Patent Application
20060143907
This invention provides a novel process of embedding electronic circuits (and portions of circuits) into nonrigid materials in a manner that lends itself well to automation and mass-production. It also addresses issues of heat and moisture in the finished product. It is applicable to medical devices; gear for sporting, gaming, camping, and hunting; wearable computers and electronics; portable radio, computing, and entertainment; children's toys, robotics, and numerous military applications.
The need to embed circuits into flexible materials is well-established in many fields and there has been some related work in the past few years. All of the prior art has limitations, however. Some restrict circuits to specially prepared fabric; some require specially prepared electrical components; some focus upon the concept of embedding circuits within fabric without providing a practical process for how such a thing should be done; some are constrained to complete circuits; some cannot be practically automated or mass produced; and virtually none take into account the standard requirements (especially testing) of the electronic circuit layout industry. This disclosed process addresses all of these limitations.
This disclosed process works well with standard, off-the-shelf electrical components and ordinary non-rigid materials like fabrics and leathers. It can be used for completely new designs or to convert an existing printed circuit board (PCB) design to a stitched circuit design, and it addresses all the issues of automation making it truly practical to mass-produce electronics on nonrigid materials of arbitrary size and shape.
This invention describes a method of incorporating electronic circuits (or portions of circuits) into non-rigid materials. It is a flexible method that takes into account all the best practices of both the electronics and sewing industries. It incorporates testing throughout but does not require it at any particular stage. It addresses the needs of not just prototypes and short-runs, but also mass production and assembly lines.
Other features, advantages, and uses of the invention will occur to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings.
Referring to
Deciding upon both a circuit (or portion of circuit) and an item to contain it. In addition to new designs, anything that can be expressed electronically with a combination of PCBs can be readily converted for use with this process. The containing item can be virtually anything assembled from nonrigid materials like textiles, fabrics, leathers, synthetics, or composites.
The electronics layout must be created. This is analogous to generating a trace for a PCB, and existing PCB designs can be readily converted. This method is far more flexible than PCB design, though, and because shapes and sizes may be arbitrary it is easier to separate components to better dissipate heat and reduce cross talk. Likewise a pattern for the containing item must be laid out. These two operations may be performed in parallel and can be done using software or by hand.
Appropriate materials must be chosen for the design. Material selection includes not only the primary material to hold the electronics, but also potential decorative materials, liners, pudding, and threads (conductive and non-conductive as needed).
The electronics layout can optionally be printed upon the primary material.
A sewing method must be chosen. Hand sewing and machine sewing are most appropriate for short runs or prototypes. Embroidery is most appropriate for mass production. Each of these three options has its own diagram and will be discussed in detail later.
Once the electronics have been applied to the primary material, it is suggested that industry-standard incircuit tests and/or functional tests be performed. Failed tests result in a typical cycle of troubleshooting and fixing and retesting.
If multiple layers are required for the design, individual layers (each made in accordance with the described process) must be assembled together.
If lamination is desired, it can be applied. Lamination can provide protection for the electronic components against moisture and sweat.
Multiple layers can be individually tested and laminated as required by the overall design. Ultimately a final as-built test is suggested to verify proper operation of the electrical portion.
The last stage is the final assembly of the item containing the circuit (or portion of circuit).
There are three possible sewing methods. Each has its own advantages and disadvantages, and it is possible to utilize all three in a single design, especially if multiple layers are employed.
Referring to
It must first be decided whether conductive materials, wires, or cables are to be couched onto the primary material; or conductive threads sewn into the primary material.
If conductive material is to be couched, it can be done so via any the prior art methods of hand couching decorative material to fabric (e.g. a satin stitch).
If conductive thread is to be sewn into the primary material, traces and/or pads via a simple straight stitch, satin stitch or other similar method. A satin stitch using non-conductive thread can be applied afterwards to encapsulate the conductive thread. Note that different colored threads may be used to make the overall layout easier to understand.
The excess conductive threads should be snipped to prevent shorts.
Testing may be performed to check for open circuits or shorts resulting from the sewing process. Hand work is somewhat susceptible to both open circuits and shorts. If problems are found, the normal troubleshooting, fixing, and retesting cycle commences.
If pads were not stitched with conductive threads, staple pads must be attached for the components. Staple pads with holes are used for through-hole components, and staple pads without holes are used for surface-mount components.
The primary material may be wet to protect it from processing heat (like from soldering).
The conductive threads or wires must be connected to the pads. This can be achieved via either soldering or conductive adhesive compound.
The components must be placed onto the appropriate pads and connected via either solder or conductive adhesive compound.
A sparse satin stitch (or similar hand technique) can be used to optionally reinforce the physical connections of the components to the primary material. Straps may be used in lieu of thread.
Referring to
It must first be decided whether conductive materials, wires, or cables are to be couched onto the primary material; or conductive threads sewn into the primary material.
If conductive material is to be couched, it can be done so via any the prior art methods of machine couching decorative material to fabric (e.g. a zigzag stitch utilizing a couching foot).
If conductive thread is to be sewn into the primary material, traces and/or pads can be created using zigzag stitches. Conductive thread can be loaded into the upper thread dispenser, the bobbin, or both as needed.
The excess conductive threads should be snipped to prevent shorts.
Testing may be performed to check for open circuits or shorts resulting from the sewing process. Machine work is susceptible to both open circuits and shorts at this stage, and fixes are difficult after encapsulation has been performed. If problems are found, the normal troubleshooting, fixing, and retesting cycle commences.
A zigzag stitch with non-conductive thread in both the upper thread dispenser and bobbin may be used to fully encapsulate the conductive thread. Adhesive may be additionally applied to further isolate and protect the conductive thread.
If pads were not stitched with conductive threads, staple pads must be attached for the components. Staple pads with holes are used for through-hole components, and staple pads without holes are used for surface-mount components.
The primary material may be wet to protect it from processing heat (like from soldering).
If staple pads are being used, the conductive threads or wires must be connected to them. This can be achieved via either soldering or conductive adhesive compound.
The components must be placed onto the appropriate pads and connected via either solder or conductive adhesive compound.
The physical connections of the components to the primary material may be optionally reinforced with a zigzag stitch, free motion sewing, sparse satin stitch, or similar machine or hand technique. Straps may be used in lieu of thread.
Referring to
The electrical layout must be converted to at least one embroidery pattern encompassing the traces and pads. It may optionally be trivially converted to an additional enlarged traces pattern for automated trace encapsulation and a component areas pattern for automated physical component connection reinforcement.
The traces and pads must be embroidered onto the primary material using conductive thread.
The excess conductive threads should be snipped to prevent shorts.
Testing may be performed to check for open circuits or shorts resulting from the sewing process. Embroidery is somewhat susceptible to both open circuits and shorts at this stage, and fixes are difficult after encapsulation has been performed. If problems are found, the normal troubleshooting, fixing, and retesting cycle commences.
If an enlarged traces embroidery pattern was created, the traces can be encapsulated by embroidering this pattern using non-conductive thread.
If pads were not embroidered, staple pads must be attached for the components. Staple pads with holes are used for through-hole components, and staple pads without holes are used for surface-mount components.
The primary material may be wet to protect it from processing heat (like from soldering).
If staple pads are being used, the traces must be connected to them. This can be achieved via either soldering or conductive adhesive compound.
The components must be placed onto the appropriate pads and connected via either solder or conductive adhesive compound.
The physical connections of the components to the primary material may be optionally reinforced utilizing the component areas embroidery pattern if one was created. Otherwise they may be reinforced with a zigzag stitch, free motion sewing, sparse satin stitch, or similar machine or hand technique. Straps may be used in lieu of thread.
Many fields can benefit from this process, and the types of items that it can be applied to are almost limitless.
From the above description it is noted that the invention has the following advantages:
The process works with existing electrical components, nonrigid materials, and (often) assembly tools.
The process supports the best practices of both the electronics and sewing industries.
The process is not limited to simple circuits or any particular category of circuits.
The process is not limited to any particular category of nonrigid materials.
The process supports both new designs and straightforward conversion from existing PCB designs.
The process supports mass production.
It is to be understood, however, that while numerous advantages of this invention have been presented in the foregoing description along with details of the structure and function of the invention, that the disclosure is illustrative only, and changes may be made in detail (especially in matters of shape, size and arrangement of parts) within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
