JP2023183623A - Developing device and image forming apparatus - Google Patents

Abstract

To prevent variations in the performance of a developing roller.SOLUTION: A developing device comprises: a developer container that stores one-component developer composed of toner; a developing roller that is rotatably supported by the developer container, is arranged opposite to an image carrier, has irregularities on its outer peripheral surface, and rotates while carrying the toner on the outer peripheral surface to supply the toner to the image carrier; and a regulation blade that is in contact with the outer peripheral surface to adjust the layer thickness of a toner layer formed on the outer peripheral surface. The developing roller has, on the outer peripheral surface, irregularities in which the contact area ratio is 10% or more and 20% or less, which is the ratio of the actual area of contact between the outer peripheral surface and a plane of a transparent member relative to the nip area between the outer peripheral surface and the plane when the plane is brought into contact with the outer peripheral surface at a linear pressure of 50 N/m.SELECTED DRAWING: Figure 4

Description

The present invention relates to a developing device and an image forming apparatus.

A conventional developing device includes a developing roller (developer carrier). The developing roller carries toner on its outer peripheral surface and rotates. Thereby, the developing roller transports the toner. Further, the conventional developing device includes a regulating blade (developer regulating member) that contacts the outer peripheral surface of the developing roller. By bringing the regulating blade into contact with the outer circumferential surface of the developing roller, a toner layer having a uniform layer thickness is formed on the outer circumferential surface of the developing roller. Such a developing device is disclosed in Patent Document 1, for example.

Japanese Patent Application Publication No. 2012-177853

The developing roller has irregularities on its outer peripheral surface. For example, the surface roughness of the outer circumferential surface of the developing roller is specified, and the outer circumferential surface of the developing roller is formed as specified. However, since the developing roller is used with the regulating blade in contact with its outer circumferential surface, even if the outer circumferential surface of the developing roller is formed as specified, there may be large variations in the performance of the developing roller regarding toner transport. . This has the disadvantage that the amount of toner conveyed by the developing roller cannot be reliably controlled.

The present invention was made to solve the above problems, and an object of the present invention is to provide a developing device and an image forming device that can suppress variations in the performance of a developing roller.

In order to achieve the above object, a developing device according to a first aspect of the present invention includes a developing container containing a one-component developer made of toner, and a developing device rotatably supported by the developing container and facing an image carrier. The developing roller is arranged as a roller, has unevenness on its outer circumferential surface, carries toner on its outer circumferential surface, and rotates to supply toner to the image carrier. and a regulating blade for adjusting the layer thickness of the toner layer. The developing roller is the ratio of the actual contact area between the outer circumferential surface and the flat surface to the nip area between the outer circumferential surface and the flat surface when the flat surface of the transparent member is brought into contact with the outer peripheral surface at a linear pressure of 50 N/m. The outer peripheral surface has irregularities with a contact area ratio of 10% or more and 20% or less.

An image forming apparatus according to a second aspect of the present invention includes the above-mentioned developing device.

With the configuration of the present invention, it is possible to suppress variations in the performance of the developing roller.

1 is a schematic diagram of an image forming apparatus including a developing device according to an embodiment. FIG. 1 is a schematic diagram of a developing device according to one embodiment. FIG. 2 is an enlarged view of the vicinity of a contact position between a developing roller and a regulating blade of a developing device according to an embodiment. FIG. 3 is a schematic diagram showing a state in which a prism is in contact with a developing roller of a developing device according to an embodiment. 5 is a schematic diagram of the results obtained by the measurement method shown in FIG. 4. FIG. FIG. 7 is a diagram showing the results of an experiment using a developing roller in which the conditions for forming the outer circumferential surface of the developing roller were defined by the contact area ratio with a prism. FIG. 7 is a diagram showing the results of an experiment using a developing roller in which the forming conditions of the outer circumferential surface of the developing roller were defined by ten-point average roughness.

An image forming apparatus including a developing device according to this embodiment will be described below, taking a monochrome printer as an example.

<Overall configuration of image forming apparatus>
As shown in FIG. 1, an image forming apparatus 100 according to the present embodiment includes a developing device 1. As shown in FIG. The developing device 1 forms an image (toner image). In other words, the developing device 1 supplies toner to the electrostatic latent image to develop it. The configuration of the developing device 1 will be explained in detail later.

A paper feed cassette 200 is removably attached to the image forming apparatus 100 . Paper feed cassette 200 stores sheets (not shown). In printing with the image forming apparatus 100, sheets in the paper feed cassette 200 are used. Sheets that can be used in printing include copy paper, coated paper, OHP sheets, cardboard, postcards, and tracing paper.

Paper feed cassette 200 has a lift plate 201 inside. The sheets in the paper feed cassette 200 are placed on the lift plate 201. The lift plate 201 rotates with one end (upstream in the paper feeding direction and the rear end of the sheet) serving as a fulcrum, and the other end (downstream in the paper feeding direction and the front end of the sheet) swinging up and down.

A paper feed roller 202 is provided on the downstream side of the paper feed cassette 200 in the paper feed direction (sheet feed port). As the lift plate 201 rises, the sheet on the lift plate 201 comes into contact with the outer peripheral surface of the paper feed roller 202. The paper feed roller 202 rotates with the sheet in contact with it. As a result, the sheet is sent out from the paper feed cassette 200.

Image forming apparatus 100 includes an image forming section 300. Image forming section 300 receives sheets sent out from paper feed cassette 200. The image forming unit 300 forms a toner image and transfers it onto a sheet. Image forming section 300 includes a photoreceptor drum 301, a transfer roller 302, a charging device 303, and an exposure device 304. The photosensitive drum 301 corresponds to an "image carrier." Note that the developing device 1 is one component of the image forming section 300.

Photosensitive drum 301 is rotatably supported. The transfer roller 302 is in pressure contact with the outer peripheral surface of the photoreceptor drum 301 and forms a transfer nip with the photoreceptor drum 301 . The charging device 303 charges the outer peripheral surface of the photoreceptor drum 301. Exposure device 304 forms an electrostatic latent image on the outer peripheral surface of photoreceptor drum 301 . The developing device 1 develops the electrostatic latent image on the outer peripheral surface of the photoreceptor drum 301 into a toner image.

The image forming apparatus 100 also includes a fixing section 400. Fixing unit 400 includes a fixing roller 401 and a pressure roller 402. The fixing roller 401 has a built-in heater. The pressure roller 402 is in pressure contact with the fixing roller 401 and forms a fixing nip with the fixing roller 401 .

The sheet sent out from the paper feed cassette 200 enters the transfer nip. An image is printed on the sheet as it passes through the transfer nip. Specifically, the toner image on the outer peripheral surface of the photoreceptor drum 301 is transferred to the sheet. The sheet then enters the fusing nip and is heated and pressurized. As a result, the toner image is fixed on the sheet. The printed sheet that has passed through the fixing nip is discharged to the discharge tray ET.

<Configuration of developing device>
As shown in FIG. 2, the developing device 1 includes a developing container 10. As shown in FIG. The developer container 10 contains a one-component developer made of toner. Specifically, developer container 10 includes a support member 110 and a cover member 120. By combining the support member 110 and the cover member 120, the developer container 10 having an internal storage space is configured. The storage space of the developer container 10 stores a non-magnetic one-component developer consisting only of toner.

A stirring paddle SP is provided in the storage space of the developer container 10. The stirring paddle SP stirs the toner within the storage space. Note that toner is replenished from the toner container to the developer container 10 by a toner replenishing device (not shown).

The developer container 10 has an opening on the side where the photoreceptor drum 301 is arranged. The opening of the developer container 10 serves as a toner supply port to the photoreceptor drum 301 .

The developing device 1 includes a supply roller 11 and a developing roller 12. The supply roller 11 and the developing roller 12 are arranged in this order from the inside of the developing container 10 (that is, the storage space) to the outside. The developing roller 12 is arranged such that its outer circumferential surface 20 faces the outer circumferential surface of the supply roller 11 . Further, the developing roller 12 is arranged such that its outer circumferential surface 20 faces the outer circumferential surface of the photoreceptor drum 301 . In other words, the developing roller 12 is arranged between the supply roller 11 and the photosensitive drum 301. In other words, the supply roller 11 is arranged inside the developer container 10, and the developer roller 12 is arranged at the opening (toner supply port) of the developer container 10.

The supply roller 11 is rotatably supported by a support member 110. That is, the supply roller 11 is rotatably supported by the developer container 10. The supply roller 11 rotates in one direction (counterclockwise in FIG. 2). Further, the supply roller 11 carries the toner in the storage space on its outer peripheral surface. The supply roller 11 carries toner on its outer peripheral surface and rotates to supply the toner to the developing roller 12 .

The developing roller 12 is pressed against the photosensitive drum 301 with a predetermined pressure. Further, the developing roller 12 is rotatably supported by a support member 110. That is, the developing roller 12 is rotatably supported by the developing container 10. The developing roller 12 rotates in the same direction as the supply roller 11 (counterclockwise in FIG. 2). At the position where the supply roller 11 and the developing roller 12 face each other, the direction in which the outer circumferential surface of the developing roller 12 moves is opposite to the direction in which the outer circumferential surface of the supply roller 11 moves.

The developing roller 12 receives toner from the supply roller 11 and supports the toner on its outer peripheral surface 20 . The developing roller 12 carries toner on its outer peripheral surface 20 and rotates to supply the toner to the photoreceptor drum 301 . In order to efficiently move the toner from the developing roller 12 to the photoreceptor drum 301, it is preferable to apply a predetermined developing voltage to the developing roller 12.

The developing roller 12 has a rotating shaft (not shown) and a roller member (not shown) attached to the rotating shaft. The roller member rotates together with the rotating shaft. The roller member is cylindrical. For example, the roller member is a member in which a urethane coating is applied to the surface of a base material layer such as silicone rubber. Irregularities are formed on the outer peripheral surface of the roller member. That is, the developing roller 12 has irregularities on its outer peripheral surface 20. As a result, the toner is carried on the outer circumferential surface 20 of the developing roller 12. A toner layer is formed on the outer peripheral surface 20 of the developing roller 12 .

Here, the developing device 1 includes a regulating blade 13 . The regulation blade 13 is fixed to the developer container 10 at one end thereof when viewed from the direction of the rotation axis of the developer roller 12 . Further, the regulating blade 13 extends toward the developing roller 12 from the attachment point to the developing container 10 when viewed from the direction of the rotation axis of the developing roller 12 . A portion of the regulating blade 13 on the other end side opposite to the one end side (the side fixed to the developer container 10 ) contacts the outer circumferential surface 20 of the developing roller 12 . In other words, one end of the regulating blade 13 is a fixed end and is fixed to the developer container 10 . The other end of the regulating blade 13 opposite to the one end is a free end, and comes into contact with the outer circumferential surface 20 of the developing roller 12 .

The regulating blade 13 is a leaf spring. Specifically, the regulation blade 13 is a plate-shaped member made of metal. The regulating blade 13 has a thin plate shape and is made of a stainless steel plate. Note that the constituent material of the regulating blade 13 is not particularly limited.

The regulating blade 13 contacts the outer circumferential surface of the developing roller 12 at a position upstream in the rotational direction of the developing roller 12 from the position where the developing roller 12 and the photoreceptor drum 301 face each other. The regulating blade 13 comes into contact with the outer circumferential surface 20 of the developing roller 12 under a predetermined linear pressure (regulating pressure) and is bent. FIG. 3 shows the contact state of the regulating blade 13 with the outer circumferential surface 20 of the developing roller 12. For example, the free end side tip 30 of the regulating blade 13 is bent toward the side opposite to the outer peripheral surface 20 side of the developing roller 12 .

Note that the linear pressure of the regulating blade 13 against the outer circumferential surface 20 of the developing roller 12 is the contact pressure per unit length of the regulating blade 13 at the contact position between the outer circumferential surface 20 of the developing roller 12 and the regulating blade 13. The regulating blade 13 contacts the outer circumferential surface 20 of the developing roller 12 with a linear pressure of 20 N/m or more and 60 N/m or less. Further, the regulating blade 13 contacts the outer circumferential surface 20 of the developing roller 12 with a predetermined nip width. The nip width is the contact width between the outer circumferential surface 20 of the developing roller 12 and the regulation blade 13 in the circumferential direction of the developing roller 12 . In measurements using the prism 5, which will be described later, the nip width is the contact width between the outer circumferential surface 20 of the developing roller 12 and the flat surface 50 of the prism 5 in the circumferential direction of the developing roller 12. In FIG. 3, the nip width is indicated by "W".

By bringing the regulating blade 13 into contact with the outer circumferential surface 20 of the developing roller 12, excess toner on the outer circumferential surface 20 of the developing roller 12 is scraped off. As a result, the toner layer formed on the outer peripheral surface 20 of the developing roller 12 can be adjusted to have a uniform thickness. That is, the regulating blade 13 adjusts the layer thickness of the toner layer formed on the outer circumferential surface 20 of the developing roller 12 by contacting the outer circumferential surface 20 of the developing roller 12 . Further, the toner layer is charged by static electricity generated when the regulating blade 13 comes into contact with the toner layer.

Returning to FIG. 2, the developing device 1 includes a seal member 14. As shown in FIG. The seal member 14 is fixed to the support member 110 so as to be in contact with the outer peripheral surface 20 of the developing roller 12 . The seal member 14 closes the gap between the outer peripheral surface 20 of the developing roller 12 and the support member 110. Thereby, leakage of toner from the gap between the outer circumferential surface 20 of the developing roller 12 and the support member 110 can be suppressed. That is, leakage of toner from the inside of the developer container 10 to the outside can be suppressed.

<Outer peripheral surface of developing roller>
The charging properties, conveyance properties, and scraping properties of the toner carried on the outer circumferential surface 20 of the developing roller 12 depend on the surface shape (that is, surface roughness) of the outer circumferential surface 20 of the developing roller 12 . In order to keep all of the toner chargeability, transportability, and scrapability within target ranges, it is necessary to precisely control the surface shape of the outer peripheral surface 20 of the developing roller 12.

However, the regulating blade 13 is in contact with the outer peripheral surface 20 of the developing roller 12, and the developing roller 12 is used in this state. For this reason, for example, the shape of the outer circumferential surface 20 of the developing roller 12 is designed by focusing only on the surface roughness of the outer circumferential surface 20 of the developing roller 12, and the shape of the outer circumferential surface 20 of the developing roller 12 is formed as designed. Also, any one of the toner charging properties, conveying properties, and scraping properties may become insufficient. From this, it can be said that it is important whether the state of the outer peripheral surface 20 of the developing roller 12 when the regulating blade 13 is in contact with the outer peripheral surface 20 of the developing roller 12 is in the target state.

Therefore, when measuring the outer circumferential surface 20 of the developing roller 12 in the manufacturing process of the developing roller 12, a state in which the regulating blade 13 is in contact with the outer circumferential surface 20 of the developing roller 12 is reproduced. In other words, the developing roller 12 is manufactured so that the surface shape of the outer circumferential surface 20 of the developing roller 12 with the regulating blade 13 in contact with the outer circumferential surface 20 of the developing roller 12 has a target shape.

In the manufacturing process of the developing roller 12, the outer circumferential surface 20 of the developing roller 12 is measured under an environment as shown in FIG. FIG. 4 is a diagram schematically showing a method (measuring device) for measuring the outer circumferential surface 20 of the developing roller 12. In FIG. 4, elements necessary for measuring the outer circumferential surface 20 of the developing roller 12 are schematically shown.

Note that the method for measuring the outer circumferential surface 20 of the developing roller 12 is not particularly limited. When measuring the outer circumferential surface 20 of the developing roller 12, other measurement methods may be used as long as the state in which the regulating blade 13 is in contact with the outer circumferential surface 20 of the developing roller 12 can be reproduced.

A prism 5 is used to measure the outer circumferential surface 20 of the developing roller 12. In other words, the measuring device for measuring the outer peripheral surface 20 of the developing roller 12 includes the prism 5 as a component.

Prism 5 is a triangular prism having three planes that are non-parallel to each other. The prism 5 has an isosceles triangular shape when viewed from the side. Specifically, the prism 5 has a right isosceles triangular shape when viewed from the side. Note that the prism 5 corresponds to a "transparent member". The "transparent member" is not limited to the prism 5. A transparent member different from the prism 5 may be used to measure the outer peripheral surface 20 of the developing roller 12.

When measuring the outer circumferential surface 20 of the developing roller 12 , any one of the three mutually non-parallel planes of the prism 5 is pressed against the outer circumferential surface 20 of the developing roller 12 . In the following description, a plane pressed against the outer circumferential surface 20 of the developing roller 12 is designated by the reference numeral 50. The plane 50 of the prism 5 is a plane sandwiched between two mutually perpendicular planes in a side view, out of three mutually non-parallel planes of the prism 5.

The light source 6 is used to measure the outer circumferential surface 20 of the developing roller 12. The light source 6 emits light onto a plane different from the plane 50 among the three mutually non-parallel planes of the prism 5. The light from the light source 6 is incident on the plane. As the light source 6, an LED, a semiconductor laser, or the like may be used. In the following description, the reference numeral 51 is given to the plane of the prism 5 on which the light from the light source 6 is incident. Furthermore, in FIG. 4, light emitted from the light source 6 and traveling through the prism 5 is indicated by a broken line arrow. The plane 51 of the prism 5 is one of two surfaces that are perpendicular to each other when viewed from the side.

In the measurement of the outer circumferential surface 20 of the developing roller 12, the outer circumferential surface of the developing roller 12 is measured when light is incident on the plane 51 from a plane different from the planes 50 and 51 among the three mutually non-parallel planes of the prism 5. 20 and the plane 50 of the prism 5 is observed. In the following description, the surface of the prism 5 to be observed is designated by the reference numeral 52. The plane 52 of the prism 5 is the other surface that is different from one of the two surfaces that are perpendicular to each other when viewed from the side.

The plane 50 of the prism 5 is pressed against the outer circumferential surface 20 of the developing roller 12 in order to reproduce the state in which the regulating blade 13 is in contact with the outer circumferential surface 20 of the developing roller 12 . Thereby, the flat surface 50 of the prism 5 comes into contact with the outer circumferential surface 20 of the developing roller 12.

Note that the developing roller 12 has irregularities on the outer circumferential surface 20. That is, the developing roller 12 has concave portions and convex portions on the outer peripheral surface 20. Therefore, the entire area of the plane 50 of the prism 5 does not come into contact with the outer circumferential surface 20 of the developing roller 12 . Of the flat surface 50 of the prism 5, a region facing the convex portion (hereinafter referred to as a convex region) contacts the outer circumferential surface 20 of the developing roller 12, and a region facing the concave portion (hereinafter referred to as a concave region) contacts the outer circumferential surface 20 of the developing roller 12. ) does not contact the outer peripheral surface 20 of the developing roller 12. A gap (air) is created between the outer circumferential surface 20 of the developing roller 12 and the concave area of the flat surface 50 of the prism 5.

As a result, on the plane 50 of the prism 5, a difference occurs in the intensity of light depending on whether the area is a concave area or a convex area. In the concave region of the plane 50 of the prism 5, the light from the light source 6 is totally reflected. On the other hand, no gap occurs in the convex region of the plane 50 of the prism 5. Therefore, the light from the light source 6 is diffusely reflected in the convex regions of the plane 50 of the prism 5, and the light becomes weaker than in the concave regions.

By observing the plane 52 of the prism 5, the shadows (dark areas and bright areas) of the reflected light on the plane 50 can be detected, as shown in FIG. The convex region (the region of the plane 50 of the prism 5 that actually contacts the outer circumferential surface 20 of the developing roller 12) appears as a dark region. That is, a convex region can be detected. Note that FIG. 5 is a diagram schematically showing the results obtained by observing the plane 52 of the prism 5. In FIG. 5, dark areas are indicated by black circles.

By observing the plane 52 of the prism 5, the area of the plane 50 of the prism 5 that is actually in contact with the outer peripheral surface 20 of the developing roller 12 can be detected. Furthermore, the area of the detected region can be determined. That is, by observing the plane 52 of the prism 5, the contact area ratio, which will be described later, can be determined.

In measuring the outer circumferential surface 20 of the developing roller 12, the flat surface 50 of the prism 5 is pressed against the outer circumferential surface 20 of the developing roller 12 with a linear pressure of 50 N/m. Note that the regulating blade 13 contacts the outer circumferential surface 20 of the developing roller 12 with a linear pressure of 20 N/m or more and 60 N/m or less. Therefore, the linear pressure when pressing the flat surface 50 of the prism 5 against the outer peripheral surface 20 of the developing roller 12 is set to 20 N/m or more and 60 N/m or less. That is, in order to reproduce the state in which the regulating blade 13 is in contact with the outer circumferential surface 20 of the developing roller 12, the linear pressure when pressing the flat surface 50 of the prism 5 against the outer circumferential surface 20 of the developing roller 12 is 20 N/m or more and 60 N/m. It is set as below.

Then, when the flat surface 50 of the prism 5 is brought into contact with the outer circumferential surface 20 of the developing roller 12 with a linear pressure of 50 N/m, the ratio of the actual contact area to the nip area is determined. Nip area is the product of nip width and nip length. The nip width here is the contact width between the outer circumferential surface 20 of the developing roller 12 and the flat surface 50 of the prism 5 in the circumferential direction of the developing roller 12 . The nip length is the contact length between the outer circumferential surface 20 of the developing roller 12 and the flat surface 50 of the prism 5 in the direction of the rotation axis of the developing roller 12 .

Further, the actual contact area is the area where the outer circumferential surface 20 of the developing roller 12 and the flat surface 50 of the prism 5 actually come into contact. That is, the actual contact area is the area of the convex region of the plane 50 of the prism 5. Note that the ratio of the actual contact area to the nip area when the flat surface 50 of the prism 5 is brought into contact with the outer peripheral surface 20 of the developing roller 12 with a linear pressure of 50 N/m corresponds to the "contact area ratio", and in the following explanation, It is simply called the contact area ratio.

Here, a target range (an upper limit value and a lower limit value) of the amount of toner carried and conveyed on the outer circumferential surface 20 of the developing roller 12 is experimentally or empirically set in advance by the manufacturer of the developing device 1. Note that the toner conveyance amount is the amount of toner per unit area on the outer peripheral surface 20 of the developing roller 12. For example, a predetermined image is developed, and toner is collected from the outer peripheral surface 20 of the developing roller 12 during development on the downstream side in the rotational direction of the developing roller 12 from the nip position with the regulation blade 13, and the toner is collected from the area to be collected. The toner conveyance amount (M/S) is determined from the area S (m ² ) and the collected toner amount M (g). If the amount of toner conveyance deviates from the target range, image quality may deteriorate.

Therefore, a target range (an upper limit value and a lower limit value) of the contact area ratio within which the toner conveyance amount falls within the target range is set in advance. Specifically, the target range of the contact area ratio is set to 10% or more and 20% or less. In the manufacturing process of the developing roller 12, development is performed so that when the flat surface 50 of the prism 5 is brought into contact with the outer peripheral surface 20 of the developing roller 12 under a linear pressure of 50 N/m, the contact area ratio is 10% or more and 20% or less. Roller 12 is manufactured. Note that the fact that the toner conveyance amount falls within the target range by setting the target range of the contact area ratio to 10% or more and 20% or less is experimentally or empirically determined in advance by the manufacturer of the developing device 1.

In this embodiment, by manufacturing the developing roller 12 as described above, the developing roller 12 has a contact area when the outer peripheral surface 20 of the developing roller 12 is brought into contact with the flat surface 50 of the prism 5 at a linear pressure of 50 N/m. The outer peripheral surface 20 has irregularities with a ratio of 10% or more and 20% or less. The developing roller 12 carries and conveys the toner while the regulating blade 13 is in contact with its outer peripheral surface 20 under a linear pressure of 20 N/m or more and 60 N/m or less.

By defining the formation conditions of the outer circumferential surface 20 of the developing roller 12 based on the contact area ratio with the prism 5, it is possible to suppress variations in the performance of the developing roller 12. Thereby, the amount of toner conveyed by the developing roller 12 can be reliably controlled. In other words, it is possible to prevent the amount of toner conveyed by the developing roller 12 from deviating from the target range.

Further, by using the prism 5 as a transparent member brought into contact with the outer circumferential surface 20 of the developing roller 12, the state (surface shape) of the outer circumferential surface 20 of the developing roller 12 can be easily measured.

Hereinafter, an experiment conducted to confirm the effects of the above embodiment (effects regarding performance variations of the developing roller 12) will be described.

In the confirmation experiment, a developing roller with an outer diameter of 16 mm and a coating layer surface (outer peripheral surface) with MD-1 hardness of 40° or more and 50° or less was prepared. In addition, a stainless steel plate with a bent tip was prepared as a regulating blade.

Here, as a developing roller, a plurality of developing rollers were prepared in which the formation conditions (surface roughness) of the outer circumferential surface were defined by the contact area ratio with the prism. In addition, a plurality of developing rollers were prepared in which the formation conditions (surface roughness) of the outer circumferential surface were defined by the ten-point average roughness Rz.

Then, the amount of toner conveyed was confirmed for each developing roller. At this time, the flat surface of the regulating blade was brought into contact with the outer peripheral surface of the developing roller so that the state shown in FIG. 3 was achieved. Further, the linear pressure (regulating pressure) of the regulating blade against the outer circumferential surface of the developing roller was set to 20 N/m or more and 60 N/m or less. The toner is positively charged and has a particle size of 8.3 μm.

FIG. 6 shows the experimental results (relationship between the contact area ratio between the outer peripheral surface of the developing roller and the prism and the amount of toner conveyed) using a developing roller in which the conditions for forming the outer peripheral surface were defined by the contact area ratio with the prism. Further, FIG. 7 shows the experimental results (relationship between the ten-point average roughness Rz of the outer circumferential surface of the developing roller and the amount of toner conveyed) using a developing roller in which the outer circumferential surface formation condition was defined by the ten-point average roughness Rz.

As shown in FIG. 6, when using a developing roller that has unevenness on its outer peripheral surface with a contact area ratio of 10% to 20% with the prism, the toner conveyance amount (M/S) is within the target range (upper limit value and the lower limit value). On the other hand, it was confirmed that if the contact area ratio between the outer peripheral surface of the developing roller and the prism exceeds 20%, the toner conveyance amount (M/S) may fall below the lower limit of the target range. did it. From this, it can be said that it is preferable to use a developing roller having irregularities on the outer peripheral surface such that the contact area ratio with the prism is 10% or more and 20% or less.

In addition, as shown in FIGS. 6 and 7, the developing roller whose outer circumferential surface formation condition is defined by the contact area ratio with the prism is compared to the developing roller whose outer circumferential surface forming condition is defined by the ten-point average roughness Rz. It was confirmed that the variation was reduced. If the forming conditions for the outer circumferential surface of the developing roller are specified by the ten-point average roughness Rz, there will be large variations. Even if the outer circumferential surface of the developing roller is formed to have a thickness of 3 μm to 9 μm), there is a possibility that the toner conveyance amount (M/S) will be out of the target range. From this, it can be said that the amount of toner conveyance (M/S) can be reliably controlled by using a developing roller whose outer circumferential surface formation conditions are defined by the contact area ratio with the prism.

The embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the claims rather than the description of the above embodiments, and further includes all changes within the meaning and range equivalent to the claims.

1 Developing device 5 Prism (transparent member)
10 Developing container 12 Developing roller 13 Regulating blade 20 Outer peripheral surface 100 Image forming device 301 Photosensitive drum (image carrier)

Claims (4)

a developer container containing a one-component developer made of toner;
It is rotatably supported by the developer container, is disposed facing the image carrier, has an uneven outer circumferential surface, and rotates with the toner carried on the outer circumferential surface. a developing roller that supplies the toner;
a regulating blade that adjusts the layer thickness of the toner layer formed on the outer circumferential surface by contacting the outer circumferential surface;
The developing roller is configured such that when the flat surface of a transparent member is brought into contact with the outer peripheral surface under a linear pressure of 50 N/m, the outer peripheral surface and the flat surface actually contact with respect to the nip area between the outer peripheral surface and the flat surface. The developing device has unevenness on the outer circumferential surface such that a contact area ratio, which is a ratio of the area of the contact area, is 10% or more and 20% or less. The developing device according to claim 1, wherein the regulating blade contacts the outer circumferential surface with a linear pressure of 20 N/m or more and 60 N/m or less. The transparent member is an isosceles triangular prism in side view,
The surface sandwiched between the two mutually perpendicular surfaces of the prism is brought into contact with the outer peripheral surface with a linear pressure of 50 N/m, and the outer peripheral surface when light is incident on one of the two mutually perpendicular surfaces. Claim 1: The contact area ratio determined by observing the state of contact with the plane from the other surface other than the one surface of the two mutually perpendicular surfaces is 10% or more and 20% or less. Or the developing device according to 2. An image forming apparatus comprising the developing device according to claim 1 or 2.

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