JPH09325597A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the property of applying a charge to toner in the abut/nip region of a developing blade and a developing sleeve and to execute a stable developing process by specifying the relation between the 10-point average roughness of the surface of the developing sleeve an the weight average grain diameter of a one-component developer. SOLUTION: The applied developing sleeve 2 is worked so that the weight average grain diameter D of the one-component developer T used for forming an image and the 10-point average roughness Rz of the surface of the developing sleeve 2 become Rz>=D/2. Further, it is preferable that the developing sleeve 2 has a rugged surface. As a raggedness in this case, the sleeve 2 is worked so that the average interval Sm between projecting and recessed parts is <=20D when the average inclined angle θa of the projecting/recessed parts is <=45 deg. and <=10D when as the average inclined angle θa, 45 deg.<θa<90 deg. is obtained. Thus, when globular toner having high flowability and fine grain toner whose weight average grain diameter is <=5μm are used as well, the stable developing process is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic method used in, for example, a printer or a copying machine, and more particularly to an image forming apparatus using a non-magnetic one-component developer.

[0002]

2. Description of the Related Art A developing device using an electrophotographic method has a slightly different structure depending on the type of developer (hereinafter, also referred to as toner) used.
When a magnetic one-component toner is used, a magnet is only required in the developer carrier (hereinafter also referred to as a developing sleeve), and even when the magnetic one-component toner is used, a non-magnetic one-component developer ( Hereinafter, even when a non-magnetic one-component toner is used), the configuration is almost the same. Therefore, FIG. 6 shows a conventional example of a developing device when a non-magnetic one-component toner is used.

As shown in FIG. 6, conventionally, a developing device 101 of this type is provided at a photosensitive member 100, which is an image bearing member rotating in the X direction in the figure, and at a position facing the photosensitive member 100. A developing sleeve 102 that forms a developing area at a position facing the photoconductor 100 while rotating in the Y direction in the drawing, and a developer supply that is supplied to the developing sleeve 102 by rotating the non-magnetic toner T in the Z direction in the drawing. A supply roller 104 that is a means, a developing blade 103 that is a developer regulating means that regulates a coating amount and a charging amount of the toner T on the developing sleeve 102, a hopper 106 that stores the toner T, and a hopper 106 from the lower side of the developing sleeve 102. A blow-out prevention sheet 105 for preventing the toner T in the inside from scattering.

When a magnetic toner is used as the developer, a magnet is required inside the developing sleeve 102, but in this case, the supply roller 104 is often unnecessary. Further, in order to prevent the toner T from scattering, instead of the blow-out prevention sheet 105, the toner is collected in the same area,
Alternatively, a magnetic member can be arranged to prevent toner scattering.

On the other hand, in the developing device 101, a developing bias is applied to the developing sleeve 102 from a power source (not shown) to form a developing electric field in the developing area, which electrostatically charges the surface of the photoconductor 100 by means (not shown). Form a latent image. The electrostatic latent image is developed and visualized by the toner T carried on the surface of the developing sleeve 102 by the mirror image force. The residual toner T ′ remaining on the surface of the developing sleeve 102 during the development is collected in the hopper 106 via the supply roller 104.

The developing device 101 shown in FIG. 6 basically uses an insulating non-magnetic one-component toner,
Further, the toner T is supplied from the supply roller 104 to the developing sleeve 102 by the supply roller 104 and the developing sleeve 1.
This is performed by the mirror image force generated by the toner T being frictionally charged in the rubbing area with 02. On the contrary,
In the case of magnetic toner, as is well known, a magnetic force is applied to the toner supply and conveyance. The adjustment of the supply amount of the toner T to the developing sleeve 102 is performed by the developing sleeve 102 and the supply roller 1.
It is performed with a peripheral speed difference of 04. Developing device 10 of the above type
In No. 1, since the magnetic force is not required to convey the toner T, the toner is made non-magnetic, which is particularly advantageous for color image formation.

However, in the above-described conventional example, a problem may occur in the contact nip region between the developing blade 103 and the developing sleeve 102 depending on the physical properties of the toner used, and a large amount of uncharged toner is generated on the surface of the developing sleeve 102, resulting in magnetic properties. In the case of a toner, a decrease in density, an increase in reversal fog, etc. occur, and in the case of a non-magnetic toner, in addition to the above problems, an increase in toner scattering and a drop of uncharged toner from the surface of the developing sleeve 102 occur. In any case, it was difficult to form a good image. More specifically,
Studies by the present inventors have revealed that these tendencies become remarkable as the porosity of the toner used decreases.

Here, a method for measuring the porosity of the toner will be described. First, using a container attached to a powder tester manufactured by Hosokawa Micron Co., Ltd., the loose apparent density of the developer is measured according to the procedure in the instruction manual of the powder tester. Next, Shimadzu's Accupic 13
30 is used to measure the true density of the toner. As a measuring method, while tapping very lightly, a 10 cm ³ measuring cell container was filled with toner up to about 8 minutes, and the measuring cell was placed in a vacuum dryer set at 40 ° C. for 24 hours. After drying, weigh it, insert it into the main body, purge the helium gas with a filling pressure of 134.45 kPa 10 times, and then measure 5 times with a filling pressure of 134.45 kPa and an equilibrium pressure of 0.0345 kPa. To obtain the true density. From the loose apparent density and true density of the toner obtained as described above, the porosity of the toner is calculated by the following formula. Porosity = 1-Loose apparent density / true density

According to the research conducted by the present inventors, the above problem tends to be remarkable when the toner having the porosity calculated as described above is about 60% or less. This porosity tends to decrease as the particle size of the toner decreases, the shape of the toner becomes closer to a sphere, or the fluidity of the toner increases. In particular, it has been found that when the spherical toner is subjected to the external addition treatment to obtain high fluidity, the porosity is less than 60%, and the above-mentioned problems occur remarkably. That is, it becomes possible to obtain good transferability with the spheroidization of the toner, and if an external additive is added to the toner to improve the fluidity, the roughness and the scattering are reduced, and the transferability is improved. It should be possible to obtain good image quality together with the improvement,
In the conventional example as described above, the above problems occur due to the following reasons.

When the porosity of the toner becomes low, the reason why the above-mentioned problem such as the generation of a large amount of uncharged toner is likely to occur is in the contact nip region between the developing blade 103 and the developing sleeve 102. The behavior of the toner is greatly related. This will be described below with reference to FIGS. 7, 8 and 9 in addition to FIG. 6.
First, the case of the spherical toner in which the above-mentioned phenomenon remarkably occurs will be described as an example. The spherical toner having a low porosity obtains a charge amount by frictional charging with the surface of the developing sleeve 102 as a result of the toner T being rotated in the vicinity of the contact area between the developing sleeve 102 and the supply roller 104.
Due to the resulting mirror power, a part of the toner T supplied by the supply roller 104 and having the charge amount as described above is carried on the surface of the developing sleeve 102, and as shown in FIG. And is conveyed to the contact nip area N between the surface of the developing sleeve 102 and the surface of the developing sleeve 102.

Since the toner T has a low porosity, it is carried and conveyed in a relatively dense state on the surface of the developing sleeve 102 as shown in FIG. When the first layer of the toner coat layer on the surface of the developing sleeve 102 becomes dense, in addition to the reflection force generated by the frictional charging with the surface of the developing sleeve 102, the frictional force from the first layer of the toner coat layer causes the supply roller 104.
The toner T, which has been supplied by and not supplied to the first layer, is also conveyed relatively densely as the second layer.
For the same reason, the third layer, the fourth layer, ...
Multiple layers are stacked on the layers, and a toner coat layer having a multilayer structure is formed on the developing sleeve 102. Ideally, all of the toners T in this toner coat layer should have the same amount of charge, but in reality, they have a charge amount distribution. Reverse toner and uncharged toner are also present in some proportion.

In the contact nip region N shown in FIG. 7, the toner coat layer and the toner T charge amount distribution are optimized. This process will be described in detail below. In FIG. 7, the toner coated on the second layer is shown as T2. Note that FIG. 7 shows a case where the multilayer toner coat is restricted to three layers in the nip N. In the example shown in FIG. 7, since the first toner coat layer is dense in the nip N, the force F1 acts on the toner T2 in the same direction as the rotation direction Y of the developing sleeve 102. On the other hand, the frictional force F2 from the developing blade 103 acts on the toner of the third layer. By the action of F1 and F2, 2
A force F3 acts between the toner T2 of the layer and the toner T3 of the third layer. The force of F3 causes the toners of the second layer and the third layer to rotate, so that the toners of the second layer and the third layer both come into contact with the developing blade 103.
In the nip N, since the contact pressure acts on the developing blade 103, the toner T of the first layer is transferred to the developing sleeve 102.
The toner T2 of the second layer and the third layer is frictionally charged with the surface of the developing blade 103, and the distribution of the charge amount in the toner coat layer is optimized. The amount of uncharged toner is greatly reduced, and good image formation is possible. That is, even with a spherical toner having a low porosity, the above-mentioned problems do not occur under the condition that the chargeability of the toner T is maintained.

On the other hand, if the chargeability of the toner T is lowered, the following problems will occur. That is, the charging property of the toner T is lowered, and the toner T and the developing sleeve 1 near the developing sleeve 102 and the supply roller 104 approach each other.
02 When the triboelectricity with the surface is lowered, the toner T having a sufficient amount of charge is reduced, and the toner coat of the first layer becomes sparse as shown in FIG. As a result, the force F1 in FIG. 7 is greatly reduced to become F1 ′ shown in FIG. For this reason, the toner coat layer T2 as the second layer becomes sparse in combination with the insufficient charge amount of the toner T. Similarly, the third layer, the fourth layer, ... Are also sparse. However, since there is also a dense toner coat area partially,
The number of toner coat layers in the nip N is three as in the case of FIG. Under the normal contact pressure of the developing blade 103, the number of toner coat layers in the nip N does not change even if the toner coat layer becomes sparse. That is, since the number of toner coat layers in the nip N does not change, sparse toner T in the toner coat layer means a decrease in toner density in the nip N. This decrease in toner density results in a decrease in the frictional force between the toners, and as a result, the toner T2 and the third toner
Rotation between the layer toner T is less likely to occur. For this reason, the opportunity to apply the charge to the toner T2 is lost, and the charge amount distribution in the toner coat layer cannot be optimized. And
If the charge amount distribution in the toner coat layer cannot be optimized, the toner coat layer passing through the nip N is
The amount of reverse toner and uncharged toner increases, and the above-mentioned problems occur.

There are several cases in which the chargeability of the toner T is lowered, and three typical cases will be described below. The first is when the chargeability of the toner itself is low from the beginning. The spherical toner, which has good slipperiness of the toner itself, has a strong tendency that the chargeability of the toner itself becomes low because the frictional force decreases. Further, for the purpose of improving the durability of the developing device, there is a case where the toner subjected to the external additive treatment for intentionally reducing the charge amount is used in order to prevent the toner itself from being charged up due to the durability. That is, when the toner is charged up, the ghost is worsened, and the image is rugged and scattered, and the developability is deteriorated. Secondly, in the case of the non-magnetic one-component developing device as in the case of the conventional example shown in FIG. 6, toner deterioration due to durability is likely to occur and the chargeability of the toner may decrease. The third is the developing sleeve 1 in which the external additive and fine powder toner externally added to the toner are charged up.
02 New toner and developing sleeve 102 adhered to the surface
In some cases, the triboelectricity with the surface is obstructed, and the chargeability of the toner is reduced.

As described above, when the toner having a low porosity is used, if the chargeability of the toner is lowered,
It has been found that in the conventional developing device, the amount of reversal toner, especially uncharged toner, increases to cause the above-mentioned various problems. As described above, the porosity tends to be lower as the particle size of the toner is smaller, the shape of the toner is closer to a sphere, or the fluidity of the toner is higher. In particular, it has been found that when the spherical toner is subjected to an external addition treatment so as to obtain high fluidity, the porosity is less than 60%, and the problems particularly occur.

That is, in the conventional apparatus, when a toner having a high porosity such as a toner (toner having a weight average particle diameter of about 7 μm or more) produced by a conventionally used pulverization method is used, it will be described below. As described above, it is difficult to cause a problem because the margin for the above problems becomes wide, but in order to improve transferability and obtain a high-quality image, a highly fluid spherical toner is used, and further high-definition toner is used. When a fine particle toner having a weight average particle size of 5 μm or less is used for the purpose of imaging, the above-mentioned various problems become remarkable, and it is difficult to use these toners. That is, when the toner produced by the pulverization method is used in the conventional apparatus, the frictional force of the toner itself is high even if the toner density in the nip N is low, as shown schematically in FIG. The frictional force F1 ″ on the surface of the developing sleeve 102 increases, and further,
A frictional force acts between the toners of the second layer and the third layer, so that a force F3 ′ is generated between the toner T2 ′ shown in FIG. 9 and the toner of the third layer to cause rotation. As a result, compared to the case where the toner having a low porosity is used, the developing blade 1
03, the charge imparting property to the toner becomes high, and the above-mentioned problems hardly occur. In the above description, the case where the non-magnetic one-component toner is used has been described. However, such a problem basically occurs also in the magnetic one-component toner. Although there were differences, similar problems arose.

[0017]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to improve the charge imparting property to toner in the contact nip region between the developing blade and the developing sleeve in the above-described conventional developing device. By providing a developing system capable of performing a stable developing process even when a highly fluid spherical toner or a fine particle toner having a weight average particle diameter of 5 μm or less is used as a developer, toner scattering, An object of the present invention is to provide an image forming apparatus capable of forming a high-quality image without causing problems such as toner dropping from the developing sleeve, reduction in image density, and reverse fog.
Another object of the present invention is to provide an image forming apparatus having a long-life developing device having high durability capable of maintaining the above object for a long period of time.

[0018]

The above object is achieved by the present invention described below. That is, the present invention includes (i) an image carrier on which an electrostatic latent image is formed, (ii) a developer carrier for carrying a one-component developer, and a one-component system on the surface of the developer carrier. An electrostatic latent image on the image bearing member in a developing area having at least a developer amount regulating means for regulating the developer amount, and the image bearing member and the developer bearing member facing each other. In an image forming apparatus equipped with a developing device for developing with a one-component developer, the 10-point average roughness of the surface of the developer carrying member is R.
_{Letting Z} be D and the weight average particle diameter of the one-component developer be D, the 10-point average roughness R _Z and the weight average particle diameter D satisfy the relationship of R _Z ≧ D / 2. An image forming apparatus characterized by the above.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. First, an example of an image forming apparatus according to the present invention will be described with reference to the drawings. In the example described below, for example, the electrophotographic image forming apparatus shown in FIG. 5 is embodied, but the present invention is not limited to this. First, an outline of an electrophotographic image forming apparatus using the image forming apparatus of the present invention shown in FIG. 5 will be described. The electrophotographic image forming apparatus shown in FIG. 5 is provided with a photosensitive drum 0, which is an image carrier, rotatably.
Is uniformly charged by a primary charger 15, and an information signal is exposed to this by a light emitting element 16 such as a laser to form an electrostatic latent image, and then the electrostatic latent image is formed into a one-component system. A developing device 1 having a developer visualizes the image. Then, the visualized developed image is transferred to the transfer paper 18 by the transfer charger 17, and the developed image is fixed by the fixing device 19 to form a permanent image. The developer remaining on the photosensitive drum 0 after the image is formed is removed by the cleaning device 20.

FIG. 1 is an enlarged view of an example of the developing device portion of the image forming apparatus of the present invention, and the developing process will be described in more detail based on this. In FIG. 1, the photosensitive drum 0 rotates in the direction of arrow X at a rotation speed V _X , and an electrostatic latent image is formed on the surface of the photosensitive drum 0 by image exposure by means not shown. In the figure, reference numeral 1 denotes a non-magnetic one-component developing device. The non-magnetic one-component developing device 1 includes a developing sleeve 2 which rotates at a rotation speed V _Y in the arrow Y direction, a developing blade 3 and an arrow Z direction. A supply roller 4, which is a rotating developer supply unit, a blowout prevention sheet 7, and a hopper 8 containing a non-magnetic one-component developer T are provided. At this time, the rotational speeds of the photosensitive drum 0 and the developing sleeve 2 have a relationship of V _Y > V _X. Further, the developing sleeve 2 is connected to a developing bias power source 9 capable of generating a superposed voltage of a negative DC voltage 6 and an AC voltage 5, while the photosensitive drum 0 is grounded.

Next, the one-component type developer used in the image forming apparatus of the present invention as described above will be described. As described above, the object of the present invention is to improve the charge imparting property to the one-component developer in the contact nip region between the developing blade and the developing sleeve in the developing device having the conventional structure, To provide a developing system capable of performing a stable developing process even when a highly fluid spherical toner or a fine particle toner having a weight average particle diameter of 5 μm or less is used as a constituent material of a component type developer. is there. First, as the one-component developer T used in the present invention, it is preferable to use a non-magnetic one-component developer having substantially spherical toner particles, mainly for the purpose of improving transferability. In particular, those having a weight average particle diameter of 3 to 10 μm are preferable, and SF-of the spherical coefficient showing the spherical degree of the toner is further used.
It is preferable to use a one-component developer in which 1 is 100 to 140 and SF-2 is 100 to 120. SF-
When 1 exceeds 140, the toner particles have an irregular shape, and when SF-2 exceeds 120, the surface irregularities become remarkable, and in any case, it is difficult to obtain good transferability. Become.

Here, the spherical degree of the toner will be described. The spherical degree of the toner is determined by the shape factor SF− of the toner particles.
1 and SF-2 can be used. In the present invention, the shape factors SF-1 and SF-2 of the toner particles are the scanning electron microscope FE-SEM manufactured by Hitachi, Ltd.
(S-800) was used to randomly sample 100 toner images, and the image information was introduced into an image analysis device (Luzex3) manufactured by Nikole Co. through an interface for analysis, and calculated by the following formula. The value obtained is defined. SF-1 = {(MXLNG) ² / AREA} × (π
/ 4) × 100 SF-2 = {(PERI) ² / AREA} × (1 / 4π)
× 100 (MXLNG: Absolute maximum length, AREA: Toner projected area, PERI: Perimeter) The shape factor SF-1 of the toner particles shows a sphere degree, and if it is larger than 140, the shape gradually becomes irregular from a sphere. Further, SF-2 indicates the degree of unevenness, and when it is larger than 120, the unevenness becomes remarkable on the surface of the toner particles.

The weight average particle diameter of the toner can be measured by various methods, but in the present invention, it was measured using a Coulter counter multisizer. That is, a Coulter counter, Multisizer II type (manufactured by Coulter) is used as a measuring device, and an interface (manufactured by Nikkaki) and CX-1 for outputting number distribution and volume distribution.
A personal computer (Canon) is connected, and electrolyte is 1% NaC using special grade or grade 1 sodium chloride.
Prepare an aqueous solution. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant in 100 to 150 ml of the electrolytic aqueous solution in an amount of 0.1 to 5 m.
1 and further add 2 to 20 mg of the measurement sample. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and a 100 μm aperture is used as an aperture when measuring the toner particle size with the Multisizer II type Coulter Counter. taking measurement. The volume and number of toner were measured to calculate the volume distribution and number distribution. Then, the weight-based weight average particle diameter obtained from the volume distribution is obtained.

Conventionally, in the case of a developer containing non-sphericalized toner particles prepared by a pulverization method, the transfer efficiency is in the range of 85 to less than 95%, which is approximately 85 to 90.
It was often less than%. If the transfer efficiency is less than 90%, the cleaning device 2 is used to accommodate the residual transfer developer.
It was necessary to make 0 sufficiently large, and if this was not possible, the life of the device would be limited. The higher the transfer efficiency, the more the transfer residual developer decreases, and as a result, it becomes possible to reduce the volume for accommodating the transfer residual developer of the cleaning device 20 shown in FIG. It is possible to reduce the size and cost of the forming apparatus.

Therefore, the present invention aims to provide an image forming apparatus capable of achieving a transfer efficiency of a one-component developer of preferably 90% or more, more preferably 95% or more. That is, when the transfer efficiency is 90% or more, it is possible to solve the above-mentioned problems and reduce the size and cost of the apparatus. In the present invention, the shape factor SF-1 is 100 to 120 and SF-2 is 100
By using the one-component type developer having substantially spherical toner particles within the range of 140 to 140, the transfer efficiency can be improved and the transfer efficiency can be 95% or more. As described above, in the range where the transfer efficiency is 95% or more, even if the cleaning device 20 is removed, the influence of the residual transfer developer on the image exposure 16 is negligibly small, and therefore the cleaning device 20 itself is removed. It also becomes possible. As a result, it is possible to further reduce the size and cost of the image forming apparatus.

As the spherical toner particles having the above-mentioned physical properties, when the toner is manufactured, a part or the whole thereof is formed by a polymerization method, whereby more spherical toner particles can be obtained. In particular, in the polymerization method, since it can be present as pre-toner (monomer composition) particles in the dispersion medium and a necessary portion can be generated by the polymerization reaction, toner particles having considerably smoothed surface properties can be obtained. .

Further, in the present invention, it is preferable that the spherical toner particles have a low melting point for the purpose of facilitating the production of the spherical toner particles and saving energy. Therefore, it is preferable that the spherical toner particles have a core / shell structure, a low softening point substance is used as a main component constituting the core portion, and the shell portion is formed by a polymerization method. When the toner particles have a core / shell structure, it is possible to obtain the action of imparting blocking resistance without impairing the excellent fixing property of the toner. Furthermore, with a core / shell structure,
It is preferable to polymerize only the shell portion because it is possible to easily remove the residual monomer in the post-treatment step after the polymerization step, as compared with the bulk toner particles having no core.

AS having a low softening point substance as a main component constituting the core portion of the toner particles used in the present invention, AS
It is preferable to use a compound whose main component maximum peak value measured according to TM D3418-8 is 40 to 90 ° C. When the maximum peak is less than 40 ° C., the self-aggregating force of the low softening point substance becomes weak and the high temperature offset property becomes weak, which is not preferable. On the other hand, if the maximum peak exceeds 90 ° C., the fixing temperature becomes high, which is not preferable. Further, when the toner particles are obtained by the direct polymerization method, since the granulation / polymerization is carried out in an aqueous system, when the temperature of the maximum peak value is high, the low softening point substance mainly precipitates during granulation, which causes a problem. It is not preferable because it hinders the turbid system.

In the present invention, the temperature measurement of the above-mentioned maximum peak value was carried out using DSC-7 manufactured by Perkin Elmer. As the measuring method, the melting points of indium and zinc were used to correct the temperature of the device detection portion, and the heat of fusion of indium was used to correct the amount of heat. Then, an aluminum pan was used for the sample and an empty pan was set for the control, and the temperature rising rate was 10 ° C./min. Was measured.

As the low softening point substance used when forming the core portion of the toner particles preferably used in the present invention,
Specific examples thereof include paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax and derivatives thereof, or graft / block compounds thereof. These low softening point substances are incorporated into the toner particles.
It is preferable to add about 30 to 30% by weight. Addition of less than 5% by weight imposes a burden on the removal of the residual monomer in the post-treatment step after polymerization as described above, while, if more than 30% by weight, it also occurs during granulation in the production by the polymerization method. Toner particles are likely to coalesce with each other, and particles having a wide particle size distribution are easily generated.

Further, as the toner used in the present invention, by coating the surface of the spherical toner particles as described above with an external additive, a high fluidity is imparted to the toner and the influence of the photoconductor charging member is exerted. It is desirable to have a structure that allows it to escape to a certain external additive. In that sense, the coverage of the external additive on the surface of the toner particles is preferably 5 to
It is desirable to set it to 99%, more preferably 10 to 99%. The external additive coverage on the surface of the toner particles is determined by the scanning electron microscope FR-SEM (S-80 manufactured by Hitachi, Ltd.).
100 toner images are randomly sampled using 0), and the image information is introduced into an image analyzer (Luzex3) manufactured by Nikole Co. through an interface and calculated. In the image information, since the surface area of the toner particles and the external additive portion are different in lightness, the area S _{G of the} external additive portion is binarized.
And the area of the toner particle portion (including the area of the external additive portion) S
_It is divided into _T and calculated by the following formula.

[0032]

[Equation 1]

The external additive preferably used in the present invention has a particle diameter of 1/10 or less of the weight average particle diameter D of the toner particles from the viewpoint of durability when added to the toner particles. preferable. The particle size at this time means the average particle size obtained by observing the surface of the toner particles with an electron microscope. As the external additive, for example, aluminum oxide,
Titanium oxide, strontium titanate, cerium oxide,
Metal oxides such as magnesium oxide, chromium oxide, tin oxide and zinc oxide, nitrides such as silicon nitride, carbides such as silicon carbide, metal salts such as calcium sulfate, barium sulfate and calcium carbonate, zinc stearate and calcium stearate, etc. The fatty acid metal salts, carbon black, silica and the like can be used.

These external additives are preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the toner particles. Moreover, these external additives may be used alone or in combination. Furthermore, it is more preferable to use those that have been respectively subjected to a hydrophobic treatment. If the external additive amount of the external additive is less than 0.01 parts by weight, the fluidity of the one-component developer is deteriorated, and the transfer and development efficiency is reduced. As a result, uneven density of the image or so-called splattering in which the developer splatters around the image portion occurs. On the other hand, when the amount exceeds 10 parts by weight, an excessive amount of the external additive adheres to the photosensitive drum or the developing roller to deteriorate the chargeability of the developer or disturb the image.

When the porosity of the spherical non-magnetic one-component developer T produced as described above is measured, it is about 56 to 60% although it fluctuates slightly depending on the external addition conditions. As described above, when such a toner having a porosity of 60% or less is used, various problems occur in the conventional technique, and it is difficult to form a high-quality image. On the other hand, in the present invention, by using a specific developer carrier having a specific surface roughness described below as the developer carrier of the developing device, various conventional problems can be solved, and It is possible to form a high-quality image even when a toner having a porosity of 60% or less is used.

The developer carrier which characterizes the image forming apparatus of the present invention will be described below. The developer carrying member and the one-component type developer used in the developing device that constitutes the image forming apparatus of the present invention are used for image formation, with the 10-point average roughness of the surface of the developer carrying member being R _Z. When the weight average particle diameter of the one-component type developer is D, the relationship of R _Z ≧ D / 2 is satisfied.

The surface properties of the developer carrying member will be described below. FIG. 2 shows a schematic explanatory view of a cross section near the surface of an example of a developing sleeve as a developer carrying member used in the present invention. Development sleeve 2 used in the present invention
For example, a conventionally used cylindrical sleeve made of aluminum is subjected to surface treatment so as to obtain the following surface properties and finished to have a predetermined surface property (the developing sleeve 2 is, of course, It may be roller-shaped). In the present invention, when the average interval of the irregularities on the surface of the developing sleeve 2 is S and the average inclination angle of the irregularities is θ,
It is preferable to form the uneven surface of the developing sleeve 2 so as to satisfy the following relationship. When θ ≦ 45 °, S ≦ 20D When 45 ° <θ <90 °, S ≦ 10D

This will be briefly described below with reference to FIG. In the present invention, the physical property values representing the above surface properties use the definitions given in JIS B 0601,
For the measurement, a surface roughness tester (SE-30 manufactured by Kosaka Laboratory)
H) was used for the measurement. That is, the 10-point average roughness R _Z , which is a physical property value representing the characteristics of the surface of the developer carrier used in the present invention, was measured by measuring the height of unevenness at 10 points as shown in FIG. (R _Z ) is calculated from the following formula. Here, R _1n is the height of the peak from the highest to the fifth in the reference length L, and R _2n is the depth of the valley from the deepest to the fifth in the reference length L.

[0039]

[Equation 2]

Similarly, for the average spacing S of irregularities, the average length S _m is calculated from the following equation by dividing the reference length L by the number of convex portions between them. Further, the average inclination angle θ of the irregularities is obtained by the following formula from the reference length L and the height of each irregularity, and is defined as the average inclination angle θ _{a of the} irregularities.

[0041]

(Equation 3)

First, in the developing sleeve used in the present invention, the weight average particle diameter of the one-component developer T used for image formation is D.
In the case of, the 10-point average roughness R _Z of the surface of the developing sleeve 2 is R _Z ≧ D / 2, preferably 7D ≧ R _Z ≧ D / 2.
Process so that By doing this,
As shown in FIG. 3, the surface of the developing sleeve 2 can be brought into contact with the second developer coating layer. For example, when using a one-component developer having a weight average particle diameter D = 6 μm, the processing is performed so that the 10-point average roughness R _Z is R _Z ≧ 3 μm or more.

When the 10-point average roughness R _Z is R _Z <D / 2, it becomes difficult for the surface of the developing sleeve 2 to come into contact with the second developer coat layer, and the surface of the developing sleeve 2 becomes The charge imparting property of the second layer to the developer coating layer is significantly reduced. As a result, the proportion of uncharged toner generated in the developer coating layer of the second layer increases, and problems such as dropping of the uncharged toner from the surface of the developing sleeve 2 occur.

On the other hand, when the 10-point average roughness R _Z of the surface of the developing sleeve 2 is set to R _Z > 7D, in the contact nip region N between the developing sleeve 2 and the developing blade 3, the development with respect to the developer is performed. Although the contact area of the surface of the sleeve 2 is increased and the charge imparting property to the developer is improved, the following two problems occur at the same time. First, as the value of the 10-point average roughness R _Z of the surface of the developing sleeve 2 increases, the amount of developer in the developer coat layer also increases. An increase in the amount of developer in the developer coat layer means that at the same time, the number of developer reversal toners in the developer coat layer also increases, and as a result,
Inversion fog increases in the output image. In particular, according to the study by the present inventors, it was confirmed that this tendency becomes remarkable when the 10-point average roughness R _Z becomes large and exceeds R _Z > 7D. Therefore, as described above, it is preferable that the 10-point average roughness R _Z of the surface of the developing sleeve 2 is processed so that 7D ≧ R _Z ≧ D / 2.

The second problem is the average roughness R of 10 points.
_{When Z} exceeds 7D, toner fusion may easily occur on the surface of the developing sleeve 2. When the toner fusion occurs on the surface of the developing sleeve 2, the charge imparting property to the developer on the surface of the developing sleeve 2 deteriorates, and uncharged toner easily occurs. As a result, the problems that have occurred conventionally are likely to occur again. The reason why toner fusion occurs on the surface of the developing sleeve 2 is that when the 10-point average roughness R _Z becomes large, friction between the surface of the developing sleeve 2 and the developer due to an increase in contact area of the surface of the developing sleeve 2 with the developer. It is considered that this is because the charging time increases. That is,
It is considered that the frictional heat generated is increased due to the increase in the frictional charging time, and the developer is fused to the surface of the developing sleeve 2. As described above, since the improvement of the charge imparting property also causes an increase in frictional heat, it can be said that the value of R _Z has a practical upper limit. It is considered that the upper limit varies depending on the softening point of the toner and the like, but according to the study conducted by the present inventors, it is preferable that 7D ≧ R _Z also from this point.

Further, the developing sleeve 2 used in the present invention having the above-mentioned 10-point average roughness preferably has an uneven surface. In this case, the uneven shape has an average of the unevenness described above. The interval S _m is processed so that S _m ≦ 20 D when the average inclination angle θ _a of the unevenness described above is θ _a ≦ 45 °, and S _m ≦ 10 when 45 ° <θ _a <90 °.
It is preferable to process it so that it becomes D. That is, if the convex portion inclination angle θ is gentle, widen the pitch of the irregularities,
When the convex portion inclination angle θ is steep, the pitch of the concave and convex portions is made short. With this configuration, it is possible to increase the probability that the second developer coating layer of the toner carried on the surface of the developing sleeve 2 contacts the surface of the developing sleeve 2.

As described above, when the image forming operation is performed using the developing device 1 in which the developing sleeve 2 having the uneven surface is arranged, the case where the one-component developer having a low porosity is used. However, since the chargeability is not impaired,
Problems that have occurred in the past can be solved. The reason will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of the operation of the developing device in the present invention. First, as a result of the rotation of the one-component developer T in the vicinity of the contact nip region between the developing sleeve 2 and the supply roller 4, the one-component developer T and the developing sleeve 2 are sufficiently frictionally charged, If the one-component developer T is densely coated with the developer (first layer) on the surface of the developing sleeve 2, the developing blade 3 and the developing sleeve 2 can be processed as described in the conventional example with reference to FIG.
In the contact nip region N with the contact surface, the charge imparting to the one-component developer of the second layer and the third layer and the distribution of the charge amount in each developer coat layer are sufficiently optimized. Does not occur.

Further, when the developing sleeve having the uneven surface as exemplified above is used, the conventional example is shown in FIG.
Even if the situation is similar to that described using, no problem will occur. That is, even when a one-component developer having a low electrification property is used, the developer is deteriorated due to durability and the electrification property of the one-component developer is lowered, and the surface of the developing sleeve 2 is further charged. Even if the increased external additive or fine toner particles are fixed and the triboelectric charging property between the developing sleeve 2 and the one-component developer is deteriorated, the problem as in the conventional example does not occur. In the present invention, as shown in FIG. 3, unevenness is provided on the surface of the developing sleeve 2, and the surface is made sparse enough to contact the developer coating layer of the second layer and affect the second layer. It depends. Therefore, even if the first developer coating layer on the surface of the developing sleeve 2 becomes sparse, the conventional problem does not occur. That is, according to the image forming apparatus of the present invention, unlike the conventional case shown in FIG.
As shown in (1), the second developer coating layer T2 has an opportunity to be charged from the surface of the developing sleeve 2. Therefore, in the contact nip region N between the developing blade 3 and the developing sleeve 2,
Charge imparting to the developer coat layers of the second layer and the third layer and optimization of the charge amount distribution in each developer coat layer are performed.

Further, in the present invention, the developing sleeve 2
By roughening the surface of the developer coating layer T2 by roughening the surface of the developer coating layer T2 of the second layer, as shown in FIG.
1 is generated in the same manner as the force F1 generated in the first developer coat layer shown in FIG. 7, a force F3 is generated between the second layer and the third layer.
Occurs, and rotation occurs between the developer coat layer T2 and the developer coat layer of the third layer. As a result, in the nip area N,
The charge imparting property from the developing blade 3 to the developer coating layers of the second layer and the third layer is improved, and the charge amount distribution in the developer coating layer is optimized. As a result, according to the image forming apparatus of the present invention, the amount of the reversal toner and especially the uncharged developer is remarkably reduced as compared with the conventional one, and various problems which have been conventionally caused can be prevented from occurring.

According to the research conducted by the present inventors, the effect of the present invention described above is that the surface roughness R _Z of the developing sleeve 2 is about 3.
If the thickness is at least μm, the above effect will be produced. However, since the amount of the developer coat held on the surface of the developing sleeve 2 increases as R _Z increases, a developer with a low porosity that can achieve the above-mentioned remarkable effects of the present invention is used. In this case, it is preferable to use those processed to have R _Z in the range of 10 μm to 40 μm. On the other hand, the surface unevenness S _m
With respect to the above, if S _m becomes too large, the effect of the present invention is reduced, which is not preferable. For example, the unevenness interval S _m
Is about 150 μm or more, the effect of the present invention is reduced, but within the above range, the effect of the present invention can be maintained.

As described above, according to the image forming apparatus of the present invention, even if a one-component developer having a low porosity is used, it is possible to always give a good charge to the developer. Various problems do not occur unlike the conventional case. As a result, in the present invention, it becomes possible to use a highly fluid spherical toner capable of improving the transferability and the image quality, and it is possible to form a high quality and high quality image. Further, since the image forming apparatus of the present invention can cope with the case where the chargeability of the developer is lowered, the durability of the developing apparatus 1 is improved and the life of the image forming apparatus can be extended. .

As a method of surface treatment for forming the uneven surface of the developing sleeve 2 capable of exhibiting the above-mentioned excellent effects, a known technique can be used, for example, an aluminum developing sleeve. By spraying an arbitrary glass ball in the range of φ30 to 200 μm on the surface of the aluminum base material of No. 2 at a predetermined pressure for a predetermined time from a predetermined distance, the unevenness as shown in FIG. 3 can be formed. .

In the present invention, it is preferable that the powder is formed on the base material of the developing sleeve 2 by fusion bonding or bonding via a bonding layer. That is, as a method of forming irregularities on the surface of the developing sleeve 2, for example, as shown in FIG. 4, conductive metal particles 10 having a weight average particle diameter of about 30 μm are used, and the conductive metal particles are used. Two
By adhering to the surface via the conductive primer layer 11, predetermined irregularities can be easily obtained on the surface of the base material.
When this method is used, as shown in FIG.
Since R _{Z of the} surface of the developing sleeve 2 is determined by the particle size of the conductive metal particles 10, it is possible to finish the surface more accurately than when the unevenness is formed by the method described above with reference to FIG. Become. In particular, as compared with the case described with reference to FIG. 3, the accuracy of the average spacing S _m of irregularities can be improved. Further, in the above description, the conductive metal particles 10 are used as the powder, but instead of this, in order to further improve the charge imparting property to the toner, for example, positive chargeability (negative imparting property) is used. A powder made of a resin such as polyamide resin (nylon) may be used, or a powder obtained by coating the surface of the conductive metal particles with a resin such as polyamide resin (nylon) may be used. Further, it is preferable that these powders used in the present invention are spherical in order to soften the excessive load on the toner.

Further, in the above-mentioned example, the powder such as the conductive metal particles 10 is adhered through the primer layer, but the present invention is not limited to this, and the surface of the developing sleeve 2 is directly melt-adhered by heat. Even in this case, however, the surface of the developing sleeve 2 can be finished to have roughness having predetermined irregularities. Even if unevenness is imparted to the surface of the developing sleeve 2 by any of the above-mentioned methods, the same excellent effect as that described above with reference to FIG. 3 can be obtained. Although the non-magnetic one-component developer is used in the above description, the same effect can be obtained by using the magnetic one-component developer.

[0055]

EXAMPLES The present invention is further described below with reference to examples of the present invention.
This will be described in detail. First, the development three
Buds A to K were prepared. (Manufacture of developing sleeve A) Aluminum developing sleeve
From the position about 180 mm away from the surface of the tube, φ1
Discharge pressure of about 70μm glass beads 3.2kgf / cm
^TwoFor 60 seconds to form irregularities on the surface
By processing, a developing sleeve A was obtained. Obtained developing sleeve
The uneven shape of the surface of A has a surface roughness R_ZIs 35 μm
, The average inclination angle of unevenness θ_aIs 60 °, the average interval S of irregularities_m
Was processed to 47 μm. In the manufacture of developing sleeve A
The blasting conditions used are shown in Table 1, and the obtained developing three
Table 3 shows the physical properties of A.

(Production of Developing Sleeves B to G) Table 1 shows the blast conditions used in the production of the developing sleeve A shown in Table 1.
The developing sleeves B to G were manufactured by making the respective changes as shown in FIG. Table 3 shows the physical properties of the obtained developing sleeves B to G.

[0057]

[Table 1] Table 1: Blasting conditions used in manufacturing the developing sleeve

(Production of Developing Sleeve H) 40 parts by weight of carbon black is mixed with 100 parts by weight of polyamide resin, and this is gently mixed and stirred for about 24 hours to prepare a conductive polyamide resin. Furthermore, with respect to 100 parts by weight of the obtained conductive polyamide resin, the weight average diameter is 5 μm.
25 parts by weight of polyamide particles of about m are mixed to obtain 24
The coating agent H is prepared by gently mixing and stirring for about an hour.
After cleaning the surface of the aluminum developing sleeve tube with ethanol, pulling up speed 4 on this developing sleeve surface.
A curing agent was applied by dip coating at 0 m / min and dried for about 2 to 3 hours. Subsequently, the coating agent H obtained above was subjected to a dip coating at a pulling rate of 10 m / min, and a dry curing treatment was performed at 80 ° C. for 20 minutes to obtain a developing sleeve H.

(Production of Developing Sleeve I) 40 parts by weight of carbon black is mixed with 100 parts by weight of polyamide resin, and this is gently mixed and stirred for about 24 hours to prepare a conductive polyamide resin. Further, with respect to 100 parts by weight of the obtained conductive polyamide resin, a weight average diameter of 30
A coating agent I is prepared by mixing 100 parts by weight of ferrite metal particles of about μm and gently mixing and stirring for about 24 hours. After the surface of the aluminum developing sleeve bare tube was washed with ethanol, the developing sleeve surface was dep-coated with a curing agent at a pulling rate of 40 m / min,
It was dried for about 2 to 3 hours. Subsequently, the coating agent I obtained above was applied by dipping coating at a pulling rate of 20 m / min, and dried and cured at 80 ° C. for 20 minutes to obtain a developing sleeve I.

(Production of developing sleeve J) 100 parts by weight of polyamide resin is mixed with 40 parts by weight of carbon black, and this is gently mixed and stirred for about 24 hours to prepare a conductive polyamide resin. Further, with respect to 100 parts by weight of the obtained conductive polyamide resin, a weight average diameter of 30
A coating agent J is prepared by mixing 100 parts by weight of ferrite metal particles of about μm and gently mixing and stirring for about 24 hours. After the surface of the aluminum developing sleeve bare tube was washed with ethanol, the developing sleeve surface was dep-coated with a curing agent at a pulling rate of 40 m / min,
It was dried for about 2 to 3 hours. Subsequently, the coating agent J obtained above was subjected to dip coating at a pulling rate of 25 m / min, and dried and cured at 80 ° C. for 20 minutes to obtain a developing sleeve J.

(Production of Developing Sleeve K) 40 parts by weight of carbon black is mixed with 100 parts by weight of polyamide resin, and this is gently mixed and stirred for about 24 hours to prepare a conductive polyamide resin. Furthermore, with respect to 100 parts by weight of the obtained conductive polyamide resin, the weight average diameter is 5 μm.
25 parts by weight of polyamide particles of about m are mixed to obtain 24
The coating agent K is prepared by gently mixing and stirring for about an hour.
After cleaning the surface of the aluminum developing sleeve tube with ethanol, pulling up speed 4 on this developing sleeve surface.
A curing agent was applied by dip coating at 0 m / min and dried for about 2 to 3 hours. Subsequently, the coating agent K obtained above was subjected to a dip coating at a pulling rate of 15 m / min, and a dry curing treatment was performed at 80 ° C. for 20 minutes to obtain a developing sleeve K.

The coating conditions used in the production of the developing sleeves H to K described above are summarized in Table 2, and the physical properties of the developing sleeves H to K obtained are shown in Table 3.

[0063]

[Table 2] Table 2: Coating conditions used in manufacturing the developing sleeves H to K

[0064]

[Table 3] Table 3: Physical properties of the developing sleeves A to K

(Production of one-component developer A) To 710 g of ion-exchanged water, 450 g of 0.1 M Na ₃ PO ₄ aqueous solution was added and heated to 60 ° C., and then TK homomixer (made by Tokushu Kika Kogyo) ) Was used for stirring at 12,000 rpm.
To this, 68 g of 1.0 M-CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ . -(Monomer) Styrene 165g n-Butyl acrylate 35g- (Colorant) C.I. I. Pigment Blue 15: 3 15g ・ (Charge control agent) salicylic acid metal compound 3g ・ (polar resin) saturated polyester (acid value 14, peak molecular weight: 8,000) 10g ・ (release agent) ester wax (melting point 70 ° C) 50g The above formulation was heated to 60 ° C. and uniformly dissolved and dispersed at 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). In addition to this, the polymerization initiator 2,2 '
-Azobis (2,4-dimethylvaleronitrile) (10 g) was dissolved to prepare a polymerizable monomer composition.

The above polymerizable monomer composition was charged into the aqueous medium obtained above, and the mixture was mixed at 10 ° C. at 10 ° C. using a TK type homomixer at 60 ° C. in an N ₂ atmosphere.
After stirring for a minute, the polymerizable monomer composition was granulated. afterwards,
While stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and the reaction was performed for 10 hours. After the completion of the polymerization reaction, residual monomers were removed under reduced pressure, and after cooling, hydrochloric acid was added to dissolve calcium phosphate, followed by filtration, washing with water, and drying to obtain colored suspended particles (toner particles). The obtained toner particles were measured by a toner tomographic surface measurement method using a transmission electron microscope (TEM). As a result, a core portion mainly composed of wax, and a resin covering the core portion (synthesized by polymerization of a polymerizable monomer) The resin had a core / shell structure having a shell portion mainly composed of the resin. The obtained toner particles had a shape factor SF-1 of 115 and a shape factor SF-2 of 110.

100 parts by weight of the polymerized toner particles having the core / shell structure obtained above are mixed with 2.2 parts by weight of finely treated hydrophobic silica powder having a specific surface area of 200 m ² / g according to the BET method. Then, the one-component developer A subjected to the external addition treatment was prepared. The external additive coverage of the one-component developer A is 85%, and further the electron microscope (magnification: 1
The particle size of the silica fine powder in the surface observation of the one-component developer A was about 50 nm. The obtained one-component developer A has a weight average particle diameter of 6.0 μm,
The porosity was 55%.

(Production of One-Component Developer B) To 710 g of ion-exchanged water, 450 g of 0.1 M Na ₃ PO ₄ aqueous solution was added and heated to 60 ° C., then TK homomixer (made by Tokushu Kika Kogyo) ) Was used for stirring at 12,000 rpm.
To this, 68 g of 1.0 M-CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ . -(Monomer) Styrene 165g n-Butyl acrylate 35g- (Colorant) C.I. I. Pigment Blue 15: 3 15 g- (Charge control agent) salicylic acid metal compound 3 g- (Polar resin) saturated polyester (acid value 14, peak molecular weight: 8,000) 10 g On the other hand, the above formulation was heated to 60 ° C and TK homomixer (Made by Tokushu Kika Kogyo Co., Ltd.) was used to uniformly dissolve and disperse at 12,000 rpm. In addition to this, the polymerization initiator 2,2'-
Azobis (2,4-dimethylvaleronitrile) (10 g) was dissolved to prepare a polymerizable monomer composition.

The above polymerizable monomer composition was added to the aqueous medium obtained above, and the mixture was added at 60 ° C. under N ₂ atmosphere.
10 using a TK homomixer at 10,000 rpm
The polymerizable monomer composition was granulated by stirring for a minute. afterwards,
While stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and the reaction was performed for 10 hours. After completion of the polymerization reaction, residual monomers were removed under reduced pressure under the same conditions as for the one-component developer A, and after cooling, hydrochloric acid was added to dissolve calcium phosphate. Then, filtration, washing with water, and drying were performed to obtain colored suspended particles (toner particles). The obtained toner particles have a shape factor SF-1.
Was 120 and the shape factor SF-2 was 115.

100 parts by weight of the polymerized toner particles obtained above were mixed with 1.5 parts by weight of finely-hydrophobized silica powder having a specific surface area of 200 m ² / g by the BET method, and externally added. The one-component developer B thus prepared was prepared. The external additive coverage of the one-component developer B was 80%. The obtained one-component developer B has a weight average particle size of 5.
It was 5 μm and the porosity was 55%.

(Production of One-Component Developer C) Styrene-acrylic resin 100 parts by weight Carbon black 5 parts by weight Low molecular weight ethylene-propylene copolymer 4 parts by weight Negative charge control agent (azo dye metal Complex) 1 part by weight The mixture having the above composition is melt-kneaded with a twin-screw extruder heated to 140 ° C., coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a jet mill to obtain a finely pulverized product ( To obtain toner particles). The obtained toner particles have a shape factor S
F-1 was 145 and shape factor SF-2 was 133.

100 parts by weight of the pulverized toner particles obtained above are mixed with 1.5 parts by weight of finely-divided silica powder having a specific surface area of 200 m ² / g by the BET method and externally added. The one-component developer C was prepared. The external additive coverage of the one-component developer C was 74%. The obtained one-component developer C has a weight average particle size of 5.
It was 0 μm and the porosity was 60%.

(Production of One-Component Developer D) Styrene-acrylic resin 100 parts by weight Carbon black 5 parts by weight Low molecular weight ethylene-propylene copolymer 4 parts by weight Negative charge control agent (azo dye metal Complex) 1 part by weight The mixture having the above composition is melt-kneaded with a twin-screw extruder heated to 140 ° C., coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a jet mill to obtain a finely pulverized product ( To obtain toner particles). The obtained toner particles have a shape factor S
F-1 was 148 and shape factor SF-2 was 136.

100 parts by weight of the pulverized toner particles obtained above are mixed with 1.9 parts by weight of hydrophobized silica fine powder having a specific surface area of 200 m ² / g by the BET method, and externally added. The one-component developer D was prepared. The external additive coverage of this one-component developer D was 75%. The obtained one-component developer D has a weight average particle diameter of 4.
It was 8 μm and the porosity was 67%.

Table 4 shows the physical properties of the above-obtained one-component developers A to D.

Table 4: Physical properties of the one-component developers A to D

Example 1 The one-component developer A obtained above was applied to the developing device shown in FIG.
And a developing sleeve A, an idle rotation durability test is performed under the following idle rotation conditions, and the coating state of the one-component developer A on the developing sleeve A is observed to observe the uncharged toner from the developing sleeve A. Was evaluated. (Idle rotation condition) -Developing roller rotation speed: 100 mm / sec, 200 m
m / sec ・ Dry rotation time: 60 minutes

In the coating state observation, the presence or absence of the uncharged toner falling off during idling durability was judged based on the evaluation criteria shown in Table 5 below, and the dropping of the uncharged toner from the developing sleeve was evaluated.

[0078]

[Table 5] Table 5: Evaluation Criteria for Presence / Absence of Uncharged Toner Dropping During Endurance Rotation

Further, an image was formed under the following image output conditions by using the image forming apparatus shown in FIG. 5 equipped with the developing apparatus of this embodiment used above. (Image output condition) -Photosensitive drum peripheral speed: 120 mm / sec-Developing sleeve peripheral speed: 175 mm / sec-Charging potential on the photosensitive drum: -650 V-Exposed part potential on the photosensitive drum: -120 V-Development bias DC component : -400V AC component: 1,800V _PP , 2,000Hz-Distance between photosensitive drum and developing sleeve: 300 μm-Remark: photosensitive drum diameter: φ60 mm, developing sleeve diameter:
φ16 mm

(Evaluation) The obtained images were evaluated for image density change, reversal fog and transferability by the following evaluation methods. First, under the above-mentioned image forming conditions, 200
In the idle rotation durability test at the rotation speed of mm / sec,
Initially, after 5 minutes, 10 minutes, 30 minutes, and 60 minutes, a solid image and a solid white image are output under the following conditions to change the image density (particularly, the density reduction state) and reverse the image. The fog was evaluated based on the evaluation criteria shown in Table 6. The evaluation criterion is a comprehensive evaluation through durability (image emphasis after 60 minutes).

[0081]

[Table 6] Table 6: Evaluation criteria for image density change and reversal fog

Transferability The transferability of the image obtained above was evaluated by determining the transfer efficiency of the image. First, the transfer efficiency at the time of outputting each image is measured by the following procedures (1) to (3). That is, the amount of the developer before transfer on the photosensitive drum 0 is difficult to measure because the adhesive force of the developer to the photosensitive drum 0 is strong due to the mirroring force, and therefore the amount of the developer in each of the areas a and b below is large. It is necessary to obtain the transfer efficiency from the amount. The image forming apparatus (FIG. 5) is stopped during solid image output. The developer amount Tm (mg / cm ² ) per unit area in each of the areas a and b listed below is measured. The transfer efficiency Tr (%) is calculated from the following equation: a: developer amount Tm ₁ after transfer on the photosensitive drum 0, b: developer amount Tm ₂ after transfer on the transfer paper 18.

[0083]

(Equation 4) Next, the transferability was evaluated by the value of the transfer efficiency Tr (%) obtained as described above, based on the criteria in the table below.

[0084]

[Table 7] Table 7: Transferability evaluation criteria

The developer amount Tm per unit area used for the above-mentioned evaluation of transfer property is measured as follows. FIG.
Is an example of a device for measuring the amount of developer Tm per unit area, and a method for measuring the amount of developer per unit area will be described using this. In FIG. 10, reference numeral 30 denotes a developer suction device main body. The developer suction device 30 is roughly composed of a developer suction port 31 and a developer filter connected to the developer suction port 31. Collection filter 3
2 and an air suction port 34. Further, the developer suction port 31 can be separated from the developer suction device 30 at a portion 35 in FIG. Here, the separating structure of the developer suction port 31 and the developer collecting filter 3
The description of the connection structure with the second developer suction port 31 is omitted.
The developer suction device 30 is hollow, and an air flow 36 is generated by suction by a suction means such as an electric vacuum cleaner to suck the developer from the developer suction port 31.
The developer collecting filter 32 provided inside is configured to collect the sucked developer.

An example of a method of measuring the developer amount Tm per unit area using the above-mentioned developer suction device will be described below. FIG.
FIG. 1 is a schematic perspective view showing how the developer suction device 30 is used to measure the amount of the developer on the measurement target 37.
First, the mass m ₁ of the developer collecting filter 32 is measured. Next, as shown in FIG. 11, the developer suction port 31 of the developer suction device 30 is used as a measurement target (in this example, a solid image on the transfer paper 18 or a transfer residual developer after transfer on the photosensitive drum 0). )
The developer on the measurement target is sucked and collected by the developer collecting filter 32 while being sucked in the direction of arrow 39. Next, the mass m of the developer collecting filter 32 after collecting the developer
Measure ₂ . Further, the area S of the developer removal area 38 in the measurement object 37 after being collected by suction is measured. From the above measured values m ₁ , m ₂ , and S, the developer amount Tm per unit area is
It can be calculated by the following formula.

[0087]

(Equation 5)

Examples 2 to 9 and Comparative Examples 1 to 2 The combination of the one-component developer A and the developer sleeve A having a weight average particle diameter D of 6.0 μm used in Example 1 shown in Table 8 was prepared as described above. Evaluation was performed in the same manner as in Example 1 except that the combination of the one-component developer A containing polymerized toner particles having the same core / shell structure as described in (4) and each developing sleeve shown in Table 8 was changed. In Table 8, 10 of each developing sleeve surface
The point surface roughness R _Z , the average spacing S _{m of} the concavities and convexities, and the average inclination angle θ _a of the concavities and convexities are shown, and the characteristics of the surface of each developing sleeve are classified and shown by these values. Table 9 shows the evaluation results. As a result, when Tables 8 and 9 were overlapped, it was found that good image formation was not performed unless the requirement of R _Z ≧ D / 2 was satisfied. Further, when the average inclination angle θ of the irregularities on the surface of the developing sleeve and the average interval S of the irregularities on the surface of the developing sleeve are θ ≦ 45 °, S is S ≦ 20D or 45 ° <θ <90 °. It was confirmed that particularly good image formation was carried out when S ≦ 10D.

[0089]

Table 8: Properties of developing sleeve surface in Examples 1-9 and Comparative Examples 1-2

[0090]

[Table 9] Table 9: Evaluation results

Examples 10 to 18 and Comparative Examples 3 to 4 The combination of the one-component developer A and the developer sleeve A having the weight average particle diameter D of 6.0 μm used in Example 1 was used.
Each evaluation was performed in the same manner as in Example 1 except that the combination of the one-component developer B containing polymerized toner particles having a weight average particle diameter D of 5.5 μm and each developing sleeve shown in Table 10 was changed. . Table 10 shows the 10-point surface roughness R _{Z of} each developing sleeve surface, the average spacing S _{m of} the unevenness, and the average inclination angle θ _a of the unevenness, and further classifies the characteristics of each developing sleeve surface by these values. And showed it. Table 11 shows the evaluation results.

[0092]

Table 10: Characteristics of developing sleeve surface in Examples 10-18 and Comparative Examples 3-4

[0093]

[Table 11] Table 11: Evaluation results

Examples 19 to 27 and Comparative Examples 5 to 6 The combination of the one-component developer A having a weight average particle diameter D of 6.0 μm and the developer sleeve A used in Example 1 was used.
Each evaluation was performed in the same manner as in Example 1 except that the combination of the one-component developer C containing pulverized toner particles having a weight average particle diameter D of 5 μm and each developing sleeve shown in Table 12 was used. Table 12 shows the 10-point surface roughness R _{Z of} each developing sleeve surface, the average spacing S _{m of} the unevenness, and the average inclination angle θ _a of the unevenness. Furthermore, the characteristics of each developing sleeve surface are classified by these values. And showed it. Table 13 shows the evaluation results. As a result, as shown in Table 13, it was confirmed that the transferability was inferior as compared with Tables 9 and 11 showing the evaluation results when the polymerized toner was used.

[0095]

Table 12: Characteristics of developing sleeve surface in Examples 10-18 and Comparative Examples 3-4

[0096]

[Table 13] Table 13: Evaluation results of Examples 19 to 27 and Comparative Examples 5 to 6

Examples 28 to 37 and Comparative Example 7 The combination of the one-component developer A and the developer sleeve A having the weight average particle diameter D of 6.0 μm used in Example 1 was used.
Each evaluation was performed in the same manner as in Example 1 except that the combination of the one-component developer D containing pulverized toner particles having a weight average particle diameter D of 4.8 μm and each developing sleeve shown in Table 12 was used. . Table 14 shows the 10-point surface roughness R _{Z of} each developing sleeve surface, the average spacing S _{m of} the unevenness, and the average inclination angle θ _a of the unevenness. Furthermore, the characteristics of each developing sleeve surface are classified by these values. And showed it. The evaluation results are shown in Table 15.

[0098]

Table 14: Properties of developing sleeve surface in Examples 28 to 37 and Comparative Example 7

[0099]

Table 15: Evaluation results of Examples 28 to 37 and Comparative Example 7

[0100]

As described above, according to the present invention,
By forming specific irregularities on the surface of the developing sleeve and finishing the surface to a rough surface, it is possible to improve the charge imparting property to the developer coating layer in the contact nip region between the developing blade and the developing sleeve. As a result, even when a toner with a low porosity is used, it is possible to optimize the charge amount distribution in the developer coating layer, effectively preventing the generation of reverse toner and uncharged toner when forming an image. Therefore, a high quality image can be formed. Further, according to the present invention, it becomes possible to use a spherical toner having a high fluidity, such as a toner having a high porosity and an external additive, and it is possible to form a high-quality image.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a developing device used in the present invention.

FIG. 2 is a cross-sectional view of an example near the surface of the developing sleeve used in the present invention.

FIG. 3 is an operation explanatory view of an example of a developing sleeve of the developing device used in the present invention.

FIG. 4 is an operation explanatory view of another example of the developing sleeve of the developing device used in the present invention.

FIG. 5 is a schematic configuration diagram showing an example of an electrophotographic image forming apparatus in which the present invention is embodied.

FIG. 6 is a diagram showing an example of a developing device used in a conventional image forming apparatus.

FIG. 7 is an operation explanatory view of an example of a developing sleeve of a conventional developing device.

FIG. 8 is an operation explanatory view of another example of the developing sleeve of the conventional developing device.

FIG. 9 is an operation explanatory view of another example of the developing sleeve of the conventional developing device.

FIG. 10 is an example of a developer suction device used when measuring the amount of developer per unit area.

11 is a diagram showing a usage state of the developer suction device of FIG.

[Explanation of symbols]

 0: photoconductor drum 1: developing device 2: developing sleeve 3: developing blade 4: near contact nip between developing sleeve and developing blade 5: AC voltage 6: DC voltage 7: blowout prevention sheet 8: hopper 9: developing bias Power supply 10: Conductive metal particles 11: Conductive primer T: Non-magnetic one-component toner T2: Toner in the second coat layer

Claims (12)

[Claims] 1. An image carrier on which (i) an electrostatic latent image is formed, (ii) a developer carrier for carrying a one-component developer, and one-component system development on the surface of the developer carrier. At least a developer amount controlling means for controlling the amount of the developer is provided, and the electrostatic latent image on the image bearing member is formed in a developing region where the image bearing member and the developer bearing member face each other. In an image forming apparatus provided with a developing device for developing with a component type developer, the 10-point average roughness of the surface of the developer carrying member is R _Z, and the weight average particle diameter of the one component type developer is D. At this time, the image forming apparatus is characterized in that the 10-point average roughness R _Z and the weight average particle diameter D satisfy a relationship of R _Z ≧ D / 2. 2. The developer carrying member has the following relationship where θ ≦ 45 ° and S ≦ 20D, where S is an average interval of the unevenness on the surface of the developer carrying member and θ is an average inclination angle of the unevenness. The image forming apparatus according to claim 1, wherein the image forming apparatus has an uneven surface satisfying S ≦ 10D when 45 ° <θ <90 °. 3. The one-component developer has a shape factor SF-1.
Is 100 to 140 and the shape factor SF-2 is 100 to 120
The image forming apparatus according to claim 1, wherein the image forming apparatus has spherical toner particles within the range. 4. The image forming apparatus according to claim 3, wherein the spherical toner particles are partially or wholly formed by a polymerization method. 5. The image forming apparatus according to claim 4, wherein the spherical toner particles have a core / shell structure. 6. The image forming apparatus according to claim 5, wherein the main constituent component of the core portion of the spherical toner particles is a low softening point substance having a melting point of 40 to 90 ° C. 7. The image forming apparatus according to claim 1, wherein the one-component developer is a non-magnetic one-component developer. 8. The image forming apparatus according to claim 1, wherein the one-component developer has a surface coverage of the external additive in the range of 5 to 99%. 9. The image forming apparatus according to claim 1, wherein the unevenness of the surface of the developer carrying member is formed by melting and adhering powder on the base material through a melt adhesion or an adhesion layer. 10. The powder is either conductive metal particles, resin powder having a charging polarity opposite to that of the developer, or metal particles coated on the surface with the resin powder. The image forming apparatus according to claim 9. 11. The image forming apparatus according to claim 9, wherein the powder has a spherical shape. 12. The image forming apparatus according to claim 1, wherein the developing device further includes a developer supply unit for supplying the one-component developer to the developer carrier.