US2200753A - Television system - Google Patents

Description

. TELEVISION SYSTEM Filed Feb. 21, 1936 Oltd'l't INVEINTO A; A. LINSELL avg ATTORN EY (30 U. S. Patent Patented May 14, I940 TELEVISION SYSTEM Alfred Aubyn Linsell, Sydenham,

Londony Eng-l, f

land, assignor to Radio Corporation of America, a corporation of Delaware Application February 21, 1936, Serial No; 65,005

In Great Britain March 4,

7 Claims. (01. ire-5.8)

This invention relates to television and telecinematograph receivers and more particularly to such receivers of the kind adapted to reproduce pictures from signals which are transmitted as modulations of a carrier wave. l

According to this invention, reception of sound or sound and television signal modulated carrier wave energy is effected at a television receiving installation by means of a receiver of the superregenerative type, and the said invention is characterized in that the quenching frequency necessary for super-regenerative action is obtained from television scanning means necessarily provided in connection with television picture reproduction.

The invention is illustrated in the accompanying drawing, in which Fig. 1 shows one form of my invention, 1 Fig. 2 shows a modification of the embodiment of the invention shown in Fig. 1, and

Fig. 3 shows a further modification of the embodiment of the invention shown in Fig. 1.

Figure 1 shows one way of carrying out this invention as applied to an installation for receiving television signals and accompanying sound signals and incorporating a television reproducer of the cathode ray tube type and a sound signal receiving super-regenerative receiver operating in accordance with the invention described in the No. 1,982,694, issued December 4,

1934 to W. V. BRoberts. Referring to Figure 1,

the super-regenerative receiver comprises two valves 1, 2, Whose gridsare connected together through a resistance 3 (hereinafter for the sake of convenience in terminology termed the grid resistance, the ends of the resistance 3 being connected to the grids of the valves I, 2 through suitablebias potential sources 4, 5, as shown.

A fixed centre tapping 5 upon the resistance 3 l0 is connected to the common cathode point? of the two valves througha parallel tuned input circuit 8, 9 the coil 8 in which is inductively coupled to a coil Him a receiving aerial circuit. The aerial is shown at I I. The anodes of the two valves are ,5 connected together through two anode coils l2,

IS, the junction point between whichis connected through a suitable output device (e. g. the primary of a transformer i 4 which feeds a loudspeaker I 5 in series with a source it of anode potential to 0 the common cathode point. "I. The two anode coils l2, F3, are coupled tothe coil 8 in such a way that the coupling of one anode coil to the said tuned circuit causes reaction in a regenerative sense while the coupling of the other anode coil 5 to the said tuned input circuit causes reaction in a degenerative sense." 'I'he grid cathode spaces of the valve 5, 2!, are shunted by suitable high frequency by-pass condensers I'l, l8.

The cathode ray tube reproducer IQ of the installation may be of any known kind and scan- ,applies an output to a put transformer I4 would connect to the control ray tube. For simplicity are not shown, since itis at once obvious that the purposes;

ning action in this reproducer is effected as known per se by applying suitable sawtooth wave potentials to the usual mutually perpendicular pairs '20, 2|, of electrostatic deflecting plates, or coils (plates are shown), these potentials being derived from sawtooth wave generators which are synchronized with incoming signals as known perse. For the sake of simplicity in the drawing, applicant has merely represented in block diagram form the line and frame sweep generators 22 and 43 respectively. The television receiver 4| is likewise shown only'in simple block diagram form with the synchronizing signals path indicated by the lines drawn from the receiver 4| to the line and frame sweep generators.

The saw-tooth wave generator 22 which operates at the scanning line frequency and which one pairof electrostatic defiecting plates or coils (as shownthe plates 20) of the tube is also connected across the resistance 3 so that the generator serves the dual purpose of providing the quenching frequency and 'de-' fleeting theray in the tube. The arrangement is such that the quenching will take place duringreturn or fly-back periods of the cathode ray, i. e. when the deflecting potential is at or near the maximum. Accordingly, the reproduced It is understood, of course, that a second receiver for the television signals, .identical with that shown for the sound channeLmay be coupled tothe coil Land the resistor 3, and Whose outelectrode and cathode of the cathode ray tube to control theflintensity of the cathode ray beam picture will not be adversely afiected by ,the quenching action, a r

impinging on the fluorescent screen of the cathode fusion, the individual elements of this receiver operation of the receivers are identical.

Figure 2 shows a modifications in which a harmonic of the line frequency is used for quenching Here the generator 22, instead of being connected directly across theresistance 3 is connected in series with the primary 23 of aloose coupling transformer 24 whose secondary Z5 is tuned bymeans of a suitable shunt condenser 26 to a desired harmonic of the scanning line frequency,the tuned circuit 25, 26, being connected across the grid resistance 3. Since the generator 22 provides a saw-tooth wave its output will be rich in harmonics.

If desired and as shown in Figure 2, the fixed centre tapping 6 upon the grid resistance 3 may be replaced by an adjustable tapping 6a and, in this case, by moving this adjustable tapping 5a the relative time durations of regeneration and quenching may be varied as desired. Again, if desired, an adjustable impedanceconstituted by and to prevent conan adjustable choke 2! a 28, 29, in the other.

able impedance (or impedances) the time of the,

frequency is caused to terposed; in series between one end-of thegtuned secondary 25 and the. adjacent resistance 3.

- In the modification shown in Figure 3, both these expedients' are adopted, a choke being in'one lead and a resistance-capacity combination By adjust ng, the: adiuste quenching relative to the instantaneous position of the scanning ray in the cathode raytubercproducer may be adjusted, i..e. maybe advanced or retarded. Further, if desired, the ends or thetuned secondary of the transformer may be connected to the ends of the grid resistancethrough a frequency multiplier circuit instead of: directly; in other words, theselected harmonic of the sawtooth waveoutput' from the saw tooth wave gen erator may be frequency multiplied and the resultant higher h equencywave used: the quenching ireq'uency; for super-regenerative action. a

It will be noted that the" present invention enables the normally provided separate quench ,ing frequency oscillator of a; super-regenerative receiver to be dispensed with, the function thereof being performed according to thesaid invention by apparatus which is provided in in a television receiving installation; or obtain-- ing television scanning action; Furthermore, in

carrying out the said invention the quenching bear a fixed: predetermined relationship to the scanning'frequency and this is" likely to result in improved: reproduction so far as background or grain of the reproducedpictures is concerned.- V. I

now patricul-arly described and. ascertaincd the nature of my said invention and? in What manner the: same is to, be performed, what 2 claim is: I 1'. The method; of improving; electro-optical reproductions-which comprises the steps of generating an electron ray, directing the electron ra y toward a viewing plane, receiving electrical energyrepresentative of an electroaoptical image to be reproduced; generating locally oscillatory Wave energy, detecting the received electrical en ergy under the control of the locally generated energy, controllingthe intensity of the electron ray in accordance with the detected energy,'and controlling the position of theelectron, ray upon the viewingplanein accordance with the locally generated energy; 1

2; The method of improving: sound reproductions accompanying electroeoptical reproduc tions, which includ'esthe steps or receiving; electrical energy representative of the sound to: be reproduced, receiving electrical energy represented:- tive of an electro optical image to be reproduced, generating locally: oscillatorywaveenergy; simultaneouslycontrolling the position of? the, electroopt'ical reproduction and detecting the received energies under the control of'the locally: generated' energy, andreproducing the sound. accom panying' the electro-optical reproductions in accordance with the detected energy.

or an adjustable conend of the grid any event a. viewing'plane, simultaneously receiving electrical energesreigresentativeoi thelight intensity of the elemental areas of? the picture to be reproduced and representative of the sound to be reproduced, generating locally oscillatory wave energy, separately detecting the received electrical encrgiesfunder the control of, the locally generated energy, controlling the intensity of the electron my in accordance with the detected energy representative of the light intensities to be reproduced, controlling the position of the electron ray: upon; the viewing plane in accordance with the locally generated energy, and controlling-i the generation of sound in accordance with the detected energy representative of the soundtcbe reproduced. l

it television system comprising albathode ray tube for reproducing pictures upon a fiuow rescerit screen contained within the tube, means for receiving electrical energy representative of the light intensity of the elemental areas of the picture to be reproduced; means for generating locally oscillatory wave energy, means for detecting the received electrical ener yuuder-the control or the loceiliy generated energy, means for controlling the intensity of the electron ray in, accordance with the detected energy, and

meanspositic-hing, the point ofv electron ray impingement, upon the fluorescent screen in; ac-v he received Electric, ;1 ener iesunder the: control .crthe locally-seneratedenerer; meanst con .01 the ensityof:theelec roniray-inaccordancewith detect-ed energy rerresenrativecf-i the light intensity to: reproduced, means to con .01 I no time of the electron: ray upon. the viewing plane in accord one, wit the localh enerated nergy, and me for energizing a sound cc crater accordance-with the detected energy representative of the sound to be r pr ced.-

' sound accompanying sy em for u e coono .1; Withtelcrision-comprising atel'e regenerative sound receiver, and n, a viewing wave energy.

o. i iverto eccQmllfigny'a television comprising in! receiving eleca l energy reprcs .e. or the sound: to be rep" "need, recej-vi s: electri al ener y rep-resell? tati c; of: an lect-romp im ge to be reproduced mean-.5 for gel a locally oscillatory W ve: nergy; means for simu tanc usly control line; the Position: of the electroptiical; reproduction and detection of; the received energies in accordance wi h he locally generated energy, and means for energizing the sound reproducer c :dance with'the detected energy represen- 1 tativeofthesoundfto be reproduced.

. ALFRED AUBYN, LINSELL.

th wave energy; and means, to receiver by the locally ene"

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