US2798971A - Generator of electrostatic charges - Google Patents

Description

July 9, 1957 P. o. BERNARD GENERATOR 0F ELECTROSTATIC CHARGES Filed Jan. 23, 1956 FIG. I

FIG. 2

2,798,971 GENERATOR F ELECTROSTATEC CHARGES Pierre D. Bernard, Paris, France Application January 23, 1956, Serial No. 566,314 Claims priority, application France February 3th, 1955 7 Claims. (Cl. 319-7) Electric arrangements intended for the loading at a high voltage of converters used for the ionizing chambers serving for the measure of ionizing radiations are constituted by chemical generators such as primary batteries or else by electromagnetic or electrostatic generators.

Electrostatic generators are either of the influence or of the friction type. Both show the drawback of not being reversible and in particular they do not allow any reduction in the voltage of the charges produced.

The problem of such a reduction appears for instance whenever in the loading of an ionizing chamber the voltage reached has become higher than that required for measuring the ionizing radiations.

My invention has for its object improvements in generators of electrostatic arrangements which improvements leading to the removal of such drawbacks consist in placing inside a cylindrical recess formed inside a block of insulating material a cylinder the diameter of which is smaller than that of the recess enclosing it, which cylinder may be driven into rotation in either direction and defines with said recess an annular chamber inside which is compressed an insulating material the nature of which is different from that of the cylinder so that the friction arising between the two insulating materials upon rotation of the inner cylinder leads to the production of electrostatic charges of opposite signs and said charges are collected by at least one electrically conductive brush which engages the stationary outer insulating block and the movable bearing constituted by the intermediate filling of insulating material, said brush being arranged in a manner such that, according to the direction of rotation of the cylinder, it collects either sign of electrostatic charges produced.

I have illustrated by way of example and by no means in a binding sense in the accompanying drawing a preferred embodiment of my improved generator of electrostatic charges. In said drawing:

Figs. 1 and 2 are perspective views of said generator showing two types of brushes which may be used therewith.

As illustrated, there is formed in an insulating block 1 a cylindrical recess the wall of which has a rough or uneven surface as provided e. g. by projections 6 or recesses 7. Inside said cylindrical recess is located an insulating cylinder 2, the diameter of which is smaller, the surface of said cylinder being in contradistinction smooth. In the annular gap formed between the cylinder and the wall of the cylindrical recess is inserted an insulating filling 3 the nature of which diflers from that of the cylinder so that the friction arising between said two insulating materials may lead to the production of static charges of opposite signs.

The intermediate insulating filling inserted in the annular above-mentioned gap is constituted for instance by curled and twisted filaments such as those obtained as shavings.

When the cylinder 2 is caused to rotate round its axis,

indicates said potential has been reached. operation the potential obtained is higher than the deits. P tented July 1957 the sections of the filament curls which are in contact with said cylinder are driven in the same'direction as the latter whereas the sections of the filaments which are in contact with the wall of the recess are held in position by the rough projections 6 or recesses 7 on said wall. As a result of this driving through the rotary cylinder and of their adherence to the stationary wall, the different curls and twists of the filaments of the filling are rocked and when this rocking is at an end, the rotary cylinder rubs over the cooperating sections of the filaments, which produces electric charges of opposite signs on the cylinder and on the filaments.

Metal brushes 4a, 4b, 5a, 5b are introduced into the annular space formed between the cylinder 2 and the recess in the block 1 and collect these electrostatic charges of opposite signs generated on the rotary cylinder and on the filaments.

To this end, each brush is secured to a stationary point outside the annular gap and has its free end loosely engaging said annular gap as in the case illustrated in Fig. l or else it is secured to two stationary points outside the annular gap and has a medial ear-shaped flexible section adapted to move inside said annular gap as illustrated in Fig. 2.

Thus, according to the direction of rotation of the cylinder with reference to the direction of the brushes engaging obliquely the gap, each brush collects the static charges generated with a predetermined sign. As a matter of fact, when the direction of rotation is such that it corresponds with the direction of the brush from its free end or fromits flexible medial section towards its corresponding stationary point, the slight drive of the filaments urges said free end or medial section of the brush against the surface of the cylinder which consequently collects the static electricity generated on the said cylinder. This is the case of the brushes 4a and 4b when the cylinder revolves in the positive anti-clockwise direction.

When, in contradistinction, the direction of rotation is such that it leads from the stationary point or points of the brushes towards their free ends or towards their medial sections as the case may be, the slight shifting of the filaments raises said free ends or medial sections of the brushes away from the cylinder and henceforwards the brushes do not collect the charges on the cylinder but the charges of opposite signs generated by the surfaces of the filaments.

This is the case for the direction of rotation in the positive anti-clockwise direction when the brushes 5a and 5b are to be considered, the angular setting of which is opposed to that of the brushes 4:: and 4b. This is also the case for the brushes 4a and 4b when the rotation of the cylinder is performed in the negative clockwise direction.

When the charges to be produced are small, it is possible to resort to only one brush, say the brush 4a which collects then the positive or the negative charges according to the direction of rotation of the cylinder 2. If it is desired to obtain simultaneously positive and negative charges, I resort to two brushes such as 4a and 5a extending in opposite directions or else to a plurality of such pairs of brushes such as do and 5a, 4b and 5b etc.

Under such conditions, the loading of an ionizing chamber is produced through a rotation of the cylinder andthe sign of said loading is defined by the direction of rotation.

When the loading is to be limited to a predetermined potential the rotation may be stopped at the very moment at which a measuring instrument such as an electrometer If during sired potential, it is sufiicient to make the cylinder. rotate in the reverse direction so as to lower the potential down to the desired value.

What I claim is:

1. A frictionally operating generator of electrostatic charges comprising a block of insulating material inside which is formed a substantially cylindrical rough-walled recess, a cylinder of insulatingmaterial of a smaller diameter than said recess and forming with the latter an annular chamber, an intermediate insulating filling inserted inside said annular chamber and the nature of which is dilferent from that of the cylinder, means for driving the cylinder into rotation selectively in either direction, the intermediate insulating filling adhering to the rough wall of the recess during the rotation of the cylinder and being subjected to a mere slight angular shifting upon a change in direction of the rotation imparted to the cylinder, the friction between the'material forming the cylinder. and that of. the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling, and means for collecting the electrostatic charges on at least one of the cooperating parts, the intermediate filling and the rotary cylinder.

2. A frictionally operating generator of electrostatic charges comprising a block of insulating material inside which is formed a substantially cylindrical rough walled recess, a cylinder of insulating material of a smaller diameter than said recess and forming with the latter an annular chamber, an intermediate insulating filling inserted inside said annular chamber and the nature of which is difi'erent from that of the cylinder, means for driving the cylinder into rotation selectively in either direction, the intermediate insulating filling adhering to the rough surface of the recess during the rotation of the cylinder and being subjected to a mere slight angular shifting upon a change in direction of the rotation imparted to the cylinder, the friction between the material forming the cylinder and that of the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling, and at least one brush secured to the outer stationary block and engaging the intermediate insulating filling and adapted according to the direction of rotation of the cylinder to be urged against the cylinder to rub against same and to collect the electrostatic charges produced on the latter, and to be shifted away from said cylinder and to collect the electrostatic charges formed in the intermediate filling.

3. A frictionally operating generator of electrostatic charges comprising a block of insulating material inside which is formed a substantially cylindrical rough walled recess, a cylinder of insulating material of a smaller diameter than said recess and forming with the latter I an annular chamber, an intermediate insulating filling insertedIinside said annular chamber and the nature of which is different from that of the cylinder, means for driving the cylinder into rotation selectively in either direction, the intermediate insulating filling adhering to the rough surface of the recess during the rotation of the cylinder and being subjected to a mere slight angular shifting upon a change in direction of the rotation imparted to the cylinder, the friction between the material forming the cylinder and that of the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling, and brushes adapted to collect selectively the charges produced on one of the corresponding parts, the cylinder and the intermediate filling according to the direction of rotation of the cylinder.

4. A frictionally operating generator of electrostatic charges comprising a block of insulating material inside which is formed a substantially cylindrical rough walled recess, a cylinder of insulating material of a smaller diameter than said recess and forming with the latter an annular chamber, an intermediate insulating filling inserted inside said annular chamber and the nature of which is different from that of the cylinder, means for driving the cylinder into rotation selectively in either direction, the intermediate insulating filling adhering to the rough surface of the recess during the rotation of the cylinder and being subjected to a mere slight angular shifting upon a change in direction of the rotation imparted to the cylinder, the friction between the material forming the cylinder and that of the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling, and a number of pairs of brushes the brushes of which form angles of opposite directions with the corresponding radius of the cylinder and are adapted to collect selectively the charges of opposite signs produced by the cylinder and by the intermediate filling.

5. A frictionally operating generator of electrostatic charges comprising a block of insulating material inside which is formed a substantially cylindrical rough walled recess, the surface of which is uneven substantially throughout its extent, a cylinder of insulating material of a smaller diameter than said recess and forming with the latter an annular chamber, an intermediate insulating filling inserted inside said annular chamber and the nature of which is different from that of the cylinder, said intermediate filling being retained in position by the un evenness of said recess surface, means for driving the cylinder into rotation selectively in either direction, the

friction between the material forming the cylinder and that of the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling, and means for collecting the electrostatic charges on at least one of the cooperating parts, the intermediate filling and the rotary cylinder.

6. A frictionally operating generator of electrostatic charges comprising a block of insulatng material inside which is formed a substantially cylindrical rough walled recess, a cylinder of insulating material of a smaller diameter than said recess and forming with the latter an annular chamber, an intermediate insulating filling inserted inside said annular chamber and constituted by curled and twisted filaments, the nature of which is difierent from that of the cylinder, means for driving the cylinder into rotation selectively in either direction, the intermediate insulating filling adhering to the rough surface of the recess during the rotation of the cylinder and being subjected to a mere slight angular shifting upon a change in direction of the rotation imparted to the cylinder, the friction between the material forming the cylinder and that of the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling, and means for collecting the electrostatic charges on at least one of the cooperating parts, the intermediate filling and the rotary cylinder.

7. A frictionally operating generator of electrostatic charges comprising a block of insulating material inside which is formed a substantially cylindrical rough walled recess, the surface of which is uneven substantially throughout its extent, a cylinder of insulating material of a smaller diameter than said recess and forming with the latter an annular chamber, an intermediate insulating filling inserted inside said annular chamber and constituted by curled and twisted filaments, the nature of which is different from that of the cylinder, said intermediate filling being retained in position by the unevennesses of said recess surface, means for driving the cylinder into rotation selectively in either direction, the friction between the material formingthe cylinder and that of the intermediate filling producing electrostatic charges of opposite signs on said cylinder and on said filling and a number of pairs of brushes the brushes of which form anglesof opposite directions with the corresponding radius of the cylinder and are adapted to collect selectively the charges of opposite signs produced by the cylinder'and by the intermediate filling.

Noreferences cited.

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