US2063694A - Automatic regulation of the amplification in tele-cine transmitting amplifiers - Google Patents

Automatic regulation of the amplification in tele-cine transmitting amplifiers Download PDF

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Publication number
US2063694A
US2063694A US598476A US59847632A US2063694A US 2063694 A US2063694 A US 2063694A US 598476 A US598476 A US 598476A US 59847632 A US59847632 A US 59847632A US 2063694 A US2063694 A US 2063694A
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United States
Prior art keywords
cell
photo
resistance
amplifier
circuit
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Expired - Lifetime
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US598476A
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English (en)
Inventor
Moller Rolf
Schubert Georg
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.)
FIRM OF FERNSCH AKTIEN GES
FIRM OF FERNSCH AKTIEN-GESELLSCHAFT
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FIRM OF FERNSCH AKTIEN GES
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Application filed by FIRM OF FERNSCH AKTIEN GES filed Critical FIRM OF FERNSCH AKTIEN GES
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Publication of US2063694A publication Critical patent/US2063694A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/222—Studio circuitry; Studio devices; Studio equipment
    • H04N5/253—Picture signal generating by scanning motion picture films or slide opaques, e.g. for telecine

Definitions

  • Figure 1 is a schematic circuit diagram of our regulating device connected to a photo-electric cell and appropriate amplifying units.
  • Figure 2 is a circuit diagram illustrating means for automatically regulating the amplifier input in accord with the lighter or darker printing of the transmitting films.
  • Thevoltage variations produced by the photo cell F and amplifiedby the amplifier V are applied to the terminals A and B of the grid circuit of a thermionic valve E.
  • the anode resistance of this valve E forms part of the photo-cell circuit.
  • the resistance R is connected in parallel with a large condenser C1. so that the time of charging and discharging is larger than the transmission period corresponding to at least one film picture.
  • the condensers C2, C3 and the resistance Rg must be so proportioned that all frequencies contained in a picture are conducted in the correct amplitude relationship to the grid of the valve E. It is, of course, not necessary to restrict oneself to supplying to the amplifier a constant average alternating current amplitude, but one may equally well alter the degree of amplification by correspondingly modifying the given circuit, and directly or indirectly connecting the resistance lying in the anode Circuit of the regulating valve in the grid or anode circuit of. one of the valves of the amplifier.
  • an absolutely automatic regulation of the amplification of the transmitter amplifier can be brought about in a simple manner by putting the resistance R in the photo cell circuit (see Figure 2), so that the grid of the first valve obtains its signal from the voltage drop across this resistance, thus automatically regulating the input according to the lighter or darker printing of the transmitting films.
  • the invention can be so arranged that by the aid of an auxiliary light source, or even the projection light itself, the film is illuminated and the transmitted light arranged to fall upon a resistance whose value depends on the illumination, for example, a second photo cell or a selenium cell.
  • the selenium cell can, for example, be used directly as a grid resistance of the first valve (see resistance R in Figure 2).
  • the resistance of the selenium cell will then automatically become lower with lightly printed films and higher with darkly printed films, so that the amplification is automatically decreased in the first case and increased in the last case.
  • the same effect can also be obtained by connecting the cell in the anode circuit.
  • the brightness sensitive resistance photo cell or selenium cell
  • the invention can also be used on all usual connections of the photo cell and the first valve of the amplifier without further trouble.
  • the idea of this invention lies in the fact that by using a quite simple method, a complete automatic regulation of the alternating current amplitude applied to the transmitting device, or the degree of amplification corresponding to the copying of the transmitting film results, in any case, in only a good television picture being sent out.
  • a necessary condition is that the amplifier circuit is correctly proportioned and adjusted for a suitably chosen normal film.
  • a photo cell for transmission of films of varying density, the combination of a photo cell and an amplifier at the transmitting end, and a light source depending upon its operation on an alternating voltage at the receiving end, means for automatically smoothing out excessive variations of alternating current amplitudes in the photo cell circuit when a film of great contrast is transmitted, in order to pass a substantially constant alternating current amplitude to the receiving light source, whereby an overloading of the latter is prevented, said means comprising a resistance in the circuit of the photo cell, a condenser shunted across the terminals of said resistance, and a thermionic valve having its grid circuit connected with the out-put of the amplifier and its anode circuit connected with the terminals of said resistance, whereby any excessive increase in the alternating current amplitude of the amplifier results in a lowering of the voltage drop across said resistance and in a decrease of the photo cell voltage.
  • a photo cell at the transmitting end and an amplifier for the voltage variations produced by said photo cell, a light source at the receiving end operated by alternating voltage including the arrangement of a compensating device adapted to supply said light source with substantially constant alternating current amplitudes to prevent an overloading of said light source, said compensating device comprising a thermionic valve having its grid circuit connected with the out-put circuit of the amplifier at the transmitting end, and having a resistance shunted by a condenser in its anode circuit, said resistance being arranged in the photo cell circuit to vary the voltage therein, to thereby decrease the sensitiveness of the photo cell when a film of great contrast is transmitted.
  • a television system for transmission of films, pictures, scenes and the like by means of a photo-cell and an amplifier at the transmitting end and a light source depending upon its operation on an alternating voltage at the receiving end, means for selecting the low-frequency variations of alternating current amplitudes in the photo-cell circuit and means adapted for regulating automatically the alternating current voltage input of the amplifier to pass a substantially constant alternating current amplitude to the receiving light source, said means comprising in the circuit of the photo-cell a resistance shunted by a condenser and connected with its terminals to a circuit supplied with a voltage varying in accordance with the electrical impulses in the out-put circuit of said amplifier, whereby the voltage drop across said resistance is varied to vary the sensitiveness of the photo-cell.
  • a television system for transmission of films, pictures, scenes and the like by means of a photo-cell and an amplifier at the transmitting end and a light source depending upon its operation on an alternating voltage at the receiving end, means for selecting the low-frequency variations of alternating current amplitudes in the photo-cell circuit and means adapted for regulating automatically the alternating current voltage input of the amplifier, to pass a substantially con- 'stant alternating current, amplitude to the receiving light source, said means comprising a resistance shunted by a condenser in the circuit ofthe photo-cell and a thermionic valve having its grid circuit connected with the out-put of the amplifier and its anode circuit connected with the terminals of said resistance, whereby any excessive increase in the alternating current amplitude of the amplifier as caused by excessive contrasts in the picture results in a lowering of the voltage drop across said resistance and in a decrease of the photo-cell voltage whereby an overloading of the light source at the receiving end is avoided.
  • a transmitter employing a photo-cell, a photo-cell circuit and means for amplifying the voltage variations produced by said photo-cell
  • a receiver provided with a source of light responsive to the alternating current amplitudes of said transmitter, and means for automatically controlling the alternating current voltage input of said amplifying means to pass a substantially constant alternating current amplitude to the source of light of the receiver to prevent an overloading of said source of light
  • said means comprising a thermionic valve, leads connecting the grid terminals of said valve with the out-putof said amplifying means, a condenser in each of said leads, and a resistance connecting said leads, and a resistance shunted by a condenser in the anode circuit of said valve, said last named resistance being arranged in said photo-cell circuit to vary the voltage therein, the voltage and the sensitiveness of said photo-cell being decreased when due to excessive contrasts in the televised picture the alternating current amplitude applied to the grid circuit of said valve increases.
  • means for developing picture signals and including a photocell means for amplifying and transmitting said signals, means supplied from the amplifying means and operating to rectify the picture signals, and connecting means for applying the rectified picture signals to a control point in said system to vary the bias on said cell.
  • means for developing picture signals including a photocell and means for supporting and moving a motion picture film in cooperative relation with respect to said cell, and means for varying the negative voltage on said cell, said last-named means being responsive to conditions of variation in average light intensity to which said cell is subjected from a film during the respective picture-frame periods and being operable to efiect variation in the negative voltage on said cell inversely proportionally to occurring variations in such conditions of light intensity.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Color Television Image Signal Generators (AREA)
US598476A 1931-03-12 1932-03-12 Automatic regulation of the amplification in tele-cine transmitting amplifiers Expired - Lifetime US2063694A (en)

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Application Number Priority Date Filing Date Title
DE2063694X 1931-03-12

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US2063694A true US2063694A (en) 1936-12-08

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US598476A Expired - Lifetime US2063694A (en) 1931-03-12 1932-03-12 Automatic regulation of the amplification in tele-cine transmitting amplifiers

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US (1) US2063694A (fr)
FR (1) FR732780A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2506668A (en) * 1946-10-31 1950-05-09 Rca Corp Gain control system for facsimile scanning
US2564572A (en) * 1946-10-31 1951-08-14 Rca Corp Gain control system for facsimile scanning

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE744829C (de) * 1933-01-31 1944-06-13 Opta Radio Ag Verfahren zur Fernsehuebertragung beliebiger Spielfilme
DE766547C (de) * 1936-11-12 1954-08-09 Fernseh Gmbh Schaltung mit veraenderlichem Verstaerkungsgrad zur Verstaerkung von Bildzeichen

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2506668A (en) * 1946-10-31 1950-05-09 Rca Corp Gain control system for facsimile scanning
US2564572A (en) * 1946-10-31 1951-08-14 Rca Corp Gain control system for facsimile scanning

Also Published As

Publication number Publication date
FR732780A (fr) 1932-09-26

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