Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-07-13
2001-05-08
Gandhi, Jayprakash N. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S689000, C361S800000, C361S825000, C174S034000, C362S248000, C362S367000
Reexamination Certificate
active
06229713
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to light channels for indicating lights in computer systems and particularly to light channels that include electromagnetic interference (EMI) shielding.
2. Description of the Related Art
Many computer systems, including personal computers, workstations, servers, and embedded systems are designed to have multiple peripheral devices included in the system. A typical personal computer system includes a processor, associated memory and control logic and a number of peripheral devices that provide input and output (I/O) for the system. Such peripheral devices include, for example, compact disk read-only memory (CD-ROM) drives, hard disk drives, floppy disk drives, and other mass storage devices such as tape drives, compact disk recordable (CD-R) drives or digital video/versatile disk (DVD) drives. Additionally, computer systems often have the capability to interface with external enclosures that include additional peripheral devices.
Because these peripheral devices, and other portions of a computer system as well, often have one or more indicating lights, typically light emitting diodes (LEDs), the chassis or enclosure of the computer system is designed to allow the indicating lights to be seen by a user. This is typically accomplished using holes or slots in the chassis or enclosure that correspond with the position of the indicating lights. In computer systems that have a large number of closely spaced indicating lights, for example a server having multiple hard disk drives, each with multiple indicating lights, holes accommodating individual lights often overlap, making a single large slot preferable to several small holes. Although large slots accommodating multiple adjacent holes can be preferable from a manufacturing perspective, large openings in the computer system chassis can lead to electromagnetic interference (EMI) problems.
High speed electronic computer components inside the computer system chassis create radio frequency emissions that can interfere with other devices. Doors, removable panels, displays, ventilation openings, and other holes in the chassis allow unwanted EMI to escape the enclosure. In order to contain the EMI, openings in the chassis must be made as small as possible, or shielding must be provided to minimize the amount of EMI emanating from the chassis.
Additionally, when closely spaced indicating lights are not mounted flush with or protruding from the computer system chassis or enclosure (i.e. the lights are mounted some distance behind the front of the chassis) light from one indicating light is likely to bleed-over to an adjacent indicating light, making it difficult for a user to be certain whether one or both of the two lights are on or off. This problem can be compounded when there is some intervening layer that tends to diffuse the light from the indicating lights, such as, for example, a Mylar® label that adheres to the front of the computer system over the openings for the indicator lights and includes icons for labeling each light's function or purpose.
Accordingly, it is desirable to have a device that can shield some or all of the light from adjacent indicating lights and thereby prevent light bleed-over, while at the same time reducing the amount of EMI the escapes a computer system chassis or enclosure through holes or slots associated with the indicating lights.
SUMMARY OF THE INVENTION
It has been discovered that a device that includes multiple light channels for separating the light from adjacent indicating lights and preventing bleed-over can be constructed to include an electrically conductive material so that the device can also serve as an EMI shield to reduce the amount of EMI escaping from a computer system chassis. By reducing light bleed-over from one indicating light to the next, such a device reduces the likelihood that a user will be confused about whether an indicating light is on or off. Additionally, closely spaced indicating lights can be accommodated by slots in the chassis while EMI is reduced by the shielding effects of the light channel device.
Accordingly, one aspect of the present invention provides an apparatus including a base, a first hole, and a second hole. The base has a first surface, an opposing second surface, and a thickness therebetween, and includes an electrically conductive material. The first hole is sized to accommodate a first light emitting diode (LED) and extends from the first surface to the second surface of the base. The second hole is sized to accommodate a second LED, and extends from the first surface to the second surface of the base. The second hole is located adjacent to the first hole. The thickness of the base is at least as great as the height of either the first LED or the second LED so as to separate some light of the first LED from light of the second LED.
In another aspect of the invention, a computer system includes a processor, a memory coupled to the processor, a chassis supporting the processor and the memory, and a circuit board coupled to the chassis. The circuit board includes first and second LEDs. The computer system also includes a light channel located between the circuit board and the chassis. The light channel has a base, a first hole, and a second hole. The base has a first surface, an opposing second surface, and a thickness therebetween, and includes an electrically conductive material. The first hole is sized to accommodate a first light emitting diode (LED) and extends from the first surface to the second surface of the base. The second hole is sized to accommodate a second LED, and extends from the first surface to the second surface of the base. The second hole is located adjacent to the first hole. The thickness of the base is at least as great as the height of either the first LED or the second LED so as to separate some light of the first LED from light of the second LED.
In still another aspect of the invention, a method is disclosed. In a computer system including a processor, a memory coupled to the processor, a chassis supporting the processor and the memory, and a circuit board coupled to the chassis and including a first light emitting diode (LED) and a second LED, light of the first LED is separated from light of the second LED with a light channel. An exterior of the computer system is shielded from electromagnetic interference (EMI) from an interior of the computer system using the light channel.
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McAnally Andrew L.
Schmitt Ty R.
Ascolese Marc R.
Dell U.S.A. L.P.
Gandhi Jayprakash N.
Skjerven Morrill & MacPherson LLP
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