US2274366A - Television scanning - Google Patents

Television scanning Download PDF

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Publication number
US2274366A
US2274366A US259194A US25919439A US2274366A US 2274366 A US2274366 A US 2274366A US 259194 A US259194 A US 259194A US 25919439 A US25919439 A US 25919439A US 2274366 A US2274366 A US 2274366A
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United States
Prior art keywords
frequency
lines
line
ratio
scanning
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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
Application number
US259194A
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English (en)
Inventor
Hansen Siegfried
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General Electric Co
Original Assignee
General Electric Co
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Filing date
Publication date
Priority to BE438172D priority Critical patent/BE438172A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US259194A priority patent/US2274366A/en
Priority to FR863581D priority patent/FR863581A/fr
Application granted granted Critical
Publication of US2274366A publication Critical patent/US2274366A/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 the art of television and particularly to the scanning of the screen of a cathode ray tube employed therein.
  • a television system well known at the present time employs double interlaced scanning and has a frame frequency of 30 per second. Such a frame frequency is much higher than is necessary to preserve continuity of motion in the reproduced picture, hence the system is wasteful of band width. Efforts have been made in the past'to reduce the frame frequency, namely, the number of pictures per second, without introducing flicker or impairing continuity of the re- Q improved method of scanning in a cathode ray Because of the great difficulty, if not the impossibility of constructing a patent drawing with which one could trace the movements of the beam in a cathode ray tube in scanning a frame or picture comprising several hundred lines, .I have chosen to describe my invention first as applied to an extremely simple form embodying only a few lines which are widely spaced apart. Having explained the principle by means of this simple example its application to a commercial form will be readily apparent.
  • the electron beam of a cathode ray television tube is made to scan the tube screen or' target whether the tube is of the transmitting type or the receiving type by causing the beam to move simultaneously in two directions substantially at right tube and an improved apparatus for carrying out that method whereby the excessive band width may be materially reduced without the addition of an objectionable amount of crawl.
  • the frame frequency may be greatly reduced without producing an objectionable flicker or lack of continuity of motion.
  • the reduction of the frame frequency permits a corresponding reduction in the band width of frequenciesrequired for the transmission of the picture.
  • Fig. 1 is a circuit diagram illustrating by way of example, one form angles to each other, one being in the direction of the scanning lines, usually horizontal, and the other substantially at right angles thereto, hence, usually vertical.
  • I cause the beam first to scan successively every fifth line, that is, it successively scans lines 1, 6, 11, 16, etc. to the end of the picture and then to scan the intermediate lines in an interlaced manner.
  • This system of scanning I have termed, interlaced quintuple interlace.
  • Fig. 2A where the scanning lines 1, 6, 11 and 16 are shown by a full black line, the horizontal fly backs being shown bylighter full lines. Since lines 1, 6, 11 and 16 divide the total scanning lines into groups of five it is convenient to consider every fifth line as having the same number, such being shown in Fig. 2A by the second column of numbers. In this figure it will be seen that the number of lines called 1, shown by a solid line, is 3%, the first line 1, beginning at the point 1 and the last lin 1 terminating at the point 2, its length being /5 the length of a full line. Vertical fly back then occurs taking the line to the point 3 at the top of the picture where a new line starts which is line 3, represented by dashes.
  • the advantage of the above-described system of interlacing is that the number of frames or pictures per second may be very materially reduced without sacrificing continuity of motion or producing flicker and without objectionable I have found, for example, that whereas the number of frames or pictures per'second common heretofore has been 30, by employing my invention, I can reduce that number by the factor, 2.5, namely, to 12 frames per second and still obtain equally good results.
  • the important result of such a material reduction in the frame frequency required is that it obviously permits a the horizontal and the vertical deflections of the ter oscillator 25 which, in the form of my invencorresponding reduction in the band width of tain the 4 megacycle band width but increase the number of lines.
  • the interlaced quintuple interlace system of scanning which I employ is obtained by supplying the proper frequencies to-the beam deflecting means of a cathode ray tube of a well known form employed in television.
  • the lineor horizontal frequency may be 2l6-cyclesper second and the field or vertical frequency may be 60 cycles per second.
  • a 216 cycle frequency repre sented at 12 will therefore be applied to the horizontal deflecting means of the tube ,and a 60 cycle frequency represented at 13 will be applied to the vertical deflecting means thereof.
  • Fig. 1 the cathode ray tube I5 is shown as a tion represented by Fig. 1, produces a frequency of 26,880 cycles per second.
  • This frequency is supplied to the'multivibrator 26 which, having a ratio of 5, reduces the frequency to 5376 cycles per second.
  • the chain of multivibrators 21, 28 and 29 which, having ratios respectively of 8, 8 and 7, reduce the frequency respectively to 3360 cycles, 420 cycles and 60 cycles per second.
  • the deflecting windings 20 and I9 are supplied with saw tooth waves havin frequencies respectively of 5376 cycles and 60 cycles per second from the saw tooth generators 30 and 3
  • the generator 30 is controlled in a well known manner by the 5376 cycle frequency supplied to it from the multivibrator 26 and likewise the generator 3
  • the ratio of the line -.freqiiency, 5376 cycles, to the vertical frequency, 60 cycles, in this case is 89%; thus, as in the previously described example, this ratio is an integer.
  • the frame frequency or number of complete pictures per second is equal to 60 di vided by 5, namely 12, rather than 30, the number common at present.
  • the "radio transmitter 34 connected toreceivethe output of the tube l5 "and to receivethe output of the supersynchronizing pulse generator 35 which may be of any suitable and well known form, the generator being controlled by connections with the multivibrators 26 and 29 whereby the line and framing synchronizing pulses may be transmitted to the receiver.
  • the ratio of the line frequency to the vertical frequency may be expressed broadly as difleringfrom an integer by F If the system of interlace disclosed in Fig. 28 I beemployed in the more practicable system illus-' trated by Fig. 1 in which the number of lines is approximately standard the master oscillator will have a frequency of 25920 cycles per second, the multivibrator 26 will have a frequency of 5184 cycles per second and the chain of-multifrequency respectively to 23040, 3840, 480 and cycles per second.
  • the deflecting windings 20' vibrators 27, 28 and 29 will have frequencies respectively of 4320, 540 and 60 cycles per second.
  • the saw tooth generator 3.0 in that case will have a frequency of 5184 cycles per second.
  • the ratio of the line frequency to the vertical frequency will be 86 plus which is the same as 8'7 minus in other words, the ratio is a number, which differs from an integer by
  • the interlaced quintuple interlace system which I have devised and described above is not limited to the frequency numbers mentioned above, but may be employed for the production of pictures having a number of lines equal to any number which ends in 2, 3, '7 orB.
  • Fig. 3 I have illustrated a completesystem involving my invention including both the transmitting and the receiving apparatus and employing my interlaced quintuple interlace scanning for a 1152 line picture.
  • the transmitter comprises the cathode ray tube l5 similar to that shown in Fig. 1 and provided with the screen l6 and the optical system H which in this case is represented as being arranged to project a view on the screen,
  • the tube is also provided with the horizontal and pulse generator
  • the ratio of the line frequency, 13824 cycles in this case, to the vertical frequency, 60 cycles, is 230 thus as in the previously described examples this ratio is an integer plus As before the frame frequency, being 60 divided by 5, is 12. Since the ratio is an integer plus the fraction /5 the lines are scanned in the order 1, 4, 2, 5, 3, just as in Fig. 2B.
  • Fig. 3 a diagrammatic representation of suchapparatus including a cathode ray receiver of well known form.
  • the radio signals transmitted by the transmitter 34' and picked up by the antenna 50 are amplified by the radio frequency amplifier 5
  • the master oscillator 38 in this case produces a frequency of 69120 cycles per second.
  • This frequency is supplied to the multivibrator 39 which having a ratio of 5 reduces the frequency to 13824 cycles persecond It is also supplied to the chain of multivibrators 40, ll, 42 and 43 which, having ratios respectively of 3, 6, 8 and 8, reduce the master oscillator Hence such a receiver may be used to receive-a ing apparatus.
  • the output of the converter is supplied to the video intermediate frequency amplifler' 54 and, assuming'that sound is being transmitted as well as pictures, is also supplied to the sound intermediate frequency amplifier 55.
  • This amplifier connects through the detector 56 and the audio frequency amplifier 57 with the loud speaker 58 in the usual manner.
  • the output of the video intermediate frequency amplifier 54 is supplied through the detector 59 and the video amplifier 60 to the cathode of the cathode ray receiving tube 8
  • the horizontal beam deflecting winding 64 of the tube is supplied from the horizontal sweep frequency generator 63 which produces 13824 cycles per second or approximately ard 441 line pictures having double interlace inasmuch as the horizontal or line frequency, namely 13824, of my transmitter is so close to the horizontal line frequency, 13230, of those receivers that their horizontal sweep frequency generators are readily pulled in step at the end of each line.
  • I may,' if desired, employ frequencieshaving a ratio whichincludes a fraction whose denominator is astill higher number.
  • the method of scanning lines in a cathode ray tube which comprises moving the electron beam of the tube in one direction at a certain frequency and moving it simultaneously in a direction substantially at right angles thereto at a frequency having a ratio to said certain frequency equal to an integer plus Television apparatus
  • a cathode ray tube having a screen, -beam'deflecting means and energizing means connected therewith for causing the beam to scan the-screen successively in a plurality of spaced parallel lines, said means including means for causing the beam to scan the screen intermediate said lines in a plurality of interlaced lines.
  • Television apparatus comprising a cathode ray tube having a screen arranged to be scanned by thebeam thereof in a plurality of lines and means for causing the beam to move in the. direction of said lines and in a direction substantially at right angles thereto, said means including means for causing the ratio of the frequency of movement of the beam in the direction of the lines to the frequency of its movement in the other direction to equal an integer plus a fraction ratio is an integer plus a fraction which is close spirit andscope of my invention which modifications 1 am to cover by the appendedv claims.
  • Television apparatus comprising a cathode ray tube having a screen arranged to be scanned by the beam thereof in a plurality of lines and means for causing the beam to move in the direction of said lines and in a direction substantially at right angles thereto, said means including means for causing the ratio of the frequency of movementof the beam in the direction of.
  • the method of scanning lines I in a cathode ray. tube which comprises moving the electron beam of the tube in one direction at a certain frequencyand simultaneously moving it in a direction substantially at right angles thereto at a frequency having a ratio to said certain frequency equal to an integer plus a fraction which in its lowest terms has a numerator that is more than one and is less than the denominator minus, one.
  • ray tube having a screen arranged to be scanned by the beam thereof in a plurality of lines and means for 'causing the beam to move in the direction of said lines and in a direction substantially at right angles thereto, said means including means for causingwthe ratio of the frequency ofmovement of the beam in the direction of the lines to the frequency of its movement in the other direction to d er from an integer by 10.
  • Television apps tus comprising a cathade 9.
  • Television apparatus comprising a cathode ray tube having a screen arranged to be scanned by the beam thereof in a plurality of lines and means for causing the beam to move in the direction of said lines and in a direction substantially at right angles thereto, said means including means for causing the ratio of the frequency of movement of the ray in the direction of the lines to the frequency of its movement in the other direction to equal an integer plus ll.
  • Television apparatus comprising a cathode ray tube having a screen arranged to be scanned by the beam thereof in a plurality of lines and means for causing the my to move in the direction of said lines and in a direction substantially at right angles thereto, said means including means for causing the ratio of the frequency of V movement of the ray in the direction of the lines to the frequency of its movement in the other direction to equal an integer plus "25.
  • Television apparatus comprising a cathode ray tube having a screen arranged to be scanned for producing a plurality of deflection frequencies whose ratio diiiers from an integer by and means for supplying said frequencies each to one of said deflecting means.
  • Television apparatus comprising a cathode ray tube having a screen, and'means for causing the beam of said tube to scan said screen in a of groups of flve lines each, said means including by the beam thereof in a plurality of lines, means for deflecting the beam in the direction of the lines, means for deflecting the beam in a direction substantially at right angles thereto, means means for causing the beam to scan successively corresponding lines of said groups and including means for causing the ray to scan successively lines 1, 3, 5, 2 and 4 of said groups in the order named.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US259194A 1939-03-01 1939-03-01 Television scanning Expired - Lifetime US2274366A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE438172D BE438172A (enrdf_load_stackoverflow) 1939-03-01
US259194A US2274366A (en) 1939-03-01 1939-03-01 Television scanning
FR863581D FR863581A (fr) 1939-03-01 1940-02-28 Perfectionnements aux systèmes de télévision

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US259194A US2274366A (en) 1939-03-01 1939-03-01 Television scanning

Publications (1)

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US2274366A true US2274366A (en) 1942-02-24

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US259194A Expired - Lifetime US2274366A (en) 1939-03-01 1939-03-01 Television scanning

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US (1) US2274366A (enrdf_load_stackoverflow)
BE (1) BE438172A (enrdf_load_stackoverflow)
FR (1) FR863581A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2554806A (en) * 1944-09-29 1951-05-29 Rca Corp Pulse rate monitor
US2591816A (en) * 1948-08-31 1952-04-08 Pye Ltd Television test signal generator
US2603706A (en) * 1947-05-12 1952-07-15 Color Television Inc Scanning system for color television
US3535446A (en) * 1968-04-10 1970-10-20 Nasa Method and means for an improved electron beam scanning system
US3617629A (en) * 1968-01-17 1971-11-02 Nat Res Dev Pattern detection apparatus
US3811011A (en) * 1969-07-08 1974-05-14 Itek Corp Multiple image registration system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2554806A (en) * 1944-09-29 1951-05-29 Rca Corp Pulse rate monitor
US2603706A (en) * 1947-05-12 1952-07-15 Color Television Inc Scanning system for color television
US2591816A (en) * 1948-08-31 1952-04-08 Pye Ltd Television test signal generator
US3617629A (en) * 1968-01-17 1971-11-02 Nat Res Dev Pattern detection apparatus
US3535446A (en) * 1968-04-10 1970-10-20 Nasa Method and means for an improved electron beam scanning system
US3811011A (en) * 1969-07-08 1974-05-14 Itek Corp Multiple image registration system

Also Published As

Publication number Publication date
FR863581A (fr) 1941-04-04
BE438172A (enrdf_load_stackoverflow)

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