JP2000513262A - Electrostatic control wrist strap - Google Patents

Abstract

Abstract: An electrostatic control wristband (10) includes a strap (12) having a first polymer insulating layer and a second conductive layer (14) integrally formed with the first insulating layer. Contact means for interconnecting the second layer to the conductive tether, and means for adjusting the effective length of the strap to accommodate the size of the user's limb. I do. A third conductive layer (24) may be included to provide a constant monitoring device on the ground path. The contact means may comprise a conventional eyelet through a portion of the conductive layer with snaps for connecting to the tether. The insulating layer may be overlaid and formed on the conductive layer (14), or if the conductive layer is also a polymer, it may be co-extruded or co-molded into a sheet or tube, or may be formed by insertion molding of the insulating layer. Good. The tether comprises a grounding cord, which may be manufactured from a conductive layer surrounding the flexible reinforcing member, while the reinforcing member is a strand copper wire or a foil wound around an insulated polyamide fiber yarn It may be a tinsel or a metal-coated fiber. The tethered conductive layer may be made from a flexible elastomer with a conductive filler added, and a flexible polymer insulating layer may surround the conductive layer. Tethers may be formed in the coil to remove excess length during use.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates generally to devices for preventing electrostatic discharge, and more particularly to electrostatic control wristbands and conductive (ground) tethers, wherein the wristbands and tethers are primarily polymeric and the components of the device It is formed from a molding process that reduces the number. 2. 2. Description of the Prior Art The mere presence of an electrostatic discharge and electrostatic field can also be very detrimental to sensitive electronic (solid state) components. Modern semiconductors and integrated circuits can be degraded or destroyed by such electrostatic accumulation. One common tool used to control electrostatic discharge and accumulation is the conductive ground tether, which is designed to discharge excess electrostatic charge. A general discussion of such devices can be found in U.S. Patent Nos. 4,677,521, 5,018,044 and 5,184,274. The wristbands and tethers disclosed in the above-mentioned patents have many components that add to the cost of the device. These devices have features that are advantageous for certain uses, but are relatively expensive considering the most basic task of safe and effective grounding. Although less expensive and simpler bands have been designed, such as those shown in U.S. Pat. Nos. 3,857,397 and 4,698,724, these designs have certain inherent limitations. is there. For example, both of these designs are a single wristband / tether, meaning that if the tether portion of the device breaks, the wristband will be unusable, or vice versa, and the user will have to move away from his workstation When walking, the wristband must be completely removed or the tether portion must be hung, in contrast to designs where the tether is removably connected to the wristband. Neither of these designs is suitable for use in dual conductive systems (eg, as shown in the '044 patent). Consequently, means for adjusting the effective size of the wristband, such as, for example, the hook and loop fastening strip of the '397 patent or the adhesive layer of the' 724 patent, must be individually added to the band. . Although this separate addition step increases processing costs, the equipment is adequate because it makes good contact with the skin so that it is sufficiently conductive, and it is not tight enough to prevent it from turning and is otherwise unpleasant. It is important that accurate adjustments can be achieved. Therefore, it is desirable and advantageous to devise a durable, low cost, and low component count wristband that overcomes the aforementioned limitations. SUMMARY OF THE INVENTION The present invention is directed to a strap having a first polymer insulating layer and a second conductive layer integrally formed with the first insulating layer, and for interconnecting the second layer to a conductive tether. And a means for adjusting the effective length of the strap to accommodate the size of the user's limb. The double conductive plate of the wristband includes a third conductive layer integrally formed with the first layer, and a third conductive layer electrically connecting the third layer to the first conductive means. Interconnected to the chain, a constant monitoring device on the ground path alerts the wearer when the band or tether cannot provide continuous ground, as taught in US Pat. No. 5,057,965. And second contact means for enabling signaling. The adjustment means may comprise a clasp attached to the strap, or the wrist strap may be self-adjusting by providing the strap with a resilient strap which is a closed loop with a series of corrugations. The contact means may comprise a conventional eyelet passing through a portion of the second layer and a snap for connection to a tether, or the contact means may instead be attached to a strap to receive a tether jack. It is only necessary to provide a formed hole, which has an inner surface at least partially formed by the conductive layer. The wristband may be manufactured by molding the insulating layer overlying the conductive layer or, if the conductive layer is a polymer, co-extrusion, co-molding or insert molding with the insulating layer. The layers are either coextruded into sheets or coextruded into a tubular member, providing a closed loop wristband embodiment. A new grounding cord is also provided, in which the tether of the cord is made of a flexible stiffener, a conductive layer surrounds the stiffener, and the stiffener is wrapped around strand copper wire, or insulated polyamide fiber yarn. May be a foil tinsel wound on a metal or a metal coated fiber. The conductive layer may be made of a flexible elastomer to which a conductive filler has been added, and the insulating layer surrounds the conductive layer, and the insulating layer is also made of a flexible polymer. Conductive layers at certain ends of the tether are formed for attachment to a particular connector style. The tether portion is preferably formed in the coil to remove excess length during use. BRIEF DESCRIPTION OF THE DRAWINGS The invention is best understood by referring to the accompanying drawings. FIG. 1 is an exploded perspective view of one embodiment of the electrostatic control wristband of the present invention. FIG. 2 is a perspective view showing a manufacturing process of another embodiment of the wristband of the present invention. FIG. 3 is a perspective view, similar to FIG. 2, showing another manufacturing process for a dual conductive embodiment of an electrostatic control wristband. FIG. 4 is a perspective view showing a manufacturing process for a closed loop embodiment of the wristband of the present invention. FIG. 5 is a perspective view, similar to FIG. 4, showing another manufacturing process for a double-conductive embodiment of a closed loop wristband. FIG. 6 is a perspective view showing a layer structure of a ground cord manufactured according to the present invention. FIG. 7 is a perspective view of the grounding cord of FIG. 6 formed into a tether having connectors at both ends. FIG. 8 is a perspective view of an alternative adjustment means for an electrostatic control wristband of the present invention. FIG. 9 is a perspective view of an electrostatic control heel strap manufactured according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, and in particular to FIG. 1, there is shown an electrostatic control wristband embodiment 10 of the present invention. The wristband 10 generally comprises a strap 12 formed from an electrically insulating flexible polymeric material with an integrally formed electrically conductive layer 14. As discussed further below, the conductive layer 14 may be permanently attached to the strap 12, for example, by overmolding, co-molding, insert molding or co-extrusion. The strap 12 is preferably made from Hytrel, a durable thermoplastic elastomer (polyether-ester block copolymer) sold by EIduPont de Nemours. Pigments may be added to color the wristband. The conductive layer 14 may be a metal material, but is at least partially conductive (less than 1 × 10 ⁶ Ω / sq) so as to be able to dissipate static electricity accumulated on the wearer of the wristband 10. (Surface resistance) A polymer material to which a conductive filler is added is more preferable. A suitable material is Hytrel with 15-40% (by weight) of conductive carbon powder added, depending on the quality and size of the particles. A conductive layer 14 is placed on the thickened portion 16 along the strap 12. An electrically conductive eyelet 18 is used to interconnect wristband 10 to a ground tether through holes formed in conductive layer 14 and holes 20 formed in thickened portion 16 of strap 12. Attached to the male snap part. Different sized snaps (eg, 4 mm, 5 mm, 7 mm or 10 mm) can be attached to the strap 12. A recess 23 may be provided in the thickened portion 16 of the strap 12 to receive a snap. The eyelets and snaps may optionally be molded into the wrist strap. An optional layer 24 may be placed on top of the carbon loaded layer and used as a conductive hydrophilic barrier for clean room applications. For such high performance applications, materials that are less likely to discard (particles or fibers) or release gas may be used. Several features are molded in the shape of the strap 12. To allow adjustment of the wristband, for example, a pair of holding pins or studs, such as a small stud 26 and a large stud 28, may be formed at one end, with corresponding holes 30, 32 formed at the other end, respectively. Engage. This may provide adjustability in discrete lengths, so additional tolerances may be provided by making relief features such as extendable links 34. A first rail 36 is provided near the studs 26, 28 to hold the other end of the strap 12 in place on the stud and to form an insertion opening, and a second rail 38 is provided for the excess length of the strap. It is provided in order to maintain the height. The other end 40 may be tapered for easy insertion under the rails 36,38. Other relief features, such as ribs or grooves 42, may be formed along the strap to improve its flexibility and comfort around the user's wrist. The above design has several advantages. In addition to providing all the basic characteristics of a grounded wrist strap, wristband 10 is comfortably adjustable so that one size fits everyone with positive skin contact. Manufacturing costs are low, especially when only four parts (strap 12, conductive layer 14, eyelet 18 and snap 22) are used. An appropriate color can be easily selected by changing the pigment during the manufacturing process. As discussed below, the wristband 10 can be relatively easily manufactured by over-molding or co-molding in an alternative manner, thereby easily manufacturing the integral strap and conductive layer. Elements can be assembled immediately. FIG. 2 is a perspective view of a manufacturing process of another embodiment 44 of the wristband of the present invention. The wristbands 44 are formed by overlaying a sheet of conductive (carbon added) material over a large sheet of insulating polymer material to form a unitary sheet 46 and forming individual wristbands 44 from the unitary sheet. Manufactured. In a first step in processing the sheet 46, the lines of the sheet are cut to define the boundaries of the strap portion 48 of the wristband 44 and holes are cut through the thickened portion of the strap. In the next assembly step, the eyelets 50 and snaps 52 are installed. In a final step, the clasp 54 is attached to one end of the strap 48. A groove or recess 56 may be formed at that end of the strap 48 to match the mounting feature of the clasp 54. The end of the strap 48 may have a lead 58 that tapers and can pass through the clasp 54, and the lead is disconnected after the clasp is attached. A similar process and design is shown in FIG. The only difference is that the insulating layer is overlaid and molded over the two pieces of conductive layer, and the two pieces of conductive layer are slightly separated so that the finished wristband 60 has There are two separate conductive portions 62, 64 formed. Two snaps 66, 68 are attached to respective eyelets on the strap and contact two conductive portions 62, 64, respectively. The dual conductivity wristband 60 can then be used with a dual conductivity monitoring system, as is known in the art. FIG. 4 illustrates the manufacturing process of another embodiment 70 of the closed loop wristband according to the present invention. Similar to the process of FIGS. 2 and 3, wristband 70 is formed by separating the strap from a large piece of material having a conductive layer already formed integrally with the insulating layer, whereas in FIG. Formed from a tubular member 72 rather than from the outside, the wristband 70 can be a closed loop, ie, no clasp or other element is required to attach to either end of the wrist strap. Tubular member 72 may be formed by co-extruding conductive layer 74 with an insulating polymer material. During the extrusion process, a hole 76 for receiving a plug at the end of the ground tether may be formed in the thickened portion of the strap. The hole 76 has an inner surface at least partially formed by the conductive layer. When holes 76 are formed in this manner, the cost of the device can be further reduced by interconnecting to the tether without adding any parts (eg, eyelets and snaps). The wristband 70 may be formed from an elastic material with bends or corrugations 78 so that it can self-adjust, ie, can be firmly recessed around various sized wrists to achieve satisfactory skin contact However, it does not provide additional coordinating elements such as clasps. Instead of corrugations 78, a series of small lateral cuts may be made at the strap to provide automatic adjustment. FIG. 5 is similar to FIG. 4, but shows another dual conductive embodiment 80 of the wristband of the present invention, by providing separate conductive layers 82, 84, similar to the process of FIG. It is formed. FIG. 5 also shows that instead of forming the hole 76 for receiving the plug of FIG. 4, the snap 86 can still be used in this design. Turning to FIGS. 6 and 7, these figures show a novel ground tether 90 that can be used with the wristband of the present invention. Tether 90 shares the same design characteristics as the wristband described above, ie, has a predominantly polymeric structure and includes a conductive layer coextruded with an insulating layer. Specifically, the tether 90 again has an outer layer 92 of an insulating polymer such as Hytrel and an inner layer 94 of a conductive material, preferably Hytrel, again doped with carbon. With 32% carbon added, a typical ground cord (length 10 ') formed from tether 90 has a resistance of about 2 MΩ. Although conductive layer 94 is shown in a circular cross-sectional view, those skilled in the art will recognize that this shape is not required. The layers are over-extruded or co-extruded using tensile filaments. Near the conductive layer 94 is a reinforcing member, preferably a reinforcing fiber 96 made of polyester or Kevlar, an aromatic polyamide sold by EIduPont de Nemours. The reinforcement member may be, for example, one or more solid metal wires or tinsel foil wrapped on a reinforced strand made of polyester or Nomex fiber (Nomex is also a polyamide sold by EIduPont de Nemours). FIG. 7 shows how a tether 90 is formed in a ground cord having a connector at each end. In applications where a banana-type plug 98 is required or desired, such a plug may be attached directly to the conductive layer exposed at one end of the tether 90 using a crimp tube formed on the banana plug. The banana plug is a polymer and may be a molded part. For those applications requiring interconnection with a snap, such as snap 22, the conductive layer exposed at one end of tether 90 may be swaged to hot stamp or weld the polymer to metal snap 100. The end may be flattened. The ends are alternatively connected to a resistor, which may be connected to a metal snap. Alternatively, the female snap may be molded from conductive Hytrel and formed with prongs that grip the ends of the tether. Additional terminations may be provided with overmolded insulation and strain relief boots. FIG. 7 shows how portion 102 of tether 90 is coiled around a mandrel when the tether material is an elastomer, the mandrel being heated and then rapidly cooled to recall its memory. Set in shape to minimize excess length of tether during use. The insulating layer 92 is preferably made of a material having a high durometer (within a range of 45 to 80 Shore D) for durability (the durometer of the conductive layer 94 is preferably within a range of 25 to 50 Shore D). . The fibers 96 preferably have a diameter of 0.003 ″ to 0.015 ″, and the outer diameter of the conductive layer 94 is about 0.5 mm. 070 ", and the outer diameter of the insulating layer 92 is preferably about 0.095". FIG. 8 shows yet another alternative embodiment of an electrostatic control wristband 104 having different adjustment means. Specifically, hinged clasp 106 is integrally molded to the strap, with the clasp having a first slightly arcuate portion 108 and a second slightly arcuate portion 110, and a second slightly arcuate portion. Portion 110 overlaps portion 108 when the clasp is in the closed position. A living hinge 112 is formed between the two portions 108 and 110. Portion 108 has latch fingers 114 to releasably secure portion 110 in place. Other features such as ridges 116 and ridges 118 may be used to help align the two portions 108, 110, ie, there are corresponding holes or notches formed in the lower surface of portion 110. FIG. 9 shows how the present invention is applied to an electrostatic control device similar to a wristband, in particular to a heel strap 120. The heel strap 120, like the wristband described above, includes a main strap portion 122 of an electrically insulative polymer and includes an integrally formed conductive layer 124. However, the heel strap 120 wears when the conductive layer 124 faces down, ie, when it contacts the ground or, for example, an electrostatic control floor mat. The conductive layer 124 can be molded with a non-skid surface, such as a knurled surface. The strap 120 has frontal overlapping portions 126, 128 that wrap around the top arch of the foot or shoe and secure the strap 120 to the wearer. Another portion 130 covers around the back of the heel. The eyelet 132 makes electrical contact with the resistor 134, and the other end of the resistor 134 is attached to another eyelet 136. Eyelet 136 then secures another conductive strip 138 to strap 120. The conductive strip 138 is pressed into the wearer's shoe and makes physical contact with the wearer's foot. Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, and alternative embodiments of the invention, will be apparent to persons skilled in the art upon reading the description of the invention. It is therefore contemplated that such modifications may be made without departing from the spirit or scope of the invention as defined in the appended claims.

────────────────────────────────────────────────── ─── [Continuation of summary] The flexible polymer insulating layer surrounds the conductive layer Is also good. The tether is formed on the coil and The surplus length may be removed.

Claims (1)

[Claims]   1. An article for controlling electrostatic discharge,   A first polymer insulating layer and a second conductive layer formed integrally with the first polymer insulating layer; Straps   Contact means for interconnecting the second layer to a conductive tether;   Adjust the effective length of the strap to accommodate the size of the user's limb Means for   An electrostatic discharge control article provided.   2. A third conductive layer formed integrally with the first layer, and a third conductive layer Second contact means for interconnecting the conductive tether;   The electrostatic discharge control article according to claim 1, further comprising:   3. The adjusting means comprises a clasp attached to the end of the strap The electrostatic discharge control article according to claim 1.   4. The strap is a closed loop and the first polymer layer is elastic Formed from material,   The adjustment means includes a series of waveforms or cuts so that the strap automatically adjusts. 2. The electrostatic discharge control article according to claim 1, further comprising a stitch in the strap.   5. The contact means is formed in the strap to receive a tether jack A hole, the hole being at least partially formed by the second layer The electrostatic discharge control article according to claim 1 having an inner surface.   6. The contact means comprises a conductive eyelet passing through a portion of the second layer; An eyelet is permanently attached to the eyelet to connect to the tether The electrostatic discharge control article of claim 1 having a snapped portion.   7. A first polymer insulating elastic layer and a second polymer integrally formed with the first layer; An electrostatically controlled wristband comprising a strap having a The first and second layers form a closed loop so that the straps self-adjust. The strap has a series of corrugations and the strap is adapted to receive a tether jack. A hole in the pump, wherein the hole is at least partially formed by the second layer. Electrostatic control wristband with surface.   8. A method of manufacturing an electrostatic control wristband,   Obtaining a first strip made of a polymer insulating material;   Obtaining a second strip of conductive material;   Permanently attaching the first strip to the second strip;   The second strip to interconnect the second strip to a conductive tether Forming means for making electrical contact with;   The first strike on the first strip to accommodate the size of the user's wrist Providing a means for adjusting the effective length of the lip;   A method that includes   9. The first strip is overlaid on the second strip. 9. The method for manufacturing an electrostatic control wristband according to claim 8.   10. The second strip is a polymer and is co-pressed with the first strip. The method for manufacturing an electrostatic control wristband according to claim 8, which is issued.   11. Obtaining a third strip of conductive material;   The first strip so that the second and third strips are electrically insulating. Permanently attaching a trip to the third strip;   The third strip to interconnect the third strip to another conductive tether. Forming a second means for making electrical contact with the tip;   9. The method for manufacturing an electrostatic control wristband according to claim 8, further comprising:   12. Said adjusting means attaches a clasp to an end of said first strip The method for manufacturing an electrostatic control wristband according to claim 8 provided by:   13. The interconnect means connects to the wristband to receive a tether jack. Formed by forming a hole, said hole being reduced by said second strip. 9. An electrostatic control wrist van according to claim 8, having an inner surface at least partially formed. Manufacturing method.   14． The interconnecting means connects a conductive eyelet to a portion of the second strip. Formed by threading the eyelet to connect to the tether 9. The method according to claim 8, further comprising a snap portion.   15. The first strip is a polymer and is co-extruded into a sheet. 11. The method for manufacturing an electrostatic control wristband according to item 10.   16. The first strip is a polymer and is contracted to be coextruded into a closed loop. The method for manufacturing an electrostatic control wristband according to claim 10.   17． The end of the first strip is aligned with a mounting feature of the clasp. 13. The method of claim 12, wherein the recess is formed.   18. A tether,     A flexible reinforcing member,     It is made of a flexible polymer surrounding the reinforcing member and having a conductive filler added thereto. A conductive layer to be formed;     An insulating layer surrounding the conductive layer and made of a flexible polymer;   A tether having   A first electrical connector located at a first end of the tether and electrically connected to the conductive layer; Kuta,   A second electrical connector located at a second end of the tether and electrically connected to the conductive layer; Kuta,   A grounding cord.   19. The conductive layer at a predetermined end of the tether is used to attach a connector. The grounding cord according to claim 18, wherein the grounding cord is formed for use.   20. 20. The grounding cord of claim 18, wherein the reinforcing member is electrically conductive.