US3217236A - Circuit arrangement for producing a comparatively high voltage utilizing voltage dependent resistors - Google Patents

Circuit arrangement for producing a comparatively high voltage utilizing voltage dependent resistors Download PDF

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US3217236A
US3217236A US107483A US10748361A US3217236A US 3217236 A US3217236 A US 3217236A US 107483 A US107483 A US 107483A US 10748361 A US10748361 A US 10748361A US 3217236 A US3217236 A US 3217236A
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Prior art keywords
voltage
current
tube
circuit
resistor
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US107483A
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English (en)
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Alma Gerrit Hendrik Petrus
Busscher Willem
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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
    • H04N3/1853—Maintaining dc voltage constant using regulation in parallel
    • 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
    • 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

Definitions

  • FIG. 2 CIRCUIT ARRANGEMENT FOR PRODUCING A COMPARATIVELY HIGH VOLTAGE UTILIZING VOLTAGE DEPENDENT RESISTORS Filed May a. 1961
  • FIG. 2 CIRCUIT ARRANGEMENT FOR PRODUCING A COMPARATIVELY HIGH VOLTAGE UTILIZING VOLTAGE DEPENDENT RESISTORS
  • Such circuit arrangements are often used in television receivers for producing the high voltage for supplying the final anode of the picture tube.
  • the high voltage is stabilized by means of the ballast tube so that variations in the beam current through the display tube, which constitutes the load for the circuit arrangement, do not produce variations in the high voltage produced.
  • ballast tube has the disadvantage that it must be capable of dissipating a high power, since with the beam current cut off the full power delivered by the high voltage circuit must be dissipated by the ballast tube.
  • the full high voltage is set up across the ballast tube which must therefore be rated for a high breakdown voltage.
  • a circuit arrangement according to the invention is characterized by the addition of a voltage-dependent resistor connected in series with the anode of the ballast tube.
  • FIGURE 1 is a circuit diagram of one embodiment of the invention.
  • FIGURE 2 shows a desired anode current-grid voltage characteristic of a ballast tube as used in the circuit of FIGURE 1.
  • tube 1 constitutes the output stage of a line-deflection circuit in a television receiver.
  • the control grid of tube 1 has applied to it a control voltage 2 which periodically releases tube 1.
  • the anode circuit of the tube 1 includes a line-output transformer 3 comprising a primary winding 4 and a secondary or high voltage winding 5.
  • a tapping on the primary winding 4 is the cathode of a series-booster diode 6, the anode of which is connected to the positive terminal of a voltage source delivering a supply voltage of V volts.
  • One end of the primary winding 4 is connected to one electrode of a capacitor 7, the other electrode of which is also connected to the positive terminal of the voltage source.
  • the capacitor 7 is associated with the circuit of the series-booster diode and a positive direct voltage considerably higher than the supply voltage V is set up at the junction point of the capacitor 7 and the primary "ice winding 4. Also connected to the primary winding 4 is a line-deflection coil 8 which is traversed by the sawtooth deflecting current produced, by means of which the beam current through the picture tube 9 is deflected in a horizontal direction.
  • the pulses produced during the fiy-back period of the sawtooth current are stepped up by means of the Winding 5.
  • a rectifier diode 10 is connected to the free end of the high voltage winding 5 and rectifies the pulses resulting in a high voltage V which serves to feed the final anode of the display tube 9.
  • the beam current through the picture tube 9 may vary in several ways. This may be effected, on the one hand, by means of the video-signal which, in the present example, is supplied through a video-output tube 11 to the cathode of the display tube 9 or, on the other hand, by varying the bias potential at the Wehnelt cylinder 12 for adjusting the background brightness of the picture reproduced by the picture tube 9.
  • a high voltage generator as described above for developing a high voltage V always has a comparatively high internal resistance, for example, in the order of 4 or 5 M9. Variation in the beam current would thus result in varition of the voltage V produced. This is undesirable. More particularly, in colour-television receivers, such variation in the high voltage V results in color distortion because the convergence circuits, which are always present in a colour-television receiver, no longer operate satisfactorily.
  • the ballast tube 13 may be controlled, for example, by means of a network comprising a resistor 14 and a capacitor 15 connected between the primary winding 4 and the secondary winding 5.
  • the resistor 14 is then traversed by the direct current I from the high voltage circuit so that the voltage drop across the resistor 14 is a measure of the said direct current or load current I
  • the capacitor 15 serves to pass the pulses to the secondary winding 5.
  • the cathode of the ballast tube 13 is connected to the junction of winding 4 and capacitor 7 and the control grid is connected, through a smoothing resistor 16, to the junction point of resistor 14 and winding 5 and, through a smoothing capacitor 17, to the cathode.
  • a positive direct voltage is set up across the capacitor 7 and the resistor 14 must therefore be so proportioned that the voltage drop across it is higher than that across the capacitor 7 so that the control grid is, under all conditions, negative relative to the cathode.
  • FIGURE 1 also shows a stabilizing circuit 18 which is controlled from a tapping 19 on the primary winding 4 and which develops a negative control-voltage which is applied through a resistor 20 to the control grid of the lineoutput tube 1.
  • the stabilizing circuit 18 serves to sta bilize the sawtooth current through the deflection coil 8 and the voltage across the capacitor 7 in the event of variation in the supply voltage V or in case of ageing of the tubes 1 and 6, and in case of temperature variations. If the load on the high-voltage circuit would not vary, the high voltage V would thus also remain constant.
  • the purpose of ballast tube 13 is to stabilize the voltage V against load current variations.
  • ballast tube 13 were connected directly between the cathode of the rectifier diode 10 and the positive terminal of the supply voltage source, substantially the full high voltage would be set up across the ballast tube 13.
  • the ballast tube 13 must be capable of dissipating the power supplied by the high-voltage circuit when the beam current through the picture tube 9 is cut off (black level). Assuming that the current then flowing through the ballast tube 13 is about 1 rna., it is necessary for the tube to dissipate 25 watts. This requirement also is high.
  • a first improvement may be obtained by including a series-impedance in series with the ballast tube 13. Maintaining a constant load current as such is not influenced thereby since control of the ballast tube 13 ensures that the direct current delivered by the high-voltage circuit remains substantially unchanged irrespective of the intensity of the beam current through the picture tube 9.
  • a voltage-dependent resistor 21 (a so-called V.D.R. resistor) is connected in series with the ballast tube 13, as shown in FIGURE 1.
  • a further improvement may be obtained if the current through the ballast tube is controlled back to a predetermined minimum value of I amp. instead of a value zero for the maximum beam current. Assuming that 1 :01 rna., it follows from Table I that the maximum voltage set up across the ballast tube 13 is about 22.8 kilovolts when using an ohmic resistor of 22 megohms, and from Table II that this maximum voltage drops to 10 kilovolts when using a voltage-dependent resistor 21.
  • the dissipation requirement is reduced from 25 watts to about 3.84 watts and the breakdown-voltage requirement from 25 kilovolts to 10 kilovolts.
  • ballast tube 13 It has thus become possible considerably to reduce the dimensions of the ballast tube 13 to the size which is common practice for ordinary television receiver tubes.
  • the voltage drop across the voltagedependent resistor 21 is set to 22 kilovolts for a current of 1 ma. through the ballast tube 13.
  • V V -CI The voltage across the ballast tube 13 is given by V V -CI If I becomes smaller, it follows from Formula 3 that the voltage across the tube increases. Consequently, the maximum voltage across the tube 13 occurs for the minimum permissible current I so that it will be evident that this maximum voltage may be decreased by increasing the constant C of VDR 21.
  • Both the maximum dissipation and the breakdown voltage for which the ballast tube must be rated may be decreased by increasing C.
  • the anode voltage is also smaller during the occurrence of the maximum current.
  • a further increase of the constant C may therefore give rise to a situation in which the maximum anode current can no longer flow due to the reaction of the anode voltage upon the anode current (penetration factor), unless the negative grid-bias is exceptionally decreased, thus involving a risk of unwanted grid current.
  • the foregoing may be avoided by using a screen-grid tube instead of a triode as the ballast tube so that the current control is solely determined by the voltage at the control grid despite the high value of the voltage-dependent resistor 21.
  • the anode current of such a screen-grid tube is much less dependent upon the anode voltage than in the case of a triode.
  • the screen-grid tube used may be, for example, a tetrode or a pentode.
  • the cathode of the ballast tube 13 is connected to the lower side of the capacitor 7, then the screen grid may be connected to the junction point of the primary winding 4 and the capacitor 7, as illustrated in FIG. 1, for obtaining the desired supply voltage.
  • this implies that I must be raised from 1 ma. to 1.1 ma., if 1 :01 ma. From this it follows that if the beam current through the picture tube 9 is 1ma., the current through the ballast tube 13 assumes a value I 0.1 ma., and if the beam current is cut off, the current through the ballast tube 13 is about 1.1 ma. It is therefore ensured that the sum of the two currents is, under all conditions, about 1.1 ma. so that the voltage drop across the internal resistance of the high voltage circuit always remains constant and hence the value of the high voltage V produced does not substantially vary despite variations in the beam current.
  • the following step may be taken to prevent the current through the ballast tube 13 from decreasing below the value 1
  • the resistor 14 may be so proportioned that the voltage at the control grid of the ballast tube 13 never decreases below the cut-ofi voltage even for the maximum beam current possible through the picture tube 9.
  • the ballast tube 13 itself to be constructed so that the anode current I cannot decrease below a value 1 irrespective of the extent of the increase in negative grid-bias V at the control grid of this tube.
  • FIGURE 2 shows a desired I V characteristic of the ballast tube 13.
  • the mutual conductance of tube 13 becomes substantially zero when the control-grid voltage reaches the value V by which an anode current of I ampere keeps flowing.
  • Such a characteristic may be obtained, for example, by providing the control grid with one or more additional apertures. For this purpose, one or more turns may be omitted in winding the grid wire so that, as it were, a diode which continuously conveys a current I is connected in parallel with the ballast tube proper. The same result could be obtained, for example, by connecting a fixed resistor in parallel with the ballast tube 13.
  • the stabilizing circuit 18 is not strictly necessary. If it is desired to take only the variations in beam current into account, a control circuit with the ballast tube 13 alone sufiices.
  • circuit arrangement need not be limited to television receivers.
  • inventive concept may be used in all those cases where a voltage is produced which is stabilized by means of a ballast tube.
  • circuit arrangements may also be used for stabilizing the high voltage in X-ray equipment and radar installations.
  • a voltage regulating circuit comprising a source of voltage having first and second terminals, load circuit means connected between said terminals, a ballast device having at least output, common and control electrodes, 21 voltage-dependent resistor, means serially connecting said resistor and the output-common electrode path of said device between said terminals, and means connected to said control electrode for controlling the current through said path in the opposite sense with respect to current in said load circuit means.
  • a voltage regulating circuit comprising a source of voltage having first and second terminals, load circuit means connected between said terminals, an electron discharge device having at least cathode, anode and control grid electrodes, a voltage-dependent resistor, means serially connecting the cathode-anode path of said discharge device and said voltage-dependent resistor between said first and second terminals, means for deriving a voltage dependent upon current through said load circuit means, and means applying said dependent voltage to said control grid electrode whereby current through said discharge device varies in the opposite sense with respect to current in said load circuit means.
  • a voltage regulating circuit comprising a source of voltage of high impedance, a load circuit connected to said source, an electron discharge device having at least cathode, control grid and anode electrodes, 21 voltage-dependent resistor, means serially connecting said resistor and the anode-cathode path of said device in parallel with said load circuit, means for deriving a voltage dependent upon current flow in said source, and means for applying said dependent voltage to said control electrode whereby current variations in said load circuit produce current variations in the opposite sense in said device.
  • a voltage regulating circuit comprising a source of voltage of high impedance, a load circuit connected to said source, an electron discharge device having at least cathode, control grid and anode electrodes, a voltage-dependent resistor, means serially connecting said resistor and the anode-cathode path of said device in parallel with said load circuit, means for deriving a voltage dependent upon current flow in said source, means for applying said dependent voltage to said control electrode whereby current variations in said load circuit produce current variations in the opposite sense in said device, and means for maintaining a predetermined minimum current flow in said resistor.
  • said means for maintaining a predetermined minimum current comprises resistor means connected between said anode and cathode electrodes.
  • said means for maintaining a predetermined minimum current comprises aperture means in said control grid electrode whereby anode current flow in said tube is maintained when said control grid electrode has a sutficiently low potential to reduce the transconductance of said device to zero.
  • a high voltage regulating circuit comprising a transformer having a primary and a secondary winding, means for providing a periodic current flow in said primary winding, a first series circuit comprising said primary winding, resistance means, and said secondary winding in that order, a second series circuit comprising serially-connected rectifier means and load means, means connecting said first and second series circuits in parallel, an electron discharge device having at least cathode, control grid and anode electrodes, a third series circuit comprising a voltage-dependent resistor and the cathode-anode path of said device, means connecting said third series circuit in parallel with said load means, and means connecting the junction of said resistance means and secondary Winding to said control grid electrode, whereby current in said cathode-anode path varies in the opposite sense with respect to current flow in said load means.
  • a high voltage regulating circuit comprising a transformer having a primary and secondary winding, means for providing a periodic current flow in said primary winding, a first series circuit comprising said primary winding, resistance means, and said secondary winding in that order, a second series circuit comprising serially-connected rectifier means and load means, means connecting said first and second series circuits in parallel, an electron discharge device having at least cathode, control grid and anode electrodes, a third series circuit comprising a voltage-dependent resistor and the cathode-anode path of said device, means connecting said third series circuit in parallel with said load means, means connecting the junction of said resistance means and secondary winding to said control grid electrode, whereby current in said cathode-anode path varies in the opposite sense with respect to current flow in said load means, and means for maintaining a predetermined minimum current flow in said third series circuit.
  • a voltage regulating circuit comprising a source of voltage having first and second terminals, load circuit means connected between said terminals, a ballast device comprising first and second electrodes defining a current path through said device and a control electrode, a nonlinear voltage-dependent resistor, means serially connecting said device current path and said voltage-dependent resistor between said first and second terminals, means for deriving a control voltage which varies with the magnitude of the current flow in said load circuit means, means for applying said control voltage to said control electrode in a sense to control the current through said path in the opposite sense with respect to current in said load circuit means, and means for maintaining a predetermined minimum current flow in said resistor.
  • a voltage regulating circuit for a high impedance source of high direct voltage said source including a pair of terminals, comprising a load circuit connected across said terminals, an electron discharge device having a control electrode and an anode and a cathode which define a current path through said device, a bidirectional non-linear voltage-dependent resistor, means serially connecting the anode-cathode path of said discharge device and said voltage dependent resistor across said terminals, means for deriving a direct voltage which varies with the total load current supplied by said source, means for applying said direct voltage to said control electrode in a sense such that current variations in said load circuit produce current variations in the opposite sense in said device, and means serially connected with said voltage-dependent resistor for maintaining a predetermined minimum current flow in said resistor.

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US107483A 1960-06-24 1961-05-03 Circuit arrangement for producing a comparatively high voltage utilizing voltage dependent resistors Expired - Lifetime US3217236A (en)

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NL253082A NL253082A (xx) 1960-06-24 1960-06-24

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DE (1) DE1133774B (xx)
FR (1) FR1292755A (xx)
GB (1) GB938555A (xx)
NL (1) NL253082A (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3435279A (en) * 1964-06-18 1969-03-25 Philips Corp Circuit arrangement for producing a sawtooth current through a deflection coil and a high voltage
US3501589A (en) * 1966-07-25 1970-03-17 Zenith Radio Corp Regulated power supply
US3716778A (en) * 1970-04-09 1973-02-13 Denki Onkyo Co Ltd High voltage generating apparatus

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534559A (en) * 1947-04-05 1950-12-19 Bell Telephone Labor Inc Voltage regulation
US2817055A (en) * 1954-09-14 1957-12-17 Westinghouse Electric Corp Regulators
US2833869A (en) * 1950-08-16 1958-05-06 Gen Precision Lab Inc Power law amplifier
US2944186A (en) * 1956-06-15 1960-07-05 Philips Corp Circuit arrangement for producing a sawtooth current in a coil
US3061757A (en) * 1958-02-15 1962-10-30 Philips Corp Circuit arrangement to produce a sawtooth current in a coil and a direct voltage

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534559A (en) * 1947-04-05 1950-12-19 Bell Telephone Labor Inc Voltage regulation
US2833869A (en) * 1950-08-16 1958-05-06 Gen Precision Lab Inc Power law amplifier
US2817055A (en) * 1954-09-14 1957-12-17 Westinghouse Electric Corp Regulators
US2944186A (en) * 1956-06-15 1960-07-05 Philips Corp Circuit arrangement for producing a sawtooth current in a coil
US3061757A (en) * 1958-02-15 1962-10-30 Philips Corp Circuit arrangement to produce a sawtooth current in a coil and a direct voltage

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3435279A (en) * 1964-06-18 1969-03-25 Philips Corp Circuit arrangement for producing a sawtooth current through a deflection coil and a high voltage
US3501589A (en) * 1966-07-25 1970-03-17 Zenith Radio Corp Regulated power supply
US3716778A (en) * 1970-04-09 1973-02-13 Denki Onkyo Co Ltd High voltage generating apparatus

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DE1133774B (de) 1962-07-26
GB938555A (en) 1963-10-02
FR1292755A (fr) 1962-05-04
NL253082A (xx) 1964-03-25

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