US3333134A - Shadow mask frame with curved supporting flange paralleling screen surface - Google Patents

Shadow mask frame with curved supporting flange paralleling screen surface Download PDF

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Publication number
US3333134A
US3333134A US374588A US37458864A US3333134A US 3333134 A US3333134 A US 3333134A US 374588 A US374588 A US 374588A US 37458864 A US37458864 A US 37458864A US 3333134 A US3333134 A US 3333134A
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US
United States
Prior art keywords
shadow mask
frame
screen
flange
electrode
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
US374588A
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English (en)
Inventor
Robert C Demmy
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.)
RCA Corp
Original Assignee
RCA Corp
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 RCA Corp filed Critical RCA Corp
Priority to US374588A priority Critical patent/US3333134A/en
Priority to GB21412/65A priority patent/GB1089154A/en
Priority to DER40807A priority patent/DE1272966B/de
Priority to DK289465AA priority patent/DK119214B/da
Priority to FR20018A priority patent/FR1436439A/fr
Priority to ES0314044A priority patent/ES314044A1/es
Priority to AT528765A priority patent/AT258367B/de
Priority to BE665324A priority patent/BE665324A/xx
Priority to NL656507565A priority patent/NL144768B/xx
Application granted granted Critical
Publication of US3333134A publication Critical patent/US3333134A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/06—Screens for shielding; Masks interposed in the electron stream
    • H01J29/07—Shadow masks for colour television tubes
    • H01J29/073—Mounting arrangements associated with shadow masks

Definitions

  • Shadow mask cathode ray tubes usually comprise a mosaic screen of phosphor dots, electron gun means for exciting the screen, and a shadow mask electrode interposed between the gun and screen.
  • the shadow mask electrode usually includes a thin, multi-apertured sheet of metal disposed adjacent to, coextensive with, and substantially parallel to the mosaic screen, with the apertures thereof positioned in a systematic relationship with dots of the screen.
  • a mask electrode In herein describing a mask electrode as being parallel to the phosphor screen, it is not intended to exclude a mask-screen spacing relationship which varies from parallelism by a controlled amount for the purpose of obtaining a desired register of the electron beams on the phosphor dots.
  • the mosaic screen and the shadow mask electrode are generally rectangular with rounded corners and outwardly bowed sides.
  • the major surfaces of the screen and mask electrode are curved, e.g., approximately spherically curved.
  • such a mosaic screen and shadow mask electrode will hereinafter be referred to simply as rectangular and curved, or domed.
  • One form of prior art rectangular, domed shadow mask electrode is of the one-piece type.
  • Such an electrode comprises a thin metal sheet whose central portion is domed and multi-apertured and whose peripheral portion is shaped to provide a somewhat stiffened rim section.
  • Another form of prior art rectangular, domed shadow mask electrode comprises a domed, multi-apertured, thin metal sheet mounted across a considerably heavier rectangular frame.
  • the frame is formed by a deep-drawing process.
  • the frame has an L-shaped cross-section with two flanges perpendicular to each other.
  • One flange of the L extends toward the screenand has its edge contoured to generally conform thereto.
  • the other flange of the L is substantially planar. Consequently, the width of the contoured flange varies along the length of the frame, thus giving the frame a non-uniform cross-section.
  • Both the'one-piece mask electrode and the prior art two-piece mask electrode with the deep-drawn, variable cross-section frame are subject to undesirable dimensional changes due to heating caused by electron bombardment.
  • the one-piece electrode because of its small mass, exhibits a fluctuating distortion during operation of the tube when the displayed image changes back and forth between a dark scene to a light scene.
  • the prior art two-piece mask electrode although relatively free from such temperature fluctuations, becomes substantially distorted to an equilibrium during the operation because of the non-uniformity of the frame cross-section. This distortion, in turn, results in a distortion of the multi-apertured sheet metal masking member. Either type of distortion may adversely affect the color purity of the image displayed on the screen.
  • the one-piece mask electrode because of its small mass and thin-section rim, has insuificient mechanical rigidity if, in accordance with preferred practices, it is detachably mounted on a plurality of studs fixed to the Patented July 25, 1967 "ice tube envelope to permit quick removal of the mask electrode during manufacture.
  • a shadow mask electrode In a shadow mask cathode ray tube having a domed, rectangular phosphor screen, a shadow mask electrode according to the invention comprises a rectangular frame of relatively thick material and a relatively thin multiapertured sheet metal masking member mounted thereacross.
  • the frame has an approximately L-shaped crosssection whose shape and size are substantially uniform along the length of the frame.
  • the four sides of the rectangular frame are curved so that they are substantially parallel to the phosphor screen.
  • the multi-apertured, sheet metal masking member is domed to also generally conform to the curvature of the screen.
  • FIG. 1 is a longitudinal view partially in section of a shadow mask color cathode ray tube embodying the invention
  • FIG. 2 is a plan view of the shadow mask electrode of the tube of FIG. 1 with a part broken away;
  • FIGS. 3 and 4 are sections taken respectively along lines 3--3 and 44 of FIG. 2.
  • a cathode ray tube 10 includes an envelope 12 having a central longitudinal axis A-A.
  • the envelope 12 comprises a shallow bowl-like faceplate panel 14 sealed by a frit seal 18 at its open end to a mating open end of a funnel member 16.
  • the faceplate panel 14 comprises a rectangular, domed, faceplate 20 and a peripheral side-wall 22.
  • a domed, rectangular mosaic luminescent screen 26 comprising a multiplicity of elemental dot-like deposits of different color-emitting phosphors is disposed on the internal surface of the faceplate 20.
  • the screen 26 may be aluminized according to known techniques.
  • a shadow mask electrode 28 is disposed adjacent to, substantially co-extensive with, and approximately parallel to the mosaic phosphor screen 26.
  • the shadow mask electrode 28 comprises a domed, rectangular multi-apertured sheet metal masking member 30 mounted across a rectangular frame 32.
  • a plurality of (e.g., four) electrode support studs36 extend from the internal surface of the panel side-wall 22 at locations nearly midway between the four corners thereof.
  • A- plurality of leaf spring support straps 40 are fixed at their one ends to the shadow mask electrode frame 32.
  • the support straps 40 are provided with suitable apertures near their other (free) ends into which the support studs 36 are received so as to provide a detachable, readily removable and replaceable shadow mask electrode 28 within the panel 14.
  • the spring support straps 40 are such that their apertured free ends may be depressed toward the frame 32 to permit the shadow mask electrode 28 to be mounted onto or removed from the studs 36. Such mounting of the mask electrode 28 is useful to permit quick removal and remounting of the mask electrode 28 during the manufacture of the mosaic phosphor screen 26 in accordance with known screening practices.
  • An electron gun assembly 42 is disposed within the neck portion of the funnel member 16.
  • the gun assembly 42 is adapted to project a plurality of electron beams through the apertures of the masking member 30 and onto the mosaic phosphor screen 26.
  • the frame 32 comprises an endless strip of metal formed in a generally rectangular shape having two long side lengths 44 and two short side lengths 46.
  • the strip has a generally L-shaped cross-section which is of substantially uniform size along the strip.
  • the L is oriented with a transverse flange 48 extending inwardly toward the axis AA from the rear edge of an axial flange 50 extending toward the screen 26.
  • the cross-sectional uniformity of the frame 32 results in more uniform thermal expansion characteristics than exhibited by prior art deep-drawn, variable cross-section frames. Accordingly, with the frame 32 there is less undesirable distortion of the masking member 30 than is the case with prior art deep-drawn frames.
  • Each of the four sides of the rectangular frame 32 is bowed both outwardly (FIG. 2) away from the central longitudinal axis AA of the tube and along (FIGS. 3 and 4) the axis AA toward the phosphor screen 26.
  • the bow of the four sides 44 and 46 of the rectangular frame is such as to dispose the forward (distal, or remote from the gun) edge 51 of the axial flange 50 substantially parallel to the phosphor screen 26, i.e., the curvature of the frame sides 44 and 46' conform generally to that of the faceplate 20.
  • the transverse flange 48 is non-planar.
  • the transverse flange 48 is formed at an acute angle 0 to Y the axial flange 50 so that the flange 48 is approximately parallel, that is its major surfaces are parallel, to the phosphor screen 26.
  • transverse flange 48 is substantially parallel to'the phosphor screen 26 rather than perpendicular to the axis AA.
  • One function of the transverse flange 48 is to shadow the inner surface 52 of the axial flange 48 from electrons which would otherwise strike the inner surface 52, be deflected therefrom, pass through the apertures of the masking member 30 and produce undesirable screen excitation.
  • the transverse flange 48 By making the transverse flange 48 parallel to the phosphor screen 26, and thereby more nearly perpendicular to the electron beam path, the flange need not be as wide to completely shadow the axial flange 48 as it would have to be if it were perpendicular to the axis AA. Accordingly, the transverse flange enables the provision of a lighter weight frame 32 and an attendant cost saving on material.
  • the frame 32 is of considerably thicker material than the masking member 30. It may be as much as about or more times as thick.
  • the frame has been made of 0.093 inch thick material whereas the masking member has been made of 0.006 inch thick material.
  • a relatively thin masking member 30 is very desirable from a practical standpoint because it minimizes electron interception by the side walls of the apertures therein.
  • the provision of a relatively thick, massive frame is highly desirable so as to provide a good heat sink to stabilize the operational temperature of the shadow mask electrode 28 and prevent temperature fluctuations and .attendant dimensional fluctuations of the thin masking member 30.
  • the frame 32 with these combined advantages can be spherical surface to desirably shape it to accept the domed masking member 30.
  • This fabrication method automatically provides the desired parallel relationship between the transverse flange 48 and the phosphor screen 26.
  • a cathode ray tube comprising: an envelope including a rectangular faceplate having a substantially spherical concave internal surface disposed perpendicularly to a central tube axis, a mosaic phosphor screen disposed on said surface, electron gun means for projecting electrons onto said screen, and a a domed, rectangularshadow mask electrode disposed between said screen and said gun means,
  • said electrode comprising a rectangular frame and a rectangular multi-apertured sheet metal masking member mounted across said frame, said frame comprising an endless strip of metal having a substantially uniform L-shaped cross-section,
  • one of the flanges of the L having its major faces spherically curved and disposed substantially parallel to said concave faceplate surface
  • said multi-apertured masking member being curved with a convex surface thereof facing said concave faceplate surface and being attached to the screen edge of said other flange,
  • said flanges having a thickness many times the thickness of said multi-apertured masking member and a plurality of mask mounting means connected between said other flange and said faceplate adjacent to said spherical internal surface.

Landscapes

  • Electrodes For Cathode-Ray Tubes (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US374588A 1964-06-12 1964-06-12 Shadow mask frame with curved supporting flange paralleling screen surface Expired - Lifetime US3333134A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US374588A US3333134A (en) 1964-06-12 1964-06-12 Shadow mask frame with curved supporting flange paralleling screen surface
GB21412/65A GB1089154A (en) 1964-06-12 1965-05-20 Shadow mask colour cathode ray tube and method
DER40807A DE1272966B (de) 1964-06-12 1965-06-05 Lochmasken-Farbbildroehre und Verfahren zu ihrer Herstellung
FR20018A FR1436439A (fr) 1964-06-12 1965-06-09 Tubes à rayons cathodiques à masque perforé pour la télévision en couleurs
DK289465AA DK119214B (da) 1964-06-12 1965-06-09 Katodestrålerør og fremgangsmåde ved fremstilling af en skyggemaskeelektrode til dette.
ES0314044A ES314044A1 (es) 1964-06-12 1965-06-10 Un dispositivo de tubo de rayos catodicos.
AT528765A AT258367B (de) 1964-06-12 1965-06-11 Kathodenstrahlröhre, bestehend aus einem Kolben mit rechteckiger Frontplatte und Verfahren zu deren Herstellung
BE665324A BE665324A (xx) 1964-06-12 1965-06-11
NL656507565A NL144768B (nl) 1964-06-12 1965-06-14 Kleurentelevisieweergeefbuis.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US374588A US3333134A (en) 1964-06-12 1964-06-12 Shadow mask frame with curved supporting flange paralleling screen surface

Publications (1)

Publication Number Publication Date
US3333134A true US3333134A (en) 1967-07-25

Family

ID=23477473

Family Applications (1)

Application Number Title Priority Date Filing Date
US374588A Expired - Lifetime US3333134A (en) 1964-06-12 1964-06-12 Shadow mask frame with curved supporting flange paralleling screen surface

Country Status (9)

Country Link
US (1) US3333134A (xx)
AT (1) AT258367B (xx)
BE (1) BE665324A (xx)
DE (1) DE1272966B (xx)
DK (1) DK119214B (xx)
ES (1) ES314044A1 (xx)
FR (1) FR1436439A (xx)
GB (1) GB1089154A (xx)
NL (1) NL144768B (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4244755A (en) * 1979-09-21 1981-01-13 Corning Glass Works Process for stabilizing metallic cathode ray tube parts
EP0439884A1 (en) * 1990-01-31 1991-08-07 Samsung Display Devices Co., Ltd. Shadow mask frame for prevention of halation
CN1074578C (zh) * 1996-08-05 2001-11-07 三星电管株式会社 荫罩框架的制造方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2806162A (en) * 1954-08-18 1957-09-10 Rca Corp Cathode-ray tube
US2897392A (en) * 1956-02-09 1959-07-28 Zenith Radio Corp Color television tube mask and frame assembly
US2906904A (en) * 1956-04-17 1959-09-29 Westinghouse Electric Corp Cathode ray tube
US2922063A (en) * 1956-11-07 1960-01-19 Sylvania Electric Prod Target assembly for cathode ray tubes
US2961560A (en) * 1955-05-06 1960-11-22 Columbia Broadcasting Syst Inc Color picture tube

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2806162A (en) * 1954-08-18 1957-09-10 Rca Corp Cathode-ray tube
US2961560A (en) * 1955-05-06 1960-11-22 Columbia Broadcasting Syst Inc Color picture tube
US2897392A (en) * 1956-02-09 1959-07-28 Zenith Radio Corp Color television tube mask and frame assembly
US2906904A (en) * 1956-04-17 1959-09-29 Westinghouse Electric Corp Cathode ray tube
US2922063A (en) * 1956-11-07 1960-01-19 Sylvania Electric Prod Target assembly for cathode ray tubes

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4244755A (en) * 1979-09-21 1981-01-13 Corning Glass Works Process for stabilizing metallic cathode ray tube parts
EP0439884A1 (en) * 1990-01-31 1991-08-07 Samsung Display Devices Co., Ltd. Shadow mask frame for prevention of halation
CN1074578C (zh) * 1996-08-05 2001-11-07 三星电管株式会社 荫罩框架的制造方法

Also Published As

Publication number Publication date
BE665324A (xx) 1965-10-01
DE1272966B (de) 1968-07-18
DK119214B (da) 1970-11-30
NL6507565A (xx) 1965-12-13
GB1089154A (en) 1967-11-01
ES314044A1 (es) 1966-03-16
FR1436439A (fr) 1966-04-22
AT258367B (de) 1967-11-27
NL144768B (nl) 1975-01-15

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