RFID DEVICES WITH CONTROLLED OPTICAL PROPERTIES

An RFID device includes an antenna that is formed so as to control the optical properties of the RFID device, which may include minimizing the amount of light that will be transmitted through the RFID device or allowing for the passage of a predetermined amount of light therethrough. The RFID device includes a conductive material associated with a substrate. The conductive material includes an antenna and a periphery. An RFID chip is electrically coupled to the antenna, but not to the periphery. The antenna may be defined by a cutting or etching or printing process. A gap between the antenna and the periphery may be on the order of approximately 25 μm-200 μm (if the transmission of light through the RFID device is to be minimized) or greater in at least one section (if the passage of a predetermined amount of light through the RFID device would be desirable).

FIELD OF THE DISCLOSURE

The present subject matter relates to radio frequency identification (“RFID”) devices. More particularly, the present subject matter relates to approaches to forming the antenna of an RFID device so as to control the optical properties of the RFID device.

DESCRIPTION OF RELATED ART

Devices incorporating RFID technology are widely used for a variety of applications, including vehicle security locks, access control to buildings, and inventory tracking systems in manufacturing, warehouses, in-store retail, and other operations enhanced by tracking functions.

RFID devices may have a variety of integrated components, among them an RFID chip containing data (e.g., an identification code) and an antenna electrically connected to the chip and responsible for transmitting signals to and/or receiving signals from another RFID device (e.g., an RFID reader system).

Commonly, the antenna is manufactured by patterning, etching, or printing a conductor on a substrate in a pattern that corresponds to the desired shape of the antenna. The tracks or conductive lines thereby composing the antenna will normally contain or include opaque conductive materials (such as silver, copper or aluminum), which do not allow light transmission. The substrate associated with the antenna is typically a thin, flexible material, which may be transparent or at least translucent or otherwise configured to allow for the passage of light therethrough. This sharp contrast between the opaque antenna and the light-transmissive substrate can interfere with the appearance of materials (such as fabric labels) placed in front of conventional RFID devices. This may be especially disadvantageous for articles for which the appearance of the article is critical to marketability. For example, the aesthetic appeal of articles such as apparel labels/tags having RFID inlays may be affected due to visibility of parts of the RFID inlays through the label/tag substrate. Ideally, in these applications, no RFID device structures (e.g., conductive lines crossing a label) should be visible.

One possible approach to this problem is the use of thicker, highly opaque fabric or paper as a substrate. Thicker materials, however, can be rigid resulting in discomfort to wearer of these garments. Therefore, it is desirable for the RFID device to be soft and flexible. in which case the use of thicker substrate material is not satisfactory. Moreover, while it is desirable that the parts of the RFID device such as the antenna be invisible, it is at the same time also desirable that the logo or branding of the article to which the RFID device is tagged or attached to, be visibly and aesthetically enhanced.

SUMMARY

Methods for manufacturing an RFID device with controlled optical properties are described herein. The method includes providing a conductive material on a substrate and processing the conductive material to separate an antenna from a periphery, with the periphery being retained on the substrate. The antenna is separated from the periphery through a gap, with at least a portion of the gap being formed along a perimeter of one or more branding symbols, such as a logo or other brand identifying mark, design, etc., formed on a substrate of the RFID device. In some embodiments, the RFID chip is electrically coupled to the antenna, but not to the periphery.

In some embodiments, the method is as described above, and the conductive material is processed, for example, by cutting (e.g., die cutting), laser cutting, and/or etching in order to separate an antenna from a periphery, with the periphery being retained on the substrate. In some embodiments, the method is as described above and the conductive material, e.g., the antenna, has first and second portions, which are separated from a periphery, with the periphery being retained on the substrate. In some embodiments, the method is as described above, and the RFID chip is associated with a strap substrate at least partially formed of an opaque material and configured to extend between the first and second portions of the antenna.

In some embodiments, the method is as described above and at least a portion of the gap has a width configured to allow for the passage of a predetermined amount of light therethrough, the configuration being able to depict desired shapes, logos, designs, marks, or other optical characteristics. In still other embodiments, at least a portion of the gap is formed along a perimeter of one or more branding symbols (e.g., logo or other brand identifying mark, design, etc.) formed on the substrate of the RFID device.

In still other embodiments, at least a portion of the gap is formed along a perimeter of the one or more branding symbols formed/printed in the substrate of the RFID device. In some embodiments, the method is as described as above and further includes printing a conductive material onto a substrate so as to define an antenna and a periphery. In some embodiments, an RFID chip is electrically coupled to the antenna, but not to the periphery. The printing includes creating a gap between the antenna and the periphery, with at least a portion of the gap having a width configured to allow for the passage of a predetermined amount of light therethrough, the configuration being able to depict or enhance desired shapes, logos, design, marks, or other optical characteristics.

In some embodiments, the method is as described above and further includes providing a conductive material and defining a gap in the conductive material to configure it as a substantially spiral-shaped antenna, with at least a portion of the gap being formed along a perimeter of one or more branding symbols formed on the substrate of the RFID device. RFID device includes a substrate, a conductive material associated with the substrate, and an RFID chip are also described herein. In some embodiments, the conductive material contains an antenna and a periphery, with the RFID chip being electrically coupled to the antenna, but not to the periphery.

In some embodiments, the RFID device is as described above and further include controlled optical properties. In some embodiments, the conductive material includes an antenna and a periphery separated by a gap, with the RFID chip being electrically coupled to the antenna, but not to the periphery, and with the gap having a width in the range of approximately 25 μm to 200 μm.

In some embodiments, the RFID device is as described above and the antenna has first and second portions, with the RFID chip being associated with a strap substrate at least partially formed of an opaque material and extending between the first and second portions of the antenna.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The embodiments disclosed herein are for the purpose of providing a description of the present subject matter, and it is understood that the subject matter may be embodied in various other forms and combinations not shown in detail. Therefore, specific designs and features disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims.

FIG. 1shows one embodiment of an RFID device (shown generally as10a) in accordance with an aspect of the present disclosure. In the illustrated embodiment, a conductive material12is provided on or associated with a substrate (which is not visible inFIG. 1). The conductive material12may be associated with the substrate according to any suitable approach, including (but not limited to) printing the conductive material12onto the substrate. The conductive material12may include or contain any suitable conductor, such as silver, copper, or aluminum. As for the substrate, it may be contain, include, or be composed of any suitable (preferably non-conductive) material without departing from the scope of the present disclosure.

The conductive material12may cover any portion of the substrate, but in one embodiment, is applied to an entire surface of the substrate. The portion of the substrate onto which the conductive material12is applied will have substantially uniform optical properties (i.e., that portion of the RFID device10awill be substantially opaque, due to the presence of the conductive material12). By applying the conductive material12to an entire surface of the substrate, the resulting RFID device10awill have controlled, more uniform optical properties, as will be described in greater detail. Due to the conductive material12being applied in a manner that provides the RFID device10awith more uniform optical properties, more flexibility is possible with the material composition of the conductive material12and the substrate, as described above. For example, the opacity of the substrate is not a consideration when the conductive material12is applied in a manner that is entirely controlling of the optical properties of the resulting RFID device10a.

As also shown inFIG. 1, the conductive material12is processed to define an antenna14and a periphery16, which is electrically isolated from the antenna14without being removed from the substrate. In other words, the antenna14is formed within the conductive material12without breaking the edges of the antenna14from the peripheral conductive material. In one embodiment, the antenna14and the periphery16are physically separated by one or more gaps18defined in the conductive material12, which also serves to electrically isolate the antenna14from the remainder of the conductive material12(i.e., the periphery16). It may be advantageous for the gap(s)18to pass entirely through the conductive material12without extending into the substrate (which could weaken the substrate), though it is also within the scope of the present disclosure for at least a portion of a gap18to extend into the underlying substrate. The gap(s)18could be created after the conductive material12has been applied to the substrate, such as by an etching or cutting (e.g., laser cutting or die cutting) operation. Further, in one embodiment, the gap(s)18could be continuously formed. In particular, the gap(s)18are formed along a perimeter of one or more branding symbols including logos or patterns formed on the substrate. In another embodiment, the conductive material12is printed onto the substrate in the form of the antenna14and periphery16, with the gap(s)18being formed in regions where the conductive material12is not printed.

Regardless of how the antenna14and periphery16are defined, they may be provided in any suitable configuration without departing from the scope of the present disclosure. For example, in the embodiment ofFIG. 1, the antenna14is completely surrounded by the periphery16and includes separate first and second portions20and22. In the embodiment ofFIGS. 2 and 3, the antenna14substantially encircles the periphery16. It should be understood that the configurations of the antenna14and the periphery16shown inFIGS. 1-3are merely exemplary and that other configurations may be practiced without departing from the scope of the present disclosure (e.g., an embodiment in which the antenna14substantially encircles one portion of the periphery16, while another portion of the periphery16completely surrounds the antenna14).

In one embodiment, each gap18is narrow or has a small width, which may be in the range of approximately 25 μm to 200 μm. By providing a narrow gap or gaps18, no appreciable amount of light will be transmitted through the gap(s)18. This serves to maintain the uniformity of the optical properties of RFID device10a,with the antenna14and periphery16(which is retained on the substrate) being opaque and with the gap(s)18therebetween being substantially non-transmissive of light, thus rendering the entire RFID device10a(or at least the portion thereof in which the conductive material12is present) substantially, uniformly opaque. Another advantage of a gap or gaps18having a small width is that such a configuration allows for the conductive material12to present a substantially flat surface. A conventional RFID device will include larger spaces (e.g., on the order of approximately 10 mm) defined between portions of the antenna, which presents an uneven surface that may be difficult to print upon without significant distortion. Thus, by employing a narrow gap or gaps18to separate the antenna14from the periphery16, the clarity of print applied to the RFID device10awill be improved.

While it may be advantageous in many applications for the gap(s)18to be relatively narrow, it is within the scope of the present disclosure for all or a portion of a gap18to be wide enough to allow for an appreciable or predetermined amount of light to be transmitted therethrough. As described above, the gap(s)18may be provided in any configuration without departing from the scope of the present disclosure. As such, it may be desirable to provide a gap or gaps18(or one or more portions thereof) with a greater width and a configuration in the form of a logo or other desired pattern. In such an embodiment, an appreciable or predetermined amount of light will pass through the gap(s)18to display the logo or pattern, thereby acting as a visual enhancement for the RHD device10aand an associated label or the like. For example, the gap(s)18are formed to be positioned along a perimeter of one or more branding symbols formed in the substrate. Forming gap(s)18along the perimeter of the one or more branding symbols including a logo or a pattern ensures that there is passage or transmission of sufficient light to enhance the visibility of the branding symbols, while ensuring that there is no or minimal light transmission through the antenna14. Thus, the construction of the RFID device10aenables achieving controlled optical properties. Therefore, the construction of the RHD device10aensures that there is no visual interference of parts of the RFID device such as the antenna14with the branding of the article to which the RFID device10ais secured. Additionally, the design degrees of freedom associated with the RFID device10aare also high since the gap(s)18can be customized to be formed according to the shape and size of the branding symbols and according to their relative positioning on the substrate. Alternatively, the gap(s)18can be formed along a portion of the substrate that carries additional information such as wash care or anti counterfeit details.

Regardless of the particular configuration of the antenna14, it is electrically coupled to an RFID chip24. On account of the antenna14being electrically isolated from the periphery16, the periphery16is not electrically coupled to the RFID chip24. The RFID chip24may be electrically coupled to the antenna14according to any suitable approach, which may include direct attachment of the RFID chip24to the antenna14(as inFIG. 1) or attachment of an RFID strap26to the antenna14(as inFIG. 3). Although the periphery16of the conductive material is electrically isolated from the antenna, the periphery is still a part of the antenna and contributes to the functioning of the antenna14.

When an RFID strap26is employed, a larger gap between two portions of the antenna14is required than what is needed for direct connection of an RFID chip24. For example, while an approximately 500 μm slit may be sufficient for separating two portions of the antenna14for direct connection of an RFID chip24(as inFIG. 1), a gap on the order of approximately 2 mm×2 mm may be required when using an RFID strap26. Such a larger gap28can be seen inFIGS. 2 and 3, withFIG. 2showing the underlying substrate30. If the substrate30has different optical properties than the conductive material12(namely, if the substrate30is less opaque than the conductive material12), then the RFID strap26may be provided with an associated strap substrate32(FIG. 3) configured to overlay all or portion of the gap28. The strap substrate32may be formed of a material having optical properties that are more similar to those of the conductive material12than the substrate30(e.g., a strap substrate32formed of an opaque or colored paper or polyethylene terephthalate material), thereby preserving the controlled, substantially uniform optical properties of the RFID device10b.Alternatively, if it is impracticable to provide a strap substrate32, another option would be positioning the gap28at a location where transmission of light through the substrate30will have a minimal impact on the visual properties of the RFID device.

A comparison ofFIGS. 2 and 3shows additional processing that the periphery16may undergo. In particular, the periphery16ofFIG. 3has the same perimeter as the periphery16ofFIG. 2; however, the periphery16ofFIG. 3has been separated into a plurality of portions or sections16a,16b,and16cby one or more gaps34defined in the periphery16. Separating the periphery16into multiple sections will electrically isolate the sections from each other, which may improve performance of the antenna14. The gap(s)34defined in the periphery16may be formed according to the same approach employed in defining the gap18that separates the antenna14from the periphery16or may be formed according to a different approach. It may be advantageous for the gap(s)34defined between adjacent portions of the periphery16to be relatively narrow (similar to the gap(s)18between the antenna14and the periphery16) in order to promote uniform optical properties, though it is also within the scope of the present disclosure for at least a portion of each gap34to have a greater width in order to allow for passage of a predetermined amount of light. Similar to the gap(s)18between the antenna14and the periphery16, it may be advantageous for the gap(s)34to pass entirely through the conductive material12without extending into the substrate (which could weaken the substrate), though it is also within the scope of the present disclosure for at least a portion of a gap34to extend into the underlying substrate.

A comparison ofFIGS. 2 and 3toFIG. 1shows another approach to reducing the visibility of the gap18. In the embodiment ofFIG. 1, the antenna14is defined by a gap18having a plurality of elongated, substantially linear segments or sections. In contrast, in the embodiment ofFIGS. 2 and 3, the gap18separating the antenna14and the periphery16follows a continuously changing, non-linear path. A gap may be particularly visible at elongated, substantially linear segments, such that replacing such segments with less linear segments (e.g., sinusoidal or curving segments of the type shown inFIGS. 2 and 3) may render the gap less visually distinct. It should be understood that the non-linear path of the gap18ofFIGS. 2 and 3is merely exemplary and that a gap (or one or more segments thereof) may follow a differently configured non-linear path without departing from the scope of the present disclosure.

FIG. 4shows another embodiment of an RFID device10cwith controlled optical properties according to an aspect of the present disclosure. In the embodiment ofFIG. 4, a conductive material12is provided, with one or more gaps18being defined in the conductive material12, as in the embodiments ofFIGS. 1-3. Unlike the embodiments ofFIGS. 1-3, the conductive material12is not separated into an antenna14and a periphery16, but rather the entire conductive material12serves as the antenna14. In the embodiment shown inFIG. 4, the gap(s)18define a substantially spiral-shaped antenna14, but it should be understood that the antenna14may be differently configured, i.e., different spiral or other shape, without departing from the scope of the present disclosure. For example, if desired, the configuration could take the shape of a “logo” or other desired optical characteristic. As an embodiment, thin gaps isolating the sections of the conductor to form an antenna are in the desired shape or configuration or optical characteristic. If desired, light leakage through the thin gap can enhance the visual appeal of the label.

As in the embodiments ofFIGS. 1-3, the gap(s)18may be formed according to any suitable approach and may be either relatively narrow (to minimize the amount of light transmitted therethrough and promote more uniform optical properties) or may be wider at one or more sections to allow a predetermined amount of light therethrough to provide a desired visual effect.FIG. 4illustrates a gap18defined by a plurality of segments each following a non-linear path (as inFIGS. 2 and 3), but it should be understood that an individual segment of the gap18ofFIG. 4may be differently configured without departing from the scope of the present disclosure, including one or more segments that are substantially linear, as inFIG. 1.

FIG. 4shows an RHD chip24electrically coupled to the antenna14at or adjacent to an outer perimeter of the conductive material12. It should be understood that an RFID chip24may be positioned elsewhere on the antenna14without departing from the scope of the present disclosure and that it is also contemplated that an RFID strap (e.g., of the type shown inFIG. 3) may be employed instead of an RFID chip24that is directly connected to the antenna14.

According to yet another approach to reducing the visibility of a substrate through a gap defined in a conductive material, the RFID device may further include a masking member or material having optical properties (e.g., opacity) that are more similar to that of the conductive material than the substrate. In one embodiment, the masking member may be provided as a distinct layer, which overlays all or a portion of the gap, being positioned on the same side of the substrate as the conductive material or on the opposite side of the substrate. This is comparable toFIG. 3, in which the strap substrate32overlays the gap28, with the strap substrate32having optical properties that are more similar to those of the conductive material12than the substrate30.

Rather than being entirely uniform, the masking member may have varying optical properties. This may include the masking member including a plurality of regions or sections having optical properties that are similar to those of the conductive material, with the regions or sections being arranged in pattern, which may be random or non-random. For example,FIG. 5shows a conductive material12on a substrate30, with a gap36defined in the conductive material12and with the substrate30being visible through the gap36. The size of the gap36is exaggerated or enlarged for illustrative purposes.FIG. 6shows the same conductive material12and substrate30ofFIG. 5, but with a masking member38associated with the side of the substrate30opposite the conductive material12. For illustrative purposes, the masking member38is shown as extending beyond the perimeter of the substrate30, but it should be understood that the masking member38may be coextensive with the substrate30or may be positioned entirely inwardly of the perimeter of the substrate30.

The masking member38ofFIG. 6is illustrated as being formed of a substantially transparent material (e.g., a thermoplastic urethane material), with opaque regions or sections40arranged in a checkerboard or pixelated pattern. The opaque regions or sections40have an opacity that is similar to that of the conductive material12, such that the portions of the opaque regions or sections40aligned with the gap36will reduce the visibility of the substrate30through the gap36. It should be understood that the illustrated configuration is merely exemplary and that the masking member38may be differently configured, such as by having a uniform opacity or an opacity gradient, which would serve to feather, fade, or blend the edges of the substrate30visible through the gap36.

In yet another embodiment, rather than the masking member or material being provided as a separate layer, the masking member or material may be co-planar with and received by the gap18. For example, paint or some other non-conductive masking member or material42may be at least partially positioned within the gap18to prevent light from passing through the gap18or at least reduce the amount of light that passes through the gap18, as shown inFIG. 7. This may include the entire gap18being filled with the masking member or material42or only a portion of the gap18receiving the masking member or material42. Typically, only a small amount of the masking member or material42is required to obscure the gap18(particularly if the gap18is narrow, as described above), such that the addition of the masking member or material42will not significantly diminish the flexibility of the resulting RFID device.