US2227001A - Regulation of television receivers - Google Patents

Regulation of television receivers Download PDF

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Publication number
US2227001A
US2227001A US53534A US5353435A US2227001A US 2227001 A US2227001 A US 2227001A US 53534 A US53534 A US 53534A US 5353435 A US5353435 A US 5353435A US 2227001 A US2227001 A US 2227001A
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United States
Prior art keywords
potential
rectifier
television
regulation
cathode
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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
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US53534A
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English (en)
Inventor
Schlesinger Kurt
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LOEWE RADIO Inc
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LOEWE RADIO Inc
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Filing date
Publication date
Application filed by LOEWE RADIO Inc filed Critical LOEWE RADIO Inc
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Publication of US2227001A publication Critical patent/US2227001A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/52—Automatic gain control
    • H04N5/53—Keyed automatic gain control

Definitions

  • the light intensity of the television tube should be in direct proportion to the strength of'the field at the place of reception, independently of the frequency with whichthis strength of field is modulated. -If, therefore, the transmitter provides a constant strength of field, and if, as is necessary in the case of present-day receiving apparatuatheD. C. component is transmitted to the television tube, the lightv intensity of the image would fluctuate up and down upon varying the receiving amplification by means of a control knob, because the high frequency reaching the rectifier would be large or small dependent on the amplification, and it is a condition that the light intensity of the television tube be proportional to the excitation.
  • the light intensity value in the case of unmodulated carrier Wave should correspond with the black value of the images, a dependency-of this kind is not permissible.
  • the mean value of the lightintensity would be displaced more and more towardswhite if the amplification factor were increased, say, for the purpose of obtaining greater image potentials.
  • a second control knob would then-be necessary for adjusting the mean light-intensity of the television tube, which kn ob would. require to be actuated in reverse direction dependent on the adjustment of the receiving amplifier. A complicated and positive adjustment of this kind in reception is not to be expected of the unskilled user.
  • the second idea in the invention consists in not rectifying these synchronisation signals by the'amplitude filter which is present in any case, but to employ this amplitude filter solely for the synchronisation and to use a special regulating'rectifier, which converts the synchronisation peaks" into direct potential independently of the amplitude filter.
  • the third idea in the invention consists in not transmitting the synchronisation peaks to this regulating rectifier "dir'ectly,;as would be necessary and convenient in the case'of the amplitude filter, but capacitatively or inductively, as in this way it is accomplished that the excitation of the regulating rectifier rises and falls together with the strength of signal frequency.
  • An aerial l is coupled with the carrier wave amplifier 2, which is also coupled with the local oscillator 3, so that an amplified carrier frequency occurs at This frequency is rectified in the grid current rectifier arrangement 5 for ultra-short waves described in previous specificationsand converted without any traces of carrier frequency into a video frequency,
  • the impulse potential allowed to pass through the filtertube 9 in no way varies, because the potential I2 is so adjusted that a current is able to,.traverse 9 only when the carrier wave ceases.
  • the cathode potential l9 recedes more and more from the break-down potential of the tube 9, and all signalling amplitudes increasing in this direction serve to block the tube better.
  • the filter tube 9 serves onlythe highest peaks .fromthe impulses, and is not affected in its outi for the regulating function a new and second rectifier l3.
  • This in accordance with the invention is coupled with the output lead I, i. e., with the rectified received potential, only by way of alternating current circuit, and not directly, for example by means of a condenser I4.
  • a condenser I4 As regulating rectifier l3 there is shown in the drawing a crystal detector, the direction of the arrow indicating its transmission.
  • the use of simple rectifiers .of this nature, which are desirable for economic reasons and in viewof the simple function of I3, is only rendered possible if, by means of a series resistance It of approximately ten times the size of 6, the capacitative shunts represented by the capacities of the rectifier [3 are prevented from affecting the image lead I.
  • a manually adjustable bias I! is supplied to the cathode of I3.
  • the bias H is preferably adjusted once at-the back of the apparatus and then not fur- .theral-tered;
  • the condenser I8 is so selected as regards its capacity that it is capable of followi potential variations at the desired rate of several images.-
  • the regulating potential resuiting at the same is then supplied to the amplifying valves of the intermediate-frequency amplifier 2.
  • the orders of magnitude in the case of ISO-line images are as follows:
  • Leakage resistance it 0.5 megohm.
  • Leakage resistance l9 0.5 megohm.
  • Blocking condenser l8 approx. 0.5 mi.
  • the leakage resistance l'9 has the object of providing for a sinking of the bias with which thecondenser I8 is charged when the reception decreases.
  • the time constant of the circuit [8/19 is selected in the manner known per se dependent on the requirements placed on the rate of regulation.
  • the contact rectifier l3 may also 'be replaced by other valves.
  • the use of contact rectifiers merely offers economical advantages and no disadvantages of any kind. In the case of hot-cathode rectifiers of small dimensions It may possibly be omitted.
  • the amplitude filter 9 is. united in practice with the detector valve 5 in one glass bulb, as described in the application Ser. No. 45,729/ 35.
  • a television system for receiving a carrier ,w-ave modulated with picture signals and synchronizing impulses, comprising a receiver having an input, a plurality of amplifying tubes and an output, a demodulating device for producing detected picture signals and synchronizing impulses, an amplitude filtering device for separating the synchronizing impulses from the picture signals, a rectifier including a cathode and an anode, means including a condenser for applying the detected picture signals and synchronizing impulses between thecathode of said rectifier and a point of fixed potential, a source of potential and an impedance for normally maintaining therectifier and the point of fixed potential, and
  • a television system for receiving a carrier wave modulatedwith ;.picture signals and synchronizing impulses and wherein the synchronizing impulses have a greater amplitude than the picture signals, comprising a receiver having an input, a plurality of amplifying tubes each havinga control electrode, and an output, a demodulating device for producing detected picture signals and synchronizing impulses, an asymmetric unit including a cathode and an anode, means including a condenser for applying the detected picture signals and synchronizing impulses'between-the cathode of said asymmetric unit and a point of fixed'potential, a source of potential and a high.
  • a time constant circuit including a parallel connected resistance and condenser connected between the anode of the asymmetric unit and the point of fixed potential, and means for connecting the control electrode of at least one of the amplifying tubes to the anode of the asymmertic unit to alter the effectiveness of the amplifying tube in accordance with changes in the potential at the anode of the asymmetric unit.
  • a television system for receiving a carrier wave amplitude modulated with picture signals and synchronizing impulses and wherein the synchronizing impulses have a greater amplitude in a predetermined direction than the picture signals, comprising a receiver having a plurality of amplifying tubes each including a control electrode, a demodulating device for producing detected picture signals and synchronizing impulses, an amplitude filtering device for separating the synchronizing impulses from the picture signals, a diode rectifier including a cathode and an anode, means including a condenser and a series resistance for applying the detected picture signals and synchronizing impulses between the cathode of said diode and a point of fixed potential, a source of potential and a resistance for normally maintaining the cathode at a potential difference relative to the point of fixed potential, a time constant circuit including a parallel connected resistance and condenser connected between the anode of the diode and the point of fixed potential, and means for connecting the control electrode of at least one of the ampl
  • synchronizing impulses have a higher amplitude than the video signals
  • synchronizing impulses have a higher amplitude than the video signals
  • said 20 means consisting of a biased rectifier coupled to the control electrode of the cathode ray tube of said receiver so as to charge a storage condenser being provided with a leakage resistance and being connected to a grid of said amplifier, 25
  • said rectifier consisting of a crystal detector of very low capacity.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Circuits Of Receivers In General (AREA)
  • Picture Signal Circuits (AREA)
US53534A 1934-12-10 1935-12-09 Regulation of television receivers Expired - Lifetime US2227001A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE464492X 1934-12-10

Publications (1)

Publication Number Publication Date
US2227001A true US2227001A (en) 1940-12-31

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Family Applications (1)

Application Number Title Priority Date Filing Date
US53534A Expired - Lifetime US2227001A (en) 1934-12-10 1935-12-09 Regulation of television receivers

Country Status (4)

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US (1) US2227001A (enrdf_load_stackoverflow)
BE (1) BE412678A (enrdf_load_stackoverflow)
FR (1) FR46823E (enrdf_load_stackoverflow)
GB (1) GB464492A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2481045A (en) * 1945-03-12 1949-09-06 Rca Corp Automatic volume control and sync separator for television receivers
US2515763A (en) * 1948-10-22 1950-07-18 Gen Electric Direct current restoration circuit for television
US2520012A (en) * 1948-01-08 1950-08-22 Philco Corp Negative bias limiter for automatic gain control circuits
US2554317A (en) * 1946-12-18 1951-05-22 Rca Corp Clamp circuit
US2598929A (en) * 1949-12-15 1952-06-03 Philco Corp Direct current reinsertion circuit
US2618703A (en) * 1947-12-13 1952-11-18 Hazeltine Research Inc Keyed direct current reinsertion circuit
US2800528A (en) * 1949-06-23 1957-07-23 Du Mont Allen B Lab Inc Video amplifier bridge circuit for minimizing supply voltage variations

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2481045A (en) * 1945-03-12 1949-09-06 Rca Corp Automatic volume control and sync separator for television receivers
US2554317A (en) * 1946-12-18 1951-05-22 Rca Corp Clamp circuit
US2618703A (en) * 1947-12-13 1952-11-18 Hazeltine Research Inc Keyed direct current reinsertion circuit
US2520012A (en) * 1948-01-08 1950-08-22 Philco Corp Negative bias limiter for automatic gain control circuits
US2515763A (en) * 1948-10-22 1950-07-18 Gen Electric Direct current restoration circuit for television
US2800528A (en) * 1949-06-23 1957-07-23 Du Mont Allen B Lab Inc Video amplifier bridge circuit for minimizing supply voltage variations
US2598929A (en) * 1949-12-15 1952-06-03 Philco Corp Direct current reinsertion circuit

Also Published As

Publication number Publication date
BE412678A (enrdf_load_stackoverflow)
GB464492A (en) 1937-04-19
FR46823E (fr) 1936-09-12

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