US2561702A - Method of skiatron cleanup - Google Patents

Description

July 24, 1951 H. c. KELLY METHOD OF' SKIATRON CLEAN-UP Filed Dec. 10, 1945 mo muDOw moo-.Eko mo momsom INVENTOR HARRY C.KELLY ATTORNEY reviously mentioned Patented July 24, 1951 UNITED STATES rATENr opweg" l i; t t i METHOD F cLEAtJP y.

Harry C. Kelly,

Belmont, Masts.,-

assvignor, by

mesne assignments, to =the-@United .States of i America, as represented by the Secretary of the Navy Application December 1o, 1945, serial Ne. 534,108

Claims.y

"k-This invention relates to skiatrons or dark is known as burn-in, and is often objectionable. When it is desired to apply a different pattern Other objects and advantages of this inven-y tion will be apparent from the following speci cation when are means genfor focusing the electron and means 20 for gating the cathode 2l of the skiatron. The s additional clean-up means for defocusing the electron `means 23 for reducing the velocity of the `electron beam, 24 for inelectron beam, means 25, 26 for removing cathode gating means 20, andoptionallyA usable means generally designated 21 intercleaneup means aise ineide means 22 beam of the.- skiatron,

for simultaneousl operation when sired. When these clean-up means are operated simultaneously the sweep sifled and defocused electron beam on the screen lcreasing the speed of clean-up.

Sweep means l2 comprises sweep coils 32, a source" of normal current 33, and rotating 34 mechanically connected to coil 32, as indicated by dotted line 35. Rotating means 34 turns coil'32, and in combination with source=33 coil 32 to either source 33 or, when desired, to source I3.

Focusing means l5 comprises focus coils 36 beam on the'screen Il. lower position resistor 22 1s connected in c mal operatingcondition switch 31 is in the upper position. I n 4Source ofanode voltage I 6 provides a gating to either source I 6 provides a reduced .Means I4 comprises ay D. C. voltage increases the screen Il.

Means I8 for biasing grid I9 comprises a source 39 of D. C. voltage connected by switch 49 to the grid. This D. C. voltage, durinvgnnorv" alroperat: ing conditions/keeps the tubI 'ghtl-Sfv abv? cut-E. L .v Means 24 for intensifying the electron beam of tube I0 comprises a source 24 of decreased voltage, which when applied to grid figintensiesf f the electron beam. For normal operation sw'tch 40 connects grid I9 to source 39'VH For cle' of the skiatron switch 4I)v conn i source 24.

Means for gating cathode 2l comprises a which when applied to anode I1 total number of electrons striking mal operation is connected by switch 2li/,to cathode 2 I. To remove the lcathode gating ineansfor" clean-up, switch 26 connects cathode 2| by lead 2 -to ground. if? 'ffl: Means 21 interconnects Yallo'f the additional cleanup means -ior A-sim'ultia`.r1eoi'1s ioperatibn. 'Ihs comprises mechanical'v-couplings, designated by dotted lines 42, 43, 44, k45, and`4'6, for fall-of the switches and coupling `3I` `for remcivingV h'a't absorber 29. "f 1 "The optical projection means28 i'sfaconventional Schmidt 'projection systernffcomprising' lamp 30, reflector,'heatabsorber 29 l'er'isesE 4'8, 49 fand 5I), mirror 54, spherical mirrorf I ,correct ing lens52 and viewing-screen 53. l Using this the-ski system `an venlarged' vrepresentation* of atron pattern is available at viewing 4screerril'.

" 4'When clean-up' is desired, switch`l4'connects source I3 of s'me'wave'current'tosweep coil '32', means 31 removes heat absorber1'29 Ifrom 'the optical' projectionsystem 28, switch 31 connects resistor 22 series'withfocus `coil connects source `23 of Adecreased-anode voltage toanodefll, switch`40 connects'source 24 of =de` creased bias `supply to grid I9; and switch-'226 grounds/cathode 2l. This results inanuintensie ed Yand'- defocused electron Abeam-striking screen II, and produces thereon aisweepfwhih travels completely across thel screeninsteadiff `starting from the center. This application-of :electron bombardment, along' with yheat from:v therlight source 30, removes the burned-'insignalsina=very short time. f L *Itis to be understood that while "thisspecifr cation has described vthe theory Eo'r' theinvention as used with a projection system, the inventioniis not necessarily limited thereto. i f apparentr to a person skilled in the art, this inventionf-is applicable to any apparatus `employing'a skiatron. v f' What is claimed is:

l. i The combination with a'skiatron type l:tube and-deection means for'providing a radialsweep rotating yabout an origin on .the-screen ,ofthe skiatron, 'of v additional meansl forl rapidly .cleaning-up -the skiatron screen, said meansk yincluding a second 'source of' sweep'energy which .f changes in polarity as well asaintensity; and fmeansoper' ative when desired, to connect saidsou-rce .tosaid deflection means, vvwherebythe sweepY extends diametrically on both-sides =of the origimfthereby increasing the speed of clean-up of saidskiatrcn.

2. The combinationnof clairnv1, inwhichcsad second source `of sweepenergy Ais-za sine-@wave SOlllCe. .:g':` i; f 'i 3. The combination v"with apparatusv including a skiatron type tube, a deflection means ioripro' viding'a radiali-sweep rotatingcabout anorigin on .hasta i said electron beam,

the screen, means for focusing the electron beam of said skiatron, a source of anode voltage for the rst anode of said skiatron, means for biasing the grid of said skiatron, and means for gating the cathode of said skiatron, o additional means for rapidly cleaning-up the screen of said skiftromisaid clean-up means including, a second 'source' of' sweep 'energy providingv a sine wave, means operative when desired to connect said second source of sweep energy to said deflection .,rneans, meansfor defocusing said electron beam, means for reducing the velocity of said electron beam. io'flws'aid skiatron, means for intensifying means for removing said means, and optionally usable means interconnecting all of the aforesaid cleanclean-upv is desired, whereby the sweep, formed byi'ianintensied and defocused electron beam on the screen, extends diametrically on both sides ffiztheffzorigin, 'thereby increasing the speed'of clean-up` of saidsfskiatron. i -f f4; LThe 4coinrbination with afskiatron projection system including a skiatron type tubeadeec tionmea'ns for providing al radial sweep rotating aboutzianforigin `on the screen, and optical project-irr-me '-nsf'including a heat absorber for providing-a distant imag'e'of the screen pattern, of additionalrmeans for rapidlyHcleaning-up the screen or said "skiatron, said clean-up means including, :ai second source' of sweep energy providing a sinev wave,4 mea-nsfr operative when desired tcrconnectfsaid secondI source `of sweep energy to said f deflection means,A lmeans for r removing .the heat absorber of said optical projectio n'means-to applyiheat to said fscreen, and optionally usable means-interconnecting the vaforesaid clean-up means for simultaneous operation when clean-up isidesired, wherebythefsweep, formed on a heated screen;extendsfdiametrically on' bothv sides of the orgin,-thereby increasing the speedof Aclean-up ci?fsaid.'.skiatronV f 'Y 5. The combination with alskiatron projectioncsystem incl 'ding a skiatron type-tube; a deflection# meansfor :providing-a radial' sweep rotating:about an'origin onwthe screen, an optical projection means including a -heat absorber ioriwproviding a rdistant image of the screenpattern, means for focusing the electron beam of said ;y slriatrongf-y a :source 'of anode voltage for' the iirstfaanode-'of said-fskiatron, means for biasing the.;grid or'saidskiatron, and means for gating thefcathodeofsaid skiatron, of additional means for rapidly.-.cleaninguptthe screen of said-skiatrDn,f-.sa id clean-up-means including, a `second sourcev'oi sweepA energy a sine wave; means operativawhen desired to connect said second source :ofi sweep energy 'to said deilection means, means for .deocusing said electron beam, y the heat absorber of said optical projection rmeans to apply heat lto said screen, means for removing anode gating voltage, means f-ior, intensifying' said electron beam, means for ,removing said `cathode gating means, andV optionallyusable A meansl interconnecting all or the aforesaid clean-up means n operationrlwhen clean-up is desired, whereby the sweep, formedv by an intensified and defocused electronbeam on a heated screen, extends `diametrically on both sidesv "of the lorigi'n,therebyv increasingjthe speedof Y'clean-'up of 'said 'skiatromv I5 said'fscreen,"meansfforapplyingapotentialstosaid the operating potentials of said tube to produce an intensified defocused beam, applying a sinusoidal sweep voltage to provide electron bombardment of said screen, and applying heat energy to said screen.

ing heat energy to said screen.

9. Apparatus applies heat energy and electron bombardment n to said scree 10. In a dark trace cathode ray projection system including a skiatron type tube, deection ap- HARRY c. KELLY.

REFERENCES CITED The following references yare of record in the le of this patent:

UNITED STATES PATENTS Number Re. 22,734 2,276,359

Number Name Date Rosenthal Mar. 19, 1946 Von Ardenne Mar. 17, 1942 FOREIGN PATENTS Country Date Great Britain May 26, 1941

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