Electrophotography – Image formation – Development
Reexamination Certificate
1999-08-24
2001-01-16
Moses, Richard (Department: 2852)
Electrophotography
Image formation
Development
C118S261000
Reexamination Certificate
active
06175708
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a blade member, a blade member manufacturing method, a developing unit having a blade member, and an image forming apparatus having a developing unit and, more particularly, to a member or blade member used in an image forming apparatus such as a copying machine, a laser beam printer, or the like to adjust the amount of toner.
A copying machine or laser beam printer has a blade member incorporated in its developing unit to serve as a toner amount adjusting member. When the toner of the developing unit is attached to a latent image photosensitized on a photosensitive drum to develop the image, the blade member adjusts the amount of toner of the developing unit. This will be described with reference to the accompanying drawings.
FIG. 1
shows a sectional view of the main part of a developing unit manufactured by the present applicant.
Referring to
FIG. 1
, reference numeral
1
denotes the case of a developing unit;
2
, a photosensitive drum;
4
, a developing sleeve;
6
, a magnet mounted in the developing sleeve
4
; and
8
and
10
, toner agitating screws, respectively.
Reference numeral
12
denotes a blade member according to the present invention. The blade member
12
is fixed to blade holding members
16
and
18
with a blade attaching member
14
.
FIG. 2
shows a partial enlarged view of the structure of a position near the distal end of the blade member
12
and the developing sleeve
4
. As shown in
FIG. 2
, the distal end of the blade member
12
is constituted by two metal members. A first metal member
12
A is made of a nonmagnetic material. A distance between a distal end position
12
A-a of the first metal member
12
A and the outer surface of the developing sleeve
4
is adjusted to adjust the toner amount. A second metal member
12
B is made of a magnetic material, and constitutes a magnetic circuit together with a magnet in the developing sleeve
4
to attract the toner. Accordingly, the blade member
12
having the above arrangement is constituted by the two metal members, one of which is composed of the magnetic member.
SUMMARY OF THE INVENTION
The blade member
12
is formed by joining the member
12
A as the nonmagnetic member to the member
12
B as the magnetic member. The blade member
12
is to collide against the toner being agitated in the developing unit to receive an impact from it. Accordingly, the two metal members must be joined with a joining force that can stand the collision and impact.
For example, when an adhering is employed, the toner enters the mating portion between the nonmagnetic member
12
A and magnetic member
12
B to cause peeling of the bonded portion.
Welding is available as a method of increasing the weld strength of the mating portion.
Various methods are available for welding the two metal members. To assure the weld strength, methods such as laser welding and arc welding are available.
The first metal member as the nonmagnetic member must have a high mechanical strength as it collides against and comes into contact with the toner being agitated. As the material for the first metal member, austenite-based stainless (SUS) steel which is not attracted to a magnet is employed. This stainless steel, however, may be influenced by heat generated by welding.
More specifically, when stainless steel is melted (at about 1,500° C. which the melting temperature of a steel plate), carbon steel as the main component transforms from the austenite phase to pearlite phase. Ferrite is produced at the pearlite portion and magnetized.
When the nonmagnetic member as the first metal member and the magnetic member as the second metal member are welded to each other by laser welding or arc welding requiring a high melting temperature, since the structure that has changed to pearlite has been magnetized, the magnetized portion of the welded portion adversely affects the function as the blade member.
More specifically, when the blade member is attached to the developing unit and used to adjust the toner amount, since the structure that has changed to pearlite is magnetized, the toner attaches to this pearlite portion upon using the blade member. This forms a white streaking line at a portion to be developed, which is a defect in the developing performance.
In particular, in a color image developing system, an influence on a halftone image increases.
Furthermore, in the blade member which adjusts the toner amount of the image forming apparatus, the precision of its straightness is important. A blade member obtained by a welding method, the heat energy of which is difficult to adjust, has a problem in guaranteeing the straightness.
In order to solve the above problems, according to the present invention, there is provided a blade member for adjusting an amount of image forming toner for an image forming apparatus, wherein members constituting the blade member are a nonmagnetic member and a magnetic member.
There is also provided a blade member characterized in that the nonmagnetic and magnetic members are welded to each other intermittently by laser irradiation.
There is also provided a blade member wherein, when welding magnetic and nonmagnetic members to each other by laser irradiation of a laser beam, the laser beam is pulsed, and the laser beam to irradiate a welding portion is an in-focused state or a defocused state.
According to an aspect of the present invention, there is also provided a blade member for an image forming apparatus, in which when welding a nonmagnetic material and a magnetic material to each other, a heat energy for a welding portion can be adjusted by controlling the pulse wave of a YAG laser, so that a weld penetration depth and welding area of the nonmagnetic and magnetic materials can be adjusted.
In particular, magnetization of the metal structure of the nonmagnetic material can be prevented by controlling the YAG laser by means of pulsed-laser irradiation time.
Furthermore, there is provided a blade member in which a change in magnetic flux density of a portion of the magnetic member irradiated with a laser beam is set to be 10 G or less, so the problem of white streaking line formed on the image is solved.
Furthermore, according to the present invention, there is provided a method of manufacturing a blade member composed of a first metal member having a toner amount adjusting portion and a second metal member to be joined to the first metal member, characterized in that the first and second metal members are joined to each other by welding with intermittent irradiation of a laser beam in a longitudinal direction, and an irradiation energy is adjusted so as not to change a structure of the first metal member by the laser beam, thereby solving the above problems.
According to an aspect of the present invention, there is provided a method of manufacturing a blade member wherein the first metal member is austenite-based stainless steel.
In order to solve the problems of the developing unit described above, there is provided a developing unit for an image forming apparatus, characterized in that a blade member obtained by welding a nonmagnetic member and a magnetic member to each other by laser irradiation is used to adjust a toner amount.
There is also provided an image forming apparatus characterized by comprising a developing unit in which a blade member obtained by welding a nonmagnetic member and a magnetic member to each other by laser irradiation is used to adjust a toner amount.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
REFERENCES:
patent: 4406536 (1983-09-01), Suzuki et al.
patent: 4583490 (1986-04-01), Kan et al.
patent: 4592987 (1986-06-01), Mitsuhashi et al.
patent: 4615608 (1986-10-01), Mizutani
Iwai Koji
Ohashi Tsuneo
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Moses Richard
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