Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1996-04-08
1998-11-10
Krynski, William
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428379, 4284231, 4284258, 428906, 492 53, 492 56, 492 59, 355284, D02G 300
Patent
active
058341161
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an electroconductive roller which controls the static electricity on an object with which it is in contact, such as a toner supply roller, developing roller, transfer roller, cleaning roller or the like used in a printer of electrophotography and electrostatic recording systems.
Generally, the conventional electrophotographic process in which a toner is supplied from a toner cartridge to a light-sensitive object on which an electrostatic latent image is formed, transferred onto a sheet of paper and fixed thereon, includes (1) charging, (2) exposure, (3) development, (4) transfer, (5) fixation and (6) discharging. In each of these processes, various types of rollers are used to precisely control the static electricity on an object with which they are in contact. Recently, the requirements for the materials of such rollers have become increasingly stricter. The resistance of these rollers is measured under different ambient conditions or environments including: (1) a temperature of 35.degree. C. and a relative humidity of 85%, referred to as the "H/H environment;" (2) a temperature of 25.degree. C. and a relative humidity of 50%, referred to as the "N/N environment;" and (3) a temperature of 10.degree. C. and a relative humidity of 15%, referred to as the "L/L environment."
Since the rollers used in a developing mechanism such as a toner supply roller, developing roller and transfer roller, and those used in a cleaning mechanism, control the static electricity on a contacting object, they are required to have mechanical and electrical characteristics both better than ever. Heretofore, the polyurethane resin has been used in the form of a foam or elastomer to make such rollers because of its high durability, flexibility, low compression-caused permanent setting and low staining. In a urethane resin containing no electrically conductive additive, water and impurities existing therein will act as carrier and are slightly conductive. This mechanism of conduction is regarded as an ionic conduction, and the electrical property of the urethane resin is characteristic of the ionic conduction. A roller made of such an ordinary urethane resin shows a resistance of 10.sup.7 to 10.sup.9 .OMEGA. in the H/H environment while the resistance is 10.sup.9 to 10.sup.11 .OMEGA. in the LL environment. Namely, the resistance in the H/H environment is more than tens different from that in the L/L environment. The resistance varies little when a voltage is applied to the urethane resin.
In case such a roller is used, especially when it is used as connected to a power source controlled to a constant current, its resistance is low in the H/H environment so that a low voltage develops under the constant-current control. Since the roller shows a high resistance in the L/L environment, a high voltage develops. Many power sources controlled for a constant current, used in ordinary electrophotography systems, are controlled to 0.1 to 30 .mu.A. Assume, for example, a roller showing a resistance of 1.times.10.sup.8 .OMEGA. in the H/H environment while showing 2.times.10.sup.10 .OMEGA. in the L/L environment. If the roller is used as fed from a power source controlled to a constant current of 1 .mu.A, then voltages of 100 V and 20,000 V are developed in the respective environments. Thus, in case this roller is used, a high voltage is required in the L/L environment so that the capacity of the power source has to be increased and a countermeasure for discharging has to be taken, which will be disadvantageous economically and in terms of space. Also, in case the roller is used as connected to a power source of which the capacity is fixed and insufficient, the capacity is insufficient in the L/L environment so that no necessary magnitude of current is available, possibly causing a problem in imaging and the like.
To overcome the above drawbacks of the prior art, it has been proposed to lower the resistance of the roller by adding to the materials of the roller a substance which makes
REFERENCES:
patent: 4618630 (1986-10-01), Knobel et al.
patent: 5076201 (1991-12-01), Nishio et al.
patent: 5082870 (1992-01-01), Fududa et al.
patent: 5096934 (1992-03-01), Roberts et al.
patent: 5241343 (1993-08-01), Nishio
Mori Yuichiro
Saito Miho
Sawa Eiji
Bridgestone Corporation
Gray J. M.
Krynski William
LandOfFree
Electroconductive roller does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electroconductive roller, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electroconductive roller will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1514785