US2147559A

US2147559A - Transformation of relaxation oscillations

Info

Publication number: US2147559A
Application number: US106021A
Authority: US
Inventors: Schlesinger Kurt
Original assignee: Loewe Opta GmbH
Current assignee: Loewe Opta GmbH
Priority date: 1935-10-25
Filing date: 1936-10-16
Publication date: 1939-02-14
Anticipated expiration: 1956-02-14
Also published as: GB483667A; FR812496A; NL48965C; BE418067A; DE740131C

Description

Feb. 14, 1939. K SCHLESINGER' 2,147,559

TRANSFORMATION OF RELAXATION OSCILLATIONS Filed Oct. 16, 1936 Patented Feb. 14, 1939 UNITED STATES TRANSFORMATION OF RELAXATION OSCILLATIONS Kurt Schlesinger, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Loewe, Berlin- Steglitz, Germany Application October 16, 1936, Serial No. 106,021 In Germany October 25, 1935 8 Claims.

The invention relates to a' relaxation oscillation generator supplying the deflecting voltage for a cathode ray tube.

An object of the invention is the use of a transformer coupling between relaxation oscillation generator and the deflecting systems of the cathode ray tube. Such a transformer coupling in view of the low deflecting power of the Braun tube is able to effect a considerable increase in the deflecting potential. The internal resistance between the deflecting plates of a cathode ray tube may amount to approximately 10 ohms and the deflecting power in respect of several hundred volts deflecting potential only amounts to a few tenths of a watt. If, therefore, approximately 10 Watts are employed on the primary side, a

\/ 10-fold potential amplification is conceivable. Amplitudes of the order of 10 volts are accordingly sufiicient on the primary side, which renders possible in the case of relaxation apparatus the use of anode batteries of low potential. I

The present invention deals with the question of a form of relaxation oscillation which is devoid of error. It is not a readily possible matter to transmit a relaxation oscillation true to form by way of a transformer.

Fig. 1 shows a conventional circuit arrangement for coupling a relaxation oscillator amplifier to an inductive load.

Figs. 2 and 3 show' arrangements embodying the invention. I

In the drawing Figs. 2 and 3 show" arrangements for performing the invention. In Fig. 1 the end stage I is connected at the grid with a relaxation oscillation generator 2. It possesses an internal resistance 3 (Bl). The transformer 4 possesses an impedance composed of ohmic resistance 5 and inductive reactance 6. If it were possible to apply to the primary terminal of the transformer .an undistorted relaxation potential of the form of curve of the generator 2, a transformation true to form would'be capable'of being performed. The secondary potential would have the value e,-Ma (1) and the current would have a form of curve differing greatly to the relaxation curve. The integral curve of the primary potential would be operation of the amplifier. It is only to be obtained when the apparent resistance of the transformer is very large as compared with the internal resistance of the tube. By the use of tubes without screening grids, i. e., of 3-electrode tubes with large reciprocal of the amplification factor andlarge steepness, that is to sayfismall internal resistance, the condition of idle operation may be very closely approached. Actual accomplishment of idle operation is impossible in practice, as it is difiicult to make the transformers so large that they operate solely with potential excitation and with very small primary current.

The subject matter of the inventon is a circuit which supplies appreciable relaxation oscillations even in the case of small current-excited transformers. In this circuit the potential excitation of the relaxation apparatus itself is distorted in the manner according to the invention (see below), whereby the transformer distortion is compensated. The power amplifier I, in accordance with the invention, is already excited in a distorted relaxation curve.

By Way of explanation there is taken the extreme case of a small transformer, the apparent resistance 5 (Ra) of which is small as compared wlth the internal resistance (Ri) of the tube l. The transformer then operates in a current-confining tube, which by way of the same is apparently shcrt-circuited (case of shortcircuit). In this case the current it is an undistorted relaxation curve, and according to Formula (l) the transformer provides on the secondary side the differential curve of the primary current curve, which is unsuitable for television purposes.

Actually the state of operation is always something in between idle operation and short-circuit. The terminal potential of the transformer then consists of a purely ohmic and an inductive component. There is accordingly connected with the anode of the amplifying tube I a potential according to the following Equation (3) According to Formula (1), the secondary popose of being able to derive a clean relaxation curve from the secondary of the transformer.

The Formula (4) supplies the condition for the form of curve of the grid alternating potential with which the amplifier requires to be excited. It Will be seen that this grid alternating potential may not have a pure relaxation curve form. It is not sufiicient to add the expression B't. This would merely suffice for no-load operation. The short-circuit value A-f must also be included, and it must be added in a ratio to the undistorted grid potential which is determined by the circuit. The short-circuit value, according to Equation (i), is the integral of the relaxation oscillation. According to the invention, the grid excitation of the power amplifier I is composed of an undistorted relaxation potential curve and a superposed integral of this relaxation potential curve.

Fig. 2 shows a circuit which enables the Equation (4) to be fulfilled in practice. The second integration of the relaxation curve is effected in this circuit by charging a condenser. An anode battery I charges a first condenser 9 by way of a resistance 8. This charging takes place with constant current so long as the charging potential at 9 remains small as compared with the mains potential I. If, for example, the resistance 8 is made=l00,000 ohms and the condenser 9:1;if, the maximum potential at 9 in the case of a relaxation frequency of 25 cycles per second will be 30% of 7, and the time curve of the charging potential of the condenser may be regarded in first approach as linear curve. There are accordingly obtained at 300 volts mains potential relaxation oscillations of approximately 100 volts amplitude and linear form. (Naturally a still better linearity may be obtained by not allowing the con.- denser potential to become quite so high.) The integration at this undistorted relaxation curve called for by the Equation l) is performed by the fact that a second resistance I charges a second charging condenser II. The resistance III is made approximately ten times greater than the resistance 8, whilst the time constant of the circuit comprising resistance In and condenser Ii, of the so-called integration circuit, is selected to be, with the same requirements for linearity, just as great as the time constant of the first circuit comprising resistance 8 and condenser E. There may accordingly be selected, for example: resistance 3:10 ohms, condenser II=0.l f. In this case the current flowing in the integration circuit is neglegible for the primary circuit 8/3. The potential at the condenser II increases parabolically when the potential at the condenser 9 increases in linear fashion. By displacement of a tapping I2 over the resistance It] a suitable fraction of the two condenser potentials 9 and I I may be adjusted and conducted tothe control grid of the tube I. The tube I is then so strongly negatively biased, preferably by the battery I3, that it operates without grid current. The anode circuit of the tube is connected with the relaxation transformer 4. In specific instances it is very important to construct the transformer 4 as push-pull transformer. This instance exists in the case of high-vacuum tubes with simple and with double electrostatic deflection. The pushpull operation ensures constant sharpness of the image point at the edge of the image. It may also be of advantage to make the insulation between the primary winding 4a and the secondary winding 41) of the transformer 4 proof against high tension. The inner core of the transformer should be so dimensioned that saturation by the emissive current of 1 is avoided. It is naturally also possible by employing two power amplifier stages I already to perform push-pull operation on theprimary side and in this way to avoid saturation of the transformer iron core.

The discharge of the condensers 9 and H may be effected by means of a discharge tube I2, which in the condition of charge is blocked by negative bias I4 and is 'made conductive by the synchronisation impulses. There may also be employed two discharge tubes I2 and I2a for each of the two condensers 9 and II, the grid of which may be connected in parallel. When operations are performed with one single discharge tube I2 a bridging condenser I5 may be useful, which is so small that it does not aifect the charging operation but upon the discharge causes a more rapid discharge of the condenser II and accordingly an improvement in the return speed. In the present case I5 might amount to approximately 0.01m.

In-place of high-vacuum discharge tubes I2 there may also be employed with advantage gasfilled hot cathode tubes, which have the property of igniting and thus discharging automatically after a maximum potential, which is adjustable by their grid, has been reached.

In Fig. 2 the integral circuit comprising resistance I0 and condenser I I is connected directly with the first charging circuit comprising resistance 8 and condenser 9. Naturally the potential distortion according to the invention in accordance with Equation (4) may also be performed in separate circuits and subsequently added together. a

In Fig. 3 there is shown a circuit diagram of this kind, in which the charging circuit comprising resistance 8 and condenser 9 is separated from the integral circuit comprising resistance I0 and condenser II by a tube l5. The tube I5 receives its anode potential by way of a potential resistance I6, which is small in relation to the resistance I0. By means of a potentiometer Ifla a mixing of the potential of the two condensers may be performed in desired ratio with the aid of a sliding contact I2, and this mixture in accordance with Equation (4) passed to the end tube I and the transformer 4. Numerous other circuits are also possible, which make use of the method of integration of the undistorted relaxation curve according to the invention.

In a practical embodiment of Fig. 2 with an RE134- as output valve it. was possibleto perform push-pull transformation 1' to 10, in which it was successful in obtaining an exact image point with 400 volts relaxation amplitude by the use of an anode battery 1 of merely 300 volts and with an anode current of merely 5 ma. The power requirement for this relaxation apparatus, which operated with .a gas-filled grid controlled discharge tube I2, accordingly amounted to only 1.5 W. In comparison therewith constructions without relaxation transformation with resistance amplification at 1,000 volts anode potential required 20-30 ma., i. e., more than ten times the stated power.

I claim: I V

1. An arrangement for producing deflecting voltages of saw-tooth 'wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation'oscillation generator having input and output terminals, a transformer having a primary and a secondary winding, means for integrating the potential occurring at said output terminals, means for superimposing said integrated potential on said output potential and means for applying said superimposed potentials to said primary winding, said secondary Winding being connected to the deflecting system of said cathode ray tube.

2. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator having input and output terminals, an electronic amplifier, a transformer having a primary and a secondary winding, means for integrating the potential occurring at said output terminals, means for superimposing said integrated potential on said output potential and means for applying said superimposed potentials to the input of said electronic amplifier, the output of said electronic amplifier being connected to said primary Winding, said secondary winding being connected to the deflecting system of saidcathode ray tube.

3. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator having input and output terminals, an electronic amplifier, a transformer having a primary and a secondary winding, a resistance and a condenser, the potential occurring at said output terminals being supplied through said resistance to said condenser, means for superimposing the potential formed on said condenser on said output potential and means for applying said superimposed potentials to the input of said electronic amplifier, the output of said electronic amplifier being connected to said primary winding, said secondary winding being connected to the deflecting system of said cathode ray tube.

l. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator having input and output terminals, an electronic amplifier, a transformer having a primary and a secondary winding, a potentiometer resistance, a tapping point on said potentiometer resistance and a condenser, the potential occurring at said output terminals being applied through said potentiometer resistance to said condenser, the tapping point of said potentiometer resistance being connected to the input circuit of said electronic amplifier, the output of said electronic amplifier being connected to said primary winding, said secondary winding being connected to the deflecting system of said cathode ray tube.

5. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator including a charging condenser and a grid-controlled high vacuum discharge tube, an electronic amplifier, a transformer having a primary and a secondary winding, a potentiometer resistance, a tapping point on said potentiometer resistance, a second condenser and a second grid controlled high vacuum discharge tube for discharging said second condenser, the potential occurring at the terminals of said first charging condenser being applied through said potentiometer resistance to said second condenser, the tapping point of said potentiometer resistance being connected to the input circuit of said electronic amplifier, the output of said electronic amplifier being connected to said primary winding, said secondary Winding being connected to the deflecting system of said cathode ray tube.

6. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator including a charging condenser and a grid controlled gasfilled discharge tube, an electronic amplifier, a transformer having a primary and a secondary Winding, a potentiometer resistance, a tapping point on said potentiometer resistance, a. second condenser and a second grid controlled gas-filled discharge tube for discharging said second condenser, the potential occurring at the terminals of said first charging condenser being applied through said potentiometer resistance to said second condenser, the tapping point of said potentiometer resistance being connected to the input circuit of said electronic amplifiers, the output of said electronic amplifier being connected to said primary Winding, said secondary winding being connected to the deflecting system of said cathode ray tube.

7. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator including a charging condenser and a grid-controlled high vacuum discharge tube, an electronic amplifier, a transformer having a primary and a secondary winding, a potentiometer resistance, a tapping point on said potentiometer resistance, a second condenser and means for discharging said second condenser through said discharge tube of said first condenser, the potential occurring at the terminals of said first charging condenser being applied through said potentiometer resistance to said second condenser, the tapping point of said potentiometer resistance being connected to the input circuit of said electronic amplifier, the output of said electronic amplifier being connected to said primary winding, said secondary winding being connected to the deflecting system of said cathode ray tube.

8. An arrangement for producing deflecting voltages of saw-tooth wave form for deflecting the cathode ray in a cathode ray tube comprising a relaxation oscillation generator including a charging condenser and a grid controlled gasfilled discharge tube, an electronic amplifier, a transformer having a primary and a secondary winding, a potentiometer resistance, a tapping point on said potentiometer resistance, a second condenser and means for discharging said second condenser through said discharge tube of said first condenser, the potential occurring at the terminals of said first charging condenser being applied through said potentiometer resistance to said second condenser, the tapping point of said potentiometer resistance being connected to the input circuit of said electronic amplifier, the output of said electronic amplifier being connected to said primary Winding, said secondary Winding being connected to the deflecting system of said cathode ray tube.

KURT SCHLESINGER.