JP2014056109A - Toner holder, developing device using the same, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably form a toner layer according to surface waviness, even when an electrifying member is used in a contact state, in such a state that the surface of a conductive base material is covered with a covering layer.SOLUTION: A developing device includes a toner holder 1 arranged to face an image holder 5 holding a latent image, in a non-contact state, holding toner TN, and circularly rotated, an electrifying member 2 electrifying the toner TN held by the toner holder 1, and development electric field forming means 3 for flying the toner TN held by the toner holder 1 and electrified by the electrifying member 2 to the latent image on the image holder 1 and adhering the toner TN to the latent image, to perform development. The toner holder 1 includes a conductive base material 1a and a covering layer 1b covering the surface of the conductive base material 1a. The surface waviness of the covering layer 1b satisfies relations of Wca≤0.5(μm) and Wc-Sm≥2.5(mm), where Wca is the average height of a waviness curve element and Wc-Sm is the average length of the waviness curve element.

Description

  The present invention relates to a toner holder, a developing device using the same, a process cartridge, and an image forming apparatus.

As developing devices used in conventional electrophotographic image forming apparatuses, for example, those described in Patent Documents 1 to 3 are already known.
In Patent Document 1, as a developing sleeve, a resin film is formed on the surface of a cylindrical sleep substrate by a spray coating method, and even if the resin coating is formed on the sleeve substrate surface by a spray coating method, In order to prevent large waviness in the longitudinal direction, it is disclosed that grinding is performed with high accuracy in advance so that the maximum waviness Wcm ≦ 0.35 μm in the longitudinal direction is achieved by a centerless grinding apparatus.
In Patent Document 2, in order to prevent unevenness in image density caused by unevenness in toner adhesion due to large surface roughness and waviness, the cylindrical substrate of the developing roller is cut by machining so that the diameter is constant. The surface roughness of the cylindrical substrate is 0.06 mm or less, the undulation Wca of the cylindrical substrate is 0.5 μm or less, and the ten-point average roughness Rz of the surface of the surface layer is The point which is 4 micrometers or less is disclosed.
In Patent Document 3, in order to make the charge amount of toner in the developing chamber uniform, a new toner is supplied from the toner cartridge into the developing chamber when the toner cartridge containing new toner is replaced. It is disclosed that after the residual toner remaining in the developing chamber is agitated to obtain the agitated toner, the agitated toner is recovered from the developing chamber into the toner cartridge.

JP 2000-293030 A (Embodiment of the Invention, FIG. 2) JP 2004-37663 A (Embodiment of the Invention, FIG. 1) JP 2009-244456 A (Best Mode for Carrying Out the Invention, FIG. 3)

  The technical problem to be solved by the present invention is a mode in which the surface of a conductive substrate is coated with a coating layer, and even if the charging member is used in a contact state, the toner layer is stabilized following the surface waviness. It is an object of the present invention to provide a toner holding member that can be formed in a conventional manner, a developing device using the same, a process cartridge, and an image forming apparatus.

The invention according to claim 1 is a toner holding body that is arranged in a non-contact manner facing an image holding body on which a latent image is held, holds toner, and circulates and rotates. And the surface waviness of the covering layer is defined as Wca ≦ Wca, where the average height of the waviness curve element is Wca and the average length of the waviness curve element is Wc−Sm. The toner holding member satisfies the relationship of 0.5 (μm) and Wc−Sm ≧ 2.5 (mm).
According to a second aspect of the present invention, in the toner holder according to the first aspect, the conductive base material is a metal cylindrical base material.
According to a third aspect of the present invention, in the toner holder according to the first or second aspect, the surface waviness of the conductive substrate has Wca and Wc-Sm that are comparable to those of the coating layer. And a toner holder.
According to a fourth aspect of the present invention, in the toner holder according to any one of the first to third aspects, the coating layer is configured by a spray coating method.

According to a fifth aspect of the present invention, there is provided a toner holding body according to any one of the first to fourth aspects, a charging member that charges the toner held by the toner holding body, and the image holding body and the toner holding body. By forming a developing electric field that includes at least a DC component having a predetermined potential difference, the toner held on the toner holding member and charged by the charging member is caused to fly to the latent image on the image holding member. And a developing electric field forming means for developing the toner by attaching toner to the latent image.
According to a sixth aspect of the present invention, there is provided the developing device according to the fifth aspect, wherein the average particle diameter of the toner is d (μm) and the surface roughness of the toner holding member is an oil sump depth Rvk per surface area of 1 cm ² . The developing device is characterized by satisfying a relationship of V0 / d <6.8 × 10 ⁻⁴ , where V0 is the amount of oil pool corresponding to the amount of oil accumulated in the water.

According to a seventh aspect of the present invention, in the developing device according to the sixth aspect, the developing electric field forming means forms an electric field in which an alternating current component whose potential changes periodically is superimposed on the direct current component as the developing electric field. There is a developing device.
According to an eighth aspect of the present invention, in the developing device according to any of the fifth to seventh aspects, the charging member is a metal plate-like member that contacts the surface of the toner holding member. .

According to a ninth aspect of the present invention, there is provided a process cartridge that is detachably attached to a receiving portion that is formed in advance on the image forming apparatus casing, and an image holding body that holds a latent image, and the image holding body. 9. A process cartridge comprising: a developing device according to claim 5 for developing the latent image formed with toner.
The invention according to claim 10 includes an image carrier that holds the latent image, and the developing device according to any one of claims 5 to 8 that develops the latent image held on the image carrier with toner. An image forming apparatus characterized by that.

According to the first aspect of the present invention, even when the charging member is used in a state where the surface of the conductive base material is coated with the coating layer, the toner layer is stably tracked following the surface waviness. Can be formed.
According to the second aspect of the present invention, the toner layer can be stably formed by following the surface waviness even if the charging member is used in a contact state with a simple configuration.
According to the third aspect of the present invention, in forming a desired surface waviness curve for the toner holding member, the toner holding member can be formed in a desired manner by simply performing a desired grinding process on the surface of the conductive substrate. A surface waviness curve can be easily formed.
According to the fourth aspect of the invention, in forming a desired surface waviness curve on the toner holding member, the coating layer can be easily formed following the surface of the conductive substrate.
According to the invention of claim 5, even when the charging member is used in contact with the toner holding member whose surface of the conductive base material is coated with the coating layer, the toner layer is formed following the surface waviness. It can be formed stably.
According to the sixth aspect of the present invention, when non-contact development is performed using toner, it is possible to effectively prevent a situation in which poorly charged toner is used for development with a simple configuration.
According to the seventh aspect of the present invention, even when the developing electric field in which the alternating current component is superimposed on the direct current component is used, in the non-contact development using the toner, the poorly charged toner is formed with a simple configuration. It is possible to effectively prevent the situation where it is used for development.
According to the eighth aspect of the present invention, when performing non-contact development using toner, it is possible to stably form a toner layer following surface waviness with a simple and inexpensive configuration.
According to the ninth aspect of the present invention, even when the charging member is used in contact with the toner holding member whose surface is covered with the coating layer, the toner layer is formed following the surface waviness. A process cartridge including a developing device that can be stably formed can be easily constructed.
According to the invention of claim 10, even when the charging member is used in contact with the toner holding member whose surface of the conductive base material is coated with the coating layer, the toner layer is made to follow the surface waviness. An image forming apparatus including a developing device that can be stably formed can be easily constructed.

(A) is explanatory drawing which shows the outline | summary of embodiment of the image forming apparatus containing the developing device to which this invention is applied, (b) is the waviness characteristic of the surface of the toner holding body used with the developing device shown to (a). FIG. 4C is an explanatory diagram showing a preferable aspect of the surface roughness of the toner holding member shown in FIG. 1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. FIG. 2 is an explanatory diagram showing a main part of a developing device used in Embodiment 1. FIG. 3 is an explanatory diagram illustrating conditions of toner, a developing roll, and a developing electric field of the developing device used in the first embodiment. (A) is explanatory drawing which shows the wave | undulation characteristic of the surface of the image development roll used in Embodiment 1, (b) is explanatory drawing which shows an example of the manufacturing method of the image development roll shown to (a). (A) is explanatory drawing which shows the meaning of the average height Wca of the waviness curve element in the surface of the image development roll used in Embodiment 1, (b) shows the meaning of the average length Wc-Sm of the same waviness curve element. It is explanatory drawing. (A) is the graph which shows the roughness curve and load length rate of the object surface of the image development roll used in Embodiment 1, (b) shows the numerical formula which calculates | requires the amount of oil sumps as the surface roughness of the image development roll. It is explanatory drawing. (A) is explanatory drawing which shows typically the relationship between the roughness curve of a developing roll, and load length rate, (b) is explanatory drawing which shows the numerical formula which calculates | requires load length rate. (A) is explanatory drawing which shows the numerical formula which calculates | requires the adhesive force of the toner with respect to the surface of a developing roll, (b) is an example which decomposed | disassembled into the Coulomb force which is electrostatic adhesive force, and nonelectrostatic adhesive force about the adhesive force of toner. It is explanatory drawing shown. FIG. 3 is an explanatory diagram illustrating an example of a measuring device that measures a toner charge distribution. It is explanatory drawing which shows an example of the measurement result by the measuring apparatus shown in FIG. FIG. 5 is an explanatory diagram showing an action associated with the waviness characteristic of the surface of the developing roll used in the first embodiment. In evaluating the undulation characteristics of the developing roll of the developing device according to Example 1, the undulation characteristic parameters Wca and Wc-Sm on the surface of the developing roll are changed, and the presence or absence of the occurrence of spotted patterns on the developed image in each case It is explanatory drawing which shows the result of having investigated. In evaluating the surface roughness of the developing roll of the developing device according to Example 2 with various parameters, (a) to (d) are parameters relating to the smoothness (oil accumulation amount V0) as parameters of the surface roughness of the developing roll. , Oil sump depth Rvk, average slope RΔa, developed length ratio Rlr) and non-electrostatic adhesive force. In this evaluation, (a) to (d) are parameters relating to the surface roughness of the developing roll, such as indices related to height (arithmetic average roughness Ra, ten-point average roughness RzJIS, amplitude distribution distortion Rsk, amplitude distribution It is a graph which shows the correlation with a sharp edge (Rku) and nonelectrostatic adhesion force. In the same evaluation, (a) to (d) are the parameters of the surface roughness of the developing roll, and parameters relating to lubricity (initial wear height Rpk, initial wear length Mr1, oil sump portion length Mr2) and in the lateral direction. It is a graph which shows the correlation with the parameter | index (interval Sm of unevenness | corrugation) and nonelectrostatic adhesive force which concern. In evaluating the adhesion force of the developing device according to Example 3 to the developing roll, (a) is data indicating the state of development when the voltage applied to the developing roll is changed, and (b) is data of (a). (C) is data indicating the development voltage Vdev at the start of flight, the charge Q of the start toner, the particle size d, and the like. 18 is a graph showing the relationship between the development voltage Vdev and the development amount DMA per unit area based on the data shown in FIG. FIG. 17A is a graph showing the relationship between the development voltage Vdev and the charge amount of the development toner based on the data shown in FIG. 17B, and FIG. 17B is the development voltage Vdev based on the data shown in FIG. FIG. 6 is a graph showing the relationship between the toner particle diameter and the developing toner particle diameter. FIG. 10 is an explanatory diagram illustrating an example of a sheet for calculating an adhesion force in the developing device according to Embodiment 3. It is explanatory drawing which shows typically the process which decomposes | disassembles adhesive force based on the adhesive force calculation sheet | seat of FIG. FIG. 10 is a graph showing the relationship between the toner adhesion force and the fog density on the photoreceptor using the developing device according to Example 4. FIG. 10 is a graph showing the relationship between the Coulomb force and the fog density on the photoreceptor using the developing device according to Example 4. FIG. 10 is a graph showing the relationship between non-electrostatic adhesion force and fog density on a photoreceptor using a developing device according to Example 4. FIG. 10 is a graph showing the relationship between non-electrostatic adhesion force and fog density on a photoconductor under the condition where a toner charging process using a highly charged blade with high chargeability is performed using the developing device according to Example 4; FIG. 10 is an explanatory diagram illustrating characteristics of a developing roll used in a developing device according to Embodiment 5. It is explanatory drawing which shows the relationship between V0 measured with the measuring apparatus and nonelectrostatic adhesion regarding the developing roll shown in FIG. FIG. 27 is a graph showing the relationship between the charge amount of the flying start toner and the Coulomb force with respect to the developing roll shown in FIG. 26. FIG. 10 is an explanatory diagram in which the developing rolls of the developing devices according to Example 6 and Comparative Example 6 are changed, and the relationship between the Coulomb force, the non-electrostatic adhesive force, the adhesive force, and the particle size of the flying start toner is examined. FIG. 30 is a graph showing the relationship between the particle size of the flying start toner and the non-electrostatic adhesion force of the flying start toner based on the data shown in FIG. 29. FIG. 10 is a graph showing the state of change in fog density on the photoreceptor over time with respect to the developing device according to Example 7 and the developing device according to Comparative Example 7.

Outline of Embodiment FIG. 1A shows an outline of an embodiment of an image forming apparatus including a developing device to which the present invention is applied.
In FIG. 1, the image forming apparatus includes an image carrier 5 that holds a latent image, and a developing device 6 that develops the latent image held on the image carrier 5 with nonmagnetic toner.
In this example, the image carrier 5 is not limited to a photoconductor and a dielectric as long as it holds a latent image. Pixel electrodes corresponding to the pixel density are arranged in a lattice pattern to form a latent image on each pixel electrode. A latent image voltage may be applied. The image carrier 5 and the developing device 6 may be provided individually. For example, the image carrier 5 may be attached to a process cartridge that can be attached to and detached from a receiving unit provided in advance in the image forming apparatus housing. The developing device 6 may be incorporated in advance.
In this example, as shown in FIG. 1A, the developing device 6 is disposed in a non-contact manner so as to face the image carrier 5 on which the latent image is held, and holds the non-magnetic toner TN. At least a predetermined potential difference between the toner holder 1 that circulates and rotates, the charging member 2 that charges the toner TN held on the toner holder 1, and the image holder 5 and the toner holder 1. By forming a developing electric field E containing a direct current component, the toner TN held by the toner holding body 1 and charged by the charging member 2 is caused to fly to the latent image on the image holding body 5, thereby And developing electric field forming means 3 for developing the toner TN on the image.
In particular, as shown in FIG. 1B, the toner holder 1 used in this embodiment has a conductive substrate 1a and a coating layer 1b that covers the surface of the conductive substrate 1a. The surface waviness of the coating layer 1b is Wca ≦ 0.5 (μm), Wc−Sm ≧ 2.5 (where Wca is the average height of the waviness curve element and Wc−Sm is the average length of the waviness curve element. mm) satisfying the relationship (mm).

In such technical means, the toner holder 1 may be appropriately selected as long as it holds the non-magnetic toner TN, and the form thereof is typically a roll shape, but is not limited thereto. .
As long as the charging member 2 is a functional member that charges the toner TN held on the toner holder 1, a member that contacts the toner and is frictionally charged may be selected as appropriate.
Further, the developing electric field forming means 3 may be any one that forms a developing electric field E containing at least a DC component. From the viewpoint of improving developability, the developing electric field in which an AC component is superimposed on the DC component. The aspect which forms is preferable.
Furthermore, as the conductive substrate 1a, a metal substrate is typically used, but a high hardness resin substrate or ceramic substrate containing conductive particles may be used.
And although the material as the coating layer 1b may be selected appropriately, the coating layer 1b made of resin is preferable in consideration of followability with the surface of the conductive member.

Further, among the waviness characteristics of the toner holder 1, the average height Wca of the waviness curve element means the average of the heights of the waviness curve elements at the reference length, and the “waviness curve element” is one. One mountain + next to the valley. If this is large, the height of the undulation curve element will be high and the amplitude of the undulation will be large, so in this embodiment, the amplitude of the undulation will be reduced by setting it below a predetermined boundary value. It is intended to suppress the metal plate-like charging member so as to follow the waviness curve element.
Furthermore, the average length Wc-Sm of the waviness curve element means the average length of the waviness curve element in the reference length. If this is small, the length of the undulation curve element will be small and the one-cycle change length of the undulation will be short. Therefore, in this embodiment, by setting this to a predetermined boundary value or more, one undulation cycle It is intended to make the change length moderate so that the metal plate-like charging member can follow the waviness curve element.
In order to give a predetermined waviness curve to the surface of the toner holding member 1, a fine grinding tool (on the surface of the conductive substrate 1a or the conductive substrate 1a coated with the coating layer 1b) For example, the grinding process may be appropriately performed with a grindstone.

Next, a typical aspect or a preferable aspect of the developing device 6 used in the present embodiment will be described.
First, as a typical embodiment of the toner holding member 1, there is an embodiment in which the conductive substrate 1a is a metal cylindrical substrate.
Moreover, as a preferable aspect of the electroconductive base material 1a, the surface waviness of an electroconductive base material has what has Wca and Wc-Sm comparable as the said coating layer. In this embodiment, a desired grinding process may be performed on the surface of the conductive substrate 1a, and the coating layer 1b may be provided so as to follow this.
Furthermore, as a typical embodiment of the coating layer 1b, one formed by a spray coating method can be cited. This spray coating method is an effective method for forming a uniform coating layer 1b on the surface of the conductive substrate 1a.

Further, as a preferable aspect of the surface roughness of the toner holder 1, as shown in FIG. 1C, the average particle diameter of the nonmagnetic toner TN is d (μm), and the surface roughness of the toner holder 1 is Assuming that the amount of oil sump corresponding to the amount of oil accumulated in the sump depth Rvk per 1 cm ² of surface area is V0, those satisfying the relationship of V0 / d <6.8 × 10 ⁻⁴ can be mentioned.
In this aspect, as an arrangement that easily realizes the idea of ensuring a large non-electrostatic adhesion force for a poorly charged toner, the surface roughness of the toner holding member 1 includes an index related to smoothness and a non-electrostatic adhesion force. In particular, the oil sump amount V0 is selected from the indices related to smoothness.

Here, the correlation between the non-electrostatic adhesion force and the surface roughness of the toner holding member 1 was examined. As a surface roughness parameter having a high correlation with the non-electrostatic adhesion force, an index relating to smoothness (average slope RΔa, Development length ratio Rlr, oil sump depth Rvk, oil sump amount V0) is found, and in particular, since the correlation with the oil sump amount V0 is high, the present embodiment focuses on the sump amount V0. The desired smoothness range of the toner holder 1 was defined. Of the surface roughness of the toner holder 1, it was confirmed that the non-electrostatic adhesive force has a low correlation with respect to the index related to the height direction, the index related to the lubricity, and the index related to the lateral direction. . The relationship between the non-electrostatic adhesion force and the surface roughness of the toner holding member 1 will be described in detail in the description column of Example 2.
Further, the correlation between the non-electrostatic adhesion force and the surface roughness of the toner holding member 1 is the result of measurement with SURFCOM (Surfcom) 1400D manufactured by Tokyo Seimitsu Co., Ltd. as described in Example 2 described later. Judgment based on.
Further, it is considered that the oil pool amount V0 of the toner holder 1 depends on the particle diameter d of the toner TN. That is, even when the oil sum V0 is the same, the toner TN having a large particle size and the toner TN having a small particle size have different relative sizes, but even if the oil sum V0 has a different size, If the average particle diameter d of the toner is the same ratio relative to the oil sum V0, the relative relationship between the surface of the toner holder 1 and the toner TN is considered to be the same, and a relative parameter of V0 / d is assumed. It was.
Furthermore, the coefficient of “6.8 × 10 ⁻⁴ ” indicates that when the boundary value of the oil sum V0 is 0.004, the average particle diameter d of the flying toner TN is 5.85 μm. A boundary value of 0.004 ÷ 5.85 = 6.837... × 10 ⁻⁴ was obtained, and from this, a coefficient of “6.8 × 10 ⁻⁴ ” was selected. This will be described in detail in the description section of the embodiment described later.

Further, supplementing the non-electrostatic adhesion described above, as shown in FIG. 1C, the toner TN held on the toner holder 1 is applied to the image holder 5 by a developing electric field having only a DC component. When the developing electric field E by the developing electric field forming means 3 is applied so as to start flying, the non-electrostatic adhesion force of the toner TN to the toner holding body 1 with respect to the toner TN that starts flying, The temperature is kept at 2 nN or higher in a low temperature and low humidity environment with a temperature of 10 ° C. and a relative humidity of 15% RH.
In general, the toner TN is frictionally charged by the charging member 2, but when the toner TN is repeatedly used in association with friction with the charging member 2, the toner TN gradually changes with time.
At this time, for example, when the toner TN has an external additive added of 30 nm or more, when the toner TN changes with time, the external additive is partially embedded in the toner surface and remains. In addition to the deterioration of the fluidity, the area of contact with the charging member 2 is reduced and the chargeability tends to deteriorate.
In this state, the toner TN becomes poorly charged, and it becomes easy to generate low-charged toner and reverse polarity toner. If these poorly charged toners exist in the developing area m, which is the working area of the developing electric field E of the toner holder 1. There is a concern that a so-called fogging phenomenon may occur in which poorly charged toner flies to a non-image portion (for example, a background portion) of the image carrier 5 and adheres to the non-image portion as dirt.
In order to prevent such a poorly charged toner from flying unnecessarily to the image carrier 5 side, in this embodiment, the non-electrostatic adhesion force of the toner TN to the toner carrier 1 is 2 nN or more under predetermined environmental conditions. It is something to keep. Here, the predetermined environmental condition is determined because the non-electrostatic adhesion force of the toner TN depends on the environmental condition, so that the environmental condition for measurement is specified.

In the developing device having the toner holding member 1 having such surface roughness characteristics, as a preferred embodiment of the developing electric field forming unit 3, an alternating current component whose potential changes periodically is superimposed on the direct current component as the developing electric field E. Those that form an electric field.
When a development electric field E in which an alternating current component is superimposed on a direct current component is used, the developability is further improved as compared with the development electric field having only a direct current component, but the behavior of toner in the development zone m is active. As a result, the fog amount of poorly charged toner tends to increase with respect to the image carrier.
However, in this embodiment, the surface smoothness of the toner holder 1 is maintained in a desired state by adjusting the oil sum V0, thereby increasing the non-latent image adhesion force of the toner to the toner holder 1 and flying charge. In addition to suppressing unnecessary generation of good toner, a state where it is difficult for the poorly charged toner to fly toward the image holding member 1 with respect to the flying or knocking out of the charged good toner.

In addition, as a typical aspect of the charging member 2, an aspect in which the charging member 2 is a metal plate-like member that contacts the surface of the toner holding member 1 can be given. This example is preferable in that the charging member 2 having an inexpensive configuration can be obtained by using a metal plate-like member.
Further, from the viewpoint of maintaining good image quality in the developing device, the toner TN may have an average particle size of 6.5 μm or less.
In the toner TN having an average particle size of more than 6.5 μm, the electrostatic adhesion force is determined by looking at the ratio of the electrostatic adhesion force (Coulomb force) contributing to the adhesion force and the non-electrostatic adhesion force such as van der Waals force. On the other hand, when the average particle diameter is a small diameter of 6.5 μm or less, the ratio of the electrostatic adhesive force is lowered, so that the influence of the non-electrostatic adhesive force is easily manifested.

Further, as an aspect that is more effective as the developing device 6 according to the present embodiment, there is an aspect that presupposes the use of a low-temperature fixing toner TN that can be fixed at a low fixing temperature (for example, about 120 ° C. to 140 ° C.). .
This type of low-temperature fixing toner TN can reduce mechanical stress, and is therefore suitable for extending the life of the toner.
The low-temperature fixing toner TN may be appropriately selected by using a low molecular weight resin as a toner material, lowering the Tg (glass transition temperature) of the resin, or using a crystalline resin.
The low-temperature fixing toner TN may be specified by indicating that it can be used at the low fixing temperature described above. Of course, the toner related to the low-temperature fixing property can be directly shown as a usable fixing temperature. You may make it show based on the numerical value of this characteristic parameter paying attention to the characteristic parameter of TN. Examples of the characteristic parameter of the toner TN include a loss elastic modulus G ″ indicating a viscous component of the toner which is a viscoelastic body.
Further, the low-temperature fixing toner TN, for example, containing an external additive of 30 nm or more has a viscosity characteristic that works in the direction of promoting the partial burying of the external additive on the toner surface with use over time. ing. For this reason, if the external additive is partially embedded in the toner surface, it adversely affects the fluidity and chargeability of the toner, and the charge distribution of the toner is broadened (the charge distribution width tends to widen). Reverse polarity toner is likely to be generated.
However, in this embodiment, since the toner holder 1 has desired swell characteristics (Wca, Wc-Sm), it is assumed that a metal plate-shaped charging member is brought into contact with the surface of the toner holder 1. However, the contact pressure with respect to the toner in the contact area can be made substantially uniform. For this reason, it is preferable in that the charging property to the toner is stable and the occurrence of poorly charged toner is reduced.
Further, in the aspect in which the desired surface roughness (V0) of the toner holding member 1 is selected, fogging tends to occur in that the poorly charged toner is transferred to a non-image area (for example, a background portion) of the image holding member 5. However, in this embodiment, the non-electrostatic adhesion force of the low-temperature fixing toner TN to the toner holding body 1 is maintained at a predetermined value or more, thereby causing the image holding body to be caused by being attracted or knocked out by the flying charged good toner. 5 acts to suppress the flying of the poorly charged toner toward 5.

A typical embodiment of this type of low-temperature fixing toner TN includes a toner containing a polyester resin as a main component as a binder resin.
In this embodiment, the glass transition temperature Tg of the polyester resin is preferably 40 ° C. or higher and 80 ° C. or lower, and low temperature fixability can be obtained when it is 80 ° C. or lower. Storability can be obtained. Further, the molecular weight (weight average molecular weight Mw) of the polyester resin is preferably 10,000 or more and 100,000 or less from the viewpoint of resin productivity, fine dispersion during toner production, and compatibility during melting.
Another typical embodiment of the low-temperature fixing toner TN includes one containing a crystalline polyester resin as a binder resin.
In this embodiment, by including the crystalline polyester resin, the low-temperature fixability is further improved, and the amount of ammonia released from the toner in the fixing step can be reduced. The melting point of the crystalline polyester is preferably 50 ° C. or higher and 100 ° C. or lower. If the melting point is 50 ° C. or higher, the storage stability of the toner and the storage stability of the toner image after fixing are good, and if it is 100 ° C. or lower, the low temperature fixability is easily obtained.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment 1
-Overall configuration of image forming apparatus-
FIG. 2 is an explanatory diagram showing the overall configuration of the image forming apparatus according to the first embodiment.
In FIG. 1, an image forming apparatus 20 includes a drum-shaped photosensitive member 21 as an image holding member, a charging device 22 that charges the photosensitive member 21, and a photosensitive member 21 charged by the charging device 22. An exposure device 23 that writes an image with light, a developing device 24 that visualizes the electrostatic latent image written on the photosensitive member 21 with a developer (toner), and a visible image that is developed by the developing device 24 A transfer device 25 that transfers the converted toner image to a recording material 28 as a transfer medium, and a cleaning device 26 that cleans residual toner remaining on the photoreceptor 21 after being transferred by the transfer device 25. ing.
In this example, the transferred image transferred to the recording material 28 is discharged after being fixed by a fixing device 30 (not shown). In this example, the recording material 28 is exemplified as the transfer medium, but is not limited thereto, and includes an intermediate transfer member that temporarily holds the toner image before being transferred to the recording material 28.

Here, as shown in FIG. 3, the photosensitive member 21 is obtained by forming a photosensitive layer 212 on, for example, a drum-shaped metal frame 211. In addition, the charging device 22 has a charging container, for example, and a discharge wire is provided as a charging member in the charging container. However, the charging device 22 is not limited to this, for example, a roll shape The charging member may be selected as appropriate.
Further, as the exposure device 23, a laser scanning device, an LED array, or the like is used.
Further, as the developing device 24, a device adopting a one-component developing method using a non-magnetic toner is used. Details of the developing device 24 will be described later.
Furthermore, the transfer device 25 may be any device that acts on a transfer electric field for electrostatically transferring the toner image on the photosensitive member 21 to the recording material 28 side. For example, a roll-like transfer member to which a transfer bias is applied is used. However, the present invention is not limited to this, and a transfer corotron using a discharge wire may be appropriately selected.
Further, the cleaning device 26 has a cleaning container that opens on the photosensitive member 21 side and accommodates residual toner. A plate-like shape such as a blade or a scraper is disposed on the downstream edge of the opening of the cleaning container in the rotational direction of the photosensitive member 21. A cleaning member 261 is disposed, and a brush-shaped or roll-shaped rotational cleaning member 262 is disposed on the upstream side of the plate-shaped cleaning member 261 in the rotation direction of the photosensitive member 21. It is not limited and can be selected as appropriate.
Note that all or part of the photosensitive member 21, the charging device 22, the developing device 24, and the cleaning device 26 are assembled in advance as a process cartridge 29 so that the photosensitive member 21, the charging device 22, the developing device 24, and the cleaning device 26 can be attached to and detached from a receiving portion provided in advance in the image forming apparatus housing. You may make it wear.

-Development device-
In this example, as shown in FIGS. 2 to 4, the developing device 24 includes a developing container 40 that contains nonmagnetic toner TN and opens to face the photosensitive member 21. A developing roll 41 is disposed on the facing side, and a supply roll 42 capable of supplying the nonmagnetic toner TN in the developing container 40 is disposed on the back surface of the developing roll 41. In this, an agitator 43 as an agitating and conveying member for conveying the nonmagnetic toner TN to the supply roll 42 side while being agitated is disposed.
In this example, both the developing roll 41 and the supply roll 42 rotate in the clockwise direction, and the developing roll 41 holds the nonmagnetic toner TN supplied from the supply roll 42 and holds the photoconductor 21. Is conveyed to a developing area m opposite to the developing area m and used for development in the developing area m.
Further, a plate-like charging blade 45 is provided on the downstream side of the developing roll 41 with respect to the toner supply portion by the supply roll 42 in the toner transport direction. The charging blade 45 preferably has a Beakers hardness of 90 or more, and is composed of, for example, a metal plate such as phosphor bronze. One end of the charging blade 45 is fixed to the opening edge of the developing container 40 and is opposed to the rotation direction of the developing roll 41. It extends so as to protrude, and is pressed against the surface of the developing roll 41 with a predetermined pressing force P. For this reason, the toner TN held on the developing roll 41 is frictionally charged by passing through the pressure contact portion between the charging blade 45 and the developing roll 41, and is regulated to a predetermined transport amount. It has become.
The fixing portion of the charging blade 45 has a bracket 46 attached to the opening edge of the developing container 40, and a spacer 47 is interposed between the bracket 46 and the base end of the charging blade 45 is sandwiched and held by the holder 48. Is.

One end of a sealing member 49 made of an elastic member is fixed to the lower edge of the opening of the developing container 40, and the free end of the sealing member 46 is upstream of the toner supply portion of the developing roll 41 by the supply roll 42 in the toner transport direction. The gap between the developing roll 41 and the developing container 40 is closed by being elastically contacted to the side.
Further, in this example, a developing power source 51 for forming a developing electric field is provided between the developing roll 41 and the photoreceptor 21, and the non-magnetic toner TN is supplied to the developing roll 41 in the supply roll 42. A supply power source 52 is provided for forming a supply electric field.
In this example, the developing power supply 51 applies a developing voltage Vdev in which the AC component Vac is superimposed on the DC component Vdc to the developing roll 41, and the supply power supply 52 is a power supply for the developing power supply 51. A supply voltage Vs that has a DC component having a predetermined potential difference with respect to the DC component Vdc and in which an AC component having the same period as the AC component Vac of the developing power supply 51 is superimposed on the DC component is applied. Yes.

-Toner-
In the present embodiment, the non-magnetic toner TN is formed as a toner having a small average particle diameter d of 6.5 μm or less and a low fixing temperature (for example, about 120 ° C. to 140 ° C.) that can be fixed at low temperature. Specifically, it contains a binder resin, a colorant, a release agent, and other additives.

-Development roll-
In the present embodiment, as shown in FIG. 5A, the developing roll 41 includes a roll body 411 made of metal such as aluminum, and a urethane or nylon system on which the surface of the roll body 411 is coated. And a coating layer 412 made of a resin such as styrene.
Here, as the coating layer 412, the filler component contained in the resin component is preferably 20 parts by weight or less with respect to 100 parts by weight of the resin component in order to obtain the swell characteristics described later.
−Waviness characteristics−
The surface of the developing roll 41 in this example has the following waviness characteristics.
That is, when the average height of the undulation curve element is Wca and the average length of the undulation curve element is Wc-Sm, the relationship shown in (I) (II) is satisfied.
Wca ≦ 0.5 (μm) (I)
Wc-Sm ≧ 2.5 (mm) (II)
Here, as shown in FIG. 6A, Wca is the height Zti (i) of m undulation curve elements (a valley adjacent to the undulation peak corresponding to one period) in the reference length L. = 1 to m), and the magnitude means the magnitude of the amplitude in the height direction of the swell, and is set to 0.5 μm or less obtained experimentally.
Further, as shown in FIG. 6B, Wc-Sm is the length Xsi (m) of m undulation curve elements (the valley adjacent to the undulation peak corresponding to one period) in the reference length L. i = 1 to m) is averaged, and the size means the size of one cycle length in the swell length direction, which is set to 2.5 μm or more obtained experimentally.
This will be described in detail in Example 1 to be described later. As the waviness characteristic of the surface of the developing roll 41, one that maintains good charging performance by the charging blade 45 is selected.
The swell characteristics on the surface of the developing roll 41 are measured by, for example, SURFCOM (Surfcom) 1400D manufactured by Tokyo Seimitsu Co., Ltd.

<Development roll production method>
Here, the manufacturing method of the developing roll 41 of this example will be described. First, as shown in FIG. 5B, the metal roll body 411 is ground. As this grinding process, surface grinding may be performed a plurality of times (for example, twice) using a grindstone whose grinding roughness becomes finer in order to obtain desired waviness characteristics.
At this time, the grinding process is preferably surface grinding by centerless processing. This centerless machining is equipped with a grinding wheel for grinding the object to be ground, an adjusting grindstone for feeding the grinding object to the grindstone, and a support blade for placing the grinding object, and the object to be ground is rotated by each rotation of the grindstone and the adjusting grindstone. It is a grinding method that is suitable for grinding with high precision dimensional tolerances, because it grinds the surface while rotating, and does not take the center axis and presses it.
In this example, when grinding the roll body 411, Wca and Wc-Sm may satisfy (I) and (II) as the waviness characteristics of the roll body 411.
Thereafter, as shown in FIG. 5B, the surface of the roll body 411 is spray-coated with the sprayer 415 while rotating the roll body 411 using the resin liquid for forming the coating layer 412. You can do it.
In this spray coating method, the coating layer 412 is uniformly formed on the surface of the roll body 411 by the resin liquid, so that the undulation characteristic of the surface of the developing roll 41 coated with the coating layer 412 is the undulation characteristic of the surface of the roll body 411. It is obtained as a substantially corresponding one.

−Surface roughness characteristics−
Further, the surface roughness of the developing roll 41 in this example is selected as follows.
That is, the average particle diameter of the toner TN is d (μm) and the surface roughness of the developing roll 41 is equivalent to the amount of oil (mm ³ ) accumulated in the oil sump depth Rvk (μm) per 1 cm ² surface area. Assuming that the amount of oil sump to be V0 (μm), it is adjusted to satisfy the relationship of V0 / d <6.8 × 10 ⁻⁴ .
<Oil sump amount V0>
Here, the oil sump amount V0 is obtained by the mathematical formula shown in FIG.
In this equation, the oil sum V0 is calculated as a function of the oil sump depth Rvk and the oil sump portion length Mr2.

Now, as shown in FIG. 8A, the roughness curve of the target surface in FIG. 7A is extracted by the reference length L, and the roughness curve of this extracted portion is cut at a cutting level C parallel to the peak line. The ratio of the sum of the cutting lengths (load length ηp) obtained when cutting with the reference length L to the reference length L (see FIG. 8B) is defined as the load length ratio tp. .
This load length ratio tp represents information in both the height direction and the lateral direction, and tp **% and the cutting level C (μm) are written together.
Then, as shown in FIG. 7A, the straight line having the smallest slope (minimum slope) among the straight lines passing through the two points where the difference in tp value is 40% at the point on the curve of the load length ratio tp. (Straight line). The intersections of this straight line with 0% tp and 100% tp are point a and point b, respectively, and the intersection between the cutting level C passing through point b and the curve of the load length rate tp is point e, and the load length rate tp Let f be the intersection of this curve and 100% tp. At this time, a point g on 100% tp is obtained such that the area surrounded by the line segment be, the line segment bf, and the curve ef is equal to the area of the triangle beg. In this state, the distance between the points b and g is Rvk, and the tp value of the point e is Mr2.
In addition, an intersection of the cutting level C passing through the point a and the curve of the load length rate tp is c, and an intersection of the curve of the load length rate tp and 0% tp is i. At this time, a point j on 0% tp is obtained such that the area surrounded by the line segment ac, the line segment ai, and the curve ci is equal to the area of the triangle acj. Furthermore, let k be the intersection of the cutting level C passing through point b and 0% tp. In this state, the distance between the points a and j is defined as the initial wear height Rpk, the tp value at the point c is defined as the initial friction length Mr1, and the distance between the points j and k is defined as the effective load roughness Rk.

<Relationship between oil sump and toner particle size>
Further, the oil sum V0 is an index related to the smoothness of the surface roughness, and in relation to the toner, the developing roller 41 having the same oil sum V0 surface roughness also has a toner particle size d depending on the toner particle size d. It is presumed that the degree of influence between is different. For this reason, in this example, it is assumed that the oil pool amount V0 and the toner particle diameter d have the same effect if the relative ratio 'V0 / d' is equal, and the surface roughness parameter of the developing roll 41 'V0 / d' is adopted.
<Selection of boundary value>
The method of selecting the boundary value of the surface roughness 'V0 / d' of the developing roll 41 is to determine the boundary value V0th of the oil pool amount V0 at which the non-electrostatic adhesion force with respect to the toner of the particle size selected in advance is 2 nN. The toner particles that start to fly when the developing roll 41 having a surface roughness whose oil sum V0 is a boundary value are used and a developing electric field selected in advance is applied between the developing roll 41 and the photosensitive member 21. The diameter dth is determined, and V0th / dth is calculated from these.
Details of this will be described in an embodiment described later.

<Adjustment method of oil sump amount V0>
As a method for adjusting the amount of oil sum V0 as the surface roughness of the developing roll 41, for example, a grinding tool having a predetermined surface roughness is selected as a polishing tool such as a grindstone, and the roll body is subjected to predetermined polishing conditions. The surface of 411 is polished and finished, and then the resin coating layer 412 is coated using, for example, a spray coating method, a dip method, or the like.
In this example, the surface roughness of the developing roll 41 corresponds to the surface roughness of the roll body 411 because the coating layer 412 is formed into a uniform thin film following the roll body 411 by spray coating. Finished. However, if the surface roughness of the developing roll 41 becomes rougher than the surface roughness of the roll body 411, the final surface finishing process is performed on the developing roll 41 to which the coating layer 412 is attached. do it.

<Calculation method of non-electrostatic adhesive force>
The toner adhesion force F with respect to the developing roll 41 is obtained by the mathematical formula shown in FIG.
In this equation, “A (Q / d) ² ” in the first term is a term corresponding to a Coulomb force (electrostatic adhesion force) depending on the charged charge of the toner, and “Bd” in the second term is van der. Indicates non-electrostatic adhesion force such as Waals force.
Here, “Q” is the charged charge of the toner, “d” is the particle size of the toner, and “A” and “B” are coefficients.
In order to obtain this kind of toner adhesion force F, a particle charge amount distribution measuring device 60 (see FIG. 10) capable of measuring toner particle charge amount distribution information is used. Based on the measurement result of the particle charge amount distribution measuring device 60 when the development voltage consisting only of Vdc is changed, the toner charge at the toner flight start point of the development curve (see FIG. 11) based on the development voltage of the DC component Vdc. The toner adhesion force F is obtained from Q and the developing electric field E (Vdev / DRS (abbreviation of Drum Roll Space: meaning of a gap between the drum-shaped photosensitive member and the developing roll)). In FIG. 11, the horizontal axis of the development curve represents the development voltage Vdev, and the vertical axis represents the development amount DMA (abbreviated for developed mass per area) per unit area of the particle charge amount distribution measuring apparatus 60.
After this, for example, the same toner, the same developing roll, etc. are used, and only the high charging blade (for example, a new one) and the low charging blade (for example, one used over time) are changed as charging blades having different charging characteristics. The toner adhesion force F in the case where all the conditions are the same and only the charge amount of the toner is different is obtained, the simultaneous equations relating to the equation shown in FIG. 9A are solved, and the coefficient “A” of the equation shown in FIG. B ′ is obtained, and the Coulomb force and the non-electrostatic adhesion force are determined (see FIG. 9B).
A specific method for calculating the non-electrostatic adhesive force will be described in detail in Examples.

<Particle charge distribution measurement device>
Examples of the particle charge amount distribution measuring apparatus 60 used in the present embodiment include E-spart (Espert Analyzer) manufactured by Hosokawa Micron Corporation.
As shown in FIG. 10, the basic structure of the particle charge amount distribution measuring device 60 is divided into two parts by giving a constant frequency deviation to the laser beam generating device 61 and the laser beam generated from the laser beam generating device 61. A beam splitter 62 for splitting, a measurement chamber 63 for introducing the laser beam split by the beam splitter 62 and irradiating the particle 80 to be measured at the measurement point M, and the particle 80 to be measured in the measurement chamber 63 A condenser 70 such as a condenser lens for condensing the laser beam scattered and emitted from the measurement chamber 63, a detector 71 for detecting the collected beam, and a detection output from the detector 71 And a calculation device 72 for calculating the charge amount information of the particles 80 to be measured.
Here, the measurement chamber 63 has a box-shaped container body 64, a measured particle introduction port 68 is provided on the upper wall portion of the container body 64, and a measured particle discharge port 69 is formed on the lower wall portion of the container body 64. In addition, a sound wave vibration generating mechanism 65 is disposed on the opposite side walls of the container body 64, and further, a measurement is performed on the opposite side walls of the container body 64 on which the sound wave vibration generating mechanism 65 is disposed. Electrodes 66 capable of forming a predetermined electric field are respectively disposed in the chamber 63, and a power source 67 is connected to one electrode 66 and the other electrode 66 is grounded.
Next, the operation of the particle charge amount distribution measuring apparatus 60 will be described.
Now, when the measured particle 80 conveyed to the nitrogen gas stream from the measured particle introduction port 68 of the measurement chamber 63 by using an appropriate supply means is charged, the charged particle is a sound wave from the sonic vibration generating mechanism 65. The measurement point M is irradiated with the laser beam divided into two while dropping according to the magnitude of the charge amount and the vibration by the vibration due to the above and the electric field from the electrode 66 to which a predetermined voltage is applied. In this case, the particle oscillates with a delay from the reference sound wave according to its size, and at the same time falls with a certain bias according to the charge amount. Then, the laser beam is scattered reflecting such information from the particles, and this scattered beam is detected by the detector 71 via the condenser 70 and then input to the arithmetic unit 72 to obtain a predetermined value. Calculated as charge amount information.

-Operation of the developing device-
In the developing device 24 according to the present embodiment, the toner TN in the developing container 40 is agitated and conveyed toward the supply roll 42 by the agitator 43 and supplied to the developing roll 41 by the supply roll 42 as shown in FIG. The
Thereafter, the toner TN held on the developing roll 41 passes through the charging blade 45 and is charged, and then reaches the developing area m between the developing roll 41 and the photoreceptor 21.
In this state, since the developing electric field E is formed in the developing area m, most of the toner TN held on the developing roll 41 flies toward the electrostatic latent image formed on the photosensitive member 21, By attaching to the electrostatic latent image, it is used for developing the electrostatic latent image.
When such a developing device operates, the toner behaves as follows.

-Charging by charging blade-
First, how the waviness characteristic on the surface of the developing roll 41 of this example affects the charging operation by the charging blade will be described.
The waviness characteristics on the surface of the developing roll 41 of this example are such that Wca is as small as 0.5 μm or less and Wc-Sm is as large as 2.5 mm or more.
Therefore, in this example, as shown in the upper right column of FIG. 12, the metal charging blade 45 is deformed following the undulation U on the surface of the developing roll 41, and the charging blade 45 is held on the surface of the developing roll 41. Therefore, the toner TN on the developing roll 41 is substantially uniformly charged.
On the other hand, if it supplements about the aspect different from this example, for example in the comparative form 1 (Wca <= 0.5micrometer, Wc-Sm <2.5mm) where Wca is small and Wc-Sm is also small, As shown in the upper left column of FIG. 12, the charging blade 45 is not in contact with the toner TN held near the center of the concave portion of the narrow undulation U1 because Wc-Sm is small. There is a concern that the charge distribution of the toner TN on the developing roll 41 may become insufficient, resulting in unevenness in the charge distribution.
In Comparative Example 2 (Wca> 0.5 μm, Wc-Sm <2.5 mm) where Wca is large and Wc-Sm is small, as shown in the lower left column of FIG. 12, Wc-Sm is small, and , The charging blade 45 is not in contact with the toner TN held in the concave portion of the narrow undulation U2, and the charging property of the toner TN in this portion becomes insufficient, and the toner on the developing roll 41 There is a concern that the TN charge distribution may be uneven.
Furthermore, in Comparative Example 3 (Wca> 0.5 μm, Wc-Sm ≧ 2.5 mm) where Wca is large and Wc-Sm is large, as shown in the lower right column of FIG. 12, Wc-Sm is large, and Because of the large Wca, the charging blade 45 is not in contact with the toner TN held in the deep recess of the wide undulation U3, and the toner TN is insufficiently charged in this portion, and the toner on the developing roll 41 There is a concern that the TN charge distribution may be uneven.
For this reason, in the present embodiment, the chargeability of the toner by the charging blade 45 is substantially uniform, and there is no development failure (occurrence of spotted pattern) due to uneven charging of the toner.

Example 1
The embodiment of the developing device according to the first embodiment was taken as Example 1, and the swell characteristics on the surface of the developing roll used in Example 1 were evaluated.
In this example, the roll body of the developing roll was made of an aluminum cylindrical tube, and the surface was ground twice by centerless processing to obtain desired swell characteristics. At this time, GC100 was used as the final finishing grindstone.
And on the surface of this roll main body, urethane-based paint: Takelac E553 (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd., nonvolatile content 50%) 100 parts by weight, and silica as a filler: AEROSIL 200 (trade name, After adding 15 parts by weight of Nippon Aerosil Co., Ltd. and 10 parts by weight of carbon black: Asahi Thermal (trade name, manufactured by Asahi Carbon Co., Ltd.) as a conductivity-imparting agent, stirring and dispersing for several hours in a pot mill, Polyisocyanate-based crosslinking agent: Takelac D140N (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd.) 20 parts by weight is added, spray coated, and then heated and cured at 150 ° C. for 30 minutes to form a coating layer on the surface of the roll body did.
At this time, developing rolls having different waviness characteristics on the surface of the roll main body were produced by changing the surface grinding conditions of the roll main body, and the developing characteristics were evaluated by a developing device incorporating each developing roll.
Here, as an evaluation of the development characteristics, when halftone images are created under the same development conditions for each development device model using development rolls having different waviness characteristics, a spot pattern as development unevenness is generated. It was examined whether it occurred.
The results are shown in FIG.
According to the figure, when the waviness characteristic on the surface of the developing roll satisfies Wca ≦ 0.5 (μm) and Wc−Sm ≧ 2.5 (mm), a spotted pattern as a development failure is seen. Although there was no waviness characteristic other than that, a mottled pattern as defective development was observed.

Example 2
The embodiment embodying the developing device according to the first embodiment is referred to as Example 2, and the reason why attention is paid to the amount of oil pool as the surface roughness of the developing roll used in Example 2 will be described.
First, focusing on each index relating to the surface roughness of the developing roll as a manifestation factor of the non-electrostatic adhesion among the toner adhesion to the developing roll, SURFCOM 1400D manufactured by Tokyo Seimitsu Co., Ltd. is used as a surface roughness measuring device. In addition, each index of the surface roughness of the target surface of a plurality of development roll models was measured, and non-electrostatic adhesion force was calculated among the toner adhesion forces to each development roll model.
Here, the following were selected as each index regarding the surface roughness of each developing roll model. These indices are based on the standard of JIS B0601: '01.
(1) Oil sump amount V0
(2) Oil sump depth Rvk
(3) Average slope RΔa
(4) Expanded length ratio Rlr
(5) Arithmetic mean roughness Ra
(6) Ten-point average roughness RzJIS
(7) Distortion of amplitude distribution Rsk
(8) Amplitude distribution point Rku
(9) Initial wear height Rpk
(10) Initial wear length Mr1
(11) Oil sump length Mr2
(12) Concavity and convexity spacing Sm

The results are shown in FIGS.
FIGS. 14A to 14D show the relationship between the index <(1) oil sump amount V0 to (4) development length ratio Rlr> relating to smoothness in the surface roughness and the non-electrostatic adhesion force of the toner. FIGS. 15A to 15D are graphs showing an index related to height among surface roughnesses <(5) arithmetic average roughness Ra to (8) sharpness Rku of amplitude distribution> and non-electrostatic attachment of toner. FIG. 16A to FIG. 16D are graphs showing the relationship with the adhesion force, and the indices relating to the lubricity among the surface roughness <(9) initial wear height Rpk to (11) oil sump length Mr2> and lateral It is a graph which shows the relationship between the parameter | index <(12) uneven | corrugated space | interval Sm> regarding a direction, and the nonelectrostatic adhesion force of a toner.
According to the result of FIG. 14, it is understood that the non-electrostatic adhesion force has a high correlation with the index related to smoothness in the surface roughness, and it is understood that the index having the highest correlation is the oil sump amount V0. The In addition, about the level of correlation, the approximate line by the least square method was calculated | required with respect to the plot point of each graph, and the magnitude of the variation amount of this approximate line and each plot was evaluated.
On the other hand, according to the results of FIGS. 15 and 16, the non-electrostatic adhesion force may not be correlated with an index related to height, an index related to lubricity, and an index related to the lateral direction. Understood.
Incidentally, when the correlation between the oil sum V0 and the ten-point average roughness RzJIS was examined, it was confirmed that no correlation was found between them. In addition, when the correlation between the oil sum V0 and the other indexes among the index related to the height, the index related to the lubricity, and the index related to the unevenness was examined in the same manner, no correlation was found at all.
Based on such results, the present application has come to focus on the oil pool amount V0 in the surface roughness of the developing roll as a cause of the development of non-electrostatic adhesion in the toner adhesion.

Example 3
An embodiment of the developing device according to the first embodiment is referred to as Example 3, and an example of an evaluation method related to toner adhesion to the developing roll used in Example 3 is shown.
-Measurement with particle charge distribution measurement device-
First, an E-spart manufactured by Hosokawa Micron Co., Ltd. is used as a particle charge amount distribution measuring device, and as shown in FIG. 17A, the surface potential of the counter electrode (photoreceptor) is charged to −202 V and applied to the developing roll. By applying the voltage while changing the voltage (applied voltage of only the direct current component Vdc in this example), a developing electric field is formed between the developing roll and the photosensitive member by a developing potential difference (developing voltage) Vdev. The development amount DMA (abbreviation of developed mass per area) per unit area was determined.
When a development curve showing the relationship between each development voltage Vdev and the development amount DMA per unit area was drawn, the result shown in FIG. 18 was obtained.
As can be seen from the figure, when Vdev exceeds a certain value, DMA tends to increase substantially in proportion to Vdev. Note that the approximate straight line shown in FIG. 18 is obtained by approximating the data surrounded by hatching among the data of Vdev in FIG. 17A by the least square method.

Also, in FIG. 17A, a plurality of (four in this example) measurement targets for the charge amount Q and particle size d of the toner flying to the counter electrode are selected, and Q (fC) and d ( μm) was measured, and the result shown in FIG. 17B was obtained.
Here, the measurement conditions for the measurement of Q and d may be appropriately selected. In this example, as a measurement condition, the developing device has a standard size (in order to measure the adhesive force in a time-degraded state of the toner. In this example, the printing was performed to the extent that the number of printed sheets of A4 side) corresponds to 15 kPV, and the average value of 3000 toners to be measured was obtained.
In FIG. 17B, DRS means a gap between the drum-shaped photoconductor and the developing roll, and the average toner attached to the counter electrode (photoconductor) by the developing electric field under each developing condition. The adhesion was about -5 to -6 (nN). The toner adhesion force F was determined by F = Q × Vdev / DRS.
Then, when the relationship between Vdev and Q is plotted based on the result shown in FIG. 17B, the result shown in FIG. 19A is obtained, and when the relationship between Vdev and d is plotted, FIG. The result shown in (b) was obtained. The approximate straight line in each figure is a straight line approximated to each plot by the least square method.
According to FIG. 19 (a), it is understood that Q has a relationship that increases approximately proportionally with an increase in Vdev, whereas according to FIG. 19 (b), d increases with an increase in Vdev. It is understood that there is a tendency to decrease approximately proportionally.

Then, in the approximate Vdev-DMA line shown in FIG. 18, Vdev at the intersection of DMA = 0 is considered to correspond to the developing voltage at which the toner starts to fly, and when this was examined, it is shown in FIG. 17 (c). A value like this was obtained.
Then, in the approximate Vdev-Q line shown in FIG. 19A, the value of Q at the developing voltage Vdev at the start of toner flight is assumed to be the charge amount at which the toner starts to fly, and also shown in FIG. 19B. In the approximate straight line of Vdev-d, the value of d at the developing voltage Vdev at the start of toner flight is assumed to be the toner particle diameter at which the toner starts to fly, and the result shown in FIG. 17C is obtained. It was.
In this way, the developing voltage Vdev, the charge amount Q, and the toner particle size (corresponding to the average particle size) d of the toner that starts to fly to the developing roll to be measured are obtained. When these values are used, the toner adhesion force F of the toner that starts flying can be obtained from the calculation formula F = Q × Vdev / DRS.

-Evaluation of toner adhesion-
In evaluating the toner adhesion force, for example, when a low charging blade (for example, one used over time) is used as a charging blade, measurement is performed by the particle charge amount distribution measuring apparatus as described above, and shown in FIG. It is assumed that the development voltage Vdev at the start of flying, the charge amount Q of the flying start toner, and the particle diameter d of the flying start toner are obtained.
On the other hand, for example, a highly charged blade (for example, a new one) is used as the charging blade so that all other conditions are the same and only the charge amount is different, and the measurement using the same particle charge amount distribution measuring apparatus as described above is performed. Then, as shown in FIG. 20, the developing voltage Vdev at the start of the flight, the charge amount Q of the flying start toner, and the particle size d of the flying start toner are obtained.
In this state, Q1 and d1 that are the first measurement conditions are substituted into the mathematical formula for obtaining the toner adhesion force F shown in FIG. 9A, and Q2 and d2 that are the second measurement conditions are substituted. A simultaneous equation as shown in FIG. 21 is created. F (1) represents the toner adhesion force under the first measurement condition, and F (2) represents the toner adhesion force under the second measurement condition. All the measurement conditions were performed in a predetermined low temperature and low humidity environment (temperature 10 ° C., humidity 15% RH).
Then, the simultaneous equations are solved with the coefficients A and B of the simultaneous equations as unknowns, and the coefficients A and B are calculated as shown in FIG.
Thereby, the coefficients A and B of the mathematical formula shown in FIG. 9A are obtained (see FIG. 20), and the mathematical formula of the toner adhesion force F is determined. In this state, when the Coulomb force (electrostatic adhesion force) is calculated from the first term of the formula and the non-electrostatic adhesion force is calculated from the second term, the results shown in FIGS. 20 and 21 are obtained. When the toner adhesion force is expressed in a graph form in which the toner adhesion force is decomposed into a Coulomb force and a non-electrostatic adhesion force, a result as shown in FIG. 21 is obtained.
According to the figure, the toner adhesion force is higher when using a highly charged blade (for example, a new one) than when using a low charged blade (for example over time) with a lower charge. And the coulomb power also increases.
Compared to this, the non-electrostatic adhesion force is different from the case of the Coulomb force in both the highly charged blade with high chargeability and the low charge blade with low chargeability, in a low temperature and low humidity environment (temperature 10 ° C., humidity 15). % RH) is understood to be approximately the same value of 2 nN or more.

Example 4
Next, an embodiment that embodies the developing device according to the first exemplary embodiment is referred to as Example 4, and the relationship between the toner adhesion force and the fog density on the photosensitive member (corresponding to contamination due to flying of a poorly charged toner) is evaluated.
-Relationship between toner adhesion and fog density of toner transferred onto photoconductor-
Now, using a highly charged blade with high chargeability (for example, a new one) and a low charge blade with low chargeability (for example, one that is used over time), for example, a plurality of developing roll models (oil accumulation amount as surface roughness) When the toner adhesion force was changed by using a model having a different V0), and the fog density of the toner transferred onto the photoreceptor at that time was measured, the result shown in FIG. 22 was obtained.
Here, when the allowable value of the fog density on the photosensitive member of the toner is 0.02 or less, the toner adhesion force is 4.5 nN or more in a low temperature and low humidity environment (temperature 10 ° C., humidity 15% RH). It is understood that it is necessary.
However, in this example, since the fog of the toner on the photosensitive member is correlated with the development amount MD (Mass on Developer Roll) on the developing roll, the fog density is set to “ The value converted by the formula of “fogging density (converted value) = fogging density (actual value) × (3 g / m ² ) / (MDg / m ² used in the experiment)” is used. As a method for actually measuring the fog density, the fog toner on the photosensitive member is copied onto a substantially transparent tape and attached to a predetermined paper, and the density of the fog toner on the paper is measured using X-Rite 983 nite. Next, a substantially transparent tape that does not copy the toner is applied to the same paper, and the reference density obtained by measuring the density in the same manner is subtracted from the measured density to obtain the fog density on the photoreceptor.

Further, when the fog density of the toner transferred onto the photoconductor was measured using the Coulomb force as a parameter instead of the toner adhesion force in the above example model, the result shown in FIG. 23 was obtained.
According to the figure, it was confirmed that, for example, when the charging blade deteriorates, the Coulomb force of the toner decreases by about 2 to 2.4 nN as indicated by an arrow. That is, it can be understood that the coulomb force of the toner adhesion force is affected by the charging property of the charging blade, and the coulomb force is likely to change.
On the other hand, when the fog density of the toner transferred onto the photoconductor was measured using the non-electrostatic adhesive force as a parameter instead of the toner adhesive force in the above example model, the result shown in FIG. 24 was obtained.
According to the figure, for example, when the charging blade deteriorates, the fog density of the toner changes accordingly, but the non-electrostatic adhesion force remains substantially the same as shown by the arrow, and the charging blade usage history is It is understood that it is difficult to be affected by the accompanying deterioration. For this reason, even if the charging property by the charging blade changes, the non-electrostatic adhesion force is maintained at substantially the same level. Therefore, the surface roughness of the developing roll is ensured to ensure a certain degree of non-electrostatic adhesion force. It is understood that if the toner is adjusted, it plays an important role in raising the toner adhesion.
Further, from FIG. 24, the relationship between the non-electrostatic adhesion force when using a highly charged blade (for example, a new one) with high chargeability and the fog density of the toner transferred onto the photoreceptor is extracted. The result shown in FIG. 25 was obtained.
At this time, it is understood that the fog density of the toner is not more than an allowable value in any plot. However, since these plots use a highly charged blade with high chargeability, the Coulomb force is 2.5 nN. It is relatively high as described above, and it is understood that the non-electrostatic adhesive force has an effect of suppressing the toner fog phenomenon under such conditions.
In FIG. 25, the non-electrostatic adhesion force and the fog density of the toner are proportional to the toner as the non-electrostatic adhesion force increases, as indicated by an approximate straight line obtained by approximating each plot by the least square method. The fog density tends to decrease.
For this reason, it is understood that if the non-electrostatic adhesive force is 2 nN or more, the fog density of the toner falls within 0.01 or less.

Example 5
Next, an example in which the developing device according to the first embodiment is embodied as Example 5, and desirable characteristics of the developing roll used in Example 5 are examined.
In this embodiment, a deteriorated toner having a standard size (A4 size horizontal size in this example) printed with an idle rotation equivalent to 15 kPV is used, a highly charged blade (for example, a new one) with high chargeability, When the relationship between the Coulomb force as the toner adhesion force and the non-electrostatic adhesion force was examined using a low low charging blade (for example, one used over time), the result shown in FIG. 26 was obtained. In addition, all of these adhesive forces are measured in a low temperature and low humidity environment (temperature 10 ° C., humidity 15% RH).
In this figure, a straight line (4.5 nN) indicated by a thick solid line is selected as the lower limit value of the toner adhesion force, but a region of a desirable toner adhesion force is above the straight line (7.0 nN) indicated by a thick dotted line. Area is selected.
Further, as a desirable region for the non-electrostatic adhesive force that does not affect the deterioration of the charging blade, a region of 2 nN or more is selected as shown by a one-dot chain line in the figure.
As for the relationship between the oil sum V0 as the surface roughness of the developing roll and the non-electrostatic adhesion force, the relationship shown in FIG. 27 is obtained.
In the same figure, an approximate straight line approximated by the least square method for each plot is indicated by a two-dot chain line, and a location where 2.0 nN which is a boundary value of a desired non-electrostatic adhesive force region intersects is V0 = 0.004. It is understood that the oil accumulation amount V0 is 0.004 or less in a desirable non-electrostatic adhesive force region.
In this embodiment, a deteriorated toner having a standard size (A4 size horizontal size in this example) printed with an idle rotation equivalent to 15 kPV is used, and a highly charged blade (for example, a new one) with high chargeability, When the relationship between the Coulomb force as the toner adhesion force and the charge amount of the flying start toner was examined using a low-charge blade with low properties (for example, one that was used over time), the result shown in FIG. 28 was obtained.
In this figure, since the Coulomb force and the charge amount of the flying start toner are substantially proportional to each other, an approximate straight line is created. When the toner adhesion force is 7.0 nN or more, the non-electrostatic adhesion force is At locations where the distribution is 2.0 to 3.0 nN, the non-electrostatic adhesion force is assumed to be 3.0 nN, and the Coulomb force is required to be 4.0 nN or more. Therefore, the charge amount of the flying start toner is 1.5 fC. It is understood that it takes more than a degree.

Example 6
An embodiment of the developing device according to the first embodiment was taken as Example 6, and the relationship between the non-electrostatic adhesion force of the toner to the developing roll used in Example 6 and the particle size of the flying start toner was evaluated. For reference, the developing roll according to Comparative Example 6 not included in Example 6 was also evaluated in the same manner.
-Relationship between non-electrostatic adhesion and flying start toner particle size-
As shown in FIG. 29, a plurality of developing roll models are created, and the charging property by the charging blade is changed for each developing roll model, and the toner adhesion force, Coulomb force, and non-electrostatic adhesion force of the flying start toner are obtained. In addition, the particle diameter of the flying start toner in each case was determined.
The result is shown in FIG.
In the figure, it is understood that the particle diameter of the flying start toner and the non-electrostatic adhesion force of the flying start toner are substantially proportional.

Example 7
An embodiment of the developing device according to the first embodiment is referred to as Example 7, and the developing device according to Example 7 is used over time from the start of use (standard size (in this example, A4 size horizontal size)) with a print number of 15 kPV. The fog density of the toner transferred to the photoconductor during that period was examined, and as shown in FIG. 31, the fog density transferred to the photoconductor was at an allowable level (0.02: TMDA in this example). It was confirmed that it was below.
For comparison, the same conditions as in Example 7 are used as Comparative Example 7 in which the developing roll does not satisfy the formula of the oil sum V0 as the surface roughness of Embodiment 1 (for example, the aluminum rough surface). As shown in FIG. 31, it was confirmed that the fog density of the toner transferred onto the photoconductor exceeds the allowable level after the number of printed sheets exceeds 4 kPV as shown in FIG.

  DESCRIPTION OF SYMBOLS 1 ... Toner holding body, 1a ... Conductive base material, 1b ... Coating layer, 2 ... Charging member, 3 ... Development electric field formation means, 5 ... Image holding body, 6 ... Developing apparatus, E ... Developing electric field, TN ... Toner, d: average particle diameter of toner, V0: amount of oil pool, m: development zone, Wca: average height of waviness curve element, Wc-Sm: average length of waviness curve element

Claims (10)

A toner holding body that is arranged in a non-contact manner facing an image holding body on which a latent image is held, holds toner and circulates and rotates,
A conductive substrate and a coating layer covering the surface of the conductive substrate;
The surface waviness of the coating layer is as follows. The average height of the waviness curve element is Wca, and the average length of the waviness curve element is Wc-Sm.
Wca ≦ 0.5 (μm)
Wc-Sm ≧ 2.5 (mm)
A toner holding member satisfying the following relationship: The toner holder according to claim 1.
The toner holding body, wherein the conductive base material is a metal cylindrical base material. The toner holder according to claim 1 or 2,
The toner carrier, wherein the surface waviness of the conductive substrate has Wca and Wc-Sm of the same degree as the coating layer. The toner holder according to any one of claims 1 to 3,
The toner holding body, wherein the coating layer is configured by a spray coating method. A toner holder according to any one of claims 1 to 4,
A charging member for charging the toner held on the toner holder;
By forming a developing electric field containing at least a DC component having a predetermined potential difference between the image carrier and the toner carrier, the toner held on the toner carrier and charged by the charging member A developing electric field forming means for flying the latent image on the image carrier and attaching the toner to the latent image for development;
A developing device comprising: The developing device according to claim 5, wherein
Assuming that the average particle diameter of the toner is d (μm) and the surface roughness of the toner holding member is V0, an oil pool amount corresponding to the amount of oil accumulated in the oil pool depth Rvk per 1 cm ² of the surface area is V0. ,
V0 / d <6.8 × 10 ⁻⁴
A developing device satisfying the relationship: The developing device according to claim 6.
The developing field forming device forms an electric field in which an alternating current component whose potential changes periodically is superimposed on the direct current component as the developing electric field. The developing device according to any one of claims 5 to 7,
The developing device according to claim 1, wherein the charging member is a metal plate-like member that contacts the surface of the toner holding member. A process cartridge that is detachably attached to a receiving portion formed in advance in an image forming apparatus housing,
An image carrier for holding a latent image;
9. A process cartridge comprising: a developing device according to claim 5 for developing a latent image held on the image holding member with toner. An image carrier for holding a latent image;
An image forming apparatus comprising: the developing device according to claim 5, wherein the latent image held on the image holding member is developed with toner.