Electricity: electrical systems and devices – Safety and protection of systems and devices – High voltage dissipation
Reexamination Certificate
1999-04-08
2001-06-12
Leja, Ronald W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
High voltage dissipation
C361S753000, C361S799000
Reexamination Certificate
active
06246560
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to the field of grounding of electrical signal processing systems and more particularly to a peripheral device isolator.
BACKGROUND OF THE INVENTION
Manufacturers of telecommunications processing system devices utilize isolated or integrated grounding schemes to comply with Bellcore. Telecom grounding schemes isolate Frame/Chassis/Safety ground from power ground.
Computer systems and peripherals have traditionally used a single common logic and chassis ground. Thus, all logic components and the chassis enclosing the logic components are connected to a common ground. Chassis components also include the cases of peripheral devices such as tape drives and CD-ROM drives. Therefore, a transient voltage on the device chassis may enter the internal logic components as the transient voltage travels to the single integrated logic and chassis ground. The transient voltage can cause system interruption and damage. A transient voltage such as ESD commonly occurs with devices requiring human interaction. The human body has an electrostatic potential which may discharge upon touching the device. This discharge can be up to 15,000 volts applied directly to the device causing a transient voltage spike which will follow the path of least resistance to a ground. If the electrostatic discharge or any other transient surge occurs on a computer device, such as a CD-ROM drive or a tape drive, the voltage spike follows the path of least resistance to the single common logic and chassis ground. This path could flow through logic components which could be interrupted or damaged due to the voltage spike.
Manufacturers of telecommunications processing devices and systems desire to use computer peripherals in the design of their systems. However, this presents a grounding problem since computer peripherals use a common logic and chassis ground. Some manufacturers of telecommunications processing systems mount computer peripherals in their systems, isolating the computer peripheral from the host system frame using some form of non-conducting isolators. This maintains the separation of the host system logic and frame grounds. However, if the computer peripheral requires human interaction, a transient voltage spike may occur on the computer peripheral. Therefore, the resulting voltage spike would travel through the computer peripheral chassis to the host system logic ground since the computer peripheral's common integrated logic and chassis ground is attached to the host system logic ground. Thus, the voltage spike would enter the host system logic ground which could result in the voltage spike entering logic components thereby causing interruptions or damages to those components.
Due to the aforementioned problems, it is desirable to provide a ground isolation technique that allows for the implementation of computer peripheral devices in a telecommunications system.
SUMMARY OF THE INVENTION
From the foregoing, it may be appreciated that a need has arisen for a peripheral device isolator that allows computer peripheral devices to be incorporated into a telecommunications system. In accordance with the present invention, a system and method for isolating a peripheral device and protecting the host system from a transient voltage on the peripheral device is provided which substantially eliminates or reduces disadvantages or problems associated with using computer peripheral devices in telecommunications systems.
According to one embodiment of the present invention, there is provided a peripheral device isolator which is capable of isolating a peripheral device from a host system frame and diverting transient voltages on the peripheral device into the host system frame. The peripheral device isolator is constructed of an insulating material with a conductive area on each of two opposite sides. These conductive areas are connected to each other via a transient voltage suppression device.
According to another embodiment of the present invention, there is provided a processing system which has a system frame with a frame ground, chassis components with a chassis ground, and a plurality of logic components which are grounded to a separate logic system ground. Peripheral devices having an integrated chassis and logic ground used in the processing system are isolated from the system frame with a peripheral device isolator which has a transient voltage suppressor. The Peripheral Device Isolator connects the peripheral device chassis to the system frame. This electrical signal path allows a transient voltage spike on the peripheral device chassis to travel into the system frame and, thus, into the frame ground. This prevents the transient voltage spike from entering the plurality of logic components either within the peripheral device chassis or within the host system logic ground and causing interruptions or damages.
The present invention provides various technical advantages over conventional device isolation techniques. For example, one technical advantage is to provide an electrical signal path from the peripheral device chassis to the host system frame so that transient voltage spikes can travel from the peripheral device chassis directly into the host system frame ground without affecting any logic components within the peripheral device chassis or the host system. Another technical advantage is to implement a peripheral device isolator to allow incorporation of computer peripheral devices into a telecommunications system. Other examples may be readily ascertainable by those skilled in the art from the following figures, description, and claims.
REFERENCES:
patent: 4958255 (1990-09-01), Pritchard
patent: 5786974 (1998-07-01), Zaretsky
Linares Ignacio A.
Reynolds Dale L.
Topper, III Donald H.
Alcatel USA Sourcing L.P.
Baker & Botts L.L.P.
Leja Ronald W.
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