US2137010A - Television system - Google Patents

Television system Download PDF

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Publication number
US2137010A
US2137010A US729730A US72973034A US2137010A US 2137010 A US2137010 A US 2137010A US 729730 A US729730 A US 729730A US 72973034 A US72973034 A US 72973034A US 2137010 A US2137010 A US 2137010A
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United States
Prior art keywords
impulses
frequency
control
oscillator
tube
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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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US729730A
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English (en)
Inventor
Alda V Bedford
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.)
RCA Corp
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RCA Corp
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Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
Priority to US729730A priority Critical patent/US2137010A/en
Priority to FR790824D priority patent/FR790824A/fr
Priority to DER2934D priority patent/DE942451C/de
Priority to GB16872/35A priority patent/GB458161A/en
Application granted granted Critical
Publication of US2137010A publication Critical patent/US2137010A/en
Anticipated expiration legal-status Critical
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
    • H04N5/04—Synchronising
    • H04N5/06—Generation of synchronising signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising

Definitions

  • My invention relates to television systems and particularly to television systems which comprise a cathode-ray transmitter tube and an electric discharge tube generator of defiecting and synchronizing impulses.
  • An object of my invention is to provide an improved television system in which pictures transmitted from a lm are properly framed.
  • an object of my invention is to provide a. television system, utilizing an electric discharge tube impulse generator, in which pictures transmitted from a film are always properly framed.
  • a further object of my invention is to provide a television transmitter in which the frequency of an electric discharge tube impulse generator is held substantially constant.
  • a further and more specific object of my invention is to control the frequency of an electric discharge tube impulse generator with respect to the frequency of the current from a power line or the like.
  • a vacuum tube impulse generator which has an output suitable for interlaced scanning as described in my above-mentioned copending application.
  • a motion picture film having a picture thereon to be transmtted is moved into position in a lm gate by means of a standard intermittent mechanism which is driven by a synchronous motor connected to a 60 cycle power line.
  • Fig. 2 is an end view of a shutter disc shown in Fig. 1,
  • Fig. 3 is a group of curves which are referred to in explaining my invention.
  • Fig. 4 is a circuit diagram of an amplifier employed in the system shown in Fig. 1,
  • Fig. 5 is a set of curves which are referred to in explaining the operation of my control circuit.
  • Fig. 6 is a chart illustrating the operation of the picture projector and scanner.
  • a. television transmitter system which includes a cathode ray transmitter tube I of the type described in an article by Dr. V. K. Zworykin which appears in the January, 1934, issue of The Journal of The Franklin Institute.
  • 'Ihis tube comprises an evacuated envelope 3 having an electron gun 5, a focusing and accelerating anode 1 and a mosaic 9 of light sensitive elements thereon.
  • Defiecting means such as defiecting coils II and I3, are provided for defiecting the electron beam horizontally and vertically, respectively, in order to scan the mosaic 9 with the beam.
  • an electric discharge tube impulse generator is provided.
  • This generator consists of a main oscillator I5 from which are derived electrical impulses of the desired frequency for horizontal deflection and also electrical impulses of the desired frequency for vertical deflection.
  • the main oscillator I5 may be a blocking oscillator consisting of an electrical discharge tube I1 having a cathode I9, a control grid 2l and an anode 23.
  • is connected through a variable grid leak resistor 25 and through a resistor 21 in the control circuit (which will be described hereinafter) to ground and through ground to the cathode I9. ⁇
  • the anode 23 is maintained at a positive potential by means of a suitable voltage source such as a battery 29 which has its negative terminal connected to the cathode l5 and its positive terminal connected through a resistor 3
  • a condenser 31 is connected in series with the secondary 33 of the transformer 35, the condenser 31 and secondary 39 being connected between the control grid 2l and the cathode I9.
  • the transformer windings 33 and 35 are so phased that sfn increase in plate current in the tube I1 causes the control grid 2l to become more positive whereby grid current flows into the grid condenser 31 to charge it in such a direction as to apply a negative bias to the control grid 2l.
  • the plate current finally approaches its saturation value so that its rate of increase becomes less, the voltage fed back to the grid decreases whereby the plate current decreases, thus reversing the phase of the voltage applied to the control gri4 through the transformer 35 and biasing the tube I1 beyond cut-0H.
  • Ihe voltage impulses produced by the oscillator l5 are impressed upon a chain of frequency dividers Il, 43, 45, and 41, each of which may be a blocking oscillator operating the same as the main oscillator l5 but at a lower frequency. Each oscillator is locked in step with the oscillator of next highest frequency.
  • the circuit of the frequency divider 4I is illustrated in order to illustrate the invention more completely but a description of the circuit is not believed to be necessary in view of the description of the main oscillator circuit I5.
  • the frequency of the main oscillator output is divided in two steps of three and two steps of five, as indicated on the drawings to produce voltage impulses occurring at the rate of 48 per second, this being the desired vertical deflecting or frame frequency.
  • the 48 cycle impulses are supplied to the input circuit of a saw-tooth Wave generator 4I which converts them into voltage impulses of the necessary shape for causing a flow of current, having a saw-tooth wave shape, through the deflecting coils I3.
  • 'I'he horizontal defiecting impulses are obtained by impressing a portion of the output energy of the main oscillator I5 upon the input circuit of a frequency divider 5i which divides the frequency of the main oscillator output by two to produce 5400 impulses per second.
  • is impressed upon a saw-tooth wave generator 53 which has its output connected across the horizontal deecting coils Il for causing a iiow of saw-tooth wave current therethrough.
  • My improved television system is especially designed, as will .be explained hereinafter, for the transmission of pictures on a motion picture film, such a film being indicated generally at 55.
  • the picture frames are moved intermittently into position in a film gate 51 by means of a standard intermittent 59.
  • 'I'he intermittent 59 is driven through a gear box 6I by a synchronous motor 53 at the standard speed whereby 24 pictures per second are projected upon the mosaic 9.
  • a shutter disc 55 is also driven by the synchronous motor 53 through the gear box 5i, it being rotated at 24 revolutions per second.
  • the shutter disc 55 has two openings 61 and 69 therein which are diametrically opposite each other for the purpose of cutting of! the light projected toward the mosaic periodically, as will be more fully explained hereinafter.
  • a control circuit 1i is provided for maintaining the impulse generator locked in with the 60 cycle power line 13 to which the motor 53 is connected.
  • the control circuit includes an electric discharge tube 15 having a cathode 11, a control grid 19 and an anode 8l.
  • the tube 15 is so adjusted that it functions as a distorting amplifier or detector. In one specific embodiment this is accomplished by maintaining the control grid 19 at a high negative bias by means of a biasing source, such as a battery 83, the negative bias being high enough to bias the tube beyond the cut-off potential.
  • is maintained at a positive potential by means of a source of potential, such as a battery 85, having its negative terminal connected to the cathode 11 and its positive terminal connected to the anode 8l through the resistor 21.
  • the resistor 21 is shunted by a filter condenser 81.
  • the resistor 21 is connected in series with the grid leak resistor 25 of the blocking oscillator l5 whereby any change in voltage drop across the resistor 21 causes a. change in the bias on the control grid 2l of the blocking oscillator.
  • 'I'he filter condenser 81 has sufficient capacity to integrate current impulses and cause a substantially steady flow of current through the resistor 21.
  • the current flow through the control circuit resistor 21 is caused to vary in response to a phase shift between frequency of the 60 cycle current from the power line 13 and the frequency of the impulse generator output by impressing the impulses from both the power line and the impulse generator upon the input circuit of the control tube 15.
  • the two groups of control impulses occur at the same frequency. Therefore, since current from the power line has a frequency of 60 cycles and the impulses from the vertical deecting circuit occur at the rate of 48 per second, the 48 cycle impulses are impressed upon a frequency divider 89 which lowers the frequency to 12 impulses per second. The output of the frequency divider 89 is impressed upon a wave shaping amplifier 9
  • a frequency divider 95 which divides the frequency by five to produce impulses occurring at the rate of 12 per second. Both the frequency divider 95 and the frequency divider 89 ⁇ particularly when the may be blocking oscillators similar to the ones described above.
  • the impulses appearing in the output circuit of the frequency divider 95 are impressed upon a wave shaping amplifier 91 from lthe output of which they are fed into the input 4circuit of the control tube 15 through a transformer 99 in such phase that they add with the 12 cycle impulses from amplier 9
  • and 91 may be omitted, if desired, distorting or detector tube 15 is biased to cut-olf, as described. Also, if
  • the sine wave current therefrom may be impressed directly upon the control tube circuit 1
  • Fig. 3 shows the wave shape of the voltage impulses appearing in the output circuit of a frequency divider where it is a blocking oscillator.
  • 03 are typical of the voltage impulses generated by a blocking oscillator. It will be noted that each wave includes a sharp positive impulse, this impulse being the one which is used for control purposes.
  • and 91 cut od the portion of the voltage wave which appears below the dotted line
  • the amplifier consists of two resistance coupled amplifier stages, the first stage comprising an electric discharge tube
  • the second amplier stage includes an electric discharge tube which is biased to function as a non-distorting amplifier.
  • 01 permits the passage of only the positive peak of the blocking oscillator voltage wave, that is, the portion of the wave above the dotted line
  • and 91 appear in the input circuit of the control tube 15 as shown at
  • the grid lvoltage-plate current characteristic of the tube 15 is shown at
  • 3 and H5, shown in Fig. 5 are the impulses derived from the power line and from the oscillator, respectively.
  • the oscillator frequency decreases to shift the oscillator control impulse to the position shown by the dotted curve
  • this causes less current to flow through the resistor 21 whereby the negative potential 20 applied to the control grid 2
  • the frequency of the main oscillator I5 may be controlled by the control circuit 1
  • the voltage drop across the resistor 21 may be utilized to change the potential on the anode 23 of the blocking oscillator tube
  • the control impulses applied to the control circuit need not have the same frequency so long as they bear a. whole number multiple frequency relation to each other, as in the case of one group of impulses occurring at twice the frequency of the other group.
  • and its associated circuits causes the mosaic 9 to be scanned synchronously with the projection of the picture frames thereon.
  • the picture projection! and scanning operation is illustrated on the chart in Fig. 6.
  • the picture is projected upon the mosaic 9 at the time A and remains thereon until the time B, at which time the shutter 55 intercepts the beam of light from the projector.
  • the cathode ray has been brought to its starting position for scanning and the film has been stationary.
  • the cathode ray starts scanning the mosaic and completes the scanning at the time C, the film being stationary during this scanning period and there being no light upon the mosaic.
  • the second shutter opening 99 rotates into position opposite the projector to permit the picture to be again projected upon the mosaic until the time D. at which time the light is again intercepted by the shutter 55. At this time, the cathode ray again begins to scan the mosaic 9, the mosaic again being dark.
  • the intermittent 59 starts to move the next picture frame into position
  • the next picture frame has been moved into position and the intermittent stops. I'he scanning of the dark mosaic con- 75 tinues until the time A. ai' which time the first shutter opening 51 again moves into position opposlte the projector and the second picture frame is projected upon the mosaic.
  • the horizontal synchronizing impulses are impressed through a wave shaping amplifier
  • the vertical defecting impulses are impressed through a wave shaping amplifier
  • the horizontal and vertical synchrozing impulses are impressed upon such a stage in the amplifier
  • 31 may be the same as the amplifier shown in Fig. 4 except that it is preferred to adjust the plate resistor of the first tube such that. the signal strength on the grid of the second tube I I I causes the grid to cut off the plate current of the second tube near the peaks of the negative swing.
  • the wave shaping amplifiers so adjusted, the lower portion of each blocking oscillator impulse is cut off as indicated by the dotted line
  • the synchronizing impulses before they are impressed upon the picture signal amplifier
  • the horizontal synchronizing impulses are transmitted at the end of each scanning line while the vertical synchronizing impulses are transmitted at the end of each picture frame whereby the picture signals and the synchronizing signals are not transmitted simultaneously.
  • a television system including a cathoderay transmitter tube having a mosaic of electron emissive capacity elements therein, means for generating horizontal and vertical deiiecting impulses for said tube, said means including an oscillator, means for obtaining a voltage wave from an alternating current source, means for moving a film having a picture thereon to be transmitted, said means including a synchronous motor connected to said source, means for projecting the pictures of said film upon said mosaic, means for obtaining control impulses having a fixed frequency relation to said vertical deflecting impulses, means for impressing said control impulses and said voltage wave upon a common circuit, means for producing a substantially steady current having a value depending upon the phase relation of said control impulses and said wave in said common circuit, and means for controlling the frequency of said oscillator in accordance with the value of said substantially steady current.
  • a television system including a cathoderay transmitter tube having a mosaic of electron emissive capacity elements therein, means including an oscillator for generating comparatively high frequency horizontal defiecting impulses and comparatively low frequency vertical defiecting impulses for defiecting the cathode ray in said tube, means for obtaining comparatively low frequency control impulses from said oscillator, means for obtaining periodic voltage pulses from an alternating current power source, means for intermittently moving a film having a picture thereon to be transmitted, said means including a synchronous motor connected to said power source, means for projecting a frame of said ⁇ film upon said mosaic when said film is stationary, and means for controlling the frequency of said oscillator in accordance with the phase difference of said control impulses and said voltage impulses.
  • means for generating horizontal and vertical defiecting impulses for producing said deflection said means including an oscillator, means for obtaining a voltage wave from an alternating current source, means connected to the power supply for moving a film having pictures thereon with a motion having a predetermined relation to the frequency of said alternating current, means for projecting the pictures of said film upon said screen surface, means for obtaining control impulses having a fixed frequency relation to said vertical deecting impulses, means for impressing said control impulses and said voltage wave upon a common circuit, means for producing a substantially steady current having a value depending upon the phase relation of said control impulses and said wave in said common circuit, and means for controlling the frequency of said oscillator in accordance with the value of said substantially steady current.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
  • Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
  • Selective Calling Equipment (AREA)
US729730A 1934-06-09 1934-06-09 Television system Expired - Lifetime US2137010A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US729730A US2137010A (en) 1934-06-09 1934-06-09 Television system
FR790824D FR790824A (fr) 1934-06-09 1935-06-03 Perfectionnements aux systèmes de télévision
DER2934D DE942451C (de) 1934-06-09 1935-06-09 Schaltungsanordnung fuer Fernsehsender zur Regelung eines die Bildwechselablenkung steuernden Impulsgenerators entsprechend den Netzschwankungen
GB16872/35A GB458161A (en) 1934-06-09 1935-06-11 Improvements in or relating to television systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US729730A US2137010A (en) 1934-06-09 1934-06-09 Television system

Publications (1)

Publication Number Publication Date
US2137010A true US2137010A (en) 1938-11-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
US729730A Expired - Lifetime US2137010A (en) 1934-06-09 1934-06-09 Television system

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Country Link
US (1) US2137010A (de)
DE (1) DE942451C (de)
FR (1) FR790824A (de)
GB (1) GB458161A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2700102A (en) * 1945-09-14 1955-01-18 Richard H Woodward Long range navigation system
US2765422A (en) * 1951-11-19 1956-10-02 Itt Television camera tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2137010A (en) * 1934-06-09 1938-11-15 Rca Corp Television system
DE758534C (de) * 1939-06-03 1954-11-22 Opta Radio A G Anordnung zur Frequenzteilung einer Impulsspannung

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE570437C (de) * 1933-02-16 Int Standard Electric Corp Schaltungsanordnung zum Unterdruecken der bei Wechselstromheizung von Elektronenroehren auftretenden Stoerungen
US1547217A (en) * 1924-07-11 1925-07-28 American Telephone & Telegraph Phase regulator for multifrequency generators
DE498415C (de) * 1924-12-09 1930-05-22 Paul Nipkow Einrichtung zur Erzielung des Synchronismus bei Apparaten zur elektrischen Bilduebertragung
US1688916A (en) * 1926-12-11 1928-10-23 Lorenz C Ag Means for synchronizing two or more rotating bodies
GB282098A (en) * 1926-12-11 1928-08-23 Lorenz C Ag Improvements in or relating to the maintenance of constant frequency and phase relationship in periodic processes
US1788533A (en) * 1927-03-28 1931-01-13 Bell Telephone Labor Inc Frequency-control system
US2166247A (en) * 1927-09-14 1939-07-18 Western Electric Co Electro-optical transmission system
FR709287A (fr) * 1931-01-17 1931-08-05 Ets Edouard Belin Perfectionnements aux systèmes de synchronisation par triodes applicables notammentà la transmission des images
GB402291A (en) * 1932-03-07 1933-11-30 Loewe Opta Gmbh A method of synchronising television receiving apparatus by the transmitter
DE566663C (de) * 1932-04-07 1932-12-22 Telefunken Gmbh Verfahren zur UEbertragung von bewegten Bildern
DE589832C (de) * 1932-06-16 1933-12-15 Telefunken Gmbh Verfahren zur Synchronisierung von Gleichwellensendern
US2178218A (en) * 1934-05-18 1939-10-31 Rca Corp Television system
US2137010A (en) * 1934-06-09 1938-11-15 Rca Corp Television system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2700102A (en) * 1945-09-14 1955-01-18 Richard H Woodward Long range navigation system
US2765422A (en) * 1951-11-19 1956-10-02 Itt Television camera tube

Also Published As

Publication number Publication date
FR790824A (fr) 1935-11-28
GB458161A (en) 1936-12-11
DE942451C (de) 1956-05-03

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