US1991082A - Television apparatus - Google Patents

Television apparatus Download PDF

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Publication number
US1991082A
US1991082A US333374A US33337429A US1991082A US 1991082 A US1991082 A US 1991082A US 333374 A US333374 A US 333374A US 33337429 A US33337429 A US 33337429A US 1991082 A US1991082 A US 1991082A
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US
United States
Prior art keywords
frequency
fork
current
heater
scanning
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
US333374A
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English (en)
Inventor
Conrad Frank
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.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric 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 BE367034D priority Critical patent/BE367034A/xx
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US333374A priority patent/US1991082A/en
Priority to US433483A priority patent/US1872896A/en
Application granted granted Critical
Publication of US1991082A publication Critical patent/US1991082A/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
    • H04N5/067—Arrangements or circuits at the transmitter end
    • H04N5/073—Arrangements or circuits at the transmitter end for mutually locking plural sources of synchronising signals, e.g. studios or relay stations

Definitions

  • lMy ⁇ invention relatesto television and more Y particularly to a radio transmission system fork causing ⁇ distant images to appear upon a screen.
  • the object of my invention is to'provide im.- ⁇
  • a still further object of my invention Iis to provide an improved scanning-disc structure.
  • r f A still further object of my invention is to pro-4 vide an improved system for simultaneously transmitting images from ajplurality of widely spaced transmitters.
  • a frequency ⁇ near the upper limit of ⁇ the audio frequency range utilized in broadcasting musical programs preferably a frequency ⁇ near the upper limit of ⁇ the audio frequency range utilized in broadcasting musical programs.
  • the frequency of the is multiplied and the current transmitted from the transmitting stations as a carrier wave.
  • the v alternating current is maintained at aconstant frequency by means of a system including an electric clock and a synchronous motor which, periodically, applies heat to a tuning fork, as will be more fully described hereinafter.
  • a softiron ring having teeth ⁇ on its outer edge, is ⁇ attached to the'scanning discso that the scanning disc itself constitutes a part of vthe rotor of the synchronous motor.
  • Figure l is a diagrammatic view of the apparatus and electrical connections employed in ⁇ a system constructed in accordance with my in- ⁇ vention;"
  • Fig. 2 is an end elevational view "of a scarl-ffA ning disc and a synchronouslmotor constructed; inaccordance with my invention
  • e is a diagram to aid in describingftnei* operation of the constant-frequency,generator
  • Fig, ⁇ 'l is a diagrammatic viewy of ,theheatingr box and heating apparatus Aforthe oonstant-fre ⁇ quency-generatorjtuning fork;
  • the system comprises two; widelyspaced transmitting stations-station1 ⁇ A ⁇ 25" and station B-With .their ,correspondingfreceivf, ing stations-stationl andstaton B. ⁇ l.
  • a carrier wave of frequency ,fz is supplied from ⁇ a source ⁇ 1 of alternating current having a suby i stantially constantfrequency, ⁇ prefer bly above 36' the range commonlyI utilized when' transmitting i musical programs, and a frequency multiplier
  • the frequency ⁇ employed in the example being de'- f scribed is 5000 ⁇ cycles l"per second.'
  • the frequency of the. Sooo-Cycle current is multiplied tothefre; 35" jf quency fzby anysuitable frequency multiplier andfthe current ⁇ then supplied to an amplifiereV modulator 3.
  • any suitablecoul rent of frequency fp is obtained by ⁇ means 'o'fapfv 1 paratus including aj scanning disc Gand 'aphotojf' i electric cell17.
  • the scanning'dsc 6 ⁇ is'ofa Well 50 known type having holes located inja ⁇ spiral,
  • n beam of light from a light source; 8' is" passedl through these holes uponthe imagejgtow ⁇ be transmitted' and isreflected'to the photoelec-r 55 the tuning ⁇ V261 the modulated carriervvavef1, f1i5000.
  • the scanning disc 6 is rotated at a high speed by means of a synchronous motor 10 of the phonic-Wheel 5 type connected to the 500G-cycle source 1 by means of a metallic line 11 and amplifiers 12 and A carrier current f1 is modulated by the 5000- cycle current land radiated from an antenna as
  • the apparatus for transmitting the'modulated carrier wave f1, f1i5000 comprises an amplifiermodulator 14 to which is connected anV oscillatorgenerator 15, supplying a current of frequency f1, and the 500G-cycle generator 1.'
  • the amplifier-modulator 14 i's connected -to an antenna 15 by any suitable coupling means 17.
  • the receiving station A' comprises a scanning disc 18, similar to that at the transmitting stav tion, and a source of light 19, the intensity of which is varied in accordance With the modulated carrier wave j2.'1hemodulated carrier Wave f2 r isvpicked up Vby thereceiving antenna 20, demodu-V lated by a detector 21 ⁇ , and theresulting picture current fp 4ampliiied'by a vacuum-tube amplifier 22"andA impressed'upon a mercury-arc lamp 23 through. a step-down transformer24 and a condenser 25.' The mercury-arc vlamp 23 is connected to adirect-current supply through an in- 30.l Yd'u'ctance 26, aresistance, 27 andra connection 28.
  • the scanning. disc y18V is driven by a synchron'iu'sV motorl 29, ⁇ similar to motor l0, connected to aV circuit' dwhich ⁇ receives and VVcle'zn'odulates the modulated carrier Wave f1.
  • the carrier ⁇ Wave fris picked up by the antenna 31, demodulated by adetector 332, and the iresulting 500G-cycle current passed ythrough an amplifier 33 ⁇ and' 'a50 ⁇ 00-cycle iilter 34 to the synchronous motor, 29..
  • thescan- 4a.,ningdisc 18, at the-receiving station is run in synchronism withf the scanning disc 6 at the transmitting station, and a reproduction of the imageappearson a. screen 35.
  • the scanning ⁇ discs 6'and18 will remain in synchro- 4lnis'mso. that the, image Will'be reproduced even "though the frequency of the constant-frequencygenerator'output varies slightly.
  • IA svtepedown-transfo'rmer ratioof 20 to 1 has 75, ⁇ been .-foundfsatisfactcry, .f although, obviously, the
  • the ratio may vary within wide limits and should be determined by the characteristics of the particular lamp being employed.
  • the Values of capacity, inductance, resistance and direct-current-voltage supply employed in the circuit, like- Wise, are not critical. The following values have been found satisfactory: condenser 25, 300 microfarads; inductance 26, 3 henries; resistance 27, ohms; and D, C. voltage supply, 110 volts.
  • the transmitting station ⁇ B is employed for broadcasting the image 9 located at the station A o-ver a section of the country remote from the Y, section covered by station A.
  • Station B transmits on a carrier Wave having the same frequency as that transmitted from station A.
  • This carrier wave is obtained by receiving the modulated carrier Wave f1 on an antenna 36, demodulating it bya detector 37, and multiplying the frequency of the resulting 500G-cycle current by a frequency multiplier 38.
  • the resulting carrier Wave f2 is impressed upon an ampliier-modulatorBB, modulated by the picture current fp vwhich is supplied to the amplifier-modulator 39 fromvthe station A over a metallic line 40, andtransmitted from an antenna 41.
  • the receiving' station B' whichreceives the4 image 9 transmitted from station B, identical With receiving station A', except for the fact that the receiving circuit is tuned to the carrier-'Wave frequency vf3 instead of tothefre-V quency f1.
  • Fig; 4 which shows thestructure ⁇ employed at transmitting station A, the scanning vingfconnected to the scanning disc 6 by a belt 51 and by means of asynchronous motor 10.
  • the motorv may be of any type the speed of ⁇ which caribe adjusted to drive the scanning disc 6'at ⁇ approximately the correct speed.
  • the object in employing the motor 50 ⁇ is to reducethe power which mustbe furnished by the synchronous motor 10.
  • the synchronous motor 10 has a rotor which comprises a laminated iron ring 52 having teeth on its periphery and so bolted ort riveted to the scanning disc 6 thatthefdisc forms part ⁇ teeth ⁇ 63 projecting from its periphery.
  • a vibration dampener 55 for reducing the effect of hunting ofthe synchronous motor 10 is employed.
  • the dampener comprises a balance wheel ,which the scanning disc 6 comprises a disc ofi i i ;v i i metalor any other suitable material having 60
  • Square holes 61 are punched in the i screws 62. thin plates 60 in order to give the maximum amountof light with maximum detail. After the thin plates 60 have been mounted on the disc 6,- thesquare holes 61 are lined up exactly by optical..
  • stator may comprise a longer or:
  • a shorter laminated arc 64 than the one illustrat- ⁇ ed Vor if desired, it may .comprise two or more laminated arcs.
  • the modification illustrated is; ⁇ one of the preferred forms, since the structure necessary for supportingthe stator is simple and ⁇ compact. i Y
  • a synchronous motor constructed in the manlo'ne'r above-specified l provides an economical and efcient means for driving a plurality of scanningvdisos in synchronism.
  • vthe legend heater and fork is shown schematically in Fig. '7. It comprises a heat-insulated bo'x 67 within which' are locatedtwo electric heaters 68 and 69.
  • the upper heater 68 is con- -- ⁇ Vnected to a source of current through a thermostatic relay 70 of the bimetallic type.
  • a condenser '71 is shunted across the relay contacts to reduce'sparking.
  • the 'interior of the heater box L 1 is maintained at substantially a constant tem- "fperature by means of the heater 68 and thermostatic relay 70.
  • the heater 69 which may be an ordinary flat-iron heater, is provided iior applying heat directly to the tuning fork holder 72, the famount of heat which is applied being con- ⁇ tro1led by means of the circuit shown in Fig. 5.
  • the elements 73 and 74 connected to the conductors '75 and '70, respectively, are electro-magnet-icdevices for driving the tuning fork.
  • Tleconstruction of the tuning-fork holder 72, 40"'iftuning fork, and electro-magnetic driving means '73 ⁇ and '74 can best be understood by referring to Figs. 8 and 9.
  • the holder 72 comprises two solid metallic blocks 77 4and 78, preferably of l brass, each havinga vertical hole '79 drilled off ""center, therein.
  • Each block has a larger threaded hole, drilled at right-angles to the vertical ho1e'79 and communicating with it, in which one oftheelectromagn-etic driving units '7B and 74 is t supported.
  • the two blocks 77 and 78 are clamped 'li'together lby means of bolts 80, with their thin walls adjacent to each other and with a sheet of ymagnetic material 81 therebetween.
  • two well portions '79 are formed, separated by a thin partition of magnetic material 81 and ""1'1on-magnetic material 82.
  • a square notch 83 is cut in themiddle of the upper edge of this partition.
  • the tuning fork 84 is clamped, by means of' bolts 85, between two solid metal blocks 86 Eand 87, ⁇ preierably of brass.
  • Blocks 86 and 87 are i1 ⁇ secured by tous se to me mocks 77 and 'is in such position that a portion of the tuning fork 84is ⁇ loca ⁇ ted within thevnotch 83 cut in the partition, while the prongs 99 are located within the tvs-:ills 79.
  • a clip 100 is attached at the top ⁇ of the block for holding a thermometer 101.
  • the tuning-fork-driving elements 73 and .'74 comprise telephone-receiver units having poles adjacent to the prongs 99 of the tuning fork 84.
  • poles'are soft-iron pieces attached to the poles of a permanent magnet 102. They have coils 103 mounted thereon which are connected to' the binding posts 104. The driving elements w ⁇ are held-in place by means of set screws 105. 75141 The ⁇ partition above-specified is provided for vlay contact.
  • the temperature of the fork 84 may be controlled by varying the amount of heat applied to these blocks. This is done by setting the fork holder '72 upon an electric heater 69, as shown in Fig. 7, and by controlling the' amount f driving element '73 is connected to the output of .K
  • the fork 84 is driven at its natural frequency bythe energy supplied from the amplifier 106, and a current of this frequency can be obtained from the ampliner output.
  • the frequency of the current' generated is controlied by varying the amount of .heatisuppledl through the heater circuit 107-v tothe forkA heater 69.
  • the amount of heat supplied tothe fork 84 is controlled by meansof a synchronous motor. .i
  • the synchronous motor 108 connects the fork-heater circuit 107to a ⁇ source of.
  • heater 69' is alternately connected to, Vand disconnected rom, the source of current, which, in the example illustrated, isa 110 voltfalternating-current supply.
  • the circuit connecting the current supply to the fork heater 69f mayV be traced from one terminal of the 1101volt source,
  • the wind-V ing of relay 114 which pulls up the armature 113 and thereby connects the fork heater 69 to the alternating-current supply, has one terminal connected to :ground and the other terminal connected, through a resistance 121 and a'conductor 122, to one terminal of a battery 123, the other terminal of the battery 123 beingconnected.
  • a polar relay 124 having an armature '125 connected to ground, is Vprovided for connecting theright-hand terminal of the winding of 'relay' 114 to ground through' the conductor 126 and re- It is evident that, when the armato the 110 volt supply.
  • the armature 125 of the polar relay 124 rests against the righthand contact, lthe winding of the relay 114 is short circuited and the armature 113 drops down, thus disconnecting the fork heater 69 ⁇ from the 110 volt supply.
  • the armature 125Lof .thepolar relay .1241150 ⁇ a driving coil.
  • the shaft 131 is connected to the synchronous motor 108 through a gear reduction unit so that contact between element "5130 and brush 129 is made once every two sec- 'onds if the tuning fork -proper frequency.
  • the polar relay armature 125 is pulled against 84 is vibrating at the the right-hand contact, to disconnect the vfork heater 69 from the 110-volt supply, each time the 108 and the electric clock 110 are so adjusted with respect to each other that they alternately connect and disconnect the fork heater 69 and the current supply.
  • the electric clock 110 is, preferably, of the type described and claimed in my copending application, Serial No. 176,061, filed March 17, 1927, in which the pendulum is driven by charging and discharging a condenser through Y
  • the coil of the polar relay 135 is connected in series with this driving coil.
  • a special circuit is provided for passing current through the polar relay vwindings 127 and 142 in response to the closing of either the synchronous motor or the electric-clock contacts.
  • the circuit comprises the battery 123 which is connected, through a conductor 144, a resistance 145 of a few hundred ohms and a second resistance 146 of several megohms, to one terminal of a condenser 147.
  • the other terminal of the condenser 147 is connected to the other terminal of the battery 123 through ground.
  • a circuit is likewise completed from one terminal of the bat-1 sistance 146, a'condenser 149 similar to condenser 147, and through ground, to the other terminal of the battery 123.
  • the armature of therelay may be pulledaway from a relay contact even though the contacts of the synchronous motor 108 ⁇ or electric clock' ⁇ 1105i 5 e whichrpull the armature 125 against thel relay contact are still closed.
  • ⁇ and voltage have been foundsatisfactory although, obviously, other values may be employed if, ⁇ desired: ⁇ resistances 146 ⁇ and ⁇ 1,4'8 ⁇ eqi'1a1 5 fme'gohms; resistance 145 equals 1000 ohms; resistance 112 equals'50 ohms; resistance k116 equals 800 ohms; resistance 118 equals 20 ohms: condensers 147 and 149 equal .25 micro-farads; resistance 121 equals 10,000 ohms; ⁇ and voltage ⁇ of battery 123 equals 350 volts.
  • Theoperation of the-circuit will be more fully understood byrreferrin'gtolthe diagramof Fig. 6 which greatlyv exaggeratesV the rapidity-[with which changesin the' fork 'frequency ioc'cur.' In
  • the generator is supplying a current ofthe proper frequency, that is, 5,000 cycles per second.
  • the fork heater 69 is alternately connected to, and ldisconnected from, the current supply at one-second intervals.
  • the fork frequency begins to increase after the ten-second interval. After the twelve-second interval, the fork 84 begins to vibrate too rapidly, and the synchronous motor 108 speeds up. This results in heat being applied to the fork 84 an instant sooner than it would be if the fork were vibrating at the 500G-cycle frequency.
  • the temperature of the fork 84 is, iaccordingly, increased and its frequency is changed the desiredamount.
  • the fork 84 is vibrating so rapidly that the synchronous motor 108 connects the heater 69 to the current ⁇ supply ⁇ as soon as it is disconnected by the electric clockllo. It is evident that, if the fork 84 vibrates still more rapidly, the synchronous motor speed will be so high that its contact connects the fork heater 69 tothe current supply just before the contacts of relay 139 are closed by the electric clock 110 to disconnect the current supply fromthe heater. When this happens, less, instead of more, heat is applied to the fork 84 than is applied when it runs at the proper frequency, andthe system will not correct the fork frequency.
  • a manual adjustment must be made to increase the yfork Ldi,sconnects the fork heater 69 from ⁇ the curren l, .onnects the forkHheater-,GQ to thecurrent e ⁇ r,ery.10,000 ,cyc1es,- ,While-,the electric clock 110 1.1..,In television apparatus, a ⁇ scanning device ,co prising agdisc/and means comprising a plu- -.,-2. In televisionapparatuafafscanning device comprisinga yrotatabledisc and arotor element of a synchronous motor ⁇ disposed coaxially ,V'With @aid-disc andvsupportded thereby.
  • a scanning ldevice' comprising a rotatable element and a rotor ele- E 1nent, cfa .synchronous motor .directly supported 1f thereby.
  • n agarose comprising a disc; the Idisc ⁇ being :provided with a eldvvinding to provide motive power for said disc.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Scanning Arrangements (AREA)
US333374A 1929-01-18 1929-01-18 Television apparatus Expired - Lifetime US1991082A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE367034D BE367034A (enrdf_load_stackoverflow) 1929-01-18
US333374A US1991082A (en) 1929-01-18 1929-01-18 Television apparatus
US433483A US1872896A (en) 1929-01-18 1930-03-05 Constant-frequency generator

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US333374A US1991082A (en) 1929-01-18 1929-01-18 Television apparatus

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US1991082A true US1991082A (en) 1935-02-12

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BE (1) BE367034A (enrdf_load_stackoverflow)

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