JPH0511584A - Toner thin layer blade for one-component dry developing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a toner thin layer blade that can obtain high image quality with a simple configuration in a one-component dry developing device that visualizes an electrostatic latent image with frictionally charged toner. And [Structure] A thin toner layer blade 7 is formed by a leaf spring 6 and an elastic blade 5, and the elastic blade 5 is formed with a Shore hardness of 40 degrees or more and 70 degrees or less and a curvature radius of a contact surface 5a of 0.3 mm or more and 3 mm or less. Therefore, due to the range of hardness,
A sufficient triboelectric charge amount and a uniform toner layer thickness in the axial direction of the developing roller 2 are obtained, and even if the developing roller 2 and the elastic blade 5 are not parallel to each other, the developing roller 2 and the elastic blade 5 are non-parallel due to the restriction of the radius of curvature range. The fluctuation of the contact width of No. 5 is small, and a stable and uniform thin layer of toner can be obtained. As a result, a high-quality visible image can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner thin layer blade of a one-component dry developing device for visualizing an electrostatic latent image formed on a latent image carrier using a one-component developer.

[0002]

2. Description of the Related Art A one-component dry developing device used in an electronic copying machine, an electrostatic recording device, or other various recording devices deteriorates like a two-component developing device using a carrier in addition to toner. Since there is no particular need to consider the mixing ratio between the carrier and the toner, the components such as the toner concentration detection sensor, the toner replenishment control mechanism, the toner and the carrier stirring mechanism are not required, and the device configuration can be simplified. There are advantages.

In this case, the toner of the one-component developer has a relatively high volume resistivity, for example, from 10 ¹⁰ Ωcm to 10 ¹³
Toner of Ωcm or more is used, and this toner is forcibly charged to a predetermined polarity before development. Then, it is general that a triboelectrification member gives triboelectrification charge to the toner.

The triboelectrification member is composed of a toner carrier for carrying the toner, a toner thin layer blade for uniformly thinning the toner on the toner carrier, or a charging member exclusively used for the triboelectric charging of the toner. Has been formed. Among them, the one in which the toner is thinned by using a toner thinning blade and the toner is triboelectrically charged has the simplest configuration and the cost can be reduced.

A conventional toner thinning blade will be described below with reference to FIGS. 6 to 11.

In FIG. 6, an elastic blade 11 made of rubber or the like is adhered to a member having a high rigidity such as a developing butt 8, and the elastic blade 11 is pressed against the developing roller 2 with a predetermined pressure by its elasticity.

In FIG. 7, a blade 14 made of a resin or metal having a relatively high hardness is elastically supported on a blade guide 13 via a coil spring 12, and the blade 14 is pressed against the developing roller 2 at a constant pressure. Is.

In FIG. 8, a metallic leaf spring 15 is attached to the developing butt 8 and the leaf spring 15 is pressed against the developing roller 2 at a constant pressure by its elasticity.

In FIG. 9, a thin toner layer blade 18 is formed by a leaf spring 17 and a rubber material 16 attached to the tip thereof, and at least one edge portion of the tip of the rubber material 16 is provided with R, and the edge portion is The elastic force of the leaf spring 17 presses the developing roller 2 at a constant pressure.

[0010]

However, such a conventional toner thin layer blade has the following problems.

In the structure shown in FIG. 6, when the elastic blade 11 is pressed against the developing roller 2 for a long period of time, a creep phenomenon occurs, the pressing force gradually decreases, the ability to frictionally charge the toner decreases, and the image quality gradually increases. There was a problem of deterioration.

In the structure shown in FIG. 7, since the precision of the pressure contact surface and the edge portion of the blade 14 must be increased, the cost is increased, and when the precision is insufficient, the developing roller 2 is moved in the axial direction. The toner layer thickness unevenness and the toner triboelectric charge amount unevenness occur, resulting in image density unevenness and partial background stain. Further, since a force in the rotation direction of the developing roller 2 is applied to the pressure contact surface of the blade 14, the blade 14 tilts in the blade guide 13 and the blade 14 does not slide smoothly in synchronization with the deflection due to the rotation of the developing roller 2. Occurs. As a result, toner layer thickness unevenness and triboelectric charging unevenness are generated in synchronization with the rotation cycle of the developing roller 2, which causes a problem that image density unevenness and background stain occur.

In the structure shown in FIG. 8, the parallelism between the leaf spring 15 and the developing roller 2 is limited, and it is extremely difficult to make the toner layer thickness uniform. There is a problem that uneven image density and background stains occur. Particularly, in this case, there is a problem in that toner is apt to adhere and streaks occur in an image.

In the structure shown in FIG. 9, the contact between the thin toner layer blade 18 and the developing roller 2 is made uniform by the elastic force of the leaf spring 17 and the rubber material 16 mounted on the leaf spring 17, so that the toner layer thickness is reduced. It can be made relatively uniform, but FIG.
As shown in 0, when the shaft center line 19 of the developing roller 2 and the contact line 20 where the tip of the thin toner layer blade 18 contacts the developing roller 2 are not parallel, the thin toner layer blade 18 and the developing roller 2 Fig. 9 shows the contact width with the A position.
11a in FIG. 11 at the B position.
It becomes wider as indicated by 0b. As a result, even if the toner layer thickness is uniform, the R of the thin toner layer blade 18 is
Since the width of contact between the developing roller 2 and the developing roller 2 varies in the axial direction of the developing roller 2, the triboelectric charge amount of the toner becomes non-uniform in the print width direction, and scumming, uneven line width, and image density occur in the print width direction. There was a problem of causing unevenness.

The present invention solves the above problems, and an object thereof is to provide a toner thin layer blade of a one-component dry developing device having a simple structure and high image quality and high reliability.

[0016]

In order to achieve the above object, the present invention comprises a thin toner layer blade formed of a leaf spring and an elastic blade attached to the leaf spring, and the elastic blade has a Shore hardness of 40. The contact surface with the developing roller has a radius of curvature of 0.3 mm or more and 3 mm or less.

[0017]

According to the present invention, as described above, by setting the hardness of the elastic blade to the Shore hardness of 40 degrees or more, the toner layer thickness capable of obtaining a sufficient triboelectric charge amount can be obtained.
By setting the degree to be less than or equal to a value, it is possible to obtain a uniform toner layer thickness in the axial direction of the developing roller. Also, the radius of curvature of the contact surface of the elastic blade with the developing roller is 0.3 mm or more and 3 mm or more.
Due to the following, even if the mounting angle of the toner thin layer blade varies, or even when the axial center line of the developing roller and the elastic blade are not parallel, the elastic blade is always in contact with the developing roller with the same radius of curvature. The fluctuation of the contact width between the developing roller and the elastic blade is reduced, and a stable and thin toner layer can be obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in the figure, the toner 4 carried by the toner replenishing roller 3 is charged by frictional charging between the toner replenishing roller 3 and the developing roller 2 which is in contact with the toner replenishing roller 3 and is rotated, and thus the developing roller is charged. It adheres to the surface of 2.
The adhered toner 4 is rotated by the developing roller 2 in the direction of the arrow, and a leaf spring 6 and an elastic blade 5 mounted on the leaf spring 6 are attached.
The toner is conveyed to a thin toner layer blade 7 composed of and is pressed against the developing roller 2 by the thin toner layer blade 7 to be friction-charged to a higher level and to form a uniform thin layer. Then, the developing roller 2 and the drum-shaped electrostatic latent image carrier 1 (hereinafter, referred to as a photoconductor) are brought close to or in contact with each other to a developing area where they face each other, and the toner 4 on the developing roller 2 is conveyed.
Part of the toner adheres to the electrostatic latent image portion on the photoconductor 1 to make the electrostatic latent image visible. The remaining toner returns to the toner replenishing roller 3 as the developing roller 2 rotates, and a part of the toner is scraped off by the toner replenishing roller 3, but most of the toner is not scraped off but is simply disturbed, and the toner is reciprocated. It passes through the contact portion and adheres to the surface of the developing roller 2.

The above steps are repeated to perform the developing action. The toner thin layer blade 7 is formed by integrally molding a leaf spring 6 and an elastic blade 5 made of rubber or the like.
Is fixed to the developing butt 8 with screws 9 or the like so as to follow the rotation of, and the elastic blade 5 is pressed against the developing roller 2 with a predetermined force.

The elastic blade 5 has a Shore hardness of 40 degrees to 70 degrees and has a contact surface 5a with the developing roller 2.
Has a radius of curvature of 0.3 mm or more and 3 mm or less.

The elastic blade 5 is made of a rubber material such as urethane rubber, silicone rubber, fluorine rubber, natural rubber, SBR, NBR. When the toner 4 is charged in the negative polarity, the silicone rubber has the largest charge amount. When the toner 4 is charged to the positive polarity, the fluorine rubber has the highest charge amount, which is preferable, and an image with high contrast and no background stain is obtained.
Further, when other rubber materials were used, the charge amount became low regardless of the polarity of the toner 4 charged, resulting in an image with many background stains and uneven density.

Even in such a case, the toner 4 is used in the case of a silicone-modified urethane rubber, a quartz powder, or a rubber material mixed with hydrophobically or hydrophilically treated silica, that is, a material containing at least a silicon component or a fluorine component. It could be sufficiently tribocharged.

Next, referring to FIG. 3, the contact surface 5 of the elastic blade 5 is shown.
3 shows a layer thickness distribution of the toner 4 in the axial direction of the developing roller 2 with the hardness of the elastic blade 5 as a parameter when the radius of curvature of a is 1.0 mm. Further, FIG. 4 shows a distribution of the charge amount of the toner 4 in the axial direction of the developing roller 2 using the hardness of the elastic blade 5 as a parameter when the radius of curvature of the contact surface 5a is 1.0 mm.

As is apparent from FIGS. 3 and 4, when the hardness is 30 degrees, the layer thickness of the toner 4 becomes too thick, so that the toner 4 is not sufficiently rubbed between the elastic blade 5 and the developing roller 2, and the toner is charged. The amount decreased and the image quality became dirty. When the hardness is 80 degrees, the layer thickness unevenness of the toner 4 in the axial direction of the developing roller 2 becomes large, and the layer thickness of the toner 4 becomes lower than 0.4 mg / cm ² on average, and the saturated image density decreases. did.

Next, FIG. 5 shows the relationship between the radius of curvature of the contact surface 5a of the elastic blade 5 and the layer thickness of the toner 4 with the hardness of the elastic blade 5 as a parameter. Area A is a condition under which good image quality with high background saturation and no image unevenness and high saturation density is obtained. The area B is in a state in which the elastic blade 5 is in planar contact with the surface of the developing roller 2 and unevenness of the layer thickness of the toner 4 occurs in correspondence with the slight unevenness of the developing roller 2. The thickness became too thick and the background was stained.
In the area C, the contact surface 5a of the elastic blade 5 is abraded in the printing test of about 3000 sheets, and the fluctuation of the layer thickness of the toner 4 and the charge amount of the toner 4 becomes large, and the occurrence of background stain and the increase of saturation density occur. However, this causes an increase in toner consumption. Further, even in the initial stage of the printing test, if the hardness is 60 degrees or more, the layer thickness of the toner 4 becomes too thin to obtain a sufficient saturation density. In the area D, the toner 4 is too thick to cause background stain, and in the area E, the toner 4 is too thin to secure the saturation density.
As shown in FIG. 4 and FIG. 4, the thin layer unevenness becomes large and the image unevenness becomes large.

[0027]

As is apparent from the above description of the embodiments, according to the present invention, by setting the hardness of the elastic blade to a Shore hardness of 40 degrees or more, a toner capable of obtaining a sufficient triboelectric charge amount can be obtained. By obtaining a layer thickness of 70 degrees or less, it is possible to obtain a uniform toner layer thickness in the axial direction of the developing roller. Further, by setting the radius of curvature of the contact surface of the elastic blade with the developing roller to 0.3 mm or more and 3 mm or less, even if the mounting angle of the toner thin layer blade varies, or the axial center line of the developing roller and the toner thin layer blade Even when and are not parallel, since the toner thin layer blade is always in contact with the developing roller with the same radius of curvature, the variation in the contact width between the developing roller and the toner thin layer blade is small,
It is possible to obtain a stable and uniform thin layer of toner.

As described above, according to the present invention, it is possible to provide a toner thin layer blade of a one-component dry developing device having a simple structure and high image quality and high reliability.

In this embodiment, the non-magnetic one-component type electrophotographic apparatus which does not use a magnet for the developing roller has been described. However, a magnet is used for the developing roller and a magnetic one-component type toner is used for the toner. However, the same effect can be obtained.

Further, it can be widely applied to various types of printing apparatuses other than the electrophotographic apparatus, for example, an electrostatic printer, a photosensitive paper or an electrostatic recording paper in a printing process for forming and developing an electrostatic latent image on a dielectric. It can also be used in copiers and printers in the process of forming and developing an electrostatic latent image.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of a toner thin layer blade of a one-component dry developing device according to an embodiment of the present invention.

FIG. 2 is a side view of the main part.

FIG. 3 is a characteristic diagram showing the toner layer thickness distribution in the axial direction of the developing roller with the hardness of the elastic blade as a parameter.

FIG. 4 is a characteristic diagram showing a toner charge amount distribution in the axial direction of the developing roller with the hardness of the elastic blade as a parameter.

FIG. 5 is a relationship diagram showing the relationship between the radius of curvature of the contact surface of the elastic blade and the layer thickness of the toner, with the hardness of the elastic blade as a parameter.

FIG. 6 is a side view of a main portion of a toner thin layer blade of a conventional one-component dry developing device.

FIG. 7 is a side view of a main part of a toner thin layer blade of another one-component dry developing device.

FIG. 8 is a side view of an essential part of a toner thin layer blade of another one-component system dry developing device.

FIG. 9 is a side view of a main part of a toner thin layer blade of another one-component dry developing device.

FIG. 10 is a perspective view illustrating the same problem state.

FIG. 11 is a side view of the same.

[Explanation of symbols]

2 developing roller 4 toner 5 Elastic blade 5a Contact surface 6 leaf spring 7 Toner thin layer blade

Claims (3)

[Claims] 1. A thin leaf toner blade of a one-component dry developing device for frictionally charging a toner to a predetermined polarity to visualize an electrostatic latent image with the charged toner is attached to a leaf spring and the leaf spring. A one-component dry developing device formed by an elastic blade, the hardness of the elastic blade is set to a Shore hardness of 40 degrees or more and 70 degrees or less, and the radius of curvature of the contact surface with the developing roller is set to 0.3 mm or more and 3 mm or less. Toner thin layer blade. 2. A toner thin layer blade for a one-component dry developing apparatus according to claim 1, wherein the elastic blade is formed of a rubber material containing at least a silicon compound. 3. A toner thin layer blade for a one-component dry developing apparatus according to claim 1, wherein the elastic blade is formed of a rubber material containing at least a fluorine compound.