JPS63304277A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To enable always uniform and stable layer thickness control while preventing the breaking and chipping of the peak parts of surface roughness by using a toner carrier having a rough surface consisting of combinations of 1st and 2nd roughness components to constitute a developing device. CONSTITUTION:The surface of the toner carrier 2 of the device for executing the layer thickness control of a dry developing toner by means of a layer thickness control member 3 is formed of the rough surface including the 1st and 2nd roughness components 10, 20. The 1st roughness components 10 are formed at micropitch intervals by nearly unifying the height of the peak parts 11p in contact with the layer thickness control member 3 and are positioned on the upper side of the average roughness line X obtd. by averaging the roughness distribution over the entire rough surface. The 2nd roughness components 20 have the pitch intervals 20pi larger than the pitch intervals of the 1st roughness components 10 and the average depth 22b of the valley parts 22 thereof is set in the range from the min. grain size to the max. grain size of the toner contributing substantially to the development. Said components are positioned on the lower side of the average roughness line X obtd. by averaging the roughness distribution over the entire rough surface. The stable layer thickness control always under the uniform pressurized contact force is thereby executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic developing device using a dry developing toner. The present invention relates to an electrophotographic developing apparatus configured to perform the above.

``Prior Art'' Conventionally, as an electrophotographic developing device using dry developing toner, a bias voltage is applied to a developing position without bringing a single layer of toner carried on a toner carrier into direct contact with a latent image holding surface. A so-called non-contact development method is often used in which the toner is selectively caused to fly due to the electric field effect of voltage. In such a non-contact development method, it is necessary to set the thickness of the toner layer to be less than the development interval between the toner and the latent image holding surface.
It is necessary to precisely regulate the thickness of a thin toner film, and one method for regulating the thickness of such a layer is to provide a magnetic blade or the like at a non-contact position with respect to the toner carrier to further regulate the toner thickness. There is a device in which a toner layer thickness regulating member having an elasticity of 100% is brought into light contact with a toner carrier, and the contact pressure is used to form a uniform and thin toner layer.

However, in such an apparatus, if the fluidity of the toner stored in the hopper decreases due to the influence of the external environment such as humidity, or if the toner aggregates, a toner pool or the like will be formed upstream of the layer thickness regulating member. If the toner is further undulated after the layer thickness has been regulated due to the toner accumulation, white streaks or the like occur, making it difficult to perform good development.

In order to eliminate such drawbacks, the surface of the toner carrier that comes into contact with the layer thickness regulating member has been roughened to have minute irregularities, thereby increasing the frictional force at the contact position of the layer thickness regulating member and increasing the frictional force at the contact position of the layer thickness regulating member. A technique has been proposed in which a vibrating force is applied to a toner pool to facilitate loosening of aggregated toner, thereby making it possible to make the toner even more uniform after controlling the layer thickness. (Japanese Patent Application No. 54-18453) As a method for roughening the surface of such a toner carrier, for example, the surface of a cylindrical tube formed by drawing is subjected to sandblasting or bead blasting using irregularly shaped particles or regular shaped particles. By doing this, minute irregularities are formed, and
Various developing devices have been proposed in which the average roughness and pitch of the surface of the cylindrical toner carrier (hereinafter referred to as sleeve) can be controlled by appropriately selecting the particle size and spraying pressure for the above-mentioned blasting. An example of this is shown in Figure 3 (B) (
As shown in C), since the surface is roughened by the mechanical process of collision of particles, the uneven portion 50, the EiO height, especially the height of each peak stp and etp are random, and the height of each peak is random. The shapes of the peaks 51p and 81p also become extremely sharp.

In addition, in the case of an apparatus that forms a single layer of toner by providing a non-contact layer thickness regulating member on the toner carrier, it is necessary to reduce the uneven pitch interval in order to obtain a thin layer of 0.1-IJL thickness.
In order to obtain such a surface, it is necessary to devise the setting conditions of the layer thickness regulating member and the surface treatment of the toner carrier.

On the other hand, when regulating the layer thickness by bringing a toner layer thickness regulating member into contact with the sleeve having the above-mentioned surface shape, shear stress exerted by pressure contact of the layer thickness regulating member and rotation of the sleeve causes the peak portions 51p, 81p. When the sleeve is broken, the broken and missing portion is mixed into the toner layer, which has a negative effect on image formation, and the pressing force applied to the peaks 51p and 61p becomes large, causing wear on the sleeve surface. However, a problem has arisen in that the effect of surface roughening cannot be stably obtained over many years.

In order to eliminate such drawbacks, the sleeve surface roughened by sandblasting is treated with alumite to harden the surface irregularities, and the alumite coating gives the sharpened peaks a rounded appearance. is proposed.

(Unexamined Japanese Patent Publication No. 58-570!4) "Problems to be Solved by the Invention" However, the irregularities 50 mechanically treated in this way,
In the method of forming an alumite or other coating layer on 80,
If the thickness of the coating layer is too thin, the effect of hardening will not be achieved smoothly, and the top portions 51p and 81p will be missing, and if the coating layer is too thick, the bottoms 52 and 82 will be This causes the problem that the effect of forming surface irregularities is halved, and adjusting the film thickness is extremely troublesome.

Furthermore, in a developing device that uses a bias voltage to transfer the toner to the latent image holding surface, if the sleeve surface is coated with alumite, which is an insulating material, it becomes difficult to transfer the toner, and the toner is not formed. A problem arises in that the image becomes faint.

Furthermore, when the surface irregularities become hard, wear occurs on the side of the layer thickness regulating member that is in contact with the sleeve surface, making it impossible to stably regulate the layer thickness over a long period of time.

In view of such prior art, the present invention provides contact and
A thin layer can be formed regardless of non-contact, and layer thickness can be controlled stably with uniform pressure while preventing breakage or chipping of the tops of the surface irregularities, and the effect of the roughening can be maintained for a long time. It is an object of the present invention to provide an electrophotographic developing device that can be stably obtained over time.

Another object of the present invention is to provide an electrophotographic developing device that can achieve the above effects without applying a film treatment to the uneven surface portion formed on the sleeve surface.

In order to achieve this technical problem, the present invention provides a layer that faces the surface of the toner carrier 2 in contact or non-contact, as shown in FIG. 1, for example. In a device that regulates the layer thickness of dry developing toner using a thickness regulating member 3, it is an essential component that the surface of the toner carrier 2 is formed with a rough surface containing at least the first and second roughness components described below. .

(2) The first roughness component 10 is formed at minute pitch intervals with the heights of the top tips in contact with the layer thickness regulating member 3 being almost the same, and preferably, the first roughness component 10 is substantially the same as the It is characterized by being located above the roughness average line X obtained by averaging the roughness distribution over the entire rough surface.

The first roughness component 10 is formed mainly for the purpose of increasing the original vibration resistance with the layer thickness regulating member 3 and making the pressure contact force uniform, as described in the function below. Therefore, it is preferable to minimize the pitch interval and increase the number of contacts between the peak lip and the layer thickness regulating member 3 as much as possible.

Further, it is sufficient that the first roughness component 1O has a depth that does not wear out during long-term use.

Furthermore, since the primary purpose of the first roughness component 10 is to loosen and transfer the toner by rubbing against the layer thickness regulating member 3, its ten-point average roughness is substantially effective for development. It is preferable that the contributing minimum toner particle size be less than or equal to 5 JLm, specifically less than 5 JLm.

(2) The second roughness component 20 has a pitch interval 20pi larger than the pitch interval of the first roughness component 10, and the average depth 22b of the valley portion 22 is substantially the same as that of the toner contributing to development. The range from the minimum particle size to the maximum particle size, specifically 5 to 20
IL■, and preferably the second roughness component 20 is located substantially below the roughness average line X obtained by averaging the roughness distribution over the entire rough surface. It is characterized by

The second roughness component 20 is generally used to increase the conveying force while biting the toner particles into the troughs 22, so the pitch interval 20p i is 5.
A rough pitch interval of 20 pi of about 0 to 500 JL■ may be sufficient.

"Action" According to this technical means, the effects of the present invention described later can be smoothly achieved by causing each of the assembled components to individually produce different effects.

In other words, the first roughness component 10 is such that (in the case of an apparatus adopting a configuration in which the layer thickness regulating member 3 contacts the surface of the toner carrier), the heights of the peaks ttp in contact with the layer thickness regulating member 3 are almost the same and are very small. Because they are formed at pitch intervals, a large number (at least two or more) of the peaks ttp come into contact with the contact surface of the layer thickness regulating member 3, and a uniform pressure contact force is obtained, which stabilizes the frictional force. Periodic minute vibrations are obtained, which facilitates loosening of toner with poor fluidity or agglomerated toner.

Moreover, the roughness component is at minute pitch intervals and at the peak portion 11P.
Since the heights are almost the same, the shear stress acting on the peak lip is greatly reduced by the sliding of the layer thickness regulating member 3, and breakage of the peak lip is prevented.

Further, the second roughness component 20 has a pitch interval of 20 pi which is larger than the pitch interval of 20 pi of the first roughness component IO, and the average depth 22b of the valley portion 22 is the minimum of the toner that substantially contributes to development. Because it was set in the range from the particle size to the maximum particle size,
In other words, since the toner can be held in the valley portion 22 without completely sinking into the valley portion 22, the peak portion 11 of the first roughness component. Even if the toner whose layer thickness is regulated slips due to the contact pressure with the layer thickness regulating member 3 on the surface of the trough 20, the troughs 22 of the second roughness component 20 will firmly hold the slipped toner and reliably It becomes possible to transport the

Therefore, according to the present invention, by the action of each of the roughness components, it is possible to precisely and stably regulate the layer thickness of the toner, and it is also possible to reliably transport the toner to the development position.

The plurality of roughness components can be obtained by forming surface irregularities through mechanical treatment such as blasting, as described later, and then by acid treatment or Since it can be easily formed by dissolving and smoothing with alkali treatment, it is several steps easier to manufacture and handle than alumite treatment.

Incidentally, the present invention relates to an apparatus in which the layer thickness regulating member is not in contact with the toner carrier, and substantially the same effect as described above can be obtained, and the present invention is naturally applicable to such an apparatus. obtain.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. It's nothing more than that.

FIG. 2 shows a schematic configuration of an electrophotographic developing apparatus according to an embodiment of the present invention.

Reference numeral 1 denotes a photosensitive drum having a photoconductive layer formed on its surface, and an electrophotographic peripheral device (not shown) for image formation is arranged along the rotation direction.

2 is a non-magnetic sleeve containing a fixed magnet assembly 5;
As will be described later, the outer peripheral surface has a first roughness component 10 and a second roughness component 10.
The surface is roughened to have a roughness component 20 of .

By rotating the sleeve 2 at a predetermined circumferential speed in the direction of the arrow, the high-resistance magnetic toner negatively charged due to mutual friction inside the toner container B is supported on its circumferential surface and transported to the development position. It is possible to perform predetermined development.

Further, a DC pulse generation circuit 7 is connected to the sleeve 2, and by applying a switching DC bias to the developing area between the sleeve 2 and the photoreceptor drum 1, the sleeve 2 is
Development is carried out by selectively flying the toner supported on the latent image holding surface of the photoreceptor drum 1. In this embodiment, polyethylene, magnetic powder, charge control agent, silica, etc. are mixed in a predetermined weight part. A magnetic toner formed by using a magnetic toner having an average particle size of 10 μm and a toner particle size range of 5 to 20 μm was used.

Reference numeral 3 denotes a toner thickness regulating member 3 disposed on the outlet side of the toner container B on the upstream side of the development position, which is made of a metal thin plate elastic member, and whose free end side is bent at a predetermined curvature. 3a is brought into contact with the circumferential surface of the sleeve 2 with a predetermined pressing force, while the proximal end side is extended toward the toner container B side at a predetermined penetration angle, and the outer wall surface of the support member 8 formed at the outlet portion of the toner container 8 be fixed to.

Next, the surface shape of the sleeve 2 will be explained according to the manufacturing order.

First, the surface of an aluminum cylindrical tube is formed into a predetermined diameter by drawing and has a surface roughness as shown in FIG. After forming a rough surface as shown in CB), 12
~0.5 min ~3 in ~13% caustic soda alkaline solution
After being immersed for a minute and treated with alkali, it was washed with water to form a rough surface as shown in FIG. 3(A).

The same effect can be obtained by using sandpaper treatment or bead blasting for the sandblasting treatment, or by using dilute sulfuric acid, dilute hydrochloric acid, other acids, or an alkali other than caustic soda for the alkali treatment.

When the shape of such a rough surface is measured in detail, it is found that the first roughness component 10 is above the roughness average line obtained by averaging the roughness distribution over the entire rough surface, and the first roughness component 10 is below the roughness average line. Second roughness component 2
0 are substantially present and the first roughness component 1
The average pitch and distribution of 0 is 1.8±1.8 (2σ) 1, and the 10-point average roughness is 2.8 1, both of which are the minimum toner particle diameter (51L) that substantially contributes to development. It is as follows.

Also, the average pitch and distribution of the second roughness component is 380±210
(2σ) end l, and the average depth 22b and distribution of the valley portion 22 are 11.1±E1. O(2σ)IL is within the end layer and toner particle size range 5-20.

In order to confirm the effect of this example, the sleeve 2 shown in FIG. 3 CB) was subjected to the sandblasting process.
(Comparative Example 1), Figure 3 (C
), and the sleeve 2 (Example) according to the embodiment of the present invention shown in FIG. 3(A) were used for actual development. When 1000 sheets of an original with many blank areas were continuously copied, the image density decreased from 1.1 to 0.9. And then continue 2
After 000 copies were made, fogging appeared on the white background. This is thought to be due to the abrasion of the surface irregularities as well as toner being partially fused to the peaks ttp of the convex portions.

In Comparative Example 2, when 2000 sheets of an almost solid black original were continuously copied, white streaks appeared in the images. This seems to be due to the fact that the peak portion UP is broken and the broken and missing portion is mixed into the toner layer.

Next, in the example of the present invention, 10,000 sheets of an original with a large white area were copied, and then 10,000 sheets of an original with almost solid black were successively copied, and good images were obtained in both cases.

"Effects of the Invention" As described above, according to the present invention, the toner carrier 2 has a rough surface made of a combination of the first and second roughness components.
By configuring the developing device using this, it is possible to always regulate the layer thickness evenly and stably while preventing breakage or chipping of the tops of the surface irregularities, and the effect of the surface roughening can be maintained for many years. You can get it stably.

Further, according to the present invention, the toner carrier can be formed through a simple manufacturing process, and since there is no need to apply an insulating coating such as alumite to the surface, the toner is transferred to the latent image holding surface using a bias voltage. It can also be applied to developing devices with different configurations, and is highly versatile.

It has various effects such as

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is a schematic configuration diagram of an electrophotographic developing apparatus according to an embodiment of the present invention. 3(A), 3(B), and 3(C) show the surface roughness of the toner carrier used in the embodiment shown in FIG. 2 and the prior art, respectively. ! l Figure 3 (C) (B)

Claims (1)

[Scope of Claims] 1) In a developing device that performs predetermined electrophotographic development by regulating the layer thickness of the toner carried on a toner carrier by a layer thickness regulating member, the toner is conveyed to a development position side, and the toner carrying member is The body surface has at least a first roughness component formed at minute pitch intervals with the heights of the peaks substantially aligned, and a pitch interval larger than the pitch interval of the first roughness component, and an average of the valleys thereof. 2) An electrophotographic developing device characterized by having a rough surface including a second roughness component whose depth is set in a range from the minimum particle size to the maximum particle size of the toner that substantially contributes to development. 3) Roughness distribution over the entire rough surface of the electrophotographic developing device according to claim 1, wherein the ten-point average roughness of the roughness component 1 is less than or equal to the minimum toner particle size that substantially contributes to development. The first roughness component is above the roughness average line obtained by averaging, and the second roughness component is below the roughness average line.
The electrophotographic developing device according to claim 1, wherein the roughness components are substantially located respectively.