Information
-
Patent Grant
-
6415129
-
Patent Number
6,415,129
-
Date Filed
Thursday, March 15, 200123 years ago
-
Date Issued
Tuesday, July 2, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
-
CPC
-
US Classifications
Field of Search
US
- 399 353
- 399 356
- 399 343
- 399 346
-
International Classifications
-
Abstract
In an electrophotographic image forming apparatus, a cleaning unit includes a brush roller made up of a paper tube and a cloth rapped around the paper tube. Straight bristles are implanted in the cloth and formed of polyester or polyamide. To form the straight bristles, the tips of loop-like bristles implanted in the cloth are cut off. Assuming that the diameter of the cloth, or brush support, is Ds (mm), then the bristles are implanted in a density ρ of 30/πDs or above (1/mm2). The individual bristle has a diameter Df of 0.05 or above (mm) and presses the surface of a photoconductive drum with a mean pressure of 10×10−5 (N) or above. The cleaning unit achieves a desirable cleaning ability without reducing the life of the image carrier, while removing contaminants from the surface of the image carrier.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a copier, printer, facsimile apparatus, multiplex machine or similar image forming apparatus. More particularly, the present invention relates to an electrophotographic image forming apparatus of the type repeating an image forming process, which includes charging, optical writing, development, image transfer and cleaning, with an image carrier to thereby sequentially form toner images on the image carrier, and sequentially transferring the resulting toner images to recording media, a cleaning unit for cleaning the surface of the image carrier, and a brush roller for the cleaning unit.
It is a common practice with an electrophotographic image forming apparatus to form, in a monochrome mode, a toner image on an image carrier and then transfer the toner image to a paper sheet, OHP (OverHead Projector) sheet or similar recording medium. After the image transfer, a cleaning unit removes toner left on the image carrier to thereby prepare the image carrier for the next image forming cycle.
In a color mode, monocolor images are sequentially formed on the image carrier while being sequentially transferred to an intermediate transfer body or another image carrier one above the other. The resulting color image completed on the intermediate transfer body is collectively transferred to a recording medium. After the image transfer, the surface of the photoconductive element and that of the intermediate image transfer body each are cleaned by a particular cleaning unit.
Each cleaning unit has customarily been implemented with a brush roller, a blade, a magnet brush or a bias roller. The brush roller has loop-like bristles or straight bristles implanted therein. The problem with loop-like bristles is that they press the image carrier, which is formed of OPC (Organic PhotoConductor) or similar resin, with a pressure several ten times to several hundred times higher than the pressure of straight bristles. The loop-like bristles therefore shave off the image carrier and cause a CTL (Carrier Transport Layer) included in the image carrier to wear, thereby reducing the life of the image carrier. Another problem is that such bristles cannot be densely implanted and therefore irregularly scrape off toner, resulting in stripe-like brush marks on the surface of the image carrier. The brush marks lower image density.
Not only toner but also ozone, NOx (nitrogen oxides) and other reactive gases produced by charging and image transfer deposit on the surface of the image carrier. Further, during image transfer, even talc, clay and paper fibers themselves deposit on the image carrier. Talk and clay are used to improve the quality of a paper surface. A cleaning member implemented by the loop brush can remove such deposits (contaminants), but a cleaning member implemented by any one of the straight brush, blade, magnet brush and bias roller cannot easily remove them. This is particularly true with an image carrier having fluorine-contained resin or wax on its surface and having a coefficient of friction of 0.2 or below, as measured by an Euler belt method.
As stated above, a conventional cleaning member with straight bristles cannot fully remove contaminants deposited on the image carrier although it can fully remove toner, as proved by experiments. Also, it was experimentally found that even bristles implanted in a higher density to increase the pressure of the entire brush, as taught in Japanese Patent Laid-Open Publication No. 9-288441 by way of example, failed to solve the above problem. Further, a greater amount of bite of the brush into the image carrier was not a solution to the problem either. The greater amount of bite caused the brush to deform (so-called creep) and thereby caused a torque to vary, resulting in irregular rotation and therefore noise and vibration.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication No. 6-337598.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to improve the cleaning ability of a cleaning unit, which is included in an electrophotographic image forming apparatus, without reducing the life of an image carrier to thereby remove even contaminants, which would lower image quality.
It is another object of the present invention to more surely prevent image quality from being lowered in an electrophotographic image forming apparatus.
It is another object of the present invention to improve the cleaning ability by easily increasing the pressure of a brush.
It is another object of the present invention to allow a brush roller to smoothly rotate without excessively increasing a load to act on an image carrier or causing it to vary.
It is another object of the present invention to further extend the life of an image carrier and promote the easy migration of toner from the image carrier, thereby obviating defective images.
It is still another object of the present invention to provide the surface of an image carrier with a coefficient of friction of 0.3 or below with a simple configuration.
It is yet another object of the present invention to cope with both of a photoconductive element and an intermediate image transfer body, which are specific forms of an image carrier.
It is a further object of the present invention to achieve the above-described objects with a cleaning unit for an electrophotographic image forming apparatus and a brush roller included in the cleaning unit.
In accordance with the present invention, in an electrophotographic image forming apparatus including a brush roller for cleaning the surface of an image carrier, the brush roller has straight bristles implanted in a density ρ (1/mm
2
) satisfying a relation:
ρ≧30
/πDs
where Ds denotes the diameter (mm) of a brush support included in the brush roller. The bristles each exert a mean pressure of 10×10
−5
(N) on the surface of the image carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which:
FIG. 1
is a fragmentary view showing an electrophotographic image forming apparatus embodying the present invention;
FIG. 2
is an enlarged fragmentary view of a cleaning unit included in the illustrative embodiment;
FIG. 3
is an isometric view showing a brush roller included in the cleaning unit in relation to a photoconductive element;
FIG. 4
is an enlarged end view of the brush roller;
FIG. 5
is a view showing a specific arrangement for measuring a mean pressure with which the individual bristle of the brush roller presses the photoconductive element;
FIG. 6
is a plot showing the lower limit of a bristle density determined with polyester bristles, polypropylene bristles and polyamide bristles;
FIG. 7
is a plot showing the lower limit of the pressure of the individual bristle also determined with polyester bristles, polypropylene bristles and polyamide bristles;
FIG. 8
is a view showing thin sheets of chrome stainless steel, playing the role of the bristles, contacting a planar surface playing the role of the photoconductive element;
FIG. 9
is a graph showing a relation between the angle of the root of the individual chrome stainless steel sheet and the distance between nearby sheets;
FIG. 10
is a graph showing a relation between the angle of the root of the individual chrome stainless steel sheet and the pressure;
FIG. 11
is a view showing toner particles deposited on the bristles in a single layer;
FIG. 12
is a plot showing the upper limit of a bristle density determined with polyester bristles, polypropylene bristles and polyamide bristles; and
FIG. 13
is a fragmentary view of an electrophotographic color image forming apparatus to which the present invention is also applicable.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to
FIG. 1
of the drawings, an electrophotographic image forming apparatus embodying the present invention is shown. As shown, the image forming apparatus includes a photoconductive drum
10
, which is a specific form of an image carrier. A charger
11
is positioned above and faces the drum
10
. The charger
11
extends in parallel to the drum
10
. A developing unit
12
, an image transfer unit
13
and a cleaning unit
14
are sequentially arranged around the drum
10
in a direction of rotation of the drum
10
, which is indicated by an arrow in FIG.
1
. An optical writing unit
15
is positioned above the charger
11
. A fixing unit
16
is positioned below the cleaning unit
14
.
In operation, while the drum
10
is in rotation, the charger
12
uniformly charges the surface of the drum
10
. The optical writing unit
15
scans the charged surface of the drum
10
with a light beam L in accordance with image data. As a result, a latent image is electrostatically formed on the drum
10
. The developing unit
12
develops the latent image with toner to thereby produce a corresponding toner image. The image transfer unit
13
transfers the toner image from the drum
10
to a paper sheet, OHP sheet or similar recording medium
17
being conveyed below the drum
10
.
The cleaning unit
14
removes the toner left on the drum
10
after the image transfer. Subsequently, a discharge lamp, not shown, discharges the surface of the drum
10
to prepare the drum
10
for the next image forming cycle. The paper sheet
17
with the toner image is conveyed to the fixing unit
16
. The fixing unit
16
fixes the toner image fixed on the paper sheet
17
. The paper sheet
17
is then driven out of the apparatus body to, e.g., a print tray.
FIG. 2
shows a specific configuration of the cleaning unit
14
. As shown, the cleaning unit
14
includes a casing
20
whose open top is closed by a lid
21
. The lid
21
supports a cleaning blade or cleaning member
23
via a blade holder
22
. The edge of the cleaning blade
23
is pressed against the surface of the drum
10
. The casing
20
rotatably supports a brush roller or another cleaning member
24
. The brush roller
24
is pressed against he surface of the drum
10
such that its circumference bites into the drum
10
by a suitable amount. A lubricant
25
is fixedly mounted on the casing
20
and held in contact with the circumference of the brush roller
24
.
A screw
26
is disposed in the bottom portion of the casing
20
for conveying toner collected from the drum
10
to one side in the axial direction of the screw
26
. A Mylar sheet
27
is fitted on the underside of the bottom open portion of the casing
20
and lightly contacts the drum
10
at its edge. The Mylar sheet
27
prevents toner scraped off by the cleaning blade
23
and brush roller
24
from dropping to the outside of the casing
20
.
As shown in
FIGS. 3 and 4
, the brush roller
24
includes a shaft
38
provided with a flange portion
33
. A paper tube
30
is fitted around the flange portion
33
. A cloth
31
with straight bristles
32
implanted therein is wrapped around the paper tube
30
. The straight bristles
32
are formed of polyester, polypropylene or polyamide and produced by cutting off the tips of loop-like bristles implanted in the cloth
31
.
In the illustrative embodiment, assuming that the cloth or brush support
31
has a diameter of Ds (mm), then the bristles
32
are implanted in a density ρ (1/mm
2
) that is greater than or equal to 30/πDs. Also, each bristle
32
has a diameter Df selected to be greater than or equal to 0.05 (mm). The individual bristle
32
presses the surface of the drum
10
with a mean pressure of 10×10
−5
(N) or above.
FIG. 5
shows a specific arrangement for measuring the mean pressure of the individual bristle
32
acting on the surface of the drum
10
. As shown, the arrangement includes an electronic balance
35
held in a horizontal position. A 100-mm wide block
36
is mounted on the electronic balance
35
. Further, a guide
37
is mounted on the block
36
. The balance
35
is initially reset to zero. On the other hand, the shaft
38
of the brush roller
24
is affixed to a height gauge, not shown, such that the shaft
38
is parallel to the top of the block
36
. Subsequently, the height of the brush roller
24
is adjusted such that the brush roller
24
bites into the block
36
by a preselected amount.
The height gauge supporting the brush roller
24
is slid to move the brush roller
24
to the top of the block
36
via the guide
37
. The brush roller
24
is held in pressing contact with the top of the block
36
for
1
minute. The value of the balance
35
is read in
1
minute to determine the pressure of the brush roller
24
acting over a width of 100 mm. This pressure is divided by the number of bristles
32
in order to produce a mean pressure for a single bristle
32
.
The straight bristles
32
are advantageous over loop-like bristles in that they reduce the wear of the CTL layer of the drum
10
and thereby extends the life of the drum
10
. Further, the straight bristles
32
can be implanted in the drum
10
more densely than loop-like bristles in order to make stripe-like brush marks on the drum
10
inconspicuous, thereby insuring desirable image quality.
Why the bristle density ρ should be greater than or equal to 30 πDs will be described hereinafter. Assume that α bristles are implanted in the cloth
31
for a unit length in the axial direction. Then, the number of bristles (linear density) α is expressed as:
α=ρπ
Ds
(1)
It was experimentally found that a linear density α less than 30 rendered brush marks conspicuous. By contrast, a linear density α of 30 or above, particularly 80 or above, successfully reduced the distance between nearby brush marks to a level that could not be observed by eye. The linear density α should therefore satisfy a relation:
α≧30 (2)
or more preferably
α≧80 (3)
The equation (1) and relation (2) derive:
ρπ
Ds≧
30
This relation may be modified as:
ρ≧30/π
Ds
Likewise the equation (1) and relation (3) derive:
ρ≧80/π
Ds
FIG. 6
plots the lower limits of densities determined with polyester bristles, polypropylene bristles and polyamide bristles. In
FIG. 6
, the ordinate and abscissa indicate single-bristle pressure and linear density α, respectively. In
FIG. 6
, bristles a at the left-hand side of a line A and having linear densities α of less than 30 (bristles/mm) scratch the surface of the drum
10
in the form of stripes when used over a long period of time. Such stripes make the charge potential or the potential after exposure irregular and thereby cause white stripes or black stripes to appear in an image.
Experiments showed that bristles b whose linear density α was greater than 30 (bristles/mm), but smaller than 80 (bristles/mm), sometimes produced stripes when undesirable conditions occurred at the same time. However, bristles c at the left-hand side of a line B and having linear densities α of 80 (bristles/mm) or above did not produce any stripe in an image in most of possible conditions.
FIG. 7
also plots the lower limits of densities determined with polyester bristles, polypropylene bristles and polyamide bristles. In
FIG. 7
, the ordinate and abscissa indicate single-bristle pressure and linear density α, respectively. In
FIG. 7
, bristles d, for example, whose linear densities α are around 1,000 (bristles/mm) and whose single-bristle pressure is between 1×10
−5
to 6×10
−5
(N/number) are conventional. The bristles d could not exhibit a sufficient cleaning ability. Even bristles e with a higher linear density could not achieve a sufficient cleaning ability.
More than 10,000 prints were produced over a long period of time with a lubricant being applied to the drum
10
. When further prints were produced in a humid environment, many images were blurred or otherwise defective. This is presumably because NOx and other active gases accumulated on the surface of the drum
10
and absorbed moisture due to the humid environment to thereby lower the surface resistance of the drum
10
. The lowered surface resistance causes the charge of a latent image to scatter.
Even bristles f and g shown in FIG.
7
and having comparatively high single-bristle pressures close to 10×10
−5
(N/number) sometimes failed to achieve a sufficient cleaning ability. Specifically, assume that the charger
11
and image transfer unit
13
adjoin or contact the drum
10
, and each is applied with an AC voltage. Then, the amount of contaminants to deposit on the drum
10
increases. In this condition, when the surface of the drum
10
had a relatively small coefficient of friction, a sufficient cleaning ability could not be achieved; in a humid environment, images were blurred. In the above range, it may be possible to obviate blurred or otherwise defective images by adjusting the contact condition, but a margin available is limited.
In
FIG. 7
, bristles h have a single-bristle pressure of 10×10
−5
(N/number) or above, i.e., above a line C were increased in rigidity. The bristles h were found to sufficiently remove the contaminants from the surface of the drum
10
even in the above-described conditions relating to the charger
11
, image transfer unit
13
, and drum
10
. The resulting images were free from defects including blur.
A load to act on the drum
10
during rotation increases with an increase in the linear density α and an increase in single-bristle pressure, making straight brushes unusable in practice. A line D shown in
FIG. 7
indicates a limit in this respect.
FIG. 8
shows, in a ten-magnification scale, thin sheets of chrome stainless steel contacting a planar surface. The chrome stainless steel is implemented by SUS prescribed by JIS (Japanese Industrial Standards). The thin sheets and planar surface are supposed to be the bristles and drum, respectively. The bristles had a diameter of 8 mm and a length of 5 mm and implanted in a brush support having a diameter of 18 mm. The bristles were caused to bite into the drum by 1.5 mm. The position where the tip of the individual bristle contacts the planar surface was read in order to determine a distance between the tips of nearby bristles. The distance was multiplied by the tangential cos γ of the angle γ of the tip of the individual bristle to thereby determine a distance between nearby bristles.
FIG. 9
shows such determined distances. In
FIG. 9
, the ordinate and abscissa indicate the distance and the angle θ of the root of the individual bristle, respectively. As for the angle θ, the angle in the direction normal to the drum (line O—O) is assumed to be zero degree.
FIG. 10
shows a relation between the angle θ of the root of the individual chrome stainless steel sheet and the pressure to act on the drum.
FIGS. 8 through 10
indicate the following:
(1) The straight bristles each contact the drum independently of the others;
(2) The distance between the bristles is smallest at a position where the bristles start contacting the drum and bend little;
(3) The distance between the bristles at the above position is about 22% of the distance measured on the cloth;
(4) A mean distance between the bristles between the above position and the initial 12 degrees is 30% of the distance measured on the cloth; and
(5) A mean distance between the bristles between the above position and the initial zero degree is 50% of the distance measured on the cloth.
It follows that when a space occupancy is 30%, nearby bristles locally press each other via toner. This, however, does not cause the torque to noticeably vary because the bristles press each other around the position where they start contacting the drum and therefore bend little.
When the space occupancy exceeds 50 %, more than one half of the brushes contacting the drum press each other via toner. As a result, the bristles do not rub the drum
10
independently of each other, but even the bristles not contacting the drum
10
contribute to the pressure. Moreover, the degree of contribution of such unexpected bristles depends on the degree of yield of the bristles and the amount of toner deposited on the bristles. The above space occupancy therefore causes the pressure of the brush acting on the drum
10
and the drive torque of the drum
10
to vary.
As shown in
FIG. 11
, assume that the individual bristle
32
of the brush roller
24
has a diameter Df, and that toner particles
40
have a diameter Dt each. Then, when the toner particles
40
deposit on the bristle
32
in a single layer, the space occupancy is (Dt+Df)
2
. By multiplying this space occupancy by the bristle density ρ, an occupancy β with respect to the cloth
31
is expressed as:
β=ρ(
Dt+Df
)
2
(4)
FIG. 12
shows a relation between the single-bristle pressure (ordinate) and the brush and toner space occupancy β determined with polyester bristles, polypropylene bristles and polyamide bristles. When the space occupancy β was 0.5 (%) or below (left-hand side of a line E), preferably 0.3 (%) or below (left-hand side of a line F), the toner particles
40
deposited on the bristles
32
did not noticeably increase the load on the drum
10
or did not vary it. The brush roller
24
could therefore smoothly rotate. The space occupancy β should therefore satisfy the following relation:
β≦0.5 (5)
or more preferably
β≦0.3 (6)
The equation (4) and relation (5) derive:
ρ(
Dt+Df
)
2
≦0.5
This relation may be modified as:
ρ≦0.5/(
Dt+Df
)
2
Likewise, the equation (4) and relation (6) indicate that the bristle density ρ should preferably satisfy a relation:
ρ≦0.3/(
Dt+Df
)
2
In the above-described type of image forming apparatus, the surface of the drum
10
should preferably have a coefficient of friction of 0.3 or below in order to reduce wear and extend the life. In the illustrative embodiment, the brush roller
24
in rotation shaves off the lubricant
25
and applies it to the drum
10
, maintaining the above coefficient of friction of 0.3 or below. In addition, such a coefficient of friction promotes the easy migration of toner from the drum
10
and thereby obviates defective images.
In the illustrative embodiment, the cleaning unit has been shown and described as using the cleaning blade
24
together with the brush roller
24
. However, the present invention is, of course, applicable to a cleaning unit including only a brush roller or a brush roller and a cleaning member other than a cleaning blade.
The illustrative embodiment has concentrated on a monochromatic image forming apparatus including the photoconductive drum
10
.
FIG. 13
shows a color image forming apparatus to which the present invention is also applicable. As shown, the color image forming apparatus includes a photoconductive drum
50
, a charger
51
, a developing unit
52
, and an intermediate image transfer body
53
. The developing unit
52
includes developing devices
52
B (black),
52
C (cyan),
52
M (magenta) and
52
Y (yellow).
In operation, while the drum
50
is in rotation, the charger
51
uniformly charges the surface of the drum
50
. An optical writing unit, not shown, scans the charged surface of the drum
50
with a light beam L to thereby form a latent image on the drum
50
. Subsequently, one of the developing devices
52
B through
52
Y develops the latent image with toner of particular color and thereby produces a corresponding toner image. The toner image is transferred from the drum
50
to the intermediate image transfer body
53
.
Likewise, the other developing devices each form a particular toner image on the drum
50
. Such toner images are sequentially transferred to the intermediate image transfer body
53
one above the other, completing a composite color image on the body
53
. The color image is collectively transferred from the intermediate image transfer body
53
to a paper sheet
54
. Cleaning units
55
and
56
respectively clean the drum
50
and intermediate image transfer body
53
after the image transfer. The cleaning units
55
and
56
include brush rollers
57
and
58
, respectively.
In summary, it will be seen that the present invention provides an electrostatic image forming apparatus having various unprecedented advantages, as enumerated below.
(1) Straight bristles are implanted in a brush roller. The straight bristles reduce the wear of an image carrier and thereby extend the life of the image carrier, compared to loop-like bristles. In addition, the straight bristles can be implanted more densely than loop-like bristles in order to make brush marks on the image carrier inconspicuous, preventing image quality from being lowered.
(2) The bristles are implanted with a density ρ of 30/πDs or above in order to render the brush marks inconspicuous. Further, the individual bristle presses the surface of the image carrier with a mean pressure of 10×10
−5
(N) or above. The bristles can therefore be increased in rigidity in order to remove reactive gases, talc, clay, paper fibers and other contaminants from the image carrier. The bristles therefore achieve an enhanced cleaning ability.
(3) When the bristle density ρ is 80/πDs or above, the distance between nearby brush marks is not recognizable by eye, making the brush marks inconspicuous. This further enhances image quality.
(4) The individual bristle has a diameter of 0.5 mm or above. This readily increases a mean pressure with which the individual bristle presses the surface of the image carrier to 10×10
−5
(N) or above, thereby enhancing the cleaning ability.
(5) Because the bristle density is lower than a preselected value, the brush roller does not excessively increase a load to act on the image carrier or cause it to vary. In addition, the brush roller itself can smoothly rotate.
(6) When bristle density is reduced below the upper limit, the above advantage (5) is further enhanced.
(7) The surface of the image carrier is provided with a coefficient of friction of 0.3 or below in order to reduce wear and extend the life. Further, such a surface coefficient promotes the easy migration of toner from the image carrier, obviating defective images.
(8) The brush roller applies a lubricant to the image carrier, so that the above coefficient of friction can be easily implemented.
(9) The image carrier may be implemented by either one of a photoconductive element and an intermediate image transfer body, as desired.
(10) A cleaning unit achieves a higher cleaning ability for removing the contaminants without reducing the life of the image carrier. This successfully insures desirable image quality.
(11) The cleaning unit includes a cleaning blade in addition to the brush roller for further enhancing the cleaning ability.
Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.
Claims
- 1. In an electrophotographic image forming apparatus including a brush roller for cleaning a surface of an image carrier, said brush roller comprises straight bristles implanted in a density ρ (1/mm2) satisfying a relation:ρ≧30/πDs where Ds denotes a diameter (mm) of a brush support included in said brush roller, andsaid bristles each exert a mean pressure of 10×10−5 (N) on a surface of said image carrier.
- 2. The apparatus as claimed in claim 1, wherein the density ρ satisfies a relation:ρ≧80/πDs.
- 3. The apparatus as claimed in claim 2, wherein said bristles each have a diameter Df (mm) satisfying a relation:Df≧0.05.
- 4. The apparatus as claimed in claim 3, wherein the density ρ satisfies a relation:ρ≦0.5/(Dt+Df)2 where Dt denotes a mean particles size of toner.
- 5. The apparatus as claimed in claim 4, wherein the density ρ satisfies a relation:ρ≦0.3/(Dt+Df)2.
- 6. The apparatus as claimed in claim 5, wherein a surface of said image carrier has a coefficient of friction of 0.3 or below.
- 7. The apparatus as claimed in claim 6, wherein said brush roller applies a lubricant to the surface of said image carrier to thereby provide said surface with the coefficient of friction of 0.3 or below.
- 8. The apparatus as claimed in claim 7, wherein said image carrier comprises a photoconductive element, said apparatus charging a surface of said photoconductive element, forming a latent image on said surface, developing said latent image with toner, and transferring a resulting toner image.
- 9. The apparatus as claimed in claim 8, wherein said image carrier comprises an intermediate image transfer body, said apparatus sequentially transferring monocolor toner images from said photoconductive element to said intermediate image transfer body one above the other and transferring a resulting color image to a recording medium.
- 10. The apparatus as claimed in claim 1, wherein said bristles each have a diameter Df (mm) satisfying a relation:Df≧0.05.
- 11. The apparatus as claimed in claim 10, wherein the density ρ satisfies a relation:ρ≦0.5/(Dt+Df)2 where Dt denotes a mean particles size of toner.
- 12. The apparatus as claimed in claim 11, wherein the density ρ satisfies a relation:ρ≦0.3/(Dt+Df)2.
- 13. The apparatus as claimed in claim 12, wherein a surface of said image carrier has a coefficient of friction of 0.3 or below.
- 14. The apparatus as claimed in claim 13, wherein said brush roller applies a lubricant to the surface of said image carrier to thereby provide said surface with the coefficient of friction of 0.3 or below.
- 15. The apparatus as claimed in claim 14, wherein said image carrier comprises a photoconductive element, said apparatus charging a surface of said photoconductive element, forming a latent image on said surface, developing said latent image with toner, and transferring a resulting toner image.
- 16. The apparatus as claimed in claim 15, wherein said image carrier comprises an intermediate image transfer body, said apparatus sequentially transferring monocolor toner images from said photoconductive element to said intermediate image transfer body one above the other and transferring a resulting color image to a recording medium.
- 17. The apparatus as claimed in claim 1, wherein the density ρ satisfies a relation:ρ≦0.5/(Dt+Df)2 where Dt denotes a mean particle size of toner and Df (mm) is a diameter of each said bristles.
- 18. The apparatus as claimed in claim 17, wherein the density ρ satisfies a relation:ρ≦0.3/(Dt+Df)2.
- 19. The apparatus as claimed in claim 18, wherein a surface of said image carrier has a coefficient of friction of 0.3 or below.
- 20. The apparatus as claimed in claim 19, wherein said brush roller applies a lubricant to the surface of said image carrier to thereby provide said surface with the coefficient of friction of 0.3 or below.
- 21. The apparatus as claimed in claim 20, wherein said image carrier comprises a photoconductive element, said apparatus charging a surface of said photoconductive element, forming a latent image on said surface, developing said latent image with toner, and transferring a resulting toner image.
- 22. The apparatus as claimed in claim 21, wherein said image carrier comprises an intermediate image transfer body, said apparatus sequentially transferring monocolor toner images from said photoconductive element to said intermediate image transfer body one above the other and transferring a resulting color image to a recording medium.
- 23. The apparatus as claimed in claim 1, wherein a surface of said image carrier has a coefficient of friction of 0.3 or below.
- 24. The apparatus as claimed in claim 23, wherein said brush roller applies a lubricant to the surface of said image carrier to thereby provide said surface with the coefficient of friction of 0.3 or below.
- 25. The apparatus as claimed in claim 24, wherein said image carrier comprises a photoconductive element, said apparatus charging a surface of said photoconductive element, forming a latent image on said surface, developing said latent image with toner, and transferring a resulting toner image.
- 26. The apparatus as claimed in claim 25, wherein said image carrier comprises an intermediate image transfer body, said apparatus sequentially transferring monocolor toner images from said photoconductive element to said intermediate image transfer body one above the other and transferring a resulting color image to a recording medium.
- 27. The apparatus as claimed in claim 1, wherein said image carrier comprises a photoconductive element, said apparatus charging a surface of said photoconductive element, forming a latent image on said surface, developing said latent image with toner, and transferring a resulting toner image.
- 28. The apparatus as claimed in claim 27, wherein said image carrier comprises an intermediate image transfer body, said apparatus sequentially transferring monocolor toner images from said photoconductive element to said intermediate image transfer body one above the other and transferring a resulting color image to a recording medium.
- 29. The apparatus as claimed in claim 1, wherein said image carrier comprises an intermediate image transfer body, said apparatus sequentially transferring monocolor toner images from said photoconductive element to said intermediate image transfer body one above the other and transferring a resulting color image to a recording medium.
- 30. In a cleaning unit for an electrophotographic image forming apparatus that includes a brush roller for cleaning a surface of an image carrier, said brush roller comprises straight bristles implanted in a density ρ (1/mm2) satisfying a relation:ρ≧30/πDs where Ds denotes a diameter (mm) of a brush support included in said brush roller, andsaid bristles each exert a mean pressure of 10×10−5 (N) on a surface of said image carrier.
- 31. The cleaning unit as claimed in claim 30, wherein a cleaning blade is used in combination with said brush roller as a cleaning member.
- 32. In a brush roller included in a cleaning unit for an electrophotographic image forming apparatus for cleaning a surface of an image carrier, said brush roller comprises straight bristles implanted in a density ρ (1/mm2) satisfying a relation:ρ≧30/πDs where Ds denotes a diameter (mm) of a brush support included in said brush roller, andsaid bristles each exert a mean pressure of 10×10−5 (N) on a surface of said image carrier.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2000-073268 |
Mar 2000 |
JP |
|
2001-033803 |
Feb 2001 |
JP |
|
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
5998008 |
Shimamura et al. |
Dec 1999 |
A |
Foreign Referenced Citations (2)
Number |
Date |
Country |
6-337598 |
Dec 1994 |
JP |
9-288441 |
Nov 1997 |
JP |