US3320470A - Line deflection circuit having transformer with tertiary winding to compensate for high voltage load variations - Google Patents

Line deflection circuit having transformer with tertiary winding to compensate for high voltage load variations Download PDF

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US3320470A
US3320470A US335605A US33560564A US3320470A US 3320470 A US3320470 A US 3320470A US 335605 A US335605 A US 335605A US 33560564 A US33560564 A US 33560564A US 3320470 A US3320470 A US 3320470A
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Prior art keywords
voltage
winding
control
tertiary
primary
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US335605A
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English (en)
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Janssen Peter Johanne Hubertus
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/18—Generation of supply voltages, in combination with electron beam deflecting
    • H04N3/185—Maintaining DC voltage constant
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/18—Generation of supply voltages, in combination with electron beam deflecting

Definitions

  • the invention relates to a line deflection circuit for use in a television receiver, and more particularly to a deflection circuit including means for compensating for the high voltage load variations of the system.
  • the circuit comprises a transformer connected in the output circuit of an amplifying element.
  • the transformer primary winding is coupled to one or more deflection coils and the secondary winding is connected to a rectifier for producing an acceleration voltage for the final anode of the display tube.
  • the transformer also includes a tertiary winding which supplies a voltage to a control-circuit by means of which a direct control-voltage is produced.
  • the control voltage is in turn supplied to a controlelectrode of the amplifying element to compensate for high voltage load variations.
  • the control-circuit contained in the arrangement of the kind set forth serves two purposes. In the first place variations of the slope of the sawtooth current passing through the deflection coils and of the high voltage produced are thus counteracted, which variations may be due to supply voltage fluctuations. In the second place the control-circuit serves to reduce variations of the slope of the sawtooth current due to variations of the mean brightness of the scene to be reproduced.
  • To the secondary winding is connected the display tube via the rectifier, said tube constituting a load varying with the mean brightness of the scene to be reproduced. With an increasing brightness the high voltage produced and the slope of the sawtooth current are reduced.
  • the controlcircuit has for its object to keep the slope of the sawtooth current substantially constant for a varying high voltage load, whereby at the same time a certain degree of stabilisation of the high voltage is achieved.
  • the transformer is provided with a tertiary winding which is coupled magnetically and fixedly with the primary windin g or which forms part of said primary winding.
  • the primary fly-back pulses appearing across this tertiary winding are fed to the control-circuit.
  • a non-linear element is included in the control-circuit and conveys current only, or substantially only, during that part of the fly-back time in which the fly-back pulses supplied to the element are at a maximum.
  • the arrangement adjusts itself for the operation of the control-circuit so that the maximum value of these pulses is kept constant. This provides a satisfactory stabilisation of the slope of the sawtooth current and of the high voltage in the event of supply voltage fluctuations.
  • This phenomenon is principally due to the stray inductance always prevailing between the primary winding and the secondary winding of the transformer.
  • This stray inductance is, moreover, chosen to be fairly high in order to avoid dying-out phenomena during the forward stroke (so-called third-harmonic tuning).
  • the controlcircuit in known line deflection arrangements of the kind set forth receives apart from the primary fly-back pulses a voltage which depends, with a varying high-voltage load. unambiguously upon the slope of the sawtooth current.
  • a first disadvantage of this method is, however, that optimum stabilisation cannot be attained.
  • a second disadvantage consists in that the voltages available in the arrangement which depend unambiguously upon the slope of the sawtooth current are, in general, too low for the said purpose, so that it is necessary to include in the control-circuit a rectifying element with a control-electrode, to which said voltage is fed.
  • a rectifying element without a controlelectrode in the control-circuit is preferred, for example, a voltage-dependent resistor.
  • the invention provides a line deflection arrangement in which a single voltage-dependent resistor as a rectifying element in the control-circuit is sufiicient. whilst nevertheless a satisfactory control is obtained. Furthermore, it is possible to maintain a strict control over the slope of the sawtooth current or to allow this slope to vary slightly with the varying high-voltage, which may be desirable under certain conditions.
  • the line deflection arrangement according to the invention is characterized in that the tertiary winding is magnetically coupled both with the primary winding and with the secondary winding, so that the ratio between the part of the tertiary voltage which corresponds to the secondary voltage and the part of the tertiary voltage which corresponds to the primary voltage lies between 0.2 and 5. Whilst the polarities of the two said parts of the tertiary voltage are the same.
  • the invention is based on the recognition of the fact that by adding secondary fly-back pulses to the primary fly-back pulses to be fed to the control-circuit the instant at which the rectifying element of the control-circuit is mainly conducting is displaced towards the middle of the fly-back time, where a substantially unambiguous relationship exists between the primary fiy-back voltage and the slope of the sawtooth current, whilst, moreover. by the choice of the magnitude of the secondary fly-back pulses to be added the influence of the finite control-gain can be compensated wholly or partly.
  • FIG. 1 shows an embodiment of a line deflection circuit arrangement according to the invention.
  • FIG. 2 serves for explaining the measure according to the invention.
  • reference numeral 1 designates an output transformer comprising a closed circuit of ferromagnetic material, on which are arranged a primary winding 2, a secondary winding 3 and a tertiary winding 4.
  • the primary winding is connected at one end 5 via a large booster capacitor 6 to the positive terminal of a supply voltage source E, whilst a tapping 7 of the primary winding is connected through an efliciency diode 8 to the said positive terminal.
  • the end 9 of the primary winding is connected to the anode of a pentode 10, the cathode of which is connected to earth (the negative terminal of the supply voltage source) and to the control-grid of which is fed via a capacitor 11 a signal 12, which blocks the pentode periodically.
  • the connections of the further electrodes of the pentode are not indicated since they may be made in any known manner.
  • One or more horizontal deflection coils 13, arranged on the display tube and producing the horizontal deflection of the electron beam in the display tube, are connected between the end 5 of the primary Winding of the transformer and a tapping 14 of the same.
  • the pentode is made conductive by the control-signal 12 to an extent such that the diode 8 is conducting.
  • the constant booster voltage V of the capacitor 6 for the whole duration of the forward stroke.
  • the transformed constant voltage V appears also throughout the primary winding and across the deflection coils 13. This voltage produces in the deflection coils a sawtooth current, which may, if desired, be given a substantially S-shaped waveform by including in series with the deflection coils a capacitor 22 of suitably chosen capacitance.
  • the pentode 10 is blocked by the control-signal 12, so that the diode 8 is also blocked.
  • the energy available in the transformer and in the deflection coils then produces an electric oscillation across the parasitic capacities of the transformer and of the deflection coils, so that a large positive voltage pulse (the primary fly-back pulse) is produced across the primary winding.
  • This positive voltage pulse is stepped up in the secondary winding 3 and rectified by means of a rectifier 15.
  • the positive direct voltage thus obtained is smoothed by a gapacitor 16 and fed to the final anode 23 of the display tu e.
  • the display tube thus constitutes a high-voltage load varying with the mean brightness of the scene to be reproduced and connected to the rectifier 15. Owing to an increasing high-voltage load the voltage of the booster capacitor 6 drops for a number of periods and hence the slope of the sawtooth current in the deflection coils 13 decreases. A decrease in high-voltage load involves an increase in booster voltage and hence an increase of the slope of the sawtooth current.
  • FIG. 1 For counteracting these variations of the booster voltage the arrangement of FIG. 1 includes a control-circuit comprising a tertiary winding 4 on the transformer and the series combination of a voltage-dependent resistor 17 and a capacitor 18, to which the fly-back pulses appearing across the tertiary winding 4 are fed.
  • the junction of the voltage-dependent resistor 17 and the capacitor 18 is connected to earth and the direct voltage occurring across the capacitor 18 due to the rectifying effect of the element 17 is supplied via a resistor 19 to the control-electrode of the pentode 10.
  • control-circuit is provided with a high-ohmic direct-current source formed by a potentiometer 20, connected to the direct voltage and a large resistor 21.
  • This direct current source supplies via the tertiary winding 4 to the voltage-dependent resistor an adjustable direct current I It is known that this measure provides a considerable increase in control-gain, whilst by the adjustment of said direct current the values of the voltages of the transformer and hence the width of the image reproduced by the display tube can be adjusted.
  • FIG. 2 illustrates the voltage (V across the primary winding of the transformer for a low high-voltage load (curve a).and for a great high-voltage load (curve b) with such a control that the voltage occurring during the forward stroke and hence the booster voltage V which is proportional to the primary forward-stroke voltage remain constant.
  • Curves a and b of FIG. 2 illustrates the primary voltage in dependence upon the high-voltage load with an ideal control aimed at for maintaining a con stant slope of the sawtooth current across the deflection coils 13.
  • the waveform of the fly-back pulses deviating materially from the sine-wave form and depending strongly upon the high-voltage load is due to the eflect of the diode 15 varying with the high-voltage load and to the stray inductance occurring between the primary winding 2 of the transformer and the secondary winding 3 thereof.
  • This stray inductance is often chosen so high that during the forward stroke no dying-out phenomena occur (so-called thirdaharmonic tuning).
  • the measure according to the invention provides an additional advantage in that sufficiently high secondary fly-back pulses are available in the arrangement, so that a control-circuit including only a voltage-dependent resistor will sufiice.
  • a further advantage of the measure according to the invention is that the peaks of the secondary fly-back pulses exhibit flattening, since the diode 15 is conducting during these peaks, which flattened part increases with an increase in high-voltage load.
  • Curves c and d of FIG. 2 illustrate the waveform of the secondary fly-back pulses for a low and a high high-voltage load with a constant forwardstroke voltage.
  • the larger flattening with an increase in high-voltage load results in that, when the control-circuit would receive only secondary fly-back pulses an overcompensation control would be obtained, which would mean that the booster voltage V 'would'increase with an increase in high-voltage load.
  • FIG. 1 illustrates how the measure according to the invention can be carried out in practice.
  • the output transformer comprises a ferro-magnetic circuit composed of four limbs arranged in a square and connected with each other.
  • the primary winding 2 and the secondary winding 3 are arranged on two opposite limbs and the tertiary winding is disposed on one of the intermediate limbs of the transformer, so that the tertiary winding is coupled partially with the primary winding and partially with the secondary winding.
  • the invention provides a simple method in which the tertiary winding can be arranged at such a place of the intermediate limb that a control is obtained which corresponds to the optimum to the preference of the designer.
  • control-circuit receives a tertiary voltage which is composed of a part corresponding to the secondary voltage and a part corresponding to the primary voltage, whilst the ratio (6) between the part corresponding to the secondary voltage and the part corresponding to the primary voltage lies between 0.2 and 5.
  • k is the coefiicient of coupling between the primary winding and the secondary winding
  • [ is the coupling coefficient between the primary winding and the tertiary winding and k is the coupling coeflicient between the secondary winding and the tertiary winding.
  • the ratio 6 may be measured in a simple manner on a transformer.
  • the series combination of for example two windings, one of which is magnetically and fixedly coupled with the primary winding or forms part of the latter, whereas the other is coupled magnetically and fixedly with the secondary winding or forms part thereof, may be considered to be a tertiary winding.
  • the ratio 6 can then be calculated in the manner described above.
  • a deflection circuit for a display tube comprising, amplifier means for generating a deflection signal and including a control electrode, a transformer comprising a primary winding, a secondary winding, and a tertiary winding inductively coupled with both the primary winding and the secondary winding so as to have induced therein a tertiary flyback voltage composed of first and second voltage components corresponding to the primary and secondary winding fiyback pulses, respectively, said transformer windings being arranged so that the polarity of said first and second components are the same and the ratio of said second voltage component to said first voltage component lies in the range between 0.2 and 5, means for applying said deflection signal to said primary winding, a deflection coil coupled to said primary winding, a rectifier connected to said secondary winding to produce the high voltage for the acceleration anode of said display tube, a control circuit coupled to said tertiary winding and including a non-linear element for developing a direct current control voltage determined by said tertiary voltage,
  • said nonlinear element comprises a voltage-dependent resistor, a capacitor, said control circuit comprising the series combination of said capacitor and said voltage-dependent resistor and means for supplying said tertiary voltage to said series combination.
  • said transformer further comprises a ferromagnetic core comprising four interconnected limbs arranged in the shape of a rectangle, said primary and secondary windings being arranged on two opposed limbs of the rectangle and said tertiary winding being arranged on one of the remaining limbs thereof.
  • a circuit as described in claim 1 further comprising a capacitor connected in series with said non-linear element and across said tertiary winding, means for connecting the common junction between one terminal of said capacitor and the non-linear element to a fixed potential, and direct current connecting means for coupling the other terminal of said capacitor directly to said control electrode.
  • nonlinear element comprises a resistance element having a non-linear symmetrical current-voltage characteristic
  • said control circuit further comprising a capacitor connected in series circuit with said resistance element and said tertiary winding, and means providing a direct voltage bias to said resistance element.
  • a deflection circuit for a television receiver comprising, an amplifier device having a control electrode and an output electrode, a transformer comprising a primary winding, a secondary winding, and a tertiary winding inductively coupled with both the primary winding and the secondary winding, a source of direct voltage, means connecting said primary winding and said output electrode in series with said voltage source, means coupled to said control electrode for interrupting the current flow in said amplifier device so as to cause a deflection current to flow in said primary winding, said tertiary winding having induced therein a flyback voltage pulse composed of first and second components of voltage in a predetermined ratio and of the same polarity and corresponding to the primary and secondary winding fiyback pulses, respectively, a rectifier interconnecting said seco ndary winding and the acceleration anode of the receiver display tube, a control circuit for stabilizing the current in said amplifier device upon variation of said direct voltage comprising a non-linear element coupled to said tertiary winding for developing a
  • k is the coetficient of coupling between primary and secondary windings
  • [c is the coefficient of coupling between primary and tertiary windings
  • k is the coefficient of coupling between secondary and tertiary windings.
  • control circuit further comprises a capacitor connected in series with said non-linear element and said tertiary winding for developing said direct current control voltage, said means for supplying comprising a direct current connection for applying the voltage across said capacitor to said control electrode.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
  • Coils Or Transformers For Communication (AREA)
US335605A 1963-01-11 1964-01-03 Line deflection circuit having transformer with tertiary winding to compensate for high voltage load variations Expired - Lifetime US3320470A (en)

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Application Number Priority Date Filing Date Title
NL287703A NL125030C (en(2012)) 1963-01-11 1963-01-11

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US3320470A true US3320470A (en) 1967-05-16

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US (1) US3320470A (en(2012))
AT (1) AT253582B (en(2012))
BE (1) BE642322A (en(2012))
CH (1) CH422052A (en(2012))
DE (1) DE1190500B (en(2012))
DK (1) DK110184C (en(2012))
ES (1) ES295151A1 (en(2012))
GB (1) GB1026932A (en(2012))
IT (1) IT712562A (en(2012))
NL (1) NL125030C (en(2012))
OA (1) OA00796A (en(2012))

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3428856A (en) * 1965-05-24 1969-02-18 Conrac Corp Television high voltage regulator
US3517253A (en) * 1968-05-22 1970-06-23 Rca Corp Voltage regulator
US3562578A (en) * 1968-04-25 1971-02-09 Victor Company Of Japan Vertical deflection circuit of television receiver

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU466902B2 (en) * 1971-06-15 1973-01-04 N.V. Philips Gloeilampenfabrieken Circuit arrangement for supplying eht tothe acceleration anode ofa picture display tube

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2907825A (en) * 1956-01-21 1959-10-06 Philips Corp Arrangement for use in television receivers to synchronize the line deflection circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2907825A (en) * 1956-01-21 1959-10-06 Philips Corp Arrangement for use in television receivers to synchronize the line deflection circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3428856A (en) * 1965-05-24 1969-02-18 Conrac Corp Television high voltage regulator
US3562578A (en) * 1968-04-25 1971-02-09 Victor Company Of Japan Vertical deflection circuit of television receiver
US3517253A (en) * 1968-05-22 1970-06-23 Rca Corp Voltage regulator

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Publication number Publication date
ES295151A1 (es) 1964-03-01
AT253582B (de) 1967-04-10
DK110184C (da) 1970-01-12
CH422052A (de) 1966-10-15
IT712562A (en(2012))
BE642322A (en(2012)) 1964-07-09
DE1190500B (de) 1965-04-08
NL287703A (en(2012)) 1965-02-25
OA00796A (fr) 1967-11-15
GB1026932A (en) 1966-04-20
NL125030C (en(2012)) 1969-01-15

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