US2098384A - Protective system - Google Patents

Protective system Download PDF

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Publication number
US2098384A
US2098384A US726442A US72644234A US2098384A US 2098384 A US2098384 A US 2098384A US 726442 A US726442 A US 726442A US 72644234 A US72644234 A US 72644234A US 2098384 A US2098384 A US 2098384A
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United States
Prior art keywords
ray
potential
tube
cathode
anode
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Expired - Lifetime
Application number
US726442A
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English (en)
Inventor
Robert R Goodrich
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RCA Corp
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RCA Corp
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Publication date
Application filed by RCA Corp filed Critical RCA Corp
Priority to US726442A priority Critical patent/US2098384A/en
Priority to FR789987D priority patent/FR789987A/fr
Priority to BE409520D priority patent/BE409520A/xx
Application granted granted Critical
Publication of US2098384A publication Critical patent/US2098384A/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
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/20—Prevention of damage to cathode-ray tubes in the event of failure of scanning

Definitions

  • My invention relates to protective systems and more particularly to systems for protecting cathode-ray tubes against destructive beam-current.
  • cathode-ray tubes When cathode-ray tubes are utilized in television receivers or for the purpose of alternating current analysis and the like, it is customary to provide ray-deecting devices which cause the ray, or beam to periodically traverse the fluorescent screen in a pre-determined pattern. If, by reason of failure of the ray-deflecting devices, etc., the ray comes to rest upon the uorescent screen and remains stationary for even a very short time the screen is burned and the tube is rendered substantially useless for satisfactory picture reception.
  • an object of my present invention to provide means whereby .failure of the ray-deflection generators associated withv a cathode-ray tube does not occasion the ow of destructive b current.
  • Another object of my invention is to provide a protective system lfor a cathode-ray tube that shallv function to prevent destructive beam-current in the event of breakage of certain essential circuit connections.
  • a still further and more specific object of my invention is to provide a protective system for a cathode-ray tube that shall function to prevent destructive beam-current in the event that certain essential connections in the protective system, itself, are broken.
  • I provide a relay for connecting the second anode to ground and for simultaneously de-energizing the source which supplies it with potential and I make use of a unidirectional current derived from the ray-deecting devices for. determining the operation of the relay.
  • Figure 1 is a view of a portion of a television receiving system in which an embodiment of my invention is included, and
  • Fig. 2 is a view of a portion of a television receiver including an alternative embodiment of my invention.
  • a cathode-ray tube I of the general type to which my invention pertains is constituted by an evaculated envelope having a bulbous portion 3 and a cylindrical portion 5.
  • the bulbous portion may be provided with a. metallic coating 'l to serve as a second anode and the large end is provided with an interior fluorescent screen 9 usually made from Willemite or the like.
  • An electron gun constituted by an equipotential cathode Il, a grid i3 and a first anode i4, is disposed in the cylindrical portion of the tube.
  • Suitable grid-cathode biasing potential and anode potential is provided from a common source, exemplified in the drawings by a bleeder resistor I5 connected across the output terminals of a rectiiier Il, over a plurality of conductive connections I9, 2
  • ray-deflection may be accomplished by utilizing electromagnetic deiection coils alone, electrostatic defiecting plates alone or by a combination of coils and plates.
  • the generators maybe of the continuous oscillation type, merely synchronized by incoming synchronizing impulses, or they may be of the intermittent type which only functions to provide output impulses when triggered-oil' by the 55 apparent hereinafter, is applicable to either type. If. during the operation of the system thus far described, for translating incoming picture-l signals into a visml reproductionof the transmitted view, the deiiecting generators should fail simultaneously the fluorescent screen in the tube would immediately be ruined. Even though but one of the generatorsV should fail. or the connections between it and the deiiecting coils should break, thesereenmightbe spoiledsincetheray. traversing the screen in a single direction under an accelerating potential of the order of 10,000 volts, causes much higher localised heating than normal.
  • I provide means, responsive to de-energisation of one or both of thedeiiecting coils. for depriving the ray of accelerating potential.
  • the circuit for supplying the primary windlng 8l of a power transformer 31 feeding the rectiner includes an armature Il and a fixed :ontact Il of a'relay Il. It will also be noted :hat the relay is provided with a second grounded armature Il which is connected to the cathode if the cathode-ray tube and is normally held sway from a nxed contact 41 from which a coniection 49 extends to the rst anode il in the :athode-ray tube.
  • the armatures are interconaected by an insulator Il for simultaneous movenent.
  • the relay when the relay is energized' the Lrmature is drawn up and held to complete the :nergizing circuit for the primary winding of the :ower transformer. When it drops out. the energizing circuit is broken and the iirst anode is zonnected directly to the cathode and to ground, ilus depriving it of potential.
  • a source I1 preferably of unidirectional iotential such as a battery or rectifier but an ilternating current source may be used.
  • the athode of the control tube is connected to an ntermediate point on the bleeder resistor and i fixed or static negative bias suiiicient to stop he ilow of output current is provided by conlecting the grid to the negative end of the reistor.
  • I rovide further means for deriving positive poentials from the deflection impulses and for utilzing them to nullify the xed negative potential lerived from the bleeder resistor.
  • theseveral diodes are so connected to the resisten that the rectified current iiowing sets up potentials in opposition to the negative potential impressed upon the grid of the control tube from the potential supply resistor Il. 'ihrough proper choice of the constants of the system the static negative potential may be overcome and the grid of the control tube given the proper positive potential to permit just enough space current to ow in the relay winding to pull up and hold the armatures.
  • the control-tube cathodeheater fail, the same action, obviously, takes it 'expedient to connect a reasonably large capacitor II in shunt with each o!
  • each capacitor for example, may have a capacity of .015 mfd., and each resistor may be .2 megohm.
  • a reactor-condenser nlter may be interposed between the output resistors l. and .i and the input terminals of the controltube for the same purpose although such a illter is not usually necessary.
  • Such a filter is exemplified in the drawings by a sexies connected resistor 8i and a plurality of shunt condensers Il.
  • an inductor may be substituted for the filter-resistor if desired.
  • grids are coupled to the ray-denection plates through stopping condensers ll and il, respectively, and the device is provided with an output, or self-bias resistor IM around which a reasonably large capacitor
  • the self-bias resistor is included in the input circuit of the control tube, the connections being such that the potential across it bucks" the static negative potential on the grid.
  • the average plate current from a thermionic device which obtains its bias from a self-bias resistor is substantially constant although it does increase slightly in response to the presence of grid excitation.
  • the space current in the excited condition may be made to override the static negative potential on the grid of the control-tube and the system functions in substantially the same manner as the system exemplified by Fig. 1.
  • a cathode ray tube having a uorescent screen, means within the tube for developing a cathode ray and directing it toward the screen, means for deilecting the rayacross the screen according to a predetermined recurrent pattern, a ray-accelerating anode within the tube, connections for supplying a potential to the anode and means for depriving the anode of potential and connecting it to ground upon failure of the ray-deflecting means.
  • a cathode ray tube having a fluorescent screen
  • means within the tube for developing a cathode ray and directing it toward the screen
  • a cathode ray tube having a fluorescent screen
  • means within the tube for developing a cathode ray and directing it toward the screen
  • connections for supplying anode potential to said tube, switching means included in said connections and means responsive to the energization of said ray-deileeting means for determining the operation of said switching means.
  • a cathode ray tube having a fluorescent screen
  • means within the tube for developing a cathode ray and directing it toward the screen, an accelerating anode interposed between the said means and the screen, means including a source of fluctuating potential for causing the ray to traverse the screen according to a pre-determined pattern, a unidirectional potential source, a thermionic tube having an output circuit including the winding of a relay, a movable armature and a fixed contact associated with the relay winding, connections whereby the armature and the contact connect the unidirectional potential source to the accelerating anode upon energization of the relay winding, means for normally biasing the thermionic tube negatively to substantially the cut-on potential, means for deriving a unidirectional potential from the source of fluctuating potential, and connections for utilizing the derived unidirectional potential to nulllfy the said normal negative bias whereby, when the ray is being deected across the screen the anode is supplied with potential and
  • unipotential deriving means includes a thermionic tube and additionally characterized inthat connections are provided whereby cathode heating potential may be applied to.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US726442A 1934-05-19 1934-05-19 Protective system Expired - Lifetime US2098384A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US726442A US2098384A (en) 1934-05-19 1934-05-19 Protective system
FR789987D FR789987A (fr) 1934-05-19 1935-05-14 Système protecteur pour tubes à rayon cathodique
BE409520D BE409520A (enrdf_load_html_response) 1934-05-19 1935-05-18

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US726442A US2098384A (en) 1934-05-19 1934-05-19 Protective system

Publications (1)

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US2098384A true US2098384A (en) 1937-11-09

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US726442A Expired - Lifetime US2098384A (en) 1934-05-19 1934-05-19 Protective system

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US (1) US2098384A (enrdf_load_html_response)
BE (1) BE409520A (enrdf_load_html_response)
FR (1) FR789987A (enrdf_load_html_response)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444902A (en) * 1946-02-27 1948-07-06 Rca Corp Protective circuit
US2455992A (en) * 1947-01-25 1948-12-14 Du Mont Allen B Lab Inc Cathode-ray tube amusement device
US2492674A (en) * 1945-12-20 1949-12-27 Sylvania Electric Prod Cathode-ray tube circuits
US2577848A (en) * 1950-02-16 1951-12-11 Rca Corp Protective circuit
US2584932A (en) * 1949-07-16 1952-02-05 Rca Corp Television kinescope projection circuit
US2607018A (en) * 1949-11-29 1952-08-12 Rca Corp Means and method for protecting kinescope screens
US2625265A (en) * 1947-04-01 1953-01-13 Electric Sorting Machine Compa Photoelectric sorting apparatus
US2635208A (en) * 1948-04-21 1953-04-14 John M Cage Television circuit
US2709768A (en) * 1952-06-05 1955-05-31 Gen Precision Lab Inc Cathode ray tube protection circuits
US2808536A (en) * 1954-11-18 1957-10-01 Rca Corp Cathode ray tube protecting and energizing circuits
US2810858A (en) * 1954-06-14 1957-10-22 Itt Protective circuit
US3090889A (en) * 1960-05-03 1963-05-21 Bell Telephone Labor Inc Electron beam intensity control circuit
US3164745A (en) * 1961-05-02 1965-01-05 Shulman Abraham Sweep collapse and rotation failure alarm system for ppi display device
US3402316A (en) * 1966-09-29 1968-09-17 Sylvania Electric Prod Flux switch protective system for electrical apparatus
US3555348A (en) * 1969-01-13 1971-01-12 Ibm Cathode ray tube screen protection system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE942827C (de) * 1952-03-16 1956-05-09 Hans Werner Paehr Dr Rer Nat Anordnung zum Schutz des Leuchtschirmes von Braunschen Roehren in elektrischen Empfangs- und Anzeigegeraeten, insbesondere Fernsehgeraeten
DE1032424B (de) * 1952-07-12 1958-06-19 Philips Patentverwaltung Schaltungsanordnung zum Schutz des Schirmes einer Elektronenstrahlroehre gegen UEberlastung

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2492674A (en) * 1945-12-20 1949-12-27 Sylvania Electric Prod Cathode-ray tube circuits
US2444902A (en) * 1946-02-27 1948-07-06 Rca Corp Protective circuit
US2455992A (en) * 1947-01-25 1948-12-14 Du Mont Allen B Lab Inc Cathode-ray tube amusement device
US2625265A (en) * 1947-04-01 1953-01-13 Electric Sorting Machine Compa Photoelectric sorting apparatus
US2635208A (en) * 1948-04-21 1953-04-14 John M Cage Television circuit
US2584932A (en) * 1949-07-16 1952-02-05 Rca Corp Television kinescope projection circuit
US2607018A (en) * 1949-11-29 1952-08-12 Rca Corp Means and method for protecting kinescope screens
US2577848A (en) * 1950-02-16 1951-12-11 Rca Corp Protective circuit
US2709768A (en) * 1952-06-05 1955-05-31 Gen Precision Lab Inc Cathode ray tube protection circuits
US2810858A (en) * 1954-06-14 1957-10-22 Itt Protective circuit
US2808536A (en) * 1954-11-18 1957-10-01 Rca Corp Cathode ray tube protecting and energizing circuits
US3090889A (en) * 1960-05-03 1963-05-21 Bell Telephone Labor Inc Electron beam intensity control circuit
US3164745A (en) * 1961-05-02 1965-01-05 Shulman Abraham Sweep collapse and rotation failure alarm system for ppi display device
US3402316A (en) * 1966-09-29 1968-09-17 Sylvania Electric Prod Flux switch protective system for electrical apparatus
US3555348A (en) * 1969-01-13 1971-01-12 Ibm Cathode ray tube screen protection system

Also Published As

Publication number Publication date
FR789987A (fr) 1935-11-09
BE409520A (enrdf_load_html_response) 1935-06-29

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