US 3283209 A
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Description (OCR text may contain errors)
NOV- 1, 1966 R. W. SCHUTZ STATIC ELIMINATOR Filed April 5, 1964 United States Patent thee 3,283,209 STATIC ELIMINATOR Rudolph W. Schutz, Crystal Lake, Ill., assignor to Uarco, Incorporated, a corporation of Illinois Filed Apr. 3, 1964, Ser. No. 357,107 4 Claims. (Cl. 317-2) This invention relates to the structure of an elongated static eliminating bar and more particularly to a device for removing or neutralizing static electricity charges upon a moving web of stationery or other material.
In recent years the problem of static electricity in continuous form stationery has increased manyfold due to a combination of` factors, among which is the use of very thin papers and papers which are specially coated or supercalendered and a material increase in the speed at which such papers are moved through printing and servicing equipment. Computers and their associated printers have been speeded up very materially. Brusters Iand deleavers which handle the continuous form stationery after it is printed have also been increased in speed severalfold. As a result, static electricity on the surfaces of the papers has become an increasingly vexatious problem.
The present invention has to do with a generator type of static eliminator, that is, one in which an electrical charge of high voltage but very low amperage is used to create an atmosphere adjacent the paper web providing free ions to neutralize the static charge. Such general type of static eliminators are presently available from several sources. The cost of such units, however, has been prohibitively high preventing extensive use of static eliminators on relatively low cost equipment. The available equipment also fails to be readily adaptable to different forms of equipment but must generally be specially ordered to t the environment in which it is to be used. The present invention eliminates these defects of the available and prior known structures by providing a new structure producible at a small fraction `of the cost of available equipment by providing a better form of construction.
It is therefore the principal object .of this invention to provide a new and improved static eliminator structure.
Another object is to make such a static eliminator having an extremely compact cross sectional size.
Another object is to make a static eliminator having a novel arrangement of parts permitting the building of the eliminator in various lengths at a minimum of cost of manufacturing equipment, operations and material.
Other objects, features and advantages of the present invention will be apparent from the following description of a preferred embodiment illustrated in the accompanying drawings, in which:
FIGURE 1 is a broken side elevational view partially in section through a static eliminator bar embodying the invention;
FIGURE 2 is a broken plan view of the bar illustrated in FIGURE 1;
FIGURE 3 is an upright sectional view through the bar adjacent the left hand end as shown in FIGURE 1 taken substantially along line 3-3 therein;
FIGURE 4 is a sectional view similar to FIGURE 3 taken adjacent one of the discharge points and substantially along line 4-4 in FIGURE l;
FIGURE 5 is a view similar to FIGURES 3 and 4 taken through one of the support members for the electrically conductive bar and substantially along line 5 5 in FIGURE l;
FIGURE 6 is an elevational view of the right hand end plug on the bar of FIGURE 1 as it would appear removed from the bar; and
3,233,209 Patented Nov. l, 1966 FIGURE 7 is a perspective view of one of the discharge point structures.
It is contemplated that the static eliminator bar of the present invention may be made in various lengths, for example, from 10 to 60 or be used with more than one length of bar in tandem to make up any length of bar desired. Each unit will have the same cross sectional shape which is quite small, the bar illustrated being one of 1% wide by about deep. A transformer supplies the electrical energy to the bar and its output would be measured as a few milliamperes. Two sizes of transformers may be required to cover the range of lengths of bar, there being a matching of the output of the transformer with the number of discharge points available on the bar with which the transformer is connected. The number of points should be enough to prevent arcing between the point and ground and not too many to prevent the desired generation of ozone in the atmosphere surrounding the point, thus providing free ions for the neutralization of a static electricity charge. This invention is concerned primarily with the structure of the bar itself.
Referring to the drawings, the outer casing 1t) is a sheet metal, generally channel-shaped, member comprising the outer sheath of the bar. As shown in the cross sectional view, the channel 10 has a bottom wall 11, a pair of side walls 12 and 13, each of which has an inturned upper extremity 14 and 15, respectively, terminating in upper longitudinally extending edges 16 and 17, respectively. The sheet metal may be given appropriate surface treatment such as plating providing a pleasing appearance for the unit. The bottom wall Il is extended at each end of the length of the channel providing fingers or ears 18 and 19, respectively, for supporting the bar on a piece of equipment and also providing the ground connection for the bar. In FIGURE l the ears are shown at approximately a right angle to the longitudinal extent of the bar but may be turned to any other angle or extended horizontally, if desired.
The electrical energy is conducted to the interior of the structure specically to a brass rectangular bar 20 extending longitudinally throughout substantially all but the end portions of the casing and having a constant cross sectional shape except for a slot at one end to receive the electrical conductor 21. The slot may best be seen at 22 in FIGURES l and 5. Other shapes of bar may be used, if desired.
To make structures of different lengths, only the casing and the brass bar need be chosen since all other components are the same in any length of bar. Only the number of components or their spacing will vary. The brass bar is supported in the bottom of the casing by a plurality of blocks 23 each of which is formed of a plastic material of a size to be wedged into the bottom of the casing as illustrated in FIGURE 5. The block is somewhat doughnut-shaped in section with a rectangular hole therein to receive the bar therein. As shown in FIGURE 1, three such support blocks are used to support the brass bar 20. The blocks 23 support the brass bar in a spaced relationship to the casing.
The discharge points are preferably formed of sheet metal. As illustrated in FIGURE 7, the sheet metal has a base `bent into a U-shape to sit astraddle of the brass bar and to grip the bar to hold the point in place. The upwardly extending point 24 is a continuation of the flat surface 25 of the base portion which is integral to the pair of downwardly extending legs 26 and 27. As illustrated in FIGURE 4, the point 24 extends above the bar While the legs 26 and 27 grip the bar 20. Being of sheet metal, the base c-an be made resilient to frictionally hold the point in any position along the length of the bar to which it is manually placed. The length of the base of the point determines the minimum number of points that can be placed upon a given length of bar. It has been found that the corona `around a point extends for `about 1% in all directions for the energy used in one unit. Therefore, any two adjacent points may be 11/2 apart without leaving an area unaffected. Also, by way of example, the length of the base of the points in the illustrated structure is `about 3A providing considerable variation in the number of points which may be placed upon a given length of bar.
The ends of the casing are each closed by a plastic molded end plug. The end plug 30 through which the insulation 31 containing the elect-rical conductor 21 passes is provided with an opening 32 just sufficiently large to pass the insulation 31. Otherwise, the plug has an outstanding flange 33 adjacent a groove 34 Ion each side of the plug shaped to receive and embrace the end of the casing. Thus, as shown in FIGURES 3, 4 and 5, the side walls of the casing extend into the groove 34 and are embraced firmly therein and the bottom 11 ts between the flanges 33 on the plug in contact with the bottom of the plug.
Once the casing, bar, supports, points and end plugs are assembled, a dielectric potting compound 40 is poured into the casing so as to surround the parts and encapsulate all but the extremities of the discharge points as shown in FIGURE 4. The potting compound 40 is preferably an epoxy resin. Since such resin has a dielectric strength about 400 times that of air, the use of the epoxy is very desirable, because of its dielectric pr-operties and also in that it allows the bar to be small in section. The danger of shock to a workman is quite improbable since the extremities 41 of the points are spaced well below the edges 16 and 17 of the casing. The current is so low that the shock is annoying rather than damaging if it occurs. The electrical lead to the brass bar may be connected to any type of connector such as dagramm-atically illustrated at 42 to a transformer not shown. Each discharge point of the bar represents a load or current output requirement to the transformer. The load is a function of the distance between a point and the nearest ground, usually the outer casing, and is also -a function of the number of points on the bar. The load does not vary with the spacing of the points along the bar. Therefore the effective area of static neutralization may be increased or decreased without changing the load by changing the lateral spacing of the points on the bar before potting. Thus, the transformer used should 4be designed for the specic number of points desired on the length of bar used. Ordinarily, the number of points can be varied somewhat for a given transformer as is known.
The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art.
1. A static eliminator, comprising: an outer elongated channel-shaped metal casing having means for connection to ground; an electrically conductive bar extending lengthwise in the casing; a plurality of discharge points electrically connected to the bar and arranged along its length, each discharge point being formed of metal material and having a U-shaped base shaped to straddle the bar in gripping relation thereto and thus position and hold the point relative to the bar; a dielectric potting compound consisting of an epoxy resin iilling said casing to a level exposing only the tips of said points `and insulating said bar from `said casing; and means for connecting said bar to an electrical energy source.
2. The static eliminator of claim 1 wherein the conductive bar has a polygonal cross section with spaced opposed iiat surfaces and wherein the U-shaped base has spaced opposed portions for engagement with the spaced opposed at surfaces of the conductive bar.
3. The static eliminator 4of claim 1 wherein the electrically conductive bar is generally rectangular in cross section and wherein the U-shaped base of the discharge point is generally right -angular in cross section.
4. The static eliminator of claim 3 wherein the periphery of the bar and the interior of the U-shaped base are in substantial intimate engagement throughout the cross sectional extent of the bar and base of the discharge point.
References Cited by the Examiner UNITED STATES PATENTS 940,431 l1/ 1909 Chapman 317-2 X 2,392,808 l/1946 Chapman 317-2 X 3,137,806 6/1964 Schweriner 317-2 X 3,162,787 12/1964 Hanscom 317-2 X 3,174,748 3/1965 Roberts 317-262 X MILTON O. HI'RSHFIELD, Primary Examiner.
SAMUEL BERNSTEIN, Examiner.
J. A. SILVERMAN, Assistant Examiner.