Self-Grounding I/O Card
A self-grounding input/output (I/O) card assembly in accordance with one embodiment of the present invention includes at least a printed circuit board (PCB), at least one BNC connector attached to the PCB, and a metallic tab formed on the PCB. In accordance with the present invention, the metallic tab is formed on the PCB such that when the I/O card assembly is installed into a metallic housing, the metallic tab contacts the metallic housing and bends back until the metallic tab makes contact with the body of the BNC connector thus creating a continuous grounding loop between the BNC connector, the self-grounding I/O card and the metallic housing.
This application claims the benefit of U.S. Provisional Patent Application No. 60/562,858, filed Apr. 15, 2004, which is incorporated herein by reference in its entirety.
TECHNICAL FIELDThis invention relates to input/output (I/O) cards, and more particularly, to a self-grounding I/O card.
BACKGROUND ARTTransferring signals to and from printed circuit boards within an electronic device invariably involves printed circuit board connectors which couple signals to ribbon or wire conductors, coaxial cable etc. The ribbon, wire or coaxial conductors in turn couple the signals from the printed circuit board connector to and from a connection panel which provides an input output capability via conductors coupling to external equipment. Electronic equipment having such printed circuit boards and functioning with high frequency signals, for example in a range from 10 mega Hertz to beyond 1 giga Hertz, can suffer impaired performance. For example, if signal and signal return conductor impedance variations or discontinuities exist at each conductor junction, degraded signal propagation can result. Such impedance discontinuities, also known as return loss, will cause unwanted and undesirable signal reflections which degrade the wanted transmission signal by adding and or subtracting various components of the transmission signal and limiting the maximum interconnection length or signal detection threshold etc.
It is known to provide a direct connective arrangement between a printed circuit board conductor and a connector mounted to the printed circuit board such that when inserted within a module frame or chassis, the on-board connector protrudes beyond the module frame, or chassis to provide an I/O connection at a panel. In the case of a printed circuit board having BNC connectors, edge conductors are located at a module edge such that when inserted into a module frame the printed edge conductors extend or protrude into and mate with an end portion, or mounting throat of a bulkhead or chassis mounted BNC connector. This connective method offers the advantages of reduced parts count and reduced manufacturing and assembly costs. In addition this connective arrangement can provide a better impedance match between the BNC connector and the PCB conductor.
A BNC mounting throat, however, requires excellent contact performance for both, the signal and signal return or ground connections to reduce the effects of electromagnetic radiation. Electromagnetic radiation is a natural consequence of current flow through the electrical circuits on a card. Unchecked, electromagnetic radiation can interfere with and disrupt the operation of electrical and electronic circuits in a host device. The interference resulting from electromagnetic radiation is commonly known as electromagnetic interference (EMI). Because electromagnetic radiation is a natural consequence of current flow, it cannot practically be prevented. Instead, emissions of the electromagnetic radiation must be controlled in order to prevent harmful EMI from resulting.
In many circumstances, electromagnetic interference (EMI) can be prevented or reduced by enclosing components in a substantially continuous conductive shell. That is, it is generally acknowledged that metal or metallic structures, if properly located and grounded, can be effective in controlling harmful electromagnetic radiation. Metals are effective in this regard because they generally have a low characteristic impedance which has the desirable characteristic of reflecting the high impedance electromagnetic radiation typically emitted by computers and related devices. By reflecting the electromagnetic radiation away from vulnerable circuits or devices, the metal thereby acts as a protective shield.
In prior art arrangements to prevent harmful EMI from resulting, return signal connection spring ground clips have been employed, which are attached to a BNC body, as shown in
The present invention addresses the deficiencies of the prior art by providing a self-grounding input/output (I/O) card.
In one embodiment of the present invention, a self-grounding input/output (I/O) card assembly includes a printed circuit board (PCB), at least one metallic I/O connector (such as a BNC) attached to the PCB board, and a metallic tab formed on the PCB. In accordance with the present invention, the metallic tab is formed on the PCB such that when the self-grounding I/O card is installed into a metallic housing, the metallic tab formed on the PCB contacts the metallic housing and bends back until the metallic tab makes contact with the body of the metallic I/O connector (e.g., BNC) thus creating a continuous grounding loop between the metallic I/O connector (e.g., BNC), the self-grounding I/O card and the metallic housing.
In an alternate embodiment of the present invention, a self-grounding input/output (I/O) card as described above further includes a slot for mating said I/O card with a second PCB. The slot of the self-grounding I/O card of the present invention is lined with solder to facilitate a continuous grounding loop including the second PCB.
BRIEF DESCRIPTION OF THE DRAWINGSThe teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
DETAILED DESCRIPTIONThe present invention advantageously provides a self-grounding input/output (I/O) card. Although throughout the teachings herein and in various embodiments of the present invention, the aspects of the present invention are described with respect to an I/O card housed by a rack unit and including a BNC I/O connector, the specific embodiments of the present invention should not be treated as limiting the scope of the invention. It will be appreciated by those skilled in the art and informed by the teachings of the present invention that the concepts of the present invention can be advantageously applied to I/O cards housed in substantially any chassis and comprising substantially any metallic I/O connector.
The prior signal grounding arrangement shown
However, the return signal grounding arrangements of
In accordance with the present invention, when a self-grounding I/O card of the present invention, such as the I/O card 200 of
Optionally, a protruding edge of the metallic tabs of a self-grounding I/O card of the present invention may mate with a hole or indentation having a similar form in for example a metal rear panel of a chassis that houses the self-grounding I/O card for not only completing a continuous grounding loop from the metallic edge I/O connectors to the chassis and for grounding the I/O card itself, but also for assisting in locating the self-grounding I/O card of the present invention and for providing stability to the self-grounding I/O card. For example, in the self-grounding I/O card 200 of
More specifically, the self-grounding I/O card 300 of
As recited above with respect to the self-grounding I/O card 200 of
As described above, the self-grounding I/O card 300 of
More specifically, the slot 350 of the self-grounding I/O card 300 of
Although the concepts of a self-grounding I/O card of the present invention described above with reference to
While the forgoing is directed to various embodiments of the present invention, other and further embodiments of the invention can be devised without departing from the basic scope thereof. As such, the appropriate scope of the invention is to be determined according to the claims, which follow.
Claims
1. An input/output (I/O) card assembly, comprising:
- a printed circuit board (PCB);
- at least one metallic I/O connector attached to said PCB; and
- a metallic tab formed on said PCB, said metallic tab formed such that when said I/O card assembly is installed into a metallic housing, said metallic tab contacts said metallic housing and bends back until the metallic tab makes contact with the body of said at least one metallic I/O connector thus creating a continuous grounding loop between said at least one metallic I/O connector, said I/O card assembly and said metallic housing.
2. The I/O card assembly of claim 1, wherein said at least one metallic I/O connector comprises at least one BNC connector.
3. The I/O card assembly of claim 1, wherein said metallic tab comprises solder.
4. The I/O card assembly of claim 1, further comprising a slot for mating said I/O card assembly with a second PCB.
5. The I/O card assembly of claim 4, wherein said slot is metallically lined.
6. The I/O card assembly of claim 5, wherein said slot is lined with solder.
7. The I/O card assembly of claim 4, wherein said I/O card assembly comprises an audio/video card.
8. The I/O card assembly of claim 7, wherein said second PCB comprises a matrix PCB having a metallically lined slot.
9. The I/O card assembly of claim 1, wherein at least a portion of said at least one metallic tab mates with a similarly shaped indentation or hole of said metallic housing for providing support for said I/O card assembly.
Type: Application
Filed: Apr 15, 2005
Publication Date: Oct 11, 2007
Inventors: Steven Miller (Nevada City, CA), Scott Praitt (Grass Valley, CA)
Application Number: 11/578,397
International Classification: H05K 5/00 (20060101);