US2995679A - Circuit arrangement for generating a sawtooth current in an inductance - Google Patents

Circuit arrangement for generating a sawtooth current in an inductance Download PDF

Info

Publication number
US2995679A
US2995679A US592323A US59232356A US2995679A US 2995679 A US2995679 A US 2995679A US 592323 A US592323 A US 592323A US 59232356 A US59232356 A US 59232356A US 2995679 A US2995679 A US 2995679A
Authority
US
United States
Prior art keywords
inductance
current
voltage
transistor
switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US592323A
Other languages
English (en)
Inventor
Derek Robert Skoyles
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Philips Corp
North American Philips Co Inc
Original Assignee
US Philips Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US2995679A publication Critical patent/US2995679A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A22—BUTCHERING; MEAT TREATMENT; PROCESSING POULTRY OR FISH
    • A22C—PROCESSING MEAT, POULTRY, OR FISH
    • A22C7/00—Apparatus for pounding, forming, or pressing meat, sausage-meat, or meat products
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
    • A47J43/00—Implements for preparing or holding food, not provided for in other groups of this subclass
    • A47J43/20—Shapes for preparing foodstuffs, e.g. meat-patty moulding devices, pudding moulds
    • 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
    • H03K4/48—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements semiconductor devices
    • H03K4/60—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements semiconductor devices in which a sawtooth current is produced through an inductor
    • H03K4/62—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements semiconductor devices in which a sawtooth current is produced through an inductor using a semiconductor device operating as a switching device
    • H03K4/68—Generators in which the switching device is conducting during the fly-back part of the cycle
    • 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
    • H03K4/86—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements gas-filled tubes or spark-gaps

Definitions

  • This invention relates to circuit arrangements for generating a sawtooth current in an inductance, i.e. to sawtooth wave generating circuits, time-base circuits and the like.
  • Such circuits may be used inter alia for generating sawtooth currents for magnetic deflection of the beam of a cathode ray tube e.g. in television application.
  • Conventional circuits used for the latter purpose operate in such manner that a substantially constant voltage is applied to an inductance, which is coupled to or constituted by the deflection coils, so that a linear rise in current occurs in the inductance during the stroke period of the sawtooth cycle.
  • the current in the inductance is interrupted by cutting off a high-vacuum or hard" valve which acts as a switch in series with the inductance.
  • the current in the valve has zero value at the beginning of the stroke period and reaches a maximum value at the end of the stroke.
  • the valve is cut off sharply while such maximum current is flowing and this initiates the fiyback.
  • the latter involves reversal of current to a maximum value of opposie sign following which the next stroke commences.
  • current flow in the reverse direction or a corresponding transformed current is allowed to fiow through an auxiliary diode.
  • the switch valve must cut off sharply, and in this respect a hard valve, e.g. a pentode, is satisfactory.
  • Alternative switchin means such as transistors and thyratrons could also pass the currents required, but cannot be switched off abruptly while current is flowing unless an alternative current path is provided.
  • Such alternative switch means can be turned on faster than they can be turned off and are capable of passing heavy initial currents with very low voltage drop. Accordingly it is an object of the invention to provide improved circuit arrangements capable of utilizing the relatively fast turning-on characteristics of switch means that can turn on faster than they can be turned off.
  • a circuit arrangement for generating a sawtooth current in an inductance comprises the means for causing the current in the inductance to have its maximum value at the beginning of the stroke period of the sawtooth, and means for causing said current to decay in a substantially linear manner to a minimum value during the stroke period, following which maximum current is restored in the inductance during the fiyback period.
  • a circuit arrangement comprises the inductance and a capacitance, means for charging said capacitance during the stroke period, a switch between said inductance and capacitance Patented Aug. 8, 1961 whereby the capacitance may be discharged through the inductance during the fiyback period in a resonant manner, means for permitting continued flow of current through said inductance in the stroke period subsequent to completion of said discharge of the capacitance, and means for applying a substantially constant voltage to said inductance during the stroke period in order to .cause the continued flow of current therein to decay substantially linearly to a minimum value.
  • Such a system has peak voltage and current characteristics which contrast as follows with conventional systerns.
  • peak voltage and peak current are required for a conventional time-base, then peak voltage is applied across the switch during current reversal and a sawtooth current increasing to peak current has to pass through the switch for part of the scan or stroke period (be tween half and full period according to design).
  • peak voltages are built up across the switch during the scan or stroke period and thus cause high voltages to exist for a longer time on the switch. Also, peak current is twice as great for the same peak voltage but lasts for only a much shorter time (if the circuit is designed for the same peak current as a conventional circuit, then the peak voltage is twice as great).
  • the power dissipation in the switch is proportional to the resistance of the switch, and in this respect a transistor is far more suitable than a thyratron since its minimum internal resistance is much smaller.
  • dissipation due to hole storage in a transistor may be greatly reduced in circuits according to the invention since the collector current is interrupted when it is at low value. In fact diversion of the current of the inductance to an alternative path after the fiyback period allows the switch to open while carrying current at low values with only a small rise in applied volts as opposed to peak current at an instant of rapid rise in volts as conventional cases.
  • the switch may for example be constituted by a transistor or by a thyratron as explained more fully hereinafter.
  • the capacitance may be in parallel with the series combination of the inductance and the switch.
  • the switch may be in parallel with the series combination of capacitance and inductance (the latter being referred to hereinafter as the main capacitance" and main inductance wherever confusion may arise due to the addition of auxiliary or optional reactances).
  • the means for applying a substantially constant voltage to the inductance during its discharge so as to linearise the latter may comprise a battery in series with a rectifier effective to prevent discharge of the capacitance through the battery.
  • said means may comprise a rectifier in series with a resistance connected in parallel with a storage capacitance which is large enough to be held charged at a substantially constant level corresponding to the voltage appearing across the inductance during scan.
  • said means may comprise a transformer coupling arranged between the inductance and the HT. supply points of the charging circuit so that the linearly decreasing current fed back to the supply permits a constant DC. voltage across the inductance.
  • the capacitance-charging circuit may operate in any suitable manner, but preferably the charging of thecapacitance is effected resonantly through a charging choke with which said capacitance is resonant to a frequency such that a half cycle corresponds approximately to the stroke period.
  • the main inductance may, if desired, be actually constituted by the deflection coil or coils.
  • the switch may be actuated by synchronisation pulses in the case of television or like applications, or it may be actuated by a relaxation oscillator circuit when the invention is applied to a DO. transformer or voltage changer.
  • a simple and generalised form of the circuit arrangement comprises a capacitor C1 which is charged from an II.T. supply through a charging impedance Z during the stroke of the sawtooth, and an inductance L1 through which capacitor C1 is discharged rcsonantly when a switch SW is closed for the fiyback period.
  • the inductance L1 discharges through means V which provide a discharge path for the continued flow of the current in the inductance.
  • means V applies to the inductance Li a substantially constant voltage.
  • a rectifier D1 is provided in series with means V to prevent direct discharge of C1 through means V instead of through L1.
  • the impedance Z is contituted by a charging choke with which capacitor C1 resonates to a frequency such that a half cycle corresponds approximately to the stroke period.
  • FIGURE 2 shows a circuit in which the switch SW is in parallel with the series combination of the capacitance Cl and inductance L1 instead of being in series with the said inductance.
  • the means V may be constituted by a battery or by a resist ance shunted by a capacitance of very large value.
  • FIGURE 3 which shows a circuit arrangement similar to that of FIGURE 1, in which the switch SW is constituted by a P-N-P junction transistor T.
  • An electrolytic capacitor C2 is shunted by a resistance R providing a path without which the dischange of current from inductance L1 would be prevented due to the capacitor C2 charging up to the peak voltage appearing across L1.
  • rectifier D1 also prevents discharge of capacitor C2 due to ringing with choke L2.
  • Half cycle resonant charging of capacitor C1 is effected through a charging choke L2 and an optional rectifier D2.
  • D2 is only necessary if the resonant frequency of L2Cl is such that one half cycle is smaller than the stroke period in which case Cl would otherwise discharge back into L2.
  • the transistor T can be opened without rupturing the inductive current thus minimising power dissipation due to hole-storage in the transistor.
  • the transistor T must be on for the whole of the flyback period and can stay on for an initial portion of the stroke period; however, in the latter condition it will tend to interfere with the re-charging of capacitor C1 and therefore it is desi able that the transistor T should be turned off as soon as possible after the end of the flyback period.
  • inductance L1 delivers its energy to the means V
  • capacitance C1 will once again be charged to a value 2HT (as shown in curve a) resonantly in a time determined by L2 and C1.
  • curve b represents the changes in the voltage V across the inductance L1
  • curve 0 represents the voltage V across the switch T
  • curve e represents the current I through rectifier D1.
  • curve f represents the emitter-collector current 1-; of the transistor, such current being approximately the difierence between the currents I and I of curves d, c.
  • the transistor T is switched on by the leading edges of negative-going pulses applied to a pulse input point P and switched oil by the trailing edges thereof.
  • negative-going pulses applied to a pulse input point P and switched oil by the trailing edges thereof.
  • such pulses are of 12-14 [1.8 duration with a stroke duration of about s.
  • the voltage difference applied between the collector and emitter electrodes of the transistor at the instant when it is switched on has a value sumeicnt to cause avalanche multiplication of the charge carriers through collision in the depletion layer of the collector, at least at the start of the flyback period.
  • the switching on process is thus speeded up, the current through the transistor building up more rapidly and the voltage there across collapsing more suddenly, so that a power transistor can be made to work much faster than it would without making use of the avalanche etfect.
  • the voltage between the collectorand emitter-electrodes of the transistor can be made to collapse to practically zero value by connecting a capacitor of, say some thousands of pF between said electrodes.
  • a capacitor serves to store suflicient charge-carriers to sustain the discharge through the transistor until the voltage there across has collapsed to the desired low value.
  • FIGURE 5 shows a circuit in which the means V include a transformer coupling arranged between the inductance and the HT supply points of the charging drcuit so that the linearly decreasing current fed back to the supply induces a constant DC. voltage across the inductance Ll.
  • the rectifier D3 is required to prevent pulses of current being taken from the voltage supply in the flyback periods when the current in the inductance L1 rises rapidly.
  • the rectifier D3 must be polarized in the reverse direction with respect to the supply voltage.
  • FIGURE 6 shows a circuit similar to that of FIGURE 3 in which the P-N-P junction transistor is replaced by a thyratron, thepolarity of the H.T. voltage being appropriately reversed.
  • the grid of the thyratron is driven by positive pulses applied at point P in place of the megative pulses required for base control in FIGURE 3.
  • centralisation of the scan on the screen may be eifected e.g. by transformer coupling between the inductance L1 and the deflection coils, or by A.C. cucase of a junction transistor such as transistor T of FIG- URE 7 where the coils are indicated at Ld.
  • transistor T Hitherto the operating conditions of transistor T have not been examined closely, and preferred conditions for television applications will now be considered for the case a junction transistor such as transistor T of FIG- URE 3.
  • the base is not merely made to pass a small current-instead, it is driven hard negative to ensure that the transistor is operating in the Knee" or hard-on condition, and this may be effected with the aid of regenerative feedback or an enternal generator.
  • a circuit for producing a sawtooth current through an inductance comprising a transformer having a primary winding which constitutes said inductance and having a secondary winding, a charging circuit comprising a voltage source, an impedance, and a capacitor continuously connected to be charged from said source through said impedance, a switch connected to selectively connect said primary winding across said capacitor thereby to discharge said capacitor, and a secondary circuit connected across said secondary winding and comprising a source of voltage and a rectifier connected :in series, said rectifier being polarized in the reverse direction with respect to the last-named voltage, thereby to supply a sub stantially constant voltage across said primary winding during the charging periods of said capacitor.
  • a circuit for producing a current having a sawtooth shaped waveform in an inductance comprising a capacitor, an inductive impedance, means serially continually connecting said impedance and capacitor to a source of voltage, means periodically connecting said inductance in parallel with said capacitor, a winding inductively coupled to said inductance, a rectifier, and means serially connecting said rectifier and winding to a source of voltage, said rectifier being polarized in the reverse direction with respect to said last-named source of voltage.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Zoology (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Details Of Television Scanning (AREA)
  • Dc-Dc Converters (AREA)
US592323A 1955-06-21 1956-06-19 Circuit arrangement for generating a sawtooth current in an inductance Expired - Lifetime US2995679A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB17917/55A GB821517A (en) 1955-06-21 1955-06-21 Improvements in or relating to electric sawtooth wave generator circuits, time-base circuits and the like

Publications (1)

Publication Number Publication Date
US2995679A true US2995679A (en) 1961-08-08

Family

ID=43304910

Family Applications (1)

Application Number Title Priority Date Filing Date
US592323A Expired - Lifetime US2995679A (en) 1955-06-21 1956-06-19 Circuit arrangement for generating a sawtooth current in an inductance

Country Status (5)

Country Link
US (1) US2995679A (fr)
BE (1) BE548867A (fr)
DE (1) DE1041612B (fr)
FR (1) FR1192913A (fr)
GB (1) GB821517A (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3111603A (en) * 1959-07-02 1963-11-19 Rca Corp Television deflection circuit
US3131310A (en) * 1959-06-04 1964-04-28 Philips Corp Transistor circuit for generating narrow pulses
US3179843A (en) * 1963-01-14 1965-04-20 Fairchild Camera Instr Co Combined television sweep current generator and power supply
US3185844A (en) * 1961-09-19 1965-05-25 Bess Leon Radiation dosimeter circuit
US3188517A (en) * 1960-04-19 1965-06-08 Kaiser Aerospace & Electronics Transistorized horizontal sweep output circuit
US3197671A (en) * 1962-05-21 1965-07-27 Warwick Eletronics Inc Transistorized deflection system
US3198978A (en) * 1960-09-30 1965-08-03 Philco Corp Low d.c. power horizontal deflection circuit
US3211946A (en) * 1961-04-28 1965-10-12 Warwick Electronics Inc Electromagnetic deflection circuits
US3229150A (en) * 1961-08-17 1966-01-11 Philips Corp Flyback driven deflection circuit
US3235766A (en) * 1961-10-26 1966-02-15 Nerth American Philips Company Time-base circuit with self starting means
US3319075A (en) * 1961-06-02 1967-05-09 Marconi Wireless Telegraph Co Pulse delay circuits using resonant charging with minimum current detectors
US3436591A (en) * 1965-08-06 1969-04-01 Rca Corp Electron beam deflection and low voltage supply circuit
US3517250A (en) * 1967-06-07 1970-06-23 Siemens Ag Horizontal deflection circuit for picture tube of television system
US3654510A (en) * 1969-11-14 1972-04-04 Gen Electric Direct drive vertical deflection system utilizing a storage capacitor and discharge tube in place of an output transformer
US3700958A (en) * 1971-03-05 1972-10-24 Rca Corp Deflection and pincushion correction circuit

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1263075B (de) * 1965-05-26 1968-03-14 Philips Patentverwaltung Schaltungsanordnung zum Erzeugen einer Saegezahnspannung an einem Kondensator
CN107086810A (zh) * 2017-06-29 2017-08-22 张玉炜 一种高能脉冲电源控制电路

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2562941A (en) * 1946-03-20 1951-08-07 Standard Telephones Cables Ltd Sweep generator
US2571824A (en) * 1949-08-25 1951-10-16 Rca Corp Gaseous discharge circuit
US2598134A (en) * 1945-05-11 1952-05-27 Rca Corp Power conservation system
US2664521A (en) * 1951-11-07 1953-12-29 Motorola Inc Deflection circuits
US2697784A (en) * 1946-03-14 1954-12-21 Richard H Blythe Linear sweep circuit
US2728857A (en) * 1952-09-09 1955-12-27 Rca Corp Electronic switching
US2760109A (en) * 1952-12-26 1956-08-21 Rca Corp Kinescope deflection circuits
US2774911A (en) * 1954-02-08 1956-12-18 Int Standard Electric Corp Circuit arrangement for the generation of saw-tooth shaped deflecting currents

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE491135A (fr) * 1948-09-21

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2598134A (en) * 1945-05-11 1952-05-27 Rca Corp Power conservation system
US2697784A (en) * 1946-03-14 1954-12-21 Richard H Blythe Linear sweep circuit
US2562941A (en) * 1946-03-20 1951-08-07 Standard Telephones Cables Ltd Sweep generator
US2571824A (en) * 1949-08-25 1951-10-16 Rca Corp Gaseous discharge circuit
US2664521A (en) * 1951-11-07 1953-12-29 Motorola Inc Deflection circuits
US2728857A (en) * 1952-09-09 1955-12-27 Rca Corp Electronic switching
US2760109A (en) * 1952-12-26 1956-08-21 Rca Corp Kinescope deflection circuits
US2774911A (en) * 1954-02-08 1956-12-18 Int Standard Electric Corp Circuit arrangement for the generation of saw-tooth shaped deflecting currents

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3131310A (en) * 1959-06-04 1964-04-28 Philips Corp Transistor circuit for generating narrow pulses
US3111603A (en) * 1959-07-02 1963-11-19 Rca Corp Television deflection circuit
US3188517A (en) * 1960-04-19 1965-06-08 Kaiser Aerospace & Electronics Transistorized horizontal sweep output circuit
US3198978A (en) * 1960-09-30 1965-08-03 Philco Corp Low d.c. power horizontal deflection circuit
US3211946A (en) * 1961-04-28 1965-10-12 Warwick Electronics Inc Electromagnetic deflection circuits
US3319075A (en) * 1961-06-02 1967-05-09 Marconi Wireless Telegraph Co Pulse delay circuits using resonant charging with minimum current detectors
US3229150A (en) * 1961-08-17 1966-01-11 Philips Corp Flyback driven deflection circuit
US3185844A (en) * 1961-09-19 1965-05-25 Bess Leon Radiation dosimeter circuit
US3235766A (en) * 1961-10-26 1966-02-15 Nerth American Philips Company Time-base circuit with self starting means
US3197671A (en) * 1962-05-21 1965-07-27 Warwick Eletronics Inc Transistorized deflection system
US3179843A (en) * 1963-01-14 1965-04-20 Fairchild Camera Instr Co Combined television sweep current generator and power supply
US3436591A (en) * 1965-08-06 1969-04-01 Rca Corp Electron beam deflection and low voltage supply circuit
US3517250A (en) * 1967-06-07 1970-06-23 Siemens Ag Horizontal deflection circuit for picture tube of television system
US3654510A (en) * 1969-11-14 1972-04-04 Gen Electric Direct drive vertical deflection system utilizing a storage capacitor and discharge tube in place of an output transformer
US3700958A (en) * 1971-03-05 1972-10-24 Rca Corp Deflection and pincushion correction circuit

Also Published As

Publication number Publication date
GB821517A (en) 1959-10-07
BE548867A (fr) 1959-11-20
DE1041612B (de) 1958-10-23
FR1192913A (fr) 1959-10-29

Similar Documents

Publication Publication Date Title
US2995679A (en) Circuit arrangement for generating a sawtooth current in an inductance
US3562623A (en) Circuit for reducing stray capacity effects in transformer windings
US2266516A (en) Saw-tooth wave generator
US2896115A (en) Retrace driven deflection circuit for cathode ray tubes
US3784857A (en) Television deflection circuit with low power requirement
US2998532A (en) Linear ramp voltage wave shape generator
US3070727A (en) Transistor circuit for applying sawtooth currents to an inductance
US2747136A (en) Cathode ray beam deflection system
US2939040A (en) Scanning generator
US2458532A (en) Cathode-ray tube circuit
US3467882A (en) Scanning circuits operative with line voltage type of power supply
US2179607A (en) Cathode ray deflecting circuits
US2254031A (en) Relaxation oscillation generator
US4625155A (en) Resonant switching apparatus using a cascode arrangement
US3697880A (en) Circuit for switching between two unidirectional voltages
US2919414A (en) Magnetic pulse modulator
US2085402A (en) Method of and apparatus for producing electrical waves
US3038128A (en) Transistor blocking oscillator using resonant pulse width control
US3323001A (en) Time-base circuit arrangement having transistor and scr switching elements
US2996641A (en) Cathode ray tube deflection circuit
US2555832A (en) Cathode ray deflection system
US2962626A (en) Deflection system for a cathode ray tube
US3134928A (en) Transistor vertical deflection circuits
US3300680A (en) Television sweep system with semiconductor switch and energy storage device for expedting its activation
US3714503A (en) Resonant energy recovery type crt deflection circuit