US2213275A

US2213275A - Electrical oscillation generator

Info

Publication number: US2213275A
Application number: US160809A
Authority: US
Inventors: Gloess Paul Francois Marie
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1936-09-19
Filing date: 1937-08-25
Publication date: 1940-09-03
Anticipated expiration: 1957-09-03
Also published as: GB505269A; FR823070A

Description

Sept. 3, 1940. P. F. M GLQESS ELECTRICAL OSGILLATION GENERATOR Filed Aug. 25, 1937 2 Sheets-Sheet 1 Fig. 3.

- Fig. 4.

ArromvEr Sept. 194G- P. F. M. GLOESS 2,213,275

ELECTRI CAL O S C ILLATION GENERATOR Filed Aug. 25, 1937 2 Sheets-Sheet 2 Patented Sept. 3, 1940 2,213,275 ELECTRICAL OSCILLATION GENERATOR,

Paul Francois Marie Gloess, Paris, France, assignor to International Standard Electric Gorporation, New York, N. Y.

Application August 25,

1937, Serial No. 160,809

In France September 19,1936

2 Claims.

The invention relates to circuits for producingor employing oscillations of saw tooth or other similar predetermined forms. Such forms of oscillations are commonly employed to control the potentials applied to the deflecting plates of the cathode ray tubes so as to cause a surface to be scanned in accordance with a given law, by' a cathode ray.

The circuits forming the subject of the present'invention are applicable in particular to the production of symmetric deflecting potentials. They may be employed with cathode ray tubes having either one or two electrostatic deflection systems and are particularly applicable to the case of 'a tube with a high vacuum requiring symmetrical deflecting potentials and, more particularly, to television receivers or to oscillog-raphs employing such tubes.

Arrangements according to the invention have, inparticular, the advantage of directly producingsymmetric and opposite saw tooth potentials withoutthe' intermediary of amplifier or dephasing tubes.

According 'to' the invention a condenser associated-with a discharging" device is charged over two equal resistances each connected at one end tonnearmature of the condenser and at the other? endto a source of potential.

The inventionis set forth in more detail in the following description based onthe accompanying drawings in which:

Fig. 1 represents'a schematic arrangement of a: circuit employing features of the invention comprising a condenser C associated with a discharge. device;

-Figs.-.2.and 3 represent curves showing the variation of the potentials in function oftime atthe terminals of thecondenser C;

Fig. 4.- shows one application of the circuits forming the subject of the invention to one of the deflecting systems of a cathode ray tube;

' Fig. 5 represents a modification of the arrangement of the discharge tube employed in Fig. 4;

Fig. 6 shows an embodiment of the invention applied to a television receiver.

The circuit of Fig. 1 comprises a condenser 0, two loading resistances R1 and R2 of equal value connected, on the one hand, to a source of direct tension and, on the other hand, to the two armatures-of the condenser C. To the terminals of thecondenser C is: connected a discharge device for causing the rapiddischarge of the condenserC at regular time intervals. These intervals may be defined either by the period of the system-itself, or by: means: of an external control device, which operates, for example, by applying suitable impulses to the discharge device.

The operation of this arrangement is as follows: we will first of all imagine the condenser C discharged and the source of potential E disconnected from the circuit. The armatures A and B of the condenser are then at the same tension which will be taken as the origin. The source E then being connected, a charging current is produced in the circuit which will tend to charge the condenser C to the tension E. The two armatures A and B of the condenser will take equal charges but of oppositesigns which will increase in accordance with an exponential law, as shown in the curves VA and VB of Fig. 2. At the end ofa-sufliciently long period the potentials of these two armatures will have taken respective values very close to The discharge device V, when it operates, short-circuits the two armatures of the condenser C and causes its almostinstantaneous discharge. I

The battery E remaining in the. circuit and the discharge device-short-circuiting periodically the armatures of the condenser C, the potentials of its armatures VA and VB vary'periodically in accordance with a law which may be considered asbeing in symmetricalsaw tooth form as shown in Fig. 3.; It is sufficient to choose the constants of the circuit in such awaythat the fraction of the charging curve of each period approximates to astraight line.

The-release deviceV may consist either of a vacuum tube with three or more electrodes, or of two or more vacuum tubes suitably interconnected, or again of a gas discharge-tube with cold or hot cathode with two or more electrodes, or in any other arrangement fulfilling the same function. a

The variable saw tooth potential collected at the terminals A and. B of the condenser may be employed, for example, in deflector systems of a cathode ray tube as shown in Fig. 4 in which the circuit of Fig. 1 serves to produce the sweep potentials of one of the deflecting systems of a television receiver. The deflecting circuit then comprises the condenser C, the resistances R1 and R2 of equal value and the'triode gas discharge tube V. The grid of this tube is negatively polarised by means of the resistance R3 through the primary winding of the transformer T1 while an anode resistance R4 limits the dischargecurrent of the tube.

The terminals A and B of the. condenser are respectively .connected through the condenser CA-2111C]. CB to the deflecting plates. Pxi and Pxz ofthecatho'de'ray tube whose anode A12. is brought to the mean potential of the plates by means of the resistances RA and Re.

The saw tooth potentials obtained at A and B are transmitted to the deflecting plates Pxl. and Pxz through the condensers CA and CB, respectriode V, a hard vacuum tube with three or more electrodes may be employed. For example, as.

shown in Fig. 5, such a vacuum tube may be employed provided with a positive reaction coupling, for reducing the period of discharge. This coupling as shown comprises a transformer T one of the windings of which is connected between the plates of the valve V and the terminal A and the other winding between the grid of the tube and the upper end I) of the primary of the transformer T1 of Fig. 4.

Fig. 6, to which we will now refer, shows a television receiver circuit employing features of the invention. In the embodiment shown in the drawings, the high tension supply comprises a rectifier tube Rv which rectifies alternating current thus supplying the necessary power which is filtered by means of two shunt condensers CF associated with a series resistance RF. The variouselectrodes of the cathode ray tube K are fed between the wires I and 2 by means of a potentiometric system comprising the adjustable resistances P1 and P2 and the fixed resistances R and R to which are suitably connected the anodes A1 and A2, the grid G and a point F of the cathodic filament. The signal modulation is applied at M through a condenser CM. Resistances RE and RE are also connected in series with the potentiometric system mentioned and connected to terminals E and E to which may, respectively, be connected one plate of each pair of plates Px1, Pxz, and Pm, PYZ in order, if necessary, to adjust the outlining of the image or the centering of the image on the screen of the cathode tube.

Two circuits similar to that described with reference to Fig. 4 and both employing gas discharge tubes VX and W, provide the horizontal and vertical deflecting potentials. Two condensers CX and CY fulfil the same function as the condenser C of Fig. 4. These condensers are respectively associated with the tubes VX and W and with the resistances, R1, R2, and R5, R6. The plate circuits of the tubes VX and W comprise resistances R4 and Rs, respectively, and their grid circuits include biasing resistances R3 and R which may or may not be adjustable.

The condenser-valve discharge units have their terminals A, B and C, D respectively connected to the pairs of deflecting plates Pm, Pxz and Pan, PY2 whose connections are the same as in Fig. 4, and comprise condensers CA and CB and anode resistances RA and RB, on the one hand, and condensers Cc and CD and anode resistances Re and RD on the other hand. Synchronising impulses are applied at S1--S1 to the terminals of the primary of the coupling transformer T1 for the horizontal deflection, and at Sz-Sz to the terminals of the primary of the coupling transformer T2 for the vertical deflection.

' It is obvious that this television receiver arrangement has only been described by way of example, and that otherembodiments employing features of the invention can be carried out without departing from the scope of the invention.

What is claimed is:

1. In a television receiver, a cathode ray tube having a cathode, an anode and two deflector plates; a common source of direct current having a positive terminal and a negative terminal;

' a condenser having two armatures; a galvanic connection including a first ohmic resistance connecting one armature with said positive terminal; and another galvanic connection including a second ohmic resistance of substantially the same value as said first resistance connecting the other armature with said negative terminal whereby substantially the full potential of said common source is applied through said two resistors in series to charge said condensers substantially symmetrically with respect to the midpoint of said source; means for periodically rapidly discharging said condenser, whereby the potentials of said armatures undergo symmetric saw tooth variations; two capacitative connections from said two armatures to said two deflecting plates respectively for transmitting to said plates only the symmetric potential variations of said armatures; high impedance galvanic connections from said two plates to said positive terminal for maintaining said plates at a mean direct current potential close to that of said positive terminal; and two galvanic con-'- nections from said positive and negative terminals to said anode and cathode respectively for applying therebetween at least substantially the full potential of said common source.

2. In a television receiver, a cathode ray tube having a cathode, an anode and two deflector plates; a'common source of direct current including rectifier means for producing a direct current and a potential divider connected there.- across; a condenser having two armatures;. a'gal vanic connection including a first ohmic resistance connecting one armature with a point substantially adjacent the positive end of said divider; and another galvanic connection including a second ohmic resistance of substantially the same value as said first resistance connecting the other armature with a point substantially adjacent the negative end of said divider whereby substantially the full potential of said common source is applied through said two resistors in series to charge said condenser substantially symmetrically with respect to the mid-point of said divider; means for periodically rapidly discharging said condenser, whereby the potentials of said armatures undergo symmetric saw tooth variations; two capacitative connections from said two armautres to said two deflecting plates respectively for transmitting to said plates only the symmetric potential variations of said armatures; high impedance galvanic connections from said two plates to a point substantially more positive than the mid-point of said divider for maintaining said plates at a mean direct current potential more positive than said mid-point; and two galvanic connections from points substantially adjacent the positive and negative ends of i said divider to said anode and cathode respectively for applying therebetween at least suba stantially the full potential of said common source.

PAUL FRANCOIS MARIE GLOESS.