger than the toner particle size is used, and as shown in FIG. 9B, a developing roller which is a developer carrier. Gap holding particles 25 between the layer 10 and the layer thickness regulating member 24
Thus, a gap 19 having a diameter equal to that of the gap holding particles 25 is formed, and the developer 15 is passed through the gap 19 to form a developer layer having a thickness substantially equal to the outer diameter of the gap holding particles 25. The gap holding particles 25 do not transfer to the electrostatic latent image side during development, are held on the developing roller 10, are collected in the developing container, and are repeatedly used.

[0004]

In the developing device using the conventional elastic blade as the layer thickness regulating member, the contact pressure between the layer thickness regulating member 24 and the developing roller 10 as the developer carrying member is uniform in the axial direction. It is difficult to keep this state stable for a long period of time. Therefore, a thin developer layer having a desired layer thickness and a uniform developer thin layer is formed.
It is difficult to form and maintain a stable image over 0 for a long period of time, and density unevenness easily occurs in a recorded image.

For example, as shown in FIG. 8A, a sharp edge is formed at the tip of a layer thickness regulating member 24 made of a metal elastic blade, and the edge portion is elastically applied to the developing roller 10 made of an elastic body. An apparatus for pressing and uniformizing the developer layer has been proposed. In this apparatus, a layer thickness regulating member 2 made of a metallic elastic blade is used to realize the uniformization of the developer layer.
It is necessary to form the sharp edge portion of No. 4 with high precision such as several μm or less. This is developer 15
If the particle diameter of the toner generally used as is about 5 to 10 μm is extremely fine and the processing accuracy of the edge portion of the blade tip is several μm or more, uneven streaks remain as indentations on the toner layer regulation surface. This is because these indentations appear as white streaks or black streaks on the recorded image. Even if the processing accuracy of the sharp edge portion of the metal blade tip can be set to several μm or less, such an edge portion is damaged by rubbing with hard toner such as minute unevenness and scratches. However, it is difficult to maintain stable toner thin layer formation for a long period of time. Further, since the processing cost becomes extremely high if the above-described high-precision processing is performed, it is practically impossible to put it into practical use.

Further, as shown in FIG. 8 (b), the flat surface of the layer thickness regulating member 24 made of a metallic elastic blade or the rotating surface of the metallic roller is pressed against the developing roller 10 made of an elastic body to develop the developer 15. Although a developing device that regulates the layer thickness is also proposed, in this device, in order to regulate the toner layer thickness to a predetermined thinness, a layer thickness regulating member 24 composed of a metal elastic blade is applied to the developing roller 10 with a large pressure. It is necessary to crimp. Therefore, the toner particles are crushed and the layer thickness regulating member 24
Toner adheres to the surface of the developing roller 10 and toner filming adheres to the surface of the developing roller 10 easily, and uneven streaks are left as marks on the toner layer thickness regulation surface, resulting in uneven layer thickness over a long period of use. become.

In the conventional method using the layer thickness regulating member 24 composed of an elastic blade, the developing roller 1 is generally used.
0 or at least one of the layer thickness regulating members 24 is composed of a soft elastic body, and therefore permanent strain is generated in the soft elastic body or the leaf spring-shaped layer thickness regulating member 24 is bent due to long-term use. The pressing force of the regulating member 24 against the developing roller 10 changes,
The layer thickness changes or becomes non-uniform. If the developing device is stopped for a longer period, the developing roller 10
Local plastic deformation occurs in the contact portion with the upper layer thickness regulating member 24, the layer thickness of the developer 15 becomes non-uniform at that portion, and the rotation speed of the developing roller 10 and the latent image charge holding medium 18 increases. It fluctuates and causes a so-called jitter problem.

Further, the pressing force of the leaf spring-shaped layer thickness regulating member 24 against the developing roller 10 is likely to change greatly even if the mounting position of the layer thickness regulating member 24 is slightly changed. At times, the mounting accuracy of the layer thickness regulating member 24 is strict. For example, when the layer thickness is regulated using the edge of the metal blade tip described above, in order to achieve a predetermined layer thickness, the setting angle of the metal blade is strictly set to an extremely narrow range of ± 0.4 degrees. It has been described in JP-A-3-21968 that it must be fixed. Further, the plate-spring-like layer thickness regulating member 24 easily vibrates, resonates with the vibration generated in the image forming apparatus, and easily vibrates, and the layer thickness of the developer 15 easily fluctuates periodically.

On the other hand, in the method of using the developer containing the particles 19 for holding the gaps, which is described in JP-A-4-204977, the layer thickness is regulated by the particles 25 for holding the gaps, so that the method using an elastic blade is used. Although it has an advantage that a thin developer layer having a desired layer thickness can be formed more easily than the above, the mixing ratio of the gap holding particles 25 and the toner 15 gradually changes with long-term use, and the mixing ratio falls within a certain range. If it exceeds, it becomes impossible to form a uniform thin layer. Therefore, it is necessary to provide a mechanism for controlling the mixing ratio within a certain range, a remaining amount sensor of the toner 15 and the like, which complicates the structure of the developing device and makes it expensive, and poor maintainability. . Further, since the toner 15 is insufficiently supplied to the developing roller 10 immediately below and in the vicinity of the gap holding particles 25, it is difficult to uniformly form a thin developer layer on the developing roller 10.

An object of the present invention is to solve the problems of the prior art and to easily form a thin developer layer having a desired uniform layer thickness on a developer carrying member with a simple structure. Another object of the present invention is to provide a highly reliable developing device capable of forming a uniform thin developer layer for a long period of time.

[0011]

A developing device of the present invention is a developing device used for visualizing an electrostatic latent image with a developer, wherein the developer is formed on at least the electrostatic latent image. The developer carrier to be conveyed and a layer thickness regulating member that regulates the layer thickness of the thin developer layer formed on the developer carrier are configured to include the developer carrier or the layer thickness regulating member. At least one has a convex portion in the vicinity of both end portions, the developer carrying member and the layer thickness regulating member are pressure-contacted via the convex portion, and the convex portion is formed in a region sandwiched by the both convex portions of the both end portions. A uniform gap having a size equal to the height is formed.

Further, the developing device of the present invention is characterized in that the convex portion is formed by a plating process.

Further, the convex portion of the developing device of the present invention is
It is characterized by being formed by a plastic working method such as forging.

Further, the size of the gap of the developing device of the present invention is at least the average particle size of the developer,
The average particle size of the developer is 6 times or less, preferably the maximum particle size of the developer or more and 4 times or less of the average particle size of the developer.

Further, the friction coefficient of the layer thickness regulating member of the developing device of the present invention with the developer in the region corresponding to the gap is the same as that of the developer in the region corresponding to the gap of the developer carrier. Is sufficiently smaller than the friction coefficient of.

Further, the friction coefficient between the developer carrier and the developer at the pressure contact portion between the developer carrier and the layer thickness regulating member of the developing device of the present invention, and the layer thickness regulating member and the developer. The coefficient of friction between and is at least sufficiently small that the developer does not enter the pressure contact portion.

Further, the developer carrier and the layer thickness regulating member of the developing device of the present invention are characterized by being made of a material having a longitudinal elastic modulus of 100 kg / mm ² or more.

[0018]

According to the present invention, a uniform gap having a size approximately equal to the desired layer thickness of the thin developer layer is formed between the developer carrying member and the layer thickness regulating member, and the developer is passed through this gap. By doing so, a uniform thin developer layer having a desired thickness can be easily formed on the developer carrying member. Since the layer thickness of the thin developer layer formed on the developer carrier is formed to be approximately equal to the height of the convex portions formed on both ends of the developer carrier, the height of the convex portion is changed. As a result, the thickness of the thin developer layer formed on the developer carrier can be easily controlled. Further, by forming the gap between the developer carrier and the layer thickness regulating member with high accuracy in advance, it is possible to easily realize the uniform layer thickness of the thin developer layer.

By the way, the thin developer layer formed on the developer carrying member is an extremely thin layer from one layer to several layers, and in order to form such a thin developer layer, it is on the order of several μm to several tens μm. It is necessary to form fine protrusions on the developer carrier or on the layer thickness regulating member. It is possible to form such a fine convex portion by a normal machining method such as a cutting method, but there is a problem in productivity when mass production is taken into consideration, and it becomes very expensive, It is practically extremely difficult to put the protrusion formation by the usual mechanical method into practical use.
Therefore, in the developing device of the present invention, such fine protrusions are formed by a plastic processing method such as plating or forging, thereby enabling high productivity and high precision processing.

In the developing device of the present invention, unlike the conventional developing device using an elastic blade, it is not necessary to press the developer layer with a large pressure by the layer thickness regulating member, so that the development to the layer thickness regulating member is performed. Adhesion of the developer and filming of the developer on the developer carrier do not occur.

Further, in the developing apparatus of the present invention, when a latent medium having a flexible medium such as a pyroelectric polymer film or a photosensitive belt is used as the latent image charge holding medium,
The developer carrying member and the layer thickness regulating member can be made of a member having a high longitudinal elastic modulus such as metal. Therefore, the problem of permanent deformation of the developer carrying member and the layer thickness regulating member, which has been a problem in the conventional developing device, does not occur, and stable and uniform thin layer formation can be performed for a long period of time. In the developing device of the present invention, the developer carrier or the layer thickness regulating member can be made of a soft elastic material such as rubber or foam material in principle, but the developer carrier and the layer thickness regulating member are possible. Due to the pressing force acting between them, elastic deformation easily occurs in both members, making it difficult to control the size of the gap and making it difficult to form the gap uniformly over the entire surface. As a result of conducting an experimental study by changing the materials of the developer carrying member and the layer thickness regulating member variously, the developer carrying member and the layer thickness regulating member are made of a material having at least a longitudinal elastic modulus of 100 kg / mm ² or more. It was confirmed that a uniform thin layer can be easily formed.

Further, in the developing device of the present invention, the developer carrying member and the layer thickness regulating member can be constituted by a structure having high rigidity, and the layer thickness regulating member can be regulated like the conventional developing device using the elastic blade. The problem of member vibration does not occur.

[0023]

Next, the present invention will be described with reference to the drawings. For the sake of explanation, on the developing roller which is the developer carrying member and the layer thickness regulating roller which is the layer thickness regulating member, both the thin layer forming region and the thin layer forming region are involved in the thin developer layer formation. The outer region is defined as both ends.

FIG. 1 is a diagram showing the construction of a developing device according to the first embodiment of the present invention, in which a developing roller 10 having fine protrusions 21 formed in the vicinity of both ends 26 is used as a developer carrier, and the layer thickness is An example in which a cylindrical layer thickness regulating roller 11 is used as the regulating member is shown. 1A and 1B are a side cross-sectional view of the entire developing device and a top view showing a pressure contact state between the developing roller 10 and the layer thickness regulating roller 11, respectively. Referring to FIG. 1, the developing device of this embodiment includes a developing roller 10,
Layer thickness regulating roller 11, supply roller 12, recovery blade 13, seal material 14, toner 1 as a developer
5, a toner tank 16 and a developing bias power source 17 for applying a developing bias. The supply roller 12 has a structure in which a foam is attached to a metal cored bar, and the toner 15 is supplied to the outer peripheral surface of the developing roller 10 by the supply roller 12. The toner 15 supplied onto the developing roller 10 is the layer thickness regulating roller 11 and the developing roller 10.
The layer thickness is regulated by passing through the gap 19 formed between the developing roller 10 and the toner, and a thin toner layer 22 having a uniform thickness which is almost equal to the size of the gap 19 is formed on the developing roller 10. The toner thin layer 22 thus formed is conveyed onto the latent image charge holding medium 18 on which the electrostatic latent image is formed, and the electrostatic latent image is visualized by the contact developing method. Residual toner on the developing roller 10 that has not been used in the development is scraped off by the supply roller 12 that rotates in the opposite direction to the developing roller 10,
The toner is collected in the toner tank 16. Here, the recovery blade 13 and the sealing material 14 are
It is arranged to prevent toner from spilling from.
The charging of the toner 15 is performed by frictional charging between the toner 15 and the supply roller 12 and between the toner 15 and the developing roller 10 that occurs when the toner 15 is supplied from the supply roller 12 to the developing roller 10, and a gap between the toner 15 and the toner 15. Toner 15 and developing roller 10 generated when passing through 19
And friction charging between the toner 15 and the layer thickness regulating roller 11.

First, a method of manufacturing the developing roller 10 will be described. Center line average roughness Ra =
After finishing to 1.23 μm and ten-point average roughness Rz = 4.5 μm, in order to increase the friction coefficient with the toner 15 and obtain a sufficient toner conveying force, only the thin layer forming region 20 is subjected to Ra by sandblasting. = 2.55 μm, Rz = 1
Finish to 2.4 μm. Finally, the minute protrusions 21 of several μm to several tens μm are formed on both ends of the metal roller by nickel plating, and the developing roller 10 having the protrusions 21 at both ends 26 is manufactured. By such nickel plating, the convex portions 21 can be easily processed with sufficient accuracy of at least ± 0.5 μm in height accuracy, and the convex portions 21 can be simultaneously formed on a plurality of developing rollers 10 by batch processing. Since it can be performed, it has been confirmed that the productivity is extremely superior to the machining method such as the cutting method. Further, when the formation of the convex portion 21 by the forging method is also tried, both end portions 26 have the same processing accuracy and productivity as the plating process even in the forging method.
It was confirmed that the developing roller 10 having the fine protrusions 21 of several μm to several tens μm can be easily manufactured.

Next, a plurality of developing rollers 10 in which the heights of the convex portions 21 formed on both end portions 26 of the developing roller 10 are variously manufactured are manufactured, and the size of the gap 19 is changed to 5 to 60 μm, and the development is performed. An attempt was made to form a thin toner layer 22 on the roller 10. The toner 15 used in the experiment is a negatively charged non-magnetic toner having an average particle size of 8 μm, and the layer thickness regulating roller 11 is a metal roller having a surface roughness Ra = 1.23 μm and Rz = 4.5 μm. The toner thin layer 22 was formed by rotating the roller 10 in the forward direction.

As a result, when the gap 19 is smaller than the average particle size 8 μm of the toner 15, most of the toner 15 on the developing roller 10 cannot pass through the gap 19 and the fine toner having a particle size smaller than the gap 19 is used. Since the thin layer is formed only by itself, the formed toner thin layer 22 is thinner than the size of the gap 19 and is a sparse extremely non-uniform thin layer. Such a tendency becomes more remarkable as the gap 19 becomes smaller, and when the size of the gap 19 is 5 μm, almost no thin layer can be formed. Also, gap 1
Since the size of 9 is smaller than the average toner particle size, the gap 1
A toner having a particle diameter slightly larger than the size of 9 is easily crushed in the gap 19 and there is a problem that toner adheres to the outer peripheral surface of the developing roller 10 or the layer thickness regulating roller 11.

Next, the size of the gap 19 was set to 9 μm, which was slightly larger than the average toner particle size, and an attempt was made to form a thin layer.
As a result, it is possible to form a uniform toner thin layer 22 having a thickness of about 9 μm on the developing roller 10, and even if the thin layer is formed for a long period of time, the outer peripheral surface of the developing roller 10 and the layer thickness regulating roller 11 can be formed. Toner adhesion was also significantly reduced to a level where there was no practical problem. From the above, it was confirmed that a uniform thin layer can be easily formed on the developing roller 10 by setting the size of the gap 19 to be at least 9 μm and not less than the average toner particle size. Therefore, the developing device was configured under the above conditions to perform image recording. A photoconductor belt (OPC) is used as the latent image charge holding medium 18, and an electrostatic latent image that becomes a black solid image is formed on the OPC by an exposing unit (not shown) and developed by a reversal developing method. Image recording was performed by transferring and fixing to As a result, it was possible to stably form a good solid black image with an optical density of 1.5 without unevenness in density. Further, when fine line image recording was performed in the same manner, it was confirmed that fine line image recording faithful to the formed latent image was possible with almost no fogging.

However, when image recording was carried out for a long time with the size of the gap 19 set to 9 μm, the image density gradually decreased when the amount of toner remaining in the developing tank became about 1/5. became. The cause has been found to be as follows. That is, the gap 1
Since the size of 9 is smaller than the maximum particle size of the toner 15,
When image recording is performed for a long period of time, the proportion of the toner 15 having a particle size of 9 μm or more that cannot pass through the gap 19 in the developing tank increases. As a result, the ratio of the amount of toner that can pass through the gap 19 to the total amount of toner decreased, and the uniformity of the toner thin layer 22 gradually deteriorated. As described above, when the size of the gap 19 is smaller than the maximum toner particle size, it is necessary to replace the toner before the total toner is consumed, but in the case of this embodiment, it is 4/5 of the total toner amount. A uniform thin toner layer 22 is formed on the developing roller 10 until the toner is consumed.
Was formed, and high-quality image recording was possible.

Next, the size of the gap 19 is set to 16 μm, which is equal to the maximum particle size of the toner 15, to form a thin toner layer. Here, the maximum particle size of the toner 15 is defined as the toner particle size that occupies 95% in the particle size distribution. As a result, a uniform thin toner layer 22 having a thickness approximately equal to the size of the gap 19 can be formed until almost all the toner 15 in the developing container is consumed. Moreover, the developing roller 10
And, toner adhesion to the outer peripheral surface of the layer thickness regulating roller 11 no longer occurs.

Further, the size of the gap 19 was gradually set to be large, and the same experiment as above was conducted. As a result, the gap 1
It was found that the toner 15 easily spilled from the gap 19 when the size of 9 exceeded about 6 times the average toner particle size. Also, as the size of the gap 19 increases,
Since the amount of charge applied to the toner 15 is reduced by frictional charging and the uniformity of the toner charge amount is deteriorated, density unevenness easily occurs when image recording is performed. Further, as the gap 19 increases, the toner charge amount decreases, and the toner 15
Since the adhesion of the toner to the developing roller 10 is reduced, the toner is likely to be scattered to the non-image area. When the size of the gap 19 is about 5 to 6 times the average particle diameter of the toner, the fog is slightly caused on the non-image area. There has occurred. In order to reduce such density unevenness and fog to a level where there is practically no problem,
It was experimentally confirmed that the size of the gap 19 should be at least 4 times the average particle size of the toner 15.

Therefore, an image recording experiment was carried out by configuring the developing device with the gap 19 having a size of 20 μm, which is 2.5 times the average particle diameter of the toner. As the latent image charge holding medium 18, a pyroelectric polymer film (PVD) that generates an electric charge by heating.
F) was used and the entire surface was heated by a thermal head (not shown) to form a solid black latent image, and then visualized by a regular development method. Further, after transferring the toner image on the polymer film onto the recording paper, the toner image was fixed and a solid black image was recorded. As a result, it was confirmed that good image recording with a high optical density of 1.5 and no density unevenness can be stably realized for a long period until the toner 15 in the toner tank 16 is exhausted. Further, when fine line image recording was performed in the same manner, it was confirmed that it was possible to perform fine line image recording faithful to the formed latent image without fogging.

In this embodiment, the layer thickness regulating roller 1
Although 1 was rotated in the forward direction with respect to the developing roller 10, it was confirmed that the same effect could be obtained by rotating it in the reverse direction or stopping it. When the layer thickness regulating roller 11 is rotated in the reverse direction, the toner is frictionally charged more than when the layer thickness regulating roller 11 is rotated in the forward direction and when the layer thickness regulating roller 11 is stopped. It was confirmed that a larger charge amount can be given to 15. It was also confirmed that when the supply roller 11 is rotated in the reverse direction and the forward direction, the charge amount of the toner 15 can be increased by increasing the rotation speed. As described above, it was confirmed that the developing device according to this embodiment can stably form a uniform thin toner layer and control the toner charge amount.

FIG. 2 shows a developing device according to a second embodiment of the present invention, in which a developing roller 10 is used as a developer carrying member,
An example in which a cylindrical layer thickness regulating roller 11 having fine protrusions 21 formed on both end portions 26 is used as the layer thickness regulating member is shown. The outline of the developing device is the same as that of FIG. 1A, and FIG. 2 is a top view showing a state where the developing roller 10 and the layer thickness regulating roller 11 are in pressure contact with each other. Except for the developing roller 10 and the layer thickness regulating roller 11,
The structure is exactly the same as that of the first embodiment. Similar to the first embodiment, the size of the gap 19 was variously changed, and the thin layer forming experiment and the image recording experiment were conducted. As a result, as in the first embodiment, the size of the gap 19 is set to at least the toner 1.
It was confirmed that it is possible to form a uniform thin toner layer 22 on the developing roller 10 when the average particle size is 5 or more and 6 times or less the average particle size of the toner 15. Further, by setting the size of the gap 19 to be equal to or larger than the maximum particle diameter of the toner and equal to or smaller than 4 times the average particle diameter of the toner, it is possible to form a uniform thin layer for a long period of time as in the first embodiment. , And confirmed that it is possible to further improve reliability and image quality.

FIG. 3 shows a developing device according to a third embodiment of the present invention, in which a developing roller 10 is used as a developer carrying member,
An example in which a cylindrical layer thickness regulating roller 11 is used as the layer thickness regulating member and fine projections 21 are formed on the developing roller 10 and four end surface portions of the layer thickness regulating roller 11 will be described.
The outline of the developing device is similar to that of FIG. 1A, and FIG. 3 is a top view showing a state where the developing roller 10 and the layer thickness regulating roller 11 are in pressure contact with each other. Also in this case, it was confirmed that exactly the same effects as those of the first and second embodiments described above were obtained.

FIG. 4 shows a developing device according to a fourth embodiment of the present invention. As a developer carrying member, fine protrusions 21 are formed at both ends.
An example is shown in which the formed developing roller 10 is used and a block-shaped layer thickness regulating plate 23 is used as the layer thickness regulating member. FIG.
3A and 3B are a side sectional view of the developing device and a top view showing a state where the developing roller 10 and the layer thickness regulating member are in pressure contact with each other. As shown in FIG. 4A, the developing device includes a developing roller 10, a layer thickness regulating plate 23, a supply roller 12, a recovery blade 13, and a toner 1 as a developer.
5, a toner tank 16 and a developing bias power source 17 for applying a developing bias. The supply roller 12 has a structure in which a foam is attached to a metal cored bar, and the toner 15 is supplied to the outer peripheral surface of the developing roller 10 by the supply roller 12. The toner 15 supplied onto the developing roller 10 is regulated in layer thickness by passing through a gap 19 formed between the layer thickness regulating plate 23 and the developing roller 10, and the thickness is almost equal to the size of the gap 19. A thin toner layer 22 having a uniform thickness is formed on the developing roller 10. The toner thin layer 22 thus formed is conveyed onto the latent image charge holding medium 18 on which the electrostatic latent image is formed, and the electrostatic latent image is developed by the contact developing method. Residual toner on the developing roller 10 that has not been used for development is scraped off by the supply roller 12 that rotates in the opposite direction to the developing roller 10, and is collected in the toner tank 16.

The difference from the first embodiment is that the layer thickness regulating member is changed from a cylindrical shape to a block shape, and the layer thickness regulating member also serves as the sealing material 14 in the first embodiment. The point is that it also functions to prevent spillage, and that the layer thickness regulating member does not rotate and is fixed to the toner tank 16. Except for these points, the developing device has the same configuration as that of the first embodiment. Similar to the first embodiment, the size of the gap 19 was changed variously, and the thin layer forming experiment and the image recording experiment were conducted. As a result, when the size of the gap 19 is set to be at least the average particle size of the toner 15 and not more than 6 times the average particle size of the toner 15, the uniform thin toner layer 22 is formed on the developing roller 10. It was confirmed that Further, the size of the gap 19 is set to the toner 1
5 is the maximum particle size or more and is less than or equal to 4 times the toner average particle size, the toner 15 adheres to the developing roller 10 and the layer thickness regulating plate 23, toner spills, and fogging during development. Further, it was confirmed that the reliability was improved and a uniform thin layer could be formed over a long period of time.

Similar to the first embodiment, an image recording experiment was conducted by setting the size of the gap 19 to 20 μm which is 2.5 times the average particle diameter of the toner. A pyroelectric polymer film (PVDF) that generates electric charges by heating is used as the latent image charge holding medium 18, and the entire surface is heated by a thermal head (not shown) to form a black solid latent image, and then regular development is performed. It was visualized by the method. Further, the toner image on the polymer film was transferred onto a recording paper and then fixed to obtain a black solid image. As a result, it was confirmed that a high image with an optical density of 1.5 and a good image without density unevenness can be stably realized for a long period until the toner 15 in the toner tank 16 is exhausted. Further, when fine line image recording was performed in the same manner, it was confirmed that fine line image recording faithful to a latent image without fog was possible. Although the layer thickness regulating member has a rigid body structure in FIG. 4, the same effect can be obtained even if the layer thickness regulating member is constituted by the plate-like elastic blade 24 as in the fifth embodiment of the present invention shown in FIG. It was confirmed that

FIG. 6 shows a developing device according to a sixth embodiment of the present invention, in which a developing roller 10 is used as a developer carrying member,
An example in which a plate-shaped layer thickness regulating plate 23 having fine protrusions 21 formed at both ends is used as the layer thickness regulating member is shown. The outline of the developing device is similar to that of FIG. 4A, and FIG.
It is a top view which shows the press-contact state of the layer thickness regulation plate 23. Except for the developing roller 10 and the layer thickness regulating plate 23, the structure is exactly the same as that of the fourth embodiment, and similarly to the fourth embodiment, the size of the gap 19 is variously changed to perform a thin layer forming experiment and an image. Recording experiments were conducted. As a result, when the size of the gap 19 is set to be at least the toner average particle size or more and 6 times or less of the toner average particle size, it is possible to form a uniform thin toner layer on the developing roller 10. It was confirmed. Further, when the size of the gap 19 is set equal to or larger than the maximum toner particle diameter and equal to or smaller than 4 times the average toner particle diameter, the toner 15 adheres to the developing roller 10 and the layer thickness regulating roller 11, toner spills, It was also confirmed that the reliability of fogging during development was further improved, and a uniform thin layer could be formed for a long period of time.

FIG. 7 shows a developing device according to a seventh embodiment of the present invention, in which a developing roller 10 is used as a developer carrying member,
An example is shown in which a plate-shaped layer thickness regulating plate 23 is used as the layer thickness regulating member, and minute protrusions 21 are formed on both end surfaces of both the developing roller 10 and the layer thickness regulating plate 23. The outline of the developing device is the same as that of FIG. 4A, and FIG. 7 is a top view showing the state where the developing roller 10 and the layer thickness regulating plate 23 are in pressure contact with each other. Also in this case, it was confirmed that the same effect as that of the above-mentioned fourth embodiment was obtained.

In the embodiment of the present invention, the supply roller is provided for supplying the toner to the developer carrying member, but the toner may be supplied by utilizing its own weight. Further, in the embodiment of the present invention, the non-magnetic toner is used as the developer, but the magnetic toner may be used. In the embodiment of the present invention, the contact developing method using the one-component developing device has been described as an example.
The same effect can be obtained by applying it to a non-contact developing method or a two-component developing device. Further, in the embodiment of the present invention, the metal material is used as the developer carrying member and the layer thickness regulating member, but the longitudinal elastic modulus is 100 kg / m even when a polymer material such as hard vinyl chloride is used.
It has been confirmed that the same effect as that of the example of the present invention can be obtained when m ² or more.

In order to clarify the influence of the friction coefficient between the toner, which is the developer, and the developer carrying member and the layer thickness regulating member, on the developing characteristics, the surface roughness of both members was changed to the first embodiment. A comparison was made.

Comparative Example 1 In the first embodiment of the present invention, the surface roughness of the thin layer forming region 20 of the developing roller 10 is Ra =
2.55 μm, Rz = 12.4 μm, both ends 2
The surface roughness of 6 is Ra = 1.23 μm, Rz = 4.5 μm
formed to m. Further, the layer thickness regulation roller 11 has a surface roughness Ra = 1.
23 μm and Rz = 4.5 μm, but in Comparative Example 1, the surface roughness (coefficient of friction with toner) of the thin layer forming region 20 of the layer thickness regulating roller 11 was Ra = 2.55 μm and Rz.
= 12.4 μm, and the thin layer forming region 2 of the developing roller 10
Surface roughness at 0 (friction coefficient with toner 15) Ra =
A toner thin layer was formed in the same manner as in the first embodiment, with the value of 1.23 μm and Rz = 4.5 μm. As a result, in Comparative Example 1, the toner carrying force could not be applied to the developing roller 10 and the toner carrying force was applied to the layer thickness regulating roller 11 side, so that a thin toner layer is formed on the layer thickness regulating roller 11 side. It became a result.

(Comparative Example 2) In Comparative Example 2, the surface roughness (coefficient of friction with the toner 15) of the thin layer forming area 20 of the layer thickness regulating roller 11 is determined as the surface roughness (toner of the developing roller 10). Friction coefficient with 15) as well as R
a = 2.55 μm and Rz = 12.4 μm, and a thin layer was formed in the same manner as in the first embodiment. As a result, the toner conveying force is applied to both the developing roller 10 and the layer thickness regulating roller 11, and a thin developer layer is formed on both the outer peripheral surfaces of the developing roller 10 and the layer thickness regulating roller 11.
A non-uniform toner thin layer 22 was formed on the surface of No. 0.

From Comparative Example 1 and Comparative Example 2 described above, in order to form a uniform thin layer on the developing roller 10, the coefficient of friction with the developer in the thin layer forming region of the layer thickness regulating member is calculated as follows.
It was confirmed that it is necessary to form the developer carrier sufficiently smaller than the friction coefficient with the developer in the thin layer forming region.

Comparative Example 3 In Comparative Example 3, the surface roughness at both end portions 26 of the layer thickness regulating roller 11 is Ra = 1.8.
The thickness was increased to 5 μm and Rz = 8.3 μm, and a thin layer forming experiment was conducted in the same manner as in the first embodiment. As a result, the developing roller 10
The fine toner having a small particle size entered the pressure contact portion between the layer thickness regulation roller 11 and the toner, and the toner 15 was crushed and the toner filming adhered to the developing roller 10 and the layer thickness regulation roller 11. When the development is continued for a long period of time, the amount of adhered toner gradually increases, and as a result, the size of the gap 19 gradually increases, and the toner thin layer 22 having a desired thickness cannot be formed. The size of the gap 19 was changed, and the uniformity of the thin toner layer 22 was significantly deteriorated. Developing roller 1
The surface roughness at both end portions 26 of 0 is Ra = 1.85 μ
The same phenomenon occurred when m and Rz were increased to 8.3 μm.

According to the above comparative experiment, at least the friction coefficient between the developer carrying member and the developer at the pressure contact portion between the developer carrying member and the layer thickness regulating member, and the friction coefficient between the layer thickness regulating member and the developer are at least. It has been confirmed that it is necessary to form the pressure contact portion sufficiently small so that the developer does not enter the pressure contact portion.

[0048]

In the developing device of the present invention, a uniform gap, which is approximately equal to the desired thickness of the thin developer layer, is formed between the developer carrier and the layer thickness regulating member, and the developer is formed in this gap. By passing through, it is possible to form a thin developer layer having a desired uniform layer thickness on the developer carrier with high precision and ease, and to form a uniform thin developer layer for a long period of time. It is possible to realize a highly reliable one-component developing device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a developing device according to a first embodiment of the present invention, in which (a) and (b) are side cross-sectional views of the entire developing device, a developing roller and a layer thickness regulating roller, respectively. FIG. 3 is a top view showing the pressed state of FIG.

FIG. 2 is a top view showing a pressed state of a developing roller and a layer thickness regulating member in a second embodiment of the present invention.

FIG. 3 is a top view showing a pressed state of a developing roller and a layer thickness regulating member according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a developing device according to a fourth embodiment of the present invention, in which (a) and (b) are a side sectional view of the entire developing device, a developing roller and a layer thickness regulating plate, respectively. FIG. 3 is a top view showing the pressed state of FIG.

FIG. 5 is a top view showing a pressed state of a developing roller and a layer thickness regulating member in a fifth embodiment of the present invention.

FIG. 6 is a top view showing a pressed state of a developing roller and a layer thickness regulating member in a sixth embodiment of the present invention.

FIG. 7 is a top view showing a pressed state of a developing roller and a layer thickness regulating member in a seventh embodiment of the present invention.

FIG. 8 is a side view showing an outline of a conventional developing device.

FIG. 9 is a side view showing an outline of a conventional developing device.

[Explanation of symbols]

 10 Developing Roller (Developer Carrier) 11 Layer Thickness Control Roller 12 Supply Roller 13 Recovery Blade 14 Sealing Material 15 Toner (Developer) 16 Toner Tank 17 Developing Bias Power Supply 18 Latent Image Charge Retaining Medium 19 Gap 20 Thin Layer Forming Area 21 Convex portion 22 Toner thin layer 23 Layer thickness regulating plate 24 Layer thickness regulating member (elastic blade) 25 Gap holding particles 26 Both ends

Claims (7)

[Claims] 1. A developing device used for visualizing an electrostatic latent image with a developer, comprising a developer carrier for carrying the developer on at least the electrostatic latent image, and the developer. And a layer thickness regulating member that regulates the layer thickness of the developer thin layer formed on the carrier, wherein at least one of the developer carrier and the layer thickness regulating member has a convex portion near both ends. However, the developer carrying member and the layer thickness regulating member are pressed against each other via the convex portion, and a uniform gap having a size equal to the height of the convex portion is formed in a region sandwiched between the both convex portions at both ends. A developing device, which is formed and configured. 2. The developing device according to claim 1, wherein the convex portion is formed by a plating process. 3. The developing device according to claim 1, wherein the convex portion is formed by a plastic working method such as forging. 4. The size of the gap is at least not less than the average particle size of the developer and not more than 6 times the average particle size of the developer, preferably not less than the maximum particle size of the developer. 4. The developing device according to claim 1, wherein the developing agent is 4 times or less the average particle diameter of the developer. 5. A coefficient of friction with the developer in a region corresponding to the gap of the layer thickness regulating member is sufficiently larger than a coefficient of friction with the developer in a region corresponding to the gap of the developer carrier. 5. The developing device according to claim 1, wherein the developing device is small. 6. A friction coefficient between the developer bearing member and the developer at a pressure contact portion between the developer bearing member and the layer thickness regulating member, and a friction coefficient between the layer thickness regulating member and the developer. Is sufficiently small that at least the developer does not enter the pressure contact portion.
The developing device according to 2, 3, 4 or 5. 7. The developer carrying member and the layer thickness regulating member are made of a material having at least a longitudinal elastic modulus of 100 kg / mm ² or more.
The developing device according to 3, 4, 5 or 6.