US2086833A - Television - Google Patents

Television Download PDF

Info

Publication number
US2086833A
US2086833A US572138A US57213831A US2086833A US 2086833 A US2086833 A US 2086833A US 572138 A US572138 A US 572138A US 57213831 A US57213831 A US 57213831A US 2086833 A US2086833 A US 2086833A
Authority
US
United States
Prior art keywords
picture
frequency
frequencies
control
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
US572138A
Other languages
English (en)
Inventor
Walton George William
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.)
Individual
Original Assignee
Individual
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
Application filed by Individual filed Critical Individual
Application granted granted Critical
Publication of US2086833A publication Critical patent/US2086833A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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

  • This invention relates to methods of synchronizing the scanning devices used in television and the like, and has for its object the provision of one or more control frequencies transmitted with the picture currents in such a manner that the picture received is not affected thereby and that the actual picture .transmission and reception may also be simplified.
  • one or more sinusoidal control frequencies are transmitted with the picture currents, or as a modulation of the picture currents, which control frequencies are used at the receiver to maintain correct synchronism, phase and the like, the arrangement being, however, such that the actualpicture is thereby in no way disturbed even if the control frequencies are not electrically balanced out.
  • This is accomplished by choosing such a control frequency that its effect in a received picture is balanced out in succeeding pictures by reason of the phase changes of the control frequency which appear in these succeeding pictures.
  • the control frequency itself need not change phase,.the change being only apparent, as it is caused through the relation of the picture frequency to the control frequency.
  • the trans-- mission band is made narrow, thus allowing the transmission of a picture having greater detail
  • Optical stops or apertures may in some cases be used for producing a sinusoidal modulation of the picture currents, this being accomplished by the change of angle or position of a pencil of light passing through, or by the stop or aperture. This method is very'useful where oscillatory scanning is used and affords also a simple means of balancing out any uneven brilliancy in the picture caused by the oscillatory scanning.
  • the filters above mentioned may be very conveniently produced by photographic means, which besides being very precise, are cheap and can be produced in quantity by printing.
  • Figs. 1-6 are diagrams illustrating the prin-' ciple of the invention.
  • Fig. 7 is a circuit diagram showing one arrangement for separating picture signals from synchronizing signals
  • Figs. 8, 9, 9a, 10, 10a, 11, 11m, 12, 12a, 13, 13a, and 14 to 19 illustrate diagrammatically various ways in which the invention may be performed
  • Figs. 20 to 22 show diagrammatically various optical systems for use with the present inven tion
  • Figs. 23 to 25 show various forms of optical stop' which may be used in the arrangements such as are shown in Figs. 20 to 22,
  • Fig. 26 is a circuit diagram showing a further arrangement for separating picture signals and synchronizing impulses
  • Figs. 27 and 28 show two forms of filter for use with the invention, and Figs. 27a. and 28a show the distribution of shading on the filters of Figs. 27 and 28 respectively,
  • Figs. 29, 30, and 31 are wave-form diagrams showing the operation of the invention.
  • Fig.32 is a circuit diagram showing a further arrangement for separating electrical impulses, suitable for use with a cathode ray tube,
  • Figs. 33*and 34 are further diagrams illustrating a way of performing the invention.
  • Fig. 35 shows a filter disc
  • Figs. 36 to 43 show the electrode system 0 Kerr cells suitable for use with the invention
  • Figs. 44, 45, and 4c illustrate diagrammatiure 2 shows the control frequency superimposedon a D. C. component. If 1 and 2 are superposed the result is as shown in Figure 3. If now in the next complete picture the phase of the current in Figure 2 is reversed, the detail of the picture shown in Figure 1 combined with the control frequency will be as shown in Figure 4. It will be seen that the curves according to Figures 3 and 4 will also correspond tothe light intensity at the receiver, 1. e. looking at a corresponding part of the reproduced pictures, the brightness indicated by Figure 3 will be seen in the one complete picture and that indicated by Figure 4 in a succeeding picture.
  • control frequency As the phase of the control frequency is reversed in the succeeding picture, and as in television succeeding pictures are shown in rapid succession so that the human eye is unable to follow the change of picture, the control frequency cannot be seen, only an average illumination being apparent. However, as the detail indicated in Figure 1 does not change phase from Figure 2 to Figure 4 it remains positive and therefore it appears in the picture. If the control frequency according to Figure 2 modulates the picture current it varies the amplitude of the detail indicated in Figure 1, reproducing lt in one picture as shown in Figure 5 and in the next one as shown in' Figure 6. No control frequency is apparent in the reproduced picture as only the mean value of the impulses,
  • the picture currents may be.
  • a transformer l delivers the control frequency at the terminals Sf and the picture frequencies appear at the terminals 6. This arrangement does not provide complete separation, for this is not required specifically, but at the terminals 5 the percentage of low frequency is greatest, and at 6 least. Many arrangements are possible and are well known .in usual electrical practice, and there is no need actually to have any separation. This will be understood from Figures 3 and 4.
  • the hump due tothe picture detail in the control frequency shown in Figure 3 will tend todisplace the phase of, synchronization towards the hu p, bill in AXB C wherein A is the number of complete pictures per second, and B and C any whole numbers, such that B is not a multiple of C. C gives the number of complete pictures over which the effect of the control frequency is zero. visable that C be as small as possible, viz. 2, in order that there be as little flicker as possible in the reproduced picture. a
  • control frequency affords a means of securing completely automatic phasing or framing of the picture, being particularly convenient in os- .-cil1atory scanning.
  • a frequency may also be used for synchronization, provided it is truly sinusoidal rnd the synchronizing device responds correctly to the variatidn, for it is, less susceptible to disturbing influences such as picture detail I and line frequencies, and will maintain synchronism for a longer period than is possible with higher frequencies.
  • Figures 8 and 9 show the appearance of a control frequency of /2 of the picture frequency in alternate complete pictures.
  • Figure 8' shows the appearance of a received picture, say during the positive half cycle ,of the control frequency
  • Figure 9 shows the same during the negative half cycle,.i. e. the appear ance of two successive complete pictures.
  • the shading of the pictures varies sinusoidally from top to bottom, a half cycle being shown at the side.
  • the picture of Figure 8 may be considered as superimposed on the picture of Figure 9, so that the shadings are added, with the result that the picture shown in Figure 10 is obtained.
  • Figure 10a it is shown how the addition of the positive and negative values produces a constant mean value. This cancellation takes place independently of the phase relation of the control frequency to the pictures, and is unaffected by, nor does it affect the picture details, which appear just as though the control frequency was not present.
  • Figures 11 to 13 illustrate the case when the control frequency is i
  • the picture has four strips so that the frequency is comparable with the strip frequency.
  • Figure 11 shows one picture and Figure 12 the next one.
  • Figures 14 to 1'7 show forms of filters according to this invention which permit the control frequencies to be produced and be balanced in the 1 picture received.
  • control frequency must be a multiple of the picture frequency unless the filter is movable.
  • the frequency is four 20 times the picture frequency, the picture being scanned in four horizontal strips. If the picture had any other number of strips the control frequency per second would be that number multiplied by the number of pictures per second.
  • Figure 14 is shown a filter having a sinusodial variation of shade from left to right, but no variation from top to bottom; the scanning of the strips is effected horizontally.
  • the filter is suitably placed, preferably in the focal 30 plane of the image at the transmitter, the picture currents are modulated by a control frequency produced by the filter.
  • -A filter as shown in Figure 15, which is a negative of Figure 14, is
  • FIGS 16 and 17 show the transmitter and receiver filter for the same frequency as in Figures 14 and 15, but the phase is displaced through 90.
  • the filters as shown should preferably be of double width so as to cover two cycles instead of one and thus enable the receiver filter to be ad- 45 shown in Figure 18.
  • Such a filter may be the same, irrespective of the number of strips in the picture.
  • the frequency will always be the picture frequency multiplied by the number of strips.
  • the filter may also be used with the variation at right angles to the strips to produce a control frequency equal to the picture frequency, which frame the picture. In this case, the control device shouldbe polarized so that there will be only one position in which the picture will frame.
  • two such filters may be used at right angles, either separate or combined in one filter, one variation being parallel to the direction of scanning and the other one at right angles thereto, whereby two control frequencies are produced, one for automatic framing and the other or synchronizing.
  • the filter has one cycle 'per (35 picture width, but it is possible to arrange that when a picture of a definte number of strips is to be transmitted any number of complete cycles in the whole picture is obtained. In the latter case the filter should only be used with pictures hav- 7 ing the number of strips for which the filter is made.
  • Such a filter is shownin Figure 19, having four strips and cycles per complete picture,
  • Such a filter is i may be used automatically to adjust the phase or the scanning being again assumed to be unithat there, must be a whole number, or a whole number and a half, of complete cycles per swing, and if the scann ng during a swing is not at constant speed, then the filter must be so made that the frequency produced is constant.
  • the end of a swing should be always at a maximum or minimum shade value, otherwise there is a phase reversal of the control frequency produced with alternate swings in scanning.
  • - may be effected by applying the same frequencies to control the intensity of light falling on.
  • a photographic surface placed preferably in a position where the image is formed or seen with the apparatus when receiving or transmitting actual pictures. The photographic surface is exposed for a sufficient length of time to attain the required density. When this photograph is formed it may be used as a master print, from which any number of copies can be taken by contact printing, or any other process.
  • Stops and apertures may be used to produce control frequencies, and to remove them from a received picture wherever a beam of light has a traversing or angular movement.
  • An arrangement is shown in Figure 20 illustrating the arrangement at a television transmitter using a Nipkow disc.
  • the Nipkow disc I has formed on it the image to be transmitted.
  • a section of the image throws light through the scanning aperture 5 forming a divergent pencil of light, which the condenser lens 9 focusses on to a photo cell Ill, in such a way that as 5 is moved to the position II, there is no movement of the spot of light at the focus of 9.
  • An aperture I2, the size of which depends on the amount of variation required, is suitably placed between 9 and Iii. As shown, only half of the light from the aperture at 5 passes through I2, and as 5 moves towards II, the amount of light passing through I2 in ⁇ ,
  • stop I8 is of such a size andsopositioned that the light is maximum at the points I6 and I1, and minimum midway -between-- them at .the,
  • the aperture 20 has a suitable form dependent on the type of scanning.
  • Figure 24 illustrates an arrangement similar to that shown in Figure 23, exceptthat a stop 24 is used instead of an aperture, the frequencies produced having a phase displacement of 180 relatively to those produced according to Figure 23.
  • the arrangement may therefore be used in a receiver when an arrangement as shown in Figure 23 is used in the transmitter, or vice versa, in order to eliminate the control frequencies from the received picture.
  • Figure 25 shows an arrangement of a stop 25 and apertures 26, 21, 28, 29, 30, 3
  • the cross section of the pencil of light should be approximately the same as that of the apertures. Obviously such arrangements are possible which enable other control frequencies to be obtained, exactly as is possible with filters.
  • FIG. 26 A typical arrangement is shown in Figure 26. wherein the'whole of the received currents are applied to the terminals 32. The actual picture detail freqencies are takenfrom terminals 34,
  • the inductances 35 and 36 offer a high impedance to the picture detail currents, and a low impedance to the control frequencies, so that the latter pass through the primary of the trans former 31.
  • the secondary of the transformer 31 supplies only very weak picture detail currents, but the control frequencies are strong.
  • the higher control frequency is taken to the deflecting plates 38 of the cathode ray tube through a condenser 39 which offers little impedance to them, but high impedance to the low control frequency.
  • the inductance 40 offers a high impedance to the higher control frequency and a low impedance to the low control frequency, so that the latter passes through the primary of the transformer 4 I.
  • the secondary of the transformer 4' I supplies a strong low control frequency, a weak high control frequency, and very weak picture detail frequencies.
  • the two latter frequencies are further reduced in strength by a by pass condenser 42, offering a high impedance tothe low control frequency, which is applied strongly to the deflection plates 38' of the cathode ray tube.
  • a by pass condenser 44 may be connected across the secondary of the transformer 31, which condenser offers a low impedance to picture detail frequencies but a high impedance to the other frequencies.
  • An inductance 43 is connected in the circuit of the deflecting plates 38 to prevent picture detail frequencies from being applied at high strength to the said plates. This arrangement may be modified in many respects and use may be made of numerous other similar arrangements well known in practice.
  • the picture currents are modulated as shown in Figure 29, and such a form of current variation in the receiver when applied to the deflecting plates will cause the spot of cathode rays to move slowly at a constant speed from one side to the other, and then at the end of the movement to jump quickly back again, the process being then repeated.
  • Figure 27 will give only one scanning, but two quency of Figure 31.
  • One part of these changes filters as shown in' Figure 2'larranged at right angles to one another will give the double scanning.
  • the two filters may be combined in one, such as is shown in Figure 28, wherein the shade value decreases continuously at a constant rate from 44 to 48 diagonally.
  • Figure .28 shows the same filter as Figure 27,- but the shading has been rotated so that maximum variation of shade is along the diagonal.
  • the filter according to Figure 28 to be scanned rapidly from 44 to 45, and the secondary scanning to be from 44 to 4
  • the resulting modulation of I the picture current will be as shown in Figure 30, if there are four scannings from 44 to 45 during the scanning from 44 to 47.
  • the points 49, 50 and Bi show the end of one complete scanning and the beginning of the next, and the points 49, 52, 53, 54 and 50 the beginnings of horizontal scannings and the ends of those preceding them.
  • the grid of the valve 62 is in parallel with the valve but is fed through an inductance or resistance 63 which offers a high impedance to picture detail changes, a condenser 64 assisting in by-passing the picture detail changes, so that the latter are considerably reduced at the grid of the valve 62.
  • the valve taoperates in a similar way, except that the inductance or resistance 6E5 has a high impedance, and the condenser M a low impedance to picture detail changes and to the higher frequency changes shown in Figure 31,; consequently the low frequency changes are greatest at the grid of the-valve 55.
  • the resistances 68 and 69 allow a current to flow through I53 and respectively so that the latter resistances are operative.
  • the low frequency change in Figure 31 is greatest in the anode resistance Iii of valve 65.
  • the tapping on 10 allows part of the voltage to be passed through the resistance ii and be applied to the grids of the valves 66 and B2.
  • the phase of the currents so applied to the valves 60 and 62 is opposite to the phase they receive from the terminals 58 and consequently with correct adjustments the low frequency changes of Figure 31 will balance out from the currents applied to the valves 60 and 62. Therefore the changes of current through the anode resistance 12 ofthe valve 62 correspond to the high'freflows through the resistance 18 to the grids of the valves and BI, and because of the opposite phase it balances out that frequency from the anode currents of those valves. As the-low and.
  • valves in parallel with interlocked negative reaction as It is also useful as a means of eliminating control frequencies from the received picture.
  • the separation though not absolutely complete, may be made very good with only a small percentage of the undesired frequencies appearing, if adjustments are correctly made.
  • Many modifications are possible, but the characteristic of all of them is the negative reaction of circuits on other circuits in order to eliminate the frequencies of those circuits from the one on which they react; one circuit reacts on all other circuits or on those which require complete elimination of the frequency of that circuit.
  • An alternative method which produces the same result' consists in making the apertures of varying area, preferably by varying the size in' the direction of scanning, so that the light passed by the respective apertures shall be the same as would be obtained in Figure35.
  • the receiver would of course be modified in the opposite sense, i. e. the hole in the receiver disc having the maximum area would correspond to the one with minimum areain the transmitter, and the holes in the two discs would have the same relative position in the spiral.
  • the filters may be separate from the scanning member and may move at a speed different from that of the latter so that the control frequency produced is dependent on the scanning and the speed of the filter.
  • the scanning is unidirectional it is advisable to move the filter in the same way, and with oscillatory scanning the filter should also oscillate,',otherwise irregular frequencies may be produced.
  • the filters need not move in-the scanning directions, but may be arranged to move at an angle thereto, so that one filter can produce two control frequencies at the same time by adiust-. ing the angle of movement in correct relation to the two scanning directions.
  • the points of even shade value in the filter may be at an angle to the direction of scanning, i. e. the filter may be made such as shown in Figure 15 and be slightly displaced angularly when it will produce the effect of the filter shown in Figure 11. This applies equally tostationary as well as to moving filters.
  • Apertures and stops which as has been explained above are the equivalents of filters, may also be moved in a similar way.
  • the control frequencies at the transmitter may be produced by ordinary electrical methods, for instance by separate generators and the like, the scanning being suitably synchronized therewith, or the generators coupled to the scanning arrangement.
  • a generator may be provided on the shaft of a Nipkow disc.
  • the modulation of the photoelectric current may also be effected by known electrical .means, such as thermionic valves.
  • Another way, of eliminating unwanted frequencies in a received picture consists in the modulation of light, for instance by such devices, as Kerr cells, the modulation being such as to balance out the unwanted frequencies.
  • additional poiarizers and analyzers need not be used; for instance more than one Kerr cell or when using the Faraday rotation of polarized light more than one coil may be used in tandem or side by side between the crossed Nichol prisms, one giving the normal light modulation required for the picture, and the other or others a modulation at the unwanted frequencies, but with a light variation which balances out the unwanted frequencies from the picture.
  • the cell may be provided with additional electrodes for this purpose. There may be one or a pair of added electrodes for each unwanted frequency, although this is not necessary, since all such frequencies may be applied to one, or one pair of added electrodes.
  • Figures 36 to 43 show a number of different arrangements of such Kerr cells,only the electrodes being shown.
  • the unwanted frequencies may be applied to the electrodes 88 and 81 and the picture impulses to the electrode 88 as one pole and to the electrodes 88 and 81 as the other pole, a resistance, inductance, or two condensers in series being connected across 88 and 81, and the impulses supplied to 88 being applied to a middle point of the'shunt across 86 and 81.
  • the two kinds of currents may of course be applied in the opposite way to the electrodes.
  • and 88 have shunts across them as mentioned in connection with Figure 38.
  • the one kindof impulses are applied to the midpoints of theshunts 88 and 88, and 8
  • the arrangement according to Figure 30 maybe used also'without shunts, one kind of impulses 'being applied to 88 and 82 and the other to 88 and 8
  • an additional electrode may be provided, to which the unwanted frequencies are applied,
  • control frequencies are sinusoidal, but this is not essential.
  • the requirements are that the control frequencies should be continuous and regular as regards periodicity, wave form, phase and amplitude,
  • Aperture and stop compensation is of course equivalent to filter compensation
  • frequencies equal to control frequencies cannot occur in ordinary practice, for if they could, movement of details in a scene must be such as to produce a change of phase of the corresponding picture impulse in the succeeding picture, which means such a rapid movement in the scene that it could not be seen by the eye, or such a structure of the scene combined with a precise movement, as does not occur in an ordinary scene, except very rarely.
  • the same remarks apply to methods where compensation occurs automatically in succeeding strips of the picture. 4
  • sinusoidal control frequencies are most satisfactory, more particularly with unidirectional. scanning, for departures from sinus form obviously produce a number of sinusoidal frequencies, which are more likely to disturb the received picture. Filter compensation is preferable where the wave form is not sinusoidal.
  • the effect of the frequency applied to the picture currents in the received picture is equal to the variation due to the oscillatory scanning in the receiver, and shown by the full line, then the picture appears to be evenly illuminated, since the applied frequency is cancelled out of the picture. by the scanning in the receiver. Nevertheless that frequency may be used in the receiver in order to synchronize and adjust the phase of the oscillatory scanning.
  • a control frequency of the form shown may very easily be produced in the transmitter, by using a filter of the form shown in Figure 1.5. Further, the filter may be such that the control frequency is perfectly cancelled out of the received picture, since it can be produced photographicallyby the oscillatory scanning.
  • the period 95-93 represents a swing of the scanning device in one direction and the period tit-Edits swing in the opposite direction; therefore the position oftfi in the picture is the same as that of 9d, and a stationary detail in the picture which is scanned equally in two successive swings will produce the hump 96 in the dotted curve in one swing, and a corresponding hump 911 in the next swing.
  • the received currents may be applied direct to the synchronizing device, if the latter consists of a non-polarized'magnetic, electrostatic, or electrodynamic device of the dynamometer type; otherwise rectification is necessary.
  • the frequencies are passed through a circuit having two branches, the one containing an inductance and the other one a condenser, as shown in Figure 4'1. This arrangement produces an amplitude modulation of the frequencies of opposite phases in the two branches.
  • I00 are the output terminals and I0! are rectifiers. If no rectifiers are used, the primary of the transformer I02 is replaced by the coils or the like of the synchronizing apparatus.
  • the invention may be used with, equal advantage in picture telegraphy and be readily applied to the various systems. When a cylinder is employed on which the picture is attached or received, and use is made of filters, the latter may also be of cylindrical form, or made" flexible so that they can be bent to therequired curvature.
  • the filters be in contact with the picture, for which purpose use is preferably made of atransparent cylinder such as glass, with the filter permanently provided thereon, the picture in' the transmitter, and thephotographic surface in the. receiver being placed inside or outside the cylinder according to the general construction of the apparatus, so that it is in contact with the filter.
  • the filter will remain in the correct position with respect to the phase adjustment and the synchronizing devices;
  • the methods preferred for picture telegraphy are those in'which the compensation is effected by means of multiple electrode Kerr cells, or in which it takes place automatically in two strips of the picture, using the double size aperture or spot of light.
  • Two control frequencies may be used, one corresponding to the number of revolutions of the cylinder, or to half. thereof, and the other one which is higher and is used to control the speed of the driving motor.
  • a method of television, picture -telegraphy and the like consisting in adding uninterrupted control frequenciesto the picture currents, transmitting them simultaneously and at the same time as the said .picture currents, using the said control frequencies in the receiver for synchronization, phase adjustment or framing and producing in the receiver a counter effect equal to that of the control frequencies and thereby canceiling the said control frequencies from the received picture as seen by the human eye.
  • control frequencies are added to the picture currents in the form of an amplitude modulation of the latter.
  • control frequencies are added to the picture currents in the form of a frequency modulation of a carrier frequency.
  • Amethod of television, picture telegraphy consisting in adding an uninterrupted control frequency to the picture currents, transmitting it at the same time as the said picture currents,
  • control frequency in the receiver for synchronization and the said control frequency being a fractional multiple of the frequency of the picture scanning so that there is a change of phase of the effects of the control frequency relative to the picture in a succession of picture scannings, which produces in the receiver an opposition control frequency effects in a group of successive picture scannings so that the effect of the control frequency, due to the persistence of vision, is zero in that group as seen bythe human eye.
  • a method of television, picture telegraphy consisting in adding an uninterrupted control frequency to the picture currents, transmitting it at the the same time as the said picture currents, using the said control frequency in the receiver for synchronization phase adjustment the said control frequency being a fractional multiple of the strip frequency of scanning the picture so that there is a phase displacement of control frequency effects relative to the picture in the direction of scanning in a succession of strip scannings which are caused to, oppose in a group of successive strip scannings 'by scanning at the receiver with afractional overlap of strips, so'that the eifect of thecontrol frequency, due to persistence of vision, is zero in that group as seen by the human eye;
  • An apparatus for television and picture telegraphy comprising in combination with a transmitter for the simultaneous transmission of picture currents and control frequencies, a receiver having shaded optical means interposed in the path of light forming the picture in the receiver for the purpose of cancelling out from the picture as seen the eflects of the control frequencies.
  • ST A method consisting in using electrical ,means for suppressing some of the control frequencies from the picture screens in the receiver byselective electrical circuits and the application of opposing frequencies equal to the frequencies to-be suppressed.
  • a scanning device andalight control device which together produce the picture, the said light device having in'addition to the normal electrodes and control members to which the received picture currents are applied, other control members to which the control frequencies obtained by partial filtering from the received picturecurrents are applied to produce a variation of light opposite and substantially equal to the variation caused by thecon'trol frequencies added to the picture currentsapplied to thenormal electrodes and control members of the light control device for the purposeof cancelling the effect of the control frequencies in the picture.
  • Television and picture telegraphy receiving apparatus adapted for the reception of combined picture and control electrical oscillations and in which a counter balancing effect is produced for the purpose of removing the unwanted effects of the control oscillations comprising s,ose,sss creased intensity and said picture oscillation is i of reduced intensity compared with said combined oscillations, an electro-optical control device having a plurality of pairs of controlling members, means for applying potential difleren'ces corresponding to said combined oscillations across one of said pairs of controlling members and means for applying potential differences corresponding to said corrective oscillation across another of saidpairs of controlling members.
  • Television and picture telegraphy receiving apparatus adapted for the reception of combined picture and control electrical oscillations comprising means for producing from said combined electrical oscillations, a corrective electrical oscillation in which said control oscillation is of increased intensity and said picture oscilla-l tion is of reduced intensity compared with said combined oscillation, means for producing light varying in intensity in accordance with said combined oscillation and light varying in intensity in accordance with said corrective oscillation and means for combining the two light variations in such a manner that variations due to said control oscillation substantially cancel one another.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Scanning Arrangements (AREA)
US572138A 1930-11-13 1931-10-30 Television Expired - Lifetime US2086833A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE641519T 1930-11-13

Publications (1)

Publication Number Publication Date
US2086833A true US2086833A (en) 1937-07-13

Family

ID=34812939

Family Applications (1)

Application Number Title Priority Date Filing Date
US572138A Expired - Lifetime US2086833A (en) 1930-11-13 1931-10-30 Television

Country Status (3)

Country Link
US (1) US2086833A (en(2012))
DE (1) DE641519C (en(2012))
NL (1) NL40187C (en(2012))

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2435736A (en) * 1941-02-13 1948-02-10 Zenith Radio Corp Frequency modulated picture receiver
US2508451A (en) * 1947-05-02 1950-05-23 Robert H Dicke Sound recording and reproducing apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1136732B (de) * 1959-07-23 1962-09-20 Siemens Ag Verfahren zur zentralen Synchronisation von Fernsehnetzen

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2435736A (en) * 1941-02-13 1948-02-10 Zenith Radio Corp Frequency modulated picture receiver
US2508451A (en) * 1947-05-02 1950-05-23 Robert H Dicke Sound recording and reproducing apparatus

Also Published As

Publication number Publication date
DE641519C (de) 1937-02-03
NL40187C (en(2012))

Similar Documents

Publication Publication Date Title
US2389646A (en) Television system
US2461515A (en) Color television system
US2389979A (en) Color television system
US2413075A (en) Method and system for developing television signals
US2271876A (en) Television shading control circuit
US2037577A (en) Television method and apparatus
US2385563A (en) Deflection control system
US2086833A (en) Television
US4988927A (en) Deflection circuit for a television picture tube
US2630485A (en) Color television apparatus
US2865984A (en) Edge correcting system for visual image transference apparatus
US1955332A (en) View transmission system
US3716657A (en) Apparatus for increasing signal to noise ratio in television low light level scenes
US2255408A (en) Facsimile system
US2929870A (en) Video signal compensating circuitry
US2752418A (en) Color television indexing system
US2301374A (en) Facsimile and picture system without synchronizing units
US3553356A (en) Method and system for generating color television signals without loss of vertical resolution
US2174490A (en) Telephoto system
US2485594A (en) Waveform compensating circuit for television film transmitters
US3029387A (en) Electro-mechanical device
US1955320A (en) Television synchronization method
US1863278A (en) System and apparatus for the electrical production of images
US1874200A (en) Electrooptical image producing system
US2182326A (en) Television receiving apparatus