JP2601275B2 - Electrophotographic developing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developing device using dry developing toner, and more particularly, to a toner carried on a toner carrier.
The present invention relates to an electrophotographic developing device configured to perform layer thickness regulation by a layer thickness regulating member.

`` Prior art '' Conventionally, as an electrophotographic developing device using a dry developing toner, a bias voltage is applied to a developing position without directly contacting a toner layer carried on a toner carrying member with a latent image holding surface. A so-called non-contact developing method in which the toner is caused to fly selectively by the electric field effect of a voltage is often used. In such a non-contact development method, it is necessary to set the toner layer thickness to be equal to or less than the development interval between the latent image holding surface and the toner layer. As a method of regulating the layer thickness, a method in which a magnetic blade or the like is provided at a non-contact position with respect to the toner carrier to regulate the toner layer thickness, and a toner layer thickness regulating member having a predetermined elasticity is lightly contacted on the toner carrier. In some cases, a uniform and thin toner layer is formed by the contact pressure.

However, in such an apparatus, when the fluidity of the toner stored in the hopper is reduced due to the influence of the external environment such as humidity, or when the toner is aggregated, a toner pool or the like is formed on the upstream side of the layer thickness regulating member. As a result, swelling, white streaks, and the like are generated in the toner layer after the layer thickness is regulated due to the accumulation of the toner and the like, which causes a problem that good development becomes difficult.

Conventionally, in order to solve such a drawback, the surface of the toner carrier in contact with the layer thickness regulating member is roughened so as to have fine irregularities, thereby increasing the frictional force at the contact position of the layer thickness regulating member. There has been proposed a technique in which a vibration force is applied to a toner pool to facilitate the loosening of the aggregated toner and the like, thereby making the toner layer uniform after the regulation of the layer thickness. (Japanese Patent Application No. 54-16453) As a method of roughening the surface of the toner carrier, for example, sand blasting or bead blasting of the surface of a cylindrical tube formed by drawing is performed using irregular or regular particles. By performing the above-described process, a developing device in which the surface roughness and pitch of the surface of the cylindrical toner carrier (hereinafter referred to as a sleeve) are regulated by appropriately selecting the particle size and the spraying pressure for performing the blasting, as well as forming the fine irregularities. Various examples of the rough surface are shown in FIGS. 3 (B) and 3 (C). However, in order to adopt a configuration in which the surface is roughened by mechanical processing such as collision of particles, an uneven portion 50 is required. , 60, in particular, the height of each peak 51p, 61p becomes random, and the shape of each peak 51p, 61p becomes extremely sharp.

Further, in the case of a device in which a toner layer is formed by providing a non-contact layer thickness regulating member on the toner carrier, it is necessary to reduce the pitch interval between the concavities and convexities in order to obtain a thin layer of 0.1 to 5 μm. 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 the layer thickness is regulated by bringing the toner layer thickness regulating member into contact with the sleeve having the surface shape, the peaks 51p and 61p are formed by the pressure contact of the layer thickness regulating member and the shear stress urged by the rotation of the sleeve. Are broken, and the broken portions are mixed into the toner layer to adversely affect image formation, and the pressing force applied to the peaks 51p and 61p is increased to cause wear of the sleeve surface. However, there has been a problem that the effect of the surface roughening cannot be stably obtained for many years.

In order to solve such a defect, the surface of the sleeve roughened by sand blasting is subjected to alumite treatment so as to harden the surface irregularities and to make the peaks sharpened by the alumite coating round. Has been proposed. (Problems to be Solved by the Invention) However, the uneven portions 50, 60 mechanically treated in this manner.
In the method of forming an alumite or other coating film on the other hand, if the thickness of the coating layer is too thin, the effect of hardening is not smoothly achieved, and the peaks 51p and 61p may be missing, and the like. If the coating layer is too thick, the valley bottoms 52 and 62 will be filled with the coating layer, and the effect of forming the surface irregularities will be reduced by half, and the adjustment of the film thickness is very troublesome.

Further, in a developing device having a configuration in which the toner is transferred to the latent image holding surface side by a bias voltage, if a configuration is employed in which alumite, which is an insulating material, covers the sleeve surface,
The transfer of the toner becomes difficult, and the formed image becomes thin.

Further, if the surface irregularities become hard, abrasion occurs on the layer thickness regulating member side in contact with the sleeve surface, and it is impossible to regulate the layer thickness stably for many years.

In view of the above prior art, the present invention can form a thin layer irrespective of contact / non-contact of the layer thickness regulating member, and can stably maintain the layer thickness with a uniform pressure contact force at all times while preventing breakage or missing of the surface unevenness peaks. It is an object of the present invention to provide an electrophotographic developing apparatus which can regulate the surface and can stably obtain the effect of the surface roughening for many years.

Another object of the present invention is to provide an electrophotographic developing apparatus capable of achieving the above-mentioned effects without performing a coating treatment on the surface irregularities formed on the sleeve surface.

[Means for Solving the Problems] In order to achieve the technical object, the present invention provides a layer thickness regulating member 3 which is in contact with the surface of the toner carrier 2 in a contact state as shown in FIG. 1, for example. In the apparatus for controlling the layer thickness of the dry developing toner, the surface of the toner carrier 2 is
An essential component is that it is formed with a rough surface containing at least the first and second roughness components described later.

The first roughness component 10 is formed at a fine pitch interval with the heights of the peaks 11p in contact with the layer thickness regulating member 3 substantially uniform, and the first roughness component 10 substantially covers the entire surface of the rough surface. Is characterized in that it is located above a roughness average line X obtained by averaging the roughness distribution.

Note that the first roughness component 10 is formed mainly for the purpose of increasing the frictional resistance with the layer thickness regulating member 3 and uniforming the pressing force as described later. Then, it is required that the pitch interval is made minute and the number of contacts between the peak 11p and the layer thickness regulating member 3 is increased as much as possible, and the roughness of the first roughness component 10 is used for a long time. It suffices if the depth is such that it does not disappear.

Since the first roughness component 10 is mainly composed of loosening and rolling of the toner by sliding contact with the layer thickness regulating member 3, its ten-point average roughness is substantially equal to that of the development. It is preferable that the particle diameter is not more than the minimum particle diameter of the toner, specifically, not more than 5 μm.

The second roughness component 20 has a pitch interval 20pi of the valley 22.
Has a pitch interval 20pi larger than the pitch interval of the first roughness component 10, and sets the average depth 22b of the valley 22 from the minimum particle size to the maximum particle size of the toner substantially contributing to development. Range, specifically 5 to 20 μm, and the second roughness component 20 is substantially below the roughness average line X obtained by averaging the roughness distribution over the entire rough surface. It is characterized by being located.

Incidentally, since the second roughness component 20 is generally used to increase the conveying force while causing the toner particles to bite into the valleys 22, the pitch interval 20pi is 50 to 500 μm.
A coarse pitch interval of about 20pi may be sufficient.

"Operation" According to the technical means, the above-described operations of the present invention are smoothly achieved by causing each of the roughness components to individually generate a different operation.

In other words, the first roughness component 10 (in the case of an apparatus adopting a configuration in which the layer thickness regulating member 3 comes into contact with the surface of the toner carrier) has a peak 11p that comes into contact with the layer thickness regulating member 3 with a substantially uniform height and a very small height. Since they are formed at the pitch interval, a large number (at least two or more) of the peaks 11p come into contact with the contact surface of the layer thickness regulating member 3, so that a uniform pressing force can be obtained. Periodic micro-vibration is obtained, so that loose toner and aggregated toner can be easily disentangled.

Also, the roughness component has a fine pitch interval and a peak 11p.
Since the heights are substantially uniform, the shearing stress acting on the peak 11p is greatly reduced even by the rubbing of the layer thickness regulating member 3, and breakage of the peak 11p is prevented.

Further, the second roughness component 20 has a pitch interval 20pi larger than the pitch interval 20pi of the first roughness component 10, and the average depth 22b of the valley 22 is substantially equal to the minimum value of the toner that contributes to development. Since the toner particles are set in the range from the particle diameter to the minimum particle diameter, in other words, the toner can be held in a form in which the toner does not completely sink into the valleys 22, so that the first roughness is maintained. Even when the toner whose layer thickness is regulated by the contact pressure with the layer thickness regulating member 3 slips on the peak 11p of the component, the second
It is possible to securely hold the slipped toner at the valleys 22 of the roughness component 20 and to surely convey the toner.

Therefore, according to the present invention, the layer thickness of the toner can be regulated accurately and stably by the action of the respective roughness components, and the toner can be reliably transported to the developing position.

Also, the plurality of roughness components form surface irregularities by mechanical processing such as blast processing as described later, and then the sharpened peaks 11p formed by the mechanical processing are subjected to acid processing or Because it can be easily formed by dissolving and smoothing by alkali treatment, it is easier to manufacture and handle several steps than alumite treatment.

Incidentally, the present invention is a case of an apparatus adopting a configuration in which the layer thickness regulating member is not in contact with the toner carrier, and can obtain substantially the same operation as described above, and the present invention is naturally applied to such an apparatus. obtain.

Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

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 for image formation (not shown) is arranged along the rotation direction.

Reference numeral 2 denotes a non-magnetic sleeve in which the fixed magnet assembly 5 is included, whose outer peripheral surface is roughened so as to have a first roughness component 10 and a second roughness component 20 as described later.

When the sleeve 2 rotates at a predetermined peripheral speed in the direction of the arrow, the high-resistance magnetic toner charged negatively due to mutual friction in the toner container 6 is carried on its peripheral surface to the developing position. And predetermined development can be performed.

A DC pulse generating circuit 7 is connected to the sleeve 2.
By applying a switching DC bias to a developing area between the photosensitive drum 1 and the toner, the toner carried on the sleeve 2 is selectively flown to the latent image holding surface of the photosensitive drum 1 by the electric field effect to develop the toner. I do. In this embodiment, a magnetic toner formed by mixing polyethylene, a magnetic powder, a charge controlling agent, silica and the like in a predetermined weight part, having an average particle size of 10 μm and a toner particle size range of 5 to 20 μm is used. Was.

Reference numeral 3 denotes a toner layer thickness regulating member 3 disposed on the outlet side of the toner container 6 on the upstream side of the developing position, which is formed of a metallic thin plate elastic member, and whose free end is bent at a predetermined porosity. The curved portion 3a is brought into contact with the peripheral surface of the sleeve 2 with a predetermined pressing force, and the base end side is extended toward the toner container 6 at a predetermined penetration angle, and is provided outside the support member 8 formed at the outlet of the toner container 6. Fix it on the wall.

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

First, it is formed to a predetermined diameter by drawing, and FIG. 3 (C)
The surface of an aluminum cylindrical tube having a surface roughness as described above is subjected to sandblasting using irregular particles having a particle size of # 100 to form a rough surface as shown in FIG. ~
After alkali treatment by dipping in a 13% caustic soda alkaline solution for 0.5 to 3 minutes, it was washed with water to form a rough surface as shown in FIG. 3 (A).

The same effect can be obtained by performing the sand blasting with a sandpaper treatment or a bead blasting treatment, and the alkali treatment with a treatment using an acid other than diluted sulfuric acid, diluted hydrochloric acid, or caustic soda.

When such a rough surface is measured in detail, the first roughness component 10 is above the roughness average line obtained by averaging the roughness distribution over the entire rough surface, and the above-mentioned roughness is below. Second roughness component 20
And the average pitch and distribution of the first roughness component 10 are 1.8 ± 1.6 (2σ) μm, and the ten-point average roughness is 2.6 μm, both of which substantially contribute to development. It is smaller than the minimum grain size (5 μm).

The average pitch and distribution of the second roughness component are 360 ± 210 (2
σ) μm, average depth 22b of valley 22 and distribution are 11.1 ± 6.0
(2σ) μm, which is within the range of 5 to 20 μm for the toner particle size.

In order to confirm the effect of this embodiment, the leave 2 shown in FIG.
(Comparative Example 1), sleeve 2 (Comparative Example 2) shown in FIG. 3 (C) subjected to bead blasting, and FIG. 3 (A)
The actual development was performed using the sleeves 2 (Examples) according to the examples of the present invention shown in FIG. 1 respectively. In Comparative Example 1, the originals with many white backgrounds were continuously copied 1000 sheets. .
It dropped from 1 to 0.9. When 2,000 more copies were made, fogging occurred on the white background. This is presumably because the toner was partially fused to the convex peaks 11p together with the abrasion of the surface irregularities.

In Comparative Example 2, white streaks appeared in the image when almost solid black originals were continuously copied 2,000 times. This is the summit
It is considered that 11p is broken, and the broken part is mixed in the toner layer.

Next, according to the embodiment of the present invention, a document having many white background portions is 10,000 sheets,
Next, when nearly solid black originals were continuously copied on each of 10,000 sheets, good images were obtained in each case.

[Effects of the Invention] As described above, according to the present invention, by forming a developing device using a toner carrier 2 having a rough surface composed of a combination of first and second roughness components, The layer thickness can be regulated uniformly and stably at all times while preventing the breakage or dropout of the peak, and the effect of the surface roughening can be stably obtained for many years.

According to the present invention, the toner carrier can be formed by a simple manufacturing process, and since the surface is not coated with an insulating coating such as alumite, the toner is transferred to the latent image holding surface by a bias voltage. It can be applied to a developing device having a configuration, and has high versatility.

And so on.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram of an electrophotographic developing apparatus according to an embodiment of the present invention, and FIG.
(B) and (C) are graphs showing the surface roughness of the toner carrier used in each of the embodiment shown in FIG. 2 and the prior art.

Claims (2)

(57) [Claims] An apparatus for regulating the layer thickness of a dry developing toner by a layer thickness regulating member facing a surface of a toner carrier in a contact state, wherein the surface of the toner carrier has a first roughness component and a second roughness component. The first roughness component is formed at a fine pitch interval, with the heights of the peaks in contact with the layer thickness regulating member being substantially uniform, and the first roughness component is formed by the first roughness component. The second roughness component is located substantially above a roughness average line obtained by averaging the roughness distribution over the entire rough surface. And the average depth of the valleys is set in a range from the minimum particle size to the maximum particle size of the toner substantially contributing to development. An electrophotographic developing apparatus, wherein a roughness component is located substantially below the roughness average line. 2. The electrophotographic developing apparatus according to claim 1, wherein the ten-point average roughness of the first roughness component is equal to or less than a minimum toner particle diameter which substantially contributes to development.