US2188288A - Arrangement for generating tilting oscillations - Google Patents

Description

Jan. 23, 1940. K. SCHLESINGER 2,138,233

ARRANGEMENT FOR GENERATING TILTING OSCILLATIONS Original Filed May 2, 1933 Jnvemor:

Patented Jan. 23, 1940 UNITED STATES ARRANGEMENT FOR GENERATING TILTING OSCILLATIONS Kurt Schlesinger, Berlin, Germany, assignor, by

mesne assignments, to Loewe Radio, Inc., a corporation of New York Original application May 2, 1933, Serial No. 668,940. Divided and this application February 16, 1934, Serial No. 711,572. In Germany May 2 Claims.

Discharge tubes are already known having a hot cathode, a grid and a gas filling of relatively high pressure (for example atmosphere). In these discharge tubes the grid does not act as a control element but as blocking element. As long as the control grid possesses a corresponding negative potential a discharge does not take place, however high the potential may be between the anode and the cathode. Immediately, however, the discharge-by shifting of the grid potential-has once commenced, the sameirrespective of any variation in the grid potentialcontinues as long as a potential exists between the cathode and the anode.

The subject matter of the invention is the use of these discharge tubes of the kind known per se, possibly in conjunction with known flash connection systems, for generating self-controlled (so-called free tilting oscillations) or foreigncontrolled (induced) tilting oscillations.

For the generation of foreign-controlled tilting oscillations the potential of the tilting condenser, which is charged in chronologically linear fashion, possibly with the assistance of a screening grid tube in the manner known per se, is, in accordance with the invention, applied to the correspondingly negative-biassed grid between the cathode and the anode and the control potential. For producing self-controlled tilting oscillations the control potential in accordance with the invention is derived from the tilting potential, for example by means of a potential divider connection system. Capacitative dividing of the potential is particularly suitable for the purpose of the invention. as leakage currents do not take place in connection therewith. Naturally, however, it is also possible to employ highly ohmic division of the potential, and if necessary also an inductive division of the potential.

Preferably, foreign control and self control may be combined with each other in the arrangement according to the invention. A combination of this character possesses the advantage that the tilting oscillation does not ceaseupon momentary failure on the part of the foreign control potential. This arrangement possesses particular advantages in connection with television receiving arrangements.

The arrangement according to the invention permits of the use of ignition potentials as desired, as the ignition potential in the case of a given. frequency depends solely on the extent of the charging current. The quenching potential is equal to 0. The tilting condenser is completely discharged. The arrangement permits of very exact control at the merely weakly negativebiassed grid. A further appreciable advantage of the arrangement resides in the fact that the same also enables relatively small ignition potentialsapproximately 150-200 voltsto be employed.

Other objects and embodiments of the invention will be more fully understood from the appended drawing, whereof Fig. 1 shows an arrangement for generating foreign controlled tilting potentials, whilst Figs. 2 and 3 show a peculiarly gas-filled, hot cathode, three electrode valve which may preferably be employed according to the invention.

In the drawing l is the discharge tube, which is filled with gas of approximately mm.-1 atmosphere, (the gas pressure depends on the peculiar gas the tube is to be filled with) having the hot cathode 2, the grid 3 and the anode 4. 8 is the grid bias battery. The control potential is represented in symbolical fashion of "9. 5 is the tilting condenser. At 6 and I there is fed the charging current, which serves for chronological linear charging of the tilting condenser 5 and may be produced by means of a screening grid tube.

The arrangement operates in the following manner: At first the condenser 5 is charged to the ignition potential, which may be selected as desired, and in the case of a given frequency depends only on the extent of the charging current. A discharge cannot take place so long as the grid 3 receives the requisite negative bias (for example, approximately .1, -10 or 20 volts) through the medium of the battery 8. At the moment when the negative-biassed grid has been raised by the control potential to a suiiiciently high potential the discharge commences. The

discharge continues until the condenser 5 has been completely discharged. The quenching potential is accordingly equal to "0. The tilting potential may be derived in immediate fashion at the condenser.

Though each kind of gas-filled, hot-cathode, three electrode tubes may be employed for the arrangement described, preferably tubes may be employed, which are constructed in such fashion that the cold glow discharge only takes place at potentials which are as high as possible.

For this purpose there is employed for all electrodes, and more particularly for the grid, a metal, preferably tungsten, with the greatest possible relieving work as building material. Gases having a high ionisation potential, and more particularly quicksilver, argon and nitrogen, have been found to be particularly suitable as filling gas. The pressure of the gas is preferably selected at, say, .12 mm. The most favourable working point is situated, generally speaking, at approximately 1 mm. pressure, if argon,

and 0.1 mm. if quicksilver. is employed.

According to the invention there is employed as a cathode one having a basic layer composed of alkaline earth metal oxide, for example barium oxide, which is furnished Withacoating of alkaline earth metal, such as barium, which may be applied for example by atomization. It has been found, that cathodes of this nature are particularly suitable for the present purpose, whilst the pure oxide cathodes become incapable of use after a short time. The cathode employed according 'to the invention possesses 'a considerably higher primary emission, and despite the cooling by the filling of gas requires only a verylow heating current, whereas ordinary oxide cathodes require very much greater heating for the same output. As regards the tube according to the invention, the use of indirectly heated cathodes is absolutely essential. In accordance with the invention, the cathode isconstruoted in such fashion that a discharge is reliably avoided between the emissive surface of, the cathode and the heating element. In particular, the insulation between the emissive surface and the heating element requires to be extremely good, at least in the direction from the emissive surface to the heating element. To avoid discharge between the emissive surface and the heating element either the filament may be completely embedded in. insulating material, or the; filamentmay' be provided with a weakly positive bias as compared'with the emissive surface. It is also possible to make the distance between the emissive surface and the filament smaller than the free distances of the filling gas under,- operative conditions. Naturally, it is further possible to combine the stated measures wholly or in part with each other. The fact that metallic vapour cathodes under the working conditions concerned arerelatively insensitive, i. e.', possess a longer life, is unexpected insofar as on the basis of previous knowledge it was to be assumed that exactlymetallic vapour cathodes possess. a very considerable sensitiveness as compared with the drumming effect.

The grid of the tube according to the invention is constructed in such fashion that the same does not reveal, any natural emission. For this purposethe grid is so constructed that it possesses considerable heat-radiating surfaces, so that under all circumstances the grid temperature is situated below that temperature at which the material of the grid discloses a natural emission of appreciable amount in practice. The large grid-cooling surface employed according to the invention is of particular importance insofar the grid upon the arc discharge is subjected to a very considerable heating, and 'in an exceptionally short space of time again requires to be cooled down to a temperature at which no kind of natural emission can take place.

It has been found that it is expedient to employ tubes having an exceptionally small reciprocal of the amplification factor (approximately /1oon%5%). According to-the invention, there may be employed the known amplification systems with rotary cylindrical embodiment of the electrodes. It is particularly convenient, however, to employ a system as illustrated diagrammatically byway of example (Figs. 2 and 3).

In the tube I there is provided a grid cylinder 3 which is closed on all sides and is furnished with a tube-like abutment 5, through the opening of which the electrons are able to pass out into the inner space of the tube. In the grid cylinder 3 there is provided the cathode 2. The anode 4 is constructed as a circular ring which is placed about the tube-like abutment 5 at a certain distance from the aperture thereon The, diameter of the grid cylinder may be approximately 10 mm., its length approximately 30 mm. The diameter of the aperture of the tubular member is in this. case preferably 1 mm., the diameter of the anode ring 10 mm. The light metal applied to the cathode by atomization may be arranged in the grid cylinder itself; or it is also possible to provide the metal to be atomized in a special container, which possesses an opening corresponding with an opening in the grid cylinder, and is arranged in such fashion that it completely covers this metal vapour inlet aperture of the cylinder. The cathode 2, as set forth in detail in the above, is constructed as an indirect cathodaand for the sake of facilitated comprehension, is: illustrated in the form of asimple filament with return wire. I

The electrode leads within the tube are situated as wide as possible apart, :andin this connection the spacing of the anode lead from the grid and cathode leads willpreferably be made larger than the relative spacing of the gridand cathode leads. In accordance with the invention, all leads may conveniently. be'furnished within the tube with an insulating layer or screening means. The grid cylinder. itself may also be coatedv with an insulating layer, more particularly on'its outer face directed towards the interior of, the tube, and if necessary also on the inside, of the tube-like abutment.

For screening off the impulse, energy occurring in the tube, and also for screening ofi external fields of disturbance, both the bulb of the tube as well as the baseare completely screened off. For the purpose of the. invention the bulb and the base may be metallizedin the manner known per se. The leads are passed out through narrow borings in the metallized'base. The passage ways, after the leads have been passed through, may conveniently also be screened off additionally; v

The use of the connection systems according to the invention enables completely even synchronisation to. be obtained and to reduce the return period .to such extentthat the return line is, almost entirely invisible.

,, This application is .a division of domestic application Number 668,940, filed May 2, 1933, and now Patent Number 2,083,202, issued June 8, 1937.,

I claim: v

1. A gaseous ,discharge device comprising a container, a .gasin said container, an indirectly heated cathode, a gridelectrode consisting of a metallic cylinder closed at one end having a tubelike abutment thereon, said grid electrode surrounding said indirectly heated cathode, and a ring-shaped anode surrounding said tube-like abutment of said grid electrode.

2. A gaseous discharge device comprising a container, a gas in said container, an indirectly heated cathode, a grid electrode consisting of a metallic cylinder closed at one end, having a tube-like abutment thereon, said grid electrode surrounding said indirectly heated cathode, and a ring-shaped anode surrounding said tube-like abutment of said grid electrode, the diameter of said anode being much greater than the diameter of said tube-like abutment.

KURT SCI-ILESINGER.

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