JP6520282B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus.

  By supplying the developer to which the oil-impregnated particles are added, the wear of the cleaning blade is reduced as compared with the case where the oil-impregnated particles are not present.

  Patent Document 1 describes that a damming means for blocking toner is provided in the vicinity of the cleaning blade.

  In Patent Document 2, an opening is provided in the toner reservoir. The toner temporarily stagnates at the wedge portion of the photosensitive body and the toner reservoir, and the stagnant toner is disturbed at the convex portion, the toner is supplied to the non-image position in the axial direction, and abrasion of the BLD and the photosensitive body is suppressed. Have been described.

JP 2005-004051 A JP, 2010-140049, A

  In some cases, the developer may not uniformly reach the cleaning area of the cleaning blade.

  An object of the present invention is to obtain an image forming apparatus capable of uniformly distributing a developer to a cleaning area of a cleaning blade.

The invention according to claim 1 is formed on the image carrier by a developer which is disposed in contact with the image forming surface of the circulating image carrier and to which oil-impregnated particles are added at a predetermined ratio. A cleaning blade for scraping the developer remaining on the image carrier after transferring the formed image onto a recording medium;
A plate disposed upstream of the cleaning blade in the circumferential direction of the image carrier and extending in a direction intersecting the circumferential direction;
Have,
The plates that include a plurality of convex portions arranged in a staggered manner.

In the invention according to claim 2, in the invention according to claim 1, the plate is
Resilient and provided with a biased film-like substrate in a direction in contact with the image carrier,
Wherein the plurality of protrusions are provided on a surface that faces said image carrier in the substrate are arranged in a direction crossing the circumferential direction and the circumferential direction of the image carrier.

In the invention according to claim 3 , in the invention according to claim 1 or 2 , the addition amount of the oil-impregnated particles is 0.05 wt% to 0.3 wt% with respect to 1 gram of the developer. .

According to the first and second aspects of the present invention, the developer to which the oil-impregnated particles are added can be uniformly distributed to the cleaning area of the cleaning blade.
Further, the forced guidance including the drive system is not performed, and the developer can be uniformly distributed to the cleaning area of the cleaning blade according to the movement of the untransferred developer.

According to the third aspect of the present invention, it is possible to reduce the occurrence of color streaks of abrasion due to scraping of the developer by the cleaning blade, as compared with the case where the oil impregnated particles are not within the range.

FIG. 2 is a schematic view showing the configuration of the image forming apparatus according to the present embodiment as viewed from the front side. It is an enlarged view of the cleaning device concerning this embodiment. It is a plate which concerns on this Embodiment, (A) is a front view of the plate surface in which the convex part was formed, (B) is a bottom view of FIG. 3 (A). FIG. 6 is a front view showing a process of diffusing the toner remaining in the form of a chart image by the plate and the convex portion according to the present embodiment. It is an oil impregnation elastomer particle addition amount-cleaning blade wear degree characteristic chart, and an oil impregnation elastomer particle addition amount-color streak NG frequency characteristic chart. (A) is a perspective view which specifies the field of a peripheral surface of a photo conductor drum, (B) is a characteristic view showing the degree of wear of the cleaning blade corresponding to each field specified with Drawing 6 (A). It is a plate concerning modification 1, and (A) is a front view of the plate surface in which the line-like projection part was formed, (B) diffuses the toner which remained in the chart image shape by the plate and modification concerning a modification 1 It is a front view which shows the process to do. FIG. 10 is an enlarged view of a cleaning device (toner reservoir formation) according to a second modification;

  FIG. 1 is a schematic block diagram of an image forming apparatus 10 to which the present embodiment is applied.

  The image forming apparatus 10 can form an image in full color in a 4-series tandem system, and sequentially forms an image of each color of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side. The electrophotographic first image forming unit 12Y, the second image forming unit 12M, the third image forming unit 12C, and the fourth image forming unit 12K that output the data are arranged at predetermined intervals.

  In the following, since the first image forming unit 12 Y, the second image forming unit 12 M, the third image forming unit 12 C, and the fourth image forming unit 12 K of the four series have the same configuration, when collectively referred to Unit 12 ”. Further, in the case where the respective constituent members of the image forming unit 12 are described without distinction, in the drawings, the end ("Y", "M", "C", "K") of the reference numerals of the respective constituent members described is omitted. May.

  The image forming unit 12 includes a drum-shaped photosensitive drum 14 as an image carrier having a photosensitive layer on the surface, a charging device 16 for uniformly charging the photosensitive drum 14, and the like. An exposure device 18 for irradiating the photosensitive drum 14 with image light to form an electrostatic latent image, a developing device 20 for transferring toner to the latent image to form a toner image, and toner remaining on the photosensitive drum 14 after transfer. And a cleaning device 26 for removing the

  Further, the image forming apparatus 10 includes an endless belt-like intermediate transfer belt 22 stretched around the photosensitive drums 14 of each of the four image forming units 12 in a rotatable manner and a path on the photosensitive drums 14. And a primary transfer roll 24 for transferring the toner image formed on the intermediate transfer belt 22 to the intermediate transfer belt 22.

  The image forming apparatus 10 further includes a recording paper transport mechanism 28 for transporting the recording paper P stored in the paper tray 29 and a fixing device 30 for fixing the toner image on the recording paper P.

  The intermediate transfer belt 22 is wound around a primary transfer roll 24, a drive roll 32 that is rotationally driven, a tension roll 34 that adjusts tension, and a backup roll 36.

  Further, a secondary transfer roll 38 for transferring the toner image on the intermediate transfer belt 22 onto the recording paper P conveyed by the recording paper conveyance mechanism 28 at a position facing the backup roll 36 with the intermediate transfer belt 22 interposed therebetween. Is provided. In addition, after the toner image is transferred onto the recording paper P by the secondary transfer roll 38, a toner removing device 40 is provided for removing the toner remaining on the intermediate transfer belt 22.

  The recording paper transport mechanism 28 includes a pickup roll 42, transport rolls 44 and 46, paper guides 48, 50, 52, 54 and 56 for guiding the transport movement path, a paper discharge roll 58, a paper discharge tray ) And so on. The recording paper transport mechanism 28 transports and drives the recording paper P stored in the paper tray 29 to a secondary transfer position where the secondary transfer roll 38 and the backup roll 36 face each other across the intermediate transfer belt 22, and then The sheet is conveyed and driven from the secondary transfer position to the fixing device 30, and then is conveyed and driven from the fixing device 30 to the sheet discharge tray.

  FIG. 2 is a cross-sectional view showing the detailed configuration of the cleaning device 26 facing the peripheral surface of the photosensitive drum 14.

  The cleaning device 26 includes a cleaner housing 60 disposed close to the photosensitive drum 14 and opening on the side facing the photosensitive drum 14. One end of a seal member 62 is fixed to the upper open end of the cleaner housing 60.

  The other end of the seal member 62 is in contact with the photosensitive drum 14 to substantially close the gap between the photosensitive drum 14 and the cleaner housing 60, and the waste toner T contained in the cleaning device 26 is externally transferred. Prevent leakage or splashing. For the sealing member 62, for example, a thermoplastic polyurethane film having a thickness of 0.1 mm is used.

  Inside the cleaner housing 60, a cleaning blade 64 as a cleaning member is disposed downstream of the seal member 62 in the rotational direction of the photosensitive drum 14 (indicated by an arrow in the drawing). Further, an auger 66 is disposed at a lower portion in the cleaner housing 60.

  The cleaning blade 64 is formed of an elastic material in a plate shape having a predetermined thickness. As the blade material, for example, thermosetting polyurethane rubber is used which is excellent in mechanical properties such as abrasion resistance, chipping resistance and creep resistance.

  The material of the cleaning blade 64 is not limited to urethane rubber, and functional rubber materials such as silicone rubber, fluororubber, ethylene / propylene / diene rubber and the like are used. Further, the cleaning blade 64 is adhered to the sheet metal 68, and the leading edge portion is provided so as to abut on the surface of the photosensitive drum.

  The blade pressurizing system in the present embodiment adopts a low displacement constant displacement system having a simple structure. However, the blade pressing method is not limited to the constant displacement method, and a constant load method in which the contact pressure hardly changes with time may be used.

  In the cleaning device 26 having such a configuration, the untransferred toner (transfer residual toner T) remaining on the surface of the photosensitive drum 14 is scraped off by the cleaning blade 64 after passing in front of the seal member 62 as it is.

  The toner scraped off by the cleaning blade 64 is temporarily stored in the cleaner housing 60, and finally conveyed and discharged by the auger 66 to the outside of the side of the cleaning device 26.

  The cleaning device 26 is configured as a unit (process cartridge) integral with at least the photosensitive drum 14, and is removable from the image forming apparatus in the state of the unit.

  Here, in the present embodiment, the plate 70 is provided between the seal member 62 and the cleaning blade 64.

  That is, one end of the plate 70 is fixed to the upper open end of the cleaner housing 60 to which one end of the sealing member 62 is fixed so as to be superimposed on the sealing member 62.

  The plate 70 is disposed along the tangential direction of the photosensitive drum 14, and a plurality of convex portions 72 are provided on the opposing surface thereof.

  As shown in FIG. 3, the plate 70 is formed in a horizontally long rectangular shape corresponding to the axial length dimension of the drum 14 as a base material, and the upper end in the height direction shown in FIG. This corresponds to one end fixed to the upper open end of the housing 60.

  At the lower end portion in the height direction of the plate 70, a plurality of convex portions 72 (convex portion groups) are formed extending in two rows in the height direction.

  In the following, the upstream side of the photosensitive drum 14 in the rotational direction is referred to as a first line, and the downstream side is referred to as a second line.

  The convex portions 72 of each row are provided at a constant interval, and are arranged offset in the width direction between the rows by a half of the constant interval, forming a so-called staggered arrangement. The amount of displacement is not limited to 1/2 as long as the convex portions 72 in a particular row correspond to the space area between the two convex portions 72 in the other row. Moreover, when forming the convex part group of three or more lines, there may exist an area | region which does not become a zigzag arrangement in part. Furthermore, the plurality of convex portions may be formed irregularly in a predetermined area of the plate without being restricted to the rows to form a zigzag shape.

  As shown in FIG. 2, the convex portion 72 has a hemispherical shape, and the vertex of the convex portion 72 is in contact with the circumferential surface of the photosensitive drum 14 by the elastic force of the plate 70.

  The plate 70 applied to the present embodiment is, for example, a resin film having a thickness dimension of 0.05 to 0.1 mm. As a resin film, PET (polychlorinated terephthalate) is representative.

  The convex portion 72 in the first row is a hemispherical dimple having a diameter of 1.5 mm and a protruding height dimension of 0.75 mm at a position of height H1 (3.5 mm) from the lower end portion of FIG. The convex portions 72 were arranged at a pitch of P1 (5 mm).

  Further, the convex portions 72 in the second row are arranged in a staggered arrangement by the convex portions 72 in the first row at a position of height H 2 (2 mm) from the lower end portion of FIG. The convex portions 72 which are hemispherical dimples having a diameter of 1.5 mm and a protruding height of 0.75 mm were arranged at a pitch of P2 (5 mm).

  The convex portion 72 interferes with the transfer residual toner T moving with the rotation of the photosensitive drum 14 as shown in FIG. 4, and has a function of restricting the movement of the transfer residual toner T.

  The transfer residual toner T whose movement is limited is guided so as to bypass the convex portion 72. At this time, since the convex portions 72 are arranged in a staggered arrangement in two lines, the transfer residual toner T is diffused by being deviated from the movement with regularity (the movement along the rotation direction of the photosensitive drum). In this state, the cleaning blade 64 is reached.

  FIG. 4 shows the transfer residual toner T remaining after the chart image for adjusting the toner condition of each color is formed on the photosensitive drum 14.

  The chart image is a strip image of Y, M, C and K colors formed in the rotational direction of the photosensitive drum 14, and in FIG. It is formed.

  The residual transfer toner T remaining after the formation of the chart image interferes with the convex portions 72 (first line) of the plate 70, and as shown by the arrow A in FIG. Distribute to divert to the left and right of.

  Further, the transfer residual toner T dispersed to bypass is interfered with the convex portion 72 (second line) of the next step, and as shown by an arrow B in FIG. Distributed to further bypass.

  As a result, the transfer residual toner T remaining in the form of a belt is spread over the entire area in the axial direction of the photosensitive drum 14.

(Toner additive)
For cleaning with the cleaning blade 64, it is effective to supply oil. Therefore, oil impregnated elastomer particles as oil impregnated particles are added to the toner.

  The oil-impregnated elastomer particles are not particularly limited as long as they contain an oil, and those having a crosslinked structure or those having a porous body may be used.

  The oil contained in the oil-impregnated elastomeric particles may be a compound having a melting point of less than 20 ° C., that is, a compound that is liquid at 20 ° C., and various known silicone oils and lubricating oils may be mentioned. Further, the oil contained in the oil-impregnated elastomer particles may be contained singly or in combination of two or more.

  The oil to be impregnated into the oil-impregnated elastomeric particles is preferably silicone oil. As silicone oils, silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, phenylmethylpolysiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, fluorine-modified polysiloxane, methacryl-modified Examples thereof include reactive silicone oils such as polysiloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane.

  Among these, dimethylpolysiloxane (also referred to as "dimethyl silicone oil") forms a uniform external additive dam uniformly in the width direction of the cleaning blade, and does not cause a secondary failure due to contamination in other processes. Particularly preferred for reasons such as

  Below, the example of preparation of oil impregnation elastomeric particle Po is shown.

  40 parts of styrene, 10 parts of butadiene, 25 parts of diethylbenzene as a diluent and 50 parts of isoamyl alcohol, and 2.0 parts of dimethyl 2,2'-azobis (2-methylbutyronitrile) as a polymerization initiator were mixed and dissolved.

  This mixture was poured into a dispersion solution of 10 parts of calcium carbonate powder (number average particle diameter: 0.1 μm, TP-123 manufactured by Okutama Kogyo Co., Ltd.), 50 parts of sodium chloride and 200 parts of water. After emulsification was performed at 6,000 rpm for 1 minute using a mixer, a polymerization reaction was performed at 70 ° C. for 20 hours in a nitrogen atmosphere.

  Then, after adding hydrochloric acid to decompose calcium carbonate, water washing was performed, and then washing with ethanol to remove the diluent. Furthermore, wet classification was performed to select elastomer particles having a number average particle diameter of 3 μm, and vacuum drying was performed at 100 ° C. for 12 hours.

  Thereafter, 150 parts of dimethyl silicone oil (Shin-Etsu Chemical Co., Ltd., model number: KM 351, viscosity at 25 ° C .: 50 cs) is dissolved in 1,000 parts of ethanol and mixed with 100 parts of elastomer particles with stirring, using an evaporator The solvent ethanol was distilled off and dried to obtain an oil-containing elastomer 1. The number average particle diameter of the obtained oil-containing elastomer was 3 μm, and the sphericity was 0.95.

  The operation of the present embodiment will be described below.

  Since the image forming unit 12 has substantially the same configuration, the first image forming unit 40Y for forming a yellow image disposed on the upstream side in the traveling direction of the intermediate transfer belt 22 will be representatively described here. . Note that, instead of yellow (Y), members having the same functions as those of the first image unit 40Y are given the same reference numeral with magenta (M), cyan (C), and black (K) attached. Descriptions of the second to fourth image forming units 40M, 40C, and 40K are omitted.

  First, prior to operation, the surface of the photosensitive drum 14Y is charged to a potential of about -600 V to -800 V by the charging device 16Y.

  The photosensitive drum 14Y is formed by laminating a photosensitive layer on a conductive metal substrate, and usually has a high resistance. However, when the LED light is irradiated, the specific resistance of the portion irradiated with the LED light is It has a changing nature.

  Therefore, a light beam (for example, LED light) for exposure is output from the exposure device 18 on the surface of the charged photosensitive drum 14Y according to the image data for yellow sent from the control unit (not shown). The light beam is applied to the photosensitive layer on the surface of the photosensitive drum 14Y, whereby an electrostatic latent image of a yellow printing pattern is formed on the surface of the photosensitive drum 14Y.

  The electrostatic latent image is an image formed on the surface of the photosensitive drum 14Y by charging, the specific resistance of the irradiated portion of the photosensitive layer is reduced by the light beam, and the charge on the surface of the photosensitive drum 14Y is charged. Is a so-called negative latent image which is formed by the flow, while the charge of the portion not irradiated with the light beam remains.

  The electrostatic latent image thus formed on the photosensitive drum 14Y is rotated to a predetermined development position by the rotation of the photosensitive drum 14Y. Then, at this development position, the electrostatic latent image on the photosensitive drum 14Y is made visible (toner image) by the developing device 20Y.

  In the developing device 20Y, a yellow toner manufactured by an emulsion polymerization method is accommodated. The yellow toner is frictionally charged by being stirred inside the developing device 20Y, and has a charge of the same polarity (−) as the charge on the surface of the photosensitive drum 14Y.

  When the surface of the photosensitive drum 14Y passes through the developing device 20Y, yellow toner is electrostatically attached only to the electrostatic latent image portion on the surface of the photosensitive drum 14Y, and the latent image is developed by the yellow toner. Ru.

  The photosensitive drum 14Y continues to rotate, and the toner image developed on the surface of the photosensitive drum 14Y is conveyed to a predetermined primary transfer position. When the yellow toner image on the surface of the photosensitive drum 14Y is transported to the primary transfer position, a predetermined primary transfer bias is applied to the primary transfer roll 24Y, and electrostatic force from the photosensitive drum 14Y toward the primary transfer roll 24Y Acts on the toner image, and the toner image on the surface of the photosensitive drum 14Y is transferred to the surface of the intermediate transfer belt 22.

  The transfer bias applied at this time is the (+) polarity opposite to the polarity (−) of the toner, and, for example, in the first image forming unit 40Y, constant current control to about +20 to 30 μA by the control unit (not shown) It is done.

  On the other hand, the transfer residual toner on the surface of the photosensitive drum 14Y is cleaned by the cleaning device 26Y.

  The primary transfer bias applied to the primary transfer rolls 24M, 24C and 24K after the second image forming unit 40M is also controlled in the same manner as described above.

  Thus, the intermediate transfer belt 22 to which the yellow toner image is transferred in the first image forming unit 40Y is sequentially conveyed through the second to fourth image forming units 40M, 40C, and 40K, and the toner images of the respective colors are similarly superimposed. And multiple transfer.

  The intermediate transfer belt 22 on which toner images of all colors are multiply transferred through all the image forming units 12 is circumferentially transported in the direction of the arrow, and carries the images of the backup roll 36 and the intermediate transfer belt 22 in contact with the inner surface of the intermediate transfer belt 22. It leads to the secondary transfer portion constituted by the secondary transfer roll (transfer means) 12 disposed on the surface side.

  On the other hand, the recording paper P is fed between the secondary transfer roll 12 and the intermediate transfer belt 22 at a predetermined timing via the supply mechanism, and a predetermined secondary transfer bias is applied to the secondary transfer roll 12 .

  The transfer bias applied at this time is opposite in polarity (+) to the polarity (−) of the toner, and the electrostatic force from the intermediate transfer belt 22 to the recording paper P acts on the toner image, and the toner on the surface of the intermediate transfer belt 22 The image is transferred to the surface of the recording paper P.

  Thereafter, the recording paper P is fed to the fixing device 30, the toner image is heated and pressed, the color-superimposed toner image is melted, and the toner image is permanently fixed on the surface of the recording paper P. The recording paper P for which the fixing of the color image is completed is carried out toward the discharge unit, and a series of color image forming operations are completed.

  Here, in the cleaning device 26 according to the present embodiment, the transfer residual toner T remaining on the surface of the photosensitive drum 14 is scraped off by the cleaning blade 64 after it passes in front of the seal member 62 as it is.

  The toner scraped off by the cleaning blade 64 is temporarily stored in the cleaner housing 60, and finally conveyed and discharged by the auger 66 to the outside of the side of the cleaning device 26.

  Since the cleaning blade 64 is in contact with the circumferential surface of the photosensitive drum 14, the cleaning blade 64 wears over time (in some cases, the photosensitive drum 14 may also be worn). Oil-impregnated elastomeric particles are added to the toner to reduce this degree of wear.

However, even if oil-impregnated elastomeric particles are added, as shown in FIG. 4 , the transfer residual toner T remaining after forming the chart image does not exist with the existing region in the axial direction of the photosensitive drum 14 Areas may be clearly separated.

  Therefore, even if the oil impregnated elastomer particles are added to the transfer residual toner T, a region where the cleaning blade 64 comes in contact with the photosensitive drum 14 is generated in the absence of the transfer residual toner T and the oil impregnated elastomer particles. In order to solve this, it was necessary to increase the addition amount of the oil-impregnated elastomer particles, but if the addition amount of the oil-impregnated elastomer particles is increased, the number of NG color streaks may increase, which may adversely affect the image quality. The

  Therefore, in the present embodiment, the plate 70 is provided between the seal member 62 and the cleaning blade 64. The convex portion 72 is formed on the plate 70 in two lines in the rotational direction of the photosensitive drum 14.

  Due to the presence of the convex portion 72, the transfer residual toner T remaining after forming the chart image interferes with the convex portion 72 (first line) of the plate 70 as shown by the arrow A in FIG. It disperse | distributes so that it may detour on the right and left of the convex part 72 of 1st line. The transfer residual toner T dispersed in the convex portions 72 of the first row interferes with the convex portions 72 of the second row as shown by arrow B in FIG. It disperses to bypass it further.

  As a result, the transfer residual toner T remaining in the form of a band spreads throughout the axial direction of the photosensitive drum 14. This prevents the cleaning blade 64 from contacting the photosensitive drum 14 in the absence of the transfer residual toner T and the oil-impregnated elastomeric particles.

  Incidentally, in order to reduce wear by cleaning the cleaning blade 64, it is preferable that the amount of the oil-impregnated elastomer particles added is large. On the other hand, when the oil-impregnated elastomer particles are excessive, color streaks tend to be generated in the image.

  FIG. 5 shows the wear degree characteristic curve of the cleaning blade 64 with respect to the addition amount of the oil-impregnated elastomer particles, and the color streak NG frequency characteristic curve with respect to the addition amount of the oil-impregnated elastomer particles.

  As described above, the degree of wear of the cleaning blade 64 tends to decrease as the amount of the oil-impregnated elastomer particles added increases.

  On the other hand, the number of color streaks NG tends to increase as the amount of the oil-impregnated elastomer particles added increases.

  Here, as a comparative example, when the plate 70 is not present, the range between the wear upper limit level and the color streak NG generation limit level is indicated by the arrow A.

  On the other hand, in the present embodiment, the plate 70 is provided, and the transfer residual toner T is dispersed by (the convex portion 72 of) the plate 70, and the plate 70 does not exist (that is, does not disperse). Further, the wear reduction performance of the cleaning blade 64 is improved.

  In other words, the range between the wear upper limit level and the color streak generation limit level in the present embodiment (see arrow B in FIG. C) is more oil impregnated elastomer than in the absence of a plate (see arrow D in FIG. 5). It is expanded to the one with a small addition amount of particles.

  According to the improvement of the wear reduction performance of the cleaning blade 64, in the present embodiment, the addition amount (wt%) of the oil-impregnated elastomer particles to 1 g of toner in the developer is 0.05 wt% to 0.3 wt%, Preferably, it is 0.05 wt% to 0.1 wt%.

  In addition, as an example, when the plate 70 is not present (comparative example), the appropriate value of the addition amount (wt%) of the oil-impregnated elastomer particles to 1 g of toner in the developer is 0.3 wt% to 0.4 wt% . The lower limit of 0.3 wt% is an example of the wear upper limit level, and the upper limit of 0.4 wt% is an example of the color streak generation upper limit level.

  Therefore, in the present embodiment in which the plate 70 is provided, it is possible to reduce by 0.1 to 0.35 points as compared with the comparative example. As a result, in the present embodiment, the addition amount of the oil-impregnated elastomer particles can be shifted to a region where the number of occurrences of color streaks NG is small.

  Hereinafter, the additive amount of the oil-impregnated elastomer particles in the configuration (the present embodiment) in which the plate 70 (the convex portion 72) is present and the configuration (comparative example) in which the plate 70 is not present in Table 1 NG evaluation and OK / NG evaluation of the wear of the cleaning blade 64 are shown. The color streaks and wear OK / NG include a case determined by comparison with a predetermined threshold value and a case determined by a sensitivity determination. In Table 1, "○" means OK, "x" means NG, and "△" means NG although it may be used (that is, OK).

As understood from the experiments in Table 1, in Comparative Examples 1 to 6 without the plate 70, when the amount of the oil-impregnated elastomer particles added is small, the wear on the cleaning blade 64 is NG, and the oil-impregnated elastomer particles are When the addition amount is large, it becomes NG regarding the color streaks.

  On the other hand, in Embodiments 1 to 6 in which the plate 70 is provided, the wear of the cleaning blade 64 is OK (“o” and “Δ”) even if the addition amount of the oil-impregnated elastomer particles is small. That is, in the present embodiment, the presence of the plate 70 makes it possible to eliminate both the elimination of color streaks and the reduction of the wear of the cleaning blade 64.

(Experimental example)
As the recording medium P, the cleaning blade 64 is subjected to a test of maintaining 50000 rotations at the number of rotations of the photosensitive drum 14 at the axial position corresponding to AC 7.5% of the A3 size paper at a rotational speed of the photosensitive drum 14. The wear rate of was measured.

  The photosensitive drum 14 used was an aluminum base having an outer diameter of 40 mm and a thickness of 2 mm and provided with an undercoat layer, a charge generation layer, and a charge transport layer.

  The cleaning blade 64 is a 2 mm thick L-shaped metal plate coated with polyurethane rubber of MD-1 hardness 75 to 80 degrees, thickness 2 mm and width 12 mm so as to have a free length of 8 mm. The bite amount to 14 was set to 1 mm.

  The wear rate (wear degree) of the cleaning blade 64 was set to the increase rate of the cleaning blade 64 per 1000 revolutions of the photosensitive drum 14. The cross-sectional area of the portion where the edge of the cleaning blade 64 is worn is the amount of wear of the cleaning blade 64.

  In FIG. 6A, the area on the circumferential surface of the photosensitive drum 14 is the area where the transfer residual toner T is on the sheet passing section which is the area for transferring the image to the recording medium P (the sheet passing section Image area 80), area without toner (sheet passing area (non-image area) 82), area without image transfer to recording medium P (In non-sheet passing area 84), photosensitivity It is located at both end portions in the axial direction of the body drum 14 and is classified into regions (Out non-image portion 86) not involved in image formation.

  FIG. 6B compares the degree of wear when the plate 70 is disposed (this embodiment) and when the plate 70 is not disposed (comparative example) in each of the regions classified in FIG. 6A. FIG.

  As shown in FIG. 6B, the sheet passing portion (image portion) 80 has a wear degree as low as that of the present embodiment and the comparative example.

  On the other hand, in the sheet passing portion (non-image portion) 82, the In non-sheet passing portion 84, and the Out non-image portion 86 in which the transfer residual toner T does not exist, the present embodiment is significantly worn compared to the comparative example. Low degree.

  The transfer residual toner T (in particular, the transfer residual toner T of the chart image shown in FIG. 4) is dispersed by the plate 70 (the convex portion 72) (see arrows A and B in FIG. 4). This is because the contact portion with the body drum 14 is distributed.

  As a result, since the degree of wear of the cleaning blade 64 is reduced without increasing the amount of the oil-impregnated elastomer particles, as shown in FIG. 5 described above, the amount of the oil-impregnated elastomer particles does not have color streaks NG. It becomes an area.

(Modification 1)
In the present embodiment, an example of the plate 70 is described in which the hemispherical convex portions 72 are arranged in two rows (first and second rows) and the convex portions 72 are arranged in a zigzag shape. as shown in FIG. 7 (a), it may be applied to the plate 70A in which stripe-shaped protrusions 7 2 a inclined by 45 ° with respect to the rotational direction of the photosensitive drum 14 is formed.

In the plate 70A, as shown in FIG. 7 (B), streak-like protrusions 72 A is a so-called dike, as represented in the chart image, the residual toner T that is separated of the photosensitive drum 14 It is possible to diffuse on average to the circumferential surface.

(Modification 2)
Further, in the present embodiment, the plate 70 has a role of pressing the convex portion 72 against the photosensitive drum 14 and holding the same, but further, a part of the plate 70 is extended and the back surface of the cleaning blade 64 is The overlapping portion 71 may be formed so as to overlap, and the toner accumulation region TD may be provided by the plate 70, the overlapping portion 71, and the cleaning blade 64. By providing the area TD, even if the image of characters and the like are continuously formed and the transfer residual toner T is smaller than the image, the transfer residual toner is temporarily retained and then dispersed, so the transfer residual toner Average diffusion of T is possible.

10 Image Forming Device 12Y First Image Forming Unit 12M Second Image Forming Unit 12C Third Image Forming Unit 12K Fourth Image Forming Unit 12 Image Forming Unit (Generic)
14 (CMYK) Photosensitive drum 16 (CMYK) Charging device 18 (CMYK) Exposure device 20 (CMYK) Developing device 26 (CMYK) Cleaning device P Recording paper 28 Recording paper conveyance mechanism 30 Fixing device 24 (CMYK) Primary transfer roll 32 Drive roll 34 Tension roll 36 Backup roll 38 Secondary transfer roll 40 Toner removing device 42 Pick-up roll 44, 46 Transport roll 48, 50, 52, 54, 56 Paper guide 58 Ejection roll 29 Paper tray 60 Cleaner housing 62 Seal member 64 Cleaning blade 66 auger 68 sheet metal 70 plate 72 convex part

Claims (3)

After the image formed on the image carrier is transferred to the recording medium by a developer which is disposed in contact with the image forming surface of the circulating image carrier and to which oil impregnated particles are added in a predetermined ratio A cleaning blade for scraping off the developer remaining on the image carrier;
A plate disposed upstream of the cleaning blade in the circumferential direction of the image carrier and extending in a direction intersecting the circumferential direction;
Have,
The plate is an image forming apparatus that comprise a plurality of convex portions arranged in a staggered manner. The plate is
Resilient and provided with a biased film-like substrate in a direction in contact with the image carrier,
Wherein the plurality of protrusions are provided on a surface that faces said image carrier in said base material, the circumferential direction and the image according to claim 1, characterized in that arranged in a direction transverse to the circumferential direction of the image carrier Forming device. The oil amount of impregnation particles 1 gram claim 1 or claim 2 image forming apparatus according a 0.05wt% ~0.3wt% relative developer.