BACKGROUND OF THE INVENTION Computing devices, such as personal computers, are now commonplace in the consumer market. Unfortunately, the current state of the art in enclosure and expansion card design requires considerable expertise and time on the part of the user to change or upgrade the functionality of such devices. Most designs allow for the upgrade procedure to be accomplished using common household tools, or no tools at all, although all of the designs typically require at least partial disassembly of the housing.

In the industrial and telecommunications markets, computer enclosures of rack-mount type are used. Rack-mount enclosures typically consist of a five-sided box with the front vertical face open to accept expansion cards. A backplane having a number of sockets is usually installed in the back of the unit and parallel to the back vertical wall. Expansion cards are installed from the front, guided by rails or similar mechanisms, and engage sockets on the backplane when fully seated. All connections for external cables are placed at the front of the unit and on the front bezel of each expansion card. Disk drives with removable media, such as floppy drives, are often placed directly onto expansion cards providing direct access to the

media and eliminating the need for cables. The designs using rack-mount enclosures include industry-standard computers based on busses such as VME and others that provide excellent accessibility to expansion cards without requiring enclosure disassembly. Unfortunately, the fact that all external cables attach to expansion cards from the front of the enclosure renders the rack-mount enclosure unacceptable for the office and home microcomputer market from cosmetic, ergonomic and safety considerations.

One of the primary requirements for the desktop computer market is the ability to attach additional external cables to the back of the computer enclosure. This positions such cables out of sight, reduces desktop clutter, and prevents accidental disconnection by the user. All the solutions currently available in the office and home microcomputer markets, including those based on industry-standard busses such as ISA, PCI, NuBus and Micro Channel, approach this problem in essentially the same manner. The typical microcomputer enclosure is a six-sided box constructed of at least two major parts, a chassis and a cosmetic cover. The back vertical wall of the chassis features openings through which connectors on expansion cards may be accessed.

A backplane or a motherboard is installed in the chassis perpendicular to the back vertical wall and includes a plurality of sockets for accepting expansion cards. The expansion cards of prior art enclosures typically comprise a bus connector located along one edge of the card and optional electrical connectors for the attachment of external cables located along an adjacent, perpendicular edge of the card. A metal bezel is typically utilized on expansion cards to block the portion of the opening in the back vertical wall of the chassis that is not utilized for accessing electrical connectors on the card. When a card having electrical connectors is

installed in a socket on the backplane, the electrical connectors on the card can then be accessed through an opening in the back vertical wall of the chassis.

The process of installing expansion cards involves four major steps. First, the cosmetic cover is removed from the chassis. Second, an opening in the back vertical wall of the chassis is exposed by removing a metal bracket or cover plate. Third, an expansion card is installed perpendicular to both the backplane and the back vertical wall of the chassis by inserting the card into an appropriate socket on the backplane so that the bezel of the expansion card aligns with the opening in the back vertical wall exposed in step two. Step four involves the installation of the cosmetic cover back onto the chassis.

The typical microcomputer enclosure is further complicated by the fact that disk drives with removable media are best accessed from the front of the enclosure. To facilitate such access, the majority of microcomputer enclosures incorporate separate drive bays at the front of the enclosure. The placement of the drive bays at the front of the enclosure requires the use of cables to provide electrical connections between the drive and the drive controller card. A disk drive is installed in a typical microcomputer chassis, with or without special adapter brackets, in a five-step process. Step one involves the removal of the cosmetic cover from the chassis. In step two, a blank bezel is removed from the cosmetic cover to allow subsequent access to the disk drive. The third step consists of the installation of the disk drive in a drive bay. Extra steps may now be required to install a drive controller card in an expansion slot, if one is not already present. Then, in step four, the necessary cables are connected between the

drive and the drive controller card as well as the power supply. In step five the cosmetic cover is installed back on the chassis.

As can be seen from the above description, the microcomputer chassis designs of the prior art achieve the placement of external cable connections on the back of the enclosure at the expense of significant complexity in terms of both design and serviceability.

Due to the rapidly changing nature of the computer market, the ability to easily upgrade the functionality of computing devices is essential in maintaining their usefulness. As more and more computing devices find their way into the homes of consumers who lack technical training, the ease with which these devices can be upgraded becomes a major factor in determining their useful life. In addition to the difficulties in upgrading and service, the design complexity of existing microcomputer enclosures results in considerable expense to the manufacturer in terms of raw materials, tooling, and manufacturing cost, thereby diminishing the manufacturer's overall ability to compete in the marketplace.

What is needed is a new design to allow computing devices that can be upgraded easily in the field by untrained consumers and that can be manufactured efficiently with the minimum number of parts and assembly steps.

SUMMARY OF THE INVENTION The main objective of the present invention is to provide a computer enclosure and expansion card design which facilitates the installation and removal of expansion cards from the front of the enclosure without disassembly of the enclosure, and also allows the attachment of external cables to install expansion cards from the back of the enclosure. A computer enclosure apparatus and a complementary expansion card design are disclosed herein that achieve this objective. Within the context of the invention, the term'computer'means any electronic device for processing digitally encoded information.

The computer enclosure has a back wall having a plurality of openings, equal in number to the maximum number of expansion cards the enclosure is designed to receive, and also has a backplane with a plurality of sockets to accept expansion cards. The sockets are equal in number to the openings and are spaced the same distance apart as the openings. The backplane is mounted in the enclosure parallel to the back wall, and is sized and aligned so as not to block any of the openings, and so that each of the plurality of sockets is juxtapose to and substantially aligned with exactly one of the openings. The computer enclosure of the present invention is configure to receive expansion cards for installation from the front of the enclosure. The enclosure may additionally incorporate structure for slidably receiving the expansion cards as well as a latching structure to facilitate installation, positive retention and removal of the expansion cards.

The expansion card of the present invention includes a printed circuit board, a bus connector positioned along the back edge of the expansion card to engage one of the sockets on

the backplane, and a connector for the attachment of external cables to the expansion card. The connector is positioned along the same (back) edge of the expansion card as the bus connector and aligned so as to be accessible from the back of the enclosure through the appropriate opening in the enclosure back wall when the expansion card is installed in a socket on the backplane of the computer enclosure. Optional indicator lights, switches and removable media receptacles are positioned along the opposite (front) edge of the expansion card so as to be accessible from the front of the enclosure. An expansion card assembly is contemplated utilizing a small-size printed circuit board mounted on a metal frame. The frame is sized and proportioned so as to facilitate installation in the computer enclosure of the present invention, and the printed circuit board is mounted on the frame so as to align with a socket on the backplane and an opening in the enclosure back wall when the expansion card assembly is installed in the enclosure.

DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded perspective view showing the back wall of the enclosure that forms my invention having a plurality of openings, the backplane of the invention having a plurality of sockets and an expansion card interconnectable therewith; Figure 2 shows the components of Figure 1 assembled together in accordance with the present invention; Figure 3 is a perspective view showing the assembly in Figure 2 from the back;

Figure 4 is an exploded perspective view of an expansion card shown in Figures 1-3; Figure 5 shows the assembled expansion card of Figure 4 from a back perspective view; Figure 6 is a front perspective view of the assembly in Figure 5; Figure 7 shows an expansion card bracket supporting a small-format printed circuit board, a disk drive and a front bezel; and Figure 8 is a perspective view of the enclosure of the present invention showing the enclosure back wall and side walls.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the present invention is a low-cost ungradable home computer. A computing device intended for the consumer market places an equally high premium on cosmetic appearance, ease of use and low cost, and therefore stands to derive the most benefit from the innovations of the present invention.

The essential components of the invention are illustrated in Figure 1. An enclosure back wall 1 is an important part of a complete enclosure which, in the preferred embodiment, is a five-sided box with the front face open in order to receive expansion cards. The specific features of enclosure back wall 1 that are unique to the present invention are a set of openings 4 that will allow access from the outside to installed expansion cards on the inside. In addition,

the back wall 1 will allow the mounting of a backplane 2 parallel to the enclosure back wall 1.

Other means of mounting the backplane 2 parallel to the back wall 1 are possible that are not part of the enclosure back wall 1 but are instead incorporated into other parts of the computer enclosure. A number of computer enclosure designs are known in the prior art that feature access openings in the enclosure back wall. However the backplane or motherboard in these designs is mounted perpendicular to the enclosure back wall. By specifying that the backplane 2 is mounted parallel to the enclosure back wall 1, the benefits of the present invention enable expansion cards to be installed and removed from the front of the enclosure while external cables can be attached to the expansion cards from the back of the enclosure.

The main supporting structure is a printed circuit board 3. This is a horizontal member that will support electronics of the device which is being installed. Note that the backplane 2 has a plurality of sockets 5 which will connect with a bus connector 6 located on the printed circuit board 3. Bus connector 6 is of the card-edge type. Bus connector 6 may also be of the right-angle box type, in addition to a surface-mount type, in addition to any of a number of known types. Adjacent the bus connector 6 is a connector 7 intended to facilitate connection between the printed circuit board 3 and its associated electronics and points remote with respect to the present invention.

A metal back bezel 8 surrounds the connector 7 and accomplishes several functions. The bezel 8 provides support and stability to the connector 7. The bezel 8 further provides a sealing and finishing structure with respect to the plurality of openings 4. This will help where the enclosure of the present invention is being cooled under directed air flow. The bezel sealing

also prevents dust from entering and coming into contact with the electronics carried on the printed circuit board 3.

At the other end of the printed circuit board 3, a front bezel 9 is supported and shown with an indicator light 10. It is understood that the indicator light 10 may exist in multiple numbers depending upon the electronics carried by the printed circuit board 3 as is necessary to indicate functionality to the user.

The expansion card illustrated in Figure 1 is one of many designs that may be constructed in accordance with the present invention. Additional examples of such designs are shown in Figure 4, Figure 5, Figure 6 and Figure 7. In Figure 4, an exploded view of a CD-ROM expansion card is shown. A CD-ROM drive 11 is shown mounted directly onto the printed circuit board 3.

Figure 5 illustrates a rear view which specifically shows the details of connector 7 as well as the assembled version of the CD-ROM expansion card of the present invention. Figure 8 illustrates a slightly different version where the expansion card bracket 12 carries both a disk drive 13 and a small-format printed circuit board 14. This assembly meets the parameters of expansion card design under the present invention having a bus connector 6 and a connector 7 in side-by-side alignment on the back-facing edge of the assembly.

Thus, as is shown, there can exist a large variety of possible combinations for the expansion card of the present invention. Other structures can include floppy disk drives and

other receptacles of removable computer media, such as memory card sockets, to be easily mounted to printed circuit board 3 and made accessible through appropriate apertures in front bezel 9. This allows the combination of the entire storage subsystem, including the drive, the controller electronics, the means for interconnecting the controller to the drive, and all mounting hardware to fit into one easily serviceable assembly.

The important feature of expansion card design under the present invention is the co-location or side-by-side alignment of the bus connector 6 and connector 7 substantially on the same edge of the printed circuit board 3, the edge that faces towards the back of the enclosure when the expansion card is installed in the enclosure. This co-location of the two components enables the bus connector 6 to engage a socket 5 on the backplane 2 upon the installation of the expansion card in the enclosure and simultaneously make connector 7 accessible through a corresponding opening 4 in the enclosure back wall 1 for the purpose of attaching external cables.

To meet cosmetic and emissions requirements, a metal back bezel 8 and a plastic front bezel 9 are further incorporated into the design of the expansion card. As required, the front bezel 9 may feature an additional EMI shield, many forms of which are known in the art. The indicator light 10 may be placed on the printed circuit board 3 so as to be visible through a corresponding aperture in front bezel 9.

The enclosure design is further illustrated in Figure 8, having side walls 15 and incorporating a set of card guides 16 to slidably receive expansion cards. A complete enclosure

of the present invention will also incorporate a top wall and a bottom wall which have been omitted from the illustration in Figure 8 for clarity of presentation, inasmuch as the top and bottom walls are not essential to the present invention but serve the purposes of providing mechanical stability, improving the cosmetic appearance and providing EMI shielding.

The means used to assemble the structures shown in Figures 1-8 can be any method calculated to provide long life and serviceability. For example, in Figure 1, the backplane 2 is attached to the back wall 1 by use of set off structures 17 to avoid using screws or rivets to attach the backplane 2 while not forcing the surface of backplane 2 against the back wall 1. Other types of attachment are equally acceptable both for the backplane 2 and all other structures.