US2152234A - Television system - Google Patents

Television system Download PDF

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Publication number
US2152234A
US2152234A US623325A US62332532A US2152234A US 2152234 A US2152234 A US 2152234A US 623325 A US623325 A US 623325A US 62332532 A US62332532 A US 62332532A US 2152234 A US2152234 A US 2152234A
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US
United States
Prior art keywords
scanning
picture
ray
lines
cathode ray
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
US623325A
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English (en)
Inventor
Randall C Ballard
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
Original Assignee
RCA 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
Priority to BE397676D priority Critical patent/BE397676A/xx
Priority to BE409519D priority patent/BE409519A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US623325A priority patent/US2152234A/en
Priority to GB20410/33A priority patent/GB420391A/en
Application granted granted Critical
Publication of US2152234A publication Critical patent/US2152234A/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
    • 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
    • H04N3/30—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical otherwise than with constant velocity or otherwise than in pattern formed by unidirectional, straight, substantially horizontal or vertical lines
    • H04N3/34—Elemental scanning area oscillated rapidly in direction transverse to main scanning direction

Definitions

  • My invention relates to improvements in television systems and, more particularly, to an improved method of scanning.
  • cathode ray tube for receiving purposes resides in the feature of retentivity of fluorescence of the fluorescent screen with which the tube is provided, which screen is scanned by the cathl ode ray.
  • i-t has been determined that, for the purpose of making use of this fluorescence to the best advantage, the received picture frequency should not be materially greater than sixteen pictures per second.
  • Another object of my invention is to provide an improved television system for the transmission of sound film, wherein the frequency channel required for television is reduced without changing from the standard rate of 24 pictures a second at which the nlm is run.
  • Another object of my invention is to provide an improved method of operation whereby the number of picture lines can be substantially in- 5 creased without necessitating an increase in the required frequency channel.
  • Another object of myinvention is to provide an improved method whereby the optical effect, referred to as icker, is eliminated or reduced 10 to a. negligible degree.
  • Fig. 2 is an enlarged elevational view of the 20 scanning disc in Fig. 1, looking toward the left in this figure; l
  • Fig. 3 is a diagrammatic view of a television receiving system constructed and operable in accordance with my invention
  • 25 Fig. 4 is a schematic illustration of the manner in which the cathode ray scans the uorescent screen in Fig. 3.
  • My invention resides in the improved system and method of operation of the character here- 30 inafter described and claimed.
  • the transmitting system shown in Fig. 1 comprises a scanning disc III provided with apertures at its edge arranged on a circle concentric, with the axis of rotation of the disc.
  • Light from a 35 suitable source I2 passes through these apertures and through a standard sound film I4 onto a photoelectric cell I6.
  • Picture signals are thereby developed and, after passing through a plurality of amplifiers I8 and. 20 and a modulator 40 22, may be radiated by a suitable radio transmitter 24 or otherwise conveyed to distant receiver-locations.
  • the film I4 is supported in the usual manner, and is fed along at the normal rate of 24 pic- 45 tures a second.
  • the disc III is provided with other apertures through which 50,
  • the disc I0 Assuming that it is desired to reproduce an 8 0 line picture at the receiving station, the disc I0, for this purpose, is provided with 81 apertures A1 to Asi, and is rotated at the rate of twelve revolutions a second, or x/2 the picture frequency at which the nlm I4 is run.
  • the operation therefore, is such that each picture of the lm Ais scanned along 40.5,lines.
  • the disc is also provided with .a'plurality of apertures a1 to an. equal in number to the picture apertures, these apertures being so arranged, as will be well understood, that a4 synchronizing impulse is developed? and ,t ransrnitted at the end of each picture line.
  • One: of ⁇ these apertures that is, the aperture a for example, is made substantially larger than the others for the purpose of developing a framing impulse.
  • I is provided with another framing aperture or opening, disposed as shown, diametrically opposite the openingzgg, and between synchronizing apertures ani-sind The reason for this particular arrangement "will be understood during the course of the following description and explanation; 3
  • the disc III is rotated at the rate oi' one revolution for every twofr'ames of the film.
  • the disc is provided with an Aodg! ⁇ number of pictur apertures, that is, 81, eachpicture of the lm will be scanned along 40.5 lines. ⁇
  • the framing opening 34 wilf be in position between the light source 26 andfthe photoelectric cell 26 to effect transmission of a framing impulse.
  • the aperture aas will be in poqtion to effect transmission of a second framing impulse. This second framing impulse'oocurs at the end of the 81st scanning line, at the end of each complete revolution of the disc.
  • the transmitted picture signals and the synchronizing and framing impulses are received by a suitable radio receiver 36, and appear across resistances 38, 46 and 42.
  • 'Ihe picture signals which are positive in sign, are taken from the resistance 36 and are applied, by a connection 44, to the control grid 46 of a cathode ray tube 46. In this manner, the intensity of the ray 60 is varied in accordance with the picture signals.
  • the 'I'he cathode ray tube is provided, at its large which the ray 50 is caused to scan in a manner simulating the scanning action at the transmitter.
  • the ray is deflected horizontally 972 times a second by causing a saw-tooth current wave, at this frequency, to pass througha plurality of horizontal deflection lcoils 54.
  • These coils are supplied from a suitable generator 56 for this purpose, which is locked in step with the line-scanning frequency at the the resistance 40 and applied to the input circuit of this generator.
  • the frequency of 972 cycles is required on account of the fact that the transmitter by ⁇ the received synchronizingimpulses taken from transmitting disc has 81 picture apertures and rotates at the rate of twelve revolutions a second.
  • the ray 60 is deflected vertically at the rate of 24 times a second by electromagnetic coils 56 through which a saw-tooth current wave at this frequency is caused to pass.
  • a suitable generator 60 operates to generate this wave. and is locked in step with the framing frequency at the trans'- mitter by taking the framing impulses from the Yof my present invention, they are not illustrated in detail.
  • Fig. 4 is a schematic representation of the approximate path along which the ray scans the fluorescent screen 62, the figure being considered as a view looking toward the left in Fig. 3.
  • the area of the fluorescent screen which is scanned by the ray 66 is always the same, that is, the area ABCD.
  • the aperture aan at the transmitter is in position to eifect transmission of a second framing impulse, whereupon the rayl is returned vertically to the point B along the path shown.
  • the ray reaches the point H at the instant kof completion of what would have been the scanning line 80, and reaches the point B at the completion of what would have been theline 81.
  • return deflection of the ray horizontally occurs in zero time. From .the
  • the screen 52 is scanned horizontally along '77 effectivelines, and that a time period corresponding to 4 lines is used in the vertical return of theA ray.
  • the cathode ray tube presents what appears to be a normal 'VI-line picture.
  • the tube is presenting .a series of 38.5 line pictures which intermesh or are interwoven with each other. Due to the persistence of the fluorescent screen, the optical effect is the same as though the ⁇ picture were comprised of 77 lines occurring in succession. At the outset, it was stated that an 80-line picture was to be reproduced. This assumption was for convenience.
  • the frequency channel required for a T7-line picture in my improved system will be that corresponding approximately to a l-line picture. With such a low limit of channel requirement for a 'f7-line picture, it would be feasible to change to a picture of more lines, up to the limitation imposed by transmission requirements.
  • Another advantage of my improved method and system resides in the fact that standard sound film can be run at the normal rate, and the fluorescent screen in the cathode ray tube at the receiving station can, at the same time, be scanned in such manner as to obtain the full advantage of the fluorescent effect, all without requiring cumbersome and costly constructions, as heretofore.
  • apertures or opening is used in the specification and claims in a broad sense, and is intended to cover the various well-known modifications such, for example, as the disc construction with lenses inserted in apertures or openings.
  • vertical deflection cycle means the complete cycle of deflection caused by the vertical deecting means, this complete cycle consisting of a useful deecting period and a return line period.
  • horizontal deection and vertical deflection refer to the fast and slow deflections, respectively, and are not limited to the direction of viewing or space location of the deiiections.
  • a system for producingv television images utilizing a skip line scanning which comprises a cathode ray tube having a fluorescent screen and having means to develop a cathode ray and means for causing the developed ray to produce the effect of varying intensities of light and shadow on said uorescent screen, means for producing a deflection of the ray in its passage through the tube to cause the ray to traverse the said screen in paths bearing an angular relationship to each other, and means coordinated with the deilecting means for alternately changing the predetermined control paths of position at which the ray produces the fluorescent effects to cause successive traversals of the complete predetermined pattern traced upon the fluorescent screen to be interspersed.
  • a Atelevision receiver comprising the combination of a cathode ray tube having a target element and means to develop'a cathode ray and means for causing the cathode ray to traverse in a series of adjacent lines a predetermined pattern on the target element, and means for causing at the completion of each of a plurality of lines of travel corresponding substantially to an entire image representation, a separation between successive complete paths of traversal .so as to produce an interspersed series of complete traversals wherein the individual lines of each image representation alternate.
  • a television transmission system for moving picture lm, means for supporting and imparting feeding movement to a film, means for developing picture signals comprising a rotatable disc for scanning said film, said disc being provided with picture apertures all of which are disposed on a single circle concentric to the axis of rotation thereof, and means for rotating said disc; said system being characterized by the fact that the rate of feeding movement of the film, 1n terms of pictures per second, is twice the rate of rotation of said disc, in terms of complete revolutions per second, and further characterized in that the number of said apertures divided by said rate of feeding equals a whole number plus onehalf.
  • a television receiver comprising a cathode ray tube having therein means to develop a cathode ray and a fluorescent screen-to produce luminous effects, means arranged in cooperative relationship with the cathode ray tube for causing the developed cathode ray to traverse the screen along a series of substantially parallel paths, and means to produce at the completion of a predetermined number of parallel paths of traversal a second series of substantially parallel paths interlaced with respect to the flrst series of parallel paths so that alternately produced series of complete traversals of the screen by the cathode ray are interspersed.
  • a system for producing television images utilizing skip-line scanning which comprises a cathode ray tube having means to develop a cathode ray and means for causing the developed ray to produce the effect of varying intensities of light and shadow on the fluorescent end wall ofthe tube, means for producing a deection of the ray in its passage through the tube to cause the ray to traverse the screen in paths bearing an angular relationship to each other, and means coordinated with the deecting means for alternately changing the predetermined controlled paths of position at which the ray produces the fluorescent effects to cause successive traversals of the complete predetermined pattern traced upon the tube wall-to be interspersed.
  • a television receiver comprising the combination of a cathode ray tube having means to develop a cathode ray and means for causing the cathode ray to traverse in a series of adjacent interpersed scanning lines,
  • the method oiuscan-l ning a picture area which comprises deiiecting a scanning ray vertically and simultaneously causing the scanning ray to traverse the entire width of said area a plurality of times and a fraction oi' said width once during a vertical deectingcycle, said fraction being greater than one-eighth, and next causing said ray to again traverse the entire width of said area a plurality of times and a fraction of said width once during the next vertical deflection cycle, said lastmentioned fraction being the same as the rstmentioned fraction, and interlocking said vertical deection and said width traversals to maintain'a xed frequency relation therebetween, said fraction having a numerator and a denominator each of which is a whole number.
  • the method of scanning a picture area which comprises causing a scanning ray to traverse said area both horizontally and vertically to produce during a vertical deflection cycle a plurality o1' scanning lines each having a certain length and an additional scanning line having a length which is a fraction of the length of any one line of said plurality o!
  • a scanning ray to traverse a given area horizontally :c times per second
  • -means for causing said ray simultaneously to traverse said area vertically y times per second
  • a cathode ray tube means for deiiecting the cathode ray at a freode ray simultaneously at a frequency rate of y,
  • means for producing horizontal synchronizing impulses occurring at a frequency z means for producing vertical synchronizing impulses occurring at a frequency y, and means for interlocking said rst means and said second means to maintain a xed frequency relation between :c and 1r, where K whereby said area is scanned successively K times .with the scanning lines oi' said successive K scannings of said area interspersed or interlaced, A being a whole number less thanx, and where y is such a value that and where' is a whole numso small that the K number of scannings are repeated at a rate at least equal to that at which persistence of vision substantially causes icker disappearance.
  • the method of scanning a picture area which comprises deilecting a scanning ray vertically and simultaneously causing the scanning ray to traverse the entire width of said area a plurality of times and a fraction of said width once during a vertical deection cycle, said fraction vbeing greater than oneeighth, and next causing said ray-to again traverse the entire width oi' said area a plurality oi' times and a fraction of said width once during deflecting cycle, said lastmentioned fraction being the same as the firstmentioned fraction, interlocking said vertical deection and said width traversals to maintain a fixed frequency relation therebetween, and completing the cycle of scanning by repeating the vertical traversal n times per cycle of scanning where .l n is the selective fraction.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Selective Calling Equipment (AREA)
  • Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
US623325A 1932-07-19 1932-07-19 Television system Expired - Lifetime US2152234A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE397676D BE397676A (tr) 1932-07-19
BE409519D BE409519A (tr) 1932-07-19
US623325A US2152234A (en) 1932-07-19 1932-07-19 Television system
GB20410/33A GB420391A (en) 1932-07-19 1933-07-19 Improvements in or relating to television systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US623325A US2152234A (en) 1932-07-19 1932-07-19 Television system

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US2152234A true US2152234A (en) 1939-03-28

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Application Number Title Priority Date Filing Date
US623325A Expired - Lifetime US2152234A (en) 1932-07-19 1932-07-19 Television system

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US (1) US2152234A (tr)
BE (2) BE409519A (tr)
GB (1) GB420391A (tr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521008A (en) * 1944-06-27 1950-09-05 John H Homrighous Television and sound multiplex system
US2546972A (en) * 1945-03-17 1951-04-03 Int Standard Electric Corp Television synchronizing system
US3351707A (en) * 1965-05-04 1967-11-07 Photo Electronics Corp Electronic color viewer
US3624291A (en) * 1968-12-28 1971-11-30 Olympus Optical Co Optically interlaced scanning and reproducing apparatus using multiple drums to permit scanning of motion picture film or stationary film

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR819883A (fr) * 1936-07-04 1937-10-28 Perfectionnements aux appareils de télévision notamment à leurs systèmes de balayage

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521008A (en) * 1944-06-27 1950-09-05 John H Homrighous Television and sound multiplex system
US2546972A (en) * 1945-03-17 1951-04-03 Int Standard Electric Corp Television synchronizing system
US3351707A (en) * 1965-05-04 1967-11-07 Photo Electronics Corp Electronic color viewer
US3624291A (en) * 1968-12-28 1971-11-30 Olympus Optical Co Optically interlaced scanning and reproducing apparatus using multiple drums to permit scanning of motion picture film or stationary film

Also Published As

Publication number Publication date
GB420391A (en) 1934-11-30
BE397676A (tr)
BE409519A (tr)

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