초록 ▼

A conveyor for transporting objects sensitive to electrostatic discharge. In one embodiment, the present invention relates to a roller conveyor with conductive rollers in electrical communication with an electrical ground. The rollers preferably have about 105 ohms resistance from the outer diameter

A conveyor for transporting objects sensitive to electrostatic discharge. In one embodiment, the present invention relates to a roller conveyor with conductive rollers in electrical communication with an electrical ground. The rollers preferably have about 105 ohms resistance from the outer diameter to the inner diameter to ensure that electrostatic charges built up on the conveyed object can flow to ground, yet not flow too quickly. In another embodiment, the roller shafts are supported on highly conductive bushings that provide a path to electrical ground that is preferably less that 104 ohms. In yet another embodiment, the roller shafts are driven by a conductive pulley that minimizes the build-up of electrostatic charge as a result of a triboelectric effect with the drive belt.

대표청구항 ▼

What is claimed is: 1. An apparatus comprising: a conveyor adapted for moving objects, said conveyor including: a plurality of electrically conductive non-metallic rollers adapted for conveying an object thereon, said rollers having an outer diameter adapted for contacting the object and an inner d

What is claimed is: 1. An apparatus comprising: a conveyor adapted for moving objects, said conveyor including: a plurality of electrically conductive non-metallic rollers adapted for conveying an object thereon, said rollers having an outer diameter adapted for contacting the object and an inner diameter, said rollers having a first electrical resistance from the outer diameter to the inner diameter; a plurality of electrically conductive rotatable roller shafts for supporting said plurality of rollers; a plurality of electrically conductive non-metallic bushings for rotatably supporting said plurality of roller shafts; and wherein said rollers, said roller shafts, and said bushings are in electrical communication with a common electrical ground, there being a second electrical resistance from one of said roller shafts supported by one of said bushings to the common electrical ground, the second electrical resistance being less than the first electrical resistance. 2. The apparatus according to claim 1, wherein said bushings are formed from a synthetic material including conductive microfibers, graphite, or carbon. 3. A The apparatus according to claim 1, wherein said rollers are formed from a synthetic material including conductive microfibers. 4. The apparatus according to claim 1, wherein the first electrical resistance is more than about one hundred thousand ohms and less than about two million ohms. 5. The apparatus according to claim 1, which further comprises: a plurality of electrically conductive non-metallic pulleys, each of said pulleys being coupled to one of said roller shafts, said pulleys being in electrical communication with the common electrical ground; and a plurality of drive belts, each of said drive belts driving one of said pulleys. 6. An apparatus according to claim 5, wherein said drive belts are formed from a urethane material, and said pulleys are fabricated from a synthetic material including conductive microfibers, carbon, or graphite. 7. An apparatus according to claim 5, which further comprises at least one electrically conductive cover, and wherein said pulleys and said drive belts cooperate to generate a triboelectric field, and said cover provides an electromagnetic shield to contain the triboelectric field. 8. The apparatus according to claim 1 which further comprises a plurality of electrically conductive bushing holders for supporting said plurality of bushings, and a static support member for supporting said plurality of bushing holders, said bushing holders and said static support member being in electrical communication with the common electrical ground. 9. The apparatus according to claim 1 wherein the first electrical resistance is less than about two million ohms, and the second electrical resistance is less than about one hundred thousand ohms. 10. The apparatus according to claim 9, wherein the first electrical resistance is more than about one hundred thousand ohms. 11. The apparatus according to claim 10, wherein said rollers are formed from a synthetic material including conductive microfibers. 12. The apparatus according to claim 11, which further comprises: a plurality of electrically conductive non-metallic pulleys, each one of said pulleys being coupled to one of said roller shafts, said pulleys being in electrical communication with the common electrical ground; and a plurality of drive belts, each of said drive belts driving one of said pulleys. 13. An apparatus according to claim 12, which further comprises at least one electrically conductive cover, and wherein said pulleys and said drive belts cooperate to generate a triboelectric field, and said cover provides an electromagnetic shield to contain the triboelectric field. 14. An apparatus comprising: a conveyor adapted for moving an object, said conveyor including: a plurality of electrically conductive non-metallic rollers adapted for conveying an object thereon; a plurality of electrically conductive rotatable roller shafts adapted and configured for supporting said plurality of rollers, said rollers and said roller shafts being in electrical communication with an electrical ground; and electrically conductive means for driving the roller shafts, a portion of said driving means being in electrical communication with an electrical ground. 15. The apparatus according to claim 14 wherein said driving means comprises: a plurality of electrically conductive non-metallic pulleys, each of said pulleys being coupled to one of said roller shafts, each said roller shaft being rotatably driven by one of said pulleys, said pulleys being in electrical communication with an electrical ground; and a plurality of drive belts, each of said drive belts driving one of said pulleys. 16. The apparatus according to claim 15 wherein said drive belts are substantially smooth and said pulleys are substantially smooth and include at least one V-groove. 17. The apparatus according to claim 16 which further comprises a static support member and a rotatable drive shaft supported by said static support member, wherein said drive shaft drives at least one of said drive belts. 18. The apparatus according to claim 15 wherein said drive belts have a toothed surface and said pulleys have a toothed outer diameter adapted and configured for coupling with the toothed surface of said drive belts. 19. An apparatus according to claim 14, which further comprises at least one electrically conductive cover in electrical communication with the electrical ground, and wherein said driving means generates a triboelectric field, and said cover provides an electromagnetic shield to contain the triboelectric field. 20. The apparatus according to claim 19, which further comprises a static support member adapted and configured for supporting said roller shafts, wherein said static support member and said cover cooperate to form a plenum which is evacuated to remove particulate matter from said conveyor. 21. An apparatus according to claim 14, wherein each of said rollers have an outer diameter and an inner diameter, the resistance between the inner diameter and the outer diameter being more than about one hundred thousand ohms and less than about two million ohms. 22. An apparatus according to claim 21, wherein said pulleys are formed from a synthetic material comprising conductive microfibers. 23. An apparatus according to claim 22, which further comprises at least one electrically conductive cover in electrical communication with the electrical ground, and wherein said driving means generates a triboelectric field, and said cover provides an electromagnetic shield to contain the triboelectric field. 24. An apparatus comprising: a conveyor for moving an object, said conveyor including: at least one electrically conductive roller adapted and configured for contacting the object, said roller having an outer surface and an inner diameter, the resistance between the inner diameter and the outer surface being more than about one hundred thousand ohms and less than about two million ohms; and at least one electrically conductive rotatable roller shaft having an outer diameter for rotatably supporting said at least one roller; wherein the electrical resistance from the outer diameter of said roller shaft to an electrical ground is less than about ten thousand ohms, and the outer surface of said at least one roller is in electrical communication with an electrical ground. 25. An apparatus according to claim 24, which further comprises: at least one electrically conductive bushing for rotatably supporting said least one roller shaft; and a static support member for supporting said at least one bushing; wherein said roller is in communication with an electrical ground through said roller shaft, said bushing, and said static support member. 26. An apparatus according to claim 25, wherein said bushing is formed from a synthetic material which includes conductive microfibers, carbon, or graphite. 27. The apparatus of claim 24 where the electrical resistance from the outer surface of said roller to the inner diameter of said roller is more than about three hundred thousand ohms and less than about eight hundred thousand ohms. 28. An apparatus comprising: a conveyor for moving objects, said conveyor including: a plurality of electrically conductive rollers for supporting the objects; said roller having an outer diameter and an inner diameter, the resistance between the inner diameter and the outer diameter being more than about one hundred thousand ohms and less than about two million ohms; a plurality of electrically conductive rotatable roller shafts for supporting said plurality of rollers, each of said roller shafts supporting at least one said roller; a plurality of electrically conductive bushings adapted and configured for rotatably supporting said plurality of roller shafts; a plurality of electrically conductive bushing holders for supporting said plurality of bushings; a plurality of electrically conductive non-metallic pulleys, each of said pulleys being coupled to one of said roller shafts; and a plurality of drive belts, each of said drive belts driving one of said pulleys; wherein said rollers, said roller shafts, said bushings, said pulleys, and said bushing holders are in electrical communication with a common electrical ground. 29. The apparatus according to claim 28, wherein said bushings are formed from a synthetic material including conductive microfibers, graphite, or carbon. 30. The apparatus according to claim 28, wherein said rollers are formed from a synthetic material including conductive microfibers. 31. An apparatus according to claim 28, wherein said drive belts are formed from a urethane material, and said pulleys are fabricated from a synthetic material including conductive microfibers, carbon, or graphite. 32. The apparatus of claim 28, where the electrical resistance from the outer surface of said roller to the inner diameter of said roller is more than about three hundred thousand ohms and less than about eight hundred thousand ohms. 33. A method comprising: providing a conveyor; transporting an object on the conveyor; generating an electrostatic charge associated with the object; conducting the electrostatic charge from the object through a first resistance, the first resistance having a value of more than about one hundred thousand ohms and less than about two million ohms; conducting the electrostatic charge through a second resistance after said conducting through a first resistance, the second resistance having a value of less than one hundred thousand ohms; and conducting the electrostatic charge to ground. 34. The method according to claim 29, wherein said providing includes a roller conveyor having a roller shaft driven by a pulley and belt, and which further comprises: generating a triboelectric field by the pulley and belt; and shielding the object from the triboelectric field. 35. The method according to claim 34, wherein said providing includes a roller conveyor having a roller shaft driven by a pulley and belt, and which further comprises: generating an electrostatic charge by the pulley and the belt; and conducting the electrostatic charge generated by the pulley and belt through the pulley to ground.