US2355135A - Synchronizing apparatus for cathode-ray oscillographs - Google Patents

Synchronizing apparatus for cathode-ray oscillographs Download PDF

Info

Publication number
US2355135A
US2355135A US109507A US10950736A US2355135A US 2355135 A US2355135 A US 2355135A US 109507 A US109507 A US 109507A US 10950736 A US10950736 A US 10950736A US 2355135 A US2355135 A US 2355135A
Authority
US
United States
Prior art keywords
cathode
synchronizing
current
modulated
parts
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
US109507A
Other languages
English (en)
Inventor
Barthelemy Rene
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 US2355135A publication Critical patent/US2355135A/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
    • H04N5/08—Separation of synchronising signals from picture signals

Definitions

  • the object of the present invention is to provide an improvement of the above-mentioned systems, which improvement is characterized by the use of the synchronizing impulses.
  • 1n eiect in order the more readily to dierentiate, in the modulated current, the synchronizingimpulses from the variationsof current due to the analysis of the image, it has been proved to apply the synchronizing impulses to the current modulated by the image in such a manner that the variations of current due to the synchronizing impulses are of the same sense as the variations of current due to the dark parts of the image.
  • this method enables the synchronizing apparatus at the receiver to be controlled bythe whole of the modulated voltage received without the necessity of separating out the synchronizing signals by means of alters or other appropriate apparatus.
  • Figures 1, 2, and 3of the accompanying drawing represent the curves of the lmodulated current as afunqtion of time.
  • Figure 4 is Va circuit diagram of a synchronizing apparatus at the receiver.
  • Fig. 1 shows the normal curve of the current modulated by the analysis of the image.
  • parts l, 2 and 3 correspond to the bright parts v of a iine and the parts I', 2' correspond to the bright parts of the following line.
  • the parts 4, 5; S correspond to the dark parts.
  • the mean current in is such that, for an interval equal to the analysis of an imagefthe total surfaces of the curve corresponding to the bright parts in equal to the surfaces of the curve corresponding to the dark parts.
  • the maximum amplitude of the dark parts, compared with the mean current in, is small compared with the maximum amplitude of the bright parts. It is on the appreciation of this fact that the present invention is based. It is known practice to insert the synchronizing impulses in the current modulated by the image in such a manner that the impulses produce current variations of the same sense as the bright regions of the image. It may thus happen that the maximum amplitude of the bright regions is close to the amplitude of the synchronizing signals. Filters are then necessary, at the receiver, to separate the signals out of the whole of the modulated current received.
  • the amplitude of the synchronizing signals is of the same sense as the dark parts of the analysis, as is shown in Fig. 2, in which l represents va synchronizing signal transmitted between two' successive lines. It will thus be seen that .this signal is clearly distinguished from the obscure' parts t, 5, 6. It is then possible to operate the synchronizing apparatus at the receiver directly by the received modulated current without the interposition of a lter. It is, in effect, suicient to polarize this apparatus in'such a manner that the obscure parts do not cause the same to function whilst the synchronizing sig-A nals bring it into action.
  • the synchronizing signals correspond to a reduction of theintensity of the modulated current which may even annul it.
  • the synchronizing device at the receiver consists of gas discharge tubes, considerable diiiioulties are encountered in obtaining the precise triggering of these tubes by means of 1 the annulment of themodulated current. Therefore, the present invention provides also that'the modulation. as the manmade-r, shan be Sliema;
  • the principal advantages of this process aref chronizing impulsesithe easy separation of the synchronizing signals from the remainder of the modulation; the provision of a very precise trggering of the gas discharge tube at the receiver; protections against interference due tojthe fact that if the intensity of the synchronizing signals is twice that of the mean intensity the energy corresponding to the same four times that of the mean energy.
  • FIG 4 shows a. circuit diagram of a convenient synchronizing device more particularly for the reception of the modulated current of the form shown in Figure 3.
  • This device comprises essentially two gas ldischarge tubes Th1 and Th2 controlling, respectively, the line" movement and the image movement of a cathode beam.
  • the received'modulated voltage is applied to the terminals Ei and En and is transmitted to the terminals of a resistance Re through the intermediary of a resistance R1 and a condenser Ci.
  • One of the terminals of the resistance Rz is connected to the earth line of the receiver and the other terminal is connected to they cathode K1 of the tube Th1.
  • Rz forms a potentiometer permitting the application, between the grid Gx and the cathode K1, of the whole or a part of the modulated voltage received.
  • This application is made in such a sense that the synchronising signals, which correspond to an increase of the modulated potential received, bring about a reduction of the potential of the cathode K1 in order to render the tube Th1 conductive.
  • the potential oi l the cathode will be reduced more than the potential ot the grid or, in other words, the vpotential of the cathode with respect tothe grid will 'be reduced and the tube, will vbecome' conductive.
  • the contact on the resistance B2 'feeding the grid G1 enables the point oltriggering of the tube Thi to be adjusted.
  • the line oscillating vcircuit comprises the condenser Cz and the charging resistance Ra.
  • An electrostatic coupling provided by the condenser C: which is very small compared to the condenser C2 is feeding the cathode K2 of the image gas discharge tube Tha associated with which is the condenser C4 and resistance R4 forming the image oscillating circuit.
  • the capacities C5 and Cs coupling of the oscillating circuits, the feeding of the cathode without separation of the modulated signals being one of the characteristic features of the present invention.
  • a synchronizing circuit for a television system comprising a gas discharge tube, a cathode, a grid and an anode in said tube, a direct current surce having positive and negative terminals.
  • a condenser connected across said cathode and anode, a first resistor connected between the positive terminal and said anode, a second resistor having a first terminal connected to said, negative terminal and a second terminal connected to said cathode, a tap on said second resistor connected to said grid, a deector circuit connected across said condenser, and a source of synchronizing impulses having a positive terminal connected to said first terminal of the second resistor and a negative terminal connected to said second terminal of the second resistor.
  • a synchronizing circuit for a television system comprising a pair of gas discharge tubes each having a cathode, a gridand an anode, a -direct current source ⁇ having a negative terminal, means fed from said source for causing a gradual increase of voltage of each of said anodes with respect to its cathode, line deiiector circuit con.- nected across the anode and cathode of one of said tubes, a frame deilector circuit connected across the anode and cathode-of the other o f said tubes, a ilrst resistor having a first terminal connected to said.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Picture Signal Circuits (AREA)
US109507A 1935-11-14 1936-11-06 Synchronizing apparatus for cathode-ray oscillographs Expired - Lifetime US2355135A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR809071T 1935-11-14

Publications (1)

Publication Number Publication Date
US2355135A true US2355135A (en) 1944-08-08

Family

ID=9253338

Family Applications (1)

Application Number Title Priority Date Filing Date
US109507A Expired - Lifetime US2355135A (en) 1935-11-14 1936-11-06 Synchronizing apparatus for cathode-ray oscillographs

Country Status (3)

Country Link
US (1) US2355135A (enrdf_load_html_response)
BE (1) BE417524A (enrdf_load_html_response)
FR (1) FR809071A (enrdf_load_html_response)

Also Published As

Publication number Publication date
FR809071A (fr) 1937-02-23
BE417524A (enrdf_load_html_response)

Similar Documents

Publication Publication Date Title
US2286450A (en) Television receiving system
US2252613A (en) Signal transmission system
US2227815A (en) Synchronization system for television
US2490561A (en) Television picture mixing circuit
GB363605A (en) Improvements in or relating to sending and receiving synchronised systems for television, telecinematography, telemechanical devices and other applications
US2176663A (en) Television and the like system
US2300942A (en) Television carrier-signal receiver control system
US2240281A (en) Automatic background control
US2295023A (en) Television system
US2353018A (en) Television apparatus
US2231792A (en) Synchronizing system and method
US2227050A (en) Television transmitting or receiving system
US2402091A (en) Television system
US2355135A (en) Synchronizing apparatus for cathode-ray oscillographs
US2229964A (en) Television synchronizing system
US2750498A (en) Synchronization of television deflection systems
GB459602A (en) Method of and arrangement for producing synchronising impulses for television transmitters
US2298863A (en) Image transmission system
US2363800A (en) Television system
US2468256A (en) Television receiver including a horizontal oscillator responsive to a predetermined fraction of transmitted synchronizing pulses
US2240533A (en) Automatic control of television receiving systems
US2321343A (en) Television system
US2256529A (en) Synchronizing signal separator circuit
US2236066A (en) Television apparatus
US2776338A (en) Variable level noise-clipping circuit