BACKGROUND OF THE INVENTION
1. Field of the invention
[0001] The present invention relates a magnetic roller for image developing means in electrophotographic
system, and more particularly to a magnetic roller of image developing means that
can largely reduce the cost of the magnetic rollers body, makes magnetic pole angle
more accurate, and enhances the magnetic strength.
2. Description of die prior art
[0002] Accordingly, the image module of a laser printer, as shown in FIG. 1, includes: a
photo-sensitive drum 11, which is a drum used to generate an electrostatic latent
image on its surface; a corona bar 12, which is provided in one side of the surface
of said photo-sensitive drum and used to distribute induction static electricity on
the surface of said photo-sensitive drum; an exposure means 13, which is provided
in another end away from said photo-sensitive drum and charging roller 12, and can
receive the signal from an image reader to emit laser for exposure, so that an exposure
area and non-exposure area similar to the image in the image reader are formed on
the surface of photo-sensitive drum; a toner cartridge device 14, which is provided
in another side of photo-sensitive drum in the backward position after exposure means
is operated, used to provide storage of toner; a magnetic roller 15 with its surface
covered by a developing sleeve, which is provided in front end of a toner cartridge
outlet close to the photo-sensitive drum. The toners inside the cartridge device 14
are attracted by magnetic force of the magnetic roller 15 and distributed on the outer
surface of developing sleeve 16, after the developing sleeve 16 keeps rotating and
has induction with the exposure area having static electricity on the surface of photo-sensitive
drum 11, toners are then attracted to the surface of photo-sensitive drum, and then,
through the photo-sensitive drum 11, toners are brought to printing area. Afterwards,
the toner transferring device 17 is used to transfer toners to adhere onto the surface
of papers to form an image identical to the character or figure to the printed out.
Then the image is obtained.
[0003] In the image developing means of printer described above, the quality of the magnetic
roller has great impact on printing quality. In the conventional magnetic roller,
as shown in FIG. 2, there is provided a nonconductive roller body 21, which is made
of rubber, plastic or other artificial resins. A plurality of S magnetic poles 22a,
22b, etc., and N magnetic poles 23a, 23b, etc. are formed on the roller body 21 closed
to the outer circular ring separately, usually in adjacent positions. Therefore, their
magnetic poles can be arranged as even poles, such as dual poles, quad poles, six
poles, or eight poles, etc. A conventional approach is to insert the magnetic bars
with S magnetic poles and N magnetic poles in outer side into the roller body (disclosed
in American Patent No. 4,517,719; 6,654,582). Another approach is to mix magnetic
materials with rubber, plastic or other artificial resins to form a cylinder as a
whole, using an exciter to excite the roller body in pre-determined outer parts of
the roller body during forming the magnetic roller, so that a plurality of S magnetic
poles and N magnetic poles are formed on the surface of the roller body opposite to
the exciter (as shown in American Patent No. 5,129,358).
[0004] However, whether the S magnetic pole and N magnetic pole are formed by inserting
the magnetic bars into the roller body or formed with the roller body as a whole,
the entire cost of the magnetic roller is very high. This is because the materials
of the roller body are very expensive and the technology that makes magnetic angle,
magnetic strength, and magnetism equalization fit the need of printers is sophisticated.
Moreover, if S magnetic poles and N magnetic poles are formed by inserting the magnetic
bars into furrows formed on the surface of the roller body, this not only brings many
problems with regards to density configuration, but also causes inconvenience on assembling.
The problems regarding magnetic angle, magnetic strength, and magnetism equalization
in each magnetic bar still need to be solved.
[0005] If S magnetic poles and N magnetic poles are formed on the adjacent edge of the whole
roller body, some magnetic dipoles (small magnets) can not be exactly allocated in
the position coherent to the magnetic flux, therefore, there are still some irregularly
arranged magnetic dipoles (small magnets) 24 (as shown in FIG. 3) would be distributed
aside the magnetic poles (as shown in area A, B, C, D of FIG 3) and even central part
of the roller body, causing the magnetic flux of S magnetic poles and N magnetic poles
to be interfered, which affects the magnetic angle and magnetism equalization of magnetic
poles and decreases magnetic strength, having impact on magnetic force configuration
of the whole magnetic roller, making magnetization of the roller's magnetic materials
incomplete. The satisfactory printing quality cannot be achieved because toners cannot
be attracted on the accurate positions.
[0006] Accordingly, the present invention has been made for solving the above-mentioned
problems occurred in the prior art.
SUMMARY OF THE INVENTION
[0007] Accordingly, the object of present invention is to provide a magnetic roller for
image developing means in electrophotographic system. The magnetic roller for image
developing means of printer according to the present invention is formed as an integral
body. The magnetic roller is a non-cylinder body, and only S magnetic poles and N
magnetic poles are formed in outward protruding status, so that the area between S
magnetic poles and N magnetic poles can be largely curtailed and the cost of the magnetic
roller can be largely reduced.
[0008] In the magnetic roller for image developing means in eletrophotographic system according
to the present invention, since magnetic poles are formed in outward protruding status,
and the area between S magnetic poles and N magnetic poles is largely curtailed, as
a result, magnetic flux of magnetic poles can be more concentrated during magnetic
excitation. In magnetic roller the magnetic dipoles (shown as small magnets) those
are arranged irregularly and thus (cause) the interference of magnetic poles would
be decreased. Therefore, magnetic flux of S magnetic poles and N magnetic poles can
be increased, the effect of attracting toner can be enhanced, and printing quality
can be further enhanced. This is the another object of the present invention.
[0009] The magnetic roller for image developing means of printer according to the present
invention, with the position of S magnetic poles and N magnetic poles are fixed, the
magnetic angle is then fixed, so that the accuracy of magnetic angle can be enhanced.
This is further object of the present invention.
[0010] The above objects and other advantages of the present invention will become more
apparent by describing in detail the preferred embodiment of the present invention
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
FIG. 1 is a drawing showing the configuration of a conventional magnetic roller for
image developing means in electrophotographic system.
FIG. 2 is a perspective view of a conventional magnetic roller for image developing
means in electrophotographic system.
FIG. 3 is a plane view of a conventional magnetic roller showing the magnetic flux
between magnetized magnetic poles of the magnetic roller and magnetic poles ordering
means.
FIG 4 is a drawing showing magnetic excitation to form the magnetic roller according
to the present invention.
FIG. 5 is a plane view of the magnetic roller according to the present invention.
FIG. 6 is a perspective view of the magnetic roller of printer image developer of
in the present invention.
FIG. 7 is a plane view of the magnetic roller in the present invention having a sleeve
on it.
FIG. 8 is a drawing illustrating how the magnetic roller of the present invention
saves the cost of materials.
FIG. 9 is a drawing showing another embodiment of the magnetic roller in the present
invention.
FIG. 10 is a perspective view of another embodiment of the magnetic roller in the
present invention shown in FIG. 9.
FIGS. 11 to 14 are drawings illustrating other embodiments of the magnetic roller
of present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] As shown in FIG. 4, 5, and 6, the magnetic roller for image developing means of the
present invention in electophotographic system includes a cylindrical roller body
3, which is made of rubber, plastic or other artificial resins mixed with magnetic
materials as a unity.
[0013] A plurality of S magnetic poles 41, 42 and N magnetic poles 51, 52 on the outer surface
of roller body 3 are protruded outward from the center of the roller body 3, so that
S magnetic poles 41, 42 and N magnetic poles 51, 52 form strip shape in the direction
of the axis of roller body; and an axis of roller 6, which is passed through the center
of the roller body.
[0014] Wherein, said plurality of S magnetic poles 41, 42 and N magnetic poles 51, 52 are
formed after roller body 3 is manufactured by injection, compression, or extrusion
process and before the process of curing, using a plurality of exciting devices 61,
62, 63, 64 to excite the protruding part of the magnetic roller respectively, so that
S magnetic poles and N magnetic poles are formed on the protruding part respectively.
The roller body formed by this way is a magnetic roller with outward protruding S
magnetic poles 41, 42 and N magnetic poles 51, 52. Such a magnetic roller is a non-circular
body in a unity, and the areas 71, 72, 73, 74 between S magnetic poles and N magnetic
poles are hollow in inner indentation status.
[0015] As the above-mentioned magnetic roller is implemented in image developing means (i.e.
printer), as shown in FIG. 7, the roller body is covered by a developing sleeve 8,
since the areas 71, 72, 73, 74 between S magnetic poles 41, 42 and N magnetic poles
51, 52 are in indentation status, the entire expensive materials of the magnetic roller
can be largely reduced and the cost of the magnetic roller can be largely reduced
(as shown in FIG. 8). Furthermore, since these areas are non-magnetic in concave area,
magnetic flux between magnetic poles will not be interfered, thus the magnetic strength
of magnetic poles in the magnetic roller can be largely increased. Furthermore, since
the position of magnetic poles is fixed, the effect that makes magnetic angle more
accurate can be achieved.
[0016] In another embodiment of the present invention, as shown in FIG. 9 and 10, when S
magnetic poles 41, 42 and N magnetic poles 51, 52 are in outward protruding status,
the magnetic flux is oriented along with the indentation arc between two adjacent
magnetic poles. Therefore, when using the exciting devices to magnetize the magnetic
poles in the protruding part of the roller body, the S magnetic poles and N magnetic
poles are magnetized in fixed angles. These angles between S magnetic poles and N
magnetic poles can be equalized or not. Since the magnetic flux between two adjacent
magnetic poles are coherent with the inner indentation arc of the magnetic roller,
irregular arrangement of magnetic dipoles (small magnets) can be greatly decreased
and magnetic strength of the magnetic roller can be largely enhanced.
[0017] In addition, since the position of magnetic poles is fixed, magnetic angle of the
magnetic roller can be more accurate. In the magnetic roller of the embodiment, the
more magnetic flux is oriented into the central part of the roller, the more effective
the magnetization of the material is. Since the convex parts are extruded outward
in fixed angles, thus the magnetic flux can be more concentrated, the magnetic strength
are enhanced, and the materials saved have been increased than the prior embodiment,
thus promoting large cost down.
[0018] In the magnetic roller of the present invention, as S magnetic poles and N magnetic
poles can be paired or not paired (as shown in FIG 11), the magnetic poles can be
even poles, such as dual poles, quad poles, six poles, etc. or in odd numbers, while
the surface of roller body 3 and magnetic poles 41, 42, 51, 52 are in arc shape (with
same or different curvatures) or not in arc shape.
[0019] For example, as shown in FIG. 12, for different necessities, the open angles α1,
α2, ...between two adjacent magnetic poles can be different. Therefore the concave
areas 71, 72, 73, 74 between two adjacent magnetic poles can be formed into different
areas. Moreover, as shown in FIG. 13, for processing convenience and to reduce production
cost, each of the surfaces 710, 720, 730, 740 of roller body 3 between two adjacent
magnetic poles, even each of the surfaces 410, 420, 510, 520 of magnetic poles 41,
42, 51, 52 can be formed into a plane.
[0020] In addition, for special uses and other considerations, for example, in order to
obtain different flux densities, as shown in FIG. 14, the protruded heights of the
magnetic poles 41, 42... of the magnetic roller of present invention can be different.
[0021] In conclusion from above, according to the magnetic roller for image developing means
of the present invention in a electrophotographic system, by making the magnetic roller
formed as a non-cylinder body in a unity and only S magnetic poles and N magnetic
poles are in outward protruding status, so that the area between two magnetic poles
is in inner indentation status, which effectively makes magnetic angle of the magnetic
roller more accurate, enhances magnetic strength, and largely reduces the cost of
magnetic roller. Also, the present invention has not yet opened to public, it is then
complied with the conditions of allowable patents.
[0022] Although the above-mentioned embodiments of the present invention has been described
for illustrative purposes, those skilled in the art will appreciate that various modifications,
additions and substitutions are possible, without departing from the scope and spirit
of the invention as disclosed in the accompanying claims.
1. A magnetic roller for image developing means in electrophotographic system, comprising:
a roller body, which is made of rubber, plastic, or other artificial resin mixed with
magnetic materials as a unity; and an axis of roller which passes through the center
of the roller body; characterized in that: a plurality of S magnetic poles and N magnetic poles are protruded outward to form
on outer ring of the roller body, and the areas between two adjacent magnetic poles
are in inner indentation status.
2. The magnetic roller for image developing means as claimed in claim 1, wherein the
base of the two adjacent magnetic poles in said roller body is connected with the
convex arc surface.
3. The magnetic roller for image developing means as claimed in claim 1, wherein the
base of the two adjacent magnetic poles in said roller body is connected with the
concave are surface.
4. The magnetic roller for image developing means as claimed in claim 1, wherein the
surface between two adjacent magnetic poles in said roller body is formed into a plain
surface.
5. The magnetic roller for image developing means as claimed in claim 1, wherein the
surface of magnetic pole is an arc with the same curvature.
6. The magnetic roller for image developing as claimed in claim 1, wherein the surface
of magnetic pole is an arc with the different curvature.
7. The magnetic roller for image developing as claimed in claim 1, wherein the surface
of magnetic poles is plain.
8. The magnetic roller for image developing as claimed in claim 1, wherein the protruding
height of the magnetic pole is similar.
9. The magnetic roller for image developing as claimed in claim 1, wherein the protruding
height of the magnetic poles are different.
10. The magnetic roller for image developing means as claimed in claim 2, wherein the
surface of magnetic pole is an arc with the same curvature.
11. The magnetic roller for image developing means as claimed in claim 3, wherein the
surface of magnetic pole is an arc with the same curvature.