Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
2000-04-25
2001-08-07
Nguyen, Chau N. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
C174S036000
Reexamination Certificate
active
06271472
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to cables, and more particularly to improved cables used to interconnect computer systems to external peripheral devices.
2. Description of the Related Art
Personal computers provide today's users with the power to communicate with other networked users, share information and access data from peripheral devices. As is well known, personal computers are capable of being connected to a variety of peripheral devices, such as, fixed and removable storage drives, scanners, compact discs, etc. To achieve high performance data transfer interfaces between the host computer system and a given peripheral device, computer users typically use hardware that can take advantage of the small computer system interface (SCSI) protocol. Typically, a computer is provided with SCSI capabilities via SCSI controller cards that connect to the host computer or via a SCSI chip that is integrated as part of the computer's motherboard. Once a computer is provided with SCSI capabilities, the user is able to connect either internal or external SCSI peripheral devices to the computer. Internally, SCSI ribbon cables are used to interconnect the peripheral devices to the computers controller card or a motherboard's connector. Externally, SCSI peripheral devices can be coupled to the computer's connector receptacle via an external SCSI cable.
FIG. 1A
illustrates a computer system
10
having a SCSI peripheral device (PD)
12
connected thereto. Generally, a SCSI cable
14
is connected to a SCSI controller connector located on the backside of the computer system's housing. The other end of the SCSI cable
14
has a connector
16
that couples to the SCSI peripheral device
12
. Unfortunately, SCSI cables
14
which comport to the rigorous SCSI electrical specification requirements are designed having thick and rigid physical characteristics. For instance, SCSI cable
14
typically has an outer diameter of about ½ inch. Although the SCSI protocol has evolved through several generations to provide enhanced throughput capabilities, the physical makeup of the cabling has remained substantially the same. As a result, the SCSI protocol itself is sometimes viewed by consumers as behind the times, simply because the cabling appears thick, bulky, and is extremely rigid.
FIG. 1B
shows a magnified view of the SCSI cable
14
and its internal contents. As shown, the SCSI cable typically has an outer jacket that covers a braided conductive shield
18
. The braided conductive shield
18
covers several layers of tightly wrapped plastic and an insulative cover
20
. The tightly wrapped plastic and insulative cover
20
is configured to enclose the plurality of wires
22
, which lead to the connector
16
, which may be a 50 pin or 68 pin connector. Although there has been a desire to reduce the physical size of the SCSI cable
14
, cable designers were largely prevented from completing this task because the SCSI ANSI X3.131 standard for SCSI-1, SCSI-2, and SCSI-3, imposes strict electrical characteristic requirements. In addition, present manufacturing techniques and tooling for conventional SCSI cables are not capable of producing cables with thinner dimensions.
Beyond the fact that conventional SCSI cables
14
place an improper stigma on the SCSI protocol as a whole as being outdated, users of today's computer systems also demand that external cabling be more flexible and capable of spanning longer distances. For instance, users sometimes like to place the housing of the computer system under a desk or at a location that is spaced apart from the computer monitor. At the same time, the user may want to place external peripheral devices, such as, second hard drives, removable drives, scanners, CD ROMs, CD-Rs, CD-RWs, on the desk top near the monitor so as to provide easy access during a working session. Conventional SCSI cables that meet the full SCSI electrical specification are quite short, spanning distances of approximately 2 to 3 feet. The length limitation, coupled with the thick and bulky nature of the SCSI cable, thus reinforces the improper image of SCSI being old and outdated.
Furthermore, because conventional SCSI cables are not very flexible, when a connection is made to the computer housing, the computer housing is sometimes required to be arranged in an awkward way, so as to avoid accidental unplugging. That is, because the conventional SCSI cable resists bending, movement of the computer housing can in some cases cause the connector to be partially unplugged. Consequently, the physical nature of the SCSI cable can introduce a level of unreliability, which can hamper a computer user's image of SCSI and the user's desire to use SCSI for interconnecting to and from external peripheral devices.
In view of the foregoing, there is a need for SCSI cables that have smaller diameters, have improved flexibility, and have the ability of spanning longer distances, while continuing to meet the cabling electrical characteristics set forth in the SCSI standard.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by providing a cable design for use in interconnecting to external SCSI peripheral devices. The cable is designed to be highly flexible and thin, relative to conventional SCSI cables. It should be appreciated that the present invention can be implemented in numerous ways, including as a process of making, an apparatus including the cable, a system for making, or a cable device. Several inventive embodiments of the present invention are described below.
In one embodiment, a SCSI external cable is disclosed. The cable includes: (a) an inner non-conducting fiber; (b) a core layer of twisted pairs, each of the core layer twisted pairs in the core layer being concentrically wrapped around the inner non-conducting fiber; (c) a first layer of twisted pairs, each of the first layer twisted pairs being concentrically wrapped around the core layer of twisted pairs; (d) a second layer of twisted pairs, each of the second layer twisted pairs being concentrically wrapped around the first layer of twisted pairs; (e) an inner shield being concentrically wrapped in a first direction around the second layer of twisted pairs; (f) an outer shield being concentrically wrapped in a second direction around the inner shield, the second direction being opposite the first direction of the inner shield; and (g) a jacket configured to wrap around the outer shield. In this embodiment, a tape separator can optionally be wrapped concentrically around the second layer of twisted pairs, and then, the inner shield can be wrapped around the tape separator. Preferably, the inner shield is an aluminum tape, and the outer shield is in the form of a plurality of flat copper filaments (aligned side-by-side). The plurality of flat copper filaments and the aluminum tape function together to provide the SCSI external cable with an increased degree of flexibility. Most preferably, the cable of this embodiment is capable of being implemented for connectors having up to about 68 pins.
In another embodiment, a SCSI external cable capable of being implemented for connectors having up to about 50 pins is disclosed. The SCSI cable of this embodiment includes: (a) an inner non-conducting fiber; (b) a first layer of twisted pairs, each of the first layer twisted pairs being concentrically wrapped around the inner non-conducting fiber; (c) a second layer of twisted pairs, each of the second layer twisted pairs being concentrically wrapped around the first layer of twisted pairs; (d) an inner shield being concentrically wrapped in a first direction around the second layer of twisted pairs; (e) an outer shield being concentrically wrapped in a second direction around the inner shield, the second direction being opposite the first direction of the inner shield; and (f) a jacket configured to wrap around the outer shield.
In yet another embodiment, a SCSI external cable for interconnecting external peripher
Karrmann David E.
Mattos Steve D.
Plourde Kenneth J.
Adaptec, Inc.
Martine & Penilla LLP
Nguyen Chau N.
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