JP2006330562A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which an inexpensive organic photoreceptor and a toner with a lubricative substance externally added thereto are used, by which a high quality image is formed and which has excellent durability. <P>SOLUTION: The image forming apparatus performs image formation by using a photoreceptor of ≥45 nN/m in surface free energy and the toner with the lubricative substance added thereto, electrifying the photoreceptor, producing the electrostatic latent image by exposure and developing the electrostatic latent image by using the toner. The average of the surface free energy on the photoreceptor surface in an image forming area of the photoreceptor during the image formation by the image forming apparatus is ≤32 mN/m and the difference between the maximum value and minimum value of the surface free energy is ≥5 mN/m. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof. In particular, charging, writing, development, transfer, cleaning, static elimination, etc. are repeated to form a toner image on the photoreceptor in sequence, and the toner image is sequentially transferred and recorded on a transfer sheet such as paper or an OHP film. The present invention can be applied to an electrophotographic image forming apparatus.

With the development and popularization of PCs (personal computers), the demand for higher image quality in color image formation in electrophotographic apparatuses has become very strong. For example, materials that capture color images from digital cameras and scanners are very commonly used, and it has become common for the plot area of graphs to be halftone colors.
In addition, it has become common to form images taken with digital cameras not only with silver halide photographs but also with sublimation printers and inkjet printers. However, these image formations require a long time for image formation, and the cost of paper and ink for image formation is high, and producing posters and presentation materials has problems in terms of production speed and cost. there were.

  Image formation using an electrophotographic process is excellent in terms of production speed and cost, but it has been necessary to further improve image quality. In image formation using an electrophotographic process, to improve the image quality, it is sufficient to reduce the particle size of the toner. However, as the particle size of the toner decreases, the transfer residual toner on the photosensitive member by the cleaning blade decreases. The cleaning could not be performed sufficiently and the image quality was greatly deteriorated. As the particle size of the toner decreases, the amount of charge per toner weight increases, so the electrostatic adhesion between the photoreceptor and toner increases. The cleaning blade scrapes off the toner on the photosensitive member. However, the toner with a small particle size is relatively small compared to the case where the toner is caught by the cleaning blade, and the force to scrape off the toner is small. become weak. In addition, when the cleaning blade vibrates due to the friction between the cleaning blade and the photoconductor, the toner enters a slight gap generated between the cleaning blade and the photoconductor, and the toner passes through the cleaning blade, greatly reducing the image quality. It was a cause. If there is a large amount of toner slipping due to such cleaning failure, streaky abnormal images may be formed, or the slipped toner may adhere to the charging roller, causing uneven resistance of the charging roller, and whitening due to uneven charging potential. In many cases, streaks were generated, and the toner component adhered to the photosensitive member in a streak form to generate white streaks.

  In order to reduce the adhesion between the photoconductor and the toner, it is effective to reduce the surface free energy of the photoconductor. For example, Patent Document 1 discloses a photoconductor having a surface free energy of 30 dyne / cm or less by using a binder containing a fluororesin. However, an image of an image forming apparatus using this photoconductor can form a high-quality image without much image formation. However, as the image formation is repeated, the surface free energy of the photoconductor increases. As a result, the image quality deteriorates.

  In Patent Document 2, a photoconductor having a surface layer made of amorphous silicon containing fluorine is used, the surface free energy of the photoconductor is set to 40 mN / m or less, and image flow adhering to the surface of the photoconductor by repeating image formation is disclosed. An image forming apparatus that removes a substance to be caused by a cleaning unit is disclosed. However, since the surface layer of amorphous silicon containing fluorine is formed by a vapor phase method, the cost of the photoreceptor is very high. Further, there is no disclosure of residual toner cleaning properties when a small particle size toner is used. In general, defective cleaning of residual toner does not occur on the entire image forming area, but tends to concentrate on a limited area, which is caused by variations in the shape of the cleaning blade and the surface free energy of the photoreceptor. It is. For this reason, it is not preferable that the surface free energy of the photoreceptor is measured only at one point on the photoreceptor.

  Patent Document 3 discloses an image forming apparatus in which a photoreceptor having a siloxane resin layer has a surface free energy of 40 to 80 mN / m, an average particle diameter of toner of 4 to 12 μm, and an average charge of 10 to 30 μC / g. It is disclosed. However, the toner used in this image forming apparatus is set to have a low average charge amount in order to weaken the adhesion to the photoreceptor. For this reason, the stability of the image is lower than that in the case of using normal toner, and soiling is likely to occur depending on the environment, which is not preferable.

  Patent Document 4 discloses an image forming apparatus using a photoconductor having a surface free energy of 3 to 65 mN / m, and increasing the surface free energy of the photoconductor by durability to 25 mN / m. In the measurement of the surface free energy disclosed in Patent Document 4, water, methylene iodide, and α-bromonaphthalene are used, but an error in calculating the surface free energy occurs with only three types of solvents. The error cannot be verified. In particular, water tends to cause measurement errors, and it is difficult to measure true surface free energy. Further, as described above, it is not preferable that the surface free energy of the photoreceptor is measured only at one point on the photoreceptor. If the image to be formed by the user is completely random, one point may be measured. However, a user who creates many images such as quotations and proposals, such as a standard table, has a free surface on the photoreceptor. It is easy to generate an energy distribution, and it is easier to have a distribution in the longitudinal direction of the photoconductor than in the circumferential direction of the photoconductor. It is not preferable to have a surface free energy distribution in the longitudinal direction of the photoconductor, which is liable to cause a reduction in image quality due to a decrease in cleaning properties.

  Patent Document 4 also discloses an image forming apparatus using an inexpensive organic photoreceptor as a photoreceptor. However, in an image forming apparatus using an organic photosensitive member, the organic photosensitive member is easily worn by friction with a cleaning blade. The body thickness must be increased. In this case, since the film thickness of the photoconductor in the initial stage of image formation and that over time are greatly different, the capacitance varies greatly over time of the photoconductor, and it is difficult to make the image density constant. Patent Document 4 also discloses an image forming apparatus using a photoreceptor in which a surface layer containing a fluorine compound is provided on an organic photoreceptor. However, since the wear rate of the surface layer containing a fluorine compound is not much slower than that of a normal organic photoreceptor, the surface layer needs to have a considerable thickness. However, if the surface layer is made too thick, the movement of holes is hindered, so that the post-exposure potential and the residual potential are likely to increase, making it difficult to use in a high-quality image forming apparatus.

  For the purpose of wear resistance of an inexpensive organic photoreceptor, Patent Document 5 discloses an organic photoreceptor in which a filler such as a metal oxide is contained in the photoreceptor surface layer. This organic photoreceptor has a very high wear resistance with respect to the cleaning blade, which is preferable. However, this organic photoconductor increases the surface free energy of the photoconductor, repeats image formation, decreases the transfer efficiency, tends to cause abnormal images such as voids, and wears a cleaning blade to perform cleaning. It had the defect that it was easy to generate a defect.

In Patent Document 6 and Patent Document 7, when a lubricant is externally added to the toner and the toner is developed on the photoreceptor by image formation, the lubricant adheres from the toner to the photoreceptor. It is described that the surface free energy can be reduced, the friction between the photoreceptor and the cleaning blade can be reduced, and the cleaning performance of the remaining toner can be ensured. However, since the lubricating material is supplied only to the place where the toner is developed on the photoconductor, the surface of the place where the toner is not developed by the user who creates a lot of images like a standard table such as an estimate or a plan. Since the energy remains high, the surface free energy variation of the photoconductor tends to be very large. If the place where the surface free energy is high and the place where the surface free energy is in contact with each other with a boundary, the cleaning blade is likely to vibrate at the boundary, and a cleaning failure and an irritating frictional sound are likely to occur.
JP-A-10-69100 JP 2001-66812 A JP 2001-272809 A Japanese Patent Laid-Open No. 11-311875 JP-A-01-170951 Japanese Patent No. 2859646 JP 2002-229241 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that is capable of forming a high-quality image and has excellent durability in an image forming apparatus using an inexpensive organic photoconductor and toner externally added with a lubricating substance.

  As a result of detailed studies to solve the above problems, the present inventors have found that inexpensive organic photoreceptors have high surface free energy, and as such, there are many problems in terms of toner cleaning properties and durability. However, by forming an image using a toner externally added with a lubricating substance, the surface free energy on the surface of the photoconductor is reduced and the variation in the surface free energy on the surface of the photoconductor is set to 5 mN / m or less. If possible, the present inventors have found that an image forming apparatus capable of forming a high-quality image and having excellent durability can be provided, and the present invention has been achieved. That is, the present invention has the following configuration.

(1) Using a photoconductor having a surface free energy of 45 mN / m or more and a toner externally added with a lubricating substance, charging the photoconductor, producing an electrostatic latent image by exposure, and electrostatically using the toner In an image forming apparatus that develops a latent image and forms an image, the average surface free energy of the surface of the photoreceptor in the image forming area of the photoreceptor during image formation by the image forming apparatus is 32 mN / m or less, and the surface free energy Forming apparatus in which the difference between the maximum value and the minimum value is 5 mN / m or less.

(2) In the image forming apparatus according to (1), the measurement of the surface free energy on the surface of the photoconductor during image formation is performed for each of a plurality of divided areas in a direction orthogonal to the rotation direction of the photoconductor. An image forming apparatus having a width of a plurality of divided areas of 50 mm or less.
(3) The image forming apparatus according to (1) or (2), wherein the lubricant substance externally added to the toner is a metal soap.

（ただし、前記数式中、γ_Ｌは、γ^ａ _Ｌ＋γ^ｂ _Ｌ＋γ^Ｃ _Ｌで表される液体の表面自由エネルギーを表す。γ^ａ _Ｌは、液体の表面自由エネルギーの分散成分を表す。γ^ｂ _Ｌは、液体の表面自由エネルギーの双極子成分を表す。γ^Ｃ _Ｌは、液体の表面自由エネルギーの水素結合成分を表す。γ^ａ _Ｓは、固体の表面自由エネルギーの分散成分を表す。γ^ｂ _Ｓは、固体の表面自由エネルギーの双極子成分を表す。γ^Ｃ _Ｓは、固体の表面自由エネルギーの水素結合成分を表す。θは、接触角を表す。） (4) In the image forming apparatus according to any one of (1) to (3), the surface free energy of the photoconductor measures a contact angle with a liquid whose components of the surface free energy are known, It is a method for measuring the surface free energy of a solid using the following formula (7) based on the extended Fowkes theory, and is a value obtained by linear regression from contact angle data with four or more liquids. An image forming apparatus.

(However, in the formula, gamma _L is, .Ganma represents the surface free energy of the liquid represented by ^{_{γ a L + γ b L +}} γ C L a L is, .Ganma ^b representing the dispersive component of the surface free energy of the liquid _L represents a dipole component of the surface free energy of the liquid, γ ^C _L represents a hydrogen bond component of the surface free energy of the liquid, γ ^a _S represents ^a dispersed component of the surface free energy of the solid, γ ^b _(S represents the dipole component of the surface free energy of the solid, γ ^C _S represents the hydrogen bond component of the surface free energy of the solid, and θ represents the contact angle.)

(5) In the image forming apparatus described in (4), the liquid for measuring the contact angle in order to obtain the surface free energy of the photoreceptor is selected from diiodomethane, α-bromonaphthalene, diethylene glycol, glycerin, and formamide. An image forming apparatus.
(6) In the image forming apparatus according to any one of (1) to (5), the image forming apparatus stores image information for each of a plurality of divided areas in a direction perpendicular to the rotation direction of the photosensitive member. An image forming apparatus comprising image information calculating means for calculating, and performing charge exposure development for each area separately from the purpose of image formation based on the image information for each area.

(7) In the image forming apparatus according to (6), the width of the plurality of divided areas of the image information calculation unit that calculates image information for each of the plurality of divided areas in a direction perpendicular to the rotation direction of the photosensitive member is 30 mm. An image forming apparatus comprising:
(8) The image forming apparatus according to (6) or (7), wherein the image information calculating unit is a unit that calculates information of an image area with respect to a traveling area.
(9) In the image forming apparatus according to any one of (6) to (8), an exposure pattern is determined for each area according to image information of each area, and exposure development is performed separately from the purpose of image formation. An image forming apparatus comprising:

(10) In the image forming apparatus according to any one of (6) to (9), the charge exposure development is performed for each of the regions based on the image information for each region separately from the image forming purpose. An image forming apparatus, which is performed every time after formation.
(11) The image forming apparatus according to any one of (1) to (10), wherein the average particle size of the toner is 7 μm or less.
(12) The image forming apparatus according to any one of (1) to (11), wherein the highest resolution at which an image can be formed by the image forming apparatus is 1000 dpi or more.
(13) The image forming apparatus according to any one of (1) to (12), wherein the image forming apparatus is capable of forming a color image.
(14) A process cartridge for an image forming apparatus used in the image forming apparatus according to any one of (1) to (13), wherein the electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, and A process cartridge for an image forming apparatus, wherein at least one means selected from cleaning means is integrally formed and is detachable from an image forming apparatus main body.

  N. Akiaki Kitazaki, Toshio Hata et al. In Fowkes' theory describing nonpolar intermolecular forces with respect to surface free energy (synonymous with surface tension) in Japan Adhesion Association Journal 8 (3), 131-141 (1972). On the other hand, it states that it can be further expanded to a component by polar or hydrogen-bonded intermolecular forces. By this extended Fowkes theory, the surface free energy of each substance can be obtained with three components.

This theory is based on the following three assumptions.
<Assumption 1>
The surface free energy of organic materials is expressed as the sum of three different components.
γ = γ ^a + γ ^b + γ ^c (1)
γ ^a : dispersion component (nonpolar wetting)
γ ^b : Dipole component (wetting due to polarity)
γ ^c : hydrogen bonding component (wetting by hydrogen bonding)

<Assumption 2>
Each surface free energy that decreases as a result of contact of two substances can be expressed as the sum of the geometric mean of the corresponding surface free energies, and if there is no corresponding component, there is no interaction between the components. Think.

<Assumption 3>
Standard substances are classified into the following three types.
^(A) γ = γ a Type: saturated hydrocarbons liquid and solid.
(B) γ = γ ^a + γ ^b type: liquids and solids other than (A) and (C).
(C) [gamma] = [gamma] ^a + [gamma] ^b + [gamma] ^c type: Liquids and solids that are soluble in water or have a small interfacial tension with water ([gamma] ₁₂ <30 mN / m) and have hydrogen bonds.

となる。 Based on these assumptions, the surface free energy can be obtained as follows.
If the bonding energy of substances 1 and 2 is W ₁₂ ,
W ₁₂ = γ ₁ + γ ₂ −γ ₁₂ (3)
And from equation (2)

It becomes.

となる。 In the case where the substance is a solid and a liquid, assuming that the droplet reaches the equilibrium while maintaining the contact angle θ on the surface of the solid as shown in FIG. 11, the following Young's formula is established.
γ _S = γ _SL + γ _L cos θ (5)
Therefore, the following relationship is established between the contact angle and the adhesion energy from the equations (3) and (5).
W _SL = γ _L (1 + cos θ) (6)
From equations (4) and (6)

It becomes.

Using equation (7), first, the contact angle was measured using a liquid TypeA, seeking _gamma ^{S a} from equation (7), then measuring the contact angle with a liquid TypeB, obtaining the gamma _S ^b. At this time, γ _S ^a and γ _S ^b may be obtained from simultaneous data of two types of Type B liquid. Finally, measuring the contact angle with a liquid TypeC, in a way that finding a gamma _S ^c can be determined each component of the surface free energy of the solid. Further, each component of the surface free energy of the solid can also be obtained from the data of three types of liquids in which γ _L ^b or γ _L ^c is not 0 for all liquids, using a ternary simultaneous equation.

However, when trying to determine each component of the surface free energy of the solid by the above method, the square root (√γ _S ^b or the like) of each component of the surface free energy may become negative due to the calculation. For example, when √γ _S ^b becomes negative, it is calculated by assuming that γ _S ^b = 0 without calculating γ _S ^b by squaring. The method of obtaining from the contact angle data of three types of liquids is that the solid surface free energy obtained by the combination of the liquids used for the measurement varies greatly, and it is not known which combination of liquids the measurement result should be reliable. was there. In addition, the contact angle is affected by the surface shape of the sample and changes its value. In some cases, the accurate surface free energy may not be measured. However, the conventional method cannot measure the exact surface free energy. Even if it was difficult to judge it. In particular, when water is used for three types of liquids, such problems are likely to occur, and the surface free energy is calculated for calculation, but it is not known whether the calculated value is a true value. It was.

とおくと、
ｙ＝ａｘ_１＋ｂｘ_２＋ｃｘ_３ ・・・（８）
となる。したがって固体の表面自由エネルギーの各成分（ａ，ｂ，ｃ）は標準物質による接触角データ（ｙ；ｘ_１，ｘ_２，ｘ_３）からの線形回帰により求めることができる。従来の３種類の液体の接触角データから求める方法は３つの未知数を３本の式から求めている。そのため何らかの影響で１つの液体の接触角が真値から大きくずれると、求まる固体の表面自由エネルギーもその影響を大きく受けてしまう。本発明における４種類以上の接触角データから求める方法では、この接触角の真値からのずれの影響を平均化し、表面自由エネルギー測定結果における接触角測定誤差の影響を少なくすることができる。 In the extended Fowkes theory (7),

After all,
y = ax ₁ + bx ₂ + cx ₃ (8)
It becomes. Therefore, each component (a, b, c) of the surface free energy of the solid can be obtained by linear regression from the contact angle data (y; x ₁ , x ₂ , x ₃ ) by the standard material. In the conventional method of obtaining from three types of liquid contact angle data, three unknowns are obtained from three equations. For this reason, if the contact angle of one liquid greatly deviates from the true value due to some influence, the obtained surface free energy of the solid is greatly affected. In the method of obtaining from four or more types of contact angle data in the present invention, the influence of deviation from the true value of the contact angle can be averaged, and the influence of the contact angle measurement error on the surface free energy measurement result can be reduced.

  Moreover, when calculating | requiring by linear regression, R-2 power value (multiple correlation coefficient) is computable. If the R-square value is close to 1, all contact angle data are in the theoretical formula (7), and it can be determined that the obtained surface free energy of the solid is reliable. That is, the measurement reliability can be easily determined by the R-2 power value. As a criterion for determination, when the R-square value is 0.8 or more, the measurement result is considered to be reliable. If it is determined that the R-square value is small and the reliability is low, it is considered that the contact angle cannot be measured accurately. In many cases, the cause is the surface shape of the sample, and it is necessary to devise a sample form that reduces the surface roughness and voids. Sample preparation methods with less surface roughness and voids include compression molding and heat melting.

が最小になるように（ａ，ｂ，ｃ）を決める。最小の条件は

であり、計算すると、（１２）より

（１３）より

（１４）より

となる。（１５）〜（１７）の３元連立方程式を解けば（ａ，ｂ，ｃ）が求まる。 The calculation method by linear regression is as follows.
Assuming that there are contact angle data for n types (n ≧ 3) of liquid, write as follows.
y _i = ax _i1 + bx _i2 + cx _i3 i = 1 to n (9)
If the error is ε,
ε _i = y _i − (ax _i1 + bx _i2 + cx _i3 ) i = 1 to n (10)
Sum of squares of this error

(A, b, c) is determined so that is minimized. The minimum requirement is

And when calculated, from (12)

From (13)

From (14)

It becomes. (A, b, c) can be obtained by solving the ternary simultaneous equations (15) to (17).

The surface free energy of the solid can be obtained by squaring the obtained (a, b, c).
However, at this time, any of a, b, and c may be negative. Since a, b, and c are the square roots of the surface free energy of the solid, it is physically strange that this is negative. Therefore, the above calculation must be solved under the conditions of a ≧ 0, b ≧ 0, and c ≧ 0.
Since S (a, b, c) is quadratic with respect to a, b, c, when any of a, b, c becomes negative, for example, when c becomes negative, c = What is necessary is just to obtain | require (a, b) so that S (a, b, 0) may become the minimum. Here, when b becomes negative, b = 0 is set, and a is obtained so that S (a, 0, 0) is minimized. However, even when c becomes negative, there are cases where S is smaller when (a, c) is calculated such that b = 0 and S (a, 0, c) is minimized. Therefore, in actuality, when any one of a, b, and c is negative, a = 0, b = 0, c = 0, a = b = 0, a = c = 0, b = c = 0 A solution to be obtained is calculated by calculating a ≧ 0, b ≧ 0, c ≧ 0 and S being minimum.

（１１）、（１８）からＳが最小の場合、Ｒ−２乗値は最大となる。 The R-2 power value can be obtained by the following equation.

When S is the minimum from (11) and (18), the R-squared value is the maximum.

The standard substance used in the measurement method of the present invention may be a combination in which each component of the surface free energy is four or more types of known liquids and γ _L ^b or γ _L ^c does not become zero in all liquids. Examples of liquids having known components of surface free energy include those listed in Tables 1 to 3. However, it is necessary not to cause extended wetting. Extended wetting is a phenomenon in which wetting spreads spontaneously when a droplet is placed on a solid. In this case, the contact angle cannot be measured. Type A liquids cause extended wetting for many organics.

  As a combination of standard substances for measuring the surface free energy of an organic substance, a combination including two or more types of Type B liquids and two or more types of Type C liquids is preferable without using a Type A liquid. In the surface free energy measurement, the value obtained depends on the combination of liquids used for the measurement, but the combination including two or more types of Type B liquids and two or more types of Type C liquids shows almost the same value and the measurement is stable.

  As the liquid used for measuring the surface free energy on the surface of the photosensitive member in the image forming apparatus of the present invention, for example, the solvents described in Journal of Japan Adhesion Association 8 (3), 131-141 (1972) can be used. , Diiodomethane, α-bromonaphthalene, diethylene glycol, glycerin, and formamide are preferable because the surface free energy of the surface of the photoreceptor with high reliability can be obtained.

  In the image forming apparatus of the present invention, an inexpensive organic photoconductor having a surface free energy of 45 mN / m or more is used as the photoconductor. As described above, a photoconductor having a surface free energy of 45 mN / m or more has a large frictional force with the cleaning blade, and thus the photoconductor and the cleaning blade are easily worn. Therefore, by forming an image using toner to which a lubricating substance is externally added, the lubricating substance can be transferred from the toner to the photosensitive member, and the surface free energy of the photosensitive member surface can be reduced. The frictional force can be reduced. However, the surface free energy of the photoreceptor used in the present invention is essentially 45 mN / m or more, preferably 47 mN / m or more, and more preferably 48 to 55 mN / m. If there is unevenness or disappearance from the photoconductor, where there is a place where the lubricant is present and where there is no lubricant, there will be a large difference in surface free energy, resulting in poor cleaning and noise. Is likely to occur. Therefore, it is necessary to control the surface free energy distribution of the photoreceptor.

  In the image forming apparatus of the present invention, the average surface free energy of the photoreceptor during image formation is 32 mN / m or less, preferably 30 mN / m or less, more preferably 10 to 28 mN / m. When the average surface free energy of the photoconductor during image formation exceeds 32 mN / m, the frictional force between the photoconductor and the cleaning blade increases, and the photoconductor and the cleaning blade are easily worn. This is not preferable because it is likely to cause cleaning failure and abnormal noise. Even if the average surface free energy is less than or equal to 32 mN / m, if there is a distribution of surface free energy, poor cleaning and abnormal noise are likely to occur, and the variation in surface free energy becomes a problem as the surface free energy decreases. . In the image forming apparatus of the present invention, the difference between the maximum value and the minimum value of the surface free energy on the surface of the photoreceptor during image formation is 5 mN / m or less, preferably 4 mN / m or less, more preferably 3 mN / m or less.

Since the surface free energy on the surface of the photoreceptor in the image forming apparatus of the present invention is leveled by the cleaning blade, there is little unevenness in the rotation direction of the photoreceptor. For this reason, when measuring with 4 or more types of solvent with the preferable measuring method of surface free energy, it is preferable to measure a contact angle along the circumferential direction of a photoreceptor.
The area for determining the surface free energy distribution on the surface of the photoreceptor of the present invention is performed for each of the plurality of divided areas in a direction perpendicular to the rotation direction of the photoreceptor, and the width of the divided areas is 50 mm or less. Preferably it is 30 mm or less, More preferably, it is 5-25 mm. If the width of the divided region exceeds 50 mm, it is too wide, and there is a high possibility that there are a plurality of locations where surface free energy variations of 5 mN / m or more are present in the region.

  Lubricating substances externally added to the toner used in the image forming apparatus of the present invention include fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride, zinc stearate, aluminum stearate, lead stearate, magnesium stearate, oleic acid Metal soap such as zinc can be exemplified, and metal soap that is easy to migrate from the toner to the photoreceptor and spread on the photoreceptor is preferable. Economic, safety of substances generated by decomposition due to charging, etc., and to the photoreceptor In view of the influence of the above, zinc stearate is most preferable. The external addition amount of the lubricating substance is usually 0.01 to 0.5% by weight, preferably 0.02 to 0.3% by weight, based on the toner. If the amount of the external addition of the lubricating substance is less than 0.01% by weight with respect to the toner, the amount of the lubricating substance that can be transferred to the photoreceptor is small, and thus the surface free energy tends to vary, which is not preferable. Since the surface free energy of the photoconductor used in the image forming apparatus of the present invention is essentially high, if the amount of the lubricating material supplied from the toner is small, the surface free energy variation on the surface of the photoconductor tends to become very large. It is easy to lead to deterioration of image quality and generation of abnormal noise. If the external addition amount of the lubricating substance is more than 0.5% by weight based on the toner, problems with the toner charging property are likely to occur, which is not preferable.

  An excellent image quality can be ensured whatever the average particle diameter of the toner used in the image forming apparatus of the present invention is. However, even with toner of 7 μm or less, preferably 6 μm or less, cleaning is possible. Since abnormal images due to defects can be suppressed, image formation with high image quality can be realized.

  In the image forming apparatus of the present invention, if the toner externally added with a lubricating substance does not adhere to the photoreceptor surface, the lubricating substance does not adhere to the photoreceptor surface, and the surface free energy on the photoreceptor surface cannot be reduced. . For this reason, unless the device for adhering toner is applied to the entire surface of the photoconductor, the average surface free energy of the photoconductor cannot be reduced to 32 mN / m or less depending on the image formed by the user. It is difficult to make the difference between the maximum value and the minimum value of the surface free energy on the surface of the photosensitive member 5 mN / m or less, and it is not preferable because abnormal images and abnormal sounds due to poor cleaning are easily caused.

  Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-221769, a plurality of regions are divided in a direction perpendicular to the developer transport direction of the photoreceptor, and an image area ratio for each divided region is obtained. It is preferable that the surface free energy on the surface of the photosensitive member can be kept constant by calculating and integrating and outputting a solid image on the entire surface of the photosensitive member according to the comparison result and cleaning it without performing transfer. However, consumption of toner should be avoided as much as possible even though toner is originally the property of the user and no image is formed. Therefore, the toner used for controlling the surface free energy of the photoreceptor can be changed by changing the image area to be output to each area according to the integrated amount of the image area for each divided area, and cleaning without transferring. It is very preferable that the average surface free energy of the photoconductor is 32 mN / m or less and the difference between the maximum value and the minimum value is 5 mN / m or less. In this case, as the area to be divided, the larger the image area, the better. However, in reality, the width of the area is 50 mm or less, preferably 30 mm or less, and more preferably 1 to 25 mm. If the width of the divided region exceeds 50 mm, the surface free energy tends to vary, and the toner consumption tends to increase, which is not preferable.

  In the image forming apparatus of the present invention, in order to control the surface free energy of the photosensitive member, the image area to be output to each region is changed according to the integrated amount of the image area for each divided region, and transfer is not performed. The cleaning may be performed only when the difference between the integrated amounts reaches a threshold value or more, but it is also performed periodically every 2000 sheets of image formation, preferably 1500 sheets or less, more preferably every 100 to 1000 sheets. It is preferable that the surface free energy of the photoreceptor can be reliably controlled.

  Although the highest resolution that can be used in the present invention for image formation by the image forming apparatus is whatever the resolution, high-quality image formation can be performed. In particular, high-resolution image formation of 1000 dpi or more, preferably 1200 dpi or more. In this case, high quality image formation becomes possible and the effect is high.

There are two methods for cleaning the toner on the photosensitive member by setting one cleaning blade in the reverse rotation direction (counter) or the forward rotation direction (leading) with respect to the rotation direction of the photosensitive member. However, if necessary, a cleaning brush such as polyester fiber or nylon fiber is used in combination.
Since the blade cleaning method is advantageous for downsizing the image forming apparatus, it is adopted in most image forming apparatuses.
In the blade cleaning method, when the cleaning blade is installed in the counter direction with respect to the rotation direction of the photosensitive member, the biting into the photosensitive member is increased and the toner cleaning performance can be improved.

For the cleaning blade, an elastic plate having a JIS-A hardness of about 70 to 80 degrees and a rebound resilience of about 30 to 60% is cut into a strip shape having a width of 1.5 mm to 3 mm, and is made of aluminum or iron. Used by attaching to a plate-like support substrate.
At present, polyurethane rubber for a cleaning blade that is preferably used generally tends to be in close contact with a photoreceptor made of polycarbonate resin, and the frictional resistance between the photoreceptor and the blade is extremely large.

Examples of the elastic body used in the cleaning blade include polyurethane rubber, silicone rubber, fluorine rubber, chloroprene rubber, and neoprene rubber. Polyurethane rubber is preferably used from the viewpoint of durability and cleaning resilience characteristics. Polyurethane rubber is mainly composed of polyol, isocyanate, and curing agent.
Polyurethane rubber is prepared by mixing dehydrated polyol and isocyanate, adding a curing agent to the prepolymer obtained by reacting at a temperature of 70 to 140 (° C) for about 100 minutes, and heating to 140 to 160 ° C in advance. Place in the mold of the placed molding machine and cure for 50-60 minutes. Then, it is obtained by taking out from a metal mold | die and cutting with a cutting machine to a required magnitude | size.

According to the first aspect of the present invention, the surface free energy on the surface of the photoconductor during image formation is low and the variation thereof is small. Therefore, image formation capable of forming a high-quality image without generating an abnormal image due to poor cleaning. An apparatus can be provided.
According to the second aspect, since the surface free energy of each region of the photoconductor can be managed, it is possible to provide an image forming apparatus capable of forming a high quality image without generating an abnormal image due to poor cleaning. .
According to the third aspect of the present invention, it is possible to provide an image forming apparatus that can easily reduce the surface free energy of each region of the photosensitive member and can form a high-quality image without generating an abnormal image due to poor cleaning. it can.
According to the fourth and fifth aspects, since the surface free energy of the photosensitive member can be accurately obtained, an image forming apparatus capable of forming a high-quality image without generating an abnormal image due to poor cleaning. Can be provided.

According to the sixth to ninth aspects, since the surface free energy of the photosensitive member can be controlled to be low and the variation can be controlled, image formation capable of forming a high-quality image without generating an abnormal image due to poor cleaning. An apparatus can be provided.
According to the tenth aspect, since it is possible to reliably control the surface free energy of the photosensitive member to be low and to reduce variation, it is possible to form a high-quality image without generating an abnormal image due to poor cleaning. Image forming apparatus can be provided.
According to the eleventh aspect, it is possible to provide an image forming apparatus capable of forming a high-quality image even when a small-diameter toner capable of forming a high-definition and high-quality image is used.
According to the twelfth aspect, it is possible to provide an image forming apparatus capable of forming a high-resolution and high-quality image without generating an abnormal image.
According to the thirteenth aspect, it is possible to provide an image forming apparatus capable of forming a high-quality color image without generating an abnormal image.
According to the fourteenth aspect, it is possible to provide a process cartridge capable of forming a high-quality image without generating an abnormal image.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic configuration diagram of a small color printer, which is an example of an image forming apparatus according to the present invention.
Reference numeral A in the figure is the main body of the printer. In the apparatus main body A, a transfer material conveyance path P is provided obliquely from the lower right to the upper left in the drawing.
On the transfer material conveyance path P, four monochrome image forming means 10Y, 10M, 10C, and 10B of yellow, magenta, cyan, and black are arranged in order from the lower right to the upper left along the conveyance path P to form a tandem type. Prepare. Each monochromatic image forming means 10 is composed of photosensitive units 12Y, 12M, 12C, and 12B and developing units 13Y, 13M, 13C, and 13B, and is detachable from the apparatus main body A. More specifically, each of the photoconductor units described later is provided with drum-like photoconductors 14Y, 14M, 14C, and 14B.

On such monochromatic image forming means 10Y, 10M, 10C and 10B, a writing unit 16 which will be described in detail later is provided obliquely along the monochromatic image forming means 10.
On the other hand, an endless belt-shaped transfer material carrier 18 is stretched between the monochrome image forming means 10Y, 10M, 10C, and 10B with the transfer material conveyance path P interposed therebetween. In the illustrated example, the transfer material carrier 18 is wound around four support rollers 19 and is in contact with the photoreceptors 14Y, 14M, 14C, and 14B, and a part of the transfer material carrier 18 is provided along the transfer material conveyance path P. The apparatus can be rotated and conveyed counterclockwise in the figure.
Inside the transfer material carrier 18, backup rollers 20Y, 20M, 20C, and 20B and transfer brushes 21Y, 21M, 21C, and 21B are arranged corresponding to the respective photoreceptors 14Y, 14M, 14C, and 14B. The backup rollers 20Y, 20M, 20C, and 20B bring the transfer material carrier 18 and the transfer material into close contact with the photoreceptors 14Y, 14M, 14C, and 14B. The transfer brushes 21Y, 21M, 21C, and 21B are supplied with a transfer bias from a power source (not shown). In the illustrated example, it is a transfer brush, but it may be a non-contact charger.

Along the transfer material conveyance path P, a registration roller pair 23 is provided at an upstream position of the transfer material carrier 18 and a fixing unit 24 is provided at a downstream position. The fixing unit 24 is configured by pressing a pressure roller 26 against a fixing belt 25 that is an endless belt, and a discharge roller pair 27 at an outlet.
At the downstream position of the fixing unit 24, a reversing unit 29 is provided attached to the apparatus main body A. The reversing unit 29 discharges the transfer material as it is, reverses and discharges it, or returns it to the apparatus main body A again.
Further, a reverse discharge path P1 is formed at a downstream position of the fixing unit 24 from the transfer material conveyance path P, and the transfer material is discharged to the discharge stack section 30 on the apparatus main body A. A discharge roller pair 31 is provided.

On the other hand, below the transfer material carrier 18, a refeed unit 33 for guiding and refeeding the transfer material reversed by the reversing unit 29 along the extending direction between the pair of guide plates 32. Place it diagonally.
Below the re-feed unit 33, the paper feed cassettes 34 are provided in two upper and lower stages. In the paper feed cassette 34, transfer materials such as paper and OHP film having different sizes are stacked and stored. Then, a paper feeding unit 35 for separating and feeding the transfer materials one by one is provided.
On the right side of the sheet feeding unit 35 in the drawing, the transfer material fed from the sheet feeding unit 35 and the transfer material re-fed through the refeed unit 33 are guided to the registration roller pair 23 in the transfer material conveyance path P. A paper feed path P2 is provided.
Further, a manual feed section is provided on the right side of the apparatus main body A in the figure, and a manual feed tray 36 is attached to the manual feed section so as to be freely opened and closed. The manual feed portion is provided with a paper feed portion 37 that separates and feeds the transfer materials on the manual feed tray 36 one by one, and manually feeds the transfer material fed from the paper feed portion 37 to the registration roller pair 23. A paper path P3 is provided.

  When an image is recorded on a transfer material using this color printer, for example, the paper feed unit 35 is selectively driven based on a signal from the host, and the transfer materials in one paper feed cassette 34 are moved one by one. The paper is separated and fed out, put into the paper feed path P2, and abutted against the registration roller pair 23 and stopped. Alternatively, the manual paper feed unit 37 is driven, the transfer materials on the manual tray 36 are separated one by one and fed out, put into the manual paper feed path P3, and abutted against the registration roller pair 23 and stopped.

On the other hand, in each of the monochromatic image forming means 10Y, 10M, 10C, and 10B, the individual photoconductors 14Y, 14M, 14C, and 14B are rotated to form yellow, magenta, cyan, and black monochromatic toner images on the respective photoconductors. To do. At the same time, one of the support rollers 19 is rotationally driven by a drive motor (not shown), the other support rollers 19 are driven to rotate, and the transfer material carrier 18 is rotated and conveyed.
Then, the registration roller pair 23 is rotated in synchronization with the rotation of the photosensitive member, the transfer material is put into the transfer material conveyance path P, and the monochromatic image forming means 10Y, 10M, 10C, 10B and the transfer material carrier 18 are aligned. In between, the transfer material is conveyed by the rotational conveyance of the transfer material carrier 18. Along with the conveyance, the single color toner images on the individual photoconductors 14Y, 14M, 14C, and 14B are transferred by the transfer brushes 21Y, 21M, 21C, and 21B, and the combined full color image is recorded on the transfer material.

The transfer material after the image transfer is sent to the fixing unit 24 to fix the transferred image, and is then discharged by the discharge roller pair 27. When the paper is discharged in the face-down state, it is switched by a switching claw (not shown), led to the reverse paper discharge path P1, discharged by the discharge roller pair 31, and stacked on the paper discharge stack unit 30 in page order.
When discharging in the face-up state, it is switched by a switching claw (not shown), led to the reversing unit 29, and discharged straight as it is.

Similarly, when recording on the back side of a transfer material on which one side has been recorded, it is similarly switched by a switching claw (not shown) and led to the reversing unit 29, reversed by the reversing unit 29, and then led to the refeed unit 33. Then, the sheet is again put in the paper feed path P2 and abutted against the registration roller pair 23 and stopped.
Then, the sheet is again put into the transfer material conveyance path P, sent between the monochrome image forming means 10Y, 10M, 10C, and 10B and the transfer material carrier 18 to record the composite full color image on the back surface, and then the fixing unit. The sheet is fixed at 24 and discharged, for example, by the discharge roller pair 31 through the reverse discharge path P <b> 1 and stacked on the discharge stack unit 30.

Next, the individual monochromatic image forming means 10Y, 10M, 10C, and 10B will be described in detail below.
As shown in FIG. 2, in each of the photoconductor units 12 (12Y, 12M, 12C, and 12B) of the individual monochromatic image forming means 10Y, 10M, 10C, and 10B, a drum-like photoconductor 14 (14Y, 14M), which will be described later in detail. A charging device 40 and a cleaning device 41 are provided around 14C and 14B).
In the charging device 40, a roller-shaped charging member 42 is disposed in the vicinity of the photosensitive member 14, and the photosensitive member 14 is charged by applying a charging bias between the charging member 42 and the photosensitive member 14. The charging member 42 is brought into contact with a cleaner 43 made of sponge or the like for cleaning the surface thereof. In the illustrated example, the charging member 42 has a roller shape, but may be a known non-contact charger.

The cleaning device 41 includes a fur brush 44 that rotates freely in contact with the outer periphery of the photoconductor 14, and a cleaning blade 45 made of polyurethane rubber, for example, with the tip pressed against the photoconductor 14. Reference numeral 46 in the drawing is a recovery screw.
Then, the fur brush 44 is rotated in the counter direction with respect to the photoconductor 14 to remove transfer residual toner remaining on the photoconductor 14 after image transfer. Thereafter, the toner remaining on the photoreceptor 14 is scraped off and removed by the cleaning blade 45. In the illustrated example, the toner removed by the fur brush 44 and the cleaning blade 45 is discharged from the monochromatic image forming units 10Y, 10M, 10C, and 10B by the rotation of the collection screw 46, and is not shown in FIG. The toner passes through the waste toner transport path and is transported to the waste toner bottle 49.
Each photoconductor unit 12 is provided with a portion 47 serving as a main positioning reference and two portions 48 serving as a secondary positioning reference so that they can be accurately positioned and attached to the apparatus main body A. To.

  On the other hand, in each of the developing units 13Y, 13M, 13C, and 13B that are the developing devices of the individual monochromatic image forming units 10Y, 10M, 10C, and 10B, a single component developer may be used. And a two-component developer comprising a non-magnetic toner. As the non-magnetic toner, yellow toner is used in the developing unit 13Y, magenta is used in the developing unit 13M, cyan is used in the developing unit 13C, and black toner is used in the developing unit 13B.

  In each of the monochromatic image forming means 10Y, 10M, 10C, and 10B, as the photoconductor 14 rotates in the clockwise direction in FIG. 2, a charging bias is applied by the charging device 40 to make the surface of the photoconductor 14 uniform. Is charged. Next, writing is performed with scanning light from the writing unit 16 to form an electrostatic latent image on the surface of the photoreceptor 14. Then, the developing unit 13 (13Y, 13M, 13C, and 13B) attaches toner to develop the electrostatic latent image, and forms a monochromatic toner image on the photoconductor 14.

A monochrome single-color toner image is formed on the photosensitive member 14Y of the single-color image forming unit 10Y, a magenta single-color toner image is formed on the photosensitive member 14M of the single-color image forming unit 10M, and a cyan single color is printed on the photosensitive member 14C of the single-color image forming unit 10C. A black single color toner image is formed on the photoreceptor 14B of the single color image forming unit 10B.
Although not shown, each developing unit 13 includes a toner density detection sensor.

Next, the writing unit 16 will be described in detail below.
As shown in FIG. 3, the writing unit 16 is provided with two six-sided rotary polygon mirrors 51 and 52 that can be rotated by a polygon motor 50. Then, the light emitted from a laser diode (not shown) is reflected by being divided into scanning light for yellow, magenta, cyan, and black by the rotation of the rotary polygon mirrors 51 and 52.

The yellow scanning light is reflected by the mirror 54 through the fθ lens 53, passes through the long WTL 55, is reflected by the mirrors 56 and 57, and irradiates the photoreceptor 14Y of the photoreceptor unit 12Y.
The magenta scanning light is reflected by the mirror 58 through the fθ lens 53, passes through the long WTL 59, is reflected by the mirrors 60 and 61, and irradiates the photoreceptor 14M of the photoreceptor unit 12M.
The scanning light for cyan is reflected by the mirror 63 through the fθ lens 62, is reflected by the mirrors 65 and 66 through the long WTL 64, and irradiates the photoreceptor 14C of the photoreceptor unit 12C.
The scanning light for black is reflected by the mirror 67 through the fθ lens 62, is reflected by the mirrors 69 and 70 through the long WTL 68, and irradiates the photoreceptor 14B of the photoreceptor unit 12B.

FIG. 5 shows a schematic diagram of a control block of the printer.
As can be seen from FIG. 5, a main control board 80 is provided in the laser printer. The main control board 80 is supplied with power from a power supply unit 81 and is connected to a personal computer 83 via a controller board 82 via a network or the like. An operation / display panel 84 is also connected to the controller board 82.

The main control board 80 is connected to, for example, the writing control unit 85 to control the writing unit 16, drives the polygon motor 86 of the writing unit 16, and drives the photosensitive member 14 and the developing device 13. Is driven, a fixing / feeding drive motor 88 for driving the fixing device 24 and the rollers of the sheet feeding system is driven, and various clutches such as the developing clutch 94 are turned on and off.
On the other hand, various detection sensors are operated to control the high-voltage power supply unit 89 to apply various bias voltages, to control the toner supply motor 91 based on the output signal of the toner density sensor 90 of the developing unit 13, and to the fixing device 24. The fixing heater 93 is turned on / off based on the output signal of the thermistor 92.

  When an image is formed on the transfer sheet using this laser printer, the photosensitive member 14 is rotated by driving the photosensitive member / development driving motor 87 based on a signal from the personal computer 83 as a host. As the photosensitive member 14 rotates, the surface thereof is first uniformly charged by the charging roller 40 by applying a charging bias by the high-voltage power supply unit 89, and then the writing control unit 85 is activated and the writing device 16 operates the writing light L Is written to form an electrostatic latent image on the photosensitive member 14. Subsequently, by simultaneously driving the developing unit 13 based on the photoconductor / development driving motor 87, the developing roller provided in the developing unit 13 is driven, and a developing bias is applied to the photoconductor 14 by applying a developing bias by the high-voltage power supply unit 89. A toner is attached, and the electrostatic latent image on the photoconductor 14 is visualized to form a toner image on the photoconductor 14.

Next, the photoreceptor 14 used in each photoreceptor unit 12 will be described in detail below.
For example, as shown in FIG. 4A or 4B, the photoconductor 14 is formed by forming a photoconductive layer 73 on a conductive support 72 and providing a protective layer 74 on the photoconductive layer 73. . The photosensitive layer 73 is formed of the charge generation layer 75 and the charge transport layer 76, but the charge transport layer 76 may be provided on the charge generation layer 75 as shown in FIG. The charge generation layer 75 may be provided on the charge transport layer 76 as in B).

The conductive support 72 has a volume resistance of 10 ¹⁰ Ωcm or less, such as a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, or a metal oxide such as tin oxide or indium oxide. Surface of the product by cutting, super-finishing, polishing, etc. after forming a plate of aluminum or aluminum alloy, nickel, stainless steel, etc. It consists of a treated tube.

  The charge generation layer 75 is a layer mainly composed of a charge generation material. As the charge generation material, an inorganic or organic material is used, and typical examples include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squaric. Examples include acid dyes, phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes, selenium, selenium-tellurium alloys, selenium-arsenic alloys, and amorphous silicon. These charge generation materials may be used alone or in combination of two or more.

  The charge generation layer 75 is obtained by dispersing the charge generation material together with a binder resin, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, 2-butanone, dichloroethane, or the like by a ball mill, an attritor, a sand mill, or the like, and applying a dispersion. Can be formed. Application is performed by dip coating, spray coating, bead coating, or the like.

The binder resin used as appropriate is polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, silicone resin, acrylic resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl ketone resin, polystyrene, resin, polyacrylic. Examples thereof include resins and polyamide resins. The amount of the binder resin is suitably 0 to 2 parts with respect to 1 part of the charge generating material on a weight basis.
The charge generation layer 75 can also be formed by a known vacuum thin film manufacturing method. The film thickness of the charge generation layer 75 is usually 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer 76 can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed.
Among charge transport materials, low molecular charge transport materials include electron transport materials and hole transport materials. Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide. These electron transport materials may be used alone or as a mixture of two or more.

  Examples of the hole transport material include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane. , Styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These hole transport materials may be used alone or as a mixture of two or more.

  When a polymer charge transport material is used as the charge transport material, the charge transport layer 76 may be formed by dissolving or dispersing in a suitable solvent, coating and drying the solution. The polymer charge transport material may be a material having a charge transporting substituent in the main chain or side chain in the low molecular charge transport material. Furthermore, if necessary, an appropriate amount of a binder resin, a low molecular charge transport material, a plasticizer, a leveling agent, a lubricating substance, or the like can be added to the polymer charge transport material.

  Examples of the binder resin used for the charge transport layer 76 together with the charge transport material include polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, and polyvinyl chloride resin. , Vinyl chloride-vinyl acetate copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, acrylic Examples thereof include thermoplastic or thermosetting resins such as resins, silicone resins, epoxy resins, melamine resins, urethane resins, phenol resins, and alkyd resins.

Examples of the solvent include tetrahydrofuran, dioxane, toluene, 2-butanone, monochlorobenzene, dichloroethane, methylene chloride and the like.
The thickness of the charge transport layer 76 may be appropriately selected in the range of 5 to 30 μm according to desired photoreceptor characteristics.
Examples of the plasticizer added to the charge transport layer 76 as desired include general-purpose plasticizers such as dibutyl phthalate and dioctyl phthalate, and the amount used is 0 to 30 based on the weight of the binder resin. % Is appropriate.
Examples of the leveling agent that is optionally added to the charge transport layer 76 include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. About 0 to 1% is suitable with respect to binder resin on a weight basis.

The amount of the charge transport material contained in the photosensitive layer 73 is preferably 40% by weight or more of the charge transport layer 76. If it is less than 40% by weight, a sufficient light decay time in the high-speed electrophotographic process cannot be obtained in pulsed light exposure in laser writing on the photoreceptor, which is not preferable.
The charge transport layer mobility in the photoreceptor 14 is 3 × 10 ⁻⁵ cm ² / V · under the condition of the charge transport layer electric field strength in the range of 2.5 × 10 ^{5 to} 5.5 × 10 ⁵ V / cm. It is preferably at least s, more preferably at least 7 × 10 ⁻⁵ cm ² / V · s. This mobility can be adjusted as appropriate to achieve this under each use condition. This mobility may be obtained by a conventionally known TOF method.

An undercoat layer can be formed on the photoreceptor 14 between the conductive support 72 and the photosensitive layer 73. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is applied using a solvent, the resin is a resin having high resistance to general organic solvents. Is desirable.
Examples of such resins include polyvinyl alcohol resins, casein, water-soluble resins such as sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane resins, melamine resins, alkyd-melamine resins, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.
Further, fine powder of metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer in order to prevent moire and reduce residual potential.

This undercoat layer can be formed by using an appropriate solvent and coating method in the same manner as the photosensitive layer 73 described above. Furthermore, it is also useful to use a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like as the undercoat layer.
In addition, the undercoat layer which the _Al 2 _{O 3} was formed by those anodized, organic matter such as polyparaxylylene _{(parylene), SiO, SnO 2, TiO} 2, ITO, Ce0 2 , etc. inorganic It is also effective to form the film by a vacuum thin film manufacturing method. The thickness of the undercoat layer is suitably from 0 to 5 μm.

On the photoreceptor 14, a protective layer 74 containing a filler is formed on the photosensitive layer 73 as a surface layer for the purpose of protecting the photosensitive layer 73 and improving durability.
Materials used for the protective layer 74 include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin, phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, polyacrylate. Resin, polyallylsulfone resin, polybutylene resin, polybutylene terephthalate resin, polycarbonate resin, polyethersulfone resin, polyether resin, polyethylene terephthalate resin, polyimide resin, acrylic resin, polymethylpentene resin, polypropylene resin, polyphenylene oxide resin, polysulfone resin , AS resin, AB resin, BS resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin and the like. A filler is added to the protective layer 5 for the purpose of improving wear resistance.

Examples of the filler include fluorine resins such as polytetrafluoroethylene, silicone resins, and those obtained by dispersing inorganic materials such as titanium oxide, tin oxide, and potassium titanate in these resins.
The amount of filler added to the protective layer 74 is usually 10 to 40%, preferably 20 to 30% on a weight basis. If the amount of the filler is less than 10%, the wear is large and the durability is inferior, and if it exceeds 40%, the increase in the bright part potential at the time of exposure becomes remarkable, and the decrease in sensitivity cannot be ignored.
Furthermore, a dispersion aid can be added to the protective layer 74 in order to improve the dispersibility of the filler. As the added dispersion aid, those used in paints and the like can be used as appropriate, and the amount thereof is usually 0.5 to 4%, preferably 1 to 2% based on the amount of filler contained on a weight basis. .
It is also effective to add the above-described charge transport material to the protective layer 74, and an antioxidant can be added as necessary. The antioxidant will be described later.

As a method for forming the protective layer 74, a normal coating method such as a spray method is employed. The thickness of the protective layer 74 is 0.5 to 10 μm, preferably about 4 to 6 μm.
It is important for the wear resistance and image characteristics that the form of the filler in the protective layer 74 be constant. In other words, the presence of the protective layer 74 does not impair the sensitivity and electrostatic stability of the photosensitive layer 73, and does not impair the fineness of the exposure. It can contribute.
In order to satisfy this requirement, it is necessary that the filler content in an arbitrary cross section of the protective layer 74 is 3 to 5% as an area occupation ratio in the plane. In addition, the filler contained in the protective layer has a peak at 0.2 to 0.3 μm in the particle size distribution including secondary particles, and is occupied by a filler having a particle size of 0.3 μm or more in an arbitrary cross section of the protective layer 74. The area needs to be 10 to 30% of the total filler occupation area in the plane. As a result of investigations by the inventors, when the above range is not satisfied, it was confirmed that the residual potential increased, the sensitivity decreased, the resolution decreased, the wear resistance decreased, and abnormal image generation due to filming occurred.
The control of the form of the filler in the protective layer 74 is possible by the particle size and distribution of the filler material used, the coating liquid formulation, and the coating apparatus, and the use of a dispersion aid is effective.

  It is also possible to form another intermediate layer between the photosensitive layer 73 and the protective layer 74. In the intermediate layer, a binder resin is generally used as a main component. Examples of the binder resin include polyamide resin, alcohol-soluble nylon, water-soluble polyvinyl butyral resin, polyvinyl butyral resin, and polyvinyl alcohol resin. As a method for forming the intermediate layer, the above-described normal coating method is employed. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

  In order to improve environmental resistance, antioxidants, plasticizers, lubricants, UV absorbers, low-molecular charge transporting substances and leveling agents are added to each layer, especially for the purpose of preventing a decrease in sensitivity and an increase in residual potential. can do.

  Examples of the antioxidant that can be added to each layer include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl- 3- (4-hydroxy-3,5-di-tert-butylphenol), 2,2-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2-methylene-bis- (4-ethyl) -6-tert-butylphenol), 4,4-thiobis- (3-methyl-6-tert-butylphenol), 4,4-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3- Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl Benzene, tetrakis- [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, bis [3,3-bis (4-hydroxy-3-tert-butylphenyl) butyric Acid] phenol compounds such as glycol ester, tocopherols, N-phenyl-N-isopropyl-p-phenylenediamine, N, N-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec Paraphenylenediamines such as -butyl-p-phenylenediamine, N, N-di-isopropyl-p-phenylenediamine, N, N-dimethyl-N, N-di-t-butyl-p-phenylenediamine, 5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, -Hydroquinones such as dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-methylhydroquinone, dilauryl-3,3-thiodipropionate, distearyl- Organic sulfur compounds such as 3,3-thiodipropionate, ditetradecyl-3,3-thiodipropionate, triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, And organic phosphorus compounds such as tri (2,4-dibutylphenoxy) phosphine.

  Examples of plasticizers that can be added to each layer include triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate , Phosphate ester plasticizers such as triphenyl phosphate, dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-phthalate n-octyl, dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl phthalate Phthalate ester plasticizers such as decyl, dibutyl fumarate, dioctyl fumarate, aromatic carboxylic acid ester plasticizers such as trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and dibutyl adipate , Di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, n-octyl adipate, diisodecyl adipate, dicapryl adipate, di-2-azelate Ethylhexyl, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, tetrahydrophthalic acid Dioctyl, Tetrahi Aliphatic dibasic acid ester plasticizers such as di-n-octyl lophthalate, fatty acids such as butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin Ester derivative plasticizer, methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate, epoxidized soybean oil, epoxidized linseed oil, epoxy butyl stearate Epoxy plasticizers such as decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, Dihydric alcohol ester plasticizers such as diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate, chlorine-containing plasticizers such as chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, and methoxychlorinated fatty acid methyl, polypropylene Polyester plasticizers such as adipate, polypropylene sebacate, polyester, acetylated polyester, p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide , Sulfonic acid derivative plasticizers such as p-toluenesulfone-N-cyclohexylamide, triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, Citric acid derivative plasticizers such as tri-2-ethylhexyl citrate, acetylcitrate-n-octyldecyl, etc., terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietic acid Etc.

  Examples of lubricants that can be added to each layer include hydrocarbon compounds such as liquid paraffin, paraffin wax, microwax, and low-polymerized polyethylene, and fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. Compounds such as fatty acid amide compounds such as stearylamide, palmitylamide, oleinamide, methylenebisstearoamide, ethylenebisstearoamide, lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, fatty acid polyglycol esters, etc. Ester compounds, alcohol compounds such as cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol, lead stearate, cadmium stearate, barium stearate, Calcium stearic acid, zinc stearate, metal soaps such as magnesium stearate, carnauba wax, candelilla wax, beeswax, spermaceti, insect wax, natural waxes such as montan wax, other silicone compounds, fluorine compounds, and the like.

  Examples of ultraviolet absorbers that can be added to each layer include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2,4-trihydroxybenzophenone, 2,2,4,4-tetrahydroxybenzophenone, and 2,2-dihydroxy. Benzophenone UV absorbers such as 4-methoxybenzophenone, salsylate UV absorbers such as phenyl salsylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate, (2-hydroxy Phenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy3-tertiarybutyl 5-methylphenyl) 5-chlorobenzotriazole, etc. Benzotria UV absorbers, cyanoacrylate UV absorbers such as ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate, nickel (2,2 thiobis (4-t- Octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and other quencher (metal complex) UV absorbers, bis (2,2,6,6-tetramethyl-4- Piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] Ethyl] -4- [3- (3,5-di-t-butyl) 4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4 5] HALS (hindered amine) ultraviolet absorbers such as undecane-2,4-dione and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

In this way, the photosensitive layer 14 is formed with the photosensitive layer 73 and the protective layer 74 on the conductive support, and an undercoat layer and an intermediate layer are formed as desired, and the protective layer 74 contains a filler. , To improve wear resistance and improve durability. Furthermore, the photoreceptor 14 has excellent durability and stability even for high-speed electrophotographic processes by making the form of the filler in the protective layer 74 constant as described above, and wear resistance. It is an excellent photoreceptor 14. Further, by supplying a lubricating material such as zinc stearate onto the protective layer 74, it is possible to suppress filming in a state where the abrasion resistance is good. In the process, the toner adhesion on the photoconductor 14 during the non-image formation and the toner recovery operation in the cleaning unit are repeated, and this has an effect of suppressing the image flow while maintaining the wear resistance.
In the illustrated example, the photosensitive member 14 has a drum shape, but may similarly have a belt shape having a high surface hardness.

  The toner used in the present invention is externally added with 0.01 to 0.5% by weight of a lubricating substance (for example, zinc stearate). In this way, the lubricating material can be applied to the surface of the photoreceptor 14. In the above-described color printer, a charging bias is applied by, for example, the charging device 40 during image formation. At that time, discharge products such as ozone and nitrogen oxide are generated and adhere to the photoconductor 14, and transfer materials are formed. The image quality of the toner image recorded above is degraded. It has also been found that the surface layer of the photoconductor 14, which is an organic photoconductor, is oxidized by the discharge and wear proceeds. By forming a thin layer of a lubricating material on the photoconductor, the surface energy of the photoconductor 14 is reduced, filming is prevented and adhesion is difficult to adhere, and the lubricating material layer is a protective layer. It is possible to prevent oxidation of the surface layer of the photoreceptor due to electric discharge and reduce wear of the photoreceptor. By externally adding a lubricating substance to the toner, it is possible to reduce the size and cost by eliminating the need for a dedicated lubricating substance coating apparatus.

  The toner includes a binder resin, a colorant, and a charge control agent as main components, and other additives are added as necessary. Specific examples of the binder resin include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, and styrene-vinyl chloride copolymer. Styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) Polymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, Styrene-phenyl methacrylate copolymer, etc.), styrene-α -Styrenic resins such as methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer (monopolymer or copolymer containing styrene or styrene substitution product), vinyl chloride resin, rosin-modified maleic acid resin Phenyl resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral, and the like can be used.

As the colorant (for example, yellow, magenta, cyan and black) used for the toner, those known for toners can be used. The amount of the colorant is suitably from 0.1 to 15 parts by weight, more preferably from 0.15 to 9 parts by weight, based on 100 parts by weight of the binder resin.
Specific examples of the charge control agent include a nigrosine dye, a chromium-containing complex, a quaternary ammonium salt, and the like, which are properly used depending on the polarity of the toner particles. The amount of the charge control agent is 0.1 to 10 parts by weight, more preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the binder resin.

In addition, it is advantageous to add a fluidity imparting agent to the obtained toner particles. As the fluidity-imparting agent, fine particles of metal oxides such as silica, alumina, magnesia, zirconia, ferrite, magnetite and the like, and silane coupling agent, titanate coupling agent, zircoaluminate, quaternary ammonium salt, fatty acid, Examples thereof include those treated or coated with a treatment agent such as a fatty acid metal salt, a fluorine-based activator, a solvent, or a polymer. The addition amount of these fluidity imparting agents is preferably in the range of 0.1 to 7.0 parts by weight, particularly 0.2 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. These fluidity imparting agents have a particle size in the range of 0.01 to 3 μm.
Moreover, the above-mentioned thing is used as a lubricious substance.

  To externally add a fluidity-imparting agent and a lubricating substance to the toner particles, the toner particles are mixed with the fluidity-imparting agent and the lubricating substance, and the powder is moved in a fluid state at high speed by air current or mechanical force. To avoid crushing. Examples of the mixer include a high-speed flow type mixer such as a Henschel mixer and a UM mixer. The external addition of the fluidity-imparting agent and the lubricating substance to the toner particles can be performed in a plurality of times. However, since the lubricating substance needs to be efficiently transferred onto the photoreceptor, finally, It is preferable to add them alone or together with a fluidity-imparting agent.

  As a method for producing a toner for two-component developer, it can be produced by various known methods or a combination thereof. For example, in the kneading and pulverization method, a binder resin, a colorant such as carbon black, and necessary additives are dry-mixed, heated and melt-kneaded with an extruder or two-roll, three-roll, etc., and after cooling and solidification Then, the toner is pulverized by a pulverizer such as a jet mill and classified by an airflow classifier. In addition, a toner can be directly produced from a monomer, a colorant, and an additive by suspension polymerization or non-aqueous dispersion polymerization.

The carrier core material is generally made of itself or having a coating layer on the core material. The core material of the resin-coated carrier that can be used in the present invention is ferrite or magnetite. The particle size of the core material is 20 to 65 μm, preferably about 30 to 60 μm.
Fluorine-containing monomers used for carrier coating layer formation include vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinyl ether substituted with fluorine atoms, and vinyl ketone substituted with fluorine atoms. Examples of the polymer include vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, perfluoroalkyl vinyl ether-vinylidene fluoride-tetrafluoroethylene copolymer, and vinylidene fluoride. Polymers, tetrafluoroethylene copolymers, polymers containing vinyl ethers substituted with fluorine atoms, polymers containing vinyl ketones substituted with fluorine atoms, fluorinated alkyl copolymers Relate polymer, or a fluorinated alkyl methacrylate polymer.

Components copolymerized with the fluorine-containing monomer include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, and benzyl acrylate. Benzyl methacrylate, acrylic acid amide, methacrylic acid amide, cyclohexyl acrylate, cyclohexyl methacrylate, hydroxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, ethylene, propylene, and the like.
As a method for forming the coating layer, a resin may be applied to the surface of the carrier core particle by means of a spraying method, a dipping method, or the like, as in the past.

In the illustrated example described above, the case where the present invention is applied to a color printer has been described. However, the present invention can be similarly applied to a copying machine, a facsimile, and other image forming apparatuses. Further, the present invention can be applied not only to a full color but also to a two-color or monochrome image forming apparatus.
In the image image forming apparatus of the present invention, the electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means are integrally formed, and the image forming apparatus main body is formed. It may be mounted as a detachable process cartridge for an image forming apparatus.

FIG. 6 shows a control block diagram of charge exposure development different from the purpose of image formation.
In the figure, reference numeral 100 is a pixel number counting means for counting the number of pixels to be written, and 101 is an image area calculating means for calculating the image area based on the output of the pixel number counting means 100.
The image area of the image developed by the developing unit 13 and formed on the photoreceptor 14 can be calculated from the following equation.
[Image area] = [Count pixel count] × [1 pixel area]
Here, since the area of one pixel is determined in advance, the image area can be known by counting the number of written pixels by the pixel number counting means 100.
Then, according to the calculation result of the image area calculation unit 101, the charge exposure development execution unit 105 different from the image formation purpose is operated, and a developer is attached to the photoconductor 14 by the development unit 13 separately from the development purpose. Supply substances.

In the figure, reference numeral 102 denotes a counting means for counting the number of rotations or the rotation time of the photosensitive member 14, and 103 denotes a traveling area calculating means for calculating the traveling area of the photosensitive member 14 based on the output of the counting means 102.
The traveling area of the photoreceptor 14 can be calculated from the following equation.
[Traveling area] = [traveling distance] x [imaging width]
Here, since the image forming width is determined in advance, the traveling area can be known by obtaining the traveling distance.
The travel distance can be calculated from the following equation.
[Travel distance] = [counting rotation number of photoconductor] × [peripheral length of photoconductor] or [travel distance]
Here, since the circumference of the photoconductor 14 is determined in advance, the running distance can be known by counting the number of rotations of the photoconductor 14 by the counting means 102. The travel distance may be calculated by counting the rotation time based on the linear velocity of the photoreceptor 14.

The outputs of the image area calculating unit 101 and the traveling area calculating unit 103 are input to the image area rate calculating unit 104, and an image area ratio that is a ratio of the image area to the traveling area of the photoconductor 14 is calculated from the following equation.
[Image area ratio] = [Image area] / [Running area]
Then, based on the calculated image area ratio, the charged exposure development execution means 105 different from the purpose of image formation is operated, and a developer is attached to the photosensitive member 14 by the development unit 13 separately from the purpose of development. Supply.

FIG. 7 shows a flowchart of an example of charge exposure development different from the purpose of image formation.
When the controller 82 receives image data from the personal computer 83 connected via a network or the like, in step S1, the CPU of the main control board 80 is charged exposure different from the image forming purpose stored in the NVRAM (nonvolatile memory). The development conditions (exposure pattern for execution or non-execution) are read out. Next, in step S2, the pixel number counting means 100 starts counting the number of pixels P1 to Pn of the N-divided area in the direction orthogonal to the conveyance direction of the photosensitive member, and counts the rotation number or rotation time of the photosensitive member 102. Starts counting the number of rotations or the rotation time of the photosensitive member 14.
Subsequently, in step S3, the photosensitive member 14 is rotated, charging, writing, developing, transferring, cleaning, discharging, etc. are repeated to form a toner image on the photosensitive member 14, and the toner image is transferred to the transfer sheet. To record.

Then, after completing the image formation on the last transfer sheet of one job (from when the photosensitive member 14 starts rotating until it stops), in step S4, charge exposure development different from the image formation is executed. If it is determined whether or not to execute, the process proceeds to step S5, and the charge exposure development execution unit 105 different from the image formation purpose executes charge exposure development different from the image formation. In step S6, the rotation of the photosensitive member 14 is stopped. In other words, when it is necessary to execute charge exposure development different from image formation, the charge exposure development execution means 105 different from the image formation purpose develops the latent image corresponding to the last transfer sheet of one job. After the operation is completed, the developing unit 13 attaches a developer separately from the purpose of development and supplies a lubricating substance to the photosensitive member. When it is not necessary to execute the charge exposure development different from the image formation, the process proceeds from step S4 to step S6 as it is, and the rotation of the photosensitive member 14 is stopped.
In step S7, by storing it in the NVRAM, the charging exposure development condition different from the image forming purpose is updated, and the count values of the pixel number counting means 100 and the counting means 102 are cleared.

FIG. 8 shows an example of a flowchart for determining charging exposure development conditions different from the image forming purpose in step S7. First, the image area ratios H1 to Hn of the regions S1 to Sn divided into N in the direction perpendicular to the conveyance direction of the photosensitive member are calculated (step S8). Next, it is confirmed whether or not the minimum value Hmin of these H1 to Hn is smaller than a predetermined reference image area ratio Hs (step S9). If it is not Hmin> Hs, execution of charging exposure development different from the purpose of image formation by exposure development is determined for the region Sx where Hx <Hs among S1 to Sn (step S10).
After the completion of the next job, charging exposure development different from image formation is executed based on the charged exposure development condition different from the updated new image formation purpose. As described above, by controlling charging exposure and development conditions different from the image forming purpose from the previous job count result, the number of rotations of the photosensitive member 14 and the number of write pixels are counted in real time during the job. Control for determining charging exposure development conditions different from the purpose of image formation can be performed, and the load on the CPU can be greatly reduced and the program can be simplified.

By the way, the lubricating material transferred from the toner onto the photoconductor 14 is stretched out using the cleaning blade 28 of the cleaning device 14, and the lubricating material is uniformly applied to the surface of the photoconductor 14. Therefore, in an image forming apparatus using a contact type as the transfer device 13, the transfer device 13 is separated from the photosensitive member 14 during the charging exposure development operation different from the image forming purpose, or during the transfer operation. It is preferable to increase the supply efficiency of the lubricating substance by applying a reverse polarity bias voltage to prevent the toner from adhering to the transfer device 13.
Assuming that the image area ratio is the same as the transfer sheet area, even if the image area ratio is the same, if the transfer sheet size is different, the toner consumption will be different. However, by obtaining the image area ratio with respect to the traveling area of the photosensitive member 14 as described above, it is possible to form images on transfer sheets of various sizes, or to form images one by one or in large quantities continuously. In various cases, it is possible to more accurately detect the toner consumption amount and predict the influence on the photoreceptor wear.

FIG. 9 shows a flowchart of another example of charge exposure development different from the purpose of image formation.
In the example shown in FIG. 9, when image data is received, an image forming process such as charging / writing / developing / transfer / cleaning is started (step S11), and the counting of the number of pixels to be written is started. The rotation number or the rotation time is counted (step S12).
Next, it is determined whether the accumulated time from the start of the image forming operation, the accumulated rotational speed of the photosensitive member, or the accumulated number of images formed has passed a predetermined value (S13). It is determined whether or not to perform charge exposure development different from the image formation purpose from the charge exposure development conditions different from the purpose (S14), and if necessary, a charge exposure development operation different from the image formation purpose is executed (S14). S15). Then, the count value is cleared (S16), and each count is restarted.

The determination of whether to perform the charging exposure development operation different from the purpose of image formation is simple and preferably based on the cumulative number of image formations, 2000 images or less, preferably 1500 images or less, more preferably 100 to 1000. It is preferable to perform the process periodically for each sheet since the surface free energy of the photoreceptor can be reliably controlled.
When the image forming operation is completed (S17), the rotation of the photosensitive member 14 is stopped (S18), and the count value is cleared (S19).
In this way, the charge exposure development execution means 105 different from the purpose of image formation finishes the image forming operation for the previous transfer sheet in one job and before starting the image forming operation for the next transfer sheet. In addition, it is possible to supply a lubricant substance to the photoreceptor 14 by attaching a developer separately from the development purpose in the developing unit 13.

テトラヒドロフラン ２００部
保護層用塗工液
ビスフェノールＺ型ポリカーボネート
（帝人化成社製：Ｚポリカ Ｍｖ５万） １０部
下記構造の低分子電荷輸送物質 ７部

アルミナフィラー
（住友化学工業製ＡＡ−０２〜ＡＡ−１０、平均一次粒径：０．２〜１．０μｍ、
比抵抗≒（２．５〜４）×１０^１２（Ω・ｃｍ）） ５．３部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
分散助剤：（ＢＹＫ−Ｐ１０４ ビックケミージャパン製） ０．１２部 Next, specific examples will be described. All parts are parts by weight.
Example 1
A charge generation layer using a bisazo pigment as a charge generator is formed by laminating an undercoat layer in which titanium oxide is dispersed in an alkyd-melanin resin on an aluminum substrate (conductive support) having a diameter of 30 mm and a length of 340 mm. After the lamination, a charge transport layer by the following charge transport layer coating solution and a protective layer by the following protective layer application solution are applied in that order, and then dried, an undercoat layer of 3.5 μm, a charge of 0.15 μm Forty photoconductors comprising a generation layer, a 25 μm charge transport layer, and a protective layer of about 4.5 μm were prepared. At this time, the coating of the protective layer was performed by a spray method, and the others were performed by a dip coating method.
Coating liquid for charge transport layer Bisphenol Z-type polycarbonate (manufactured by Teijin Chemicals Ltd .: Z Polica Mv50,000) 10 parts Low molecular charge transport material with the following structure 8 parts

Tetrahydrofuran 200 parts Coating liquid for protective layer Bisphenol Z-type polycarbonate (manufactured by Teijin Chemicals Ltd .: Z Polyca Mv50,000) 10 parts 7 parts low molecular charge transport material with the following structure

Alumina filler (AA-02 to AA-10, manufactured by Sumitomo Chemical Co., Ltd., average primary particle size: 0.2 to 1.0 μm,
Specific resistance≈ (2.5-4) × 10 ¹² (Ω · cm)) 5.3 parts Tetrahydrofuran 400 parts Cyclohexanone 200 parts Dispersing aid: (BYK-P104, manufactured by Big Chemie Japan) 0.12 parts

The surface free energy of this photoconductor was measured at 14 points at intervals of 20 mm from the contact angle of diiodomethane, α-bromonaphthalene, glycerin and diethylene glycol from a point 45 mm from the end of the photoconductor.
When measuring the contact angle with diiodomethane, α-bromonaphthalene, glycerin, or diethylene glycol, measure by rotating the photoconductor so that the distance from the edge is constant and the location measured with each solvent is not measured with another solvent. did. The surface free energy of the photoreceptor measured from the contact angle of each solvent is 50.2 to 50.7 mN / m, and the difference between the maximum value and the minimum value of the surface free energy at 14 locations is 0.0 to 0.2 mN. / M.

  This photoreceptor is incorporated into an imagio Neo C325 (manufactured by Ricoh, tandem color image forming apparatus), and image formation is carried out using a toner having an average particle diameter of 6.4 μm and externally added with 0.16% by weight of zinc stearate. It was. As a cleaning means, a polyurethane cleaning blade having a rubber hardness (JIS-A) of 70, a rebound resilience of 40, and a thickness of 2 mm was brought into contact with the photoconductor in the counter direction. Two charts each having an average image area ratio of 6%, in which letters are arranged in an average, were formed to form a total of 70,000 images. During image formation, there are areas where the area is divided into 10 areas at intervals of 27 mm in a direction perpendicular to the longitudinal direction (rotation direction) of the photoreceptor, and the average image area ratios H1 to H10 in each area are 1.3% or less. In this case, the charging exposure development was performed only in that region, and the charging exposure development operation different from the image forming purpose for two rotations of the photosensitive member was executed.

  Specifically, when there is a region where the average image area ratio in the region is 1.3% or less at the end of one job, a horizontal line of 4 dots of 600 dpi is set to 32 dots for that region of the photoconductor. Ten charged exposure developments were carried out at intervals, and toner was supplied onto the photoreceptor. Separately from this, for every 500 sheets of image formation, 15 areas of an average image area ratio of each area of 2% or less were charged and developed by charging 15 lines of 1 dot of 4 dots of 600 dpi at intervals of 32 dots, and toner was applied to the photoreceptor. I tried to supply.

  When the surface free energy of each photoconductor for black, yellow, cyan, and magenta was measured, the average surface free energy of each photoconductor was 27.0, 26.4, 27.5, and 27.9 mN / m, respectively. The difference between the maximum value and the minimum value of the surface free energy of each photoconductor was 1.2, 1.6, 2.3, and 1.4 mN / m, respectively. When a halftone image of each color, a solid image, a grid image, and a landscape photograph taken with a digital still camera were imaged, a high quality image was obtained.

Example 2
In the first embodiment, instead of the chart with an average image area ratio of 6% in which characters are arranged on average, the left half shown in FIG. 10 is a chart in which image data is arranged and the right half is arranged with characters, and the left half is The average image area ratio is 20%, the right half has an average image area ratio of 2%, and the average image area ratio of the entire chart is about 10%. An image was formed.
When the surface free energy of each of the photoconductors for black, yellow, cyan, and magenta was measured in the same manner as in Example 1, the average surface free energy of each photoconductor was 26.8, 27.8, and 27.2, respectively. The difference between the maximum value and the minimum value of the surface free energy of each photoconductor was 3.9, 2.7, 4.2, and 2.1 mN / m, respectively. When a halftone image of each color, a solid image, a grid image, and a landscape photograph taken with a digital still camera were imaged, a high quality image was obtained.

Comparative Example 1
In Example 2, image formation was performed in the same manner as in Example 2 except that no charge exposure development without image formation was performed.
When the surface free energy of each of the photoconductors for black, yellow, cyan, and magenta was measured in the same manner as in Example 2, the average surface free energy of each photoconductor was 31.2, 28.8, and 29.4, respectively. 32.3 mN / m, and the difference between the maximum value and the minimum value of the surface free energy of each photoconductor was 7.5, 4.1, 8.7, and 5.95 mN / m, respectively. When a halftone image of each color was output, band-shaped density unevenness occurred in the black, cyan, and magenta images.

Example 3
In Example 1, an image was formed using a toner having an average particle diameter of 5.8 μm and externally added with 0.15% by weight of zinc stearate.
When the surface free energy of each of the photoconductors for black, yellow, cyan, and magenta was measured in the same manner as in Example 1, the average surface free energy of each photoconductor was 27.0, 27.5, and 27.4, respectively. The difference between the maximum value and the minimum value of the surface free energy of each photoconductor was 4.1, 3.3, 2.9, and 1.8 mN / m, respectively. When a halftone image of each color, a solid image, a grid image, and a landscape photograph taken with a digital still camera were imaged, a high quality image was obtained.

Example 4
In Example 3, the chart is a chart in which image data is arranged in the left half and characters in the right half are arranged in the left half shown in FIG. 10, the left half has an average image area ratio of 22% and the right half has an average image area ratio of 2%. The average image area ratio of the entire chart was about 10%, and image formation was performed in the same manner as in Example 3 except that 50,000 images were formed.
When the surface free energy of each of the photoconductors for black, yellow, cyan, and magenta was measured in the same manner as in Example 3, the average surface free energy of each photoconductor was 27.7, 28.8, and 28.3, respectively. 27.4 mN / m, and the difference between the maximum value and the minimum value of the surface free energy of each photoconductor was 2.9, 3.5, 3.3, and 4.0 mN / m, respectively. When a halftone image of each color, a solid image, a grid image, and a landscape photograph taken with a digital still camera were imaged, a high quality image was obtained.

Comparative Example 2
In Example 4, image formation was performed in the same manner as in Example 3 except that the charge exposure development without image formation was not performed. When the surface free energy of each of the photoconductors for black, yellow, cyan, and magenta was measured with 10,000 images formed, the average surface free energy of each photoconductor was 34.5, 28.0, 29. The difference between the maximum value and the minimum value of the surface free energy of each photoconductor was 12.1, 9.3, 15.2, and 6.1 mN / m, respectively. When a halftone image of each color was output, band-shaped density unevenness occurred in the black, yellow, cyan, and magenta images.

1 is an overall schematic configuration diagram of an example of an image forming apparatus according to the present invention. 2 is a cross-sectional view of a photoreceptor unit used in the image forming apparatus of the present invention. FIG. 2 is a schematic configuration diagram of a writing unit used in the image forming apparatus of the present invention. (A) is a partial cross-sectional configuration diagram of a photoconductor used in the present invention, and (B) is a partial cross-sectional configuration diagram of another photoconductor used in the present invention. FIG. 2 is a schematic control block diagram in the image forming apparatus of the present invention. FIG. 5 is a control block diagram of charge exposure development different from the image forming object of the present invention. It is an example of the flowchart of the charging exposure development different from the image formation purpose of the present invention. It is another example of the flowchart of the charging exposure development different from the image forming purpose of the present invention. It is another example of the flowchart of the charging exposure development different from the image forming purpose of the present invention. 6 is a chart used in Examples 2 and 4. It is explanatory drawing for description of a Young type | formula.

Explanation of symbols

10, 10Y, 10M, 10C, 10B Monochromatic image forming means 12, 12Y, 12M, 12C, 12B Photosensitive unit 13, 13Y, 13M, 13C, 13B Developing unit (developing device)
14, 14Y, 14M, 14C, 14B Photoconductor 16 Writing unit 18 Transfer material carrier 19 Support roller 20Y, 20M, 20C, 20B Backup roller 21Y, 21M, 21C, 21B Transfer brush 23 Register roller pair 24 Fixing unit 29 Reversing unit 33 Re-feed unit 34 Paper feed cassette 40 Charging device 41 Cleaning device 44 Fur brush 45 Cleaning blade 51, 52 Six-sided rotary polygon mirror 53, 62 fθ lens 54, 56, 57, 58, 60, 61, 63, 65, 66, 67, 69, 70 Mirror 72 Conductive support 73 Photosensitive layer 74 Protective layer 75 Charge generation layer 76 Charge transport layer 101 Image area calculation means 104 Image area rate calculation means 105 Charge exposure development execution different from the purpose of image formation means

Claims (14)

  Using a photoreceptor having a surface free energy of 45 mN / m or more and a toner externally added with a lubricant, the photoreceptor is charged, an electrostatic latent image is produced by exposure, and the electrostatic latent image is formed using the toner. In the image forming apparatus for developing an image by developing the image, the average of the surface free energy of the surface of the photoreceptor in the image forming area of the photoreceptor during image formation by the image forming apparatus is 32 mN / m or less, and the maximum value of the surface free energy Forming apparatus in which the difference between the minimum value and the minimum value is 5 mN / m or less.   2. The image forming apparatus according to claim 1, wherein the surface free energy of the surface of the photosensitive member during image formation is measured for each of the plurality of divided regions in a direction perpendicular to the rotation direction of the photosensitive member. An image forming apparatus having a width of 50 mm or less.   3. The image forming apparatus according to claim 1, wherein the lubricating substance externally added to the toner is a metal soap. 4. The image forming apparatus according to claim 1, wherein the surface free energy of the photosensitive member is measured by measuring a contact angle with a liquid in which each component of the surface free energy is known, and the following formula according to an extended Fowkes theory: (7) is a method for measuring the surface free energy of a solid, wherein the surface free energy is a value obtained by linear regression from contact angle data with four or more liquids. apparatus.

(However, in the formula, gamma _L is, .Ganma represents the surface free energy of the liquid represented by ^{_{γ a L + γ b L +}} γ C L a L is, .Ganma ^b representing the dispersive component of the surface free energy of the liquid _L represents a dipole component of the surface free energy of the liquid, γ ^C _L represents a hydrogen bond component of the surface free energy of the liquid, γ ^a _S represents ^a dispersed component of the surface free energy of the solid, γ ^b _(S represents the dipole component of the surface free energy of the solid, γ ^C _S represents the hydrogen bond component of the surface free energy of the solid, and θ represents the contact angle.)   5. The image forming apparatus according to claim 4, wherein the liquid for measuring the contact angle for determining the surface free energy of the photoreceptor is selected from diiodomethane, α-bromonaphthalene, diethylene glycol, glycerin, and formamide. apparatus.   6. The image forming apparatus according to claim 1, wherein the image forming apparatus calculates image information for each of a plurality of divided areas in a direction perpendicular to the rotation direction of the photosensitive member. The image forming apparatus is characterized in that, based on the image information for each area, charge exposure development is performed for each area separately from the purpose of image formation.   7. The image forming apparatus according to claim 6, wherein the width of the plurality of divided areas of the image information calculating means for calculating image information for each of the plurality of divided areas in a direction orthogonal to the rotation direction of the photosensitive member is 30 mm or less. An image forming apparatus.   8. The image forming apparatus according to claim 6, wherein the image information calculating means is means for calculating image area information relative to a running area.   9. The image forming apparatus according to claim 6, wherein an exposure pattern is determined for each area in accordance with image information of each area, and exposure and development are performed separately from the purpose of image formation. An image forming apparatus.   10. The image forming apparatus according to claim 6, wherein, based on the image information for each area, charge exposure development is performed for each of the areas separately from the purpose of image formation every 2000 sheets or less. An image forming apparatus.   The image forming apparatus according to claim 1, wherein an average particle size of the toner is 7 μm or less.   12. The image forming apparatus according to claim 1, wherein a maximum resolution at which an image can be formed by the image forming apparatus is 1000 dpi or more.   The image forming apparatus according to claim 1, wherein the image forming apparatus is capable of forming a color image.   A process cartridge for an image forming apparatus used in the image forming apparatus according to claim 1, wherein the process cartridge is selected from an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, and a cleaning unit. A process cartridge for an image forming apparatus, wherein at least one means is integrally formed and is detachable from the main body of the image forming apparatus.

Images