Electrophotography – Image formation – Development
Reexamination Certificate
1999-09-13
2001-10-09
Braun, Fred L (Department: 2852)
Electrophotography
Image formation
Development
C399S284000
Reexamination Certificate
active
06301461
ABSTRACT:
THE STATE OF THE ART
The doctor blade is used in a toner cartridge assembly for ensuring a substantially even distribution of toner on a magnetic roller.
It has been observed that during the use of a toner cartridge assembly, the efficiency of the doctor blade decreases, whereby the quality of copying and or printing documents decreases.
This problem is especially important when toner cartridge assembly are reconditioned for use.
It has been proposed to apply on the doctor blade a strip comprising a polyurethane conductive layer and a polyester layer, the said strip having a total thickness of about 30-60 &mgr;m. The polyester layer is glued on the doctor blade.
However, after 2,000-3,000 copies, the efficiency of such a doctor blade decreases, whereby the quality ofthe following copies is poor.
The invention relates to a doctor blade with an improved efficiency, as well as a strip to be glued on a substrate of a doctor blade for improving its efficiency.
BRIEF DESCRIPTION OF THE INVENTION
The invention relates to a doctor bade consisting of at least a substrate provided with an element having a face adapted for working with a magnetic roller of a machine selected from the group consisting of copier, printer and facsimile machine, said element being made at least partly of an elastic material. At least a part of the face adapted for working with a magnetic roller has an electrical surface resistivity of less than 9.9 10
14
&OHgr; per square, advantageously less than 10
13
&OHgr; per square, preferably between 10
7
and 10
12
&OHgr; per square, while at least a part of the element made at least partly of an elastic material has a thickness of at least 100 &mgr;m, for example comprised between 100 &mgr;m and 5 mm.
According to a advantageous embodiment, the doctor blade consists of at least a substrate provided with an element having face adapted for working with a magnetic roller of a machine selected from the group consisting of copier, printer and facsimile machine, said element being made at least partly of an elastic material, wherein at least a part of the element made at least partly of an elastic material has thickness of at least 100 &mgr;m, the said part having a thickness of at least 100 &mgr;m having a face adapted for working with a magnetic roller, the said face having an electrical surface resistivity of less than 9.9 10
14
&OHgr; per square, advantageusly less than 10
13
&OHgr;per square, preferably comprised between 10
7
and 10
12
&OHgr; per square, most preferably between 10
8
and 10
11
&OHgr; per square.
Preferably, at least a part of the element made of at least partly of an elastic material and having a face with an electrical surface resistivity of less than 9.9 10
13
&OHgr; per square has thickness comprised between 100 &mgr;m and 5 mm.
The element has advantageously a thickness comprised between 200 &mgr;m and 3 mm.
According to an advantageous embodiment of the doctor blade, the element comprises at least two layers, namely
a first layer made of elastic material, said layer having a thickness of more than 100 &mgr;m, and
a second layer covering at least partly the said first layer and being adapted for working with a magnetic roller of a copier, printer or facsimile machine, said second layer having a thickness of less than 100 &mgr;m and an electrical surface resistivity of less than 9.9 10
14
&OHgr; per square.
Said second layer has advantageously a thickness of less than 50 &mgr;m, preferably a thickness comprised between 10 and 35 &mgr;m.
The element is advantageously made, at least partly, of elastomer material, such as polyurethane, rubber, silicone, and mixtures thereof.
According to a specific embodiment, the doctor blade comprises a flexible substrate made at least partly of a material selected from the group consisting of polyurethane, silicone, polyester, metallic blade, PVC, polycarbonate, and mictures thereof.
The said element is advantageously glued on the flexible substrate of the doctor blade. Other fixing means of the element on the flexible substrate are possible, such as mechanical fixing means. In case of mechanical fixing means, the element comprises advantageously a substantially rigid support (such as aluminum plate), the longitudinal edges of which slides into rails of the substrate.
The face adapted for working with a magnetic roller and having an electrical surface resistivity of less than 9.9 10
14
&OHgr; per square has advantageously a resistance against abrasion measured by the ASTM-1938 abrasion test of less than 0.1 g.
According to a possible embodiment, the doctor blade comprises a flexible substrate having a free end edge, said free end edge being at least covered by the said element. Preferably, at least the part of the element covering the said free edge has a face having an electrical surface resistivity of less than 9.9 10
14
&OHgr; per square.
According to another embodiment, the substrate is a flexible substrate having a face on which the element is attached, the said face of the substrate having a free end edge. The element is distant from said free end edge advantageously of a distance of at least 50 &mgr;m, preferably of at least 100 &mgr;m, for example of 200 &mgr;m to 600 &mgr;m.
The element comprises advantageously only a top layer containing conductive material, said layer having a thickness of less than 50 &mgr;m, for example comprised between 10 and 35 &mgr;m, and a face adapted for working with a magnetic roller having an elelctrical surface resisitivity of less than 9.9 10
14
&OHgr; per square.
According to a preferred embodiment, the element comprises at least two layers, namely
a first layer made at least partly of polyurethane, said layer having a thickness of more than 100 &mgr;m, and
a second layer covering at least partly the said first layer and being adapted for working with a magnetic roller of a copier, printer or facsimile machine, said second layer being made at leat partly of polyurethane and conductive material, said second layer having a thickness of less than 100 &mgr;m and an elelctrical surface resistivity of less than 9.9 10
14
&OHgr; per square.
The first layer has advantageously an electrical surface resistivity of more than 10 10
14
&OHgr; per square.
According to another possible embodiment, the doctor blade comprises a flexible substrate having a free end edge, the said first layer being glued on a face of the said substrate at a distance from the said first layer so as to form a groove or recess with a depth of at least 100 &mgr;m, preferably of at least 200 &mgr;m. The said depth is advantageously comprised between 200 and 600 &mgr;m. The said groove has advantageously a width of at least 200 &mgr;m, for example comprised between 500 &mgr;m and 5 mm, but preferably comprised between 500 &mgr;m and 2 mm.
The invention relates also to a toner assemble for a copier, printer or facsimile machine, said toner aseembly comprising at least:
a container or catridge for containing toner;
a magnetic roller, and
a doctor blade working with the magnetic roller,
the said toner assembly having the improvement that the doctor blade consists of at least a substrate provided with an element having a face adapted for working with a magnetic roller of a machine selected from the group consisting of copier, printer and facsimile machine, said element being made at least partly of an elastic material, wherein at least a part of the face adapted for working with a magnetic roller has an electrical surface resistivity of less than 9.9 10
14
&OHgr; per square (advantageously of less than 10
13
&OHgr; per square, preferably between 10
7
and 10
12
&OHgr; per square, most preferably between 10
8
and 10
11
&OHgr; per square) and wherein at least a part of the element made at least partly of an elastic material has thickness of at least 100 &mgr;m(advantageously comprised between 100 &mgr;m and 5 mm, preferably between 200 &mgr;m and 3 mm, most preferably between 200 &mgr;m and 1 mm).
The doctor blade and the element are advantageously as disclosed here before when describing the doctor
Braun Fred L
CF Technologies
Darby & Darby
Ngo Hoang
LandOfFree
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