JP2809794B2 - Development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electrophotographic apparatus and an electrostatic recording apparatus.
The present invention relates to a developing method for visualizing an electrostatic latent image, and more particularly to a developing method for obtaining a high-quality image using one-component toner.

(Prior Art) As one of developing means using a one-component toner (developer), for example, US Pat. No. 3,152,012, US Pat. No. 3,754,963, US Pat. No. 3,731,146,
The pressure development method is known from JP-A-47-13088, JP-A-47-13089, JP-B-51-36070, JP-B-52-36414 and the like. In this pressure development method, a thin layer of a one-component developer consisting only of a non-magnetic toner is formed on the surface of a toner carrier having elasticity, conductivity and roughness, and this toner layer holds an electrostatic latent image. It is characterized in that it makes contact with the surface of the electrostatic latent image holding member so that the relative speed becomes zero, and has many advantages such as simplification of the apparatus and easy colorization. However, as a result of additional tests by the present inventors, it was found that the following problems existed in the developing means.

It is specified that an important feature of the above pressure development method is that the surface of the toner layer and the surface of the electrostatic latent image are moved at a relative peripheral speed of substantially zero. However, as a result of the experiment, it was found that the developed image obtained under these conditions was poor in sharpness and poor in background fog and density unevenness. On the other hand, when the speed difference is provided, the toner particles roll or slide at the contact position between the toner layer and the electrostatic latent image surface, and the charge of the toner particles is promoted and the image is arranged. An extremely sharp, no background fog, uniform and high-density developed image was obtained.

When the pressure development method is performed, the charged particles on the toner carrier, that is, the toner, are transferred to the electrostatic latent image surface, so that an electric circuit (hereinafter, referred to as a developing current) flows through an electric circuit from the toner carrier to a power supply for developing bias. Flows. Therefore, the resistance value of the surface of the toner carrier or the resistance value between the surface of the toner carrier and the power source for developing bias must be equal to or less than a predetermined value. However, the above-mentioned known examples do not disclose a concept that is practically effective in this regard.

Further, since the above-described development current is mainly caused by the movement of the toner particles, the amount of toner charge, the amount of toner attached to the electrostatic latent image formed on the surface of the electrostatic latent image holding member, and the amount of toner It depends on the moving speed, the size of the toner carrier, and the like. Therefore, the potential of the toner carrier surface, that is, the effective developing bias value fluctuates due to the relationship between these elements and the above-described resistance values, and in some cases, an extremely poor image in which fog or insufficient density is recognized may be obtained. is there.

In addition, in this method, a non-magnetic developer (toner) is supported on the surface of the toner carrier, and a fixed amount of non-magnetic toner is always supplied. It is not easy to supply a latent image. Because it is not possible to reliably apply remote acting force such as magnetic force to non-magnetic toner,
This is because, when the toner layer on the surface of the toner carrier is consumed by the development of the predetermined latent image, it is difficult to quickly form and recover a thin toner layer on the surface of the toner carrier (hereinafter, referred to as “the toner layer”).
The ability to quickly recover the thin toner layer on the surface of the toner carrier and always supply a constant amount of the thin toner layer to the latent image is called toner transportability. When such a toner conveyance failure occurs, the density is reduced in the latter half of the solid image.
To improve toner transportability, a sponge roller or brush roller is provided in a toner container, and these rollers rub non-magnetic toner on a toner carrier to supply toner. And JP-A-62-7067 and JP-A-62-95558.

Further, in the above-described pressure development method, since the toner carried on the toner carrier is pressed or brought into contact with the electrostatic latent image to perform the development, an elastic and conductive developing roller may be used as the toner carrier. Required. In particular, when the electrostatic latent image holder is a rigid body, it is an essential condition that the toner carrier is formed of an elastic body in order to avoid damaging it.

As a specific example of the toner carrier having such a configuration, an elastic layer such as foam rubber or polyurethane foam is provided on the surface of a metallic roller base material, and further, a graphite is contained in a flexible conductive layer and a binder resin. A developing roller in which an outermost layer in which particles are dispersed is sequentially coated is known (JP-A-47-13088). That is, the graphite-binder resin mixture was applied to a thin plate of aluminum-treated polyethylene terephthalate by using a horizontal coating device for about 20 hours.
2. Description of the Related Art A toner carrier (developing roller) having a surface layer formed by coating so as to have a thickness of μm is known.

On the other hand, in the above-mentioned pressure developing method, means for pressing a toner layer forming member against the toner carrier is used in order to form a thin layer of toner on the toner carrier. The following two types of means are conventionally known as the toner layer thickness controlling means.

(A) Press the antinode of the plate-shaped toner layer thickness regulating member against the toner carrier.

(B) Press the end of the plate-shaped toner layer thickness regulating member against the toner carrier.

The method or means for pressing the surface of the plate-like toner layer thickness regulating member bellow in (a) is described in, for example, JP-B-63-16736, JP-A-57-165866, JP-A-60-73649, It is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-138967, U.S. Pat.No. 4,521,098, and the like. At the same time as the layer is formed, the toner particles are surely triboelectrically charged, so that a good visible image can be obtained.

On the other hand, means for pressing the end of the plate-like toner layer thickness regulating member (b) is disclosed in JP-B-51-36070 and JP-A-53-23638.
JP-A-58-116559, JP-B-60-15068, JP-A-62-95559, JP-A-62-96981 and JP-A-62-113178. ing. These known means for pressing the ends are further classified into the following three types.

(I) A method of pressing a tip processed into a cylindrical surface (JP-B-51-36070).

(Ii) A method of pressing a sharp tip (JP-A-53-23638, etc.).

(Iii) A method of pressing a flat processed tip (JP-A-62-95559, etc.).

According to these means, a desired toner thin layer can be formed with a relatively low pressing force.
Problems associated with the method (1) can be avoided. However, these methods of pressing the end also have the following problems. In the case of pressing the sharp tip of (ii), the contact area between the toner carrier and the regulating member is extremely small, and the pressure is concentrated. Therefore, the pressure setting on the entire regulating member must be strictly controlled. In addition, there is a disadvantage that a slight defect in processing accuracy at the leading end causes the toner layer to be non-uniform, and the thickness of the toner layer is generally likely to be excessively thin. (Ii
In the case (i), since the end section of the plate-shaped regulating member is pressed against the toner carrier, the problem relating to the means (ii) does not occur in a normal state. Due to the fluctuation, the edge of the end section comes into contact with the toner carrier, and the same problem as the case (ii) may occur. On the other hand, in the means (i), since there is no sharp edge at the end of the restricting member, even if the mounting state of the restricting member fluctuates slightly, problems such as the cases (ii) and (iii) occur. And the manufacture and assembly of the device becomes extremely easy.
Further, by making the ends curved, an intermediate effect between the means for pressing the belly surface and the means for pressing the sharp end can be obtained, and the toner layer can be thinned with relatively low pressure. Reliable charging of the toner particles can be achieved.

(Problems to be solved by the invention) Of these problems, the case of
-12627, JP-A-53-23638, etc.
It is disclosed that moving the toner carrier faster than the electrostatic latent image improves image quality. On the other hand, various proposals have been made on the preferable range of the volume resistance value of the surface of the toner carrier with respect to the problem in the above case. In Japanese Patent Publication No. Sho 60-22352, 10 ⁵
It is preferable to use a conductive material having a conductivity of Ωcm or less, and it is preferable that a material having a conductivity of 10 ⁸ Ωcm or less is preferred in Japanese Patent Publication No. 62-3949, and it is 10 ¹³ Ω in Japanese Utility Model Publication No. 62-35097.・ C
m or more is good, Japanese Patent Publication No. 63-26386 discloses that
It is pointed out that about 10 ⁸ Ω · cm is good.
However, the fact that the preferred range of the resistance value differs according to each invention in this way suggests that the appropriate conditions fluctuate due to some of the factors described in the above-mentioned problems, and the overall Unless a good balance is taken into account, it is difficult to obtain a good image.

In the above case, the toner transportability can be improved to some extent, but if the frictional charging between the toner carrier surface and the non-magnetic toner particles is insufficient, the non-magnetic toner particles cannot adhere to the toner carrier surface. However, improvement in transportability cannot be expected. Further, even if good toner transportability is obtained in the initial state, a phenomenon in which a thin film of non-magnetic toner is formed on the surface of the toner carrier by use for a long period of time, that is, a phenomenon called filming occurs. Often, the triboelectric charging between the particles and the surface of the toner carrier becomes insufficient, resulting in deterioration of the toner transportability.

By the way, in an electrophotographic apparatus such as a copying machine or a laser printer, as a method of controlling the density of an obtained image, generally, the amount of light for exposing an electrostatic latent image holding member (photosensitive member) is controlled or applied to a toner carrier. A method by controlling a developing bias voltage is known. According to these methods, it is possible to control the image density to some extent. However, there is a developing method in which a thin layer of non-magnetic toner is formed on the surface of the toner carrier, and this is supplied to a latent image to perform development. When used, there is a problem in that an obtained image density has an upper limit, and higher density cannot be expected. This is because if the nonmagnetic toner thin layer on the toner carrier is consumed by 100%, it is impossible to further increase the density. When the thickness of the non-magnetic toner layer is increased in order to increase the density, the non-magnetic toner adheres to the surface of the toner carrier without contacting the toner carrier, the non-magnetic toner layer thickness regulating member or the toner supply member described above. There is a problem that the toner particles cause fogging in the non-image area.

Also, in the case of, even if the elastic layer satisfies the above conditions,
If left under pressure for a long period of time, compression set of the elastic layer may occur, which may affect the image. On the other hand, since elastic materials having low compression set are generally high in height, for example, when eccentricity occurs in the toner carrier, it is not easy to obtain a development nip width sufficient to cover such fluctuations, and image density is reduced. In some cases, there was unevenness (density unevenness). Further, there is a difficult problem in that the surface smoothness of the toner carrier is influenced by the surface condition of the elastic layer forming the base, that is, whether or not it is due to the forming conditions suitable for the material.

Furthermore, regarding the durability of the toner carrier, in the case of a toner carrier having a conductive layer provided on an elastic layer, specific techniques are disclosed for scratches and abrasion or peeling of the conductive layer that occur during use. No, it is not known what durability is required as a conductive layer, or it becomes an unnecessarily expensive toner carrier for the required life,
The required life was not achieved, the production management was difficult, and the variation between lots was large.

When the toner carrier is made of an elastic material, there are many practical advantages, but there are the following disadvantages. That is, when the toner layer forming member is pressed to form a thin layer of the required toner, the pressed portion is dented and a so-called compression set is generated. Moreover, the dents are likely to occur when the same location is compressed for a long period of time, and when the environment is high or low temperature. Therefore, when this compression set occurs, the toner layer formed on the toner carrier is likely to be non-uniform, the developing electric field at the time of development is non-uniform, Due to the difficulty in moving at a constant speed, for example, there is a problem that density unevenness, white streaks, and black streaks are generated in an image obtained by development, thereby deteriorating the image quality. Moreover, in this case, the image quality may be deteriorated even when not used, and it is desirable that the environmental conditions are reduced as much as possible when storing or transporting in a warehouse.

Furthermore, in the case of (1), in these developing devices that press the abdominal surface of the plate-shaped regulating member of (a), the toner particles are filled in a wedge-shaped space formed between the regulating member and the toner carrier. Since the toner particles tend to stay and are likely to be pushed out by the subsequent toner particles, the regulating member must be pressed against the toner carrier with a relatively high pressure to form a desired thin toner layer. As a result, there have been problems such as that toner adheres to the toner carrier and the regulating member, and that the force required for driving the toner carrier becomes large.

On the other hand, of the means (b) for pressing the end of the plate-shaped regulating member, the most practical method (i) for pressing the cylindrically processed tip has the following disadvantages. It became clear. For example, Japanese Patent Publication No. 51-36070 discloses that a regulating member made of a material such as polytetrafluoroethylene or polyformaldehyde (trade name: Delrin) and having its end face processed into a cylindrical surface is suitable.
However, according to the follow-up test of the present inventors, the processing accuracy of the regulating member, particularly that the warpage or undulation in the longitudinal direction causes unevenness of the toner layer, particularly because the material is close to a rigid body, It was found that there were drawbacks in that it was not possible to absorb the inferiority of the mounting and processing accuracy and that the toner layer was likely to be non-uniform, and that processing for obtaining a highly accurate cylindrical surface was not easy. In addition, the toner tends to adhere to the surface of the regulating member due to long-term use, resulting in unevenness of the toner layer.

The present invention has been made in order to solve the problems of the related art, and has as its object to provide a developing method capable of easily obtaining a uniform, high-density image which is always sharp, has no background fog.

[Constitution of the Invention] (Means for Solving the Problems) In a developing method according to the present invention, a thin toner layer is formed on the surface of a toner carrier to which a developing bias voltage has been applied, and the thin toner layer is formed on an electrostatic latent image. In a developing method for visualizing the electrostatic latent image by supplying the electrostatic latent image to the surface of the electrostatic latent image holding member on which the image is formed, the charge amount of the toner adhered to the surface of the electrostatic latent image holding member by the development is represented by q [C / kg], the charge obtained by the toner by frictional charging with the electrostatic latent image holding member surface is q _p [C / kg], the electric resistance value of the toner holding member is R [Ω · m ² ], l [m] the effective length, the effective surface area of the toner carrying member S _r [m ^2], the amount of toner adhering to the electrostatic latent image holding member surface by the development ^{_{m p [kg / m 2]}} , the electrostatic latent the moving speed of the image holding member surface V _p [m / sec], the toner adhesion amount of the toner carrying member surface m [kg / m ^2] and the toner k the speed ratio of the bearing member surface and the electrostatic latent image holding member surface,
When a, these values conditional expression -100 [V] ≦ {- ( q-q p) m p V p l + q p (km-m p) V p l} · R / S r ≦ 100 [V] It is characterized by being adjusted so as to satisfy the following.

(Operation) The operation of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a sectional view of a main part of a developing device for explaining the operation of the developing method of the present invention. A toner layer 5 made of, for example, a one-component non-magnetic toner is formed on the surface of a toner carrier (developing roller) 4 composed of a conductive shaft 1, an elastic layer 2, and a surface resin layer 3, and this is formed into an electrostatic latent image. The development is carried out by contacting the surface of the photosensitive drum 6 as a holding member. Although the developing method of the present invention can be applied to a well-known regular developing method, a case where reversal development is performed will be exemplified here.

First, the toner carriers are classified according to their electrical resistance values as follows, and a theoretical analysis is performed based on the model shown in FIG.

(A) Conductive toner carrier: The surface resin layer 3 is made conductive, and a developing bias is directly applied to this surface layer by a power source (not shown). The developing bias may be supplied to the shaft 1 by applying a conductive resin layer also to the end of the toner carrier 4 to make the shaft 1 and the surface layer 3 conductive. Even when the elastic layer 2 is also made conductive, a bias can be supplied from the shaft 1 similarly. When the elastic layer 2 is made conductive, the surface resin layer 3 may not be provided.

(B) a semiconductive toner carrier: the elastic layer 2 is semiconductive;
The surface layer 3 is made conductive and a bias is applied to the shaft 1.

(C) Dielectric toner carrier: making the elastic layer 2 conductive;
A bias is applied to the shaft 1 using the surface layer 3 as a dielectric layer.

FIG. 2 is an enlarged schematic view showing the development area of FIG. 1, and shows the inside of each layer on the photoconductor surface of the elastic layer 2, the surface resin layer 3, the toner layer 5, and the electrostatic latent image holding member 6. Alternatively, various physical quantities on the surface are defined as shown in the figure. To generalize the theory, the above-described dielectric toner carrier will first be analyzed.

 Gauss's law is applied to each region in FIG.

div D _p = 0 (1) div D _t = ρ _t (ρ _t = const.) (2) div D _i = 0 (3) The boundary condition is D _p · n = σ where n is a unit normal vector. _b (4) (D _t −D _p ) · n = σ _p (5) (D _i −D _t ) · n = σ _i (6) −D _i · n = σ _r (7) φ _p (0) = 0 (8) φ _p (dp) = φt (dp) (9) φ _t (dp + dt) = φ _i (dp + dt) (10) φ _i (dp + dt + di) = V _b (11) Before reaching the development area When the surface potential of the photosensitive layer 6 and the dielectric layer 3 and Vo and _{V i, σ p = ε p} V o / dp and _{(12) σ i = ε i} V i / di (13) above the boundary value problem Solving and finding the electric field in the toner layer, However, A = dp / ε _p + dt / ε _t + di / ε _i (15) The toner layer is separated at the point Xo where the electric field in the toner layer becomes 0, and development is performed. Electrostatic latent image carrier (photoconductor drum)
Toner amount m _p adhering to six surfaces, the toner adhesion amount of the toner carrying member 4 surface m, the surface speed of the toner carrying member 4 and the electrostatic latent image holding member 6 V _r, V _p, the speed ratio k = When _{V r / V p, m p} = km (Xo-dp) / dt (16) equation (14) and (16), This is a characteristic equation showing the development characteristics of the dielectric toner carrier.

The characteristic formula of the conductive toner carrier is di = 0 in formula (17),
With V _i = 0, Becomes

Next, consider a semiconductive roller. In FIG. 2, d _i =
0, V _i = 0, and consider a semi-conductive layer of a resistor R between the conductive layer and the developing bias power supply. In this case, it is necessary to consider that the effective developing bias varies depending on the developing current.

Considering the frictional charging of the toner particles and the electrostatic latent image holding member 6 surface in the developing region, the developing current I in the development of the entire solid image by using the m _p of formula _{(18), I = I p} -I r = _{- (q-q p) m} p Vpl + q by _{p (km-m p) V} p l (19) developing a current I a potential difference occurs across the resistor R, the effective developing bias V _e is, V _e = V _b + RI / S _r (20). However, the following symbols were used.

I _p : Current due to toner adhesion to electrostatic latent image carrier I _r : Current due to residual toner on toner carrier surface q: Charge amount of toner adhered to electrostatic latent image carrier surface q _p : Electrostatic latent image retention Amount of toner charge due to friction with body surface R: Resistance of toner carrier (Ω · m ² ) l: Effective length of toner carrier S _r : Effective surface area of toner carrier Variation of effective development bias Ve due to development is result in changes in the toner amount m _p, as a result, again V _e varies.
By computer repeats the cycle, variations in V _e is 0.1V
The value of m _p when converged below was true amount of the developing toner.
FIG. 3 shows a flowchart of the calculation.

Based on the above theory, the development characteristics of the three types of toner carriers are derived, and various development parameters are optimized by comparison with experimental results.

(1) Development Characteristics of Conductive Toner Carrier FIG. 4 shows the development characteristics of the conductive toner carrier.
The agreement between theory and experiment is good. In the analysis, it was assumed that the thickness of the toner layer in the development area did not depend on the speed ratio k, and the following experimental values were used. In the experiment, a toner carrier having a surface conductive layer of 63 Ω · m ² was used.

m = 4.8 × 10 ⁻³ kg / m ² dp = 20, dt = 11, di = 50 μm ε _p * = 3.4, ε _t * = 1.2, ε _i * = 6.5 q = −1.10 × 10 ⁻² C / kg (at k = 1.30) q = -1.43 × 10 -2 C / kg (at k = 2.36) q = -1.55 × 10 -2 C / kg (at k = 3.32) V o = -70V, l = 0.2m V _p = 3.93 × 10 ^-2 m / sec S _r = 1.13 × 10 ^-2 m ² q _p = −0.2 × 10 ^-2 C / kg (2) Development characteristics of semiconductive toner carrier Development characteristics in this case Is shown in FIG. As can be seen from the figure, when the electric resistance R of the toner carrier is 1.1 × 10 ⁵ Ω · m ² or less, there is hardly any difference in characteristics due to the resistance value. However, when the electric resistance R exceeds this value, the γ value (characteristic curve) ) Is observed.

Here, as shown in FIG. 6, it should be noted that the developing toner amount m _p per unit area by the ratio of the image portion area to the whole latent image in the developing position (S / So) is changed.

Fig. 7 shows the whole solid development (ie S / S _o = 1)
3 shows the relationship between the amount of developed toner and the resistance R of the toner carrier. As can be seen from the figure, the resistance value is 1 × 10 ⁵
If it exceeds Ω · m ² , a sharp decrease in concentration occurs. Furthermore, as a result of examining the quality of the image quality, it was found that there was no problem at 1.1 × 10 ⁵ Ω · m ² , but that the image density was clearly reduced visually at 1.5 × 10 ⁶ Ω · m ² . Therefore, the resistance R of the toner carrier is R <1.5 × 10 ⁶ Ω · m ² , preferably R ≦
It must be 1.1 × 10 ⁵ Ω · m ² .

Here, the resistance R of the toner carrier in the developing method according to the present invention will be defined. In general, a specific resistance ρ is used as a resistance value of a substance. Here, a product ρ · le (= R and R) of a specific resistance value ρ and a thickness le of an elastic layer is used as a roller parameter that actually governs development characteristics. Is used. However, actually, an electrode having an area S is brought into contact with the peripheral surface of the toner carrier, an ammeter is connected thereto, and a voltage of 10 V is applied to the shaft. _Is calculated, and the resistance value R is obtained by R = _Ro · S. Using the general definition equation of the resistance value, R _o = ρ · le / S, R _o · S = ρ · le. Therefore, the resistance R (= ρ ・ le)
Can be calculated as _Ro · S.

The result of the simulation based on the flowchart shown in FIG. 3 will be discussed in more detail. In the flowchart, the convergence of the effective developing bias can be known by calculating the effective developing bias and repeating a loop returning to the start with n = n + 1. FIG. 8 is a diagram in which the calculation result of the effective developing bias is plotted with the number of loop repetitions n as the horizontal axis. FIG. 8 (a) shows R = 1.5
In the case of × 10 ⁶ Ω · m ² , FIG. 8B shows R = 3.0 × 10 ⁶ Ω · m
The state at the time of ² is shown. However, Vo = 0V.
In FIG. 8 (b), the effective developing bias is diverged, and it can be seen that it is in the resistance range that requires consideration of transient phenomena. In FIG. 8A, the value of the effective developing bias in the first loop varies from the initial value of -100V to about 0V. From this result, the absolute value of RI / S _r in equation (20) is 1
00V or less, that is, −100 <｛− (q−q _p ) m _{p Vp} l + q _p (km−m _p ) V _p1 ｝ · R / S _r <100 This is a condition for obtaining an image.

(3) Development Characteristics of Dielectric Toner Carrier FIG. 9 shows the development characteristics of the dielectric toner carrier, from which the γ value of development can be controlled by the thickness and dielectric constant of the dielectric layer. It can be seen that there is a problem that the development characteristics fluctuate due to a change in the surface potential of the toner carrier caused by frictional charging with the toner. Therefore, practically, means for stabilizing the surface potential of the dielectric layer is required. In the experiment, a toner carrier having a 50 μm-thick dielectric layer on the surface of a 28 Ω · m ² conductive elastic layer was used.

From the above results, the resistance value of the toner carrier was set to 1.5 × 10 ⁶ Ω
・ It became clear that stable and high-density development characteristics can be obtained by setting m ² or less.

Practically, 1) In consideration of prevention of dielectric breakdown of the electrostatic latent image holding member, 1
A resistance value of × 10 ⁴ to 1.5 × 10 ⁶ Ω · m ² is required.

2) It is not easy to manufacture a semiconductive elastic toner carrier having such a resistance range with good reproducibility.

3) Considering that the semiconductive toner carrier studied in the present invention is equivalent to a device in which a resistor is inserted between the surface conductive layer of the conductive toner carrier and the developing bias power source, the toner carrier is surface layer is a stable conductive layer of less than ^{1.5 × 10 6 Ω · m 2} , the developing bias through the protective resistor (about 1Emuomega～100emuomega) to 1 × 10 ⁴ not to be equivalent to 1.5 × 10 ⁶ Ω · m ² Is most effective.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG. 10 is a sectional view of a main part of a developing device used for carrying out the method of the present invention. The developing device 10 includes a toner container 11 for storing the one-component toner 11a, a toner supply roller 14a for supplying the one-component toner 11a to the toner carrier 14, and a toner supply roller 14a for regulating the supplied toner on the surface of the toner carrier 14. A toner layer thickness regulating member 14b for forming a uniform toner layer on the surface, and an electrostatic latent image formed on the surface opposite to the toner carrier 14 which carries and rotates the toner layer and is visualized. A latent image holding member (photosensitive drum) 16, a recovery blade 14 c for collecting the remaining toner in the toner container 11, and a toner container 11
And a spring 14d for pressing the toner layer thickness regulating member 14b against the toner carrier surface 14 with a constant load.

In FIG. 10, reference numeral 15 denotes a charger for applying a required electrostatic charge to a photosensitive drum 16 as a latent image holding member, and 17 denotes an exposure for forming a required electrostatic latent image on the surface of the photosensitive drum 16. A transfer device 18 for transferring an electrostatic latent image of the photosensitive drum 16 as a latent image holding member, which has been visualized by development, to a support such as paper, and 12 a toner carrier 14 A DC power supply for supplying a required current to the toner supply roller 14a; and 13, a protection resistor.

Next, components of the developing device having the above configuration will be described. The toner carrier 14 is made of a metal such as aluminum or stainless steel, or a hard or soft resin such as a phenol resin, an acrylic resin, a urethane resin, a fluororesin, a polyamide resin, a silicone resin, a melamine resin, a polystyrene resin, a polyester resin, and an epoxy resin. Further, a composite made of these composites can be used, and a magnetic roller having a magnetic pole disposed therein may be used.

In this embodiment, a non-magnetic (or non-magnetized) toner carrier 14 having elasticity and conductivity will be exemplified. As the elastic conductive toner carrier 14, a conductive rubber layer (for example, a conductive carbon particle, a metal particle, a metal fiber, a rubber such as urethane rubber, silicon rubber, ethylene propylene rubber, NBR, chloroprene rubber, and butyl rubber) is provided around a shaft. By dispersing etc. 1.
With a resistance of less than 5 × 10 ⁶ Ω · m ² )
Further, the surface is coated with silicon resin, urethane resin, fluorine resin, or the like, or the surface of a high-resistance or insulating rubber roller is coated with conductive resin, or semi-conductive (1.5 × 10 ⁶ Ω · m A roller with a conductive layer on the surface of a rubber roller (less than ² ) can be said to be suitable, but in this case, a conductive urethane coating is applied to the surface of an EPDM rubber roller with a hardness of 30 degrees (JISA type), The case where the elastic conductive toner carrier adjusted so that the resistance value between the surfaces is less than 1.5 × 10 ⁶ Ω · m ² will be described. Outer diameter of metal shaft is 8mm, outer diameter of rubber roller is 18m
m, and the thickness of the conductive urethane paint was 20 to 200 μm.

As a method of developing an electrostatic latent image, a method in which the electrostatic latent image surface and the surface of the toner carrier 14 are brought into a non-contact state and the toner particles are caused to fly by a developing electric field to perform development, Alternatively, there is a method of performing development by sliding.
In the case of the present invention, any method can be applied. In the present embodiment, a case where the toner carrier 14 contacts the electrostatic latent image surface of the electrostatic latent image holder 16 will be described. In the case of non-contact developing method, the amount of charge q _p of toner to acquire a triboelectric charge of the electrostatic latent image holding member 16 side is zero.

The tip end of the toner layer thickness regulating member 14b is formed into a cylindrical surface or a curved surface (a cylindrical surface or a curved surface) and has a rubber hardness of 30.
Of the toner carrier 14 by a pressing force of a spring 14d.
In contact with the surface.

That the cross-sectional tip of the regulating member 14b is an arc or a curve produces an intermediate effect between the effect of pressing the abdominal surface and the effect of pressing the sharp edge, and the desired effect can be obtained with a relatively low pressing force. It was possible to form a thin toner layer and to reliably charge the toner particles by friction. In the toner layer thickness regulating member 14b, good results were obtained when the radius of curvature of the cylindrical surface or curved surface at the tip was 0.1 mm to 20 mm, preferably 0.5 mm to 10 mm.

Other developing conditions use the values described in the above basic configuration or operation, the surface potential of the electrostatic latent image holding member (photosensitive drum) 16 is -500 V, the output of the developing bias power supply 12 is -200 V,
When the development was performed with the value of the protective resistor 13 set to 10 MΩ, an extremely good image having uniform, high density and no fog was obtained.

According to the present invention, it is extremely easy to set the developing conditions for obtaining a good image, as can be seen from the description of the basic configuration or operation of the developing method according to the present invention and the description of the specific examples. A good developed image can be obtained without exception.

Conventionally, various values have been proposed as the volume resistance value of the toner carrier, and a good image has not always been obtained even if the development is performed in accordance therewith. By setting conditions that are comprehensively considered, a high-quality developed image can always be obtained easily, and a practical developing method has been provided.

In the above description, the case where a non-magnetic one-component toner is used has been illustrated. However, the present invention can be applied to a developing method using a magnetic toner, and an elastic roller is illustrated as a toner carrier. Even when a toner carrier is used, a great effect is of course exerted.

Embodiment 2 Next, another embodiment of the developing method according to the present invention will be described.

The first example of the developing method is to leave a part of the non-magnetic toner thin layer on the surface of the toner carrier after the development is completed within the range of the set developing conditions. Similarly, within the range of the development conditions set above, the moving speed vt of the toner carrier, the moving speed of the latent image is vi,
Assuming that the amount of toner adhering to the surface of the toner carrier before development is m ₁ (mg / cm ² ), the value of (vt / vi) · m ₁ varies depending on the nature of the latent image to be developed.

That is, according to the developing method of this embodiment, a part of the non-magnetic toner thin layer is left on the surface of the toner carrier after the development is completed, so that the residual toner facilitates the adhesion of new non-magnetic toner particles. (Call-in), the toner transportability is remarkably improved.

Although it is not clear why the residual toner brings about an improvement in the toner transportability, the residual toner itself causes a triboelectric charge to induce a charge of the opposite polarity (so-called mirror image charge) on the surface of the toner carrier. Since the toner image strongly adheres to the surface of the toner carrier due to the image force, the residual toner scoops up new non-magnetic toner particles in the toner container,
It is considered that this contributes to the improvement of toner conveyance.

Further, even when the non-magnetic toner thin layer is formed by pressing the non-magnetic toner layer thickness regulating member against the surface of the toner carrying member, the regulating member and the toner carrying member may be used when the residual toner passes under the pressure of the regulating member. The toner transportability is significantly improved, such as by forming gaps between the bodies, making it easier for new non-magnetic toner particles to pass under pressure.

On the other hand, even when the amount m ₁ (mg / cm ² ) of the toner adhering to the surface of the toner carrier before development is small, the speed ratio between the toner carrier and the latent image is increased by increasing the speed ratio vt / vi to the latent image. The toner supply amount (vt / vi) · m ₁ can be increased, and a desired high-density image can be obtained. Of course, the density can be increased by increasing m ₁ by changing the toner layer thickness regulating member or its setting conditions.However, as described above, unnecessarily increasing m ₁ leads to the occurrence of fog. It is preferable to use an increase in vi.

In particular, when outputting an image with many solid areas (vt
/ vi) · m ₁ enables to obtain a good image with high contrast. Conversely, when outputting an image composed of line images such as characters, (vt / vi) · m ₁ is reduced,
By suppressing the amount of toner adhering to the latent image, a sharper image can be output. Such (vt / vi) · m ₁
Can be changed by operating a switch or a volume at the discretion of the user to change the rotation speed of the motor or the setting condition of the toner layer thickness regulating member, or in the output image. The ratio of the area occupied by the solid image, the ratio of the line image, and the like can be detected by optical or electrical means, and can be automatically changed according to a predetermined judgment criterion programmed in advance. This makes it possible to control the image density over an extremely wide range even in a developing method using a thin nonmagnetic toner layer.

More importantly actions and effects, and to be able to control the toner conveying ability of the by (vt / vi) of · m ₁ increases or decreases. That is, when outputting an image mainly composed of line images such as characters, the amount of toner consumption is small and the toner transportability does not deteriorate, so that (vt / vi) · m ₁ is suppressed to a small value to achieve a sharper image. Output a simple line image. Conversely, when outputting an image mainly composed of a solid image, the amount of toner supply to the latent image is increased by increasing (vt / vi) · m ₁ , whereby the residual toner on the toner carrier after development is increased. Is also increased to achieve an improvement in toner transportability, and thus a reduction in image density can be effectively prevented. Where (vt / vi)
· M ₁ increase or decrease may be performed manually, latent image properties (properties) that is developed in the image is detected and whether line image or a solid image to be output may be performed automatically controlled.

A specific example of a developing method using a developing device having a basic structure similar to that shown in FIG. 10 will be described below.

In this specific example, the unexposed portion potential v ₀ of the electrostatic latent image
But -500 V, exposed portion potential v ₁ is illustrated for the case of attaching the toner by reversal development method the latent image of -50 V. That is, the background potential and the image portion potential correspond to V ₀ and V ₁ , respectively. A developing bias voltage V ₂ is applied to the conductive layer of the toner carrier 14.
Is applied. In this embodiment, V ₂ =
-200V, vt = 80mm / sec, photoconductor surface speed vi = 40mm / sec,
The contact width between the photosensitive drum 16 and the toner carrier 14 is set to 2-3 mm, and the toner 11a is a negatively charged one-component non-magnetic toner composed of styrene acrylic resin, carbon black, a charge control agent, wax, hydrophobic silica, and the like. The case where it is used will be the standard condition.

The evaluation of the image is performed by fixing a toner image on designated paper for PPC by Toshiba Corporation using a laser printer LB-1305 manufactured by Tokyo Electric Co., Ltd., and measuring the image using a Macbeth reflection densitometer RD-918. Using. However, the laser printer used had a developing unit modified to a one-component non-magnetic developing device shown in FIG.

In addition, the evaluation of toner transportability was A4 for solid black images.
The image density D at the leading edge of the paper and the image density D ′ at the trailing edge are measured.
When -D 'is 0.2 or less, a method of determining good is used, and when -D' exceeds 0.2, a method of determining bad is used. Further, the amount of toner adhering to the surface of the toner carrier before development ^{_{m 1 (mg / cm 2)}} , the amount of toner transferred to the latent image surface by a developing of m ₁ m ₂ (mg / c
m ² ), and the amount of toner remaining on the surface of the toner carrier after development was defined as m ₃ (mg / cm ² ), and these values were measured by the following three methods.

a. A method of collecting the toner on the surface of the toner carrier 14 and the surface of the electrostatic latent image holder 16 with an adhesive tape (Scotch mending tape, 810), and converting them into m ₁ , m ₂ , and m ₃ from the collected area and weight. .

b. By carrying out development, the electrostatic latent image holder before and after toner adhesion
Measure the weight difference of 16 and calculate m ₁ , m ₂ , from m ₃ = m ₁ −m ₂
How to get the m _3. Here, m ₁ is measured under the condition that the developing electric field is increased and the toner layer is completely transferred to the electrostatic latent image holding member 16 side.

c. The toner layer on the surface of the toner carrier is sucked into the cyclone by air, and the weight is measured to obtain m ₁ ,
calculated m _3, a method of obtaining a m ₂ by m ₂ = m ₁ -m _3.

Since the agreement of these three measured values is extremely good, any of the measured values may be used.

_First , the value of m ₂ / m ₁ or m ₃ / m ₁ and the toner transportability (D
−D ′) was examined. The value of m ₁ is 0.4 to 0.6 (mg / cm ² )
The values of m ₂ and m ₃ were changed by variously changing the developing voltage V ₁ -V ₂ . As a result, in the range of m ₂ / m ₁ ≦ 0.9, D−D ′ was 0.2 or less, and good toner transportability was recognized. However, when m ₂ / m ₁ exceeded 0.9, D−D ′ was decreased.
Significant toner conveyance failure exceeding 0.2 was observed. In consideration of variations in various conditions, it is more preferable that m ₂ / m ₁ be 0.8 or less in practical use. When m ₃ / m ₁ is used, when m ₃ / m ₁ ≧ 0.1, and preferably when m ₃ / m ₁ ≧ 0.2, the transportability is good. Expressed in absolute value of the toner amount m ₃ remaining in the toner carrying member 14 surface after development, 0.04 (mg / cm ²⁾ or more, preferably 0.08 (mg / cm ²⁾ or more and good toner conveying ability to This is the condition for obtaining

As described above, in the case of the present embodiment, it is possible to prevent deterioration or reduction of the toner transportability, and to obtain a uniform and high-density good image at all times.

Embodiment 3 This embodiment relates to a case where the amount of toner supplied to a unit area (1 cm ² ) of the latent image surface, that is, (vt / vi) · m _1, is related to the toner transportability. In order to obtain an image having an image density of 1.0 or more, since 0.58 to 0.63 mg of toner must be attached to 1 cm ^{2 of the} latent image surface, m ₃ / m ₁ ≧
To satisfy the condition that 0.1, in order to satisfy _{(vt / vi) · m 1} ≧ 0.7, vt, vi, it may be necessary to set the m ₁ it revealed. Under these conditions, the initial image density can be set to 1.0 or more and the DD 'can be set to 0.2 or less, so that a uniform and high-density solid image can always be output.

When (vt / vi) · m ₁ is large, more toner can be supplied to the latent image and at the same time more toner can be left on the surface of the toner carrier 14 after development. It is desirable to set (vt / vi) · m ₁ to a larger value.

In the developing device having the configuration shown in FIG. 10, the toner carrier
14 is driven to rotate by a motor (not shown). As is well known, the rotation speed of the motor can generally be easily changed by changing a constant in a control circuit. Therefore, by changing the moving speed vt of the toner carrier 14, (vt / vi) · m ₁
Can be changed to improve toner transportability, image density, and sharpness. In particular, when the properties (properties) of an image to be output mainly include a solid portion and a large amount of toner is expected to be consumed by development, a user of a copying machine or a printer is installed in these devices. By operating the switch or the volume control, the rotation speed of the motor is selected, and (vt / vi) · m ₁ is increased, so that a uniform and high-density image free from toner conveyance failure can be output.

In the conventional density adjustment method using the exposure amount or the developing bias, the toner thin layer on the toner carrier
When the conditions for adhering to the surface were reached, it was impossible to further increase the concentration, but according to the developing method of the present invention, (vt / v
i) · m principle can be high density infinitely by increasing the _1, and does not occur density reduction due to toner conveyance failure.

Conversely, if the image to be output mainly consists of line images such as characters and it is expected that a large amount of toner will not be consumed, the motor for driving the toner carrier 14 is decelerated to reduce It is possible to prevent a character image from being broken by development and obtain a sharper image.

Further, in a device for outputting a desired image using image data converted into an electric signal, for example, a laser beam printer, an LED printer, a liquid crystal printer, an ionographic printer, an electrostatic recording device, and a copying machine using these devices, By automatically analyzing the image to be output and automatically controlling the rotation speed of the toner carrier 14 according to the ratio of the solid portion, it is possible to always obtain a uniform, high-density solid image and a sharp line image. .

A more specific description will be given using the developing device shown in FIG. Assuming that the rotational peripheral speeds of the electrostatic latent image holder (photosensitive drum) 16 and the roller type toner carrier 14 are vi and vt, respectively, and the outer diameter of the roller type toner carrier 14 is d, an image to be output is obtained. Length of the included solid image (circumferential direction of photoconductor surface,
Alternatively, when the length of the image transferred on the paper (measured along the traveling direction of the paper) l satisfies l <πd · (vi / vt), the above-described density reduction due to the toner conveyance failure does not occur. . This is because the length of the solid image corresponding to one rotation of the toner carrier 14 is πd ·
(Vi / vt), and if l is less than or equal to this value, there is no need to consider toner conveyance failure as a problem. Therefore,
The length l in the image to be output is, when the solid image exists that satisfies l ≧ πd · (vi / vt ) is increased (vt / vi) · m ₁ in the above manner, if prevent toner conveyance failure Good. In a device that outputs an image using an image-modulated electric signal, image data is automatically analyzed, and (vt / vi) · m ₁ can be automatically changed according to the value of l.
In a so-called analog type copying machine, an electrostatic latent image is formed by forming reflected light from a copy original on the surface of the photosensitive drum 16 and then developed and copied.
Since it is not easy to automatically detect the rotation speed of the toner carrier, it may be possible to set the rotation speed of the toner carrier manually according to the judgment or preference of the user. (Vt / vi) · m ₁ may be set to be changed.

In the above description, the method of changing (vt / vi) · m ₁ by mainly changing vt has been described. However, it is also possible to control m ₁ as being variable. In this case, it is effective to make the pressing force P of the toner layer thickness regulating member 14b against the toner carrier 14 variable. In particular,
In the apparatus shown in FIG. 10, a load regulating member 1 that determines the length of a spring 14d that applies a load to the toner layer thickness regulating member 14b
4e can be moved in the vertical direction in the figure, and if the vertical position is appropriately set by a driving means (not shown), m ₁ is set to 0.1.
(Mg / cm ² ) to about 1.2 (mg / cm ² ).

According to the developing method of this embodiment, the nature of the image to be output, in particular the amount of toner supplied to the latent image in accordance with the length of the solid image for changing the _{(vt / vi) · m 1} , very wide image density It can be changed arbitrarily over the range, and at the same time a sharper line image can be obtained. In addition, by increasing the toner supply amount (vt / vi) · m ₁ to the latent image, more toner can be left on the toner carrier after development, so that the toner transportability can be improved. Can also. Further, by changing vt in accordance with the properties of the image, a great effect can be obtained such that the rubbing of the surface of the toner carrier is not unnecessarily increased and the life of the toner carrier is extended. Can be

Next, Examples 4 to 10 of the first developing device suitable for carrying out the developing method according to the present invention will be described.

First, the basic features of the first developing device are as follows.

Even after long-term use or long-term storage of the developing device,
By setting the toner carrier (developing roller) to an elastic conductive roller having a compression set of 20% or less, image quality is not deteriorated due to deformation of the toner carrier, and high-quality image can be maintained.

The surface roughness of the toner carrier base is 20 μm Rz (JIS B060
1) or less and 50 μm Rmax (JIS B0601) or less, so that the elastic conductive roller (toner carrier) can be manufactured easily and inexpensively, and a high-quality image quality developing device can be obtained. .

In addition, since the surface roughness of the toner carrier is maintained at 10 μm Rz (JIS B0601) or less even after a predetermined abrasion test, even after long-term use of the developing device, the surface is hardly damaged and high quality is maintained. Image quality can be maintained.

Furthermore, after a predetermined abrasion resistance test, by maintaining the resistance value of the toner carrier at 10 ⁷ Ω / cm ² or less,
Even after long-term use of the developing device, the image quality is not affected by the ratio between the white background portion and the image portion of the image, and high quality image quality can be maintained.

Further, the toner carrier base and the conductive layer are firmly integrated with a peel strength of 20 g / mm or more, so that the surface layer of the developing roller does not peel even in initial or long-term use, and high-quality image quality is obtained. Can be maintained.

Embodiment 4 FIG. 11 is a sectional view showing an example of a configuration of a main part of a first developing device suitable for carrying out a developing method according to the present invention. The developing device 20 includes a toner container 2 containing a one-component toner 21a.
1. A toner supply roller 24a that supplies the one-component toner 21a onto a toner carrier (developing roller) 24, and regulates the supplied toner to form a toner layer with a substantially uniform thickness on the toner carrier 24. Toner layer thickness regulating member (coating blade) 24b, which is in contact with and rotates the toner carrier 24 which carries the toner layer and forms an electrostatic latent image on the surface to visualize the electrostatic latent image It comprises a holding member (photosensitive drum) 26, a stirrer 21b for stirring the toner 21a in the toner container 21, a spring 24d for pressing the toner layer thickness regulating member 24b against the toner carrier 24 with a constant load, and the like. .

Further, the photosensitive member of the electrostatic latent image holding member 26 may be any of, for example, selenium, cadmium sulfide, zinc oxide, amorphous silicon, and organic. Was used. The electrostatic latent image holder 26 is uniformly negatively charged by the scorotron charger 25, and is then exposed to an image-modulated light beam, for example, a laser beam 27, so that a required electrostatic latent image is formed on the surface. You. This electrostatic latent image is visualized by the developing device 20 as described above, and a toner image is formed.

The formed toner image is transferred to a transfer paper 28a as an image carrier by a transfer charger (transfer device) 28 and fixed by a fixing device (not shown). Here, the toner remaining on the surface of the electrostatic latent image holding member 26 without being partially transferred is removed by the cleaning blade 29 or the like. Thereafter, the photoreceptor is irradiated with light by the static elimination lamp 30, then charged again by the charger 25, and the above process is repeated.

Here, the principle of visualization of a latent image by the developing device 20 in the above-described process, that is, the principle of development will be described.

Of the surface potential of the charged and exposed photoreceptor (electrostatic latent image holding member) 26, the potential of the unexposed portion is set to Vo and the potential of the exposed portion is set to Vq. The developing bias voltage applied to the body 24 is Vb. Also, the surface potential (effective developing bias) Ve of the toner carrier 24
Is equal to the developing bias voltage Vb, and the electrostatic latent image is reversely developed with a one-component toner charged to a negative polarity. In this reversal development, generally, the effective development bias Ve is set so as to satisfy | Vo |> | Ve |> | Vq | (Vo, Ve, and Vq are all negative), and the development is performed by a potential difference | Ve−Vq |. While doing
The potential difference | Vo−Ve | prevents toner from adhering to a non-image portion (dirt of a white background portion, so-called fog), and required development is performed.

Next, the configuration or component parts of the developing device 20 will be described. First, the toner layer thickness regulating member 24b regulates the amount of toner adhering to the surface of the toner carrier 24,
Since it serves to impart triboelectric charge to toner particles by frictional charging, it is made of a material that is easily frictionally charged.

In the present invention, since the toner particles are negatively charged, substances located on the positive side in the triboelectric charging order, such as silicone rubber, polyamide resin, melamine / formalin resin, polyurethane rubber, styrene acrylonitrile copolymer, wool, quartz, etc. It is preferable to choose. In practice, it is preferable to select a material that does not cause the toner to adhere to the toner layer thickness regulating member 24b even when used for a long period of time and that can form a uniform toner layer on the surface of the toner carrier 24. According to these experiments, when silicone rubber having releasability was used, even when printing on 100,000 sheets of A4 paper, toner did not stick, and a toner layer with a uniform thickness could always be formed. The particles were positively charged negatively, and no deterioration in image quality was observed.

There are also some choices regarding the shape and press-contact style of the toner layer thickness regulating member 24b, such as a method of pressing an antinode of a flat plate, a method of pressing an edge of a flat plate, and a method of pressing an end flat surface of a flat plate. , Both are applicable,
In this embodiment, the end is formed in an arc shape, and means for pressing the arc portion is used. According to this means, the toner layer thickness regulating member 24
The appropriate load b can be reduced, and the driving torque of the toner carrier 24 can be reduced. Further, the thickness of the toner layer on the toner carrier 24 can be made uniform and the charge amount of the toner can be kept uniform.

As the toner supply roller 24a, for example, 100 cells
A piece / 25 mm of urethane foam is suitable, and it is preferable to use a urethane foam which has been subjected to a conductive treatment because it can loosen the electrostatic aggregation of the toner and form a more uniform toner layer. In addition, a brush roller or a low hardness rubber roller may be used. Then
The toner supply roller 24a is set to have a contact depth of about 0.1 to 1.0 mm with respect to the toner carrier 24, and is set to about 1/4 to 2 times the peripheral speed of the toner carrier 24, thereby rotating the toner supply roller 24a. Even when a large amount of toner is consumed, such as in the case of development, required toner can be supplied.

Next, the toner carrier 24 will be described. As shown in perspective in FIG. 12, the toner carrier 24 is partially cut away, and the elastic layer 31b and the flexible conductive layer 31c, which form a roller base having elasticity, are sequentially arranged around the conductive shaft 31a. Are arranged and configured coaxially, and the surface conductive layer 31c is
The shaft is extended from the end surface of the toner carrier 24 and connected to the shaft 31a, and the surface of the toner carrier 24 and the shaft 31a are electrically connected.

In the present embodiment, the above-described toner carrier 24 having a compression set of 20% or less in a predetermined measurement method was used. First, a method for measuring the compression set defined in the present invention will be described with reference to FIG. For compression set, JIS K6301 describes the measurement method, but the shape of the test piece does not match with the present example, so in the present invention, the following toner carrier was used as the test piece. It is based on a simple measurement method close to the actual usage. That is, as described in FIG. 11, the toner carrier 24 is pressed by several components, and when not used or stored for a long period of time, the deformation of the pressed portion does not recover elastically, and so-called distortion occurs. If this is large, a uniform toner layer cannot be formed in the distorted portion, or the electric field generated between the electrostatic latent image holder (photosensitive drum) 26 and the image fluctuates, resulting in image deterioration. In the worst case, white streaks occur in the image.

Such a measurement of the distortion is sufficient if it can be measured using the developing device 20, but it is difficult to quantify the distortion. Therefore, as shown in FIG. 13 (a), a roller having high dimensional accuracy, for example, a roller 32 made of stainless steel and a toner carrier 24 as an object to be measured are arranged at regular intervals, and an optical system 33 is used. And measure the spacing optically. At this time, the center distance between the two can be kept constant, and after removing the DUT 24,
The center distance can be removed and maintained at the same distance as before, and the distance between the two at the same portion can be measured optically.

In FIG. 13A, the outer diameter of the toner carrier 24 is 20 mm, and the center distance between the two is 20.2 mm. If the accuracy of the measured object is good, the distance between the two is measured as 0.2 mm. Also,
The thickness of the part of the device under test 24 other than the shaft is t ₀ mm.
Here, since the outer diameter of the shaft is 8 mm, t ₀ = 6 mm. As described above, if the outer diameter of the shaft is measured first, the thickness of the measured object 24 is measured.

Next, as shown in FIG. 13 (b), the part (FIG. 13 (a)) where the distance between the objects to be measured 24 is measured as described above is compressed using a jig. This compression, in accordance with the JIS K6301, compresses 25% of the wall thickness t _0, and held for 22 hours at 70 ° C. environment. When the thickness of this time and t _2, a t ₂ = 4.5 mm. Next, the compression is stopped, the mixture is left at room temperature for 30 minutes, and the interval between the compressed portions is optically measured as shown in FIG. 13 (c). In this case, the center distance is held equal to the time of FIG. 13 (a), if the interval is determined to be 0.3 mm, the thickness t ₁ in this case it is t ₁ = 5.9 mm. Thus, the compression set is calculated by the following equation.

Therefore, in the above example, t ₀ = 6, t ₁ = 5.9, t ₁ =
It becomes 6.7% as 4.5.

By the way, in the present embodiment, the deterioration of the image due to the above-mentioned distortion can be prevented by selecting and setting the compression set of the toner carrier 24 to 20% or less. However, the pressing force of the toner layer thickness regulating member 24b at this time is 10 to 100 g / cm. Considering changes in conditions such as when the pressing force is the largest, the compression set of the toner carrier 24 is preferably 10%.
The following is good. In the above, the temperature setting during compression is 70
° C, but this is in consideration of the temperature during transportation and storage, and even when kept at a higher temperature or exposed to a lower temperature, the temperature setting at the time of the compression is appropriately selected. It can be measured by this measuring method. We measured at −20 ° C. for low temperatures.

Here, regarding the compression set of the toner carrier 24 having a configuration in which the flexible conductive layer is provided on the elastic layer as shown in FIG. It has been assumed that the compression set is preferably 20% or less, but in the present invention, the toner carrier 24 having a structure as shown in FIG. It is proposed that the distortion factor be 20% or less, preferably 10% or less.

The difference will be described. According to the experiments performed by the present inventors, even when the compression set of the roller base 31b is 20% or less, the image quality may be deteriorated. It was found that this was not due to a change in conditions such as a compressive load on the toner 24, but rather due to the structure and material of the toner carrier 24.

It was also found that the presence of the flexible layer 31c on the surface increased the compression set and decreased the compression set. First, regarding the reason why the strain rate is small, considering the case of compressing the elastic body and the case of compressing the elastic body having a flexible layer on the surface, the latter will receive the load in a wider portion, The deformation at that time is for deforming not only the weighted portion but also other portions. In addition, the manner of changing the amount of deformation from the portion having the largest deformation to the portion having not been deformed becomes gentle, and the influence of distortion itself on image quality deterioration is reduced. That is, sharp breaks and sharp dents on the toner carrier 24 when permanent distortion occurs are less likely to occur.

Also, the reason why the strain rate is large is as follows.
In some cases, the surface layer 31c is deformed due to heat or the like. In this case, the strain rate of the elastic layer 31b was set to 10% or less, preferably 7% or less, and the strain rate of the toner carrier 24 was set to 20% or less. As described above, since the influence of the distortion on the image cannot be determined only by the elastic layer 31b, the distortion of the toner carrier 24 may be considered. On the other hand, when a dent occurs, the depth of the dent
If it was 0.1 mm or less, there was almost no effect on image quality.

Furthermore, as for those whose dent width is 1 mm or more and whose dent is gentle, the image quality is not affected if the depth is 0.2 mm or less. This dent gradually becomes inconspicuous due to the rebound resilience (elastic recovery force) of the toner carrier 24 and disappears during use. The time until disappearance depends on the compression set, hardness, etc., and the smaller the compression set, the better, preferably
20% or less is better and the hardness is better, but the toner carrier
As the hardness increases, the driving torque of the developing device 10 increases, and the processing accuracy and mounting accuracy of the device and components become severe. Therefore, it is better to reduce the compression set.

For the above-mentioned reason, the present inventors have proposed that the hardness of the elastic layer 31b is 40 degrees or less (JIS K6301 A type) or less, but the flexible layer 31c is provided on the elastic layer 31b. When the hardness is increased by several degrees, this is because the part where the hardness meter presses the object to be measured is needle-shaped, so that when measuring from above the flexible layer 31c, the circumference of the part pressed by the needle is also increased. The dent, the load on the needle increases, and the hardness is measured high. As a result of the experiment, the inventors have found that the toner carrier 24 having the flexible layer 31c
Has a hardness of 45 degrees or less, preferably 20 to 35 degrees.

Further, the variation is preferably ± 5 degrees or less, preferably ± 5 degrees.
3 degrees or less is good. As a result, the driving torque of the developing device is reduced.
It is 1 kg · cm or less, and the processing accuracy and mounting accuracy of equipment and parts are eased.

Embodiment 5 In this embodiment, the toner carrier 24 having the structure shown in FIG.
In the above, a toner carrier 24 having a surface roughness of not more than 20 μm Rz (JIS B0601) and not more than 50 μm Rmax (JIS B0601) of an elastic layer 31b having a compression set of 10% or less as a roller substrate was used.

The present inventors have considered that the smoothness or roughness of the surface layer of the toner carrier is preferably 3 μm Rz (JIS B0601) or less. That is, the uniformity of the layer thickness and charge amount of the toner layer formed on the toner carrier 24 is not impaired,
This is because density unevenness and fogging can be prevented from occurring in the image. In the present embodiment, the elastic layer 31b inside the surface layer
The surface roughness of the surface layer 31c formed on the outside thereof can easily be adjusted to 3 μm Rz (J
IS B0601) It was possible to do the following. In particular, the elastic layer 31
By setting the surface roughness of b to 10 μm Rz (JIS B0601) or less, the surface roughness of the surface layer 31c could be reduced to 3 μm Rz (JIS B0601) or less without finishing after forming the surface layer.

At this time, if the thickness of the surface layer 31c is 20 μm or more, the above-described roughness is satisfied. However, when dust is mixed in when forming the surface layer 31c, or when there is an influence of large particles of the surface layer material, finishing is necessary, but it was easier to finish compared to the conventional one. . Also, the elastic layer
31b with a surface roughness of 20μm Rz (JIS B0601) or less, 50μm
By setting Rmax (JIS B0601) or less, the surface layer 31c
Even if the surface roughness is less than 6μm Rz (JIS B0601),
The toner layer formed on the developing roller was uniform, and there was no deterioration in image quality.

This will be described with reference to FIG. FIG. 14 is a cross-sectional view schematically showing an example in which a surface layer 31c is formed on the surface of an elastic layer 31b as a roller base. FIG. 14 (a) shows that the surface of the elastic layer 31b is rough, and FIG. 14 (b) shows that the surface of the elastic layer 31b is smooth. Fig. 14 (a)
In this case, the behavior such as elastic deformation when the surface is pressed is partially different, and it is difficult for the toner layer formed on the toner carrier 24 to be uniform. Therefore, in the case of FIG. 14 (a), the surface roughness of the surface layer must be smaller than in the case of FIG. 14 (b), and when the surface roughness of the elastic layer 31b is severe, However, even if the surface roughness of the surface layer 31c is reduced, the image quality is not improved, and it is not easy to reduce the surface roughness of the surface layer 31c.

In addition, the thickness of the toner layer formed on the toner carrier 24 and the easiness of toner adhesion are affected by the surface roughness of the toner carrier 24. In this case, the surface roughness of the elastic layer 31b as the roller base is also 20 μm Rz (JIS B0601).
Below, 50 μm Rmax (JIS B0601) or less is preferable. This is because, as described above, the behavior of the elastic deformation of the toner carrier 24 is partially different, and the surface roughness of the surface layer 31c is difficult to be uniform, so that the toner layer formed on the toner carrier 24 is This is because it becomes difficult to make them uniform.

Next, a method for forming the above surface layer will be described. First, the surface layer 31c is formed to a thickness of a predetermined value or more on the elastic layer 31b having a compression set of 20% or less, and then polished and finished to a thickness near a predetermined value at least once. Such a forming method is preferable. Because the toner carrier 24
As a characteristic required for the surface layer, the thickness of the surface layer 31c affects its resistance value.

Conventionally, the present inventors have determined that the resistivity of the surface layer 31c is 10 ⁷ Ωcm or less in specific resistance and 1 × 10 ⁹ Ω / c in surface resistance.
m ² or less, preferably 1 × 10 ⁷ Ω / cm ² or less, but when applied to the developing means having such a wide range of resistance, the surface layer 31c has a resistance of 10 ⁷ Ωcm What is necessary is just to form in the thickness below the value which is the following materials.

For example, if a material with a surface resistance of about 10 ⁴ Ωcm is used, 30
The thickness may be not less than μm. However, the surface roughness of the elastic layer 31b must be 20 μm Rz (JIS B0601) or less. In consideration of the variation of each product, it is preferable to form the layer to a thickness of 30 μm or more and then finish it to about 30 μm by polishing. As for the thickness of the surface layer 31c, an example in which only the resistance value is noted has been described, and the thickness may be about 50 μm to 200 μm in consideration of abrasion resistance and polishing accuracy.

Further, particularly when applied to a developing means having a narrow allowable resistance range in which the resistance value of the surface layer 31c affects the image quality,
This method of forming the surface layer 31c is effective because the thickness of the surface layer 31c can be made uniform. Further, when a more accurate thickness is required, layer formation and finishing may be performed a plurality of times.

Furthermore, such a process may be performed a plurality of times even when the thickness of the layer is increased or when different types of layers are stacked. Also,
After forming the surface layer 31c to a predetermined value or more, finishing may be performed a plurality of times, or finishing may be performed after performing layer formation a plurality of times.

After forming the surface layer 31c having a surface roughness equal to or more than a predetermined value, it is preferable to perform finishing to a roughness equal to or less than a predetermined value at least once. This is because the surface roughness of the elastic layer 31b contributes to the adhesion to the surface layer, and the surface roughness of the elastic layer 31b cannot be reduced, or it is easy to reduce the surface roughness of the elastic layer 31b. If not, for example, if the material itself is sticky, the surface is likely to be rough.

When the elastic layer 31b is a foam, foam cells appear on the surface, so that the surface cannot be smoothed. In such a case, a surface layer having a rough surface may be formed on the elastic body layer 31b, and then a desired surface roughness may be obtained by finishing. In particular, when the surface layer is formed on the foam, the surface layer may be formed a plurality of times, and may be finished each time.

Further, even if the surface roughness of the elastic layer 31b is small, it may not be easy to reduce the surface roughness to a predetermined value or less due to dust or the like when forming the surface layer. Even in such a case, it is preferable to finish after forming the surface layer. It may be performed simultaneously with the finishing of the thickness of the surface layer described above.

Example 6 In this example, the surface roughness was 10% after a predetermined wear resistance test.
This is an example in which a toner carrier 24 having a μm Rz (JIS B0601) or less and a compression set of 20% or less is used.

First, the wear resistance test will be described with reference to FIG. FIG. 15 is a perspective view schematically showing a state of a wear resistance test, in which 24 is a toner carrier (developing roller), 35 is sandpaper, and 36 is a pressure plate. The pressure plate 36 has a thickness t of 4 m.
m, the length of the toner carrier 24 along the axial direction is longer than the axial length of the toner carrier 24. When the load w is pressurized, the sandpaper 35 and the toner carrier 24 sandwiched between the toner carrier 24 and the toner carrier 24 are structured such that a uniform load is applied per length in the axial direction. . Further, the toner carrier 24 can rotate while rubbing with the sandpaper 35 in a state where the load w is pressed.

The rotational peripheral speed during the test is the same as the speed when the developing device 20 is used. At this time, sandpaper 35
Are held by the pressure plate 36 and adhered so as not to shift. Sandpaper 35 uses Tamiya model (manufacturer, Komatsubara polishing mill) No. 600 and No. 180. When using No. 600, the load w is set to 100 g / cm, and when using No. 180, the load w is set to 70 g / cm.

First, as the first wear resistance test, the number 600 was 100g / cm
With a load of, rotate for 10 seconds. Then, the surface roughness is measured. Further, using another new toner carrier 24, it is rotated at a load of 70 g / cm at No. 180 for 10 seconds, and then the surface roughness is measured. In the present embodiment, the rotational peripheral speed was set to approximately 70 mm / s because the peripheral speed during development of the toner carrier 24 was approximately 70 mm / s.

The result of the first abrasion resistance test was 10
μm Rz (JIS B0601) or less. The first abrasion resistance test is for preventing the toner carrier 24 from being damaged by dust, dirt, and lump of toner during use of the developing device, thereby preventing image quality from deteriorating. That is, after the first abrasion resistance test, the surface roughness of the toner carrier 24 was 10 μm Rz (JI
If SB0601) or less, the image quality is not degraded due to the toner carrier 24 being damaged.

Next, as a second wear resistance test, the number 600 was 100 g / cm
Then, the toner is rotated at a load of NT / k for ₁ second, and then the surface roughness of the toner carrier 24 is measured. Another new toner carrier 24
Using a No. 180, it is rotated at a load of 70 g / cm for NT / k for ₂ seconds, and then the surface roughness of the toner carrier 24 is measured.

Here, N is the specification of the number of printings (life) of the developing device.
In this embodiment, the number is set to 100,000. T is an average time (second) during which the toner carrier 24 rotates for printing one sheet. In this embodiment, T is 10 seconds. k ₁ and k ₂ are acceleration factors, and k ₁ is 1000
And k ₂ is 2000. Therefore, in this embodiment, NT / k ₁ is 1
6 minutes and 36 seconds, NT / k ₂ is 8 minutes and 18 seconds. As a result of the second abrasion resistance test, the surface roughness of the toner carrier 24 was no more than 10 μm Rz (JIS B0601) at both No. 600 and No. 180.

The second abrasion resistance test is for preventing deterioration of image quality due to abrasion of the toner carrier 24 during long-term use. That is, after the second wear resistance test, the toner carrier
If the surface roughness of 24 is 10μm Rz (JIS B0601) or less,
Even in long-term use, deterioration of image quality due to wear of the toner carrier 24 can be prevented. According to the experiments of the present inventors,
As a result of a printing test of 100,000 sheets using the toner carrier 24 described above, the toner carrier 24 is not damaged and the image quality is not deteriorated, and the toner carrier 24 is worn and the image quality is deteriorated. Did not.

The first developing device suitable for carrying out the developing method according to the present invention is not limited to the embodiments described in the fourth to sixth embodiments, but includes a device having a flexible layer 31c on an elastic layer 31b. The present invention is applicable to those having one or more layers, and is not limited to a contact-type developing unit. In particular, at least the surface is made of a flexible conductive layer 31c, a layer provided with a resistance layer thereon, or a toner carrier 24 having a conductive elastic layer 31b as a roller base. Can be applied to those having a resistance layer.

Example 7 In this example, the resistance value was 1 × after a predetermined wear resistance test.
This is a developing device using a toner carrier 24 having a resistance of 10 ⁷ Ω · cm ² or less and a compression set of 20% or less. First, the first abrasion resistance test was performed in the same manner as in Example 6 above.
Is the same as the abrasion resistance test.

As a result of the first abrasion resistance test, 1 ×
It was 10 ⁷ Ω · cm ² or less. With such a toner carrier 24, it was possible to prevent the toner carrier 24 from being damaged during use of the developing device, thereby changing the resistance value and deteriorating the image quality.

Next, the second wear resistance test is the same as the second wear resistance test as described above. As a result of the second wear resistance test, 60
It was 1 × 10 ⁷ Ω · cm ² or less in both No. 0 and No. 180. With such a toner carrier 24, even when the developing device is used for a long time, it is possible to prevent the resistance value from changing due to the wear of the toner carrier 24, thereby preventing the image quality from deteriorating. Also in this embodiment,
As a result of a printing test of 100,000 sheets, the resistance value was within the allowable range of 1 × 10 ⁷
Ω · cm ² or less, and there was no deterioration in image quality. The potential difference at the time of resistance measurement was measured at 10V.

The present invention is not limited to the embodiment and can be applied to a developing device having a developing roller whose surface resistance value affects image quality. In such a case, the allowable range of the resistance value after the abrasion test depends on the developing device and the developing means, but is determined from the influence of the resistance value on the initial image in each case. Moreover, the surface is a flexible conductive layer.
31c, and further, a resistance layer provided on it,
Alternatively, the present invention can be applied to a toner carrier 24 having the conductive elastic layer 31b as a roller base and having a flexible resistance layer on at least the surface.

Example 8 In this example, a compression set of 10 was used as the developing roller base.
% Or less of the elastic body layer 31b and the flexible surface layer 31c in a predetermined measurement method using a toner carrier 24 integrated with a peel strength of 20 g / mm or more. First, a method for measuring the peel strength will be described with reference to FIG.

FIG. 16 is a schematic view for explaining a method of measuring the peel strength, in which 24 is a toner carrier, 31b is an elastic layer serving as a roller base, and 31c is a flexible surface layer partially peeled. The toner carrier 24 is rotatably supported around a shaft 31a. When the surface layer 31c is used as the toner carrier 24, the part where the surface layer 31c is peeled has a width W as shown in the figure,
Peel in the direction of friction or peeling. At this time,
A cut (cutline in the figure) is made in the surface layer 31c with a width W to reduce the influence of other portions. In addition, the surface layer 31
When c cannot be easily removed, use white gum tape SULION TAPE
(Manufactured by Sugawara Industries, trade name) on the part to be peeled off,
It is good to peel off with c. Further, with respect to a material having stronger adhesion, Alon Alpha (trade name, manufactured by Toa Gosei Chemical Co., Ltd.) may be flown between the surface layer 31c and the SULION TAPE, and then peeled off. Also, what is peeled off by SULION TAPE is already 20 g / mm or less, which can be easily determined by SULION TAPE. When using a tape, it is advisable to make a cut after bonding the tape.

In this manner, when the surface layer 31c is peeled off with the width W (mm), the toner carrier 24 is rotatably supported, so that the toner carrier 24 can be peeled substantially in the normal direction of the toner carrier 24. The peeling force F (g) is pulled in a direction normal to the toner carrier 24 and in a direction perpendicular to the axis. Peeling speed is about 1mm / s
And

In this embodiment, the width W is set to 10 mm. Force F is measured using a load transducer at room temperature, room temperature, preferably at 20 ° C, 50 ° C.
In an environment of% RH, the force F was recorded along with the time being pulled by a recorder. Since the pulling speed is known,
The relationship between the peeled length and position and the force at that time can be easily understood. The force F (g) and the width W (m
m), the peeling force per length was obtained as F / W (g / mm), which was defined as the peeling strength (g / mm).

In addition, according to the record of the recorder, the force F is usually not constant but wavy, and therefore, in the measured value of one round of the toner carrier 24, an abnormal portion, for example, a part of the surface layer 31c does not peel off, The average value of 10 points from the largest value to the fifth value and the smallest value to the fifth value was used except for the value significantly different from the part and the first and last values. Further, another place was peeled off, values of several places were similarly obtained, and their averages were averaged. Further, when a place where the force F is small in one round of the toner carrier 24 is close to a place in another circle of the toner carrier 24 in another place, the average of the ten points and the force F at that time are not obtained. Was used. Further, if there is a difference in the axial direction, the toner carrier at the place where the average value of the force F is the smallest
The average value of the force F for 24 rounds was used. In this embodiment,
The peel strength was 20 g / mm or more. Also preferably, 40
It is preferably g / mm or more, and ideally, one that does not peel off by the above method is preferable.

According to the toner carrier 24 as in the present embodiment, a developing device in which the image quality is not degraded due to the peeling of the surface layer 31c even when used for a long time is obtained. The method of forming the surface layer 31c described in the fifth embodiment can also be applied to the present embodiment. Further, the surface has a flexible conductive layer 31c, a layer provided with a resistive layer thereon, or the conductive elastic layer 31b.
Can be applied to a toner carrier 24 having a flexible resistive layer on at least the surface thereof.

Embodiment 9 In this embodiment, the surface resistance layer 31c of the toner carrier 24 having a compression set of 20% or less is formed of a material containing at least urethane, a material containing fluororesin, or a material containing at least silicone. ing. Further, the elastic body layer 31b as the roller base has a material containing at least urethane, at least ethylene propylene rubber (EP
R or EPDM), a material containing at least an NBR rubber, or a material containing at least silicone. The toner carrier is provided with the fourth to eighth toner carriers.
Also, any of the following tenth embodiments can be applied. Among them, it is particularly preferable that the surface resistance layer 31c is a urethane elastomer, and the elastic layer 31b is urethane, EPDM or NBR rubber. If the urethane elastomer as the surface resistance layer 31c does not have sufficient peel strength with the elastic layer 31c, the elastic layer 31b may be surface-treated with a primer or the like. Further, the surface resistance layer 31c is a fluorine-based material,
Preferably, the elastic layer 31b is made of silicone. In this case, it is also preferable to perform a surface treatment on the elastic layer 31b with a primer or the like.

Further, the surface resistance layer 31c is made of silicone and the elastic layer 31b is made of silicone.
Is preferably silicone or urethane, and the surface resistance layer 31c is preferably silicone and further provided with a fluorine-based resistance layer on its surface. These combinations had sufficient peel strength between the respective layers, and all had a peel strength of 40 g / mm or more.

Thus, the surface resistance layer 31c is selected according to the triboelectric charging polarity. If the surface is to have a positive polarity, urethane or silicone is preferable, and if the surface is to have a negative polarity, a fluorine-based material is preferable. The resistance value of each layer is adjusted by dispersing and containing conductive carbon, metal powder, and metal fibers. For the surface layer, it is particularly important to adjust the layer thickness. In this case, the fourth to eighth and tenth of the following It is necessary to consider the characteristics described in the embodiment.

The present inventors have reported that as the surface layer 31c, SUPEREX DH-20Z313 made by Nippon Miractran and, if necessary, primer or electropack Z-279 (manufactured by Taitai Kako, trade name) or AE-85 (manufactured by Nippon Polyurethane) (Trade name) was used as a urethane elastomer, and Teflon or latex (trade name) was used as a fluorine type. The elastic layer 31b includes EPDM rubber rollers made of Daiwa Rubber, urethane rubber rollers made by Bando Kagaku, NBR rubber rollers made by Zeon (processed by Nankaken), LL made by Bridgestone
Rubber (urethane rubber sponge), Toyo Polymer Rubicell (urethane sponge), Toshiba Silicone (processed by Showa Electric Cable) silicone roller, Inoue MTP ENDUR
(Urethane sponge) or the like was used. Among them, the elastic layer 31b that can be reduced in resistance (10 ⁸ Ωcm or less)
There are Daiwa rubber EPDM rubber roller, Bando Chemical urethane rubber roller, Toyo polymer rubicell, Toshiba silicone silicone, Toray silicone silicone.

Embodiment 10 This embodiment is an example in which a toner carrier 24 having a coefficient of friction of 0.6 or less according to a predetermined measuring method and a compression set of 20% or less is used. First, a method of measuring the coefficient of friction will be described with reference to FIG.

FIG. 17 is a perspective view schematically showing a method of measuring the coefficient of friction.
7 is affixed. The designated paper 37 is sandwiched between the pressing plate 36 and the toner carrier 24 so that a uniform load w can be applied to the toner carrier 24. The pressure plate 36 has a thickness t of 10 mm.
The length of the toner carrier 24 along the axial direction is the toner carrier.
Longer than 24 axis lengths. Further, the toner carrier 24 can rotate while rubbing with the designated paper 37 in a state where the load w is pressed. When measuring, the maximum torque required to start rotating the toner carrier 24 in a stationary state with the load w applied in an environment of normal temperature and normal humidity, preferably at 20 ° C. and 50% is measured and designated. The maximum force in the tangential direction at the portion in contact with the paper 37 is determined. By dividing this force by the total load acting on the portion in contact with the designated paper 37 (the load w plus the weight of the pressing plate as necessary), the designated paper 37
The maximum static friction coefficient between the toner and the toner carrier 24 is determined.

In this embodiment, this value is set to 0.6 or less. According to this embodiment, the drive torque of the toner carrier 24 in the developing device can be reduced, and the drive motor can be reduced in size and cost. In this embodiment, the total driving torque of the driving parts of the developing device such as the toner carrier 24 and the toner supply roller 24a can be reduced to 1 kgcm or less. The coefficient of friction is preferably 0.5 or less.

As described above, according to the first developing device suitable for carrying out the developing method according to the present invention, a high-quality, low-cost developing device can be obtained even after long-term use and long-term storage.

Embodiment 11 Next, an example of a second developing device suitable for carrying out the developing method according to the present invention will be described.

The basic configuration of the developing device is the same as that shown in FIG. 11, and in this embodiment, a flexible conductive layer 31c is provided on the surface as a toner carrier 24, and an elastic layer 31b is provided inside.
Used was used. Here, the surface conductive layer 31c is 1
It has a resistance value of × 10 ⁹ Ω / cm ² or less, the hardness of the toner carrier 24 is 40 degrees or less (JISK6301A type) and the compression set is 20% (J
ISK6301) below. The toner supply roller 24a used was made of urethane foam.

Further, as the toner layer thickness regulating member 24b which regulates the toner layer attached to the surface of the toner carrier 24 and imparts triboelectric charge to the toner particles by frictional charging, a silicone rubber plate which is easily frictionally charged is used. used. Further, as for the shape and pressure contact mode of the toner layer thickness regulating member 24b (coating blade), for example, there are a method of pressing an antinode of a flat plate, a method of pressing an edge of a flat plate, and the like. Is processed into an arc shape of 3 mm in diameter, and the arc portion is pressed.

In such a developing device using the elastic toner carrier 24, the compression set of the toner carrier 24 causes deterioration of image quality. The portion where compression set is likely to occur is a portion pressed by the toner layer thickness regulating member 24b, a portion pressed by the electrostatic latent image holding member (photosensitive drum) 26, and a portion contacting the toner supply roller 24a. Portion and the portion that is in contact with the recovery blade 24c, but the portion that is in contact with the toner supply roller 24a and the portion that is in contact with the recovery blade 24c have almost no effect on the deformation of the toner carrier 24. No problem.

In addition, since the amount of deformation of the portion pressed by the electrostatic latent image holding member 26 is actually 0.1 mm or less, for example, if the toner carrier 24 having a compression set of 20% or less is used, the dent amount, that is, the distortion amount is reduced. Was 0.02 mm or less, the dent was not sharp, and there was almost no deterioration in image quality. The distortion of this part is 0.05mm
It was good if it was the following. However, the toner layer thickness regulating member
The portion pressed by 24b has a large pressing force and a small pressing area, so that the image quality may be deteriorated when the storage environment or the use environment is deteriorated. Needless to say, it is preferable that the environmental conditions are moderate.

FIG. 18 is a cross-sectional view of a configuration example of a main part of a developing apparatus suitable for carrying out the developing method according to the present invention based on the electrophotographic apparatus having the configuration described in FIG. The same reference numerals are given to the same or similar components or components as those in FIG.

In the present embodiment, the configuration is such that the pressing force between the toner carrier 24 and the toner layer thickness regulating member 24b can be reduced. That is, by inserting the stopper 24e into the holder 24f of the toner layer thickness regulating member 24b, the toner layer thickness regulating member 24b is lifted in a direction away from the toner carrier 24, and the pressing force therebetween is reduced.

When using a developing device particularly provided with a means (stopper 24e) capable of reducing the pressing force of the toner layer thickness regulating member 24b as described above, the stopper 24e is pulled out in the direction of arrow A so that the developing device shown in FIG. It will be in the same state as the case. Here, the toner 21a is supplied to the toner container 21 and then used. However, in FIG. 18, the lid 21c cannot be opened by the stopper 24e, and the stopper 24e must be removed. Can also be prevented.

Further, in this embodiment, the lid 21c rotates around the fulcrum 21d, and the lid 21c is opened to supply the toner 21a.However, even when a known toner cartridge is used, It is possible to prevent forgetting to remove the stopper 24e. Further, the tip of the stopper 24e is wedge-shaped as shown in the figure, so that it can be easily inserted and inserted into the toner layer thickness regulating member 24b holder 24f.

According to an experiment conducted by the present inventors, the extent to which the toner layer thickness regulating member 24b should be lifted is (deformation amount of the toner carrier 24 by the toner layer thickness regulating member 24b) ×
If the (permanent compression set of the toner carrier 24) is set to be equal to or less than 0.02 mm, there is almost no deterioration in image quality.

In this embodiment, the amount of deformation is reduced without the stopper 24e.
Since the compression set was 0.2% or less and the compression set was 20% or less, the amount of deformation was 0.1 mm when the stopper was inserted by raising the stopper by 0.1 mm, and the product of the deformation and the compression set was 0.02 mm. Was. It was also found that the provision of the stopper 24e makes the actual amount of distortion smaller than the amount of distortion 0.02 mm calculated by the above equation. This is because if the environment changes without the stopper 24e, the toner carrier 24
This is because the elasticity of the film may change and the amount of deformation may increase.

Further, since the rubber material used for the toner carrier 24 is not a perfect elastic body but a so-called viscoelastic body, if a load is applied to the material, it takes time for the deformation to stabilize. If added, the amount of deformation may increase. That is, the viscosity that affects the time also changes depending on the environment.

In this way, it is possible to prevent the image quality from deteriorating even when the toner carrier 24 and the toner layer thickness regulating member 24b are held without being separated.For example, after use, the stopper 24e is placed in a state where the toner is contained. By inserting and inserting again, it is possible to prevent the image quality from deteriorating even when the apparatus is not used for a long period of time, and to prevent the inadvertent ejection of the toner. For example, when a color image is obtained by a developing device containing color toner, deterioration of image quality can be prevented even when toner is contained.

The means for reducing the pressing force of the toner layer thickness regulating member 24b is not limited to the above example.For example, the spring supporting member 24g supporting the spring 24d may be moved, or the toner layer thickness regulating member 24b may be moved directly. .

The reason why the holder 24f is moved in the present embodiment is that in the case of the configuration shown in the figure, if the friction with the stopper 24e is large, the insertion of the stopper 24e becomes difficult. That is, in the present embodiment, the toner layer thickness regulating member 24b is made of silicone rubber having a large friction. Further, it is easier to operate and design the stopper 24e when the pulling direction of the stopper 24e is not in the direction of the toner container 21. This is because using a known toner cartridge,
This is because the space above the toner container 21 is used and it becomes an obstacle.

As described above, the mechanism or means for reducing the pressing force of the toner layer thickness regulating member 24b is not limited to the above example, and the driving of this mechanism or means may be manual or automatic. For example, using a driving force originally provided in the electrophotographic apparatus, a cam, a link, a gear, or the like may be used, or insertion and extraction may be performed by an electromagnetic force.

Here, in the case where the operation is automatically performed, it is preferable that the stopper 24e and the driving force transmitting portion to the stopper 24e be able to be separated from and connected to each other. For this purpose, it is preferable that the stopper 24e has a shape having a hole or a hook at an end, a shape having a U-shape or a gear, or the like.

FIG. 19 shows an example in which a function is added to the stopper 24e in the configuration shown in FIG. In the case of this example, the pressing force of the toner layer thickness regulating member 24b can be reduced before use, and at the time of use, a pressing force suitable for use conditions can be obtained with the stopper 24e attached. That is, by inserting the stopper 24e in the direction B, the position 24e 'of the stopper 24e becomes the holder 24f, and the holder 24f receives the load set by the spring 24d. At this time, it is preferable that the stopper at the portion of the toner container 21 does not have a large play.

In FIG. 19, the left side surface of the position of the position 24e 'of the stopper 24e is determined by the positioning member 24h at an appropriate position. In addition, position 2 of stopper 24e so that
The right side surface of 4e 'is formed. In addition, stopper
24e also serves as a stopper for the lid 21c.
It can also hold the member (known toner cartridge) forming c.

FIG. 20 shows a configuration example in which the member for reducing the pressing force cannot be removed from the developing device. As shown in the figure, a stopper 24e is provided with a projection 24e "which is engaged with the end of the holder 24f of the toner layer thickness regulating member 24b. When the toner 21 is supplied, it is pulled in the direction A, and when it is not used, it is pushed in the direction B. Before use or when not in use, the position may be set as shown in the figure.

FIG. 21 shows an example in which the pressing force can be reduced by controlling the shape of the holder 24f, and it is possible to reduce the pressing force without inserting the stopper 24e through another member. That is, the toner layer thickness regulating member 24 b and the toner carrier 2
Due to the spring-like action of the holder 24f accompanying the separation and connection with the 4, the separation and connection between the stopper 24e and the toner carrier 24 are facilitated, and this is preferable in order to automatically reduce the pressing force.

As described above, in the case of the second developing device suitable for carrying out the developing method according to the present invention, before or during use, the pressing of the toner layer thickness regulating member 24b pressing the surface of the elastic toner carrier 24 is performed. Since the pressure is reduced, deterioration of image quality due to compression set of the toner carrier is effectively prevented. In addition, there is another effect that the environmental conditions for installing or storing the developing device before use or when not in use can be eased. Moreover, the means for attachment can be realized simply, easily and inexpensively.

Embodiment 12 Next, an embodiment of a third developing device suitable for carrying out the developing method according to the present invention will be described.

First, the basic operation of the developing device according to the present embodiment is as follows. In the first case, since the toner layer thickness regulating member is formed of a flexible plate-shaped polymer, even if the toner layer thickness regulating member or the toner carrier has a slight processing accuracy defect, the processing accuracy defect is reduced. The toner is flexibly deformed to absorb, and a relatively thin pressing force can form a thin toner layer having a uniform thickness. The toner layer thickness regulating member not only has elasticity but also has a plate-like shape and its end is pressed, so that it can be more flexibly deformed.

Further, since the end portion is pressed, the regulation of the toner layer thickness can be performed at a lower pressure than when the belly surface of the plate-like elastic body is pressed. Therefore, the driving force of the toner carrier may be small, and the toner does not adhere to the toner layer thickness regulating member even during long-term use.

Furthermore, since the pressure is not concentrated on a small area as compared with the case where a sharp edge is pressed, the state of the toner layer may fluctuate significantly even if the setting of conditions such as pressure and mounting slightly fluctuates. Disappears. For the same reason, the demands on the processing accuracy of the ends are relatively low. In the method of pressing the end plane, the edge of the end plane may come into contact with the toner carrier due to slight fluctuations in various conditions, causing unevenness of the toner layer thickness. Such a problem is completely eliminated.

Further, if the toner layer thickness regulating member is constituted by a flexible plate-like polymer and a rigid support member inserted and arranged inside the polymer, the plate-like polymer is deformed more than necessary. The toner layer does not become uneven. Also, when manufacturing the toner layer thickness regulating member, the rigid supporting member and the elastic polymer can be easily and integrally molded by a method such as insert molding, so that the elastic polymer is bonded to the supporting member. No need for post-processing such as
Manufacturing and assembly processes are simplified.

In the second case, in addition to the toner layer thickness regulating member, an elastic or flexible plate-like toner supply member is further disposed near the toner carrier, so that when a large amount of toner is consumed by development, Also, the toner can be quickly supplied to the surface of the toner carrier, and a toner layer having a constant thickness can always be formed.

A method of supplying toner to a toner carrier by rubbing the toner carrier with a toner supply roller such as a sponge roller has been known. Need not be driven, and a great effect can be obtained in reducing the size and cost of the device.

Here, the principle of toner supply by the plate-like toner supply member is partially common to the principle of toner thin layer formation by the plate-like toner layer thickness regulating member. In other words, disposing the plate-like toner supply member near the toner carrying member constitutes a space similar to the wedge-shaped space formed by the toner carrying member and the antinode surface of the plate-like toner layer thickness regulating member. The toner aggregate that enters the space due to the movement of the toner carrier and stays there is strongly pressed against the surface of the toner carrier by the subsequent pushing of the toner aggregate and adheres to the surface of the toner carrier. become.

In this way, since the toner is quickly supplied to the surface of the toner carrier, even after the development of a so-called black solid image or the like is performed and a large amount of toner is consumed, the development density does not decrease, and A good image with a uniform density can be maintained. In particular, when the toner layer thickness is regulated at the end of the plate-like member as in the first case, a better regulating action can be obtained as compared with the means for pressing the belly surface, but the wedge-shaped member described above is used. Is not always sufficiently formed, and the toner supply at the toner layer thickness regulation position generally tends to be insufficient. In such a case, if the plate-like toner supply member is used, the toner is reliably supplied, so that it is possible to focus only on the reliable operation at the toner layer thickness restriction position. Derived effects can also be obtained.

Further, when the above-described toner supply roller and the plate-like toner supply member are used at the same time, more reliable toner supply is realized, and a great effect is obtained in performing good development.

The third developing device suitable for carrying out the developing method according to the present invention has the same basic configuration as that shown in FIG. That is, this developing device is a one-component toner 11
a toner container 11, a toner supply roller 14a for supplying the one-component toner 11a to a toner carrier 14 (developing roller) 14, and a toner carrier 14 for regulating the supplied toner.
A toner layer thickness regulating member 14 for forming a uniform toner layer thereon
b, an electrostatic latent image holding member (photosensitive drum) 16 for forming a visible image of the electrostatic latent image formed on the surface opposite to the rotating toner carrier 14 carrying the toner layer; Recovery blade for collecting remaining toner in toner container 11
14c, a stirrer 11 for stirring the toner 11a in the toner container 11
b, a spring 14d for pressing the toner layer thickness regulating member 14b against the toner carrier 14 with a constant load, and a charger 1 for applying a required electrostatic charge to a photosensitive drum as an electrostatic latent image holder 16
Exposure means 17 for forming a required electrostatic latent image on the surface of the electrostatic latent image holding member 16, and developing the electrostatic latent image on the surface of the electrostatic latent image holding member 16 into a visible image by development. For example, it includes a transfer device 18 for transferring to a support such as paper, a DC power supply 12 for supplying a required current to the toner carrier 14 and a toner supply roller 14a via a protective resistor 13, and the like.

As a method for developing an electrostatic latent image, the latent image surface and the toner carrier 14 are used.
A method in which the surface is brought into a non-contact state, a method in which the toner particles fly by a developing electric field to perform the development, a method in which the two are brought into contact to perform the development by rolling or sliding, and a DC electric field is formed between the two. Although any of a developing method and a method of developing by forming an AC electric field can be applied, in the present embodiment, a case where a means for contacting the toner carrier 14 with the latent image surface will be described.

The rubber hardness of the toner layer thickness regulating member 14b is processed into a cylindrical surface or a curved surface (a cylindrical surface or a curved surface).
It is made of a plate-like polymer of 30 to 100 degrees, and its tip is pressed by a spring 14d to press the toner carrier 1
It is in contact with the surface of 4. The fact that the tip of the cross section of the toner layer thickness regulating member 14b is a circular arc or a curve produces an intermediate effect between the effect of pressing the abdominal surface and the effect of pressing the sharp edge as described above. A desired toner thin layer can be formed with a relatively low pressing force, and the toner particles can be frictionally charged reliably. The radius of curvature of the cylindrical surface or curved surface at the tip is 0.1 mm to 20 mm, preferably 0.5 mm to 10
Good results are obtained with mm. In other words, when it is less than 0.1 mm, the same problem as when pressing a sharp edge, 20 mm
This is because, when it exceeds, problems that occur when the abdominal surface is pressed are slightly recognized.

Further, the surface roughness of the leading end surface has a great effect on the uniformity of the toner layer. As a result of examining the correlation between the surface roughness and the uniformity of the image using the ten-point average roughness Rz and the maximum height Rmax of the surface roughness display specified in JIS standard B0601, the toner layer thickness regulating member 14b The surface roughness of at least the portion of the cylindrical surface or the end surface of the end portion that contacts the toner carrier 14
10 μm Rz or less and 30 μm Rmax or less, preferably 5 μm
It was found that a toner layer having substantially no thickness unevenness was obtained when Rz was not more than 10 μm and Rmax was not more than 10 μm, and an image having good uniform density was obtained. Over 10μm Rz or 30μm Rm
When it exceeds ax, a remarkable thickness unevenness occurs in the toner layer,
Streaky density unevenness occurred in the image.

In forming a uniform toner layer, the flexibility of the toner layer thickness regulating member 14b is extremely important. When using a material exceeding 100 degrees as measured by an A-type rubber hardness meter specified in JIS6301, it was difficult to form a uniform toner layer at low pressure. This is because there is a practical limit to the processing accuracy of the toner carrier 14 and the toner layer thickness regulating member 14b, and in order to absorb these inevitable inaccuracy, the toner layer thickness regulating member 14b is Due to the need to press them.

On the other hand, if the hardness of the toner layer thickness regulating member 14b is less than 30 degrees, the tip may be turned over or excessively deformed due to the contact with the toner carrier 14 or the pressure of the toner assembly, so that the toner layer may still be defective. It is easy to be uniform. 30 degrees to 10
If a material in the range of 0 °, preferably 50 ° to 85 ° is used, a toner layer having a uniform thickness is maintained by an appropriate deformation action.

In connection with the above-mentioned deformation problem, the toner layer thickness regulating member 14
There are appropriate values for the thickness b and the free length as an elastic plate. The plate thickness is preferably in the range of 0.5 mm to 15 mm, and the free length, that is, the distance from the support end to the free end of the toner layer thickness regulating member 14b is preferably longer than the plate thickness. Sheet thickness is
If it is less than 0.5 mm, it is difficult to manufacture it accurately by molding, and if it exceeds 15 mm, the toner layer thickness regulating member 14b
In order to obtain sufficient flexibility as described above, the free length must be set long, which causes a problem such as an increase in the size of the apparatus.

In FIG. 10, the tip shape of the toner layer thickness regulating member 14b is a cylindrical surface, but other shapes such as those shown in cross sections in FIGS. 22 to 25 are also conceivable. 22 and 25, the upstream side of the surface of the toner carrier 14 and the toner layer thickness regulating member 14b form a space A in which a relatively large amount of toner can be held. Regulator 14
An effect similar to the toner supply effect obtained when the belly surface of b is pressed, that is, an effect that the toner is quickly supplied to the surface of the toner carrier 14 even when a large amount of toner is consumed is obtained.

23 and 24, the space A becomes small, so that a desired toner thin layer can be formed by relatively low pressure.

In addition, in such a shape, a function of eliminating foreign matter or a lump of toner that is going to enter under pressure is obtained, so that foreign matter does not stay under pressure and a uniform thin toner layer is always formed. . Further, the pressing position of the toner layer thickness regulating member 14b against the toner carrier 14
Various options are possible, as shown side-by-side in the figure.

Normally, as shown at 14b1 in FIG. 26, the tip of the toner layer thickness regulating member 14b may be arranged so as to face the center axis of the toner carrier 14, but if it is arranged at the upstream side as at 14b2, the foreign matter removing function Can work more effectively, and 14
If it is arranged downstream as in b3, the toner supply function can be effectively operated.

When the toner layer thickness regulating member 14b is configured to be pressed by the spring 14d while being supported by the guide member so as to be movable in the vertical direction in FIG. 26, the action direction of the stress by the toner carrier 14 and the toner layer thickness regulating member It can be said that it is advisable to arrange at the position of 14b2 where the movement direction of 14b substantially coincides. 14b1 and
Even when arranged at a position like 14b3, as shown in a side view in FIG. 27, the support 39a of the toner layer thickness regulating member 14b is oriented in a direction different from the direction of the toner layer thickness regulating member 14b by the guide 39b. If the configuration is such that it is movably supported and pressed against the toner carrier 14 by the spring 14d, the same effect as when it is disposed at the position shown in FIG. 14B2 can be obtained.

Further, as shown in a side view in FIG. 28, there are a method of pressing the toner layer thickness regulating member 14b in the forward direction with respect to the rotation direction of the toner carrier 14 and a method of pressing the toner layer thickness regulating member 14b in the reverse direction even at the same pressing position. . The forward pressure contact shown in FIG. 28 (a) has an excellent toner supply function, and the reverse pressure contact shown in FIG. 28 (b) has an excellent foreign matter removing function.

There are two methods for manufacturing the toner layer thickness regulating member 14b, a method of obtaining a curved surface at the tip by cutting and a method of obtaining the above-described shape by molding. When a method by cutting is used, an extremely accurate curved surface can be obtained. On the other hand, the molding method is excellent in mass productivity and is practically advantageous. When the toner layer thickness regulating member 14b having the shape as shown in FIG. 10 is manufactured by a molding method, molds 40a and 40b having a structure as shown in cross section in FIG. 29 (a) are usually used. In this case, burrs must not be formed on the curved surface at the tip end of the toner layer thickness regulating member 14b, so it is necessary to break the mold in the vicinity of the flat portion of the side surface or the rising portion of the curved surface (position 40c in FIG. Occurs. In such a shape, since the curved surface at the tip is surrounded by the first portion 40a of the mold, air bubbles easily accumulate in this portion at the time of molding, which often results in poor precision of the curved surface.

In general, when a mold is broken at a flat or curved portion, remarkable burrs are generated at this portion, and a complicated deburring step is required after molding. On the other hand, if the tip shape of the toner layer thickness regulating member 14b is constituted by a curved surface and a sharp end as shown in FIG. 22 or FIG. 24, and the curved surface is set so as to be pressed by the toner carrier 14, 29 (b), the mold can be divided.

With the molds 41a and 41b having such a shape, bubbles are less likely to accumulate on the curved surface portion, and so-called burrs can be cut off at sharp edges, so that it is not necessary to provide a deburring step after molding. By adopting such a shape, the defect rate of the product was remarkably reduced even in the mass production process, and the manufacturing cost was also reduced.

In the developing device of the present embodiment, in order to uniformly press the flexible toner layer thickness regulating member 14b having a hardness of 30 to 100 degrees against the toner carrier 14, it is preferable that the member is accurately supported by a rigid body. In order to equalize the pressure in the longitudinal direction of the toner layer thickness regulating member 14b, it is appropriate to directly press the elastic toner layer thickness regulating member 14b with the spring 14d as shown in a side view in FIG. Instead, it is desirable that the toner layer thickness regulating member 14b be supported by the rigid support member 42 to make the pressure uniform, as shown in a side view in FIGS. 30 (b) and (c). However, the support member 42 does not necessarily have to be a rigid body. For example, as shown in FIG. 30 (d), a strong elastic plate 43 such as a phosphor bronze plate or a stainless plate having a thickness of 0.1 mm or more is used. May be supported.

In these examples, after the toner layer thickness regulating member 14b is molded, it is bonded to the support member 42 or the elastic plate 43 ((b)
And (d)) or a step of inserting (in the case of (c)). In the case of bonding, strong adhesiveness is required structurally, so that the materials and adhesives of the components are limited.

When the toner layer thickness regulating member 14b is inserted into the U-shaped rigid support member 42 and used as in the example of FIG.
In order to securely hold the toner layer thickness regulating member 14b, it is necessary to push the toner layer thickness regulating member 14b into a groove having an opening slightly smaller than the thickness of the toner layer thickness regulating member 14b. Was deformed, which sometimes caused unevenness in the thickness of the toner layer.

On the other hand, if the support member 42 is inserted and disposed inside the toner layer thickness regulating member 14b during molding as shown in perspective in FIG. 31, and so-called insert molding is performed, all of the above problems can be solved. it can. Support member 42 is 0.1mm thick
It is preferable that the metal plate has a length of from 1 mm to 3 mm, and the length from the tip of the support member 42 to the tip of the toner layer thickness regulating member 14b, that is, the free length of the regulating member 2b is 1 mm to 10 mm, preferably the toner layer thickness regulating member 14b. When the thickness l is equal to or greater than the thickness l, the elasticity of the toner layer thickness regulating member 14b is utilized, and a more uniform toner layer type is possible.

In addition to regulating the toner layer thickness, the toner layer thickness regulating member 14b is required to have a function of frictionally charging toner particles to a predetermined polarity. Therefore, as a material constituting the toner layer thickness regulating member 14b, it is necessary to select a material which is easily charged to a polarity opposite to the charging polarity of the toner particles in a well-known friction charging sequence.

When the toner particles are negatively charged, silicone rubber,
Formalin resin, PMMA, polyamide, melamine resin, polyurethane rubber, polyurethane sponge and the like are used. When the toner particles are positively charged, a fluororesin,
Polyethylene, acrylonitrile, natural rubber, epoxy resin, nitrile rubber and the like are preferred. However, if the triboelectrification property is controlled by mixing a dye etc. into these materials,
It is also possible to provide the opposite charging characteristics.

Another property required for the material constituting the toner layer thickness regulating member 14b is that the toner does not adhere to the toner layer thickness regulating member 14b even after long-term use. Such toner fixation causes the toner to be non-uniform, and the charging of the toner becomes insufficient.

According to detailed experiments by the present inventors, it has been found that among the above-mentioned various materials, those containing silicon rubber or urethane rubber as a main component give the best results for such purpose. In particular, silicone rubber, because of its release properties,
Even after a very long period of use (approximately 100,000 printing steps), no toner sticking occurred. However, it is preferable that these rubbers do not contain additives such as migratory plasticizers, vulcanizing agents, and antioxidants, or that even if they are contained, they are extremely small. That is, it is important to select a material that does not contaminate the toner material, the toner carrier 14, and the photoreceptor as the electrostatic latent image holder 16 due to a precipitation phenomenon of inclusions called bleed or bloom.

When using silicone rubber, it is necessary to pay attention to its wear resistance. In general, silicon rubber is inferior to other rubber materials in terms of abrasion resistance, and therefore, a material improved by adding a filler or the like should be used. According to the experiments by the present inventors, when the contact area between the regulating member and the developing roller becomes 5 times or more as compared with the initial state due to abrasion, the state of the toner layer, particularly the thickness of the toner layer, changes, which is not preferable.

As a problem to be noted when molding and processing the elastic toner layer thickness regulating member 14b, there is a problem of "sink" at both ends. Here, "fin" means that the length 1 shown in FIG. 31 is different at both ends and the center in the longitudinal direction. As an example, when a silicone rubber toner layer thickness regulating member having l = 10 mm, t = 3 mm, a tip radius of 1.5 mm, and a length of 200 mm was molded and examined for processing accuracy, a “15 mm range from both ends in the longitudinal direction was obtained. A sink occurred, and in this range, 10 <l ≦ 11 mm.

This “sink” is mainly caused when the molded product is pulled out from the mold, and it is difficult to completely eliminate the molded product. Therefore, the length was set to 250 mm at the time of molding, and both ends were cut by 25 mm each after being pulled out from the mold. As a result, an extremely accurate regulating member could be obtained. Before cutting
Accuracy was 9.95 ≦ l ≦ 10.90
The accuracy was improved to 9.95 ≦ l ≦ 10.05. The length of the part to be cut off is preferably 5% or more of the entire length including both ends.

By using the toner layer thickness regulating member 14b having the configuration described above, a thin toner layer having a very uniform thickness can be formed on the surface of the toner carrier 14 for a long period of time.

By using the toner layer thickness regulating member 14b having the above configuration, a thin toner layer having a very uniform thickness can be formed on the surface of the toner carrier 14 for a long period of time, and a high-quality image can be generally obtained. There are two things to be aware of. That is, when a large amount of toner is consumed due to development of a solid image on the entire surface, how to quickly supply the toner 11a to the surface of the toner carrier 14 to form a toner layer having a predetermined thickness. This is a problem that always accompanies the method of developing with a thin layer of toner, but becomes more important when the one-component non-magnetic toner 11a is used because toner cannot be supplied by magnetic force.

As shown in FIG. 10, it is already known that a method of rubbing an elastic toner supply roller 14a made of sponge, rubber, or the like against a toner carrier 14 can improve toner transportability by the toner carrier 14. Technology.
A method is also known in which the toner supply roller 14a is made conductive and a voltage is applied thereto to supply the toner by an electric field. However, this method may not always provide sufficient toner transportability, and generally needs to provide a speed difference between the surface of the toner carrier 14 and the surface of the toner supply roller 14a. The force required for driving the roller 14a is increased, the toner supply roller 14a occupies a space in the developing device, hinders the overall size reduction, and is not preferable in reducing cost. There are many problems.

The present inventors have studied the arrangement of a plate-like toner supply member 14f as shown in FIG. 32, as a cross-sectional view of a main part, as a means for reliably transporting toner with a simpler configuration. The effect was confirmed. Improvement in toner supply is achieved by the following two principles.

I. The toner 11a is pushed into the space A 'formed by the plate-like toner supply member 14f, the toner layer thickness regulating member 14b, and the toner carrier 14, and the internal pressure in the space A' increases due to the pressure of the subsequent toner. Therefore, even if a large amount of toner is consumed, the toner is promptly supplied onto the toner carrier 14.

II.In the wedge-shaped space B 'formed by the plate-like toner supply member 14f and the toner supply roller 14a, the same internal pressure as in the case of the above I occurs, and the toner is pressed against the toner carrier 14 again, so that the toner is Supplied promptly.

In order to simultaneously obtain the effects of I. and II., It is preferable that the plate-like toner supply member 14f is formed of an elastic body or a flexible member, and the antinode surface is lightly pressed against the toner carrier 14. As the material of the plate-like toner supply member 14f, various rubber plates (thickness is preferably about 0.5 to 3 mm) and resin plates (thickness is preferably about 20 μm to 1 mm) as described above can be used. Rubber, urethane rubber, polyester film, polyimide film, Teflon film,
It can be said that PET film is more suitable.

Further, a large amount of toner is packed in the space A 'by the rotation of the toner carrier 14, and the internal pressure is adjusted according to the internal pressure so that an excessive amount of toner does not pass under the pressure of the toner layer thickness regulating member 14b. It is preferable that the plate-like toner supply member 14f can be moved toward and away from the toner carrier 14. The reason is that if the plate-like toner supply member 14f is configured to separate from the toner carrier 14 when the internal pressure increases and reaches a certain value (broken line in FIG. 32), the internal pressure does not increase to a certain value or more. The toner layer does not become too thick. If the space A 'is not a closed space due to the separation of the toner supply member 14f from the toner carrier 14, a part of the toner in the space A' can return to the toner container 11 from the gap between them. The pressure increase in A 'can be reliably suppressed.

When the elastic or flexible toner layer thickness regulating member 14b as described above is used, the contacting / separating operation is automatically performed according to the stiffness of the plate. Can be supplied. FIG. 33 is a side view showing an example of a configuration in which a rigid plate is used to obtain the same effect. Since the rigid plate 14f 'is rotatably supported by the hinge 14g and is pressed against the toner carrier 14 by the spring 14h, the internal pressure of the toner can be more strictly controlled.

Since the plate-like toner supply member 14f or 14f 'is attached for the purpose of obtaining the toner supply function, there is no need to exert the function of regulating the toner layer thickness unlike the toner layer thickness regulation member 14b. . Strictly speaking,
It is not preferable that the toner supply members 14f and 14f 'form a toner layer having a thickness smaller than a desired toner layer. Accordingly, when the pressures of the toner layer thickness regulating member 14b and the plate-like toner supply member 14f (or 14f ') on the toner carrier 14 are set to P1 and P2 [g / cm ² ], respectively, P2> P2 is set. This is very important.

Modified examples of the plate-like toner supply member 14f are shown in a side view in FIGS. 34 and 35. FIG. 34 focuses on providing the closed space A ', and the plate-like toner supply member 14f may be a rigid plate. FIG. 35 is intended to obtain the effect of I. In this case, the closed space A 'is not formed, but the toner supply can be improved by the wedge-shaped space B'. Of course, the combined use of the plate-like toner supply member 14f (or 14f ') shown in FIGS. 32 to 35 and the toner supply roller 14a shown in FIG. 10 is remarkable in improving the toner transportability. Effect.

By making the plate-like toner supply member 14f conductive,
Excessive charging of the toner can be prevented. further,
A DC voltage, an AC voltage, or a voltage obtained by superimposing the DC voltage or the AC voltage is applied thereto, and the supply of toner to the toner carrier 14 can be further promoted by an electric field. When the toner particles are negatively charged, the potential of the toner supply member 14f may be set to a negative potential side of the toner carrier 14. When the AC electric field is superimposed on such a DC electric field, the toner particles are more reliably supplied to the surface of the toner carrier 14 while reciprocating between them. When the surface of the toner carrier 14 is conductive, the surface of the plate-like toner supply member 14f on the toner carrier 14 side is a high resistance layer or an insulating layer, and the opposite side is a conductive layer. It is preferable to apply.

In addition, as the toner supply roller 14a in FIG. 10, a polyeletan foam roller is provided with conductivity of 10 ⁸ Ωcm or less by post-impregnation with conductive carbon,
It is preferable that the conductive carbon be dispersed in a polyurethane solution before foaming and then foamed to form a conductive foam. Making the toner supply roller 14a conductive is important for preventing excessive charging of toner particles, as is the case with making the toner supply member 14f conductive.

As described above, the developing device suitable for carrying out the developing method according to the present invention is a simple, inexpensive, easy-to-manufacture and easy-to-assemble structure, but is always a uniform one-component toner having a desired thickness. A thin layer can be formed, and good development can be constantly performed over a long period of time.

[Effects of the Invention] As described above, according to the present invention, it is extremely easy to set development conditions for obtaining a good image, and a good developed image can be obtained without exception. That is, various values have been proposed as the volume resistance value of the toner carrier in the related art, and a good image could not be obtained even if the development was performed in accordance therewith. It is possible to set conditions in consideration of the situation, and a truly practical developing method can be obtained.

In the embodiment, the case where a non-magnetic one-component toner is used is illustrated. However, the present invention is applicable to a developing method using a magnetic toner, and an elastic toner carrier is exemplified as a toner carrier. Of course, even when a hard toner carrier made of resin or resin is used, a great effect is exerted.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a developing device for explaining the operation of the developing method of the present invention, and FIG. 2 is a diagram showing the relationship between the components of a toner carrier and electrical characteristics for explaining the operation of the developing method of the present invention. FIG. 3 is a schematic diagram showing the relationship, FIG. 3 is a flowchart of a computer simulation supporting the operation of the developing method of the present invention, FIG. 4 is a developing characteristic diagram when a conductive toner carrier is used in the developing method of the present invention, and FIG. FIG. 6 is a view showing a developing characteristic when a semiconductive toner carrier is used in the developing method of the present invention. FIG. 6 is a diagram showing an electrostatic latent image holding in a developing device using a semiconductive toner carrier in the developing method of the present invention. FIG. 7 is a graph showing the relationship between the electrostatic latent image area of the body surface and the amount of toner adhered per unit area. FIG. 7 shows the electric resistance of the toner carrier and the total solid in a developing apparatus using a semiconductive toner carrier in the developing method of the present invention. Developed FIG. 8 is a graph showing the relationship between the amount of toner adhered to the surface of the electrostatic latent image holding member, and FIG. 8 shows the number of loop repetitions, the effective bias value, and the like in the flowchart of FIG. FIG. 9 is a developing characteristic diagram when a dielectric toner carrier is used in the developing method of the present invention, and FIG. 10 is a cross-sectional view showing a main part of a developing device used for carrying out the developing method of the present invention. Fig. 11,
FIG. 12 is a cross-sectional view illustrating a configuration example of a main part of a developing device suitable for performing the developing method according to the present invention. FIG. 12 is a configuration example of a toner carrier used in the developing device suitable for performing the developing method according to the present invention. 13 (a), (b) and (c) are side views showing a method for measuring the compression set of a toner carrier for a developing device suitable for carrying out the developing method according to the present invention, and FIG. (A) and (b) are cross-sectional views showing an example of a main configuration of a toner carrier, FIG. 15 is a perspective view showing a wear resistance test method of the toner carrier for a developing device, and FIG. 16 is toner for a developing device. FIG. 17 is a perspective view showing a method for measuring the peel strength of the carrier, FIG. 17 is a perspective view showing a method for measuring the coefficient of friction of the toner carrier for a developing device, and FIGS.
The drawings are cross-sectional views showing different main configuration examples of a developing device suitable for carrying out the developing method according to the present invention. FIGS. 22 to 25 are toner layer thicknesses in the developing device suitable for carrying out the developing method according to the present invention. FIG. 26 is a side view showing a different configuration example of the regulating member, FIG. 26 is an explanatory diagram showing the relationship between the arrangement position and characteristics of the toner layer thickness regulating member in a developing device suitable for carrying out the developing method according to the present invention, and FIG. 28 (a) and 28 (b) are cross-sectional views of main parts showing another example of a supporting structure of a toner layer thickness regulating member in a developing device suitable for carrying out the developing method according to the present invention. FIGS. 29 (a) and (b) are explanatory diagrams for explaining a difference in characteristics depending on the direction of a toner layer thickness regulating member in a developing device suitable for a developing device according to the present invention. Layer thickness regulating member Sectional view showing a shape-type embodiment, a 30
FIGS. 9A, 9B, 9C, and 9D are side views of main parts showing different examples of the configuration of supporting the toner layer thickness regulating member in the developing device suitable for carrying out the developing method according to the present invention. FIG. 31 is an explanatory diagram for explaining the difference in characteristics depending on the size and shape of the toner layer thickness regulating member in a developing device suitable for carrying out the developing method according to the present invention, and FIG. 32 is suitable for carrying out the developing method according to the present invention. FIG. 33 to FIG. 35 are cross-sectional views of an essential part showing an example of disposition of a plate-like toner supply member in a developing device. FIGS. It is principal part sectional drawing which shows an example. 1, 31a ... conductive shaft 2, 31b ... elastic layer 3, 31c ... surface resin layer 4, 14, 24 ... developing roller (toner carrier) 5 ... toner layer 6, 16, 26 ... Electrostatic latent image carrier (photosensitive drum) 11, 21 Toner container 11a, 21a Toner 12 Development bias power supply 14a, 24a Toner supply roller 14b, 24b Toner layer thickness regulating member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Endo 6-78 Minamicho, Mishima-shi, Shizuoka Prefecture Inside the Technical Research Institute, Tokyo Electric Company (72) Inventor Yoshimitsu Otaka 6-78 Minamicho, Mishima-shi, Shizuoka Prefecture Technology of Tokyo Electric Co., Ltd. (56) References JP-A-64-52180 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/08 G03G 15/06

Claims (1)

(57) [Claims] A thin toner layer formed on the surface of the toner carrier to which a developing bias voltage is applied, and supplying the thin toner layer to the surface of the electrostatic latent image holding member on which the electrostatic latent image is formed; In a developing method for visualizing an electrostatic latent image, the charge amount of the toner adhered to the latent image holding member by development is represented by q
[C / kg], the charge obtained by the toner by frictional charging with the latent image holding member is q _p [C / kg], the electric resistance value of the toner holding member is R [Ω · m ² ], the effective length _{l [m], S r [} m 2] of the effective area of the toner carrying member, the amount of toner adhering to the latent image bearing member by the developing m _p [kg
/ m ^2], the moving speed of the electrostatic latent image holding member surface V _p [m / sec], the toner adhesion amount of the toner carrying member surface m [kg / m ^2], and the surface of the toner carrier and the electrostatic latent image when the speed ratio of the retention member surface was k, these values are condition -100 [V] ≦ {- ( q-q p) m p V p l + q p (km-m p) V p l} · R / A developing method characterized by being adjusted so as to satisfy S _r ≦ 100 [V].