MXPA98010575A - Bracelet tape for the control of stai loads - Google Patents

Abstract

The present invention relates to a bracelet (10) for the control of static charges comprising a band (12) having a first polymeric, insulating layer and a second conductive layer (14) molded in one piece with the first layer , a contact means (22) for interconnecting the second layer with a conductive belt, and means for adjusting an effective length of the belt or band to accommodate the size of the limb or limb of a user. A third conductive layer (24) may be included to provide a constant verification device on the ground path. The contact means may comprise a conventional eyelet passing through a portion of the conductive layer with a quick connecting structure for connection to the belt. The insulating layer can be overmoulded on the conductive layer (14) or, where the conductive layer is also polymeric, it can be jointly molded or extruded together in a mine form or in a tubular shape, or it can be molded with insert, with the insulating layer. The belt comprises a grounding cord which may be constructed of a conductive layer surrounding a flexible reinforcing member, wherein the reinforcing member may be braided copper wire, of metallic paper wrapped around a fiber yarn. of insulating polyamide, or a fiber coated with metal. The conductive layer of the belt can be constructed with flexible elastomer loaded with a builder material, and a flexible, polymeric insulating layer can surround the conductive layer. The belt can have the shape of a spiral to eliminate the excess length, during the

Description

BRACELET TAPE FOR THE CONTROL OF STATIC LOADS FIELD OF THE INVENTION The present invention relates, in general, to devices for preventing electrostatic discharges, more particularly to a bracelet and conductive strap (grounding) for the control of static charges, where the bracelet and the strap are basically a polymeric material and are formed by molding processes to reduce the number of parts in the device.

BACKGROUND OF THE INVENTION Electrostatic discharges, as well as the mere presence of a static electric field can be extremely damaging to sensitive electronic parts (in the solid state). Modern semiconductors and integrated circuits can be degraded or destroyed by this formation of static charges. A common tool that is used to REF. : 29040 the control of the formation and discharge of static charges, is a conductive belt of connection to earth which is designed to drain the excess of electrostatic charge. A general discussion of these devices can be found in U.S. Patent Nos. 4,677,521, 5,018.44 and 5,184,274. The bracelets and straps described in the patents mentioned above have many parts that increase the cost of those devices. Although these devices have features that make them advantageous for particular uses, they are relatively expensive when considered for the most basic safety and effective grounding tasks. Smaller and less expensive webs such as those shown in U.S. Patent Nos. 3,857,397 and 4,698,724 have been designed, but these designs suffer from certain inherent limitations. For example, both of these designs are unitary bracelets / straps, which means that if the strap portion of the device is broken, the bracelet becomes unusable, or vice versa, which also means that if the user wishes to walk away from his or her station. The bracelet must be completely removed, or the strap portion must be left behind, in contrast to the designs that allow the strap to be connected to the bracelet in such a way that it can be disengaged. Both of these designs are also unsuitable for use in a dual conductor system (such as that shown in the aforementioned patent 5,018,044). Finally, the means for adjusting the effective size of the bracelet should be applied separately to the band, such as the hook and loop fastening strips described in the aforementioned Patent No. 3,857,397, or as the adhesive layer described in FIG. the aforementioned patent 4,698,724. This separate application step increases the cost of the process but it is critical that the device achieves an accurate, appropriate fit, given that it must have a good contact with the skin to be sufficiently conductive, and still not be so tight that restrict circulation or as to cause discomfort to the user. Therefore it would be desirable and advantageous to devise a durable bracelet, low cost, and having few parts or parts, which exceeds the foregoing limitations.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a bracelet for the control of static charges, which generally comprises a strip having a first polymer layer, insulating, and a second layer, conductive, molded in one piece with the first layer, a contact means for the interconnection of the second layer with a conductive belt; and means for adjusting an effective length of the strip to accommodate the size of the arm or member of a user. A dual conductor version of the bracelet can be further constructed to provide a third conductive layer also molded in one piece with the first layer, and a second electrically isolated contact means of the first contact means for interconnecting the third layer with a second conductive strap, to allow a constant verification device, on the route to ground, to indicate to the user, by means of an alarm, when the band or strap fails to provide a continuous ground connection, as described in US Pat. No. 5,057,965. The adjustment means may comprise a clasp attached to one end of the strip, or the strip for use on the wrist may be self-supporting providing an elastic strip which is a closed loop having a series of corrugations in the strip. The contact means may comprise a conventional eyelet passing through a portion of the second layer, and a snap portion for connection to the strap, or the contact means may instead simply be provided by a formed hole. in the strip for receiving a female plug of the strap, and the hole has an inner surface which is at least partially formed by the conductive layer. The wristbands can be manufactured by overmolding the insulating layer on the conductive layer, or, where the conductive layer is polymeric, they can be coextruded, or molded or can be molded with insert, together with the insulating layer. The layers can be coextruded in the form of a sheet, or they can be coextruded into a tubular member to provide the closed ring bracelet modalities. A novel cord for grounding is also provided, wherein the cord strap is constructed of a flexible reinforcing member, of a conductive layer surrounding the reinforcing member, wherein the reinforcing member may be of twisted copper wires. , or metallic paper wrapped tightly around a filament of polyamide fiber, insulator, or a metal-coated fiber. The conductive layer is constructed of a flexible elastomer loaded with a conductive filler material, and an insulating layer surrounding the conductive layer, the insulating layer also being constructed of a flexible polymer. The conductive layer, at a given end of the strap, is formed for attachment to a particular style of connector. A portion of the belt is preferably formed as a spiral to eliminate excess length during use.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be understood in the best way with reference to the accompanying drawings, wherein: Figure 1 is a perspective view, with separation of parts, of an embodiment of the bracelet for the control of static charges, of the present invention; Figure 2 is a perspective view, representing a manufacturing process for another embodiment of a wristband in accordance with the present invention; Figure 3 is a perspective view showing another manufacturing process similar to that of Figure 2 but for a dual driver mode of a wristband for the control of static charges; Figure 4 is a perspective view showing a manufacturing process for a closed ring mode of a wristband according to the present invention; Figure 5 is a perspective view showing another manufacturing process similar to that of Figure 4 but for a dual conductor mode of a closed ring bracelet; Figure 6 is a perspective view showing the layered construction of a grounding cord manufactured in accordance with the present invention; Y Figure 7 is a perspective view of the grounding cord, of Figure 6, made as a belt having connectors at each end; Figure 8 is a perspective view of an alternative adjustment means for the static load control wristband of the present invention; Y Figure 9 is a perspective view of a wrist strap for use in the bead, for static control, which can be manufactured in accordance with the present invention.

DESCRIPTION OF THE PREFERRED MODALITY Now, with reference to the Figures, and in particular with reference to Figure 1, there is represented a modality 10 of the bracelet for the control of static charges, of the present invention. The bracelet 10 is composed, in general, of a strip 12 formed of a polymeric material, flexible, electrically insulating, having an electrically conductive layer 14 molded in one piece. As discussed further below, the conductive layer 14 can be permanently bonded to the strip 12, for example, by a process of overmolding, co-molding, insert molding, or co-extrusion. Strip 12 is preferably constructed of Hytrel, a durable thermoplastic elastomer (polyether block copolymer) available in E.l. duPont de Nemours. A pigment can be added to color-code the bracelet. The conductive layer 14 can be made of a metallic material but is more preferably made of a polymeric material that has been charged with a conductive filler material to render it at least partially conductive (a surface resistivity of less than 1 x 10 ° O / square) , so that it is capable of dissipating the formation of electrostatic charges on the user of the bracelet 10. A suitable material is the Hytrel loaded with a conductive carbon powder, in an amount of 15 to 40% (basis weight) depending on the quality and size of the particles. The conductive layer 14 is placed along the strip 12 in a thickened portion 16 of the mass. An electrically conductive eyelet 18 passes through a hole formed in the conductive layer 14 and a hole 20 formed in the thickened portion 16 of the strip 12, and is fixed to a male quick connect part 22 which is used to interconnect bracelet 10 to a grounding strap. To the strip 12 can be attached structures for quick connection, of different sizes (for example 4 mm, 5 mm, 7 mm or 10 mm). A depression 23 may be provided in the thickened portion 16 of the strip 12, to receive the quick connect structure. The eyelet and the structure for quick connection can be optionally molded inside the bracelet. An optional layer 24 can be used as a conductive, hydrophilic barrier, placed on the carbon-laden layer, for applications in clean rooms. For those extreme applications, materials can be used in which there is less chance of detachment (particles or fibers) or from which some gas emanates. Many features are molded into the shape of the strip 12. To allow for the adjustment of the bracelet, studs or retention projections may be formed at one end, such as a pair of small projections 26 and a larger projection 28, which engage to the corresponding holes, respectively, formed at the other end. since this provides adjustability to discrete lengths, additional tolerance can be provided by constructing in relief features such as links that can be stretched 34. Near the projections 26 and 28 a first bar 36 is provided to retain the other end of the bar. strip 12 in place, on the projections, forming an insertion opening, and a second bar 38 is provided to retain the excess length of the strip. The other end 40 can be tapered for easy insertion below the bars 36 and 38. Other relief features can be formed along the strip, such as ridges or slots 42 to improve its flexibility and fit around the wrist of the user. There are several advantages to the previous design. In addition to providing all the basic features of a strip that is worn on the wrist, for grounding, the bracelet 10 can be adjusted so comfortably that a single size fits all wrist sizes, with a positive contact with the skin. It has a low manufacturing cost particularly when so few parts are used as 4 (the strip 12, the conductive layer 14, the eye 18 and the structure for quick connection 22). You can also change the pigment in the manufacturing process to easily select the appropriate colors. As discussed below, the bracelet 10 is manufactured relatively easily by overmolding or coextrusion processes which allow simple fabrication of the strip and the conductive layer, integrated, and the easy assembly of the addition components. Figure 2 is a perspective view representing a manufacturing process for another embodiment 44 of a wristband in accordance with the present invention. The bracelet 44 is constructed by overmolding a sheet of conductive material (loaded with carbon) on a larger sheet of the insulating polymer material, forming an integral sheet 46 from which the individual bracelets 44 can be formed. In the first In step of the process sheet 46, linear cuts can be made in the sheet to define the boundaries of the strip portion 48 of the bracelet 44, and a hole can be punched through the thickened portion of the strip. In the next assembly step, eye 50 and structure for quick connection 52 are joined. In the final step, the buckle 54 is attached to one end of the strip 48. On that end of the strip 48, indentations or indentations 56 may be formed to match the attachment characteristics of the buckle 54. That end of the strip 48 may have an anterior section 58 which is tapered to allow passage through the buckle 54, and the anterior section 58 may be cut after the buckle is secured. Figure 3 shows a similar process and design. The only difference is that the insulating layer is overmoulded on two pieces of a conductive layer, and the two pieces of the conductive layer are slightly separated so that, in the finished bracelet 60, there are two separate conductor sections 62 and 64 formed along the inner surface of the strip. Two structures for quick connection 66 and 68 are attached to the respective eyelets on the strip, so that they are in contact with the two conductor sections 62 and 64, respectively. The dual driver's bracelet 60 can then be used in conjunction with dual driver inspection systems, which are known in the art.

Figure 4 depicts a manufacturing process for another embodiment 70 of a ring or closed loop bracelet, in accordance with the present invention. As with the processes of Figures 2 and 3, the bracelet 70 is made by cutting a strip from a larger piece of material having the conductive layer as part of the same piece, with the insulating layer, but in Figure 4 The bracelet is formed from a tubular member 72 instead of from a sheet, allowing the bracelet 70 to be a closed ring that is, a buckle or other type of elements is not needed to join either end of the bracelet. strip for use on the wrist. Tubular members 72 can be formed by coextruding the conductive layer 74 with the insulating polymer material, during the coextrusion process, a hole 76 can be formed in the strip, in a thickened portion thereof, to receive a plug that is located on the end of a ground strap. The hole 76 has an interior surface that is formed, at least partially, by the conductive layer. The formation of the hole 76 in this manner further reduces the cost of the given device that provides interconnection with the belt without the need to add more parts, (i.e., the eyelet and the structure for quick connection). The bracelet 70 can be formed of an elastic material having corrugations or bends 78 in such a way that it is self-fastening, that is, that it is able to securely gather around wrists of various sizes to achieve satisfactory contact with the skin, but without providing additional components for its adjustment, such as a buckle. Instead of the corrugations 78, a series of small cross sections can be made in a section of the strip, to provide self-adjustment. Figure 5 is similar to Figure 4 but illustrates another dual conductor mode 80 of a wristband in accordance with the present invention, formed by providing separate conductive layers 82 and 84 as in the process of Figure 3. Figure 5 also illustrates that with this design the quick connect structures 86 can still be used, instead of forming the plug receiving hole 76, of Figure 4. Focusing on Figures 6 and 7, those Figures represent a novel grounding strap 90 which is it can be used in conjunction with the wristband of the present invention. The belt 90 shares some of the same design characteristics of the bracelets described above, for example, that it has a mainly polymeric construction and that it includes a conductive layer that is extruded together with an insulating layer. Specifically, the belt 90 has an outer layer 92 of an insulating polymer, such as Hytrel, and an inner layer of a conductive material, again preferably Hytrel loaded with carbon. With a load of carbon of 32%, a typical cord for connection to ground (10 feet long) made, from the belt 90 would have a resistance of approximately 2 MO. The conductive layer 94 is shown with a circular cross section but those skilled in the art will appreciate that this form is not mandatory. The layers can be extruded on top or coextruded, using a ductile filament. Near the center of the conductive layer 94 is a reinforcing member, preferably a reinforcing fiber 96 made of polyester or Keviar, an aromatic polyamide available from E.l duPont de Nemours. The reinforcing member could also be, for example, one or more solid metal wires, or metallic paper wound on a reinforcing thread, of polyester fibers or non-ex (Nomex is a polyamide also available from E.l. duPont de Nemours). Figure 7 shows how the belt 90 can be made in the form of a grounding cord having connectors at each end. In applications where a banana-style plug 98 is required or desired, that plug can be secured directly to the exposed conductive layer, at one end of the belt 90, using a pleated tube, formed on the banana plug. The banana plug can also be a molded, polymeric part. For applications where interconnection with a quick connection structure such as the quick connection structure 22 is required, the exposed conductive layer, at one end of the belt 90, can be compressed to flatten the end in order to stamp or weld with heat the polymer to the structure, metallic for fast connection 100. The end can, on the contrary, connect to a resistor and the resistor can be connected to the metal structure for fast connection. Alternatively, a female structure can be molded for quick connection, from Hytrel conductor, and teeth can be formed that grip the end of the belt. In order to give rigidity to the terminations, it is also possible to use electrically molded insulating bodies and sleeves for stress relief. Figure 7 also shows how, if the materials of the belt are elastomers, a portion 102 of the belt 90 can be wound onto a mandrel which is heated and then rapidly cooled so as to retain the shape of a spiral, to minimize the length in excess of the strap, during use. The insulating layer 92 is preferably a material with higher hardness values (which are in the range of 45 to 80 Shore D) for its durability (the durometer value of the conductive layer 94 is preferably in the range of 25). at 50 shore D). The fiber 96 preferably has a diameter of 0.008 cm (0.003 in.) To 0.004 cm (0.0015 in.), The conductive layer 94 has an outer diameter of approximately 0.18 cm (0.070 in.), And the insulating layer 92 has an outer diameter of approximately 0.24 cm (0.095 inches). Figure 8 still represents another alternative embodiment of a bracelet 104 for the control of static charges which has a different adjustment means. Specifically, an articulated buckle 106 is molded as part of a single piece, in the strip, the buckle has a slight slightly arched portion 108, and a second slightly arched portion 110 which, when the buckle is in the closed position, remains the portion 108. Between the two portions 108 and 110 a useful hinge is formed. The portion 108 has the latching fingers 114 to secure the portion I10 in place, so that it can be released. Other features such as protuberances 116 and ribs 118 can be used to help align the two portions 108 and 110, ie, corresponding holes or notches are formed in the lower portion of the portion 110. Figure 9 illustrates how it can be applied the present invention to devices for the control of static charges similar to bracelets, particularly to a strip or tape 120 for the heel. The heel strip 120 includes a portion of electrically insulating, polymeric main tape 122, which has a conductive layer 124 molded on the same piece, similar to the bracelets described above. The tape 120 for the heel is adapted, however, to be used in such a way that the conductive layer 124 is oriented downwards, i.e., that it comes into contact with the floor or, for example, with a floor plush for the floor. control of static charges. The conductive layer 124 can be molded with a non-slippery surface, such as a curled surface. The tape 120 has front overlap sections 126 and 128 that wrap around the arc portion, top, of a foot or shoe to secure the tape 120 to the wearer. Another portion 130 is wrapped around the back side of the heel.

The portion 130 is maintained in a nested configuration by another eyelet or rivet 132. The eyelet 132 is in electrical contact with a resistor 134 whose other end is attached to another eyelet 136. The eyelet 136 in turn secures another conductive strip 138 to the tape 120. The conductive strip 138 is placed inside the user's shoe so that it is physically in contact with the wearer's foot. Although the invention has been described with reference to specific embodiments this description does not purport to have been elaborated in a limiting sense. Various modifications of the described modality, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art when referring to the description of the invention. It is therefore contemplated that such modifications may be made without departing from the spirit or scope of the present invention, as defined in the appended claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (20)

1. An article for controlling electrostatic discharges, characterized in that it comprises: a strip or strip having a first insulating, polymeric layer, and a second conductive layer molded with the first layer in such a way that they form a single piece; a contact means for interconnecting the second layer with a conductive belt; means for adjusting an effective length of the tape or band to accommodate the size of the limb or limb of the user.

2. The article according to claim 1, characterized in that it further comprises: a third conductive layer also molded, forming a single piece, with the first layer; and a second contact means for interconnecting the third layer with a second conductor run.

3. The article according to claim 1, characterized in that the adjustment means comprises a buckle attached to one end of the band.

4. The article according to claim 1, characterized in that: the band is a ring or closed loop and the first polymeric layer is formed of an elastic material; the adjustment means comprises a series of corrugations or cuts in the band, in such a way that the band is au t or j u s t ab 1 e.

5. The article according to claim 1, characterized in that the contact means comprises a hole formed in the band to receive a female plug of the belt, the hole has an inner surface which is formed, at least partially, by the second layer.

6. The article according to claim 1, characterized in that the contact means comprises a conductive eyelet passing through a portion of the second layer, the eyelet has a quick connection portion, permanently attached to the eyelet, for connection to the belt.

7. A bracelet for the control of electrostatic charges, characterized in that it comprises a band having a first elastic, insulating, polymeric layer, and a second polymeric conductive layer, molded in the same piece with the first layer, the first and second layers form a closed ring and have a series of corrugations in such a way that the band is automatic, and the band also has in it a hole to receive a female plug of the belt, the hole has an inner surface that is formed, at least partially, by the second layer.

8. A process for the manufacture of a bracelet for the control of static charges, characterized in that it comprises the steps of: obtaining a first strip of polymeric, insulating material; obtain a second strip of conductive material; permanently apply the first strip to the second strip; forming a means that remains in electrical contact with the second strip, for interconnecting the second strip with a conductive belt; providing a means on the first strip, for adjusting an effective length of the first strip, to accommodate the size of a user's wrist.

9. The process according to claim 8, characterized in that the first strip is overmold on the second t ra.

10. The process according to the rei indication 8, characterized in that the second strip is polymeric and is coextruded with 1 to the first strip.

11. The process according to claim 8, characterized in that it further comprises the steps of: obtaining a third strip of a conductive material; permanently applying the first strip to the third strip, in such a way that the second and third strips are electrically isolated; and forming a second means that is in electrical contact with the third strip, to interconnect the third strip with another conductive belt.

12. The process according to claim 8, characterized in that the adjustment means is provided by attaching a buckle to one end of the first strip.

13. The process according to claim 8, characterized in that the interconnection means is achieved by forming a hole in the bracelet to receive a female plug of the strap, the hole has an inner surface that is formed, at least partially, by a second strip.

14. The process according to the rei indication 8, characterized in that the interconnection means is formed by passing a coder eye through a portion of the second strip, the eyelet has a portion for quick connection, to make the connection to the belt.

15. The process according to claim 10, characterized in that the first strip is polymeric and is co-extruded in the form of a sheet or sheet.

16. The process according to the rei indication 10, characterized in that the first strip is polymeric and is coextruded in the form of a ring or closed loop.

17. The process according to claim 12, characterized in that the end of the first strip has indentations that are coupled with the fixing characteristics that are on the buckle.

18. A cord for grounding, characterized in that it comprises: a strap having a reinforcing member, flexible, a conductive layer surrounding the reinforcing member, the conductive layer is constructed of a flexible polymer that is loaded with a conductive filler material , and an insulating layer surrounding the conductive layer, the insulating layer is constructed of a flexible polymer; a first electrical connector located at a first end of the belt and electrically connected to the conductive layer; and a second electrical connector located at a second end of the belt and electrically connected to the conductive layer.

19. The cord for ground connection, according to claim 18, characterized in that the conductive layer at a given end of the belt is formed for connection to a connector.

20. The grounding cord, according to claim 18, characterized in that the reinforcing member is electrically conductive. SUMMARY OF THE INVENTION The present invention relates to a bracelet (10) for the control of static charges comprising a band (12) having a first polymeric, insulating layer, and a second conductive layer (14) molded in one piece with the first layer , a contact means (22) for interconnecting the second layer with a conductive belt, and means for adjusting an effective length of the belt or band to accommodate the size of the limb or limb of a user. A third conductive layer (24) may be included to provide a constant verification device on the ground path. The contact means may comprise a conventional eyelet passing through a portion of the conductive layer with a quick connection structure for connection to the strap. The insulating layer can be overmold on the conductive layer (14) or, where the conductive layer is also polymeric, it can be molded together or extruded together in a sheet form or in a tubular form, or can be molded with insert, with the insulating layer. The belt comprises a grounding cord which may be constructed of a conductive layer surrounding a flexible reinforcing member, wherein the reinforcing member may be braided copper wire, metal foil wrapped around a fiber cord of insulating polyamide, or a fiber coated with metal. The conductive layer of the belt can be constructed of a flexible elastomer loaded with a conductive filler material, and a flexible, polymeric insulating layer can surround the conductive layer. The belt can be in the shape of a spiral to eliminate excess length, during use.