US2309672A - Cathode ray beam deflecting circuit - Google Patents

Cathode ray beam deflecting circuit Download PDF

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Publication number
US2309672A
US2309672A US325207A US32520740A US2309672A US 2309672 A US2309672 A US 2309672A US 325207 A US325207 A US 325207A US 32520740 A US32520740 A US 32520740A US 2309672 A US2309672 A US 2309672A
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United States
Prior art keywords
tube
current
circuit
resistance
cathode ray
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Expired - Lifetime
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US325207A
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English (en)
Inventor
Otto H Schade
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RCA Corp
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RCA Corp
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Publication date
Priority to NL102938D priority Critical patent/NL102938B/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US325207A priority patent/US2309672A/en
Priority to NL102938A priority patent/NL84973C/nl
Application granted granted Critical
Publication of US2309672A publication Critical patent/US2309672A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K4/00—Generating pulses having essentially a finite slope or stepped portions
    • H03K4/06—Generating pulses having essentially a finite slope or stepped portions having triangular shape
    • H03K4/08—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape
    • H03K4/10—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only
    • H03K4/26—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor
    • H03K4/28—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor using a tube operating as a switching device

Definitions

  • This invention relates to an improvement in circuits for producing voltage variations for causing deflection of the cathode ray beam produced in a cathode ray tube. More particularly, the invention is concerned with circuits to be used in television transmitting or receiving systems wherein the electron beam of a cathode ray tube is deflected horizontally at a relatively high rate.
  • cathode ray beams in television receivers are preferably deflected by electromagnetic means, a large deflecting voltage variation is reignad in order to produce the necessary current changes in the deflecting coil for producing the required change or flux for deflecting the cathode ray beam and particularly for returning the cathode ray beam in a relatively short space of time.
  • the cathode ray beam which is produced in the re-- celving tube is deflected vertically at the rate of hill deflections per second, i ti (or more) of the time for each cycle being used for deflecting the beam in one direction vertically, and the remaining 1% (or less) of the cycle being used for returning the beam to its initial starting point.
  • the cathode ray beam is deflected horizontally at the rate of 13,230 cycles per secend, 1% (or more) of the time for each cycle being required to deflect the beam in one direction horizontally, and the remaining portion of the cycle being used to return the beam to its initial starting point.
  • the return time be less than /500 of a second for the vertical deflections, and less than ;132300 of a second for horizontal deflections, if possible.
  • variations for deflecting the beam are produced by a powerful amplifier tube of the beam power type working in conjunction with a diode for assisting in producing a more linear change in the voltage variation.
  • Another purpose of the present invention resides in the provision of a cathode ray beam defleeting circuit which will produce substantially In presently used television circuits, the high voltage Such circuits require rather delicate adjustments, and at best do not linear voltage variations over the desired portion of the deflection cycle.
  • Still another advantage of the present invention resides in the provision of a simple arrangement whereby a. certain portion of the voltage developed by a rectifier tube or diode is superimposed upon the control electrode of the power I amplifier tube in opposition to the voltage normally applied to this electrode so that an increased efficiency will be obtained from the power amplifier tube.
  • a still further purpose of the present invention resides in the provision of means whereby the distribution or linearity of the voltage variation may be readily controlled so that the circuit may be easily adjusted after the receiver has been completed.
  • Figure 1 represents a deflection circuit similar to those now in use
  • Figure 2 shows a schematic representation of the circuit shown in Figure 1;
  • FIG. 3 shows a cathode ray beam deflection circuit constructed in accordance with the purposes of the present invention
  • Figure 4 shows a series of curves representing the current decay time of the diode as a function of the potential opposing such change
  • Figure 5 shows a family of curves representing the current decay time of the rectifier or diode as a function of the ohmic resistance of the circuit
  • Figure 6 shows a series of curves representing the current and voltage variations at various points in the circuits shown in Figures 1 and 3;
  • FIG. 7 shows graphically the results which are accomplished by using the circuit shown in Figure 3
  • the circuit includes a discharge tube ill, a power amplifier tube it, and a damping tube It.
  • the discharge tube includes a cathode, a control electrode i6, and an anode IS.
  • the cathode of the discharge tube Ill is preferably connectedto ground, and the control electrode It of the tube is connected to ground through an adjustable resistance or potentiometer 2
  • the anode i8 is connected to a source of positive potential through an adjustable resistance or potentiometer 22.
  • the control electrode of the discharge tube I is supplied with controlling or synchronizing impulses which are impressed between the control electrode and the cathode, and these controlling or synchronizing impulses, in the case of a television receiving apparatus, are generally transmitted from the transmitting station along with the picture signals.
  • the exact circuit used in connection with the discharge tube i0 is not vital to the present invention, since any type of a deflection or saw-tooth voltage wave form generator may be used.
  • Various forms of relaxing oscillators, blockingoscillators and multivibrators have successfully been used for producing the desired saw-tooth wave forms of low voltage variations. It is desirable, however, that the oscillator or saw-tooth wave form generator be controllable as to its speed of operation and a variation in the amount of the resistance 2
  • the amplitude of the voltage variation as derived from the anode of the tube Hi should be controllable in order to vary the amount of horizontal deflection of the cathode ray beam, and by adjusting the value of the resistance 22, the amplitude of the voltage variation at the anode it of the tube iii may be controlled.
  • the voltage variations which exist at the anode it of the tube iii are impresed upon the control electrode M of the amplifier tube l2 by means of a coupling condenser 26.
  • the control eectrode is connected to ground by way of the grid resistance 26.
  • the cathode of the amplifier tube 12 is connected to ground by way of resistance 32 which is by-passed by condenser iii. This resistance is used in order that proper voltage relationships may exist between the control electrode and the cathode of tube l2.
  • the tube i2, as stated above, is generally of th beam power type. and may be a tube such as the SL6 or the 6V6 type.
  • the screen grid of the power tube is connected to a source of positive potential, and the beam forming electrodes are, of course, connected to the cathode as is conventional in beam type tubes.
  • the anode 36 of the tube i2 is connected to one end of the primary winding 3% of the output transformer it, while the other end of the primary winding is connected to a source'oi" positive potential.
  • the secondary winding 32 of the outi put transformer it is connected to the deflecting coils M which surround the, neck of the cathode ray tube in order that the cathode ray beam may be deflected by the electro-magnetic flux which is produced thereby.
  • a diode or damping tube i l Connected in parallel with the primary winding 38 of the output transformer M, is a diode or damping tube i l and a resistance and condenser combination.
  • the cathode of the damping tube is connected to the anode of the power amplifier tube I2 while the anode of the damping tube It is connected to the source of positive potential by means of a variable resistanc M, the resistance being shunted by a condenser flit.
  • the portion of the circuit shown in Figure 1, including the power amplifier tube l2, the damping tube It and the primary of the output transformer 38 may be resolved into a simplified schematic showing such as disclosed in Figure 2 of the drawings.
  • the power amplifler tube I2 is shown substantially identically as it is shown in Figure 1, as is also the damping tube Mi.
  • the inductance of the deflection coils as reflected into the anode circuit of tube [2 is shown at 38a, while the reflected resistance component is represented by the resistance R0.
  • the condenser C shown in Figure 2 represents the total reflected and shunt capacity in the anode circuit of tube 12.
  • the resistance Rd of Figure 2 represents the eifective resistance of the diode or damping tube it, while the source of potential E represents the voltage which is developed across the resistance it during the operation of the circuit shown in Figure 1.
  • the polarity of this source of potential, as well as the polarity of the anode potential for the tube i2 are shown in the figure.
  • the damping tube M By using the damping tube M, these oscillations are prevented and the damping tube or diode, in view of its connection in the circuit and the effect of the potential E, operates as a switch which closes at the end of the return time, i. e., at the beginning of the initial horizontal deflection cycle.
  • One cycle of operation is represented by the time T shown in Figure 6, while the return period is indicated by the time Tr in Figure 6.
  • the switching operation of the diode or damping tube It: causes transient currents to flow in the circuit 38a, Re, Rd and i l of Figure 2. This transient current if of correct magnitude and wave form assists the tube l2 in causing the desired current changes in the primary of the output transformer, and assists to a large extent in improving the efficiency of the circuit.
  • the damping tube current wave form must be given such a shape and the power tube bias must be so adjusted that the geometric sum of the plate current of the power tube l2 and the diode current of the tube it, is a straight line. Unless this condition does exist, very undesirable distortions may result in the picture as a result of non-linear deflection of the cathode ray beam in thehorizontal direction. Normally, in circuits such as shown in Figure i, it is desirable that the diode current be stretched over substantially the full time occupied by the horizontal deflection cycle because a sumciently slow diode cutoti is dimcult to obtain due to the value of resistance Re.
  • the above described circuit may be improved in operation and emciency, and the linearity of the deflection may be improved, if a certain amount of feedback is permitted from the damping tube It to the input electrode of the power amplifier tube. 12.
  • Such a circuit is shown in Figure 3 of the drawings. This circuit is similar in many respects to the circuit shown in Figure 1, except/that the condenser 30, which is connected between the anode It of tube It and ground in Figure l, is replaced by condenser Mia and a variable resistance ill.
  • a resultant linear characteristic and improved efficiency could be obtained by modifying the shape of the current wave form of the damping tube it or of the power tube it to supplement the other. If these two wave forms can be so adjusted, then a true linear characteristic may result, but in the system shown in Figure 1, such a matching is not always possible. Since changing the wave form of the current which is passed by the damping tube MI is not directly and readily possible, the present invention relates to a change in the wave form of the current passed by the power tube It.
  • the resistance of the deflection circuit alone causes a fast decay of the diode current, that is, the current passed by the damping tube it, and hence, poor distribution, or at least, reduced scanning efliciency results.
  • Such drawbacks are completely overcome by using a system such'as shown in Figure 3, since, in view of the feedback arrangement, values of the resistances R and Ra may be greatly increased without atfecting the linearity of the deflection or the emciency of the system. Accordingly, the deflection During normal operation of the circuit.
  • circuit may be positioned quite remotely with respect to the television camera and the associated deflecting coils.
  • the plate current of the power amplifier tube l2 will be initially reduced so that a wave form of the plate current of the power amplifier tube will resemble the curve shown at 62 in Figure 6, which is somewhat difierent from the wave form shown at iii. in the same figure.
  • the curves t2 and 62 the effect of the feedback from the damping tube will become clearly apparent.
  • Figure '7 In order to make a clear comparison of the current supplied by the power amplifier tube it under the conditions both with and without feedback, attention is directed to Figure '7 where the two current waves are adjacent each other.
  • the curve bi in Figure '7 indicates the current passed by the power amplifier tube it without any feedback from the damping tube, as in a circuit such as shown in Figure l.
  • the curve tit indicates the shape of the current wave supplied by the power amplifier tube it when the feedback arrangement shown in Figure 3 is util zed.
  • the curve t t shows the current passed by the damping tube it in Figure 3 which is necessary to produce a proper matching of the damping tube to the power amplifier tube when the feedback arrangement is used.
  • which is preferably made adjustable, causes a certain amount of "peaking of the voltage applied to the control electrode of the power amplifier tube i2. This peaking effect is not deleterious, but on the contrary, improves the scanning efficiency of the system.
  • the presence of the resistance 3i causes the feedback component shown in curve 60 of Figure 6 to follow the dotted line portion of the curve during the return time.
  • may be called a distribution control, since an adjustment of the value or the resistance 3
  • an amplifier tube including a cathode, a control electrode and an anode, means for impressing the voltage variations upon the control electrode of said amplifier tube, a load circuit including cathode ray beam deflection coils coupled to the anode of said amplifier tube, an asymmetric unit including two electrodes, means for connecting one electrode of said asymmetric unit to the amplifier anode end of the load circuit, means including an adjustable impedance for connecting the other electrode of said asymmetric unit to the other end of the load circuit whereby the current passed by said asymmetric unit will produce potential variations across said impedance, a condenser and a resistance connected in series between the said other electrode of said asymmetric unit and a point of fixed potential, and means including a condenser for coupling the control electrode of said amplifier tube to the junction of said condenser and resistance whereby the potential variations produced across said impedance will be superimposed upon the voltage variations of saw-tooth wave form.
  • a cathode ray beam deflection generator comprising means for producing voltage variations of substantially saw-tooth wave form, an amplifier tube including a cathode, a control electrode and an anode, means for impressing the voltage variations of saw-tooth wave form upon the control electrode of said amplifier tube, a load circuit including cathode ray beam deflection coils coupled to the anode of said amplifier tube, a diode including a cathode and an anode, means for connecting the cathode of the diode to one end of the load circuit, means including an impedance for connecting the anode of the diode to the other end of the load circuit whereby the current passed by the diode will produce potential variations across said impedance, a condenser and resistance connected in series between the anode of said diode and a point of fixed potential, and means including va condenser for coupling the control electrode of said amplifier tube to the junction of said series connected condenser and resistance whereby the potential variations produced across said imped
  • a cathode ray beam deflection generator comprising means for producing voltage variations of substantially saw-tooth wave form, an amplifier tube including a cathode, a control electrode and an anode, means for impressing the voltage variations of saw-tooth wave form upon the control electrode of said amplifier tube, a load circuit including cathode ray beam deflection coils coupled to the anode of said amplifier tube, a diode including a cathode and an anode, means for connecting the cathode of the diode to the amplifier anode end of the load circuit, means including a resistance for connecting the anode of the diode to the other end of the load circuit whereby the current passed by the diode will produce potential variations across said resistance, a condenser and a second resistance connected in series between the anode of said diode and point of fixed potential, and means including a second condenser for connecting the control electrode of said amplifier tube to the junction of said condenser and said second resistance whereby the potential variations produced across

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US325207A 1940-03-21 1940-03-21 Cathode ray beam deflecting circuit Expired - Lifetime US2309672A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL102938D NL102938B (en(2012)) 1940-03-21
US325207A US2309672A (en) 1940-03-21 1940-03-21 Cathode ray beam deflecting circuit
NL102938A NL84973C (en(2012)) 1940-03-21 1941-09-17

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US325207A US2309672A (en) 1940-03-21 1940-03-21 Cathode ray beam deflecting circuit

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US2309672A true US2309672A (en) 1943-02-02

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2431952A (en) * 1944-06-07 1947-12-02 Gen Electric Pulse generating circuit
US2449969A (en) * 1945-05-29 1948-09-28 Rca Corp Compensating device
US2521741A (en) * 1950-09-12 Deflection circuit
US2584268A (en) * 1949-06-16 1952-02-05 Gen Precision Lab Inc Television sweep circuits
US2591249A (en) * 1946-06-28 1952-04-01 Belmont Radio Corp Transformerless saw-tooth current generator
US2603750A (en) * 1947-02-28 1952-07-15 Emi Ltd Electrical circuit arrangement for the generation of oscillations
US2621308A (en) * 1949-03-31 1952-12-09 Rca Corp Electronic tube and circuits
US2621307A (en) * 1946-12-04 1952-12-09 Emi Ltd Scanning circuit arrangement for television and the like apparatus
US2752527A (en) * 1953-08-18 1956-06-26 Tektronix Inc Method of magnifying waveforms on a cathode-ray tube and circuit therefor
US2758248A (en) * 1955-02-21 1956-08-07 Gen Electric Anti-pincushion circuit

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521741A (en) * 1950-09-12 Deflection circuit
US2431952A (en) * 1944-06-07 1947-12-02 Gen Electric Pulse generating circuit
US2449969A (en) * 1945-05-29 1948-09-28 Rca Corp Compensating device
US2591249A (en) * 1946-06-28 1952-04-01 Belmont Radio Corp Transformerless saw-tooth current generator
US2621307A (en) * 1946-12-04 1952-12-09 Emi Ltd Scanning circuit arrangement for television and the like apparatus
US2603750A (en) * 1947-02-28 1952-07-15 Emi Ltd Electrical circuit arrangement for the generation of oscillations
US2621308A (en) * 1949-03-31 1952-12-09 Rca Corp Electronic tube and circuits
US2584268A (en) * 1949-06-16 1952-02-05 Gen Precision Lab Inc Television sweep circuits
US2752527A (en) * 1953-08-18 1956-06-26 Tektronix Inc Method of magnifying waveforms on a cathode-ray tube and circuit therefor
US2758248A (en) * 1955-02-21 1956-08-07 Gen Electric Anti-pincushion circuit

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Publication number Publication date
NL84973C (en(2012)) 1957-05-15
NL102938B (en(2012)) 1900-01-01

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