HK1168979B - Reinforced device housing - Google Patents

Description

Reinforced equipment housing

Cross reference to related applications

This application claims priority from U.S. non-provisional application No. 12/467,998 entitled "regained device housing," filed on even 18/5 2009, which is incorporated herein by reference in its entirety.

Technical Field

Embodiments disclosed herein relate generally to housings for electronic devices and, more particularly, to housings formed of carbon fiber reinforced plastic.

Background

Many electronic devices, including portable devices, have housings made of plastic. Plastic housings tend to be relatively inexpensive and simple to manufacture, but may be brittle and may crack under relatively low stress. Other electronic devices have metal housings. Metal housings are durable but may be heavier and/or more expensive to manufacture than comparable sized plastic housings.

Some electronic devices use reinforced plastic housings. For example, some devices may have a housing formed of Carbon Fiber Reinforced Plastic (CFRP). A standard CFRP may be made of multiple layers, each layer typically having carbon fibers aligned in a plastic matrix such that the fibers all extend in substantially the same direction within the layer. Carbon fibers impart resistance and structural strength against forces applied transversely to the length of the fiber to prevent bending and breakage. CFRP materials typically have high strength-to-weight and weight-to-stiffness ratios. However, CRFPs can crack or break if they are bent or wound such that the carbon fibers bend along their length axis. More generally, the fibers in each layer of a CRFP generally resist forming steep angles (e.g., those formed at right-angled corners) that assume and/or maintain a shape having a compound curve and resist bridging transitions. More specifically, the fibers will resist sharp corners and complex curved shapes, and bridging transitions between adjacent layers, voids, and other ornamentation and structural defects. Thus, CFRP may not be a suitable material of choice for many applications, particularly those having relatively sharp corners, such as housings for electronic devices.

Disclosure of Invention

In general, the embodiments described herein take the form of a housing for an electronic device. The housing may be made of a layered CFRP material or other fiber-in-matrix type material. In an example embodiment, a spine or frame made of CFRP may support and attach to a CFRP skin (skin).

The embodiments may accommodate electronic devices or almost anything else. Due to the similar materials used to form the frame and skin, the two components can be robustly bonded to each other and have similar, if not identical, coefficients of thermal expansion. The combination of robust bonding with similar coefficients of thermal expansion may allow the embodiments to resist cracking that could damage other enclosures.

In general, the skin is formed from multiple layers of CFRP laminated to one another. The carbon fibers in each adjacent layer generally extend in different directions. This may allow the skin to bend in multiple directions without causing cracking of all layers extending through the skin, as some layers may crack but others will bend.

By tapering certain segments of the frame and forming a step pattern in adjacent portions of the skin, mechanical stress can be spread over the tapered segments rather than being transmitted from the skin to a single edge abutment (abutment) between the two components. The skin is less likely to separate from the frame under stress, since the stress is spread across a larger area rather than being concentrated in the plane defining the connection between the frame and the skin.

Drawings

FIG. 1 depicts a top perspective view of an example embodiment.

Fig. 2 depicts a perspective view of the back of the embodiment of fig. 1.

FIG. 3 is a cross-sectional view of a portion of the embodiment of FIG. 1 taken along line 3-3 in FIG. 1.

FIG. 4 depicts a top perspective view of the frame portion of the embodiment of FIG. 1.

Fig. 5 depicts a back perspective view of the frame portion shown in fig. 4.

Fig. 6 is a top plan view of a skin portion of the embodiment of fig. 1.

Figure 7 is a cross-sectional view of the skin shown in figure 6 taken along line 7-7 in figure 6.

FIG. 8 is a top plan view of a corner portion of the embodiment of FIG. 1 shown during manufacture of the embodiment.

Fig. 9 is a perspective view of the bottom of a corner of the frame shown in fig. 4.

FIG. 10 is a cross-sectional view of the embodiment taken along line 10-10 of FIG. 1.

FIG. 11 is a flow chart illustrating an example method for fabricating the embodiment shown in FIG. 1.

Detailed Description

In general, the embodiments described herein take the form of a housing for an electronic device. The housing may be made of a layered matrix in-band fiber type material (e.g., CFRP). In an example embodiment, a spine made of CFRP may support and attach to the CFRP skin.

The CFRP ridges may be a unitary frame that imparts strength and rigidity to the overall enclosure, but also constitute at least some of the corners of the frame. In some embodiments, the ridge may be rectangular. The skin layers may be formed from multiple layers of CFRP type material laminated one to the other. In some embodiments, each layer may be cut at one or more corners so as to expose at least a portion of the layer below it. Thus, the skin may have the overall shape of a cross, such that each arm of the cross may be wrapped around a different side of the above-mentioned rectangular ridge.

FIG. 1 depicts a top perspective view of an example embodiment 100, while FIG. 2 depicts a rear perspective view of the embodiment. Embodiment 100 includes a frame 105 attached to a skin 110. As mentioned above, both the frame and the skin may be formed of CFRP or another polymer material reinforced with substantially aligned fibers. An example method for fabricating embodiment 100 is discussed subsequently with respect to fig. 11, along with other possible embodiments.

In embodiments having a cross-shaped skin 110, corners of the frame 105 may be exposed. Accordingly, the corner flanges 115 may be formed as part of the frame 105 or otherwise attached thereto. These flanges generally constitute the surfaces adjacent to the skin and the exposed portions of the frame when forming embodiment 100. As can be seen by comparing fig. 1 and 2, the exposed surface of each corner flange 115 is generally larger at the front than at the rear. In other words, the skin 110 covers more of the rear face than the front face of each corner flange 115. It should be noted that alternative embodiments may have the flange front face covered more than the rear face, or have the skin cover both the front and rear faces as much. A post or wall extends between each pair of corners.

As best shown in fig. 1, 3 and 4, the frame 105 or spine is a rectangular piece having a circular outer edge and a substantially flat inner edge, wherein the circular outer edge constitutes an arcuate segment. Thus, in the cross-section shown in fig. 3, the frame 105 appears to be a portion of a circle. It should be noted that FIG. 3 is a cross-section of embodiment 100 taken along line 2-2 in FIG. 1. Skin 110 surrounds frame 105 and forms an inner lip 300 near each sidewall along the base of the embodiment. By adhering to itself and forming the inner lip 300, the skin 110 generally provides a strong bond and contributes to the overall adhesive bond between the skin and the frame.

Although the frame 105 is shown in the cross-section of fig. 2 as having a rounded outer edge and a flat inner edge, in alternative embodiments, the shape of the frame surface may vary. For example, in some embodiments, the frame may be C-shaped in cross-section, rectangular in other embodiments, and so forth. Practically speaking, the shape of the frame may vary depending on the application of the embodiment 100, space constraints, thermal distribution factors, loads on the embodiment, and the like.

Fig. 4 and 5 generally depict top and bottom perspective views of the frame 105. The frame 105 is made of a CFRP material, typically by mixing chopped carbon fibers with the same epoxy resin used to form each CFRP layer of the skin layer 110. Accordingly, in this embodiment, the composition of the frame and the skin are almost identical.

Other embodiments may be formed of different materials with fibers in the matrix. For example, materials such as fiberglass, aramid (one example of which is KEVLAR), polyethylene (including DYNEEMA and SPECTRA), polypropylene, and other reinforcing fibers may be used. Other matrix compositions may be used for the material, including any other type of thermoset material (examples of which are polyester, vinyl ester, phenolic, etc.), thermoplastics including nylon or other polyamides, polypropylene, high density polyethylene, polyetheretherketone (Peek), and others. When constructing the embodiments using thermoplastics, the ridges or frames may be injection molded using carbon filled nylon, thereby allowing skin 110 to be thermoformed from a nylon prepreg layer reinforced with carbon fibers. Additionally, in such embodiments, the frame 105 and the skin 110 may be attached to one another using only heat; pressure may not be required. Accordingly, it should be understood that any of the materials mentioned above may be used alone or in combination in place of the CFRP in the described embodiments. Thus, references herein to "CFRP" should be understood to be provided only as an example of the above materials and combinations.

The frame 105 includes a plurality of walls 405, each having a maximum height in the middle and tapering toward the corners of the frame. Tapered segments 400 are defined on each wall at each corner. Tapered segments 400 (also shown as elements 805 and 810 in FIG. 8) generally extend from the edge of corner flange 115 to the beginning of the corner radius. Fig. 8 is an enlarged view of a portion of the frame 105 shown in the dashed box of fig. 4.

Corner flanges 115 provide reinforcement against stress and shock at each corner. By extending the flanges outward from the corners, stresses due to impacts to the corners may be distributed across a larger area, thereby reducing the likelihood of the frame cracking when the corners impact the surface. Additionally, spreading such stresses along a larger surface (e.g., a flange) may reduce the impact or vibration transmitted to the electronic components housed in embodiment 100, thereby reducing the likelihood of equipment failure.

Turning to fig. 6 and 7, the skin 110 will now be discussed. As discussed in fig. 6 and 7, the skin layer 110 may be formed from a plurality of individual layers 600, 605, 610, 615, 620, 625, 630, 635 stacked one on top of the other or stacked alongside one another. Although skin 110 is shown with eight layers, it should be appreciated that other embodiments may employ more or fewer layers.

Each layer 600, 605.. 635 is a single sheet of CFRP. In this embodiment, adjacent layers are oriented such that the fibers of adjacent layers do not extend in the same direction. For example, the fibers in layer 600 may extend from the top to the bottom of fig. 6, while the fibers in layer 605 are offset by a 45 degree angle, while the fibers in layer 610 extend from left to right with respect to fig. 6. Although a 45 or 90 degree offset is often used, the exact offset between fibers in adjacent layers can vary. The layers may be bonded to each other by any of a variety of means, including chemical adhesives, heat sealing (thermoforming), ultrasonic bonding, chemical reaction between layers, and the like. Generally, the impregnated layers forming the skin layer 110 are co-cured to attach adjacent layers.

As best shown in fig. 6, each layer 600, 605.. 635 is undercut at the corners with respect to the layers below it, such that the edges of the uppermost layer are cut to have the deepest corners (e.g., the corners closest to the centerline of skin 110). Although the skins are shown with the corners of each layer undercut along both the horizontal and vertical axes, in alternative embodiments, such undercutting may occur along only one of the two axes. In still other embodiments, only certain corners or none of the corners may be undercut. It should be noted that in order to resist separation of the skin layer 110 into constituent parts, each layer is bonded to an adjacent layer.

Fig. 7 shows the various layers 600, 605.. 635 of skin layer 110 from an end view, specifically along line 7-7 of fig. 6. When viewed from this perspective, it can be seen that the layers 600, 605.. 635, when taken as a whole, form a stepped pattern. Such undercut patterns generally interact with corner portions of the frame 105 to impart additional resistance to the skin 110 from tearing, breaking or peeling from the frame, as will now be discussed with reference to fig. 7 and 8.

FIG. 8 depicts a portion of the frame 105 during manufacture of the embodiment, specifically a corner 800 having a first tapered portion 805 and a second tapered portion 810. Tapered portions 805, 810 engage each other via corner flange 815. In the view of fig. 8, the skin 110 has not yet been attached to the frame 105, but it has been properly aligned for attachment. In this way, the part of the frame under the skin can be seen. Fig. 9 is a perspective view of the bottom of corner 800, also showing corner flange 815.

The tapered portions 805, 810 generally narrow along the transition from the corner 800 to the straight mandrel segments 820, 825 of the frame 105. Both the mandrel portion and the tapered portion are solid in cross-section, but alternative embodiments may be hollow. In general, the thickness of the tapered portion at the edge of the corner 800 is equal to the thickness of the mandrel segment plus the thickness of all layers of the skin layer 110, as the skin layer is wrapped circumferentially around the mandrel segment. That is, when the embodiment 100 is fully assembled, there is little or no significant change in the thickness of any of the sidewalls because the added dimension of the skin 110 compensates for the difference between the thicknesses of the corner 800, tapered portions 805, 810, and mandrel segments 820, 825. In addition, the individual layers 600, 605.. 635 of the skin layer 110 constitute a stepped pattern that generally compensates for the thinning/tapering of the tapered portion. A portion of corner flange 815 is covered by the skin when the skin is wrapped around the frame. In general, corner flange 815 extends between the two tapered portions 805, 810 of each corner.

Fig. 10 illustrates in cross-section an example of skin 110 wrapped around a length of frame 105. In particular, fig. 10 illustrates the relationship between the stepped undercut layers 600, 605.. 630 of the skin and the tapered portion 810 and mandrel portion 825 of the frame. FIG. 10 is a cross-sectional view of the embodiment taken along line 10-10 of FIG. 1.

As can be seen in fig. 10, the overall height of the embodiment 100 is substantially constant, except that the frame 105 has a gradually increasing thickness as it extends toward the middle of each spindle portion 820, 825. The respective layers 600, 605.. 630 of the skin 110 compensate for the reduced height/cross-section of the tapered segment 810 and the mandrel portion 825. As the size of the tapered segments 810 decreases, the additional layers add thickness and/or height to the overall shape of the embodiment. It should be noted that some embodiments may gradually reduce the size of the tapered segment 810 rather than providing it with relatively smooth, tapered sidewalls. In such an embodiment, the length of each "step" or portion of the tapered segment may be approximately the distance of the corresponding offset between adjacent layers of the skin 110. Thus, when the skin is wrapped around the frame during manufacturing (as described below with respect to fig. 11), each ply is adjacent to one step formed about the circumference of the tapered portion 810.

In addition to providing a uniform transition between corner 800 and mandrel portion 825, the stepped portion formed by the offset layer of skin 110 may also serve to enhance the bond between the skin and frame 105. By gradually spreading the transitions and edges of each layer 600, 605.. 630 across the tapered portion 810, the stresses placed on the embodiment 100 may be spread across the tapered portion rather than concentrated to the connection point between the skin and the frame. Accordingly, the stepped configuration of the skin in combination with the tapered portion of the frame may reduce the likelihood of cracking or separation of the skin from the frame due to mechanical and/or thermal stresses.

It should be noted that other embodiments may reverse the location of the mandrel portion 825 and the tapered portion 810, and form a step pattern in the skin 110 at the middle portion of the skin edge, rather than at the corners.

Fig. 11 is a flow chart illustrating an example method for forming embodiment 100 or a similar embodiment. It should be understood that certain operations may be performed in an order other than those illustrated herein. For example, the skin 110 may be created prior to compression molding the frame 105. Accordingly, variations of this exemplary method will be readily apparent to those of ordinary skill in the art. Such variations are contemplated and included in this document. Additionally, the order of operations shown herein is for convenience only and should not be construed as requiring any particular order for fabrication.

In operation 1100, the mold frame 105 is compressed. Generally, the frame is formed in two or three molds. The mixture (typically a powder, granular mixture or heterogeneous combination of epoxy resin and chopped carbon fibers) is placed into a mold matrix. It should be noted that this epoxy/carbon fiber mixture is also similar, if not identical, to the composition of skin layer 110. The same or similar epoxy resin is used in both elements and each has carbon fibers suspended therein. The top plate of the mold is lowered into the mold base and the powder is distributed into the empty space formed by the top plate and the mold base. In general, this empty area assumes the shape of the final finished frame 105.

The mold is heated while the powder is compressed with the mold. As the mixture heats up, the epoxy melts and flows to fill the void, thereby distributing the chopped carbon fibers throughout the space. When the epoxy cools, it hardens into a matrix surrounding the carbon fibers. After the epoxy is set, the frame 105 is formed and may be removed from the mold (or, in the case where the same mold is used in operations 1120-1135, may remain there).

In operation 1105, each layer 600, 605.. 630 of the skin layer 110 is cut. In particular, a stair-step configuration resulting from the layer combination is cut into each layer. In operation 1110, the layers are placed one on top of the other and bonded to each other. This bonding may occur only in the middle of the layers, leaving a non-stick release paper covering the step arrangement. It should be noted that certain embodiments may combine the layers to form the skin layer 110 and then cut away portions of the individual layers to form the stepped configuration mentioned above.

In operation 1115, the skin layer 110 is placed into a mold for producing a final form of the embodiment. That is, the mold attaches skin 110 to frame 105. In operation 1120, after the non-stick release paper is removed, an adhesive (typically a thin film adhesive) is applied to the exterior of the frame 105 and/or to those portions of the skin layer 110 that will contact the frame during the molding process. Once the adhesive is applied, the frame may be placed in a mold over the skin in operation 1125. In the case where the skin and the frame are to be bonded to each other by thermal welding, ultrasonic welding, or the like, the adhesive may be omitted or operation 1120 may be skipped.

Both of these pieces are placed in a mold and the edges of the skin 110 may be wrapped around or over the frame 105. In general, this is done in such a way that the step parts of the skin are aligned with the tapered segments of the frame. When the parts are properly aligned, the mold can be closed and a draft (draft) applied to the skin and frame. The draft angle generally holds the parts in place as the mold is closed, heated, and pressurized, and allows the mold to develop horizontal and vertical pressure as it is closed. The skin and frame are cured and bonded to each other under sufficient heat and pressure, where the precise amount of heat and pressure may vary with the composition of the CFRP, the dimensions of the skin and/or frame, etc. It should be noted that determination of appropriate heat and/or pressure is within the understanding of one of ordinary skill in the art. Generally, when the mold is closed, skin 110 wraps around the outside of frame 105, extending along the inner edge of the frame and covering a portion of itself. This covering of the skin on itself forms an inner lip 300, best shown in fig. 3, and facilitates creating a strong bond that surrounds the frame and locks it in place with respect to the skin.

Because the skin 110 and the frame 105 are made of similar, if not identical, compositions, the components are relatively efficiently and securely bonded to each other. In essence, the embodiment 100 becomes a unitary or nearly unitary structure due to the similarity of the materials comprising the frame and spine. In addition, because the skin and frame are made of similar or identical materials, the coefficients of thermal expansion of the two elements are matched or nearly matched. Accordingly, the thermal load creates only minimal stress at the interface between the skin and the frame, and thus cracking or separation of the frame and/or skin may be reduced.

After curing, the embodiment 100 may be removed from the mold.

The embodiments may accommodate any number of electronic components. For example, certain embodiments may be used to form the exterior surface of a mobile phone, a laptop or notebook computer, a tablet computing device, a desktop computer, a television, a stereo receiver, or virtually any other electronic device. The embodiments may form substantially all or only a portion of an electronic enclosure, such as a back shell and sidewalls. Alternative embodiments may not be electronic device housings at all, but may form any number of objects, typically made of metal or plastic. For example, certain embodiments may be formed as described herein to create a service utensil or vessel. Other embodiments may create a box or storage container.

It should be noted that a wide variety of objects may be formed according to the methods and embodiments described herein. For example, a fibrous frame within a matrix and a fibrous cover within a matrix may be used to form a golf club head. A three-dimensional frame in the shape of a club head may be formed as described above, with the skin wrapped around and attached to the frame. A single cover may be used, or multiple covers may form the exterior of the club head (e.g., one cover for each side of the head). Also, in some embodiments, more than one frame may be employed. Continuing with the golf club head example, two frames, one above and one below, may be formed and then connected to each other prior to applying the cover. Alternative embodiments may take the form of: turbine blades (e.g., for windmills or turbines); a propeller; wing, or tail structures; bicycle parts such as crank arms and seat posts; a container; skis and snowboards; and so on.

It should be noted that complex, closed three-dimensional shapes can be produced using the embodiments disclosed herein; it is not necessary that any portion of the resulting shape be open or exposed. Thus, the frame may be shaped such that one segment of the frame extends along the X-axis of the object to be formed, a second segment extends along the Y-axis of the object, and a third segment extends along the Z-axis of the object. For example, a square box may have a frame extending along three separate axes from each corner of the box. In other embodiments, the frame segments may define three or more unique planes extending between each set of two segments, thereby defining a three-dimensional structure or portion of the structure.

The foregoing has generally been described with respect to specific embodiments and methods of manufacture. It will be apparent to those skilled in the art that certain modifications may be made without departing from the spirit or scope of the disclosure. For example, fibers other than carbon may be used as a strengthening or stiffening element. As an example, some metal may be used instead, or another type of plastic may be used. Accordingly, the proper scope of the present disclosure is set forth in the following claims.

Claims (15)

1. A housing, comprising:

a frame formed from a first material, and defining:

a corner segment;

a mandrel segment; and

a tapered segment connecting the corner segment and the mandrel segment; and

a cross-shaped skin formed from the first material separately from the frame and bonded to the frame;

wherein:

the cruciform skin is formed from a plurality of layers of the first material, the plurality of layers being adjacent to the tapered segment;

the first material is a composite of at least fibers and a matrix suspending the fibers;

the outer edge of each of the plurality of layers forms at least one step pattern;

a portion of the cross-shaped skin overlies a mandrel segment of the frame; and

the thickness of the tapered segment at the corner segment edges is equal to the thickness of the mandrel segment plus the thickness of all layers of the cruciform skin.

2. The enclosure of claim 1, wherein said first material is carbon fiber reinforced plastic.

3. The enclosure of claim 1, wherein:

the frame is solid in cross-section; and

at least a portion of each of the plurality of layers is positioned adjacent to a particular portion of the tapered segment.

4. The housing of claim 1, wherein at least a portion of the step pattern surrounds at least a portion of the tapered segment.

5. The enclosure of claim 1, wherein:

the frame defining at least one corner flange extending from at least one corner; and

a portion of the cross-shaped skin overlies a portion of the corner flange.

6. A method of manufacturing an object, comprising:

forming a frame from a material with fibers in a matrix, the frame defining:

a corner segment;

a mandrel segment; and

a tapered segment connecting the corner segment and the mandrel segment; and

forming a cruciform skin from at least a first layer and a second layer of said matrix fiber-bearing material, the forming of the cruciform skin comprising:

cutting the first layer into a first cross shape;

cutting said second layer into a second cross shape; and

bonding the first layer to the second layer such that the second cross shape exposes a portion of the first cross shape, thereby creating a step pattern on the cross-shaped skin layer;

wrapping at least a portion of the cruciform skin about at least a portion of the frame;

wrapping a step pattern on the cross-shaped skin about the progressively subdivided segments; and

bonding the cross-shaped skin to the frame.

7. The method of claim 6, wherein:

the first layer comprises a first plurality of fibers substantially aligned in a matrix;

the second layer comprises a second plurality of fibers substantially aligned in a matrix;

the first plurality of fibers extends along a first axis; and

the second plurality of fibers extends along a second axis different from the first axis.

8. The method of claim 7, wherein the fiber-in-matrix material is carbon fiber reinforced plastic.

9. The method of claim 7, further comprising removing at least a portion of the second layer prior to wrapping the at least a portion of the cross-shaped skin about the at least a portion of the frame.

10. The method of claim 7, wherein forming the frame from the fiber-in-matrix material comprises:

placing a pelletized fiber-in-matrix material in a mold, the pelletized fiber-in-matrix material comprising fibers and a matrix;

closing the mold;

heating the mold until the matrix melts; and

curing the matrix about the fibers to form the frame.

11. The method of claim 6, wherein:

the frame defining at least a first edge, a second edge, and a third edge of a three-dimensional object;

the first and second edges defining a first plane extending therebetween;

the second and third edges defining a second plane extending therebetween;

the first and third edges define a third plane extending therebetween; and

the first, second and third planes are non-parallel or overlap.

12. An object, comprising:

a frame, comprising:

four tapered corners; and

four struts, each strut extending between two tapered corners, thereby forming a rectangular shape; and

a cruciform skin comprising a plurality of layers, each of said plurality of layers having a smaller surface area than the layers below it, thereby constituting a stair-step pattern, said cruciform skin being at least partially adjacent to and bonded to at least a segment of said frame, said frame defining:

a corner segment;

a mandrel segment; and

a tapered segment connecting the corner segment and the mandrel segment;

wherein:

the cross-shaped surface layer surrounds the four pillars;

the four corners are exposed; and

the frame and the cross-shaped skin are formed from a material with fibers in a matrix; and

the thickness of the tapered segment at the corner segment edges is equal to the thickness of the mandrel segment plus the thickness of all layers of the cruciform skin.

13. The object according to claim 12, wherein the cross-shaped skin constitutes a bottom surface of the object.

14. The object of claim 13, wherein the frame and the cross-shaped skin are separately formed from a fibrous material within the matrix.

15. The object of claim 14, wherein each of the four corners comprises an inwardly extending flange substantially parallel to the bottom surface.