JP2006047942A - Image forming apparatus, developing device, process cartridge, evaluation method of image forming apparatus and manufacturing method of image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of maintaining a satisfactory image which does not cause density deterioration of the image and density irregularity over a long term, to provide an evaluation method of the image forming apparatus and to provide a manufacturing method of the image forming apparatus. <P>SOLUTION: Toner average charging amount (Q/d)<SB>dev</SB>in the developing device after one-hour agitation of unused developer and toner average charging amount (Q/d)<SB>drum</SB>on the latent image carrier after one-hour agitation of unused developer satisfy the relation; ¾(Q/d)<SB>dev</SB>-(Q/d)<SB>drum</SB>¾≤0.10[f×C/10μm]. Further, toner average particle size d<SB>dev</SB>in the developing device after one-hour agitation of unused developer and toner average particle size d<SB>drum</SB>on the latent image carrier after one-hour agitation of unused developer satisfy the relation; ¾d<SB>dev</SB>-d<SB>drum</SB>¾≤0.20[μm]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, a developing device, a process cartridge, an image forming apparatus evaluation method, and an image forming apparatus manufacturing method.

  Conventionally, developing devices using a two-component developer containing toner and a magnetic carrier have been widely used. This developing device carries a two-component developer on a developer carrying member and conveys it to a region facing an image carrier such as a photosensitive drum. Then, for example, while applying an alternating electric field between the image carrier and the developer carrier, the electrostatic latent image formed on the image carrier is developed and visualized according to the image information. .

  In a conventional developing device, the developer is charged mechanically with an agitator. For this reason, the toner is subjected to mechanical stress by the agitator. Further, the toner on the developer carrying member is regulated by the thin layer regulating member, and the amount of the developer conveyed to the development area is regulated. When the toner passes through the thin layer forming member, it receives a large mechanical stress.

  Generally, an external additive is attached to the toner around the base resin in order to impart fluidity, and the additive is buried or detached due to the mechanical stress. When such additives are buried or detached, the fluidity is lowered and the non-electrostatic adhesion force of the toner is increased. Then, the toner adheres to a carrier or the like in the developing device, and the toner charge distribution in the developing device becomes broad. As a result, a toner with a high charge amount selectively adheres to the photoconductor, and a relatively small amount of toner is in equilibrium with the potential on the photoconductor, causing the image density to be lower than the desired image density. There was.

  It is conceivable to cope with such a problem by increasing the developing ability. As means for increasing the developing ability, for example, increasing the linear speed ratio of the developing carrier to the photosensitive member, or forming a plurality of grooves on the surface of the developing carrier as described in Patent Document 1. It is done. By increasing the linear velocity ratio of the developing carrier to the photosensitive member as in the former, the number of times the photosensitive member contacts the magnetic brush on the developing carrier while passing through the developing region can be increased. The amount of toner adhered to the toner can be increased. In the latter case, since the developer is held in the groove by the groove, the amount of developer conveyed to the developer carrying member can be increased, and the amount of toner adhered to the surface of the photoreceptor can be increased.

JP 2003-208027 A

  As described above, by increasing the developing ability, a sufficient amount of developer can be uniformly supplied to the surface of the photoreceptor. However, even if the developing performance is increased, abnormal images such as density unevenness still remain. May occur.

Therefore, in order to pursue this cause, the inventors in the initial state and the state in which the toner is deteriorated by continuous stirring for 1 hour, respectively, the toner particle size distribution and the charge amount distribution on the photoreceptor, and The relationship between the particle size distribution of the toner in the developing device and the charge amount distribution was examined. The results are shown in FIGS.
As shown in FIG. 5 and FIG. 6, in the initial state, the contour lines of the number distribution indicating the charge amount and particle size of the toner on the photoconductor, and the contour lines of the number distribution indicating the charge amount and particle size of the toner in the developing device. There is not much difference. However, the contour lines of the number distribution indicating the charge amount and particle size of the toner on the photoconductor after stirring for 1 hour shown in FIGS. 7 and 8 and the contour lines of the number distribution indicating the charge amount and particle size of the toner in the developing device. It can be seen that is significantly different. Specifically, it can be seen that a large amount of toner having a large particle diameter is present on the photoreceptor. The toner having a large particle size on the photoreceptor is a toner that has deteriorated and aggregated in the developing device to increase the apparent particle size, or is a toner having a large particle size that originally existed in the developing device. Is not clear, but the former is considered likely. The toner that has aggregated and thus has an apparently large particle diameter is in a state where the additive is buried and the non-electrostatic adhesion is strong. Aggregated toner adhering to the surface of the photoconductor adheres strongly to the photoconductor due to the pressure of the transfer nip during transfer, and does not move electrostatically to the transfer member even when a transfer bias is applied. As a result, it is considered that density unevenness occurs in the image.
From the above, even if the developing performance is improved and a sufficient amount of developer is supplied to the surface of the photosensitive member, if the aggregated toner adheres on the photosensitive member as described above, Since the transferred toner is not transferred, it is considered that an abnormal image such as density unevenness has occurred.

  As described above, the mechanism by which a large amount of toner having a large particle diameter exists on the photoreceptor is not clear, but the following can be inferred. Usually, the image forming apparatus is designed so that the toner with the average charge amount and the average particle diameter in the initial state is likely to adhere to the photoreceptor. Therefore, as shown in FIGS. 5 and 6, there is no significant difference between the toner charge amount distribution and particle size distribution in the developing device in the initial state and the toner charge distribution and particle size distribution on the photosensitive member. That is, in this image forming apparatus, the charge amount is about −0.3 [fc / μm] and the average particle size is 5.5 [μm], which is the largest number of toners in the developing device in the initial state. The image forming conditions are adjusted so that the toner easily adheres to the surface of the photoreceptor. However, as shown in FIG. 7, after stirring for one hour, the toner deteriorates, and the toner that exists most in the developing device has a charge amount of about −0.2 [fc / μm] and an average particle diameter. Is 5.5 [μm]. Therefore, the absolute amount of toner in the developing device having a charge amount of about −0.3 [fc / μm] and an average particle diameter of 5.5 [μm] is reduced compared to the initial time. Then, there is a high probability that toner having a large particle diameter in the developing device having a charge amount of about −0.3 [fc / μm] will also adhere to the photoreceptor. As a result, as shown in FIG. 8, it is considered that the particle size distribution of the toner adhering to the photoconductor is larger than the particle size distribution of the toner in the developing device.

  From FIGS. 7 and 8, the difference between the charge amount of the toner that easily adheres to the surface of the photoreceptor and the charge amount (average charge amount) of the toner that exists most in the developing device increases. The amount of toner having a charge amount that easily adheres to the surface of the photoreceptor in the developing device is reduced. Then, the toner with a high charge amount in the developing device also adheres to the photoconductor, and the toner and the potential on the photoconductor are in an equilibrium state in a state where the toner is not sufficiently adhered on the photoconductor. As a result, problems such as a decrease in image density are considered to occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to evaluate an image forming apparatus and an image forming apparatus capable of maintaining a good image free from image density reduction and density unevenness over time. And a method of manufacturing an image forming apparatus.

To achieve the above object, the invention of claim 1 is directed to a latent image carrier that carries a latent image, and a developer comprising a toner and a carrier, which is carried on the developer carrier and faces the latent image carrier. In an image forming apparatus comprising: a developing device that is transported to a developing region and develops a latent image on the latent image carrier to form a toner image; and in the developing device after stirring the unused developer for one hour Toner average charge amount (Q / d) _dev and the average toner charge amount (Q / d) _drum of the latent image carrier after stirring the unused developer for one hour is | (Q / d) _dev − (Q / d) _drum | ≦ 0.10 [f · C / 10 μm], and the average particle diameter d _dev of the toner in the developing device after stirring the unused developer for one hour; and the toner average particle diameter d _drum of the latent image bearing member one hour after stirring the developer unused, | d _de And it is characterized in satisfying the relationship _{≦ 0.20 [μm] | -d drum} .
According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the developing device forms a gap with the developer carrier, and allows the developer on the developer carrier to pass through the gap. A developer regulating member that regulates the layer thickness of the developer on the developer carrying member, and a developer carrying amount per unit area on the developer carrying member immediately after regulation by the developer regulating member is 20 [Mg / cm ² ] or more and 60 [mg / cm ² ] or less.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner is added with hydrophobic silica fine particles having an average particle size of 80 nm or more and 140 nm or less. It is what.
Further, the invention according to claim 4 is the image forming apparatus according to claim 1, 2, or 3, wherein the toner contains 0.3 [wt%] or more of hydrophobic silica fine particles having an average particle size of 50 [nm] or less, Hydrophobic titanium oxide fine particles having an average particle size of 1.5 [wt%] or less and an average particle size of 50 [nm] or less are added in an amount of 0.2 [wt%] or more and 1.2 [wt%] or less. It is what.
The invention of claim 5 is the image forming apparatus according to claim 1, 2, 3 or 4, wherein the developer has a toner concentration of 5.0 wt% or more and 9.0 wt% or less, and the average of the developer The charge amount (Q / M) is 15 [−μC / g] or more and 40 [−μC / g] or less.
The invention of claim 6 is the image forming apparatus of claim 1, 2, 3, 4 or 5, wherein the toner has a weight average particle diameter of 5.0 μm or more and 8.0 μm or less. The ratio (Dw / Dn) of the diameter (Dw) to the number average particle diameter (Dn) is 1.20 or less.
According to a seventh aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, or sixth aspect, a developer having a toner particle number ratio of 3 μm or less and a particle number ratio of 5% or less is used. It is characterized by.
The invention of claim 8 is the image forming apparatus of claim 1, 2, 3, 4, 5, 6 or 7, wherein the toner and carrier used for the developer are at a normal temperature and humidity and a toner concentration of 5%. the charging amount Q ₆₀₀ obtained when the carrier and toner was mixed and stirred for 10 minutes under the following conditions, when the charge amount Q ₂₀ obtained when stirred and mixed for 20 seconds under the same conditions, Z (%) = A toner and a carrier that can obtain a charge rising ratio Z (%) calculated by (Q ₂₀ / Q ₆₀₀ ) × 100 of 70 (%) or more are used.
According to a ninth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth, seventh or eighth aspect, the peripheral speed Vs of the developer carrier and the peripheral speed Vp of the image carrier are The above relationship satisfies the relationship of 1.5 ≦ (Vs / Vp) ≦ 2.5.
According to a tenth aspect of the present invention, a developer comprising a toner and a carrier is carried on a developer carrying member, conveyed to a developing region facing the latent image carrying member, and on the latent image carrying member carrying the latent image. In a developing device that develops a latent image into a toner image, an average toner charge amount (Q / d) _dev in the developing device after stirring the unused developer for one hour, and the unused developer average toner charge amount of the latent image carrier after stirring one hour _{(Q / d) drum} and is _{| (Q / d) dev -} (Q / d) drum | ≦ 0.10 [f · C / 10μm] relationship And an average toner particle diameter d _dev in the developing device after stirring the unused developer for 1 hour, and an average toner particle of the latent image carrier after stirring the unused developer for 1 hour The diameter d _drum satisfies the relationship of | d _dev −d _drum | ≦ 0.20 [μm]. It is a sign.
The invention of claim 11 is a latent image carrier, a charging means for charging the surface of the image carrier, and an exposure means for forming a latent image by exposing the charged surface of the latent image carrier. The image forming apparatus includes a developing unit that develops a latent image on the latent image carrier and a cleaning unit that cleans the surface of the latent image carrier, and is attachable to and detachable from at least the latent image carrier. In the process cartridge in which the body and the developing means are integrally supported, the developing means is the developing device according to claim 10.
According to a twelfth aspect of the present invention, there is provided a characteristic in an image forming apparatus comprising: a latent image carrier that carries a latent image; and a developing device that supplies toner to the latent image on the latent image carrier for development. In the evaluation method of the image forming apparatus that detects and evaluates the image forming apparatus, as the characteristics, the toner average charge amount (Q / d) _dev in the developing device and the toner average charge amount of the latent image carrier ( Q / d) _Drum , toner average particle diameter d _dev in the developing device, and toner average particle diameter d _drum on the latent image carrier are detected, respectively, and the average toner charge amount (Q / D) in the developing device is detected. the ≦ 0.10 [f · C / 10μm ] | (Q / d) drum - (Q / d) dev | d) dev and toner average charge quantity of the latent image carrier _{(Q / d)} relationship with _drum is Whether the toner average particle diameter d _dev and the toner image carrier It is characterized in that it is evaluated whether or not the relationship with the mean particle diameter d _drum satisfies | d _dev −d _drum | ≦ 0.20 [μm].
According to a thirteenth aspect of the present invention, there is provided an image forming apparatus that determines a required specification of an image forming apparatus, determines a design condition of the image forming apparatus that satisfies the required specification, and manufactures the image forming apparatus based on the design condition. In the production method, the required specifications are the average toner charge amount (Q / d) _dev in the developing device after stirring the unused developer for 1 hour, and the unused developer after stirring for 1 hour. average toner charge amount of the latent image carrier _{(Q / d) drum} and is _{| (Q / d) dev -} (Q / d) drum | satisfy the relationship of ≦ 0.10 [f · C / 10μm ], and, The toner average particle diameter d _dev in the developing device after stirring the unused developer for one hour and the toner average particle diameter d _drum of the latent image carrier after stirring the unused developer for one hour are: , | D _dev −d _drum | ≦ 0.20 [μm] It is a feature.

According to the first to thirteenth aspects of the present invention, | (Q / d) _dev− (Q / d) _drum | ≦ 0.10 [f] in a state where the unused developer is sufficiently deteriorated by stirring for one hour. C / 10 μm], and the average toner particle diameter d _dev in the developing device after stirring the unused developer for 1 hour, and the latent image carrier after stirring the unused developer for 1 hour The average particle diameter d _drum of the toner satisfies the relationship | d _dev −d _drum | ≦ 0.20 [μm]. The image forming apparatus is set so as to satisfy such a relationship, and the charge amount and the particle diameter of the toner that easily adheres to the latent image carrier over time are set to the charge amount of the toner that exists most in the developing device and The particle size. As a result, as in the prior art, since there is a small amount of toner having a charge amount and particle size that easily adheres to the latent image carrier in the developing device, It is possible to suppress the agglomerated toner from adhering to the latent image carrier. Accordingly, it is possible to suppress a problem that density unevenness occurs even though a sufficient amount of developer is uniformly supplied onto the latent image carrier.
In addition, the charge amount of the toner that easily adheres to the latent image carrier can be maintained over time at the charge amount of the toner that exists most in the developing device. For this reason, since there is a small amount of toner having a charge amount that easily adheres to the latent image carrier in the developing device as in the prior art, a toner that is higher than the charge amount that easily adheres to the latent image carrier in the development device is latent. Adhesion on the image carrier is suppressed. As a result, it is possible to prevent the toner and the potential on the latent image carrier from being in an equilibrium state when the toner is not sufficiently adhered on the latent image carrier, and to suppress a decrease in image density. it can.

  An embodiment in which the present invention is applied to an electrophotographic full-color printer (hereinafter referred to as a printer) as an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram showing the internal configuration of the printer. In FIG. 1, a plurality of photosensitive units 2Y, 2M, 2C, and 2K are detachably mounted on the apparatus body 1 in a box-shaped apparatus body 1. A transfer belt 3 serving as a recording material carrier is disposed obliquely in the diagonal direction of the apparatus main body 1 at the center in the apparatus main body 1. The transfer belt 3 is provided so as to be able to be driven to rotate in the direction of an arrow A in the drawing, spanned by a plurality of rollers to which the rotational driving force is transmitted.

  The photoconductor units 2Y, 2M, 2C, and 2K include drum-like photoconductors 4Y, 4M, 4C, and 4K as image carriers, and the transfer belt 3 so that the surface of each photoconductor is in contact with the transfer belt 3. It is arrange | positioned above. The arrangement of the photoconductor units 2Y, 2M, 2C, and 2K is in the order of 4Y, 4M, 4C, and 4K so that the photoconductor 2Y is on the paper feed side and the photoconductor unit 2K is positioned on the fixing device 9 side. . As the photoconductors 4Y, 4M, 4C, and 4K, belt-like photoconductors or the like may be used.

  The developing devices 5Y, 5M, 5C, and 5K serving as the developer supply means are disposed to face the photoreceptors 4Y, 4M, 4C, and 4K, respectively. For example, the developing device 5Y supplies a two-component developer having yellow toner (hereinafter referred to as Y) and a carrier to the electrostatic latent image on the photoreceptor 4Y for development. The developing device 5M supplies a two-component developer having magenta (hereinafter referred to as M) toner and a carrier to the electrostatic latent image on the photoreceptor 4M for development. The developing device 5C supplies a two-component developer having cyan (hereinafter referred to as C) toner and a carrier to the electrostatic latent image on the photoreceptor 4C for development. The developing device 5K supplies, for example, a two-component developer having black (hereinafter referred to as K) toner and a carrier to the electrostatic latent image on the photoreceptor 4K for development.

  A writing device 6 as an exposure unit is disposed above the photoreceptor units 2Y, 2M, 2C, and 2K, and a duplex unit 7 is disposed below the photoreceptor units 2Y, 2M, 2C, and 2K. Below the duplex unit 7, paper feed units 13 and 14 that can accommodate transfer materials P of different sizes are disposed. A reversing unit 8 is disposed on the left side of the apparatus main body 1, and a manual feed tray 15 is provided on the right side of the apparatus main body 1 so as to be opened and closed in the direction of arrow B. A fixing device 9 is disposed between the transfer belt 3 and the reversing unit 8. A reverse conveyance path 10 is branched and formed on the downstream side of the fixing device 9 in the transfer material conveyance direction. The reverse conveyance path 10 guides the sheet-like transfer material P to a paper discharge tray 12 provided in the upper part of the apparatus by a paper discharge roller 11 disposed in the conveyance path.

  The photoreceptor units 2Y, 2M, 2C, and 2K are units for forming toner images of Y, M, C, and K colors on the photoreceptors 4Y, 4M, 4C, and 4K, and are disposed in the apparatus main body 1. The configuration is the same except for the location. Here, the configuration of the photoreceptor unit 2Y will be described. FIG. 2 is a schematic configuration diagram showing an internal configuration of the photoreceptor unit 2Y. As shown in FIG. 2, the photoreceptor unit 2Y includes a photoreceptor 4Y, a charging roller 16Y that contacts the photoreceptor 4Y, and a cleaning device 17Y that cleans the surface of the photoreceptor 4Y. Mounted as possible. The cleaning device 17Y includes a brush roller 18Y and a cleaning blade 19Y.

  FIG. 3 is a schematic configuration diagram showing the configuration of the writing device 6. In the writing device 6, as shown in FIG. 3, two rotary polygon mirrors 20, 21 arranged coaxially are rotated by a polygon motor 22. The rotary polygon mirrors 20 and 21 include a Y laser beam modulated by Y image data from laser diodes as two laser light sources (not shown), an M laser beam modulated by M image data, and the other two lasers. The laser beam for C modulated by the C image data from the laser diode as the light source and the laser beam for K modulated by the K image data are distributed to the left and right for reflection. The Y laser light and the M laser light from the rotary polygon mirrors 20 and 21 pass through the two layers of the fθ lens 23. The Y laser light from the fθ lens 23 is reflected by the mirror 24, passes through the long WTL 25, and then irradiates the photoreceptor 4Y of the photoreceptor unit 2Y via the mirrors 26 and 27. The M laser light from the fθ lens 23 is reflected by the mirror 28, passes through the long WTL 29, and then is reflected by the photoconductor 4M of the photoconductor unit 2M via the mirrors 30 and 31. The C laser light and the K laser light from the rotary polygon mirrors 20 and 21 pass through the two layers of the fθ lens 32. The C laser light from the fθ lens 32 is reflected by the mirror 33, passes through the long WTL 34, and then irradiates the photoreceptor 4C of the photoreceptor unit 2C via the mirrors 34 and 36. The K laser light from the fθ lens 32 is reflected by the mirror 37 and passes through the long WTL 38, and then is irradiated to the photoconductor 4K of the photoconductor unit 2K through the mirrors 39 and 40.

  Since the developing devices 5Y, 5M, 5C, and 5K have the same configuration except for different toner colors, the configuration of the developing device 5Y will be described. FIG. 4 is a schematic configuration diagram showing an internal configuration of the developing device 5Y. As shown in FIG. 4, the developing device 5Y accommodates a two-component developer having Y toner and a carrier in a developing case 53 as a developer accommodating portion. Further, in the developing case 53, a developing sleeve 54 as a developer carrying member disposed so as to face the photoreceptor 4Y through an opening 53a of the developing case 53, and a screw for conveying the developer while stirring the developer. Members 55 and 56.

  The developing case 53 is divided by a partition wall 57 into a first space portion 65 located on the developer supply side to the photoreceptor 4Y and a second space portion 64 side receiving supply of replenishing toner from the supply port 62. It is divided. The screw member 56 is disposed in the space portion 65, and the screw member 55 is disposed in the space portion 64, and is rotatably supported by a bearing member (not shown) provided in the developing case 53. Of course, the developing sleeve 54 is also rotatably supported by the developing case 53 via a bearing member (not shown), and rotates when a rotational driving force is transmitted from a driving means (not shown). Further, a toner concentration sensor 63 as a toner concentration detecting means for detecting and outputting the toner concentration in the developer is mounted on the developing case 53 so that the detection surface faces the space 65.

  In the developing device 5Y configured as described above, the two-component developer in the developing case 53 is frictionally charged by stirring the Y toner and the carrier while circulating in the developing device 5Y by the constant speed rotation of the screw members 55 and 56. The conveying screw 56 supplies a part of the developer to the developing sleeve 54, and the developing sleeve 54 carries and conveys the developer magnetically. The height (carrying amount) of the developer on the developing sleeve 54 is regulated by a developer regulating member 61 disposed in the developing case 53. The electrostatic latent image on the photoreceptor 4Y is developed with Y toner on the developing sleeve 54 to become a Y toner image. When the toner concentration of the developer in the developing case 53 reaches a predetermined value, Y toner is supplied from the toner supply port 62 to the space 64 side in the developing case 53. The Y toner is mixed with the developer by stirring by the screw member 55 and replenished to the space 65 side.

  In the printer having the above-described configuration, when image formation is instructed by an operation unit (not shown), the photoconductors 4Y, 4M, 4C, and 4K are driven to rotate by a drive source (not shown) and rotate clockwise in FIG. The charging rollers 16Y, 16M, 16C, and 16K of the photosensitive units 2Y, 2M, 2C, and 2K are charged with a charging bias from a power source (not shown) to uniformly charge the photosensitive bodies 4Y, 4M, 4C, and 4K, respectively. The photoconductors 4Y, 4M, 4C, and 4K are uniformly charged by the charging rollers 16Y, 16M, 16C, and 16K and then modulated by the writing device 6 with image data of Y, M, C, and K colors by the writing device 6. Exposure to light forms an electrostatic latent image on each surface. The electrostatic latent images on these photoreceptors 4Y, 4M, 4C, and 4K are developed by developing devices 5Y, 5M, 5C, and 5K to become toner images of Y, M, C, and K colors.

  One transfer material P is separated from the selected one of the paper feed cassettes 13 and 14 by paper feed rollers 45 and 46, and is arranged closer to the paper feed side than the photosensitive unit 2Y. The paper is fed to the registration roller 1. In the present embodiment, a manual feed tray 15 is disposed on the right side portion of the apparatus main body 1, and the transfer material P can also be fed from the manual feed tray 15 to the registration rollers 51. The registration roller 51 sends each transfer material P onto the transfer belt 3 at a timing when the leading edge of the transfer material P coincides with the toner image on the photoreceptors 4Y, 4M, 4C, and 4K. The transferred transfer material P is electrostatically attracted to the transfer belt 3 charged by the paper suction roller 52 and conveyed to each transfer unit. When the transferred transfer material P passes through the transfer portions in sequence, the transfer brushes 47, 48, 49, and 50 use toners of Y, M, C, and K colors on the photoreceptors 4Y, 4M, 4C, and 4K, respectively. Images are sequentially superimposed and transferred. As a result, a full-color toner image with four colors superimposed is formed. The full color toner image is fixed on the transfer material P on which the full color toner image is formed by the fixing device 9. The fixed transfer material P is reversely discharged to the paper discharge tray 12 through a discharge path corresponding to the designated mode, or is straightly discharged from the fixing device 9 through the reversing unit 8 and discharged straight. The

  The above-described image forming operation is an operation when the full-color mode for superimposing four colors is selected by an operation unit (not shown). For example, when the three-color superposition full-color mode is selected on the operation unit, the formation of the K toner image is omitted, and the full-color image obtained by superposing the Y, M, and C three-color toner images on the transfer material P. It is formed. When the monochrome image forming mode is selected on the operation unit, only the K toner image is formed and a monochrome image is formed on the transfer material P.

FIG. 9 is a perspective view showing the internal configuration of the developing device 5 used in the present embodiment. The replenishment toner supplied from the supply port 62 is agitated while being moved in the direction of the arrow in the drawing by the rotation of the screw members 55 and 56. The agitated toner is carried and conveyed on the developing sleeve 54 and used for developing the latent image on the surface of the photoreceptor 4.
In the present embodiment, as shown in FIG. 2, a photoconductor unit 2Y including a photoconductor 4Y, a charging roller 16Y, and a cleaning device 17Y is detachably attached to the apparatus main body. The configuration in which the unit including the photoconductor 4 is detachable from the apparatus main body 1 is not limited to this. A configuration that is detachable from the apparatus main body 1 may be applied as a process cartridge including a developing device.
FIG. 10 is a cross-sectional view of a process cartridge 500 applicable to the present embodiment. The process cartridge 500 includes a charging roller 16 as a charging unit, a developing device 5 as a developing unit, a cleaning device 17 as a cleaning unit, and the like around the photosensitive member 4. FIG. 11 shows a schematic configuration diagram of the printer apparatus main body 1 including the process cartridge 500. As described above, the members around the photosensitive member 4 can be integrally attached to and detached from the printer apparatus main body 1 as the process cartridge 500 in an integrated manner, thereby improving the maintainability. The process cartridge is not limited to the configuration of the process cartridge 500 described above, and it is sufficient that at least the developing device 5 and the photosensitive member 4 are integrally coupled and detachable from the printer apparatus main body 1. In FIG. 11, only one process cartridge 500 is shown, but by arranging a plurality of process cartridges 500 in the direction of surface movement of the transfer belt 3, color image formation is possible.

  In the printer according to this embodiment, it is preferable that the developing conditions of the developer and the developing device 5 have the following characteristics. It is preferable to develop a printer that satisfies the following conditions and incorporate it into the apparatus.

In the printer of this embodiment, in a state where the unused developer is sufficiently deteriorated by stirring for 1 hour, | (Q / d) _dev− (Q / d) _drum | ≦ 0.10 [f · C / 10 μm ] And the average particle diameter d _dev of the developing device after stirring the unused developer for 1 hour and the latent image carrier after stirring the unused developer for 1 hour. It is preferable that the toner average particle diameter d _drum satisfies a relationship of | d _dev −d _drum | ≦ 0.20 [μm].

A method for measuring the average toner charge amount (Q / d) _dev in the developing device calculated from the number ratio and the average toner particle diameter d _dev in the developing device will be described. As a method for measuring the toner average charge amount (Q / d) _dev and toner average particle diameter d _dev in the developing device, a method using a charge spectrum method, a method using a laser Doppler velocimeter, and the like are known. Any measuring method can be used, but here, a measuring method in a toner particle charge amount distribution measuring apparatus (E-Spart Analyzer; manufactured by Hosokawa Micron Corporation) using a laser Doppler velocimeter is shown. First, the developer in the developing device is held on a developer holding stand constituted by a magnet. Next, the developer held on the developer holding table is separated into a magnetic carrier and toner by an air gun (nitrogen gas), and only the toner particles are sucked into the measurement unit. The toner sucked into the measuring unit is sequentially measured for the charge amount, and the charge amount distribution of the toner and the particle size distribution are obtained at the same time. The measurement conditions in the present embodiment were as follows.
・ Nitrogen gas blow pressure: 0.4kg / cm2G
・ Nitrogen gas blow time: 2 sec
・ Nitrogen gas blow interval: 2 sec
・ Rotation speed of developer holder: 320/1500 rpm
From the toner charge amount distribution in the developing device, the toner average charge amount (Q / d) _dev of the toner in the developing device is obtained. Further, the toner average particle diameter d _dev in the developing device is obtained from the particle size distribution of the toner in the developing device.

The E-spart analyzer can also be used when measuring the average charge amount (Q / d) _drum and the average particle diameter d _drum of the toner on the image carrier. As a measurement procedure, at the stage where the toner is developed on the image carrier by the image forming apparatus, the image forming process is stopped and the image carrier is taken out from the image forming apparatus. The image bearing member is fixed to a dedicated jig, and toner is sucked into the measuring unit by an air gun (nitrogen gas). The toner sucked into the measuring unit is sequentially measured for the charge amount, and the charge amount distribution of the toner and the particle size distribution are obtained at the same time. The measurement conditions in the present embodiment were as follows.
・ Nitrogen gas blow pressure: 0.4kg / cm2G
・ Nitrogen gas blow time: 2 sec
・ Nitrogen gas blow interval: 2 sec
From the toner charge amount distribution in the developing device, the toner average charge amount (Q / d) _drum of the toner in the developing device is obtained. Further, the toner average particle diameter _ddrum in the developing device is obtained from the particle size distribution of the toner in the developing device.

  Further, as the developer according to the present embodiment, a developer having a toner concentration in the range of 5.0 to 9.0 (wt%) and an average charge amount Q / M of 15 to 40 [−μC / g] is used. It is desirable to optimize the coverage of the carrier with the toner and the developer fluidity. When the toner concentration is lower than 5.0 (wt%), the charge amount Q / M of the developer increases, and it is necessary to set a higher development potential for developing the electrostatic latent image on the photosensitive member. There is a risk of reducing the life of the photoreceptor. Further, when the charge amount Q / M of the developer exceeds 40 [−μC / g], the possibility that the image density is lowered increases. Further, when the toner concentration is higher than 9.0 (wt%), the charge amount Q / M of the developer tends to decrease. When the charge amount Q / M of the developer is less than 40 [-μC / g], toner scattering is likely to occur, and the so-called background contamination in which the image background portion is stained with toner as the level of toner scattering deteriorates. Occurs and degrades image quality. Therefore, by using a developer having an average charge amount Q / M of 15 to 40 [−μC / g] in a toner concentration range of 5.0 to 9.0 (wt%), a small particle size carrier is used. Even with a developer using a small particle size toner, stable image quality can be obtained over a long period of time.

In the developer according to the exemplary embodiment, the ratio of the toner to the carrier is 2 to 25 parts by weight, preferably 4 to 15 parts by weight, per 100 parts by weight of the carrier. Further, the coverage of the carrier with the toner is 10 to 80%, preferably 20 to 60%. When the coverage of the carrier with toner is 50%, the toner charge amount is 35 (−μC / g) or less, more preferably 25 (−μC / g) or less. The lower limit is not particularly limited, but is usually about 15 (−μC / g). The coverage is calculated by the following formula.
Coverage (%) = (Wt / Wc) × (ρc / ρt) × (Dc / Dw) × (1/4) × 100
In the above formula, Dc is the carrier weight average particle diameter (μm), Dw is the toner weight average particle diameter (μm), Wt is the toner weight (g), Wc is the carrier weight (g), and ρt is the toner true The density (g / cm ³ ) and ρc represent the true carrier density (g / cm ³ ).

The weight average particle size is calculated based on the particle size distribution (relationship between the number frequency and the particle size) of the particles measured on the basis of the number. The weight average particle diameter Dw in this case is represented by the following formula.
Dw = {1 / Σ (nD ³ )} × {Σ (nD ⁴ )}
In the above formula, D represents the representative particle size (μm) of particles present in each channel, and n represents the total number of particles present in each channel. The channel indicates a length for equally dividing the particle size range in the particle size distribution diagram, and in the present embodiment, a length of 2 μm is adopted. Further, as the representative particle size of the particles existing in each channel, the lower limit value of the particle size stored in each channel was adopted.

  The developer according to the exemplary embodiment has a toner weight average particle diameter of 5.0 to 8.0 μm, and a ratio of the toner weight average particle diameter (Dw) to the number average particle diameter (Dn) (Dw / It is desirable that Dn) is 1.20 or less. The reduction in toner particle size is indispensable for increasing the resolution, but as a side effect, fluidity and storage stability tend to deteriorate. When the toner particle size is less than 5.0 μm, the fluidity of the developer is extremely deteriorated, and it becomes difficult to ensure a uniform toner concentration in the developer. Further, the reduction in the toner particle diameter is a direction in which the coverage with respect to the carrier increases. When the coverage is excessively high, there is a concern that the carrier contamination is accelerated and the toner is scattered. As a means for improving the fluidity of the toner and the developer, a means for adding a large amount of additives to the toner cannot be expected to be essentially improved because side effects occur. However, by making the particle size distribution of the toner uniform, the side effects associated with reducing the toner particle size are overcome. In other words, the weight average and number average particle diameter ratio Dw / Dn of the toner is preferably close to 1, and by setting it to 1.20 or less, an effect of suppressing deterioration in fluidity can be obtained, and a small particle diameter toner is used. Even in this case, the toner density can be made uniform. As described above, the weight average particle diameter of the toner is 5.0 to 8.0 μm, and the weight average / number average particle diameter ratio Dw / Dn is 1.20 or less, thereby adding to the image density stability. As a result, the resolution is improved and a higher quality image can be obtained. In addition, when the particle number ratio of 3 μm or less in the toner particle size distribution is set to 5% or less, the quality improvement effect in fluidity and storage stability is remarkable, and the toner replenishment property to the developing device and the toner charge rising property are good. A good level.

  The particle size distribution of the toner can be measured by various methods. In this embodiment, the toner particle size distribution is measured using a small hole passage method (Coulter counter method). As a measuring device, COULTERCOUNTERMODETA2 (manufactured by Coulter) was used, an interface for outputting number distribution and volume distribution was connected, and an aperture (pore) of 100 μm was used. As a measuring method, first, a toner measurement sample is dispersed in a surfactant added to an electrolytic aqueous solution. This sample is injected into another 1% NaCl field solution, and an electric current is passed between the electrodes through the electrolytic solution in which the electrodes are placed on both sides of the aperture tube. The particle size distribution of 2 to 40 μm particles is measured from the resistance change at this time, and the number average particle diameter and the weight average particle diameter are obtained from the average distribution.

  In addition, the developer according to the exemplary embodiment desirably has a toner charge rising ratio Z (%) obtained as described later of 70 (%) or more. By setting the toner charge rising ratio Z (%) to 70 (%) or more, a great improvement effect was observed in toner scattering and background stains. The toner charge rising characteristic is an important characteristic for how efficiently the replenished toner adheres uniformly to the carrier to form a uniform mixed state. In particular, the excellent charge rise characteristics means that the electrostatic force and van der Waals force act on the carrier in a short time and the desired charge amount can be obtained, and it is possible to suppress toner scattering and background stains. Become.

The toner charge rising ratio Z (%) is obtained when the toner and the carrier are stirred and mixed for 10 minutes under normal temperature (23 ± 3 ° C.) and normal humidity (50 ± 10%) under a toner concentration of 5% or less. When the charge amount Q ₂₀ obtained by stirring and mixing under the same conditions for 20 seconds with respect to the charge amount Q ₆₀₀ obtained is calculated as Z (%) = (Q ₂₀ / Q ₆₀₀ ) × 100. A method for measuring the charge amounts Q ₆₀₀ and Q ₂₀ is as follows. A developer is prepared by mixing 50 g of a carrier and a toner corresponding to a toner concentration of 5% under normal temperature and humidity for a predetermined time (device name: Ball mill mount S4-2, manufactured by Ito Manufacturing Co., Ltd., rotation speed: 280 rpm). To do. 3 g of this developer was placed in a measuring gauge set with a mesh of 635 mesh (manufactured by Toyo Corporation, SUS316), and blow-off for 60 seconds (blow-off device: TB-200, manufactured by Toshiba Chemical Corporation), blow gas: nitrogen air, Blow pressure: 1.5 ± 0.1 (kg / cm 2)), and then the charge amount Q (μC) and mass M (g) of the scattered powder were measured, and the charge amount Q / M (−μC / g) ) Can be obtained.

  In addition, it is preferable that a fluidity imparting agent is added to the toner. Various fluidity imparting agents can be used, but it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using an average particle diameter of both fine particles of 50 [nm] or less, electrostatic force and van der Waals force with the toner can be remarkably improved, and toner fluidity is improved. Is planned. As a result, a desired charge level of the developer can be obtained, good image quality can be obtained, and transfer residual toner can be reduced. Further, the titanium oxide fine particles are excellent in environmental stability and image density stability, but tend to deteriorate the charge rising characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, it is considered that the influence of deterioration of charging rise characteristics becomes large. However, when the addition amount of the hydrophobic silica fine particles is in the range of 0.3 to 1.5 [wt%] and the hydrophobic titanium oxide fine particles are in the range of 0.2 to 1.2 [wt%], the charge rising characteristics are large. Even if copying was repeated, stable image quality was obtained and toner scattering could be suppressed even when copying was repeated.

  Further, by adding hydrophobic silica having a large particle diameter of 80 to 140 [nm], the performance is further improved with respect to transferability and developability. In particular, the effect of improving the quality is remarkable in a developer using a toner having a small particle diameter such that the average particle diameter of the toner is 7 [μm] or less. That is, the additive having a large particle size acts as a spacer between the toner particles, and it is possible to suppress the toner aggregation at the time of toner transfer compression and the embedding of the additive on the toner surface at the time of empty stirring of the developing machine. As a result, it was possible to obtain a high-quality image over a long period of time without causing solid image density unevenness due to transfer failure and toner fluidity deterioration due to burying of the additive.

  The weight average particle diameter Dw of the carrier according to the present embodiment is preferably 25 to 60 [μm], more preferably 30 to 45 [μm]. When the weight average particle diameter Dw of the carrier is larger than 60 [μm], the magnetic carrier holding force on the photoconductor is strong and carrier adhesion hardly occurs. However, since the surface area of the carrier per unit weight is small, when the toner concentration is increased in order to obtain a high image density, the scumming increases rapidly. In addition, when the dot diameter of the latent image is small, the variation in the dot diameter increases. On the other hand, when the weight average particle diameter Dw of the carrier is smaller than 25 μm, the magnetic moment per carrier particle is lowered, the magnetic carrier holding force on the developing sleeve is weakened, and carrier adhesion is likely to occur.

  Furthermore, the content ratio of the particles having a particle size of less than 44 [μm] in the carrier particles is 70 [wt%] or more, preferably 75 [wt%] or more. When the said content rate is less than the said range, the improvement effect with respect to the carrier adhesion mentioned above is small. The content ratio of particles having a particle size of 62 [μm] or more is less than 3 wt%, preferably less than 1 [wt%]. The greater the content of particles of 62 [μm] or more, the greater the variation in dot diameter, and the lower the dot reproducibility becomes. The content ratio of particles having a particle size of less than 22 [μm] is 7 [wt%] or less. In the case of a small particle size carrier, most of the carrier adhering to the carrier is a fine particle of less than 22 [μm]. The present inventors evaluated carrier adhesion by changing the weight ratio of particles smaller than 22 [μm] in a small particle size carrier having a weight average particle diameter Dw of 25 to 45 [μm]. As a result, if the particles having a particle size of 22 [μm] or less are 7 [wt%] or less, the carrier adhesion is improved to the extent that there is no problem, and 3 [wt%] or less and further 1 [wt%] or less. Further, it was found that the quality improvement effect was great.

  Further, the magnetic moment per carrier particle when a magnetic field of 1000 oersted (Oe) is applied is 70 [emu / g] or more, preferably 76 [emu / g] or more. The upper limit is not particularly limited, but is usually about 150 [emu / g]. When the magnetic moment is smaller than 70 [emu / g], the magnetic carrier holding force on the developing sleeve is reduced, and carrier adhesion is likely to occur.

  The magnetic moment of the carrier can be measured as follows. Using a BH tracer (BHU-60 / manufactured by Riken Denshi Co., Ltd.), 1.0 g of carrier particles are packed in a cylindrical cell and set in an apparatus. The magnetic field is gradually increased and changed to 3000 Oersted, then gradually reduced to zero, and then the opposite magnetic field is gradually increased to 3000 Oersted. Further, after gradually reducing the magnetic field to zero, a magnetic field is applied in the same direction as the first. In this way, the BH curve is illustrated, and the magnetic moment of 1000 oersted is calculated from the figure.

Examples of the carrier core material particles having a magnetic moment of 76 [emu / g] or more when a magnetic field of 1000 oersted is applied include, for example, ferromagnetic materials such as iron and cobalt, magnetite, hematite, Li-based ferrite, Mn -Zn ferrite, Cu-Zn ferrite, Ni-Zn ferrite, Ba ferrite, Mn-Mg-Sr ferrite, Mn ferrite and the like. Ferrite is a sintered body generally represented by the following formula.
(MO) x (NO) y (Fe ₂ O ₃ ) z
However, x + y + z = 100 mol%, and M and N are Ni, Cu, Zn, Li, Mg, Mn, Sr, Ca, etc., respectively, and the divalent metal oxide and the trivalent iron oxide Consists of a complete mixture.

As for the characteristics of the developing device, it is preferable that the developer carrying amount per unit area on the developing sleeve immediately after regulation by the developer regulating member is 20 to 60 [mg / cm ² ]. When the carrying amount is less than 20 [mg / cm ² ], it is necessary to increase the electric field applied between the developing sleeve and the photoconductor, which is disadvantageous for carrier adhesion. Further, when the developer carrying amount is more than 60 [mg / cm ² ], the dropping of the agent is more likely to occur on the downstream side in the developer conveying direction of the developing sleeve than the developer regulating member. Further, in the space between the photosensitive member and the developing sleeve, the developer filling density tends to increase, and the fluidity of the developer in this space tends to decrease. Along with this decrease in fluidity, toner supply to the electrostatic latent image on the photoreceptor is not smoothly performed, and image density reduction and density unevenness are likely to occur.

  In the developing device, when the peripheral speed of the developing sleeve is Vs and the peripheral speed Vp of the photosensitive member, it is desirable to adjust Vs / Vp to be in the range of 1.5 to 2.5. This makes it possible to obtain a high quality image. When Vs / Vp is lower than 1.5, the developer passing time through the electrostatic latent image is shortened, so that the developing ability is reduced and an image having a large area is output. The decrease in image density becomes remarkable. Further, it is known that when Vs / Vp is higher than 2.5, that is, an abnormal image is generated in a direction in which the contact time between the developer and the electrostatic latent image is increased. The abnormal image referred to here is a decrease in image density at the rear end of the solid image portion, image omission, particularly image omission that is noticeable at the rear end of the halftone image, and image density at the boundary between the solid image and the halftone image. It means change. All of these appear at locations where the latent image potentials are different and at the boundary portions of the image density where the latent image potentials change rapidly and discontinuously. This is due to the phenomenon that the toner in the developer moves in the process of passing the developer through the development nip, and the transient phenomenon when the developer layer having a capacitance as a derivative passes through different discontinuous development electric fields. It is considered a thing.

Hereinafter, the carrier and toner materials used in this embodiment will be described. First, the carrier used in the present embodiment is composed of magnetic core particles and a resin layer covering the surface. As the resin for forming this resin layer, a known resin conventionally used in the production of carriers can be used. For example, a silicone resin containing a repeating unit represented by the following chemical formula 1 can be preferably used for the resin layer of the carrier.

  Examples of the straight silicone resin used for the resin layer of the carrier include KR271, KR272, KR282, KR252, KR255, KR152 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406 (manufactured by Toray Dow Corning Silicone). A modified silicone resin can also be used for the resin layer of the carrier. Examples of such materials include epoxy-modified silicone, acrylic-modified silicone, phenol-modified silicone, urethane-modified silicone, polyester-modified silicone, and alkyd-modified silicone. Specific examples of the modified silicone resin include epoxy modified product: ES-1001N, acrylic modified silicone: KR-5208, polyester modified product: KR-5203, alkyd modified product: KR-206, urethane modified product: KR-305 ( As mentioned above, Shin-Etsu Chemical Co., Ltd.), epoxy modified product: SR2115, alkyd modified product: SR2110 (manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like.

The silicone resin can contain an appropriate amount (0.001 to 30% by weight) of an aminosilane coupling agent. Examples of such a silicone resin include the following.
_{H 2 N (CH 2) 3} Si (OCH 3) 3: MW179.3
_{H 2 N (CH 2) 3} Si (OC 2 H 5) 3: MW221.4
_{H 2 NCH 2 CH 2 CH 2} Si (CH 3) 2 (OC 2 H 5): MW161.3
_{H 2 NCH 2 CH 2 CH 2} Si (CH 3) (OC 2 H 5) 2: MW191.3
_{H 2 NCH 2 CH 2 NHCH 2} Si (OCH 3) 3: MW194.3
_{H 2 NCH 2 CH 2 NHCH 2} CH 2 CH 2 Si (CH 3) (OCH 3) 2: MW206.4
_{H 2 NCH 2 CH 2 NHCH 2} CH 2 CH 2 Si (OCH 3) 3: MW224.4
_{(CH 3) 2 NCH 2 CH} 2 CH 2 Si (CH 3) (OC 2 H 5) 2: MW219.4
_{(C 4 H 9) 2 NC} 3 H 6 Si (OCH 3) 3: MW291.6

  Furthermore, as the resin layer of the carrier used in this embodiment, the following can be used alone or mixed with the silicone resin. Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, 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, styrene-octyl acrylate copolymer) Polymer, styrene-phenyl acrylate copolymer, etc.) styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene -Phenyl methacrylate copolymer, etc.) Styrene resins such as len-α-chloroacrylic acid methyl copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, ketone resin, ethylene -Ethyl acrylate copolymer, xylene resin, polyamide resin, phenol resin, polycarbonate resin, melamine resin and the like.

  As a method for forming the resin layer on the surface of the core particles of the carrier, a known method such as a spray drying method, a dipping method, or a powder coating method can be used. In particular, a method using a fluidized bed type coating apparatus is effective for forming a uniform coated film.

  The thickness of the resin layer formed on the surface of the carrier core particles is usually 0.02 to 1 μm, preferably 0.03 to 0.8 μm. Since the thickness of the resin layer is extremely small, the particle size distribution of the carrier made of core material particles covering the resin layer and the carrier core material particles is substantially the same.

Further, the resistivity of the carrier may be adjusted as necessary, and this is possible by adjusting the resistance of the coating resin on the core material particles and controlling the film thickness. In order to adjust the carrier resistance, it is also possible to add conductive fine powder to the coating resin layer. Examples of the conductive fine powder, conductive ZnO, metal or metal oxide powder such as Al, of SnO2 or various prepared in various ways elements doped _{SnO 2, TiB 2, ZnB 2} , MoB 2 , etc. Examples thereof include boride, silicon carbide, polyacetylene, polyparaphenylene, poly (para-phenylene sulfide) polypyrrole, conductive polymers such as polyethylene, carbon black such as furnace black, acetylene black, and channel black. These conductive fine powders are made uniform by using a dispersing machine using a medium such as a ball mill or a bead mill, or a stirrer equipped with a blade rotating at high speed after being put into a solvent used for coating or a resin solution for coating. Can be dispersed.

  Next, the toner used in this embodiment is composed of at least a binder resin, a colorant, a release agent, and a charge control agent. This toner can be an amorphous or spherical toner prepared by various toner production methods such as a polymerization method and a granulation method. Either magnetic toner or non-magnetic toner can be used.

  As the toner binder resin used here, all those conventionally used as toner binder resins are applied. Specifically, homopolymers of styrene such as polystyrene, polychlorostyrene, and polyvinyltoluene, and substituted products thereof; styrene / p-chlorostyrene copolymer, styrene / propylene copolymer, styrene / vinyltoluene copolymer, styrene / Vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / octyl acrylate copolymer, styrene / methyl methacrylate copolymer Styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, styrene / acrylonitrile copolymer, styrene / vinyl ethyl ether copolymer, styrene / Vinyl methyl ketone copolymer, styrene / Styrene copolymer such as styrene / butadiene copolymer, styrene / isoprene copolymer, styrene / acrylonitrile / indene copolymer, styrene / maleic acid copolymer, styrene / maleic acid ester copolymer; polymethyl methacrylate, Polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyvinyl butyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic Base petroleum resin, chlorinated paraffin, paraffin wax and the like, and these may be used alone or in admixture of two or more.

  As the colorant of the toner used here, dyes and pigments capable of obtaining yellow, magenta, cyan, and black toners can be used, and pigments and dyes conventionally used as toner colorants can be used. All apply. Specifically, nigrosine dye, aniline blue, calco oil blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green, Hansa Yellow G rhodamine 6C lake, chrome yellow, quinacridone, benzidine yellow, malachite green, malachite Examples thereof include green hexalate, rose bengal, monoazo dye / pigment, disazo dye / pigment, and trisazo dye / pigment. The amount of these colorants to be used is generally 1-30 wt%, preferably 3-20 wt%, relative to the binder resin.

  As the toner charge control agent used here, either a positive charge control agent or a negative charge control agent can be used. In the case of a color toner, a transparent to white color that does not impair the color tone is used. Are preferably used. For example, quaternary ammonium salts, imidazole metal complexes, salts, and the like are used as positive polarity, and salicylic acid complexes, salts, organic boron salts, calixarene compounds, and the like are listed as negative polarity.

  In addition, in the toner used here, in order to provide releasability, in addition to synthetic waxes such as low molecular weight polyethylene and polypropylene, candelilla wax, carnauba wax, rice wax, wax, jojoba oil Plant waxes such as beeswax; animal waxes such as beeswax, lanolin and whale wax; mineral waxes such as montan wax and ozokerite; fat waxes such as hydrogenated castor oil, hydroxystearic acid, fatty acid amide, phenol fatty acid ester These may be used alone or in combination of two or more.

  Further, the toner used here includes various plasticizers (dibutyl phthalate, phthalic acid) for the purpose of adjusting the thermal properties, electrical properties, and physical properties of the toner as necessary in addition to the above-mentioned release agent. It is also possible to add auxiliaries such as dioctyl) and resistance adjusting agents (tin oxide, lead oxide, antimony oxide, etc.). Furthermore, the toner of the present invention may be mixed with a fluidity-imparting agent other than the above-mentioned mold release agent and auxiliary agent, if necessary. Examples of the fluidity-imparting agent include silica fine particles, titanium oxide fine particles, aluminum oxide fine particles, magnesium fluoride fine particles, silicon carbide fine particles, boron carbide fine particles, titanium carbide fine particles, zirconium carbide fine particles, boron nitride fine particles, titanium nitride fine particles, nitriding. Zirconium fine particles, magnetite fine particles, molybdenum disulfide fine particles, aluminum stearate fine particles, magnesium stearate fine particles, zinc stearate fine particles, fluorine-based resin fine particles, acrylic resin fine particles, and the like may be used, and these may be used alone or in combination of two or more. It is possible. As the fluidity-imparting agent, those having a primary particle size of less than 0.1 μm, a surface hydrophobized with a silane coupling agent, silicon oil or the like, and a hydrophobization degree of 40 or more are preferable.

  A known method is used as a method for producing the toner used here. For example, a binder resin, a colorant and a pigment, a charge control agent, and if necessary, a release agent and the like are sufficiently mixed using a mixing machine such as a Henschel mixer and a ball mill at an appropriate ratio. Thereafter, melt kneading is performed using a screw-type extrusion continuous kneader, a two-roll mill, a three-roll mill, and a pressure and heating kneader. In the case of a color toner, a masterbatch pigment obtained by previously melt-kneading a part of the binder resin and the pigment for the purpose of improving the dispersibility of the pigment is generally used as the colorant. The kneaded product obtained by the above method is cooled and solidified, and then coarsely pulverized using a pulverizer such as a hammer mill. Further, the coarsely pulverized product is pulverized with a jet mill pulverizer and then subjected to surface treatment using a rotor pulverizer connected to an airflow classifier or the like. For example, a hammer mill, a ball mill, a tube mill, a vibration mill, etc. can be mentioned as a collision type pulverizer. As a jet type pulverizer comprising compressed air and a collision plate as main components, I type and IDS type collision pulverizers (manufactured by Nippon Pneumatic Industry Co., Ltd.) can be preferably used. Examples of the rotor pulverizer include a roll mill, a pin mill, and a fluidized bed jet mill. In particular, as a rotor type pulverizer comprising a fixed container as an outer wall and a rotating piece having the same central axis as that of the fixed container, turbo mills (manufactured by Turbo Industry Co., Ltd.), kryptron (manufactured by Kawasaki Heavy Industries, Ltd.) ), Fine mill (manufactured by Nippon Pneumatic Industry Co., Ltd.) and the like can be used. For the connected classifier, a dispersion separator (DS) classifier (manufactured by Nippon Pneumatic Industry Co., Ltd.), a multi-part classifier (Elbow Jet; manufactured by Nittetsu Mining Co., Ltd.), etc. can be used as the air classifier. . Furthermore, fine powder classification can be performed using an airflow classifier or a mechanical classifier to obtain fine particles.

  Furthermore, when adding and mixing a fluidity-imparting agent to the fine particles obtained by the above method, known equipment such as a Henschel mixer, a super mixer, and a ball mill can be used. Alternatively, a toner may be directly produced from a monomer, a colorant and a fluidity imparting agent by a suspension polymerization method or a non-aqueous dispersion polymerization method.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Here, the part is based on weight. The main characteristics of the carrier and toner in each example and comparative example are summarized in Table 8 at the end, and the evaluation results are summarized in Table 9.

[Example 1]
* Example of toner production (master batch pigment component)
Pigment Quinacridone-based magenta pigment (C.I. PigmentRed122) 50 parts Binder resin Epoxy resin 50 parts Water 30 parts The above raw materials were mixed in a Henschel mixer to obtain a mixture in which pigment aggregates were soaked with water. This was kneaded for 45 minutes with two rolls set at a roll surface temperature of 130 ° C. to obtain a master batch pigment (1). Next, using this master batch pigment (1), a toner was prepared by the following method.

(Toner component)
Binder resin Epoxy resin (R-304, manufactured by Mitsui Chemicals) 100 parts Colorant Master batch pigment (1) 13 parts Charge control agent Zinc salicylate (Bontron E84, manufactured by Orient Chemical Co., Ltd.) 2 parts

  The mixture having the above composition was melt-kneaded with a twin-screw kneader, and the kneaded product was finely pulverized so as to have an average particle diameter of 12 μm with a jet mill pulverizer equipped with a flat impingement plate at the pulverization part. Furthermore, surface treatment was performed using a turbo mill in which the fine particles were connected to a DS type airflow classifier to obtain fine particles having an average particle diameter of 11.5 μm. Furthermore, fine powder classification was performed to obtain fine particles having a weight average particle diameter of 12.1 μm and a particle number ratio of 3 μm or less of 0%. To 20 kg of the fine particles, 100 g of hydrophobic silica fine particles having an average particle diameter of 0.3 μm and 100 g of hydrophobic titanium oxide fine particles having an average particle diameter of 0.3 μm are added and mixed by stirring to obtain a magenta electrophotographic toner A. It was.

* Production Example of Carrier A A silicone resin solution (solid content: 5%) was prepared by diluting a silicone resin (SR2411, manufactured by Toledo Corning Silicone). Then, using a fluidized bed type coating apparatus, the silicone resin solution is applied at a rate of about 40 g / min in an atmosphere of 100 ° C. on each particle surface of the carrier core material particles (1), and further 240 ° C. And a carrier having a film thickness of 0.53 μm and a true specific gravity of 5.0 g / cm ³ was obtained. The film thickness was adjusted depending on the amount of the coating solution.

A developer having a toner concentration (TC) of 4.5 wt% was prepared using the color toner and carrier obtained by the above method, and quality evaluation was performed by modifying the Ricoh IPSiOcolor 8100 machine to the following development conditions. As an initial setting of the developer, the toner density sensor output Vt is adjusted to 3.00 V and set as a reference value. An image with an image area of 20% was output while maintaining this reference value. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

[Example 2]
Image output and evaluation were performed in the same manner as in Example 1 using the same toner and carrier as in Example 1 except that the development conditions were changed as shown in the table below.

Example 3
Image output and evaluation were performed in the same manner as in Example 1 using the same toner and carrier as in Example 1 except that the development conditions were changed as shown in the table below.

Example 4
A magenta electrophotographic toner B was obtained in the same manner as in Example 1 except that the weight average particle size of 8.4 μm and 3 μm or less of the toner in Example 1 was adjusted to 2%. Using this toner and the development conditions of Example 3 above, image output and evaluation similar to Example 1 were carried out.

Example 5
A magenta electrophotographic toner C was obtained in the same manner as in Example 1 except that the weight average particle diameter of 5.1 μm and 3 μm or less of the toner in Example 1 was adjusted to 15%. Using this toner and the development conditions of Example 3 above, image output and evaluation were performed as in Example 1.

Example 6
* Production Example of Polymerized Toner 710 g of ion-exchanged water was charged with 450 g of a 0.1 M Na ₃ PO ₄ aqueous solution, heated to 60 ° C., and then 12000 rpm using a TK homomixer (manufactured by Special Machine Industries). Was stirred. To this, 68 g of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

(Toner component)
170g of styrene
30g of n-butyl acrylate
Quinacridone magenta pigment 10g
Di-t-butylsalicylic acid metal compound 2g
Polyester resin 10g
The above formulation was heated to 60 ° C., and uniformly dissolved and dispersed at 12000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). In this, 10 g of polymerization initiators 2,2′-azobis (2,4-dimethylvaleronitrile) were dissolved to prepare a polymerizable monomer composition. Then, the polymerizable monomer composition is put into the aqueous medium and stirred at 10,000 rpm for 20 minutes with a TK homomixer in an N ₂ atmosphere at 60 ° C. to prepare the polymerizable monomer composition. Grained. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and reacted for 10 hours. After completion of the polymerization reaction, a part of the aqueous medium is distilled off under reduced pressure and cooled, and after adding hydrochloric acid to dissolve calcium phosphate, filtration, washing and drying are performed, and the weight average particle size is 7 μm, 3 μm or less. Colored suspended particles with a ratio of 1% were obtained. To 20 kg of the fine particles, 100 g of hydrophobic silica fine particles having an average particle size of 0.3 μm and 100 g of hydrophobic titanium fine particles having an average particle size of 0.3 μm were added and stirred to obtain a magenta electrophotographic toner D. . Using this toner and the development conditions of Example 3, image output and evaluation were carried out in the same manner as in Example 1.

Example 7
Image output and evaluation were performed in the same manner as in Example 1 except that the toner in Example 6 was changed from toner D to toner E shown below, using the same development conditions as in Example 3.
* Example of toner production 100 g of hydrophobic silica fine particles with an average particle size of 30 nm, 100 g of hydrophobic titanium fine particles with an average particle size of 30 nm, and 100 g of hydrophobic silica fine particles with an average particle size of 100 nm are added to 20 kg of the above fine particles and mixed with stirring. Except that, magenta electrophotographic toner E was obtained in the same manner as in Example 6.

Example 8
Using the toner and carrier C in Example 6 above, a developer having a toner concentration (TC) of 7.0 wt% was prepared, and quality evaluation was performed by modifying a Ricoh IPSiOcolor 8100 machine. As an initial setting of the developer, the toner density sensor output Vt is adjusted to 2.50 V and set as a reference value. Other development conditions are the same as those in Example 1. An image with an image area of 20% was output while maintaining this reference value. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

Example 9
Using the toner and carrier in Example 9, an image with an image area of 1% was output under the same development conditions. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

Example 10
Using the toner and carrier C in Example 9 above, a developer having a toner concentration (TC) of 10.0 wt% was prepared, and quality evaluation was performed by modifying a Ricoh IPSiOcolor 8100 machine. As an initial setting of the developer, the toner density sensor output Vt is adjusted to 2.00 V and set as a reference value. Other development conditions are the same as those in Example 1. An image with an image area of 20% was output while maintaining this reference value. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

Example 11
Image output and evaluation were performed in the same manner as in Example 1 except that the toner in Example 6 was changed from toner D to toner F shown below, using the same development conditions as in Example 3.
* Production example of toner The same method as in Example 6 except that 100 g of hydrophobic titanium fine particles having an average particle size of 30 nm and 100 g of hydrophobic silica fine particles having an average particle size of 100 nm are added and stirred and mixed with respect to 20 kg of the fine particles. Thus, a magenta electrophotographic toner F was obtained.

Example 12
A developer having a toner concentration of 7.0% was prepared using the toner and carrier C in Example 9, and the quality was evaluated by modifying the Ricoh IPSiOcolor 8100 machine to the development conditions shown in Table 4. As an initial setting of the developer, the toner density sensor output Vt is adjusted to 3.00 V and set as a reference value. An image with an image area of 20% was output while maintaining this reference value. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

Example 13
A developer with a toner concentration of 7.0% was prepared using the toner and carrier C in Example 9, and the quality was evaluated by modifying the Ricoh IPSiOcolor 8100 machine to the development conditions shown in Table 5. As an initial setting of the developer, the toner density sensor output is adjusted to 3.00 V and set as a reference value. An image with an image area of 20% was output while maintaining this reference value. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

[Comparative Example 1]
Image output and evaluation were performed in the same manner as in Example 1 except that the carrier in Example 1 was changed from Carrier A to Carrier B shown below, using the same toner as in Example 1.
* Production Example of Carrier B A silicone resin (SR2411 manufactured by Toledo Corning Silicone) was diluted to obtain a silicone resin solution (solid content: 5%).
Using a fluidized bed coating apparatus, the above-mentioned silicone resin solution is placed on the surface of each particle having an average particle diameter of 60 μm carrier core particles (MnMgSr ferrite, 1 KOe magnetic moment 77 emu / g) at 5 ° C. in an atmosphere of 100 ° C. Then, the coating was applied at a rate of about 40 g / min and further heated at 240 ° C. for 2 hours to obtain Carrier B having a film thickness of 0.53 μm and a true specific gravity of 5.0 g / cm 3. The film thickness was adjusted according to the amount of the coating solution.

[Comparative Example 2]
Image output and evaluation were performed in the same manner as in Example 1 except that the toner of Example 1 was changed from toner A to toner G shown below, using the same development conditions as in Example 3.
* Example of Toner Production Using the kneaded material of Example 1 above, finely pulverized to a mean particle size of 12 μm with a jet mill pulverizer equipped with a flat impingement plate in the pulverizing section, and further a DS type airflow classifier Surface treatment was carried out using a turbo mill connected to No. 1 and the average particle size was 11.5 μm. Further, fine powder classification was performed to obtain fine particles having a weight average particle diameter of 11.8 μm and a particle number ratio of 3 μm or less of 20%. To 20 kg of the fine particles, 100 g of hydrophobic silica fine particles having an average particle diameter of 30 nm and 100 g of hydrophobic titanium oxide fine particles having an average particle diameter of 30 nm were added and stirred to obtain a magenta electrophotographic toner G.

[Comparative Example 3]
Image output and evaluation were carried out in the same manner as in Example 1 using the same toner and carrier as in Example 7 except that the development conditions were changed as shown in the table below.

[Comparative Example 4]
Image output and evaluation were carried out in the same manner as in Example 1 using the same toner and carrier as in Example 7 except that the development conditions were changed as shown in the table below.

[Comparative Example 5]
Image output and evaluation were carried out in the same manner as in Example 1 except that the toner in Example 6 was changed from toner D to toner H shown below, using the same development conditions as in Example 3.
* Example of toner production 50 g of hydrophobic silica fine particles having an average particle diameter of 30 nm, 50 g of hydrophobic titanium fine particles having an average particle diameter of 30 nm, and 50 g of hydrophobic silica fine particles having an average particle diameter of 100 nm are added to 20 kg of the fine particles described above and mixed with stirring. Except that, magenta electrophotographic toner H was obtained in the same manner as in Example 6.

[Comparative Example 6]
Using the toner of Comparative Example 5 and the development conditions of Example 3, an image having an image area of 1% was output. The toner density transition, developer and image carrier charge amount distribution, particle size distribution, and image quality were evaluated for 20K sheets.

  The image density was shifted by 10 mm from the L part (left side of the image) to the R part (right side of the image) of the solid part of 290 mm in the main scanning direction × 30 mm in the sub-scanning direction, and a total of 29 points were measured with the X-rite 938 spectral densitometer. The average value of the LMR portion. A range where the image density fluctuation from the initial stage is ± 0.120 is set as an allowable level.

  Further, the image density unevenness is shifted by 10 mm from the L part (left side of the image) to the R part (right side of the image) of the solid part of 290 mm in the main scanning direction × 30 mm in the sub-scanning direction. It is the value of the difference between the maximum and the minimum in the image density at each measurement location. Then, the range where the maximum and minimum difference in image density at each measurement point is 0.050 is regarded as an allowable level.

  The toner density stability was evaluated as follows. As described above, in the series of evaluations, the reference value of the toner density sensor was set before outputting the image, and the image was output by controlling the toner density sensor to be the reference value. Therefore, it can be determined that the smaller the fluctuation range of the toner density from the initial stage, the better the stability. ± 0.30 wt% is set as an allowable level in the toner density fluctuation from the initial stage.

As can be seen from Table 9, in Examples 1 to 13, | (Q / d) _dev− (Q / d) _drum | in 20K sheets is 0.1 [f · C / 10 μm] or less, and | _ddev− d _drum | is 0.2 [μm] or less. From Examples 1 to 13, it can be seen that the image density variation is ± 0.120 or less and the density unevenness is in the range of ± 0.050, and that a good image can be maintained over time.

On the other hand, when looking at Comparative Examples 1 to 5, at least one of | (Q / d) _dev− (Q / d) _drum | at 20K sheets exceeds 0.1 [f · C / 10 μm], or at 20K sheets | D _dev −d _drum | exceeds 0.2 [μm]. In Comparative Examples 1 to 5, it can be seen that the density unevenness or the image density exceeds the allowable range, and a good image cannot be maintained.

Therefore, the average charge of the toner on the photosensitive member surface _{(Q / d) drum} and an average charge amount of the toner in the developing device (Q _{/ d)} 0.1 The difference between the _dev [f · C / _10μm If the difference between the average particle diameter d _drum of the toner on the surface of the photosensitive member and the average particle diameter d _dev of the toner in the developing device can be suppressed to 0.2 [μm] or less, the image density can be reduced. It can be seen that density unevenness can be suppressed. _{Moreover, | (Q / d) dev} - (Q / d) drum | is 0.1 [f · C / 10μm] or less _and, | or is 0.2 [[mu] m] or less | d _{dev -d drum} By examining whether or not, it can be determined whether or not the image forming apparatus can form a good image.

(1)
As described above, according to the image forming apparatus of the present embodiment, | (Q / d) _dev− (Q / d) _drum | is 0.1 [f · C / 10 μm] or less even when the toner is deteriorated. If the image forming apparatus satisfies | d _dev −d _drum | of 0.2 μm or less, it is possible to maintain a good image with no decrease in image density or uneven image density over time.
(2)
Further, the developer carrying amount per unit area on the developer carrying member immediately after regulation by the developer regulating member is set to 20 to 60 [mg / cm ² ], so that between the developer carrying member and the image carrying member. It is not necessary to increase the electric field to be applied, and the occurrence of agent dropping can be suppressed on the downstream side of the developer carrying member in the developer transport direction relative to the developer regulating member. Further, a decrease in fluidity in the space between the image carrier and the developer carrier is suppressed, and it is possible to suppress the smooth supply of toner to the electrostatic latent image on the image carrier. . As a result, it is possible to suppress image density reduction and density unevenness.
(3)
Further, by adding hydrophobic silica having a large particle diameter of 80 to 140 [nm] to the toner, performance is further improved with respect to transferability and developability.
(4)
Further, hydrophobic silica fine particles having an average particle diameter of 50 [nm] or less and hydrophobic titanium oxide fine particles having an average particle diameter of 50 [nm] or less are contained in the toner in an amount of 0.2 [wt%] to 1.2 [wt%]. The following are added. By making the average particle size of hydrophobic silica fine particles and hydrophobic titanium oxide fine particles 50 nm or less, electrostatic force and van der Waals force with toner can be remarkably improved, and toner fluidity is improved. Can be made. As a result, a desired charge level of the developer can be obtained, good image quality can be obtained, and transfer residual toner can be further reduced. Further, the amount of hydrophobic silica fine particles added is in the range of 0.3 to 1.5 [wt%] and the amount of hydrophobic titanium oxide fine particles is in the range of 0.2 to 1.2 [wt%]. The rising characteristics are not significantly impaired, and even if copying is repeated, stable image quality can be obtained and toner scattering can be suppressed.
(5)
A developer having an average charge amount Q / M of 15 to 40 [-μC / g] in a toner concentration range of 5.0 to 9.0 [wt%] is used. As a result, toner scattering and a decrease in image density are suppressed, and a stable image quality can be obtained over a long period even with a developer using a small particle carrier and a small particle toner.
(6)
In addition to image density stability, the weight average particle diameter of the toner is 5.0 to 8.0 [μm], and the weight average / number average particle diameter ratio Dw / Dn is 1.20 or less. Also, the resolution can be improved and a higher quality image can be obtained.
(7)
In addition, by setting the number ratio of particles of 3 [μm] or less in the toner particle size distribution to 5% or less, the quality in fluidity and storage stability can be improved, toner replenishment into the developing device and toner charge rising. Good levels of properties can be obtained.
(8)
Further, the charge rising ratio Z (%) of the toner is set to 70 (%) or more. By setting the toner charge rising ratio Z (%) to 70 (%) or more, toner scattering and background contamination can be greatly improved.
(9)
Further, in the image forming apparatus of the present embodiment, when the peripheral speed of the developing sleeve is Vs and the peripheral speed Vp of the photosensitive member, Vs / Vp is adjusted to be in the range of 1.5 to 2.5. . When Vs / Vp is lower than 1.5, the developer passing time through the electrostatic latent image is shortened, so that the developing ability is reduced and an image having a large area is output. The decrease in density becomes remarkable. If Vs / Vp is higher than 2.5, that is, if the contact time between the developer and the electrostatic latent image is increased, an abnormal image is generated. Therefore, a high-quality image can be obtained by adjusting Vs / Vp within the range of 1.5 to 2.5.
(10)
Further, according to the developing device of the present embodiment, | (Q / d) _dev− (Q / d) _drum | is 0.1 [f · C / 10 μm] or less and | When d _dev −d _drum | satisfies 0.2 [μm] or less, it is possible to maintain a good image with no decrease in image density or uneven image density over time.
(11)
In addition, the developing device of the present embodiment is integrally supported together with at least the photosensitive member to constitute a process cartridge. As a result, members around the photoconductor such as a developing device can be attached to and detached from the printer device body together with the photoconductor, thereby improving maintainability.
(12)
Further, according to the determination method of the image forming apparatus of the present embodiment, the average toner charge amount (Q / d) _dev in the developing device, the average toner charge amount (Q / d) _{drum of the} photosensitive member, and the developing device internal The average toner particle diameter d _dev and the average toner particle diameter d _drum on the photoconductor are detected, respectively, and the average toner charge amount (Q / d) _dev in the developing device and the average toner charge amount of the photoconductor ( Q _{/ d)} relationship with the _drum is _{| (Q / d) dev -} (Q / d) drum | ≦ 0.10 and whether it meets the [f · C / 10μm] relationship, the toner average particle size d By detecting whether or not the relationship between _dev and the average particle diameter d _drum of the toner on the photoconductor satisfies | d _dev −d _drum | ≦ 0.20 [μm], the image forming apparatus Risk of reducing image density It can be determined whether or not the. By using this determination method, if the image forming conditions of the image forming apparatus are changed so as to satisfy the above conditions, it is possible to obtain an image forming apparatus that does not have density unevenness or image density decrease over time.
(13)
Further, according to the method of manufacturing the image forming apparatus of the present embodiment, in a state where the unused developer is sufficiently deteriorated by stirring for 1 hour, | (Q / d) _dev− (Q / d) _drum | ≦≦ The toner average particle diameter d _dev in the developing apparatus after stirring the unused developer for one hour, which satisfies the relationship of 0.10 [f · C / 10 μm], and the unused developer Design conditions satisfying the required specifications satisfying the relationship of | d _dev −d _drum | ≦ 0.20 [μm] with the toner average particle diameter d _drum of the latent image carrier after the time stirring are determined. The image forming apparatus is manufactured based on the above. Thereby, it is possible to manufacture an image forming apparatus in which occurrence of image density unevenness and image density reduction is suppressed over time.

1 is a schematic configuration diagram illustrating an internal configuration of a printer according to an embodiment. FIG. 2 is a schematic configuration diagram showing an internal configuration of a photoreceptor unit. The schematic block diagram which shows the structure of a writing device. FIG. 2 is a schematic configuration diagram showing an internal configuration of a developing device. FIG. 6 is a diagram illustrating a charge distribution and a particle size distribution of toner in the developing device in an initial state. FIG. 4 is a diagram illustrating a charge distribution and a particle size distribution of toner attached on a photoreceptor in an initial state. The figure which showed the charge distribution and particle size distribution of the toner in a developing device after stirring unused toner for 1 hour. FIG. 6 is a diagram showing a charge distribution and a particle size distribution of toner adhered on a photoreceptor after stirring unused toner for one hour. The perspective view which shows the internal structure of a developing device. FIG. 2 is a schematic configuration diagram showing an internal configuration of a process cartridge. 1 is a schematic configuration diagram of an image forming apparatus provided with a process cartridge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Device main body 2 Photoconductor unit 3 Transfer belt 4 Photoconductor 5 Developing device 6 Writing device 7 Duplex unit 8 Reversing unit 9 Fixing device 500 Process cartridge

Claims (13)

A latent image carrier that carries a latent image, and a developer composed of toner and carrier is carried on the developer carrier and conveyed to a development area that faces the latent image carrier, and the latent image on the latent image carrier. In an image forming apparatus equipped with a developing device that develops toner into a toner image, an average toner charge amount (Q / d) _dev in the developing device after stirring the unused developer for one hour, and unused average toner charge amount of the latent image carrier after stirring one hour the developer of _{(Q / d) drum} and is _{| (Q / d) dev -} (Q / d) drum | ≦ 0.10 [f · C / 10μm]
Satisfy the relationship
In addition, the toner average particle diameter d _dev in the developing device after stirring the unused developer for one hour, and the toner average particle diameter d _drum of the latent image carrier after stirring the unused developer for one hour are used. And
An image forming apparatus satisfying a relationship of | d _dev −d _drum | ≦ 0.20 [μm]. The image forming apparatus according to claim 1, wherein the developing device forms a gap with the developer carrying member, and allows the developer on the developer carrying member to pass through the gap, whereby the developer carrying member is placed on the developer carrying member. A developer regulating member that regulates the layer thickness of the developer, and a developer carrying amount per unit area on the developer carrying member immediately after regulation by the developer regulating member is 20 [mg / cm ² ] or more, 60 [Mg / cm ² ] or less. The image forming apparatus according to claim 1 or 2,
An image forming apparatus, wherein the toner is added with hydrophobic silica fine particles having an average particle diameter of 80 [nm] or more and 140 [nm] or less. The image forming apparatus according to claim 1, 2 or 3.
In the toner, hydrophobic silica fine particles having an average particle size of 50 [nm] or less are 0.3 [wt%] or more and 1.5 [wt%] or less, and the average particle size is 50 [nm] or less. An image forming apparatus, wherein titanium oxide fine particles are added in an amount of 0.2 [wt%] or more and 1.2 [wt%] or less. The image forming apparatus according to claim 1, 2, 3, or 4.
The developer has a toner concentration of 5.0 wt% or more and 9.0 wt% or less, and the average charge amount (Q / M) of the developer is 15 [−μC / g] or more and 40 [−μC / g]. An image forming apparatus comprising: The image forming apparatus according to claim 1, 2, 3, 4, or 5.
The toner has a weight average particle diameter of 5.0 μm or more and 8.0 μm or less, and a ratio (Dw / Dn) of the weight average particle diameter (Dw) to the number average particle diameter (Dn) is 1.20 or less. An image forming apparatus. The image forming apparatus according to claim 1, 2, 3, 4, 5 or 6.
An image forming apparatus comprising: a developer having a toner particle size ratio of 3 μm or less and a particle number ratio of 5% or less. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6 or 7.
The toner and carrier used in the developer are the same as the charge amount Q ₆₀₀ obtained when the carrier and the toner are stirred and mixed for 10 minutes under normal temperature and normal humidity and a toner concentration of 5% or less. If the charge amount Q ₂₀ obtained when stirring and mixing for 20 seconds,
Z (%) = (Q ₂₀ / Q ₆₀₀ ) × 100
An image forming apparatus using a toner and a carrier that can obtain a charge rising ratio Z (%) calculated by (1) of 70 (%) or more. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7 or 8.
An image forming apparatus, wherein the relationship between the peripheral speed Vs of the developer carrier and the peripheral speed Vp of the image carrier satisfies a relationship of 1.5 ≦ (Vs / Vp) ≦ 2.5. A developer comprising a toner and a carrier is carried on a developer carrying member, conveyed to a developing area facing the latent image carrying member, and the latent image on the latent image carrying member carrying the latent image is developed to form a toner image. In the developing device
Average toner charge amount (Q / d) _dev in the developing device after stirring the unused developer for one hour, and average toner charge amount of the latent image carrier after stirring the unused developer for one hour (Q / d) _drum is | (Q / d) _dev− (Q / d) _drum | ≦ 0.10 [f · C / 10 μm]
Satisfy the relationship
In addition, the toner average particle diameter d _dev in the developing device after stirring the unused developer for one hour, and the toner average particle diameter d _drum of the latent image carrier after stirring the unused developer for one hour are used. And
A developing device satisfying a relationship of | d _dev −d _drum | ≦ 0.20 [μm]. A latent image carrier;
Charging means for charging the surface of the image carrier;
Exposure means for exposing the charged surface of the latent image carrier to form a latent image;
Developing means for developing a latent image on the latent image carrier;
Detachable from the main body of the image forming apparatus having a cleaning means for cleaning the surface of the latent image carrier,
In a process cartridge in which at least the latent image carrier and the developing unit are integrally supported,
11. A process cartridge according to claim 10, wherein the developing means is the developing device according to claim 10. Detecting characteristics in the image forming apparatus comprising a latent image carrier that carries a latent image and a developing device that supplies toner to the latent image on the latent image carrier and develops the same. In the evaluation method of the image forming apparatus for performing the evaluation,
The characteristics include an average toner charge amount (Q / d) _dev in the developing device, an average toner charge amount (Q / d) _{drum of the} latent image carrier, an average toner particle diameter d _dev in the developing device, The average toner particle size d _drum on the image carrier is detected, and the average toner charge amount (Q / d) _dev in the developing device and the average toner charge amount (Q / d) _{drum of the} latent image carrier The relationship of | (Q / d) _dev− (Q / d) _drum | ≦ 0.10 [f · C / 10 μm]
Whether or not
The relationship between the toner average particle diameter d _dev and the toner average particle diameter d _drum on the latent image carrier is | d _dev −d _drum | ≦ 0.20 [μm].
An evaluation method for an image forming apparatus, characterized by evaluating whether or not In a manufacturing method of an image forming apparatus for determining a required specification of an image forming apparatus, determining a design condition of the image forming apparatus that satisfies the required specification, and manufacturing the image forming apparatus based on the design condition, the required specification is: Average toner charge amount (Q / d) _dev in the developing device after stirring the unused developer for one hour, and average toner charge amount of the latent image carrier after stirring the unused developer for one hour (Q / d) _drum is | (Q / d) _dev− (Q / d) _drum | ≦ 0.10 [f · C / 10 μm]
Satisfy the relationship
In addition, the toner average particle diameter d _dev in the developing device after stirring the unused developer for one hour, and the toner average particle diameter d _drum of the latent image carrier after stirring the unused developer for one hour are used. And
| D _dev −d _drum | ≦ 0.20 [μm] is satisfied.

Images