US2146017A

US2146017A - Cathode ray apparatus

Info

Publication number: US2146017A
Application number: US732566A
Authority: US
Inventors: Harley A Iams
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1934-04-28
Filing date: 1934-06-27
Publication date: 1939-02-07
Anticipated expiration: 1956-02-07

Description

Feb. 7, 1939. H. A. IAMS CATHODE RAY APPARATUS Filed June 27, 1934 WTTO/P/VEK retested Feb. 7, 1939 Orang No In 7 Radio Corporation of America, a corporation of BarlcyAIamaliast Delaware Application June 27, 1924, Serial No. 132,566

13 Claims. (01. 250-102) My invention relates to improvements in cathode ray apparatus.

In the development of cathode ray apparatus for television communication, one of the problems has been to develop a ray of electrons and cause it to come always to a sharp focus on the screen within the tube without interfering action .due to the electrical fields developed for deflecting the ray. In one form of cathode ray apparatus proposed, and embodying a pair of complementary plates supported within the tube for deflecting the ray in one direction, dimculty has been encountered due, particularly, to defo'cusing of the ray on account of interfering action between the focusing field and the electrostatic deflecting field.

In such apparatus, furthermore, it has been proposed to interpose a relatively long focusing cylinder between the inside deflecting platesand the electron gun. This construction and arrangement necessitates a relatively great distance between the screen and the end of the electron gun, which makes conditions that much more unfavor-' able for causing the ray of electrons to come to a sharp focus on the screen.

With the foregoing in mind, it is one of the objects of my invention to provide an improved construction of cathode ray apparatus of the character referred to wherein inside deflecting plates can be used to advantage without interference with the focusing field, and wherein the di mensions can be such as to bring the end 'of the electron gun substantially closer to the screen than has been possible in the various constructions' proposed heretofore.

Other objects and advantages will hereinafter appear. I

In accordance with my invention, a disc provided with a central aperture is supported between the inside deflecting plates and the output end of i the electron gun, and cooperates with the latter to develop a focusing field. The disc, besides serving as means for causing the ray of electrons to come to a sharp focus on the screen, is also effective as a shield to prevent interfering action between the electrostatic deflecting field and the focusing field.

My invention resides in the construction of the character hereinafter described and claimed.

For the purpose of illustrating my invention, an embodiment thereof is shown in the drawing,

wherein Figure 1 is an elevational sectional view of a cathode ray tube for television reception, constructed and operating in accordance with my invention; and

assignmto Figs. 2 and 3 are diagrammatiadragnientary, sectional views, illustrative of the. principle 40f operatloninl ig.l., M

In the drawing, thetaaaoejttaeat toastsnates a tube provided ,with'a. fluorescent; screen 5 l2 and with means inthe. form of an electron gun M for developing a ray IQ of. electrons anddirecting the ray toward the ;screen.-,.x= Cylindrical as shown, and are heldtogetherby wiresections 22 and insulating glass beads 24. 1A: collar 26 of insulating material is interposedbetween andis recessed to receive the adjacent ends ofithe cylinders l8 and to maintainalignmentthereof.

The electrode l8 serves as a' grld .by'which the intensity of the ray can be varied .The. electrode 20 serves to accelerate the .electrons towardthe screen l2 and also to cause therayto come'tora sharp focus on the screen.

electrodes l8 and 20 are supported inzalignment The electrodes and 20, are providedwith'the apertured discs 28 electrons must pass.

and 3,0 throughwhich. the A cathode 32 provides olooijoe ofuelectronsrj The ray i6 is deflectedvertically byapairgqi' 1., plates 34 supportedfrom -theenduof thegunby 2 wire sections 36 and, and ,insulatlng lass-beads 40. The wire sections 38-extend throughopenings in a disc 42 and into an insulating collar 44 fitted on the end ofthe cylindrical electrode 20. V

The disc 42 is providedwitha central aperture I 46 and with a flange 48 which has a snug fit on the collar 44.

The ray I6 is deflectedhorizontallyby electromagnetic coils 50 through which a saw-tooth current wave at the desiredfrequency iscaused-to PBSS. .1

The electrode 20 and the disc.4 2. are supplied with the operating potentials,'fas indicated; ,1.

In operation, an electrostatic field, indicated at 52 in Fig. 2, is developed between the disc 42 and the open end ofthe cylindrical electrode 2U,"the lines of this fleld terminatingatfthis disc and being effective to cause the electrons tolconvergc as they pass through the aperture andto come to a sharp focus on the'sci'een 125' A suitable voltage wave is applied tof the plates 34 by connections 54 to develop an electrostaticdeflecting field betweentheseplatess The edge as of the disc 42 isinrclose-proxiniity to the wall of thetube l0, and the flange 48-ex-:- tends well back of and embraces the tin; of the electrode 20.- with this arrangement,- and since the lines ofthe focusing fleld indicated at-ii terminateat the surface r the disc 42, the latte r is eflective as a shield to prevent interfering acscreen if.

In Fig. 3, the reference numeral I. designates the relatively long-cylindrical electrode used in the various constructions proposed heretofore to, focus the ray of electrons on the screen, and corre p quired operating the disc 42 .in Fig. 2. with the repotentials applied to the focusing electrode 6| and the electrode II, an electrostatic field, indicated at 82, is developed. 'Ihe lines of this field diverge as represented in the drawing, and for this reason are not as elective in focusing the ray as the construction in Figs. 1 and 2. Furthermore, some of the lines of force in the prior construction as shown in Fig. 3 extend entirely through the electrode 80' and mix with the lines of the electrostatic deflecting field be tween the deflecting plates 64. This action causes some degree of defocuslng of the ray. Inthe construction shown in Fig. 3, further, the relatively great length of the focusing tube Ill requires that the tip of the electron gun be Just that much further removed from the screen. Under the same operating conditions, therefore, the ray in the construction shown in Fig. 3 does not come to as sharp a focus on the screen as is the case in my improved construction in Figs. 1 and 2.

From the foregoing it will be seen that I have provided improved cathode ray apparatus in which provision is made for the use of inside defleeting plates without producing conditions to cause interfering action with the focusing fleld,'

and that this is accomplished by a construction which permits location of the tip of the electron gun closer to the screen'than has been possible in the various constructions proposed heretofore.

,While but one embodiment of my invention has been disclosed, it will be understood that various modifications, within the conception of those skilled in the art, are possible without departing from the spirit of my invention or the scope of the I claim as my invention:

l. Cathode ray apparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray at said screen, said ray-developing means comprising a plurality of aligned cylindrical electrodes, a centrally-apertured disc disposed between said screen and said ray-developing means and in close proximity to the adjacent end of said means, ray-deflecting means comprising a pair of complementary plates supported within said tube and between said disc and said screen, connections for applying operating potentials to said plates to develop an electrostatic deflecting field between the same, and connections for applying operating potentials to said disc and the adjacent cylindrical electrode to develop anelectrostatic field between the disc and saidelectrode for bringing the electrons ofthe ray to a focus in substantially the plane of said screen, the edge of said disc being in close proximity to the wall of said tube whereby'said disc is effective as a shield to auspiv prevent interfering action betweenthe deflecting and focusing fields. a

3. Cathode ray' apparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray at said s'creen. the output end of said means being in' the form of an elong ted n-ended cylinder from which the electrons issue, raydeflecting means comprisinga pair of complementary plates "supported within said tube and between said screen and the output end of said means, a centrally-apertured disc supported from the output end of said ray-developing means and disposed between the latter and said plates, and connections for applying operating potentials to said elementsto develop a focusing field between said disc and said cylinder and a deflecting field between said plates, the edge of said disc being in close proximity to the wall of said tube to shield the focusing field from the deflecting field.

3. Cathode rayapparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray. at said screen; a centrally-apertured disc disposed between said screen and said ray-developing means and in close proximity to the'adjacent end of said means, said disc being provided with a flange embracing said end of said means, and connections for applying operating potentials to said disc and said end of said means to develop an electrostatic field between the same to bring the electrons of the ray to a'focus in substantially the plane of said screen.

4. Cathode ray apparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray at said screen, the output end of said means being in the form of an elongated open-ended cylinder from which the electrons issue, ray-deflecting means comprising a pair of complementary plates supported 'within said tube and between said screen and the output end of said means, a centrally-apertured disc supported in axial align ment with the output end of said ray-developing means and disposed between the latter and said plates, and connections for applying operating potentials to said elements to develop a focusing fleld between said disc and said cylinder and a deflecting field between said plates, said disc being provided with a flange embracing the output end of said ray-developing means to shield the focusing field from the deflecting field.

5. Cathode ray apparatus comprising a tube envelope, a luminescent material coating one end interior surface of the envelope, means positioned within the tube envelope at the opposite end from the coating for developing a ray of electrons and directing the ray at the coating, an apertured disc electrode positioned within the, tube envelope intermediate the ray developing means and the coating and substantially adjacent the ray developing means and extending-substantially to the wall of said envelope, an annular electrode having one edge thereof attached to said disc electrode and the opposite edge thereof surrounding substantially the ray developing means, and

ray deflecting electrodes positioned intermediate the apertured disc electrode and the luminescent coating; 7

6. Cathode ray apparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray at said screen, the output end of said means being in the form of an elongated open-ended cylinder from which the electrons issue, ray-deflecting armor-r meansc mpri lnsa p ir cfjccmnl menta rnl sup rted; "within; said; tube and between, ,7 said screen and the outputqend .pf saidgmeans, a cena -apert rcd- ;disc,supp0rted in axial a nment with the outputendoi' ,SBJGIIEY-QGYCIOMDB meansand disposed between the latter and said plates,- and connections for applying operating potentials to said elements to develop a focusing field between said disc and said cylinder and a deflecting field between said plates. said disc being provided with a flange embracing the output end of said ray-developing means to shield the focusing field from the deflecting field.

'7. Cathode ray apparatus comprising a tube having a luminescent screen and means for developing a beam of electrons and directing the beam at said screen, said beam developing means including an electron emitting cathode and a tubular anode, a control electrode interposed between the tubular anode and the electron emitting cathode ior controlling the intensity of the developed electron beam, electron beam deflecting plate electrode members interposed between the said anode and the'screen, and an apertured disc beam accelerating electrode element adapted to be maintained at a high potential relative to the anode, said apertured member being located between the anode and the deflecting plates and adapted to form with the anode electrode a focusing means to focus the developed electron beam to a sharply defined spot upon the screen,

. said beam accelerating electrode having provided thereon a cylindrical flange element of a diameter greater than that of the tubular anode and surrounding and enclosing at least a portion of the end of said tubular anode toward said screen.

8. Cathode ray apparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray at said screen, said ray-developing means comprising a plurality of aligned cylindrical electrodes, a centrally-apertured disc disposed between said screen and said ray-developing means and in proximity to the adjacent end of one of said cylindrical electrodes, ray-deflecting means comprising a pair of complementary plates supported within said tube and between said disc and said screen, connections for applying operating potentials to said plates to develop an electrostatic deflecting field between the same, and connections for applying operating potentials to said disc and the adjacent cylindrical electrode to develop an electrostatic field between the disc and said electrode for bringing the electrons of the ray to a focus in substantially the plane of said screen, said disc being positioned transversely of the axis of said adjacent cylindrical electrode and extending substantially beyond the periphery of said adjacent electrode towards the wall of the tube whereby saiddisc is efiective as a shield to prevent interfering action between the deflecting and focussing fields.

9. Cathode ray apparatus according to claim a 8 in which said disc is provided with an annular flange partially overlapping the adjacent end of said adjacent electrode.

10. Cathode ray apparatus comprising a tube provided with a screen and with means for developing a ray of electrons and directing the ray at said screen, the output end of said means being in the form of an elongated open-ended cylinder from which the electrons issue, ray-deflecting means comprising a pair of complementary plates supported within said tube and between said screen and the output end of said means, a cenwithin the tube envelope electrons of the developed beam normally to focus trally-apertured disc supported adjacent the output end of said ray-developing means and disposed between the latter and said plates, and connections for applying operating potentials to said elements to develop a focussing field between 5 said disc and said cylinder and a deflecting field between said plates, said disc being positioned transversely of said cylinder and extending substantially beyond the periphery thereof towards the wall of the tube.

11. Cathode ray apparatus comprisinga tube provided with a screen and with means for de-' veloping a ray of electrons and directing the ray at. said screen, the output end 0! said means being in the form of an elongated open-ended cylinder from which the electrons issue, ray-deflecting means comprising a pair of complementary plates supported within said tube. and between said screen and the output end of said means, acen-J trally-apertured disc supported adjacent the output end of said ray-developing means and disposed between the latter and said plates, and connections for applying operating potentials to said elements to develop a focusslng field between said disc. and said cylinder and a deflecting field between said plates, said disc being provided with a flange embracing the output end of said raydeveloping means to shield the i'ocussing field from the deflecting field.

12. Cathode ray apparatus comprising a tube envelope, a luminescent material coating one-end interior surface of the envelope, means positioned at the opposite end from the coating for developing a ray of electrons and directing the ray at said coating, an apertured disc electrode positioned within the tube envelope intermediate the ray'developing means and the coating and substantially adjacent the ray developing means and extending laterally beyond the peripheral boundary of the ray-developing means, an annular metal member having one end thereof attached to said disc electrode and the opposite end thereof surrounding substantially the ray developing means, and ray deflecting electrodes positioned intermediate the apertured disc electrode and the luminescent coating.

13. An electron tube comprising an envelope having a target 'element at one end thereof and an electron beam developing means at the opposite end thereof for directing a beam of electrons toward the target, said electron beam developing means comprising an electron emitting element and at least one tubular electrode member, a centrally aperture'd disc element disposed between the target and the ray developing means and in proximity to one of the cylindrical electrode elements of said ray developing means, said disc element having an outer diameter greater than that of the tubular electrode element adjacent thereto, electron beam deflecting means comprising a pair of complementary plates supported within the envelope and intermediate the disc and the target, and connections for applying 4 operating potentials to the deflecting plates to develop an electrostatic field between the said plates, connection forapplying operating potentials to said disc and cylindrical electrode elements to develop an electrostatic field between the disc and said tubular electrodes to bring the substantially in the plane of the target, and an annular electrode element of an internal diameter greater than the outer diameter of the tubular electrode element adjacent said disc element, said last named tubular member being positioned in axisl alianmentwiththeflrstnamedtnbiflar electrode elements, and havins one end thereof extend partially over the length of the adjacent tubular electrode element and the other end extendtoward said target, said tubular member element within an area of the tubular element intermediate the ends thereof and substantially at the end thereof toward said target whereby the focusing neld developed is undisturbed by said deflecting field.

- A. IAMS.