Patent Application
20090035979
1. Field of the Invention
The present invention relates generally to connectors for removable electronic cards, and in particular to a DIMM connector disposed on a motherboard for removably receiving a DIMM.
2. Description of the Related Art
A DIMM, or dual in-line memory module, comprises a series of random access memory chips mounted on a printed circuit board or “card” for use in computers. DIMMs are removably securable to corresponding DIMM connectors on a computer's motherboard. Each DIMM is usually retained on its associated DIMM connector by a latching mechanism included with the DIMM connector. The industry standard latching mechanism includes a latch at each end of the connector. The latches are operable by hand, allowing a person to secure or release a DIMM with the person's fingers. Usually, a DIMM is released from its connector by moving the latches outward, away from one another, in a plane generally parallel to the DIMM. This movement of the levers may also cause the DIMM to be ejected from its connector.
The advent of increasingly compact computer systems, such as blade servers, created a need for a memory module having a reduced form factor, which led to the development of Very Low Profile (VLP) DIMMs. The same design considerations that precipitated the development of VLP DIMMs make it desirable for DIMM connectors to also be compact. Current VLP DIMM connectors, however, have integral latching mechanisms similar to those of full height DIMM connectors. The outward movement of the latches requires designers to provide extra clearance or spacing on the motherboard about the DIMMs, even though this extra clearance is in opposition to achieving small component footprints. The increased clearance required around the latches is an inefficient use of the limited space on a motherboard and results in less than ideal packaging density.
One embodiment of the invention provides a reduced-footprint memory module connector. The memory module connector includes a connector body having a slot for removably receiving a DIMM and a latching mechanism for releasably securing the DIMM. The latching mechanism includes a lever pivotally secured adjacent to an end of the connector body on a pivot axis oriented generally parallel to a longitudinal face of the DIMM. The lever is movable about the pivot axis from a first position for securing the DIMM in the slot and a second position for releasing the DIMM from the slot.
Another embodiment of the invention provides a memory module assembly including a plurality of memory module connectors. The connectors have connector bodies oriented parallel to one another on a motherboard. Each connector body has a slot for removably receiving a respective DIMM. At least one latching mechanism is included with each connector. Each latching mechanism includes a lever pivotally secured adjacent an end of the respective connector body. A pivot axis is oriented generally parallel to a longitudinal face of the respective DIMM. The lever is movable about the pivot axis from a first position for securing the respective DIMM in the slot and a second position for releasing the respective DIMM from the slot.
Other embodiments, aspects, and advantages of the invention will be apparent from the following description and the appended claims.
The present invention includes a reduced-footprint connector having an improved latching mechanism for facilitating the insertion and removal of a circuit board or “card” within the connector. The invention is useful, for example, in the context of memory module connectors such as “VLP DIMM” (very low profile, dual in-line memory module) connectors, and will be discussed in that context throughout. However, DIMM connectors for full-height DIMMs are also within the scope of the invention. The reduced footprint achieved by the present invention makes the invention especially valuable when applied to VLP-type DIMM connectors, for which minimizing space and size requirements is particularly desirable.
The area of a motherboard or other mounting location allocated to a connector with a latching mechanism includes not only the area or projected area of the connector as it attaches to the motherboard, but also the area or projected area on the motherboard required for the operation of the latching mechanism. In the context of the present invention, therefore, a “footprint” of a connector may be defined to include the area or projected area occupied by the connector and also any additional area or projected area that must be allocated for a user to access and operate the latching mechanism during both installation and removal of the circuit board. This characterization of a footprint considers the desire to minimize not only the two dimensional surface area of a motherboard physically occupied by a connector with latching mechanism, but also the area allocated to the connector, including the latching mechanism of the connector, and operation thereof.
In one embodiment, a connector includes a unique latching mechanism (“latch”) having features that minimize the footprint of the connector and latching mechanism. First, the latching mechanism is located at or near the end of the DIMM, so that its use does not interfere with neighboring connectors and neighboring connectors may be spaced more closely. Second, the latching mechanism includes a lever that is pivotally secured about a pivot axis that is oriented generally parallel to the DIMM to be received within the connector. Thus, operation of the latch does not require outward movement of the levers that would increase the effective length and footprint of the connector. Third, this pivot axis is laterally spaced from the plane of the circuit board to increase the linear distance of DIMM movement that the lever can achieve for a given angular displacement of the lever. Fourth, the shape of the lever is configured to allow increased angular displacement of the lever without the lever extending appreciably outside the projected width of the connector body to which the lever is attached. In one configuration, for example, the portion of the lever that would otherwise extend outside the projected boundary of the connector body is angled so as not to extend past that boundary when the latch is open, yet due to the lateral spacing of the pivot axis, the lever also does not extend appreciably beyond the opposite boundary when the latch is closed. The shape of the lever is also configured so as to avoid interference with the VLP DIMM received into the connector.
Each of these features, individually, contributes to reducing the footprint of a VLP DIMM connector according to the invention. Combined, these features optimize the connector footprint while maintaining optimal performance of the latching mechanism. An overall connector length reduction of 14%, and a circuit board space savings of 20 mm (7.5%) of the motherboard area has already been achieved according to an embodiment of the invention.
While the prior art design of the connector 12 and latch 14 provides satisfactory retention and removal of the VLP DIMM 10, the outward movement of the levers 15 requires additional clearance about the VLP DIMM 10, as designated by reference dimension “A.” This requisite clearance must take into account both the width of the user's fingers 16A, 16B and the lateral, outward distance each lever 15 moves when operating the levers 15 to release the VLP DIMM 10. The effective length “L” of the connector 12 is the distance along the motherboard that is allocated for the connector 12 and operation thereof. As defined in the context of
First, the latch 24 includes a lever 25 pivotally secured to a lever support structure 30 about a pivot axis 41. The pivot axis 41 is generally parallel to the VLP DIMM 10, which is ninety degrees from the orientation of the conventional lever 15 with respect to its connector 12 of
Second, the pivot axis 41 is laterally spaced a distance X1 from the VLP DIMM 10. By virtue of this lateral spacing of the pivot axis 41, the latch 24 produces a greater upward (the “z” direction) displacement of the VLP DIMM 10 for a given angular rotation of the lever 25 about the pivot axis 41. This reduces the amount of angular displacement of the lever 25 required to raise and unseat the VLP DIMM 10 from the connector 22. Reducing the angular displacement of the lever 25 reduces the connector footprint by reducing the lever's required range of motion in a directional component parallel to the motherboard (the “x” direction). In this embodiment, the lever 25 does not move beyond a width W of the connector body.
Third, the latch 24 is positioned at the end of the connector 24, so that movement of the lever 25 does not impinge any of the neighboring connectors 22. This desirably minimizes a spacing “X2” between adjacent connectors 22, which reduces the combined footprint of multiple connectors 22. This spacing X2 can be smaller than the width of the user's finger, because, with the latch 24 at the end of the connector 24, the user's finger does not need to be inserted between the DIMMs 10 or the connectors 12 in order to operate the latches 24.
Fourth, the lever 25 is shaped to reduce the footprint of the connector 22. The lever 25 includes an angled portion 26 so that as the lever 25 is rotated counter-clockwise to release the VLP DIMM 10, the angled portion 26 is not moved beyond the width W of the connector body. As illustrated by a reference lever 25A in a counter-clockwise open position, the angled portion 26 of the levers 25 will be substantially parallel with the wall 21 when in the open position. Thus, when rotated to a position to release the VLP DIMM 10, the angled portion 26 of the lever 25 does not extend appreciably beyond the plane of wall 21 of the respective connector 22 (or alternatively, does not extend beyond a plane parallel to wall 21, but aligned with the edge 33 of the lever support structure 30). This minimizes the effective width and footprint of the connector 22.
The connector body 27 includes a DIMM socket or “slot” 28 for receiving the VLP DIMM 10. The slot 28 is empty (the VLP DIMM 10 is not inserted). The slot 28 has a set of terminals (“socket terminals”) 29 for electrical engagement with a corresponding set of terminals (“DIMM terminals”) 31 on the VLP DIMM 10. The socket terminals 29 may provide electronic communication pathways between the VLP DIMM 10 and a memory controller on a motherboard. The socket terminals 29 are typically I/O (input/output) type terminals, for carrying I/O signals such as data, strobe, and address between the memory controller and the VLP DIMM 10.
The lever support structure 30 is disposed adjacent to an end 32 of the slot 28 at a corresponding end of the connector body 27. Although not required, the connector body 27 in this embodiment is unitarily formed with the lever support structure 30 structure. In other embodiments, the lever support structure 30 may be structurally separate from the connector body 27, such as mounted directly to a motherboard adjacent to and in alignment with the connector body 27. The lever support structure 30 includes an opening or pocket 34 for receiving a lower end 36 of the lever 25. A pair of aligned pivot support holes 38 receives a corresponding pair of aligned male pivot members 40 on the lever 25. In this embodiment, the male pivot members 40 are circular bosses or protrusions 40 that fit within the respective holes 38, forming a hinged connection. Alternative mechanisms for pivotally mounting one member to another are known in the art, and may be substituted herein for the holes 38 and protrusions 40. Whatever the mechanism employed for pivotally securing the lever 25, the pivot axis 41 will be oriented generally parallel to a longitudinal plane of the DIMM, which is aligned with the slot 28. This orientation of the pivot axis 41 is ninety-degrees apart from that of the pivot axis of the conventional lever 15 of
The lever 25 includes a push point or “grip portion” 42 for the user's finger to push or pull on to pivot the lever 25 about the pivot axis 41. The grip portion 42 may be textured to provide a more secure “grip” with the user's finger. The lever 25 includes an upper engagement portion 44 for applying a downward force to the VLP DIMM 10 at a location 45 to urge the VLP DIMM 10 at least partially downward, i.e. into the slot 28, when the lever 25 is moved clockwise about the axis 41. With the DIMM fully inserted into the slot 28, the upper engagement portion 44 may also retain the DIMM within the slot 28. The lever 25 also includes a lower engagement portion or “leg” 46 for applying a generally upward force to the VLP DIMM 10 at a location 47, to urge the VLP DIMM 10 at least partially upward, i.e. out of the slot 28, when the lever 25 is moved counter-clockwise about the axis 41 relative to the orientation of
The lever 25 provides increased mechanical advantage as compared with the conventional lever 15 (
The pivot axis 41 of the lever is laterally spaced from the centerline of the VLP DIMM 10, as discussed previously. This spacing increases the reach of the leg 46 with respect to the pivot axis 41, to increase the vertical displacement of an end 43 of the leg 46 for a given angular displacement of the lever 25 about the pivot axis 41. Thus, the VLP DIMM 10 may be released from the connector 22 with less angular movement of the lever 25.
The lever 25 is also shaped to avoid interference with the VLP DIMM 10. One of the levers 25B in
A study has demonstrated that the embodiment of the connector 22 results in a 14% reduction in the length of the connector footprint, and a circuit board space savings of 20 mm (7.5%) of the motherboard area. This length and space savings is quite significant, particularly in view of the desire to provide high density component boards and to maximize efficient use of space on a computer's motherboard, as well as the volume of the computer's chassis.
The terms “comprising,” “including,” and “having,” as used in the claims and specification herein, shall be considered as indicating an open group that may include other elements not specified. The terms “a,” “an,” and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The term “one” or “single” may be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as “two,” may be used when a specific number of things is intended. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
