US2607900A - Cathode-ray tube - Google Patents

Description

Aug. 19, 1952 M. R.' SCHUHE 2,607,900

CATHODE-RAY TUBE Filed NOV. 5. 1949 INVENTOR ,MlLToN R. scHuLTE Patented Aug. 19, 1952 i UNITED- STATES PATENT -CATHODE-RAY TUBE] MiltonV R. Schulte, Basking Ridge, N. J., assigner 4to Tung-Sol Lamp Works,'Inc`., Newark,N.-J., Y i i g.

a corporation of Delaware Application November s, 1949, serial No. 125,271

4 Claims. (Cl. 313-471) I This invention relates to cathode ray picturev tubes usedin television.

There is at present in the commercial eld the return cathode ray tube credit policy of guaranteeing twelve or eighteen months of service to customers some of whom may in this time actually use the tube for a comparatively small num- 'ber of hours while others such, for instance, as

tavern keepers, are likely to use the tube many times longer in the same interval.

This credit policy presents a serious problem to the cathode ray tube manufacturer and the television set manufacturer since neither of them at present has any accurate method of determining whether a cathode ray tube has actually been operated the intended guaranteed actual service 4ray tube of the above indicated character which can be produced by the manufacturer at a cost of only a few cents more at most than the present cost of cathode ray tubes.

Further objects of the invention will hereinafter appear.

For a better understanding of the invention reference may be had to the accompanying drawings forming a part of this application, wherein Fig. 1 illustrates schematically a conventional cathode ray picture tube embodying the invention;

Fig. 2 is a perspective view of the exhaust end of the cathode ray tube shown in Fig. 1 with certain parts broken away;

Fig. 3 is a similar perspective View of a modication;

Fig. 4 is a similar perspective View of another modification; and

Fig. 5 is a similar perspective view of another modification.

Referring to Fig. l of the drawings I have illustrated my invention as embodied in a conventional'cathode ray tube having a gun part I, a picture screen part 2 and a flaring casing part 3 between the inner end of the gun part I and the screen part 2. v

In the particular embodiment of Fig. 1 the exhaust tube for the cathode ray tube is indicated at II and in that embodiment I-have illustrated ,55 my invention vas being locatedV at least'in part in this exhaustjtube.) VThe indicating` part of the invention is designated by the numeral Sand this is devised to indicate accurately within small tolerances when the cathode ray tube has had a Vnormal number of lifek expectancy hours of burning or operation' as. for example, the intended guaranteed hours, under the present credit policy mentioned above.

In this embodiment of the invention the indicator 5 is an electrically heated filament operating either in the high vacuum of the cathode ray tube or in a high vacuum in its ownmin'iature container. It is designed and pre-life tested to burn out at the expiration of the normal number of life expectancy hours of the actual energization of the cathode ray tube. This electrically heated filament 5 in practice may be designed so as accurately to indicate this period of actual use or energization of the cathode ray tube within plus or minus ten ,(10%) percent. e

The filament 5 must'be incorporated inthe cathode ray tube in al manner .to be energized wherever the cathode'ray tube is connected in circuit by energization preparatory to operation and during operation. For this purpose the lament is provided with electrical conductors 6 and 'I which in the particular embodiment shown directly carry the filament 5 at one end and are mechanically held in spaced'relation byv an insulating bead 8 of any suitable character. The iilament- 5 may thusbe energized through the electrical conductors 6 and'l by its own electrical energy source as, for example, a battery, omitted for convenience in illustration, with thev cathode ray tube being provided with suitable leading in connections to energize the filament 5.

' With a view to minimizing expense in cathode Aray tube manufacture I prefer however to energize the electrically heatedlament 5 fromconventional terminals already'provided in the cathode ray tube as, Yfor example, the terminals I0 and II leading in from the transformer vor other supply source for the/tube lament. This connection with this source has'the additionalk advantage that the lament 5 is energized bythe same source and at the `same voltage that the cathode heating filament is energized, thel electrical conductors ofthe latter being designated in Fig. 2 by the numerals I2 and I3. The energization of the filament 5 isftherefore assured at each energization of the cathode ray tube and always in circuit during the energization of the tube and by reason of its special design and construction and operation in a high vacuum it will -burn out at or approximately at the normal vnumber ofr guaranteed life expectancy hours of the cathode rayv tube. This can be depended upon is understood that instead of one filament Ythere may be multiple laments connected in parallel across the energized leads 6 and 1. For instanceV 4 ity and also since it is disposed so far away from the screen with the gun mechanism disposed therebetween. If desired a metal or mica shield may be interposed between the indicator and the body of the tube to reduce the light passing to the main body of the tube. I have indicated schematically Vin Figs. 2 and 3 such a shield 3U.

In the embodiment of Figs. 4 and 5 the containers 2I and 25 may be darkened so as not to give out any ambrient light. This invention has the added advantage that the abuse of high line voltages which reilect on the life of the cathode Vray .tube would also reflect on the life of the life in Fig. 3 I have illustratedmultiple `filaments Y,

connected across the lead wires 6 and I and vin this particular embodiment I have illustrated two.,

such laments I5 and I6. These iilaments I5'and I6 may be if desired designed and pre-life tested either to burn out lafter the same number of hours of energization or after different hours 0f energization. If the former lthjetwoilfflfments will guard against a Ararely occasional bad lament indicatoror short life indicator indicating ya false life history to the cathode ray tube 'since 'both laments must fail in order to indicate the full normal number of .life expectancy hours of the cathode ray tube. In this embodiment of Fig. 3

the laments I5 and VI6 are also disposed within theexliaust tube 4 and are operated in the Ahigh Yvacuum of the cathode ray tube.

In ,the vembodimentof Fig. 4 I have illustrated the life expectancy indicating `filament v2i) as ernbodied inits ownminiature housing or container 2I, the latter being-supported in any suitable manner at the exhaust end of lthe cathoderay tube. The housing .or container 21 may be ,oi any -sh'ape desired and in the Vparticular' embodiment shown it assumes Ytheshape of a miniature tipless lamp bulb. The housing or container 2l may be exhausted to the high vacuum required for accurate indication o-f the lament .20 or if desired it may bey open at .oneendso as to `permit theoperationof ythe"filament `2i] Yat the high AVacuum of the cathode ray tube.

Inthe embodiment of Fig. 5 the life expectancy indicating lament 5A is suitably mounted in a capsule or short tube 25 having either .or both ends open to the high ,vacuum-'of the cathode ray tube. This capsulelor tube ,25 maybe mounted in any suitable manner, the particular mounting forming no part of lthe present invention.

'Ihusvby this invention the lnecessity for the expensive Vand onerous credit .returntube Ypolicy may be dispensed with or its complications and .uncertainties obviated. For instance, on the return of a cathoderay tube .to a set manufacturer or tube manufacturer bythe set owner, it may be accurately `and quickly determined whether the cathode ray tube has in fact operated the `normal number of life expectancy hours as, forinstance, by visual or other suitable testing ofthe indicating filament or laments-in the'cathode ray tube for remaining life thereof. Further, the indicator is visible tothe Set owner and he can be instructed not to claim vcrediton tubes with Yunlighted indicators, thus saving him the expense of returning a tube credit. Y Y

The burning-out of the indicatorrlaments does not *prevent the lfunctioning of the cathode Y,ray tubefor any hours ofthe remaining life the tube may be capable of producing. The( glowingofthe indicator filament, the latterbeingJrv disposed at Aon which he vwill -not receive lthe exhaust end of the tube will `not interfere with the production o fthe pictureon theftube screen since the filament is of miniature Vcapac indicating filaments. But the processing voltages required on the -tube during manufacture would not affect the indicator life because it could be connected parallel to the tube filament in the base vof the tube even tho it had been sealed into the tube itself. i

Iclaim: Y

l. VThe combination with. acathode ray tube having a cathode heating 'filament Yand support leads therefor, of .a second filament lhaving a predetermined life disposed within thecathode Aray .tube and Vconnected .acrossand .supported .by

the `Support leadsl fertile heating mament 'Said secondnlament servingto indicate when the tube has operated a vpi'redetervrnined number of hours.

2. 'The combination .aQQordin'g to `claim 1 wherein said second filament is disposed in the .exhaust end of the tube 'and theglow therefrom when energizedis visible Without 4destruction of thetube.

3. The combination with ,a Cathode ray ftube having a cathode heatii'ig-larnent and. a sealed off exhaust tube at one end thereof, of meansvf'o'r indicating when the tubev has operated'apre- .determined ,number .of hours,- said 'means (com.- prifsing a filament having, apredetermined vlife kdisposed within theexhaust tube and electrically vthe tube andto permit functioning of. the tube yindependently of vthe condition-of said .filament whereby proper ,functioning of lthe tube afterrexpiration of llife of the lament is-an indication that the tube has operated at least said predetermined number of hoursanL conversely, energization oft-the filament -when the ltube .fails to function is an indication-that the tube has YVfailed prior to said predeterminednumber of hours of operation. Y MILTONY n, SCHULTE.

REFERENCES einen The following references are of reco'rd'inxthe fileof this patent:

' UNITED; STATES rPAiiNrs

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