US235590A - Selenium-cell - Google Patents

Description

(Na'ModeL) S. TAINTER. Selenium Cells.

Pa ten ted Dec. 14,1880.

C. &, musm/ N. PETERS. FHOTO-LITHOGRAF UNITED STATES SUMNER TAINTER, ()F WATERTOVVN, MASSACHUSETTS.

SELENlUM-CELL.

SPECIFICATION forming part of Letters Patent No. 235,590, dated December 14:, 1880. Application filed September 25, 1880. (No model.)

To all whom it may concern:

Be it known that I, SUMNER TAINTER, of \Vatertowmcounty of Middlesex, and State of Massachusetts, haveiuvented an Improvement in Selenium-Cells, of which the following de scription, in connection with the accompanying drawings, is a specification.

My invention relates to selenium-cells or instruments containing selenium as a portion of an electric circuit.

In an application of Alexander Graham Bell, filed August 28, 1880, an apparatus was shown and described for transmitting sound or producing variations in electric current by the action of a beam of rays from the sun or other radiant bodies. The said apparatus contained an instrument having selenium in an electric circuit, the resistance whereof is varied in ac eordance with variations in the active force of the rays falling on the said selenium. In the said application various forms of instruments or cells containing selenium were described, some of which were not therein claimed, as they were not invented by the said Bell. One of the forms therein described,together with several modifications, forms the subject of the present application. In the said application of Bell it was stated that the selenium is of large resistance, and it should consequently be interposed in the circuit in the form of a conductor of but slight length and of large area 5 and it may be further stated that it is desirable to arrange the selenium in circuit, so that it will have as large a surface as possibe to be acted upon by the rays, the effect of which is greater at or near the surface upon which they fall than upon the interior mass.

The instruments of the present invention consist, generically, of two or more pieces of conducting material clamped or fastened together, but not in electric contact with one another, and so arranged that each sh all have alarge number of points near, but not touching, the other, the said points being mostly situated in or near a given surface intended to be exposed to the action of the rays. Selenium is fused in between the said points, so as to electrically eonuect the two pieces of conducting material, and as the said points are close together the selenium conductor is very short, and as the points are very numerous the selenium is inl terposed in circuit in multiple are, or as acouductor of large area, and it affords, moreover, a large surface to be acted upon by the rays in proportion to the amount of the selenium in the circuit. In some instances the pieces ofconducting material are made as two plates, one having a series of holes, and the other a series of projecting points or pins of slightly smaller diameter, to pass into the said holes, but not quite fill them, the annular spaces around the pins being filled with selenium. The holes are made tapering, being smallest, and consequently approaching the pins more closely, at the surface to be acted upon by the rays, so that the selenium conductor is shortest at the 1 surface, and consequently the electricity has the most direct path through the selenium where it is directly acted upon by the rays, and consequently most sensitive. In another instance one of the pieces of conducting material is shown as a netting, and the projections of the other piece pass into, but do not quite fill, the interstices thereof. In anotherinstauce several pieces of conductive material are formed as concentric tubes, the external diameter of each being smaller than the internal diameter of the nest larger, so as to leave concentric annular spaces between them. These spaces are filled near the ends of the tubes with selenium, the whole forming a continuous surface to be 6X- posed to the action of the rays.

Figure l is a top view, Fig. 2 an under-side view, and Fig. 3 is a sectional view, of a selenium-cell constructed in accordance with my invention; Figs. 4 and 5, plan and sectional views of a modification thereof; Figs. 6 and 7, a plan and sectional view of another modification, in which a netting is used, and Figs. 8 and 9 a plan or section of an instrument composed mainly of concentric tubes.

The instruments consist, essentially, oftwo portions, a I), of conducting material, preferably brass, to be connected with opposite terminals of an electric circuit.

Referring to Fig. 1, the portion a is a plate counterbored at c and provided with a series of holes, d, made tapering, as shown in Fig.3, and of smallest diameter near the outer surface of the plate a, which is to be acted upon by the rays.

The portion 7) is a plate provided with a series of pins, 0, arranged to pass into the middle of the holes (I when the two plates a b are properly placed together, the pins 6 being smaller in diameter than the holes (I, so as to leave a series of annular spaces between the said pins and the plate a surrounding them.

The two plates are properly matched together. A washenf, of insulating material, is placed between them to prevent electrical contact, and they are tightly fastened together by screws 9 passing through the plate I) and insulated therefrom in any convenient manner, as by the washers h under the heads thereof. A wire conductor forming one terminal of a circuit can be inserted under the head of one of the screws 9, and thus placed in electrical connection with the plate (6. Abinding-screw, z, is employed, to enable a wire to be readily connected with the plate I).

As thus far described the two plates a I) are insulated from one another, but have a series of points at d c in close proximity to one another, and lying in the outer surface of the plate a. The whole instrument is now heated to a temperature somewhat higher than the melting-point of selenium, which is rubbed over the surface of a plate, a, in the part perforated by the holes (I. The selenium will be melted, covering the surface of the plate a between the holes cl and the end of the pins 0, and filling the annular spaces between thepins e and the plate a, thus connecting the two plates to b in such manner that an electric current can pass from one to the other through the annular rings of selenium 8. When solidified, on coolin g, the selenium is to be treated by a suitable process in order to acquire the properties of conductivity and sensitiveness to the action of rays, which properties it does not possess when solidified from a liquid.

A process of treatment is fully described in ajoint application of myself and A. G. Bell, heretofore mentioned, to which referencemay be had.

It is sufficient to state here that the selenium should be heated as nearly as possible to its temperature of fusion without allowing it to actually melt, and then cooled, when it will be found to possess the desired properties.

In the form illustrated in Figs. 4 and 5 the portion 1) is formed as a box, having a flange or-side, b, with an internal shoulder, 2.

The plate a, provided with tapering holes (I, is secured by screws 3 to a plate, a, of glass or other suitable insulating material, fitted to enter the upper portion of the flange b and rest on the shoulder 2 thereof, where it is held connected with the plate I) by the screw g. The plate a is slightly smaller than the internal diameter of the flange b, and the shank of the screw 9 passes through without touching the plate a, which is thus insulated from the plate I), the latter being provided with pins 6 to,pass into the holes d, as in the instrument previously described. In thisinstance the selenium to connect the two plates to b may be placed, in a pulverized condition, in the holes d, it then resting on the plate a, inverted for that purpose, and after the two portions a b have been properly fastened together by the screw 9 the selenium will be melted and treated or annealed, as in the other instance.

In Figs. 6 and 7 the portion a is shown as a network of interwoven wires, the meshes or interstices of which correspond in function to the holes (I of the plates a, hereinbefore described.

The plate I) is provided with a series of intersecting grooves corresponding in position to the wires of the netting a, and leaving between them a series of square projections, 0, corresponding in function to the pins 6 of the other forms, they being slightly smaller than the netting a, which may rest on pieces of insulating material f, and thus be electrically separated from the portion 1).

When selenium is fused over the upper surface it completes the electric circuit between the portions to b, as before described.

In the form shown in Figs. 8 and 9 the portions a b consist of a series of concentric tubes separated from one another by a slight space and provided with flanges m, to enable them to be properly secured together. Annular washers f are placed between the said flanges m, and tubular pieces of insulating material are placed between the concentric tubes, but do not extend quite to the ends of the said tubes. A series of concentric annular channels are thus formed between the said tubes, and these channels are filled with selenium, properly prepared, as before described, which thus forms an electric connection between the said tubes. The alternate ones, a, of the said conducting -tubes are electrically connected with one terminal of an electric circuit, and the intermediate ones, I), electrically connected with the other terminal.

The insulating material employed should be of a kind not injured by the heat necessary for treating the selenium. Mica is a suitable material for this purpose, in most instances, and has generally been used by mein the construction of these instruments.

The construction shown in Figs. 1, 2, 3 is very simple, and the instrument is readily taken apart, if desired, the selenium in that case being melted.

It has been stated that the selenium, when fused upon the surface of the instrument, covers the conductive material.

I have obtained the best results by removing, by filing or otherwise, the superfluous selenium, leaving as an exposed surface only that lying between the different portions of the conductive material.

By making the holes d tapering, as shown in Figs. 3 and 5, the parts of the conductives a b which are in closest proximity, and consequently where the selenium conductor is shortest, lie on the surface to be exposed to the rays.

It is obvious that various modifications of the above-described forms may be employed,

l l l theessential features of the invention being the two portions of conductive material electrically insulated from one another, except at a series of points where they approach one another closely, and where they are connected by selenium or other equivalent material havin g the desired properties of sensitivcness as to their electrical conductivity to the action of rays falling upon it, the said connecting material being a conductor of short length and large area, and having a surface large in proportion to its total amount, in proper position to be acted upon by the rays.

I claim- 1. In an instrument containing selenium as a portion of an electric circuit, two pieces of conducting material insulated from one another and provided with a series of points near, but not in contact with, one another. and selenium placed between the said portions of conducting material at the said points to electrically connect them, substantially as described.

2. In an instrument to interpose selenium in an electric circuit, two plates of conductive material rigidly held in relation to one another without electrical contact, one plate being perforated with a series of holes or openings, and the other provided with a series of projections to pass into, but not fill, the said openings, and selenium interposed between the said projections and the perforated plate, substantially as described.

3. Two conductive plates, one provided with a series of openings and the other with a series of corresponding projections, and selenium interposed between the plates in the said openings to form, with the plates, a continuous surface, the plates being properly shaped to approach one another most closely on the said surface, as and for the purpose described.

4. The herein-described selenium-cell, consisting of two plates and an interposed layer of insulating material fastened rigidly together, one plate being provided with a series of tapering holes and the other with a series of projecting pins passing into the said holes, and selenium to complete the electric circuit between the two plates, substantially as described.

In testimony whereof I have signed my name to this specification in the presence or" two subscribing witnesses.

SUMNER TAINTER.

Witnesses:

PHILIP MAURO, BARTRAM ZEVELY.

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