JPH11258081A - Inter-powder adhesion measuring device and inter-powder adhesion measuring method and image forming device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively measure nonelectrostatic adhesion between powders by measuring centrifugal force required to separate the powders by a centrifugation method, and calculating the adhesion by using a specific relational expression. SOLUTION: When a sticking quantity per unit area of a powder layer on the sample surface is denoted by M, an average electrification quantity of powder is denoted by Q and centrifugal force required to separate the power is denoted by Fs, the centrifugal force Fs is found to plural samples different in the sticking quantity M and/or the electrification quantity Q to calculate nonelectrostatic adhesion Ft between powders by a relational expression [Ft=Fs-A×(Q/M)<2> ]. Here, A is a constant. When a thickness of a powder layer on the sample surface is H, centrifugal force Fs is similarly found to plural samples different in the thickness H and/or the electrification quantity Q to calculate nonelectrostatic adhesion Ft between the powders from a relational expression [Ft=Fs-B×(Q/H)<2> ]. Here, B is a constant. Thus, since influence of electrostatic force can be separated from dependency of a unit sticking quantity M, the average electrification quantity Q of powder or the thickness H by measuring required centrifugal force Fs, the nonelectrostatic adhesion Ft between the powders can be found by using a specific expression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring adhesion between powders and a method for measuring adhesion between powders, which measure the adhesion between toner particles, and to prevent scattering of toner particles by using them. The present invention relates to a possible image forming apparatus and an image forming method.

[0002]

2. Description of the Related Art In the field of handling powder, it is important to grasp various characteristic values of the powder. As a method of measuring the adhesive force of the powder, a method of estimating a force required to separate the powder from an object to which the powder is attached is generally used. As a method of separating powder from an object, a method using centrifugal force, vibration, impact, air pressure, electric field, magnetic field, or the like is known. Among them, the method using centrifugal force facilitates quantitative measurement, and discussed the contribution of electrostatic attraction and van der Waals force in the adhesion of toner to the photoreceptor and carrier.
J. Mastrangelo, Photogr. Sci. Eng., 26: 194-197 (198
2), `` MHLee and J. Ayala, J., who discussed the charge distribution in toner particles, which is important in toner adhesion to photoreceptors.
Image.Tech., 11: 279-284 (1985) "and" Kazuo Terao and Kiyoshi Shigehiro discussing the adhesion of non-static toner that is difficult to quantify:
Various research results have been published, such as the Journal of the Society of Electrophotography, 34 (1995) 83.

[0003] Here, "M. Takeuchi, A. Onose, M. Anzai,
R.Kojima and K.Kawai: "Proc.IS & T 7 ^th Int.Congress A
dv.Non-Impact Printing Technology, 21991, vol.1, pp.2
Of powder using centrifugal force used in "00-208"
Adhesion measurement method (hereinafter referred to as centrifugal separation adhesion measurement method and
Are shown below. This centrifugal adhesion measurement method
Is separated from the sample substrate with the powder
The receiving substrate to which the powder is attached, the sample substrate and the receiving substrate
Measuring cell composed of a spacer provided between
Is installed in the rotor of the centrifuge, and
The powder is separated from the sample substrate using centrifugal force
Attach it to the plate and apply the powder on the receiving substrate using an optical microscope, etc.
And observe it, import the image to a computer,
Perform the treatment to measure the particle size of the powder, the particle size and specific gravity of the powder
Of the powder and the number of revolutions of the rotor
Calculate the centrifugal force required for separation from
It is a method of asking. Thus, between the powder and the plane
There are many reports on adhesion measurement,
There are few reports on adhesion measurement.

On the other hand, in a toner image transfer process used in an electrophotographic method, a group of toner particles constrained by an electric field on a photoreceptor is pulled and moved by a Coulomb force to a uniform surface having no constraining force. There is a problem that toner is easily scattered. Further, Coulomb repulsion between toner particles acts on the toner transferred onto the transfer member or the intermediate transfer member, which is considered to be one of the causes of toner scattering after transfer. Therefore, the adhesion between toner particles is an important characteristic value for toner scattering. In particular, it is important to control non-electrostatic adhesion such as Van der Waals force and liquid crosslinking force, and it is desired to establish a method for quantitatively measuring the non-electrostatic adhesion.

[0005] Incidentally, as a method related to this type, for example, Japanese Patent Application Laid-Open No. 2-282760 and Japanese Patent Application Laid-Open
JP-333775, JP-A-6-167825,
There is JP-A-6-167826.

[0006]

In the prior art, it is important to control the non-electrostatic adhesion between toner particles in the transfer process of a toner image used in an electrophotographic system, but it is important to control the toner. There has been a problem that a method for quantitatively and efficiently measuring such non-electrostatic adhesion between powders has not been established.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem and to provide a powder adhesion measuring apparatus and a powder adhesion measuring apparatus capable of quantitatively measuring a non-electrostatic adhesion between powders such as toner. It is an object of the present invention to provide a method for measuring an adhesion. Further, another object of the present invention is to provide an image forming apparatus and an image forming method capable of reducing scattering of toner after forming a toner image by using the above-described powder-to-powder adhesion measuring apparatus and method. To provide.

[0008]

In order to achieve the above object, an apparatus for measuring adhesion between powders according to the present invention has a sample surface on which a powder layer is formed by stacking a plurality of powder layers. A sample substrate, a receiving substrate having an adhesion surface for adhering the powder separated from the powder layer, and a measurement cell including a spacer provided between the sample surface and the adhesion surface; and A centrifugal separator having a rotor to be rotated; an image acquisition unit for acquiring an image of the powder attached to the attachment surface; and an image of the powder acquired by the image acquisition unit, and analyzing the image of the powder. Image processing means for determining the number of powders adhering on the surface and the projected area of the powders on the receiving substrate; and the number and projection of the powders adhering to the adhering surface determined by the image processing means Independent of individual powders not adhering to each other due to area Independent state determining means for determining the number and projected area of powder that can take a state of adhering on the receiving substrate, and the relationship between the rotational speed of the rotor of the centrifugal separator and the projected area of the powder adhering on the receiving substrate. A rotor speed determining means for determining a rotor speed at which each powder is in an independent state; an average weight of the powder calculated from an average particle diameter and specific gravity of the powder attached to the attachment surface; From the number of rotations, the adhesion force deriving means for determining the centrifugal force required to separate the powder from the outermost surface of the powder layer formed on the sample surface, unit area of the powder layer on the sample surface The non-electrostatic adhesion between the powders is calculated using the adhesion amount per unit, the average charge amount of the powder, and the value of the centrifugal force required to separate the powder from the outermost surface of the powder layer. And a non-electrostatic adhesive force calculating means.

In order to achieve the above object, the method for measuring the adhesion between powders according to the present invention comprises preparing a sample substrate having a sample surface on which a powder layer is formed by laminating a plurality of powder layers. A substrate forming step of forming a receiving substrate having an adhering surface for adhering the powder separated from the powder layer; and a sample substrate, the receiving substrate, and a substrate provided between the sample surface and the adhering surface. A measuring cell forming step of forming a measuring cell composed of a spacer, a measuring cell setting step of setting the measuring cell in the rotor of a centrifugal separator having a rotor for rotating the measuring cell, A centrifugal separation step of separating the powder on the surface of the powder layer formed on the sample surface by the centrifugal force caused by the rotation of the sample layer and attaching the powder to the attachment surface; Get A substrate obtaining step, obtaining an image of the powder adhering to the adhering surface, and analyzing the obtained image of the powder to obtain the number of powder adhering on the receiving substrate The number deriving step, by analyzing the image of the powder, the projected area deriving step to determine the projected area of the powder on the receiving substrate, and from the relationship between the number and projected area of the powder adhering to the adhering surface An independent state determining step for determining the number and projection area of the powders that can take a state in which individual powders independently adhere to each other without adhering to the receiving substrate; and From the relationship of the projected area of the attached powder, a rotor rotation speed determining step of determining the rotor rotation speed at which each powder becomes an independent state, and the average of the powder calculated from the average particle diameter and specific gravity of the powder From the weight and the rotation speed of the rotor, Adhesion force deriving step of determining the centrifugal force required to separate the powder from the outermost surface of the powder layer, the amount of adhesion per unit area of the powder layer on the sample surface, the average charge amount of the powder, and A non-electrostatic adhesion force calculating step of calculating a non-electrostatic adhesion force between the powders by using a value of a centrifugal force required to separate the powder from the outermost surface of the powder layer. It is characterized by.

In order to achieve the above object, an image forming apparatus according to the present invention comprises at least an electrostatic latent image carrier for carrying an electrostatic latent image, and an electrostatic latent image carrier according to image information. Forming means for forming an electrostatic latent image, developing means for supplying toner to the electrostatic latent image to visualize the toner, and a toner image carrier for carrying the visualized toner image; The non-electrostatic adhesion between toner particles forming the toner image of the toner image carrier, which is measured in advance by the powder adhesion measurement method, is Ft (N), and the average value of the toner charge is Q (μC
/ G), where M (mg / cm ² ) is the maximum amount of toner adhering on the toner image carrier, the following relational expression “M ⁴
Q ² / (Ft × 10 ⁹ ) ≦ 60 ”.

According to another aspect of the present invention, there is provided an image forming method comprising: irradiating at least a uniformly charged electrostatic latent image carrier with light in accordance with image information; An electrostatic latent image forming step of forming and carrying an electrostatic latent image on a body, and supplying toner to the electrostatic latent image to form a visible image, and carrying the visualized toner image on a toner image carrier And a non-electrostatic process between the toner particles forming the toner image on the toner image carrier, which is measured in advance by the method for measuring an adhesion between powders according to claim 6. When the adhesive force is Ft (N), the average value of the toner charge amount is Q (μC / g), and the maximum toner adhesion amount on the toner image carrier is M (mg / cm ² ), the following relationship is obtained. It is characterized by satisfying the expression “M ⁴ Q ² / (Ft × 10 ⁹ ) ≦ 60”.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. << Examples of the Apparatus for Measuring Adhesion Between Powders and Method for Measuring Adhesion Between Powders >> The apparatus for measuring adhesion between powders in this embodiment is shown in FIG.
CPU 41 for controlling the entire apparatus and controlling the steps of the method for measuring the adhesion between powders described later, the centrifugal separator 5 used for measuring the adhesion between powders such as toner, and the interface 4
3, a display means 44 composed of a CRT, etc., for displaying an image of the powder taken in by the scanner 49 and an analysis result of the image, an input means 45 such as a keyboard and a mouse,
A memory 46 storing a control program of the CPU 41 and necessary data, an external storage device 47 for storing measurement data by the centrifugal force separation device 42 and analysis results thereof, and powders observed and photographed by an optical microscope, a CCD camera, or the like. The scanner 49 and the interface 50 for capturing the image of the powder into the apparatus main body, the image of the powder captured via the scanner 49 is analyzed, and the number of powders adhering to the receiving substrate 3 described below, And an image processing means 48 for obtaining an area projected on the receiving substrate 3. Further, as shown in FIG. 2, the centrifugal separator 5 includes a rotor 6 for rotating the measuring cell 1 shown in FIG. The rotor 6 has a hole shape in a cross section perpendicular to its own rotation center axis, and has a sample setting unit 8 that supports the holding member 7 so as to be fittable.
The holding member 7 includes a rod portion 7a and a cell holding portion 7b that holds the measurement cell 1 provided on the rod portion 7a.

In the method for measuring the adhesion between powders according to the present embodiment having such a configuration, the non-electrostatic adhesion between powders such as toner is measured by the procedure shown in FIG. 4 under the control of the CPU 41K. That is, a sample substrate 2 having a sample surface 2a formed by laminating powder in a plurality of layers or more is prepared, and a receiving substrate 3 having an adhering surface on which the powder separated from the sample substrate 2 is adhered is prepared. Receiving substrate forming step 101, sample substrate 2, receiving substrate 3, spacer 4 provided between sample surface 2 a of sample substrate 2 and attachment surface 3 a of receiving substrate 3,
A measuring cell creating step 102 for creating the measuring cell 1 comprising: a measuring cell setting step 102 for setting the measuring cell 1 in the rotor 6 of the centrifugal separator 5 having the rotor 6 for rotating the measuring cell 1; A centrifugal separation step 104 of separating the powder on the surface of the powder layer formed on the sample surface 2 a by the centrifugal force caused by the rotation of the rotor 6 of the separation device 5 and attaching the powder to the attachment surface 3 a of the receiving substrate 3; Is obtained from the rotor 6 of the centrifugal separator 5 to obtain the receiving substrate 3, and the image of the powder adhering to the adhering surface 3 a of the receiving substrate 3 is read by an optical microscope or CC (not shown).
The number of powders adhering to the receiving substrate 3 is obtained by observing and photographing with a D camera, acquiring the image via the scanner 49, and analyzing the acquired image using the image processing means 48. A powder number deriving step 106, a projected area deriving step 107 for obtaining a projected area of the powder on the adhering surface 3a of the receiving substrate 3, and a relationship between the number of powder adhering to the adhering surface 3a of the receiving substrate 3 and the projected area From the independent state determination step 108 for determining the number and projection area of the powders that can take a state in which the individual powders independently adhere to the receiving substrate 3 without adhering to each other; The rotor 6 becomes independent from the relationship between the rotation speed and the projected area of the powder attached to the receiving substrate 3.
A rotor layer number determining step 109 for determining the number of rotations of the powder, a powder layer formed on the sample surface from the average weight of the powder calculated from the average particle diameter and specific gravity of the powder and the number of rotations of the rotor 6. Adhesion deriving step 110 for obtaining the centrifugal force required to separate the powder from the outermost surface of the sample, and the adhesion amount per unit area of the powder layer on the sample surface (or the thickness of the powder on the sample surface) ), A non-electrostatic adhesion calculating step for calculating the non-electrostatic adhesion between the powders from the average charge amount of the powders and the centrifugal force required to separate the powders from the outermost surface of the powder layer. 111.

The measuring cell installation step 103 is performed by removing the rotor 6 of the centrifugal separator 5 and installing the measuring cell 1 in the removed rotor 6. The centrifugation step 104 changes the rotation speed of the rotor 6 of the centrifugal separator 5 with respect to the same sample substrate 2 and exchanges the powder attached to the sample substrate 2 at each rotation speed with the receiving substrate 3.
This is performed by attaching to the attachment surface 3a. With the powder-to-powder adhesion measuring device having the configuration shown in FIGS. 1 to 3 as described above, the measurement cell setting step 103 is a holding step of holding the measurement cell 1 by the cell holding portion 7b of the holding member 7,
The holding member 7 is fitted to the sample setting section 8, and the perpendicular of the sample surface 2 a of the sample substrate 2 and the perpendicular of the attachment surface 3 a of the receiving substrate 3 are both perpendicular to the rotation center axis of the rotor 6 of the centrifugal separator 5. The sample surface 2a of the sample substrate 2 is
a of the centrifugal separator 5 and the rotor 6 of the centrifugal separator 5.
A large centrifugal force can be applied to the measurement cell 1 using the rotor 6.

In the present embodiment, the centrifugal force F applied to the powder is represented by the weight m of the powder, the number of rotations f (rpm) of the rotor, and the distance r from the center axis of the rotor to the powder adhering surface of the sample substrate. It is obtained by the following equation (4). F = m × r × (2πf / 60) ² (4) The weight m of the powder is obtained from the following equation (5) using the true specific gravity ρ of the powder and the circle equivalent diameter d.

M = (π / 6) × ρ × d ³ (5) Further, from equations (1) and (2) described later, the centrifugal force F received by the powder can be obtained from the following equation (6). ^{F = (π 3/5400)} × ρ × d 3 × r × f 2 (6) If the toner layer on the sample surface to be separated by centrifugation, the toner of the outermost surface of the toner layer, due to the rotation Centrifugal force, non-electrostatic adhesion to other toner, Coulomb repulsion to other toner, and mirror image to the sample surface are acting. Here, when it is desired to measure the non-electrostatic adhesion between toners, it is necessary to remove the influence of electrostatic forces such as Coulomb repulsion and mirror image. In the present embodiment, the adhesion amount M (mg / cm ² ) of the powder layer on the sample surface per unit area, the average charge amount of the powder is Q (μC / g), Assuming that the centrifugal force required for separation is Fs (N), the adhesion amount M
And, the centrifugal force Fs is obtained for a plurality of samples having different charge amounts Q, and the non-electrostatic adhesion Ft (N) between the powders is calculated from the following relational expression (1). Here, A is a constant.

Ft = Fs−A × (Q / M) ² (1) Further, the thickness of the powder layer on the sample surface is H (μm), the average charge amount of the powder is Q (μC / g), Assuming that the centrifugal force required to separate the powder from the outermost surface of the powder layer is Fs (N), the centrifugal force Fs is obtained for a plurality of samples having different thicknesses H and / or charge amounts Q. From the relational expression (2), the non-electrostatic adhesion Ft (N) between the powders is calculated. Here, B is a constant.

Ft = Fs−B × (Q / H) ² (2) The centrifugal separator 5 is a CP100α manufactured by Hitachi Koki (maximum rotation speed: 100,000 rpm, maximum centrifugal acceleration: 8).
00,000 × g). As the rotor 6, an angle rotor P100AT manufactured by Hitachi Koki was used. The sample substrate 2, the receiving substrate 3, the spacer 4, and the holding member 7 have strength enough to withstand the large centrifugal force of the centrifugal separator 5, and can be rotated up to the maximum rotation speed of the centrifugal separator 5 when installed in the rotor 6. Since it is necessary to use a lightweight material having a weight not more than an appropriate weight, an aluminum member was used. Further, it is desirable that the attachment surface 3a of the receiving substrate 3 be a smooth surface with no scratches on which aluminum is deposited. Eliminating the scratches on the attachment surface 3a can prevent the scratches on the receiving substrate 3 from being measured during the screen processing for toner particle measurement. Further, as the sample surface 2a of the sample substrate 2, any material that can form a powder layer to be measured can be used. The powder to be measured may be formed by dropping the powder to be measured from above onto an arbitrary sample surface.However, in order to form a powder layer having a uniform thickness, the powder layer is formed by applying electrophotography. It is desirable to form. In particular, when the measurement target is a toner, it is necessary to prepare a sample in a state where it is desired to actually measure the adhesive force between the toners. For example, when it is desired to measure the adhesion between toners of the toner image on the photoconductor after the development process, it is desirable to use a sheet-shaped photoconductor as the sample surface 2a. When it is desired to measure the state after receiving a nip pressure or the like in the transfer step, it is desirable to attach actual paper or an OHP sheet to the sample substrate 2 as the sample surface 2a.

Hereinafter, a more specific method for measuring the adhesion between powders will be described. In this embodiment, a digital full-color copying machine PRETER650 manufactured by Ricoh was used for forming the toner layer. In addition, three kinds of toners with different amounts of external additives (H2000 silica) were prepared based on the toner for PRETER650. Table 1 shows the measurement results of the aggregation degree of various toners.
Shown in

◎

[Table 1]

The aggregation degree C of the toner was measured by the following method using a powder tester PT-N manufactured by Hosokawa Micron. Attach three types of meshes to the powder tester (screen opening, upper 75 μm, middle 45 μm, lower 2
2 μm), and place the toner sample on the upper mesh of 2 g, and vibrate for 30 seconds with the amplitude scale having an amplitude of 1 mm. The aggregation degree of the toner is calculated from the weight of the toner remaining on each mesh by the following equation.

◎

(Equation 1)

The agglomeration degree of the toner shown here is a characteristic value indicating the fluidity of the toner. The smaller the value is, the more the fluidity tends to be improved. Various toners and PRETER65
A carrier of a two-component developer for 0 was mixed to obtain a developer.
Image forming conditions such as charge potential and exposure amount were set for various developers, and a circular toner image having a diameter of 3 mm was formed on the intermediate transfer belt. Further, the intermediate transfer belt was cut out and stuck on a circular aluminum substrate as shown in FIG. Since the toner layer formed on the sample surface (part of the intermediate transfer belt) 2a of the sample substrate (aluminum substrate) 2 is charged, the Coulomb repulsion between the toner particles and the mirror image with the substrate act. Conceivable. In order to consider the effects of these forces, a plurality of samples were prepared in which the toner charge amount Q (μC / g) and the toner adhesion amount M (mg / cm ² ) on the intermediate transfer belt were changed for each toner type. Surface 2a was created. The toner charge amount Q and the toner adhesion amount M were measured on a toner image having a known area by a suction Faraday cage method. The sample substrate 2 thus prepared is mounted on the holding member 7, and the holding member 7 is set on the rotor 6, and the rotor 6 is set on the centrifugal separator 5.

Further, when the centrifugal separator 5 is operated,
The toner particles are separated from the surface of the toner layer by centrifugal force, and the receiving substrate 3 (diameter body: 8 mm, toner receiving range: 5.
2 mm). The centrifugal force F received by the toner is obtained from the above-described equation (6). D: toner particle size,
ρ: toner specific gravity 1.2 g / cm ³ , r: centrifugal radius
47 mm, f: separation rotational speed rpm.

[0025] In ^{F = (π 3/5400)} × ρ × d 3 × r × f 2 (6) The present embodiment, since a relatively large toner number of separating from the sample substrate 2, as an effective evaluation method, The particle diameter of each toner on the receiving substrate 3 was not measured, and the average particle diameter d was 7.5 μm.
m, and a method of counting only the number of toner particles was adopted. That is, the center of the attachment surface 3a of the receiving substrate 3 is C
The images were magnified and observed with a CD microscope camera (Hyperscope manufactured by KEYENCE CORPORATION) and output with a video printer. 2
When a 00 × lens is used, 77
The magnification is twice as large as one screen, 1.4mm wide x 1.1m long
An area of m = 1.54 mm ² can be observed. The enlarged photograph is taken into a personal computer (on the main body side of the adhesive force measuring device between powders) in a 400 dpi × 400 dpi black-and-white photograph mode by using a scanner 49, and is read by an image processing means 48 (image processing software (Image Pro Plus)). A binarizing process and a counting process were performed, and the number of toner particles and the number of pixels occupied by the toner particle portion, that is, the projected area of the toner on the receiving substrate 3 were counted.

Further, the rotational speed f at which the toner particles in the outermost layer at the center of the toner layer start to be separated is determined by the method described later, and the centrifugal force F required for separating the toner is obtained from the equation (6). . When centrifuging the toner layer, the problem is the large number of toners to be handled. When counting the number of toner particles on the attachment surface 3a by image processing software, as the number of toners increases, a plurality of toner particles overlap and are counted as one large particle. Therefore, in this embodiment,
A method of determining the number of rotations for separation using the total area (projected area) occupied by the toner particle portions instead of the number of toner particles is employed.

FIG. 6 shows the relationship between the number of toner particles on the adhesion surface 3a and the projected area of the toner portion (the number of pixels for image processing) for all the samples measured in this embodiment. A linear relationship holds between the number of pixels and the number of toner particles until the number of pixels of the toner portion in one video print is about 1 × 10 ⁵ . This means that up to about 1000 toner particles are attached independently. On the other hand, when the number of pixels in the toner portion is 2 × 10 ⁵ or more, the number of toner particles is saturated at about 1800. This means that when the number of toners is about 1800 or more, the toner particles overlap on the attachment surface 3a. That is, in this embodiment, in the independent state determination step 108, the number of toners on the receiving substrate 3 is 1
800 or 2 × 10 ⁵ toner part pixels are required to be the maximum number of toner particles that can be in an independent state.
In this state, it is considered that the toner particles are not separated but the toner particles are separated independently. In this embodiment, the evaluation criteria of the independent state are as follows. As the centrifugal force increases, the toner that has started to separate from the surface of the toner layer accumulates and accumulates 1800 (the number of pixels is 2 × 1).
The number of rotations at the time of flying about 0. ⁵ ) was determined as the separation rotation number f. The number of pixels in the entire area of the video print screen is about 2.4
Since it is × 10 ⁶ , about 8% of the surface layer toner is in a separated state from a simple consideration. In this state, it is considered that the toner particles are independently separated one by one.

FIGS. 7 to 9 show changes in the number of separated toners with respect to the number of centrifugal rotations for the three types of toners a, b, and c in this embodiment. The abscissa represents the centrifugal rotation speed (rpm), and the ordinate represents the cumulative number of pixels of the toner portion in logarithm. The positions of 2 × 10 ⁵ pixels determined in the independent state determination step 108 are indicated by arrows. Table 2 shows the measurement results of the toner charge amount Q (μC / g) and the toner adhesion amount M (mg / cm ² ) on the sample surface 2a under each condition.

◎

[Table 2]

For each of the above conditions, the cumulative number of pixels is 2
The number of rotor rotations at which the number of rotors becomes × 10 ⁵ was determined as the number of rotations for separation f, and the centrifugal force F was calculated by the equation (6) with the toner particle size being 7.5 μm. The centrifugal force F is a force necessary for separating the toner particles on the surface layer, and reflects the influence of both the electrostatic force and the non-electrostatic adhesive force acting between the toner particles.
Table 3 shows the calculation results of the centrifugal force F. For any toner, the larger the toner charge amount Q, the larger the centrifugal force F for separating the toner, and the larger the toner adhesion amount M, the smaller the centrifugal force F.

◎

[Table 3]

In this embodiment, a non-electrostatic adhesion force between toner particles is determined by considering and analyzing a model of an adhesion state by a mirror image as shown in FIG. Assuming that a point charge exists at the center of the toner particles on the surface layer, only the mirror image force acting on the point charge with the substrate is considered. Point charge q
Is proportional to the toner charge amount Q (μC / g), and the distance h between the substrate and the point charge is substantially proportional to the toner adhesion amount M (mg / cm ² ). Therefore, the image force F acting on the point charge is F∝ (q /
h) ² ∝ [Q / M] It is proportional to ² . This calculation result is also shown in Table 3.

Here, FIG. 11 shows the result of rearranging the centrifugal force based on the analysis method using the image force model according to the present embodiment. The vertical axis represents the centrifugal force F at which the toner on the surface starts to separate.
s and the horizontal axis show the calculated value of [Q / M] ² . The value of [Q / M] ² is considered to be proportional to the image power, but its absolute value itself has no meaning. Although there is variation in each toner,
A linear increase trend is observed. Accordingly, it is considered that the centrifugal force when the horizontal axis is extrapolated to zero represents the non-electrostatic adhesion force Ft between the toner particles. That is, the following relational expression (7) holds. Here, A is a constant.

Fs = Ft + A × (Q / M) ² (7) Further, FIG. 12 shows the correlation between the adhesion force Ft between the non-static toner particles and the toner aggregation degree. It was quantitatively confirmed that as the amount of the external additive added to the toner decreased, the degree of aggregation of the toner increased and the non-electrostatic adhesion between toners increased. In addition,
Instead of the toner adhesion amount M, the thickness H of the toner layer was measured. The toner layer thickness H was measured using a surface profile measuring microscope VF7500 manufactured by Keyence Corporation. FIG. 13 shows a correlation between the toner adhesion amount M and the toner layer thickness H. There is a substantially proportional relationship between the two. Therefore, like equation (7), equation (8)
Was satisfied, and Ft could be measured. Here, B is a constant.

Fs = Ft + B × (Q / H) ² (8) As a result of further study of this embodiment, the toner scattering in the above-described transfer process, the so-called transfer dust phenomenon, is caused by the toner charge amount and the toner adhesion amount. Furthermore, it has been found that it can be described by three characteristic values of the adhesion between toners measured by the method of this embodiment. As the amount of transfer dust increases, the number of toner particles visible in a non-image portion such as between lines increases. The transfer dust level was evaluated from the number of toner scattered in the non-image area. In this embodiment, a 200 μm-wide linear toner image on the intermediate transfer belt was photographed by a CCD microscope camera, and an enlarged photograph thereof was captured as a monochrome continuous tone image from the scanner 49 into a personal computer. Using commercially available image processing software, the continuous tone photographic image was binarized to emphasize and separate the contours of the toner particle portion and the belt portion. The number of toner particles (the number of objects) was counted using the counting function of the image processing software, and the number of toner particles scattered from the line edge per 1 mm length was calculated. This numerical value was defined as "the number of toner particles on the line N (number / mm)". The toner charge amount Q and the toner adhesion amount M on the intermediate transfer belt were measured by a suction Faraday cage method, and were 200 μm
A line image having a width was suctioned and collected by a known length. The amount of toner charge per unit weight is calculated from the amount of charge induced by the collected toner q and the weight m, and the average toner charge amount Q
(ΜC / g). Also, the average value of the line width is calculated from the enlarged photograph of the line image to calculate the area a of the line image.
(Mg / cm ² ).

Here, FIG. 14 shows a correlation between the number N of toner particles scattered on the intermediate transfer belt and the amount M of toner adhering on the intermediate transfer belt. M = 0.8-1.0 mg / cm ²
The experiment was conducted with a single-color image of magenta toner when the toner adhesion amount was relatively small, and with a two-color superimposed image in which magenta toner was superimposed on cyan toner when the toner adhesion amount was larger than that. The toner a described above was used as the toner. Further, a developer was prepared using three types of carriers having only different charging capabilities, and the toner charge amount Q on the intermediate transfer belt was changed as a parameter. The charging ability of the carrier was controlled by changing the firing temperature during the manufacturing process. Carrier A, carrier B, and carrier C were used in the order of higher charging ability. In FIG. 14, the number N of the line-scattered toner sharply increases with an increase in the toner adhesion amount M. In addition, the larger the toner charge amount Q, the larger the number N of the line scattering toner. According to the study of the present inventor, the practically acceptable level of the transfer dust is that the number of toner particles scattered on the intermediate transfer belt is 130 / mm. When the toner charge amount is large, the amount of toner adhesion on the intermediate transfer belt must be reduced. That is, image forming conditions must be set such that the amount of toner adhered to the portion where the amount of adhered toner is the largest in the image area on the intermediate transfer belt is reduced. vice versa,
If the toner charge amount is reduced, even if the maximum toner adhesion amount on the intermediate transfer belt is large, it is acceptable. The three curves in FIG. 14 represent the characteristics of “N = αM ⁴ Q ² + β”, and α =
0.28 and β = 18. This characteristic and the experimental results of transfer dust with respect to the toner adhesion amount M and the toner charge amount Q agree well. Similarly, FIG. 15 shows the results obtained by using the three types of toners a, b, and c having different addition amounts of the external additives and changing the toner aggregation degree or the adhesion force between the toners as a parameter.

Also in FIG. 15, the increase in the number N of scattered toner with the increase in the amount M of attached toner is the same. Also,
The number of scattered toners tends to decrease as the degree of aggregation of the toner or the adhesion between the toners increases due to the decrease in the amount of the external additive. The three curves in FIG. 15 also show “N = αM ⁴ Q ² +
β ”, α = 0.28 and β = 1 for toner a.
8, α = 0.12 and β = 14 for toner b, and α = 0.08 and β = 10 for toner c. This characteristic is in good agreement with the experimental results of the transcription dust.

FIG. 16 shows the relationship between the non-electrostatic adhesion Ft between toner particles determined in FIG. 12 and the parameter α determined from FIG. The curve in the figure is α = 1.8 / F
t (the unit of Ft in FIG. 16 is nN = 10 ⁻⁹ N), which is almost in agreement with the experimental result. Although the details of the mechanism of the generation of transfer dust are not clear, the non-electrostatic adhesion force Ft (N) between the toner particles, the toner adhesion amount M,
It has been clarified experimentally that the line scattering toner number N agrees well with the following empirical formula with respect to changes in the three parameters of the toner charge amount Q.

N = 1.8 M ⁴ Q ² / (Ft × 10 ⁹ ) + β (β is about 10 to 20) (9) As described above, the practically allowable number of toner particles N on the line is about 130 / mm or less. Therefore, assuming that β is 10 to 20, N−β = 1.8 M ⁴ Q ² / (Ft × 10 ⁹ ) ≦ 110 to 120 (10) Therefore, the following relational expression (3) is applied to the portion where the amount of toner is largest in the image area on the intermediate transfer belt.
By setting an image forming condition that satisfies the condition, an image with less transfer dust can be obtained.

M^FourQ^Two/ (Ft × 10⁹) ≦ 60 (3) In the above relational expression (3), the non-electrostatic
Strength Ft is 5 × 10 ^-9N ~ 3 × 10^-8Is in the range of N
Is preferred. Ft is 5 × 10^-9Places smaller than N
In order to satisfy the relational expression (3), the toner adhesion amount
M or the toner charge amount Q needs to be very small.
You. Toner in the toner-rich area on the intermediate transfer belt
-Decrease in the amount of adhesion M results in insufficient image density and toner charging
The decrease in the amount Q overlaps with the decrease in the toner cohesion degree and the toner scatters.
And so on. On the other hand, Ft is 3 × 10^-8Than N
If larger, the number of toner particles scattered on the line for transfer dust
N decreases in the decreasing direction, but the toner image
Problems such as deterioration of graininess and deterioration of transportability when supplying toner
Is generated.

In the relational expression (3), the absolute value of the toner charge amount on the intermediate transfer belt is 10 to 30 μC.
/ G is preferable. If the absolute value of the toner charge amount is smaller than 10 μC / g, the number of toner particles scattered in the line is reduced for transfer dust, but problems such as toner scattering and transfer failure occur. Conversely, when the absolute value of the toner charge amount is larger than 30 μC / g, transferability becomes insufficient.

Further, in this embodiment, the surface resistance of the intermediate transfer belt is preferably 10 ⁸ Ωcm to 10 ¹⁰ Ωcm. If the surface resistance value is smaller than 10 ⁸ Ωcm, the transfer voltage leaks and transfer failure occurs. Conversely, if the surface resistance is greater than 10 ¹⁰ Ωcm, the non-image portion of the intermediate transfer belt after the belt transfer process will maintain a negative potential. Therefore, there is a disadvantage that a static eliminator value for removing the residual potential is required. However, the charge retention in the non-image portion is effective in reducing transfer dust on the intermediate transfer belt. That is, Coulomb repulsion acts between the negative charges of the toner between the toner particles forming the image on the intermediate transfer belt to cause toner scattering, but when the non-image portion holds the negative charges, It is considered that Coulomb repulsion acts between the negative charge of the non-image portion and the toner charge to suppress transfer dust. In such a case, it is not necessary to always satisfy the condition of the relational expression (3) for reducing the transfer dust. Conversely,
The relational expression (3) indicates that the volume resistance value of the intermediate transfer belt is 10 ¹⁰ Ω.
cm or less is particularly effective.

<< First Embodiment of the Image Forming Apparatus and Image Forming Method >> Next, referring to FIG. 17, a color image forming apparatus to which the measurement result of the above-described method for measuring the adhesion between powders is applied will be described. In the present embodiment, four color developing units are arranged side by side to face one photoconductor, and toner images formed for each different color component on the photoconductor are sequentially superimposed and transferred on an intermediate transfer belt. The color image is obtained by batch-transferring the superimposed transferred toner images onto transfer paper or the like.
A drum intermediate transfer member system is adopted.

In FIG. 17, the photosensitive drum 35 (= electrostatic latent image carrier) is a function-separated type photosensitive film formed by laminating an undercoat layer, a charge generation layer, and a charge transport layer on an aluminum tube in this order. With layers. The thickness of the photosensitive layer is about 28 μm, and the capacitance is about 90 pF / cm ² . In the present embodiment, after the photosensitive drum 35 is uniformly negatively charged (about -650 to -700 V) by the scorotron charger 21, a laser beam corresponding to image information is applied to the exposure unit 22, and -100 V to −100 V is applied. 5
A 00V electrostatic latent image is formed. The potential of the photosensitive member and the potential of the exposed portion can be detected by the potential sensor A23 to control the charging condition, the exposure condition, and the like. That is, the means for forming the electrostatic latent image includes the scorotron charger 21 and the exposure unit 2
2. It comprises a potential sensor A23 and the like.

In the developing section 24 (= developing means), developing devices of four colors are arranged side by side, and develop an electrostatic latent image for each color. This is a reversal development system in which a negatively charged toner is attached to a low potential portion on a photoconductor using a dry two-component developer. The dry two-component developer is composed of a pulverized toner having an average particle size of 7.5 μm and a resin-coated carrier having an average particle size of 50 μm, and the charge amount of the toner in the developer is -10 to -30.
μC / g. The toner has an external additive of 0.2 to 0.1.
8 parts by weight of silica fine particles are added. In this embodiment, the developing bias value is set to about -500 to -550V. An AC component may be superimposed on the developing bias.
A P sensor 25 is installed at a position after the development, and the process condition can be controlled by detecting the toner adhesion amount from the optical reflectance.

The toner images of each color are transferred to the intermediate transfer belt 2.
6 (= toner image carrier). An indirect transfer voltage application method is adopted, and a belt portion bridged between the entrance roller 32 and the exit roller 33 is configured to be able to contact and separate from the photoconductor. The intermediate transfer belt 26 is a single-layer medium resistor in which carbon black is dispersed in a polycarbonate resin, a fluorine resin, or the like, has a thickness of about 150 μm, a surface resistance value of 10 ⁸ to 10 ¹⁰ Ωcm, and a volume resistance value. Used in the range of 10 ⁹ to 10 ¹¹ Ωcm.
In addition, the entrance roller 32 is grounded, and the exit roller 33 has +
A transfer voltage (Vt) of about 1000 to +1500 V is applied. The transfer voltage (Vt) is supplied from a power supply (not shown), and its output value is controlled by a control unit (not shown). Hereinafter, the transfer from the photoconductor to the intermediate transfer belt 26 is referred to as “belt transfer”. The amount of charge of the residual toner on the photoconductor after the belt transfer is controlled by a PCC (charger before cleaning) 27 and is removed by a drum cleaning device 29 with a brush and a blade.

In this embodiment, the intermediate transfer belt 26
After the first color toner image is formed thereon, the second color image forming operation is started, and the second color toner image is transferred onto the intermediate transfer belt 26 in a superimposed manner. At this time, the transfer voltage may be increased for each transfer order. In the case of a full-color image, four color toner images of black, cyan, magenta, and yellow are sequentially formed on the intermediate transfer belt 26, and then are collectively transferred onto the recording paper 34. To transfer the toner image from the intermediate transfer belt 26 to the recording paper 34, a positive voltage is applied from the back side of the paper by the paper transfer roller 31. Hereinafter, the transfer from the intermediate transfer belt 26 to the recording paper 34 is referred to as “paper transfer”. The toner remaining on the intermediate transfer belt 26 after the paper transfer is removed by the cleaning device 28.

<< Second Embodiment of the Image Forming Apparatus and Image Forming Method >> The configuration of the image forming apparatus of this embodiment is the same as that of the first embodiment.
Is substantially the same as the embodiment (FIG. 17), but the surface resistance of the intermediate transfer belt 26 is 10 ⁹ Ωc as will be described later.
m, a single-layer medium resistor having a volume resistance of 10 ¹⁰ Ωcm was used. Further, in this embodiment, the non-electrostatic adhesion F between the toner particles measured by the above-described method for measuring the adhesion between powders is used.
Using the toner a having a t of 8 × 10 ⁻⁹ N, the transfer dust quality in the final image was visually determined for the blue line portion where cyan and magenta were overlapped in two colors. In the color portion where the two colors are overlapped in this way, the amount of toner adhered on the intermediate transfer belt 26 before the paper transfer step, that is, the transfer amount increases. If the transfer dust can be reduced in the portion where the toner adhesion amount is maximum on the intermediate transfer belt 26, the transfer dust is surely reduced even in the portion where the toner adhesion amount is smaller than this. The intermediate transfer belt 26 is
A carbon black dispersed in an ethylene-tetra-fluoroethylene (ETFE) resin has a surface resistance of 10
^It is a single-layer medium resistor having a resistance of ⁹ Ωcm and a volume resistance of 10 ¹⁰ Ωcm, and the belt transfer bias value is set to +1200 V for both the first color and the second color. The charge amount of the toner in the developer was about −30 μC / g for both cyan and magenta. The average value Q of the toner charge amount on the intermediate transfer belt 26 after the belt transfer step was −17.7 μC / g. At this time, the number of toner particles scattered on the line is the result of the plot in FIG.
The toner adhesion amount M on the intermediate transfer belt is 1.1 mg / c
When m ² or less, “M ⁴ Q ² / (Ft × 10 ⁹ ) ≦ 60” was satisfied, and the transfer dust was at an acceptable level. No other problems occurred.

For comparison with this embodiment, FIG.
In the results of the plots in the middle, on the intermediate transfer belt 26
1.2mg / cm^TwoPlace
When the relational expression “M^FourQ^Two/ (Ft × 10⁹) ≦ 60 ”
It was not established, and the transfer dust became noticeable and unacceptable. << Third Embodiment of Image Forming Apparatus and Image Forming Method >>
 The configuration of the image forming apparatus of this embodiment is the same as that of the first embodiment (FIG.
This is almost the same as 17). In this embodiment, the powder
Non-electrostatic adhesion between toner particles measured by adhesion measurement method
Ft is 2 × 10 ^-8N toner c was used. In developer
Of -28 μC / g for both cyan and magenta
It was about. Intermediate transfer belt 26 after belt transfer step
The average value Q of the toner charge amount above is −17.4 μC / g.
there were. At this time, the number N of toner scattered on the line is represented by △ in FIG.
As a result of the plot, the toner on the intermediate transfer belt 26
-The amount of adhesion M is 1.36 mg / cm^TwoIn the following, the relationship
The expression "M^FourQ^Two/ (Ft × 10⁹) ≦ 60 ”is established and transferred.
Chile was at an acceptable level. Other problems also occur
Did not live.

<< Fourth Embodiment of the Image Forming Apparatus and Image Forming Method >> The configuration of the image forming apparatus of this embodiment is the same as that of the first embodiment.
This is almost the same as the embodiment (FIG. 17). In this embodiment,
As in the third embodiment, a toner c having a non-electrostatic adhesion Ft between toner particles of 2 × 10 ⁻⁸ N was used. further,
The toner concentration in the developer was reduced to increase the toner charge amount. The charge amount of the toner in the developer was about −40 μC / g for both cyan and magenta. The toner charge amount Q on the intermediate transfer belt 26 after the belt transfer step was −31 μC / g, which is out of the range of the present embodiment. At this time, the toner adhesion amount M on the intermediate transfer belt 26 is 1.00 mg / cm.
^{In 2} , the relational expression “M ⁴ Q ² / (Ft × 10 ⁹ ) ≦ 60” was satisfied, and the transfer dust was at an acceptable level. However, since the toner charge amount on the intermediate transfer belt 26 was too large, transfer failure occurred in the paper transfer process.

<< Fifth Embodiment of Image Forming Apparatus and Image Forming Method >> The configuration of the image forming apparatus of this embodiment is the same as that of the first embodiment.
This is almost the same as the embodiment (FIG. 17). In this embodiment,
An image was formed in the same manner as in the fourth embodiment using toner d having an external additive addition amount of 1.0 part by weight. The non-electrostatic adhesion Ft between the toner particles measured by the method for measuring the adhesion between powders was about 4 × 10 ⁻⁹ N, which is out of the range of the present embodiment. The toner charge amount in the developer is -15 μm for both cyan and magenta.
It was about C / g. The average value Q of the toner charge amount on the intermediate transfer belt 26 after the belt transfer step is -11.5 μC.
/ G. At this time, when the toner adhesion amount M on the intermediate transfer belt 26 is 1.1 mg / cm ² , the relational expression “M ⁴
Q ² / (Ft × 10 ⁹ ) ≦ 60 ”was established, and the transfer dust was at an acceptable level. However, toner scattering from the developing device occurred.

<< Second Embodiment of the Image Forming Apparatus and Image Forming Method
Sixth Embodiment >> The configuration of the image forming apparatus of the present embodiment is the same as that of the first embodiment.
This is almost the same as the embodiment (FIG. 17). In this embodiment,
Using the carrier A and the toner e to which no external additive was added,
Image formation was performed in the same manner as in the example. Measurement of adhesion between powders
Non-electrostatic adhesion Ft between toner particles measured by the method is 4
× 10^-8N, which is out of the range of the present embodiment. Developer
The toner charge amount in the medium was -25 μC / c for both cyan and magenta.
g. Intermediate transfer belt 2 after belt transfer step
6 is −16 μC / g.
Was. The toner adhesion amount M on the intermediate transfer belt 26 is 1.
5mg / cm^TwoThen, the relational expression "M^FourQ ^Two/ (Ft × 1
0⁹) ≦ 60 ”holds, and the transfer dust is at an acceptable level.
Met. However, the graininess of the dot image after development deteriorates
did.

<< Seventh Embodiment of the Image Forming Apparatus and Image Forming Method >> The configuration of the image forming apparatus of the present embodiment is as follows.
Is substantially the same as that of the embodiment (FIG. 17), except that the intermediate transfer belt 26 is a single layer having a surface resistance of 10 ⁸ Ωcm and a volume resistance of 10 ¹¹ Ωcm in which carbon black is dispersed in a polycarbonate resin. A medium resistor was used. As a result, the charge amount of the toner in the developer was-for both cyan and magenta.
It was about 30 μC / g. The average value Q of the toner charge amount on the intermediate transfer belt 26 after the belt transfer step is -17.
It was 7 μC / g. When the toner adhesion amount M on the intermediate transfer belt 26 is 1.0 mg / cm ² , the relational expression “M ⁴ Q
² / (Ft × 10 ⁹ ) ≦ 60 ”was established, and the transfer dust was at an acceptable level. There was no residual charge on the intermediate transfer belt 26, and the charge eliminator for the intermediate transfer belt 26 could be omitted. No other problems occurred.

<< Eighth Embodiment of the Image Forming Apparatus and Image Forming Method >> The configuration of the image forming apparatus of the present embodiment is a first embodiment.
This is almost the same as the embodiment (FIG. 17), except that a high resistance layer of about 20 μm is provided on the surface of the intermediate transfer belt 26. The surface layer is obtained by dispersing titanium oxide in PVdF resin, and has a surface resistance of 10 ¹³ Ωcm. The belt transfer bias value was set to +1600 V during cyan transfer of the first color and +2000 V during magenta transfer of the second color. Further, toner a was used as a developer. The charge amount of the toner in the developer was about −24 μC / g for both cyan and magenta.
The toner charge amount Q on the intermediate transfer belt 26 after the belt transfer step is −14.0 μC / g, and the toner adhesion amount M is 1.3.
At 7 mg / cm ² , the relational expression “M ⁴ Q ² / (Ft × 1
0 ⁹ ) ≦ 60 ”, but the intermediate transfer belt 2
6, the number N of the line scattering toner is only about 50,
Transcript levels were at acceptable levels. This is presumably because the negative charges in the non-image portion on the intermediate transfer belt 26 suppressed toner scattering. However, an afterimage due to transfer unevenness occurred in the next image forming process due to the influence of the negative charge.

According to this embodiment, the centrifugal force Fs required to separate the powder from the outermost surface of the powder layer by the centrifugal separation method
(N) was measured, and the adhesion amount M (mg / cm ² ) of the powder layer on the sample surface per unit area and the average charge amount Q (μ) of the powder layer were measured.
Since the influence of the electrostatic force can be separated from the dependency of C / g), the non-electrostatic adhesion Ft (N) between the powders can be obtained. Further, the centrifugal force Fs (N) required for separating the powder from the outermost surface of the powder layer by the centrifugal separation method was measured, and the thickness H (μm) of the powder layer on the sample surface and the average of the powder were measured. Since the influence of the electrostatic force can be separated from the dependence of the charge amount Q (μC / g), the non-electrostatic adhesion Ft (N) between the powders can be obtained.

According to the present embodiment, the step of forming a powder layer by laminating a plurality of layers of powder on the sample substrate 2 is performed by an electrophotographic developing process. Since the powder layer is formed on the sheet-like sample substrate 2 on which is formed, a uniform powder layer can be formed. Further, the step of forming a powder layer by laminating the powder on the sample substrate 2 to a thickness of at least a plurality of layers is performed on the powder image carrier on which the electrostatic latent image is formed by an electrophotographic developing process. After the powder layer is formed, the powder image is transferred and formed on a sheet-like sample substrate by an electrophotographic transfer process, so that the powder layer is formed with a simple configuration and accurately. Non-electrostatic adhesion can be measured. That is, the non-electrostatic adhesion between powders such as toner can be quantitatively and efficiently measured.

Further, according to this embodiment, the toner particles
Non-Electrostatic Adhesion of Toner and Toner Band on Toner Image Carrier
Optimizes the relationship between the three characteristic values of charge and toner adhesion
Therefore, it is possible to obtain high quality images with less transfer dust.
Wear. In addition, non-contact between toner particles on the toner image carrier
Optimize electrostatic adhesion, for example, on a toner image carrier
Non-electrostatic adhesion F between toner particles of the formed toner image
t (N) is 5 × 10 ^-9N ~ 3 × 10^-8In the range of N
To reduce transfer dust and prevent toner scattering and development.
Suppress the occurrence of abnormal images such as unevenness and obtain high quality images
Can be Or optimize the toner charge amount,
For example, the absolute value of the average charge amount of the toner on the toner image carrier
The value was set to 10 to 30 μC / g.
High quality images with little toner scattering and no toner scattering or uneven development
Can be obtained.

According to the present embodiment, the toner image carrier is an intermediate transfer belt for temporarily supporting a toner image, and the resistance value of the intermediate transfer belt is optimized, for example, the surface resistance value of the intermediate transfer belt. Is 10 ⁸ Ωcm to 10 ¹⁰ Ωcm, so the transfer device is small with a small device,
A high-quality color image without any afterimage can be obtained.

[0059]

As described above, according to the present invention, the centrifugal force Fs (N) required to separate the powder from the outermost surface of the powder layer is measured by the centrifugal separation method, and the centrifugal force Fs (N) is measured on the sample surface. The influence of electrostatic force can be separated from the dependence of the adhesion amount M (mg / cm ² ) per unit area of the powder layer and the average charge amount Q (μC / g) of the powder. Non-electrostatic adhesion F
t (N) can be determined. The centrifugal force Fs (N) required to separate the powder from the outermost surface of the powder layer by the centrifugal separation method was measured, and the thickness H (μ) of the powder layer on the sample surface was measured.
m) and the influence of the electrostatic force can be separated from the dependence on the average charge amount Q (μC / g) of the powder, so that the non-electrostatic adhesion Ft (N) between the powders can be obtained. . Therefore, it is possible to provide a powder adhesion measuring apparatus and a powder adhesion measuring method capable of quantitatively measuring the non-electrostatic adhesion between powders such as toner.

Further, according to the present invention, the non-electrostatic adhesive force between toner particles and the toner Since the relationship between the three characteristic values of the charge amount and the toner adhesion amount can be optimized, a high-quality image with less transfer dust can be obtained. Therefore, it is possible to provide an image forming apparatus and an image forming method capable of reducing scattering of toner after toner image formation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a powder adhesion measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a measuring cell of a centrifugal separator in the apparatus for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a centrifugal separator in the apparatus for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 4 is a flowchart showing an outline of a method of measuring an adhesion force between powders according to an embodiment of the present invention.

FIG. 5 is a sample diagram of centrifugal separation in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 6 is a diagram showing the correlation between the toner area and the number of toner particles in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 7 is a diagram showing the result of centrifugal separation of toner a in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 8 is a diagram illustrating a result of centrifugal separation of toner b in a powder adhesion measuring apparatus and a powder adhesion measuring method according to an embodiment of the present invention.

FIG. 9 is a diagram showing the results of centrifugal separation of toner c in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 10 is a diagram showing a mirror image model in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 11 is a diagram showing an analysis result of centrifugal force by a mirror image force model in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders according to one embodiment of the present invention.

FIG. 12 is a diagram showing a correlation between a toner cohesion degree and an inter-toner adhesive force in the inter-powder adhesive force measuring apparatus and the inter-powder adhesive force measuring method according to one embodiment of the present invention.

FIG. 13 is a diagram showing a correlation between a toner adhesion amount and a thickness in a powder adhesion measurement apparatus and a powder adhesion measurement method according to an embodiment of the present invention.

FIG. 14 is a diagram showing a correlation (change in toner charge amount) between transfer dust and toner adhesion in the apparatus for measuring adhesion between powders and the method for measuring adhesion between powders in one embodiment of the present invention.

FIG. 15 is a diagram showing a correlation (change in toner agglomeration degree) between transfer dust and toner adhesion in a powder adhesion measurement device and a powder adhesion measurement method according to one embodiment of the present invention.

FIG. 16 is a diagram showing a correlation between a toner agglomeration degree and a parameter α in a powder adhesion measurement apparatus and a powder adhesion measurement method according to an embodiment of the present invention.

FIG. 17 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 measurement cell 2 sample substrate 2a sample surface 3 receiving substrate 3a attachment surface 5 centrifugal separator 6 rotor 41 CPU 48 image processing means 49 scanner

Claims (12)

[Claims] 1. A sample substrate having a sample surface on which a powder layer formed by laminating a plurality of powder layers is provided, a receiving substrate having an adhesion surface for adhering powder separated from the powder layer, and A centrifugal separator having a measurement cell including a spacer provided between the sample surface and the adhesion surface, and a rotor for rotating the measurement cell; and an image of the powder adhered to the adhesion surface. Image acquisition means to acquire, and analyze the image of the powder acquired by the image acquisition means,
Image processing means for determining the number of powders adhering on the receiving substrate, and the projected area of the powders on the receiving substrate, and the powder adhering to the adhering surface determined by the image processing means An independent state determining means for determining the number and projected area of the powders that can take a state in which individual powders independently adhere to the receiving substrate without adhering to each other, from the relationship between the number and the projected area; and the centrifugation. From the relationship between the rotor speed of the apparatus and the projected area of the powder attached to the receiving substrate, a rotor speed determining means for determining the rotor speed at which each powder becomes an independent state; From the average weight of the powder calculated from the average particle diameter and specific gravity of the powder and the number of rotations of the rotor, centrifugation required to separate the powder from the outermost surface of the powder layer formed on the sample surface Adhesive force deriving means for obtaining force; powder on the sample surface Using the amount of adhesion per unit area of the body layer, the average charge amount of the powder, and the value of the centrifugal force required to separate the powder from the outermost surface of the powder layer, the non-electrostatic A non-electrostatic adhesive force calculating means for calculating an adhesive force, the adhesive force measuring device between powders. 2. The method according to claim 1, wherein the non-electrostatic adhesion force calculating means calculates an adhesion amount M (mg / cm) of the powder layer on the sample surface per unit area.
² ) The average charge amount of the powder is Q (μC / g), and the centrifugal force required to separate the powder from the outermost surface of the powder layer is Fs.
(N) When the constant is A, the centrifugal force Fs is obtained for a plurality of samples having different amounts of adhesion M and / or charge Q, and the following relational expression Ft = Fs−A × (Q / M) ² The non-electrostatic adhesive force Ft (N) between powders is calculated from the following formula: 3. A sample substrate having a sample surface on which a powder layer formed by laminating a plurality of powder layers is provided, a receiving substrate having an adhering surface for adhering powder separated from the powder layer, and A centrifugal separator having a measurement cell including a spacer provided between the sample surface and the adhesion surface, and a rotor for rotating the measurement cell; and an image of the powder adhered to the adhesion surface. Image acquisition means to acquire, and analyze the image of the powder acquired by the image acquisition means,
Image processing means for determining the number of powders adhering on the receiving substrate, and the projected area of the powders on the receiving substrate, and the powder adhering to the adhering surface determined by the image processing means An independent state determining means for determining the number and projected area of the powders that can take a state in which individual powders independently adhere to the receiving substrate without adhering to each other, from the relationship between the number and the projected area; and the centrifugation. From the relationship between the rotor speed of the apparatus and the projected area of the powder attached to the receiving substrate, a rotor speed determining means for determining the rotor speed at which each powder becomes an independent state; From the average weight of the powder calculated from the average particle diameter and specific gravity of the powder and the number of rotations of the rotor, centrifugation required to separate the powder from the outermost surface of the powder layer formed on the sample surface Adhesive force deriving means for obtaining force; powder on the sample surface Calculate the non-electrostatic adhesion between powders using the thickness of the body layer, the average amount of charge of the powder, and the centrifugal force required to separate the powder from the outermost surface of the powder layer And a non-electrostatic adhesive force calculating means. 4. The non-electrostatic adhesive force calculating means sets the thickness of the powder layer on the sample surface to H (μm),
(ΜC / g), when the centrifugal force required to separate the powder from the outermost surface of the powder layer is Fs (N), and the constant is B, a plurality of samples having different thicknesses H and / or different charge amounts Q are provided. A non-electrostatic adhesion force Ft (N) between the powders is calculated from the following relational expression: Ft = Fs−B × (Q / H) ² Item 3. An apparatus for measuring adhesion between powders according to Item 3. 5. A sample substrate having a sample surface on which a powder layer formed by laminating a plurality of powder layers with a thickness of at least a plurality of layers is formed, and a receiver having an adhering surface for adhering the powder separated from the powder layer. A substrate creation step of creating a substrate, the sample substrate, the receiving substrate, and a spacer provided between the sample surface and the attachment surface; a measurement cell creation step of creating a measurement cell including: A measuring cell setting step of setting the measuring cell in the rotor of a centrifugal separator having a rotor for rotating the measuring cell; and a surface of the powder layer formed on the sample surface by centrifugal force caused by rotation of the rotor. A centrifugal separation step of separating and adhering the powder to the adhering surface; a receiving substrate obtaining step of taking out the measuring cell from the rotor to obtain the receiving substrate; and an image of the powder adhering to the adhering surface. And get By analyzing the obtained image of the powder, a powder number deriving step of obtaining the number of powders adhered on the receiving substrate, and analyzing the image of the powder, A projection area deriving step of obtaining a projection area on the receiving substrate, and from a relationship between the number of powder particles adhering to the adhesion surface and the projection area,
An independent state determination step for determining the number and projected area of the powders that can take a state in which the individual powders independently adhere to the receiving substrate without adhering to each other; and the rotation speed of the rotor and the adhesion to the receiving substrate. A rotor rotation speed determining step of determining a rotor rotation speed at which the individual powders are in an independent state from the relationship of the projected area of the powder, and an average weight of the powder calculated from an average particle diameter and a specific gravity of the powder. And a rotation speed of the rotor, an adhesion force deriving step of determining a centrifugal force required to separate powder from the outermost surface of the powder layer formed on the sample surface, and a powder layer on the sample surface. Non-electrostatic adhesion between powders using the adhesion amount per unit area, the average charge amount of the powder, and the value of centrifugal force required to separate the powder from the outermost surface of the powder layer A non-electrostatic adhesive force calculating step of calculating the adhesive force between the powders. Constant method. 6. In the non-electrostatic adhesion force calculating step, the adhesion amount M (mg) of the powder layer on the sample surface per unit area.
/ Cm ² ), the average charge amount of the powder is Q (μC / g), and the centrifugal force required to separate the powder from the outermost surface of the powder layer is Fs.
(N) When the constant is A, the centrifugal force Fs is obtained for a plurality of samples having different amounts of adhesion M and / or charge Q, and the following relational expression Ft = Fs−A × (Q / M) ² 6. The method for measuring the adhesion between powders according to claim 5, wherein the non-electrostatic adhesion Ft (N) between the powders is calculated from the following formulas. 7. A sample substrate having a sample surface on which a powder layer formed by laminating a plurality of powder layers having a thickness of at least a plurality of layers, and a receiver having an adhering surface for adhering the powder separated from the powder layer. A substrate creation step of creating a substrate, the sample substrate, the receiving substrate, and a spacer provided between the sample surface and the attachment surface; a measurement cell creation step of creating a measurement cell including: A measuring cell setting step of setting the measuring cell in the rotor of a centrifugal separator having a rotor for rotating the measuring cell; and a surface of the powder layer formed on the sample surface by centrifugal force caused by rotation of the rotor. A centrifugal separation step of separating and adhering the powder to the adhering surface; a receiving substrate obtaining step of taking out the measuring cell from the rotor to obtain the receiving substrate; and an image of the powder adhering to the adhering surface. And get By analyzing the obtained image of the powder, a powder number deriving step of obtaining the number of powders adhered on the receiving substrate, and analyzing the image of the powder, A projection area deriving step of obtaining a projection area on the receiving substrate, and from a relationship between the number of powder particles adhering to the adhesion surface and the projection area,
An independent state determination step for determining the number and projected area of the powders that can take a state in which the individual powders independently adhere to the receiving substrate without adhering to each other; and the rotation speed of the rotor and the adhesion to the receiving substrate. A rotor rotation speed determining step of determining a rotor rotation speed at which the individual powders are in an independent state from the relationship of the projected area of the powder, and an average weight of the powder calculated from an average particle diameter and a specific gravity of the powder. And a rotation speed of the rotor, an adhesion force deriving step of determining a centrifugal force required to separate powder from the outermost surface of the powder layer formed on the sample surface, and a powder layer on the sample surface. Using the thickness of the powder, the average charge amount of the powder, and the value of the centrifugal force required to separate the powder from the outermost surface of the powder layer, the non-electrostatic adhesion between the powders is calculated. A method for measuring the adhesion between powders, comprising: an electrostatic adhesion calculation step. 8. In the non-electrostatic adhesion calculation step, the thickness of the powder layer on the sample surface is H (μm), the average charge amount of the powder Q (μC / g), When the centrifugal force required to separate the powder from the surface is Fs (N) and the constant is B, the centrifugal force Fs is obtained for a plurality of samples having different thicknesses H and / or different charge amounts Q. The non-electrostatic adhesive force Ft (N) between the powders is calculated from the relational expression Ft = Fs−B × (Q / H) ^2. Method. 9. An electrostatic latent image carrier for carrying an electrostatic latent image, forming means for forming an electrostatic latent image on said electrostatic latent image carrier in accordance with image information, and said electrostatic latent image carrier. A developing means for supplying toner to the image to visualize the toner image, and a toner image carrier for carrying the visualized toner image, wherein the toner image carrier is measured in advance by the powder-to-powder adhesion measuring method according to claim 6. The non-electrostatic adhesion between toner particles forming a toner image on the toner image carrier is Ft (N), the average value of the toner charge is Q (μC / g), An image forming apparatus characterized by satisfying the following relational expression M ⁴ × Q ² / (Ft × 10 ⁹ ) ≦ 60, where M is the maximum toner adhesion amount (mg / cm ² ). . 10. A non-electrostatic adhesive force Ft (N) between toner particles of a toner image formed on the toner image carrier,
The image forming apparatus according to claim 9, wherein a toner having a range of 5 × 10 ⁻⁹ N to 3 × 10 ⁻⁸ N is used. 11. A method of irradiating at least a uniformly charged electrostatic latent image carrier with light according to image information to form an electrostatic latent image on the electrostatic latent image carrier and carry the electrostatic latent image on the electrostatic latent image carrier. A latent image forming step, and a developing step of supplying toner to the electrostatic latent image to visualize the electrostatic latent image, and carrying the visualized toner image on a toner image carrier, wherein the developing step includes: The non-electrostatic adhesive force between toner particles forming a toner image on the toner image carrier, which is measured in advance by the method for measuring an adhesive force between powders described in Item 6, is Ft (N), and the average value of the toner charge amount is Q (μC /
g), assuming that the maximum toner adhesion amount on the toner image carrier is M (mg / cm ² ), the following relational expression M ⁴ × Q ² / (Ft × 10 ⁹ ) ≦ 60 is satisfied. Characteristic image forming method. 12. A non-electrostatic adhesive force Ft (N) between toner particles of a toner image formed on the toner image carrier,
The image forming method according to claim 11, wherein the thickness is in a range of 5 × 10 ⁻⁹ N to 3 × 10 ⁻⁸ N.