JPH09244395A - Developing roll and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer layer with always uniform charge amount and particle size on the surface of a developing roll without causing excessive charge amount and smaller particle size of developer on the surface of the developing roll. SOLUTION: A developing roll 11 to carry deposited one-component developer 7 to a layer thickness restriction area in a space to a layer thickness restricting member 9 and a development area Q2 nearly opposed to an image carrier 1 in sequence has the developing roll surface, where a small highly charged area 17b for the one-component developer 7 to be easily charged and a small non- charged area 17a for the one-component developer 7 to be hardly charged are densily mixed together and opposed when it is put in frictional contact with the one-component developer 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer which uses an electrophotographic system, and includes an image carrier for holding an electrostatic latent image and a developing roll. The present invention relates to a developing device that develops a one-component developer on an image carrier by an oscillating electric field with a gap provided between the developing device and a developing roll used therefor.

[0002]

2. Description of the Related Art As a one-component developing device for developing an electrostatic latent image formed on an image carrier, various types have been conventionally proposed according to the type of one-component developer used. For example, as a one-component developing device using a magnetic one-component developer, the following technology (J01) is conventionally known. (J01) (Technology shown in FIG. 10) In FIG. 10, a developing device (one-component developing device) 03 arranged to face the image carrier 02 with the developing region 01 interposed therebetween.
Is a hopper 05 for containing the one-component magnetic developer 04.
And a developing roller 08 having a magnet shaft 06 having a plurality of magnetic poles and a cylindrical developing sleeve 07 rotatably supported around the magnet shaft 06, and a one-component developer adhesion amount on the developing roller 08 (one-component developer layer Layer thickness regulating member 09 for regulating the layer thickness).

In such a developing device 03, the one-component magnetic developer 04 housed in the hopper 05 is held on the surface of the developing roll 08 by the magnetic force of the magnet shaft 06, and the one-component magnetic developer 04 and the layer thickness regulating member 09 are held together. While passing, the surface of the developing roll 08 is rubbed and a thin layer of the one-component developer 04 is formed. The rubbing between the one-component developer 04 and the surface of the developing roll 08 causes the one-component developer 04 to be triboelectrically charged and to be charged. As shown in FIG. 10, the layer thickness regulating member 09 has an elastic member such as rubber at least on the surface facing the developing roll 08, and a magnetic plate held facing the developing roll 08 with a constant gap. A non-magnetic plate can also be used. The one-component developer 04 thinned by the layer thickness regulating member 07 is conveyed to the developing area 01 where the image carrier 02 and the developing roll 08 face each other by the rotation of the developing roll 08.

The developing roll 08 has a high-voltage AC power supply 010.
A DC superimposed AC voltage is applied from the DC power source 011 and the one-component developer 04 having a charge is caused to fly to the electrostatic latent image on the image carrier 02 by the electric field in the developing area 01 to perform development. As the developing sleeve 07 of such a developing roll 08, a resin developing roll of phenol, acrylic, polyester or the like, a metal developing roll of aluminum or stainless steel, an aluminum oxide layer or metal plating on the surface, acrylic, epoxy, A metal developing sleeve having a resin coating film of polyester, phenol, etc. is used.

A development ghost is a problem peculiar to the one-component development system. This is because the triboelectric charge amount of the one-component developer increases due to repeated rubbing against the surface of the developing roll, and it is difficult to exchange the one-component developer on the surface of the developing roll. Since the diameter of the one-component developer on the surface of the developing roll is reduced each time it passes through the gap, the one-component developer on the surface of the developing roll has a difference in developing performance between the consumed portion and the non-consumed portion. Conventionally, the following technologies (J02) and (J03) have been proposed as a developing roll having a structure intended to avoid this problem.

(J02) Technology described in Japanese Patent Application Laid-Open No. 1-276174 In the technology described in this publication, a resin layer containing conductive fine particles is provided on the surface of a developing roll, and the outermost layer thereof is a one-component developer size level. By distributing secondary particles of 1.0 μm or less so as to form a gravel road, it is attempted to promote the leak of the surface charge of the one-component developer and prevent the charge-up of the one-component developer. (J03) Technology disclosed in Japanese Patent Laid-Open No. 5-6089 In the technology disclosed in this publication, a resin layer containing conductive fine particles and graphite having solid lubricity is provided on a one-component developing sleeve substrate after blasting. We are trying to obtain the same effect as above.

[0007]

[Problems to be Solved by the Invention]

(Problems of (J02) and (J03) above) However,
In any of the above methods (J02) and (J03), the charge up of the one-component developer is prevented by the leak effect of the surface charge of the one-component developer, and the development ghost is improved, resulting in the one-component development. The charge amount of the agent itself is not sufficient, the developing efficiency is lowered particularly under high temperature and high humidity, and a print image in which the density of a solid black image is lowered is likely to be formed. If you try to increase the density level of the image,
It is necessary to improve the charge level of the one-component developer. That is, the chargeability of the one-component developer provided by the developing roll and the layer thickness regulating member must be improved. The following (J04) to (J07) are known as conventional techniques for this purpose. .

(J04) Japanese Patent Publication No. Hei 4-6963 discloses a technique described in this publication, which uses a developing roll largely separated from a one-component developer in a triboelectric charging train to impart chargeability to the one-component developer. Is increasing. (J05) Japanese Patent Publication No. 51-36070 The technique described in this publication uses a layer thickness regulating member that is greatly separated from the one-component developer in the triboelectric charging train to enhance the charge imparting property to the one-component developer. ing. (J06) Technology described in JP-A-5-188748, the technology described in this publication is the roughness of a thin layer forming blade surface,
And the relationship of the triboelectric series with the one-component developer. (J07) Technology disclosed in Japanese Patent Laid-Open No. 6-236065 The technology described in this publication attempts to prevent fogging by defining the relationship between the developing roll, the toner base particles, and the triboelectrification sequence of the external additive.

(Problems of (J04) to (J07)) However, in the methods of (J04) to (J07), the charge level of the one-component developer becomes extremely high as the developing roll rotates. On the developing roll, the one-component developer forms a two-layer structure including a lower layer portion having extremely high charge and an upper layer portion where charge does not increase so much. Therefore, the charging characteristics differ between the one-component developer consuming portion and the developer non-consuming portion on the developing roll, and so-called developing ghost is likely to occur. Further, since the contact between the upper layer portion of the one-component developer and the developing roll is limited, the chances of contact charging between the one-component developers are increased, and the polarity is opposite to the regular charging polarity involved in the development. The component developer increases, and the fog on the non-image area increases.

The present inventor has found the following facts as a result of research for solving the above problems. (A) When a two-component developer is used, the charge amount of the toner is greatly influenced by the carrier, so the charge amount of the toner changes depending on the relationship between the surface of the developing roll, the toner, and the triboelectric charge train of the carrier. Therefore, it is difficult to determine the relationship between the surface of the developing roll, the toner, and the triboelectric charge train of the carrier in order to make the charging characteristics of the toner uniform. (B) By defining the relationship between the triboelectrification train between the developing roll and the one-component developer or the ionization potential value related thereto, the charging characteristic of the one-component developer on the developing roll can be made uniform.

In view of the above-mentioned problems and research results, the present invention aims at the contents described in the following (O01) to (O03). (O01) To obtain a developer layer having a uniform charge amount and particle size on the surface of the developing roll without causing the developer on the surface of the developing roll to be overcharged or having a smaller particle size. (O02) To provide a developing method in which a development ghost hardly occurs and which also has a high image density and which exhibits stable developing performance. (O03) By always obtaining a developer layer having a uniform charge amount and particle size on the surface of the developing roll, a developer having a polarity opposite to the charge polarity related to development is eliminated, and fog on the non-image area is reduced. thing.

[0012]

Next, the present invention will be described. Elements of the present invention are indicated by parentheses in the elements of the embodiments in order to facilitate correspondence with the elements of the embodiments described later. Add the enclosed items. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(First Invention) In order to solve the above problems,
The developing roll of the first invention of the present application has the following requirements (A
1) and (A2), the (A1) adhered one-component developer (7), the layer thickness regulating region between the layer thickness regulating member (9) and the image carrier (1). ), The surface of the developing roll (11) sequentially conveyed to the developing area (Q2),
(A2) A minute highly charged area (17b) where the one-component developer (7) is easily charged and a minute non-charge where the one-component developer (7) is difficult to be charged when the one-component developer (7) is frictionally contacted. The surface of the developing roll (11) where the charging area (17a) is densely mixed and exposed, and (A3) the charging train is on the same side as the minute high charging area (17b) with respect to the one-component developer (7). The surface of the developing roll (11) having the minute non-charged areas (17a).

(Second invention) Further, the developing device of the second invention of the present application is provided with the following requirements (B1) to (B3), wherein (B1) the attached one-component developer ( 7)
A developing roll (11) having a surface of a developing roll (11) that is sequentially conveyed to a layer thickness regulating region between the layer thickness regulating member (9) and a developing region (Q2) closely facing the image carrier (1),
(B2) A minute highly charged area (17b) where the one-component developer (7) is easily charged and a minute non-charge where the one-component developer (7) is hard to be charged when the one-component developer (7) is frictionally contacted. The surface of the developing roll (11) in which the charged areas (17a) are densely mixed and exposed, (B3) the highly charged area forming material (17b) forming the minute highly charged areas (17b), and the minute uncharged areas (17a) ) Forming a non-charged region forming material (1
7a) is a highly charged area forming material (17b), a non-charged area forming material (17a), and a one-component developer (7).
The surface of the developing roll (11), which is a material lined up in this order.

Highly charged region forming material (17) of the second invention
The charge trains of b), the non-charged region forming material (17a), and the one-component developer (7) are set as shown in FIG. Figure 1A
Shows an example in which the charge train of the one-component developer (7) is arranged on the negative side with respect to the surface of the developing roll (11). FIG. 1B shows the charge train of the one-component developer (7) being the developing roll (11). An example is shown in which it is arranged on the plus side with respect to the surface. In addition,
In FIG. 1, the average charge train on the surface of the developing roll (11) is, as a matter of course, a minute high charge region (17b).
And is in the middle of the minute non-charged region (17a).

(Third invention) Further, the developing device of the third invention of the present application is characterized by having the following requirements: (C
1) A developing roll that sequentially conveys the adhered one-component developer (7) to a layer thickness regulating region that abuts the layer thickness regulating member (9) and a developing region (Q2) that closely faces the image carrier (1). 11) Surface-developing developing roll (11), (C2) Micro-highly charged region (17b) and one component where the one-component developer (7) is easily charged when frictionally contacting with the one-component developer (7). Minute non-charged area (17) where the developer (7) is hard to be charged
a) The surface of the developing roll (11) which is densely exposed together with (a), (C3) a highly charged area forming material (17b) forming the minute highly charged area (17b) and the minute uncharged area (17a) are formed. The non-charged region forming material (17a)
Ionization poker tense value is high charge region forming material (1
7b), the non-charged region forming material (17a), and the one-component developer (7), which are materials arranged in this order.
surface.

Highly charged region forming material (17) of the third invention
The ionization potential values of b), the non-charged region forming material (17a), and the one-component developer (7) are set as shown in FIG. 2A shows an example in which the one-component developer (7) has a large ionization potential value with respect to the surface of the developing roll (11), and FIG. 2B shows the one-component developer (7) with respect to the surface of the developing roll (11). An example with a small ionization potential value is shown. Incidentally, in FIG. 2, the average ionization potential value on the surface of the developing roll (11) is, as a matter of course, in the middle of the minute highly charged area (17b) and the minute uncharged area (17a).

[0018]

Next, the operation of the present invention having the above features will be described. (Operation of First Invention) In the developing roll (11) of the first invention of the present application having the above-mentioned characteristics, the one-component developer (7) attached to the surface of the developing roll (11) is the layer thickness regulating member ( 9)
And the developing area (Q2) closely facing the image carrier (1). Development roll (1
1) The one-component developer (7) adhering to the surface, when passing through the layer thickness regulating region, is exposed in a densely mixed state on the surface of the developing roll (11) in a minute highly charged region (17b) and a minute uncharged region (17b). 17a) makes frictional contact. The developing roll (1
As the one-component developer (7) conveyed by 1), the charging train is composed of a minute highly charged area (17b) and a minute uncharged area (1).
7a) and the one-component developer (7) are arranged in this order, and when the one-component developer (7) is less likely to be charged in the minute non-charged region (17a), the following effects are obtained. Play.

That is, the one-component developer (7) on the developing roll (11) enters the layer thickness regulation region, and mainly due to contact friction between the developing roll (11) and the one-component developer (7). When electrostatically charged, the one-component developer (7) strongly charged between the minute highly charged region (17b) on the developing roll (11) and the layer thickness regulating member (9) has a layer thickness of When passing through the regulation area, it does not remain only in the minute highly charged area (17b), but advances to the minute uncharged area (17a) on the developing roll (11) at the next moment. Small non-charged area (1
In 7a), when the one-component developer (7) is difficult to be charged (that is, when the relationship of their charge trains is set very close to each other), the one-component developer (7) is not charged, and the reverse Further, the adhesive force (electrostatic force) between the developing roll (11) and the one-component developer (7) is reduced. This allows
In the layer thickness regulation region, the occurrence of excessive charging of the developer that strongly adheres to the surface of the developing roll (11) is suppressed,
The charge distribution of the developer layer on the developing roll (11) is kept substantially uniform. That is, the developing roll (11) of the present invention and the minute non-charged area (1) on the surface of the developing roll (11).
If the one-component developer (7) whose charge sequence is close to 7a) is used, in the developer non-consumable portion on the developing roll (11),
It is possible to suppress excessive charging of the developer and reduction in particle size.
Therefore, the charging characteristics of the developer between the developer consuming portion and the non-consuming portion can be kept substantially the same, so that the development ghost can be eliminated.

Further, in the present invention, the developing roll (1
1) Even in the minute non-charged area (17a) on the surface, the charge sequence is smaller than the one-component developer (7) and in the highly charged area (17a).
Since the one-component developer (7) is on the same side as b) and the one-component developer (7) does not always adhere to the developing roll (11) in the layer thickness regulation area, contact between the one-component developers (7) For the reason that the opportunity of charging can be suppressed to a small extent, it is possible to suppress the generation of a reverse polarity developer that is charged to a polarity opposite to the regular charging polarity. Therefore, it is possible to reduce fogging on the non-image portion on the image carrier (1).

(Operation of the Second Invention) In the developing device of the second invention of the present application having the above-mentioned characteristics, the one-component developer (7) attached to the surface of the developing roll (11) is the layer thickness regulating member ( 9) and the developing area (Q2) closely facing the image carrier (1). When the one-component developer (7) attached to the surface of the developing roll (11) passes through the layer thickness regulation region, the minute highly charged region (17b) and the minute non-charged region closely exposed on the surface of the developing roll (11) are exposed. It makes frictional contact with the charged area (17a). In the developing device according to the second aspect of the present invention, as the one-component developer (7) conveyed by the developing roll (11), the charging train includes a minute highly charged area (17b), a minute uncharged area (17a), and A developer in which the one-component developer (7) is less likely to be charged in the minute non-charged region (17a) is used while being arranged in the order of the component developer (7).

The one-component developer (7) adheres to the surface of the developing roll (11) and enters the layer thickness regulation region, and mainly between the developing roll (11) and the one-component developer (7). When the electrostatic charge is imparted by the contact friction, the developer which is strongly electrified between the highly-charged region on the developing roll (11) and the layer thickness regulating member (9) moves in the layer thickness regulated region. In addition to staying only in the highly charged area, it advances to the uncharged area on the developing roll (11) at the next moment. When the relationship of the charging sequence between the non-charged region and the one-component developer (7) is set very close to each other, the charging of the one-component developer (7) does not proceed, and conversely, the developing roll (11) The adhesion between the one-component developer (7) is reduced. This suppresses the occurrence of excessive charging of the developer that strongly adheres to the surface of the developing roll (11) within the layer thickness regulation region, and the charge distribution of the developer layer on the developing roll (11) is substantially uniform. Kept in. That is, in the developing device of the present invention, the developing roll (1) having the surface of the developing roll (11) in which the minute non-charged area (17a) and the minute highly charged area (17b) are densely mixed.
Since 1) and the one-component developer (7) which is difficult to be charged in the minute non-charged area (17a) on the surface of the developing roll (11) are used, the developer non-consuming portion on the developing roll (11) is used. Further, it is possible to suppress the developer from being excessively charged and the particle size being reduced. Therefore, the charging characteristics of the developer between the developer consuming portion and the non-consuming portion can be kept substantially the same, so that the development ghost can be eliminated.

Further, in the second aspect of the invention, even in the minute non-charged area (17a) on the surface of the developing roll (11), the charging sequence is the same as that in the minute highly charged area (17b) as compared with the one-component developer (7). Since the one-component developer (7) is not always attached to the developing roll (11) in the layer thickness regulation region, the one-component developer (7)
Due to the fact that the chances of contact charging between them can be suppressed to a small extent, it is possible to suppress the generation of a reverse polarity developer that is charged to a polarity opposite to the regular charging polarity. Therefore, it is possible to reduce fogging on the non-image portion on the image carrier (1).

(Operation of Third Invention) In the developing device of the third invention of the present application having the above-mentioned characteristics, the one-component developer (7) attached to the surface of the developing roll (11) is the layer thickness regulating member ( 9) and the developing area (Q2) closely facing the image carrier (1). When the one-component developer (7) attached to the surface of the developing roll (11) passes through the layer thickness regulation region, the minute highly charged region (17b) and the minute non-charged region closely exposed on the surface of the developing roll (11) are exposed. It makes frictional contact with the charged area (17a). In the developing device of the third aspect of the present invention, the one-component developer (7) conveyed by the developing roll (11) has an ionization potential of a minute highly charged region (17b) and a minute uncharged region (17).
a) and the one-component developer (7) are arranged in this order,
A developer in which the one-component developer (7) is hard to be charged in the minute non-charged region (17a) (that is, a developer having a small difference in ionization potential value) is used.

In the regulation based on the ionization potential value, the higher the electron donating property, the smaller the ionization potential value and the positive charging property, and the stronger the electron accepting property, the larger the ionization potential value and the negative charging property. There is a tendency. That is, as the difference in the ionization potential value between the developer and the developing roll (11) is larger, both the developer and the developing roll (11) exhibit strong positive and negative chargeability, and the charge imparted from the developing roll (11) to the developer is increased. Becomes stronger. Therefore, as in the third aspect of the invention, depending on the magnitude of the ionization potential value of the material used, the minute highly charged area (17) on the surface of the developing roll (11) can be changed.
b) and the minute non-charged area (17a), and the charging performance of the one-component developer (7) are defined, whereby the second
It is possible to configure a developing device that has the same effect as the invention.

The one-component developer (7) adheres to the surface of the developing roll (11) and enters the layer thickness regulation region, and mainly between the developing roll (11) and the one-component developer (7). When electrostatically charged by contact friction, the one-component developer (7) strongly charged between the minute highly charged region (17b) on the developing roll (11) and the layer thickness regulating member (9) is When moving in the layer thickness regulation area, the developing roll (11) is not stopped at the minute highly charged area (17b) but at the next moment.
It advances to the minute non-charged area (17a) above. When the ionization potential is set very close between the minute non-charged region (17a) and the one-component developer (7), the charging of the one-component developer (7) does not proceed and the developing roll (11) )
The adhesive force (electrostatic force) between the toner and the one-component developer (7) is reduced. This suppresses the occurrence of excessive charging of the developer that strongly adheres to the surface of the developing roll (11) within the layer thickness regulation region, and the charge distribution of the developer layer on the developing roll (11) is substantially uniform. Kept in. That is, in the developing device of the present invention, the developing roll (11) having the surface of the developing roll (11) in which the minute highly charged region (17b) and the minute highly charged region (17b) are densely mixed, and the developing roll (11). Since the one-component developer (7) that is difficult to be charged in the minute non-charged area (17a) on the surface is used, in the developer non-consumed portion on the developing roll (11),
It is possible to suppress excessive charging of the developer and reduction in particle size. Therefore, the charging characteristics of the developer between the developer consuming portion and the non-consuming portion can be kept substantially the same, so that the development ghost can be eliminated.

In the third aspect of the invention, the minute non-charged area (17a) on the surface of the developing roll (11) has the same ionization potential as that of the minute highly charged area (17b) as compared with the one-component developer (7). Is set to the side, and since the one-component developer (7) does not always adhere to the developing roll (11) in the layer thickness regulation area, contact charging between the one-component developers (7) Therefore, it is possible to suppress the occurrence of a reverse polarity developer that is charged to a polarity opposite to the regular charging polarity for the reason that it is possible to suppress the chances of the occurrence of the above. Therefore, the image carrier (1)
Fogging on the upper non-image area can be reduced.

[0028]

Next, an embodiment of the present invention will be described. (Embodiment 1 of 1st invention) Embodiment 1 of the developing roll (11) of the 1st invention of this application provided the following requirements (A4) in the developing roll (11) of the 1st invention. (A4) The surface of the developing roll (11), wherein the minute highly charged area (17b) and the minute uncharged area (17a) are present in an average period (1/5) r to 5r.

(Operation of First Embodiment of First Invention) In the first embodiment of the developing roll (11) of the first invention of the present application having the above-mentioned features, the surface of the developing roll (11) is The minute highly charged area (17b) and the minute uncharged area (1
Since 7a) is present in the average period (1/5) r to 5r, charging and non-charging of the one-component developer (7) can be repeated at an appropriate period to uniformly charge the developer.
If the average period is less than this, it becomes difficult to efficiently realize a charged or uncharged state, and if the average period is more than this, the developer may stay in either a charged or uncharged state. Since the amount of the developer increases, the developer with high charge and the developer with low charge can exist at the same time, which greatly deviates from the object of the present invention.

(Embodiment 2 of the first invention) Embodiment 2 of the developing roll (11) of the first invention of the present application is the developing roll of the first invention or Embodiment 1 of the first invention. (11) is provided with the following requirement (A5): (A5) The minute non-charged area (17a) is made of a conductive resin, and the minute highly charged area (17a).
b) is the surface of the developing roll (11) composed of fine particles dispersed in the conductive resin.

(Operation of Second Embodiment of First Invention) In the second embodiment of the developing roll (11) of the first invention of the present application having the above-mentioned features, the surface of the developing roll (11) is The minute non-charged area (17a) is made of a conductive resin, and the minute highly charged area (17b) is made of fine particles dispersed in the conductive resin. With such a structure, it is possible to easily obtain the surface of the developing roll (11) in which the minute non-charged areas (17a) and the minute highly charged areas (17b) are densely exposed.

(Embodiment 1 of the third invention) In Embodiment 1 of the developing device of the third invention of the present application, the developing device of the third invention has the following requirement (C4). The developing roll (11), wherein the difference between the ionization potential value of the (C4) one-component developer (7) and the average ionization potential value of the surface of the developing roll (11) is 0.2 eV to 1.2 eV. surface.

(Operation of First Embodiment of Third Invention) In the first embodiment of the developing device of the third invention of the present application having the above-mentioned characteristics, the developing roll (11) and the one-component developer (7) are used. ), The difference ΔIP between the ionization potential value of the one-component developer (7) and the average ionization potential value of the surface of the developing roll (11) is 0.2 eV to 1.2 eV. Such a developing roll (11) and a one-component developer (7)
The developing device using can make the charge amount of the one-component developer (7) appropriate. When the difference ΔIP between the ionization potential value of the one-component developer (7) and the average value of the ionization potential of the developing roll (11) is 0.2 eV or less, the developer is not sufficiently charged, and when the difference is 1.2 eV or more, it is overcharged. Become. The one-component developer (7)
In order to easily set the charge amount of the developer to an appropriate value, the difference ΔIP between the ionization potential value of the developer and the average value of the ionization potential of the developing roller (11) is from 0.4 eV to 1.0.
It is preferably eV. The reason is that ΔIP =
This is because in the case of 0.2 to 0.4 and 1.0 to 1.2, the charge stability of the developer with time (for example, after copying 10,000 sheets) is lowered.

(Embodiment 2 of the third invention) Further, Embodiment 2 of the developing apparatus of the third invention of the present application is the same as the developing apparatus of Embodiment 1 of the third invention or the third invention. (C5) developing roll (11) surface, the minute highly charged region (17b), characterized in that
And the surface of the developing roll (11) in which the difference between the ionization potential values of the minute non-charged region (17a) is 0.2 eV to 1.2 eV.

(Operation of Second Embodiment of Third Invention) In the second embodiment of the developing device of the third invention of the present application having the above-mentioned characteristics, the minute highly charged area (on the surface of the developing roll (11) ( The difference between the ionization potential values of 17b) and the minute non-charged region (17a) is 0.2 eV to 1.2 eV. When the difference in the ionization potential value is 0.2 eV or less, it is difficult to suppress the development of the overcharged developer,
At 1.2 eV or more, it is difficult to specify a substance that satisfies the relationship between the one-component developer (7) that regulates the ionization potential value and the developing roll (11). The difference in ionization potential value between the minute highly charged area (17b) and the minute uncharged area (17a) on the developing roll (11) is 0.4.
It is preferably from eV to 1.0 eV. 0.4e
In the range from V to 1.0 eV, it is easy to suppress the development of the overcharged developer, and the substance that satisfies the relationship between the developer and the developing roll (11) that defines the ionization potential value is satisfied. Is easy to identify.

Examples of the present invention will now be described with reference to the drawings, but the present invention is not limited to the following examples. (Embodiment 1) FIG. 3 is an explanatory view of Embodiment 1 of a developing device equipped with the developing roll of the present invention. In FIG. 3, the image carrier 1 driven to rotate is composed of a drum having a photoconductive surface layer made of a negatively charged organic photoconductor. A charger 2 is arranged on the upstream side of the latent image writing position Q1 set along the movement locus of the surface of the image carrier 1. On the surface of the image carrier 1 whose surface is uniformly charged by the charger 2, an electrostatic latent image (for example, the background portion is -360 V, the image portion is -100 V by the light L at the latent image writing position Q1).
V electrostatic latent image) is written. The electrostatic latent image on the surface of the image carrier 1 is developed into a toner image T by the developing device G in the developing area Q2. The toner image T is transferred onto the sheet S by the transfer device 3 at the transfer position Q3. The toner remaining on the image carrier 1 is cleaned and removed by the cleaner 4. The surface of the cleaned image carrier 1 is charged again by the charger 2.

The developing device G for developing the electrostatic latent image on the image carrier 1 into a toner image in the developing area Q2 has a developing case 6. A magnetic one-component developer 7, a developer agitator 8, a layer thickness regulating member 9, and a developing roll 11 are housed in the developing case 6. The developer 7 used in the developing device G of Example 1 is styrene-acrylic resin, polypropylene wax, polyester wax,
Carbon black and magnetic powder are the main internal components, and silicone oil-treated silica and cerium oxide are externally added as external additives.

The layer thickness regulating member 9 is the developing roll surface 1
It is composed of a soft elastic body 9a that is pressed against 1 and a spring plate 9b that supports the soft elastic body 9a at one end side, and the other end side of the spring plate 9b is fixedly supported by the developing case 6. The contact position of the soft elastic body 9a with respect to the developing roll 11 is the developing roll 1 with respect to a reference line connecting the position where the developing roll 11 is closest to the image carrier 1 (developing area Q2) and the center of the developing roll 11.
1, which is at a position of 80 ° on the upstream side in the rotation direction,
The free end supporting the soft elastic body 9a is installed so as to face the downstream side in the rotation direction of the developing roller 11. The layer thickness regulating member 9 has a width of 15 mm as the soft elastic body 9a,
Silicone rubber with a thickness of 1.00 mm and a rubber hardness of 50 °, and the spring plate 9b is a stainless steel plate with a thickness of 0.1 mm (SUS304 CSP 3/4 material, tensile strength 95 k).
gf / mm ² and proof stress 68 kgf / mm ² ) are used.

The developing roll 11 has a magnetic shaft 12 fixedly supported by the developing case 6 and a developing sleeve 13 rotatably supported. Magnetic shaft 12
Has a magnetic pattern in which S and N poles, which are magnetic poles of a plurality of magnets, are arranged as shown in the drawing, and the magnetic one-component developer 7 is applied to the developing sleeve 13 along the magnetic pattern.
It is designed to adhere to the surface. Pre-development sleeve 13
Are arranged so as to face the image carrier 1 at a predetermined interval (200 μm to 350 μm) in the developing area Q2.

A bias voltage is applied from the developing bias power source B to the developing sleeve 13. The developing bias power source B is composed of a high-voltage AC power source and a DC power source, and an AC voltage superposed with a DC voltage is applied to the developing sleeve 13 of the developing roll 11 as a developing bias voltage, whereby an image is generated in the developing area Q2. An alternating electric field is generated between the carrier 1 and the carrier 1.
As the developing bias, for example, the frequency is 2.4k.
HZ, an AC voltage having a peak-to-peak voltage of 2000V and a DC voltage having a DC component of -250V are used.

The development by the above-mentioned developing device is performed as follows. That is, the magnetic one-component developer 7 contained in the hopper portion of the developing case 6 is adsorbed on the surface of the developing roll 11 while being stirred by the developer agitator 8, and is developed by the soft elastic body 9 a of the layer thickness regulating member 9. The surface of the roll 11 is rubbed. As a result, the developer 7 is thinned and at the same time frictionally charged to a predetermined polarity. Then, the thinned developer 7 is rotated in the developing area Q by the rotation of the developing roll 11.
The developer particles are transported to 2 and fly so as to reciprocate due to the alternating electric field in the developing area Q2 to form a cloud shape. Then, the cloud-shaped developer 7 is attracted and adhered to the electrostatic latent image portion on the image carrier 1 by the DC component of the developing bias voltage, and thus the development is completed.

FIG. 4 is a detailed explanatory view of the developing sleeve 13 of the developing roll 11 used in the developing device G of FIG. 3, FIG. 4A is a sectional view of the developing sleeve 13, and FIG. 4B is a main part of FIG. 4A. FIG. The developing sleeve 13 has a cylindrical developing sleeve base material 16 made of an aluminum pipe having an outer diameter of 18 mm and an inner diameter of 16.5 mm, and a developing roll surface layer 17 applied and formed on the developing sleeve base material 16. . The developing roll surface layer 17 includes a conductive resin layer (fine non-charged region forming material) 17a containing minute carbon black fine particles to impart conductivity, and a positive resin contained in the conductive resin layer 17a at a high density. It is composed of chargeable fine particles (highly charged area forming material) 17b. And
A minute uncharged region 17a is formed by the surface exposed portion of the conductive resin layer 17a, and a minute high charged region 17b is formed by the surface exposed portion of the positively chargeable fine particles (highly charged region forming material) 17b.
Are formed. The positively chargeable fine particles 17b are substances that are positively charged when they make frictional contact with the one-component developer 7.
In this embodiment, since the positively chargeable fine particles 17b are used as the minute highly charged area forming substance, the minute highly charged area, the minute uncharged area, and the charge train of the one-component developer belong to FIG. 1A. However, it is also possible to select the material so that the minute highly charged area, the minute uncharged area, and the one-component developer belong to the charging sequence shown in FIG. 1B.

When the conductive resin layer 17a is formed, 100 parts by weight of polyester resin and 30 parts by weight of carbon black having an average particle size of about 30 nm are blended, and the charging sequence is higher than that of the developer. The developing sleeve base material 1 was prepared by dispersing 20 parts by weight of an acrylic resin (positively chargeable fine particles) having an average particle diameter of 3 μm, which is located on the very positive side.
The solid content of the paint applied to No. 6 is used. After spray coating the surface of the developing sleeve base material 16 as a paint with a ratio of the solid content to the volatile content of the solvent of 10 to 5 to 20, it is dried by heating at 60 ° C and cured by heating at 170 ° C. The developing roll surface layer 17 having a film thickness of 15 to 50 μm
To form

The surface roughness (that is, the surface roughness of the developing roll surface layer 17) and the resistivity of the developing roll 11 of Example 1 are as shown. Surface roughness Ra 0.3 mm to 1.5 mm Surface roughness Sm 30 mm to 100 mm Resistivity 102 Ωcm to 105 Ωcm The surface roughness of the developing roll 11 was measured with a surface roughness meter using a needle terminal of φ2 mm.

The ionization potential values of the developer 7 and the material used for the developing roll surface layer 17 of the developing roll 11 were measured with AC-1 (photoelectron emission measuring instrument, manufactured by Riken Keiki Co., Ltd.). It was as shown in. The graph shown in Fig. 5 shows 3.4 with a xenon lamp as the light source.
The data is obtained by irradiating the sample with light of eV to 6.2 eV and monitoring oxygen ions in the atmosphere (in the chamber) 0 ₂ ⁻ ionized by the electrons emitted from the sample with a low energy counter. The energy at which the photoelectrons start to be emitted is measured as the ionization potential value. In FIG. 5, the intersection of the straight line after the rising of the graph and the X axis shows the IP value.

Regarding the triboelectric series, the polarities of the charges generated by the contact charging between the samples were measured with a surface electrometer,
The relationship of the charge train was specified. Developer 7 used in this embodiment,
The developing roll surface layer 17 of the developing roll 11, the AC-1 (photoelectron emission measuring instrument, of the material used for the developing roll surface layer,
The relationship between the measurement result of the ionization potential value by Riken Keiki Co., Ltd.) and the triboelectric charging train is shown in Table 1 of FIG.

The developing roll 11 is mounted on a printer (commercially available Fuji Xerox 4105 printer) equipped with a developing device that operates in the same developing system as the one-component developing device described in FIG. 3, and the following test is conducted. It was Then, using the developing roll 11 having the developing sleeve 17 of the present invention and the developing roll having the conventional developing sleeve,
The charging performance of the developer was examined. As the developing sleeve of the conventional example, a developing sleeve manufactured by spray coating was prepared by mixing 20 parts by weight of conductive carbon black particles with 100 parts by weight of a phenol resin. First,
In order to clarify the charging characteristics that the developing sleeve gives to the developer, the charge amount of the developer when the developing sleeve was idled in the non-developed state was measured. When the developer on the developing sleeve is measured by a suction type charge amount measuring device, the suction distance is changed so that the developer is separated into an upper layer and a lower layer of the developer. The changes in the charge amount after one rotation of the developing sleeve to after ten rotations of the developing sleeve are shown in FIGS. 7 and 8. Also,
Table 2 in FIG. 9 shows the proportion of the normally charged developer and the opposite polarity developer involved in the development among the developers on the developing sleeve.

According to this, in the conventional example shown in FIG. 7, the charge amount of the entire developer is increased by the rotation of the developing sleeve. In particular, the charge amount of the lower layer developer is remarkably increased, and the charge amount of the upper layer developer does not increase but tends to decrease. That is, in the conventional example, since the lower layer developer is in contact with the developing roll with a strong adhesive force, excessive triboelectric charging occurs when the developing roll idles, and the charge amount increases.
On the other hand, the developer in the upper layer has less contact with the developing roll due to the influence of the lower layer toner adhering to the developing roll, so that the charge amount does not increase and the contact charge between the developers increases, so that the developer of the opposite polarity is developed. The existence ratio of the agent increases. However, according to the developing roll used in the present invention shown in FIG. 8, the increase in the charge amount of the entire developer per revolution of the developing sleeve is not so remarkable as in the conventional example, and the charge amount of the developer is lower than that of the lower layer developer. There is almost no difference between the upper layer developer and the upper layer developer, so that the developer on the developing sleeve is distributed with a substantially uniform charge amount.
Further, from Table 2 of FIG. 9, it was found that there is almost no developer having a polarity opposite to that of the normally charged developer involved in the development.

Next, the print image quality performance (fogging,
Occurrence of ghost, black patch density, etc.) was investigated. Table 2 of FIG.
Regarding the developing roll of the embodiment of the present invention and the developing roll of the conventional example, the level of the developing ghost after continuously printing 10 sheets of white paper having no image portion on the entire surface of the paper and the upper layer on the developing sleeve. Difference in the amount of developer charge between the lower and lower layers, and 100% for an original with 5% of the image area in the original.
The fog level on the non-image area after printing 0 sheets and the image density of the black patch image at that time are shown. The development ghost in the table is characterized by the density difference of the 50% halftone image after consumption of the developer on the development roll and after non-consumption of the developer, and the absolute value of the density difference is ⊚: to 0.01. , ○: 0.01
.About.0.02, .DELTA.: 0.02 to 0.03, x: 0.03 or more. The level of fogging on the non-image area was evaluated according to the criteria of ⊚: hardly expressed, ◯: not practically noticeable, Δ: slightly noticeable in practical use, and x: very noticeable. That is, from Table 2 in FIG. 9, in the present invention, the difference in charge amount between the upper layer and the lower layer, the first rotation of the developing sleeve-1
By setting the charge amount difference at the 0th rotation smaller than that in the conventional example, the occurrence of development ghost can be suppressed. Further, the level of fogging can be improved by reducing the proportion of the reverse polarity developer.

(Modifications) Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, but is within the scope of the gist of the present invention described in the claims. Thus, various changes can be made. A modified embodiment of the present invention is illustrated below. (H01) In the above embodiment, the case where the charging series is shown in FIG. 1A has been described, but the same effect can be obtained even in the case where the charging series is shown in FIG. 1B. (H02) In the above-described embodiment, the polyester resin is used as the base resin of the conductive resin layer. However, other resins that are equivalent to the polyester resin in terms of charging sequence and are on the positively charged side of the developer ( Epoxy resin, fluorine resin, etc.)
Can be used. (H03) In the above-described examples, acrylic resin was used as the positively chargeable fine particles for imparting negative polarity to the developer, but as an alternative material, metal powder such as copper powder, stainless powder, iron powder, or alumina. It is possible to use potassium titanate, titanium oxide and the like. (H04) In the above-mentioned embodiment, the post-treatment after coating the resin is not performed, but in order to expose the positively chargeable fine particles to the surface of the developing roll, the surface of the developing roll is treated with a fine abrasive of # 1000 or more. It is possible to carry out post-polishing.
Further, in order to expose the positively chargeable fine particles to the surface of the developing roll, a solution having an erosive property only in the base resin,
It is possible to apply wet etching treatment only to the base resin. (H05) The developing roll surface layer 17 can be formed by the following method. That is, in order to form the minute non-charged regions 17a on the surface of the sleeve base material 16, the one-component developer 7 is applied with the conductive resin layer 17a which is close in charge sequence (or has a small difference in ionization potential value), When a resin of a paint whose charge train is separated from the component developer 7 (the difference in the ionization potential value is large) is applied and the average particle diameter of the one-component developer is r, a cycle of (1/5) r to 5r The method of etching the upper layer resin with.

[0051]

The developing roll and the developing device of the present invention described above can achieve the following effects. (E01) In the layer thickness control region, the one-component developer highly charged in the minute and highly charged region on the surface of the developing roll is not charged in the minute non-charged region, and the adhesive force due to the electrostatic force with the surface of the developing roll becomes small, and the developing roll surface It is easier to get away from. Therefore, the developer on the surface of the developing roll is not overcharged or has a smaller particle size, and a developer layer having a uniform charge amount and particle size can be obtained on the surface of the developing roll. Therefore,
It is possible to perform development exhibiting stable development performance with almost no development ghost. (E02) Since the one-component developer does not always adhere to the surface of the developing roll in the layer thickness regulation region, the chance of contact between the one-component developer and the developing roll increases. For this reason, it is possible to reduce the amount of the one-component developer having the polarity opposite to the charging polarity related to the development, and it is possible to reduce the fog on the non-image area.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a developer and a triboelectric charge train of a developing roll in the present invention.

FIG. 2 is a diagram showing a relationship between a developer and an ionization potential value of a developing roll in the present invention.

FIG. 3 is an explanatory diagram of an embodiment of a developing device provided with the developing roll of the present invention.

4 is an explanatory view of an embodiment of a developing roll according to the present invention, FIG. 4A is a sectional view of a developing sleeve of the developing roll, and FIG. 4B is an enlarged view of a main part of FIG. 4A.

FIG. 5 is a diagram showing light energy, a photoelectron emission amount at that time, and an ionization potential value when the ionization potential value is measured.

6 is a table 1 shown in FIG. 6, which shows the ionization of the materials used for the developer 7 and the developing roll surface layer 17 of the developing roll 11 of Example 1 by the AC-1 (photoelectron emission measuring instrument, manufactured by Riken Keiki). 6 is a table showing the relationship between the potential value measurement results and the triboelectric charging train.

FIG. 7 is a graph showing the charge amounts of the entire developer layer, the upper developer layer, and the lower developer layer for each rotation number of the developing roll in the conventional example.

FIG. 8 is a diagram showing the charge amounts of all layers of the developer, the upper layer of the developer, and the lower layer of the developer according to the number of rotations of the developing roll in the embodiment of the present invention.

FIG. 9 shows a developing roll after continuous printing of 10 blank sheets with no image area on the entire surface of the developing roll of the embodiment of the present invention and the developing roll of the conventional example. -Strike level and upper layer on the developing sleeve,
Differences in the amount of developer charge in the lower layer, the level of fog on the non-image area after printing 1000 sheets of an original in which the ratio of the image area in the original is 5%, and the image density of the black patch image at that time It is a table showing.

FIG. 10 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

Q2 ... Development area. 1 ... Image bearing member, 7 ... One-component developer, 9
... Layer thickness regulating member, 11 ... Developing roll, 12 ... Magnetic shaft, 13 ... Developing sleeve, 16 ... Developing sleeve base material, 1
7 ... Developing roll surface layer, 17a ... Minute non-charged area (non-charged area forming material), 17b ... Micro high charge area (highly charged area forming material).

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 30, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

6 is a table 1 shown in FIG. 6, which shows the ionization of the materials used for the developer 7 and the developing roll surface layer 17 of the developing roll 11 of Example 1 by the AC-1 (photoelectron emission measuring instrument, manufactured by Riken Keiki). 6 is a table showing the relationship between the potential value measurement results and the triboelectric charge train.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Figure 9

[Correction method] Change

[Correction contents]

FIG. 9 shows a developing roll after continuous printing of 10 blank sheets with no image area on the entire surface of the developing roll of the embodiment of the present invention and the developing roll of the conventional example. -Strike level and upper layer on the developing sleeve,
Differences in the amount of developer charge in the lower layer, the level of fog on the non-image area after printing 1000 sheets of an original in which the ratio of the image area in the original is 5%, and the image density of the black patch image at that time FIG.

Claims (8)

[Claims] 1. A developing roll having the following requirements, and (A1) the adhered one-component developer closely faces a layer thickness regulating region between the layer thickness regulating member and an image carrier. (A2) Micro-highly charged area where the one-component developer is easily charged and minute non-charged area where the one-component developer is hard to be charged when the one-component developer is frictionally contacted The surface of the developing roll in which and are densely mixed and exposed. (A3) The surface of the developing roll having the minute non-charged area on the same side as the minute highly charged area in the charging line with respect to the one-component developer. 2. The development roll according to claim 1, wherein the average particle size of the (A4) one-component developer is r, and the micro-highly charged area and the micro-non-charged area are small. The surface of the developing roll, in which the charged region exists between the average period (1/5) r and 5r. 3. The developing roll according to claim 1 or 2, characterized in that: (A5) the minute uncharged region is made of a conductive resin, and the minute highly charged region is the conductive layer. The developing roll surface composed of fine particles dispersed in a photosensitive resin. 4. A developing device having the following requirements: (B1) The adhered one-component developer is closely opposed to a layer thickness regulating region between the layer thickness regulating member and an image carrier. A developing roll having a developing roll surface successively conveyed to the developing area, (B2) when in friction contact with the one-component developer,
The surface of the developing roll in which a minute high-charged region where the one-component developer is easily charged and a minute non-charged region where the one-component developer is hard to be charged are densely mixed and exposed, (B3) A high charge forming the minute high-charged region The area forming material and the non-charged area forming material forming the minute non-charged area are materials in which the electrified rows are a high-charged area forming material, a non-charged area forming material, and a one-component developer in order. . 5. The developing device according to claim 4, wherein the following requirements are met: (B4) The one-component developer and the charge train are close to each other, and the one-component developer is in frictional contact with each other. The non-charged region forming material in which the developer is less likely to be charged. 6. A developing device characterized by having the following requirements: (C1) developing the adhered one-component developer in close proximity to a layer thickness regulating region in contact with a layer thickness regulating member and an image carrier. A developing roll having a surface of a developing roll that is sequentially conveyed to a region, (C2) a minute highly charged region where the one-component developer is easily charged and a minute charge where the one-component developer is difficult to be charged when the one-component developer is frictionally contacted The surface of the developing roll in which the non-charged areas are densely mixed and exposed, (C3) the high-charged area forming material that forms the minute high-charged areas, and the non-charged area forming material that forms the minute non-charged areas are ionized pockets. The surface of the developing roll, wherein the value is a material in which the high-charge region forming material, the non-charge region forming material, and the one-component developer are arranged in this order. 7. The developing device according to claim 6, wherein the difference between the ionization potential value of the (C4) one-component developer and the average ionization potential value of the surface of the developing roll is 0. The surface of the developing roll, which is from 2 eV to 1.2 eV. 8. The developing device according to claim 7, wherein the difference (C5) between the minute highly charged area and the minute uncharged area on the surface of the developing roll is 0. The surface of the developing roll, which is from 0.2 eV to 1.2 eV.