U.S. patent number 3,916,830 [Application Number 05/497,523] was granted by the patent office on 1975-11-04 for magnetic brush developer.
This patent grant is currently assigned to Konishiroku Photo Industry Co. Ltd.. Invention is credited to Haruo Fujii, Nin-ichi Kamogawa, Motoki Kojima.
United States Patent |
3,916,830 |
Kojima , et al. |
November 4, 1975 |
Magnetic brush developer
Abstract
An improved scraping plate, in combination with a magnetic brush
developer, is disclosed, which has an upwardly extending edge
contacting the magnetic brush for removal of residual developer
materials and a plurality of guide elements for moving the scraped
residual developer materials axially whereby the developer
materials are more uniformally mixed.
Inventors: |
Kojima; Motoki (Hino,
JA), Kamogawa; Nin-ichi (Tokyo, JA), Fujii;
Haruo (Mitaka, JA) |
Assignee: |
Konishiroku Photo Industry Co.
Ltd. (Tokyo, JA)
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Family
ID: |
12633824 |
Appl.
No.: |
05/497,523 |
Filed: |
August 15, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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256801 |
May 25, 1972 |
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Foreign Application Priority Data
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May 26, 1971 [JA] |
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46-42359 |
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Current U.S.
Class: |
399/254; 118/203;
399/273 |
Current CPC
Class: |
G03G
15/09 (20130101) |
Current International
Class: |
G03G
15/09 (20060101); G03G 013/08 () |
Field of
Search: |
;118/637,203,104
;15/256.5,256.51 ;117/17.5 ;355/3DD |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Kaplan; Morris
Attorney, Agent or Firm: Bierman & Bierman
Parent Case Text
This application is a continuation of Ser. No. 256801, filed May
25, 1972, now abandoned, which claims the priority of Japanese
application 42,359/1971 filed May 26, 1971.
Claims
What we claim is:
1. In an apparatus for developing an electrostatic latent image,
comprising a magnetic brush formed on a cylindrical member and
disposed within a trough, a particulate developer comprising a
magnetic carrier and a toner disposed in said trough, said
cylindrical member partially immersed in said developer, means for
rotating said cylinder, means for passing a latent image carrier in
proximity to and in contact with the brush thereby developing said
image, and scraping means for removing residual developer from said
cylindrical member for return to said trough after development,
said scraping means being located downstream of the zone of image
development and extending along the longitudinal extent of said
cylinder, the improvement which comprises said scraping means
comprising a scraping plate extending upwardly and along said
longitudinal extent and having a linear front edge in close
proximity to said cylinder thereby adapted to remove the residual
developer, said scraping means further comprising a plurality of
transversely directed and oppositely inclined guide elements
extending from the rear edge of said scraping plate for moving at
least a part of the scraped residual developer axially of said
cylinder whereby the magnetic carrier and toner particles removed
from said cylinder are more uniformly mixed.
2. An apparatus according to claiml 1, wherein said guide elements
are rearwardly extending from the rear edge of said scraping
plate.
3. An apparatus according to claim 1, wherein said guide elements
are placed under said scraping plate and rearwardly extending.
4. An apparatus according to claim 1, wherein said guide elements
comprising two groups of the guide elements, a first group of the
guide elements being spaced along said longitudinal extent of said
cylinder and extending from the rear edge of said scraping plate, a
second group of the guide elements being individually spaced under
and between two adjacent guide elements of said first group and
rearwardly extending from the rear edge of said scraping plate.
5. An apparatus according to cliam 1, wherein said guide elements
comprise a plurality of spaced panels rearwardly extending from the
rear edge of said scraping plate and a panel element extending from
each lateral edge of each said spaced panel and directed downwardly
and outwardly with respect to said spaced panels and said scraping
plate.
6. An apparatus for developing an electrostatic latent image
comprising a rotatable magnetic brush formed on a cylindrical
member and disposed within a trough, a particulate developer
comprising a magnetic carrier and a toner disposed in said trough,
said cylindrical member partially immersed in said developer means
for passing a latent image carrier in proximity to and in contact
with the magnetic brush thereby developing said image, a fixed
scraping plate located downstream of the zone of image development
extending along the longitudinal extent of said cylinder and having
an upwardly extending front edge in close proximity to said
cylinder thereby removing residual developer from the cylinder for
return to said trough, said plate including a plurality of spaced
panels extending rearwardly from the rear edge of said plate, and a
panel element extending from each lateral edge of each said spaced
panel and directed downwardly and outwardly with respect to said
spaced panels and said scraper plate, whereby developer material
removed from said cylinder is moved axially of said cylinder by
each of said panel panel elements to more uniformly mix the carrier
and toner particles.
7. An apparatus as in claim 6, wherein said spaced panels each
extend upwardly with respect to said plate.
Description
This invention relates to a developing apparatus with a magnetic
brush for use in visualization of an electrostatic latent
image.
An electrostatic latent image can be formed in various methods.
Commonly known is a method wherein photo image corresponding to an
original is projected on a uniformly charged photo-conductive
insulating layer and the charge on exposed portion is dissipated to
form an electrostatic latent image. An alternative is the method
wherein needle end discharge is effected imageweise on the
insulating layer to form an electrostatic photographic latent
image.
In order to visualize thus formed electrostatic latent image, a
developer is used which comprises, for example, a magnetic carrier
and a toner. In the practical operation, the developer is adhered
to the peripheral surfaces of a cylindrical magnet assembly
comprising a plurality of magnets arranged at the peripheral
surface thereof with alternate polarity whereby the developer is
kept in brush-shaped configuration. The developer kept in
brush-shaped configuration is moved along the peripheral surfaces
of the cylindrical magnet assembly and brought into contact with
the electrostatic latent image so that the toner contained in the
developer can be selectively adhered to the latent image thereby
developing and visualizing the latter.
The above-mentioned developing method is generally referred to as
"magnetic developing process," for which a number of apparatus have
been proposed. In one proposed embodiment, there is employed an
apparatus wherein a developer is adhered directly on the peripheral
surfaces of the cylindrical magnet assembly, which is rotated in
turn so that the developer can be conveyed and brought into contact
with the electrostatic latent image. In another proposed
embodiment, there is employed an apparatus wherein a developer is
adhered to the peripheral surface of a freely rotate cylindrical
(non-magnetic) supporting member, which has magnets located inside
thereof, and the developer is adhered to the peripheral surface of
said cylindrical member, which is rotated in turn so that the
developer can be conveyed and brought into contact with the
electrostatic latent image. In still another embodiment, there is
employed an apparatus in which a cylindrical (non-magnetic)
supporting member has magnets located at the inner peripheral
surface thereof, each of said magnets having a magnetic pole
alternately different in polarity along the inner peripheral
surface of said supporting member. In practical operation of this
apparatus, a developer is conveyed in the direction opposite to the
direction of rotation of the magnets and brought into contact with
an electrostatic latent image by rotating the cylindrical magnets
while the developer is self-rotated.
In these magnetic brush developing apparatus, there is employed a
flat scraping plate which scrapes off the developer from the
peripheral surface of a cylindrical magnet assembly or a
cylindrical supporting member after the developer has passed a
developing position at which it is brought into contact with an
electrostatic latent image. This scraping operation is effected in
order to keep the magnetic carrier-to-toner ratio constant
throughout the operation so that the developed image having an even
and uniform density can be obtained at any time by the
development.
The magnetic carrier-to-toner ratio of a developer will vary in
response to the progress of development because the toner is
consumed. In the conventional process, therefore, the developer
having a varied magnetic carrier-to-toner ratio must be scraped off
wholly or partly from the peripheral surface of the cylindrical
magnet assembly comprising a plurality of magnets or the
cylindrical supporting member having magnets located therein and
then returned to a container accommodating a fresh developer, so as
to adjust again the magnetic carrier-to-toner ratio at a constant
level required for development. Thus, the developer conveyed to a
developing position can be kept at a desired level of the magnetic
carrier-to-toner ratio at any time.
However, the prior art flat scraping plate has an inherent
disadvantage such that a large part of the developer will move in
the direction of rotation of the magnetic brush and not in the
axial direction of the latter within the container, because the
plate allows the developer to drop only in the direction of the
peripheral surface of the brush within the container after it has
scraped off the developing formulation from the latter.
So far as the developer moves only in the direction of rotation of
the magnetic brush, the portion having a low toner density is
maintained without being improved if it is present in the
developer. Consequently, the photo image visualized by means of
such developing apparatus will have a streaky shade. Moreover, if
the toner concentration of the developer becomes low, the magnetic
carrier itself may adhere to the developing surface. Also, in the
portion where the toner concentration is too high, the toner may
adhere to the non-image portion of the developing surface to
produce fog.
The present invention has for its object to eliminate the
above-mentioned disadvantage in the developing apparatus with a
magnetic brush and provide an apparatus for developing an
electrostatic latent image with a magnetic brush whereby toner
concentration can be kept uniformly at any time so as to obtain a
uniform developing effect.
It has been found that such apparatus for developing an
electrostatic latent image with a magnetic brush can be obtained by
providing close to the supporting surface of the brush a scraping
plate which scrapes off from the peripheral surface of the brush a
developer which has pressed through a developing position and
displaces the thus scraped developer in the axial direction of
rotation of the brush. It should be understood that the expression
"displacement of the scraped developer in the axial direction of
rotation of the magnetic brush" means that said developer is
allowed to move into any direction non-peripheral to the axis of
rotation of the brush.
For better understanding of the invention, an embodiment thereof
will be described below with reference to the accompanying drawings
in which,
FIG. 1 is a longitudinal sectional view of one embodiment of the
developing apparatus with a magnetic brush according to the
invention,
FIG. 2 is an enlarged perspective view of the developer scraping
plate of the apparatus shown in FIG. 1,
FIG. 3 is an enlarged perspective view of another embodiment of the
developer scraping plate, and
FIG. 4 is a sectional view taken along line A - A' of FIG. 3.
In FIG. 1, reference numerals 1, 2, 3, 4 and 5 denote a magnet
respectively. The magnet 1 is located close to a developing
position and serves to form a developer comprising a toner and an
iron dust carrier into brush-shaped configuration. Reference
numeral 6 denotes a cylindrical supporting member which surrounds
the magnets 1, 2, 3, 4 and 5 and is rotated in the direction as
shown by arrow A. Reference numeral 7 denotes a developing
formulation comprising an iron dust carrier and a toner, which is
supported in the periphery of the cylindrical supporting member 6
and is moved by rotation of the supporting member in the direction
as shown by arrow A. Reference numeral 8 denotes a surface to be
developed movable in the direction as shown by arrow B, 10 a
container accomodating a developer and 11 an edge for putting the
ear of the developing brush in order. Reference numeral 9 denotes a
scraping plate which scrapes off the developer on the cylindrical
supporting member 6 and has a shape as shown in FIG. 2. The
scraping plate 9 is mounted close to the cylindrical supporting
member 6. This plate comprises a base portion 21 which acts to
scrape off the developer from the supporting member, inclined
raised portions 22, 22 which are spaced apart from one another at
the rearward edge of the base portion and inclined wing portions
23, 24 and 23, 24 which are integrally formed on both sides of each
of the raised portions. In FIG. 2, there is shown only two sets
each comprising a raised portion 22 and wing portions 23 and 24.
However, in practice, there are provided a large number of sets
each including a raised portion and two wing portions. When the
developer is scraped off from the cylindrical supporting member 6,
it will slide on the base portion 21 in the direction as shown by
arrow C. In the base portion 21 without raised portion 22, the
developer will drop the rearward edge of the portion 21, whilst in
the base portion 21 provided with a raised portion 22, the
developer will slide along the portion 22 and drop through the wing
portions 23, 24 in the direction as shown by arrow D. Thus, the
developer is moved by the raised portion 22 and the wing portions
23, 24 also in the direction of rotary axis of the cylindrical
supporting member 6. Therefore, even if there is a portion in which
toner concentration is low in a developer, the portion is mixed
with the developer present in other portions by the above-mentioned
agitating effect of the scraping plate 9, thereby eliminating local
difference in concentration and achieving uniform toner
concentration.
FIG. 3 and FIG. 4 show another embodiment of the invention. A
scraping plate 30 has a structure similar to that of the scraping
plate 9 shown in FIG. 1 and FIG. 2 and includes a base portion 31,
projecting parts 32 and inclined wing portions 33, 34. Further, the
wing portions 33, 34 have developer receiving portions 35, 36
secured at their respective forward ends. Below the scraping plate
30 is fixed rigidly an auxiliary plate 41, which has inclined wing
portions 37, 38. The wing portions 33, 34 of the scraping plate 30
and the wing portions 37, 38 of the auxiliary plate 41 are
alternately located as shown in FIG. 3. The wing portions 37, 38
have developer receiving portions 39, 40 at their respective
forward ends. The developer will drop partly between the wing
portion 33 and the wing portion 34 adjacent thereto, and the
remainder will drop between the wing portion 37 and the wing
portion 38 adjacent thereto.
In this apparatus, the movement of the developer is more
complicated than that in the apparatus as shown in FIG. 1, so that
local uneveness in toner concentration can be quickly
eliminated.
When the developer with a magnetic brush according to the present
invention is used, the amount of the developer which is
accommodated in the container may become uneven. However, in the
bottom of the container 10 there is accommodated a developer enough
to fill the space between the container and the cylindrical
supporting member 6, so that there does not occur unevenness in the
length of the ear of the developing brush due to unevenness in the
amount of toner. This ensures, in combination with the fact the
edge 11 is provided to put the ear of the brush in order, that
unevenness in the amount of developer does not exert ill influence
on developing effect.
While the invention has been described with reference to particular
embodiments, it should be obvious that various changes and
modifications are possible to those skilled in the art, so that it
is intended that the invention be solely limited by the appended
claims.
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