KR100507256B1 - Static control wrist strap - Google Patents

Abstract

The electrostatic control wristband 10 of the present invention is a strap 12 having a first polymer insulating layer and a second conductive layer 14 formed integrally with the first layer, and the mutual interaction between the second layer and the conductive tether. Contact means 22 for connection and means for adjusting the effective length of the strap to fit the wrist or ankle dimensions of the user. The third conductive layer 24 can be included to provide a device that constantly monitors the ground path. The contact means may comprise a conventional eyelet through which a snap passes through a portion of the conductive layer for connection with the tether. The insulating layer is extrapolated onto the conductive layer 14, or the conductive layer is co-molded, co-extruded or insert molded into a sheet or tubular shape to the insulating layer. The tether includes a ground cord, which may be composed of a conductive layer surrounding the flexible reinforcing member, which may be a metal wire, gold foil wound polyamide fiber yarn, metal coated fiber. The conductive layer of the tether may be composed of a flexible elastomer containing a conductive filler, with the flexible polymer insulating layer surrounding the conductive layer. The tether may be formed into a coil so that no extra length is left during use.

Description

Power Control Wrist Straps {STATIC CONTROL WRIST STRAP}

The present invention relates generally to devices for preventing electrostatic discharge, in particular electrostatically controlled wristbands and conductive (ground) tethers which are primarily polymer and are formed to reduce the number of parts of the device through the molding process.

In addition to the presence of electrostatic fields, electrostatic discharges can be fatal to sensitive electronic (solid state) components. Modern semiconductors and integrated circuits can be degraded or damaged by such static buildup. Common tools used to control electrostatic discharge and formation include conductive ground tethers designed to dissipate excessive static charge. A general discussion of such a device can be found in US Pat. Nos. 4,677,521, 5,018,044 and 5,184,274.

The wrist band and tether disclosed in the above patent are composed of a plurality of parts, thereby increasing the unit cost of the device. While these devices have useful features for certain applications, they are relatively expensive given the most basic challenges of safety and effective grounding. Cheaper and simpler bands, such as those shown in US Pat. Nos. 3,857,397 and 4,698,724, are designed, which have the disadvantage of having some inherent limitations. For example, the two designs described above are integral wristbands / tethers, which, unlike designs that releasably connect the tethers to the wristbands, may cause the wristband to no longer be used if the tether portion of the device is broken, On the contrary, if the wrist band is broken, the tether can no longer be used, and it also means that when the user wants to leave the workplace, the wrist band must be completely removed or the tether part is suspended. Both of these designs are also unsuitable for the use of dual conductor systems (as shown in US Pat. No. 5,018,044). Finally, the means for adjusting the effective size of the wrist band must be attached separately to the band, such as, for example, a hook / loop-type fixing strip of US Pat. No. 3,857,397 or an adhesive layer of No. 4,698,724. This separate attachment process increases the manufacturing cost, but it is very important that the device can be properly adjusted so as not to be too tight so as not to disturb or distract blood circulation while properly contacting the skin to have sufficient conductivity. Therefore, it is desirable and useful to devise a wristband that is durable, inexpensive and has fewer parts while overcoming the above limitations.

The invention will be better understood by reference to the accompanying drawings.

1 is an exploded perspective view of one embodiment of the electrostatic control wristband of the present invention.

Figure 2 is a perspective view showing the manufacturing process of another embodiment of a wrist band according to the present invention.

FIG. 3 is a perspective view showing another manufacturing process similar to FIG. 2 except for a double conductor embodiment of an electrostatic control wristband. FIG.

4 is a perspective view showing a manufacturing process of the closed loop embodiment of the wrist band according to the present invention.

FIG. 5 is a perspective view showing another manufacturing process similar to FIG. 4 except for the double conductor embodiment of the closed loop wrist band. FIG.

Fig. 6 is a perspective view showing the layered structure of the ground cord made in accordance with the present invention.

FIG. 7 is a perspective view of the ground cord of FIG. 6, made tethered with connectors at one end; FIG.

Figure 8 is a perspective view of another adjusting means of the electrostatic control wristband of the present invention.

9 is a perspective view of an electrostatic control heel strap that may be manufactured in accordance with the present invention.

The present invention generally relates to a strap having a first polymer insulating layer and a second conductive layer integrally molded to the first layer, contact means for interconnecting the second layer to the conductive tether, and a user's arm or leg An electrostatically controlled wristband is provided that includes means for adjusting the effective length of the strap to fit the dimensions. The dual conductor-type wrist band includes a third conductive layer that is also integrally molded with the first layer and second contact means electrically insulated from the first contact means interconnecting the third layer with the second conductive tether, As disclosed in US Pat. No. 5,057,965, it is configured to provide a device that constantly monitors the ground path to alert the wearer as an alarm when the band or tether fails to provide a continuous ground state. The adjusting means may comprise a buckle attached to the end of the strap, or the wrist strap may be self-adjusting by providing a closed looped elastic strap with a series of pleats in the strap. The contact means comprises a conventional eyelet passing through a portion of the second layer and a snap portion connected to the tether, or the contact means is formed on the strap to receive the tether jack and at least a portion of the inner surface is formed of a conductive layer. It can simply be provided as a hole having a.

The wrist band may be manufactured by overmolding the insulating layer on the conductive layer when the conductive layer is a polymer, or by coextrusion, co-molding or insert molding with the insulating layer. The layers may be co-extruded into a sheet shape or co-extruded into a tubular member to provide a closed loop wrist band embodiment.

A new grounding cord is also provided, the tether of which consists of a flexible reinforcing member, a conductive layer surrounding the reinforcing member, and a metal sheath, the reinforcing member being twisted copper wire or insulating polyamide. A gold foil or metal-clad fiber around a fiber yarn. The conductive layer is composed of a flexible elastomer containing a conductive filler, the insulating layer surrounds the conductive layer, and the insulating layer is also composed of a flexible polymer. A conductive layer located at a predetermined end of the tether is formed to attach to a particular connector type. It is desirable to form part of the tether into a coil so that no extra length is left in use.

Referring now to the drawings, and in particular with reference to FIG. 1, one embodiment 10 of an electrostatic control wristband of the present invention is shown. In general, wrist band 10 is comprised of strap 12 formed of an electrically insulating flexible polymer material that is integrally molded with electrical conductive layer 14. As discussed in detail below, the conductive layer 14 is permanently attached to the strap 12 by, for example, extrapolation, co-molding, insert molding or co-extrusion. Strap 12 is this. children. It is preferably composed of Hytrel, a durable thermoplastic elastomer (polyether-ester block copolymer) available from EI duPont de Nemours. Pigments may be added to color the wristband. The conductive layer 14 may be a metal material, but includes a conductive filler to be at least partially conductive (surface resistance less than 1 × 10 ⁶ Ω / sq) to dissipate the static electricity formed in the wearer of the wristband 10. It is more preferable that it is a polymer material. As the material, Hytrel including 15 to 40% by weight of conductive carbon powder is suitable depending on particle characteristics and size.

The conductive layer 14 is located in the thick portion 16 along the strap 12. The electrically conductive eyelets 18 pass through holes formed in the conductive layer 14 and holes 20 formed in the thick portion 16 of the strap 12 to be used to interconnect the wristband 10 with a ground tether. It is attached to the male snap portion 22. Snaps of various dimensions (eg, 4 mm, 5 mm, 7 mm or 10 mm) can thus be attached to strap 12. The thick portion 16 of the strap 12 may be provided with a recess 23 for receiving a snap. Optionally, the eyelets and snaps may be molded into the wrist strap. Additional layers 24 may be used as the conductive, hydrophilic membranes positioned on the carbon containing layer for clean room applications. In this important application, materials with low release of dust (particles or fibers) or gases can be used.

Several features are molded to the strap 12. For adjusting the length of the wrist band, a retaining pin or stud such as a pair of small studs 26 and a large stud 28 is formed at one end, each of which is formed in the corresponding holes 30 and 32 formed at the other end. Each combined. They allow for discontinuous adjustment of the length, so that additional relief may be provided by constructing a relief, such as stretchable link 34. The first rail 36 is provided near the studs 26 and 28 to hold the other end of the strap 12 in the stud upper position to form an insertion hole, and the second rail 38 to retain the extra length of the strap. ) Is provided. The other end 40 may be tapered to facilitate insertion under the rails 36, 38. Other reliefs, such as ribs or grooves 42, may be formed along the strap to enhance the flexibility of the strap so that the strap fits nicely around the user's wrist.

The above design has several advantages. In addition to providing all of the basic characteristics of a ground wrist strap, the wrist band 10 can be conveniently adjusted to fit comfortably in proper contact with everyone's skin in one dimension. In particular, the manufacturing cost is low when four components (strap 12, conductive layer 14, eyelet 18, snap 22) are used. Moreover, by changing a pigment | dye during a manufacturing process, appropriate color can be selected easily. As will be discussed later, wristbands can be made relatively easily through an extrapolation or coextrusion process that allows for simple fabrication of integral straps and conductive layers and rapid assembly of additional components.

Figure 2 is a perspective view showing the manufacturing process of another embodiment 44 of the wrist band according to the present invention. Wrist band 44 is constructed by extrapolating a sheet of conductive (carbon containing) material on a sheet of wider insulating polymer material and forming an integral sheet 46 on which individual wrist bands 44 can be formed. In the first step of manufacturing the seat 46, a line may be cut in the sheet to define the boundary of the strap portion 48 of the wrist band 44, and a hole is punched through the thick portion of the strap. In the next assembly step, the eyelet 50 and the snap 52 are attached. In the final step, buckle 54 is attached to one end of strap 48. A groove or recess 56 is formed in the end of the strap 48 to mate with the attachment portion of the buckle 54. This strap end 48 has a tapered lead portion 58 that can pass through the buckle 54, which is cut after attachment of the buckle.

Similar processes and designs are shown in FIG. The only difference is that the insulating layer is extrapolated on the two conductive layers, where the two conductive layers are slightly separated, so that in the finished wristband 60 two separate conductive portions 62, 64 are formed in the strap. It is formed along the surface. Two snaps 66, 68 are attached to each eyelet on the strap to make contact with the two conductive portions 62, 64, respectively. This allows dual conductor wrist band 60 to be used with dual conductor monitoring systems known in the art.

4 illustrates a manufacturing process of another embodiment 70 of a closed loop wrist band according to the present invention. As in the process of Figures 2 and 3, the wristband 70 is made by cutting the strap from a wide material having a conductive layer already integrally formed in the insulating layer. In Figure 4, the wristband is a tubular member, not a sheet. Since it is formed from 72 and the wristband 70 becomes a closed loop, there is no need for a buckle or other element to attach the end of the wrist strap. The tubular member 72 can be formed by coextrusion of the conductive layer 74 with an insulating polymeric material. During the extrusion process, holes 76 may be formed in thick portions within the strap to receive plugs at the ends of the ground tether. The hole 76 has an inner surface whose at least part is formed of a conductive layer. Forming holes 76 in this manner further lowers the cost of the device because the tether can be interconnected without adding other components (ie, eyelets and snaps). Wrist band 70 is formed of an elastic material having bends or creases 78 to allow for self-adjustment, i.e. satisfactory skin contact, without the need for additional adjustment elements such as buckles, around wrists of various sizes. It can be stretched and fixed in the Instead of the pleats 78, a series of small transverse cuts may be formed in the strap portion to provide self adjustment.

FIG. 5 shows another double conductor embodiment 80 of the wristband according to the present invention, similar to FIG. 4 but formed to have separate conductive layers 82 and 84 as in the process of FIG. FIG. 5 also shows a snap 86 that may be used in the design instead of the plug receiving hole 76 of FIG.

6 and 7, these figures show a new ground tether 90 that can be used with the wristband of the present invention. Tether 90 has some of the same design features as the wristbands described above, that is, a conductive layer that is coextruded with an insulating layer and mainly has a polymer configuration. Specifically, the tether 90 has an outer layer 92 made of an insulating polymer such as Hytrel, and an inner layer 94 made of a conductive material (carbon-containing Hytrel is preferable). When the carbon content is 32%, a typical ground cord 10 'long made of tether 90 has a resistance of about 2 kΩ. Although the conductive layer 94 is shown to have a circular cross section, those skilled in the art will appreciate that such a shape is not essential. The layers can be extrapolated or coextruded using tensile filaments. Near the center of the conductive layer 94 is a reinforcing member, preferably polyester or E. children. Reinforcing fibers 96 of Kevlar, an aromatic polyamide available from Dupont de Nemo. In addition, the reinforcing member may be, for example, one or more solid metal wires or wound on reinforcement lines of polyester or Nomex (polyamide available from E. Dupont de Nemoa) fibers. It may be gold leaf.

7 shows how tether 90 is made of a ground cord having connectors at each end. If a banana plug 98 is required or desired, such a plug can be attached directly to the exposed conductive layer at one end of the tether 90 using a pleated tube formed on the banana plug. Banana plugs are also polymer molded parts. If a snap, such as snap 22, is required for interconnection, the conductive layer exposed at one end of the tether 90 may be bent to a flat end for thermal stamping or welding of the polymer to the metal snap 100. Instead, the end may be connected to a resistor and the resistor may be connected to a metal snap. Alternatively, female snaps with prongs gripping the ends of the tether may be molded with conductive hytrel. Extrapolated insulators and stress relief boots can be used further for end reinforcement.

In addition, FIG. 7 shows a coil shape by winding a portion 102 of the tether 90 into a coil shape on a mandrel and rapidly cooling after heating to minimize extra tether length in use when the material of the tether is an elastomer. It shows how to make me remember. The insulating layer 92 is preferably a material having a higher durometer hardness (in the range of 45 to 80 Shore D) for durability (the durometer hardness of the conductive layer 94 is preferably in the range of 25 to 50 Shore D ). Fiber 96 has a diameter of 0.08 mm to 0.38 mm (0.003 inch to 0.015 inch), conductive layer 94 has an outer diameter of about 1.78 mm (0.070 inch), and insulating layer 92 is about 2.41 mm ( 0.095 inch).

8 shows another variant embodiment of the electrostatic control wrist band 104 with various adjustment means. Specifically, hinge buckle 106 is integrally molded to the strap, and the buckle has a slightly arced first portion 108 and a slightly arced second portion 110, when the buckle is closed, the second portion ( 110 overlaps the first portion 108. Living hinge 112 is formed between two portions 108, 110. The first portion 108 has a latch finger 114 for releasably securing the second portion 110 in place. Other members, such as bumps 116 and ridges 118, may be used to help align the two portions 108 and 110, with corresponding holes or notches formed in the underside of the second portion 110. FIG.

Figure 9 illustrates how the present invention is attached to an electrostatic control device, in particular a heel strap 120, similar to a wrist band. Heel strap 120 includes an electrically insulating polymer main strap portion 122 having an integrally formed conductive layer 124, similar to the wrist band described above. However, the heel strap 120 is configured to be worn such that the conductive layer 124 faces downward, ie, in contact with the ground, an electrostatic control floor mat, or the like. The conductive layer 124 may be molded to have a non-slip surface, such as a jagged surface. Strap 120 has front overlaps 126 and 128 that wrap around the upper arc of the foot or shoe so that strap 120 is secured to the wearer. The other portion 130 wraps around the posterior side of the heel. Portion 130 is secured in a nested shape by another eyelet or rivet 132. The eyelet 132 is in electrical contact with a resistor 134 whose other end is attached to the other eyelet 136. Eyelet 136 then secures another conductive strip 138 to strap 120. The conductive strip 138 is encased in the wearer's shoe so as to be in physical contact with the wearer's foot.

The present invention has been described above with reference to specific embodiments, but the description is not meant to be interpreted in a limiting sense. Those skilled in the art will readily appreciate various modifications of the disclosed embodiments and other embodiments of the invention by reference to the description of the invention. It is therefore to be understood that such modifications may be made without departing from the spirit or scope of the invention as set forth in the appended claims.

Claims (6)

An apparatus for controlling electrostatic discharge, A strap that is a closed loop having a first polymer insulating layer formed of an elastic material and a second conductive layer molded integrally with the first layer; Contact means for interconnecting said second layer with a conductive tether, Means for adjusting the effective length of the strap to fit the dimensions of the user's arm or leg. The apparatus of claim 1, further comprising a third conductive layer integrally formed with the first layer, and second contact means for interconnecting the third layer and the second conductive tether. The device of claim 1 wherein said adjusting means comprises a buckle attached to one end of the strap. The device of claim 1, wherein the contact means comprises a hole formed in the strap to receive a tether jack, the hole having an inner surface at least partially formed of a second layer. The device of claim 1, wherein the contact means comprises a conductive eyelet passing through a portion of the second layer, the eyelet having a snap portion permanently attached to the eyelet to connect with the tether. In the electrostatic control wrist band, A strap having a first polymer insulating elastic layer and a second polymer conductive layer integrally molded with the first layer, The first and second layers form a closed loop and have a series of pleats to allow the strap to self-adjust, the strap further having a hole for receiving a tether jack, the hole having at least a portion of the second layer. An electrostatic control wrist band having an inner surface formed of a layer.